WorldWideScience

Sample records for abundance seasonal dynamics

  1. Seasonal variations in abundance, biomass and grazing rates of microzooplankton in a tropical monsoonal estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Gauns, M.; Mochemadkar, S.; Patil, S.; Pratihary, A.K.; Naqvi, S.W.A.; Madhupratap, M.

    Seasonal abundance, composition and grazing rates of microzooplankton (20–200 µm) in the Zuari estuary were investigated to evaluate their importance in food web dynamics of a tropical monsoonal estuary. Average abundances of microzooplankton...

  2. Seasonal temperature and precipitation regulate brook trout young-of-the-year abundance and population dynamics

    Science.gov (United States)

    Kanno, Yoichiro; Pregler, Kasey C.; Hitt, Nathaniel P.; Letcher, Benjamin H.; Hocking, Daniel; Wofford, John E.B.

    2015-01-01

    Abundance of the young-of-the-year (YOY) fish can vary greatly among years and it may be driven by several key biological processes (i.e. adult spawning, egg survival and fry survival) that span several months. However, the relative influence of seasonal weather patterns on YOY abundance is poorly understood.

  3. Seasonal Abundance of Aphids and Aphidophagous Insects in Pecan

    Directory of Open Access Journals (Sweden)

    Ghulam Abbas

    2012-12-01

    Full Text Available Seasonal occurrence of aphids and aphidophagous insects was monitored for six years (2006–2011 from full leaf expansion in May to leaf fall in October in “Desirable” variety pecan trees that were not treated with insecticides. Aphid outbreaks occurred two times per season, once in the spring and again in the late summer. Yellow pecan and blackmargined aphids exceeded the recommended treatment thresholds one time and black pecan aphids exceeded the recommended treatment levels three times over the six seasons. Increases in aphidophagous insect abundance coincided with aphid outbreaks in five of the six seasons. Among aphidophagous insects Harmonia axyridis and Olla v-nigrum were frequently collected in both the tree canopy and at the ground level, whereas, Coccinella septempunctata, Hippodamia convergens were rarely found in the tree canopy and commonly found at the ground level. Green lacewing abundance was higher in the ground level than in the tree canopy. Brown lacewings were more abundant in the tree canopy than at the ground level. Dolichopodid and syrphid fly abundance, at the ground level increased during peak aphid abundance in the tree canopy. Application of an aqueous solution of fermenting molasses to the pecan foliage during an aphid outbreak significantly increased the abundance of ladybeetles and lacewings and significantly reduced the abundance of yellow pecan, blackmargined and black pecan aphids.

  4. Seasonal Abundance of Aphids and Aphidophagous Insects in Pecan

    Science.gov (United States)

    Dutcher, James D.; Karar, Haider; Abbas, Ghulam

    2012-01-01

    Seasonal occurrence of aphids and aphidophagous insects was monitored for six years (2006–2011) from full leaf expansion in May to leaf fall in October in “Desirable” variety pecan trees that were not treated with insecticides. Aphid outbreaks occurred two times per season, once in the spring and again in the late summer. Yellow pecan and blackmargined aphids exceeded the recommended treatment thresholds one time and black pecan aphids exceeded the recommended treatment levels three times over the six seasons. Increases in aphidophagous insect abundance coincided with aphid outbreaks in five of the six seasons. Among aphidophagous insects Harmonia axyridis and Olla v-nigrum were frequently collected in both the tree canopy and at the ground level, whereas, Coccinella septempunctata, Hippodamia convergens were rarely found in the tree canopy and commonly found at the ground level. Green lacewing abundance was higher in the ground level than in the tree canopy. Brown lacewings were more abundant in the tree canopy than at the ground level. Dolichopodid and syrphid fly abundance, at the ground level increased during peak aphid abundance in the tree canopy. Application of an aqueous solution of fermenting molasses to the pecan foliage during an aphid outbreak significantly increased the abundance of ladybeetles and lacewings and significantly reduced the abundance of yellow pecan, blackmargined and black pecan aphids. PMID:26466738

  5. Size-based hydroacoustic measures of within-season fish abundance in a boreal freshwater ecosystem.

    Directory of Open Access Journals (Sweden)

    Riley A Pollom

    Full Text Available Eleven sequential size-based hydroacoustic surveys conducted with a 200 kHz split-beam transducer during the summers of 2011 and 2012 were used to quantify seasonal declines in fish abundance in a boreal reservoir in Manitoba, Canada. Fish densities were sufficiently low to enable single target resolution and tracking. Target strengths converted to log2-based size-classes indicated that smaller fish were consistently more abundant than larger fish by a factor of approximately 3 for each halving of length. For all size classes, in both years, abundance (natural log declined linearly over the summer at rates that varied from -0.067 x day(-1 for the smallest fish to -0.016 x day(-1 for the largest (R2 = 0.24-0.97. Inter-annual comparisons of size-based abundance suggested that for larger fish (>16 cm, mean winter decline rates were an order of magnitude lower (-0.001 x day(-1 and overall survival higher (71% than in the main summer fishing season (mean loss rate -0.038 x day(-1; survival 33%. We conclude that size-based acoustic survey methods have the potential to assess within-season fish abundance dynamics, and may prove useful in long-term monitoring of productivity and hence management of boreal aquatic ecosystems.

  6. Size-based hydroacoustic measures of within-season fish abundance in a boreal freshwater ecosystem.

    Science.gov (United States)

    Pollom, Riley A; Rose, George A

    2015-01-01

    Eleven sequential size-based hydroacoustic surveys conducted with a 200 kHz split-beam transducer during the summers of 2011 and 2012 were used to quantify seasonal declines in fish abundance in a boreal reservoir in Manitoba, Canada. Fish densities were sufficiently low to enable single target resolution and tracking. Target strengths converted to log2-based size-classes indicated that smaller fish were consistently more abundant than larger fish by a factor of approximately 3 for each halving of length. For all size classes, in both years, abundance (natural log) declined linearly over the summer at rates that varied from -0.067 x day(-1) for the smallest fish to -0.016 x day(-1) for the largest (R2 = 0.24-0.97). Inter-annual comparisons of size-based abundance suggested that for larger fish (>16 cm), mean winter decline rates were an order of magnitude lower (-0.001 x day(-1)) and overall survival higher (71%) than in the main summer fishing season (mean loss rate -0.038 x day(-1); survival 33%). We conclude that size-based acoustic survey methods have the potential to assess within-season fish abundance dynamics, and may prove useful in long-term monitoring of productivity and hence management of boreal aquatic ecosystems.

  7. Population dynamic of the swallowtail butterfly, Papilio polytes (Lepidoptera: Papilionidae in dry and wet seasons

    Directory of Open Access Journals (Sweden)

    SUWARNO

    2010-01-01

    Full Text Available Suwarno (2010 Population dynamic of the swallowtail butterfly, Papilio polytes (Lepidoptera: Papilionidae in dry and wet seasons. Biodiversitas 11: 19-23. The population dynamic of Papilio polytes L. (Lepidoptera: Papilionidae in dry and wet seasons was investigated in the citrus orchard in Tasek Gelugor, Pulau Pinang, Malaysia. Population of immature stages of P. polytes was observed alternate day from January to March 2006 (dry season, DS, from April to July 2006 (secondary wet season, SWS, and from October to December 2006 (primary wet season, PWS. The population dynamics of the immature stages of P. polytes varied between seasons. The immature stages of P. polytes are more abundance and significantly different in the PWS than those of the DS and the SWS. The larval densities in all seasons decreased with progressive development of the instar stages. Predators and parasitoids are the main factor in regulating the population abundance of immature stages of P. polytes. There were positive correlations between the abundance of immature stages of P. polytes and their natural enemies abundance in each season. Ooencyrtus papilioni Ashmead (Hymenoptera: Encyrtidae is the most egg parasitoid. Oxyopes quadrifasciatus L. Koch. and O. elegans L. Koch. (Araneae: Oxyopidae are the main predators in the young larvae, meanwhile Sycanus dichotomus Stal. (Heteroptera: Reduviidae, Calotes versicolor Fitzinger (Squamata: Agamidae, birds and praying mantis attacked the older larvae.

  8. Seasonality in insect abundance in the "Cerrado" of Goiás State, Brazil

    Directory of Open Access Journals (Sweden)

    Neuza Aparecida Pereira da Silva

    2011-03-01

    Full Text Available Seasonality in insect abundance in the "Cerrado" of Goiás State, Brazil. Many studies have provided evidence that tropical insects undergo seasonal changes in abundance and that this is partly due to alternation between the dry and rainy seasons. In the Brazilian "Cerrado" (savannah, this season alternation is particularly evident. The purpose of this work was to study the seasonal abundance of insects in a "Cerrado" area in the municipality of Pirenópolis, Goiás State, Brazil. The insects were captured fortnightly using a light trap between September 2005 and August 2006. The insects collected were separated at the order level and counted. Faunistic analysis was performed to select the predominant insect orders, a multiple linear regression to examine the relation between climatic variables (temperature and precipitation with the abundance of insects and a circular distribution analysis to evaluate the existence of seasonality in the abundance of insect orders. A total of 34,741 insect specimens were captured, belonging to 19 orders. The orders with the greatest number of specimens were Hymenoptera (8,022, Coleoptera (6,680, Diptera (6,394, Lepidoptera (6,223, Isoptera (2,272, Hemiptera (2,240 and Trichoptera (1,967, which represent 97.3% of all the specimens collected. All the orders, except for Diptera, Isoptera and Trichoptera, showed a relationship with the climate variables (temperature, and all the orders, except for Diptera, presented a grouped distribution, with greater abundance in the transition from the end of the dry season (September to the start of the rainy one (October/November. A discussion about seasonality on the abundance of the insects is presented.

  9. Nonbreeding-Season Drivers of Population Dynamics in Seasonal Migrants: Conservation Parallels Across Taxa

    Directory of Open Access Journals (Sweden)

    Anna M. Calvert

    2009-12-01

    Full Text Available For seasonal migrants, logistical constraints have often limited conservation efforts to improving survival and reproduction during the breeding season only. Yet, mounting empirical evidence suggests that events occurring throughout the migratory life cycle can critically alter the demography of many migrant species. Herein, we build upon recent syntheses of avian migration research to review the role of non-breeding seasons in determining the population dynamics and fitness of diverse migratory taxa, including salmonid fishes, marine mammals, ungulates, sea turtles, butterflies, and numerous bird groups. We discuss several similarities across these varied migrants: (i non-breeding survivorship tends to be a strong driver of population growth; (ii non-breeding events can affect fitness in subsequent seasons through seasonal interactions at individual- and population-levels; (iii broad-scale climatic influences often alter non-breeding resources and migration timing, and may amplify population impacts through covariation among seasonal vital rates; and (iv changes to both stationary and migratory non-breeding habitats can have important consequences for abundance and population trends. Finally, we draw on these patterns to recommend that future conservation research for seasonal migrants will benefit from: (1 more explicit recognition of the important parallels among taxonomically diverse migratory animals; (2 an expanded research perspective focused on quantification of all seasonal vital rates and their interactions; and (3 the development of detailed population projection models that account for complexity and uncertainty in migrant population dynamics.

  10. Local and cross-seasonal associations of climate and land use with abundance of monarch butterflies Danaus plexippus

    Science.gov (United States)

    Saunders, Sarah P.; Ries, Leslie; Oberhasuer, Karen S.; Thogmartin, Wayne E.; Zipkin, Elise F.

    2017-01-01

    Quantifying how climate and land use factors drive population dynamics at regional scales is complex because it depends on the extent of spatial and temporal synchrony among local populations, and the integration of population processes throughout a species’ annual cycle. We modeled weekly, site-specific summer abundance (1994–2013) of monarch butterflies Danaus plexippus at sites across Illinois, USA to assess relative associations of monarch abundance with climate and land use variables during the winter, spring, and summer stages of their annual cycle. We developed negative binomial regression models to estimate monarch abundance during recruitment in Illinois as a function of local climate, site-specific crop cover, and county-level herbicide (glyphosate) application. We also incorporated cross-seasonal covariates, including annual abundance of wintering monarchs in Mexico and climate conditions during spring migration and breeding in Texas, USA. We provide the first empirical evidence of a negative association between county-level glyphosate application and local abundance of adult monarchs, particularly in areas of concentrated agriculture. However, this association was only evident during the initial years of the adoption of herbicide-resistant crops (1994–2003). We also found that wetter and, to a lesser degree, cooler springs in Texas were associated with higher summer abundances in Illinois, as were relatively cool local summer temperatures in Illinois. Site-specific abundance of monarchs averaged approximately one fewer per site from 2004–2013 than during the previous decade, suggesting a recent decline in local abundance of monarch butterflies on their summer breeding grounds in Illinois. Our results demonstrate that seasonal climate and land use are associated with trends in adult monarch abundance, and our approach highlights the value of considering fine-resolution temporal fluctuations in population-level responses to environmental

  11. Factors influencing long-term and seasonal waterbird abundance ...

    African Journals Online (AJOL)

    ... influence waterbird communities include rainfall quantity and distribution, waterbird movement, breeding and moulting; anthropogenic drivers include activities such as fishing and agriculture. Results suggest that seasonal variations in resource availability influenced the waterbird community composition and abundance, ...

  12. Dynamics of Viral Abundance and Diversity in a Sphagnum-Dominated Peatland: Temporal Fluctuations Prevail Over Habitat.

    Science.gov (United States)

    Ballaud, Flore; Dufresne, Alexis; Francez, André-Jean; Colombet, Jonathan; Sime-Ngando, Télesphore; Quaiser, Achim

    2015-01-01

    Viruses impact microbial activity and carbon cycling in various environments, but their diversity and ecological importance in Sphagnum-peatlands are unknown. Abundances of viral particles and prokaryotes were monitored bi-monthly at a fen and a bog at two different layers of the peat surface. Viral particle abundance ranged from 1.7 x 10(6) to 5.6 x 10(8) particles mL(-1), and did not differ between fen and bog but showed seasonal fluctuations. These fluctuations were positively correlated with prokaryote abundance and dissolved organic carbon, and negatively correlated with water-table height and dissolved oxygen. Using shotgun metagenomics we observed a shift in viral diversity between winter/spring and summer/autumn, indicating a seasonal succession of viral communities, mainly driven by weather-related environmental changes. Based on the seasonal asynchrony between viral and microbial diversity, we hypothesize a seasonal shift in the active microbial communities associated with a shift from lysogenic to lytic lifestyles. Our results suggest that temporal variations of environmental conditions rather than current habitat differences control the dynamics of virus-host interactions in Sphagnum-dominated peatlands.

  13. Linear relationship between peak and season-long abundances in insects.

    Directory of Open Access Journals (Sweden)

    Ksenia S Onufrieva

    Full Text Available An accurate quantitative relationship between key characteristics of an insect population, such as season-long and peak abundances, can be very useful in pest management programs. To the best of our knowledge, no such relationship has yet been established. Here we establish a predictive linear relationship between insect catch Mpw during the week of peak abundance, the length of seasonal flight period, F (number of weeks and season-long cumulative catch (abundance A = 0.41MpwF. The derivation of the equation is based on several general assumptions and does not involve fitting to experimental data, which implies generality of the result. A quantitative criterion for the validity of the model is presented. The equation was tested using extensive data collected on captures of male gypsy moths Lymantria dispar (L. (Lepidoptera: Erebidae in pheromone-baited traps during 15 years. The model was also tested using trap catch data for two species of mosquitoes, Culex pipiens (L. (Diptera: Culicidae and Aedes albopictus (Skuse (Diptera: Culicidae, in Gravid and BG-sentinel mosquito traps, respectively. The simple, parameter-free equation approximates experimental data points with relative error of 13% and R2 = 0.997, across all of the species tested. For gypsy moth, we also related season-long and weekly trap catches to the daily trap catches during peak flight. We describe several usage scenarios, in which the derived relationships are employed to help link results of small-scale field studies to the operational pest management programs.

  14. The seasonal role of field characteristics on seed-eating bird abundances in agricultural landscapes

    Institute of Scientific and Technical Information of China (English)

    Emmanuel ZUFIAURRE; Mariano CODESIDO; Agustín M.ABBA; David BILENCA

    2017-01-01

    In temperate agroecosystems,avian responses in abundance and distribution to landscape attributes may be exacerbated by the coupling of natural seasons and farming practices.We assessed the seasonal roles of field WPe,field use in the surroundings,and distance from a field to the nearest woodlot on the abundance of seed-eating birds in a 225,000 km2 study area in the Pampas of central Argentina.During spring-summer and autumn of 2011-2013,we randomly selected 392 fields and used transect samples to collect data on abundance and presence of seed-eating bird species.We recorded a total of 11,579 individuals belonging to 15 seed-eating bird species.We used generalized lineal mixed models to relate bird abundance to field type,field use in the surroundings,and distance to the nearest woodlot.In spring-summer (breeding season) most bird responses were associated with their nesting requirements.Species that build their nests in trees,such as eared doves Zenaida auriculata,picazuro pigeons Patagioenas picazuro,and monk parakeets Myiopsitta monachus,were more abundant in fields closer to woodlots,whereas grassland yellow-finches Sicalis luteola,which nest at areas with tall grasses,were more abundant in fields with livestock use patches in the field surroundings.In autumn (non-breeding season),most bird responses were associated with foraging and refuge needs.The high abundance of eared doves in crop stubbles and the association of pigeons at field surroundings dominated by croplands or at crop stubbles surrounded by livestock use fields revealed the intimate association of these species to sites with high availability of food resources.In addition,both picazuro pigeons and spot-winged pigeons Patagioenas maculosa were associated with woodlots,which provide suitable roosting sites.Our results show that in temperate agroecosystems,the relationships between field characteristics and seed-eating bird abundances vary with season.

  15. The seasonal role of field characteristics on seed-eating bird abundances in agricultural landscapes

    Science.gov (United States)

    Codesido, Mariano; Abba, Agustín M.; Bilenca, David

    2017-01-01

    Abstract In temperate agroecosystems, avian responses in abundance and distribution to landscape attributes may be exacerbated by the coupling of natural seasons and farming practices. We assessed the seasonal roles of field type, field use in the surroundings, and distance from a field to the nearest woodlot on the abundance of seed-eating birds in a 225,000 km2 study area in the Pampas of central Argentina. During spring-summer and autumn of 2011–2013, we randomly selected 392 fields and used transect samples to collect data on abundance and presence of seed-eating bird species. We recorded a total of 11,579 individuals belonging to 15 seed-eating bird species. We used generalized lineal mixed models to relate bird abundance to field type, field use in the surroundings, and distance to the nearest woodlot. In spring-summer (breeding season) most bird responses were associated with their nesting requirements. Species that build their nests in trees, such as eared doves Zenaida auriculata, picazuro pigeons Patagioenas picazuro, and monk parakeets Myiopsitta monachus, were more abundant in fields closer to woodlots, whereas grassland yellow-finches Sicalis luteola, which nest at areas with tall grasses, were more abundant in fields with livestock use patches in the field surroundings. In autumn (non-breeding season), most bird responses were associated with foraging and refuge needs. The high abundance of eared doves in crop stubbles and the association of pigeons at field surroundings dominated by croplands or at crop stubbles surrounded by livestock use fields revealed the intimate association of these species to sites with high availability of food resources. In addition, both picazuro pigeons and spot-winged pigeons Patagioenas maculosa were associated with woodlots, which provide suitable roosting sites. Our results show that in temperate agroecosystems, the relationships between field characteristics and seed-eating bird abundances vary with season. PMID

  16. Diversity and Seasonal Dynamics of Actinobacteria Populations in Four Lakes in Northeastern Germany

    Science.gov (United States)

    Allgaier, Martin; Grossart, Hans-Peter

    2006-01-01

    The phylogenetic diversity and seasonal dynamics of freshwater Actinobacteria populations in four limnologically different lakes of the Mecklenburg-Brandenburg Lake District (northeastern Germany) were investigated. Fluorescence in situ hybridization was used to determine the seasonal abundances and dynamics of total Actinobacteria (probe HGC69a) and the three actinobacterial subclusters acI, acI-A, and acI-B (probes AcI-852, AcI-840-1, and AcI-840-2). Seasonal means of total Actinobacteria abundances in the epilimnia of the lakes varied from 13 to 36%, with maximum values of 30 to 58%, of all DAPI (4′,6′-diamidino-2-phenylindole)-stained cells. Around 80% of total Actinobacteria belonged to the acI cluster. The two subclusters acI-A and acI-B accounted for 60 to 91% of the acI cluster and showed seasonal means of 49% (acI-B) and 23% (acI-A) in relation to the acI cluster. Total Actinobacteria and members of the clusters acI and acI-B showed distinct seasonal changes in their absolute abundances, with maxima in late spring and fall/winter. In eight clone libraries constructed from the lakes, a total of 76 actinobacterial 16S rRNA gene sequences were identified from a total of 177 clones. The majority of the Actinobacteria sequences belonged to the acI and acIV cluster. Several new clusters and subclusters were found (acSTL, scB1-4, and acIVA-D). The majority of all obtained 16S rRNA gene sequences are distinct from those of already-cultured freshwater Actinobacteria. PMID:16672495

  17. Seasonal dynamics of ant community structure in the Moroccan Argan Forest.

    Science.gov (United States)

    El Keroumi, Abderrahim; Naamani, Khalid; Soummane, Hassna; Dahbi, Abdallah

    2012-01-01

    In this study we describe the structure and composition of ant communities in the endemic Moroccan Argan forest, using pitfall traps sampling technique throughout the four seasons between May 2006 and February 2007. The study focused on two distinct climatic habitats within the Essaouira Argan forest, a semi-continental site at Lahssinate, and a coastal site at Boutazarte. Thirteen different ant species were identified, belonging to seven genera. Monomorium subopacum Smith and Tapinoma simrothi Krausse-Heldrungen (Hymenoptera: Formicidae) were the most abundant and behaviorally dominant ant species in the arganeraie. In addition, more specimens were captured in the semi-continental site than in the coastal area. However, no significant difference was observed in species richness, evenness, or diversity between both sites. Composition and community structure showed clear seasonal dynamics. The number of species, their abundance, their diversity, and their evenness per Argan tree were significantly dissimilar among seasons. The richness (except between summer and autumn), and the abundance and the evenness of ant species among communities, showed a significant difference between the dry period (summer and spring) and the rainy period (winter and autumn). Higher abundance and richness values occurred in the dry period of the year. Ant species dominance and seasonal climatic variations in the arganeraie might be among the main factors affecting the composition, structure, and foraging activity of ant communities. This study, together with recent findings on ant predation behavior below Argan trees, highlights the promising use of dominant ant species as potential agents of Mediterranean fruit fly bio-control in the Argan forest and surrounding ecosystems.

  18. Ocean time-series reveals recurring seasonal patterns of virioplankton dynamics in the northwestern Sargasso Sea.

    Science.gov (United States)

    Parsons, Rachel J; Breitbart, Mya; Lomas, Michael W; Carlson, Craig A

    2012-02-01

    There are an estimated 10(30) virioplankton in the world oceans, the majority of which are phages (viruses that infect bacteria). Marine phages encompass enormous genetic diversity, affect biogeochemical cycling of elements, and partially control aspects of prokaryotic production and diversity. Despite their importance, there is a paucity of data describing virioplankton distributions over time and depth in oceanic systems. A decade of high-resolution time-series data collected from the upper 300 m in the northwestern Sargasso Sea revealed recurring temporal and vertical patterns of virioplankton abundance in unprecedented detail. An annual virioplankton maximum developed between 60 and 100 m during periods of summer stratification and eroded during winter convective mixing. The timing and vertical positioning of this seasonal pattern was related to variability in water column stability and the dynamics of specific picophytoplankton and heterotrophic bacterioplankton lineages. Between 60 and 100 m, virioplankton abundance was negatively correlated to the dominant heterotrophic bacterioplankton lineage SAR11, as well as the less abundant picophytoplankton, Synechococcus. In contrast, virioplankton abundance was positively correlated to the dominant picophytoplankton lineage Prochlorococcus, and the less abundant alpha-proteobacteria, Rhodobacteraceae. Seasonally, virioplankton abundances were highly synchronous with Prochlorococcus distributions and the virioplankton to Prochlorococcus ratio remained remarkably constant during periods of water column stratification. The data suggest that a significant fraction of viruses in the mid-euphotic zone of the subtropical gyres may be cyanophages and patterns in their abundance are largely determined by Prochlorococcus dynamics in response to water column stability. This high-resolution, decadal survey of virioplankton abundance provides insight into the possible controls of virioplankton dynamics in the open ocean.

  19. Seasonal abundance of the dolphinfish, Coryphaena hippurus, in Hawaii and the tropical Pacific Ocean

    Directory of Open Access Journals (Sweden)

    Syd Kraul

    1999-12-01

    Full Text Available This report looks at possible explanations for the seasonal abundance of the dolphinfish, Coryphaena hippurus, in Hawaii. In Hawaii and many parts of the Pacific Ocean, the abundance of C. hippurus (called mahimahi in Hawaii varies seasonally in a pattern that is fairly consistent from year to year. Size frequency analysis shows that this pattern of seasonal landings matches the pattern of cohort abundance in certain years. The strongest cohorts are spawned in July, often stay in our fishing zone for at least 5 months, and may comprise the predominant portion of the catch through October. Even though mahimahi spawn copiously all year in captivity, the data here suggest that wild mahimahi either spawn less frequently, or their larvae survive better at certain times of the year. Thus, seasonal abundance of mahimahi in Hawaii might be a function of cohort survival. The abundance pattern also fits the pattern of change in seasonal surface temperatures, and it is quite possible that mahimahi migrate north and south to stay in the sea surface thermocline associated with the 23°C isotherm. Natural growth rates were derived from our size frequency analyses, and the rates matched growth rates reported in a previous study of otolith ring deposition. A significant increase in longline fishing in 1989 increased total landings but did not reduce the catch quantity or sales price for charter boat mahimahi.

  20. Seasonal abundance and molecular identification of West Nile virus ...

    African Journals Online (AJOL)

    Seasonal abundance and molecular identification of West Nile virus vectors, Culex pipens and Culex ... Background: West Nile virus (WNV) infection, is an arbovirus infection with high morbidity and mortality, the vector respon- sible for both human ... Major diseases transmitted are known as Arboviral dis- eases because ...

  1. Distribution and seasonal abundance of large cetaceans in the ...

    African Journals Online (AJOL)

    Killer whale Orcinus orca presence was coincident with that of offshore minke whales and the southward migrations of other baleen whales, whereas densities of animals deemed as bottlenose whale Hyperoodon planifrons suggest strong early and late summer seasonal abundance in the offshore region. Such extensive ...

  2. Comparison of the seasonal variability in abundance of the copepod Pseudocalanus newmani in Lagoon Notoro-ko and a coastal area of the southwestern Okhotsk Sea

    Science.gov (United States)

    Kitamura, Mitsuaki; Nakagawa, Yoshizumi; Nishino, Yasuto; Segawa, Susumu; Shiomoto, Akihiro

    2018-03-01

    Replacement of the warm water of the Soya Warm Current (SWC) and the cold water of the East Sakhalin Current (ESC) occurs seasonally along the coast of the southwestern Okhotsk Sea, and sea ice covers the surface during winter. Pseudocalanus newmani is one of the dominant copepods in coastal waters of the northern hemisphere. To better understand the population dynamics of the copepod P. newmani in coastal areas of the southwestern Okhotsk Sea, this study compared the seasonal variation in P. newmani abundance in Lagoon Notoro-ko and a coastal area of the Okhotsk Sea with regard to developmental stage. We sampled P. newmani in the lagoon, including during the ice cover season, and the coastal waters. Pseudocalanus newmani was abundant at both sites in spring. During summer-fall, adults disappeared from the populations at both sites, whereas the early developmental stages were abundant and dominated the population. Total length of adult females decreased toward summer at both sites. Pseudocalanus newmani abundance in the lagoon increased in early winter, and larger females were found in the populations at both sites. These phenomena at both sites corresponded with seasonal variation in water temperature caused by seasonal water-mass replacement and sea ice.

  3. Seasonal abundance of epipelic algae and sediment parameters of ...

    African Journals Online (AJOL)

    Amadi-Ama creek is located close to sources of wastes which are introduced into the creek thus altering the physico-chemical parameters and the aquatic biota of the creek due to variation in nutrient load of the water. The seasonal abundance of epipelic algae and sediment parameters of Amadi-Ama Creek were ...

  4. Seasonal patterns of horse fly richness and abundance in the Pampa biome of southern Brazil.

    Science.gov (United States)

    Krüger, Rodrigo Ferreira; Krolow, Tiago Kütter

    2015-12-01

    Fluctuations in seasonal patterns of horse fly populations were examined in rainforests of tropical South America, where the climate is seasonal. These patterns were evaluated with robust analytical models rather than identifying the main factors that influenced the fluctuations. We examined the seasonality of populations of horse flies in fields and lowland areas of the Pampa biome of southern Brazil with generalized linear models. We also investigated the diversity of these flies and the sampling effort of Malaise traps in this biome over two years. All of the 29 species had clear seasonality with regard to occurrence and abundance, but only seven species were identified as being influenced by temperature and humidity. The sampling was sufficient and the estimated diversity was 10% more than observed. Seasonal trends were synchronized across species and the populations were most abundant between September and March and nearly zero in other months. While previous studies demonstrated that seasonal patterns in population fluctuations are correlated with climatic conditions in horse fly assemblages in South America rainforests, we show a clear effect of each factor on richness and abundance and the seasonality in the prevalence of horse fly assemblages in localities of the Pampa biome. © 2015 The Society for Vector Ecology.

  5. Seasonal dynamics of snail populations in coastal Kenya: Model calibration and snail control

    Science.gov (United States)

    Gurarie, D.; King, C. H.; Yoon, N.; Wang, X.; Alsallaq, R.

    2017-10-01

    A proper snail population model is important for accurately predicting Schistosoma transmission. Field data shows that the overall snail population and that of shedding snails have a strong pattern of seasonal variation. Because human hosts are infected by the cercariae released from shedding snails, the abundance of the snail population sets ultimate limits on human infection. For developing a predictive dynamic model of schistosome infection and control strategies we need realistic snail population dynamics. Here we propose two such models based on underlying environmental factors and snail population biology. The models consist of two-stage (young-adult) populations with resource-dependent reproduction, survival, maturation. The key input in the system is seasonal rainfall which creates snail habitats and resources (small vegetation). The models were tested, calibrated and validated using dataset collected in Msambweni (coastal Kenya). Seasonal rainfall in Msambweni is highly variable with intermittent wet - dry seasons. Typical snail patterns follow precipitation peaks with 2-4-month time-lag. Our models are able to reproduce such seasonal variability over extended period of time (3-year study). We applied them to explore the optimal seasonal timing for implementing snail control.

  6. Seasonal dynamics of the copepod community in a tropical monsoonal estuary and the role of sex ratio in their abundance pattern

    Digital Repository Service at National Institute of Oceanography (India)

    Vineetha, G.; Madhu, N.V.; Kusum, K.K.; Sooria, P.M.

    structure of copepods in the tropical monsoonal estuarine system.The ecological scenario in the Cochin estuary revealed that irrespective of the season, higher zooplankton abundance occurred in the mesohaline zone (MSZ; salinity 5–18) of the estuary, despite...

  7. Seasonal Dynamics of Haptophytes and dsDNA Algal Viruses Suggest Complex Virus-Host Relationship.

    Science.gov (United States)

    Johannessen, Torill Vik; Larsen, Aud; Bratbak, Gunnar; Pagarete, António; Edvardsen, Bente; Egge, Elianne D; Sandaa, Ruth-Anne

    2017-04-20

    Viruses influence the ecology and diversity of phytoplankton in the ocean. Most studies of phytoplankton host-virus interactions have focused on bloom-forming species like Emiliania huxleyi or Phaeocystis spp. The role of viruses infecting phytoplankton that do not form conspicuous blooms have received less attention. Here we explore the dynamics of phytoplankton and algal viruses over several sequential seasons, with a focus on the ubiquitous and diverse phytoplankton division Haptophyta, and their double-stranded DNA viruses, potentially with the capacity to infect the haptophytes. Viral and phytoplankton abundance and diversity showed recurrent seasonal changes, mainly explained by hydrographic conditions. By 454 tag-sequencing we revealed 93 unique haptophyte operational taxonomic units (OTUs), with seasonal changes in abundance. Sixty-one unique viral OTUs, representing Megaviridae and Phycodnaviridae , showed only distant relationship with currently isolated algal viruses. Haptophyte and virus community composition and diversity varied substantially throughout the year, but in an uncoordinated manner. A minority of the viral OTUs were highly abundant at specific time-points, indicating a boom-bust relationship with their host. Most of the viral OTUs were very persistent, which may represent viruses that coexist with their hosts, or able to exploit several host species.

  8. Abundance, Fishing Season and Management Strategy for Blue Swimming Crab (Portunus pelagicus) in Pangkajene Kepulauan, South Sulawesi, Indonesia.

    Science.gov (United States)

    Wiyono, Eko Sri; Ihsan

    2018-03-01

    In order to manage blue swimming crabs in Pangkajene Kepulauan, management measures are required. Since the environment which affects the abundance of the blue swimming crab varies seasonally, it is necessary to take into account the seasonal nature with the aim of developing a management strategy. The objectives of this study are to define the abundance of and fishing season of blue swimming crabs in the Pangkajene Kepulauan waters, South Sulawesi, Indonesia. The fishing season was analysed using seasonal index analysis, while fish abundance was analysed by means of Equilibrium-Schaefer. The result of this study demonstrated that fishermen allocate their fishing gear all year, although the fish catch is seasonal. Based on analysis of the result, the fishing season for the blue swimming crabs is short. The peak fishing season starts in May and finishes in June. However, in order to enable their families to earn a living, fishermen operated their fishing gear throughout the year. As a result, both catch landing and effort were close to maximum sustainable yield (MSY). In order to reduce fishing pressure, it is necessary to reduce fishing gear and have a seasonal arrangement regarding fishing gear allocation.

  9. Seasonal occurrence and abundance of caridean shrimp larvae at Helgoland, German Bight

    Science.gov (United States)

    Wehrtmann, Ingo S.

    1989-03-01

    Plankton samples were collected from January 1985 to January 1986 three times per week at Helgoland to study seasonal occurrence and abundance of caridean shrimp larvae. A total of eleven species were obtained. Ninety-one % of all larvae collected during the sample period belonged to Crangon crangon L. and Crangon allmanni Kinahan, 6% to Philocheras trispinosus Hailstone and 3% to the remaining eight species. Collections were generally dominated by C. crangon larvae. However, C. allmanni larvae were most abundant in June coinciding with hatching activities of the population near Helgoland. C. allmanni was observed to have the highest density of all species with approximately 8 larvae per m3. Larvae of Eualus occultus (Lebour), Eualus pusiolus (Kroyer), Hippolyte varians Leach and Athanas nitescens Leach were most likely released by populations inhabiting the rocky intertidal zone around Helgoland. The presence of Processa modica Williamson & Rochanaburanon and Processa nouveli holthuisi Al-Adhub & Williamson in the German Bight was verified by observations of a series of different developmental stages. Larvae of the rare species Caridion steveni Lebour were also recorded. The observed shrimp species were placed into three different groups with respect to their seasonal occurrence. Possible advantages of the timing of larval dispersal relative to predation and food availability are given. The results on seasonal occurrence and relative abundance are discussed in relation to environmental factors (temperature, salinity) as well as to the geographical distribution of the species.

  10. Temporal dynamics of abundance and composition of nitrogen-fixing communities across agricultural soils.

    Directory of Open Access Journals (Sweden)

    Michele C Pereira E Silva

    Full Text Available BACKGROUND: Despite the fact that the fixation of nitrogen is one of the most significant nutrient processes in the terrestrial ecosystem, a thorough study of the spatial and temporal patterns in the abundance and distribution of N-fixing communities has been missing so far. METHODOLOGY/PRINCIPAL FINDINGS: In order to understand the dynamics of diazotrophic communities and their resilience to external changes, we quantified the abundance and characterized the bacterial community structures based on the nifH gene, using real-time PCR, PCR-DGGE and 454-pyrosequencing, across four representative Dutch soils during one growing season. In general, higher nifH gene copy numbers were observed in soils with higher pH than in those with lower pH, but lower numbers were related to increased nitrate and ammonium levels. Results from nifH gene pyrosequencing confirmed the observed PCR-DGGE patterns, which indicated that the N fixers are highly dynamic across time, shifting around 60%. Forward selection on CCA analysis identified N availability as the main driver of these variations, as well as of the evenness of the communities, leading to very unequal communities. Moreover, deep sequencing of the nifH gene revealed that sandy soils (B and D had the lowest percentage of shared OTUs across time, compared with clayey soils (G and K, indicating the presence of a community under constant change. Cosmopolitan nifH species (present throughout the season were affiliated with Bradyrhizobium, Azospirillum and Methylocistis, whereas other species increased their abundances progressively over time, when appropriate conditions were met, as was notably the case for Paenibacilus and Burkholderia. CONCLUSIONS: Our study provides the first in-depth pyrosequencing analysis of the N-fixing community at both spatial and temporal scales, providing insights into the cosmopolitan and specific portions of the nitrogen fixing bacterial communities in soil.

  11. Influence of Seasonal Food Availability on the Dynamics of Seabird Feeding Flocks at a Coastal Upwelling Area.

    Science.gov (United States)

    Anguita, Cristóbal; Simeone, Alejandro

    2015-01-01

    The formation of multi-species feeding flocks (MSFFs) through visual recruitment is considered an important strategy for obtaining food in seabirds and its functionality has been ascribed to enhanced foraging efficiency. Its use has been demonstrated in much of the world's oceans and includes numerous species. However, there is scant information on the temporal stability of the composition and abundance of MSFFs as well as the effect of seasonal food availability on their dynamics. Between July 2006 and September 2014, we conducted monthly at-sea seabird counts at Valparaiso Bay (32°56' to 33°01'S, 71°36' to 71°46'W) within the area of influence of the Humboldt Current in central Chile. This area is characterized by a marked seasonality in primary and secondary production associated with upwelling, mainly during austral spring-summer. Based on studies that provide evidence that flocking is most frequent when food is both scarce and patchy, we hypothesized that seabird MSFF attributes (i.e. frequency of occurrence, abundance and composition) will be modified according to the seasonal availability of food. Using generalized linear models (GLMs), our results show that the contrasting seasonality in food availability of the study area (using chlorophyll-a concentration as a proxy) had no significant influence on MSFF attributes, sparsely explaining their variations (P>0.05). Rather than seasonal food availability, the observed pattern for MSFF attributes at Valparaiso Bay suggests a substantial influence of reproductive and migratory (boreal and austral migrants) habits of birds that modulates MSFF dynamics consistently throughout the whole year in this highly variable and patchy environment. We highlight the importance of visual recruitment as a mechanism by which migratory and resident birds interact. This would allow them to reduce resource unpredictability, which in turn has a major impact on structuring seabird's MSFF dynamics.

  12. Influence of Seasonal Food Availability on the Dynamics of Seabird Feeding Flocks at a Coastal Upwelling Area.

    Directory of Open Access Journals (Sweden)

    Cristóbal Anguita

    Full Text Available The formation of multi-species feeding flocks (MSFFs through visual recruitment is considered an important strategy for obtaining food in seabirds and its functionality has been ascribed to enhanced foraging efficiency. Its use has been demonstrated in much of the world's oceans and includes numerous species. However, there is scant information on the temporal stability of the composition and abundance of MSFFs as well as the effect of seasonal food availability on their dynamics. Between July 2006 and September 2014, we conducted monthly at-sea seabird counts at Valparaiso Bay (32°56' to 33°01'S, 71°36' to 71°46'W within the area of influence of the Humboldt Current in central Chile. This area is characterized by a marked seasonality in primary and secondary production associated with upwelling, mainly during austral spring-summer. Based on studies that provide evidence that flocking is most frequent when food is both scarce and patchy, we hypothesized that seabird MSFF attributes (i.e. frequency of occurrence, abundance and composition will be modified according to the seasonal availability of food. Using generalized linear models (GLMs, our results show that the contrasting seasonality in food availability of the study area (using chlorophyll-a concentration as a proxy had no significant influence on MSFF attributes, sparsely explaining their variations (P>0.05. Rather than seasonal food availability, the observed pattern for MSFF attributes at Valparaiso Bay suggests a substantial influence of reproductive and migratory (boreal and austral migrants habits of birds that modulates MSFF dynamics consistently throughout the whole year in this highly variable and patchy environment. We highlight the importance of visual recruitment as a mechanism by which migratory and resident birds interact. This would allow them to reduce resource unpredictability, which in turn has a major impact on structuring seabird's MSFF dynamics.

  13. SEASONAL ABUNDANCE OF ORGANIC MOLECULAR MARKERS IN URBAN PARTICULATE MATTER FROM PHILADELPHIA, PA

    Science.gov (United States)

    Organic molecular markers were measured in airborne particulate matter (PM10) from the City of Philadelphia North Broad Street air quality monitoring site to identify the seasonal abundances of key tracer compounds together with their dominant sources. Daily PM10...

  14. Factors affecting the abundance of leaf-litter arthropods in unburned and thrice-burned seasonally-dry Amazonian forests.

    Science.gov (United States)

    Silveira, Juliana M; Barlow, Jos; Louzada, Julio; Moutinho, Paulo

    2010-09-21

    Fire is frequently used as a land management tool for cattle ranching and annual crops in the Amazon. However, these maintenance fires often escape into surrounding forests, with potentially severe impacts for forest biodiversity. We examined the effect of experimental fires on leaf-litter arthropod abundance in a seasonally-dry forest in the Brazilian Amazon. The study plots (50 ha each) included a thrice-burned forest and an unburned control forest. Pitfall-trap samples were collected at 160 randomly selected points in both plots, with sampling stratified across four intra-annual replicates across the dry and wet seasons, corresponding to 6, 8, 10 and 12 months after the most recent fire. Arthropods were identified to the level of order (separating Formicidae). In order to better understand the processes that determine arthropod abundance in thrice-burned forests, we measured canopy openness, understory density and litter depth. All arthropod taxa were significantly affected by fire and season. In addition, the interactions between burn treatment and season were highly significant for all taxa but Isoptera. The burned plot was characterized by a more open canopy, lower understory density and shallower litter depth. Hierarchical partitioning revealed that canopy openness was the most important factor explaining arthropod order abundances in the thrice-burned plot, whereas all three environmental variables were significant in the unburned control plot. These results reveal the marked impact of recurrent wildfires and seasonality on litter arthropods in this transitional forest, and demonstrate the overwhelming importance of canopy-openness in driving post-fire arthropod abundance.

  15. Seasonal variation in composition and abundance of harmful dinoflagellates in Yemeni waters, southern Red Sea.

    Science.gov (United States)

    Alkawri, Abdulsalam

    2016-11-15

    General abundance and species composition of a dinoflagellate community in Yemeni coastal waters of Al Salif (southern Red Sea) were studied with a view to understand the annual variations in particular the toxic species. Dinoflagellates were more abundant among phytoplankton. Thirty five dinoflagellate taxa were identified, among which 12 were reported as potentially toxic species. A significant change in seasonal abundance was recorded with the maximum (2.27∗10 6 cellsl -1 ) in May, and the minimum (2.50∗10 2 cellsl -1 ) recorded in January. Kryptoperidinium foliaceum, which was reported for the first time from the Red Sea, was the most abundant species with a maximum in May 2013 (2.26∗10 6 cellsl -1 ). Spearman's rank correlation analysis indicates that, total harmful dinoflagellate cells, K. foliaceum, Prorocentrum gracile and Prorocentrum micans were significantly correlated with temperature. This study suggests that Yemeni waters should be monitored to investigate harmful species and to identify areas and seasons at higher risk. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Density and climate influence seasonal population dynamics in an Arctic ungulate

    DEFF Research Database (Denmark)

    Mortensen, Lars O.; Moshøj, Charlotte; Forchhammer, Mads C.

    2016-01-01

    The locally migratory behavior of the high arctic muskox (Ovibos muschatus) is a central component of the breeding and winter survival strategies applied to cope with the highly seasonal arctic climate. However, altered climate regimes affecting plant growth are likely to affect local migration...... cover), forage availability (length of growth season), and the number of adult females available per male (operational sex ratio) influence changes in the seasonal density dependence, abundance, and immigration rate of muskoxen into the valley. The results suggested summer temperature as the major...... controlling factor in the seasonal, local-scale migration of muskoxen at Zackenberg. Specifically, higher summer temperatures, defined as the cumulative average daily positive degrees in June, July, and August, resulted in decreased density dependence and, consequently, increase in the seasonal abundance...

  17. The rainy season increases the abundance and richness of the aquatic insect community in a Neotropical reservoir

    Directory of Open Access Journals (Sweden)

    HS Santana

    Full Text Available Alterations in aquatic systems and changes in water levels, whether due to rains or dam-mediated control can cause changes in community structure, forcing the community to readjust to the new environment. This study tested the hypothesis that there is an increase in the richness and abundance of aquatic insects during the rainy season in the Serra da Mesa Reservoir, with the premise that increasing the reservoir level provides greater external material input and habitat diversity, and, therefore, conditions that promote colonization by more species. We used the paired t test to test the differences in richness, beta diversity, and abundance, and a Non-metric Multidimensional Scaling (NMDS was performed to identify patterns in the community under study. Additionally, Pearson correlations were analyzed between the richness, abundance, and beta diversity and the level of the reservoir. We collected 35,028 aquatic insect larvae (9,513 in dry period and 25,515 in the rainy season, predominantly of the Chironomidae family, followed by orders Ephemeroptera, Trichoptera, and Odonata. Among the 33 families collected, only 12 occurred in the dry season, while all occurred in the rainy season. These families are common in lentic environments, and the dominance of Chironomidae was associated with its fast colonization, their behavior of living at high densities and the great tolerance to low levels of oxygen in the environment. The hypothesis was confirmed, as the richness, beta diversity, and abundance were positively affected by the increase in water levels due to the rainy season, which most likely led to greater external material input, greater heterogeneity of habitat, and better conditions for colonization by several families.

  18. The rainy season increases the abundance and richness of the aquatic insect community in a Neotropical reservoir.

    Science.gov (United States)

    Santana, H S; Silva, L C F; Pereira, C L; Simião-Ferreira, J; Angelini, R

    2015-01-01

    Alterations in aquatic systems and changes in water levels, whether due to rains or dam-mediated control can cause changes in community structure, forcing the community to readjust to the new environment. This study tested the hypothesis that there is an increase in the richness and abundance of aquatic insects during the rainy season in the Serra da Mesa Reservoir, with the premise that increasing the reservoir level provides greater external material input and habitat diversity, and, therefore, conditions that promote colonization by more species. We used the paired t test to test the differences in richness, beta diversity, and abundance, and a Non-metric Multidimensional Scaling (NMDS) was performed to identify patterns in the community under study. Additionally, Pearson correlations were analyzed between the richness, abundance, and beta diversity and the level of the reservoir. We collected 35,028 aquatic insect larvae (9,513 in dry period and 25,515 in the rainy season), predominantly of the Chironomidae family, followed by orders Ephemeroptera, Trichoptera, and Odonata. Among the 33 families collected, only 12 occurred in the dry season, while all occurred in the rainy season. These families are common in lentic environments, and the dominance of Chironomidae was associated with its fast colonization, their behavior of living at high densities and the great tolerance to low levels of oxygen in the environment. The hypothesis was confirmed, as the richness, beta diversity, and abundance were positively affected by the increase in water levels due to the rainy season, which most likely led to greater external material input, greater heterogeneity of habitat, and better conditions for colonization by several families.

  19. Seasonal diversity and dynamics of haptophytes in the Skagerrak, Norway, explored by high-throughput sequencing

    Science.gov (United States)

    Egge, Elianne Sirnæs; Johannessen, Torill Vik; Andersen, Tom; Eikrem, Wenche; Bittner, Lucie; Larsen, Aud; Sandaa, Ruth-Anne; Edvardsen, Bente

    2015-01-01

    Microalgae in the division Haptophyta play key roles in the marine ecosystem and in global biogeochemical processes. Despite their ecological importance, knowledge on seasonal dynamics, community composition and abundance at the species level is limited due to their small cell size and few morphological features visible under the light microscope. Here, we present unique data on haptophyte seasonal diversity and dynamics from two annual cycles, with the taxonomic resolution and sampling depth obtained with high-throughput sequencing. From outer Oslofjorden, S Norway, nano- and picoplanktonic samples were collected monthly for 2 years, and the haptophytes targeted by amplification of RNA/cDNA with Haptophyta-specific 18S rDNA V4 primers. We obtained 156 operational taxonomic units (OTUs), from c. 400.000 454 pyrosequencing reads, after rigorous bioinformatic filtering and clustering at 99.5%. Most OTUs represented uncultured and/or not yet 18S rDNA-sequenced species. Haptophyte OTU richness and community composition exhibited high temporal variation and significant yearly periodicity. Richness was highest in September–October (autumn) and lowest in April–May (spring). Some taxa were detected all year, such as Chrysochromulina simplex, Emiliania huxleyi and Phaeocystis cordata, whereas most calcifying coccolithophores only appeared from summer to early winter. We also revealed the seasonal dynamics of OTUs representing putative novel classes (clades HAP-3–5) or orders (clades D, E, F). Season, light and temperature accounted for 29% of the variation in OTU composition. Residual variation may be related to biotic factors, such as competition and viral infection. This study provides new, in-depth knowledge on seasonal diversity and dynamics of haptophytes in North Atlantic coastal waters. PMID:25893259

  20. Adverse moisture events predict seasonal abundance of Lyme disease vector ticks (Ixodes scapularis)

    Science.gov (United States)

    Berger, Kathryn A.; Ginsberg, Howard S.; Dugas, Katherine D.; Hamel, Lutz H.; Mather, Thomas N.

    2014-01-01

    Background: Lyme borreliosis (LB) is the most commonly reported vector-borne disease in north temperate regions worldwide, affecting an estimated 300,000 people annually in the United States alone. The incidence of LB is correlated with human exposure to its vector, the blacklegged tick (Ixodes scapularis). To date, attempts to model tick encounter risk based on environmental parameters have been equivocal. Previous studies have not considered (1) the differences between relative humidity (RH) in leaf litter and at weather stations, (2) the RH threshold that affects nymphal blacklegged tick survival, and (3) the time required below the threshold to induce mortality. We clarify the association between environmental moisture and tick survival by presenting a significant relationship between the total number of tick adverse moisture events (TAMEs - calculated as microclimatic periods below a RH threshold) and tick abundance each year.Methods: We used a 14-year continuous statewide tick surveillance database and corresponding weather data from Rhode Island (RI), USA, to assess the effects of TAMEs on nymphal populations of I. scapularis. These TAMEs were defined as extended periods of time (>8 h below 82% RH in leaf litter). We fit a sigmoid curve comparing weather station data to those collected by loggers placed in tick habitats to estimate RH experienced by nymphal ticks, and compiled the number of historical TAMEs during the 14-year record.Results: The total number of TAMEs in June of each year was negatively related to total seasonal nymphal tick densities, suggesting that sub-threshold humidity episodes >8 h in duration naturally lowered nymphal blacklegged tick abundance. Furthermore, TAMEs were positively related to the ratio of tick abundance early in the season when compared to late season, suggesting that lower than average tick abundance for a given year resulted from tick mortality and not from other factors.Conclusions: Our results clarify the mechanism

  1. Seasonal distribution and abundance of cetaceans within French waters- Part I: The North-Western Mediterranean, including the Pelagos sanctuary

    Science.gov (United States)

    Laran, Sophie; Pettex, Emeline; Authier, Matthieu; Blanck, Aurélie; David, Léa; Dorémus, Ghislain; Falchetto, Hélène; Monestiez, Pascal; Van Canneyt, Olivier; Ridoux, Vincent

    2017-07-01

    The biodiversity of the Mediterranean Sea is undergoing important changes. Cetaceans, as top predators, are an important component of marine ecosystems. The seasonal distribution and abundance of several cetacean species were studied with a large aerial survey over the North-Western Mediterranean Sea, including the international Pelagos sanctuary, the largest Marine Protected Area (MPA) designed for marine mammals in the Mediterranean. A total of 8 distinct species of cetaceans were identified, and their occurrence within the sanctuary was investigated. Abundance estimates were obtained for three groups of species: the small delphinids (striped dolphins mainly), the bottlenose dolphin and the fin whale. There was a seasonal variation in striped dolphin abundance between winter (57,300 individuals, 95% CI: 34,500-102,000) and summer (130,000, 95% CI: 76,800-222,100). In contrast, bottlenose dolphin winter abundance was thrice that of summer. It was also the only species to exhibit any preference for the Pelagos sanctuary. Fin whale abundance had the reverse pattern with winter abundance (1000 individuals, 95% CI: 500-2500) and summer (2500 individuals, 95% CI: 1500-4300), without any preference for the sanctuary. Risso's dolphins, pilot whales and sperm whales did not exhibit strong seasonal pattern in their abundance. These results provide baseline estimates which can be used to inform conservation policies and instruments such as the Habitats Directive or the recent European Marine Strategy Framework Directive.

  2. Abiotic and biotic factors influencing nanoflagellate abundance and distribution in three different seasons in PRE, South China Sea

    Science.gov (United States)

    Zhang, Xia; Shi, Zhen; Huang, Xiaoping; Li, Xiangfu

    2017-07-01

    Spatial distribution characteristics of two nanoflagellate groups, together with physico-chemical and biological factors, were studied in three seasons in the Pearl River Estuary (PRE), South China Sea. Nanoflagellates were more abundant in warm periods than that in winter. The average abundance in the three observations (spring, summer and winter) was as follow: 1.28 ± 1.17, 0.88 ± 1.02 and 0.28 ± 0.23 × 103 cells ml-1 of heterotrophic nanoflagellate (HNF), and 1.26 ± 0.85, 0.89 ± 0.77 and 0.65 ± 0.52 × 103 cells ml-1 of pigmented nanoflagellate (PNF). In our three studied seasons, NF density was generally higher in the inner estuary and decreasing to the lowest in the outer estuary. Our results suggested that PNF classes were more sensitive than HNF groups to freshwater discharge. The proportion of PNF gradually increased from spring (49.7%) to winter (67.7%), with the river flow was accordingly decreasing. Moreover, spatial distribution pattern in three seasons showed the response of PNF populations to freshwater input was similar to phytoplankton assemblages in the PRE. Total bacterial and live bacterial abundance (measured by LIVE/DEAD kit) were associated with both two NF components, which implied that NF was a potential predator controlling the bulk abundance of bacteria and proportion of active cells. These results revealed the seasonal and spatial variations of NF abundance in diverse conditions in the PRE and how their response to different ecological processes.

  3. Potential damages, seasonal abundance and distribution of Empoasca terminalis Distant (Homoptera: Cicadellidae on soybean in South Sulawesi

    Directory of Open Access Journals (Sweden)

    Andi Nasruddin

    2015-09-01

    Full Text Available Plant damages caused by leafhopper, Empoasca terminalis Distant (Homoptera: Cicadellidae on soybean were first encountered in 2007 in Makassar, South Sulawesi. The insect has been constantly associated with soybean crops in the province ever since. The purposes of the present study were to (i evaluate potential yield loss attributable to the leafhopper in an experimental set up, (ii seasonal abundance of E. terminalis, and (iii distribution of E. terminalis in all major soybean-producing areas in the province. Potential yield loss due to the leafhopper was assessed in a field experiment using two large plots. One of the plots was kept leafhopper-free by weekly insecticide sprays; and the other plot was left unsprayed to allow leafhopper infestation to occur. Adult abundance was weekly monitored using a sweep net throughout the season. Nymph abundance was determined by direct count on the plant leaves. Leafhopper distribution was assessed through surveys conducted in all major soybean-producing areas in South Sulawesi, from 2009–2013. The results of the study showed that E. terminalis caused an average yield loss of 26% on susceptible crops without insecticide use. First leafhopper infestation in all planting seasons occurred two weeks after the plant emergence. Rainfall negatively correlated with the leafhopper abundance. The leafhopper existed in all major soybean production areas in the province. Therefore, our results confirmed the status of E. terminalis as an important soybean pest in the region. In addition, crops planted early in the dry season could escape from heavy leafhopper infestation.

  4. Seasonal diversity and dynamics of haptophytes in the Skagerrak, Norway, explored by high-throughput sequencing.

    Science.gov (United States)

    Egge, Elianne Sirnaes; Johannessen, Torill Vik; Andersen, Tom; Eikrem, Wenche; Bittner, Lucie; Larsen, Aud; Sandaa, Ruth-Anne; Edvardsen, Bente

    2015-06-01

    Microalgae in the division Haptophyta play key roles in the marine ecosystem and in global biogeochemical processes. Despite their ecological importance, knowledge on seasonal dynamics, community composition and abundance at the species level is limited due to their small cell size and few morphological features visible under the light microscope. Here, we present unique data on haptophyte seasonal diversity and dynamics from two annual cycles, with the taxonomic resolution and sampling depth obtained with high-throughput sequencing. From outer Oslofjorden, S Norway, nano- and picoplanktonic samples were collected monthly for 2 years, and the haptophytes targeted by amplification of RNA/cDNA with Haptophyta-specific 18S rDNA V4 primers. We obtained 156 operational taxonomic units (OTUs), from c. 400.000 454 pyrosequencing reads, after rigorous bioinformatic filtering and clustering at 99.5%. Most OTUs represented uncultured and/or not yet 18S rDNA-sequenced species. Haptophyte OTU richness and community composition exhibited high temporal variation and significant yearly periodicity. Richness was highest in September-October (autumn) and lowest in April-May (spring). Some taxa were detected all year, such as Chrysochromulina simplex, Emiliania huxleyi and Phaeocystis cordata, whereas most calcifying coccolithophores only appeared from summer to early winter. We also revealed the seasonal dynamics of OTUs representing putative novel classes (clades HAP-3-5) or orders (clades D, E, F). Season, light and temperature accounted for 29% of the variation in OTU composition. Residual variation may be related to biotic factors, such as competition and viral infection. This study provides new, in-depth knowledge on seasonal diversity and dynamics of haptophytes in North Atlantic coastal waters. © 2015 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

  5. Seasonal and Spatial Environmental Influence on Opisthorchis viverrini Intermediate Hosts, Abundance, and Distribution: Insights on Transmission Dynamics and Sustainable Control.

    Directory of Open Access Journals (Sweden)

    Christina Sunyoung Kim

    2016-11-01

    Full Text Available Opisthorchis viverrini (Ov is a complex-life-cycle trematode affecting 10 million people in SEA (Southeast Asia. Human infection occurs when infected cyprinid fish are consumed raw or undercooked. Ov requires three hosts and presents two free-living parasitic stages. As a consequence Ov transmission and infection in intermediate and human hosts are strongly mediated by environmental factors and understanding how environmental variability influences intermediate host abundance is critical. The objectives of this study were 1 to document water parameters, intermediate hosts abundance and infection spatio-temporal variation, 2 to assess their causal relationships and identify windows of transmission risk.Fish and snails were collected monthly for one year at 12 sites in Lawa Lake, an Ov-endemic region of Khon Kaen Province in Northeast Thailand. Physicochemical water parameters [pH, temperature (Tp, dissolved oxygen (DO, Salinity, electrical conductivity (EC, total dissolved solid (TDS, nitrite nitrogen (NO2-N, lead (Pb, total coliform bacteria (TCB and fecal coliform bacteria (FCB] were measured. Multivariate analyses, linear models and kriging were used to characterize water parameter variation and its influence on host abundance and infection prevalence. We found that sampling sites could be grouped in three clusters and discriminated along a nitrogen-salinity gradient where higher levels in the lake's southern region predicted higher Bithynia relative abundance (P<0.05 and lower snail and fish species diversity (P<0.05. Highest Bithynia abundance occurred during rainy season (P<0.001, independently of site influence. Cyprinids were the most abundant fish family and higher cyprinid relative abundance was found in areas with higher Bithynia relative abundance (P<0.05. Ov infection in snails was anecdotal while Ov infection in fish was higher in the southern region (P<0.001 at sites showing high FCB.Our results indicate that water contamination

  6. Seasonal distribution and abundance of cetaceans within French waters- Part II: The Bay of Biscay and the English Channel

    Science.gov (United States)

    Laran, Sophie; Authier, Matthieu; Blanck, Aurélie; Doremus, Ghislain; Falchetto, Hélène; Monestiez, Pascal; Pettex, Emeline; Stephan, Eric; Van Canneyt, Olivier; Ridoux, Vincent

    2017-07-01

    From the Habitat Directive to the recent Marine Strategy Framework Directive, the conservation status of cetaceans in European water has been of concern for over two decades. In this study, a seasonal comparison of the abundance and distribution of cetaceans was carried out in two contrasted regions of the Eastern North Atlantic, the Bay of Biscay and the English Channel. Estimates were obtained in the two sub-regions (375,000 km²) from large aerial surveys conducted in the winter (November 2011 to February 2012) and in the summer (May to August 2012). The most abundant species encountered in the Channel, the harbour porpoise, displayed strong seasonal variations in its distribution but a stable abundance (18,000 individuals, CV=30%). In the Bay of Biscay, abundance and distribution patterns of common / striped dolphins varied from 285,000 individuals (95% CI: 174,000-481,000) in the winter, preferentially distributed close to the shelf break, to 494,000 individuals (95% CI: 342,000-719,000) distributed beyond the shelf break in summer. Baleen whales also exhibited an increase of their density in summer. Seasonal abundances of bottlenose dolphins were quite stable, with a large number of 'pelagic' encounters offshore in winter. No significant seasonal difference was estimated for pilot whales and sperm whale. These surveys provided baseline estimates to inform policies to be developed, or for existing conservation instruments such as the Habitats Directive. In addition, our results supported the hypothesis of a shift in the summer distributions of some species such as harbour porpoise and minke whale in European waters.

  7. Seasonal dynamics of SAR11 populations in the euphotic and mesopelagic zones of the northwestern Sargasso Sea

    DEFF Research Database (Denmark)

    Carlson, Craig A; Morris, Robert; Parsons, Rachel

    2009-01-01

    , resolving their temporal dynamics can provide important insights to the cycling of organic and inorganic nutrients. This quantitative time-series data revealed distinct annual distribution patterns of SAR11 abundance in the euphotic (0-120) and upper mesopelagic (160-300 m) zones that were reproducibly...... correlated with seasonal mixing and stratification of the water column. Terminal restriction fragment length polymorphism (T-RFLP) data generated from a decade of samples collected at BATS were combined with the FISH data to model the annual dynamics of SAR11 subclade populations. 16S rRNA gene clone...... the Sargasso Sea surface layer, and revealed new details of their population dynamics....

  8. Strong seasonality and interannual recurrence in marine myovirus communities.

    Science.gov (United States)

    Pagarete, A; Chow, C-E T; Johannessen, T; Fuhrman, J A; Thingstad, T F; Sandaa, R A

    2013-10-01

    The temporal community dynamics and persistence of different viral types in the marine environment are still mostly obscure. Polymorphism of the major capsid protein gene, g23, was used to investigate the community composition dynamics of T4-like myoviruses in a North Atlantic fjord for a period of 2 years. A total of 160 unique operational taxonomic units (OTUs) were identified by terminal restriction fragment length polymorphism (TRFLP) of the gene g23. Three major community profiles were identified (winter-spring, summer, and autumn), which resulted in a clear seasonal succession pattern. These seasonal transitions were recurrent over the 2 years and significantly correlated with progression of seawater temperature, Synechococcus abundance, and turbidity. The appearance of the autumn viral communities was concomitant with the occurrence of prominent Synechococcus blooms. As a whole, we found a highly dynamic T4-like viral community with strong seasonality and recurrence patterns. These communities were unexpectedly dominated by a group of persistently abundant viruses.

  9. Seasonal Abundance and Host-Feeding Patterns of Anopheline Vectors in Malaria Endemic Area of Iran

    Directory of Open Access Journals (Sweden)

    Hamidreza Basseri

    2010-01-01

    Full Text Available Seasonal abundance and tendency to feed on humans are important parameters to measure for effective control of malaria vectors. The objective of this study was to describe relation between feeding pattern, abundance, and resting behavior of four malaria vectors in southern Iran. This study was conducted in ten indicator villages (based on malaria incidence and entomological indices in mountainous/hilly and plain regions situated south and southeastern Iran. Mosquito vectors were collected from indoor as well as outdoor shelters and the blood meals were examined by ELISA test. Over all 7654 female Anopheles spp. were captured, the most common species were Anopheles stephensi, An. culicifacies, An. fluviatilis, and An. d'thali. The overall human blood index was 37.50%, 19.83%, 16.4%, and 30.1% for An. fluviatilis, An. stephensi, An. culicifacies, and An. d'thali, respectively. In addition, An. fluviatilis fed on human blood during the entire year but the feeding behavior of An. stephensi and An. culicifacies varied according to seasons. Overall, the abundance of the female mosquito positive to human blood was 4.25% per human shelter versus 17.5% per animal shelter. This result indicates that the vectors had tendency to rest in animal shelters after feeding on human. Therefore, vector control measure should be planned based on such as feeding pattern, abundance, and resting behavior of these vectors in the area.

  10. Seasonal abundance of soil arthropods in relation to meteorological and edaphic factors in the agroecosystems of Faisalabad, Punjab, Pakistan.

    Science.gov (United States)

    Shakir, Muhammad Mussadiq; Ahmed, Sohail

    2015-05-01

    Soil arthropods are an important component of agroecosystems, contributing significantly to their biodiversity and functioning. However, seasonal patterns, population dynamics, and significant roles of these soil arthropods in improvement of soil structures and functions are influenced by many factors. The objective of the current study was to investigate soil arthropod abundance in relation to a blend of meteorological and edaphic factors and to find out the difference in abundance among various crops (sugarcane, cotton, wheat, alfalfa fodder, and citrus orchards). The arthropod sampling was done by pitfall traps and Tullgren extractions on fortnightly intervals. Soil temperature and relative humidity were noted on the field sites while analysis for soil pH, organic matter, and soil moisture contents were done in the laboratory. The rainfall data was obtained from an observatory. Results showed that significant differences were found in soil arthropod abundance across different sampling months and crops. Out of total 13,673 soil arthropods sampled, 38 % belonged to Collembola, followed by 15 % Hymenoptera, 15 % Acarina, 11 % Myriapods, 6 % Coleoptera, 5 % Orthoptera, and 5 % Araneae. Mean abundance per sample was highest in summer months as compared to winter. Overall abundance per sample was significantly different between all crops (p arthropods according to abundance, i.e., highly abundant (Collembola, Acarina, Myripoda, Hymenoptera), moderately abundant (Orthoptera, Aranae, Coleoptera), least abundant (Dermaptera, Hemiptera, Diptera), and rare (Blattaria, Isoptera, Diplura, Lepidoptera). Soil temperature and soil organic matter showed significant positive correlation with abundance, while relative humidity was significantly negatively correlated. Soil moisture and soil pH showed no significant correlations while no correlation was found with total rainfall. PCA analysis revealed that soil surface arthropods were the major contributors of variation in overall

  11. Seasonal dynamics of ichthyodiversity in a hill stream of the Darjeeling Himalaya, West Bengal, india

    Directory of Open Access Journals (Sweden)

    M.L. Acharjee

    2014-12-01

    Full Text Available The small torrential spring-fed hill-stream Relli in the Darjeeling Himalaya of West Bengal was studied from March 2007 to February 2009 to assess seasonal dynamics and diversity of fish populations.  The study revealed that the stream sustained 25 rheophilic cold water fish species from 15 genera and five families having ornamental, food and sport value.  Seven omnivorous species were abundantly found, and the array of juveniles and sub adults suggests this stream is used as a breeding and nursery ground for some species.  The stream harboured fish with unique modifications such as adhesive structures.  Analysis of monthly data indicate that abundance and diversity indices increased slightly during April–May and sharply during October–November, indicating significant seasonal variations with the low diversity observed during monsoon months reflecting environmental stresses.  Evenness was high in all sampling sites, and inversely related to the dominance index of ichthyofauna.  The density and diversity of fish assemblages along the gradient of the stream may be interrupted due to anthropogenic disturbances.  Our study provides baseline data which may be helpful for conservation and management of fish species, and in formulating fishery policy. 

  12. Structure, seasonal dynamics and distribution of zooplankton in lake Drukshiai in 1994

    International Nuclear Information System (INIS)

    Mazheikaite, S.; Pashkauskas, R.

    1995-01-01

    Investigations on the zooplankton of Lake Drukshiai were carried out in 1994. There were registered 62 taxons of protozoa and 50 taxons of metazoa, and compared with the data of 1979 - 1986 the diversity of species composition decreased 2.1 times. Eurytermic and stenothermic thermophylic species prevailed in the plankton biocenosis. In protozooplankton dominated ciliates of subclasses teolotricha and spirotricha, in metazooplankton -planctonic crustacea (Copopeda and Cladocera). Rotifers (Rotaria) were abundant only in the shallow and heated water outlet area. Seasonal dynamics of protozooplankton indicated one maximum in spring and metazooplankton - in summer. High diferentiation in quantity and biomass of zooplankton in the lake revealed different level of eutrophication of some areas. (author). 7 refs., 5 figs

  13. Seasonal abundance and potential of Japanese encephalitis virus infection in mosquitoes at the nesting colony of ardeid birds, Thailand.

    Science.gov (United States)

    Changbunjong, Tanasak; Weluwanarak, Thekhawet; Taowan, Namaoy; Suksai, Parut; Chamsai, Tatiyanuch; Sedwisai, Poonyapat

    2013-03-01

    To investigate the abundance and seasonal dynamics of mosquitoes, and to detect Japanese encephalitis virus (JEV) in these mosquitoes at the nesting colony of ardeid birds. Mosquitoes were collected bimonthly from July 2009 to May 2010 by Centers for Disease Control. Light traps and dry ice, as a source of CO2, were employed to attract mosquitoes. Mosquitoes were first identified, pooled into groups of upto 50 mosquitoes by species, and tested for JEV infection by viral isolation and reverse transcriptase polymerase chain reaction. A total of 20 370 mosquitoes comprising 14 species in five genera were collected. The five most abundant mosquito species collected were Culex tritaeniorhynchus (95.46%), Culex vishnui (2.68%), Culex gelidus (0.72%), Anopheles peditaeniatus (0.58%) and Culex quinquefasciatus (0.22%). Mosquito peak densities were observed in July. All of 416 mosquito pools were negative for JEV. This study provides new information about mosquito species and status of JEV infection in mosquitoes in Thailand. Further study should be done to continue a close survey for the presence of this virus in the ardeid birds.

  14. Seasonal variation in copepod abundance in relation to other zooplanktonic groups in the northwestern Mediterranean

    NARCIS (Netherlands)

    Kouwenberg, Juliana H.M.

    1993-01-01

    Abundance of adult copepods and late copepodid stages from the upper 50 m in the Golfe du Lion (N.W. Mediterranean) was studied by the author in 1986, 1987, and 1988 for each season. Altogether 87 stations at 22 fixed locations were sampled in the frame of the multidisciplinary French/Spanish

  15. Effects of seasonality on drosophilids (Insecta, Diptera) in the northern part of the Atlantic Forest, Brazil.

    Science.gov (United States)

    Coutinho-Silva, R D; Montes, M A; Oliveira, G F; de Carvalho-Neto, F G; Rohde, C; Garcia, A C L

    2017-10-01

    Seasonality is an important aspect associated with population dynamic and structure of tropical insect assemblages. This study evaluated the effects of seasonality on abundance, richness, diversity and composition of an insect group, drosophilids, including species native to the Neotropical region and exotic ones. Three preserved fragments of the northern Atlantic Forest were surveyed, where temperatures are above 20 °C throughout the year and rainfall regimes define two seasons (dry and rainy). As opposed to other studies about arthropods in tropical regions, we observed that abundance of drosophilids was significantly higher in the dry season, possibly due to biological aspects and the colonization strategy adopted by the exotic species in these environments. Contrarily to abundance, we did not observe a seasonal pattern for richness. As for other parts of the Atlantic Forest, the most representative Neotropical species (Drosophila willistoni, D. sturtevanti, D. paulistorum and D. prosaltans) were significantly more abundant in the rainy season. Among the most abundant exotic species, D. malerkotliana, Zaprionus indianus and Scaptodrosophila latifasciaeformis were more importantly represented the dry season, while D. simulans was more abundant in the rainy period. The seasonality patterns exhibited by the most abundant species were compared to findings published in other studies. Our results indicate that exotic species were significantly more abundant in the dry season, while native ones exhibited an opposite pattern.

  16. The hidden seasonality of the rare biosphere in coastal marine bacterioplankton

    KAUST Repository

    Alonso-Sáez, Laura

    2015-04-08

    Summary: Rare microbial taxa are increasingly recognized to play key ecological roles, but knowledge of their spatio-temporal dynamics is lacking. In a time-series study in coastal waters, we detected 83 bacterial lineages with significant seasonality, including environmentally relevant taxa where little ecological information was available. For example, Verrucomicrobia had recurrent maxima in summer, while the Flavobacteria NS4, NS5 and NS2b clades had contrasting seasonal niches. Among the seasonal taxa, only 4 were abundant and persistent, 20 cycled between rare and abundant and, remarkably, most of them (59) were always rare (contributing <1% of total reads). We thus demonstrate that seasonal patterns in marine bacterioplankton are largely driven by lineages that never sustain abundant populations. A fewer number of rare taxa (20) also produced episodic \\'blooms\\', and these events were highly synchronized, mostly occurring on a single month. The recurrent seasonal growth and loss of rare bacteria opens new perspectives on the temporal dynamics of the rare biosphere, hitherto mainly characterized by dormancy and episodes of \\'boom and bust\\', as envisioned by the seed-bank hypothesis. The predictable patterns of seasonal reoccurrence are relevant for understanding the ecology of rare bacteria, which may include key players for the functioning of marine ecosystems. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  17. Seasonal dynamics of butterfly population in DAE Campus, Kalpakkam, Tamil Nadu, India

    Directory of Open Access Journals (Sweden)

    K.J. Hussain

    2011-01-01

    Full Text Available Seasonal population trends of butterflies inhabiting the campus of Department of Atomic Energy (DAE at Kalpakkam were recorded by setting a permanent line transect of 300m and recording all species of butterflies observed within a 5m distance. The survey yielded 2177 individuals of 56 butterfly species, belonging to the families Nymphalidae, Pieridae, Lycaenidae, Papilionidae and Hesperiidae. Nymphalidae were found to be the dominant family during all seasons. Species richness and abundance were highest during the northeast monsoon and winter periods, indicating that in the southern plains of India butterflies prefer cool seasons for breeding and emergence. The taxonomic structure of the butterflies sampled resembles that of the Western Ghats and other regions of India in two ways: (a dominance of nymphalids and (b peak abundance during wet seasons. A detailed study of ecologically important local butterfly fauna and their host plants is in progress, to construct a butterfly garden in Kalpakkam to attract and support butterflies.

  18. Demographic processes in a local population: seasonal dynamics of ...

    African Journals Online (AJOL)

    ... differences in daily recruitment and within-patch survival rates. Males were most abundant relative to females early in the season, indicating protandry. Total adult population size was small and showed dramatic variation between the two years, indicating how vulnerable the local population is to demographic extinction.

  19. Seasonal abundance of soil arthropods in relation to meteorological and edaphic factors in the agroecosystems of Faisalabad, Punjab, Pakistan

    Science.gov (United States)

    Shakir, Muhammad Mussadiq; Ahmed, Sohail

    2015-05-01

    Soil arthropods are an important component of agroecosystems, contributing significantly to their biodiversity and functioning. However, seasonal patterns, population dynamics, and significant roles of these soil arthropods in improvement of soil structures and functions are influenced by many factors. The objective of the current study was to investigate soil arthropod abundance in relation to a blend of meteorological and edaphic factors and to find out the difference in abundance among various crops (sugarcane, cotton, wheat, alfalfa fodder, and citrus orchards). The arthropod sampling was done by pitfall traps and Tullgren extractions on fortnightly intervals. Soil temperature and relative humidity were noted on the field sites while analysis for soil pH, organic matter, and soil moisture contents were done in the laboratory. The rainfall data was obtained from an observatory. Results showed that significant differences were found in soil arthropod abundance across different sampling months and crops. Out of total 13,673 soil arthropods sampled, 38 % belonged to Collembola, followed by 15 % Hymenoptera, 15 % Acarina, 11 % Myriapods, 6 % Coleoptera, 5 % Orthoptera, and 5 % Araneae. Mean abundance per sample was highest in summer months as compared to winter. Overall abundance per sample was significantly different between all crops ( p Aranae, Coleoptera), least abundant (Dermaptera, Hemiptera, Diptera), and rare (Blattaria, Isoptera, Diplura, Lepidoptera). Soil temperature and soil organic matter showed significant positive correlation with abundance, while relative humidity was significantly negatively correlated. Soil moisture and soil pH showed no significant correlations while no correlation was found with total rainfall. PCA analysis revealed that soil surface arthropods were the major contributors of variation in overall abundance in extreme temperature months while microarthropods in low-temperature months. CCA analysis revealed the occurrence of

  20. Population and evolutionary dynamics in spatially structured seasonally varying environments.

    Science.gov (United States)

    Reid, Jane M; Travis, Justin M J; Daunt, Francis; Burthe, Sarah J; Wanless, Sarah; Dytham, Calvin

    2018-03-25

    Increasingly imperative objectives in ecology are to understand and forecast population dynamic and evolutionary responses to seasonal environmental variation and change. Such population and evolutionary dynamics result from immediate and lagged responses of all key life-history traits, and resulting demographic rates that affect population growth rate, to seasonal environmental conditions and population density. However, existing population dynamic and eco-evolutionary theory and models have not yet fully encompassed within-individual and among-individual variation, covariation, structure and heterogeneity, and ongoing evolution, in a critical life-history trait that allows individuals to respond to seasonal environmental conditions: seasonal migration. Meanwhile, empirical studies aided by new animal-tracking technologies are increasingly demonstrating substantial within-population variation in the occurrence and form of migration versus year-round residence, generating diverse forms of 'partial migration' spanning diverse species, habitats and spatial scales. Such partially migratory systems form a continuum between the extreme scenarios of full migration and full year-round residence, and are commonplace in nature. Here, we first review basic scenarios of partial migration and associated models designed to identify conditions that facilitate the maintenance of migratory polymorphism. We highlight that such models have been fundamental to the development of partial migration theory, but are spatially and demographically simplistic compared to the rich bodies of population dynamic theory and models that consider spatially structured populations with dispersal but no migration, or consider populations experiencing strong seasonality and full obligate migration. Second, to provide an overarching conceptual framework for spatio-temporal population dynamics, we define a 'partially migratory meta-population' system as a spatially structured set of locations that can

  1. Co-existence of Anaerobic Ammonium Oxidation Bacteria and Denitrifying Anaerobic Methane Oxidation Bacteria in Sewage Sludge: Community Diversity and Seasonal Dynamics.

    Science.gov (United States)

    Xu, Sai; Lu, Wenjing; Mustafa, Muhammad Farooq; Caicedo, Luis Miguel; Guo, Hanwen; Fu, Xindi; Wang, Hongtao

    2017-11-01

    Anaerobic ammonium oxidation (ANAMMOX) and denitrifying anaerobic methane oxidation (DAMO) have been recently discovered as relevant processes in the carbon and nitrogen cycles of wastewater treatment plants. In this study, the seasonal dynamics of ANAMMOX and DAMO bacterial community structures and their abundance in sewage sludge collected from wastewater treatment plants were analysed. Results indicated that ANAMMOX and DAMO bacteria co-existed in sewage sludge in different seasons and their abundance was positively correlated (P bacteria in autumn and winter indicated that these seasons were the preferred time to favour the growth of ANAMMOX and DAMO bacteria. The community structure of ANNAMOX and DAMO bacteria could also shift with seasonal changes. The "Candidatus Brocadia" genus of ANAMMOX bacteria was mainly recovered in spring and summer, and an unknown cluster was primarily detected in autumn and winter. Similar patterns of seasonal variation in the community structure of DAMO bacteria were also observed. Group B was the dominant in spring and summer, whereas in autumn and winter, group A and group B presented almost the same proportion. The redundancy analysis revealed that pH and nitrate were the most significant factors affecting community structures of these two groups (P < 0.01). This study reported the diversity of ANAMMOX and DAMO in wastewater treatment plants that may be the basis for new nitrogen removal technologies.

  2. Seasonal abundance and activity of pill millipedes ( Arthrosphaera magna) in mixed plantation and semi-evergreen forest of southern India

    Science.gov (United States)

    Ashwini, Krishna M.; Sridhar, Kandikere R.

    2006-01-01

    Seasonal occurrence and activity of endemic pill millipedes ( Arthrosphaera magna) were examined in organically managed mixed plantation and semi-evergreen forest reserve in southwest India between November 1996 and September 1998. Abundance and biomass of millipedes were highest in both habitats during monsoon season. Soil moisture, conductivity, organic carbon, phosphate, potassium, calcium and magnesium were higher in plantation than in forest. Millipede abundance and biomass were about 12 and 7 times higher in plantation than in forest, respectively ( P 0.05). Millipede abundance and biomass were positively correlated with rainfall ( P = 0.01). Besides rainfall, millipedes in plantation were positively correlated with soil moisture as well as temperature ( P = 0.001). Among the associated fauna with pill millipedes, earthworms rank first followed by soil bugs in both habitats. Since pill millipedes are sensitive to narrow ecological changes, the organic farming strategies followed in mixed plantation and commonly practiced in South India seem not deleterious for the endangered pill millipedes Arthrosphaera and reduce the risk of local extinctions.

  3. Landscape seasons and air mass dynamics in Latvia

    International Nuclear Information System (INIS)

    Krauklis, A.; Draveniece, A.

    2004-01-01

    Latvia is located in the middle of an area where the boreal and nemoral zones and the regions of oceanic and continental climate meet, and it was studied as a model territory of the most typical variation of boreo-nemoral ecotone. The subject of this study was seasonal dynamics of the state of landscapes and diachronous links between seasons. It was found that landscapes undergo 12 seasonal states or seasons during the annual cycle of insulation and air mass occurrence. Each season may be distinguished by a definite amount of solar radiation, distinctive state of heat and water balance, phenological state of vegetation, and a distinctive occurrence of different air mass types and their particular 'association'. During each season these variables show a particular combination of numerical values and a distinctive landscape pattern

  4. Seasonal differences in extinction and colonization drive occupancy dynamics of an imperilled amphibian.

    Directory of Open Access Journals (Sweden)

    Lea A Randall

    Full Text Available A detailed understanding of the population dynamics of many amphibian species is lacking despite concerns about declining amphibian biodiversity and abundance. This paper explores temporal patterns of occupancy and underlying extinction and colonization dynamics in a regionally imperiled amphibian species, the Northern leopard frog (Lithobates pipiens in Alberta. Our study contributes to elucidating regional occupancy dynamics at northern latitudes, where climate extremes likely have a profound effect on seasonal occupancy. The primary advantage of our study is its wide geographic scale (60,000 km2 and the use of repeat visual surveys each spring and summer from 2009-2013. We find that occupancy varied more dramatically between seasons than years, with low spring and higher summer occupancy. Between spring and summer, colonization was high and extinction low; inversely, colonization was low and extinction high over the winter. The dynamics of extinction and colonization are complex, making conservation management challenging. Our results reveal that Northern leopard frog occupancy was constant over the last five years and thus there is no evidence of decline or recovery within our study area. Changes to equilibrium occupancy are most sensitive to increasing colonization in the spring or declining extinction in the summer. Therefore, conservation and management efforts should target actions that are likely to increase spring colonization; this could be achieved through translocations or improving the quality or access to breeding habitat. Because summer occupancy is already high, it may be difficult to improve further. Nevertheless, summer extinction could be reduced by predator control, increasing water quality or hydroperiod of wetlands, or increasing the quality or quantity of summer habitat.

  5. Seasonal differences in extinction and colonization drive occupancy dynamics of an imperilled amphibian.

    Science.gov (United States)

    Randall, Lea A; Smith, Des H V; Jones, Breana L; Prescott, David R C; Moehrenschlager, Axel

    2015-01-01

    A detailed understanding of the population dynamics of many amphibian species is lacking despite concerns about declining amphibian biodiversity and abundance. This paper explores temporal patterns of occupancy and underlying extinction and colonization dynamics in a regionally imperiled amphibian species, the Northern leopard frog (Lithobates pipiens) in Alberta. Our study contributes to elucidating regional occupancy dynamics at northern latitudes, where climate extremes likely have a profound effect on seasonal occupancy. The primary advantage of our study is its wide geographic scale (60,000 km2) and the use of repeat visual surveys each spring and summer from 2009-2013. We find that occupancy varied more dramatically between seasons than years, with low spring and higher summer occupancy. Between spring and summer, colonization was high and extinction low; inversely, colonization was low and extinction high over the winter. The dynamics of extinction and colonization are complex, making conservation management challenging. Our results reveal that Northern leopard frog occupancy was constant over the last five years and thus there is no evidence of decline or recovery within our study area. Changes to equilibrium occupancy are most sensitive to increasing colonization in the spring or declining extinction in the summer. Therefore, conservation and management efforts should target actions that are likely to increase spring colonization; this could be achieved through translocations or improving the quality or access to breeding habitat. Because summer occupancy is already high, it may be difficult to improve further. Nevertheless, summer extinction could be reduced by predator control, increasing water quality or hydroperiod of wetlands, or increasing the quality or quantity of summer habitat.

  6. Highly diverse molluscan assemblages of Posidonia oceanica meadows in northwestern Alboran Sea (W Mediterranean): Seasonal dynamics and environmental drivers

    Science.gov (United States)

    Urra, Javier; Mateo Ramírez, Ángel; Marina, Pablo; Salas, Carmen; Gofas, Serge; Rueda, José L.

    2013-01-01

    The seasonal dynamics of the molluscan fauna associated with the westernmost populations of the Mediterranean seagrass Posidonia oceanica, has been studied throughout an annual cycle in the northwestern coasts of the Alboran Sea. Samples were collected seasonally (5 replicated per season) using a non-destructive sampling technique (airlift sampler) on quadrats of 50 × 50 cm at 2 sites located 7 km apart. Several environmental variables from the water column (temperature, chlorophyll a), the sediment (percentage of organic matter) and the seagrass meadows (shoot density, leaf height and width, number of leaves per shoot) were also measured in order to elucidate their relationships with the dynamics of the molluscan assemblages. In these meadows, a total of 17,416 individuals of molluscs were collected, belonging to 71 families and 171 species, being Rissoidae, Pyramidellidae and Trochidae the best-represented families, and Mytilidae, Nassaridae and Trochidae the dominant ones in terms of abundance. The assemblages were dominated by micro-algal grazers, filter feeders and ectoparasites (including those feeding on sessile preys). The species richness and the abundance displayed significant maximum values in summer, whereas evenness and diversity displayed maximum values in spring, being significant for the evenness. Both abundance and species richness values were positively correlated to seawater temperature and percentage organic matter, only for the latter, and negatively to leaf width. Significant seasonal groupings were obtained with multivariate analyses (MDS, Cluster, ANOSIM) using qualitative and quantitative data that could be mainly related to biological aspects (i.e. recruitment) of single species. The molluscan assemblages are influenced by the biogeographical location of the area (Alboran Sea), reflected in the absence or scarcity of most Mediterranean species strictly associated with P. oceanica (e.g. Tricolia speciosa, Rissoa ventricosa) and by the

  7. Seasonal and spatial variations in heterotrophic nanoflagellate and bacteria abundances in sediments of a freshwater littoral zone

    NARCIS (Netherlands)

    Starink, Mathieu; Bär-Gilissen, M.J.; Cappenberg, T.E.

    1996-01-01

    We studied seasonal variation in heterotrophic nanoflagellates (HNAN) and bacterial, densities at different depths in the sediment of two freshwater littoral stations. Station 1 was in a reed bed of Phragmites australis; station 2 was outside the reed zone in open water. Benthic HNAN abundances

  8. Seasonal dynamics of the plant community and soil seed bank along a successional gradient in a subalpine meadow on the Tibetan Plateau.

    Directory of Open Access Journals (Sweden)

    Miaojun Ma

    Full Text Available BACKGROUND: Knowledge about how change the importance of soil seed bank and relationship between seed mass and abundance during vegetation succession is crucial for understanding vegetation dynamics. Many studies have been conducted, but their ecological mechanisms of community assembly are not fully understood. METHODOLOGY: We examined the seasonal dynamics of the vegetation and soil seed bank as well as seed size distribution along a successional gradient. We also explored the potential role of the soil seed bank in plant community regeneration, the relationship between seed mass and species abundance, and the relative importance of deterministic and stochastic processes along a successional gradient. PRINCIPAL FINDINGS: Species richness of seed bank increased (shallow layer and the total and seed density decreased (each layer and the total significantly with succession. Species richness and seed density differed significantly between different seasons and among soil depths. Seed mass showed a significant negative relationship with relative abundance in the earliest successional stage, but the relationships were not significant in later stages. Seed mass showed no relationship with relative abundance in the whole successional series in seed bank. Results were similar for both July 2005 and April 2006. CONCLUSIONS: The seed mass and abundance relationship was determined by a complex interaction between small and larger seeded species and environmental factors. Both stochastic processes and deterministic processes were important determinants of the structure of the earliest stage. The importance of seed bank decreased with succession. The restoration of abandoned farmed and grazed meadows to the species-rich subalpine meadow in Tibetan Plateau can be successfully achieved from the soil seed bank. However, at least 20 years are required to fully restore an abandoned agricultural meadow to a natural mature subalpine meadow.

  9. Dynamical characteristics of the seasonal circulations over the Korea peninsula

    International Nuclear Information System (INIS)

    1989-10-01

    This paper reports dynamical characteristics of the seasonal circulations over the Korean peninsula. It consists of summary, research method, result, consideration and conclusion. It introduces the method of research ; characteristics of circulation over seasonal wind in Asia, characteristic of upper jet stream related cold wave and monsoon in East Asia and dynamics of pulsation and maintain of high atmospheric pressure in siberia in winter. It was reported by Korea science foundation in 1989.

  10. Seasonal Distribution and Historic Trends in Abundance of White Sharks, Carcharodon carcharias, in the Western North Atlantic Ocean

    Science.gov (United States)

    Curtis, Tobey H.; McCandless, Camilla T.; Carlson, John K.; Skomal, Gregory B.; Kohler, Nancy E.; Natanson, Lisa J.; Burgess, George H.; Hoey, John J.; Pratt, Harold L.

    2014-01-01

    Despite recent advances in field research on white sharks (Carcharodon carcharias) in several regions around the world, opportunistic capture and sighting records remain the primary source of information on this species in the northwest Atlantic Ocean (NWA). Previous studies using limited datasets have suggested a precipitous decline in the abundance of white sharks from this region, but considerable uncertainty in these studies warrants additional investigation. This study builds upon previously published data combined with recent unpublished records and presents a synthesis of 649 confirmed white shark records from the NWA compiled over a 210-year period (1800-2010), resulting in the largest white shark dataset yet compiled from this region. These comprehensive records were used to update our understanding of their seasonal distribution, relative abundance trends, habitat use, and fisheries interactions. All life stages were present in continental shelf waters year-round, but median latitude of white shark occurrence varied seasonally. White sharks primarily occurred between Massachusetts and New Jersey during summer and off Florida during winter, with broad distribution along the coast during spring and fall. The majority of fishing gear interactions occurred with rod and reel, longline, and gillnet gears. Historic abundance trends from multiple sources support a significant decline in white shark abundance in the 1970s and 1980s, but there have been apparent increases in abundance since the 1990s when a variety of conservation measures were implemented. Though the white shark's inherent vulnerability to exploitation warrants continued protections, our results suggest a more optimistic outlook for the recovery of this iconic predator in the Atlantic. PMID:24918579

  11. Seasonal variations of phytoplankton dynamics in Nunatsiavut fjords (Labrador, Canada) and their relationships with environmental conditions

    Science.gov (United States)

    Simo-Matchim, Armelle-Galine; Gosselin, Michel; Blais, Marjolaine; Gratton, Yves; Tremblay, Jean-Éric

    2016-04-01

    We assessed phytoplankton dynamics and its environmental control in four Labrador fjords (Nachvak, Saglek, Okak, and Anaktalak) during summer, early fall and late fall. Primary production and chlorophyll a (chl a) biomass were measured at seven optical depths, including the depth of subsurface chl a maximum (SCM). Phytoplankton abundance, size structure and taxonomy were determined at the SCM. Principal component analysis and non-metric multidimensional scaling were used to analyze relationships between production, biomass and community composition in relation to environmental variables. We observed a marked seasonal variability, with significant differences in phytoplankton structure and function between summer and fall. Surprisingly, primary production and chl a biomass were not significantly different from one fjord to another. The highest values of primary production (1730 mg C m- 2 day- 1) and chl a biomass (96 mg chl a m- 2) were measured during the summer bloom, and those high values indicate that Labrador fjords are highly productive ecosystems. The summer community showed relatively high abundance of nanophytoplankton (2-20 μm) while the fall community was characterized by low primary production and chl a biomass as well as relatively high abundance of picophytoplankton (< 2 μm). The low value of carbon potentially exported out of the euphotic zone throughout the study (≤ 31% of total primary production) suggests that phytoplankton production was mainly grazed by microzooplankton rather than being exported to greater depths. We observed a mixed assemblage of diatoms and flagellates in summer, whereas the fall community was largely dominated by flagellates. Seasonal variations in phytoplankton dynamics were mainly controlled by the strength of the vertical stratification and by the large differences in day length due to the northerly location of Labrador fjords. This study documents for the very first time phytoplankton structure and function in

  12. An integrated data model to estimate spatiotemporal occupancy, abundance, and colonization dynamics

    Science.gov (United States)

    Williams, Perry J.; Hooten, Mevin B.; Womble, Jamie N.; Esslinger, George G.; Bower, Michael R.; Hefley, Trevor J.

    2017-01-01

    Ecological invasions and colonizations occur dynamically through space and time. Estimating the distribution and abundance of colonizing species is critical for efficient management or conservation. We describe a statistical framework for simultaneously estimating spatiotemporal occupancy and abundance dynamics of a colonizing species. Our method accounts for several issues that are common when modeling spatiotemporal ecological data including multiple levels of detection probability, multiple data sources, and computational limitations that occur when making fine-scale inference over a large spatiotemporal domain. We apply the model to estimate the colonization dynamics of sea otters (Enhydra lutris) in Glacier Bay, in southeastern Alaska.

  13. A Theoretical Approach to Understanding Population Dynamics with Seasonal Developmental Durations

    Science.gov (United States)

    Lou, Yijun; Zhao, Xiao-Qiang

    2017-04-01

    There is a growing body of biological investigations to understand impacts of seasonally changing environmental conditions on population dynamics in various research fields such as single population growth and disease transmission. On the other side, understanding the population dynamics subject to seasonally changing weather conditions plays a fundamental role in predicting the trends of population patterns and disease transmission risks under the scenarios of climate change. With the host-macroparasite interaction as a motivating example, we propose a synthesized approach for investigating the population dynamics subject to seasonal environmental variations from theoretical point of view, where the model development, basic reproduction ratio formulation and computation, and rigorous mathematical analysis are involved. The resultant model with periodic delay presents a novel term related to the rate of change of the developmental duration, bringing new challenges to dynamics analysis. By investigating a periodic semiflow on a suitably chosen phase space, the global dynamics of a threshold type is established: all solutions either go to zero when basic reproduction ratio is less than one, or stabilize at a positive periodic state when the reproduction ratio is greater than one. The synthesized approach developed here is applicable to broader contexts of investigating biological systems with seasonal developmental durations.

  14. Fire decreases arthropod abundance but increases diversity: Early and late season prescribed fire effects in a Sierra Nevada mixed-conifer forest

    Science.gov (United States)

    Ferrenberg, Scott; Schwilk, Dylan W.; Knapp, Eric E.; Groth, Eric; Keeley, Jon E.

    2006-01-01

    Prior to fire suppression in the 20th century, the mixed-conifer forests of the Sierra Nevada, California, U.S.A., historically burned in frequent fires that typically occurred during the late summer and early fall. Fire managers have been attempting to restore natural ecosystem processes through prescription burning, and have often favored burning during the fall in order to mimic historical fire regimes. Increasingly, however, prescription burning is also being done during the late spring and early summer in order to expand the window of opportunity for needed fuel reduction burning. The effect of prescribed fires outside of the historical fire season on forest arthropods is not known. The objective of this study was to compare the short-term effects of prescribed fires ignited in the early and late fire season on forest floor arthropods. Arthropod abundance and diversity were assessed using pitfall trapping in replicated burn units in Sequoia National Park, California. Overall, abundance of arthropods was lower in the burn treatments than in the unburned control. However, diversity tended to be greater in the burn treatments. Fire also altered the relative abundances of arthropod feeding guilds. No significant differences in arthropod community structure were found between early and late season burn treatments. Instead, changes in the arthropod community appeared to be driven largely by changes in fuel loading, vegetation, and habitat heterogeneity, all of which differed more between the burned and unburned treatments than between early and late season burn treatments.

  15. Seasonal variation of zooplankton abundance and community structure in Prince William Sound, Alaska, 2009-2016

    Science.gov (United States)

    McKinstry, Caitlin A. E.; Campbell, Robert W.

    2018-01-01

    Large calanoid copepods and other zooplankters comprise the prey field for ecologically and economically important predators such as juvenile pink salmon, herring, and seabirds in Prince William Sound (PWS).​ From 2009-2016, the Gulf Watch Alaska program collected zooplankton 5-10 times each year at 12 stations in PWS to establish annual patterns. Surveys collected 188 species of zooplankton with Oithona similis, Limacina helicina, Pseudocalanus spp., and Acartia longiremis as the most common species present in 519 samples. Generalized additive models assessed seasonal abundance and showed peak abundance in July (mean: 9826 no. m-3 [95% CI: 7990-12,084]) and lowest abundance in January (503 no. m-3 [373 to 678]). Significantly higher zooplankton abundance occurred in 2010 (542 no. m-3 ± 55 SE) and lowest in 2013 (149 no. m-3 ± 13). The species composition of communities, determined via hierarchical cluster analysis and indicator species analysis, produced six distinct communities based on season and location. The winter community, characterized by warm-water indicator species including Mesocalanus tenuicornis, Calanus pacificus, and Corycaeus anglicus, diverged into four communities throughout the spring and summer. The first spring community, characterized by copepods with affinities for lower salinities, occurred sound-wide. The second spring community, comprised of planktonic larvae, appeared sporadically in PWS bays in 2011-2013. Spring and summer open water stations were defined by the presence of large calanoid copepods. A summer community including the most abundant taxa was common in 2010 and 2011, absent in 2013, then sporadically appeared in 2014 and 2015 suggesting interannual variability of zooplankton assemblages. The zooplankton community shifted to a uniform assemblage characterized by cnidarians in the early autumn. Community assemblages showed significant correlations to a set of environmental variables including SST, mixed layer depth

  16. Tree species, spatial heterogeneity, and seasonality drive soil fungal abundance, richness, and composition in Neotropical rainforests.

    Science.gov (United States)

    Kivlin, Stephanie N; Hawkes, Christine V

    2016-12-01

    Tropical ecosystems remain poorly understood and this is particularly true for belowground soil fungi. Soil fungi may respond to plant identity when, for example, plants differentially allocate resources belowground. However, spatial and temporal heterogeneity in factors such as plant inputs, moisture, or nutrients can also affect fungal communities and obscure our ability to detect plant effects in single time point studies or within diverse forests. To address this, we sampled replicated monocultures of four tree species and secondary forest controls sampled in the drier and wetter seasons over 2 years. Fungal community composition was primarily related to vegetation type and spatial heterogeneity in the effects of vegetation type, with increasing divergence partly reflecting greater differences in soil pH and soil moisture. Across wetter versus drier dates, fungi were 7% less diverse, but up to four-fold more abundant. The combined effects of tree species and seasonality suggest that predicted losses of tropical tree diversity and intensification of drought have the potential to cascade belowground to affect both diversity and abundance of tropical soil fungi. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  17. Seasonal distribution and historic trends in abundance of white sharks, Carcharodon carcharias, in the western North Atlantic Ocean.

    Directory of Open Access Journals (Sweden)

    Tobey H Curtis

    Full Text Available Despite recent advances in field research on white sharks (Carcharodon carcharias in several regions around the world, opportunistic capture and sighting records remain the primary source of information on this species in the northwest Atlantic Ocean (NWA. Previous studies using limited datasets have suggested a precipitous decline in the abundance of white sharks from this region, but considerable uncertainty in these studies warrants additional investigation. This study builds upon previously published data combined with recent unpublished records and presents a synthesis of 649 confirmed white shark records from the NWA compiled over a 210-year period (1800-2010, resulting in the largest white shark dataset yet compiled from this region. These comprehensive records were used to update our understanding of their seasonal distribution, relative abundance trends, habitat use, and fisheries interactions. All life stages were present in continental shelf waters year-round, but median latitude of white shark occurrence varied seasonally. White sharks primarily occurred between Massachusetts and New Jersey during summer and off Florida during winter, with broad distribution along the coast during spring and fall. The majority of fishing gear interactions occurred with rod and reel, longline, and gillnet gears. Historic abundance trends from multiple sources support a significant decline in white shark abundance in the 1970s and 1980s, but there have been apparent increases in abundance since the 1990s when a variety of conservation measures were implemented. Though the white shark's inherent vulnerability to exploitation warrants continued protections, our results suggest a more optimistic outlook for the recovery of this iconic predator in the Atlantic.

  18. Small mammal use of native warm-season and non-native cool-season grass forage fields

    Science.gov (United States)

    Ryan L Klimstra,; Christopher E Moorman,; Converse, Sarah J.; Royle, J. Andrew; Craig A Harper,

    2015-01-01

    Recent emphasis has been put on establishing native warm-season grasses for forage production because it is thought native warm-season grasses provide higher quality wildlife habitat than do non-native cool-season grasses. However, it is not clear whether native warm-season grass fields provide better resources for small mammals than currently are available in non-native cool-season grass forage production fields. We developed a hierarchical spatially explicit capture-recapture model to compare abundance of hispid cotton rats (Sigmodon hispidus), white-footed mice (Peromyscus leucopus), and house mice (Mus musculus) among 4 hayed non-native cool-season grass fields, 4 hayed native warm-season grass fields, and 4 native warm-season grass-forb ("wildlife") fields managed for wildlife during 2 summer trapping periods in 2009 and 2010 of the western piedmont of North Carolina, USA. Cotton rat abundance estimates were greater in wildlife fields than in native warm-season grass and non-native cool-season grass fields and greater in native warm-season grass fields than in non-native cool-season grass fields. Abundances of white-footed mouse and house mouse populations were lower in wildlife fields than in native warm-season grass and non-native cool-season grass fields, but the abundances were not different between the native warm-season grass and non-native cool-season grass fields. Lack of cover following haying in non-native cool-season grass and native warm-season grass fields likely was the key factor limiting small mammal abundance, especially cotton rats, in forage fields. Retention of vegetation structure in managed forage production systems, either by alternately resting cool-season and warm-season grass forage fields or by leaving unharvested field borders, should provide refugia for small mammals during haying events.

  19. Dynamic N -occupancy models: estimating demographic rates and local abundance from detection-nondetection data

    Science.gov (United States)

    Sam Rossman; Charles B. Yackulic; Sarah P. Saunders; Janice Reid; Ray Davis; Elise F. Zipkin

    2016-01-01

    Occupancy modeling is a widely used analytical technique for assessing species distributions and range dynamics. However, occupancy analyses frequently ignore variation in abundance of occupied sites, even though site abundances affect many of the parameters being estimated (e.g., extinction, colonization, detection probability). We introduce a new model (“dynamic

  20. Seasonality in the Mesozooplankton Community of Delaware Bay, USA

    Science.gov (United States)

    Wickline, A.; Cohen, J.

    2016-02-01

    Zooplankton communities in temperate estuaries undergo seasonal shifts in abundance and species composition, though the physical/biological mechanisms behind these shifts vary among systems. Delaware Bay is a well-mixed estuary on the mid-Atlantic coast with predictable seasonal variation in environmental conditions and circulation. To understand factors influencing mesozooplankton community dynamics in this system, we conducted seasonal sampling at 16 stations over the estuary's salinity range in 2014-2015. Sampling paralleled the last similar investigation into Delaware Bay zooplankton, conducted in the early 1950s. Biomass, measured as dry weight and totaled for all stations, was low in late summer and high in spring and fall. Bio-volume, measured either as displacement volume or calculated from ZooScan processing to exclude detritus, also showed a similar pattern. Across seasons, the mesozooplankton community was dominated by copepods, representing over 60% of the relative abundance at each station. Acartia tonsa was the dominant calanoid species in summer and fall, with abundances up to 7,353 ind. m-3, which is similar to the 1950s. In spring, Centropages hamatus and C. typicus were dominant at densities up to 2,550 ind. m-3 throughout the estuary, which is an increase from the 1950s. Environmental data suggest the seasonal shift in dominance from neritic Centropages to estuarine Acartia could be driven by increased stratification of the estuary during periods of high river discharge in spring, creating a two-layer system with a bottom advection current fed by the coastal ocean, bringing coastal species into the estuary. As river discharge decreases, the advection current is reduced, creating a well-mixed estuary and allowing Acartia to dominante. As river discharge is ultimately determined by precipitation, which is predicted to increase during winter with climate change in this region, the phenology of mesozooplankton species dynamics could shift as well.

  1. Seasonal and interannual variations in coccolithophore abundance off Terceira Island, Azores (Central North Atlantic)

    Science.gov (United States)

    Narciso, Áurea; Gallo, Francesca; Valente, André; Cachão, Mário; Cros, Lluïsa; Azevedo, Eduardo B.; e Ramos, Joana Barcelos

    2016-04-01

    In order to characterize the natural coccolithophore community occurring offshore Azores and to determine their annual and interannual patterns, monthly samples were collected, from September 2010 to December 2014, in the photic zone off Terceira Island. The present study revealed a clear seasonal distribution and a considerable interannual variability of the living coccolithophore community. The highest coccolithophore abundances were observed during spring and winter months, especially due to the smaller species Emiliania huxleyi and Gephyrocapsa ericsonii. In fact, the highest biomass period was registered during April 2011, associated with enhanced abundance of the overcalcified morphotype of E. huxleyi, which was possibly influenced by subpolar waters and subsequent upwelling conditions. The highest abundances of Gephyrocapsa muellerae were recorded during June 2011 and 2014, indicating that this species characterizes the transition between the period of maximum productivity and the subsequent smoother environmental conditions, the first and the later stages of the phytoplankton succession described by Margalef, respectively. During summer to early fall, a gradual decrease of the overall coccolithophore abundance was observed, while the species richness (Margalef diversity index) increased. A subtropical coccolithophore assemblage mainly composed by Umbellosphaera tenuis, Syracosphaera spp., Discosphaera tubifera, Rhabdosphaera clavigera and Coronosphaera mediterranea indicated the presence of surface warmer waters accompanied by reduced mixing and low nutrients concentration. During late fall to winter, the coccolithophore abundance increased again with a concomitant reduction in species diversity. This is potentially linked to low sea surface temperatures, moderate nutrients concentration and surface mixed layer deepening. During 2011, colder and productive waters led to an increase in the total coccolithophore abundances. On contrary, during 2012

  2. Coral reef fish assemblages along a disturbance gradient in the northern Persian Gulf: A seasonal perspective.

    Science.gov (United States)

    Ghazilou, Amir; Shokri, Mohammad Reza; Gladstone, William

    2016-04-30

    Seasonal dynamics of coral reef fish assemblages were assessed along a gradient of potential anthropogenic disturbance in the Northern Persian Gulf. Overall, the attributes of coral reef fish assemblages showed seasonality at two different levels: seasonal changes irrespective of the magnitude of disturbance level (e.g. species richness), and seasonal changes in response to disturbance level (e.g. total abundance and assemblage composition). The examined parameters mostly belonged to the second group, but the interpretation of the relationship between patterns of seasonal changes and the disturbance level was not straightforward. The abundance of carnivorous fishes did not vary among seasons. SIMPER identified the family Nemipteridae as the major contributor to the observed spatiotemporal variations in the composition of coral reef fish assemblages in the study area. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Seasonal abundance and development of the Asian longhorned beetle and natural enemy prevalence in different forest types in China

    Science.gov (United States)

    Houping Liu; Leah S. Bauer; Tonghai Zhao; Ruitong Gao; Therese M. Poland

    2016-01-01

    Seasonal abundance and population development of the Asian longhorned beetle (ALB), Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae), and prevalence of its natural enemies were studied on Hankow willow (Salix matsudana Koidz.) at an urban forest site (Anci) and a rural forest site (Tangerli) in Hebei province...

  4. Abundance and stratification of soil macroarthropods in a Caatinga Forest in Northeast Brazil.

    Science.gov (United States)

    Araújo, V F P; Bandeira, A G; Vasconcellos, A

    2010-10-01

    In arid and semiarid environments, seasonality usually exerts a strong influence on the composition and dynamics of the soil community. The soil macroarthropods were studied in a Caatinga forest located in the Reserva Particular do Patrimônio Natural (RPPN) Fazenda Almas, São José dos Cordeiros, Paraíba, Brazil. Samples were collected during the dry and rainy seasons following the method proposed by the Tropical Soil Biology and Fertility Program (TSBF), with minor modifications. At each station, 15 soil blocks (20 × 20 × 30 cm: 12 L) were extracted and divided into three layers: A (0-10 cm), B (10-20 cm), and C (20-30 cm). In the rainy and dry seasons 1,306 ± 543(se) and 458 ± 212 ind.m-2 macroarthropods were found, respectively, with 35 and 18 respective taxa recorded. The abundance of individuals and taxa were significantly higher in the rainy season. Isoptera (57.8%) was the most abundant taxon, followed by Hymenoptera: Formicidae (17.2%), Coleoptera larvae (7.3%), and Araneae (3.5%). In the rainy season, abundance in layer A (576 ± 138 ind.m-2) was significantly higher than that of layer C (117 ± 64 ind.m-2), but was not different from layer B (613 ± 480 ind.m-2). There was also no difference between the layer B and C abundances. In the dry season, abundance in layer B (232 ± 120 ind.m-2) was not significantly different compared to layer A (182 ± 129 ind.m-2), but was significantly higher than abundance in layer C (44 ± 35 ind.m-2). During the rainy season, layer A (34 taxa) was significantly richer in taxa than layers B (19 taxa) and C (11 taxa). On the other hand, during the dry season the richness of layers A (12 taxa) and B (12 taxa) was equal, but significantly higher than that of layer C (6 taxa). Richness of taxa and abundance were positively correlated with soil organic matter and negatively correlated with soil temperature. The community of soil macroarthropods in the area of Caatinga studied has taxonomic and functional structures that

  5. Abundance and stratification of soil macroarthropods in a Caatinga Forest in Northeast Brazil

    Directory of Open Access Journals (Sweden)

    VFP Araújo

    Full Text Available In arid and semiarid environments, seasonality usually exerts a strong influence on the composition and dynamics of the soil community. The soil macroarthropods were studied in a Caatinga forest located in the Reserva Particular do Patrimônio Natural (RPPN Fazenda Almas, São José dos Cordeiros, Paraíba, Brazil. Samples were collected during the dry and rainy seasons following the method proposed by the Tropical Soil Biology and Fertility Program (TSBF, with minor modifications. At each station, 15 soil blocks (20 × 20 × 30 cm: 12 L were extracted and divided into three layers: A (0-10 cm, B (10-20 cm, and C (20-30 cm. In the rainy and dry seasons 1,306 ± 543(se and 458 ± 212 ind.m-2 macroarthropods were found, respectively, with 35 and 18 respective taxa recorded. The abundance of individuals and taxa were significantly higher in the rainy season. Isoptera (57.8% was the most abundant taxon, followed by Hymenoptera: Formicidae (17.2%, Coleoptera larvae (7.3%, and Araneae (3.5%. In the rainy season, abundance in layer A (576 ± 138 ind.m-2 was significantly higher than that of layer C (117 ± 64 ind.m-2, but was not different from layer B (613 ± 480 ind.m-2. There was also no difference between the layer B and C abundances. In the dry season, abundance in layer B (232 ± 120 ind.m-2 was not significantly different compared to layer A (182 ± 129 ind.m-2, but was significantly higher than abundance in layer C (44 ± 35 ind.m-2. During the rainy season, layer A (34 taxa was significantly richer in taxa than layers B (19 taxa and C (11 taxa. On the other hand, during the dry season the richness of layers A (12 taxa and B (12 taxa was equal, but significantly higher than that of layer C (6 taxa. Richness of taxa and abundance were positively correlated with soil organic matter and negatively correlated with soil temperature. The community of soil macroarthropods in the area of Caatinga studied has taxonomic and functional structures that are

  6. Seasonal dynamics of water use efficiency of typical forest and grassland ecosystems in China

    CERN Document Server

    Zhu, Xianjin; Wang, Qiufeng; Hu, Zhongmin; Han, Shijie; Yan, Junhua; Wang, Yanfen; Zhao, Liang

    2014-01-01

    We selected four sites of ChinaFLUX representing four major ecosystem types in China-Changbaishan temperate broad-leaved Korean pine mixed forest (CBS), Dinghushan subtropical evergreen broadleaved forest (DHS), Inner Mongolia temperate steppe (NM), and Haibei alpine shrub-meadow (HBGC)-to study the seasonal dynamics of ecosystem water use efficiency (WUE = GPP/ET, where GPP is gross primary productivity and ET is evapotranspiration) and factors affecting it. Our seasonal dynamics results indicated single-peak variation of WUE in CBS, NM, and HBGC, which were affected by air temperature (Ta) and leaf area index (LAI), through their effects on the partitioning of evapotranspiration (ET) into transpiration (T) (i.e., T/ET). In DHS, WUE was higher at the beginning and the end of the year, and minimum in summer. Ta and soil water content affected the seasonal dynamics of WUE through their effects on GPP/T. Our results indicate that seasonal dynamics of WUE were different because factors affecting the seasonal dyn...

  7. Seeding method influences warm-season grass abundance and distribution but not local diversity in grassland restoration

    Science.gov (United States)

    Yurkonis, Kathryn A.; Wilsey, Brian J.; Moloney, Kirk A.; Drobney, Pauline; Larson, Diane L.

    2010-01-01

    Ecological theory predicts that the arrangement of seedlings in newly restored communities may influence future species diversity and composition. We test the prediction that smaller distances between neighboring seeds in drill seeded grassland plantings would result in lower species diversity, greater weed abundance, and larger conspecific patch sizes than otherwise similar broadcast seeded plantings. A diverse grassland seed mix was either drill seeded, which places seeds in equally spaced rows, or broadcast seeded, which spreads seeds across the ground surface, into 24 plots in each of three sites in 2005. In summer 2007, we measured species abundance in a 1 m2 quadrat in each plot and mapped common species within the quadrat by recording the most abundant species in each of 64 cells. Quadrat-scale diversity and weed abundance were similar between drilled and broadcast plots, suggesting that processes that limited establishment and controlled invasion were not affected by such fine-scale seed distribution. However, native warm-season (C4) grasses were more abundant and occurred in less compact patches in drilled plots. This difference in C4 grass abundance and distribution may result from increased germination or vegetative propagation of C4 grasses in drilled plots. Our findings suggest that local plant density may control fine-scale heterogeneity and species composition in restored grasslands, processes that need to be further investigated to determine whether seed distributions can be manipulated to increase diversity in restored grasslands.

  8. Dynamic complexities in a seasonal prevention epidemic model with birth pulses

    International Nuclear Information System (INIS)

    Gao Shujing; Chen Lansun; Sun Lihua

    2005-01-01

    In most of population dynamics, increases in population due to birth are assumed to be time-dependent, but many species reproduce only during a single period of the year. In this paper, we propose an epidemic model with density-dependent birth pulses and seasonal prevention. Using the discrete dynamical system determined by stroboscopic map, we obtain the local or global stability, numerical simulation shows there is a characteristic sequence of bifurcations, leading to chaotic dynamics, which implies that the dynamical behaviors of the epidemic model with birth pulses and seasonal prevention are very complex, including small amplitude oscillations, large-amplitude multi-annual cycles and chaos. This suggests that birth pulse, in effect, provides a natural period or cyclicity that may lead a period-doubling route to chaos

  9. Seasonal dynamics of plankton communities coupled with ...

    African Journals Online (AJOL)

    In this study, we studied the influence of the physical-chemical and biological factors (bacterioplankton and phytoplankton abundances) for zooplankton dynamics in a Sidi Saâd reservoir in Centre of Tunisia. The samplings were carried out in spring, summer, autumn and winter (2005 to 2006) in the deepest station (surface ...

  10. The Effect of Seasonal Weather Variation on the Dynamics of the Plague Disease

    Directory of Open Access Journals (Sweden)

    Rigobert C. Ngeleja

    2017-01-01

    Full Text Available Plague is a historic disease which is also known to be the most devastating disease that ever occurred in human history, caused by gram-negative bacteria known as Yersinia pestis. The disease is mostly affected by variations of weather conditions as it disturbs the normal behavior of main plague disease transmission agents, namely, human beings, rodents, fleas, and pathogens, in the environment. This in turn changes the way they interact with each other and ultimately leads to a periodic transmission of plague disease. In this paper, we formulate a periodic epidemic model system by incorporating seasonal transmission rate in order to study the effect of seasonal weather variation on the dynamics of plague disease. We compute the basic reproduction number of a proposed model. We then use numerical simulation to illustrate the effect of different weather dependent parameters on the basic reproduction number. We are able to deduce that infection rate, progression rates from primary forms of plague disease to more severe forms of plague disease, and the infectious flea abundance affect, to a large extent, the number of bubonic, septicemic, and pneumonic plague infective agents. We recommend that it is more reasonable to consider these factors that have been shown to have a significant effect on RT for effective control strategies.

  11. Coral Bacterial-Core Abundance and Network Complexity as Proxies for Anthropogenic Pollution

    Directory of Open Access Journals (Sweden)

    Deborah C. A. Leite

    2018-04-01

    Full Text Available Acclimatization via changes in the stable (core or the variable microbial diversity and/or abundance is an important element in the adaptation of coral species to environmental changes. Here, we explored the spatial-temporal dynamics, diversity and interactions of variable and core bacterial populations associated with the coral Mussismilia hispida and the surrounding water. This survey was performed on five reefs along a transect from the coast (Reef 1 to offshore (Reef 5, representing a gradient of influence of the river mouth, for almost 12 months (4 sampling times, in the dry and rainy seasons. A clear increasing gradient of organic-pollution proxies (nitrogen content and fecal coliforms was observed from Reef 1 to Reef 5, during both seasons, and was highest at the Buranhém River mouth (Reef 1. Conversely, a clear inverse gradient of the network analysis of the whole bacterial communities also revealed more-complex network relationships at Reef 5. Our data also indicated a higher relative abundance of members of the bacterial core, dominated by Acinetobacter sp., at Reef 5, and higher diversity of site-stable bacterial populations, likely related to the higher abundance of total coliforms and N content (proxies of sewage or organic pollution at Reef 1, during the rainy season. Thus, the less “polluted” areas may show a more-complex network and a high relative abundance of members of the bacterial core (almost 97% in some cases, resulting in a more-homogeneous and well-established bacteriome among sites/samples, when the influence of the river is stronger (rainy seasons.

  12. Spatiotemporal heterogeneity in prey abundance and vulnerability shapes the foraging tactics of an omnivore

    Science.gov (United States)

    Rayl, Nathaniel; Bastille-Rousseau, Guillaume; Organ, John F.; Mumma, Matthew; Mahoney, Shane P.; Soulliere, Colleen; Lewis, Keith; Otto, Robert; Murray, Dennis; Waits, Lisette; Fuller, Todd

    2018-01-01

    Prey abundance and prey vulnerability vary across space and time, but we know little about how they mediate predator–prey interactions and predator foraging tactics. To evaluate the interplay between prey abundance, prey vulnerability and predator space use, we examined patterns of black bear (Ursus americanus) predation of caribou (Rangifer tarandus) neonates in Newfoundland, Canada using data from 317 collared individuals (9 bears, 34 adult female caribou, 274 caribou calves).During the caribou calving season, we predicted that landscape features would influence calf vulnerability to bear predation, and that bears would actively hunt calves by selecting areas associated with increased calf vulnerability. Further, we hypothesized that bears would dynamically adjust their foraging tactics in response to spatiotemporal changes in calf abundance and vulnerability (collectively, calf availability). Accordingly, we expected bears to actively hunt calves when they were most abundant and vulnerable, but switch to foraging on other resources as calf availability declined.As predicted, landscape heterogeneity influenced risk of mortality, and bears displayed the strongest selection for areas where they were most likely to kill calves, which suggested they were actively hunting caribou. Initially, the per‐capita rate at which bears killed calves followed a type‐I functional response, but as the calving season progressed and calf vulnerability declined, kill rates dissociated from calf abundance. In support of our hypothesis, bears adjusted their foraging tactics when they were less efficient at catching calves, highlighting the influence that predation phenology may have on predator space use. Contrary to our expectations, however, bears appeared to continue to hunt caribou as calf availability declined, but switched from a tactic of selecting areas of increased calf vulnerability to a tactic that maximized encounter rates with calves.Our results reveal that

  13. How Does Dung Beetle (Coleoptera: Scarabaeidae) Diversity Vary Along a Rainy Season in a Tropical Dry Forest?

    Science.gov (United States)

    Novais, Samuel M A; Evangelista, Lucas A; Reis-Júnior, Ronaldo; Neves, Frederico S

    2016-01-01

    Dung beetle community dynamics are determined by regional rainfall patterns. However, little is known about the temporal dynamics of these communities in tropical dry forests (TDFs). This study was designed to test the following predictions: 1) Peak diversity of dung beetle species occurs early in the wet season, with a decrease in diversity (α and β) and abundance throughout the season; 2) Nestedness is the primary process determining β-diversity, with species sampled in the middle and the end of the wet season representing subsets of the early wet season community. Dung beetles were collected in a TDF in the northern Minas Gerais state, Brazil over three sampling events (December 2009, February and April 2010). We sampled 2,018 dung beetles belonging to 39 species and distributed among 15 genera. Scarabaeinae α-diversity and abundance were highest in December and equivalent between February and April, while β-diversity among plots increased along the wet season. The importance of nestedness and species turnover varies between pairs of sample periods as the main process of temporal β-diversity. Most species collected in the middle and end of the wet season were found in greater abundance in early wet season. Thus, the dung beetle community becomes more homogeneous at the beginning of the wet season, and as the season advances, higher resource scarcity limits population size, which likely results in a smaller foraging range, increasing β-diversity. Our results demonstrate high synchronism between the dung beetle life cycle and seasonality of environmental conditions throughout the wet season in a TDF, where the onset of rains determines adult emergence for most species. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America.

  14. Seasonal dynamic thinning at Helheim Glacier

    DEFF Research Database (Denmark)

    Bevan, Suzanne L.; Luckman, Adrian; Khan, Shfaqat Abbas

    2015-01-01

    of 671±70kgm-3 and calculate that total water equivalent volume loss from the active part of the glacier (surface flow speeds >1 m day-1) ranges from 0.5 km3 in 2011 to 1.6 km3 in 2013. A rough ice-flux divergence analysis shows that at lower elevations (... the time series, that melt-induced acceleration is most likely the main driver of the seasonal dynamic thinning, as opposed to changes triggered by retreat....

  15. Spatio-temporal Variations of Abundance, Biomass, and ...

    African Journals Online (AJOL)

    The spatio-seasonal variations of Pseudodiaptomus hessei abundance, biomass and reproductive parameters were investigated in the Grand-Lahou lagoon at five stations during the dry and wet (or rainy) seasons from September 2005 to August 2006. In all sampling stations, abundance and biomass of P. hessei in the dry ...

  16. Measurements of Neuronal Soma Size and Estimated Peptide Concentrations in Addition to Cell Abundance Offer a Higher Resolution of Seasonal and Reproductive Influences of GnRH-I and GnIH in European Starlings.

    Science.gov (United States)

    Amorin, Nelson; Calisi, Rebecca M

    2015-08-01

    Hypothalamic neuropeptides involved in vertebrate reproduction, gonadotropin releasing hormone (GnRH-I) and gonadotropin-inhibitory hormone (GnIH), can vary in the abundance of immunoreactive cells as a function of the reproductive status and nest box occupation of European starlings (Sturnus vulgaris). While using the abundance of cells as an indicator of the activity of neurohormones is informative, incorporating information on cell size (readily observed using immunohistochemistry) can offer a more detailed understanding of environmentally-mediated changes in hormonal dynamics. In this study, we tested the hypothesis that the size of cells' somas and the estimated concentration of peptides in cells immunoreactive (ir) for GnRH-I and GnIH would vary throughout the breeding season and as a function of nest-box status (resident or not). In the absence of a direct assay of protein, we estimated an index of the concentration of hypothalamic peptides via the relative optical density (i.e., the difference between the mean optical density and the optical density of background staining). In support of our hypothesis, we found that GnRH-I- and GnIH-ir soma size and peptide concentration changed both in males and females throughout the breeding season. Somas were largest and estimated peptide concentration was highest mid-season when compared with earlier in the season or to the non-breeding period. For nest-box residents, GnIH-ir soma size and peptide concentration were higher during the middle of the breeding season than earlier in the breeding season, although residence in the nest box was not related to GnRH-I-ir variables. Our results confirm that previously reported changes in cell abundance mimic changes we see in GnRH-I and GnIH-ir soma size and our proxy for peptide concentration. However, investigating changes in the soma of GnRH-I-ir cells revealed a peak in size during the middle of the breeding season, a change not evident when solely examining data on the

  17. Successional dynamics in the seasonally forced diamond food web.

    Science.gov (United States)

    Klausmeier, Christopher A; Litchman, Elena

    2012-07-01

    Plankton seasonal succession is a classic example of nonequilibrium community dynamics. Despite the fact that it has been well studied empirically, it lacks a general quantitative theory. Here we investigate a food web model that includes a resource, two phytoplankton, and a shared grazer-the diamond food web-in a seasonal environment. The model produces a number of successional trajectories that have been widely discussed in the context of the verbal Plankton Ecology Group model of succession, such as a spring bloom of a good competitor followed by a grazer-induced clear-water phase, setting the stage for the late-season dominance of a grazer-resistant species. It also predicts a novel, counterintuitive trajectory where the grazer-resistant species has both early- and late-season blooms. The model often generates regular annual cycles but sometimes produces multiyear cycles or chaos, even with identical forcing each year. Parameterizing the model, we show how the successional trajectory depends on nutrient supply and the length of the growing season, two key parameters that vary among water bodies. This model extends nonequilibrium theory to food webs and is a first step toward a quantitative theory of plankton seasonal succession.

  18. Seasonal dynamics of the inorganic nutrients from auatic comple SomovaParche in 21

    Directory of Open Access Journals (Sweden)

    SECELEANUODOR Daniela

    2017-12-01

    Full Text Available The existence of nitrogen compounds influence variety, abundance and nutritional value of aquatic organisms. This study aimes to analyze the dynamic of nutrient inorganic forms in spring (March, summer (July and autumn (September seasons, in 2016. The selected sampling points were: SomovaParcheş complex inlet (S1, Somova-Parches complex outlet channel into the Danube River (S2, rainwater and cooling water discharge from the industrial zone of Tulcea (S3, Casla lake (S4, Somova lake (S5, Parches lake (S6, Rotundu lake (S6. Study results show that the physico-chemical characteristics and surface water quality from the aquatic complex Somova-Parches are determined by natural factors (climate, flowing regime and also by the effects of industrial activities of Tulcea town. Also, it were identified exceedings of maximum allowed concentrations for good ecological status, established by the Water Framework Directive transposed into Romanian legislation through MMGA Order 161/2006.

  19. Seasonal and habitat abundance and distribution of some forensically important blow flies (Diptera: Calliphoridae) in Central California.

    Science.gov (United States)

    Brundage, Adrienne; Bros, Shannon; Honda, Jeffrey Y

    2011-10-10

    Seasonal and habitat calliphorid abundance and distribution were examined weekly for two years (2001-2003) in Santa Clara County, California, using sentinel traps baited with bovine liver. Of the 34,389 flies examined in three defined habitats (rural, urban, and riparian), 38% of the total catch represented Compsomyiops callipes (Bigot) and 23% represented Phormia regina (Meigen). Other flies collected in this survey included Calliphora vomitoria (Linnaeus), Calliphora latifrons (Hough), Lucilia sericata (Meigen), Lucilia cuprina (Wiedemann), and Lucilia mexicana (Macquart), which is a new record for the area. Multivariate MANOVA and ANOVA (P ≤ 0.05) analysis indicate significant seasonal habitat preference for all fly species examined. This information may be used to identify potentially forensically impo rtant fly species within Santa Clara County, California. Published by Elsevier Ireland Ltd.

  20. Seasonal dynamics and diversity of bacteria in retail oyster tissues.

    Science.gov (United States)

    Wang, Dapeng; Zhang, Qian; Cui, Yan; Shi, Xianming

    2014-03-03

    Oysters are one of the important vehicles for the transfer of foodborne pathogens. It was reported that bacteria could be bio-accumulated mainly in the gills and digestive glands. In artificially treated oysters, bacterial communities have been investigated by culture-independent methods after harvest. However, little information is available on the seasonal dynamics of bacterial accumulation in retail oyster tissues. In this study, retail oysters were collected from local market in different seasons. The seasonal dynamics and diversity of bacteria in oyster tissues, including the gills, digestive glands and residual tissues, were analyzed by denaturing gradient gel electrophoresis (DGGE). It was interesting that the highest bacterial diversity appeared in the Fall season, not in summer. Our results indicated that Proteobacteria was the predominant member (23/46) in oyster tissues. Our results also suggested that bacterial diversity in gills was higher than that in digestive glands and other tissues. In addition, not all the bacteria collected from surrounding water by gills were transferred to digestive glands. On the other hand, few bacteria were found in oyster tissues except in the gills. Therefore, the gills could be the best candidate target tissue for monitoring of pathogenic bacteria either to human or to oyster. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Seasonal abundance of eggplant leafminer Liriomyza sativae (Blanchard, 1938) (Diptera, Agromyzidae) in plastic-house

    Science.gov (United States)

    Kathiar, S. A.; Flaih, S. K.; Al-Khazraji, H. I.; Ismael, S. K.

    2018-05-01

    The eggplant Solanum melongena L. crop is attacked by one of the most common pests which is the leafminer Liriomyza sativae (Blanchard, 1938); therefore, this investigation was conducted to study the seasonal abundance of the eggplant leafminer in eggplant Plastic-house. The results showed that the highest average of infested leaves was 6.67 leaf, the highest average of tunnels by leaf miner was 9.87 tunnels and the highest percent of infestation was recorded 30.5% in 23. April. 2017. This study showed the parasitoid Diglyphus isaea (Walker, 1838) (Hymenoptera, Eulophidae) was recorded as a natural enemy to control the pest and the highest incidence of parasitism was 32.2 parasites on average in 16. April. 2017.

  2. Seasonal abundance and blood feeding activity of Anopheles minimus Theobald (Diptera: Culicidae) in Thailand.

    Science.gov (United States)

    Chareonviriyaphap, Theeraphap; Prabaripai, Atchariya; Bangs, Michael J; Aum-Aung, Boonserm

    2003-11-01

    Anopheline mosquito larvae and adults were sampled at Ban Pu Teuy, Tri-Yok District, Kanchanaburi Province, western Thailand, from January 2000 to December 2001. Over the period of 2 yr, Anopheles minimus sensu lato was the most commonly collected species, followed by Anopheles swadiwongporni and Anopheles dirus sensu lato; all three species are important vectors of malaria in Thailand. Attempted blood feeding by An. minimus occurred throughout the night, with two distinct feeding peaks: strong activity immediately after sunset (1800-2100 hours), followed by a second, less pronounced, rise before sunrise (0300-0600 hours). Anopheles minimus were more abundant during the wet season compared with the dry and hot seasons, although nocturnal adult feeding patterns were similar. Anopheles minimus fed readily on humans inside and outside of houses, showing a slight preference for exophagy. The human-biting peak of An. minimus in our study area differed from other localities sampled in Thailand, indicating the possible existence of site-specific populations of An. minimus exhibiting different host-seeking behavior. These results underscore the importance of conducting site-specific studies to accurately determine vector larval habitats and adult activity patterns and linking their importance in malaria transmission in a given area.

  3. Characterization of free amino acids, bacteria and fungi in size-segregated atmospheric aerosols in boreal forest: seasonal patterns, abundances and size distributions

    Science.gov (United States)

    Helin, Aku; Sietiö, Outi-Maaria; Heinonsalo, Jussi; Bäck, Jaana; Riekkola, Marja-Liisa; Parshintsev, Jevgeni

    2017-11-01

    Primary biological aerosol particles (PBAPs) are ubiquitous in the atmosphere and constitute ˜ 30 % of atmospheric aerosol particle mass in sizes > 1 µm. PBAP components, such as bacteria, fungi and pollen, may affect the climate by acting as cloud-active particles, thus having an effect on cloud and precipitation formation processes. In this study, size-segregated aerosol samples ( 10 µm) were collected in boreal forest (Hyytiälä, Finland) during a 9-month period covering all seasons and analysed for free amino acids (FAAs), DNA concentration and microorganism (bacteria, Pseudomonas and fungi). Measurements were performed using tandem mass spectrometry, spectrophotometry and qPCR, respectively. Meteorological parameters and statistical analysis were used to study their atmospheric implication for results. Distinct annual patterns of PBAP components were observed, late spring and autumn being seasons of dominant occurrence. Elevated abundances of FAAs and bacteria were observed during the local pollen season, whereas fungi were observed at the highest level during autumn. Meteorological parameters such as air and soil temperature, radiation and rainfall were observed to possess a close relationship with PBAP abundances on an annual scale.

  4. Seasonal composition, abundance and biomass of the subestuarine fish assemblage in Solís Chico (Río de la Plata estuary, Uruguay).

    Science.gov (United States)

    Plavan, A Acuña; Gurdek, R; Muñoz, N; Gutierrez, J M; Spósito, M; Correa, P; Caride, A

    2017-01-01

    The large estuaries can present long narrow branches called subestuaries or tidal creeks. These types of subsystems are distributed along the Uruguayan coast of the Río de la Plata estuary and are very important as nursery and refuge areas for fish. For the first time, the seasonal composition and abundance of the fish community of the Solís Chico subestuary was studied by using beach and gill nets. Fourteen species, mainly euryhaline (86%) presented a significant representation of juvenile stages. The fish community was dominated by Odontesthes argentinensis, Platanichthys platana, Mugil liza, Brevoortia aurea, Micropogonias furnieri and Paralichthys orbignyanus, similar to adjacent subestuaries. While Micropogonias furnieri and B. aurea were the most abundant species, some other species were rarely caught. A seasonal variation of the fish assemblage abundance was detected, with higher values in autumn showing a positive correlation with temperature. Species that complete their life cycle in the Río de la Plata estuary, some of which are relevant to fisheries (64% of the analyzed species) were captured in the Solís Chico subestuary. The importance of this environment as a transitional system for some estuarine fish species is advised.

  5. Seasonal abundance of the navel orangeworm, Amyelois transitella, in figs and the effect of peripheral aerosol dispensers on sexual communication.

    Science.gov (United States)

    Burks, Charles S; Brandl, David G

    2004-01-01

    We used flight traps baited with unmated female navel orangeworm Amyelois transitella (Walker) (Lepidoptera: Pyralidae) to examine, over two growing seasons, seasonal changes in the abundance of males in fig orchards and the impact of release of 48 mg per ha per day of the pheromone component (Z,Z)-11,13-hexadecadienal from peripherally-located timed-release dispensers on the ability of males to find unmated females within 16-ha treatment plots. Material was placed out and mating disruption was commenced at the beginning of April in the first year, and at the beginning of July the second year. This technique effectively prevented males from finding females in female-baited traps placed throughout the plot. Navel orangeworm abundance was high in figs during the first and third flight, but lower in June and July during the second flight. Since Calimyrna figs are not susceptible to attack by navel orangeworm until mid-to-late July, these findings suggest that materials cost can be reduced by beginning treatment later. Implications for insect pest management in figs and other California crops are discussed.

  6. Density-driven water exchange controls seasonal declines in the abundance of jellyfish (Aurelia aurita) in a Danish fjord system

    DEFF Research Database (Denmark)

    Goldstein, Josephine; Jürgensen, Carsten; Steiner, Ulrich

    2018-01-01

    and disappears by winter. While food limitation has been suggested as possible driver of distinct seasonal declines in the local jellyfish abundance, the role of hydrodynamic forcing in the shallow, semi-enclosed system is still unclear. Based on regular measurements from a two-year field campaign, we provide...

  7. Spatiotemporal heterogeneity in prey abundance and vulnerability shapes the foraging tactics of an omnivore.

    Science.gov (United States)

    Rayl, Nathaniel D; Bastille-Rousseau, Guillaume; Organ, John F; Mumma, Matthew A; Mahoney, Shane P; Soulliere, Colleen E; Lewis, Keith P; Otto, Robert D; Murray, Dennis L; Waits, Lisette P; Fuller, Todd K

    2018-05-01

    Prey abundance and prey vulnerability vary across space and time, but we know little about how they mediate predator-prey interactions and predator foraging tactics. To evaluate the interplay between prey abundance, prey vulnerability and predator space use, we examined patterns of black bear (Ursus americanus) predation of caribou (Rangifer tarandus) neonates in Newfoundland, Canada using data from 317 collared individuals (9 bears, 34 adult female caribou, 274 caribou calves). During the caribou calving season, we predicted that landscape features would influence calf vulnerability to bear predation, and that bears would actively hunt calves by selecting areas associated with increased calf vulnerability. Further, we hypothesized that bears would dynamically adjust their foraging tactics in response to spatiotemporal changes in calf abundance and vulnerability (collectively, calf availability). Accordingly, we expected bears to actively hunt calves when they were most abundant and vulnerable, but switch to foraging on other resources as calf availability declined. As predicted, landscape heterogeneity influenced risk of mortality, and bears displayed the strongest selection for areas where they were most likely to kill calves, which suggested they were actively hunting caribou. Initially, the per-capita rate at which bears killed calves followed a type-I functional response, but as the calving season progressed and calf vulnerability declined, kill rates dissociated from calf abundance. In support of our hypothesis, bears adjusted their foraging tactics when they were less efficient at catching calves, highlighting the influence that predation phenology may have on predator space use. Contrary to our expectations, however, bears appeared to continue to hunt caribou as calf availability declined, but switched from a tactic of selecting areas of increased calf vulnerability to a tactic that maximized encounter rates with calves. Our results reveal that generalist

  8. External Morphology of Adult Citrus Butterfly, Papilio memnon (Linnaeus, 1758) and Seasonal Abundance of the Species

    International Nuclear Information System (INIS)

    Ni Ni Win

    2005-10-01

    Sexual dimorphism is obvious in Papilio memnon. The female adult resembles that of Papilio polytes another citrus butterfly species. However, marked difference is observed in the size and red spots on the base of the forewing. The adult male P. memnon is blue black in colour and red spots are present on the base of the underside of both for and hind wings. The win span of sexes ranges from 120mm to 150mm. The breeding season is from end of June to early part of January, the peak being in the month of November. The recorded diagnostic external features of this studied species are described supported by scaled photographs. Seasonal abundance of this species is also mentioned. It is learnt through the internet that a mounted specimen of this species fetched $2.95 in Malaysia. It is therefore concluded that successful rearing of this species in captivity could be of benefit to the country.

  9. Seasonal variations of species composition and abundance of zooplankton in Ehoma Lake, a floodplain lake in Nigeria

    Directory of Open Access Journals (Sweden)

    Okechukwu. I Okogwu

    2010-03-01

    Full Text Available Ehoma Lake is among the important breeding sites of the major fishes in the Mid-Cross River, Nigeria. The juveniles of these fishes are solely dependent on zooplankton, which has not been studied previously. I studied monthly the lake’s physico-chemical variables and zooplankton composition in three stations (littoral, sub-littoral and pelagic from March 2005 to August 2006. Sixty-seven zooplankton species (42 rotifers, 19 cladocerans and 6 copepods were identified. Daphnia obtusa Kurz, Keratella valga Ehrenberg, Keratella ticinensis Callerrio, Keratella hiemalis Carlin, Brachionus dimidiatus Bryce and Lecane candida Hauer and Murray are new records for Nigeria. The dominant zooplankters were Diaphanosoma excisum Kurz and Moina micrura Kurz. There was an inverse relationship between species richness and abundance. Richness was highest in the dry season while peak zooplankton abundance was recorded in the rainy season. Zooplankton abundance and species richness decreased progressively from the littoral to the pelagic station while the Shannon-Weaver diversity index varied from 0.68 to 1.28 without a clear seasonal trend. There is a succession pattern: rotifers that are dominant in the dry season are replaced by cladocerans in the rainy season. This succession was greatly influenced by seasonal flooding of the lake. As no previous information on the zooplankton of the lake is available, this study provides baseline data on the lake`s zooplankton. Rev. Biol. Trop. 58 (1: 171-182. Epub 2010 March 01.El lago Ehoma, situado en la mitad del río Cross, es uno de los lugares de reproducción de las principales especies de peces del río. Los juveniles de estos peces dependen exclusivamente del zooplancton, sin embargo poco se sabe sobre este recurso en el lago. En este estudio, las variables físico-químicas y del zooplancton del lago fueron estudiadas mensualmente en tres estaciones (litoral, sub-litoral y pelágica, de marzo de 2005 a agosto de

  10. Season-modulated responses of Neotropical bats to forest fragmentation.

    Science.gov (United States)

    Ferreira, Diogo F; Rocha, Ricardo; López-Baucells, Adrià; Farneda, Fábio Z; Carreiras, João M B; Palmeirim, Jorge M; Meyer, Christoph F J

    2017-06-01

    Seasonality causes fluctuations in resource availability, affecting the presence and abundance of animal species. The impacts of these oscillations on wildlife populations can be exacerbated by habitat fragmentation. We assessed differences in bat species abundance between the wet and dry season in a fragmented landscape in the Central Amazon characterized by primary forest fragments embedded in a secondary forest matrix. We also evaluated whether the relative importance of local vegetation structure versus landscape characteristics (composition and configuration) in shaping bat abundance patterns varied between seasons. Our working hypotheses were that abundance responses are species as well as season specific, and that in the wet season, local vegetation structure is a stronger determinant of bat abundance than landscape-scale attributes. Generalized linear mixed-effects models in combination with hierarchical partitioning revealed that relationships between species abundances and local vegetation structure and landscape characteristics were both season specific and scale dependent. Overall, landscape characteristics were more important than local vegetation characteristics, suggesting that landscape structure is likely to play an even more important role in landscapes with higher fragment-matrix contrast. Responses varied between frugivores and animalivores. In the dry season, frugivores responded more to compositional metrics, whereas during the wet season, local and configurational metrics were more important. Animalivores showed similar patterns in both seasons, responding to the same group of metrics in both seasons. Differences in responses likely reflect seasonal differences in the phenology of flowering and fruiting between primary and secondary forests, which affected the foraging behavior and habitat use of bats. Management actions should encompass multiscale approaches to account for the idiosyncratic responses of species to seasonal variation in

  11. Seasonal variation and impact of waste-water lagoons as larval habitat on the population dynamics of Culicoides sonorensis (Diptera:Ceratpogonidae at two dairy farms in northern California.

    Directory of Open Access Journals (Sweden)

    Christie E Mayo

    Full Text Available The Sacramento (northern Central Valley of California (CA has a hot Mediterranean climate and a diverse ecological landscape that is impacted extensively by human activities, which include the intensive farming of crops and livestock. Waste-water ponds, marshes, and irrigated fields associated with these agricultural activities provide abundant larval habitats for C. sonorensis midges, in addition to those sites that exist in the natural environment. Within this region, C. sonorensis is an important vector of bluetongue (BTV and related viruses that adversely affect the international trade and movement of livestock, the economics of livestock production, and animal welfare. To characterize the seasonal dynamics of immature and adult C. sonorensis populations, abundance was monitored intensively on two dairy farms in the Sacramento Valley from August 2012- to July 2013. Adults were sampled every two weeks for 52 weeks by trapping (CDC style traps without light and baited with dry-ice along N-S and E-W transects on each farm. One farm had large operational waste-water lagoons, whereas the lagoon on the other farm was drained and remained dry during the study. Spring emergence and seasonal abundance of adult C. sonorensis on both farms coincided with rising vernal temperature. Paradoxically, the abundance of midges on the farm without a functioning waste-water lagoon was increased as compared to abundance on the farm with a waste-water lagoon system, indicating that this infrastructure may not serve as the sole, or even the primary larval habitat. Adult midges disappeared from both farms from late November until May; however, low numbers of parous female midges were detected in traps set during daylight in the inter-seasonal winter period. This latter finding is especially critical as it provides a potential mechanism for the "overwintering" of BTV in temperate regions such as northern CA. Precise documentation of temporal changes in the annual

  12. Japanese Interest in “Hotaru” (Fireflies) and “Kabuto-Mushi” (Japanese Rhinoceros Beetles) Corresponds with Seasonality in Visible Abundance

    Science.gov (United States)

    Takada, Kenta

    2012-01-01

    Seasonal changes in the popularity of fireflies [usually Genji-fireflies (Luciola cruciata Motschulsky) in Japan] and Japanese rhinoceros beetles [Allomyrina dichotoma (Linne)] were investigated to examine whether contemporary Japanese are interested in visible emergence of these insects as seasonal events. The popularity of fireflies and Japanese rhinoceros beetles was assessed by the Google search volume of their Japanese names, “Hotaru” and “Kabuto-mushi” in Japanese Katakana script using Google Trends. The search volume index for fireflies and Japanese rhinoceros beetles was distributed across seasons with a clear peak in only particular times of each year from 2004 to 2011. In addition, the seasonal peak of popularity for fireflies occurred at the beginning of June, whereas that for Japanese rhinoceros beetles occurred from the middle of July to the beginning of August. Thus seasonal peak of each species coincided with the peak period of the emergence of each adult stage. These findings indicated that the Japanese are interested in these insects primarily during the time when the two species are most visibly abundant. Although untested, this could suggest that fireflies and Japanese rhinoceros beetles are perceived by the general public as indicators or symbols of summer in Japan. PMID:26466535

  13. The flavonoid pathway in tomato seedlings: transcript abundance and the modeling of metabolite dynamics.

    Directory of Open Access Journals (Sweden)

    Marian Groenenboom

    Full Text Available Flavonoids are secondary metabolites present in all terrestrial plants. The flavonoid pathway has been extensively studied, and many of the involved genes and metabolites have been described in the literature. Despite this extensive knowledge, the functioning of the pathway in vivo is still poorly understood. Here, we study the flavonoid pathway using both experiments and mathematical models. We measured flavonoid metabolite dynamics in two tissues, hypocotyls and cotyledons, during tomato seedling development. Interestingly, the same backbone of interactions leads to very different accumulation patterns in the different tissues. Initially, we developed a mathematical model with constant enzyme concentrations that described the metabolic networks separately in both tissues. This model was unable to fit the measured flavonoid dynamics in the hypocotyls, even if we allowed unrealistic parameter values. This suggested us to investigate the effect of transcript abundance on flavonoid accumulation. We found that the expression of candidate flavonoid genes varies considerably with time. Variation in transcript abundance results in enzymatic variation, which could have a large effect on metabolite accumulation. Candidate transcript abundance was included in the mathematical model as representative for enzyme concentration. We fitted the resulting model to the flavonoid dynamics in the cotyledons, and tested it by applying it to the data from hypocotyls. When transcript abundance is included, we are indeed able to explain flavonoid dynamics in both tissues. Importantly, this is possible under the biologically relevant restriction that the enzymatic properties estimated by the model are conserved between the tissues.

  14. Seasonal trends in abundance and composition of marine debris in selected public beaches in Peninsular Malaysia

    Science.gov (United States)

    Mobilik, Julyus-Melvin; Ling, Teck-Yee; Husain, Mohd-Lokman Bin; Hassan, Ruhana

    2015-09-01

    The abundance and composition of marine debris were investigated at Saujana (in the state of Negeri Sembilan) and Batu Rakit (in the state of Terengganu) beaches during surveys conducted in December 2012 (northeast monsoon), May 2013 (intermediate monsoon) and July 2013 (southwest monsoon). A total of 4,682 items of debris weighing 231.4 kg were collected and sorted. Batu Rakit received substantially greater quantities of debris (815±717 items/km or 40.4±13.0 kg/km) compared to Saujana (745±444 items/km or 36.7±18.0 kg/km). Total debris item was more abundant during the southwest monsoon (SWM) (1,122±737 items/km) compared to the northeast monsoon (NEM) (825±593 items/ km) and the intermediate monsoon (IM) (394±4 items/km) seasons. Plastic category (88%) was the most numerous items collected and object items contributed 44.18% includes packaging, plastic fragments, cups, plastic shopping bags, plastic food wrapper, clear plastic bottles from the total debris items collected. Object items associated with common source (47%) were the highest debris accumulated, followed by terrestrial (30%) and marine (23%) sources. The high percentage of common and terrestrial sources during SWM season requires immediate action by marine environment stakeholders to develop and introduce strategies to reduce if not totally eliminates the marine debris in the marine environment. Awareness should be continued and focused on beach users and vessels' crew to alert them on the alarming accumulation rate of marine debris and its pathways into the marine environment.

  15. Seasonal abundance of crustaceans associated with artisanal fishery of blue crab (Callinectes sapidus) in Sisal, Yucatan, Mexico

    OpenAIRE

    Celis-Sánchez, José Alfredo; Estrella-Canto, Arely de Jesús; Poot-López, Gaspar Román; González-Salas, Carlos; López-Rocha, Jorge Alberto

    2014-01-01

    Seasonal abundance and selectivity of the main crustacean species associated with blue crab fishing was studied at the port of Sisal, Yucatan, Mexico. For this purpose, 52 crab traps were used, which were divided into four parallel transects placed 100, 150, 200 and 250 m of the shoreline. Each transect consisted of 13 traps 20 m from each other. Traps were set at dusk and checked at dawn, standardizing the fishing effort to 17 hours/trap/day. A total of 832 organisms from eight species were ...

  16. seasonal population dynamics of rodents of mount chilalo, arsi ...

    African Journals Online (AJOL)

    Preferred Customer

    ABSTRACT: A study on seasonal population dynamics of rodents was carried out on Mount. Chilalo from .... vegetation growth, availability of food and water, and ... vegetation (3,300–4,200 masl) (Alemayehu. Mengistu, 1975; APEDO and ABRDP, 2004). The mountain is one of the Afrotropical biodiversity hotspots areas.

  17. Long-term and seasonal dynamics of dengue in Iquitos, Peru.

    Directory of Open Access Journals (Sweden)

    Steven T Stoddard

    2014-07-01

    Full Text Available Long-term disease surveillance data provide a basis for studying drivers of pathogen transmission dynamics. Dengue is a mosquito-borne disease caused by four distinct, but related, viruses (DENV-1-4 that potentially affect over half the world's population. Dengue incidence varies seasonally and on longer time scales, presumably driven by the interaction of climate and host susceptibility. Precise understanding of dengue dynamics is constrained, however, by the relative paucity of laboratory-confirmed longitudinal data.We studied 10 years (2000-2010 of laboratory-confirmed, clinic-based surveillance data collected in Iquitos, Peru. We characterized inter and intra-annual patterns of dengue dynamics on a weekly time scale using wavelet analysis. We explored the relationships of case counts to climatic variables with cross-correlation maps on annual and trimester bases.Transmission was dominated by single serotypes, first DENV-3 (2001-2007 then DENV-4 (2008-2010. After 2003, incidence fluctuated inter-annually with outbreaks usually occurring between October and April. We detected a strong positive autocorrelation in case counts at a lag of ∼ 70 weeks, indicating a shift in the timing of peak incidence year-to-year. All climatic variables showed modest seasonality and correlated weakly with the number of reported dengue cases across a range of time lags. Cases were reduced after citywide insecticide fumigation if conducted early in the transmission season.Dengue case counts peaked seasonally despite limited intra-annual variation in climate conditions. Contrary to expectations for this mosquito-borne disease, no climatic variable considered exhibited a strong relationship with transmission. Vector control operations did, however, appear to have a significant impact on transmission some years. Our results indicate that a complicated interplay of factors underlie DENV transmission in contexts such as Iquitos.

  18. Abundance and Diversity of Denitrifying and Anammox Bacteria in Seasonally Hypoxic and Sulfidic Sediments of the Saline Lake Grevelingen

    Science.gov (United States)

    Lipsewers, Yvonne A.; Hopmans, Ellen C.; Meysman, Filip J. R.; Sinninghe Damsté, Jaap S.; Villanueva, Laura

    2016-01-01

    Denitrifying and anammox bacteria are involved in the nitrogen cycling in marine sediments but the environmental factors that regulate the relative importance of these processes are not well constrained. Here, we evaluated the abundance, diversity, and potential activity of denitrifying, anammox, and sulfide-dependent denitrifying bacteria in the sediments of the seasonally hypoxic saline Lake Grevelingen, known to harbor an active microbial community involved in sulfur oxidation pathways. Depth distributions of 16S rRNA gene, nirS gene of denitrifying and anammox bacteria, aprA gene of sulfur-oxidizing and sulfate-reducing bacteria, and ladderane lipids of anammox bacteria were studied in sediments impacted by seasonally hypoxic bottom waters. Samples were collected down to 5 cm depth (1 cm resolution) at three different locations before (March) and during summer hypoxia (August). The abundance of denitrifying bacteria did not vary despite of differences in oxygen and sulfide availability in the sediments, whereas anammox bacteria were more abundant in the summer hypoxia but in those sediments with lower sulfide concentrations. The potential activity of denitrifying and anammox bacteria as well as of sulfur-oxidizing, including sulfide-dependent denitrifiers and sulfate-reducing bacteria, was potentially inhibited by the competition for nitrate and nitrite with cable and/or Beggiatoa-like bacteria in March and by the accumulation of sulfide in the summer hypoxia. The simultaneous presence and activity of organoheterotrophic denitrifying bacteria, sulfide-dependent denitrifiers, and anammox bacteria suggests a tight network of bacteria coupling carbon-, nitrogen-, and sulfur cycling in Lake Grevelingen sediments. PMID:27812355

  19. Abundance and diversity of denitrifying and anammox bacteria in seasonally hypoxic and sulfidic sediments of the saline Lake Grevelingen

    Directory of Open Access Journals (Sweden)

    Yvonne A. Lipsewers

    2016-10-01

    Full Text Available Denitrifying and anammox bacteria are involved in the nitrogen cycling in marine sediments but the environmental factors that regulate the relative importance of these processes are not well constrained. Here, we evaluated the abundance, diversity and potential activity of denitrifying, anammox, and sulfide-dependent denitrifying bacteria in the sediments of the seasonally hypoxic saline Lake Grevelingen, known to harbor an active microbial community involved in sulfur oxidation pathways. Depth distributions of 16S rRNA gene, nirS gene of denitrifying and anammox bacteria, aprA gene of sulfur-oxidizing and sulfate-reducing bacteria, and ladderane lipids of anammox bacteria were studied in sediments impacted by seasonally hypoxic bottom waters. Samples were collected down to 5 cm depth (1 cm resolution at three different locations before (March and during summer hypoxia (August. The abundance of denitrifying bacteria did not vary despite of differences in oxygen and sulfide availability in the sediments, whereas anammox bacteria were more abundant in the summer hypoxia but in those sediments with lower sulfide concentrations. The potential activity of denitrifying and anammox bacteria as well as of sulfur-oxidizing, including sulfide-dependent denitrifiers and sulfate-reducing bacteria, was potentially inhibited by the competition for nitrate and nitrite with cable and/or Beggiatoa-like bacteria in March and by the accumulation of sulfide in the summer hypoxia. The simultaneous presence and activity of organoheterotrophic denitrifying bacteria, sulfide-dependent denitrifiers and anammox bacteria suggests a tight network of bacteria coupling carbon-, nitrogen- and sulfur cycling in Lake Grevelingen sediments.

  20. Spatial and temporal dynamics of drosophilid larval assemblages associated to fruits

    Directory of Open Access Journals (Sweden)

    Renata Alves da Mata

    2015-03-01

    Full Text Available The study of organisms and their resources is critical to further understanding population dynamics in space and time. Although drosophilids have been widely used as biological models, their relationship with breeding and feeding sites has received little attention. Here, we investigate drosophilids breeding in fruits in the Brazilian Savanna, in two contrasting vegetation types, throughout 16 months. Specifically, larval assemblages were compared between savannas and forests, as well as between rainy and dry seasons. The relationships between resource availability and drosophilid abundance and richness were also tested. The community (4,022 drosophilids of 23 species and 2,496 fruits of 57 plant taxa varied widely in space and time. Drosophilid assemblages experienced a strong bottleneck during the dry season, decreasing to only 0.5% of the abundance of the rainy season. Additionally, savannas displayed lower richness and higher abundance than the forests, and were dominated by exotic species. Both differences in larval assemblages throughout the year and between savannas and gallery forests are consistent with those previously seen in adults. Although the causes of this dynamic are clearly multifactorial, resource availability (richness and abundance of rotten fruits was a good predictor of the fly assemblage structure.

  1. Impact of Seasonal Variability in Water, Plant and Soil Nutrient Dynamics in Agroecosystems

    Science.gov (United States)

    Pelak, N. F., III; Revelli, R.; Porporato, A. M.

    2017-12-01

    Agroecosystems cover a significant fraction of the Earth's surface, making their water and nutrient cycles a major component of global cycles across spatial and temporal scales. Most agroecosystems experience seasonality via variations in precipitation, temperature, and radiation, in addition to human activities which also occur seasonally, such as fertilization, irrigation, and harvesting. These seasonal drivers interact with the system in complex ways which are often poorly characterized. Crop models, which are widely used for research, decision support, and prediction of crop yields, are among the best tools available to analyze these systems. Though normally constructed as a set of dynamical equations forced by hydroclimatic variability, they are not often analyzed using dynamical systems theory and methods from stochastic ecohydrology. With the goal of developing this viewpoint and thus elucidating the roles of key feedbacks and forcings on system stability and on optimal fertilization and irrigation strategies, we develop a minimal dynamical system which contains the key components of a crop model, coupled to a carbon and nitrogen cycling model, driven by seasonal fluctuations in water and nutrient availability, temperature, and radiation. External drivers include seasonally varying climatic conditions and random rainfall forcing, irrigation and fertilization as well as harvesting. The model is used to analyze the magnitudes and interactions of the effects of seasonality on carbon and nutrient cycles, crop productivity, nutrient export of agroecosystems, and optimal management strategies with reference to productivity, sustainability and profitability. The impact of likely future climate scenarios on these systems is also discussed.

  2. Seasonal dynamics of zooplankton in Columbia–Snake River reservoirs,with special emphasis on the invasive copepod Pseudodiaptomus forbesi

    Science.gov (United States)

    Emerson, Joshua E.; Bollens, Stephen M.; Counihan, Timothy D.

    2015-01-01

    The Asian copepod Pseudodiaptomus forbesi has recently become established in the Columbia River. However, little is known about its ecology and effects on invaded ecosystems. We undertook a 2-year (July 2009 to June 2011) field study of the mesozooplankton in four reservoirs in the Columbia and Snake Rivers, with emphasis on the relation of the seasonal variation in distribution and abundance of P. forbesi to environmental variables. Pseudodiaptomus forbesi was abundant in three reservoirs; the zooplankton community of the fourth reservoir contained no known non-indigenous taxa. The composition and seasonal succession of zooplankton were similar in the three invaded reservoirs: a bloom of rotifers occurred in spring, native cyclopoid and cladoceran species peaked in abundance in summer, and P. forbesi was most abundant in late summer and autumn. In the uninvaded reservoir, total zooplankton abundance was very low year-round. Multivariate ordination indicated that temperature and dissolved oxygen were strongly associated with zooplankton community structure, with P. forbesi appearing to exhibit a single generation per year . The broad distribution and high abundance of P. forbesi in the Columbia–Snake River System could result in ecosystem level effects in areas intensively managed to improve conditions for salmon and other commercially and culturally important fish species. 

  3. Seasonal quantitative dynamics and ecology of pelagic rotifers in an acidified boreal lake

    Directory of Open Access Journals (Sweden)

    Svein Birger Wærvågen

    2017-12-01

    Full Text Available Lake Gjerstadvann is a dimictic, oligotrophic, slightly acidified boreal lake in southern Norway (northwest Europe. The planktonic rotifer community of this lake was studied quantitatively during one year in order to investigate the impacts of the local environment and biotic interactions on seasonal succession and habitat selection. Pure suspension feeders (mainly Keratella spp., Conochilus spp., and Kellicottia longispina together with raptorial graspers or specialised feeders (mainly Polyarthra spp. and Collotheca spp. dominated the rotifer community over prolonged periods, whereas carnivorous/omnivorous species (mainly Asplanchna priodonta were extremely uncommon. Low bicarbonate buffering capacity resulted in a distinctive seasonal oscillating pH between 5.0 and 5.6, defining a special acid-transition lake category. The pH values were highest in the productive period during summer, and lowest during ice break-up coinciding with the peak reactive aluminium concentrations of 250-300 mg L-1. As in typical Norwegian boreal perch lakes, the most abundant cladoceran was Bosmina longispina due to perch predation on the genus Daphnia. Rotifer community structure was significantly related to temperature and oxygen (P=0.001 and P=0.022, illustrating the important effects of the seasonal cycle and vertical density stratification. The most significant competition indicator species were B. longispina and Eudiaptomus gracilis (both with P=0.001. A variance partitioning indicated that 14% of the total community composition variance could only be explained by biotic interactions, while 19% of the variance could be attributed to environmental gradients. Of the variance, 23% could not be resolved between biotic interactions and environmental gradients, while a residual of 44% was not explainable by any of the variables. Acid conditions alone cannot account for all the observed changes in the rotifer community of this lake with low humic content, since

  4. Use of the robust design to estimate seasonal abundance and demographic parameters of a coastal bottlenose dolphin (Tursiops aduncus population.

    Directory of Open Access Journals (Sweden)

    Holly C Smith

    Full Text Available As delphinid populations become increasingly exposed to human activities we rely on our capacity to produce accurate abundance estimates upon which to base management decisions. This study applied mark-recapture methods following the Robust Design to estimate abundance, demographic parameters, and temporary emigration rates of an Indo-Pacific bottlenose dolphin (Tursiops aduncus population off Bunbury, Western Australia. Boat-based photo-identification surveys were conducted year-round over three consecutive years along pre-determined transect lines to create a consistent sampling effort throughout the study period and area. The best fitting capture-recapture model showed a population with a seasonal Markovian temporary emigration with time varying survival and capture probabilities. Abundance estimates were seasonally dependent with consistently lower numbers obtained during winter and higher during summer and autumn across the three-year study period. Specifically, abundance estimates for all adults and juveniles (combined varied from a low of 63 (95% CI 59 to 73 in winter of 2007 to a high of 139 (95% CI 134 to148 in autumn of 2009. Temporary emigration rates (γ' for animals absent in the previous period ranged from 0.34 to 0.97 (mean  =  0.54; ±SE 0.11 with a peak during spring. Temporary emigration rates for animals present during the previous period (γ'' were lower, ranging from 0.00 to 0.29, with a mean of 0.16 (± SE 0.04. This model yielded a mean apparent survival estimate for juveniles and adults (combined of 0.95 (± SE 0.02 and a capture probability from 0.07 to 0.51 with a mean of 0.30 (± SE 0.04. This study demonstrates the importance of incorporating temporary emigration to accurately estimate abundance of coastal delphinids. Temporary emigration rates were high in this study, despite the large area surveyed, indicating the challenges of sampling highly mobile animals which range over large spatial areas.

  5. Seasonal variation in diversity and abundance of understorey birds ...

    African Journals Online (AJOL)

    Our findings suggest that in a situation where there is no natural forest, an exotic plantation with suitable indigenous understorey cover can help in protection of birds, including endemic and near-endemic species. Keywords: birds, conservation, Eastern Arc Mountains, plantation, seasonal altitudinal migration, seasons, ...

  6. Seasonal dynamics of Co60 accumulation by Elodea canadensis Rich

    International Nuclear Information System (INIS)

    Bochenin, V.F.; Chebotina, M.Ya.

    1975-01-01

    The seasonal dynamics of Co 60 accumulation by one of the most widely distributed fresh-water plants, elodea (Elodea canadensis Rich), were studied. Accumulation was shown to vary with the season. A very low coefficient of accumulation (500-700 units) was typical for the summer period (June to August). It increased in the fall, reached its highest values (3500-4000) in mid-winter (January), and dropped sharply in the spring. Radioisotope concentrations in the plant varied similarly. The cumulative capacity of plants for Co 60 may vary by a factor of 6 to 7 during the year. It is suggested that the seasonal changes in Co 60 accumulation may be caused by both differences in the physiological state of the plants at different times of the year, and by seasonal variations in the hydrochemical regime of the water reservoir. Experiments were done to clarify which of these mechanisms is the determining factor. (V.A.P.)

  7. The role of carrion supply in the abundance of deep-water fish off California.

    Science.gov (United States)

    Drazen, Jeffrey C; Bailey, David M; Ruhl, Henry A; Smith, Kenneth L

    2012-01-01

    Few time series of deep-sea systems exist from which the factors affecting abyssal fish populations can be evaluated. Previous analysis showed an increase in grenadier abundance, in the eastern North Pacific, which lagged epibenthic megafaunal abundance, mostly echinoderms, by 9-20 months. Subsequent diet studies suggested that carrion is the grenadier's most important food. Our goal was to evaluate if changes in carrion supply might drive the temporal changes in grenadier abundance. We analyzed a unique 17 year time series of abyssal grenadier abundance and size, collected at Station M (4100 m, 220 km offshore of Pt. Conception, California), and reaffirmed the increase in abundance and also showed an increase in mean size resulting in a ∼6 fold change in grenadier biomass. We compared this data with abundance estimates for surface living nekton (pacific hake and jack mackerel) eaten by the grenadiers as carrion. A significant positive correlation between Pacific hake (but not jack mackerel) and grenadiers was found. Hake seasonally migrate to the waters offshore of California to spawn. They are the most abundant nekton species in the region and the target of the largest commercial fishery off the west coast. The correlation to grenadier abundance was strongest when using hake abundance metrics from the area within 100 nmi of Station M. No significant correlation between grenadier abundance and hake biomass for the entire California current region was found. Given the results and grenadier longevity, migration is likely responsible for the results and the location of hake spawning probably is more important than the size of the spawning stock in understanding the dynamics of abyssal grenadier populations. Our results suggest that some abyssal fishes' population dynamics are controlled by the flux of large particles of carrion. Climate and fishing pressures affecting epipelagic fish stocks could readily modulate deep-sea fish dynamics.

  8. Efeitos da sazonalidade e do tamanho da planta hospedeira na abundância de galhas de Cecidomyiidae (Diptera em Piper arboreum (Piperaceae Effects of seasonality and the size of host plants on abundance of Cecidomyiidae (Diptera galls on Piper arboreum (Piperaceae

    Directory of Open Access Journals (Sweden)

    Walter Santos de Araújo

    2009-06-01

    Full Text Available Este trabalho teve por objetivo verificar se existem efeitos da sazonalidade e do tamanho da planta hospedeira na ocorrência de galhas de Cecidomyiidae (Diptera em Piper arboreum (Piperaceae. O estudo foi conduzido mensalmente de setembro/2006 a agosto/2007, em uma área remanescente de Mata Mesófila Semidecídua em Goiânia, Goiás, Brasil. Em cada coleta, 10 indivíduos da planta hospedeira foram escolhidos aleatoriamente, e a altura, o número total de folhas, o número de folhas com galhas e o número de galhas por folhas foram estimados. A abundância de galhas variou significativamente durante o período de estudo, sendo que a maior abundância foi encontrada no início da estação chuvosa. A altura da planta hospedeira e o número de folhas por indivíduo também estiveram positivamente e significativamente relacionados com a abundância de galhas, uma vez que, plantas maiores oferecem maior disponibilidade de recursos e sítios de oviposição. Os resultados do presente estudo apontam que a sazonalidade pode ser tão determinante na abundância de galhas quanto os padrões arquitetônicos da planta hospedeira. As mudanças sazonais podem influenciar diretamente o desenvolvimento da planta hospedeira e assim, alterar a quantidade e a qualidade dos nutrientes oferecidos aos insetos galhadores.The objective of this work was to verify the effects of seasonality and the size of host plants on occurrence of Cecidomyiidae (Diptera galls on Piper arboreum (Piperaceae. This study was carried out monthly, from September, 2006 to August, 2007, in a remnant area of Semidecidual Forest in Goiânia, Goiás, Brazil. In each survey, 10 individuals of the host plant were chosen randomly, and the height, the total number of leaves, the number of leaves with galls and the number of galls per leaves were estimated. The abundance of galls varied significantly during the study period, being the greatest abundance found at the beginning of the rainy season

  9. Food abundance explains the breeding season of a tropical ...

    African Journals Online (AJOL)

    The timing of breeding in birds is a life-history trait that generally depends on food availability, but other factors may play a role, particularly in tropical areas where food availability is less seasonal than in temperate or polar areas. We studied the factors affecting the breeding season of the Crab Plover Dromas ardeola, ...

  10. Seasonality and comparative dynamics of six childhood infections in pre-vaccination Copenhagen

    DEFF Research Database (Denmark)

    Metcalf, C. Jessica E.; Bjørnstad, Ottar N.; Grenfell, Bryan T.

    2009-01-01

    Seasonal variation in infection transmission is a key determinant of epidemic dynamics of acute infections. For measles, the best-understood strongly immunizing directly transmitted childhood infection, the perception is that term-time forcing is the main driver of seasonality in developed...... of seasonality and basic reproductive rate of infections that should result from term-time forcing are also not upheld. We conclude that where yearly trajectories of susceptible numbers are perturbed, e.g. via waning of immunity, seasonality is unlikely to be entirely driven by term-time forcing. For the three...... bacterial infections, pertussis, scarlet fever and diphtheria, there is additionally a strong increase in transmission during the late summer before the end of school vacations....

  11. Seasonal dynamics of fish assemblage in a pond canal

    Czech Academy of Sciences Publication Activity Database

    Musil, J.; Adámek, Zdeněk; Baranyi, Ch.

    2007-01-01

    Roč. 15, č. 3-4 (2007), s. 217-226 ISSN 0967-6120. [New Challenges in Pond Aquaculture. České Budějovice, 26.04.2005-28.04.2005] Institutional research plan: CEZ:AV0Z60930519 Keywords : fish assemblage * pond canal * species richness * seasonal dynamics * alien species Subject RIV: GL - Fishing Impact factor: 0.828, year: 2007

  12. Meteorological factors and pollen season dynamics of selected herbaceous plants in Szczecin, 2004-2008

    Directory of Open Access Journals (Sweden)

    Małgorzata Puc

    2012-12-01

    Full Text Available The pollen of mugwort, plantain, sorrel, nettle and pigweed is an important airborne allergen source worldwide. The occurrence of pollen grains in the air is a seasonal phenomenon and estimation of seasonal variability in the pollen count permits evaluation of the threat posed by allergens over a given area. The aim of the study was to analyse the dynamics of Artemisia, Plantago, Rumex, Urticaceae and Chenopodiaceae pollen season in Szczecin (western Poland in 2004-2008 and to establish a relationship between the meteorological parameters versus the pollen count of the taxa studied. Measurements were performed by the Hirst volumetric trap (model Lanzoni VPPS 2000. Consecutive phases during the pollen season were defined for each taxon (1, 5, 25, 50, 75, 95, 99% of annual total and duration of the season was determined using the 98% method. On the basis of this analysis, temporary differences in the dynamics of the seasons were most evident for Artemisia. Correlation analysis with weather parameters demonstrated that the maximum wind speed, mean and maximum air temperature, relative humidity and dew point are the main factors influencing the average daily pollen concentrations in the atmosphere.

  13. Gear and seasonal bias associated with abundance and size structure estimates for lentic freshwater fishes

    Science.gov (United States)

    Fischer, Jesse R.; Quist, Michael C.

    2014-01-01

    All freshwater fish sampling methods are biased toward particular species, sizes, and sexes and are further influenced by season, habitat, and fish behavior changes over time. However, little is known about gear-specific biases for many common fish species because few multiple-gear comparison studies exist that have incorporated seasonal dynamics. We sampled six lakes and impoundments representing a diversity of trophic and physical conditions in Iowa, USA, using multiple gear types (i.e., standard modified fyke net, mini-modified fyke net, sinking experimental gill net, bag seine, benthic trawl, boat-mounted electrofisher used diurnally and nocturnally) to determine the influence of sampling methodology and season on fisheries assessments. Specifically, we describe the influence of season on catch per unit effort, proportional size distribution, and the number of samples required to obtain 125 stock-length individuals for 12 species of recreational and ecological importance. Mean catch per unit effort generally peaked in the spring and fall as a result of increased sampling effectiveness in shallow areas and seasonal changes in habitat use (e.g., movement offshore during summer). Mean proportional size distribution decreased from spring to fall for white bass Morone chrysops, largemouth bass Micropterus salmoides, bluegill Lepomis macrochirus, and black crappie Pomoxis nigromaculatus, suggesting selectivity for large and presumably sexually mature individuals in the spring and summer. Overall, the mean number of samples required to sample 125 stock-length individuals was minimized in the fall with sinking experimental gill nets, a boat-mounted electrofisher used at night, and standard modified nets for 11 of the 12 species evaluated. Our results provide fisheries scientists with relative comparisons between several recommended standard sampling methods and illustrate the effects of seasonal variation on estimates of population indices that will be critical to

  14. Seasonal forcing in a host-macroparasite system.

    Science.gov (United States)

    Taylor, Rachel A; White, Andrew; Sherratt, Jonathan A

    2015-01-21

    Seasonal forcing represents a pervasive source of environmental variability in natural systems. Whilst it is reasonably well understood in interacting populations and host-microparasite systems, it has not been studied in detail for host-macroparasite systems. In this paper we analyse the effect of seasonal forcing in a general host-macroparasite system with explicit inclusion of the parasite larval stage and seasonal forcing applied to the birth rate of the host. We emphasise the importance of the period of the limit cycles in the unforced system on the resulting dynamics in the forced system. In particular, when subject to seasonal forcing host-macroparasite systems are capable of multi-year cycles, multiple solution behaviour, quasi-periodicity and chaos. The host-macroparasite systems show a larger potential for multiple solution behaviour and a wider range of periodic solutions compared to similar interacting population and microparasite systems. By examining the system for parameters that represent red grouse and the macroparasite nematode Trichostrongylus tenuis we highlight how seasonality could be an important factor in explaining the wide range of seemingly uncorrelated cycle periods observed in grouse abundance in England and Scotland. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Temporal Dynamics of Arthropods on Six Tree Species in Dry Woodlands on the Caribbean Island of Puerto Rico

    Science.gov (United States)

    Beltrán, William; Wunderle, Joseph M.

    2014-01-01

    Abstract The seasonal dynamics of foliage arthropod populations are poorly studied in tropical dry forests despite the importance of these studies for understanding arthropod population responses to environmental change. We monitored the abundance, temporal distributions, and body size of arthropods in five naturalized alien and one native tree species to characterize arthropod seasonality in dry novel Prosopis–Leucaena woodlands in Puerto Rico. A branch clipping method was used monthly to sample foliage arthropod abundance over 39 mo. Seasonal patterns of rainfall and abundance within various arthropod taxa were highly variable from year to year. Abundance for most taxa did not show significant seasonality over the 3 yr, although most taxa had abundance peaks each year. However, Homoptera displayed high seasonality with significant temporal aggregations in each year. Formicidae, Orthoptera, and Coleoptera showed high variation in abundance between wet and dry periods, whereas Hemiptera were consistently more abundant in the wet period. Seasonal differences in mean abundance were found only in a few taxa on Tamarindus indica L. , Bucida buceras L. , Pithecellobium dulce , and (Roxburgh) Benth. Mean arthropod abundance varied among tree species, with highest numbers on Prosopis juliflora , (Swartz) De Candolle, Pi. dulce , Leucaena leucocephala , and (Lamarck) de Wit. Abundance of Araneae, Orthoptera, Coleoptera, Lepidoptera larvae, and all arthropods showed weak relationships with one or more climatic variables (rainfall, maximum temperature, or relative humidity). Body size of arthropods was usually largest during the dry periods. Overall, total foliage arthropod abundance showed no consistent seasonality among years, which may become a more common trend in dry forests and woodlands in the Caribbean if seasonality of rainfall becomes less predictable. PMID:25502036

  16. Seasonal changes in the abundance of bacterial genes related to dimethylsulfoniopropionate catabolism in seawater from Ofunato Bay revealed by metagenomic analysis

    KAUST Repository

    Kudo, Toshiaki; Kobiyama, Atsushi; Rashid, Jonaira; Reza, Shaheed; Yamada, Yuichiro; Ikeda, Yuri; Ikeda, Daisuke; Mizusawa, Nanami; Ikeo, Kazuho; Sato, Shigeru; Ogata, Takehiko; Jimbo, Mitsuru; Kaga, Shinnosuke; Watanabe, Shiho; Naiki, Kimiaki; Kaga, Yoshimasa; Segawa, Satoshi; Mineta, Katsuhiko; Bajic, Vladimir B.; Gojobori, Takashi; Watabe, Shugo

    2018-01-01

    Ofunato Bay is located in the northeastern Pacific Ocean area of Japan, and it has the highest biodiversity of marine organisms in the world, primarily due to tidal influences from the cold Oyashio and warm Kuroshio currents. Our previous results from performing shotgun metagenomics indicated that Candidatus Pelagibacter ubique and Planktomarina temperata were the dominant bacteria (Reza et al., 2018a, 2018b). These bacteria are reportedly able to catabolize dimethylsulfoniopropionate (DMSP) produced from phytoplankton into dimethyl sulfide (DMS) or methanethiol (MeSH). This study was focused on seasonal changes in the abundances of bacterial genes (dddP, dmdA) related to DMSP catabolism in the seawater of Ofunato Bay by BLAST+ analysis using shotgun metagenomic datasets. We found seasonal changes among the Candidatus Pelagibacter ubique strains, including those of the HTCC1062 type and the Red Sea type. A good correlation was observed between the chlorophyll a concentrations and the abundances of the catabolic genes, suggesting that the bacteria directly interact with phytoplankton in the marine material cycle system and play important roles in producing DMS and MeSH from DMSP as signaling molecules for the possible formation of the scent of the tidewater or as fish attractants.

  17. Seasonal changes in the abundance of bacterial genes related to dimethylsulfoniopropionate catabolism in seawater from Ofunato Bay revealed by metagenomic analysis

    KAUST Repository

    Kudo, Toshiaki

    2018-04-26

    Ofunato Bay is located in the northeastern Pacific Ocean area of Japan, and it has the highest biodiversity of marine organisms in the world, primarily due to tidal influences from the cold Oyashio and warm Kuroshio currents. Our previous results from performing shotgun metagenomics indicated that Candidatus Pelagibacter ubique and Planktomarina temperata were the dominant bacteria (Reza et al., 2018a, 2018b). These bacteria are reportedly able to catabolize dimethylsulfoniopropionate (DMSP) produced from phytoplankton into dimethyl sulfide (DMS) or methanethiol (MeSH). This study was focused on seasonal changes in the abundances of bacterial genes (dddP, dmdA) related to DMSP catabolism in the seawater of Ofunato Bay by BLAST+ analysis using shotgun metagenomic datasets. We found seasonal changes among the Candidatus Pelagibacter ubique strains, including those of the HTCC1062 type and the Red Sea type. A good correlation was observed between the chlorophyll a concentrations and the abundances of the catabolic genes, suggesting that the bacteria directly interact with phytoplankton in the marine material cycle system and play important roles in producing DMS and MeSH from DMSP as signaling molecules for the possible formation of the scent of the tidewater or as fish attractants.

  18. Contrasting recruitment seasonality of sea urchin species in Gran Canaria, Canary Islands (eastern Atlantic

    Directory of Open Access Journals (Sweden)

    S. GARCIA-SANZ

    2014-03-01

    Full Text Available Despite sea-urchins can play an important role affecting the community structure of subtidal bottoms, factors controlling the dynamics of sea-urchin populations are still poorly understood. We assessed the seasonal variation in recruitment of three sea-urchin species (Diadema africanum, Paracentrotus lividus and Arbacia lixula at Gran Canaria Island (eastern Atlantic via monthly deployment of artificial collectors throughout an entire annual cycle on each of four adjacent habitat patches (seagrasses, sandy patches, ‘urchin-grazed’ barrens and macroalgal-dominated beds within a shallow coastal landscape. Paracentrotus lividus and A. lixula had exclusively one main recruitment peak in late winter-spring. Diadema africanum recruitment was also seasonal, but recruits appeared in late summer-autumn, particularly on ‘urchin-grazed’ barrens with large abundances of adult conspecifics. In conclusion, this study has demonstrated non-overlapping seasonal recruitment patterns of the less abundant species (P. lividus and A. lixula with the most conspicuous species (D. africanum in the study area.

  19. Predictors of leafhopper abundance and richness in a coffee agroecosystem in Chiapas, Mexico.

    Science.gov (United States)

    Burdine, Justin D; Domínguez Martínez, Gabriel H; Philpott, Stacy M

    2014-04-01

    Coffee agroecosystems with a vegetatively complex shade canopy contain high levels of biodiversity. However, as coffee management is intensified, diversity may be lost. Most biodiversity studies in coffee agroecosystems have examined predators and not herbivores, despite their importance as potential coffee pests and coffee disease vectors. We sampled one abundant herbivore group of leafhoppers on an organic coffee farm in Chiapas, Mexico. We sampled leafhoppers with elevated pan traps in high- and moderate-shade coffee during the dry and wet seasons of 2011. The two major objectives were to 1) compare leafhopper abundance and richness during the wet and dry seasons and 2) examine the correlations between habitat characteristics (e.g., vegetation, elevation, and presence of aggressive ants) and leafhopper richness and abundance. We collected 2,351 leafhoppers, representing eight tribes and 64 morphospecies. Leafhopper abundance was higher in the dry season than in the wet season. Likewise, leafhopper richness was higher in the dry season. Several vegetation and other habitat characteristics correlated with abundance and richness of leafhoppers. The number of Inga trees positively correlated with leafhopper abundance, and other significant correlates of abundance included vegetation complexity. Leafhopper richness was correlated with the number of Inga trees. As leafhoppers transmit important coffee diseases, understanding the specific habitat factors correlating with changes in abundance and richness may help predict future disease outbreaks.

  20. Distribution And Seasonal Abundance Of Anopheline Mosquito ...

    African Journals Online (AJOL)

    The essence of this study was to identify Anopheles mosquito species in Nguru, Yobe State and to determine their distribution and relative abundance in the months of the year. Insecticide and aspirator were used to collect mosqutoes in human dwellngs and preserved in 2% formalin for identcation using dissectng ...

  1. Seasonality of macroalgal communities in a subtropical drainage basin in Paraná state, southern Brazil.

    Science.gov (United States)

    Branco, C C Z; Krupek, R A; Peres, C K

    2008-11-01

    Seasonal dynamics of macroalgal communities was analyzed monthly by samplings in three stream segments of the Pedras River Basin, mid-south region of Paraná State, southern Brazil, from April 2004 to March 2005. The seasonal fluctuations in macroalgal species richness and abundance were correlated with selected environmental variables. In general, the seasonal distribution patterns of these communities were distinct from those reported from other tropical and temperate regions, with higher macroalgal richness and abundance observed from late spring to late fall. Multiple linear regression analysis revealed that the stream variable most closely related with the temporal distribution pattern observed was temperature, which had a very similar seasonal pattern to the biological parameters. On the other hand, the floristic composition was quite diverse in the streams sampled. Among the 25 taxa identified, only two were common to the three streams whereas 15 were restricted to a single sampling site. These data indicate that, although temperature seems to be an effective relationship with global temporal pattern, particular characteristics of each stream can strongly influence the seasonal tendencies in local scale. The results of Detrended Correspondence Analysis (DCA) and Cluster Analysis corroborated this observation.

  2. Seasonality of macroalgal communities in a subtropical drainage basin in Paraná state, southern Brazil

    Directory of Open Access Journals (Sweden)

    CCZ. Branco

    Full Text Available Seasonal dynamics of macroalgal communities was analyzed monthly by samplings in three stream segments of the Pedras River Basin, mid-south region of Paraná State, southern Brazil, from April 2004 to March 2005. The seasonal fluctuations in macroalgal species richness and abundance were correlated with selected environmental variables. In general, the seasonal distribution patterns of these communities were distinct from those reported from other tropical and temperate regions, with higher macroalgal richness and abundance observed from late spring to late fall. Multiple linear regression analysis revealed that the stream variable most closely related with the temporal distribution pattern observed was temperature, which had a very similar seasonal pattern to the biological parameters. On the other hand, the floristic composition was quite diverse in the streams sampled. Among the 25 taxa identified, only two were common to the three streams whereas 15 were restricted to a single sampling site. These data indicate that, although temperature seems to be an effective relationship with global temporal pattern, particular characteristics of each stream can strongly influence the seasonal tendencies in local scale. The results of Detrended Correspondence Analysis (DCA and Cluster Analysis corroborated this observation.

  3. Phytoplankton dynamics in relation to seasonal variability and upwelling and relaxation patterns at the mouth of Ria de Aveiro (West Iberian Margin over a four-year period.

    Directory of Open Access Journals (Sweden)

    Tânia Vidal

    Full Text Available From June 2004 to December 2007, samples were weekly collected at a fixed station located at the mouth of Ria de Aveiro (West Iberian Margin. We examined the seasonal and inter-annual fluctuations in composition and community structure of the phytoplankton in relation to the main environmental drivers and assessed the influence of the oceanographic regime, namely changes in frequency and intensity of upwelling events, over the dynamics of the phytoplankton assemblage. The samples were consistently handled and a final subset of 136 OTUs (taxa with relative abundance > 0.01% was subsequently submitted to various multivariate analyses. The phytoplankton assemblage showed significant changes at all temporal scales but with an overriding importance of seasonality over longer- (inter-annual or shorter-term fluctuations (upwelling-related. Sea-surface temperature, salinity and maximum upwelling index were retrieved as the main driver of seasonal change. Seasonal signal was most evident in the fluctuations of chlorophyll a concentration and in the high turnover from the winter to spring phytoplankton assemblage. The seasonal cycle of production and succession was disturbed by upwelling events known to disrupt thermal stratification and induce changes in the phytoplankton assemblage. Our results indicate that both the frequency and intensity of physical forcing were important drivers of such variability, but the outcome in terms of species composition was highly dependent on the available local pool of species and the timing of those events in relation to the seasonal cycle. We conclude that duration, frequency and intensity of upwelling events, which vary seasonally and inter-annually, are paramount for maintaining long-term phytoplankton diversity likely by allowing unstable coexistence and incorporating species turnover at different scales. Our results contribute to the understanding of the complex mechanisms of coastal phytoplankton dynamics in

  4. Seasonal Oxygen Dynamics in a Thermokarst Bog in Interior Alaska: Implications for Rates of Methane Oxidation

    Science.gov (United States)

    Neumann, R. B.; Moorberg, C.; Wong, A.; Waldrop, M. P.; Turetsky, M. R.

    2015-12-01

    Methane is a potent greenhouse gas, and wetlands represent the largest natural source of methane to the atmosphere. However, much of the methane generated in anoxic wetlands never gets emitted to the atmosphere; up to >90% of generated methane can get oxidized to carbon dioxide. Thus, oxidation is an important methane sink and changes in the rate of methane oxidation can affect wetland methane emissions. Most methane is aerobically oxidized at oxic-anoxic interfaces where rates of oxidation strongly depend on methane and oxygen concentrations. In wetlands, oxygen is often the limiting substrate. To improve understanding of belowground oxygen dynamics and its impact on methane oxidation, we deployed two planar optical oxygen sensors in a thermokarst bog in interior Alaska. Previous work at this site indicated that, similar to other sites, rates of methane oxidation decrease over the growing season. We used the sensors to track spatial and temporal patterns of oxygen concentrations over the growing season. We coupled these in-situ oxygen measurements with periodic oxygen injection experiments performed against the sensor to quantify belowground rates of oxygen consumption. We found that over the season, the thickness of the oxygenated water layer at the peatland surface decreased. Previous research has indicated that in sphagnum-dominated peatlands, like the one studied here, rates of methane oxidation are highest at or slightly below the water table. It is in these saturated but oxygenated locations that both methane and oxygen are available. Thus, a seasonal reduction in the thickness of the oxygenated water layer could restrict methane oxidation. The decrease in thickness of the oxygenated layer coincided with an increase in the rate of oxygen consumption during our oxygen injection experiments. The increase in oxygen consumption was not explained by temperature; we infer it was due to an increase in substrate availability for oxygen consuming reactions and

  5. Temporal dynamics of arthropods on six tree species in dry woodlands on the Caribbean Island of Puerto Rico.

    Science.gov (United States)

    Beltrán, William; Wunderle, Joseph M

    2014-01-01

    The seasonal dynamics of foliage arthropod populations are poorly studied in tropical dry forests despite the importance of these studies for understanding arthropod population responses to environmental change. We monitored the abundance, temporal distributions, and body size of arthropods in five naturalized alien and one native tree species to characterize arthropod seasonality in dry novel Prosopis-Leucaena woodlands in Puerto Rico. A branch clipping method was used monthly to sample foliage arthropod abundance over 39 mo. Seasonal patterns of rainfall and abundance within various arthropod taxa were highly variable from year to year. Abundance for most taxa did not show significant seasonality over the 3 yr, although most taxa had abundance peaks each year. However, Homoptera displayed high seasonality with significant temporal aggregations in each year. Formicidae, Orthoptera, and Coleoptera showed high variation in abundance between wet and dry periods, whereas Hemiptera were consistently more abundant in the wet period. Seasonal differences in mean abundance were found only in a few taxa on Tamarindus indica L., Bucida buceras L., Pithecellobium dulce, and (Roxburgh) Benth. Mean arthropod abundance varied among tree species, with highest numbers on Prosopis juliflora, (Swartz) De Candolle, Pi. dulce, Leucaena leucocephala, and (Lamarck) de Wit. Abundance of Araneae, Orthoptera, Coleoptera, Lepidoptera larvae, and all arthropods showed weak relationships with one or more climatic variables (rainfall, maximum temperature, or relative humidity). Body size of arthropods was usually largest during the dry periods. Overall, total foliage arthropod abundance showed no consistent seasonality among years, which may become a more common trend in dry forests and woodlands in the Caribbean if seasonality of rainfall becomes less predictable. © The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.

  6. Comparative dynamics, seasonality in transmission, and predictability of childhood infections in Mexico

    Science.gov (United States)

    Mahmud, A. S.; Metcalf, C. J. E.; Grenfell, B. T.

    2018-01-01

    The seasonality and periodicity of infections, and the mechanisms underlying observed dynamics, can have implications for control efforts. This is particularly true for acute childhood infections. Among these, the dynamics of measles is the best understood and has been extensively studied, most notably in the UK prior to the start of vaccination. Less is known about the dynamics of other childhood diseases, particularly outside Europe and the US. In this paper, we leverage a unique dataset to examine the epidemiology of six childhood infections - measles, mumps, rubella, varicella, scarlet fever and pertussis - across 32 states in Mexico from 1985 to 2007. This dataset provides us with a spatiotemporal probe into the dynamics of six common childhood infections, and allows us to compare them in the same setting over the same time period. We examine three key epidemiological characteristics of these infections – the age profile of infections, spatiotemporal dynamics, and seasonality in transmission - and compare with predictions from existing theory and past findings. Our analysis reveals interesting epidemiological differences between the six pathogens, and variations across space. We find signatures of term time forcing (reduced transmission during the summer) for measles, mumps, rubella, varicella, and scarlet fever; for pertussis, a lack of term time forcing could not be rejected. PMID:27873563

  7. Pan-Antarctic analysis aggregating spatial estimates of Adélie penguin abundance reveals robust dynamics despite stochastic noise.

    Science.gov (United States)

    Che-Castaldo, Christian; Jenouvrier, Stephanie; Youngflesh, Casey; Shoemaker, Kevin T; Humphries, Grant; McDowall, Philip; Landrum, Laura; Holland, Marika M; Li, Yun; Ji, Rubao; Lynch, Heather J

    2017-10-10

    Colonially-breeding seabirds have long served as indicator species for the health of the oceans on which they depend. Abundance and breeding data are repeatedly collected at fixed study sites in the hopes that changes in abundance and productivity may be useful for adaptive management of marine resources, but their suitability for this purpose is often unknown. To address this, we fit a Bayesian population dynamics model that includes process and observation error to all known Adélie penguin abundance data (1982-2015) in the Antarctic, covering >95% of their population globally. We find that process error exceeds observation error in this system, and that continent-wide "year effects" strongly influence population growth rates. Our findings have important implications for the use of Adélie penguins in Southern Ocean feedback management, and suggest that aggregating abundance across space provides the fastest reliable signal of true population change for species whose dynamics are driven by stochastic processes.Adélie penguins are a key Antarctic indicator species, but data patchiness has challenged efforts to link population dynamics to key drivers. Che-Castaldo et al. resolve this issue using a pan-Antarctic Bayesian model to infer missing data, and show that spatial aggregation leads to more robust inference regarding dynamics.

  8. Spatiotemporal variations in the abundance and composition of bulk and chromophoric dissolved organic matter in seasonally hypoxia-influenced Green Bay, Lake Michigan, USA.

    Science.gov (United States)

    DeVilbiss, Stephen E; Zhou, Zhengzhen; Klump, J Val; Guo, Laodong

    2016-09-15

    Green Bay, Lake Michigan, USA, is the largest freshwater estuary in the Laurentian Great Lakes and receives disproportional terrestrial inputs as a result of a high watershed to bay surface area ratio. While seasonal hypoxia and the formation of "dead zones" in Green Bay have received increasing attention, there are no systematic studies on the dynamics of dissolved organic matter (DOM) and its linkage to the development of hypoxia. During summer 2014, bulk dissolved organic carbon (DOC) analysis, UV-vis spectroscopy, and fluorescence excitation-emission matrices (EEMs) coupled with PARAFAC analysis were used to quantify the abundance, composition and source of DOM and their spatiotemporal variations in Green Bay, Lake Michigan. Concentrations of DOC ranged from 202 to 571μM-C (average=361±73μM-C) in June and from 279 to 610μM-C (average=349±64μM-C) in August. In both months, absorption coefficient at 254nm (a254) was strongly correlated to bulk DOC and was most abundant in the Fox River, attesting a dominant terrestrial input. Non-chromophoric DOC comprised, on average, ~32% of bulk DOC in June with higher terrestrial DOM and ~47% in August with higher aquagenic DOM, indicating that autochthonous and more degraded DOM is of lower optical activity. PARAFAC modeling on EEM data resulted in four major fluorescent DOM components, including two terrestrial humic-like, one aquagenic humic-like, and one protein-like component. Variations in the abundance of DOM components further supported changes in DOM sources. Mixing behavior of DOM components also indicated that while bulk DOM behaved quasi-conservatively, significant compositional changes occurred during transport from the Fox River to the open bay. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Aquatic environmental DNA detects seasonal fish abundance and habitat preference in an urban estuary.

    Directory of Open Access Journals (Sweden)

    Mark Y Stoeckle

    Full Text Available The difficulty of censusing marine animal populations hampers effective ocean management. Analyzing water for DNA traces shed by organisms may aid assessment. Here we tested aquatic environmental DNA (eDNA as an indicator of fish presence in the lower Hudson River estuary. A checklist of local marine fish and their relative abundance was prepared by compiling 12 traditional surveys conducted between 1988-2015. To improve eDNA identification success, 31 specimens representing 18 marine fish species were sequenced for two mitochondrial gene regions, boosting coverage of the 12S eDNA target sequence to 80% of local taxa. We collected 76 one-liter shoreline surface water samples at two contrasting estuary locations over six months beginning in January 2016. eDNA was amplified with vertebrate-specific 12S primers. Bioinformatic analysis of amplified DNA, using a reference library of GenBank and our newly generated 12S sequences, detected most (81% locally abundant or common species and relatively few (23% uncommon taxa, and corresponded to seasonal presence and habitat preference as determined by traditional surveys. Approximately 2% of fish reads were commonly consumed species that are rare or absent in local waters, consistent with wastewater input. Freshwater species were rarely detected despite Hudson River inflow. These results support further exploration and suggest eDNA will facilitate fine-scale geographic and temporal mapping of marine fish populations at relatively low cost.

  10. Seasonality distribution of the abundance and activity of nitrification and denitrification microorganisms in sediments of surface flow constructed wetlands planted with Myriophyllum elatinoides during swine wastewater treatment.

    Science.gov (United States)

    Li, Xi; Zhang, Miaomiao; Liu, Feng; Chen, Liang; Li, Yuyuan; Li, Yong; Xiao, Rulin; Wu, Jinshui

    2018-01-01

    Surface flow constructed wetlands (SFCWs) planted with Myriophyllum elatinoides for treatment of swine wastewater were examined to evaluate the effect of season, segment (site S1, S2, and S3), and treatment (100mgL -1 TN, T1; 300mgL -1 TN, T2; 500mgL -1 TN, T3) on the activity, and abundances of nitrifying and, denitrifying microorganisms, and on the abundance of sediment bacteria. The activity and abundances of nitrifiers, denitrifiers, and the abundance of bacteria were the highest in T3 samples, especially in S1 (Pswine wastewater treatment stimulate the growth of nitrifiers, denitrifiers and bacteria in sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. The distribution, relative abundance, and seasonal phenology of Ceratitis capitata, Ceratitis rosa, and Ceratitis cosyra (Diptera: Tephritidae) in South Africa.

    Science.gov (United States)

    De Villiers, Marelize; Manrakhan, Aruna; Addison, Pia; Hattingh, Vaughan

    2013-10-01

    Ceratitis capitata (Wiedemann), Ceratitis rosa Karsch, and Ceratitis cosyra (Walker) are fruit fly species (Diptera: Tephritidae) of economic importance in South Africa. These pests cause direct damage to a number of commercially produced fruit and are of phytosanitary concern. A study was conducted to determine the distribution, relative abundance, and seasonal occurrence of the three species in different climatic regions of South Africa. The relative abundance and seasonal phenology of C. capitata and C. rosa were also compared between production areas and home gardens in Stellenbosch, Western Cape. Yellow bucket traps baited with Biolure were used to trap the flies over a 2-yr period in the different sampling areas. Different fruit types were sampled in Stellenbosch to determine fruit fly infestation. C. capitata was found to have a widespread distribution in South Africa, whereas C. rosa were absent from or only present in low numbers in the drier regions. C. cosyra was restricted to the North East and East coast, following a similar pattern to the distribution of marula, Sclerocarrya birrea, an important wild host. Fruit in home gardens provided a breeding ground for C. capitata and C. rosa and a source for infestation of orchards when fruit started to mature, highlighting the need for an area-wide strategy for the control of fruit flies.

  12. Effect Of Agrotechnical Measures And Varieties On Seasonal Dynamics Of Tetranychus Urticae Koch (Acari, Trombidiformes, Tetranychidae On High Tunnel-Cultivated Garden Strawberries

    Directory of Open Access Journals (Sweden)

    Salmane Ineta

    2015-04-01

    Full Text Available The aim of the present study was to determine the seasonal pattern of two-spotted spider mite Tetranychus urticae on strawberries cultivated in polythene-covered high tunnels in temperate climatic conditions. Various cultivars were used and the effect of modification of plant covering indices on abundance and incidence of these mites was also tested. The number of two-spotted spider mites was relatively low at the beginning of the vegetation season and started to increase when average air temperature rose above 20 to 25 °C. In the experiment two types of tunnels differing in additional plant cover were used. The maximum mite abundance did not significantly vary between varieties in tunnel 1 conditions, but it was significantly lower for variety 'Sonata' in tunnel 2 conditions. Mite numbers significantly declined after strawberry foliage mowing and removal of polythene cover. Mite development was prolonged in tunnel 1, where additional cover of plants was used and higher early season air temperature was recorded in comparison to tunnel 2. It was concluded that increase in early season temperature can increase two-spotted spider mite abundance and have a more negative effect on strawberry plants in respect of foliage damage by mites.

  13. Seasonal variation of ground spiders in a Brazilian Savanna

    Directory of Open Access Journals (Sweden)

    Marina Farcic Mineo

    2010-06-01

    Full Text Available The Brazilian Savanna Ecoregion (Cerrado is one of the richest biomes in the world, with a characteristic highly seasonal climate a dry season between May and September and a rainy season from October through April. Ground-dwelling spiders from three Cerrado phytophysiognomies, "campo cerrado", "cerrado" and "cerrad��o", were sampled using pitfall traps during two years, totaling 111 species and 3,529 individuals. The abundance of individuals and species richness was higher during the wet season. Fifty-eight species were captured exclusively during that period, whereas only nineteen were restricted to the dry season. Only two species were found in all samples. The number of juveniles was higher than the number of adults in all phytophysiognomies and in all species during both seasons. The highest abundance was registered in October and the lowest in April. Overall sex ratio was male-biased in all vegetation types sampled. Distinct climate variables affected the abundance of spiders depending on sex, age and vegetal physiognomy where they were sampled. This study involved the longest sampling of spider abundance and diversity on the ground of a Brazilian Savanna.

  14. Dogwood Borer (Lepidoptera: Sesiidae) Abundance and Seasonal Flight Activity in Apple Orchards, Urban Landscapes, and Woodlands in Five Eastern States

    OpenAIRE

    Bergh, J. C.; Leskey, T. C.; Walgenbach, J. F.; Klingeman, W. E.; Kain, D. P.; Zhang, A.

    2017-01-01

    The relative abundance and seasonal flight activity of dogwood borer, Synanthedon scitula Harris (Lepidoptera: Sesiidae), was measured using weekly records from traps baited with its sex pheromone and deployed in apple orchards, urban landscapes, and native woodland sites in New York, West Virginia, Virginia, North Carolina, and Tennessee in 2005 and 2006. The mean total number of moths captured per site in apple orchards was 3,146 ± 644 and 3095 ± 584 SE in 2005 and 2006, respectively, excee...

  15. Seasonal dynamics and functioning of the Sylt-Rømø Bight, northern Wadden Sea

    Science.gov (United States)

    de la Vega, Camille; Horn, Sabine; Baird, Dan; Hines, David; Borrett, Stuart; Jensen, Lasse Fast; Schwemmer, Philipp; Asmus, Ragnhild; Siebert, Ursula; Asmus, Harald

    2018-04-01

    The Wadden Sea undergoes large seasonal changes in species abundance and biomass comprising its complex food web. This study examined four carbon food web models of the Sylt-Rømø Bight, one for each season. Each flow model consisted of 66 compartments depicting the respective biomass and energy budget of each ecosystem component and the flows between them. Ecological network analysis (ENA), a set of algorithms to evaluate the functioning of ecological networks, was used to assess the seasonal variability in the system properties of the Sylt-Rømø Bight food webs. We used an uncertainty analysis to quantitatively evaluate the significance of inter-seasonal differences. Clear seasonal variation was observed in most of the whole system indicators such as the flow diversity, the effective link density and the relative redundancy which varied by 12.8%, 17.3% and 10.3% respectively between the highest in summer and the lowest during fall and winter, whereas the relevant ascendency ratio was the highest in winter during the least active months. Other indices such as the average mutual information index, which fluctuated between 1.73 in fall and 1.79 in spring, showed no significant variation between seasons. Results from ENA have great potential for ecosystem management, as it provides a holistic assessment of the functioning of ecosystems.

  16. Effects of irrigation on the seasonal abundance of Empoasca vitis in north-Italian vineyards.

    Science.gov (United States)

    Fornasiero, D; Duso, C; Pozzebon, A; Tomasi, D; Gaiotti, F; Pavan, F

    2012-02-01

    The effect of irrigation on the abundance of Empoasca vitis (Göthe) populations was investigated in four vineyards located in northeastern Italy. In two experiments, we compared leafhopper population densities in plots irrigated (micro-spray irrigation system) or nonirrigated. In another experiment, we studied the effect of various irrigation systems on E. vitis populations over two successive seasons. In particular, five treatments were compared: control (not irrigated), traditional drip system, three types of subirrigation varying in distance from the row (40, 135, and 95 cm). In this vineyard, stem water potential was monitored with a pressure chamber. E. vitis population densities were affected by irrigation, with higher densities of this pest recorded on irrigated vines. Highest E. vitis densities were detected in drip irrigation plots compared with nonirrigated plots where water stress was highest. Moderate water stress (subirrigation plots) was associated with intermediate leafhopper densities. Implications for integrated pest management are discussed.

  17. Seasonal dynamics and vertical distribution of plant-feeding nematode communities in grasslands

    NARCIS (Netherlands)

    Verschoor, B.C.; Goede, de R.G.M.; Hoop, de J.W.; Vries, de F.W.

    2001-01-01

    The vertical distribution and seasonal dynamics of plant- and fungal-feeding nematode taxa in permanent grasslands were investigated. Dolichodoridae, Paratylenchus, Pratylenchus, Tylenchidae and Aphelenchoides dominated the upper 10 cm soil and their numbers strongly decreased with depth. The

  18. Individual and collective stock dynamics: intra-day seasonalities

    International Nuclear Information System (INIS)

    Allez, Romain; Bouchaud, Jean-Philippe

    2011-01-01

    We establish several new stylized facts concerning the intra-day seasonalities of stock dynamics. Beyond the well-known U-shaped pattern of the volatility, we find that the average correlation between stocks increases throughout the day, leading to a smaller relative dispersion between stocks. Somewhat paradoxically, the kurtosis (a measure of volatility surprises) reaches a minimum at the open of the market, when the volatility is at its peak. We confirm that the dispersion kurtosis is a markedly decreasing function of the index return. This means that during large market swings, the idiosyncratic component of the stock dynamics becomes sub-dominant. In a nutshell, the early hours of trading are dominated by idiosyncratic or sector-specific effects with little surprises, whereas the influence of the market factor increases throughout the day, and surprises become more frequent.

  19. Seasonal migrations, body temperature fluctuations, and infection dynamics in adult amphibians

    Directory of Open Access Journals (Sweden)

    David R. Daversa

    2018-05-01

    Full Text Available Risks of parasitism vary over time, with infection prevalence often fluctuating with seasonal changes in the annual cycle. Identifying the biological mechanisms underlying seasonality in infection can enable better prediction and prevention of future infection peaks. Obtaining longitudinal data on individual infections and traits across seasons throughout the annual cycle is perhaps the most effective means of achieving this aim, yet few studies have obtained such information for wildlife. Here, we tracked spiny common toads (Bufo spinosus within and across annual cycles to assess seasonal variation in movement, body temperatures and infection from the fungal parasite, Batrachochytrium dendrobatidis (Bd. Across annual cycles, toads did not consistently sustain infections but instead gained and lost infections from year to year. Radio-tracking showed that infected toads lose infections during post-breeding migrations, and no toads contracted infection following migration, which may be one explanation for the inter-annual variability in Bd infections. We also found pronounced seasonal variation in toad body temperatures. Body temperatures approached 0 °C during winter hibernation but remained largely within the thermal tolerance range of Bd. These findings provide direct documentation of migratory recovery (i.e., loss of infection during migration and escape in a wild population. The body temperature reductions that we observed during hibernation warrant further consideration into the role that this period plays in seasonal Bd dynamics.

  20. Effects of seasonality and resource limitation on organic matter turnover by Chironomidae (Diptera) in southern Appalachian headwater streams

    Science.gov (United States)

    Angela Romito; Susan Eggert; Jeffrey Diez; J. Wallace

    2010-01-01

    Despite their high abundance, secondary production, and known reliance on detrital material, the role of chironomids (Diptera) in fine particulate organic matter (FPOM) dynamics has not been well quantified. We conducted field trials using fluorescent pigment markers to estimate seasonal rates of consumption, annual secondary production, assimilation efficiency (AE),...

  1. Seasonal dynamics of dissolved, particulate and microbial components of a tidal saltmarsh-dominated estuary under contrasting levels of freshwater discharge

    Science.gov (United States)

    Bittar, Thais B.; Berger, Stella A.; Birsa, Laura M.; Walters, Tina L.; Thompson, Megan E.; Spencer, Robert G. M.; Mann, Elizabeth L.; Stubbins, Aron; Frischer, Marc E.; Brandes, Jay A.

    2016-12-01

    affect total abundance of phytoplankton (<52 μm) or chlorophyll-a concentrations, a proxy for phytoplankton biomass. Phytoplankton community dynamics were primarily seasonally-driven. Bacterioplankton abundance and community composition, based upon flow cytometry, were affected by discharge, possibly due to decreased salinity and/or increased inputs of terrigenous DOM. Seasonal patterns in inorganic nutrient, POC, PON and chlorophyll-a concentrations, and Secchi depth were not significantly influenced by the 2013 increase in discharge. For other components, most notably δ13C-DIC values, DOM and bacterioplankton, the influence of increased discharge in 2013 was superimposed upon their seasonal patterns. This study showed that in addition to tidal mixing and in situ saltmarsh and estuarine production and removal processes, the level of riverine freshwater discharge impacted the quantity and character of many water column components in this tidal saltmarsh ecosystem.

  2. Seasonality in Abundance, Biomass and Production of the Phytoplankton of Welala and Shesher Wetlands, Lake Tana Sub-Basin (Ethiopia)

    NARCIS (Netherlands)

    Wondmagegne, K.; Wondie, A.; Mingist, M.; Vijverberg, J.

    2012-01-01

    The species composition and production of the phytoplankton community of the Shesher and Welala floodplain Wetlands, on the eastern side of Lake Tana, were studied during four seasons from July 2009 to May 2010. We investigated the spatial and temporal dynamics of phytoplankton, densities, biomass,

  3. Seasonal prediction of the Leeuwin Current using the POAMA dynamical seasonal forecast model

    Energy Technology Data Exchange (ETDEWEB)

    Hendon, Harry H.; Wang, Guomin [Centre for Australian Weather and Climate Research, Bureau of Meteorology, PO Box 1289, Melbourne (Australia)

    2010-06-15

    The potential for predicting interannual variations of the Leeuwin Current along the west coast of Australia is addressed. The Leeuwin Current flows poleward against the prevailing winds and transports warm-fresh tropical water southward along the coast, which has a great impact on local climate and ecosystems. Variations of the current are tightly tied to El Nino/La Nina (weak during El Nino and strong during La Nina). Skilful seasonal prediction of the Leeuwin Current to 9-month lead time is achieved by empirical downscaling of dynamical coupled model forecasts of El Nino and the associated upper ocean heat content anomalies off the north west coast of Australia from the Australian Bureau of Meteorology Predictive Ocean Atmosphere Model for Australia (POAMA) seasonal forecast system. Prediction of the Leeuwin Current is possible because the heat content fluctuations off the north west coast are the primary driver of interannual annual variations of the current and these heat content variations are tightly tied to the occurrence of El Nino/La Nina. POAMA can skilfully predict both the occurrence of El Nino/La Nina and the subsequent transmission of the heat content anomalies from the Pacific onto the north west coast. (orig.)

  4. Plant nitrogen dynamics and nitrogen-use strategies under altered nitrogen seasonality and competition.

    Science.gov (United States)

    Yuan, Zhiyou; Liu, Weixing; Niu, Shuli; Wan, Shiqiang

    2007-10-01

    Numerous studies have examined the effects of climatic factors on the distribution of C(3) and C(4) grasses in various regions throughout the world, but the role of seasonal fluctuations in temperature, precipitation and soil N availability in regulating growth and competition of these two functional types is still not well understood. This report is about the effects of seasonality of soil N availability and competition on plant N dynamics and N-use strategies of one C(3) (Leymus chinensis) and one C(4) (Chloris virgata) grass species. Leymus chinensis and C. virgata, two grass species native to the temperate steppe in northern China, were planted in a monoculture and a mixture under three different N seasonal availabilities: an average model (AM) with N evenly distributed over the growing season; a one-peak model (OM) with more N in summer than in spring and autumn; and a two-peak model (TM) with more N in spring and autumn than in summer. The results showed that the altered N seasonality changed plant N concentration, with the highest value of L. chinensis under the OM treatment and C. virgata under the TM treatment, respectively. N seasonality also affected plant N content, N productivity and N-resorption efficiency and proficiency in both the C(3) and C(4) species. Interspecific competition influenced N-use and resorption efficiency in both the C(3) and C(4) species, with higher N-use and resorption efficiency in the mixture than in monoculture. The C(4) grass had higher N-use efficiency than the C(3) grass due to its higher N productivity, irrespective of the N treatment or competition. The observations suggest that N-use strategies in the C(3) and C(4) species used in the study were closely related to seasonal dynamics of N supply and competition. N seasonality might be involved in the growth and temporal niche separation between C(3) and C(4) species observed in the natural ecosystems.

  5. Seasonal dynamics of bacterial biomass and production in a coastal arctic ecosystem: Franklin Bay, western Canadian Arctic

    Science.gov (United States)

    Garneau, Marie-Ã. Ve; Roy, SéBastien; Lovejoy, Connie; Gratton, Yves; Vincent, Warwick F.

    2008-07-01

    The Canadian Arctic Shelf Exchange Study (CASES) included the overwintering deployment of a research platform in Franklin Bay (70°N, 126°W) and provided a unique seasonal record of bacterial dynamics in a coastal region of the Arctic Ocean. Our objectives were (1) to relate seasonal bacterial abundance (BA) and production (BP) to physico-chemical characteristics and (2) to quantify the annual bacterial carbon flux. BA was estimated by epifluorescence microscopy and BP was estimated from 3H-leucine and 3H-thymidine assays. Mean BA values for the water column ranged from 1.0 (December) to 6.8 × 105 cells mL-1 (July). Integral BP varied from 1 (February) to 80 mg C m-2 d-1 (July). During winter-spring, BP was uncorrelated with chlorophyll a (Chl a), but these variables were significantly correlated during summer-autumn (rs = 0.68, p winter, late winter-late spring, and summer. A baseline level of BB and BP was maintained throughout late winter-late spring despite the persistent cold and darkness, with irregular fluctuations that may be related to hydrodynamic events. During this period, BP rates were correlated with colored dissolved organic matter (CDOM) but not Chl a (rs BP.CDOM∣Chl a = 0.20, p < 0.05, N = 176). Annual BP was estimated as 6 g C m-2 a-1, implying a total BP of 4.8 × 1010 g C a-1 for the Franklin Bay region. These results show that bacterial processes continue throughout all seasons and make a large contribution to the total biological carbon flux in this coastal arctic ecosystem.

  6. The specificity of host-bat fly interaction networks across vegetation and seasonal variation.

    Science.gov (United States)

    Zarazúa-Carbajal, Mariana; Saldaña-Vázquez, Romeo A; Sandoval-Ruiz, César A; Stoner, Kathryn E; Benitez-Malvido, Julieta

    2016-10-01

    Vegetation type and seasonality promote changes in the species composition and abundance of parasite hosts. However, it is poorly known how these variables affect host-parasite interaction networks. This information is important to understand the dynamics of parasite-host relationships according to biotic and abiotic changes. We compared the specialization of host-bat fly interaction networks, as well as bat fly and host species composition between upland dry forest and riparian forest and between dry and rainy seasons in a tropical dry forest in Jalisco, Mexico. Bat flies were surveyed by direct collection from bats. Our results showed that host-bat fly interaction networks were more specialized in upland dry forest compared to riparian forest. Bat fly species composition was different between the dry and rainy seasons, while host species composition was different between upland dry forest and riparian forest. The higher specialization in upland dry forest could be related to the differences in bat host species composition and their respective roosting habits. Variation in the composition of bat fly species between dry and rainy seasons coincides with the seasonal shifts in their species richness. Our study confirms the high specialization of host-bat fly interactions and shows the importance of biotic and abiotic factors to understand the dynamics of parasite-host interactions.

  7. Fungi diversity in PM2. 5 and PM1 at the summit of Mt. Tai: abundance, size distribution, and seasonal variation

    Science.gov (United States)

    Xu, Caihong; Wei, Min; Chen, Jianmin; Zhu, Chao; Li, Jiarong; Lv, Ganglin; Xu, Xianmang; Zheng, Lulu; Sui, Guodong; Li, Weijun; Chen, Bing; Wang, Wenxing; Zhang, Qingzhu; Ding, Aijun; Mellouki, Abdelwahid

    2017-09-01

    Fungi are ubiquitous throughout the near-surface atmosphere, where they represent an important component of primary biological aerosol particles. This study combined internal transcribed spacer region sequencing and quantitative real-time polymerase chain reaction (qPCR) to investigate the ambient fungi in fine (PM2. 5, 50 % cutoff aerodynamic diameter Da50 = 2.5 µm, geometric standard deviation of collection efficiency σg = 1.2) and submicron (PM1, Da50 = 1 µm, σg = 1.2) particles at the summit of Mt. Tai located in the North China Plain, China. Fungal abundance values were 9.4 × 104 and 1.3 × 105 copies m-3 in PM2. 5 and PM1, respectively. Most of the fungal sequences were from Ascomycota and Basidiomycota, which are known to actively discharge spores into the atmosphere. The fungal community showed a significant seasonal shift across different size fractions according to Metastats analysis and the Kruskal-Wallis rank sum test. The abundance of Glomerella and Zasmidium increased in larger particles in autumn, whereas Penicillium, Bullera, and Phaeosphaeria increased in smaller particles in winter. Environmental factors, namely Ca2+, humidity, and temperature, were found to be crucial for the seasonal variation in the fungal community. This study might serve as an important reference for fungal contribution to primary biological aerosol particles.

  8. Seasonal methane dynamics in three temperate grasslands on peat

    DEFF Research Database (Denmark)

    Schäfer, Carolyn; Elsgaard, Lars; Hoffmann, Carl Christian

    2012-01-01

    Background and Aims Drained peatlands are considered to be insignificant CH4 sources, but the effect of drainage on CH4 dynamics has not been extensively studied. We investigated seasonal dynamics of CH4 in two fen peat soils and one bog peat soil under permanent grassland in Denmark. Methods Soil......, even though soil CH4 concentrations of up to 155 and 1000 μmol CH4 dm−3 were measured in one of the fen peats and in the bog peat, respectively. Significant CH4 concentrations were observed above the water table. Methane production assays confirmed the presence of viable methanogens in the upper parts...... of the bog peat soil. The aerenchymous plant Juncus effusus L. liberated CH4 from the peat at rates of up to 3.3 mg CH4 m−2 h−1. No CH4 dynamics were observed in the second fen peat which, in contrast to the other two sites, had high sulfate concentrations. Conclusions Peat type and the distribution...

  9. Seasonality in cholera dynamics: A rainfall-driven model explains the wide range of patterns in endemic areas

    Science.gov (United States)

    Baracchini, Theo; King, Aaron A.; Bouma, Menno J.; Rodó, Xavier; Bertuzzo, Enrico; Pascual, Mercedes

    2017-10-01

    Seasonal patterns in cholera dynamics exhibit pronounced variability across geographical regions, showing single or multiple peaks at different times of the year. Although multiple hypotheses related to local climate variables have been proposed, an understanding of this seasonal variation remains incomplete. The historical Bengal region, which encompasses the full range of cholera's seasonality observed worldwide, provides a unique opportunity to gain insights on underlying environmental drivers. Here, we propose a mechanistic, rainfall-temperature driven, stochastic epidemiological model which explicitly accounts for the fluctuations of the aquatic reservoir, and analyze with this model the historical dataset of cholera mortality in the Bengal region. Parameters are inferred with a recently developed sequential Monte Carlo method for likelihood maximization in partially observed Markov processes. Results indicate that the hydrological regime is a major driver of the seasonal dynamics of cholera. Rainfall tends to buffer the propagation of the disease in wet regions due to the longer residence times of water in the environment and an associated dilution effect, whereas it enhances cholera resurgence in dry regions. Moreover, the dynamics of the environmental water reservoir determine whether the seasonality is unimodal or bimodal, as well as its phase relative to the monsoon. Thus, the full range of seasonal patterns can be explained based solely on the local variation of rainfall and temperature. Given the close connection between cholera seasonality and environmental conditions, a deeper understanding of the underlying mechanisms would allow the better management and planning of public health policies with respect to climate variability and climate change.

  10. Fish and phytoplankton exhibit contrasting temporal species abundance patterns in a dynamic north temperate lake.

    Directory of Open Access Journals (Sweden)

    Gretchen J A Hansen

    Full Text Available Temporal patterns of species abundance, although less well-studied than spatial patterns, provide valuable insight to the processes governing community assembly. We compared temporal abundance distributions of two communities, phytoplankton and fish, in a north temperate lake. We used both 17 years of observed relative abundance data as well as resampled data from Monte Carlo simulations to account for the possible effects of non-detection of rare species. Similar to what has been found in other communities, phytoplankton and fish species that appeared more frequently were generally more abundant than rare species. However, neither community exhibited two distinct groups of "core" (common occurrence and high abundance and "occasional" (rare occurrence and low abundance species. Both observed and resampled data show that the phytoplankton community was dominated by occasional species appearing in only one year that exhibited large variation in their abundances, while the fish community was dominated by core species occurring in all 17 years at high abundances. We hypothesize that the life-history traits that enable phytoplankton to persist in highly dynamic environments may result in communities dominated by occasional species capable of reaching high abundances when conditions allow. Conversely, longer turnover times and broad environmental tolerances of fish may result in communities dominated by core species structured primarily by competitive interactions.

  11. Fish and Phytoplankton Exhibit Contrasting Temporal Species Abundance Patterns in a Dynamic North Temperate Lake

    Science.gov (United States)

    Hansen, Gretchen J. A.; Carey, Cayelan C.

    2015-01-01

    Temporal patterns of species abundance, although less well-studied than spatial patterns, provide valuable insight to the processes governing community assembly. We compared temporal abundance distributions of two communities, phytoplankton and fish, in a north temperate lake. We used both 17 years of observed relative abundance data as well as resampled data from Monte Carlo simulations to account for the possible effects of non-detection of rare species. Similar to what has been found in other communities, phytoplankton and fish species that appeared more frequently were generally more abundant than rare species. However, neither community exhibited two distinct groups of “core” (common occurrence and high abundance) and “occasional” (rare occurrence and low abundance) species. Both observed and resampled data show that the phytoplankton community was dominated by occasional species appearing in only one year that exhibited large variation in their abundances, while the fish community was dominated by core species occurring in all 17 years at high abundances. We hypothesize that the life-history traits that enable phytoplankton to persist in highly dynamic environments may result in communities dominated by occasional species capable of reaching high abundances when conditions allow. Conversely, longer turnover times and broad environmental tolerances of fish may result in communities dominated by core species structured primarily by competitive interactions. PMID:25651399

  12. Peripartal rumination dynamics and health status in cows calving in hot and cool seasons.

    Science.gov (United States)

    Paudyal, S; Maunsell, F; Richeson, J; Risco, C; Donovan, A; Pinedo, P

    2016-11-01

    Our objective was to evaluate the effect of season of calving, associated with variable levels of heat stress, on the dynamics of rumination during the prepartum period and early lactation of cows that were healthy or affected by peripartal health disorders. Three weeks before the estimated due date, 210 multiparous Holstein cows at the University of Florida Dairy Unit were affixed with a neck collar containing rumination loggers, providing rumination time (RT) in 2-h periods. One blood sample was collected in a subpopulation of cows (n=76) at 12 to 48h postcalving to assess metabolic status by determining serum calcium, nonesterified fatty acid, and β-hydroxybutyrate concentrations. The occurrence of peripartal health disorders (dystocia, clinical ketosis, clinical hypocalcemia, metritis, and mastitis) was assessed by University of Florida veterinarians and trained farm personnel. We analyzed the dynamics of daily RT over ± 14d relative to parturition in cows that were healthy or affected by specific health disorders by season of calving [hot season, June to September (n=77); cool season, November to April (n=118)] using repeated measures analysis and comparison of least squares means at different time points relative to calving. Rumination was consistently reduced on the day of calving in both healthy and sick cows in both the hot and cool seasons. Only hot-season calvings had shorter average daily RT prepartum and postpartum in cows affected by severe negative energy balance and subclinical ketosis. Dystocia during the hot season was associated with shorter daily RT prepartum; for cool-season calvings, cows with dystocia had reduced RT postpartum. We also observed reduced RT in cows with ketosis prepartum and postpartum in both the hot and cool seasons. Daily RT was reduced postpartum in cows with hypocalcemia and mastitis that calved during the cool season, and it was shorter in cows with metritis in both the hot and cool seasons. Our results indicated that

  13. Response of wild mammals to seasonal shrinking-and-expansion of habitats due to flooding regime of the Pantanal, Brazil

    Directory of Open Access Journals (Sweden)

    S. B. Mamede

    Full Text Available The Pantanal is a large savanna wetland (138,183 km² in Brazil, important for its wildlife, fed by tributaries of the upper Paraguay River, center of South America (Brazil, touching Bolivia and Paraguay. Uplands are plateaus (250-1,200 m high, 215,000 km² in Brazil and flatland is the Pantanal (80-150 m high, 147,574 km² in Brazil. Rivers are slow moving when they meet the flatland (slope 0.3-0.5 m/km east-west; 0.03-0.15 m/km north-south, periodically overflowing their banks, creating a complex seasonal habitat range. Recurrent shallow flooding occupies 80% of the Pantanal; during the dry season flooded areas dry up. Fluctuating water levels, nutrients and wildlife form a dynamic ecosystem. A flooding regime forms distinct sub-regions within the Pantanal. A mammal survey was carried out in the sub-region of the Rio Negro from April, 2003 through March, 2004 to study the diversity and abundance of terrestrial mammals during the dry and flooding seasons. A total of 36 species were observed in the field. The capybara Hydrochaeris hydrochaeris was the most frequent species, followed by the crab-eating-fox Cerdocyon thous and the marsh deer Blastocerus dichotomus. The highest abundance of species was observed during the dry season (August and September, when there is a considerable expansion of terrestrial habitats, mainly seasonally flooded grassland. Animal abundance (in terms of observed individual frequencies varied during the dry and wet seasons and the seasonally flooded grassland was the most utilized habitat by mammals in the dry season.

  14. Seasonal distribution and abundance of Ohio River fishes at the J.M. Stuart Electric Generating Station

    International Nuclear Information System (INIS)

    Yoder, C.O.; Gammon, J.R.

    1976-01-01

    Distributions of Ohio River fishes were studied in the vicinity of a 2400-Mw coal-fired electric generating plant. Three thermally elevated zones, two ambient river zones, and a backwater zone were sampled intensively from June 1974 through February 1975 following the completion of all four units of the power plant. Less intensive collections were made preceding and during construction from 1970 to 1973. Overall variations in water temperature in 1974 to 1975 ranged from 6 to 40 0 C in the heated zones, 4 to 30 0 C in the ambient river zones, and 5 to 27 0 C in the backwater zone. Seasonal and spatial differences in abundance, diversity, and faunal associations were largely influenced by temperature. Notable changes in species populations from 1970 to 1975 were observed which were attributed to power-plant operation. Although seasonal definitions in terms of summer, fall, and winter were generally used, they were of very limited value, as demonstrated by annual fluctuations in community parameters. Apparently near-freezing temperatures in the ambient river zones, as well as high summer temperatures in the effluent canal, limit the time fish can spend in these areas and force them to seek more hospitable temperatures. This suggests that there are critical winter as well as summer months, with spring/fall transitional periods in between in the vicinity of thermal effluents

  15. The community structure and seasonal dynamics of plankton in Bange Lake, northern Tibet, China

    Science.gov (United States)

    Zhao, Wen; Zhao, Yuanyi; Wang, Qiaohan; Zheng, Mianping; Wei, Jie; Wang, Shan

    2016-11-01

    The seasonal variations in biomass, abundance, and species composition of plankton in relation to hydrography were studied in the saline Bange Lake, northern Tibet, China. Sampling was carried out between one to three times per month from May 2001 to July 2002. Salinity ranged from 14 to 146. The air and water temperature exhibited a clear seasonal pattern, and mean annual temperatures were approximately 4.8°C and 7.3°C, respectively. The lowest water temperature occurred in winter from December to March at -2°C and the highest in June and July at 17.7°C. Forty-one phytoplankton taxa, 21 zooplankton, and 5 benthic or facultative zooplankton were identified. The predominant phytoplankton species were Gloeothece linearis, Oscillatoria tenuis, Gloeocapsa punctata, Ctenocladus circinnatus, Dunaliella salina, and Spirulina major. The predominant zooplankton species included Holophrya actra, Brachionus plicatilis, Daphniopsis tibetana, Cletocamptus dertersi, and Arctodiaptomus salinus. The mean annual total phytoplankton density and biomass for the entire lake were 4.52×107 cells/L and 1.60 mg/L, respectively. The annual mean zooplankton abundance was 52, 162, 322, and 57, 144 ind./L, in the three sublakes. The annual mean total zooplankton biomass in Lakes 1-3 was 1.23, 9.98, and 2.13 mg/L, respectively. The annual mean tychoplankton abundances in Bg1, 2, and 3 were 47, 67, and 654 ind./L. The annual mean tychoplankton biomass was 2.36, 0.16, and 2.03 mg/L, respectively. The zooplankton biomass (including tychoplankton) in the lake was 9.11 mg/L. The total number of plankton species in the salt lake was significantly negatively correlated with salinity.

  16. High prevalence of cestodes in Artemia spp. throughout the annual cycle: relationship with abundance of avian final hosts

    Science.gov (United States)

    Sánchez, Marta I.; Nikolov, Pavel N.; GEorgieva, Darina D.; Georgiev, Boyko B.; Vasileva, Gergana P.; Pankov, Plamen; Paracuellos, Mariano; Lafferty, Kevin D.; Green, Andy J.

    2013-01-01

    Brine shrimp, Artemia spp., act as intermediate hosts for a range of cestode species that use waterbirds as their final hosts. These parasites can have marked influences on shrimp behavior and fecundity, generating the potential for cascading effects in hypersaline food webs. We present the first comprehensive study of the temporal dynamics of cestode parasites in natural populations of brine shrimp throughout the annual cycle. Over a 12-month period, clonal Artemia parthenogenetica were sampled in the Odiel marshes in Huelva, and the sexual Artemia salina was sampled in the Salinas de Cerrillos in Almería. Throughout the year, 4–45 % of A. parthenogenetica were infected with cestodes (mean species richness = 0.26), compared to 27–72 % of A. salina (mean species richness = 0.64). Ten cestode species were recorded. Male and female A. salina showed similar levels of parasitism. The most prevalent and abundant cestodes were those infecting the most abundant final hosts, especially the Greater Flamingo Phoenicopterus ruber. In particular, the flamingo parasite Flamingolepis liguloides had a prevalence of up to 43 % in A. parthenogenetica and 63.5 % in A. salina in a given month. Although there was strong seasonal variation in prevalence, abundance, and intensity of cestode infections, seasonal changes in bird counts were weak predictors of the dynamics of cestode infections. However, infection levels of Confluaria podicipina in A. parthenogenetica were positively correlated with the number of their black-necked grebe Podiceps nigricollis hosts. Similarly, infection levels of Anomotaenia tringae and Anomotaenia microphallos in A. salina were correlated with the number of shorebird hosts present the month before. Correlated seasonal transmission structured the cestode community, leading to more multiple infections than expected by chance.

  17. Seasonal Blowfly Distribution and Abundance in Fragmented Landscapes. Is It Useful in Forensic Inference about Where a Corpse Has Been Decaying?

    Science.gov (United States)

    Zabala, Jabi; Díaz, Beatriz; Saloña-Bordas, Marta I.

    2014-01-01

    Blowflies are insects of forensic interest as they may indicate characteristics of the environment where a body has been laying prior to the discovery. In order to estimate changes in community related to landscape and to assess if blowfly species can be used as indicators of the landscape where a corpse has been decaying, we studied the blowfly community and how it is affected by landscape in a 7,000 km2 region during a whole year. Using baited traps deployed monthly we collected 28,507 individuals of 10 calliphorid species, 7 of them well represented and distributed in the study area. Multiple Analysis of Variance found changes in abundance between seasons in the 7 analyzed species, and changes related to land use in 4 of them (Calliphora vomitoria, Lucilia ampullacea, L. caesar and L. illustris). Generalised Linear Model analyses of abundance of these species compared with landscape descriptors at different scales found only a clear significant relationship between summer abundance of C. vomitoria and distance to urban areas and degree of urbanisation. This relationship explained more deviance when considering the landscape composition at larger geographical scales (up to 2,500 m around sampling site). For the other species, no clear relationship between land uses and abundance was found, and therefore observed changes in their abundance patterns could be the result of other variables, probably small changes in temperature. Our results suggest that blowfly community composition cannot be used to infer in what kind of landscape a corpse has decayed, at least in highly fragmented habitats, the only exception being the summer abundance of C. vomitoria. PMID:24918607

  18. Seasonal dynamics of the shoreline vegetation in the Zapatosa floodplain lake complex, Colombia

    Directory of Open Access Journals (Sweden)

    Udo Schmidt-Mumm

    2014-09-01

    Full Text Available Floodplain lakes and associated wetlands in tropical dry climates are controlled by pronounced and severe seasonal hydrologic fluctuations. We examined the plant community response to a bimodal flooding pattern in the Zapatosa Floodplain Lake Complex (ZFLC, Northern Colombia. We measured floristic and quantitative change in four sampling periods emphasizing seasonal differences in plant abundance and life-form structure. Of 79 species identified in the lake complex, 52 were used to characterize eight community types via classification and ordination procedures. Results showed that community structure does not change significantly during the flooding/receding stages. But maximum drawdown phase significantly disrupts the aquatic community structure and the exposed shorelines become colonized by ruderal terrestrial plants. Early rainfalls at the beginning of the wet season are emphasized as an important feature of plant regeneration and community development. The general strategy of the ZFLC vegetation can be framed into the flood pulse concept of river-floodplain systems. Thus, plant communities are mainly responding to disturbances and destruction events imposed by extreme water level fluctuations. Rev. Biol. Trop. 62 (3: 1073-1097. Epub 2014 September 01.

  19. Land use determinants of small mammals abundance and ...

    African Journals Online (AJOL)

    The objective of this study was to determine the relationship between land use types and practices and small mammal abundance and distribution. A field survey was used to collect data in three landscapes differing in plague incidences. Data collection was done both in the wet season (April-June 2012) and dry season ...

  20. Seasonal variation in the prevalence of sand flies infected with Leishmania donovani.

    Science.gov (United States)

    Tiwary, Puja; Kumar, Dinesh; Mishra, Mukesh; Singh, Rudra Pratap; Rai, Madhukar; Sundar, Shyam

    2013-01-01

    Visceral Leishmaniasis (VL) is a life threatening neglected infectious disease in the Indian subcontinent, transmitted by the bite of female sand flies. Estimation of the infectivity in the vector population, collected in different seasons, may be useful to better understanding the transmission dynamics of VL as well as to plan vector control measures. We collected sand flies from highly endemic regions of Bihar state, India for one year over three seasons. The species of the sand flies were confirmed by species-specific PCR-RFLP. Leishmania donovani infection was investigated in 1397 female Phlebotomus argentipes using PCR, targeting the Leishmania specific minicircle of the kDNA region. Further, the parasitic load in the infected sand flies was measured using quantitative PCR. Though sand flies were most abundant in the rainy season, the highest rate of infection was detected in the winter season with 2.84% sand flies infected followed by the summer and rainy seasons respectively. This study can help in vector elimination programmes and to reduce disease transmission.

  1. Periodic matrix models for seasonal dynamics of structured populations with application to a seabird population.

    Science.gov (United States)

    Cushing, J M; Henson, Shandelle M

    2018-02-03

    For structured populations with an annual breeding season, life-stage interactions and behavioral tactics may occur on a faster time scale than that of population dynamics. Motivated by recent field studies of the effect of rising sea surface temperature (SST) on within-breeding-season behaviors in colonial seabirds, we formulate and analyze a general class of discrete-time matrix models designed to account for changes in behavioral tactics within the breeding season and their dynamic consequences at the population level across breeding seasons. As a specific example, we focus on egg cannibalism and the daily reproductive synchrony observed in seabirds. Using the model, we investigate circumstances under which these life history tactics can be beneficial or non-beneficial at the population level in light of the expected continued rise in SST. Using bifurcation theoretic techniques, we study the nature of non-extinction, seasonal cycles as a function of environmental resource availability as they are created upon destabilization of the extinction state. Of particular interest are backward bifurcations in that they typically create strong Allee effects in population models which, in turn, lead to the benefit of possible (initial condition dependent) survival in adverse environments. We find that positive density effects (component Allee effects) due to increased adult survival from cannibalism and the propensity of females to synchronize daily egg laying can produce a strong Allee effect due to a backward bifurcation.

  2. Timing of breeding and reproductive performance in murres and kittiwakes reflect mismatched seasonal prey dynamics

    Science.gov (United States)

    Shultz, M.T.; Piatt, John F.; Harding, A.M.A.; Kettle, Arthur B.; van Pelt, Thomas I.

    2009-01-01

    Seabirds are thought to time breeding to match the seasonal peak of food availability with peak chick energetic demands, but warming ocean temperatures have altered the timing of spring events, creating the potential for mismatches. The resilience of seabird populations to climate change depends on their ability to anticipate changes in the timing and magnitude of peak food availability and 'fine-tune' efforts to match ('Anticipation Hypothesis'). The degree that inter-annual variation in seabird timing of breeding and reproductive performance represents anticipated food availability versus energetic constraints ('Constraint Hypothesis') is poorly understood. We examined the relative merits of the Constraint and Anticipation Hypotheses by testing 2 predictions of the Constraint Hypothesis: (1) seabird timing of breeding is related to food availability prior to egg laying rather than the date of peak food availability, (2) initial reproductive output (e.g. laying success, clutch size) is related to pre-lay food availability rather than anticipated chick-rearing food availability. We analyzed breeding biology data of common murres Uria aalge and black-legged kittiwakes Rissa tridactyla and 2 proxies of the seasonal dynamics of their food availability (near-shore forage fish abundance and sea-surface temperature) at 2 colonies in Lower Cook Inlet, Alaska, USA, from 1996 to 1999. Our results support the Constraint Hypothesis: (1) for both species, egg laying was later in years with warmer sea-surface temperature and lower food availability prior to egg laying, but was not related to the date of peak food availability, (2) pre-egg laying food availability explained variation in kittiwake laying success and clutch size. Murre reproductive success was best explained by food availability during chick rearing. ?? 2009 Inter-Research.

  3. Effects of reforestation on ammonia-oxidizing microbial community composition and abundance in subtropical acidic forest soils.

    Science.gov (United States)

    Wu, Ruo-Nan; Meng, Han; Wang, Yong-Feng; Gu, Ji-Dong

    2018-06-01

    Forest ecosystems have great ecological values in mitigation of climate change and protection of biodiversity of flora and fauna; re-forestry is commonly used to enhance the sequestration of atmospheric CO 2 into forest storage biomass. Therefore, seasonal and spatial dynamics of the major microbial players in nitrification, ammonia-oxidizing archaea (AOA) and bacteria (AOB), in acidic soils of young and matured revegetated forests were investigated to elucidate the changes of microbial communities during forest restoration, and compared to delineate the patterns of community shifts under the influences of environmental factors. AOA were more abundant than AOB in both young and matured revegetated forest soils in both summer and winter seasons. In summer, however, the abundance of amoA-AOA decreased remarkably (p < 0.01), ranging from 1.90 (± 0.07) × 10 8 copies per gram dry soil in matured forest to 5.04 (± 0.43) × 10 8 copies per gram dry soil in young forest, and amoA-AOB was below detection limits to obtain any meaningful values. Moreover, exchangeable Al 3+ and organic matter were found to regulate the physiologically functional nitrifiers, especially AOA abundance in acidic forest soils. AOB community in winter showed stronger correlation with the restoration status of revegetated forests and AOA community dominated by Nitrosotalea devanaterra, in contrast, was more sensitive to the seasonal and spatial variations of environmental factors. These results enrich the current knowledge of nitrification during re-forestry and provide valuable information to developmental status of revegetated forests for management through microbial analysis.

  4. Seasonal module dynamics of Turbinaria triquetra (Fucales, Phaeophyceae) in the southern Red Sea

    NARCIS (Netherlands)

    Ateweberhan, Mebrahtu; Bruggemann, J. Henrich; Breeman, Anneke M.

    2006-01-01

    Module dynamics in the fucoid alga Turbinaria triquetra (J. Agardh) Kutzing were studied on a shallow reef flat in the southern Red Sea. Seasonal patterns in thallus density and size were determined, and the initiation, growth, reproduction, and shedding of modules were studied using a tagging

  5. Seasonal abundance and biology of sporophagous thrips and notes on other thrips (Insecta, Thysanoptera) on the Mediterranean oak, Quercus rotundifolia L. in Navarra (N Spain)

    OpenAIRE

    Goldarazena, A.; Mound, L. A.

    1999-01-01

    This paperrecords the seasonal abundance of four species of sporophagous thrips collected on the Mediterranean oak, Quercus rotundifolia L., in the Mediterranean area of Navarra (N Spain). The life cycles of Cornpsothrips albosignatus (Reuter), Priesneriella clavicornis (Knechtel); Megalothrips bonannii Uzel and Cryptohrips nigripes (Reuter) are reported, and notes given about habitat specificity and wing development. Notes about host specific Terebrantia thrips of the Mediterranean oak are a...

  6. The Impact of High-Turbidity Water's Seasonal and Decadal Variations on Offshore Phytoplankton and Nutrients Dynamics around The Changjiang Estuary

    Science.gov (United States)

    Ge, J.; Torres, R.; Chen, C.; Bellerby, R. G. J.

    2017-12-01

    The Changjiang Estuary is characterized as strong river discharge into the inner shelf of the East China Sea with abundant sediment load, producing significant high-turbidity water coverage from river mouth to deep region. The growth of offshore phytoplankton is dynamically controlled by river flushed low-salinity and high-turbidity water, and salter water from inner shelf of East China Sea. During last decade, the sediment and nutrients from the Changjiang River has significantly changed, which lead to the variation of offshore phytoplankton dynamics. The variations of sediment, nutrients, and their influenced phytoplankton has been simulated through a comprehensive modeling system, which integrated a multi-scale current-wave-sediment FVCOM model and generic marine biogeochemistry and ecosystem ERSEM model through The Framework for Aquatic Biogeochemical Models (FABM). This model system has successfully revealed the seasonal and decadal variations of sediment, nutrients transport around the inner shelf of the East China Sea. The spring and autumn peaks of phytoplankton growth were correctly captured by simulation. The modeling results, as well as MODIS and GOCI remote sensing, shows a strong sediment decreasing from northern to southern region, which creates different patterns of Chlorophyll-a distribution and seasonal variations. These results indicate the high-turbidity water in northern region strongly influenced the light attenuation in the water column and limits the phytoplankton growth in this relatively higher-nutrient area, especially in the wintertime. The relatively low-turbidity southern region has significant productivity of phytoplankton, even during low-temperature winter. The phytoplankton growth increased in the northern region from 2005 to 2010, with the increase of the nutrient load during this period. Then it became a decreasing trend after 2010.

  7. High abundance androgen receptor in goldfish brain: characteristics and seasonal changes

    International Nuclear Information System (INIS)

    Pasmanik, M.; Callard, G.V.

    1988-01-01

    Testosterone (T) exerts its actions in brain directly via androgen receptors or, after aromatization to estradiol, via estrogen receptors. Brain aromatase activity in teleost fish is 100-1000 times greater than in mammals and would be expected to significantly reduce the quantity of androgen available for receptor binding. Experiments were carried out on the goldfish Carassius auratus to determine if androgen receptors are present in teleost brain and whether their physicochemical properties reflect elevated aromatase. Cytosolic and nuclear extracts were assayed with the use of [ 3 H]T and charcoal, Sephadex LH-20, or DNA-cellulose chromatography to separate bound and free steroids. Binding activity was saturable and had an equally high affinity for T and 5 alpha-dihydrotestosterone. Although mibolerone was a relatively weak competitor, the putative teleost androgen 11-ketotestosterone, methyltrienolone (R1881), estradiol, progesterone, and cortisol were poor ligands. Characteristics that distinguish this receptor from a steroid-binding protein in goldfish serum are the presence of binding activity in both nuclear and cytosolic extracts, a low rate of ligand-receptor dissociation, electrophoretic mobility, sedimentation properties in low vs. high salt, and tissue distribution. DNA cellulose-adhering and nonadhering forms were detected, but these did not differ in other variables measured. Although goldfish androgen receptors resembled those of mammals in all important physicochemical characteristics, they were unusually abundant compared to levels in rat brain, but comparable to levels in prostate and other male sex hormone target organs. Moreover, there were seasonal variations in total receptors, with a peak at spawning (April) 4- to 5-fold higher than values in reproductively inactive fish

  8. Carbon dynamics in corn-soybean sequences as estimated from natural carbon-13 abundance

    International Nuclear Information System (INIS)

    Huggins, D.R.; Clapp, C.E.; Allmaras, R.R.; Lamb, J.A.; Layese, M.F.

    1998-01-01

    Carbon flow in terrestrial ecosystems regulates partitioning between soil organic C (SOC) and atmospheric CO2. Our objectives were to assess SOC dynamics using natural 13C abundance in corn (Zea mays L., a C4 species)-soybean [Glycine max (L.) Merr., a C3 species] sequences. Fifteen treatments of continuous corn, continuous soybean, various sequences of corn and soybean, and fallow were initiated in 1981 at Lamberton, MN, on a Webster clay loam (fine-loamy, mixed, mesic Typic Haplaquoll). In 1991, soil and aboveground shoot samples from all treatments were analyzed for total organic C and delta 13C. Carbon inputs, delta 13C, and SOC were integrated into a two-pool model to evaluate C dynamics of corn and soybean. Total SOC was similar across all treatments after 10 yr; however, differences in soil delta 13C occurred between continuous corn (delta 13C = -17.2 per thous and) and continuous soybean (delta 13C = -18.2 per thousand). Modeled C dynamics showed SOC decay rates of 0.011 yr-1 for C4-derived C and 0.007 yr-1 for C3-derived C, and humification rates of 0.16 yr-1 for corn and 0.11 yr-1 for soybean. Decay and humification rates were slightly lower than those found in other Corn Belt studies. Levels of SOC were predicted to decline an additional 7 to 18% with current C inputs from either corn or soybean, respectively. Annual C additions required for SOC maintenance averaged 5.6 Mg C ha-1, 1.4 to 2.1 times greater than previously reported estimates. Controlled variation in natural 13C abundance in corn-soybean rotations during a 10-yr period adequately traced C dynamics

  9. Seasonal timing of first rain storms affects rare plant population dynamics

    Science.gov (United States)

    Levine, J.M.; McEachern, A.K.; Cowan, C.

    2011-01-01

    A major challenge in forecasting the ecological consequences of climate change is understanding the relative importance of changes to mean conditions vs. changes to discrete climatic events, such as storms, frosts, or droughts. Here we show that the first major storm of the growing season strongly influences the population dynamics of three rare and endangered annual plant species in a coastal California (USA) ecosystem. In a field experiment we used moisture barriers and water addition to manipulate the timing and temperature associated with first major rains of the season. The three focal species showed two- to fivefold variation in per capita population growth rates between the different storm treatments, comparable to variation found in a prior experiment imposing eightfold differences in season-long precipitation. Variation in germination was a major demographic driver of how two of three species responded to the first rains. For one of these species, the timing of the storm was the most critical determinant of its germination, while the other showed enhanced germination with colder storm temperatures. The role of temperature was further supported by laboratory trials showing enhanced germination in cooler treatments. Our work suggests that, because of species-specific cues for demographic transitions such as germination, changes to discrete climate events may be as, if not more, important than changes to season-long variables.

  10. Community structure and seasonal dynamics of diatom biofilms and associated grazers in intertidal mudflats

    NARCIS (Netherlands)

    Sahan, E.; Sabbe, K.; Creach, V.; Hernandez-Raquet, G.; Vyverman, W.; Stal, L.J.; Muyzer, G.

    2007-01-01

    The composition and seasonal dynamics of biofilm-associated eukaryotic communities were analysed at the metre and kilometre scale along a salinity gradient in the Westerschelde estuary (The Netherlands), using microscopy and a genetic fingerprinting technique (PCR-DGGE). Microphytobenthic biomass,

  11. Seasonal variation of macromedusae (Cnidaria at North Bay, Florianópolis, southern Brazil

    Directory of Open Access Journals (Sweden)

    Miodeli Nogueira Júnior

    2010-06-01

    Full Text Available Seasonal variation of large medusae abundance and biomass was studied in the North Bay, Santa Catarina, southern Brazil (27°30'S, 48° 32'W, from February to December 2005. Collecting was conducted seasonally with the help of fishing bottom trawl in 30-minute sections (12 in summer, 18 in each of the remaining seasons in six stations, totaling 66 samples. Eight species were found: the hydrozoans Aequorea sp., Olindias sambaquiensis Müller, 1861, and Rhacostoma atlantica L. Agassiz, 1850; the cubozoans Chiropsalmus quadrumanus (Müller, 1859 and Tamoya haplonema Müller, 1859, and the scyphozoans Aurelia sp., Chrysaora lactea Eschscholtz, 1829 and Lychnorhiza lucerna Haeckel, 1880. Capture rates were low, up to 38 indiv. ha-1, and only ~47% of the samples were positive for jellyfish, comprising 206 individuals. Medusae abundance and species richness clearly changed from one season to another, but did not vary between the sites. Higher species richness (7 out of 8 and greater abundances were recorded during the fall (~60% and 72% of all medusae individuals and biomass respectively. Specific frequency of capture varied from 1.5 to 29% and C. lactea was the only species found in more than 25% of the samples. The three most common species dominated in different periods of the year: C. lactea during fall (78% of individuals and 60% of biomass, R. atlantica during winter (90% of individuals and 17% of biomass, and O. sambaquiensis in spring (78% of individuals and 40% of biomass. Only two individuals were caught during summer, one C. lactea and one R. atlantica. The results offer a general picture of the distribution of the macromedusae in the North Bay, but a continuous monitoring is desirable for a more detailed knowledge on the jellyfish dynamics in the Brazilian coastal waters.

  12. Prickly business: abundance of sea urchins on breakwaters and coral reefs in Dubai.

    Science.gov (United States)

    Bauman, Andrew G; Dunshea, Glenn; Feary, David A; Hoey, Andrew S

    2016-04-30

    Echinometra mathaei is a common echinoid on tropical reefs and where abundant plays an important role in the control of algal communities. Despite high prevalence of E. mathaei on southern Persian/Arabian Gulf reefs, their abundance and distribution is poorly known. Spatial and temporal patterns in population abundance were examined at 12 sites between breakwater and natural reef habitats in Dubai (UAE) every 3 months from 2008 to 2010. Within the breakwater habitat, densities were greatest at shallow wave-exposed sites, and reduced with both decreasing wave-exposure and increasing depth. Interestingly, E. mathaei were significantly more abundant on exposed breakwaters than natural reef sites, presumably due to differences in habitat structure and benthic cover. Population abundances differed seasonally, with peak abundances during summer (July-September) and lower abundances in winter (December-February). Seasonal fluctuations are likely the result of peak annual recruitment pulses coupled with increased fish predation from summer to winter. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Fish larval composition, abundance and seasonality in a southern ...

    African Journals Online (AJOL)

    abundance was relatively low (38 larvae 100 m-3 ), possibly as a result of the extremely low phytoplankton productivity and poor ... hoveelheid visplankton is laag (38 larwes 100 m-3), heelwaarskynlik as gevolg van die baie lae fitoplankton- opbrengs en lae ..... depressed ichthyoplankton food resources. According to.

  14. Dynamics in Microbial Composition and Functionality over a Season in Two Contrasting Estuarine Systems

    DEFF Research Database (Denmark)

    Traving, Sachia; Bentzon-Tilia, Mikkel; Mantikci, Mustafa

    2015-01-01

    In aquatic microbial ecology it remains unclear how bacterial community composition and dynamics are coupled to functionality, and whether this putative coupling varies over the season. In this study we address the questions if bacterial community composition can be linked to community function, ...

  15. Seasonal differences in leaf-level physiology give lianas a competitive advantage over trees in a tropical seasonal forest

    NARCIS (Netherlands)

    Cai, Z.Q.; Schnitzer, S.A.; Bongers, F.

    2009-01-01

    Lianas are an important component of most tropical forests, where they vary in abundance from high in seasonal forests to low in aseasonal forests. We tested the hypothesis that the physiological ability of lianas to fix carbon (and thus grow) during seasonal drought may confer a distinct advantage

  16. Effect of tillage and planting date on seasonal abundance and diversity of predacious ground beetles in cotton.

    Science.gov (United States)

    Shrestha, R B; Parajulee, M N

    2010-01-01

    A 2-year field study was conducted in the southern High Plains region of Texas to evaluate the effect of tillage system and cotton planting date window on seasonal abundance and activity patterns of predacious ground beetles. The experiment was deployed in a split-plot randomized block design with tillage as the main-plot factor and planting date as the subplot factor. There were two levels for each factor. The two tillage systems were conservation tillage (30% or more of the soil surface is covered with crop residue) and conventional tillage. The two cotton planting date window treatments were early May (normal planting) and early June (late planting). Five prevailing predacious ground beetles, Cicindela sexguttata F., Calosoma scrutator Drees, Pasimachus spp., Pterostichus spp., and Megacephala Carolina L. (Coleoptera: Carabidae), were monitored using pitfall traps at 2-week intervals from June 2002 to October 2003. The highest total number of ground beetles (6/trap) was observed on 9 July 2003. Cicindela sexguttata was the dominant ground dwelling predacious beetle among the five species. A significant difference between the two tillage systems was observed in the abundances of Pterostichus spp. and C. sexguttata. In 2002. significantly more Pterostichus spp. were recorded from conventional plots (0.27/trap) than were recorded from conservation tillage plots (0.05/trap). Significantly more C. sexguttata were recorded in 2003 from conservation plots (3.77/trap) than were recorded from conventional tillage plots (1.04/trap). There was a significant interaction between year and tillage treatments. However, there was no significant difference in the abundances of M. Carolina and Pasimachus spp. between the two tillage practices in either of the two years. M. Carolina numbers were significantly higher in late-planted cotton compared with those observed in normal-planted cotton. However, planting date window had no significant influence on the activity patterns of the

  17. Infection Paradox: High Abundance but Low Impact of Freshwater Benthic Viruses

    Science.gov (United States)

    Filippini, Manuela; Buesing, Nanna; Bettarel, Yvan; Sime-Ngando, Télesphore; Gessner, Mark O.

    2006-01-01

    The discovery of an abundant and diverse virus community in oceans and lakes has profoundly reshaped ideas about global carbon and nutrient fluxes, food web dynamics, and maintenance of microbial biodiversity. These roles are exerted through massive viral impact on the population dynamics of heterotrophic bacterioplankton and primary producers. We took advantage of a shallow wetland system with contrasting microhabitats in close proximity to demonstrate that in marked contrast to pelagic systems, viral infection, determined directly by transmission electron microscopy, and consequently mortality of prokaryotes were surprisingly low in benthic habitats in all seasons. This was true even though free viruses were abundant throughout the year and bacterial infection and mortality rates were high in surrounding water. The habitats in which we found this pattern include sediment, decomposing plant litter, and biofilms on aquatic vegetation. Overall, we detected viruses in only 4 of a total of ∼15,000 bacterial cells inspected in these three habitats; for comparison, nearly 300 of ∼5,000 cells suspended in the water column were infected. The strikingly low incidence of impact of phages in the benthos may have important implications, since a major portion of microbial biodiversity and global carbon and nutrient turnover are associated with surfaces. Therefore, if failure to infect benthic bacteria is a widespread phenomenon, then the global role of viruses in controlling microbial diversity, food web dynamics, and biogeochemical cycles would be greatly diminished compared to predictions based on data from planktonic environments. PMID:16820485

  18. Seasonal dynamics of structure and functional activity of ectomycorrhizal roots of the Siberian fir

    Directory of Open Access Journals (Sweden)

    T. A. Sizonenko

    2017-12-01

    Full Text Available The aim of our work was to study seasonal dynamics of the Siberian fir Abies sibirica Ledeb. ectomycorrhizal morpho-anatomical structure, respiration rate and fluorescence. The study was carried out in the bilberry-sphagnum spruce forest in the middle taiga of the Komi Republic, Russia. The morpho-anatomical structure and fluorescence parameters were studied by light and luminescence microscopy. Thin root respiration was studied in intact fine roots in the field using an infrared gas analyzer. 12 subtypes of fungal mantels were revealed in ectomycorrhizal fir roots; their amount and composition demonstrated seasonal dynamic changes. At the beginning vegetation stage, the diversity and proportion of pseudoparenchymatous and double covers were maximal. Plant component of ectomycorrhizae that includes cortical parenchyma and stele had high activity of fluorescence during the entire vegetation period. The dynamics of staining of fungal component (fungal mantel and Hartig net was more contrasting. The highest fluorescence intensity of cortical parenchyma was found in ectomycorrhizae with maximal fungal mantel thickness. High proportion of tannin cells in cortical parenchyma was related with low intensity of fungal mantel and Hartig net fluorescence. During vegetation season, maximal amount of intensively strained ectomycorrhizal elements occurred in July and unstrained – in June and August. Relation between fine roots respiration and an increase of brightly strained ectomycorrhizal structural elements in fir roots was not statistically significant. Root CO2-emission was lower in May and September in comparison with summer months. For respiration rate of fir fine roots we found its strong positive correlation with the litter temperature.

  19. Seasonal differences in leaf-level physiology give lianas a competitive advantage over trees in a tropical seasonal forest.

    Science.gov (United States)

    Cai, Zhi-Quan; Schnitzer, Stefan A; Bongers, Frans

    2009-08-01

    Lianas are an important component of most tropical forests, where they vary in abundance from high in seasonal forests to low in seasonal forests. We tested the hypothesis that the physiological ability of lianas to fix carbon (and thus grow) during seasonal drought may confer a distinct advantage in seasonal tropical forests, which may explain pan-tropical liana distributions. We compared a range of leaf-level physiological attributes of 18 co-occurring liana and 16 tree species during the wet and dry seasons in a tropical seasonal forest in Xishuangbanna, China. We found that, during the wet season, lianas had significantly higher CO(2) assimilation per unit mass (A(mass)), nitrogen concentration (N(mass)), and delta(13)C values, and lower leaf mass per unit area (LMA) than trees, indicating that lianas have higher assimilation rates per unit leaf mass and higher integrated water-use efficiency (WUE), but lower leaf structural investments. Seasonal variation in CO(2) assimilation per unit area (A(area)), phosphorus concentration per unit mass (P(mass)), and photosynthetic N-use efficiency (PNUE), however, was significantly lower in lianas than in trees. For instance, mean tree A(area) decreased by 30.1% from wet to dry season, compared with only 12.8% for lianas. In contrast, from the wet to dry season mean liana delta(13)C increased four times more than tree delta(13)C, with no reduction in PNUE, whereas trees had a significant reduction in PNUE. Lianas had higher A(mass) than trees throughout the year, regardless of season. Collectively, our findings indicate that lianas fix more carbon and use water and nitrogen more efficiently than trees, particularly during seasonal drought, which may confer a competitive advantage to lianas during the dry season, and thus may explain their high relative abundance in seasonal tropical forests.

  20. The taxonomy and seasonal population dynamics of some Magela Creek flood plain microcrustaceans (Cladocera and copedoda)

    International Nuclear Information System (INIS)

    Julli, M.E.

    1986-01-01

    Six Magela Creek floodplain billabongs were sampled between September 1981 and January 1983 to determine the seasonal population dynamics of littoral and limnetic microcrustaceans. Thirty-seven cladoceran and four copepod species were identified amongst littoral weedbeds and several unidentified harpacticoid copepods and ostracods were also found. By comparison only 6 cladoceran and 4 copepod species were found in limnetic areas. Littoral species generally attained their highest densities during the mid-Wet to Early-dry seasons. The number of open water species present in samples generally increased with the progression of the Dry season. Towards the end of the Dry season, a simplification of the limnetic species assemblage occurred in some billabongs, perhaps in response to adverse changes in water quality

  1. Dynamical 3-Space Predicts Hotter Early Universe: Resolves CMB-BBN 7-Li and 4-He Abundance Anomalies

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2010-01-01

    Full Text Available The observed abundances of 7-Li and 4-He are significantly inconsistent with the predictions from Big Bang Nucleosynthesis (BBN when using the $Lambda$CDM cosmological model together with the value for $Omega_B h^2 = 0.0224pm0.0009$ from WMAP CMB fluctuations, with the value from BBN required to fit observed abundances being $0.009 < Omega_B h^2 < 0.013$. The dynamical 3-space theory is shown to predict a 20% hotter universe in the radiation-dominated epoch, which then results in a remarkable parameter-free agreement between the BBN and the WMAP value for $Omega_B h^2$. The dynamical 3-space also gives a parameter-free fit to the supernova redshift data, and predicts that the flawed $Lambda$CDM model would require $Omega_Lambda = 0.73$ and $Omega_M = 0.27$ to fit the 3-space dynamics Hubble expansion, and independently of the supernova data. These results amount to the discovery of new physics for the early universe that is matched by numerous other successful observational and experimental tests.

  2. Riqueza, abundância e sazonalidade de Sphingidae (Lepidoptera num fragmento de Mata Atlântica de Pernambuco, Brasil Species richness, abundance and seasonality of Sphingidae (Lepidoptera in a fragment of Atlantic Rainforest of Pernambuco, Brazil

    Directory of Open Access Journals (Sweden)

    José A. Duarte Júnior

    2005-09-01

    Full Text Available Na Mata Atlântica de Pernambuco, NE-Brasil (Reserva Biológica de Gurjaú, Cabo de Santo Agostinho foi realizado um levantamento de Sphingidae de dezembro de 2002 a novembro de 2003. Os esfingídeos foram coletados com luz de vapor de mercúrio durante duas noites consecutivas por mês, próximo ao novilúnio. Foram determinadas riqueza de espécies, abundância e sazonalidade. Oitenta e nove espécimes de 23 espécies em 13 gêneros foram registrados; 84% dos indivíduos foram machos. Muitas espécies foram raras e de 13 espécies foi coletado apenas um exemplar. Xylophanes loelia (Druce, 1878, X. libya (Druce, 1878, Hemeroplanes triptolemus (Cramer, 1779, Eumorpha anchemolus (Cramer, 1779, Manduca brasilensis (Jordan, 1911, M. hannibal (Cramer, 1779, Adhemarius gannascus (Stoll, 1790 e Protambulyx astygonus (Boisduval, [1875] foram registradas pela primeira vez no Nordeste do Brasil. A esfingofauna não mostrou nenhum padrão de sazonalidade, e riqueza e abundância de espécies de esfingídeos não se correlacionaram com precipitação mensal e temperatura.In the Atlantic Rainforest of Pernambuco, NE-Brazil (Reserva Biológica de Gurjaú, Cabo de Santo Agostinho a survey of Sphingidae was performed from December 2002 to November 2003. The hawkmoths were collected with vapor mercury light during two consecutive nights per months near new moon. Species richness, abundance and seasonality were determined. Eighty-nine specimens of 23 species in13 genera were recorded; 84% the individuals were males. Most species were rare and from 13 species only one exemplar was collected. Xylophanes loelia (Druce, 1878, X. libya (Druce, 1878, Hemeroplanes triptolemus (Cramer, 1779, Eumorpha anchemolus (Cramer, 1779, Manduca brasilensis (Jordan, 1911, M. hannibal (Cramer, 1779, Adhemarius gannascus (Stoll, 1790 e Protambulyx astygonus (Boisduval, [1875] were recorded for the first time in Northeastern Brazil. The sphingofauna showed no seasonal patterns and

  3. Seasonal abundance, biomass, diversity, and trophic structure of fish in a salt-marsh tidal creek affected by a coastal power plant

    International Nuclear Information System (INIS)

    Homer, M.

    1976-01-01

    Monthly measurements were made of the seasonal abundance, biomass, species diversity, and trophic composition of fish inhabiting the tidal creeks of salt marshes receiving thermal discharge near Crystal River, Fla. In the warm months (May through September 1974), mean abundance in the creek receiving thermal discharge was 0.46 individuals/m 2 and mean biomass was 2.2 g (preserved weight)/m 2 . In a control area, creek values in the warm months were 6.77 individuals/m 2 and 9.1 g (preserved weight)/m 2 , respectively. During the cold months (October 1974 through February 1975) there were 0.48 individuals/m 2 and 8.3 g (preserved weight)/m 2 in the discharge area and 0.58 individuals/m 2 and 7.4 g preserved weight/m 2 in the control area. In all months except May 1974 and February 1975, species diversity as species per 1000 individuals was higher in the control creek than in the discharge creek. No apparent differences in fish trophic structure were observed

  4. Fungi diversity in PM2. 5 and PM1 at the summit of Mt. Tai: abundance, size distribution, and seasonal variation

    Directory of Open Access Journals (Sweden)

    C. Xu

    2017-09-01

    Full Text Available Fungi are ubiquitous throughout the near-surface atmosphere, where they represent an important component of primary biological aerosol particles. This study combined internal transcribed spacer region sequencing and quantitative real-time polymerase chain reaction (qPCR to investigate the ambient fungi in fine (PM2. 5, 50 % cutoff aerodynamic diameter Da50 =  2.5 µm, geometric standard deviation of collection efficiency σg =  1.2 and submicron (PM1, Da50 =  1 µm, σg =  1.2 particles at the summit of Mt. Tai located in the North China Plain, China. Fungal abundance values were 9.4  ×  104 and 1.3  ×  105 copies m−3 in PM2. 5 and PM1, respectively. Most of the fungal sequences were from Ascomycota and Basidiomycota, which are known to actively discharge spores into the atmosphere. The fungal community showed a significant seasonal shift across different size fractions according to Metastats analysis and the Kruskal–Wallis rank sum test. The abundance of Glomerella and Zasmidium increased in larger particles in autumn, whereas Penicillium, Bullera, and Phaeosphaeria increased in smaller particles in winter. Environmental factors, namely Ca2+, humidity, and temperature, were found to be crucial for the seasonal variation in the fungal community. This study might serve as an important reference for fungal contribution to primary biological aerosol particles.

  5. Seasonal sediment dynamics shape temperate bedrock reef communities

    Science.gov (United States)

    Figurski, Jared D.; Freiwald, Jan; Lonhart, Steve I.; Storlazzi, Curt

    2016-01-01

    Mobilized seafloor sediment can impact benthic reef communities through burial, scour, and turbidity. These processes are ubiquitous in coastal oceans and, through their influence on the survival, fitness, and interactions of species, can alter the structure and function of benthic communities. In northern Monterey Bay, California, USA, as much as 30% of the seafloor is buried or exposed seasonally, making this an ideal location to test how subtidal temperate rocky reef communities vary in the presence and absence of chronic sediment-based disturbances. Designated dynamic plots were naturally inundated by sediment in summer (50 to 100% cover) and swept clean in winter, whereas designated stable plots remained free of sediment during our study. Multivariate analyses indicated significant differences in the structure of sessile and mobile communities between dynamic and stable reef habitats. For sessile species, community structure in disturbed plots was less variable in space and time than in stable plots due to the maintenance of an early successional state. In contrast, community structure of mobile species varied more in disturbed plots than in stable plots, reflecting how mobile species distribute in response to sediment dynamics. Some species were found only in these disturbed areas, suggesting that the spatial mosaic of disturbance could increase regional diversity. We discuss how the relative ability of species to tolerate disturbance at different life history stages and their ability to colonize habitat translate into community-level differences among habitats, and how this response varies between mobile and sessile communities.

  6. Mars atmospheric water vapor abundance: 1996-1997

    Science.gov (United States)

    Sprague, A. L.; Hunten, D. M.; Doose, L. R.; Hill, R. E.

    2003-05-01

    Measurements of martian atmospheric water vapor made throughout Ls = 18.0°-146.4° (October 3, 1996-July 12, 1997) show changes in Mars humidity on hourly, daily, and seasonal time scales. Because our observing program during the 1996-1997 Mars apparition did not include concomitant measurement of nearby CO 2 bands, high northern latitude data were corrected for dust and aerosol extinction assuming an optical depth of 0.8, consistent with ground-based and HST imaging of northern dust storms. All other measurements with airmass greater than 3.5 were corrected using a total optical depth of 0.5. Three dominant results from this data set are as follows: (1) pre- and post-opposition measurements made with the slit crossing many hours of local time on Mars' Earth-facing disk show a distinct diurnal pattern with highest abundances around and slightly after noon with low abundances in the late afternoon, (2) measurements of water vapor over the Mars Pathfinder landing site (Carl Sagan Memorial Station) on July 12, 1997, found 21 ppt μm in the spatial sector centered near 19° latitude, 36° longitude while abundances around the site varied from as low as 6 to as high as 28 ppt μm, and (3) water vapor abundance is patchy on hourly and daily time scales but follows the usual seasonal trends.

  7. Seasonal variation in nitrogen pools and 15N/13C natural abundances in different tissues of grassland plants

    Directory of Open Access Journals (Sweden)

    J. K. Schjoerring

    2012-05-01

    Full Text Available Seasonal changes in nitrogen (N pools, carbon (C content and natural abundance of 13C and 15N in different tissues of ryegrass plants were investigated in two intensively managed grassland fields in order to address their ammonia (NH3 exchange potential. Green leaves generally had the largest total N concentration followed by stems and inflorescences. Senescent leaves had the lowest N concentration, indicating N re-allocation. The seasonal pattern of the Γ value, i.e. the ratio between NH4+ and H+ concentrations, was similar for the various tissues of the ryegrass plants but the magnitude of Γ differed considerably among the different tissues. Green leaves and stems generally had substantially lower Γ values than senescent leaves and litter. Substantial peaks in Γ were observed during spring and summer in response to fertilization and grazing. These peaks were associated with high NH4+ rather than with low H+ concentrations. Peaks in Γ also appeared during the winter, coinciding with increasing δ15N values, indicating absorption of N derived from mineralization of soil organic matter. At the same time, δ13C values were declining, suggesting reduced photosynthesis and capacity for N assimilation. δ15N and δ13C values were more influenced by mean monthly temperature than by the accumulated monthly precipitation. In conclusion, ryegrass plants showed a clear seasonal pattern in N pools. Green leaves and stems of ryegrass plants generally seem to constitute a sink for NH3, while senescent leaves have a large potential for NH3 emission. However, management events such as fertilisation and grazing may create a high NH3 emission potential even in green plant parts. The obtained results provide input for future modelling of plant-atmosphere NH3 exchange.

  8. Timing and severity of immunizing diseases in rabbits is controlled by seasonal matching of host and pathogen dynamics.

    Science.gov (United States)

    Wells, Konstans; Brook, Barry W; Lacy, Robert C; Mutze, Greg J; Peacock, David E; Sinclair, Ron G; Schwensow, Nina; Cassey, Phillip; O'Hara, Robert B; Fordham, Damien A

    2015-02-06

    Infectious diseases can exert a strong influence on the dynamics of host populations, but it remains unclear why such disease-mediated control only occurs under particular environmental conditions. We used 16 years of detailed field data on invasive European rabbits (Oryctolagus cuniculus) in Australia, linked to individual-based stochastic models and Bayesian approximations, to test whether (i) mortality associated with rabbit haemorrhagic disease (RHD) is driven primarily by seasonal matches/mismatches between demographic rates and epidemiological dynamics and (ii) delayed infection (arising from insusceptibility and maternal antibodies in juveniles) are important factors in determining disease severity and local population persistence of rabbits. We found that both the timing of reproduction and exposure to viruses drove recurrent seasonal epidemics of RHD. Protection conferred by insusceptibility and maternal antibodies controlled seasonal disease outbreaks by delaying infection; this could have also allowed escape from disease. The persistence of local populations was a stochastic outcome of recovery rates from both RHD and myxomatosis. If susceptibility to RHD is delayed, myxomatosis will have a pronounced effect on population extirpation when the two viruses coexist. This has important implications for wildlife management, because it is likely that such seasonal interplay and disease dynamics has a strong effect on long-term population viability for many species. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  9. Seasonal Dynamics of River Corridor Exchange Across the Continental United States

    Science.gov (United States)

    Gomez-Velez, J. D.; Harvey, J. W.; Scott, D.; Boyer, E. W.; Schmadel, N. M.

    2017-12-01

    River corridors store and convey mass and energy from landscapes to the ocean, altering water quality and ecosystem functioning at the local, reach, and watershed scales. As water moves through river corridors from headwaters streams to coastal estuaries, dynamic exchange between the river channel and its adjacent riparian, floodplain, and hyporheic zones, combined with ponded waters such as lakes and reservoirs, results in the emergence of hot spots and moments for biogeochemical transformations. In this work, we used the model Networks with EXchange and Subsurface Storage (NEXSS) to estimate seasonal variations in river corridor exchange fluxes and residence times along the continental United States. Using a simple routing scheme, we translate these estimates into a cumulative measure of river corridor connectivity at the watershed scale, differentiating the contributions of hyporheic zones, floodplains, and ponded waters. We find that the relative role of these exchange subsystems changes seasonally, driven by the intra-seasonal variability of discharge. In addition, we find that seasonal variations in discharge and the biogeochemical potential of hyporheic zones are out of phase. This behavior results in a significant reduction in hyporheic water quality functions during high flows and emphasizes the potential importance of reconnecting floodplains for managing water quality during seasonal high flows. Physical parameterizations of river corridor processes are critical to model and predict water quality and to sustainably manage water resources under present and future socio-economic and climatic conditions. Parsimonious models like NEXSS can play a key role in the design, implementation, and evaluation of sustainable management practices that target both water quantity and quality at the scale of the nation. This research is a product of the John Wesley Powell Center River Corridor Working Group.

  10. The role of fire-return interval and season of burn in snag dynamics in a south Florida slash pine forest

    Science.gov (United States)

    Lloyd, John D.; Slater, Gary L.; Snyder, James R.

    2012-01-01

    Standing dead trees, or snags, are an important habitat element for many animal species. In many ecosystems, fire is a primary driver of snag population dynamics because it can both create and consume snags. The objective of this study was to examine how variation in two key components of the fire regime—fire-return interval and season of burn—affected population dynamics of snags. Using a factorial design, we exposed 1 ha plots, located within larger burn units in a south Florida slash pine (Pinus elliottii var. densa Little and Dorman) forest, to prescribed fire applied at two intervals (approximately 3-year intervals vs. approximately 6-year intervals) and during two seasons (wet season vs. dry season) over a 12- to 13-year period. We found no consistent effect of fire season or frequency on the density of lightly to moderately decayed or heavily decayed snags, suggesting that variation in these elements of the fire regime at the scale we considered is relatively unimportant in the dynamics of snag populations. However, our confidence in these findings is limited by small sample sizes, potentially confounding effects of unmeasured variation in fire behavior and effects (e.g., intensity, severity, synergy with drought cycles) and wide variation in responses within a treatment level. The generalizing of our findings is also limited by the narrow range of treatment levels considered. Future experiments incorporating a wider range of fire regimes and directly quantifying fire intensity would prove useful in identifying more clearly the role of fire in shaping the dynamics of snag populations.

  11. Seasonal Prediction of Regional Surface Air Temperature and First-flowering Date in South Korea using Dynamical Downscaling

    Science.gov (United States)

    Ahn, J. B.; Hur, J.

    2015-12-01

    The seasonal prediction of both the surface air temperature and the first-flowering date (FFD) over South Korea are produced using dynamical downscaling (Hur and Ahn, 2015). Dynamical downscaling is performed using Weather Research and Forecast (WRF) v3.0 with the lateral forcing from hourly outputs of Pusan National University (PNU) coupled general circulation model (CGCM) v1.1. Gridded surface air temperature data with high spatial (3km) and temporal (daily) resolution are obtained using the physically-based dynamical models. To reduce systematic bias, simple statistical correction method is then applied to the model output. The FFDs of cherry, peach and pear in South Korea are predicted for the decade of 1999-2008 by applying the corrected daily temperature predictions to the phenological thermal-time model. The WRF v3.0 results reflect the detailed topographical effect, despite having cold and warm biases for warm and cold seasons, respectively. After applying the correction, the mean temperature for early spring (February to April) well represents the general pattern of observation, while preserving the advantages of dynamical downscaling. The FFD predictabilities for the three species of trees are evaluated in terms of qualitative, quantitative and categorical estimations. Although FFDs derived from the corrected WRF results well predict the spatial distribution and the variation of observation, the prediction performance has no statistical significance or appropriate predictability. The approach used in the study may be helpful in obtaining detailed and useful information about FFD and regional temperature by accounting for physically-based atmospheric dynamics, although the seasonal predictability of flowering phenology is not high enough. Acknowledgements This work was carried out with the support of the Rural Development Administration Cooperative Research Program for Agriculture Science and Technology Development under Grant Project No. PJ009953 and

  12. Composition, distribution and abundance of ichthyoplankton in the ...

    African Journals Online (AJOL)

    1989-06-29

    Jun 29, 1989 ... The species composition, distribution and seasonal abundance of ichthyoplankton in the Sundays River estuary was ... The importance of southern African estuaries as nursery areas for juvenile ... 1990,25(3) the mid-channel.

  13. Seasonal PCB bioaccumulation in an arctic marine ecosystem: a model analysis incorporating lipid dynamics, food-web productivity and migration.

    Science.gov (United States)

    Laender, Frederik De; Oevelen, Dick Van; Frantzen, Sylvia; Middelburg, Jack J; Soetaert, Karline

    2010-01-01

    Primary production and species' lipid contents in Arctic ecosystems are notoriously seasonal. Additionally, seasonal migration patterns of fish may alter prey availability and thus diet. Taking the southern Barents Sea as a study region and PCBs as model contaminants, we examined to what extent each of these factors cause bioaccumulation in fish to change throughout the year. Data on physiology and standing stocks of multiple trophic levels were used to estimated season-specific carbon budgets and by inference also corresponding values for food ingestion and production of cod, capelin, and herring. When combining these values with Arctic lipid dynamics for bioaccumulation model parameter setting, we predicted bioaccumulation factors (BAFs) that were in good agreement with BAFs for cod and capelin observed between 1998 and 2008. BAFs in all fish were 10 times lower in summer than in spring and fall/winter and were mainly driven by lipid dynamics. Trophic magnification factors (TMFs: increase in BAF per unit increase in trophic level as derived from our carbon budgets) were highest for PCB 153 during spring (2.3-2.4) and lowest for PCB 52 in summer and fall/winter (1.5-1.6) and were driven by seasonal shifts in trophic level and lipid dynamics.

  14. Added value of dynamical downscaling of winter seasonal forecasts over North America

    Science.gov (United States)

    Tefera Diro, Gulilat; Sushama, Laxmi

    2017-04-01

    Skillful seasonal forecasts have enormous potential benefits for socio-economic sectors that are sensitive to weather and climate conditions, as the early warning routines could reduce the vulnerability of such sectors. In this study, individual ensemble members of the ECMWF global ensemble seasonal forecasts are dynamically downscaled to produce ensemble of regional seasonal forecasts over North America using the fifth generation Canadian Regional Climate Model (CRCM5). CRCM5 forecasts are initialized on November 1st of each year and are integrated for four months for the 1991-2001 period at 0.22 degree resolution to produce a one-month lead-time forecast. The initial conditions for atmospheric variables are obtained from ERA-Interim reanalysis, whereas the initial conditions for land surface are obtained from a separate ERA-interim driven CRCM5 simulation with spectral nudging applied to the interior domain. The global and regional ensemble forecasts were then verified to investigate the skill and economic benefits of dynamical downscaling. Results indicate that both the global and regional climate models produce skillful precipitation forecast over the southern Great Plains and eastern coasts of the U.S and skillful temperature forecasts over the northern U.S. and most of Canada. In comparison to ECMWF forecasts, CRCM5 forecasts improved the temperature forecast skill over most part of the domain, but the improvements for precipitation is limited to regions with complex topography, where it improves the frequency of intense daily precipitation. CRCM5 forecast also yields a better economic value compared to ECMWF precipitation forecasts, for users whose cost to loss ratio is smaller than 0.5.

  15. Temporal Variation in the Abundance and Richness of Foliage-Dwelling Ants Mediated by Extrafloral Nectar.

    Directory of Open Access Journals (Sweden)

    Ceres Belchior

    Full Text Available Plants bearing extrafloral nectaries (EFNs are common in the Brazilian cerrado savanna, where climatic conditions having marked seasonality influence arboreal ant fauna organization. These ant-plant interactions have rarely been studied at community level. Here, we tested whether: 1 EFN-bearing plants are more visited by ants than EFN-lacking plants; 2 ant visitation is higher in the rainy season than in dry season; 3 plants producing young leaves are more visited than those lacking young leaves in the rainy season; 4 during the dry season, plants with old leaves and flowers are more visited than plants with young leaves and bare of leaves or flowers; 5 the composition of visiting ant fauna differs between plants with and without EFNs. Field work was done in a cerrado reserve near Uberlândia, MG State, Brazil, along ten transects (total area 3,000 m2, in the rainy (October-January and dry seasons (April-July of 2010-2011. Plants (72 species; 762 individuals were checked three times per season for ant presence. Results showed that 21 species (29% and 266 individuals (35% possessed EFNs. These plants attracted 38 ant species (36 in rainy, 26 in dry season. In the rainy season, plants with EFNs had higher ant abundance/richness than plants without EFNs, but in the dry season, EFN presence did not influence ant visitation. Plant phenology affected ant richness and abundance in different ways: plants with young leaves possessed higher ant richness in the rainy season, but in the dry season ant abundance was higher on plants possessing old leaves or flowers. The species composition of plant-associated ant communities, however, did not differ between plants with and without EFNs in either season. These findings suggest that the effect of EFN presence on a community of plant-visiting ants is context dependent, being conditioned to seasonal variation.

  16. Temporal Variation in the Abundance and Richness of Foliage-Dwelling Ants Mediated by Extrafloral Nectar.

    Science.gov (United States)

    Belchior, Ceres; Sendoya, Sebastián F; Del-Claro, Kleber

    2016-01-01

    Plants bearing extrafloral nectaries (EFNs) are common in the Brazilian cerrado savanna, where climatic conditions having marked seasonality influence arboreal ant fauna organization. These ant-plant interactions have rarely been studied at community level. Here, we tested whether: 1) EFN-bearing plants are more visited by ants than EFN-lacking plants; 2) ant visitation is higher in the rainy season than in dry season; 3) plants producing young leaves are more visited than those lacking young leaves in the rainy season; 4) during the dry season, plants with old leaves and flowers are more visited than plants with young leaves and bare of leaves or flowers; 5) the composition of visiting ant fauna differs between plants with and without EFNs. Field work was done in a cerrado reserve near Uberlândia, MG State, Brazil, along ten transects (total area 3,000 m2), in the rainy (October-January) and dry seasons (April-July) of 2010-2011. Plants (72 species; 762 individuals) were checked three times per season for ant presence. Results showed that 21 species (29%) and 266 individuals (35%) possessed EFNs. These plants attracted 38 ant species (36 in rainy, 26 in dry season). In the rainy season, plants with EFNs had higher ant abundance/richness than plants without EFNs, but in the dry season, EFN presence did not influence ant visitation. Plant phenology affected ant richness and abundance in different ways: plants with young leaves possessed higher ant richness in the rainy season, but in the dry season ant abundance was higher on plants possessing old leaves or flowers. The species composition of plant-associated ant communities, however, did not differ between plants with and without EFNs in either season. These findings suggest that the effect of EFN presence on a community of plant-visiting ants is context dependent, being conditioned to seasonal variation.

  17. Sex-specific patterns in abundance, temporary emigration and survival of Indo-Pacific bottlenose dolphins (Tursiops aduncus in coastal and estuarine waters

    Directory of Open Access Journals (Sweden)

    Kate R Sprogis

    2016-02-01

    Full Text Available Inherent difficulties in determining the sex of free-ranging sexually monomorphic species often prevents a sex-specific focus on estimating abundance, movement patterns and survival rates. This study provides insights into sex-specific population parameters of Indo-Pacific bottlenose dolphins (Tursiops aduncus. Systematic, boat-based photo-identification surveys (n = 417 were conducted year-round from 2007-2013 in coastal and estuarine waters off Bunbury, Western Australia. Pollock’s Robust Design was used to quantify population parameters for three datasets: i adults and juveniles combined, ii adult females and iii adult males. For all datasets, abundance estimates varied seasonally, with general highs during summer and/or autumn, and lows during winter. Dolphins had seasonally structured temporary emigration rates with similar trends between sexes. The derived return rate (1-γ’ of temporary emigrants into the study area was highest from winter to spring, indicating that dolphins had a high probability of return into the study area during spring. We suggest that the return of dolphins into the study area and increase in abundance is influenced by the breeding season (summer/autumn. Prey availability is likely a main driver responsible for the movement of dolphins out of the study area during winter. Seasonal apparent survival rates were constant and high (0.98-0.99 for all datasets. High apparent survival rates suggest there is no permanent emigration from the study area. Our sex-specific modeling approach offers a comprehensive interpretation of the population dynamics of a top predator in a coastal and estuarine environment and acts as a model for future sex-based population studies on sexually monomorphic species.

  18. Species composition and seasonal abundance of sandflies (Diptera: Psychodidae: Phlebotominae in coffee agroecosystems

    Directory of Open Access Journals (Sweden)

    Jeanneth Perez

    2014-02-01

    Full Text Available The composition and seasonal occurrence of sandflies were investigated in coffee agroecosystems in the Soconusco region of Chiapas, Mexico. Insect sampling was performed on three plantations located at different altitudes: Finca Guadalupe Zajú [1,000 m above sea level (a.s.l.], Finca Argovia (613 m a.s.l. and Teotihuacán del Valle (429 m a.s.l.. Sandflies were sampled monthly from August 2007-July 2008 using three sampling methods: Shannon traps, CDC miniature light traps and Disney traps. Sampling was conducted for 3 h during three consecutive nights, beginning at sunset. A total of 4,387 sandflies were collected during the course of the study: 2,718 individuals in Finca Guadalupe Zajú, 605 in Finca Argovia and 1,064 in Teotihuacán del Valle. The Shannon traps captured 94.3% of the total sandflies, while the CDC light traps and Disney traps captured 4.9% and 0.8%, respectively. More females than males were collected at all sites. While the number of sandflies captured was positively correlated with temperature and relative humidity, a negative correlation was observed between sandfly numbers and rainfall. Five species of sandflies were captured: Lutzomyia cruciata , Lutzomyia texana , Lutzomyia ovallesi , Lutzomyia cratifer / undulata and Brumptomyia sp. Lu. cruciata , constituting 98.8% of the total, was the most abundant species. None of the captured sandflies was infected with Leishmania spp.

  19. Species composition and seasonal abundance of sandflies (Diptera: Psychodidae: Phlebotominae) in coffee agroecosystems

    Science.gov (United States)

    Pérez, Jeanneth; Virgen, Armando; Rojas, Julio Cesar; Rebollar-Téllez, Eduardo Alfonso; Alfredo, Castillo; Infante, Francisco; Mikery, Oscar; Marina, Carlos Felix; Ibáñez-Bernal, Sergio

    2013-01-01

    The composition and seasonal occurrence of sandflies were investigated in coffee agroecosystems in the Soconusco region of Chiapas, Mexico. Insect sampling was performed on three plantations located at different altitudes: Finca Guadalupe Zajú [1,000 m above sea level (a.s.l.)], Finca Argovia (613 m a.s.l.) and Teotihuacán del Valle (429 m a.s.l.). Sandflies were sampled monthly from August 2007-July 2008 using three sampling methods: Shannon traps, CDC miniature light traps and Disney traps. Sampling was conducted for 3 h during three consecutive nights, beginning at sunset. A total of 4,387 sandflies were collected during the course of the study: 2,718 individuals in Finca Guadalupe Zajú, 605 in Finca Argovia and 1,064 in Teotihuacán del Valle. The Shannon traps captured 94.3% of the total sandflies, while the CDC light traps and Disney traps captured 4.9% and 0.8%, respectively. More females than males were collected at all sites. While the number of sandflies captured was positively correlated with temperature and relative humidity, a negative correlation was observed between sandfly numbers and rainfall. Five species of sandflies were captured: Lutzomyia cruciata , Lutzomyia texana , Lutzomyia ovallesi , Lutzomyia cratifer / undulata and Brumptomyia sp. Lu. cruciata , constituting 98.8% of the total, was the most abundant species. None of the captured sandflies was infected with Leishmania spp. PMID:24271002

  20. Seasonal dynamics in colored dissolved organic matter in the Mediterranean Sea: Patterns and drivers

    Science.gov (United States)

    Xing, Xiaogang; Claustre, Hervé; Wang, Haili; Poteau, Antoine; D`Ortenzio, Fabrizio

    2014-01-01

    Two autonomous profiling “Bio-Argo” floats were deployed in the northwestern and eastern sub-basins of the Mediterranean Sea in 2008. They recorded at high vertical (1 m) and temporal (5 day) resolution, the vertical distribution and seasonal variation of colored dissolved organic matter (CDOM), as well as of chlorophyll-a concentration and hydrological variables. The CDOM standing stock presented a clear seasonal dynamics with the progressive summer formation and winter destruction of subsurface CDOM maxima (YSM, for Yellow Substance Maximum). It was argued that subsurface CDOM is a by-product of phytoplankton, based on two main characteristics, (1) the YSM was located at the same depth than the deep chlorophyll maximum (DCM) and (2) the CDOM increased in summer parallels the decline in chlorophyll-a. These observations suggested an indirect but tight coupling between subsurface CDOM and phytoplankton via microbial activity or planktonic foodweb interactions. Moreover, the surface CDOM variations observed both by floats and MODIS displayed different seasonal dynamics from what recorded at subsurface one. This implies that CDOM standing stock can be hardly detected by satellite. It is worthnoting that surface CDOM was found to be more related to the sea surface temperature (SST) than chlorophyll-a concentration, suggesting its physical origin, in contrast to the biological origin of YSM and subsurface standing stocks.

  1. Effect of Prophylactic Ankle-Brace Use During a High School Competitive Basketball Season on Dynamic Postural Control.

    Science.gov (United States)

    Crockett, Nathan J; Sandrey, Michelle A

    2015-08-01

    Few studies have evaluated the long-term effects of prophylactic ankle-brace use during a sport season. To determine the effects of prophylactic ankle-brace use during a high school basketball season on dynamic postural control and functional tests. Prospective repeated-measures design. High school athletic facility. 21 healthy high school basketball athletes (13 girls, 8 boys). The order of testing was randomized using the Star Excursion Balance Test (SEBT) for posteromedial (PM), medial (M), and anteromedial (AM) directions and 3 functional tests (FT) consisting of the single-leg crossover hop, single-leg vertical jump, and the single-leg 6-m hop for time at pre-, mid-, and postseason. After pretesting, the ankle brace was worn on both limbs during the entire 16-wk competitive basketball season. SEBT for PM, M, and AM and 3 single-leg FTs. Dynamic postural control using the SEBT and the 3 FTs improved over time, notably from pretest to posttest. The left limb was different from the right limb during the single-leg vertical jump. Effect sizes were large for pretest to posttest for the 3 SEBT directions and 2 of the 3 FTs. The 16-wk basketball prophylactic ankle-brace intervention significantly improved dynamic postural control and single-limb FTs over time.

  2. Quantifying temporal trends in fisheries abundance using Bayesian dynamic linear models: A case study of riverine Smallmouth Bass populations

    Science.gov (United States)

    Schall, Megan K.; Blazer, Vicki S.; Lorantas, Robert M.; Smith, Geoffrey; Mullican, John E.; Keplinger, Brandon J.; Wagner, Tyler

    2018-01-01

    Detecting temporal changes in fish abundance is an essential component of fisheries management. Because of the need to understand short‐term and nonlinear changes in fish abundance, traditional linear models may not provide adequate information for management decisions. This study highlights the utility of Bayesian dynamic linear models (DLMs) as a tool for quantifying temporal dynamics in fish abundance. To achieve this goal, we quantified temporal trends of Smallmouth Bass Micropterus dolomieu catch per effort (CPE) from rivers in the mid‐Atlantic states, and we calculated annual probabilities of decline from the posterior distributions of annual rates of change in CPE. We were interested in annual declines because of recent concerns about fish health in portions of the study area. In general, periods of decline were greatest within the Susquehanna River basin, Pennsylvania. The declines in CPE began in the late 1990s—prior to observations of fish health problems—and began to stabilize toward the end of the time series (2011). In contrast, many of the other rivers investigated did not have the same magnitude or duration of decline in CPE. Bayesian DLMs provide information about annual changes in abundance that can inform management and are easily communicated with managers and stakeholders.

  3. Spatiotemporal Dynamics of Surface Water Extent from Three Decades of Seasonally Continuous Landsat Time Series at Subcontinental Scale

    Science.gov (United States)

    Tulbure, M. G.; Broich, M.; Stehman, Stephen V.

    2016-06-01

    Surface water is a critical resource in semi-arid areas. The Murray-Darling Basin (MDB) of Australia, one of the largest semi-arid basins in the world is aiming to set a worldwide example of how to balance multiple interests (i.e. environment, agriculture and urban use), but has suffered significant water shrinkages during the Millennium Drought (1999-2009), followed by extensive flooding. Baseline information and systematic quantification of surface water (SW) extent and flooding dynamics in space and time are needed for managing SW resources across the basin but are currently lacking. To synoptically quantify changes in SW extent and flooding dynamics over MDB, we used seasonally continuous Landsat TM and ETM+ data (1986 - 2011) and generic machine learning algorithms. We further mapped flooded forest at a riparian forest site that experienced severe tree dieback due to changes in flooding regime. We used a stratified sampling design to assess the accuracy of the SW product across time. Accuracy assessment yielded an overall classification accuracy of 99.94%, with producer's and user's accuracy of SW of 85.4% and 97.3%, respectively. Overall accuracy was the same for Landsat 5 and 7 data but user's and producer's accuracy of water were higher for Landsat 7 than 5 data and stable over time. Our validated results document a rapid loss in SW bodies. The number, size, and total area of SW showed high seasonal variability with highest numbers in winter and lowest numbers in summer. SW extent per season per year showed high interannual and seasonal variability, with low seasonal variability during the Millennium Drought. Examples of current uses of the new dataset will be presented and include (1) assessing ecosystem response to flooding with implications for environmental water releases, one of the largest investment in environment in Australia; (2) quantifying drivers of SW dynamics (e.g. climate, human activity); (3) quantifying changes in SW dynamics and

  4. Phytoplankton abundance, dominance and coexistence in an eutrophic reservoir in the state of Pernambuco, Northeast Brazil.

    Science.gov (United States)

    Lira, Giulliari A S T; Araújo, Elcida L; Bittencourt-Oliveira, Maria Do Carmo; Moura, Ariadne N

    2011-12-01

    The present study reports the phytoplankton abundance, dominance and co-existence relationships in the eutrophic Carpina reservoir, Pernambuco, Brazil. Sampling was carried out at six different depths bimonthly at a single reservoir spanning two climatic periods: dry season (January, September, and November 2006) and rainy season (March, May, and July 2006). Density, abundance, dominance, specific diversity and equitability of the community were determined, along with chlorophyll a, and physical and chemical variables of the environment. Eight species were considered abundant, and their densities corresponded to more than 90% of the total phytoplankton community quantified. Cyanobacteria represented more than 80% of this density. Cylindrospermopsis raciborskii was the only dominant taxon in the dry season, and was co-dominant in the rainy season. C. raciborskii, Planktothrix agardhii and Geitlerinema amphibium had the greatest densities and lowest vertical variation coefficients. The statistical analysis indicated relationships with vertical and seasonal variations in the phytoplankton community and the following variables: total dissolved solids, water temperature, electrical conductivity and pH. The changes in the environmental variables were discrete and regulated by the establishment of precipitation however, they were able to promote vertical and seasonal instability in the structure of the phytoplankton community.

  5. Composition and abundance of zooplankton groups from a coral reef lagoon in Puerto Morelos, Quintana Roo, Mexico, during an annual cycle.

    Science.gov (United States)

    Alvarez-Cadena, José N; Ordóñez-López, Uriel; Almaral-Mendivil, Alma Rosa; Uicab-Sabido, Amira

    2009-09-01

    Zooplankton sampling was carried out monthly from January to December 1990 at station A near the coastline, and station B near the reef barrier, in a tropical coral reef lagoon in the Mexican Caribbean Sea. Samplings were made at midnight, near surface, with a conical net (mouth 0.40 m, mesh 330 microm) for 10 min. Salinity varied from 35.1 to 36.3 psu and temperature from 26.3 to 30.2 degrees C. The Bray-Curtis test applied to these results has defined two seasons: the dry season from November to May, and the wet season from June to October. A total of 37 zooplankton groups were found. Copepods were the most abundant contributing 49.0% of the total capture with Acartia espinata, Calanopia americana and Farranula gracilis as the most numerous. In the total zooplankton, however, cirripeds captured in only 15 samples of 24 were second in abundance (20.9%). Decapods, present all year-round and more abundant during the wet season, were third and contributed 19.2%. The rest of the groups were scarce and only amphipods (2.4%) and larvaceans (2.0%) were relatively abundant. The abundance of captured organisms correlated with the abiotic factors measured, thus, in the dry season, abundance was lower (mean 7.3 orgs/m3), while in the wet season the mean catch was 36.8 orgs/m3.

  6. Effect of water stress on seedling growth in two species with different abundances: the importance of Stress Resistance Syndrome in seasonally dry tropical forest

    Directory of Open Access Journals (Sweden)

    Wanessa Nepomuceno Ferreira

    2015-09-01

    Full Text Available ABSTRACTIn seasonally dry tropical forests, species carrying attributes of Stress Resistance Syndrome (SRS may have ecological advantages over species demanding high quantities of resources. In such forests, Poincianella bracteosa is abundant, while Libidibia ferrea has low abundance; therefore, we hypothesized that P. bracteosa has characteristics of low-resource species, while L. ferrea has characteristics of high-resource species. To test this hypothesis, we assessed morphological and physiological traits of seedlings of these species under different water regimes (100%, 70%, 40%, and 10% field capacity over 85 days. For most of the studied variables we observed significant decreases with increasing water stress, and these reductions were greater in L. ferrea. As expected, L. ferreamaximized their growth with increased water supply, while P. bracteosa maintained slower growth and had minor adjustments in biomass allocation, characteristics representative of low-resource species that are less sensitive to stress. We observed that specific leaf area, biomass allocation to roots, and root/shoot ratio were higher in L. ferrea, while biomass allocation to leaves and photosynthesis were higher in P. bracteosa. Results suggest that the attributes of SRS can facilitate high abundance of P. bracteosa in dry forest.

  7. Examining secular trend  and seasonality in count data using dynamic generalized linear modelling

    DEFF Research Database (Denmark)

    Lundbye-Christensen, Søren; Dethlefsen, Claus; Gorst-Rasmussen, Anders

    series regression model for Poisson counts. It differs in allowing the regression coefficients to vary gradually over time in a random fashion. Data  In the period January 1980 to 1999, 17,989 incidents of acute myocardial infarction were recorded in the county of Northern Jutland, Denmark. Records were......Aims  Time series of incidence counts often show secular trends and seasonal patterns. We present a model for incidence counts capable of handling a possible gradual change in growth rates and seasonal patterns, serial correlation and overdispersion. Methods  The model resembles an ordinary time...... updated daily. Results  The model with a seasonal pattern and an approximately linear trend was fitted to the data, and diagnostic plots indicate a good model fit. The analysis with the dynamic model revealed peaks coinciding with influenza epidemics. On average the peak-to-trough ratio is estimated...

  8. Gastrointestinal helminths may affect host susceptibility to anthrax through seasonal immune trade-offs.

    Science.gov (United States)

    Cizauskas, Carrie A; Turner, Wendy C; Wagner, Bettina; Küsters, Martina; Vance, Russell E; Getz, Wayne M

    2014-11-12

    Most vertebrates experience coinfections, and many pathogen-pathogen interactions occur indirectly through the host immune system. These interactions are particularly strong in mixed micro-macroparasite infections because of immunomodulatory effects of helminth parasites. While these trade-offs have been examined extensively in laboratory animals, few studies have examined them in natural systems. Additionally, many wildlife pathogens fluctuate seasonally, at least partly due to seasonal host immune changes. We therefore examined seasonality of immune resource allocation, pathogen abundance and exposure, and interactions between infections and immunity in plains zebra (Equus quagga) in Etosha National Park (ENP), Namibia, a system with strongly seasonal patterns of gastrointestinal (GI) helminth infection intensity and concurrent anthrax outbreaks. Both pathogens are environmentally transmitted, and helminth seasonality is driven by environmental pressures on free living life stages. The reasons behind anthrax seasonality are currently not understood, though anthrax is less likely directly driven by environmental factors. We measured a complex, interacting set of variables and found evidence that GI helminth infection intensities, eosinophil counts, IgE and IgGb antibody titers, and possibly IL-4 cytokine signaling were increased in wetter seasons, and that ectoparasite infestations and possibly IFN-γ cytokine signaling were increased in drier seasons. Monocyte counts and anti-anthrax antibody titers were negatively associated with wet season eosinophilia, and monocytes were negatively correlated with IgGb and IgE titers. Taken together, this supports the hypothesis that ENP wet seasons are characterized by immune resource allocation toward Th-2 type responses, while Th1-type immunity may prevail in drier seasons, and that hosts may experience Th1-Th2 trade-offs. We found evidence that this Th2-type resource allocation is likely driven by GI parasite infections

  9. Seasonal dynamics of ectomycorrhizal fungus assemblages on oak seedlings in the southeastern Appalachian Mountains

    Science.gov (United States)

    John F. Walker; Orson K. Jr. Miller; Jonathan L. Horton

    2008-01-01

    The potential for seasonal dynamics in ectomycorrhizal (EM) fungal assemblages has important implications for the ecology of both the host trees and the fungal associates. We compared EM fungus distributions on root systems of out-planted oak seedlings at two sites in mixed southeastern Appalachian Mountain forests at the Coweeta Hydrologic Laboratory in North Carolina...

  10. Demand for seasonal gas storage in northwest Europe until 2030. Simulation results with a dynamic model

    International Nuclear Information System (INIS)

    De Joode, J.; Oezdemir, Oe.

    2010-01-01

    The fact that depletion of indigenous gas production increases gas import dependency is widely known and accepted. However, there is considerable less attention for the implications of indigenous resource depletion for the provision of seasonal flexibility. The traditionally largest source of seasonal flexibility in Europe is indigenous gas production, mainly based in the Netherlands and the United Kingdom. With the depletion of indigenous sources the market increasingly needs to rely on other sources for seasonal flexibility, such as gas storage facilities. We investigate the future need for gas storage as a source for seasonal flexibility provision using a dynamic gas market model (GASTALE) in which different potential sources for seasonal flexibility - gas production, imports via pipeline, LNG imports and storage facilities - compete with each other in a market-based environment. The inclusion of seasonal flexibility properties in a gas market model allows a more complex analysis of seasonal flexibility issues than previously documented in literature. This is demonstrated in an analysis of the future demand for gas storage in northwestern Europe until 2030. Our results indicate that there is substantial need for additional gas storage facilities and thus supports current project proposals for new investment in gas storage facilities. (author)

  11. The Role of Stream Water Carbon Dynamics and Export in the Carbon Balance of a Tropical Seasonal Rainforest, Southwest China

    Science.gov (United States)

    Zhou, Wen-Jun; Zhang, Yi-Ping; Schaefer, Douglas A.; Sha, Li-Qing; Deng, Yun; Deng, Xiao-Bao; Dai, Kai-Jie

    2013-01-01

    A two-year study (2009 ∼ 2010) was carried out to investigate the dynamics of different carbon (C) forms, and the role of stream export in the C balance of a 23.4-ha headwater catchment in a tropical seasonal rainforest at Xishuangbanna (XSBN), southwest China. The seasonal volumetric weighted mean (VWM) concentrations of total inorganic C (TIC) and dissolved inorganic C (DIC) were higher, and particulate inorganic C (PIC) and organic C (POC) were lower, in the dry season than the rainy season, while the VWM concentrations of total organic C (TOC) and dissolved organic C (DOC) were similar between seasons. With increased monthly stream discharge and stream water temperature (SWT), only TIC and DIC concentrations decreased significantly. The most important C form in stream export was DIC, accounting for 51.8% of the total C (TC) export; DOC, POC, and PIC accounted for 21.8%, 14.9%, and 11.5% of the TC export, respectively. Dynamics of C flux were closely related to stream discharge, with the greatest export during the rainy season. C export in the headwater stream was 47.1 kg C ha−1 yr−1, about 2.85% of the annual net ecosystem exchange. This finding indicates that stream export represented a minor contribution to the C balance in this tropical seasonal rainforest. PMID:23437195

  12. The role of stream water carbon dynamics and export in the carbon balance of a tropical seasonal rainforest, southwest China.

    Directory of Open Access Journals (Sweden)

    Wen-Jun Zhou

    Full Text Available A two-year study (2009 ~ 2010 was carried out to investigate the dynamics of different carbon (C forms, and the role of stream export in the C balance of a 23.4-ha headwater catchment in a tropical seasonal rainforest at Xishuangbanna (XSBN, southwest China. The seasonal volumetric weighted mean (VWM concentrations of total inorganic C (TIC and dissolved inorganic C (DIC were higher, and particulate inorganic C (PIC and organic C (POC were lower, in the dry season than the rainy season, while the VWM concentrations of total organic C (TOC and dissolved organic C (DOC were similar between seasons. With increased monthly stream discharge and stream water temperature (SWT, only TIC and DIC concentrations decreased significantly. The most important C form in stream export was DIC, accounting for 51.8% of the total C (TC export; DOC, POC, and PIC accounted for 21.8%, 14.9%, and 11.5% of the TC export, respectively. Dynamics of C flux were closely related to stream discharge, with the greatest export during the rainy season. C export in the headwater stream was 47.1 kg C ha(-1 yr(-1, about 2.85% of the annual net ecosystem exchange. This finding indicates that stream export represented a minor contribution to the C balance in this tropical seasonal rainforest.

  13. Seasonal and interannual dynamics of soil microbial biomass and available nitrogen in an alpine meadow in the eastern part of Qinghai-Tibet Plateau, China

    Science.gov (United States)

    Xu, Bo; Wang, Jinniu; Wu, Ning; Wu, Yan; Shi, Fusun

    2018-01-01

    Soil microbial activity varies seasonally in frozen alpine soils during cold seasons and plays a crucial role in available N pool accumulation in soil. The intra- and interannual patterns of microbial and nutrient dynamics reflect the influences of changing weather factors, and thus provide important insights into the biogeochemical cycles and ecological functions of ecosystems. We documented the seasonal and interannual dynamics of soil microbial and available N in an alpine meadow in the eastern part of Qinghai-Tibet Plateau, China, between April 2011 and October 2013. Soil was collected in the middle of each month and analyzed for water content, microbial biomass C (MBC) and N (MBN), dissolved organic C and N, and inorganic N. Soil microbial community composition was measured by the dilution-plate method. Fungi and actinomycetes dominated the microbial community during the nongrowing seasons, and the proportion of bacteria increased considerably during the early growing seasons. Trends of consistently increasing MBC and available N pools were observed during the nongrowing seasons. MBC sharply declined during soil thaw and was accompanied by a peak in available N pool. Induced by changes in soil temperatures, significant shifts in the structures and functions of microbial communities were observed during the winter-spring transition and largely contributed to microbial reduction. The divergent seasonal dynamics of different N forms showed a complementary nutrient supply pattern during the growing season. Similarities between the interannual dynamics of microbial biomass and available N pools were observed, and soil temperature and water conditions were the primary environmental factors driving interannual fluctuations. Owing to the changes in climate, seasonal soil microbial activities and nutrient supply patterns are expected to change further, and these changes may have crucial implications for the productivity and biodiversity of alpine ecosystems.

  14. The response of archaeal species to seasonal variables in a subtropical aerated soil: insight into the low abundant methanogens.

    Science.gov (United States)

    Xie, Wei; Jiao, Na; Ma, Cenling; Fang, Sa; Phelps, Tommy J; Zhu, Ruixin; Zhang, Chuanlun

    2017-08-01

    Archaea are cosmopolitan in aerated soils around the world. While the dominance of Thaumarchaeota has been reported in most soils, the methanogens are recently found to be ubiquitous but with low abundances in the aerated soil globally. However, the seasonal changes of Archaea community in the aerated soils are still in the mist. In this study, we investigated the change of Archaea in the context of environmental variables over a period of 12 months in a subtropical soil on the Chongming Island, China. The results showed that Nitrososphaera spp. were the dominant archaeal population while the methanogens were in low proportions but highly diverse (including five genera: Methanobacterium, Methanocella, Methanosaeta, Methanosarcina, and Methanomassiliicoccus) in the aerated soil samples determined by high throughput sequencing. A total of 126 LSA correlations were found in the dataset including all the 72 archaeal OTUs and 8 environmental factors. A significance index defined as the pagerank score of each OTU divided by its relative abundance was used to evaluate the significance of each OTU. The results showed that five out of 17 methanogen OTUs were significantly positively correlated with temperature, suggesting those methanogens might increase with temperature rather than being dormant in the aerated soils. Given the metabolic response of methanogens to temperature under aerated soil conditions, their contribution to the global methane cycle warrants evaluation.

  15. Seasonal and long-term changes in relative abundance of bull sharks from a tourist shark feeding site in Fiji.

    Science.gov (United States)

    Brunnschweiler, Juerg M; Baensch, Harald

    2011-01-27

    Shark tourism has become increasingly popular, but remains controversial because of major concerns originating from the need of tour operators to use bait or chum to reliably attract sharks. We used direct underwater sampling to document changes in bull shark Carcharhinus leucas relative abundance at the Shark Reef Marine Reserve, a shark feeding site in Fiji, and the reproductive cycle of the species in Fijian waters. Between 2003 and 2009, the total number of C. leucas counted on each day ranged from 0 to 40. Whereas the number of C. leucas counted at the feeding site increased over the years, shark numbers decreased over the course of a calendar year with fewest animals counted in November. Externally visible reproductive status information indicates that the species' seasonal departure from the feeding site may be related to reproductive activity.

  16. Density and Seasonal Dynamics of Bemisia tabaci (Gennadius) Mediterranean on Common Crops and Weeds around Cotton Fields in Northern China

    DEFF Research Database (Denmark)

    Zhang, Xiao-ming; Yang, Nian-wan; Wan, Fang-hao

    2014-01-01

    theophrasti Medicus), sunflower (Helianthus annuus L.), sweet potato (Ipomoea batatas L.), soybean (Glycine max L.), and maize (Zea mays L.). The whitefly species identity was repeatedly tested and confirmed; seasonal dynamics on the various host plants was standardized by the quartile method. B. tabaci MED......The density seasonal dynamics of Bemisia tabaci MED were evaluated over two-years in a cotton-growing area in Langfang, Hebei Province, northern China on cotton (Gossypium hirsutum L.) and six other, co-occurring common plants: common ragweed (Ambrosia artemisiifolia L.), piemarker (Abutilon...

  17. Diversity and aboveground biomass of lianas in the tropical seasonal rain forests of Xishuangbanna, SW China.

    Science.gov (United States)

    Lü, Xiao-Tao; Tang, Jian-Wei; Feng, Zhi-Li; Li, Mai-He

    2009-01-01

    Lianas are important components of tropical forests and have significant impacts on the diversity, structure and dynamics of tropical forests. The present study documented the liana flora in a Chinese tropical region. Species richness, abundance, size-class distribution and spatial patterns of lianas were investigated in three 1-ha plots in tropical seasonal rain forests in Xishuangbanna, SW China. All lianas with > or = 2 cm diameter at breast height (dbh) were measured, tagged and identified. A total of 458 liana stems belonging to 95 species (ranging from 38 to 50 species/ha), 59 genera and 32 families were recorded in the three plots. The most well-represented families were Loganiaceae, Annonceae, Papilionaceae, Apocynaceae and Rhamnaceae. Papilionaceae (14 species recorded) was the most important family in the study forests. The population density, basal area and importance value index (IVI) varied greatly across the three plots. Strychnos cathayensis, Byttneria grandifolia and Bousigonia mekongensis were the dominant species in terms of IVI across the three plots. The mean aboveground biomass of lianas (3 396 kg/ha) accounted for 1.4% of the total community above-ground biomass. The abundance, diversity and biomass of lianas in Xishuangbanna tropical seasonal rain forests are lower than those in tropical moist and wet forests, but higher than those in tropical dry forests. This study provides new data on lianas from a geographical region that has been little-studied. Our findings emphasize that other factors beyond the amount and seasonality of precipitation should be included when considering the liana abundance patterns across scales.

  18. Estimating breeding season abundance of golden-cheeked warblers in Texas, USA

    KAUST Repository

    Mathewson, Heather A.

    2012-02-15

    Population abundance estimates using predictive models are important for describing habitat use and responses to population-level impacts, evaluating conservation status of a species, and for establishing monitoring programs. The golden-cheeked warbler (Setophaga chrysoparia) is a neotropical migratory bird that was listed as federally endangered in 1990 because of threats related to loss and fragmentation of its woodland habitat. Since listing, abundance estimates for the species have mainly relied on localized population studies on public lands and qualitative-based methods. Our goal was to estimate breeding population size of male warblers using a predictive model based on metrics for patches of woodland habitat throughout the species\\' breeding range. We first conducted occupancy surveys to determine range-wide distribution. We then conducted standard point-count surveys on a subset of the initial sampling locations to estimate density of males. Mean observed patch-specific density was 0.23 males/ha (95% CI = 0.197-0.252, n = 301). We modeled the relationship between patch-specific density of males and woodland patch characteristics (size and landscape composition) and predicted patch occupancy. The probability of patch occupancy, derived from a model that used patch size and landscape composition as predictor variables while addressing effects of spatial relatedness, best predicted patch-specific density. We predicted patch-specific densities as a function of occupancy probability and estimated abundance of male warblers across 63,616 woodland patches accounting for 1.678 million ha of potential warbler habitat. Using a Monte Carlo simulation, our approach yielded a range-wide male warbler population estimate of 263,339 (95% CI: 223,927-302,620). Our results provide the first abundance estimate using habitat and count data from a sampling design focused on range-wide inference. Managers can use the resulting model as a tool to support conservation planning

  19. Seasonal dynamics of early life stages of invasive and native ctenophores give clues to invasion and bloom potential in the Baltic Sea

    DEFF Research Database (Denmark)

    Jaspers, Cornelia; Haraldsson, Matilda; Lombard, Fabien

    2013-01-01

    and distribution of larvae and eggs of these two species. We show that their occurrence is significantly but inversely related to salinity. Mertensia ovum was present year round throughout the brackish Baltic Sea but also occurred in high-saline areas during cold seasons. Larvae of M. leidyi occurred throughout......Recently, both the invasive ctenophore Mnemiopsis leidyi and the arctic Mertensia ovum were discovered in the Baltic Sea but their range expansion remains unclear due to misidentification of their larval stages. Supported by molecular species verification we describe seasonal abundance...

  20. The Role of Phytoplankton Dynamics in the Seasonal and Interannual Variability of Carbon in the Subpolar North Atlantic - a Modeling Study

    Science.gov (United States)

    Signorini, Sergio; Hakkinen, Sirpa; Gudmundsson, K.; Olsen, A.; Omar, A. M.; Olafsson, J.; Reverdin, G.; Henson, S. A.; McClain, C. R.; Worthen, D. L.

    2014-01-01

    We developed an ecosystem/biogeochemical model system, which includes multiple phytoplankton functional groups and carbon cycle dynamics, and applied it to investigate physical-biological interactions in Icelandic waters. Satellite and in situ data were used to evaluate the model. Surface seasonal cycle amplitudes and biases of key parameters (DIC, TA, pCO2, air-sea CO2 flux, and nutrients) are significantly improved when compared to surface observations by prescribing deep water values and trends, based on available data. The seasonality of the coccolithophore and "other phytoplankton" (diatoms and dinoflagellates) blooms is in general agreement with satellite ocean color products. Nutrient supply, biomass and calcite concentrations are modulated by light and mixed layer depth seasonal cycles. Diatoms are the most abundant phytoplankton, with a large bloom in early spring and a secondary bloom in fall. The diatom bloom is followed by blooms of dinoflagellates and coccolithophores. The effect of biological changes on the seasonal variability of the surface ocean pCO2 is nearly twice the temperature effect, in agreement with previous studies. The inclusion of multiple phytoplankton functional groups in the model played a major role in the accurate representation of CO2 uptake by biology. For instance, at the peak of the bloom, the exclusion of coccolithophores causes an increase in alkalinity of up to 4 µmol kg(sup -1) with a corresponding increase in DIC of up to 16 µmol kg(sup -1). During the peak of the bloom in summer, the net effect of the absence of the coccolithophores bloom is an increase in pCO2 of more than 20 µatm and a reduction of atmospheric CO2 uptake of more than 6 mmolm(sup -2) d(sup -1). On average, the impact of coccolithophores is an increase of air-sea CO2 flux of about 27 %. Considering the areal extent of the bloom from satellite images within the Irminger and Icelandic Basins, this reduction translates into an annual mean of nearly 1500

  1. Seasonal variation of flavonoids in Teucrium polium L. (Lamiaceae

    Directory of Open Access Journals (Sweden)

    Gjoshe Stefkov

    2009-02-01

    Full Text Available Тhe aim of the present study was identification of flavone aglycones and determination of the content of each and the content of total flavonoids as well as investigation of the eventual seasonal variations of flavonoids in Teucrium polium L. (Lamiaceae. The plant samples were collected at six different locations in Republic of Macedonia, during summer in 1999, 2000 and 2003. For determination of seasonal variations, the samples were collected in v. Koleshino, in 2004, each month during the whole season. Six flavone aglycones (luteolin, apigenin, diosmetin, cirsiliol, cirsimaritin and cirsilineol were identified in the hydrolyzed extracts of the over ground part of Teucrium polium by HPLC method. The most abundant flavone was luteolin, followed by apigenin and cirsimaritin. Great seasonal variations were found in the content of each and in the content of total amount of flavonoids. The most abundant flavone during the whole season was luteolin with the highest content in May. The content of total flavonids was the highest in the period from May to July, which could be recommended as the most convenience period in the season for collecting of the plant material from Teucrium polium.

  2. Trophic roles of scavenger beetles in relation to decomposition stages and seasons

    Directory of Open Access Journals (Sweden)

    Noelia I. Zanetti

    2015-06-01

    Full Text Available Carcasses represent a trophic and reproductive resource or shelter for arthropods, which are a representative component of the decomposition process. Four experiments, one per season, were conducted in a semi-rural area of Bahía Blanca, Argentina, to study the trophic roles of cadaveric beetles, evaluating the abundance, composition and dominance during all decomposition stages and seasons. Species of necrophagous, necrophilous and omnivorous habits were found. Abundance, composition and dominance of beetles in relation to their trophic roles changed according to seasons and decomposition stages. Guilds and patterns of succession were established in relation to those periods. Trophic roles could be an indicator of beetle associations with decomposition stages and seasons.

  3. Seasonal patterns of mixed species groups in large East African mammals.

    Science.gov (United States)

    Kiffner, Christian; Kioko, John; Leweri, Cecilia; Krause, Stefan

    2014-01-01

    Mixed mammal species groups are common in East African savannah ecosystems. Yet, it is largely unknown if co-occurrences of large mammals result from random processes or social preferences and if interspecific associations are consistent across ecosystems and seasons. Because species may exchange important information and services, understanding patterns and drivers of heterospecific interactions is crucial for advancing animal and community ecology. We recorded 5403 single and multi-species clusters in the Serengeti-Ngorongoro and Tarangire-Manyara ecosystems during dry and wet seasons and used social network analyses to detect patterns of species associations. We found statistically significant associations between multiple species and association patterns differed spatially and seasonally. Consistently, wildebeest and zebras preferred being associated with other species, whereas carnivores, African elephants, Maasai giraffes and Kirk's dik-diks avoided being in mixed groups. During the dry season, we found that the betweenness (a measure of importance in the flow of information or disease) of species did not differ from a random expectation based on species abundance. In contrast, in the wet season, we found that these patterns were not simply explained by variations in abundances, suggesting that heterospecific associations were actively formed. These seasonal differences in observed patterns suggest that interspecific associations may be driven by resource overlap when resources are limited and by resource partitioning or anti-predator advantages when resources are abundant. We discuss potential mechanisms that could drive seasonal variation in the cost-benefit tradeoffs that underpin the formation of mixed-species groups.

  4. Short-term community dynamics in seasonal and hyperseasonal cerrados

    Directory of Open Access Journals (Sweden)

    MV. Cianciaruso

    Full Text Available In South America, the largest seasonal savanna region is the Brazilian cerrado. Our aim was to study temporal changes in some community descriptors, such as floristic composition, richness, species density, plant density, and cylindrical volume, in a seasonal cerrado, comparing it to a nearby hyperseasonal cerrado. In four different seasons, we placed randomly ten 1 m² quadrats in each vegetation form and sampled all the vascular plants. Seasonal changes in floristic composition, species density, and plant density were less pronounced in the seasonal than in the hyperseasonal cerrado. Floristic similarity between the vegetation forms was lower when the hyperseasonal cerrado was waterlogged. Richness and species density were higher in the seasonal cerrado, which reached its biomass peak at mid rainy season. The hyperseasonal cerrado, in turn, reached its biomass peak at early rainy season and, despite the waterlogging, maintained it until late rainy season. In the hyperseasonal cerrado, waterlogging acts as an environmental filter restricting the number of cerrado species able to withstand it. The seasonal cerrado community was more stable than the hyperseasonal one. Our results corroborated the idea that changes in the environmental filters will affect floristic composition and community structure in savannas.

  5. A Principal Component Analysis (PCA Approach to Seasonal and Zooplankton Diversity Relationships in Fishing Grounds of Mannar Gulf, India

    Directory of Open Access Journals (Sweden)

    Selvin J. PITCHAIKANI

    2017-06-01

    Full Text Available Principal component analysis (PCA is a technique used to emphasize variation and bring out strong patterns in a dataset. It is often used to make data easy to explore and visualize. The primary objective of the present study was to record information of zooplankton diversity in a systematic way and to study the variability and relationships among seasons prevailed in Gulf of Mannar. The PCA for the zooplankton seasonal diversity was investigated using the four seasonal datasets to understand the statistical significance among the four seasons. Two different principal components (PC were segregated in all the seasons homogeneously. PCA analyses revealed that Temora turbinata is an opportunistic species and zooplankton diversity was significantly different from season to season and principally, the zooplankton abundance and its dynamics in Gulf of Mannar is structured by seasonal current patterns. The factor loadings of zooplankton for different seasons in Tiruchendur coastal water (GOM is different compared with the Southwest coast of India; particularly, routine and opportunistic species were found within the positive and negative factors. The copepods Acrocalanus gracilis and Acartia erythrea were dominant in summer and Southwest monsoon due to the rainfall and freshwater discharge during the summer season; however, these species were replaced by Temora turbinata during Northeast monsoon season.

  6. New aerial survey and hierarchical model to estimate manatee abundance

    Science.gov (United States)

    Langimm, Cahterine A.; Dorazio, Robert M.; Stith, Bradley M.; Doyle, Terry J.

    2011-01-01

    Monitoring the response of endangered and protected species to hydrological restoration is a major component of the adaptive management framework of the Comprehensive Everglades Restoration Plan. The endangered Florida manatee (Trichechus manatus latirostris) lives at the marine-freshwater interface in southwest Florida and is likely to be affected by hydrologic restoration. To provide managers with prerestoration information on distribution and abundance for postrestoration comparison, we developed and implemented a new aerial survey design and hierarchical statistical model to estimate and map abundance of manatees as a function of patch-specific habitat characteristics, indicative of manatee requirements for offshore forage (seagrass), inland fresh drinking water, and warm-water winter refuge. We estimated the number of groups of manatees from dual-observer counts and estimated the number of individuals within groups by removal sampling. Our model is unique in that we jointly analyzed group and individual counts using assumptions that allow probabilities of group detection to depend on group size. Ours is the first analysis of manatee aerial surveys to model spatial and temporal abundance of manatees in association with habitat type while accounting for imperfect detection. We conducted the study in the Ten Thousand Islands area of southwestern Florida, USA, which was expected to be affected by the Picayune Strand Restoration Project to restore hydrology altered for a failed real-estate development. We conducted 11 surveys in 2006, spanning the cold, dry season and warm, wet season. To examine short-term and seasonal changes in distribution we flew paired surveys 1–2 days apart within a given month during the year. Manatees were sparsely distributed across the landscape in small groups. Probability of detection of a group increased with group size; the magnitude of the relationship between group size and detection probability varied among surveys. Probability

  7. Seasonal Snowpack Dynamics and Runoff in a Maritime Forested Basin, Niigata, Japan

    Science.gov (United States)

    Whitaker, A. C.; Sugiyama, H.

    2005-12-01

    Seasonal snowpack dynamics are described through field measurements under contrasting canopy conditions for a mountainous catchment in the Japan Sea region. Microclimatic data, snow accumulation, albedo and lysimeter runoff is given through three complete winter seasons 2002-05 in: (1) mature cedar stand, (2) larch stand, and (3) regenerating cedar stand or opening. The accumulation and melt of seasonal snowpack strongly influences streamflow runoff during December to May, including winter base-flow, mid-winter melt, rain-on-snow, and diurnal peaks driven by radiation melt in spring. Lysimeter runoff at all sites is characterised by constant ground melt of 0.8-1.0 mm/day. Rapid response to mid-winter melt or rainfall shows that the snowpack remains in a ripe or near-ripe condition throughout the snowcover season. Hourly and daily lysimeter discharge was greatest during rain-on-snow with the majority of runoff due to rainfall passing through the snowpack as opposed to snowmelt. For both rain-on-snow and radiation melt events lysimeter discharge was generally greatest at the open site, although there were exceptions such as during interception melt events. During radiation melt instantaneous discharge was up to 4.0 times greater in the opening compared to the mature cedar, and 48-hour discharge was up to 2.5 times greater. Perhaps characteristic of maritime climates, forest interception melt is shown to be important in addition to sublimation in reducing snow accumulation beneath dense canopies. While sublimation represents a loss from the catchment water balance, interception melt percolates through the snowpack and contributes to soil moisture during the winter season. Strong differences in microclimate and snowpack albedo persisted between cedar, larch and open sites, and it is suggested further work is needed to account for this in hydrological simulation models.

  8. Dynamic changes in left ventricular mass and in fat-free mass in top-level athletes during the competitive season.

    Science.gov (United States)

    D'Ascenzi, Flavio; Pelliccia, Antonio; Cameli, Matteo; Lisi, Matteo; Natali, Benedetta Maria; Focardi, Marta; Giorgi, Andrea; D'Urbano, Giorgio; Causarano, Andrea; Bonifazi, Marco; Mondillo, Sergio

    2015-01-01

    Previous cross-sectional studies have demonstrated that fat-free mass (FFM) is an important determinant of left ventricular mass (LVM) in athletes. However, cross-sectional investigations have not the ability to detect the dynamic adaptation occurring with training. We hypothesized that LVM adapts concurrently with the increase of FFM induced by exercise conditioning. We sought to study the relationship between the variations of LVM and of FFM occurring in top-level soccer players during the season. Twenty-three male top-level athletes were recruited. LVM was assessed by echocardiography and FFM by dual-energy X-ray absorptiometry. Serial measurements were performed pre-season, after 1 month, at mid- and end-season, and after 2 months of detraining. LVM significantly increased at mid-season versus pre-season values, reaching the highest value at the end of the season (p FFM significantly increased (p FFM (R = 0.36, p = 0.005; R = 0.35, p = 0.005, respectively). When ΔLVM index was set as dependent variable, the only independent predictor was ΔFFM (R = 0.87, p = 0.002). Changes in LVM occur in close association with changes in FFM, suggesting that the left ventricle adapts concurrently with the increase of the metabolically active tissue induced by training, i.e. the FFM. Therefore, the dynamic changes in FFM and LVM may reflect a physiological adaptation induced by intensive training. © The European Society of Cardiology 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  9. Host and pathogen ecology drive the seasonal dynamics of a fungal disease, white-nose syndrome.

    Science.gov (United States)

    Langwig, Kate E; Frick, Winifred F; Reynolds, Rick; Parise, Katy L; Drees, Kevin P; Hoyt, Joseph R; Cheng, Tina L; Kunz, Thomas H; Foster, Jeffrey T; Kilpatrick, A Marm

    2015-01-22

    Seasonal patterns in pathogen transmission can influence the impact of disease on populations and the speed of spatial spread. Increases in host contact rates or births drive seasonal epidemics in some systems, but other factors may occasionally override these influences. White-nose syndrome, caused by the emerging fungal pathogen Pseudogymnoascus destructans, is spreading across North America and threatens several bat species with extinction. We examined patterns and drivers of seasonal transmission of P. destructans by measuring infection prevalence and pathogen loads in six bat species at 30 sites across the eastern United States. Bats became transiently infected in autumn, and transmission spiked in early winter when bats began hibernating. Nearly all bats in six species became infected by late winter when infection intensity peaked. In summer, despite high contact rates and a birth pulse, most bats cleared infections and prevalence dropped to zero. These data suggest the dominant driver of seasonal transmission dynamics was a change in host physiology, specifically hibernation. Our study is the first, to the best of our knowledge, to describe the seasonality of transmission in this emerging wildlife disease. The timing of infection and fungal growth resulted in maximal population impacts, but only moderate rates of spatial spread. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  10. Detecting signals of seasonal influenza severity through age dynamics

    DEFF Research Database (Denmark)

    Lee, Elizabeth C.; Viboud, Cécile; Simonsen, Lone

    2015-01-01

    stages of an outbreak. To address the limitations of traditional indicators, we propose a novel severity index based on influenza age dynamics estimated from routine physician diagnosis data that can be used retrospectively and for early warning. METHODS: We developed a quantitative 'ground truth......' severity benchmark that synthesizes multiple traditional severity indicators from publicly available influenza surveillance data in the United States. Observing that the age distribution of cases may signal severity early in an epidemic, we constructed novel retrospective and early warning severity indexes....... The retrospective index was well correlated with the severity benchmark and correctly identified the two most severe seasons. The early warning index performance varied, but it projected 2007-08 as relatively severe 10 weeks prior to the epidemic peak. Influenza severity varied significantly among states within...

  11. Nutrient Dynamics of Estuarine Invertebrates Are Shaped by Feeding Guild Rather than Seasonal River Flow.

    Directory of Open Access Journals (Sweden)

    Kelly Ortega-Cisneros

    Full Text Available This study aimed to determine the variability of carbon and nitrogen elemental content, stoichiometry and diet proportions of invertebrates in two sub-tropical estuaries in South Africa experiencing seasonal changes in rainfall and river inflow. The elemental ratios and stable isotopes of abiotic sources, zooplankton and macrozoobenthos taxa were analyzed over a dry/wet seasonal cycle. Nutrient content (C, N and stoichiometry of suspended particulate matter exhibited significant spatio-temporal variations in both estuaries, which were explained by the variability in river inflow. Sediment particulate matter (%C, %N and C:N was also influenced by the variability in river flow but to a lesser extent. The nutrient content and ratios of the analyzed invertebrates did not significantly vary among seasons with the exception of the copepod Pseudodiaptomus spp. (C:N and the tanaid Apseudes digitalis (%N, C:N. These changes did not track the seasonal variations of the suspended or sediment particulate matter. Our results suggest that invertebrates managed to maintain their stoichiometry independent of the seasonality in river flow. A significant variability in nitrogen content among estuarine invertebrates was recorded, with highest % N recorded from predators and lowest %N from detritivores. Due to the otherwise general lack of seasonal differences in elemental content and stoichiometry, feeding guild was a major factor shaping the nutrient dynamics of the estuarine invertebrates. The nutrient richer suspended particulate matter was the preferred food source over sediment particulate matter for most invertebrate consumers in many, but not all seasons. The most distinct preference for suspended POM as a food source was apparent from the temporarily open/closed system after the estuary had breached, highlighting the importance of river flow as a driver of invertebrate nutrient dynamics under extreme events conditions. Moreover, our data showed that

  12. Nutrient Dynamics of Estuarine Invertebrates Are Shaped by Feeding Guild Rather than Seasonal River Flow.

    Science.gov (United States)

    Ortega-Cisneros, Kelly; Scharler, Ursula M

    2015-01-01

    This study aimed to determine the variability of carbon and nitrogen elemental content, stoichiometry and diet proportions of invertebrates in two sub-tropical estuaries in South Africa experiencing seasonal changes in rainfall and river inflow. The elemental ratios and stable isotopes of abiotic sources, zooplankton and macrozoobenthos taxa were analyzed over a dry/wet seasonal cycle. Nutrient content (C, N) and stoichiometry of suspended particulate matter exhibited significant spatio-temporal variations in both estuaries, which were explained by the variability in river inflow. Sediment particulate matter (%C, %N and C:N) was also influenced by the variability in river flow but to a lesser extent. The nutrient content and ratios of the analyzed invertebrates did not significantly vary among seasons with the exception of the copepod Pseudodiaptomus spp. (C:N) and the tanaid Apseudes digitalis (%N, C:N). These changes did not track the seasonal variations of the suspended or sediment particulate matter. Our results suggest that invertebrates managed to maintain their stoichiometry independent of the seasonality in river flow. A significant variability in nitrogen content among estuarine invertebrates was recorded, with highest % N recorded from predators and lowest %N from detritivores. Due to the otherwise general lack of seasonal differences in elemental content and stoichiometry, feeding guild was a major factor shaping the nutrient dynamics of the estuarine invertebrates. The nutrient richer suspended particulate matter was the preferred food source over sediment particulate matter for most invertebrate consumers in many, but not all seasons. The most distinct preference for suspended POM as a food source was apparent from the temporarily open/closed system after the estuary had breached, highlighting the importance of river flow as a driver of invertebrate nutrient dynamics under extreme events conditions. Moreover, our data showed that estuarine

  13. Endogenous and exogenous factors controlling temporal abundance patterns of tropical mosquitoes.

    Science.gov (United States)

    Yang, Guo-Jing; Brook, Barry W; Whelan, Peter I; Cleland, Sam; Bradshaw, Corey J A

    2008-12-01

    The growing demand for efficient and effective mosquito control requires a better understanding of vector population dynamics and how these are modified by endogenous and exogenous factors. A long-term (11-year) monitoring data set describing the relative abundance of the saltmarsh mosquito (Aedes vigilax) in the greater Darwin region, northern Australia, was examined in a suite of Gompertz-logistic (GL) models with and without hypothesized environmental correlates (high tide frequency, rainfall, and relative humidity). High tide frequency and humidity were hypothesized to influence saltmarsh mosquito abundance positively, and rainfall was hypothesized to correlate negatively by reducing the availability of suitable habitats (moist substrata) required by ovipositing adult female mosquitoes. We also examined whether environmental correlates explained the variance in seasonal carrying capacity (K) because environmental stochasticity is hypothesized to modify population growth rate (r), carrying capacity, or both. Current and lagged-time effects were tested by comparing alternative population dynamics models using three different information criteria (Akaike's Information Criterion [corrected; AIC(c)], Bayesian Information Criterion [BIC], and cross-validation [C-V]). The GL model with a two-month lag without environmental effects explained 31% of the deviance in population growth rate. This increased to > 70% under various model combinations of high tide frequency, rainfall, and relative humidity, of which, high tide frequency and rainfall had the highest contributions. Temporal variation in K was explained weakly by high tide frequency, and there was some evidence that the filling of depressions to reduce standing water availability has reduced Aedes vigilax carrying capacity over the study period. This study underscores the need to consider simultaneously both types of drivers (endogenous and exogenous) when predicting mosquito abundance and population growth

  14. Seasonal abundance, distribution, and catch per unit effort using gill ...

    African Journals Online (AJOL)

    Catch per unit effort was obtained for the fish of the Sundays .... Methods. Catch per unit effort (numbers and weight/net) of fish in the estuary was obtained from 55 .... Table 1 CPUE (number and mass) of fish caught monthly using gill-net over 12·h periods with 55 nettings at .... The abundance of some other species may.

  15. Dynamical 3-Space Predicts Hotter Early Universe: Resolves CMB-BBN 7-Li and 4-He Abundance Anomalies

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2010-01-01

    Full Text Available The observed abundances of 7 Li and 4 He are significantly inconsistent with the pre- dictions from Big Bang Nucleosynthesis (BBN when using the CDM cosmolog- ical model together with the value for B h 2 = 0 : 0224 0 : 0009 from WMAP CMB fluctuations, with the value from BBN required to fit observed abundances being 0 : 009 < B h 2 < 0 : 013. The dynamical 3-space theory is shown to predict a 20% hot- ter universe in the radiation-dominated epoch, which then results in a remarkable parameter-free agreement between the BBN and the WMAP value for B h 2 . The dy- namical 3-space also gives a parameter-free fit to the supernova redshift data, and pre- dicts that the flawed CDM model would require = 0 : 73 and M = 0 : 27 to fit the 3-space dynamics Hubble expansion, and independently of the supernova data. These results amount to the discovery of new physics for the early universe that is matched by numerous other successful observational and experimental tests.

  16. Mnemiopsis leidyi Gut Harbors Seasonally Variant and Commensal Microbial Assemblages

    Science.gov (United States)

    Mariita, R. M.; Hossain, M. J.; Liles, M. R.; Moss, A.

    2016-02-01

    Studies have shown that with widespread use of antibiotics in human and domestic animal populations, antibiotic resistance becomes increasingly common in the environment. Estuaries provide ideal conditions for acquisition and dissemination of drug resistance genes because they serve as sinks for pollution. This study aimed to identify M. leidyi microbial diversity and richness and their potential to act as vectors for antibiotic resistance determinants (ARDs). M. leidyi, although native to study area are highly invasive. Metagenomic analyses indicate that there are temporal variations of bacterioplankton assemblages in M. leidyi gut. Overall, Proteobacteria and Actinobacteria are the most abundant phyla. Despite the temporal dynamics in the microbial assemblages in M. leidyi gut, they seem to retain Propionibacterium acnes (gut microbiota in some insects) and select proteobacteria across all seasons. The results contradict previous studies that suggest that M. leidyi does not have constant a microbiota, but only seasonally variant microbial assemblages. Here we reveal the presence of M. leidyi gut ARDs in winter and summer, probably because of the ctenophores' positive geotaxis during rough surface conditions. Genes responsible for resistance to fluoroquinolones, multidrug resistance efflux pumps, mercuric reductase, copper homeostasis and blaR1 genes were observed. This is the first study to demonstrate that M. leidyi harbors constant microbiota and provides a baseline for understanding M. leidyi gut microbial and ARDs ecology. It also suggests that M. leidyi bacterial taxonomic and functional dynamics is influenced by season. Funding: Alabama EPSCoR GRSP fellowship, AU-CMB fellowship, NSF EPS-1158862, USDA-Hatch 370225-310100 (AGM, ML).

  17. Seasonal relationship between normalized difference vegetation index and abundance of the Phlebotomus kala-azar vector in an endemic focus in Bihar, India

    Directory of Open Access Journals (Sweden)

    Gouri S. Bhunia

    2012-11-01

    Full Text Available Remote sensing was applied for the collection of spatio-temporal data to increase our understanding of the potential distribution of the kala-azar vector Phlebotomus argentipes in endemic areas of the Vaishali district of Bihar, India. We produced monthly distribution maps of the normalized difference vegetation index (NDVI based on data from the thematic mapper (TM sensor onboard the Landsat-5 satellite. Minimum, maximum and mean NDVI values were computed for each month and compared with the concurrent incidence of kala-azar and the vector density. Maximum and mean NDVI values (R2 = 0.55 and R2 = 0.60, respectively, as well as the season likelihood ratio (X2 = 17.51; P <0.001, were found to be strongly associated with kala-azar, while the correlation with between minimum NDVI values and kala-azar was weak (R2 = 0.25. Additionally, a strong association was found between the mean and maximum NDVI values with seasonal vector abundance (R2 = 0.60 and R2 = 0.55, respectively but there was only a marginal association between minimum NDVI value and the spatial distribution of kala-azar vis-à-vis P. argentipes density.

  18. Seasonal patterns of mixed species groups in large East African mammals.

    Directory of Open Access Journals (Sweden)

    Christian Kiffner

    Full Text Available Mixed mammal species groups are common in East African savannah ecosystems. Yet, it is largely unknown if co-occurrences of large mammals result from random processes or social preferences and if interspecific associations are consistent across ecosystems and seasons. Because species may exchange important information and services, understanding patterns and drivers of heterospecific interactions is crucial for advancing animal and community ecology. We recorded 5403 single and multi-species clusters in the Serengeti-Ngorongoro and Tarangire-Manyara ecosystems during dry and wet seasons and used social network analyses to detect patterns of species associations. We found statistically significant associations between multiple species and association patterns differed spatially and seasonally. Consistently, wildebeest and zebras preferred being associated with other species, whereas carnivores, African elephants, Maasai giraffes and Kirk's dik-diks avoided being in mixed groups. During the dry season, we found that the betweenness (a measure of importance in the flow of information or disease of species did not differ from a random expectation based on species abundance. In contrast, in the wet season, we found that these patterns were not simply explained by variations in abundances, suggesting that heterospecific associations were actively formed. These seasonal differences in observed patterns suggest that interspecific associations may be driven by resource overlap when resources are limited and by resource partitioning or anti-predator advantages when resources are abundant. We discuss potential mechanisms that could drive seasonal variation in the cost-benefit tradeoffs that underpin the formation of mixed-species groups.

  19. Functional Stability and Community Dynamics during Spring and Autumn Seasons Over 3 Years in Camargue Microbial Mats

    Directory of Open Access Journals (Sweden)

    Mercedes Berlanga

    2017-12-01

    Full Text Available Microbial mats are complex biofilms in which the major element cycles are represented at a millimeter scale. In this study, community variability within microbial mats from the Camargue wetlands (Rhone Delta, southern France were analyzed over 3 years during two different seasons (spring and autumn and at different layers of the mat (0–2, 2–4, and 4–6 mm. To assess bacterial diversity in the mats, amplicons of the V1–V2 region of the 16S rRNA gene were sequenced. The community’s functionality was characterized using two approaches: (i inferred functionality through 16S rRNA amplicons genes according to PICRUSt, and (ii a shotgun metagenomic analysis. Based on the reads distinguished, microbial communities were dominated by Bacteria (∼94%, followed by Archaea (∼4% and Eukarya (∼1%. The major phyla of Bacteria were Proteobacteria, Bacteroidetes, Spirochaetes, Actinobacteria, Firmicutes, and Cyanobacteria, which together represented 70–80% of the total population detected. The phylum Euryarchaeota represented ∼80% of the Archaea identified. These results showed that the total bacterial diversity from the Camargue microbial mats was not significantly affected by seasonal changes at the studied location; however, there were differences among layers, especially between the 0–2 mm layer and the other two layers. PICRUSt and shotgun metagenomic analyses revealed similar general biological processes in all samples analyzed, by season and depth, indicating that different layers were functionally stable, although some taxa changed during the spring and autumn seasons over the 3 years. Several gene families and pathways were tracked with the oxic-anoxic gradient of the layers. Genes directly involved in photosynthesis (KO, KEGG Orthology were significantly more abundant in the top layer (0–2 mm than in the lower layers (2–4 and 4–6 mm. In the anoxic layers, the presence of ferredoxins likely reflected the variation of redox

  20. Seasonal population dynamics of Brachyiulus jawlowskii (Diplopoda, Julidae in the Dnieper river arena

    Directory of Open Access Journals (Sweden)

    N. G. Gudym

    2016-06-01

    Full Text Available We have researched the population dynamics of Brachyiulus jawlowskii Lohmander, 1928 in the arena of the Dnepr river (within the "Dnieper-Orilsky” Nature Reserve and also present a full picture of the habitat distribution of Julidae within the researched area. The tested models were basic types of arena biogeocenosis: sand steppe, black maple forests, artificial pine plantations, deciduous forest, meadow and swamp. Variation in population density of B. jawlowskii is determined by biotopical features. The swamp and meadow habitats can be characterized by the highest level of population dynamics. B. jawlowskii plays the greatest role in the herpetobiont grouping in swamp and oak forest habitats (6.7% and 4.6% respectively. In other types of habitat this species composes 0.1–3.5% of the total abundance of this group. The highest abundance dynamic was reached by the Julidae cenopopulations which inhabit the swamp, oak forest and meadow habitats. B. jawlowskii occupies a relatively significant share in the herpetobiont communities of these habitats. Thus, the indicators of absolute number of this species and its relative participation in the herpertobiont grouping indicate the preference of this species for marsh, oak forest and meadow habitats. These habitats can be characterized by an excessive or moderate level of edaphotopic humidification. The ecosystem of the steppe zone of Ukraine is subject to significant human impact. In nature reserves, this effect is minimized, which permits research to be conducted on regimes of natural population dynamics. We established that B. jawlowskii inhabits all habitats investigated within the arena zone of the Dnepr river. This indicates that this is an environmentally flexible Julidae species. The population dynamics of B. jawlowskii can be characterized by three distinct periods: spring-summer, summer and autumn. Each of these periods is characterized by a distinct population dynamic, but throughout the

  1. Seasonal and inter-annual dynamics of growth, non-structural carbohydrates and C stable isotopes in a Mediterranean beech forest.

    Science.gov (United States)

    Scartazza, Andrea; Moscatello, Stefano; Matteucci, Giorgio; Battistelli, Alberto; Brugnoli, Enrico

    2013-07-01

    Seasonal and inter-annual dynamics of growth, non-structural carbohydrates (NSC) and carbon isotope composition (δ(13)C) of NSC were studied in a beech forest of Central Italy over a 2-year period characterized by different environmental conditions. The net C assimilated by forest trees was mainly used to sustain growth early in the season and to accumulate storage carbohydrates in trunk and root wood in the later part of the season, before leaf shedding. Growth and NSC concentration dynamics were only slightly affected by the reduced soil water content (SWC) during the drier year. Conversely, the carbon isotope analysis on NSC revealed seasonal and inter-annual variations of photosynthetic and post-carboxylation fractionation processes, with a significant increase in δ(13)C of wood and leaf soluble sugars in the drier summer year than in the wetter one. The highly significant correlation between δ(13)C of leaf soluble sugars and SWC suggests a decrease of the canopy C isotope discrimination and, hence, an increased water-use efficiency with decreasing soil water availability. This may be a relevant trait for maintaining an acceptable plant water status and a relatively high C sink capacity during dry seasonal periods. Our results suggest a short- to medium-term homeostatic response of the Collelongo beech stand to variations in water availability and solar radiation, indicating that this Mediterranean forest was able to adjust carbon-water balance in order to prevent C depletion and to sustain plant growth and reserve accumulation during relatively dry seasons.

  2. Seasonal and spatial variation of bacterial production and abundance in the northern Levantine Sea

    Directory of Open Access Journals (Sweden)

    N. YUCEL

    2017-03-01

    Full Text Available Spatial and temporal heterogeneity in bacterial production and abundance in relation to ambient bio-physicochemical parameters has been investigated in the Levantine Sea. Five stations with different trophic states in an area extending from highly eutrophic Mersin bay to the mesotrophic Rhodes gyre area including the oligotrophic offshore waters were sampled four times. Integrated bacterial production varied between 6.1 and 90.3 µg C m-2 d-1 with higher rates occurring during September 2012 in offshore waters. Bacterial abundance ranged between 0.18 and 7.3 x 105 cells ml-1 within the euphotic zone and was generally higher up to 100 meters throughout the study period. In offshore waters, bacterial production (0.401 to 0.050 µg C m-3 d-1, abundance (4.5 to 1.6 x 105 cells ml-1 and depth of the productive layer decreased from 150 to 75 meters westward along the transect. Although the highest abundance was observed in July 2012 in offshore waters, the highest activity was measured in September 2012. These results indicated that the temperature played a key role in regulating bacterial abundance and production in the area. High chlorophyll concentrations in March did not correspond to high bacterial abundance and production at the same time. Increase in dissolved organic carbon content following spring phytoplankton bloom and the increase in temperature in the mean time might have enhanced the bacterial activity towards summer.

  3. Ammonia-Oxidizing Archaea Are More Resistant Than Denitrifiers to Seasonal Precipitation Changes in an Acidic Subtropical Forest Soil

    Directory of Open Access Journals (Sweden)

    Jie Chen

    2017-07-01

    Full Text Available Seasonal precipitation changes are increasingly severe in subtropical areas. However, the responses of soil nitrogen (N cycle and its associated functional microorganisms to such precipitation changes remain unclear. In this study, two projected precipitation patterns were manipulated: intensifying the dry-season drought (DD and extending the dry-season duration (ED but increasing the wet-season storms following the DD and ED treatment period. The effects of these two contrasting precipitation patterns on soil net N transformation rates and functional gene abundances were quantitatively assessed through a resistance index. Results showed that the resistance index of functional microbial abundance (-0.03 ± 0.08 was much lower than that of the net N transformation rate (0.55 ± 0.02 throughout the experiment, indicating that microbial abundance was more responsive to precipitation changes compared with the N transformation rate. Spring drought under the ED treatment significantly increased the abundances of both nitrifying (amoA and denitrifying genes (nirK, nirS, and nosZ, while changes in these gene abundances overlapped largely with control treatment during droughts in the dry season. Interestingly, the resistance index of the ammonia-oxidizing archaea (AOA amoA abundance was significantly higher than that of the denitrifying gene abundances, suggesting that AOA were more resistant to the precipitation changes. This was attributed to the stronger environmental adaptability and higher resource utilization efficiency of the AOA community, as indicated by the lack of correlations between AOA gene abundance and environmental factors [i.e., soil water content, ammonium (NH4+ and dissolved organic carbon concentrations] during the experiment.

  4. Algal composition and abundance in the neuston surface micro layer from a lake and pond in Virginia (U.S.A.)

    OpenAIRE

    Harold G. MARSHALL; Lubomira BURCHARDT

    2003-01-01

    A comparative study was conducted that characterized the algae within the neuston, ca 2 mm below the surface, and the algae in the water column from two freshwater habitats. There were significant differences in total algal abundance and the abundance of diatoms, cyanoprokaryotes, and chlorophytes between the neuston and water column algae of these two regions during each season and at both sites. The pond neuston was dominated by chlorophytes, with total algal abundance ranging seasonally fr...

  5. A Lotka-Volterra competition model with seasonal succession.

    Science.gov (United States)

    Hsu, Sze-Bi; Zhao, Xiao-Qiang

    2012-01-01

    A complete classification for the global dynamics of a Lotka-Volterra two species competition model with seasonal succession is obtained via the stability analysis of equilibria and the theory of monotone dynamical systems. The effects of two death rates in the bad season and the proportion of the good season on the competition outcomes are also discussed. © Springer-Verlag 2011

  6. The value of model averaging and dynamical climate model predictions for improving statistical seasonal streamflow forecasts over Australia

    Science.gov (United States)

    Pokhrel, Prafulla; Wang, Q. J.; Robertson, David E.

    2013-10-01

    Seasonal streamflow forecasts are valuable for planning and allocation of water resources. In Australia, the Bureau of Meteorology employs a statistical method to forecast seasonal streamflows. The method uses predictors that are related to catchment wetness at the start of a forecast period and to climate during the forecast period. For the latter, a predictor is selected among a number of lagged climate indices as candidates to give the "best" model in terms of model performance in cross validation. This study investigates two strategies for further improvement in seasonal streamflow forecasts. The first is to combine, through Bayesian model averaging, multiple candidate models with different lagged climate indices as predictors, to take advantage of different predictive strengths of the multiple models. The second strategy is to introduce additional candidate models, using rainfall and sea surface temperature predictions from a global climate model as predictors. This is to take advantage of the direct simulations of various dynamic processes. The results show that combining forecasts from multiple statistical models generally yields more skillful forecasts than using only the best model and appears to moderate the worst forecast errors. The use of rainfall predictions from the dynamical climate model marginally improves the streamflow forecasts when viewed over all the study catchments and seasons, but the use of sea surface temperature predictions provide little additional benefit.

  7. Empirical phylogenies and species abundance distributions are consistent with pre-equilibrium dynamics of neutral community models with gene flow

    KAUST Repository

    Bonnet-Lebrun, Anne-Sophie

    2017-03-17

    Community characteristics reflect past ecological and evolutionary dynamics. Here, we investigate whether it is possible to obtain realistically shaped modelled communities - i.e., with phylogenetic trees and species abundance distributions shaped similarly to typical empirical bird and mammal communities - from neutral community models. To test the effect of gene flow, we contrasted two spatially explicit individual-based neutral models: one with protracted speciation, delayed by gene flow, and one with point mutation speciation, unaffected by gene flow. The former produced more realistic communities (shape of phylogenetic tree and species-abundance distribution), consistent with gene flow being a key process in macro-evolutionary dynamics. Earlier models struggled to capture the empirically observed branching tempo in phylogenetic trees, as measured by the gamma statistic. We show that the low gamma values typical of empirical trees can be obtained in models with protracted speciation, in pre-equilibrium communities developing from an initially abundant and widespread species. This was even more so in communities sampled incompletely, particularly if the unknown species are the youngest. Overall, our results demonstrate that the characteristics of empirical communities that we have studied can, to a large extent, be explained through a purely neutral model under pre-equilibrium conditions. This article is protected by copyright. All rights reserved.

  8. Empirical phylogenies and species abundance distributions are consistent with pre-equilibrium dynamics of neutral community models with gene flow

    KAUST Repository

    Bonnet-Lebrun, Anne-Sophie; Manica, Andrea; Eriksson, Anders; Rodrigues, Ana S.L.

    2017-01-01

    Community characteristics reflect past ecological and evolutionary dynamics. Here, we investigate whether it is possible to obtain realistically shaped modelled communities - i.e., with phylogenetic trees and species abundance distributions shaped similarly to typical empirical bird and mammal communities - from neutral community models. To test the effect of gene flow, we contrasted two spatially explicit individual-based neutral models: one with protracted speciation, delayed by gene flow, and one with point mutation speciation, unaffected by gene flow. The former produced more realistic communities (shape of phylogenetic tree and species-abundance distribution), consistent with gene flow being a key process in macro-evolutionary dynamics. Earlier models struggled to capture the empirically observed branching tempo in phylogenetic trees, as measured by the gamma statistic. We show that the low gamma values typical of empirical trees can be obtained in models with protracted speciation, in pre-equilibrium communities developing from an initially abundant and widespread species. This was even more so in communities sampled incompletely, particularly if the unknown species are the youngest. Overall, our results demonstrate that the characteristics of empirical communities that we have studied can, to a large extent, be explained through a purely neutral model under pre-equilibrium conditions. This article is protected by copyright. All rights reserved.

  9. Sediment dynamics in a large shallow lake characterized by seasonal flood pulse in Southeast Asia.

    Science.gov (United States)

    Siev, Sokly; Yang, Heejun; Sok, Ty; Uk, Sovannara; Song, Layheang; Kodikara, Dilini; Oeurng, Chantha; Hul, Seingheng; Yoshimura, Chihiro

    2018-08-01

    Most of studies on sediment dynamics in stable shallow lakes focused on the resuspension process as it is the dominant process. However, understanding of sediment dynamics in a shallow lake influenced by flood pulse is unclear. We tested a hypothesis that floodplain vegetation plays as a significant role in lessening the intensity of resuspension process in a shallow lake characterized by the flood pulse system. Therefore, this study aimed to investigate sediment dynamics in this type of shallow lake. The target was Tonle Sap Lake (TSL), which is a large shallow lake influenced by a flood pulse system of Mekong River located in Southeast Asia. An extensive and seasonal sampling survey was conducted to measure total suspended solid (TSS) concentrations, sedimentation and resuspension rates in TSL and its 4 floodplain areas. The study revealed that sedimentation process was dominant (TSS ranged: 3-126mgL -1 ) in the high water period (September-December) while resuspension process was dominant (TSS ranged: 4-652mgL -1 ) only in the low water period (March-June). In addition, floodplain vegetation reduced the resuspension of sediment (up to 26.3%) in water. The implication of the study showed that resuspension is a seasonally dominant process in shallow lake influenced by the flood pulse system at least for the case of TSL. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Sulfur and Iron Cycling in a Coastal Sediment - Radiotracer Studies and Seasonal Dynamics

    DEFF Research Database (Denmark)

    MOESLUND, L.; THAMDRUP, B.; JØRGENSEN, BB

    1994-01-01

    The seasonal variation in sulfate reduction and the dynamics of sulfur and iron geochemistry were studied throughout a year in sediment of Aarhus Bay, Denmark. A radiotracer method for measuring sulfate reduction rates was applied with incubation times down to 15 min and a depth resolution down...... to 2 mm in the oxidized surface layer of the sediment. The radiotracer data were analyzed by a mathematical model which showed that, due to partial, rapid reoxidation of radioactive sulfide during incubation, the actual reduction rates in this layer were probably underestimated 5-fold. In the deeper......, sulfidic zone, measured rates appeared to be correct. Sulfate reduction followed the seasonal variation in temperature with maximum activity at 1-2 cm depth in late summer. In spite of its rapid production, free H2S was detectable in the porewater only below the depth of free Fe2+ at 6-7 cm throughout...

  11. Relationships Between Denitrifier Abundance, Denitrifier Diversity and Denitrification in Gulf of Mexico Hypoxic Zone Sediments.

    Science.gov (United States)

    Proctor, L. M.; Childs, C.; MacAuley, S.

    2002-12-01

    The largest zone of anthropogenic bottom water hypoxia in the Western Hemisphere occurs seasonally in the northern Gulf of Mexico. This hypoxic zone reaches its greatest extent in the summer months and is a consequence of seasonal stratification of the water column combined with the decomposition of organic matter derived from accelerated rates of primary production. The enhanced primary production is driven by inorganic nitrogen input from the Mississippi River and these conditions would seem ideal for supporting high levels of denitrification. Yet sediment denitrification exhibited a wide range, even at the height of the seasonal hypoxia. Therefore, we compared benthic denitrifier abundances and denitrifier diversity at several stations over two seasons exhibiting extremes in denitrification to evaluate the relationship between abundances, diversity and denitrification levels. Sediment denitrification ranged from 20 to 100 umol m-2 h-1, with rates in July, 2000 approximately half that observed in July, 2001. The highest rates were generally observed at stations with bottom water DO concentrations between 1 and 3 mg l-1. Relative denitrifier abundances, using nirS and nirK as proxies for denitrifiers, suggested a direct relationship between abundances and denitrification while denitrifier diversity, measured by T-RFLPs of nirS and nirK, suggested an inverse relationship between diversity and denitrification. These results suggest that several factors are important in understanding what controls denitrification in Gulf of Mexico hypoxic zone sediments.

  12. Seasonal dynamics of phytoplankton in two tropical rivers of varying size and human impact in Southeast Nigeria

    Directory of Open Access Journals (Sweden)

    Okechukwu Idumah Okogwu

    2013-12-01

    Full Text Available Phytoplankton occurrence and dynamics in rivers are mainly shaped by hydrophysical conditions and nutrient availability. Phytoplankton main structuring factors have been poorly studied in West African rivers, and this study was undertaken to identify these conditions in two tropical rivers that vary in size and human impact. For this, environmental variables and phytoplankton monthly samples were collected from the middle reaches of Asu and Cross rivers during an 18 months survey from March 2005-July 2006. Phytoplankton biomass (F=11.87, p=0.003, Shannon-Weiner diversity and species richness (F=5.93, p=0.003 showed significant seasonality in Asu but not in Cross River. Data was analyzed with Canonical correspondence analysis (CCA and showed environmental differences between the two rivers, nitrate in Asu River (5.1-15.5mg/L was significantly higher than Cross River (0.03-1.7mg/L, while PO4 (0.2-0.9mg/L was significantly lower in Asu River compared to Cross River (0.03-2.6mg/L (p<0.05. Eutrophic factors (NO3 determined primarily phytoplankton dynamics in Asu River, especially during the dry season, whereas hydrophysical factors (depth, transparency and temperature shaped phytoplankton in Cross River. Taxa indicative of an eutrophic condition, such as Euglena, Chlorella, Chlorococcus, Ceratium, Peridinium, Anabaena, Aphanizomenon, Closterium, Scenedesmus and Pediastrum spp., were frequently encountered in the shallow impounded Asu River, while riverine species, such as Frustulia rhomboids, Gyrosigma sp., Opephora martyr and Surirella splendida dominated Cross River. A succession pattern was observed in the functional groups identified: Na/MP→TB→P (rainy→dry season was observed in Asu River, whereas MP/D predominated in Cross River for both seasons. We concluded that, if nutrients predominate hydrophysical factors in shaping phytoplankton during dry season (half of the year then, they are as important as hydrophysical factors structuring

  13. African vultures don't follow migratory herds: scavenger habitat use is not mediated by prey abundance.

    Directory of Open Access Journals (Sweden)

    Corinne J Kendall

    Full Text Available The ongoing global decline in vulture populations raises major conservation concerns, but little is known about the factors that mediate scavenger habitat use, in particular the importance of abundance of live prey versus prey mortality. We test this using data from the Serengeti-Mara ecosystem in East Africa. The two hypotheses that prey abundance or prey mortality are the main drivers of vulture habitat use provide alternative predictions. If vultures select areas based only on prey abundance, we expect tracked vultures to remain close to herds of migratory wildebeest regardless of season. However, if vultures select areas where mortality rates are greatest then we expect vultures to select the driest regions, where animals are more likely to die of starvation, and to be attracted to migratory wildebeest only during the dry season when wildebeest mortality is greatest. We used data from GSM-GPS transmitters to assess the relationship between three vulture species and migratory wildebeest in the Mara-Serengeti ecosystem. Results indicate that vultures preferentially cluster around migratory herds only during the dry season, when herds experience their highest mortality. Additionally during the wet season, Ruppell's and Lappet-faced vultures select relatively dry areas, based on Normalized Difference Vegetation Index, whereas White-backed vultures preferred wetter areas during the wet season. Differences in habitat use among species may mediate coexistence in this scavenger guild. In general, our results suggest that prey abundance is not the primary driver of avian scavenger habitat use. The apparent reliance of vultures on non-migratory ungulates during the wet season has important conservation implications for vultures in light of on-going declines in non-migratory ungulate species and use of poisons in unprotected areas.

  14. Land use determinants of small mammal abundance and distribution in a plague endemic area of Lushoto District, Tanzania.

    Science.gov (United States)

    Hieronimo, Proches; Kimaro, Didas N; Kihupi, Nganga I; Gulinck, Hubert; Mulungu, Loth S; Msanya, Balthazar M; Leirs, Herwig; Deckers, Jozef A

    2014-07-01

    Small mammals are considered to be involved in the transmission cycle of bubonic plague, still occurring in different parts of the world, including the Lushoto District in Tanzania. The objective of this study was to determine the relationship between land use types and practices and small mammal abundance and distribution. A field survey was used to collect data in three landscapes differing in plague incidences. Data collection was done both in the wet season (April-June 2012) and dry season (August-October 2012). Analysis of variance and Boosted Regression Trees (BRT) modelling technique were used to establish the relationship between land use and small mammal abundance and distribution. Significant variations (p ≤ 0.05) of small mammal abundance among land use types were identified. Plantation forest with farming, natural forest and fallow had higher populations of small mammals than the other aggregated land use types. The influence of individual land use types on small mammal abundance level showed that, in both dry and wet seasons, miraba and fallow tended to favour small mammals' habitation whereas land tillage practices had the opposite effect. In addition, during the wet season crop types such as potato and maize appeared to positively influence the distribution and abundance of small mammals which was attributed to both shelter and food availability. Based on the findings from this study it is recommended that future efforts to predict and map spatial and temporal human plague infection risk at fine scale should consider the role played by land use and associated human activities on small mammal abundance and distribution.

  15. Abundance of birds in Fukushima as judged from Chernobyl

    International Nuclear Information System (INIS)

    Møller, Anders Pape; Hagiwara, Atsushi; Matsui, Shin; Kasahara, Satoe; Kawatsu, Kencho; Nishiumi, Isao; Suzuki, Hiroyuki; Ueda, Keisuke; Mousseau, Timothy A.

    2012-01-01

    The effects of radiation on abundance of common birds in Fukushima can be assessed from the effects of radiation in Chernobyl. Abundance of birds was negatively related to radiation, with a significant difference between Fukushima and Chernobyl. Analysis of 14 species common to the two areas revealed a negative effect of radiation on abundance, differing between areas and species. The relationship between abundance and radiation was more strongly negative in Fukushima than in Chernobyl for the same 14 species, demonstrating a negative consequence of radiation for birds immediately after the accident on 11 March 2011 during the main breeding season in March–July, when individuals work close to their maximum sustainable level. - Highlights: ► Abundance of birds was negatively related to radiation in Chernobyl and Fukushima. ► Effects of radiation on abundance differed between Chernobyl and Fukushima and among species. ► For 14 species common to the two areas the effects of radiation on abundance were stronger in Fukushima than in Chernobyl. - The negative effect of radiation on abundance of birds in Fukushima exceeded that for the same species in Chernobyl.

  16. Abundance estimation and Conservation Biology

    Directory of Open Access Journals (Sweden)

    Nichols, J. D.

    2004-06-01

    and where birds occur at low densities, the number of occupied patches may provide a reasonable estimate of abundance. In other cases, occupancy can be viewed as providing information about one tail of the abundance distribution, P (N = 0. The motivation for considering occupancy as a surrogate for abundance is that occupancy is based on so–called presence–absence surveys that are frequently less expensive of time and effort than methods that estimate abundance directly. We describe one set of models that can be used to estimate occupancy for a single season and another that can be used to estimate parameters such as local probabilities of extinction and colonization that are associated with occupancy dynamics. We outline a possible hybrid approach that combines occupancy data with data on marked individuals in order to betterexplore the mechanisms underlying occupancy dynamics. These five presentations made for an interesting session containing useful information and recommendations for future work. A number of themes connecting these presentations could be emphasized. For example, two of the presentations considered alternatives to standard capture–recapture sampling that can be used to draw inferences about abundance, or a portion of the abundance distribution, with field methods that should be less expensive than usual capture–recapture approaches of handling animals. We believe that the most important theme of the session was the emphasis on the processes responsible for changes in abundance. In particular, we are excited by the potential for using hierarchical models as a means of investigating relationships among vital rates and as a means of combining multiple sources of data relevant to system dynamics. Indeed, we expect the importance of this session theme to be reflected in the content and presentations of the next EURING meeting.

  17. Abundance estimation and conservation biology

    Science.gov (United States)

    Nichols, J.D.; MacKenzie, D.I.

    2004-01-01

    birds occur at low densities, the number of occupied patches may provide a reasonable estimate of abundance. In other cases, occupancy can be viewed as providing information about one tail of the abundance distribution, P (N = 0). The motivation for considering occupancy as a surrogate for abundance is that occupancy is based on so–called presence–absence surveys that are frequently less expensive of time and effort than methods that estimate abundance directly. We describe one set of models that can be used to estimate occupancy for a single season and another that can be used to estimate parameters such as local probabilities of extinction and colonization that are associated with occupancy dynamics. We outline a possible hybrid approach that combines occupancy data with data on marked individuals in order to betterexplore the mechanisms underlying occupancy dynamics. These five presentations made for an interesting session containing useful information and recommendations for future work. A number of themes connecting these presentations could be emphasized. For example, two of the presentations considered alternatives to standard capture–recapture sampling that can be used to draw inferences about abundance, or a portion of the abundance distribution, with field methods that should be less expensive than usual capture–recapture approaches of handling animals. We believe that the most important theme of the session was the emphasis on the processes responsible for changes in abundance. In particular, we are excited by the potential for using hierarchical models as a means of investigating relationships among vital rates and as a means of combining multiple sources of data relevant to system dynamics. Indeed, we expect the importance of this session theme to be reflected in the content and presentations of the next EURING meeting.

  18. Seasonality in cholera dynamics : a rainfall-driven model explains the wide range of patterns of an infectious disease in endemic areas

    Science.gov (United States)

    Baracchini, Theo; Pascual, Mercedes; King, Aaron A.; Bouma, Menno J.; Bertuzzo, Enrico; Rinaldo, Andrea

    2015-04-01

    An explanation for the spatial variability of seasonal cholera patterns has remained an unresolved problem in tropical medicine te{pascual_2002}. Previous studies addressing the role of climate drivers in disease dynamics have focused on interannual variability and modelled seasonality as given te{king_nature}. Explanations for seasonality have relied on complex environmental interactions that vary with spatial location (involving regional hydrological models te{bertuzzo_2012}, river discharge, sea surface temperature, and plankton blooms). Thus, no simple and unified theory based on local climate variables has been formulated te{emch_2008}, leaving our understanding of seasonal variations of cholera outbreaks in different regions of the world incomplete. Through the analysis of a unique historical dataset containing 50 years of monthly meteorological, demographic and epidemiological records, we propose a mechanistic, SIR-based stochastic model for the population dynamics of cholera driven by local rainfall and temperature that is able to capture the full range of seasonal patterns in this large estuarine region, which encompasses the variety of patterns worldwide. Parameter inference was implemented via new statistical methods that allow the computation of maximum-likelihood estimates for partially observed Markov processes through sequential Monte-Carlo te{ionides_2011}. Such a model may provide a unprecedented opportunity to gain insights on the conditions and factors responsible for endemicity around the globe, and therefore, to also revise our understanding of the ecology of Vibrio cholerae. Results indicate that the hydrological regime is a decisive driver determining the seasonal dynamics of cholera. It was found that rainfall and longer water residence times tend to buffer the propagation of the disease in wet regions due to a dilution effect, while also enhancing cholera incidence in dry regions. This indicates that overall water levels matter and appear

  19. Spatiotemporal model of barley and cereal yellow dwarf virus transmission dynamics with seasonality and plant competition

    Science.gov (United States)

    S.M. Moore; C.A. Manore; V.A. Bokil; E.T. Borer; P.R. Hosseini

    2011-01-01

    Many generalist pathogens are influenced by the spatial distributions and relative abundances of susceptible host species. The spatial structure of host populations can influence patterns of infection incidence (or disease outbreaks), and the effects of a generalist pathogen on host community dynamics in a spatially heterogeneous community may differ from predictions...

  20. Seasonal gravity change at Yellowstone caldera

    Science.gov (United States)

    Poland, M. P.; de Zeeuw-van Dalfsen, E.

    2017-12-01

    The driving forces behind Yellowstone's dynamic deformation, vigorous hydrothermal system, and abundant seismicity are usually ascribed to "magmatic fluids," which could refer to magma, water, volatiles, or some combination. Deformation data alone cannot distinguish the relative importance of these fluids. Gravity measurements, however, provide an indication of mass change over time and, when combined with surface displacements, can constrain the density of subsurface fluids. Unfortunately, several decades of gravity surveys at Yellowstone have yielded ambiguous results. We suspect that the difficulty in interpreting Yellowstone gravity data is due to seasonal variations in environmental conditions—especially surface and ground water. Yellowstone gravity surveys are usually carried out at the same time of year (generally late summer) to minimize the impact of seasonality. Nevertheless, surface and subsurface water levels are not likely to be constant from year to year, given annual differences in precipitation. To assess the overall magnitude of seasonal gravity changes, we conducted gravity surveys of benchmarks in and around Yellowstone caldera in May, July, August, and October 2017. Our goal was to characterize seasonal variations due to snow melt/accumulation, changes in river and lake levels, changes in groundwater levels, and changes in hydrothermal activity. We also hope to identify sites that show little variation in gravity over the course of the 2017 surveys, as these locations may be less prone to seasonal changes and more likely to detect small variations due to magmatic processes. Preliminary examination of data collected in May and July 2017 emphasizes the importance of site location relative to sources of water. For example, a site on the banks of the Yellowstone River showed a gravity increase of several hundred microgals associated with a 50 cm increase in the river level. A high-altitude site far from rivers and lakes, in contrast, showed a

  1. The effect of local and landscape-level characteristics on the abundance of forest birds in early-successional habitats during the post-fledging season in western Massachusetts.

    Directory of Open Access Journals (Sweden)

    Michelle A Labbe

    Full Text Available Many species of mature forest-nesting birds ("forest birds" undergo a pronounced shift in habitat use during the post-fledging period and move from their forest nesting sites into areas of early-successional vegetation. Mortality is high during this period, thus understanding the resource requirements of post-fledging birds has implications for conservation. Efforts to identify predictors of abundance of forest birds in patches of early-successional habitats have so far been equivocal, yet these previous studies have primarily focused on contiguously forested landscapes and the potential for landscape-scale influences in more fragmented and modified landscapes is largely unknown. Landscape composition can have a strong influence on the abundance and productivity of forest birds during the nesting period, and could therefore affect the number of forest birds in the landscape available to colonize early-successional habitats during the post-fledging period. Therefore, the inclusion of landscape characteristics should increase the explanatory power of models of forest bird abundance in early-successional habitat patches during the post-fledging period. We examined forest bird abundance and body condition in relation to landscape and habitat characteristics of 15 early-successional sites during the post-fledging season in Massachusetts. The abundance of forest birds was influenced by within-patch habitat characteristics, however the explanatory power of these models was significantly increased by the inclusion of landscape fragmentation and the abundance of forest birds in adjacent forest during the nesting period for some species and age groups. Our findings show that including factors beyond the patch scale can explain additional variation in the abundance of forest birds in early-successional habitats during the post-fledging period. We conclude that landscape composition should be considered when siting early-successional habitat to maximize its

  2. The Effect of Local and Landscape-Level Characteristics on the Abundance of Forest Birds in Early-Successional Habitats during the Post-Fledging Season in Western Massachusetts

    Science.gov (United States)

    Labbe, Michelle A.; King, David I.

    2014-01-01

    Many species of mature forest-nesting birds (“forest birds”) undergo a pronounced shift in habitat use during the post-fledging period and move from their forest nesting sites into areas of early-successional vegetation. Mortality is high during this period, thus understanding the resource requirements of post-fledging birds has implications for conservation. Efforts to identify predictors of abundance of forest birds in patches of early-successional habitats have so far been equivocal, yet these previous studies have primarily focused on contiguously forested landscapes and the potential for landscape-scale influences in more fragmented and modified landscapes is largely unknown. Landscape composition can have a strong influence on the abundance and productivity of forest birds during the nesting period, and could therefore affect the number of forest birds in the landscape available to colonize early-successional habitats during the post-fledging period. Therefore, the inclusion of landscape characteristics should increase the explanatory power of models of forest bird abundance in early-successional habitat patches during the post-fledging period. We examined forest bird abundance and body condition in relation to landscape and habitat characteristics of 15 early-successional sites during the post-fledging season in Massachusetts. The abundance of forest birds was influenced by within-patch habitat characteristics, however the explanatory power of these models was significantly increased by the inclusion of landscape fragmentation and the abundance of forest birds in adjacent forest during the nesting period for some species and age groups. Our findings show that including factors beyond the patch scale can explain additional variation in the abundance of forest birds in early-successional habitats during the post-fledging period. We conclude that landscape composition should be considered when siting early-successional habitat to maximize its benefit to

  3. Seasonally dynamic fungal communities in the Quercus macrocarpa phyllosphere differ between urban and nonurban environments.

    Science.gov (United States)

    Jumpponen, A; Jones, K L

    2010-04-01

    *The fungal richness, diversity and community composition in the Quercus macrocarpa phyllosphere were compared across a growing season in trees located in six stands within and outside a small urban center using 454-sequencing and DNA tagging. The approaches did not differentiate between endophytic and epiphytic fungal communities. *Fungi accumulated in the phyllosphere rapidly and communities were temporally dynamic, with more than a third of the analyzed operational taxonomic units (OTUs) and half of the BLAST-inferred genera showing distinct seasonal patterns. The seasonal patterns could be explained by fungal life cycles or environmental tolerances. *The communities were hyperdiverse and differed between the urban and nonurban stands, albeit not consistently across the growing season. Foliar macronutrients (nitrogen (N), potassium (K) and sulfur (S)), micronutrients (boron (B), manganese (Mn) and selenium (Se)) and trace elements (cadmium (Cd), lead (Pb) and zinc (Zn)) were enriched in the urban trees, probably as a result of anthropogenic activities. Because of correlations with the experimental layout, these chemical elements should not be considered as community drivers without further empirical studies. *We suggest that a combination of mechanisms leads to differences between urban and nonurban communities. Among those are stand isolation and size, nutrient and pollutant accumulation plus stand management, including fertilization and litter removal.

  4. Sedimentary oxygen dynamics in a seasonally hypoxic basin

    NARCIS (Netherlands)

    Seitaj, D.; Sulu-Gambari, F; Burdorf, L.D.W.; Romero-Ramirez, A.; Maire, O.; Malkin, S.Y.; Slomp, C. P.; Meysman, F.J.R.

    2017-01-01

    Seasonal hypoxia refers to the oxygen depletion that occurs in summer in the bottom water of stratified systems, and is increasingly observed in coastal areas worldwide. The process induces a seasonal cycle on the biogeochemistry of the underlying sediments, which remains poorly quantified. Here, we

  5. Sedimentary oxygen dynamics in a seasonally hypoxic basin

    NARCIS (Netherlands)

    Seitaj, Dorina; Sulu-Gambari, Fatimah; Burdorf, Laurine D. W.; Romero-Ramirez, Alicia; Maire, Olivier; Malkin, Sairah Y.; Slomp, Caroline P.; Meysman, Filip J.R.

    Seasonal hypoxia refers to the oxygen depletion that occurs in summer in the bottom water of stratified systems, and is increasingly observed in coastal areas worldwide. The process induces a seasonal cycle on the biogeochemistry of the underlying sediments, which remains poorly quantified. Here, we

  6. Specific structure, sexual parity and seasonal dynamics of separate kinds of ground-beetles of Tljaratinskiy area of Daghestan

    Directory of Open Access Journals (Sweden)

    M. H. Imanmirzaev

    2008-01-01

    Full Text Available As a result of carried out research in fauna of ground-beetles of Tljaratinskiy area it is revealed 87 kinds concerning 24 sorts. The sexual parity is established and seasonal dynamics of prepotent kinds is certain.

  7. Seasonal morphological variability in an in situ Cyanobacteria monoculture: example from a persistent Cylindrospermopsis bloom in Lake Catemaco, Veracruz, Mexico

    Directory of Open Access Journals (Sweden)

    Owen Lind

    2016-03-01

    Full Text Available The phrase cyanobacteria bloom implies a transient condition in which one to few species dominates communities. In this paper we describe a condition in which the bloom is of multi-year duration consisting of different morphologies of a single cyanobacteria species. Lake Catemaco, Veracruz, México maintained a year-round massive (108 trichomes L-1 population of potentially toxin-producing cyanobacteria, Cylindrospermopsis spp. The trichomes are present as straight and coiled morphotypes.  The relative trichome morphology abundance varied with rainy (June – October and dry seasons (November – May, but total trichome abundance did not vary.  Coiled trichomes and heterocytes (occurring only on coiled trichomes were significantly more abundant, both absolutely and relatively, during the dry season. Both coiled trichome and heterocyte mean volumes were significantly smaller during the rainy season than during the dry season.  Biovolumes were largest in January when water temperature was 5º C cooler suggesting buoyancy as a morphology-determining factor. However, with a more than three-fold lower TIN concentration during the dry season, we hypothesized that the coiled morphotype became abundant primarily because it formed heterocytes, which the straight morphotype did not. Spatial trichome and heterocyte abundance differences were small among the 15 lake sites (average CV for all dates = 20%. However, there was a pattern of increased heterocyte and coiled trichome abundance from lake inflow, as a nitrogen source, to outflow during the rainy season. The total volume of heterocytes per litre of lake water increased progressively four-fold from a minimum early in the rainy season to a maximum at the end of the dry season. Morphological diversity, as seen in Lake Catemaco, can partially compensate for the lack of species diversity in determination of community structure.

  8. A model of seasonal foliage dynamics of the subtropical mangrove species Rhizophora stylosa Griff. growing at the northern limit of its distribution

    Directory of Open Access Journals (Sweden)

    Sahadev Sharma

    2014-08-01

    Full Text Available Background Progress of forest production in response to the environment requires a quantitative understanding of leaf area development. Therefore, it is necessary to investigate the dynamics of seasonal crown foliage in order to understand the productivity of mangroves, which play an important role in the subtropical and tropical coastlines of the world. Method Crown foliage dynamics of the mangrove Rhizophora stylosa were studies to reveal patterns of leaf recruitment, survival and seasonal leaf area growth. Results Flushing of leaves occurred throughout the year, but both flushing and leaf area growth pattern of leaves varied with season. Maximum flushing occurred in summer, but leaf areas did not differ significantly with season. The half-expansion period is longer, and the intrinsic rate of increase was lower in winter. Summer flushed leaves grew faster at their initial stage and reached their maximum area over a shorter period of time. The difference in temperature and air vapor pressure deficit (VPD between summer and winter contributed to the present dynamics of foliage patterns. The mean leaf longevity was estimated to be 13.1 month. The crown foliage area was almost stable throughout the year. Conclusions Homeostatic control of the crown foliage area may be accompanied by the existence of ecophysiological mechanisms in R. stylosa. Integrating crown foliage dynamics into forest models represents an important step towards incorporating physiological mechanisms into the models for predicting growth responses to environmental changes and for understanding the complex responses of tree growth and litter production.

  9. SEASONAL MARKETING: STRATEGIES USING THE CALENDAR

    OpenAIRE

    Dr Anil Sardana; Dr PoojaTalwar; Shruti Gulati

    2018-01-01

    In this ever-dynamic world, the only thing that is constant is change. Change when happens, applies to all; then why should marketing remain the same? Each year is a witness to various seasons, and each season requires separate marketing efforts to be carried out differently. Seasonal marketing thus helps to capitalise on the varied demand through varied marketing. Every season requires special efforts and hence leads to different sales.

  10. Natural 15N abundance of soil N pools and N2O reflect the nitrogen dynamics of forest soils

    DEFF Research Database (Denmark)

    Pörtl, K.; Zechmeister-Boltenstern, S.; Wanek, W.

    2007-01-01

    Natural N-15 abundance measurements of ecosystem nitrogen (N) pools and N-15 pool dilution assays of gross N transformation rates were applied to investigate the potential of delta N-15 signatures of soil N pools to reflect the dynamics in the forest soil N cycle. Intact soil cores were collected...

  11. Examining secular trends and seasonality in count data using dynamic generalized linear modelling: a new methodological approach illustrated with hospital discharge data on myocardial infarction.

    Science.gov (United States)

    Lundbye-Christensen, S; Dethlefsen, C; Gorst-Rasmussen, A; Fischer, T; Schønheyder, H C; Rothman, K J; Sørensen, H T

    2009-01-01

    Time series of incidence counts often show secular trends and seasonal patterns. We present a model for incidence counts capable of handling a possible gradual change in growth rates and seasonal patterns, serial correlation, and overdispersion. The model resembles an ordinary time series regression model for Poisson counts. It differs in allowing the regression coefficients to vary gradually over time in a random fashion. During the 1983-1999 period, 17,989 incidents of acute myocardial infarction were recorded in the Hospital Discharge Registry for the county of North Jutland, Denmark. Records were updated daily. A dynamic model with a seasonal pattern and an approximately linear trend was fitted to the data, and diagnostic plots indicated a good model fit. The analysis conducted with the dynamic model revealed peaks coinciding with above-average influenza A activity. On average the dynamic model estimated a higher peak-to-trough ratio than traditional models, and showed gradual changes in seasonal patterns. Analyses conducted with this model provide insights not available from more traditional approaches.

  12. Abundance and diversity of wild mammals along a hydrologic ...

    African Journals Online (AJOL)

    This study was conducted in the Eastern Usangu wetland in Mbeya and Iringa regions to examine the composition, abundance and diversity of mammals along a hydrological gradient. Data were collected in two seasons using distance sampling method along transects and a handheld GPS to locate positions. Statistical ...

  13. Arthropod abundance and seasonal bird use of bottomland forest harvest gaps

    Science.gov (United States)

    Christopher E. Moorman; Liessa T. Woen; John C. Kilgo; James L. Hanula; Scott Horn; Michael D. Ulyshen

    2012-01-01

    We investigated the influence of arthropod abundance and vegetation structure on shifts in avian use of canopy gap, gap edge, and surrounding forest understory in a bottomland hardwood forest in the Upper Coastal Plain of South Carolina. We compared captures of foliage-gleaning birds among locations during four periods (spring migration, breeding, post-breeding, and...

  14. Abundance and frugivory of the toco toucan (Ramphastos toco in a gallery forest in Brazil's Southern Pantanal

    Directory of Open Access Journals (Sweden)

    J. Ragusa-Netto

    Full Text Available Unlike other toucan species, the Toco toucan (Ramphastos toco - the largest Ramphastidae - usually inhabits dry semi-open areas. This conspicuous canopy frugivore uses a large home range that includes a variety of vegetation types, among which gallery forests are widely cited as important to this species. However, the factors relating to the occurrence of Toco toucans in such habitats are unclear. I studied the abundance of Toco toucans as well as the availability of fleshy fruit in a gallery forest in the southern Pantanal (sub-region of Miranda, Brazil, in order to assess the relationship between these parameters. Also, I examined toucan foraging activity to analyze its relationship with both toucan abundance and fruit availability. The presence of the Toco toucan was more common in the gallery forest from the middle to the end of the dry season and during the middle of the wet season. Toucans foraged for fleshy fruits, mainly Genipa americana, Ficus luschnatiana, and Cecropia pachystachya fruits, feeding mostly on G. americana (by far the favorite food resource and F. luschnatiana fruits during the dry season, while C. pachystachya fruits were important in the wet season. Toco toucans foraged particularly heavily (> 80% of foraging activity on G. americana fruits during the latter part of the dry season, when fleshy fruit availability declined sharply. Toco toucan abundance in the gallery forest was associated with the availability of the most commonly consumed fleshy fruits, and also with its foraging activity. This finding suggests that the Toco toucan moved to the gallery forest periodically in response to the availability of abundant food resources, especially the G. americana fruits widely available and exploited during the severely dry season. Therefore, these fruits potentially contribute to Toco toucan persistence in the South Pantanal during the harshest period of the year.

  15. Abundance and frugivory of the Toco toucan (Ramphastos toco) in a gallery forest in Brazil's southern Pantanal.

    Science.gov (United States)

    Ragusa-Netto, J

    2006-02-01

    Unlike other toucan species, the Toco toucan (Ramphastos toco)--the largest Ramphastidae--usually inhabits dry semi-open areas. This conspicuous canopy frugivore uses a large home range that includes a variety of vegetation types, among which gallery forests are widely cited as important to this species. However, the factors relating to the occurrence of Toco toucans in such habitats are unclear. I studied the abundance of Toco toucans as well as the availability of fleshy fruit in a gallery forest in the southern Pantanal (sub-region of Miranda, Brazil), in order to assess the relationship between these parameters. Also, I examined toucan foraging activity to analyze its relationship with both toucan abundance and fruit availability. The presence of the Toco toucan was more common in the gallery forest from the middle to the end of the dry season and during the middle of the wet season. Toucans foraged for fleshy fruits, mainly Genipa americana, Ficus luschnatiana, and Cecropia pachystachya fruits, feeding mostly on G. americana (by far the favorite food resource) and F. luschnatiana fruits during the dry season, while C. pachystachya fruits were important in the wet season. Toco toucans foraged particularly heavily (> 80% of foraging activity) on G. americana fruits during the latter part of the dry season, when fleshy fruit availability declined sharply. Toco toucan abundance in the gallery forest was associated with the availability of the most commonly consumed fleshy fruits, and also with its foraging activity. This finding suggests that the Toco toucan moved to the gallery forest periodically in response to the availability of abundant food resources, especially the G. americana fruits widely available and exploited during the severely dry season. Therefore, these fruits potentially contribute to Toco toucan persistence in the South Pantanal during the harshest period of the year.

  16. Long-Term Effects of Season of Prescribed Burn on the Fine-Root Growth, Root Carbohydrates, and Foliar Dynamics of Mature Longleaf Pine

    Science.gov (United States)

    Eric A. Kuehler; Mary Anne Sword Sayer; James D. Haywood; C. Dan Andries

    2004-01-01

    Depending on the season and intensity of fire, as well as the phenology of foliage and new root growth, fire may damage foliage, and subsequently decrease whole-crown carbon fixation and allocation to the root system. In central Louisiana the authors investigated how season of prescribed burning affects fine-root dynamics, root carbohydrate relations, and leaf area...

  17. Litter decomposition, N2-fixer abundance, and microbial dynamics govern tropical dry forest recovery to land use change

    Science.gov (United States)

    Trierweiler, A.; Powers, J. S.; Xu, X.; Gei, M. G.; Medvigy, D.

    2017-12-01

    As one of the most threatened tropical biomes, Seasonal Dry Tropical Forests (TDF) have undergone extensive land-use change. However, some areas are undergoing recovery into secondary forests. Despite their broad distribution (42% of tropical forests), they are under-studied compared to wet tropical forests and our understanding of their biogeochemical cycling and belowground processes are limited. Here, we use models along with field measurements to improve our understanding of nutrient cycling and limitation in secondary TDFs. We ask (1) Is there modeling evidence that tropical dry forests can become nutrient limited? (2) What are the most important mechanisms employed to avoid nutrient limitation? (3) How might climate change alter biogeochemical cycling and nutrient limitation in recovering TDF? We use a new version of the Ecosystem Demography (ED2) model that has been recently parameterized for TDFs and incorporates a range of plant functional groups (including deciduousness and N2-fixation) and multiple resource constraints (carbon, nitrogen, phosphorus, and water). In the model, plants then can dynamically adjust their carbon allocation and nutrient acquisition strategies using N2-fixing bacteria and mycorrhizal fungi according to the nutrient limitation status. We ran the model for a nutrient gradient of field sites in Costa Rica and explored the sensitivity of nutrient limitation to key mechanisms including litter respiration, N resorption, N2-fixation, and overflow respiration. Future runs will evaluate how CO2 and climate change affect recovering TDFs. We found increasing nutrient limitation across the nutrient gradient of sites. Nitrogen limitation dominated the nutrient limitation signal. In the model, forest litter accumulation was negatively correlated with site fertility in Costa Rican forests. Our sensitivity analyses indicate that N2-fixer abundance, decomposition rates, and adding more explicit microbial dynamics are key factors in overcoming

  18. Spatiotemporal dynamics of the bacterial microbiota on lacustrine Cladophora glomerata (Chlorophyta).

    Science.gov (United States)

    Braus, Michael J; Graham, Linda E; Whitman, Thea L

    2017-12-01

    The branched periphytic green alga Cladophora glomerata, often abundant in nearshore waters of lakes and rivers worldwide, plays important ecosystem roles, some mediated by epibiotic microbiota that benefit from host-provided surface, organic C, and O 2 . Previous microscopy and high-throughput sequencing studies have indicated surprising epibiont taxonomic and functional diversity, but have not included adequate consideration of sample replication or the potential for spatial and temporal variation. Here, we report the results of 16S rRNA amplicon-based phylum-to-genus taxonomic analysis of Cladophora-associated bacterial epibiota sampled in replicate from three microsites and at six times during the open-water season of 2014, from the same lake locale (Picnic Point, Lake Mendota, Dane Co., WI, USA) explored by high-throughput sequencing studies in two previous years. Statistical methods were used to test null hypotheses that the bacterial community: (i) is homogeneous across microsites tested, and (ii) does not change over the course of a growth season or among successive years. Results indicated a dynamic microbial community that is more strongly influenced by sampling day during the growth season than by microsite variation. A surprising diversity of bacterial genera known to be associated with the key function of methane-oxidation (methanotrophy), including relatively high-abundance of Crenothrix, Methylomonas, Methylovulum, and Methylocaldum-showed intraseasonal and interannual variability possibly related to temperature differences, and microsite preferences possibly related to variation in methane abundance. By contrast, a core assemblage of bacterial genera seems to persist over a growth season and from year to year, possibly transmitted by a persistent attached host resting stage. © 2017 Phycological Society of America.

  19. Seasonal dynamics of the tick Haemaphysalis tibetensis in the Tibetan Plateau, China.

    Science.gov (United States)

    Liu, M; Li, T; Yu, Z J; Qiu, Z X; Yan, P; Li, Y; Liu, J

    2017-12-01

    The tick Haemaphysalis tibetensis (Acari: Ixodidae) Hoogstraal is an important arthropod vector widespread in the Qinghai-Tibet Plateau, and knowledge of its seasonal dynamics is still poor. The current study investigated the seasonal dynamics of the parasitic and non-parasitic H. tibetensis over a 2-year period from March 2014 to February 2016 in the Tibetan Plateau, China. During this timeframe, non-parasitic ticks were collected weekly by flag-dragging in grassland and shrubland areas, and parasitic ticks were removed weekly from selected sheep. Plateau pikas were captured using traps and examined for immature ticks between May to September 2014. Results suggest that non-parasitic H. tibetensis were mainly distributed in the grassland, and the parasitic adults and nymphs were found mostly on sheep. Larvae were usually found on Plateau pikas and the prevalence of infestation and mean parasitic intensity were 72.1 and 1.81%, respectively. Adults were observed from March to July with the major peak occurring in mid-April. Nymphs were found from March to August and reached a peak in late June. Larvae were collected from April to September, and their numbers peaked in late May. In the parasitic and non-parasitic period, the overall sex ratio of males to females was 1.62 and 1.30, respectively. Results show that H. tibetensis can complete one generation per year, with a population overlap between stages over the spring-summer months. These findings provide additional information on the biology and ecology of H. tibetensis as well as insights on its control in the environment and on sheep. © 2017 The Royal Entomological Society.

  20. Seasonally-Dynamic Presence-Only Species Distribution Models for a Cryptic Migratory Bat Impacted by Wind Energy Development.

    Directory of Open Access Journals (Sweden)

    Mark A Hayes

    Full Text Available Understanding seasonal distribution and movement patterns of animals that migrate long distances is an essential part of monitoring and conserving their populations. Compared to migratory birds and other more conspicuous migrants, we know very little about the movement patterns of many migratory bats. Hoary bats (Lasiurus cinereus, a cryptic, wide-ranging, long-distance migrant, comprise a substantial proportion of the tens to hundreds of thousands of bat fatalities estimated to occur each year at wind turbines in North America. We created seasonally-dynamic species distribution models (SDMs from 2,753 museum occurrence records collected over five decades in North America to better understand the seasonal geographic distributions of hoary bats. We used 5 SDM approaches: logistic regression, multivariate adaptive regression splines, boosted regression trees, random forest, and maximum entropy and consolidated outputs to generate ensemble maps. These maps represent the first formal hypotheses for sex- and season-specific hoary bat distributions. Our results suggest that North American hoary bats winter in regions with relatively long growing seasons where temperatures are moderated by proximity to oceans, and then move to the continental interior for the summer. SDMs suggested that hoary bats are most broadly distributed in autumn-the season when they are most susceptible to mortality from wind turbines; this season contains the greatest overlap between potentially suitable habitat and wind energy facilities. Comparing wind-turbine fatality data to model outputs could test many predictions, such as 'risk from turbines is highest in habitats between hoary bat summering and wintering grounds'. Although future field studies are needed to validate the SDMs, this study generated well-justified and testable hypotheses of hoary bat migration patterns and seasonal distribution.

  1. Seasonally-Dynamic Presence-Only Species Distribution Models for a Cryptic Migratory Bat Impacted by Wind Energy Development.

    Science.gov (United States)

    Hayes, Mark A; Cryan, Paul M; Wunder, Michael B

    2015-01-01

    Understanding seasonal distribution and movement patterns of animals that migrate long distances is an essential part of monitoring and conserving their populations. Compared to migratory birds and other more conspicuous migrants, we know very little about the movement patterns of many migratory bats. Hoary bats (Lasiurus cinereus), a cryptic, wide-ranging, long-distance migrant, comprise a substantial proportion of the tens to hundreds of thousands of bat fatalities estimated to occur each year at wind turbines in North America. We created seasonally-dynamic species distribution models (SDMs) from 2,753 museum occurrence records collected over five decades in North America to better understand the seasonal geographic distributions of hoary bats. We used 5 SDM approaches: logistic regression, multivariate adaptive regression splines, boosted regression trees, random forest, and maximum entropy and consolidated outputs to generate ensemble maps. These maps represent the first formal hypotheses for sex- and season-specific hoary bat distributions. Our results suggest that North American hoary bats winter in regions with relatively long growing seasons where temperatures are moderated by proximity to oceans, and then move to the continental interior for the summer. SDMs suggested that hoary bats are most broadly distributed in autumn-the season when they are most susceptible to mortality from wind turbines; this season contains the greatest overlap between potentially suitable habitat and wind energy facilities. Comparing wind-turbine fatality data to model outputs could test many predictions, such as 'risk from turbines is highest in habitats between hoary bat summering and wintering grounds'. Although future field studies are needed to validate the SDMs, this study generated well-justified and testable hypotheses of hoary bat migration patterns and seasonal distribution.

  2. Seasonally-dynamic presence-only species distribution models for a cryptic migratory bat impacted by wind energy development

    Science.gov (United States)

    Hayes, Mark A.; Cryan, Paul M.; Wunder, Michael B.

    2015-01-01

    Understanding seasonal distribution and movement patterns of animals that migrate long distances is an essential part of monitoring and conserving their populations. Compared to migratory birds and other more conspicuous migrants, we know very little about the movement patterns of many migratory bats. Hoary bats (Lasiurus cinereus), a cryptic, wide-ranging, long-distance migrant, comprise a substantial proportion of the tens to hundreds of thousands of bat fatalities estimated to occur each year at wind turbines in North America. We created seasonally-dynamic species distribution models (SDMs) from 2,753 museum occurrence records collected over five decades in North America to better understand the seasonal geographic distributions of hoary bats. We used 5 SDM approaches: logistic regression, multivariate adaptive regression splines, boosted regression trees, random forest, and maximum entropy and consolidated outputs to generate ensemble maps. These maps represent the first formal hypotheses for sex- and season-specific hoary bat distributions. Our results suggest that North American hoary bats winter in regions with relatively long growing seasons where temperatures are moderated by proximity to oceans, and then move to the continental interior for the summer. SDMs suggested that hoary bats are most broadly distributed in autumn—the season when they are most susceptible to mortality from wind turbines; this season contains the greatest overlap between potentially suitable habitat and wind energy facilities. Comparing wind-turbine fatality data to model outputs could test many predictions, such as ‘risk from turbines is highest in habitats between hoary bat summering and wintering grounds’. Although future field studies are needed to validate the SDMs, this study generated well-justified and testable hypotheses of hoary bat migration patterns and seasonal distribution.

  3. The role of phytoplankton dynamics in the seasonal and interannual variability of carbon in the subpolar North Atlantic – a modeling study

    Directory of Open Access Journals (Sweden)

    S. R. Signorini

    2012-05-01

    Full Text Available We developed an ecosystem/biogeochemical model system, which includes multiple phytoplankton functional groups and carbon cycle dynamics, and applied it to investigate physical-biological interactions in Icelandic waters. Satellite and in situ data were used to evaluate the model. Surface seasonal cycle amplitudes and biases of key parameters (DIC, TA, pCO2, air-sea CO2 flux, and nutrients are significantly improved when compared to surface observations by prescribing deep water values and trends, based on available data. The seasonality of the coccolithophore and "other phytoplankton" (diatoms and dinoflagellates blooms is in general agreement with satellite ocean color products. Nutrient supply, biomass and calcite concentrations are modulated by light and mixed layer depth seasonal cycles. Diatoms are the most abundant phytoplankton, with a large bloom in early spring and a secondary bloom in fall. The diatom bloom is followed by blooms of dinoflagellates and coccolithophores. The effect of biological changes on the seasonal variability of the surface ocean pCO2 is nearly twice the temperature effect, in agreement with previous studies. The inclusion of multiple phytoplankton functional groups in the model played a major role in the accurate representation of CO2 uptake by biology. For instance, at the peak of the bloom, the exclusion of coccolithophores causes an increase in alkalinity of up to 4 μmol kg−1 with a corresponding increase in DIC of up to 16 μmol kg−1. During the peak of the bloom in summer, the net effect of the absence of the coccolithophores bloom is an increase in pCO2 of more than 20 μatm and a reduction of atmospheric CO2 uptake of more than 6 mmol m−2 d−1. On average, the impact of coccolithophores is an increase of air-sea CO2 flux of about 27%. Considering the areal

  4. Seasonal development of phytoplankton populations in offshore Lake Michigan in 1975

    International Nuclear Information System (INIS)

    Parker, J.I.; Conway, H.L.; Yaguchi, E.M.

    1975-01-01

    Relationships between phytoplankton bloom sequences and environmental factors that may account for seasonal variations have not been thoroughly evaluated in Lake Michigan. We investigated the seasonal periodicity of phytoplankton in the offshore water from April to December, 1975. The seasonal distributions of phytoplankton biomass, chlorophyll a, and primary productivity per unit of lake surface area were measured at station 5. These measurements demonstrated a bimodal seasonal distribution, with maxima occurring in June and October. Previous investigators have shown that the seasonal periodicity was unimodal, with a summer maximum. Our observations demonstrated year to year variations in this abundance pattern

  5. Patterns and trends of macrobenthic abundance, biomass and production in the deep Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Renate Degen

    2015-08-01

    Full Text Available Little is known about the distribution and dynamics of macrobenthic communities of the deep Arctic Ocean. The few previous studies report low standing stocks and confirm a gradient with declining biomass from the slopes down to the basins, as commonly reported for deep-sea benthos. In this study, we investigated regional differences of faunal abundance and biomass, and made for the first time ever estimates of deep Arctic community production by using a multi-parameter artificial neural network model. The underlying data set combines data from recent field studies with published and unpublished data from the past 20 years, to analyse the influence of water depth, geographical latitude and sea-ice concentration on Arctic benthic communities. We were able to confirm the previously described negative relationship of macrofauna standing stock with water depth in the Arctic deep sea, while also detecting substantial regional differences. Furthermore, abundance, biomass and production decreased significantly with increasing sea-ice extent (towards higher latitudes down to values <200 ind m−2, <65 mg C m−2 and <73 mg C m−2 y−1, respectively. In contrast, stations under the seasonal ice zone regime showed much higher standing stock and production (up to 2500 mg C m−2 y−1, even at depths down to 3700 m. We conclude that particle flux is the key factor structuring benthic communities in the deep Arctic Ocean as it explains both the low values in the ice-covered Arctic basins and the higher values in the seasonal ice zone.

  6. Diversity in plant hydraulic traits explains seasonal and inter-annual variations of vegetation dynamics in seasonally dry tropical forests.

    Science.gov (United States)

    Xu, Xiangtao; Medvigy, David; Powers, Jennifer S; Becknell, Justin M; Guan, Kaiyu

    2016-10-01

    We assessed whether diversity in plant hydraulic traits can explain the observed diversity in plant responses to water stress in seasonally dry tropical forests (SDTFs). The Ecosystem Demography model 2 (ED2) was updated with a trait-driven mechanistic plant hydraulic module, as well as novel drought-phenology and plant water stress schemes. Four plant functional types were parameterized on the basis of meta-analysis of plant hydraulic traits. Simulations from both the original and the updated ED2 were evaluated against 5 yr of field data from a Costa Rican SDTF site and remote-sensing data over Central America. The updated model generated realistic plant hydraulic dynamics, such as leaf water potential and stem sap flow. Compared with the original ED2, predictions from our novel trait-driven model matched better with observed growth, phenology and their variations among functional groups. Most notably, the original ED2 produced unrealistically small leaf area index (LAI) and underestimated cumulative leaf litter. Both of these biases were corrected by the updated model. The updated model was also better able to simulate spatial patterns of LAI dynamics in Central America. Plant hydraulic traits are intercorrelated in SDTFs. Mechanistic incorporation of plant hydraulic traits is necessary for the simulation of spatiotemporal patterns of vegetation dynamics in SDTFs in vegetation models. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  7. Meridional Martian water abundance profiles during the 1988-1989 season

    International Nuclear Information System (INIS)

    Rizk, B.; Wells, W.K.; Hunten, D.M.; Stoker, C.R.; Freedman, R.S.; Roush, T.; Pollack, J.B.; Haberle, R.M.

    1991-01-01

    The Martian southern hemisphere atmospheric water vapor column abundance measurements reported agree with Viking Orbiter atmospheric water detectors during early southern spring and southern autumnal equinox; profiles obtained in southern mid- and late summer, however, indicate the presence of twice as much water both in the southern hemisphere and planetwide. This discrepancy is accounted for by the high optical depths created by two global dust storms during the Viking year, while the present observations were obtained in the case of the relatively dust-free atmosphere of the 1988-1989 opposition. 29 refs

  8. Dynamic ankle stability and ankle sprain occurrence in elite ball team athletes : a one season prospective study

    NARCIS (Netherlands)

    Chris Visscher; Anne Benjaminse; Koen A.P.M. Lemmink; Msc Henrike van der Does; Michel Brink; Joan Dallinga

    2013-01-01

    To compare the dynamic stability index (DSI) measured at baseline between elite ball team athletes with and without an ankle sprain during the season. Methods Forty-four elite male (age:22.5±3.6yr,height:193.7±8.0cm,mass:87.1±10.9kg) and eighteen female

  9. Seasonal dynamics of microbiological indices of water in the Ingulets and Berezovka rivers under different antropogenic burden

    OpenAIRE

    N. B. Esipova; V. А. Zhezherya

    2007-01-01

    The seasonal dynamics of microbiological indices of sanitary situation in Ingulets and Berezovka Rivers was analysed at spring-autumn period. The sanitary mapping of the rivers was done for the Alexandria area. In most cases maximal level of the rivers contamination by the lactose-positive E. coli index was found in August.

  10. Seasonal variation of assemblage and feeding guild structure of fish species in a boreal tidal basin

    Science.gov (United States)

    Kellnreitner, Florian; Pockberger, Moritz; Asmus, Harald

    2012-08-01

    Species composition, abundance, feeding relationships and guild structure of the fish assemblage in the Sylt-Rømø bight, a tidal basin in the northern Wadden Sea, were investigated to show seasonal differences and the importance of functional groups in this area. The tidal flats and in shallow subtidal areas were sampled using a beach seine and a bottom trawl net was used for deeper subtidal areas and tidal gullies. Species richness of fish was highest in summer where 26 species were caught, while the lowest richness was recorded in winter (17 species). Clear differences in species richness and abundance were found between shallow areas and deeper parts of the bight. Clupea harengus and Ammodytes tobianus were the most abundant species in deeper areas, while Pomatoschistus microps and Pomatoschistus minutus dominated shallower waters. Gut contents of 27 fish species were identified and the guild structure analyzed by UPGMA clustering of niche overlaps. Calanoid copepods (19.9%), Crangon crangon (18.2%) and mysid shrimps (8.4%) were the most abundant prey items of all fish species combined. Seven feeding guilds were present in the fall and winter, and eight and six in spring and summer, respectively. Fish feeding on calanoid copepods and C. crangon were present year round, whereas the occurrence of other guilds varied between seasons. Species composition of prey changed through seasons and, for some fish species, even the feeding mode itself varied with season. Most noticeable, 11 fish species changed guilds between seasons. We found a convergence in summer towards abundant prey items, whereas in winter diet overlap was lower. This is the first investigation of guild structure of almost all fish species present in a Wadden Sea area, and shows that consideration of seasonal differences is essential when determining feeding relationships of fish in temperate areas.

  11. Mechanisms driving postfire abundance of a generalist mammal

    Science.gov (United States)

    R. Zwolak; D. E. Pearson; Y. K. Ortega; E. E. Crone

    2012-01-01

    Changes in vertebrate abundance following disturbance are commonly attributed to shifts in food resources or predation pressure, but underlying mechanisms have rarely been tested. We examined four hypotheses for the commonly reported increase in abundance of deer mouse (Peromyscus maniculatus (Wagner, 1845)) following forest fires: source-sink dynamics, decreased...

  12. Spatial and seasonal patterns of European short-snouted seahorse ...

    African Journals Online (AJOL)

    North-East Atlantic), determining the spatial and seasonal abundance, population structure and physical appearance of European short-snouted seahorse Hippocampus hippocampus. Animals were surveyed off Gran Canaria Island in two ...

  13. Anopheles larval abundance and diversity in three rice agro-village complexes Mwea irrigation scheme, central Kenya

    Directory of Open Access Journals (Sweden)

    Mwangangi Joseph M

    2010-08-01

    Full Text Available Abstract Background The diversity and abundance of Anopheles larvae has significant influence on the resulting adult mosquito population and hence the dynamics of malaria transmission. Studies were conducted to examine larval habitat dynamics and ecological factors affecting survivorship of aquatic stages of malaria vectors in three agro-ecological settings in Mwea, Kenya. Methods Three villages were selected based on rice husbandry and water management practices. Aquatic habitats in the 3 villages representing planned rice cultivation (Mbui Njeru, unplanned rice cultivation (Kiamachiri and non-irrigated (Murinduko agro-ecosystems were sampled every 2 weeks to generate stage-specific estimates of mosquito larval densities, relative abundance and diversity. Records of distance to the nearest homestead, vegetation coverage, surface debris, turbidity, habitat stability, habitat type, rice growth stage, number of rice tillers and percent Azolla cover were taken for each habitat. Results Captures of early, late instars and pupae accounted for 78.2%, 10.9% and 10.8% of the total Anopheles immatures sampled (n = 29,252, respectively. There were significant differences in larval abundance between 3 agro-ecosystems. The village with 'planned' rice cultivation had relatively lower Anopheles larval densities compared to the villages where 'unplanned' or non-irrigated. Similarly, species composition and richness was higher in the two villages with either 'unplanned' or limited rice cultivation, an indication of the importance of land use patterns on diversity of larval habitat types. Rice fields and associated canals were the most productive habitat types while water pools and puddles were important for short periods during the rainy season. Multiple logistic regression analysis showed that presence of other invertebrates, percentage Azolla cover, distance to nearest homestead, depth and water turbidity were the best predictors for Anopheles mosquito larval

  14. Seasonality of Mansonia titillans during dam construction, Biritiba-Mirim, São Paulo State, Brazil

    OpenAIRE

    D'Avila,Frederico Alves; Gomes,Almério de Castro

    2013-01-01

    A two and a half year survey was conducted at a dam in southeastern Brazil. Shannon Traps were used for sampling. Kruskal-Wallis test showed little relation between rainfall and abundance. The data clearly show three abundance peaks, all of them in the end of the dry season, in consonance with the scarce literature existent. Although Kruskal-Wallis Test did not find a clear preference for the dry season, Pairwise Wilcoxon Rank Test revealed a significant difference between Fall and Spring sam...

  15. Seasonal dynamic of the occurrence of the gregarines infection of Harpalus rufipes (Coleoptera, Carabidae in agroecosystem

    Directory of Open Access Journals (Sweden)

    D. Y. Reshetnyak

    2015-08-01

    Full Text Available Relationships in the “parasite-host” system are closely interrelated and occur at all levels from the molecular to behavioral and population ones. There are two models of realization of these relations. The first case is when the parasites are uniformly distributed in the host population. High extensiveness of invasion is accompanied by its low intensity. The second case is when a part of host population is infected with parasites, but the negative impact is manifested to the maximum extent. Invasion of the ground beetle Harpalus rufipes (De Geer, 1774, dwelling in sweet corn agroecosystems located in the vicinity of Dnipropetrovsk near Doslidnoe village, by several gregarines species is investigated in this study. H. rufipes is an abundant, ubiquitous species, living in extremely wide range of terrestrial ecosystems, with especially high populations inhabiting anthropogenically transformed environments. H. rufipes has a wide range of feeding. This species is distributed in the Central and Eastern Europe, and introduced to North America. Gregarines were found in the intestines of 20 individuals of H. rufipes from 190 (10.5%: Gregarina ovata Dufour, 1828, G. steini Berndt, 1902, G. amarae (Hammerschmidt, 1839 Frantzius, 1848, Clitellocephalus ophoni (Tuzet and Ormieres, 1956 Clopton, 2002, Torogregarina sphinx Clopton, 1998, Gigaductus macrospora Filipponi, 1948 and G. elongatus (Moriggi, 1943 Filipponi, 1948. There is high level of infestation of C. ophoni and G. steini. At the same time, not more than three species of the gregarines were localized in the beetle body. Seasonal dynamic of occurrence of the gregarines is as follows. Maximal indices of occurrence are found at the end of August (22.2% and minimal ones at the end of June (4.8%. The highest total number of gregarines (383 ind. is recorded at the end of August, the lowest one is fixed at the beginning of September (33 ind.. Indices of gregarine species dominance are as follows

  16. Abundance and population structure of Plesionika narval (Fabricius, 1787 in the Northeastern Atlantic

    Directory of Open Access Journals (Sweden)

    R. Sousa

    2018-04-01

    Full Text Available Abstract Analysis of abundance and population structure of Plesionika narval was performed on data concerning 5,255 specimens obtained from 62 fishing sets carried out off the Madeira archipelago (Northeastern Atlantic between 2004 and 2008 in a depth range from 101 to 350 m. Abundance ranged from 0.01 to 19.74 specimens-per-trap and significant differences were found between seasons, probably as a result of an increment of population in the spring during the recruitment season. The analysis of size distribution revealed that the carapace length (CL ranged from 2.45 to 28.61 mm and that mean female size consistently exceeded that of males. Differences in mean CL were statistically significant between depth strata and seasons. Of the specimens sampled, 57.00% were males, 41.88% females and 1.42% undetermined. Sex ratio also differed significantly between seasons according to depth strata, consolidating the hypothesis of the existence of seasonal migrations related with the reproductive cycle of this species. Ovigerous females showed larger sizes and occurred all year around and remain in shallow waters in winter, summer and autumn and move to deeper waters in spring. The highest frequency of ovigerous females was recorded in summer, between 151 and 200 m deep supporting the hypothesis that spawning of this species occurs in shallow waters, especially in late summer.

  17. Post-1980 shifts in the sensitivity of boreal tree growth to North Atlantic Ocean dynamics and seasonal climate. Tree growth responses to North Atlantic Ocean dynamics

    Science.gov (United States)

    Ols, Clémentine; Trouet, Valerie; Girardin, Martin P.; Hofgaard, Annika; Bergeron, Yves; Drobyshev, Igor

    2018-06-01

    The mid-20th century changes in North Atlantic Ocean dynamics, e.g. slow-down of the Atlantic meridional overturning thermohaline circulation (AMOC), have been considered as early signs of tipping points in the Earth climate system. We hypothesized that these changes have significantly altered boreal forest growth dynamics in northeastern North America (NA) and northern Europe (NE), two areas geographically adjacent to the North Atlantic Ocean. To test our hypothesis, we investigated tree growth responses to seasonal large-scale oceanic and atmospheric indices (the AMOC, North Atlantic Oscillation (NAO), and Arctic Oscillation (AO)) and climate (temperature and precipitation) from 1950 onwards, both at the regional and local levels. We developed a network of 6876 black spruce (NA) and 14437 Norway spruce (NE) tree-ring width series, extracted from forest inventory databases. Analyses revealed post-1980 shifts from insignificant to significant tree growth responses to summer oceanic and atmospheric dynamics both in NA (negative responses to NAO and AO indices) and NE (positive response to NAO and AMOC indices). The strength and sign of these responses varied, however, through space with stronger responses in western and central boreal Quebec and in central and northern boreal Sweden, and across scales with stronger responses at the regional level than at the local level. Emerging post-1980 associations with North Atlantic Ocean dynamics synchronized with stronger tree growth responses to local seasonal climate, particularly to winter temperatures. Our results suggest that ongoing and future anomalies in oceanic and atmospheric dynamics may impact forest growth and carbon sequestration to a greater extent than previously thought. Cross-scale differences in responses to North Atlantic Ocean dynamics highlight complex interplays in the effects of local climate and ocean-atmosphere dynamics on tree growth processes and advocate for the use of different spatial scales in

  18. Seasonal dynamics of mosquito occurrence in the Lower Dyje River Basin at the Czech-Slovak-Austrian border

    Czech Academy of Sciences Publication Activity Database

    Šebesta, Oldřich; Gelbič, Ivan; Peško, Juraj

    2013-01-01

    Roč. 80, č. 1 (2013), s. 125-138 ISSN 1125-0003 R&D Projects: GA MŠk 2B08003 Institutional research plan: CEZ:AV0Z50070508 Institutional support: RVO:68081766 ; RVO:60077344 Keywords : Czech Republic * South Moravia * Aedes vexans * Culex modestus * seasonal dynamics Subject RIV: EG - Zoology Impact factor: 0.865, year: 2013

  19. Seasonal dynamics of tetracycline resistance gene transport in the Sumas River agricultural watershed of British Columbia, Canada.

    Science.gov (United States)

    Keen, Patricia L; Knapp, Charles W; Hall, Kenneth J; Graham, David W

    2018-07-01

    Environmental transport of contaminants that can influence the development of antibiotic resistance in bacteria is an important concern in the management of ecological and human health risks. Agricultural regions are locales where practices linked to food crop and livestock production can introduce contaminants that could alter the selective pressures for the development of antibiotic resistance in microbiota. This is important in regions where the use of animal manure or municipal biosolids as waste and/or fertilizer could influence selection for antibiotic resistance in pathogenic bacterial species. To investigate the environmental transport of contaminants that could lead to the development of antibiotic resistance in bacteria, a watershed with one of the highest levels of intensity of agricultural activity in Canada was studied; the Sumas River located 60 km east of Vancouver, British Columbia. This two-year assessment monitored four selected tetracycline resistance genes (tet(O), tet(M), tet(Q), tet(W)) and water quality parameters (temperature, specific conductivity, turbidity, suspended solids, nitrate, phosphate and chloride) at eight locations across the watershed. The tetracycline resistance genes (Tc r ) abundances in the Sumas River network ranged between 1.47 × 10 2 and 3.49 × 10 4  copies/mL and ranged between 2.3 and 6.9 copies/mL in a control stream (located far from agricultural activities) for the duration of the study. Further, Tc r abundances that were detected in the wet season months ranged between 1.3 × 10 3 and 2.29 × 10 4  copies/mL compared with dry season months (ranging between 0.6 and 31.2 copies/mL). Highest transport rates between 1.67 × 10 11 and 1.16 × 10 12  copies/s were observed in November 2005 during periods of high rainfall. The study showed that elevated concentrations of antibiotic resistance genes in the order of 10 2 -10 4  copies/mL can move through stream networks in an

  20. Hydrology and density feedbacks control the ecology of intermediate hosts of schistosomiasis across habitats in seasonal climates.

    Science.gov (United States)

    Perez-Saez, Javier; Mande, Theophile; Ceperley, Natalie; Bertuzzo, Enrico; Mari, Lorenzo; Gatto, Marino; Rinaldo, Andrea

    2016-06-07

    We report about field and theoretical studies on the ecology of the aquatic snails (Bulinus spp. and Biomphalaria pfeifferi) that serve as obligate intermediate hosts in the complex life cycle of the parasites causing human schistosomiasis. Snail abundance fosters disease transmission, and thus the dynamics of snail populations are critically important for schistosomiasis modeling and control. Here, we single out hydrological drivers and density dependence (or lack of it) of ecological growth rates of local snail populations by contrasting novel ecological and environmental data with various models of host demography. Specifically, we study various natural and man-made habitats across Burkina Faso's highly seasonal climatic zones. Demographic models are ranked through formal model comparison and structural risk minimization. The latter allows us to evaluate the suitability of population models while clarifying the relevant covariates that explain empirical observations of snail abundance under the actual climatic forcings experienced by the various field sites. Our results link quantitatively hydrological drivers to distinct population dynamics through specific density feedbacks, and show that statistical methods based on model averaging provide reliable snail abundance projections. The consistency of our ranking results suggests the use of ad hoc models of snail demography depending on habitat type (e.g., natural vs. man-made) and hydrological characteristics (e.g., ephemeral vs. permanent). Implications for risk mapping and space-time allocation of control measures in schistosomiasis-endemic contexts are discussed.

  1. Synchrony, compensatory dynamics, and the functional trait basis of phenological diversity in a tropical dry forest tree community: effects of rainfall seasonality

    Science.gov (United States)

    Lasky, Jesse R.; Uriarte, María; Muscarella, Robert

    2016-11-01

    Interspecific variation in phenology is a key axis of functional diversity, potentially mediating how communities respond to climate change. The diverse drivers of phenology act across multiple temporal scales. For example, abiotic constraints favor synchronous reproduction (positive covariance among species), while biotic interactions can favor synchrony or compensatory dynamics (negative covariance). We used wavelet analyses to examine phenology of community flower and seed production for 45 tree species across multiple temporal scales in a tropical dry forest in Puerto Rico with marked rainfall seasonality. We asked three questions: (1) do species exhibit synchronous or compensatory temporal dynamics in reproduction, (2) do interspecific differences in phenology reflect variable responses to rainfall, and (3) is interspecific variation in phenology and response to a major drought associated with functional traits that mediate responses to moisture? Community-level flowering was synchronized at seasonal scales (˜5-6 mo) and at short scales (˜1 mo, following rainfall). However, seed rain exhibited significant compensatory dynamics at intraseasonal scales (˜3 mo), suggesting interspecific variation in temporal niches. Species with large leaves (associated with sensitivity to water deficit) peaked in reproduction synchronously with the peak of seasonal rainfall (˜5 mo scale). By contrast, species with high wood specific gravity (associated with drought resistance) tended to flower in drier periods. Flowering of tall species and those with large leaves was most tightly linked to intraseasonal (˜2 mo scale) rainfall fluctuations. Although the 2015 drought dramatically reduced community-wide reproduction, functional traits were not associated with the magnitude of species-specific declines. Our results suggest opposing drivers of synchronous versus compensatory dynamics at different temporal scales. Phenology associations with functional traits indicated that

  2. Sympatric occurrence and population dynamics of Scylla spp. in equatorial climate: Effects of rainfall, temperature and lunar phase

    Science.gov (United States)

    Fazhan, Hanafiah; Waiho, Khor; Darin Azri, Mohammad Farhan; Al-Hafiz, Ismail; Norfaizza, Wan Ibrahim Wan; Megat, Fadhlul Hazmi; Jasmani, Safiah; Ma, Hongyu; Ikhwanuddin, Mhd

    2017-11-01

    Mud crabs (Scylla spp.) are known to exist sympatrically in the wild. However, information on their population dynamics and the influence of climate parameters and lunar phase, especially along the equatorial region, are limited. Four sampling stations representing three seas (the Strait of Malacca, South China Sea and Sulu Sea) along the equator were selected. Mud crabs were collected using baited traps during spring tides from April 2012 to July 2013. All three Scylla species, S. olivacea, S. tranquebarica and S. paramamosain live in sympatry in the three seas. Scylla olivacea is the most prevalent species in the Strait of Malacca and South China Sea, whereas S. paramamosain dominates the Sulu Sea. The total crab abundance was not affected by rainfall or temperature. The abundance of S. tranquebarica in Strait of Malacca was negatively correlated with temperature and positively correlated with rainfall whereas the abundance of S. paramamosain positively correlated with temperature only at South China Sea. Scylla tranquebarica was the largest in terms of body size and it showed interchanging abundance trends with S. paramamosain. The average body size of S. paramamosain did not differ significantly with that of S. tranquebarica and S. olivacea. This decrease is most likely attributed to overfishing. Significant seasonal fluctuations in mean carapace width were detected in S. tranquebarica and S. paramamosain, but not in S. olivacea. The monthly sex ratio of all three species occasionally fluctuates above the equal sex ratio value. Lunar phase did not affect species abundance, but males and females were significantly heavier during full moon. These findings serve as a baseline of seasonal variation in crab population dynamics that are useful in mud crab fisheries and resource management.

  3. Seasonal Variation on Microbial Community and Methane Production during Anaerobic Digestion of Cattle Manure in Brazil.

    Science.gov (United States)

    Resende, Juliana Alves; Godon, Jean-Jacques; Bonnafous, Anaïs; Arcuri, Pedro Braga; Silva, Vânia Lúcia; Otenio, Marcelo Henrique; Diniz, Cláudio Galuppo

    2016-04-01

    Anaerobic digestion is an alternative method for the treatment of animal manure and wastewater. The anaerobic bioconversion of biomass requires a multi-step biological process, including microorganisms with distinct roles. The diversity and composition of microbial structure in pilot-scale anaerobic digestion operating at ambient temperature in Brazil were studied. Influence of the seasonal and temporal patterns on bacterial and archaeal communities were assessed by studying the variations in density, dynamic and diversity and structure. The average daily biogas produced in the summer and winter months was 18.7 and 16 L day(-1), respectively, and there was no difference in the average methane yield. Quantitative PCR analysis revealed that no differences in abundances and dynamics were found for bacterial communities and the total number of Archaea in different seasons. Analysis of bacterial clone libraries revealed a predominance of Firmicutes (54.5 %/summer and 46.7 %/winter) and Bacteroidetes (31.4 %/summer and 44.4 %/winter). Within the Archaea, the phylum Euryarchaeota was predominant in both digesters. Phylogenetic distribution showed changes in percentage between the phyla identified, but no alterations were recorded in the quality and amount of produced methane or community dynamics. The results may suggest that redundancy of microbial groups may have occurred, pointing to a more complex microbial community in the ecosystem related to this ambient temperature system.

  4. Biological soil crusts exhibit a dynamic response to seasonal rain and release from grazing with implications for soil stability

    Science.gov (United States)

    Jimenez, Aguilar A.; Huber-Sannwald, E.; Belnap, J.; Smart, D.R.; Arredondo, Moreno J.T.

    2009-01-01

    In Northern Mexico, long-term grazing has substantially degraded semiarid landscapes. In semiarid systems, ecological and hydrological processes are strongly coupled by patchy plant distribution and biological soil crust (BSC) cover in plant-free interspaces. In this study, we asked: 1) how responsive are BSC cover/composition to a drying/wetting cycle and two-year grazing removal, and 2) what are the implications for soil erosion? We characterized BSC morphotypes and their influence on soil stability under grazed/non-grazed conditions during a dry and wet season. Light- and dark-colored cyanobacteria were dominant at the plant tussock and community level. Cover changes in these two groups differed after a rainy season and in response to grazing removal. Lichens with continuous thalli were more vulnerable to grazing than those with semi-continuous/discontinuous thalli after the dry season. Microsites around tussocks facilitated BSC colonization compared to interspaces. Lichen and cyanobacteria morphotypes differentially enhanced resistance to soil erosion; consequently, surface soil stability depends on the spatial distribution of BSC morphotypes, suggesting soil stability may be as dynamic as changes in the type of BSC cover. Longer-term spatially detailed studies are necessary to elicit spatiotemporal dynamics of BSC communities and their functional role in biotically and abiotically variable environments. ?? 2009 Elsevier Ltd.

  5. Impact of seasonal forcing on reactive ecological systems.

    Science.gov (United States)

    Vesipa, Riccardo; Ridolfi, Luca

    2017-04-21

    Our focus is on the short-term dynamics of reactive ecological systems which are stable in the long term. In these systems, perturbations can exhibit significant transient amplifications before asymptotically decaying. This peculiar behavior has attracted increasing attention. However, reactive systems have so far been investigated assuming that external environmental characteristics remain constant, although environmental conditions (e.g., temperature, moisture, water availability, etc.) can undergo substantial changes due to seasonal cycles. In order to fill this gap, we propose applying the adjoint non-modal analysis to study the impact of seasonal variations of environmental conditions on reactive systems. This tool allows the transient dynamics of a perturbation affecting non-autonomous ecological systems to be described. To show the potential of this approach, a seasonally forced prey-predator model with a Holling II type functional response is studied as an exemplifying case. We demonstrate that seasonalities can greatly affect the transient dynamics of the system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. [Abundance and body size of Menippe mercenaria (Crustacea: Brachyura), in artificial refuges in Quintana Roo, Mexico].

    Science.gov (United States)

    Cervantes-Martínez, A; Ramírez-González, A

    2001-01-01

    In Florida and Cuba the stone crab Menippe mercenaria (Say, 1818) is under strong fishing-pressure; nevertheless in the Mexican Caribbean it is considered as sub-utilized and poorly known resource. Artificial shelters ("condominios cubanos") were used to study relative abundance, age structure, claw length-carapace amplitude relation, and population in three seasons and four sectors at Bahía Ascension, Quintana Roo, Mexico. The abundance varied according to the sector and sampling season: population was higher in the south and during the north wind ("Nortes") season (January to March). The carapace amplitude was directly proportional to claw length (r2 = 0.83, 0.97 and 0.89; p < 0.05 in females, males and total, respectively). The results suggest that specimens with 37.5 and 67.5 mm of carapace amplitude are the most limited regarding refuge availability in the Bay.

  7. Influence of temporal variation and host condition on helminth abundance in the lizard Tropidurus hispidus from north-eastern Brazil.

    Science.gov (United States)

    Filho, J A Araujo; Brito, S V; Lima, V F; Pereira, A M A; Mesquita, D O; Albuquerque, R L; Almeida, W O

    2017-05-01

    Ecological characteristics and environmental variation influence both host species composition and parasite abundance. Abiotic factors such as rainfall and temperature can improve parasite development and increase its reproduction rate. The comparison of these assemblages between different environments may give us a more refined analysis of how environment affects the variation of helminth parasite abundance. The aim of the present study was to evaluate how temporal variation, host size, sex and reproduction affect helminth abundance in the Tropidurus hispidus lizard in Caatinga, Restinga and Atlantic Forest environments. Overall, larger-sized lizards showed higher helminth abundance. We found a monthly variation in the helminth species abundance in all studied areas. In the Caatinga area, monoxenic and heteroxenic parasites were related to the rainy season and to the reproductive period of lizards. In Restinga, monoxenic and heteroxenic helminth species were more abundant during the driest months. In the Atlantic Forest, the rainy and host reproductive season occurred continuously throughout the year, so parasite abundance was relatively constant. Nevertheless, heteroxenic species were more abundant in this area. The present results showed that the temporal variation, body size, sex, reproductive period and habitat type influence the abundance and composition of helminth species in T. hispidus.

  8. Seasonal variations in suspended-sediment dynamics in the tidal reach of an estuarine tributary

    Science.gov (United States)

    Downing-Kunz, Maureen A.; Schoellhamer, David H.

    2013-01-01

    Quantifying sediment supply from estuarine tributaries is an important component of developing a sediment budget, and common techniques for estimating supply are based on gages located above tidal influence. However, tidal interactions near tributary mouths can affect the magnitude and direction of sediment supply to the open waters of the estuary. We investigated suspended-sediment dynamics in the tidal reach of Corte Madera Creek, an estuarine tributary of San Francisco Bay, using moored acoustic and optical instruments. Flux of both water and suspended-sediment were calculated from observed water velocity and turbidity for two periods in each of wet and dry seasons during 2010. During wet periods, net suspended-sediment flux was seaward; tidally filtered flux was dominated by the advective component. In contrast, during dry periods, net flux was landward; tidally filtered flux was dominated by the dispersive component. The mechanisms generating this landward flux varied; during summer we attributed wind–wave resuspension in the estuary and subsequent transport on flood tides, whereas during autumn we attributed increased spring tide flood velocity magnitude leading to local resuspension. A quadrant analysis similar to that employed in turbulence studies was developed to summarize flux time series by quantifying the relative importance of sediment transport events. These events are categorized by the direction of velocity (flood vs. ebb) and the magnitude of concentration relative to tidally averaged conditions (relatively turbid vs. relatively clear). During wet periods, suspended-sediment flux was greatest in magnitude during relatively turbid ebbs, whereas during dry periods it was greatest in magnitude during relatively turbid floods. A conceptual model was developed to generalize seasonal differences in suspended-sediment dynamics; model application to this study demonstrated the importance of few, relatively large events on net suspended-sediment flux

  9. Global sampling of the seasonal changes in vegetation biophysical properties and associated carbon flux dynamics: using the synergy of information captured by spectral time series

    Science.gov (United States)

    Campbell, P. K. E.; Huemmrich, K. F.; Middleton, E.; Voorhis, S.; Landis, D.

    2016-12-01

    Spatial heterogeneity and seasonal dynamics in vegetation function contribute significantly to the uncertainties in regional and global CO2 budgets. High spectral resolution imaging spectroscopy ( 10 nm, 400-2500 nm) provides an efficient tool for synoptic evaluation of the factors significantly affecting the ability of the vegetation to sequester carbon and to reflect radiation, due to changes in vegetation chemical and structural composition. EO-1 Hyperion has collected more than 15 years of repeated observations for vegetation studies, and currently Hyperion time series are available for study of vegetation carbon dynamics at a number of FLUX sites. This study presents results from the analysis of EO-1 Hyperion and FLUX seasonal composites for a range of ecosystems across the globe. Spectral differences and seasonal trends were evaluated for each vegetation type and specific phenology. Evaluating the relationships between CO2 flux parameters (e.g., Net ecosystem production - NEP; Gross Ecosystem Exchange - GEE, CO2 flux, μmol m-2 s-1) and spectral parameters for these very different ecosystems, high correlations were established to parameters associated with canopy water and chlorophyll content for deciduous, and photosynthetic function for conifers. Imaging spectrometry provided high spatial resolution maps of CO2 fluxes absorbed by vegetation, and was efficient in tracing seasonal flux dynamics. This study will present examples for key ecosystem tipes to demonstrate the ability of imaging spectrometry and EO-1 Hyperion to map and compare CO2 flux dynamics across the globe.

  10. Volume 90, Issue1 (February 2005)Articles in the Current Issue:Original PaperSeasonal Dynamics of Benthic and Planktonic Algae in a Nutrient-Rich Lowland River (Spree, Germany)

    Science.gov (United States)

    Werner, Petra; Köhler, Jan

    2005-02-01

    We studied chlorophyll a (chl. a), biovolume and species composition of benthic algae and phytoplankton in the eutrophic lower River Spree in 1996. The chl. a concentration was estimated as 3.5 (2.7-4.5) μg/cm2 for epipsammon, 9.4 (7.4-11.9) μg/cm2 for epipelon and 6.7 (5.7-7.8) μg/cm2 for the epilithon (median and 95% C. L.). The mean total biomass of benthic algae was significantly higher (6.0 μg chl. a/cm2) than the areal chl. a content of the pelagic zone (1.6 μg chl. a/cm2). Although certain phytoplankton taxa were abundant in the periphyton, benthic taxa generally dominated the assemblages. Seasonal dynamics of benthic algae were probably controlled by light and nitrate supply (sand), discharge fluctuations (sand, mud) and invertebrate grazing (stones). This paper shows the importance of benthic algae even in phytoplankton-rich lowland rivers with sandy or muddy sediments.

  11. Modelling the effects of seasonality and socioeconomic impact on the transmission of Rift Valley fever virus

    Science.gov (United States)

    Xiao, Yanyu; Beier, John C.; Cantrell, Robert Stephen; Cosner, Chris; DeAngelis, Donald L.; Ruan, Shigui

    2015-01-01

    Rift Valley fever (RVF) is an important mosquito-borne viral zoonosis in Africa and the Middle East that causes human deaths and significant economic losses due to huge incidences of death and abortion among infected livestock. Outbreaks of RVF are sporadic and associated with both seasonal and socioeconomic effects. Here we propose an almost periodic three-patch model to investigate the transmission dynamics of RVF virus (RVFV) among ruminants with spatial movements. Our findings indicate that, in Northeastern Africa, human activities, including those associated with the Eid al Adha feast, along with a combination of climatic factors such as rainfall level and hydrological variations, contribute to the transmission and dispersal of the disease pathogen. Moreover, sporadic outbreaks may occur when the two events occur together: 1) abundant livestock are recruited into areas at risk from RVF due to the demand for the religious festival and 2) abundant numbers of mosquitoes emerge. These two factors have been shown to have impacts on the severity of RVF outbreaks. Our numerical results present the transmission dynamics of the disease pathogen over both short and long periods of time, particularly during the festival time. Further, we investigate the impact on patterns of disease outbreaks in each patch brought by festival- and seasonal-driven factors, such as the number of livestock imported daily, the animal transportation speed from patch to patch, and the death rate induced by ceremonial sacrifices. In addition, our simulations show that when the time for festival preparation starts earlier than usual, the risk of massive disease outbreaks rises, particularly in patch 3 (the place where the religious ceremony will be held).

  12. Breeding phenology of birds: mechanisms underlying seasonal declines in the risk of nest predation.

    Directory of Open Access Journals (Sweden)

    Kathi L Borgmann

    Full Text Available Seasonal declines in avian clutch size are well documented, but seasonal variation in other reproductive parameters has received less attention. For example, the probability of complete brood mortality typically explains much of the variation in reproductive success and often varies seasonally, but we know little about the underlying cause of that variation. This oversight is surprising given that nest predation influences many other life-history traits and varies throughout the breeding season in many songbirds. To determine the underlying causes of observed seasonal decreases in risk of nest predation, we modeled nest predation of Dusky Flycatchers (Empidonax oberholseri in northern California as a function of foliage phenology, energetic demand, developmental stage, conspecific nest density, food availability for nest predators, and nest predator abundance. Seasonal variation in the risk of nest predation was not associated with seasonal changes in energetic demand, conspecific nest density, or predator abundance. Instead, seasonal variation in the risk of nest predation was associated with foliage density (early, but not late, in the breeding season and seasonal changes in food available to nest predators. Supplemental food provided to nest predators resulted in a numerical response by nest predators, increasing the risk of nest predation at nests that were near supplemental feeders. Our results suggest that seasonal changes in foliage density and factors associated with changes in food availability for nest predators are important drivers of temporal patterns in risk of avian nest predation.

  13. Breeding phenology of birds: mechanisms underlying seasonal declines in the risk of nest predation.

    Science.gov (United States)

    Borgmann, Kathi L; Conway, Courtney J; Morrison, Michael L

    2013-01-01

    Seasonal declines in avian clutch size are well documented, but seasonal variation in other reproductive parameters has received less attention. For example, the probability of complete brood mortality typically explains much of the variation in reproductive success and often varies seasonally, but we know little about the underlying cause of that variation. This oversight is surprising given that nest predation influences many other life-history traits and varies throughout the breeding season in many songbirds. To determine the underlying causes of observed seasonal decreases in risk of nest predation, we modeled nest predation of Dusky Flycatchers (Empidonax oberholseri) in northern California as a function of foliage phenology, energetic demand, developmental stage, conspecific nest density, food availability for nest predators, and nest predator abundance. Seasonal variation in the risk of nest predation was not associated with seasonal changes in energetic demand, conspecific nest density, or predator abundance. Instead, seasonal variation in the risk of nest predation was associated with foliage density (early, but not late, in the breeding season) and seasonal changes in food available to nest predators. Supplemental food provided to nest predators resulted in a numerical response by nest predators, increasing the risk of nest predation at nests that were near supplemental feeders. Our results suggest that seasonal changes in foliage density and factors associated with changes in food availability for nest predators are important drivers of temporal patterns in risk of avian nest predation.

  14. Seasonal Dynamics of Sublittoral Meiobenthos in Relation to Phytoplankton Sedimentation in the Baltic Sea

    Science.gov (United States)

    Ólafsson, E.; Elmgren, R.

    1997-08-01

    Meiobenthic metazoans (40-500) μm were sampled monthly at a 37 m deep station in the north-western Baltic Sea proper. Nematodes dominated the meiofauna, ranging from 67% of total abundance in February to 91% in September. Harpacticoid copepods were the second most common group, ranging from 2% in September to 15% in February. Total meiofauna shell-free dry weight biomass was lowest in winter (0·9 mg 10 cm -2in January), and increased rapidly following the spring bloom, to high values in May-July (peak 1·7 mg 10 cm -2in July). As an annual average, ostracods contributed most to biomass, 38%, while nematodes and harpacticoids made up 24 and 15%, respectively. Only nematodes were common below 2 cm depth in the sediment, and few nematodes penetrated below 4 cm. Of Wieser's morphologically based nematode feeding groups, epistrate feeders dominated the surface sediment, and non-selective deposit feeders dominated the deeper layer in May. Total nematode abundance was significantly different among dates, with lowest numbers in winter and spring (October-April), and almost doubled within about 2 months after the spring phytoplankton bloom in March. There was a significant increase in selective deposit feeders and epistrate feeders after the spring bloom. Harpacticoid copepods were almost all of two species, Pseudobradyasp. and Microarthridion littorale, both of which differed significantly in abundance among months, and displayed continuous reproduction throughout the year, with a peak in pairs in precopula in winter for Pseudobradyasp. and in ovigerous females in M. littoraleafter the spring bloom. Pseudobradyawas significantly more numerous in winter than in other seasons. Microarthridion littoralehad its highest abundance from July to October. Three species of ostracods were common throughout the year and all differed significantly in numbers among months. Turbellaria, Kinorhyncha were found in lowest numbers during winter and peaked in summer. The peak of newly

  15. Seasonal Synchronization of a Simple Stochastic Dynamical Model Capturing El Niño Diversity

    Science.gov (United States)

    Thual, S.; Majda, A.; Chen, N.

    2017-12-01

    The El Niño-Southern Oscillation (ENSO) has significant impact on global climate and seasonal prediction. Recently, a simple ENSO model was developed that automatically captures the ENSO diversity and intermittency in nature, where state-dependent stochastic wind bursts and nonlinear advection of sea surface temperature (SST) are coupled to simple ocean-atmosphere processes that are otherwise deterministic, linear and stable. In the present article, it is further shown that the model can reproduce qualitatively the ENSO synchronization (or phase-locking) to the seasonal cycle in nature. This goal is achieved by incorporating a cloud radiative feedback that is derived naturally from the model's atmosphere dynamics with no ad-hoc assumptions and accounts in simple fashion for the marked seasonal variations of convective activity and cloud cover in the eastern Pacific. In particular, the weak convective response to SSTs in boreal fall favors the eastern Pacific warming that triggers El Niño events while the increased convective activity and cloud cover during the following spring contributes to the shutdown of those events by blocking incoming shortwave solar radiations. In addition to simulating the ENSO diversity with realistic non-Gaussian statistics in different Niño regions, both the eastern Pacific moderate and super El Niño, the central Pacific El Niño as well as La Niña show a realistic chronology with a tendency to peak in boreal winter as well as decreased predictability in spring consistent with the persistence barrier in nature. The incorporation of other possible seasonal feedbacks in the model is also documented for completeness.

  16. Seasonal changes of fructans in dimorphic roots of Ichthyothere terminalis (Spreng.) Blake (Asteraceae) growing in Cerrado.

    Science.gov (United States)

    de Almeida, Lorrayne Veloso; Ferri, Pedro Henrique; Seraphin, José Carlos; de Moraes, Moemy Gomes

    2017-11-15

    Cerrado is a floristically rich savanna in Brazil, whose vegetation consists of a physiognomic mosaic, influenced by rainfall seasonality. In the dry season rainfall is substantially lower and reduces soil water supply, mainly for herbs and subshrubs. Climatic seasonal variations may well define phenological shifts and induce fluctuations of plant reserve pools. Some Cerrado native species have thickened underground organs that bear buds and store reserves, as adaptive features to enable plant survival following environmental stresses. Asteraceae species accumulate fructans in storage organs, which are not only reserve, but also protecting compounds against the effects of cold and drought. Ichthyothere terminalis is one Asteraceae species abundant in cerrado rupestre, with underground organs consisting of thickened orthogravitropic and diagravitropic roots. The objectives of this study were to analyze how abiotic environmental factors and plant phenology influence fructan dynamics in field grown plants, and verify if fructan metabolism differs in both root types for one year. I. terminalis accumulates inulin-type fructans in 10-40% of the dry mass in both root types. Fructan dynamics have similar patterns described for other Asteraceae species, exhibiting a proportional increase of polysaccharides with the senescence of the aerial organs. Multivariate analyzes showed that, as rainfall decreased, environmental factors had a stronger influence on metabolite levels than phenological shifts in both root types. Only slight differences were found in fructan dynamics between orthogravitropic and diagravitropic roots, suggesting they may have similar fructan metabolism regulation. However, these small differences may reflect distinct microclimatic conditions in both root types and also represent the influence of sink strength. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. The RAVE-on Catalog of Stellar Atmospheric Parameters and Chemical Abundances for Chemo-dynamic Studies in the Gaia Era

    Energy Technology Data Exchange (ETDEWEB)

    Casey, Andrew R.; Hawkins, Keith; Koposov, Sergey; Sanders, Jason; Gilmore, Gerry [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Hogg, David W. [Simons Center for Data Analysis, 160 Fifth Avenue, 7th Floor, New York, NY 10010 (United States); Ness, Melissa; Rix, Hans-Walter [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Kordopatis, Georges; Kunder, Andrea; Steinmetz, Matthias; Enke, Harry [Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Zwitter, Tomaž; Matijevič, Gal [University of Ljubljana, Faculty of Mathematics and Physics, Jadranska 19, 1000 Ljubljana (Slovenia); Freeman, Kenneth C.; Casagrande, Luca [Research School of Astronomy and Astrophysics, Mount Stromlo Observatory, The Australian National University, ACT 2611 (Australia); Seabroke, George [Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, RH5 6NT (United Kingdom); Bienaymé, Olivier [Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l’Université, F-67000 Strasbourg (France); Bland-Hawthorn, Joss [Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia); Gibson, Brad K. [E.A. Milne Centre for Astrophysics, University of Hull, Hull, HU6 7RX (United Kingdom); and others

    2017-05-01

    The orbits, atmospheric parameters, chemical abundances, and ages of individual stars in the Milky Way provide the most comprehensive illustration of galaxy formation available. The Tycho- Gaia Astrometric Solution (TGAS) will deliver astrometric parameters for the largest ever sample of Milky Way stars, though its full potential cannot be realized without the addition of complementary spectroscopy. Among existing spectroscopic surveys, the RAdial Velocity Experiment (RAVE) has the largest overlap with TGAS (≳200,000 stars). We present a data-driven re-analysis of 520,781 RAVE spectra using The Cannon . For red giants, we build our model using high-fidelity APOGEE stellar parameters and abundances for stars that overlap with RAVE. For main sequence and sub-giant stars, our model uses stellar parameters from the K2/EPIC . We derive and validate effective temperature T {sub eff}, surface gravity log g , and chemical abundances of up to seven elements (O, Mg, Al, Si, Ca, Fe, and Ni). We report a total of 1,685,851 elemental abundances with a typical precision of 0.07 dex, a substantial improvement over previous RAVE data releases. The synthesis of RAVE-on and TGAS is the most powerful data set for chemo-dynamic analyses of the Milky Way ever produced.

  18. Seasonal variation of fatty acids from drip water in Heshang Cave, central China

    International Nuclear Information System (INIS)

    Li Xiuli; Wang Canfa; Huang Junhua; Hu Chaoyong; Xie Shucheng

    2011-01-01

    Research highlights: → A 2-year monitoring to investigate the seasonal variation of fatty acids in cave drip water. → Microbes are the dominant source for fatty acids in drip water. → The relative abundance of mono-unsaturated responds negatively with external air temperature. - Abstract: In order to investigate how lipids in cave water respond to seasonal climate change, drip water samples were collected from 2006 to 2008 in Heshang Cave, central China for fatty acid analysis. These lipids are abundant in the drip water. Their compositions are dominated by lower-molecular-weight nC16:0, nC18:0 and nC14:0 acids, together with mono-unsaturated nC18:1, nC16:1 and nC14:1. Analysis of one water sample revealed marked differences between the dissolved and particulate fractions. The dissolved fraction contains total fatty acids one order of magnitude higher than that of the particulate fraction. The distributional patterns of the fatty acids suggest that microbes living in the overlying soils and/or groundwater system contribute most fatty acids to the drip water. This 2-a monitoring experiment reveals that the abundance of mono-unsaturated fatty acids relative to the saturated homologues (nC16:1/nC16:0 and nC18:1/nC18:0) relate inversely to the changes of synchronous external air temperature. Higher values occur under cold conditions (winter/spring), while lower values appear in warm intervals (summer). Further studies are needed to elucidate the dynamic processes by which the external temperature affects fatty acids in drip water and to confirm the potential application of fatty acid ratios such as nC16:1/nC16:0 and nC18:1/nC18:0 in paleotemperature reconstructions.

  19. Abundance, food habits, and breeding season of exotic T ilapia zillii and native O reochromis niloticus L. fish species in Lake Zwai , Ethiopia

    Directory of Open Access Journals (Sweden)

    Padanillay C. Prabu

    2008-05-01

    Full Text Available Relative abundance, diet and breeding season overlap in the reproduction of exotic Tilapia zillii and native Oreochromis niloticus in Lake Zwai were studied from samples collected over 12 months. Younger fish of both species collected were also evaluated for food composition.Food items from stomachs of both species were collected and analysed using the frequency of occurrence method. In terms of number, T. zillii dominated O. niloticus at the sampling sites. In both species, macrophytes, detritus, blue green algae, diatoms, green algae, Ceratium, Euglena,and Phacus constituted foods of plant origin, whereas chironomid larvae, Copepoda, Cladocera,Rotifera, Nematoda, fish eggs, and fish scales constituted foods of animal origin. Foods of the latter type such as Ephemeroptera and mollusks were also noted in the diet of adult T. zillii.Despite the extensive overlap in food habits of the two species, however, the food items were found in the diet of the species with different average percentage frequencies of occurrence. The level of gonad maturation and gonadosomatic index (GSI values showed that in Lake Zwai breeding was year-round for both T. zillii and O. niloticus, with a peak during April-September and February-August respectively, indicating extended breeding season overlap in reproduction. The two species were always found together in the catches from the sampling sites, which indicated some niche overlap between them.

  20. Seasonal monitoring of deep-sea megabenthos in Barkley Canyon cold seep by internet operated vehicle (IOV.

    Directory of Open Access Journals (Sweden)

    Carolina Doya

    Full Text Available Knowledge of the processes shaping deep-sea benthic communities at seasonal scales in cold-seep environments is incomplete. Cold seeps within highly dynamic regions, such as submarine canyons, where variable current regimes may occur, are particularly understudied. Novel Internet Operated Vehicles (IOVs, such as tracked crawlers, provide new techniques for investigating these ecosystems over prolonged periods. In this study a benthic crawler connected to the NEPTUNE cabled infrastructure operated by Ocean Networks Canada was used to monitor community changes across 60 m2 of a cold-seep area of the Barkley Canyon, North East Pacific, at ~890 m depth within an Oxygen Minimum Zone (OMZ. Short video-transects were run at 4-h intervals during the first week of successive calendar months, over a 14 month period (February 14th 2013 to April 14th 2014. Within each recorded transect video megafauna abundances were computed and changes in environmental conditions concurrently measured. The responses of fauna to environmental conditions as a proxy of seasonality were assessed through analysis of abundances in a total of 438 video-transects (over 92 h of total footage. 7698 fauna individuals from 6 phyla (Cnidaria, Ctenophora, Arthropoda, Echinodermata, Mollusca, and Chordata were logged and patterns in abundances of the 7 most abundant taxa (i.e. rockfish Sebastidae, sablefish Anoplopoma fimbria, hagfish Eptatretus stoutii, buccinids (Buccinoidea, undefined small crabs, ctenophores Bolinopsis infundibulum, and Scyphomedusa Poralia rufescens were identified. Patterns in the reproductive behaviour of the grooved tanner crab (Chionnecetes tanneri were also indicated. Temporal variations in biodiversity and abundance in megabenthic fauna was significantly influenced by variabilities in flow velocity flow direction (up or down canyon, dissolved oxygen concentration and month of study. Also reported here for the first time are transient mass aggregations of

  1. Early-stage changes in natural (13)C and (15)N abundance and nutrient dynamics during different litter decomposition.

    Science.gov (United States)

    Gautam, Mukesh Kumar; Lee, Kwang-Sik; Song, Byeong-Yeol; Lee, Dongho; Bong, Yeon-Sik

    2016-05-01

    Decomposition, nutrient, and isotopic (δ(13)C and δ(15)N) dynamics during 1 year were studied for leaf and twig litters of Pinus densiflora, Castanea crenata, Erigeron annuus, and Miscanthus sinensis growing on a highly weathered soil with constrained nutrient supply using litterbags in a cool temperate region of South Korea. Decay constant (k/year) ranged from 0.58 to 1.29/year, and mass loss ranged from 22.36 to 58.43 % among litter types. The results demonstrate that mass loss and nutrient dynamics of decomposing litter were influenced by the seasonality of mineralization and immobilization processes. In general, most nutrients exhibited alternate phases of rapid mineralization followed by gradual immobilization, except K, which was released throughout the field incubation. At the end of study, among all the nutrients only N and P showed net immobilization. Mobility of different nutrients from decomposing litter as the percentage of initial litter nutrient concentration was in the order of K > Mg > Ca > N ≈ P. The δ(13)C (0.32-6.70 ‰) and δ(15)N (0.74-3.90 ‰) values of residual litters showed nonlinear increase and decrease, respectively compared to initial isotopic values during decomposition. Litter of different functional types and chemical quality converged toward a conservative nutrient use strategy through mechanisms of slow decomposition and slow nutrient mobilization. Our results indicate that litter quality and season, are the most important regulators of litter decomposition in these forests. The results revealed significant relationships between litter decomposition rates and N, C:N ratio and P, and seasonality (temperature). These results and the convergence of different litters towards conservative nutrient use in these nutrient constrained ecosystems imply optimization of litter management because litter removal can have cascading effects on litter decomposition and nutrient availability in these systems.

  2. Temporal dynamics influenced by global change: bee community phenology in urban, agricultural, and natural landscapes.

    Science.gov (United States)

    Leong, Misha; Ponisio, Lauren C; Kremen, Claire; Thorp, Robbin W; Roderick, George K

    2016-03-01

    Urbanization and agricultural intensification of landscapes are important drivers of global change, which in turn have direct impacts on local ecological communities leading to shifts in species distributions and interactions. Here, we illustrate how human-altered landscapes, with novel ornamental and crop plant communities, result not only in changes to local community diversity of floral-dependent species, but also in shifts in seasonal abundance of bee pollinators. Three years of data on the spatio-temporal distributions of 91 bee species show that seasonal patterns of abundance and species richness in human-altered landscapes varied significantly less compared to natural habitats in which floral resources are relatively scarce in the dry summer months. These findings demonstrate that anthropogenic environmental changes in urban and agricultural systems, here mediated through changes in plant resources and water inputs, can alter the temporal dynamics of pollinators that depend on them. Changes in phenology of interactions can be an important, though frequently overlooked, mechanism of global change. © 2015 John Wiley & Sons Ltd.

  3. Environmental parameters influence on the dynamics of total and pathogenic Vibrio parahaemolyticus densities in Crassostrea virginica harvested from Mexico’s Gulf coast

    International Nuclear Information System (INIS)

    López-Hernández, Karla M.; Pardío-Sedas, Violeta T.; Lizárraga-Partida, Leonardo; Williams, José de J.; Martínez-Herrera, David; Flores-Primo, Argel; Uscanga-Serrano, Roxana; Rendón-Castro, Karla

    2015-01-01

    Highlights: • V. parahaemolyticus densities in oysters were isolated in spring and winter seasons. • Pathogenic genes abundances varied with environmental parameters seasonal changes. • Water temperature modulated V. parahaemolyticus abundance during reduced salinities. • V. parahaemolyticus with potentially pathogenic genes raises important health issues. - Abstract: The influence of environmental parameters on the total and pathogenic Vibrio parahaemolyticus seasonal densities in American oysters (Crassostrea virginica) was evaluated for 1 year. Harvesting site A yielded the highest mean densities of V. parahaemolyticus tlh+, tdh+/trh−, tdh−/trh+ and tdh+/trh+ during spring season at 2.57, 1.74, 0.36, and −0.40 log 10 MPN/g, respectively, and tdh+/orf8+ during winter season (0.90 log 10 MPN/g). V. parahaemolyticus tlh+ densities were associated to salinity (R 2 = 0.372, P < 0.022), tdh+/trh+ to turbidity (R 2 = 0.597, P < 0.035), and orf8+ to temperature, salinity, and pH (R 2 = 0.964, P < 0.001). The exposure to salinity and temperature conditions during winter and spring seasons regulated the dynamics of V. parahaemolyticus harboring potentially pathogenic genotypes within the oyster. The adaptive response of V. parahaemolyticus to seasonal environmental changes may lead to an increase in survival and virulence, threatening the seafood safety and increasing the risk of illness

  4. Evaluation of surface water dynamics for water-food security in seasonal wetlands, north-central Namibia

    Directory of Open Access Journals (Sweden)

    T. Hiyama

    2014-09-01

    Full Text Available Agricultural use of wetlands is important for food security in various regions. However, land-use changes in wetland areas could alter the water cycle and the ecosystem. To conserve the water environments of wetlands, care is needed when introducing new cropping systems. This study is the first attempt to evaluate the water dynamics in the case of the introduction of rice-millet mixed-cropping systems to the Cuvelai system seasonal wetlands (CSSWs in north-central Namibia. We first investigated seasonal changes in surface water coverage by using satellite remote sensing data. We also assessed the effect of the introduction of rice-millet mixed-cropping systems on evapotranspiration in the CSSWs region. For the former investigation, we used MODIS and AMSR-E satellite remote sensing data. These data showed that at the beginning of the wet season, surface water appears from the southern (lower part and then expands to the northern (higher part of the CSSWs. For the latter investigation, we used data obtained by the classical Bowen ratio-energy balance (BREB method at an experimental field site established in September 2012 on the Ogongo campus, University of Namibia. This analysis showed the importance of water and vegetation conditions when introducing mixed-cropping to the region.

  5. Calibration and combination of dynamical seasonal forecasts to enhance the value of predicted probabilities for managing risk

    Science.gov (United States)

    Dutton, John A.; James, Richard P.; Ross, Jeremy D.

    2013-06-01

    Seasonal probability forecasts produced with numerical dynamics on supercomputers offer great potential value in managing risk and opportunity created by seasonal variability. The skill and reliability of contemporary forecast systems can be increased by calibration methods that use the historical performance of the forecast system to improve the ongoing real-time forecasts. Two calibration methods are applied to seasonal surface temperature forecasts of the US National Weather Service, the European Centre for Medium Range Weather Forecasts, and to a World Climate Service multi-model ensemble created by combining those two forecasts with Bayesian methods. As expected, the multi-model is somewhat more skillful and more reliable than the original models taken alone. The potential value of the multimodel in decision making is illustrated with the profits achieved in simulated trading of a weather derivative. In addition to examining the seasonal models, the article demonstrates that calibrated probability forecasts of weekly average temperatures for leads of 2-4 weeks are also skillful and reliable. The conversion of ensemble forecasts into probability distributions of impact variables is illustrated with degree days derived from the temperature forecasts. Some issues related to loss of stationarity owing to long-term warming are considered. The main conclusion of the article is that properly calibrated probabilistic forecasts possess sufficient skill and reliability to contribute to effective decisions in government and business activities that are sensitive to intraseasonal and seasonal climate variability.

  6. Retrieval of water vapor column abundance and aerosol properties from ChemCam passive sky spectroscopy

    Science.gov (United States)

    McConnochie, Timothy H.; Smith, Michael D.; Wolff, Michael J.; Bender, Steve; Lemmon, Mark; Wiens, Roger C.; Maurice, Sylvestre; Gasnault, Olivier; Lasue, Jeremie; Meslin, Pierre-Yves; Harri, Ari-Matti; Genzer, Maria; Kemppinen, Osku; Martínez, Germán M.; DeFlores, Lauren; Blaney, Diana; Johnson, Jeffrey R.; Bell, James F.

    2018-06-01

    We derive water vapor column abundances and aerosol properties from Mars Science Laboratory (MSL) ChemCam passive mode observations of scattered sky light. This paper covers the methodology and initial results for water vapor and also provides preliminary results for aerosols. The data set presented here includes the results of 113 observations spanning from Mars Year 31 Ls = 291° (March 30, 2013) to Mars Year 33 Ls= 127° (March 24, 2016). Each ChemCam passive sky observation acquires spectra at two different elevation angles. We fit these spectra with a discrete-ordinates multiple scattering radiative transfer model, using the correlated-k approximation for gas absorption bands. The retrieval proceeds by first fitting the continuum of the ratio of the two elevation angles to solve for aerosol properties, and then fitting the continuum-removed ratio to solve for gas abundances. The final step of the retrieval makes use of the observed CO2 absorptions and the known CO2 abundance to correct the retrieved water vapor abundance for the effects of the vertical distribution of scattering aerosols and to derive an aerosol scale height parameter. Our water vapor results give water vapor column abundance with a precision of ±0.6 precipitable microns and systematic errors no larger than ±0.3 precipitable microns, assuming uniform vertical mixing. The ChemCam-retrieved water abundances show, with only a few exceptions, the same seasonal behavior and the same timing of seasonal minima and maxima as the TES, CRISM, and REMS-H data sets that we compare them to. However ChemCam-retrieved water abundances are generally lower than zonal and regional scale from-orbit water vapor data, while at the same time being significantly larger than pre-dawn REMS-H abundances. Pending further analysis of REMS-H volume mixing ratio uncertainties, the differences between ChemCam and REMS-H pre-dawn mixing ratios appear to be much too large to be explained by large scale circulations and thus

  7. Dynamical explanation for the high water abundance detected in Orion

    International Nuclear Information System (INIS)

    Elitzur, M.

    1979-01-01

    Shock wave chemistry is suggested as the likely explanation for the high water abundance which has been recently detected in Orion by Phyllips et al. The existence of such a shock and its inferred properties are in agreement with other observations of Orion such as the broad velocity feature and H 2 vibration emission. Shock waves are proposed as the likely explanation for high water abundances observed in other sources such as the strong H 2 O masers

  8. The timing of birds' breeding seasons : the Perrins hypothesis revisited especially for migrants

    NARCIS (Netherlands)

    Drent, Rudolf H.

    2006-01-01

    Perrins (1970) galvanized thinking on the timing of birds' breeding seasons by pointing out that most individuals laid too late for the offspring to profit fully from the seasonal peak of food abundance, and suggested that the proximate cause was a shortage of food for the female when forming the

  9. Dynamics of size-fractionated phytoplankton biomass in a monsoonal estuary: Patterns and drivers for seasonal and spatial variability

    Science.gov (United States)

    Rajaneesh, K. M.; Mitbavkar, Smita; Anil, Arga Chandrashekar

    2018-07-01

    Phytoplankton size-fractionated biomass is an important determinant of the type of food web functioning in aquatic ecosystems. Knowledge about the effect of seasonal salinity gradient on the size-fractionated biomass dynamics is still lacking, especially in tropical estuaries experiencing monsoon. The phytoplankton size-fractionated chlorophyll a biomass (>3 μm and 3 μm size-fraction was the major contributor to the total phytoplankton chlorophyll a biomass with the ephemeral dominance of biomass concentration of both size-fractions showed signs of recovery with increasing salinity downstream towards the end of the monsoon season. In contrast, the chlorophyll a biomass response was size-dependent during the non-monsoon seasons with the sporadic dominance (>50%) of biomass during high water temperature episodes from downstream to middle estuary during pre-monsoon and at low salinity and high nutrient conditions upstream during post-monsoon. These conditions also influenced the picophytoplankton community structure with picoeukaryotes dominating during the pre-monsoon, phycoerythrin containing Synechococcus during the monsoon and phycocyanin containing Synechococcus during the post-monsoon. This study highlights switching over of dominance in size-fractionated phytoplankton chlorophyll a biomass at intra, inter-seasonal and spatial scales which will likely govern the estuarine trophodynamics.

  10. History, distribution, and seasonal abundance of the Least Tern Sternula antillarum (Aves: Charadriiformes: Sternidae in Brazil

    Directory of Open Access Journals (Sweden)

    Caio J. Carlos

    2013-04-01

    Full Text Available We review existing data on the distribution of the Least Tern, Sternula antillarum along the Brazilian coast, based on the literature and museum specimens, and present results of a year-long study (October 2008 to September 2009 on the seasonal abundance of this species on a large tidal flat area, Cajuais Bank, in the State of Ceará, north-eastern Brazil. We evaluate whether the observed variation in the abundance of terns is due to the occurrence of an undocumented breeding colony, or alternatively, whether it results from an influx of migrants from the Northern Hemisphere. The recovery of historical data revealed that all literature references on the distribution of birds in the Americas, published up to the late 1990s include Brazil in the non-breeding range of the Least Tern. This inclusion is based on a few, old (late 19th and early 20th centuries museum specimens, all of which have been collected on the northern and north-eastern coasts of this country'. From the late 1980s, birds continued to be occasionally recorded along the coastline, running from the State of Amapá (01°N up to the State of Bahia (10°S, with records of single individuals in south-eastern and southern Brazil. An alleged record from Rocas Atoll, 260 km off the Brazilian mainland, might tentatively refer to the Old World Little Tern S. albifrons. At Cajuais Bank, Least Terns occurred from October 2008 to April 2009, and in September 2009. The highest numbers (> 800 individuals were recorded in January-February (Southern Hemisphere's summer. The species was observed in rather small numbers (< 30 in March-April (early-mid Southern Hemisphere fall and in September (early Southern Hemisphere spring, being absent from the area in May-August (Southern Hemisphere's fall and winter. In October-December 2008 (Southern Hemisphere's spring, and September 2009 (early Southern Hemisphere's summer, no birds were in breeding plumage. In January, about 32% of the birds were in

  11. Leaf ontogeny dominates the seasonal exchange of volatile organic compounds (VOC) in a SRC-poplar plantation during an entire growing season

    Science.gov (United States)

    Brilli, Federico; Gioli, Beniamino; Fares, Silvano; Zenone, Terenzio; Zona, Donatella; Gielen, Bert; Loreto, Francesco; Janssens, Ivan; Ceulemans, Reinhart

    2015-04-01

    The declining cost of many renewable energy technologies and changes in the prices of fossil fuels have recently encouraged governments policies to subsidize the use of biomass as a sustainable source of energy. Deciduous poplars (Populus spp.) trees are often selected for biomass production in short rotation coppiced (SRC) for their high CO2 photosynthetic assimilation rates and their capacity to develop dense canopies with high values of leaf area index (LAI). So far, observations and projections of seasonal variations of many VOC fluxes has been limited to strong isoprenoids emitting evergreen ecosystems such tropical and Mediterranean forests as well as Citrus and oil palm plantation, all having constant values of LAI. We run a long-term field campaign where the exchange of VOC, together with CO2 and water vapor was monitored during an entire growing season (June - November, 2012) above a SRC-based poplar plantation. Our results confirmed that isoprene and methanol were the most abundant fluxes emitted, accounting for more than 90% of the total carbon released in form of VOC. However, Northern climates characterized by fresh summertime temperatures and recurring precipitations favored poplar growth while inhibiting the development of isoprene emission that resulted in only 0.7% of the net ecosystem carbon exchange (NEE). Besides, measurements of a multitude of VOC fluxes by PTR-TOF-MS showed bi-directional exchange of oxygenated-VOC (OVOC) such as: formaldehyde, acetaldehyde, acetone, isoprene oxidation products (iox, namely MVK, MAC and MEK) as well as ethanol and formic acid. The application of Self Organizing Maps to visualize the relationship between the full time-series of many VOC fluxes and the observed seasonal variations of environmental, physiological and structural parameters proved the most abundant isoprene ad methanol fluxes to occur mainly on the hottest days under mid-high light intensities when also NEE and evapotraspiration reached the highest

  12. Seasonal dynamics of Proteocephalus sagittus in the stone loach Barbatula barbatula from the Haná River, Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Jarkovský, J.; Koubková, B.; Scholz, Tomáš; Prokeš, Miroslav; Baruš, Vlastimil

    2004-01-01

    Roč. 78, č. 3 (2004), s. 225-229 ISSN 0022-149X R&D Projects: GA ČR GA524/01/1314; GA AV ČR IAA6093104 Institutional research plan: CEZ:AV0Z6022909; CEZ:AV0Z6093917 Keywords : Cestoda * Proteocephalus sagittus * seasonal dynamics Subject RIV: EH - Ecology, Behaviour Impact factor: 0.676, year: 2004

  13. Seasonal climate manipulations have only minor effects on litter decomposition rates and N dynamics but strong effects on litter P dynamics of sub-arctic bog species.

    Science.gov (United States)

    Aerts, R; Callaghan, T V; Dorrepaal, E; van Logtestijn, R S P; Cornelissen, J H C

    2012-11-01

    Litter decomposition and nutrient mineralization in high-latitude peatlands are constrained by low temperatures. So far, little is known about the effects of seasonal components of climate change (higher spring and summer temperatures, more snow which leads to higher winter soil temperatures) on these processes. In a 4-year field experiment, we manipulated these seasonal components in a sub-arctic bog and studied the effects on the decomposition and N and P dynamics of leaf litter of Calamagrostis lapponica, Betula nana, and Rubus chamaemorus, incubated both in a common ambient environment and in the treatment plots. Mass loss in the controls increased in the order Calamagrostis Litter chemistry showed within each incubation environment only a few and species-specific responses. Compared to the interspecific differences, they resulted in only moderate climate treatment effects on mass loss and these differed among seasons and species. Neither N nor P mineralization in the litter were affected by the incubation environment. Remarkably, for all species, no net N mineralization had occurred in any of the treatments during 4 years. Species differed in P-release patterns, and summer warming strongly stimulated P release for all species. Thus, moderate changes in summer temperatures and/or winter snow addition have limited effects on litter decomposition rates and N dynamics, but summer warming does stimulate litter P release. As a result, N-limitation of plant growth in this sub-arctic bog may be sustained or even further promoted.

  14. Seasonal growth dynamics of the seagrass Zostera caulescens on the eastern coast of Korea

    Science.gov (United States)

    Kim, Jong-Hyeob; Park, Sang Hoon; Kim, Young Kyun; Kim, Seung Hyeon; Park, Jung-Im; Lee, Kun-Seop

    2014-12-01

    Zostera caulescens is an endemic seagrass species in Northeastern Asia. Estimated distributional area of this species is approximately 1-5 km2 on the coasts of Korea. Because Z. caulescens has a very limited distribution, the growth dynamics of Z. caulescens is little known in the coastal waters of Korea. In the present study, we investigated the growth dynamics of Z. caulescens in relation to coincident measurements of environmental factors, such as underwater irradiance, water temperature, and nutrient availability. The study was conducted on a monotypic meadow of Z. caulescens in Uljin on the eastern coast of Korea from September 2011 to September 2012. Shoot density and biomass of Z. caulescens showed distinct seasonal variations, and exhibited strong correlations with water temperature suggesting that the seasonal growth of this species was regulated by water temperature. Shoot density and biomass rapidly decreased during the high water temperature period in summer, and thus Z. caulescens is considered a cold water adapted species like other temperate seagrass species on coasts of Korea. Biomass of photosynthetic leaf tissues on reproductive shoots was approximately 4 times higher than that on vegetative shoots. The height of reproductive shoots ranged from 1.2 m in February 2012 to 3.2 m in August 2012, whereas the height of vegetative shoots was usually less than 1.0 m. Leaf tissues on reproductive shoots probably received much more light for photosynthesis than those on vegetative shoots. Thus, reproductive shoots may play an important role in total production of Z. caulescens.

  15. Edaphic Conditions Regulate Denitrification Directly and Indirectly by Altering Denitrifier Abundance in Wetlands along the Han River, China.

    Science.gov (United States)

    Xiong, Ziqian; Guo, Laodong; Zhang, Quanfa; Liu, Guihua; Liu, Wenzhi

    2017-05-16

    Riparian wetlands play a critical role in retaining nitrogen (N) from upland runoff and improving river water quality, mainly through biological processes such as soil denitrification. However, the relative contribution of abiotic and biotic factors to riparian denitrification capacity remains elusive. Here we report the spatiotemporal dynamics of potential and unamended soil denitrification rates in 20 wetlands along the Han River, an important water source in central China. We also quantified the abundance of soil denitrifying microorganisms using nirK and nirS genes. Results showed that soil denitrification rates were significantly different between riparian and reservoir shoreline wetlands, but not between mountain and lowland wetlands. In addition, soil denitrification rates showed strong seasonality, with higher values in August (summer) and April (spring) but lower values in January (winter). The potential and unamended denitrification rates were positively correlated with edaphic conditions (moisture and carbon concentration), denitrifier abundance, and plant species richness. Path analysis further revealed that edaphic conditions could regulate denitrification rates both directly and indirectly through their effects on denitrifier abundance. Our findings highlight that not only environmental factors, but also biotic factors including denitrifying microorganisms and standing vegetation, play an important role in regulating denitrification rate and N removal capacity in riparian wetlands.

  16. Global assessment of seasonal potential distribution of Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae)

    International Nuclear Information System (INIS)

    Szyniszewska, Anna M.; Tatem, Andrew J.

    2015-01-01

    The Mediterranean fruit fly (Medfly) is one of the world's most economically damaging pests. It displays highly seasonal population dynamics, and the environmental conditions suitable for its abundance are not constant throughout the year in most places. An extensive literature search was performed to obtain the most comprehensive data on the historical and contemporary spatio-temporal occurrence of the pest globally. The database constructed contained 2328 unique geo-located entries on Medfly detection sites from 43 countries and nearly 500 unique localities, as well as information on hosts, life stages and capture method. Of these, 125 localities had information on the month when Medfly was recorded and these data were complemented by additional material found in comprehensive databases available online. Records from 1980 until present were used for medfly environmental niche modeling. Maximum Entropy Algorithm (MaxEnt) and a set of seasonally varying environmental covariates were used to predict the fundamental niche of the Medfly on a global scale. Three seasonal maps were also produced: January-April, May- August and September-December. Models performed significantly better than random achieving high accuracy scores, indicating a good discrimination of suitable versus unsuitable areas for the presence of the species. (author)

  17. Effects of thermal vapor diffusion on seasonal dynamics of water in the unsaturated zone

    Science.gov (United States)

    Milly, Paul C.D.

    1996-01-01

    The response of water in the unsaturated zone to seasonal changes of temperature (T) is determined analytically using the theory of nonisothermal water transport in porous media, and the solutions are tested against field observations of moisture potential and bomb fallout isotopic (36Cl and 3H) concentrations. Seasonally varying land surface temperatures and the resulting subsurface temperature gradients induce thermal vapor diffusion. The annual mean vertical temperature gradient is close to zero; however, the annual mean thermal vapor flux is downward, because the temperature‐dependent vapor diffusion coefficient is larger, on average, during downward diffusion (occurring at high T) than during upward diffusion (low T). The annual mean thermal vapor flux is shown to decay exponentially with depth; the depth (about 1 m) at which it decays to e−1of its surface value is one half of the corresponding decay depth for the amplitude of seasonal temperature changes. This depth‐dependent annual mean flux is effectively a source of water, which must be balanced by a flux divergence associated with other transport processes. In a relatively humid environment the liquid fluxes greatly exceed the thermal vapor fluxes, so such a balance is readily achieved without measurable effect on the dynamics of water in the unsaturated zone. However, if the mean vertical water flux through the unsaturated zone is very small (theoretical prediction is supported by long‐term field measurements in the Chihuahuan Desert. The analysis also makes predictions, confirmed by the field observations, regarding the seasonal variations of matric potential at a given depth. The conceptual model of unsaturated zone water transport developed here implies the possibility of near‐surface trapping of any aqueous constituent introduced at the surface.

  18. Soil and Foliar Arthropod Abundance and Diversity in Five Cropping Systems in the Coastal Plains of North Carolina.

    Science.gov (United States)

    Adams, Paul R; Orr, David B; Arellano, Consuelo; Cardoza, Yasmin J

    2017-08-01

    Soil and foliar arthropod populations in agricultural settings respond to environmental disturbance and degradation, impacting functional biodiversity in agroecosystems. The objective of this study was to evaluate system level management effects on soil and foliar arthropod abundance and diversity in corn and soybean. Our field experiment was a completely randomized block design with three replicates for five farming systems which included: Conventional clean till, conventional long rotation, conventional no-till, organic clean till, and organic reduced till. Soil arthropod sampling was accomplished by pitfall trapping. Foliar arthropod sampling was accomplished by scouting corn and sweep netting soybean. Overall soil arthropod abundance was significantly impacted by cropping in corn and for foliar arthropods in soybeans. Conventional long rotation and organic clean till systems were highest in overall soil arthropod abundance for corn while organic reduced till systems exceeded all other systems for overall foliar arthropod abundance in soybeans. Foliar arthropod abundance over sampling weeks was significantly impacted by cropping system and is suspected to be the result of in-field weed and cover crop cultivation practices. This suggests that the sum of management practices within production systems impact soil and foliar arthropod abundance and diversity and that the effects of these systems are dynamic over the cropping season. Changes in diversity may be explained by weed management practices as sources of disturbance and reduced arthropod refuges via weed reduction. Furthermore, our results suggest agricultural systems lower in management intensity, whether due to organic practices or reduced levels of disturbance, foster greater arthropod diversity. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Population dynamics of Glossina fuscipes fuscipes on Buvuma Island, Lake Victoria, Uganda

    International Nuclear Information System (INIS)

    Ogwal, L.M.; Kangwagye, T.N.

    1990-01-01

    A survey made of Buvuma Island to establish the incidence, distribution and population dynamics of tsetse flies showed that Glossina fuscipes fuscipes Newstead was the most abundant species. This species occurred in the southeastern, western and northern parts of the island. Although the fly is both riverine and peridomestic in its habits, the survey revealed that its population was concentrated mainly within a distance of about 2 km from the lake shores around houses, in banana plantations, at forest edges and roadsides, in fishing villages and ports of call, on grazing grounds and at water collection points. Studies of the population dynamics revealed seasonal variations in the abundance of the species, with a peak during the main dry season, i.e. in the months of January and February. The breeding peak was reached during the minor rainy season. Trap catches were highest in fishing villages and ports of call, followed in decreasing order by catches at forest edge and roadside locations, at water collection points, around houses, in banana plantations and on grazing grounds. It appears that the fishing villages and ports of call were possibly the most suitable breeding grounds. The efficiency of the traps was reflected in the fact that G. f. fuscipes populations were reduced by up to 95% in Tome and 90% in the Bulopa-Walwanda and Lwenyanja villages. Many puparia were also found on the sandy beaches around fishing villages and ports of call. There was evidence of fly movement between the islands and the mainland, indicating that, although geographically isolated, Buvuma Island is not isolated from the mainland in terms of tsetse fly movement. (author). 21 refs, 5 figs, 1 tab

  20. Agricultural crops and soil treatment impacts on the daily and seasonal dynamics of CO2 fluxes in the field agroecosystems at the Central region of Russia

    Science.gov (United States)

    Mazirov, Ilya; Vasenev, Ivan; Meshalkina, Joulia; Yaroslavtsev, Alexis; Berezovskiy, Egor; Djancharov, Turmusbek

    2015-04-01

    The problem of greenhouse gases' concentrations increasing becomes more and more important due to global changes issues. The main component of greenhouse gases is carbon dioxide. The researches focused on its fluxes in natural and anthropogenic modified landscapes can help in this problem solution. Our research has been done with support of the RF Government grants # 11.G34.31.0079 and # 14.120.14.4266 and of FP7 Grant # 603542 LUC4C in the representative for Central Region of Russia field agroecosystems at the Precision Farming Experimental Field of Russian Timiryazev State Agrarian University with cultivated sod podzoluvisols, barley and oats - vetch grass mix (Moscow station of the RusFluxNet). The daily and seasonal dynamics of the carbon dioxide have been studied at the ecosystem level by the Eddy covariance method (2 stations) and at the soil level by the exposition chamber method (40 chambers) with mobile infra red gas analyzer (Li-Cor 820). The primary Eddy covariance monitoring data on CO2 fluxes and water vapor have been processed by EddyPro software developed by LI-COR Biosciences. According to the two-year monitoring data the daily CO2 sink during the vegetation season is usually approximately two times higher than its emission at night. Seasonal CO2 fluxes comparative stabilization has been fixed in case the plants height around 10-12 cm and it usually persist until the wax ripeness phase. There is strong dependence between the soil CO2 emission and the air temperature with the correlation coefficient 0.86 in average (due to strong input of the soil thin top functional subhorizon), but it drops essentially at the end of the season - till 0.38. The soil moisture impact on CO2 fluxes dynamics was less, with negative correlation at the end of the season. High daily dynamics of CO2 fluxes determines the protocol requirements for seasonal soil monitoring investigation with less limitation at the end of the season. The accumulated monitoring data will be

  1. Phytoplankton community characteristics of the icebound season ...

    African Journals Online (AJOL)

    The taxonomic structure and spatial variability of phytoplankton abundance in the icebound season was obtained from the Zhalong Wetland. A total of 109 taxa were identified in all samples, 92 taxa occurring in at least two samples or the percentages over 1% in at least one sample were utilized in further study. The algal ...

  2. Seasonal dynamics and effects of nitrogen supply rate on nitrogen and carbohydrate reserves in cutting-derived Salix viminalis plants

    Science.gov (United States)

    Lars Bollmark; Lisa Sennerby-Forsse; Tom Ericsson

    1999-01-01

    Nurient storage is an important aspect of resprouting potential and production of Salix viminalis L., a pioneer species used for biomas production in weden. Seasonal dynamics of nitrogen (N), protien, soluble arbohydrates, starches, and lipids were studied in roots, cutting, stems, and leaves during a full growth cycle induced by varying photoperiod...

  3. Effects of winter marsh burning on abundance and nesting activity of Louisiana seaside sparrows in the Gulf Coast Chenier Plain

    Science.gov (United States)

    Gabrey, S.W.; Afton, A.D.

    2000-01-01

    Louisiana Seaside Sparrows (Ammodramus maritimus fisheri) breed and winter exclusively in brackish and saline marshes along the northern Gulf of Mexico. Many Gulf Coast marshes, particularly in the Chenier Plain of southwestern Louisiana and southeastern Texas, are burned intentionally in fall or winter as part of waterfowl management programs. Fire reportedly has negatively affected two Seaside Sparrow subspecies (A. m. nigrescens and A. m. mirabilis) in Florida, but there is no published information regarding effects of fire on A. m. fisheri. We compared abundance of territorial male Louisiana Seaside Sparrows, number of nesting activity indicators, and vegetation structure in paired burned and unburned plots in Chenier Plain marshes in southwestern Louisiana during the 1996 breeding season (April-July) before experimental winter burns (January 1997) and again during two breeding seasons post-burn (1997-1998). We found that abundance of male sparrows decreased in burned plots during the first breeding season post-burn, but was higher than that of unburned plots during the second breeding season post-burn. Indicators of nesting activity showed a similar but non-significant pattern in response to burning. Sparrow abundance and nesting activity seemingly are linked to dead vegetation cover, which was lower in burned plots during the first breeding season post-burn, but did not differ from that in unburned plots during the second breeding season post-burn. We recommend that marsh management plans in the Gulf Coast Chenier Plain integrate waterfowl and Seaside Sparrow management by maintaining a mosaic of burned and unburned marshes and allowing vegetation to recover for at least two growing seasons before reburning a marsh.

  4. Seasonality of community structure and carbon flow in Narragansett Bay sediments

    International Nuclear Information System (INIS)

    Rudnick, D.T.

    1984-01-01

    Seasonal patterns of benthic community dynamics and the pathways of detrital decomposition in Narragansett Bay were examined. Benthic meiofauna and macrofauna exhibited a pronounced seasonality, with peak abundances in the late spring and minima in the late summer. This pattern was most pronounced for surface dwelling fauna, particularly harpacticoid copepods. These results were attributed to the seasonality of detrital inputs to the sediment and the fate of these inputs. A six month study in which 14 C-sodium bicarbonate was added to a large (13 m 3 ) microcosm enabled the author to observe pathways of carbon flow. Half of the labeled organic carbon that was deposited on the sediment during the winter and spring was found in the sediment in July. At least 20 gC/m 2 had accumulated since December. Within the sediment, the existence of two discrete food webs was distinguished by measurement of faunal specific activity. Surface fauna, dominated by the meiofauna, exclusively assimilate fresh (labeled) organics, while subsurface fauna (meiofauna and macrofauna) predominantly assimilated older, non-labeled organics for the duration of the study. Only the subsurface food web had access to the storage of buried detritus. While there was a surplus of detritus for both food webs during the winter and spring, the authors expect that benthic respiration rates exceed organic deposition rates during the summer. Detrital storage may be critical for the survival of the fauna through the summer

  5. Co-existence of Anaerobic Ammonium Oxidation Bacteria and Denitrifying Anaerobic Methane Oxidation Bacteria in Sewage Sludge: Community Diversity and Seasonal Dynamics

    DEFF Research Database (Denmark)

    Xu, Sai; Lu, Wenjing; Mustafa, Muhammad Farooq

    2017-01-01

    Anaerobic ammonium oxidation (ANAMMOX) and denitrifying anaerobic methane oxidation (DAMO) have been recently discovered as relevant processes in the carbon and nitrogen cycles of wastewater treatment plants. In this study, the seasonal dynamics of ANAMMOX and DAMO bacterial community structures......, and an unknown cluster was primarily detected in autumn and winter. Similar patterns of seasonal variation in the community structure of DAMO bacteria were also observed. Group B was the dominant in spring and summer, whereas in autumn and winter, group A and group B presented almost the same proportion...

  6. Dynamics of the Water Circulations in the Southern South China Sea and Its Seasonal Transports.

    Science.gov (United States)

    Daryabor, Farshid; Ooi, See Hai; Samah, Azizan Abu; Akbari, Abolghasem

    2016-01-01

    A three-dimensional Regional Ocean Modeling System is used to study the seasonal water circulations and transports of the Southern South China Sea. The simulated seasonal water circulations and estimated transports show consistency with observations, e.g., satellite altimeter data set and re-analysis data of the Simple Ocean Data Assimilation. It is found that the seasonal water circulations are mainly driven by the monsoonal wind stress and influenced by the water outflow/inflow and associated currents of the entire South China Sea. The intrusion of the strong current along the East Coast of Peninsular Malaysia and the eddies at different depths in all seasons are due to the conservation of the potential vorticity as the depth increases. Results show that the water circulation patterns in the northern part of the East Coast of Peninsular Malaysia are generally dominated by the geostrophic currents while those in the southern areas are due solely to the wind stress because of negligible Coriolis force there. This study clearly shows that individual surface freshwater flux (evaporation minus precipitation) controls the sea salinity balance in the Southern South China Sea thermohaline circulations. Analysis of climatological data from a high resolution Regional Ocean Modeling System reveals that the complex bathymetry is important not only for water exchange through the Southern South China Sea but also in regulating various transports across the main passages in the Southern South China Sea, namely the Sunda Shelf and the Strait of Malacca. Apart from the above, in comparision with the dynamics of the Sunda Shelf, the Strait of Malacca reflects an equally significant role in the annual transports into the Andaman Sea.

  7. How ants drop out: ant abundance on tropical mountains.

    Science.gov (United States)

    Longino, John T; Branstetter, Michael G; Colwell, Robert K

    2014-01-01

    In tropical wet forests, ants are a large proportion of the animal biomass, but the factors determining abundance are not well understood. We characterized ant abundance in the litter layer of 41 mature wet forest sites spread throughout Central America (Chiapas, Guatemala, Honduras, Nicaragua, and Costa Rica) and examined the impact of elevation (as a proxy for temperature) and community species richness. Sites were intentionally chosen to minimize variation in precipitation and seasonality. From sea level to 1500 m ant abundance very gradually declined, community richness declined more rapidly than abundance, and the local frequency of the locally most common species increased. These results suggest that within this elevational zone, density compensation is acting, maintaining high ant abundance as richness declines. In contrast, in sites above 1500 m, ant abundance dropped abruptly to much lower levels. Among these high montane sites, community richness explained much more of the variation in abundance than elevation, and there was no evidence of density compensation. The relative stability of abundance below 1500 m may be caused by opposing effects of temperature on productivity and metabolism. Lower temperatures may decrease productivity and thus the amount of food available for consumers, but slower metabolisms of consumers may allow maintenance of higher biomass at lower resource supply rates. Ant communities at these lower elevations may be highly interactive, the result of continuous habitat presence over geological time. High montane sites may be ephemeral in geological time, resulting in non-interactive communities dominated by historical and stochastic processes. Abundance in these sites may be determined by the number of species that manage to colonize and/or avoid extinction on mountaintops.

  8. How ants drop out: ant abundance on tropical mountains.

    Directory of Open Access Journals (Sweden)

    John T Longino

    Full Text Available In tropical wet forests, ants are a large proportion of the animal biomass, but the factors determining abundance are not well understood. We characterized ant abundance in the litter layer of 41 mature wet forest sites spread throughout Central America (Chiapas, Guatemala, Honduras, Nicaragua, and Costa Rica and examined the impact of elevation (as a proxy for temperature and community species richness. Sites were intentionally chosen to minimize variation in precipitation and seasonality. From sea level to 1500 m ant abundance very gradually declined, community richness declined more rapidly than abundance, and the local frequency of the locally most common species increased. These results suggest that within this elevational zone, density compensation is acting, maintaining high ant abundance as richness declines. In contrast, in sites above 1500 m, ant abundance dropped abruptly to much lower levels. Among these high montane sites, community richness explained much more of the variation in abundance than elevation, and there was no evidence of density compensation. The relative stability of abundance below 1500 m may be caused by opposing effects of temperature on productivity and metabolism. Lower temperatures may decrease productivity and thus the amount of food available for consumers, but slower metabolisms of consumers may allow maintenance of higher biomass at lower resource supply rates. Ant communities at these lower elevations may be highly interactive, the result of continuous habitat presence over geological time. High montane sites may be ephemeral in geological time, resulting in non-interactive communities dominated by historical and stochastic processes. Abundance in these sites may be determined by the number of species that manage to colonize and/or avoid extinction on mountaintops.

  9. Forecasting the spatial and seasonal dynamic of Aedes albopictus oviposition activity in Albania and Balkan countries.

    Directory of Open Access Journals (Sweden)

    Clément Tisseuil

    2018-02-01

    Full Text Available The increasing spread of the Asian tiger mosquito, Aedes albopictus, in Europe and US raises public health concern due to the species competence to transmit several exotic human arboviruses, among which dengue, chikungunya and Zika, and urges the development of suitable modeling approach to forecast the spatial and temporal distribution of the mosquito. Here we developed a dynamical species distribution modeling approach forecasting Ae. albopictus eggs abundance at high spatial (0.01 degree WGS84 and temporal (weekly resolution over 10 Balkan countries, using temperature times series of Modis data products and altitude as input predictors. The model was satisfactorily calibrated and validated over Albania based observed eggs abundance data weekly monitored during three years. For a given week of the year, eggs abundance was mainly predicted by the number of eggs and the mean temperature recorded in the preceding weeks. That is, results are in agreement with the biological cycle of the mosquito, reflecting the effect temperature on eggs spawning, maturation and hatching. The model, seeded by initial egg values derived from a second model, was then used to forecast the spatial and temporal distribution of eggs abundance over the selected Balkan countries, weekly in 2011, 2012 and 2013. The present study is a baseline to develop an easy-handling forecasting model able to provide information useful for promoting active surveillance and possibly prevention of Ae. albopictus colonization in presently non-infested areas in the Balkans as well as in other temperate regions.

  10. Effects of drought season length on live moisture content dynamic in Mediterranean shrubs: 8 years of data

    Science.gov (United States)

    Pellizzaro, Grazia; Ventura, Andrea; Bortolu, Sara; Duce, Pierpaolo

    2017-04-01

    Mediterranean shrubs are an important component of Mediterranean vegetation communities. In this kind of vegetation, live fuel is a relevant component of the available fuel which catches fire and, consequently, its water content plays an important role in determining fire occurrence and spread. In live plant, water content patterns are related to both environmental conditions (e.g. meteorological variables, soil water availability) and ecophysiological characteristics of the plant species. According to projections on future climate, an increase in risk of summer droughts is likely to take place in Southern Europe. More prolonged drought seasons induced by climatic changes are likely to influence general flammability characteristics of fuel. In addition, variations in precipitation and mean temperature could directly affect fuel water status and length of critical periods of high ignition danger for Mediterranean ecosystems. The aims of this work were to analyse the influence of both weather seasonality and inter-annual weather variability on live fuel moisture content within and among some common Mediterranean species, and to investigate the effects of prolonged drought season on live moisture content dynamic. The study was carried out in North Sardinia (Italy). Measurements of LFMC seasonal pattern of two really common and flammable Mediterranean shrub species (Cistus monspeliensis and Rosmarinus officinalis) were performed periodically for 8 years. Meteorological variables were also recorded. Relationships between live fuel moisture content and environmental conditions (i.e. rainfall, air temperature and soil moisture) were investigated and effects of different lengths of drought season on LFMC pattern were analysed. Results showed that distribution and amount of rainfall affected seasonal variation of live fuel moisture content. In particular more prolonged drought seasons caused a longer period in which LFMC was below 95 -100% that is commonly considered as

  11. Seasonal changes in the communities of photosynthetic picoeukaryotes in Ofunato Bay as revealed by shotgun metagenomic sequencing

    KAUST Repository

    Rashid, Jonaira; Kobiyama, Atsushi; Reza, Md. Shaheed; Yamada, Yuichiro; Ikeda, Yuri; Ikeda, Daisuke; Mizusawa, Nanami; Ikeo, Kazuho; Sato, Shigeru; Ogata, Takehiko; Kudo, Toshiaki; Kaga, Shinnosuke; Watanabe, Shiho; Naiki, Kimiaki; Kaga, Yoshimasa; Mineta, Katsuhiko; Bajic, Vladimir B.; Gojobori, Takashi; Watabe, Shugo

    2018-01-01

    Small photosynthetic eukaryotes play important roles in oceanic food webs in coastal regions. We investigated seasonal changes in the communities of photosynthetic picoeukaryotes (PPEs) of the class Mamiellophyceae, including the genera Bathycoccus, Micromonas and Ostreococcus, in Ofunato Bay, which is located in northeastern Japan and faces the Pacific Ocean. The abundances of PPEs were assessed over a period of one year in 2015 at three sampling stations, KSt. 1 (innermost bay area), KSt. 2 (middle bay area) and KSt. 3 (bay entrance area) at depths of 1 m (KSt. 1, KSt. 2 and KSt. 3), 8 m (KSt. 1) or 10 m (KSt. 2 and KSt. 3) by employing MiSeq shotgun metagenomic sequencing. The total abundances of Bathycoccus, Ostreococcus and Micromonas were in the ranges of 42–49%, 35–49% and 13–17%, respectively. Considering all assayed sampling stations and depths, seasonal changes revealed high abundances of PPEs during the winter and summer and low abundances during late winter to early spring and late summer to early autumn. Bathycoccus was most abundant in the winter, and Ostreococcus showed a high abundance during the summer. Another genus, Micromonas, was relatively low in abundance throughout the study period. Taken together with previously suggested blooming periods of phytoplankton, as revealed by chlorophyll a concentrations in Ofunato Bay during spring and late autumn, these results for PPEs suggest that greater phytoplankton blooming has a negative influence on the seasonal occurrences of PPEs in the bay.

  12. Seasonal changes in the communities of photosynthetic picoeukaryotes in Ofunato Bay as revealed by shotgun metagenomic sequencing

    KAUST Repository

    Rashid, Jonaira

    2018-04-30

    Small photosynthetic eukaryotes play important roles in oceanic food webs in coastal regions. We investigated seasonal changes in the communities of photosynthetic picoeukaryotes (PPEs) of the class Mamiellophyceae, including the genera Bathycoccus, Micromonas and Ostreococcus, in Ofunato Bay, which is located in northeastern Japan and faces the Pacific Ocean. The abundances of PPEs were assessed over a period of one year in 2015 at three sampling stations, KSt. 1 (innermost bay area), KSt. 2 (middle bay area) and KSt. 3 (bay entrance area) at depths of 1 m (KSt. 1, KSt. 2 and KSt. 3), 8 m (KSt. 1) or 10 m (KSt. 2 and KSt. 3) by employing MiSeq shotgun metagenomic sequencing. The total abundances of Bathycoccus, Ostreococcus and Micromonas were in the ranges of 42–49%, 35–49% and 13–17%, respectively. Considering all assayed sampling stations and depths, seasonal changes revealed high abundances of PPEs during the winter and summer and low abundances during late winter to early spring and late summer to early autumn. Bathycoccus was most abundant in the winter, and Ostreococcus showed a high abundance during the summer. Another genus, Micromonas, was relatively low in abundance throughout the study period. Taken together with previously suggested blooming periods of phytoplankton, as revealed by chlorophyll a concentrations in Ofunato Bay during spring and late autumn, these results for PPEs suggest that greater phytoplankton blooming has a negative influence on the seasonal occurrences of PPEs in the bay.

  13. Seasonal dynamics of light absorption by chromophoric dissolved organic matter (CDOM) in the NW Mediterranean Sea (BOUSSOLE site)

    Science.gov (United States)

    Organelli, Emanuele; Bricaud, Annick; Antoine, David; Matsuoka, Atsushi

    2014-09-01

    We analyze a two-year time-series of chromophoric dissolved organic matter (CDOM) light absorption measurements in the upper 400 m of the water column at the BOUSSOLE site in the NW Mediterranean Sea. The seasonal dynamics of the CDOM light absorption coefficients at 440 nm (acdom(440)) is essentially characterized by (i) subsurface maxima forming in spring and progressively reinforcing throughout summer, (ii) impoverishment in the surface layer throughout summer and (iii) vertical homogeneity in winter. Seasonal variations of the spectral dependence of CDOM absorption, as described by the exponential slope value (Scdom), are characterized by highest values in summer and autumn at the surface and low values at the depths of acdom(440) subsurface maxima or just below them. Variations of acdom(440) are likely controlled by microbial digestion of phytoplankton cells, which leads to CDOM production, and by photochemical destruction (photobleaching), which leads to CDOM degradation. Photobleaching is also the main driver of Scdom variations. Consistently with previous observations, acdom(440) for a given chlorophyll a concentration is higher than expected from Case I waters bio-optical models. The total non-water light absorption budget shows that surface waters at the BOUSSOLE site are largely dominated by CDOM during all seasons but the algal bloom in March and April. These results improve the knowledge of CDOM absorption dynamics in the Mediterranean Sea, which is scarcely documented. In addition, they open the way to improved algorithms for the retrieval of CDOM absorption from field or satellite radiometric measurements.

  14. Effects of Forest Gaps on Litter Lignin and Cellulose Dynamics Vary Seasonally in an Alpine Forest

    Directory of Open Access Journals (Sweden)

    Han Li

    2016-01-01

    Full Text Available To understand how forest gaps and the associated canopy control litter lignin and cellulose dynamics by redistributing the winter snow coverage and hydrothermal conditions in the growing season, a field litterbag trial was conducted in the alpine Minjiang fir (Abies faxoniana Rehder and E.H. Wilson forest in a transitional area located in the upper reaches of the Yangtze River and the eastern Tibetan Plateau. Over the first year of litter decomposition, the litter exhibited absolute cellulose loss and absolute lignin accumulation except for the red birch litter. The changes in litter cellulose and lignin were significantly affected by the interactions among gap position, period and species. Litter cellulose exhibited a greater loss in the winter with the highest daily loss rate observed during the snow cover period. Both cellulose and lignin exhibited greater changes under the deep snow cover at the gap center in the winter, but the opposite pattern occurred under the closed canopy in the growing season. The results suggest that decreased snowpack seasonality due to winter warming may limit litter cellulose and lignin degradation in alpine forest ecosystems, which could further inhibit litter decomposition. As a result, the ongoing winter warming and gap vanishing would slow soil carbon sequestration from foliar litter in cold biomes.

  15. Spatial Dynamics of Sea Turtle Abundance and Shrimping Intensity in the U.S. Gulf of Mexico

    Directory of Open Access Journals (Sweden)

    Carrie J. McDaniel

    2000-07-01

    Full Text Available In order to examine the scientific feasibility of area closures for sea turtle protection, we determined the spatial dynamics of sea turtles for the U.S. Gulf of Mexico by analyzing National Marine Fisheries Service (NMFS aerial survey data in September, October, and November of 1992, 1993, and 1994. Turtle sightings were grouped into depth zones and NMFS fishery statistical zones, and strip transect methods were used to estimate the relative abundance of sea turtles in each subzone. Average shrimping intensity was calculated for each subzone for all months of 1992, 1993, and 1994, as well as for the months and locations of the aerial survey. The spatial overlap of sea turtle abundance and shrimping intensity suggested regions where interactions are likely to occur. Sea turtles were observed at much higher rates along the coast of Florida than in the Western Gulf; the highest density of sea turtles was observed in the Florida Keys region (0.525 turtles/km2. Shrimping intensity was highest in the Western Gulf along the coast of Texas and Louisiana, for both annual and fall estimates. Among alternative management scenarios, area closures in conjunction with continued Turtle Excluder Device (TED requirements would probably best prevent sea turtles from future extinction. By implementing shrimping closures off of South Padre Island, Texas, a potential second nesting population of Kemp's ridleys (Lepidochelys kempi could be protected. Closing waters where shrimping intensity is low and sea turtle abundance is high (e.g., South Florida waters would protect sea turtles without economically impacting a large number of shrimpers.

  16. Comparing different methods to assess weaver ant abundance in plantation trees

    DEFF Research Database (Denmark)

    Wargui, Rosine; Offenberg, Joachim; Sinzogan, Antonio

    2015-01-01

    Weaver ants (Oecophylla spp.) are widely used as effective biological control agents. In order to optimize their use, ant abundance needs to be tracked. As several methods have been used to estimate ant abundance on plantation trees, abundances are not comparable between studies and no guideline...... is available on which method to apply in a particular study. This study compared four existing methods: three methods based on the number of ant trails on the main branches of a tree (called the Peng 1, Peng 2 and Offenberg index) and one method based on the number of ant nests per tree. Branch indices did...... not produce equal scores and cannot be compared directly. The Peng 1 index was the fastest to assess, but showed only limited seasonal fluctuations when ant abundance was high, because it approached its upper limit. The Peng 2 and Offenberg indices were lower and not close to the upper limit and therefore...

  17. Spatial and Temporal Dynamics of Mixotrophic Protists Within a Protected Glacial Lake

    Science.gov (United States)

    DeVaul, S. B.; Sanders, R. W.

    2016-02-01

    Bacterivorous protists are vital components of the aquatic food web as prey for zooplankton and top-down regulators of bacteria. Many bacterivores utilize mixotrophic nutrition that combines photosynthesis with ingestion of particulate matter. Mixotrophic protists are capable of substantial rates of bacterivory - often greater than co-occurring heterotrophic flagellates. It has been argued that mixotrophs may gain a competitive advantage in natural systems due to their ability to utilize photosynthesis during periods of reduced particulate food or phagotrophy during periods of decreased irradiance. A central goal of ecological study has been to understand and ultimately predict the composition of communities in response to varying environmental conditions. The objectives of this study were to determine seasonal abundances and bacterial ingestion rates of heterotrophic, phototrophic and mixotrophic nanoflagellates (hereafter referred to as HNAN, PNAN and MNAN) and identify abiotic drivers that influence spatial and temporal dynamics of these functional groups. Water samples were collected approximately monthly over a 1.5 year period from Lake Lacawac, a 13,000 year old lake with a protected watershed. Trends in MNAN abundance were related to seasonal patterns of thermal stratification and varied with depth. Maximum abundance occurred in the summer epilimnion. Although HNAN abundance tended to be greater than that of MNAN, the latter generally had a greater grazer impact on bacterial biomass within the epilimnion. During the study period, MNAN removed a maximum of 75% of the bacterial biomass daily in the metalimnion. Mixotroph abundance and grazing impact tended to decrease in deeper waters, and was nearly absent in the anaerobic hypolimnion in late summer and early autumn.

  18. Seasonality as a Parrondian game

    Energy Technology Data Exchange (ETDEWEB)

    Peacock-Lopez, Enrique, E-mail: epeacock@williams.edu [Department of Chemistry, University of Cape Town, Rondebosch, 7701 Cape Town (South Africa)

    2011-08-15

    Switching strategies can be related to the so-called Parrondian games, where the alternation of two losing games yields a winning game. We consider two dynamics that by themselves yield undesirable behaviors, but when alternated, yield a desirable oscillatory behavior. In the analysis of the alternate-logistic map, we prove that alternating parameter values yielding extinction with parameter values associated with chaotic dynamics results in periodic trajectories. Ultimately, we consider a four season logistic model with either migration or immigration. -- Highlights: → We consider the logistic map as a population model and include parameter switching. → From bifurcation diagrams, we find parameters that follow the Parrondian Paradox. → We study a four-season Parrondian model that includes migration or immigration.

  19. Seasonality as a Parrondian game

    International Nuclear Information System (INIS)

    Peacock-Lopez, Enrique

    2011-01-01

    Switching strategies can be related to the so-called Parrondian games, where the alternation of two losing games yields a winning game. We consider two dynamics that by themselves yield undesirable behaviors, but when alternated, yield a desirable oscillatory behavior. In the analysis of the alternate-logistic map, we prove that alternating parameter values yielding extinction with parameter values associated with chaotic dynamics results in periodic trajectories. Ultimately, we consider a four season logistic model with either migration or immigration. -- Highlights: → We consider the logistic map as a population model and include parameter switching. → From bifurcation diagrams, we find parameters that follow the Parrondian Paradox. → We study a four-season Parrondian model that includes migration or immigration.

  20. Examining Dynamical Processes of Tropical Mountain Hydroclimate, Particularly During the Wet Season, Through Integration of Autonomous Sensor Observations and Climate Modeling

    Science.gov (United States)

    Hellstrom, R. A.; Fernandez, A.; Mark, B. G.; Covert, J. M.

    2016-12-01

    Peru is facing imminent water resource issues as glaciers retreat and demand increases, yet limited observations and model resolution hamper understanding of hydrometerological processes on local to regional scales. Much of current global and regional climate studies neglect the meteorological forcing of lapse rates (LRs) and valley and slope wind dynamics on critical components of the Peruvian Andes' water-cycle, and herein we emphasize the wet season. In 2004 and 2005 we installed an autonomous sensor network (ASN) within the glacierized Llanganuco Valley, Cordillera Blanca (9°S), consisting of discrete, cost-effective, automatic temperature loggers located along the valley axis and anchored by two automatic weather stations. Comparisons of these embedded hydrometeorological measurements from the ASN and climate modeling by dynamical downscaling using the Weather Research and Forecasting model (WRF) elucidate distinct diurnal and seasonal characteristics of the mountain wind regime and LRs. Wind, temperature, humidity, and cloud simulations suggest that thermally driven up-valley and slope winds converging with easterly flow aloft enhance late afternoon and evening cloud development which helps explain nocturnal wet season precipitation maxima measured by the ASN. Furthermore, the extreme diurnal variability of along-valley-axis LR, and valley wind detected from ground observations and confirmed by dynamical downscaling demonstrate the importance of realistic scale parameterizations of the atmospheric boundary layer to improve regional climate model projections in mountainous regions. We are currently considering to use intermediate climate models such as ICAR to reduce computing cost and we continue to maintain the ASN in the Cordillera Blanca.

  1. Seasonal abundance of Lutzomyia longipalpis (Diptera: Psychodidae) at an endemic focus of visceral leishmaniasis in Colombia.

    Science.gov (United States)

    Morrison, A C; Ferro, C; Pardo, R; Torres, M; Devlin, B; Wilson, M L; Tesh, R B

    1995-07-01

    Ecological studies on the sand fly Lutzomyia longipalpis (Lutz & Neiva) were conducted during 1990-1993 in a small rural community in Colombia where American visceral leishmaniasis is endemic. Standardized weekly sand fly collections made from pigpens and natural resting sites displayed a bimodal annual abundance cycle, with a small peak occurring in October-November and a larger one in April-May. Time series analysis was employed to quantify the associations between sand fly abundance and weather factors (temperature, relative humidity, and rainfall). In addition to a prominent 6-mo cycle. Fourier analysis of the collection data demonstrated that the L. longipalpis population also exhibited a 5- to 8-wk cycle that may represent the length of larval development. Autoregressive moving average models were fit to weekly collection data and their residuals were regressed against rainfall, temperature, and relative humidity. A significant positive association between female L. longipalpis abundance and the relative humidity and rainfall recorded 3 wk earlier was found, indicating that these factors may be of value in predicting sand fly abundance. Additionally, these data indicated that L. longipalpis larvae may become quiescent during adverse conditions.

  2. Defining microbial community composition and seasonal variation in a sewage treatment plant in India using a down-flow hanging sponge reactor.

    Science.gov (United States)

    Nomoto, Naoki; Hatamoto, Masashi; Hirakata, Yuga; Ali, Muntjeer; Jayaswal, Komal; Iguchi, Akinori; Okubo, Tsutomu; Takahashi, Masanobu; Kubota, Kengo; Tagawa, Tadashi; Uemura, Shigeki; Yamaguchi, Takashi; Harada, Hideki

    2018-05-01

    The characteristics of the microbial community in a practical-scale down-flow hanging sponge (DHS) reactor, high in organic matter and sulfate ion concentration, and the seasonal variation of the microbial community composition were investigated. Microorganisms related to sulfur oxidation and reduction (2-27%), as well as Leucobacter (7.50%), were abundant in the reactor. Anaerobic bacteria (27-38% in the first layer) were also in abundance and were found to contribute to the removal of organic matter from the sewage in the reactor. By comparing the Simpson index, the abundance-based coverage estimator (ACE) index, and the species composition of the microbial community across seasons (summer/dry, summer/rainy, autumn/dry, and winter/dry), the microbial community was found to change in composition only during the winter season. In addition to the estimation of seasonal variation, the difference in the microbial community composition along the axes of the DHS reactor was investigated for the first time. Although the abundance of each bacterial species differed along both axes of the reactor, the change of the community composition in the reactor was found to be greater along the vertical axis than the horizontal axis of the DHS reactor.

  3. Chemical Control for Host-Parasitoid Model within the Parasitism Season and Its Complex Dynamics

    Directory of Open Access Journals (Sweden)

    Tao Wang

    2016-01-01

    Full Text Available In the present paper, we develop a host-parasitoid model with Holling type II functional response function and chemical control, which can be applied at any time of each parasitism season or pest generation, and focus on addressing the importance of the timing of application pesticide during the parasitism season or pest generation in successful pest control. Firstly, the existence and stability of both the host and parasitoid populations extinction equilibrium and parasitoid-free equilibrium have been investigated. Secondly, the effects of key parameters on the threshold conditions have been discussed in more detail, which shows the importance of pesticide application times on the pest control. Thirdly, the complex dynamics including multiple attractors coexistence, chaotic behavior, and initial sensitivity have been studied by using numerical bifurcation analyses. Finally, the uncertainty and sensitivity of all the parameters on the solutions of both the host and parasitoid populations are investigated, which can help us to determine the key parameters in designing the pest control strategy. The present research can help us to further understand the importance of timings of pesticide application in the pest control and to improve the classical chemical control and to make management decisions.

  4. Seasonality Affects the Diversity and Composition of Bacterioplankton Communities in Dongjiang River, a Drinking Water Source of Hong Kong

    Directory of Open Access Journals (Sweden)

    Wei Sun

    2017-08-01

    Full Text Available Water quality ranks the most vital criterion for rivers serving as drinking water sources, which periodically changes over seasons. Such fluctuation is believed associated with the state shifts of bacterial community within. To date, seasonality effects on bacterioplankton community patterns in large rivers serving as drinking water sources however, are still poorly understood. Here we investigated the intra-annual bacterial community structure in the Dongjiang River, a drinking water source of Hong Kong, using high-throughput pyrosequencing in concert with geochemical property measurements during dry, and wet seasons. Our results showed that Proteobacteria, Actinobacteria, and Bacteroidetes were the dominant phyla of bacterioplankton communities, which varied in composition, and distribution from dry to wet seasons, and exhibited profound seasonal changes. Actinobacteria, Bacteroidetes, and Cyanobacteria seemed to be more associated with seasonality that the relative abundances of Actinobacteria, and Bacteroidetes were significantly higher in the dry season than those in the wet season (p < 0.01, while the relative abundance of Cyanobacteria was about 10-fold higher in the wet season than in the dry season. Temperature and NO3--N concentration represented key contributing factors to the observed seasonal variations. These findings help understand the roles of various bacterioplankton and their interactions with the biogeochemical processes in the river ecosystem.

  5. Seasonal Dynamics of Phlebotomine Sand Fly Species Proven Vectors of Mediterranean Leishmaniasis Caused by Leishmania infantum.

    Directory of Open Access Journals (Sweden)

    Bulent Alten

    2016-02-01

    Full Text Available The recent geographical expansion of phlebotomine vectors of Leishmania infantum in the Mediterranean subregion has been attributed to ongoing climate changes. At these latitudes, the activity of sand flies is typically seasonal; because seasonal phenomena are also sensitive to general variations in climate, current phenological data sets can provide a baseline for continuing investigations on sand fly population dynamics that may impact on future scenarios of leishmaniasis transmission. With this aim, in 2011-2013 a consortium of partners from eight Mediterranean countries carried out entomological investigations in sites where L. infantum transmission was recently reported.A common protocol for sand fly collection included monthly captures by CDC light traps, complemented by sticky traps in most of the sites. Collections were replicated for more than one season in order to reduce the effects of local weather events. In each site, the trapping effort was left unchanged throughout the survey to legitimate inter-seasonal comparisons. Data from 99,000 collected specimens were analyzed, resulting in the description of seasonal dynamics of 56,000 sand flies belonging to L. infantum vector species throughout a wide geographical area, namely P. perniciosus (Portugal, Spain and Italy, P. ariasi (France, P. neglectus (Greece, P. tobbi (Cyprus and Turkey, P. balcanicus and P. kandelakii (Georgia. Time of sand fly appearance/disappearance in collections differed between sites, and seasonal densities showed variations in each site. Significant correlations were found between latitude/mean annual temperature of sites and i the first month of sand fly appearance, that ranged from early April to the first half of June; ii the type of density trend, varying from a single peak in July/August to multiple peaks increasing in magnitude from May through September. A 3-modal trend, recorded for P. tobbi in Cyprus, represents a novel finding for a L. infantum vector

  6. Seasonal Dynamics of Phlebotomine Sand Fly Species Proven Vectors of Mediterranean Leishmaniasis Caused by Leishmania infantum.

    Science.gov (United States)

    Alten, Bulent; Maia, Carla; Afonso, Maria Odete; Campino, Lenea; Jiménez, Maribel; González, Estela; Molina, Ricardo; Bañuls, Anne Laure; Prudhomme, Jorian; Vergnes, Baptiste; Toty, Celine; Cassan, Cécile; Rahola, Nil; Thierry, Magali; Sereno, Denis; Bongiorno, Gioia; Bianchi, Riccardo; Khoury, Cristina; Tsirigotakis, Nikolaos; Dokianakis, Emmanouil; Antoniou, Maria; Christodoulou, Vasiliki; Mazeris, Apostolos; Karakus, Mehmet; Ozbel, Yusuf; Arserim, Suha K; Erisoz Kasap, Ozge; Gunay, Filiz; Oguz, Gizem; Kaynas, Sinan; Tsertsvadze, Nikoloz; Tskhvaradze, Lamzira; Giorgobiani, Ekaterina; Gramiccia, Marina; Volf, Petr; Gradoni, Luigi

    2016-02-01

    The recent geographical expansion of phlebotomine vectors of Leishmania infantum in the Mediterranean subregion has been attributed to ongoing climate changes. At these latitudes, the activity of sand flies is typically seasonal; because seasonal phenomena are also sensitive to general variations in climate, current phenological data sets can provide a baseline for continuing investigations on sand fly population dynamics that may impact on future scenarios of leishmaniasis transmission. With this aim, in 2011-2013 a consortium of partners from eight Mediterranean countries carried out entomological investigations in sites where L. infantum transmission was recently reported. A common protocol for sand fly collection included monthly captures by CDC light traps, complemented by sticky traps in most of the sites. Collections were replicated for more than one season in order to reduce the effects of local weather events. In each site, the trapping effort was left unchanged throughout the survey to legitimate inter-seasonal comparisons. Data from 99,000 collected specimens were analyzed, resulting in the description of seasonal dynamics of 56,000 sand flies belonging to L. infantum vector species throughout a wide geographical area, namely P. perniciosus (Portugal, Spain and Italy), P. ariasi (France), P. neglectus (Greece), P. tobbi (Cyprus and Turkey), P. balcanicus and P. kandelakii (Georgia). Time of sand fly appearance/disappearance in collections differed between sites, and seasonal densities showed variations in each site. Significant correlations were found between latitude/mean annual temperature of sites and i) the first month of sand fly appearance, that ranged from early April to the first half of June; ii) the type of density trend, varying from a single peak in July/August to multiple peaks increasing in magnitude from May through September. A 3-modal trend, recorded for P. tobbi in Cyprus, represents a novel finding for a L. infantum vector. Adults

  7. Seasonal variability in penaeid prawn larval abundance in the Mandovi and Zuari estuaries, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Goswami, S.C.; Goswami, U.

    more in the bottom samples. Based on larval density, M. dobsoni appeared to be a continuous breeder. The active spawning periods in other species were during the late postmonsoon and premonsoon seasons varying with the species. Peak recruitment...

  8. Seasonal resource conditions favor a summertime increase in North Pacific diatom-diazotroph associations.

    Science.gov (United States)

    Follett, Christopher L; Dutkiewicz, Stephanie; Karl, David M; Inomura, Keisuke; Follows, Michael J

    2018-02-15

    In the North Pacific Subtropical Gyre (NPSG), an annual pulse of sinking organic carbon is observed at 4000 m between July and August, driven by large diatoms found in association with nitrogen fixing, heterocystous, cyanobacteria: Diatom-Diazotroph Associations (DDAs). Here we ask what drives the bloom of DDAs and present a simplified trait-based model of subtropical phototroph populations driven by observed, monthly averaged, environmental characteristics. The ratio of resource supply rates favors nitrogen fixation year round. The relative fitness of DDA traits is most competitive in early summer when the mixed layer is shallow, solar irradiance is high, and phosphorus and iron are relatively abundant. Later in the season, as light intensity drops and phosphorus is depleted, the traits of small unicellular diazotrophs become more competitive. The competitive transition happens in August, at the time when the DDA export event occurs. This seasonal dynamic is maintained when embedded in a more complex, global-scale, ecological model, and provides predictions for the extent of the North Pacific DDA bloom. The model provides a parsimonious and testable hypothesis for the stimulation of DDA blooms.

  9. The dynamics of intraguild predation in Chrysomya albiceps Wied. (Diptera: Calliphoridae): interactions between instars and species under different abundances of food.

    Science.gov (United States)

    Rosa, Gisele S; de Carvalho, Lidia R; dos Reis, Sergio F; Godoy, Wesley A C

    2006-01-01

    The pattern of larval interaction in blowflies confined with Chrysomya albiceps Wied. and C. rufifacies Maquart can be changed in response to the predatory behaviour of the two species to a contest-type process instead of the scramble competition that usually occurs in blowflies. Facultative predation is a frequent behaviour in C. albiceps and C. rufifacies that occurs as an alternative food source during the larval stage. In this study, we investigated the dynamics of intraguild predation by C. albiceps on other fly species in order to analyse interspecific and intraspecific survival in C. albiceps, C. megacephala and C. macellaria Fabricius. The experimental design of the study allowed us to evaluate how factors such as species, density and abundance of food influenced the survival of the calliphorid species. When C. albiceps was confined with C. megacephala or C. macellaria, only adults of C. albiceps survived at different larval densities and abundance of food. In addition, the survival of C. albiceps was higher in two-species experiments when compared to single species experiments. The implications of these results for the dynamics of C. albiceps were discussed.

  10. Phytoplankton abundance, dominance and coexistence in an eutrophic reservoir in the state of Pernambuco, Northeast Brazil

    Directory of Open Access Journals (Sweden)

    Giulliari A. S. T. Lira

    2011-12-01

    Full Text Available The present study reports the phytoplankton abundance, dominance and co-existence relationships in the eutrophic Carpina reservoir, Pernambuco, Brazil. Sampling was carried out at six different depths bimonthly at a single reservoir spanning two climatic periods: dry season (January, September, and November 2006 and rainy season (March, May, and July 2006. Density, abundance, dominance, specific diversity and equitability of the community were determined, along with chlorophyll a, and physical and chemical variables of the environment. Eight species were considered abundant, and their densities corresponded to more than 90% of the total phytoplankton community quantified. Cyanobacteria represented more than 80% of this density. Cylindrospermopsis raciborskii was the only dominant taxon in the dry season, and was co-dominant in the rainy season. C. raciborskii, Planktothrix agardhii and Geitlerinema amphibium had the greatest densities and lowest vertical variation coefficients. The statistical analysis indicated relationships with vertical and seasonal variations in the phytoplankton community and the following variables: total dissolved solids, water temperature, electrical conductivity and pH. The changes in the environmental variables were discrete and regulated by the establishment of precipitation however, they were able to promote vertical and seasonal instability in the structure of the phytoplankton community.O presente estudo remete às relações de abundância, dominância e co-existência fitoplanctônica no reservatório eutrófico de Carpina, Pernambuco, Brasil. Foram realizadas amostragens bimensalmente, em seis profundidades, em um único ponto do reservatório, contemplando dois períodos sazonais: seco (janeiro, setembro e novembro/2006 e chuvoso (março, maio e julho/2006. A densidade, abundância, dominância, diversidade específica e equitabilidade foram determinadas, além da clorofila a e algumas variáveis físicas e qu

  11. Seasonal, spatial, and maternal effects on gut microbiome in wild red squirrels.

    Science.gov (United States)

    Ren, Tiantian; Boutin, Stan; Humphries, Murray M; Dantzer, Ben; Gorrell, Jamieson C; Coltman, David W; McAdam, Andrew G; Wu, Martin

    2017-12-21

    Our understanding of gut microbiota has been limited primarily to findings from human and laboratory animals, but what shapes the gut microbiota in nature remains largely unknown. To fill this gap, we conducted a comprehensive study of gut microbiota of a well-studied North American red squirrel (Tamiasciurus hudsonicus) population. Red squirrels are territorial, solitary, and live in a highly seasonal environment and therefore represent a very attractive system to study factors that drive the temporal and spatial dynamics of gut microbiota. For the first time, this study revealed significant spatial patterns of gut microbiota within a host population, suggesting limited dispersal could play a role in shaping and maintaining the structure of gut microbial communities. We also found a remarkable seasonal rhythm in red squirrel's gut microbial composition manifested by a tradeoff between relative abundance of two genera Oscillospira and Corpococcus and clearly associated with seasonal variation in diet availability. Our results show that in nature, environmental factors exert a much stronger influence on gut microbiota than host-associated factors including age and sex. Despite strong environmental effects, we found clear evidence of individuality and maternal effects, but host genetics did not seem to be a significant driver of the gut microbial communities in red squirrels. Taken together, the results of this study emphasize the importance of external ecological factors rather than host attributes in driving temporal and spatial patterns of gut microbiota in natural environment.

  12. Biology and Seasonality of the Reemergent Pest Rhynchaenus pallicornis (Coleoptera: Curculionidae) and Methods for Monitoring Its Abundance.

    Science.gov (United States)

    Pote, John M; Nielsen, Anne L; Grieshop, Matthew J

    2016-08-01

    Rhynchaenus pallicornis (Say) is a pest of commercially grown apples in the upper Midwest. This historic pest has resurged and caused severe yield loss on farms using certified organic production practices. The life history and potential monitoring methods of R. pallicornis are presented. Seasonal abundance data were collected through beat and visual sampling. A phenological model was developed for R. pallicornis. The minimum developmental threshold of R. pallicornis was determined to be 3.5°C with a required degree-day accumulation of 125°D for first adult emergence. Larval damage was observed on >60% of leaves in unmanaged orchards and affected significantly fewer basal leaf clusters (near the trunk), than medially or apically located clusters. Of 2,900 R. pallicornis larval mines collected over two years at three different sites, 18.0% produced at least one adult parasitoid, but the targeted larval stage is unknown. Measurements of R. pallicornis larval head capsules and the simple frequency method were used to determine three larval instars of R. pallicornis The number of larval instars could also be accurately determined by observing the presence or absence of two sets of thoracic sclerites. Pyramid traps, yellow sticky cards baited with olfactory cues (pear essence, benzaldehyde, and an aggregation of adult R. pallicornis) were evaluated as R. pallicornis monitoring tools. None of the traps or lures tested significantly affected the number of adult R. pallicornis per trap. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  13. Seasonal patterns in microbial communities inhabiting the hot springs of Tengchong, Yunnan Province, China.

    Science.gov (United States)

    Briggs, Brandon R; Brodie, Eoin L; Tom, Lauren M; Dong, Hailiang; Jiang, Hongchen; Huang, Qiuyuan; Wang, Shang; Hou, Weiguo; Wu, Geng; Huang, Liuquin; Hedlund, Brian P; Zhang, Chuanlun; Dijkstra, Paul; Hungate, Bruce A

    2014-06-01

    Studies focusing on seasonal dynamics of microbial communities in terrestrial and marine environments are common; however, little is known about seasonal dynamics in high-temperature environments. Thus, our objective was to document the seasonal dynamics of both the physicochemical conditions and the microbial communities inhabiting hot springs in Tengchong County, Yunnan Province, China. The PhyloChip microarray detected 4882 operational taxonomic units (OTUs) within 79 bacterial phylum-level groups and 113 OTUs within 20 archaeal phylum-level groups, which are additional 54 bacterial phyla and 11 archaeal phyla to those that were previously described using pyrosequencing. Monsoon samples (June 2011) showed increased concentrations of potassium, total organic carbon, ammonium, calcium, sodium and total nitrogen, and decreased ferrous iron relative to the dry season (January 2011). At the same time, the highly ordered microbial communities present in January gave way to poorly ordered communities in June, characterized by higher richness of Bacteria, including microbes related to mesophiles. These seasonal changes in geochemistry and community structure are likely due to high rainfall influx during the monsoon season and indicate that seasonal dynamics occurs in high-temperature environments experiencing significant changes in seasonal recharge. Thus, geothermal environments are not isolated from the surrounding environment and seasonality affects microbial ecology. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  14. Dynamics of Phenol Degrading—Iron Reducing Bacteria in Intensive Rice Croopping System

    Institute of Scientific and Technical Information of China (English)

    LUWENJING; W.REICHARDT; 等

    2001-01-01

    Field and greenhouse experiments were conducted to investigate the effects of cropping season,nitrogen fertilizer input and aerated fallow o the dynamics of phenol degrading-iron reducing bacteria(PD-IRB)in tropical irrigated rice(Oryza sativa L.)systems,The PD-IRB population density was monitored at different stages of rice growth in two cropping seasons (dry and early wet) in a continuous annual triple rice cropping system under irrigated condition,In this system,the high nitrogen input (195 and 135 kg N ha-1 in dry and ewt seasons ,respectively)plots and control plots receiving no N fertilizer were compared to investigate the effect of nitrogen rate on population size.The phenol degrading-iron reducing bacteria (PD-IRB)were abundant in soils under croppin systems of tropical irrigated rice.However,density of the bacterial populations varied with rice growth stages.Cropping seasons,rhizosphere,and aerated fallow could affect the dynamics of PD-IRB,In the field trial,viable counts of PD-IRB in the topsoil layer(15 cm)ranged between 102 and 108 cells per gram of dry soil.A steep increase in viable counts during the second half of the cropping season suggested that the population density of PD-IRB increased ant advanced crop-growth stages.Population growth of PD-IRB was accelerated during the dry season compared to the wet season,In the greenhouse experiment,the adjacent aerated fallow revealed 1-2 orders of magnitude higher in most probable number(MPN)of PD-IRB than the wet fallow treated plots.As a prominent group of Fe reducing bacteria,PD-IRB predominated in the rhizosphere of rice,since maximum MPN of PD-IRB (2.62×108 g-1 soil) was found in rhizosphere soil.Mineral N fertilizer rates showed no significant effect on PD-IRB population density.

  15. Elemental abundances of solar sibling candidates

    International Nuclear Information System (INIS)

    Ramírez, I.; Lambert, D. L.; Endl, M.; Cochran, W. D.; MacQueen, P. J.; Bajkova, A. T.; Bobylev, V. V.; Roederer, I. U.; Wittenmyer, R. A.

    2014-01-01

    Dynamical information along with survey data on metallicity and in some cases age have been used recently by some authors to search for candidates of stars that were born in the cluster where the Sun formed. We have acquired high-resolution, high signal-to-noise ratio spectra for 30 of these objects to determine, using detailed elemental abundance analysis, if they could be true solar siblings. Only two of the candidates are found to have solar chemical composition. Updated modeling of the stars' past orbits in a realistic Galactic potential reveals that one of them, HD 162826, satisfies both chemical and dynamical conditions for being a sibling of the Sun. Measurements of rare-element abundances for this star further confirm its solar composition, with the only possible exception of Sm. Analysis of long-term high-precision radial velocity data rules out the presence of hot Jupiters and confirms that this star is not in a binary system. We find that chemical tagging does not necessarily benefit from studying as many elements as possible but instead from identifying and carefully measuring the abundances of those elements that show large star-to-star scatter at a given metallicity. Future searches employing data products from ongoing massive astrometric and spectroscopic surveys can be optimized by acknowledging this fact.

  16. Timing and severity of immunizing diseases in rabbits is controlled by seasonal matching of host and pathogen dynamics

    OpenAIRE

    Wells, Konstans; Brook, Barry W.; Lacy, Robert C.; Mutze, Greg J.; Peacock, David E.; Sinclair, Ron G.; Schwensow, Nina; Cassey, Phillip; O'Hara, Robert B.; Fordham, Damien A.

    2015-01-01

    Infectious diseases can exert a strong influence on the dynamics of host populations, but it remains unclear why such disease-mediated control only occurs under particular environmental conditions. We used 16 years of detailed field data on invasive European rabbits (Oryctolagus cuniculus) in Australia, linked to individual-based stochastic models and Bayesian approximations, to test whether (i) mortality associated with rabbit haemorrhagic disease (RHD) is driven primarily by seasonal matche...

  17. Heterogeneity in fire severity within early season and late season prescribed burns in a mixed-conifer forest

    Science.gov (United States)

    Knapp, E.E.; Keeley, J.E.

    2006-01-01

    Structural heterogeneity in forests of the Sierra Nevada was historically produced through variation in fire regimes and local environmental factors. The amount of heterogeneity that prescription burning can achieve might now be more limited owing to high fuel loads and increased fuel continuity. Topography, woody fuel loading, and vegetative composition were quantified in plots within replicated early and late season burn units. Two indices of fire severity were evaluated in the same plots after the burns. Scorch height ranged from 2.8 to 25.4 m in early season plots and 3.1 to 38.5 m in late season plots, whereas percentage of ground surface burned ranged from 24 to 96% in early season plots and from 47 to 100% in late season plots. Scorch height was greatest in areas with steeper slopes, higher basal area of live trees, high percentage of basal area composed of pine, and more small woody fuel. Percentage of area burned was greatest in areas with less bare ground and rock cover (more fuel continuity), steeper slopes, and units burned in the fall (lower fuel moisture). Thus topographic and biotic factors still contribute to the abundant heterogeneity in fire severity with prescribed burning, even under the current high fuel loading conditions. Burning areas with high fuel loads in early season when fuels are moister may lead to patterns of heterogeneity in fire effects that more closely approximate the expected patchiness of historical fires.

  18. Seasonal to hour variation scales in abundance and production of total and particle-attached bacteria in the open NW Mediterranean Sea (0–1000 m

    Directory of Open Access Journals (Sweden)

    G. Mével

    2008-11-01

    Full Text Available We present the vertical and temporal dynamics of total vs. particle-attached bacterial abundance and activity over a 5 week period under summer to autumn transition in NW Mediterranean Sea. At a weekly time scale, total bacterial biomass and production in the euphotic layers was significantly correlated with phytoplanktonic biomass. At an hourly time scale, total bacterial biomass responded very rapidly to chlorophyll a fluctuations, suggesting a tight coupling between phytoplankton and bacteria for resource partitioning during the summer-autumn transition. In contrast, no influence of diel changes on bacterial parameters was detected. Episodic events such as coastal water intrusions had a significant positive effect on total bacterial abundance and production, whereas we could not detect any influence of short wind events whatever the magnitude. Finally, we show that particle-attached bacteria can represent a large proportion (up to 49% of the total bacterial activity in the euphotic layer but display rapid and sporadic changes at hourly time scales. In the mesopelagic layers, bacterial abundance and production linearly decreased with depth, except some production peaks at 400–750 m. This study underlines the value of large datasets covering different temporal scales to clarify the biogeochemical role of bacteria in the cycling of organic matter in open seawater.

  19. Using social network analysis tools in ecology : Markov process transition models applied to the seasonal trophic network dynamics of the Chesapeake Bay

    NARCIS (Netherlands)

    Johnson, Jeffrey C.; Luczkovich, Joseph J.; Borgatti, Stephen P.; Snijders, Tom A. B.; Luczkovich, S.P.

    2009-01-01

    Ecosystem components interact in complex ways and change over time due to a variety of both internal and external influences (climate change, season cycles, human impacts). Such processes need to be modeled dynamically using appropriate statistical methods for assessing change in network structure.

  20. Seasonal variation in the distribution and isotopic composition of phytoplankton in an amazon floodplain lake, Brazil

    International Nuclear Information System (INIS)

    Caraballo, Pedro; Forsberg, Bruce R; Leite, Rosseval G

    2014-01-01

    To evaluate the seasonal variation and isotopic composition of phytoplankton, water samples were collected monthly between October 2007 and November 2008 in Lake Catalao, a floodplain lake at the confluence between rivers Negro and Amazon. Analyses of total chlorophyll concentration and δ"13C and δ"15N isotopic abundances were made from particulate size fractions of 30-60, 10-30 and <10 μm in the littoral, pelagic, and floating meadows regions. Chlorophyll concentration was found to be inversely associated to lake depth, and high concentrations of chlorophyll in the floating meadows zone were significant. The fraction <10 μm was the most abundant representing in average more than 40% of the particulate matter. The δ3 13C values were relatively constant during the study (-25.1% -34.0%), whereas the δ"15N values showed strong variability (15.6% 2.4%), which has been attributed to the resuspension of sediments during mixing of the water column. Mixing associated to the sudden drop in temperature during the rising water period was an important event in the trophic and isotopic dynamics of the lake. Variations in chlorophyll content were generally associated with the dilution process, in which concentration was inversely correlated to the water level, whereas abundance was directly correlated to the water level.

  1. Concentrations of environmental DNA (eDNA) reflect spawning salmon abundance at fine spatial and temporal scales

    Science.gov (United States)

    Tillotson, Michael D.; Kelly, Ryan P.; Duda, Jeff; Hoy, Marshal S.; Kralj, James; Quinn, Thomas P.

    2018-01-01

    Developing fast, cost-effective assessments of wild animal abundance is an important goal for many researchers, and environmental DNA (eDNA) holds much promise for this purpose. However, the quantitative relationship between species abundance and the amount of DNA present in the environment is likely to vary substantially among taxa and with ecological context. Here, we report a strong quantitative relationship between eDNA concentration and the abundance of spawning sockeye salmon in a small stream in Alaska, USA, where we took temporally- and spatially-replicated samples during the spawning period. This high-resolution dataset suggests that (1) eDNA concentrations vary significantly day-to-day, and likely within hours, in the context of the dynamic biological event of a salmon spawning season; (2) eDNA, as detected by species-specific quantitative PCR probes, seems to be conserved over short distances (tens of meters) in running water, but degrade quickly over larger scales (ca. 1.5 km); and (3) factors other than the mere presence of live, individual fish — such as location within the stream, live/dead ratio, and water temperature — can affect the eDNA-biomass correlation in space or time. A multivariate model incorporating both biotic and abiotic variables accounted for over 75% of the eDNA variance observed, suggesting that where a system is well-characterized, it may be possible to predict species' abundance from eDNA surveys, although we underscore that species- and system-specific variables are likely to limit the generality of any given quantitative model. Nevertheless, these findings provide an important step toward quantitative applications of eDNA in conservation and management.

  2. Phytoplankton dynamics in the Gulf of Aqaba (Eilat, Red Sea): A simulation study of mariculture effects

    International Nuclear Information System (INIS)

    Laiolo, Leonardo; Barausse, Alberto; Dubinsky, Zvy; Palmeri, Luca; Goffredo, Stefano; Kamenir, Yury; Al-Najjar, Tariq; Iluz, David

    2014-01-01

    Highlights: • Fish farms in the Gulf of Aqaba strongly affect phytoplankton levels. • Integrating statistics and ecological models help understand phytoplankton dynamics. • Phytoplankton dynamics are driven by mariculture activity and natural forces. • Mariculture can alter typical phytoplankton dynamics and seasonal succession. - Abstract: The northern Gulf of Aqaba is an oligotrophic water body hosting valuable coral reefs. In the Gulf, phytoplankton dynamics are driven by an annual cycle of stratification and mixing. Superimposed on that fairly regular pattern was the establishment of a shallow-water fish-farm initiative that increased gradually until its activity was terminated in June 2008. Nutrient, water temperature, irradiation, phytoplankton data gathered in the area during the years 2007–2009, covering the peak of the fish-farm activity and its cessation, were analyzed by means of statistical analyses and ecological models of phytoplankton dynamics. Two datasets, one from an open water station and one next to the fish farms, were used. Results show that nutrient concentrations and, consequently, phytoplankton abundance and seasonal succession were radically altered by the pollution originating from the fish-farm in the sampling station closer to it, and also that the fish-farm might even have influenced the open water station

  3. Seasonal and daily fluctuation of diatoms during spring tide periods in Kerkennah Islands

    Directory of Open Access Journals (Sweden)

    Mounir Ben brahim

    2015-06-01

    Full Text Available Objective: To study seasonal and the daily distribution of diatoms in the three tidal periods (flood, slack and ebb period during the spring tide. Methods: Water samples were taken and environmental variables were measured three times in each tidal period during 10 days of spring tide. Sampling was done in 2007 in Cercina station located in the western coast of Kerkennah (34°41'27'' N; 11°07'45'' E (Southern Tunisia. Results: Nutrients showed significant variation between seasons, increasing in spring and decreasing noticeably in autumn and winter. About 36 diatom species were found. Results revealed a remarkable abundance increase in spring and summer. Irregular differences in diatom abundances were revealed over the tidal periods, with the highest rates being detected during the flood and the ebb period, while the abundance rate was lowest during the slack period. This could presumably be attributed to the increase of nutrient supply of suspended particulate matter during water motion. The results revealed a correlation between diatom abundance and temperature, NO2 - , NO3 - , Si(OH4 and PO4 3 . Temperature seemed to be the most important factors which may influence the distribution and diatom abundance. Conclusions: Tide has various effects on the nutrients status and diatoms community (in terms of species composition, succession and abundance between different tidal periods. Fluctuation of diatoms was correlated with changes in the circulation of water bodies and changes in nutrient regime.

  4. Seasonal Variation of Colored Dissolved Organic Matter in Barataria Bay, Louisiana, Using Combined Landsat and Field Data

    Directory of Open Access Journals (Sweden)

    Ishan Joshi

    2015-09-01

    Full Text Available Coastal bays, such as Barataria Bay, are important transition zones between the terrigenous and marine environments that are also optically complex due to elevated amounts of particulate and dissolved constituents. Monthly field data collected over a period of 15 months in 2010 and 2011 in Barataria Bay were used to develop an empirical band ratio algorithm for the Landsat-5 TM that showed a good correlation with the Colored Dissolved Organic Matter (CDOM absorption coefficient at 355 nm (ag355 (R2 = 0.74. Landsat-derived CDOM maps generally captured the major details of CDOM distribution and seasonal influences, suggesting the potential use of Landsat imagery to monitor biogeochemistry in coastal water environments. An investigation of the seasonal variation in ag355 conducted using Landsat-derived ag355 as well as field data suggested the strong influence of seasonality in the different regions of the bay with the marine end members (lower bay experiencing generally low but highly variable ag355 and the freshwater end members (upper bay experiencing high ag355 with low variability. Barataria Bay experienced a significant increase in ag355 during the freshwater release at the Davis Pond Freshwater Diversion (DPFD following the Deep Water Horizon oil spill in 2010 and following the Mississippi River (MR flood conditions in 2011, resulting in a weak linkage to salinity in comparison to the other seasons. Tree based statistical analysis showed the influence of high river flow conditions, high- and low-pressure systems that appeared to control ag355 by ~28%, 29% and 43% of the time duration over the study period at the marine end member just outside the bay. An analysis of CDOM variability in 2010 revealed the strong influence of the MR in controlling CDOM abundance in the lower bay during the high flow conditions, while strong winds associated with cold fronts significantly increase CDOM abundance in the upper bay, thus revealing the important

  5. Deriving seasonal dynamics in ecosystem properties of semi-arid savanna grasslands from in situ-based hyperspectral reflectance

    DEFF Research Database (Denmark)

    Tagesson, Håkan Torbern; Fensholt, Rasmus; Huber, S.

    2015-01-01

    strongly affected by solar zenith angles and sensor viewing geometry, as were many combinations of visible wavelengths. This study provides analyses based upon novel multi-angular hyperspectral data for validation of Earth-observation-based properties of semi-arid ecosystems, as well as insights...... between normalised difference spectral indices (NDSIs) and the measured ecosystem properties. Finally, the effects of variable sun sensor viewing geometry on different NDSI wavelength combinations were analysed. The wavelengths with the strongest correlation to seasonal dynamics in ecosystem properties...

  6. Seasonal photosynthetic activity in evergreen conifer leaves monitored with spectral reflectance

    Science.gov (United States)

    Wong, C. Y.; Gamon, J. A.

    2013-12-01

    Boreal evergreen conifers must maintain photosynthetic systems in environments where temperatures vary greatly across seasons from high temperatures in the summer to freezing levels in the winter. This involves seasonal downregulation and photoprotection during periods of extreme temperatures. To better understand this downregulation, seasonal dynamics of photosynthesis of lodgepole (Pinus contorta D.) and ponderosa pine (Pinus ponderosa D.) were monitored in Edmonton, Canada over two years. Spectral reflectance at the leaf and stand scales was measured weekly and the Photochemical Reflectance Index (PRI), often used as a proxy for chlorophyll and carotenoid pigment levels and photosynthetic light-use efficiency (LUE), was used to track the seasonal dynamics of photosynthetic activity. Additional physiological measurements included leaf pigment content, chlorophyll fluorescence, and gas exchange. All the metrics indicate large seasonal changes in photosynthetic activity, with a sharp transition from winter downregulation to active photosynthesis in the spring and a more gradual fall transition into winter. The PRI was a good indicator of several other variables including seasonally changing photosynthetic activity, chlorophyll fluorescence, photosynthetic LUE, and pigment pool sizes. Over the two-year cycle, PRI was primarily driven by changes in constitutive (chlorophyll:carotenoid) pigment levels correlated with seasonal photosynthetic activity, with a much smaller variation caused by diurnal changes in xanthophyll cycle activity (conversion between violaxanthin & zeaxanthin). Leaf and canopy scale PRI measurements exhibited parallel responses during the winter-spring transition. Together, our findings indicate that evergreen conifers photosynthetic system possesses a remarkable degree of resilience in response to large temperature changes across seasons, and that optical remote sensing can be used to observe the seasonal effects on photosynthesis and

  7. Seasonal abundance of the shipworm Neoteredo reynei (Bivalvia, Teredinidae in mangrove driftwood from a northern Brazilian beach

    Directory of Open Access Journals (Sweden)

    Carlos S. Filho

    2008-03-01

    Full Text Available Shipworms are important decomposers of wood, especially in mangrove forests where productivity is high. However, little emphasis has been given to the activity of shipworms in relation to the export of nutrients from mangroves to adjacent coastal areas. As a first step to obtaining such information, the frequency of colonized mangrove driftwood as well as shipworm density and length were studied by collecting washed up logs during a year at Ajuruteua beach, state of Pará, northern Brazil. A single species, Neoteredo reynei (Bartsch, 1920, was found colonizing driftwood. Although large colonized logs were most common on the beach, shipworm density was higher in small logs, especially during the dry season. In general, however, density was higher during the wet season (January to April and lowest in July. Overall shipworm mean length was 9.66cm. In large logs, mean length increased between the wet and dry seasons. However, there was no difference in length among log size categories. Mean shipworm length was similar throughout most of the year but tended to be greater in July. Although salinity varied between 10.9 and 40 during the year, no relationship was found between salinity and density or length. The results suggest that shipworm activity in driftwood logs is relatively constant throughout the year. Increased air humidity and rainfall may promote survival during the wet season. Large logs may take longer to colonize and thus have lower densities than small ones which are scarce probably because they are destroyed rapidly by shipworm activity. However, data on the disintegration of logs would be necessary to test this hypothesis. Larger size of shipworms in the dry season may be related to growth after an earlier recruitment period. Shipworms in large logs during the dry season may be better protected from dessication and high temperatures by the insulating properties of the larger volume of wood.

  8. Algal composition and abundance in the neuston surface micro layer from a lake and pond in Virginia (U.S.A.

    Directory of Open Access Journals (Sweden)

    Harold G. MARSHALL

    2003-08-01

    Full Text Available A comparative study was conducted that characterized the algae within the neuston, ca 2 mm below the surface, and the algae in the water column from two freshwater habitats. There were significant differences in total algal abundance and the abundance of diatoms, cyanoprokaryotes, and chlorophytes between the neuston and water column algae of these two regions during each season and at both sites. The pond neuston was dominated by chlorophytes, with total algal abundance ranging seasonally from 0.6 to 59.6 × 10-3 cells ml-1 compared to water column algal concentrations of 4.1 to 40.4 × 10-3 cells ml-1. The lake was dystrophic, with diatoms the most common and abundant species, with the neuston algal abundance ranging from 0.09 to 1.31 × 10-3 cells ml-1, and the water column algae from 0.19 to 2.70 × 10-3 cells ml-1. Proximity to the variable nature of the surface layer was not a deterrent for neuston algal development, which frequently reached bloom status and contained a diverse assemblage of taxa.

  9. The impact of seasonal changes in stratification on the dynamics of internal waves in the Sea of Okhotsk

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    Oxana E. Kurkina

    2017-11-01

    Full Text Available The properties and dynamics of internal waves in the ocean crucially depend on the vertical structure of water masses. We present detailed analysis of the impact of spatial and seasonal variations in the density-driven stratification in the Sea of Okhotsk on the properties of the classic kinematic and nonlinear parameters of internal waves in this water body. The resulting maps of the phase speed of long internal waves and coefficients at various terms of the underlying Gardner’s equation make it possible to rapidly determine the main properties of internal solitary waves in the region and to choose an adequate set of parameters of the relevant numerical models. It is shown that the phase speed of long internal waves almost does not depend on the particular season. The coefficient at the quadratic term of the underlying evolution equation is predominantly negative in summer and winter and therefore internal solitons usually have negative polarity. Numerical simulations of the formation of internal solitons and solibores indicate that seasonal variations in the coefficient at the cubic term of Gardner’s equation lead to substantial variations in the shape of solibores.

  10. Abundância e sazonalidade das espécies de Hydropsychidae (Insecta, Trichoptera capturadas em armadilha luminosa no Estado do Paraná, Brasil Abundance and seasonality of Hydropsychidae species (Insccta, Trichoptera collected with light trap at Paraná State, Brazil

    Directory of Open Access Journals (Sweden)

    Luciane Marinoni

    2000-03-01

    Full Text Available During one year of the project called "Survey of the Entomological Fauna in Paraná State" (henceforth PROFAUPAR, 126,340 adult specimens of Trichoptera were collected with light trap. The individuais of the family Hydropsychidae were identified and a list of species is presented. Eighteen species in four genera were identified. From this, S. (R. discalis Flint, 1972,5. (R. paramnsis Flint, 1983;S (R. spinulosa Flint, 1972 are for the first time registered for Brazil and Leptonema sparsum (Ulmer, 1905, Macrostemum hyalinum (Pictet, 1836, S. (Smicridea albosignata Ulmer, 1907; S. (Rhyacophylax dentifera Flint, 1983; S. (R. iguazu Flint, 1983; S. (R. piraya Flint, 1983; S. (R. unguiculaia Flint, 1983; S. (R. vermiculata Flint, 1978 and S. (R. weidneri Flint, 1972, for Paraná State. Discussion about the individuais abundance and species seasonality is presented.

  11. Nitrification and ammonium dynamics in Taihu Lake, China: seasonal competition for ammonium between nitrifiers and cyanobacteria

    Science.gov (United States)

    Hampel, Justyna J.; McCarthy, Mark J.; Gardner, Wayne S.; Zhang, Lu; Xu, Hai; Zhu, Guangwei; Newell, Silvia E.

    2018-02-01

    Taihu Lake is hypereutrophic and experiences seasonal, cyanobacterial harmful algal blooms. These Microcystis blooms produce microcystin, a potent liver toxin, and are linked to anthropogenic nitrogen (N) and phosphorus (P) loads to lakes. Microcystis spp. cannot fix atmospheric N and must compete with ammonia-oxidizing and other organisms for ammonium (NH4+). We measured NH4+ regeneration and potential uptake rates and total nitrification using stable-isotope techniques. Nitrification studies included abundance of the functional gene for NH4+ oxidation, amoA, for ammonia-oxidizing archaea (AOA) and bacteria (AOB). Potential NH4+ uptake rates ranged from 0.02 to 6.80 µmol L-1 h-1 in the light and from 0.05 to 3.33 µmol L-1 h-1 in the dark, and NH4+ regeneration rates ranged from 0.03 to 2.37 µmol L-1 h-1. Nitrification rates exceeded previously reported rates in most freshwater systems. Total nitrification often exceeded 200 nmol L-1 d-1 and was > 1000 nmol L-1 d-1 at one station near a river discharge. AOA amoA gene copies were more abundant than AOB gene copies (p Internal NH4+ regeneration exceeded external N loading to the lake by a factor of 2 but was ultimately fueled by external N loads. Our results thus support the growing literature calling for watershed N loading reductions in concert with existing management of P loads.

  12. Observations on abundance of bluntnose sixgill sharks, Hexanchus griseus, in an urban waterway in Puget Sound, 2003-2005.

    Science.gov (United States)

    Griffing, Denise; Larson, Shawn; Hollander, Joel; Carpenter, Tim; Christiansen, Jeff; Doss, Charles

    2014-01-01

    The bluntnose sixgill shark, Hexanchus griseus, is a widely distributed but poorly understood large, apex predator. Anecdotal reports of diver-shark encounters in the late 1990's and early 2000's in the Pacific Northwest stimulated interest in the normally deep-dwelling shark and its presence in the shallow waters of Puget Sound. Analysis of underwater video documenting sharks at the Seattle Aquarium's sixgill research site in Elliott Bay and mark-resight techniques were used to answer research questions about abundance and seasonality. Seasonal changes in relative abundance in Puget Sound from 2003-2005 are reported here. At the Seattle Aquarium study site, 45 sixgills were tagged with modified Floy visual marker tags, along with an estimated 197 observations of untagged sharks plus 31 returning tagged sharks, for a total of 273 sixgill observations recorded. A mark-resight statistical model based on analysis of underwater video estimated a range of abundance from a high of 98 sharks seen in July of 2004 to a low of 32 sharks seen in March of 2004. Both analyses found sixgills significantly more abundant in the summer months at the Seattle Aquarium's research station.

  13. Seasonal variability of rocky reef fish assemblages: Detecting functional and structural changes due to fishing effects

    Science.gov (United States)

    Henriques, Sofia; Pais, Miguel Pessanha; Costa, Maria José; Cabral, Henrique Nogueira

    2013-05-01

    The present study analyzed the effects of seasonal variation on the stability of fish-based metrics and their capability to detect changes in fish assemblages, which is yet poorly understood despite the general idea that guilds are more resilient to natural variability than species abundances. Three zones subject to different levels of fishing pressure inside the Arrábida Marine Protected Area (MPA) were sampled seasonally. The results showed differences between warm (summer and autumn) and cold (winter and spring) seasons, with the autumn clearly standing out. In general, the values of the metrics density of juveniles, density of invertebrate feeders and density of omnivores increased in warm seasons, which can be attributed to differences in recruitment patterns, spawning migrations and feeding activity among seasons. The density of generalist/opportunistic individuals was sensitive to the effect of fishing, with higher values at zones with the lowest level of protection, while the density of individuals with high commercial value only responded to fishing in the autumn, due to a cumulative result of both juveniles and adults abundances during this season. Overall, this study showed that seasonal variability affects structural and functional features of the fish assemblage and that might influence the detection of changes as a result of anthropogenic pressures. The choice of a specific season, during warm sea conditions after the spawning period (July-October), seems to be more adequate to assess changes on rocky-reef fish assemblages.

  14. SEASONAL AVERAGE FLOW IN RÂUL NEGRU HYDROGRAPHIC BASIN

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    VIGH MELINDA

    2015-03-01

    Full Text Available The Râul Negru hydrographic basin is a well individualised physical-geographical unit inside the Braşov Depression. The flow is controlled by six hydrometric stations placed on the main river and on two important tributaries. The data base for seasonal flow analysis contains the discharges from 1950-2012. The results of data analysis show that there significant space-time differences between multiannual seasonal averages. Some interesting conclusions can be obtained by comparing abundant and scarce periods. Flow analysis was made using seasonal charts Q = f(T. The similarities come from the basin’s relative homogeneity, and the differences from flow’s evolution and trend. Flow variation is analysed using variation coefficient. In some cases appear significant Cv values differences. Also, Cv values trends are analysed according to basins’ average altitude.

  15. Investigation of Seasonal and Latitudinal Effects on the Expression of Clock Genes in Drosophila

    Science.gov (United States)

    Hosseini, Seyede Sanaz; Nazarimehr, Fahimeh; Jafari, Sajad

    The primary goal in this work is to develop a dynamical model capturing the influence of seasonal and latitudinal variations on the expression of Drosophila clock genes. To this end, we study a specific dynamical system with strange attractors that exhibit changes of Drosophila activity in a range of latitudes and across different seasons. Bifurcations of this system are analyzed to peruse the effect of season and latitude on the behavior of clock genes. Existing experimental data collected from the activity of Drosophila melanogaster corroborate the dynamical model.

  16. Diversity and abundance of aquatics macroinvertebrates and water quality from high and low watersheds of Gariche River, Chiriqui province, Republic of Panama

    International Nuclear Information System (INIS)

    Guinard, Johana del C; Rios, Tomas; Bernal Vega, Juan A

    2013-01-01

    Diversity and abundance of aquatic microinvertebrate and quality of water in four sampling stations located in Gariche river high and low watersheds, during the dry season (January to April) and the rainy season (July to October) of 2010, were determined using methods described by Pino and Bernal (2009). A total of 4 964 individuals, belonging to 50 genera, 30 families and nine orders of class Insecta were identified. The average of the Shannon-Weaver Diversity Index in the dry season was 2.36 and 1.95 in rainy season, representing a middle diversity in this ecosystem. In dry season, the abundance of individuals was higher in the order Hemiptera, family Veliidae, and genus Rhagovelia followed by Trichoptera, family Hydroptilidae, and genus Atanatolica. In rainy season, the most representative orders were Ephemeroptera, family Leptophlebiidae and genus Thraulodes, followed by Hemiptera, family Veliidae and genus Rhagovelia. The Jaccard Index indicated that the stations with the greatest similarity were 1 and 2, with a 65.2 % (dry season) and 76.9 % (rainy season), while the similarity was low between stations 1 and 3, with 33.3 % (dry season) and 41.7 % (rainy season). The Biotic Index BMWP/PAN for the dry and rainy seasons, indicated a regular water quality for stations 1 and 2, but with acceptable quality at stations 3 and 4. The physic and chemical variables showed values within acceptable limits during the dry season, while in the rainy season the levels were low, according to the values established by the primary environmental quality standards and quality levels for freshwater recreational use without direct contact, influencing in the heterogeneity of aquatic macroinvertebrates in each sampling station.

  17. Impact of physicochemical parameters on phytoplankton compositions and abundances in Selameko Manmade Reservoir, Debre Tabor, South Gondar, Ethiopia

    Science.gov (United States)

    Wassie, Tilahun Adugna; Melese, Ayalew Wondie

    2017-07-01

    Impact of physicochemical parameters on 2 compositions and abundances in Selameko Reservoir, Debre Tabor, South Gondar from August 2009 to May 2010 was assessed. Water quality parameters, such as temperature, water transparency, water depth, dissolved oxygen, pH, total dissolved solids, phosphate, nitrate, and silicate were measured in situ from two sites (littoral and open water zone) of the reservoir. Phytoplankton compositions and abundances were analyzed in Tana fisheries and other aquatic organisms' research center. ANOVA result of the physicochemical parameters included chlorophyll-a showed the presence of significance difference among seasons and between sites ( P < 0.05). A total of seven families, 36 genera from three groups (Diatom, Blue green algae and Green algae) of phytoplankton were identified during the study period. From all groups, diatoms were the most abundant at both sites and Blue green algae were the least abundant. ANOVA of all phytoplankton showed highly significant difference among seasons and between sites ( P < 0.05). ANOVA of all phytoplankton showed highly significant difference among seasons and between sites ( P < 0.05). Based on the stepwise regression, a total number of phytoplanktons had positive correlation with some of the physicochemical parameters (R2 = 0.99, P < 0.001, N = 16). The study concluded that some of physicochemical parameters (NO3-N and PO4-P) indicated the presence of reservoir water pollution. This is supported by the presence of pollution-resistant phytoplankton species such as Melosira and Microcystis. The reservoir water was eutrophic (productive) throughout the year. To avoid such pollution, basin and reservoir management are recommended.

  18. Seasonal fluctuations of small mammal and flea communities in a Ugandan plague focus: evidence to implicate Arvicanthis niloticus and Crocidura spp. as key hosts in Yersinia pestis transmission.

    Science.gov (United States)

    Moore, Sean M; Monaghan, Andrew; Borchert, Jeff N; Mpanga, Joseph T; Atiku, Linda A; Boegler, Karen A; Montenieri, John; MacMillan, Katherine; Gage, Kenneth L; Eisen, Rebecca J

    2015-01-08

    The distribution of human plague risk is strongly associated with rainfall in the tropical plague foci of East Africa, but little is known about how the plague bacterium is maintained during periods between outbreaks or whether environmental drivers trigger these outbreaks. We collected small mammals and fleas over a two year period in the West Nile region of Uganda to examine how the ecological community varies seasonally in a region with areas of both high and low risk of human plague cases. Seasonal changes in the small mammal and flea communities were examined along an elevation gradient to determine whether small mammal and flea populations exhibit differences in their response to seasonal fluctuations in precipitation, temperature, and crop harvests in areas within (above 1300 m) and outside (below 1300 m) of a model-defined plague focus. The abundance of two potential enzootic host species (Arvicanthis niloticus and Crocidura spp.) increased during the plague season within the plague focus, but did not show the same increase at lower elevations outside this focus. In contrast, the abundance of the domestic rat population (Rattus rattus) did not show significant seasonal fluctuations regardless of locality. Arvicanthis niloticus abundance was negatively associated with monthly precipitation at a six month lag and positively associated with current monthly temperatures, and Crocidura spp. abundance was positively associated with precipitation at a three month lag and negatively associated with current monthly temperatures. The abundance of A. niloticus and Crocidura spp. were both positively correlated with the harvest of millet and maize. The association between the abundance of several small mammal species and rainfall is consistent with previous models of the timing of human plague cases in relation to precipitation in the West Nile region. The seasonal increase in the abundance of key potential host species within the plague focus, but not outside of

  19. Constraining Parameter Uncertainty in Simulations of Water and Heat Dynamics in Seasonally Frozen Soil Using Limited Observed Data

    Directory of Open Access Journals (Sweden)

    Mousong Wu

    2016-02-01

    Full Text Available Water and energy processes in frozen soils are important for better understanding hydrologic processes and water resources management in cold regions. To investigate the water and energy balance in seasonally frozen soils, CoupModel combined with the generalized likelihood uncertainty estimation (GLUE method was used. Simulation work on water and heat processes in frozen soil in northern China during the 2012/2013 winter was conducted. Ensemble simulations through the Monte Carlo sampling method were generated for uncertainty analysis. Behavioral simulations were selected based on combinations of multiple model performance index criteria with respect to simulated soil water and temperature at four depths (5 cm, 15 cm, 25 cm, and 35 cm. Posterior distributions for parameters related to soil hydraulic, radiation processes, and heat transport indicated that uncertainties in both input and model structures could influence model performance in modeling water and heat processes in seasonally frozen soils. Seasonal courses in water and energy partitioning were obvious during the winter. Within the day-cycle, soil evaporation/condensation and energy distributions were well captured and clarified as an important phenomenon in the dynamics of the energy balance system. The combination of the CoupModel simulations with the uncertainty-based calibration method provides a way of understanding the seasonal courses of hydrology and energy processes in cold regions with limited data. Additional measurements may be used to further reduce the uncertainty of regulating factors during the different stages of freezing–thawing.

  20. Wetland characteristics linked to broad-scale patterns in Culiseta melanura abundance and eastern equine encephalitis virus infection.

    Science.gov (United States)

    Skaff, Nicholas K; Armstrong, Philip M; Andreadis, Theodore G; Cheruvelil, Kendra S

    2017-10-18

    Eastern equine encephalitis virus (EEEV) is an expanding mosquito-borne threat to humans and domestic animal populations in the northeastern United States. Outbreaks of EEEV are challenging to predict due to spatial and temporal uncertainty in the abundance and viral infection of Cs. melanura, the principal enzootic vector. EEEV activity may be closely linked to wetlands because they provide essential habitat for mosquito vectors and avian reservoir hosts. However, wetlands are not homogeneous and can vary by vegetation, connectivity, size, and inundation patterns. Wetlands may also have different effects on EEEV transmission depending on the assessed spatial scale. We investigated associations between wetland characteristics and Cs. melanura abundance and infection with EEEV at multiple spatial scales in Connecticut, USA. Our findings indicate that wetland vegetative characteristics have strong associations with Cs. melanura abundance. Deciduous and evergreen forested wetlands were associated with higher Cs. melanura abundance, likely because these wetlands provide suitable subterranean habitat for Cs. melanura development. In contrast, Cs. melanura abundance was negatively associated with emergent and scrub/shrub wetlands, and wetland connectivity to streams. These relationships were generally strongest at broad spatial scales. Additionally, the relationships between wetland characteristics and EEEV infection in Cs. melanura were generally weak. However, Cs. melanura abundance was strongly associated with EEEV infection, suggesting that wetland-associated changes in abundance may be indirectly linked to EEEV infection in Cs. melanura. Finally, we found that wet hydrological conditions during the transmission season and during the fall/winter preceding the transmission season were associated with higher Cs. melanura abundance and EEEV infection, indicating that wet conditions are favorable for EEEV transmission. These results expand the broad-scale understanding

  1. A framework for improving a seasonal hydrological forecasting system using sensitivity analysis

    Science.gov (United States)

    Arnal, Louise; Pappenberger, Florian; Smith, Paul; Cloke, Hannah

    2017-04-01

    Seasonal streamflow forecasts are of great value for the socio-economic sector, for applications such as navigation, flood and drought mitigation and reservoir management for hydropower generation and water allocation to agriculture and drinking water. However, as we speak, the performance of dynamical seasonal hydrological forecasting systems (systems based on running seasonal meteorological forecasts through a hydrological model to produce seasonal hydrological forecasts) is still limited in space and time. In this context, the ESP (Ensemble Streamflow Prediction) remains an attractive forecasting method for seasonal streamflow forecasting as it relies on forcing a hydrological model (starting from the latest observed or simulated initial hydrological conditions) with historical meteorological observations. This makes it cheaper to run than a standard dynamical seasonal hydrological forecasting system, for which the seasonal meteorological forecasts will first have to be produced, while still producing skilful forecasts. There is thus the need to focus resources and time towards improvements in dynamical seasonal hydrological forecasting systems which will eventually lead to significant improvements in the skill of the streamflow forecasts generated. Sensitivity analyses are a powerful tool that can be used to disentangle the relative contributions of the two main sources of errors in seasonal streamflow forecasts, namely the initial hydrological conditions (IHC; e.g., soil moisture, snow cover, initial streamflow, among others) and the meteorological forcing (MF; i.e., seasonal meteorological forecasts of precipitation and temperature, input to the hydrological model). Sensitivity analyses are however most useful if they inform and change current operational practices. To this end, we propose a method to improve the design of a seasonal hydrological forecasting system. This method is based on sensitivity analyses, informing the forecasters as to which element of

  2. Use of Atlantic Forest protected areas by free-ranging dogs: estimating abundance and persistence of use

    Science.gov (United States)

    Paschoal, Ana Maria; Massara, Rodrigo; Bailey, Larissa L.; Kendall, William L.; Doherty, Paul F.; Hirsch, Andre; Chiarello, Adriano; Paglia, Adriano

    2016-01-01

    Worldwide, domestic dogs (Canis familiaris) are one of the most common carnivoran species in natural areas and their populations are still increasing. Dogs have been shown to impact wildlife populations negatively, and their occurrence can alter the abundance, behavior, and activity patterns of native species. However, little is known about abundance and density of the free-ranging dogs that use protected areas. Here, we used camera trap data with an open-robust design mark–recapture model to estimate the number of dogs that used protected areas in Brazilian Atlantic Forest. We estimated the time period these dogs used the protected areas, and explored factors that influenced the probability of continued use (e.g., season, mammal richness, proportion of forest), while accounting for variation in detection probability. Dogs in the studied system were categorized as rural free-ranging, and their abundance varied widely across protected areas (0–73 individuals). Dogs used protected areas near human houses for longer periods (e.g., >50% of sampling occasions) compared to more distant areas. We found no evidence that their probability of continued use varied with season or mammal richness. Dog detection probability decreased linearly among occasions, possibly due to the owners confining their dogs after becoming aware of our presence. Comparing our estimates to those for native carnivoran, we found that dogs were three to 85 times more abundant than ocelots (Leopardus pardalis), two to 25 times more abundant than puma (Puma concolor), and approximately five times more abundant than the crab-eating fox (Cerdocyon thous). Combining camera trapping data with modern mark–recapture methods provides important demographic information on free-ranging dogs that can guide management strategies to directly control dogs' abundance and ranging behavior.

  3. Submerged macrophytes shape the abundance and diversity of bacterial denitrifiers in bacterioplankton and epiphyton in the Shallow Fresh Lake Taihu, China.

    Science.gov (United States)

    Fan, Zhou; Han, Rui-Ming; Ma, Jie; Wang, Guo-Xiang

    2016-07-01

    nirK and nirS genes are important functional genes involved in the denitrification pathway. Recent studies about these two denitrifying genes are focusing on sediment and wastewater microbe. In this study, we conducted a comparative analysis of the abundance and diversity of denitrifiers in the epiphyton of submerged macrophytes Potamogeton malaianus and Ceratophyllum demersum as well as in bacterioplankton in the shallow fresh lake Taihu, China. Results showed that nirK and nirS genes had significant different niches in epiphyton and bacterioplankton. Bacterioplankton showed greater abundance of nirK gene in terms of copy numbers and lower abundance of nirS gene. Significant difference in the abundance of nirK and nirS genes also existed between the epiphyton from different submerged macrophytes. Similar community diversity yet different community abundance was observed between epiphytic bacteria and bacterioplankton. No apparent seasonal variation was found either in epiphytic bacteria or bacterioplankton; however, environmental parameters seemed to have direct relevancy with nirK and nirS genes. Our study suggested that submerged macrophytes have greater influence than seasonal parameters in shaping the presence and abundance of bacterial denitrifiers. Further investigation needs to focus on the potential contact and relative contribution between denitrifiers and environmental factors.

  4. Discrete two-sex models of population dynamics: On modelling the mating function

    Science.gov (United States)

    Bessa-Gomes, Carmen; Legendre, Stéphane; Clobert, Jean

    2010-09-01

    Although sexual reproduction has long been a central subject of theoretical ecology, until recently its consequences for population dynamics were largely overlooked. This is now changing, and many studies have addressed this issue, showing that when the mating system is taken into account, the population dynamics depends on the relative abundance of males and females, and is non-linear. Moreover, sexual reproduction increases the extinction risk, namely due to the Allee effect. Nevertheless, different studies have identified diverse potential consequences, depending on the choice of mating function. In this study, we investigate the consequences of three alternative mating functions that are frequently used in discrete population models: the minimum; the harmonic mean; and the modified harmonic mean. We consider their consequences at three levels: on the probability that females will breed; on the presence and intensity of the Allee effect; and on the extinction risk. When we consider the harmonic mean, the number of times the individuals of the least abundant sex mate exceeds their mating potential, which implies that with variable sex-ratios the potential reproductive rate is no longer under the modeller's control. Consequently, the female breeding probability exceeds 1 whenever the sex-ratio is male-biased, which constitutes an obvious problem. The use of the harmonic mean is thus only justified if we think that this parameter should be re-defined in order to represent the females' breeding rate and the fact that females may reproduce more than once per breeding season. This phenomenon buffers the Allee effect, and reduces the extinction risk. However, when we consider birth-pulse populations, such a phenomenon is implausible because the number of times females can reproduce per birth season is limited. In general, the minimum or modified harmonic mean mating functions seem to be more suitable for assessing the impact of mating systems on population dynamics.

  5. Remotely Sensing Larval Population Dynamics of Rice Field Anophelines

    Science.gov (United States)

    Beck, Louisa R.; Dister, Sheri W.; Wood, Byron L.; Washino, Robert K.

    1997-01-01

    The primary objective of both studies was to determine if RS and GIS techniques could be used to distinguish between high and low larval-producing rice fields in California. Results of the first study suggested that early-season green-up and proximity to livestock pastures were positively correlated with high larval abundance. Based on the early-season spectral differences between high and low larval-producing fields, it appeared that canopy development and tillering influenced mosquito habitat quality. At that time, rice fields consisted of a mixture of plants and water, a combination that allowed An. freeborni females to lay eggs in partial sunlight, protected from both predators and wind. This established a population earlier in the season than in other, 'less-green' fields where tillering and plant emergence was too minimal for ovipositioning. The study also indicated the importance of the distance that a mosquito would have to fly in order to take a bloodmeal prior to ovipositing. These associations were fully explored in an expanded study two years later. The second study confirmed the positive relationship between early season canopy development and larval abundance, and also demonstrated the relationship between abundance and distance-to-pasture. The association between greenness (as measured using NDVI), distance-to-pasture, and abundance is illustrated. The second study also indicated the siginificance of the landscape context of rice fields for larval production. Fields that included opportunities for feeding and resting within the flight range of the mosquito had higher abundances than did fields that were in a homogeneous rice area.

  6. Planktonic food web structure at a coastal time-series site: I. Partitioning of microbial abundances and carbon biomass

    Science.gov (United States)

    Caron, David A.; Connell, Paige E.; Schaffner, Rebecca A.; Schnetzer, Astrid; Fuhrman, Jed A.; Countway, Peter D.; Kim, Diane Y.

    2017-03-01

    Biogeochemistry in marine plankton communities is strongly influenced by the activities of microbial species. Understanding the composition and dynamics of these assemblages is essential for modeling emergent community-level processes, yet few studies have examined all of the biological assemblages present in the plankton, and benchmark data of this sort from time-series studies are rare. Abundance and biomass of the entire microbial assemblage and mesozooplankton (>200 μm) were determined vertically, monthly and seasonally over a 3-year period at a coastal time-series station in the San Pedro Basin off the southwestern coast of the USA. All compartments of the planktonic community were enumerated (viruses in the femtoplankton size range [0.02-0.2 μm], bacteria + archaea and cyanobacteria in the picoplankton size range [0.2-2.0 μm], phototrophic and heterotrophic protists in the nanoplanktonic [2-20 μm] and microplanktonic [20-200 μm] size ranges, and mesozooplankton [>200 μm]. Carbon biomass of each category was estimated using standard conversion factors. Plankton abundances varied over seven orders of magnitude across all categories, and total carbon biomass averaged approximately 60 μg C l-1 in surface waters of the 890 m water column over the study period. Bacteria + archaea comprised the single largest component of biomass (>1/3 of the total), with the sum of phototrophic protistan biomass making up a similar proportion. Temporal variability at this subtropical station was not dramatic. Monthly depth-specific and depth-integrated biomass varied 2-fold at the station, while seasonal variances were generally web structure and function at this coastal observatory.

  7. Dynamics of Phenol Degrading-Iron ReducingBacteria{1mm in Intensive Rice Cropping System

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Field and greenhouse experiments were conducted to investigate theeffects of cropping season, nitrogen fertilizer input and aeratedfallow on the dynamics of phenol degrading-iron reducingbacteria (PD-IRB) in tropical irrigated rice ({ Oryza sativa L.)systems. The PD-IRB population density was monitored at different stagesof rice growth in two cropping seasons (dry and early wet) in acontinuous annual triple rice cropping system under irrigated condition.In this system, the high nitrogen input (195 and 135 kg N ha-1 indry and wet seasons, respectively) plots and control plots receiving noN fertilizer were compared to investigate the effect of nitrogen rate onpopulation size. The phenol degrading-iron reducing bacteria (PD-IRB)were abundant in soils under cropping systems of tropical irrigatedrice. However, density of the bacterial populations varied with ricegrowth stages. Cropping seasons, rhizosphere, and aerated fallow couldaffect the dynamics of PD-IRB. In the field trial, viable counts ofPD-IRB in the topsoil layer (15 cm) ranged between 102 and 108cells per gram of dry soil. A steep increase in viable counts during thesecond half of the cropping season suggested that the population densityof PD-IRB increased at advanced crop-growth stages. Population growth ofPD-IRB was accelerated during the dry season compared to the wet season.In the greenhouse experiment, the adjacent aerated fallow revealed 1-2orders of magnitude higher in most probable number (MPN) of PD-IRB thanthe wet fallow treated plots. As a prominent group of Fe reducingbacteria, PD-IRB predominated in the rhizosphere of rice, since maximumMPN of PD-IRB (2.62108 g-1 soil) was found in rhizospheresoil. Mineral N fertilizer rates showed no significant effect on PD-IRBpopulation density.

  8. Characterization and risk assessment of seasonal and weather dynamics in organic pollutant mixtures from discharge of a separate sewer system.

    Science.gov (United States)

    Beckers, Liza-Marie; Busch, Wibke; Krauss, Martin; Schulze, Tobias; Brack, Werner

    2018-05-15

    Sites of wastewater discharge are hotspots for pollution of freshwaters with organic micropollutants and are often associated with adverse effects to aquatic organisms. The assessment, monitoring and managment of these hotspots is challenged by variations in the pollutant mixture composition due to season, weather conditions and random spills. In this study, we unraveled temporal exposure patterns in organic micropollutant mixtures from wastewater discharge and analyzed respective acute and sublethal risks for aquatic organisms. Samples were taken from two components of a separate sewer system i) a wastewater treatment plant (WWTP) and ii) a rain sewer of a medium size town as well as from the receiving river in different seasons. Rain sewer samples were separately collected for rain and dry - weather conditions. We analyzed 149 compounds by liquid chromatography-tandem mass spectrometry (LC-MS/MS). By considering the pollution dynamics in the point sources, we reduced the complexity of pollutant mixtures by k-means clustering to a few emission groups representing temporal and weather-related pollution patterns. From these groups, we derived biological quality element (BQE) - specific risk patterns. In most cases, one main risk driving emission group and a few individual risk driving compounds were identified for each BQE. While acute risk for fish was quite low, algae were exposed to seasonally emitted herbicides (terbuthylazine, spiroxamine) and crustaceans to randomly spilled insecticides (diazinon, dimethoate). Sublethal risks for all BQE were strongly influenced by constantly emitted pollutants, above all, pharmaceuticals. Variability of risks in the river was mainly driven by water discharge of the river rather than by season or peak events. Overall, the studied WWTP represented the major pollution source with a specific emission of agricultural compounds. However, the investigated rain sewer showed to be a constant pollution source due to illicit connections

  9. Examining the patterns and dynamics of species abundance distributions in succession of forest communities by model selection

    Science.gov (United States)

    Luo, Shao-Ming; Chen, Ping; He, Xiao; Guo, Wei; Li, Bailian

    2018-01-01

    There are a few common species and many rare species in a biological community or a multi-species collection in given space and time. This hollow distribution curve is called species abundance distribution (SAD). Few studies have examined the patterns and dynamics of SADs during the succession of forest communities by model selection. This study explored whether the communities in different successional stages followed different SAD models and whether there existed a best SAD model to reveal their intrinsic quantitative features of structure and dynamics in succession. The abundance (the number of individuals) of each vascular plant was surveyed by quadrat sampling method from the tree, shrub and herb layers in two typical communities (i.e., the evergreen needle- and broad-leaved mixed forest and the monsoon evergreen broad-leaved forest) in southern subtropical Dinghushan Biosphere Reserve, South China. The sites of two forest communities in different successional stages are both 1 ha in area. We collected seven widely representative SAD models with obviously different function forms and transformed them into the same octave (log2) scale. These models are simultaneously confronted with eight datasets from four layers of two communities, and their goodness-of-fits to the data were evaluated by the chi-squared test, the adjusted coefficient of determination and the information criteria. The results indicated that: (1) the logCauchy model followed all the datasets and was the best among seven models; (2) the fitness of each model to the data was not directly related to the successional stage of forest community; (3) according to the SAD curves predicted by the best model (i.e., the logCauchy), the proportion of rare species decreased but that of common ones increased in the upper layers with succession, while the reverse was true in the lower layers; and (4) the difference of the SADs increased between the upper and the lower layers with succession. We concluded that

  10. Water-use advantage for lianas over trees in tropical seasonal forests

    NARCIS (Netherlands)

    Chen, Y.J.; Cao, K.F.; Schnitzer, S.A.; Fan, Z.X.; Zhang, J.L.; Bongers, F.

    2015-01-01

    •Lianas exhibit peak abundance in tropical forests with strong seasonal droughts, the eco-physiological mechanisms associated with lianas coping with water deficits are poorly understood. •We examined soil water partitioning, sap flow, and canopy eco-physiological properties for 99 individuals of 15

  11. Seasonal Pattern of Decomposition and N, P, and C Dynamics in Leaf litter in a Mongolian Oak Forest and a Korean Pine Plantation

    Directory of Open Access Journals (Sweden)

    Jaeeun Sohng

    2014-10-01

    Full Text Available Distinct seasons and diverse tree species characterize temperate deciduous forests in NE Asia, but large areas of deciduous forests have been converted to conifer plantations. This study was conducted to understand the effects of seasons and tree species on leaf litter decomposition in a temperate forest. Using the litterbag method, the decomposition rate and nitrogen, phosphorous, and carbon dynamics of Mongolian oak (Quercus mongolica, Korean pine (Pinus koraiensis, and their mixed leaf litter were compared for 24 months in a Mongolian oak stand, an adjacent Korean pine plantation, and a Mongolian oak—Korean pine mixed stand. The decomposition rates of all the leaf litter types followed a pattern of distinct seasonal changes: most leaf litter decomposition occurred during the summer. Tree species was less influential on the leaf litter decomposition. The decomposition rates among different leaf litter types within the same stand were not significantly different, indicating no mixed litter effect. The immobilization of leaf litter N and P lasted for 14 months. Mongolian oak leaf litter and Korean pine leaf litter showed different N and P contents and dynamics during the decomposition, and soil P2O5 was highest in the Korean pine plantation, suggesting effects of plantation on soil nutrient budget.

  12. [Mammals' camera-trapping in Sierra Nanchititla, Mexico: relative abundance and activity patterns].

    Science.gov (United States)

    Monroy-Vilchis, Octavio; Zarco-González, Martha M; Rodríguez-Soto, Clarita; Soria-Díaz, Leroy; Urios, Vicente

    2011-03-01

    Species conservation and their management depend on the availability of their population behavior and changes in time. This way, population studies include aspects such as species abundance and activity pattern, among others, with the advantage that nowadays new technologies can be applied, in addition to common methods. In this study, we used camera-traps to obtain the index of relative abundance and to establish activity pattern of medium and large mammals in Sierra Nanchititla, Mexico. The study was conducted from December 2003 to May 2006, with a total sampling effort of 4 305 trap-days. We obtained 897 photographs of 19 different species. Nasua narica, Sylvilagus floridanus and Urocyon cinereoargenteus were the most abundant, in agreement with the relative abundance index (RAI, number of independent records/100 trap-days), and according to previous studies with indirect methods in the area. The activity patterns of the species showed that 67% of them are nocturnal, except Odocoileus virginianus, Nasua narica and others. Some species showed differences with previously reported patterns, which are related with seasonality, resources availability, organism sex, principally. The applied method contributed with reliable data about relative abundance and activity patterns.

  13. The Effect of Community-Based Soil and Water Conservation Practices on Abundance and Diversity of Soil Macroinvertebrates in the Northern Highlands of Ethiopia

    Directory of Open Access Journals (Sweden)

    Mengistu Welemariam

    2018-04-01

    Full Text Available Soil and water conservation (SWC practices in the northern highlands of Ethiopia have important implications for land restoration and biodiversity recovery. The present study determined soil macroinvertebrate (SMI abundance and diversity in response to spatial conditions i.e., generated by different conservation practices, soil depth, and temporal seasonality with the wet and dry season. The SWC practices considered were exclosure + terrace, exclosure alone, terraces, and non-conserved grazing lands. Each SWC measure was selected in three sites that were considered as replications due to low heterogeneity in terms of human and livestock disturbances and biophysical factors. Soil macroinvertebrates were collected using a monolith according to tropical soil biology and fertility (TSBF method. The highest density (55% of SMI was found in exclosures followed by terraces 26%. Non-conserved communal grazing lands account for only 19% of the total. Shannon diversity index was significantly (P < 0.05 higher (1.21 in the exclosures supported with terraces and the lowest (0.9 was observed in the non-conserved communal grazing lands. Diversity was also significantly (P < 0.05 higher (1.26 in wet than dry season (0.70. The highest (41% Sorensen similarity index among SMI was found between exclosures with terraces and exclosures alone during the wet season. The lowest (20% Sorensen similarity index was found between terraces alone and exclosures with terraces in dry season. Soil macroinvertebrate abundance was higher in upper (0–10 cm than lower (10–20 and 20–30 cm soil depth. Soil macroinvertebrate abundance was positively and strongly correlated with soil moisture (R2 = 0.85 and soil organic carbon stock (R2 = 0.95. However, it was negatively (R2 = −0.71 correlated with bulk density. Generally, the abundance and diversity of SMI increased as exclosures and communal grazing lands are supported with terraces.

  14. Influence of seasonality and gestation on habitat selection by northern Mexican gartersnakes (Thamnophis eques megalops.

    Directory of Open Access Journals (Sweden)

    Tiffany A Sprague

    Full Text Available Species conservation requires a thorough understanding of habitat requirements. The northern Mexican gartersnake (Thamnophis eques megalops was listed as threatened under the U.S. Endangered Species Act in 2014. Natural resource managers are interested in understanding the ecology of this subspecies to guide management decisions and to determine what features are necessary for habitat creation and restoration. Our objective was to identify habitat selection of northern Mexican gartersnakes in a highly managed, constructed wetland hatchery. We deployed transmitters on 42 individual gartersnakes and documented use of habitat types and selection of specific habitat features. Habitat selection was similar between males and females and varied seasonally. During the active season (March-October, gartersnakes primarily selected wetland edge habitat with abundant cover. Gestating females selected similar locations but with less dense cover. During the inactive season (November-February, gartersnakes selected upland habitats, including rocky slopes with abundant vegetation. These results of this study can help inform management of the subspecies, particularly in human-influenced habitats. Conservation of this subspecies should incorporate a landscape-level approach that includes abundant wetland edge habitat with a mosaic of dense cover for protection and sparsely vegetated areas for basking connected to terrestrial uplands for overwintering.

  15. Richness and Abundance of Ichneumonidae in a Fragmented Tropical Rain Forest.

    Science.gov (United States)

    Ruiz-Guerra, B; Hanson, P; Guevara, R; Dirzo, R

    2013-10-01

    Because of the magnitude of land use currently occurring in tropical regions, the local loss of animal species due to habitat fragmentation has been widely studied, particularly in the case of vertebrates. Many invertebrate groups and the ichneumonid wasps in particular, however, have been poorly studied in this context, despite the fact that they are one of the most species-rich groups and play an important role as regulators of other insect populations. Here, we recorded the taxonomic composition of ichneumonid parasitoids and assessed their species richness, abundance, similarity, and dominance in the Los Tuxtlas tropical rain forest, Mexico. We compared two forest types: a continuous forest (640 ha) and a forest fragment (19 ha). We sampled ichneumonids using four malaise traps in both forest types during the dry (September-October) and rainy (March-April) seasons. A total of 104 individuals of Ichneumonidae belonging to 11 subfamilies, 18 genera, and 42 species were collected in the continuous forest and 11 subfamilies, 15 genera, and 24 species were collected in the forest fragment. Species richness, abundance, and diversity of ichneumonids were greater in the continuous forest than in the forest fragment. We did not detect differences between seasons. Species rank/abundance curves showed that the ichneumonid community between the forest types was different. Species similarity between forest types was low. The most dominant species in continuous forest was Neotheronia sp., whereas in the forest fragment, it was Orthocentrus sp. Changes in the ichneumonid wasp community may compromise important tropical ecosystem processes.

  16. Galactic abundance gradients from Cepheids : α and heavy elements in the outer disk

    NARCIS (Netherlands)

    Lemasle, B.; Francois, P.; Genovali, K.; Kovtyukh, V. V.; Bono, G.; Inno, L.; Laney, C. D.; Kaper, L.; Bergemann, M.; Fabrizio, M.; Matsunaga, N.; Pedicelli, S.; Primas, F.; Romaniello, M.

    2013-01-01

    Context. Galactic abundance gradients set strong constraints to chemo-dynamical evolutionary models of the Milky Way. Given the period-luminosity relations that provide accurate distances and the large number of spectral lines, Cepheids are excellent tracers of the present-day abundance gradients.

  17. Fishers' knowledge identifies environmental changes and fish abundance trends in impounded tropical rivers.

    Science.gov (United States)

    Hallwass, Gustavo; Lopes, Priscila F; Juras, Anastácio A; Silvano, Renato A M

    2013-03-01

    The long-term impacts of large hydroelectric dams on small-scale fisheries in tropical rivers are poorly known. A promising way to investigate such impacts is to compare and integrate the local ecological knowledge (LEK) of resource users with biological data for the same region. We analyzed the accuracy of fishers' LEK to investigate fisheries dynamics and environmental changes in the Lower Tocantins River (Brazilian Amazon) downstream from a large dam. We estimated fishers' LEK through interviews with 300 fishers in nine villages and collected data on 601 fish landings in five of these villages, 22 years after the dam's establishment (2006-2008). We compared these two databases with each other and with data on fish landings from before the dam's establishment (1981) gathered from the literature. The data obtained based on the fishers' LEK (interviews) and from fisheries agreed regarding the primary fish species caught, the most commonly used type of fishing gear (gill nets) and even the most often used gill net mesh sizes but disagreed regarding seasonal fish abundance. According to the interviewed fishers, the primary environmental changes that occurred after the impoundment were an overall decrease in fish abundance, an increase in the abundance of some fish species and, possibly, the local extinction of a commercial fish species (Semaprochilodus brama). These changes were corroborated by comparing fish landings sampled before and 22 years after the impoundment, which indicated changes in the composition of fish landings and a decrease in the total annual fish production. Our results reinforce the hypothesis that large dams may adversely affect small-scale fisheries downstream and establish a feasible approach for applying fishers' LEK to fisheries management, especially in regions with a low research capacity.

  18. Seasonal abundance of equine strongyles (Nematoda: Strongylidae in the State of Rio de Janeiro, Brazil Abundância sazonal de estrongilídeos de eqüinos (Nematoda: Strongylidae no Estado do Rio de Janeiro

    Directory of Open Access Journals (Sweden)

    I.V.F. Martins

    2005-02-01

    Full Text Available The seasonal abundance of lumenal and larval forms of equine strongyles in the State of Rio de Janeiro, Brazil was evaluated. Thirty horses referred to the Federal Rural University of Rio de Janeiro were necropsied and their gastrointestinal tracts were separated into stomach, small intestine, cecum, ventral colon, dorsal colon and rectum. Two aliquots of 5% of the content were collected and examined for the presence of small strongyles and the rest of the content was examined for the presence of large strongyles. The mesenteric artery, liver, pancreas and peritoneum were examined for the presence of strongyle larvae. The mucosa of intestine segments was cut into parts of equal length, and each one was examined by the mural transillumination technique. Higher abundances of larvae of Strongylus equinus (PEstudou-se a ocorrência sazonal de formas larvares e adultas de estrongilídeos nas mucosas do estômago, intestino delgado, ceco, colon ventral, colon dorsal e reto de 30 eqüídeos no Estado do Rio de Janeiro. Os grandes estrongilídeos foram encontrados em todas as mucosas e duas alíquotas de 5% do conteúdo foram retiradas para a procura de pequenos estrongilídeos. Artéria mesentérica, fígado, pâncreas e peritônio foram também examinados para larvas de estrongilídeos. As mucosas foram examinadas pela técnica de transiluminação. Larvas de Strongylus equinus (P<0,10 e adultos de Strongylus vulgaris (P<0,05 foram mais abundantes na estação seca. Larvas escistadas de ciatostomíneos o foram na estação chuvosa (P<0,02.

  19. Genetic and environmental control of seasonal carbohydrate dynamics in trees of diverse Pinus sylvestris populations.

    Science.gov (United States)

    Oleksyn, J.; Zytkowiak, R.; Karolewski, P.; Reich, P. B.; Tjoelker, M. G.

    2000-06-01

    We explored environmental and genetic factors affecting seasonal dynamics of starch and soluble nonstructural carbohydrates in needle and twig cohorts and roots of Scots pine (Pinus sylvestris L.) trees of six populations originating between 49 degrees and 60 degrees N, and grown under common garden conditions in western Poland. Trees of each population were sampled once or twice per month over a 3-year period from age 15 to 17 years. Based on similarity in starch concentration patterns in needles, two distinct groups of populations were identified; one comprised northern populations from Sweden and Russia (59-60 degrees N), and another comprised central European populations from Latvia, Poland, Germany and France (49-56 degrees N). Needle starch concentrations of northern populations started to decline in late spring and reached minimum values earlier than those of central populations. For all populations, starch accumulation in spring started when minimum air temperature permanently exceeded 0 degrees C. Starch accumulation peaked before bud break and was highest in 1-year-old needles, averaging 9-13% of dry mass. Soluble carbohydrate concentrations were lowest in spring and summer and highest in autumn and winter. There were no differences among populations in seasonal pattern of soluble carbohydrate concentrations. Averaged across all populations, needle soluble carbohydrate concentrations increased from about 4% of needle dry mass in developing current-year needles, to about 9% in 1- and 2-year-old needles. Root carbohydrate concentration exhibited a bimodal pattern with peaks in spring and autumn. Northern populations had higher concentrations of fine-root starch in spring and autumn than central populations. Late-summer carbohydrate accumulation in roots started only after depletion of starch in needles and woody shoots. We conclude that Scots pine carbohydrate dynamics depend partially on inherited properties that are probably related to phenology of root

  20. Coccolithophore diversity and dynamics at a coastal site in the Gulf of Trieste (northern Adriatic Sea)

    Science.gov (United States)

    Cerino, Federica; Malinverno, Elisa; Fornasaro, Daniela; Kralj, Martina; Cabrini, Marina

    2017-09-01

    Two years-data (May 2011-February 2013) obtained from a monthly sampling carried out at the coastal long term Ecological Research station C1-LTER in the Gulf of Trieste (northern Adriatic Sea) were analysed to describe the seasonal dynamics and diversity of coccolithophore assemblages and to assess their relationship with environmental forcing. Coccolithophores represented 10.7% of the total Utermöhl phytoplankton that were mainly dominated by small (Emiliania huxleyi, and a secondary peak in May-June (0.7-15.0 · 104 coccospheres L-1), coinciding with the increase of the light intensity and the beginning of the seasonal stratification, dominated by holococcolithophores and small Syracosphaera species. The most abundant taxa were E. huxleyi and holococcolithophores, followed by Acanthoica quattrospina, Syracosphaera species and other minor species. Statistical analyses recognized four distinct groups, corresponding to seasonal variations of environmental conditions. Considering the two years, some species displayed a recurrent seasonal pattern highlighting possible species-specific ecological requirements, while others showed an interannual variability probably due to local factors.

  1. Seasonal dynamics of the inorganic pollution in a Niger Delta River ...

    African Journals Online (AJOL)

    The level of inorganic anions of the Eleme River over the rainy and dry season periods was investigated. Results indicated that parameters like temperature, conductivity and total dissolved solids were higher during the dry than rainy seasons. Others like pH, phosphate, sulfate and dissolved oxygen had higher rainy than ...

  2. Seasonality of Fruit-Feeding Butterflies (Lepidoptera, Nymphalidae) in a Brazilian Semiarid Area

    OpenAIRE

    Nobre, Carlos Eduardo Beserra; Iannuzzi, Luciana; Schlindwein, Clemens

    2012-01-01

    A survey of 6,000 trap/hours using fruit-bait traps was conducted, in order to characterize the community of fruit-feeding butterflies and their seasonal variation in a semiarid area of NE Brazil, which exhibits a highly seasonal rainfall regime. The community was composed of 15 species, the four most abundant comprising more than 80% of the total individuals. In the first sampling month, 80% of the species had already been recorded. A strong positive correlation was found between butterfly a...

  3. Investigating the role of evergreen and deciduous forests in the increasing trend in atmospheric CO2 seasonal amplitude

    Science.gov (United States)

    Welp, L.; Calle, L.; Graven, H. D.; Poulter, B.

    2017-12-01

    The seasonal amplitude of Northern Hemisphere atmospheric CO2 concentrations has systematically increased over the last several decades, indicating that the timing and amplitude of net CO2 uptake and release by northern terrestrial ecosystems has changed substantially. Remote sensing, dynamic vegetation modeling, and in-situ studies have explored how changes in phenology, expansion of woody vegetation, and changes in species composition and disturbance regimes, among others, are driven by changes in climate and CO2. Despite these efforts, ecosystem models have not been able to reproduce observed atmospheric CO2 changes. Furthermore, the implications for the source/sink balance of northern ecosystems remains unclear. Changing proportions of evergreen and deciduous tree cover in response to climate change could be one of the key mechanisms that have given rise to amplified atmospheric CO2 seasonality. These two different plant functional types (PFTs) have different carbon uptake seasonal patterns and also different sensitivities to climate change, but are often lumped together as one forest type in global ecosystem models. We will demonstrate the potential that shifting distributions of evergreen and deciduous forests can have on the amplitude of atmospheric CO2. We will show phase differences in the net CO2 seasonal uptake using CO2 flux data from paired evergreen/deciduous eddy covariance towers. We will use simulations of evergreen and deciduous PFTs from the LPJ dynamic vegetation model to explore how climate change may influence the abundance and CO2 fluxes of each. Model results show that the area of deciduous forests is predicted to have increased, and the seasonal amplitude of CO2 fluxes has increased as well. The impact of surface flux seasonal variability on atmospheric CO2 amplitude is examined by transporting fluxes from each forest PFT through the TM3 transport model. The timing of the most intense CO2 uptake leads to an enhanced effect of deciduous

  4. Native wildflower plantings support wild bee abundance and diversity in agricultural landscapes across the United States.

    Science.gov (United States)

    Williams, Neal M; Ward, Kimiora L; Pope, Nathaniel; Isaacs, Rufus; Wilson, Julianna; May, Emily A; Ellis, Jamie; Daniels, Jaret; Pence, Akers; Ullmann, Katharina; Peters, Jeff

    2015-12-01

    Global trends in pollinator-dependent crops have raised awareness of the need to support managed and wild bee populations to ensure sustainable crop production. Provision of sufficient forage resources is a key element for promoting bee populations within human impacted landscapes, particularly those in agricultural lands where demand for pollination service is high and land use and management practices have reduced available flowering resources. Recent government incentives in North America and Europe support the planting of wildflowers to benefit pollinators; surprisingly, in North America there has been almost no rigorous testing of the performance of wildflower mixes, or their ability to support wild bee abundance and diversity. We tested different wildflower mixes in a spatially replicated, multiyear study in three regions of North America where production of pollinator-dependent crops is high: Florida, Michigan, and California. In each region, we quantified flowering among wildflower mixes composed of annual and perennial species, and with high and low relative diversity. We measured the abundance and species richness of wild bees, honey bees, and syrphid flies at each mix over two seasons. In each region, some but not all wildflower mixes provided significantly greater floral display area than unmanaged weedy control plots. Mixes also attracted greater abundance and richness of wild bees, although the identity of best mixes varied among regions. By partitioning floral display size from mix identity we show the importance of display size for attracting abundant and diverse wild bees. Season-long monitoring also revealed that designing mixes to provide continuous bloom throughout the growing season is critical to supporting the greatest pollinator species richness. Contrary to expectation, perennials bloomed in their first season, and complementarity in attraction of pollinators among annuals and perennials suggests that inclusion of functionally diverse

  5. Sediment nitrogen cycling rates and microbial abundance along a submerged vegetation gradient in a eutrophic lake.

    Science.gov (United States)

    Yao, Lu; Chen, Chengrong; Liu, Guihua; Liu, Wenzhi

    2018-03-01

    Decline of submerged vegetation is one of the most serious ecological problems in eutrophic lakes worldwide. Although restoration of submerged vegetation is widely assumed to enhance ecological functions (e.g., nitrogen removal) and aquatic biodiversity, the evidence for this assumption is very limited. Here, we investigated the spatio-temporal patterns of sediment potential nitrification, unamended denitrification and N 2 O production rates along a vegetation gradient in the Lake Honghu, where submerged vegetation was largely restored by prohibiting net-pen aquaculture. We also used five functional genes as markers to quantify the abundance of sediment nitrifying and denitrifying microorganisms. Results showed that unvegetated sediments supported greater nitrification rates than rhizosphere sediments of perennial or seasonal vegetation. However, the absence of submerged vegetation had no significant effect on denitrification and N 2 O production rates. Additionally, the abundance of functional microorganisms in sediments was not significantly different among vegetation types. Season had a strong effect on both nitrogen cycling processes and microbial abundances. The highest nitrification rates were observed in September, while the highest denitrification rates occurred in December. The temporal variation of sediment nitrification, denitrification and N 2 O production rates could be due to changes in water quality and sediment properties rather than submerged vegetation and microbial abundances. Our findings highlight that vegetation restoration in eutrophic lakes improves water quality but does not enhance sediment nitrogen removal rates and microbial abundances. Therefore, for reducing the N level in eutrophic lakes, major efforts should be made to control nutrients export from terrestrial ecosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. First Investigation of Microbial Community Composition in the Bridge (Gadeok Channel) between the Jinhae-Masan Bay and the South Sea of Korea

    Science.gov (United States)

    Lee, Jiyoung; Lim, Jae-Hyun; Park, Junhyung; Youn, Seok-Hyun; Oh, Hyun-Ju; Kim, Ju-Hyoung; Kim, Myung Kyum; Cho, Hyeyoun; Yoon, Joo-Eun; Kim, Soyeon; Markkandan, Kesavan; Park, Ki-Tae; Kim, Il-Nam

    2018-02-01

    Microbial community composition varies based on seasonal dynamics (summer: strongly stratified water column; autumn: weakly stratified water column; winter: vertically homogeneous water column) and vertical distributions (surface, middle, and bottom depths) in the Gadeok Channel, which is the primary passage to exchange waters and materials between the Jinhae-Masan Bay and the South Sea waters. The microbial community composition was analyzed from June to December 2016 using 16S rRNA gene sequencing. The community was dominated by the phyla Proteobacteria (45%), Bacteroidetes (18%), Cyanobacteria (15%), Verrucomicrobia (6%), and Actinobacteria (6%). Alphaproteobacteria (29%) was the most abundant microbial class, followed by Flavobacteria (15%) and Gammaproteobacteria (15%) in all samples. The composition of the microbial communities was found to vary vertically and seasonally. The orders Flavobacteriales and Stramenopiles showed opposing seasonal patterns; Flavobacteriales was more abundant in August and December while Stramenopiles showed high abundance in June and October at all depths. The genus Synechococcus reached extremely high abundance (14%) in the June surface water column, but was much less abundant in December water columns. Clustering analysis showed that there was a difference in the microbial community composition pattern between the strongly stratified season and well-mixed season. These results indicate that the seasonal dynamics of physicochemical and hydrologic conditions throughout the water column are important parameters in shaping the microbial community composition in the Gadeok Channel.

  7. Pex35 is a regulator of peroxisome abundance

    DEFF Research Database (Denmark)

    Yofe, Ido; Soliman, Kareem; Chuartzman, Silvia G

    2017-01-01

    Peroxisomes are cellular organelles with vital functions in lipid, amino acid, and redox metabolism. The cellular formation and dynamics of peroxisomes are governed by PEX genes, however, the regulation of peroxisome abundance is yet poorly understood. Here we use a high-content microscopy screen...

  8. Characterizing and predicting the distribution of Baltic Sea flounder (Platichthys flesus) during the spawning season

    Science.gov (United States)

    Orio, Alessandro; Bergström, Ulf; Casini, Michele; Erlandsson, Mårten; Eschbaum, Redik; Hüssy, Karin; Lehmann, Andreas; Ložys, Linas; Ustups, Didzis; Florin, Ann-Britt

    2017-08-01

    Identification of essential fish habitats (EFH), such as spawning habitats, is important for nature conservation, sustainable fisheries management and marine spatial planning. Two sympatric flounder (Platichthys flesus) ecotypes are present in the Baltic Sea, pelagic and demersal spawning flounder, both displaying ecological and physiological adaptations to the low-salinity environment of this young inland sea. In this study we have addressed three main research questions: 1) What environmental conditions characterize the spatial distribution and abundance of adult flounder during the spawning season? 2) What are the main factors defining the habitats of the two flounder ecotypes during the spawning season? 3) Where are the potential spawning areas of flounder? We modelled catch per unit of effort (CPUE) of flounder from gillnet surveys conducted over the southern and central Baltic Sea in the spring of 2014 and 2015 using generalized additive models. A general model included all the stations fished during the survey while two other models, one for the demersal and one for the pelagic spawning flounder, included only the stations where each flounder ecotype should dominate. The general model captured distinct ecotype-specific signals as it identified dual salinity and water depth responses. The model for the demersal spawning flounder revealed a negative relation with the abundance of round goby (Neogobius melanostomus) and a positive relation with Secchi depth and cod abundance. Vegetation and substrate did not play an important role in the choice of habitat for the demersal ecotype. The model for the pelagic spawning flounder showed a negative relation with temperature and bottom current and a positive relation with salinity. Spatial predictions of potential spawning areas of flounder showed a decrease in habitat availability for the pelagic spawning flounder over the last 20 years in the central part of the Baltic Sea, which may explain part of the observed

  9. Effects of seasonal drawdowns on fish assemblages in sections of an impounded river-canal system in upstate New York

    Science.gov (United States)

    George, Scott D.; Baldigo, Barry P.; Wells, Scott M

    2016-01-01

    The Mohawk River and New York State Barge Canal run together as a series of permanent and temporary impoundments for most of the distance between Rome and Albany, New York. The downstream or lower section is composed of two permanent impoundments, the middle section of a series of temporary (seasonal) impoundments, and the upper section of a series of permanent impoundments. In the middle section, movable dams are lifted from the water during winter and the wetted surface area decreases by 36–56%. We used boat electrofishing during spring 2014 and 2015 to compare the relative abundance of fish populations and the composition of fish assemblages between the permanently and seasonally impounded sections of the Barge Canal and to infer the effects of the two flow management practices. A total of 3,264 individuals from 38 species were captured, and total catch per unit effort (CPUE) ranged from 46.0 to 134.7 fish/h at sites in the seasonally impounded section, compared with 140.0–342.0 fish/h in the permanent lower section and 89.0–282.0 fish/h in the permanent upper section. The amount of drawdown explained 55% of the variation in total CPUE and was a highly significant predictor variable. Mean total CPUE in the seasonally impounded section was significantly lower (by about 50%) than that in either permanently impounded section, and the assemblage composition differed significantly between sections. The relative abundance of many lentic species was markedly lower in the seasonally impounded section, while the relative abundance of several native cyprinids and the percentage of individuals belonging to species that are native to the watershed was greater in this section. Overall, these findings suggest that winter dam removal in impounded rivers may reduce the abundance of fish but may also create more natural riverine conditions that favor some native species.

  10. Abundance of thraustochytridsand bacteria in the equatorial Indian Ocean, in relation totransparent exopolymeric particles (TEPs)

    Digital Repository Service at National Institute of Oceanography (India)

    Damare, V.; Raghukumar, S.

    Thraustochytrid protists are often abundant in coastal waters. However, their population dynamics and substrate preferences in the oceanic water column are poorly understood.We studied the abundance and distribution of thraustochytrids, bacteria...

  11. Hydrologic variability governs population dynamics of a vulnerable amphibian in an arid environment.

    Directory of Open Access Journals (Sweden)

    Erin R Zylstra

    Full Text Available Dynamics of many amphibian populations are governed by the distribution and availability of water. Therefore, understanding the hydrological mechanisms that explain spatial and temporal variation in occupancy and abundance will improve our ability to conserve and recover populations of vulnerable amphibians. We used 16 years of survey data from intermittent mountain streams in the Sonoran Desert to evaluate how availability of surface water affected survival and adult recruitment of a threatened amphibian, the lowland leopard frog (Lithobates yavapaiensis. Across the entire study period, monthly survival of adults ranged from 0.72 to 0.99 during summer and 0.59 to 0.94 during winter and increased with availability of surface water (Z = 7.66; P < 0.01. Recruitment of frogs into the adult age class occurred primarily during winter and ranged from 1.9 to 3.8 individuals/season/pool; like survival, recruitment increased with availability of surface water (Z = 3.67; P < 0.01. Although abundance of frogs varied across seasons and years, we found no evidence of a systematic trend during the 16-year study period. Given the strong influence of surface water on population dynamics of leopard frogs, conservation of many riparian obligates in this and similar arid regions likely depends critically on minimizing threats to structures and ecosystem processes that maintain surface waters. Understanding the influence of surface-water availability on riparian organisms is particularly important because climate change is likely to decrease precipitation and increase ambient temperatures in desert riparian systems, both of which have the potential to alter fundamentally the hydrology of these systems.

  12. Seasonal variation in the abundance and distribution of Anomalocardia flexuosa (Mollusca, Bivalvia, Veneridae in an estuarine intertidal plain

    Directory of Open Access Journals (Sweden)

    Jacqueline S. Silva-Cavalcanti

    2018-02-01

    Full Text Available Spatial and temporal density and biomass of the infaunal mollusk Anomalocardia flexuosa (Linnaeus, 1767 evaluated a tidal plain at Goiana estuary (Northeast Brazil. Three hundred and sixty core samples were taken during an annual cycle from three intertidal habitats (A, B and C. Shell ranged from 2.20 to 28.48 mm (15.08 ± 4.08 mm. Recruitment occurred more intensely from January to March. Total (0–1,129 g m−2 differed seasons (rainy and dry, with highest values in the early rainy season (221.0 ± 231.44 g m−2; and lowest values in the late dry season (57.34 ± 97 g m−2. The lowest occurred during the late rainy (319 ± 259 ind m−2 and early dry (496 ± 607 ind m−2 seasons. Extreme environmental situations (e.g., river flow, salinity and water temperature at the end of each season also affected density ranges (late dry: 0–5,798 ind m−2; late rainy: 0–1,170 ind m−2. A. flexuosa in the Goiana estuary presented a dominance of juvenile individuals (shell length < 20 mm, with high biomass main the recruitment period. Average shell length, density and biomass values suggest overfishing of the stock unit. A. flexuosa is an important food and income resource along its whole distribution range. The species was previously also known as Anomalocardia brasiliana (Gmelin, 1791.

  13. Viral prevalence increases with regional colony abundance in honey bee drones (Apis mellifera L).

    Science.gov (United States)

    Forfert, Nadège; Natsopoulou, Myrsini E; Paxton, Robert J; Moritz, Robin F A

    2016-10-01

    Transmission among colonies is a central feature for the epidemiology of honey bee pathogens. High colony abundance may promote transmission among colonies independently of apiary layout, making colony abundance a potentially important parameter determining pathogen prevalence in populations of honey bees. To test this idea, we sampled male honey bees (drones) from seven distinct drone congregation areas (DCA), and used their genotypes to estimate colony abundance at each site. A multiplex ligation dependent probe amplification assay (MLPA) was used to assess the prevalence of ten viruses, using five common viral targets, in individual drones. There was a significant positive association between colony abundance and number of viral infections. This result highlights the potential importance of high colony abundance for pathogen prevalence, possibly because high population density facilitates pathogen transmission. Pathogen prevalence in drones collected from DCAs may be a useful means of estimating the disease status of a population of honey bees during the mating season, especially for localities with a large number of wild or feral colonies. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Specific microbial gene abundances and soil parameters contribute to C, N, and greenhouse gas process rates after land use change in Southern Amazonian Soils

    Directory of Open Access Journals (Sweden)

    Daniel Renato Lammel

    2015-10-01

    Full Text Available Ecological processes regulating soil carbon (C and nitrogen (N cycles are still poorly understood, especially in the world’s largest agricultural frontier in Southern Amazonia. We analyzed soil parameters in samples from pristine rainforest and after land use change to pasture and crop fields, and correlated them with abundance of functional and phylogenetic marker genes (amoA, nirK, nirS, norB, nosZ, nifH, mcrA, pmoA, and 16S/18S rRNA. Additionally, we integrated these parameters using path analysis and multiple regressions. Following forest removal, concentrations of soil C and N declined, and pH and nutrient levels increased, which influenced microbial abundances and biogeochemical processes. A seasonal trend was observed, suggesting that abundances of microbial groups were restored to near native levels after the dry winter fallow. Integration of the marker gene abundances with soil parameters using path analysis and multiple regressions provided good predictions of biogeochemical processes, such as the fluxes of NO3, N2O, CO2, and CH4. In the wet season, agricultural soil showed the highest abundance of nitrifiers (amoA and Archaea, however forest soils showed the highest abundances of denitrifiers (nirK, nosZ and high N, which correlated with increased N2O emissions. Methanogens (mcrA and methanotrophs (pmoA were more abundant in forest soil, but methane flux was highest in pasture sites, which was related to soil compaction. Rather than analyzing direct correlations, the data integration using multivariate tools provided a better overview of biogeochemical processes. Overall, in the wet season, land use change from forest to agriculture reduced the abundance of different functional microbial groups related to the soil C and N cycles; integrating the gene abundance data and soil parameters provided a comprehensive overview of these interactions. Path analysis and multiple regressions addressed the need for more comprehensive approaches

  15. Forage yield and nitrogen nutrition dynamics of warm-season native forage genotypes under two shading levels and in full sunlight

    OpenAIRE

    Barro,Raquel Santiago; Varella,Alexandre Costa; Lemaire,Gilles; Medeiros,Renato Borges de; Saibro,João Carlos de; Nabinger,Carlos; Bangel,Felipe Villamil; Carassai,Igor Justin

    2012-01-01

    The successful achievement of a highly productive understorey pasture in silvopastoral systems depends on the use of well-adapted forage genotypes, showing good agronomic performance and persistence under shading and grazing. In this study, the herbage dry matter yield (DMY) and nitrogen nutrition dynamics were determined in three native warm-season grasses (Paspalum regnellii, Paspalum dilatatum and Paspalum notatum) and a forage legume (Arachis pintoi) under two shading levels compared with...

  16. Kelimpahan dan Keanekaragaman Plankton di Perairan Selat Bali (Plankton Abundance and Diversity in the Bali Strait

    Directory of Open Access Journals (Sweden)

    Ruly Isfatul Khasanah

    2013-12-01

    transitional season in November 2012 and the west season in February 2013. This research was done to observe the differences in the abundance and diversity of plankton in the two monsoon seasons. Water sample and plankton sample were collected simultaneously at the same location. Water samples were taken using a water sampler, while plankton were taken by using a planktonnet with mesh size 20 μm. Samples were taken vertically and horizontally at a depth of 1 m and 20 m below the surface. The result of nutrient measurement at Bali Strait during transitional II season showed that the concentration of phosphate, nitrate, organic matter, sillica and chlorofill-a are higher than during west season. This result indicates that there is probably movement of water mass from deeper water column to shallower area. Phosphate and nitrate are required by phytoplankton to maintain their cell membrane and sillica are used to form cell wall, especially for diatom. The reasearch also revealed that diatom (Bacillariophyceae are 95,9 % of total species and abundance of phytoplankton, and the rest are Dinophyceae. It was found that highest abundance occur during transitional season was Rhizosolenia stolterfothii of 51.405 sel.L-1 (80,1 %. While during the west monsoon the Copepod had dominates at 8.178 cell.L-1 (88,3 %. These results indicate that with plankton abundance the Bali Strait has the potential to support pelagic marine life. Keywords: plankton, Bali strait, rhizosolenia stolterfothii, monsoon

  17. Environmental factors that determine the occurrence and seasonal dynamics of Aphanizomenon flos-aquae

    Directory of Open Access Journals (Sweden)

    Yoshimasa YAMAMOTO

    2009-02-01

    Full Text Available This study investigated the seasonal dynamics of two populations of Aphanizomenon flos-aquae Ralfs ex Bornet & Flahault var. flos-aquae and four populations of A. flos-aquae var. klebahnii Elenkin in eutrophic water bodies over 1 year from February 2006 to January 2007. The growth of A. flos-aquae var. flos-aquae was promoted at high temperatures even if in one case the biomass development was very low when other co-occurring cyanoprokaryotes (Anabaena spp. and Microcystis spp. were abundant. In contrast, the highest density of the other population of A. flos-aquae var. flos-aquae was observed in August when the population density of M. aeruginosa (Kützing Kützing reached an annual peak. A. flos-aquae var. flos-aquae usually bloomed in summer but could also tolerate low temperatures in the winter, and was present in relatively high densities. The populations of A. flos-aquae var. klebahnii observed in this study can be divided into three groups based on preferred temperature; three populations increased in winter, and the other increased in summer. Large biomasses of the low-temperature-adapted A. flos-aquae were observed mainly during winter when population densities of co-occurring cyanoprokaryotes (Anabaena spp., Microcystis spp. and Planktothrix raciborskii (Woloszynska Anagnostidis & Komárek were relatively low or almost absent. The increase in or existence of cooccurring cyanoprokaryotes during the summer resulted in a decrease of the A. flos-aquae population density. It was revealed that high temperatures (20-25 °C are suitable for maintaining A. flos-aquae var. klebahnii strains isolated from the study ponds, implying that low-temperature-adapted A. flos-aquae can grow over a wide range of water temperatures. The high-temperatureadapted A. flos-aquae var. klebahnii co-existed with M. aeruginosa during summer; however, its peak population density was significantly lower than those in previous years when M. aeruginosa was absent

  18. Distribution and abundance of diatom species from coastal waters of Karachi, Pakistan

    International Nuclear Information System (INIS)

    Khokhar, F. N.; Burhan, Z.; Iqbal, P.; Abbasi, J.; Siddiqui, P.

    2016-01-01

    This is the first comprehensive study on the distribution and abundance of diatom species from the coastal and nearshore waters of Karachi, Pakistan, bordering northern Arabian Sea. A total of 20 genera are recorded in high abundance (Cerataulina, Chaetoceros, Coscinodiscus, Cylindrotheca, Eucampia, Guinardia, Haslea, Hemiaulus, Lauderia, Lennoxia, Leptocylindrus, Navicula, Nitzschia, Trieres, Planktoniella, Pleurosigma, Pseudo-nitzschia, Rhizosolenia, Thalassionema and Thalassiosira). The most abundant genera were observed Guinardia, Chaetoceros, Leptocylindrus, Nitzschia and Lennoxia at all stations. Manora coastal station (MI-1) had high abundance corresponding with high Chlorophyll a (130 meu gL- l) values. Minimum abundance and low chlorophyll a value (0.05μgL-l) were observed at Mubarak Village coastal station (MV-1). Diatom abundance showed significant correlation with Chlorophyll a. In present study 12 centric and 8 pennate forms were recorded and similarly high diversity of centric taxa was observed compared to pennate forms. A total of 134 species are recorded of which 40 species were observed at four stations, 31species at three stations, 23 at two stations and 40 species only at one station. The total phytoplankton and diatom peak abundance was observed during NE monsoon (winter season) associated with nutrient loading through up-sloping of nutrient rich water upwelled off of Oman during South West monsoon. Overall higher diversity was observed at Manora coastal and nearshore stations (MI-1, MI-2) indicating the influence of organic pollution loading from Layari and Malir rivers. (author)

  19. On the statistical mechanics of species abundance distributions.

    Science.gov (United States)

    Bowler, Michael G; Kelly, Colleen K

    2012-09-01

    A central issue in ecology is that of the factors determining the relative abundance of species within a natural community. The proper application of the principles of statistical physics to species abundance distributions (SADs) shows that simple ecological properties could account for the near universal features observed. These properties are (i) a limit on the number of individuals in an ecological guild and (ii) per capita birth and death rates. They underpin the neutral theory of Hubbell (2001), the master equation approach of Volkov et al. (2003, 2005) and the idiosyncratic (extreme niche) theory of Pueyo et al. (2007); they result in an underlying log series SAD, regardless of neutral or niche dynamics. The success of statistical mechanics in this application implies that communities are in dynamic equilibrium and hence that niches must be flexible and that temporal fluctuations on all sorts of scales are likely to be important in community structure. Copyright © 2012 Elsevier Inc. All rights reserved.

  20. Suppressing the QCD axion abundance by hidden monopoles

    International Nuclear Information System (INIS)

    Kawasaki, Masahiro

    2015-11-01

    We study the Witten effect of hidden monopoles on the QCD axion dynamics, and show that its abundance as well as isocurvature perturbations can be significantly suppressed if there is a sufficient amount of hidden monopoles. When the hidden monopoles make up a significant fraction of dark matter, the Witten effect suppresses the abundance of axion with the decay constant smaller than 10 12 GeV. The cosmological domain wall problem of the QCD axion can also be avoided, relaxing the upper bound on the decay constant when the Peccei-Quinn symmetry is spontaneously broken after inflation.

  1. Host trait combinations drive abundance and canopy distribution of atmospheric bromeliad assemblages.

    Science.gov (United States)

    Chaves, Cleber Juliano Neves; Dyonisio, Júlio César; Rossatto, Davi Rodrigo

    2016-01-01

    Epiphytes are strongly dependent on the conditions created by their host's traits and a certain degree of specificity is expected between them, even if these species are largely abundant in a series of tree hosts of a given environment, as in the case of atmospheric bromeliads. Despite their considerable abundance in these environments, we hypothesize that stochasticity alone cannot explain the presence and abundance of atmospheric bromeliads on host trees, since host traits could have a greater influence on the establishment of these bromeliads. We used secondary and reforested seasonal forests and three distinct silvicultures to test whether species richness, phylogenetic diversity and functional diversity of trees can predict the differential presence, abundance and distribution of atmospheric bromeliads on hosts. We compared the observed parameters of their assemblage with null models and performed successive variance hierarchic partitions of abundance and distribution of the assemblage to detect the influence of multiple traits of the tree hosts. Our results do not indicate direct relationships between the abundance of atmospheric bromeliads and phylogenetic or functional diversity of trees, but instead indicate that bromeliads occurred on fewer tree species than expected by chance. We distinguished functional tree patterns that can improve or reduce the abundance of atmospheric bromeliads, and change their distribution on branches and trunk. While individual tree traits are related to increased abundance, species traits are related to the canopy distribution of atmospheric bromeliad assemblages. A balance among these tree functional patterns drives the atmospheric bromeliad assemblage of the forest patches. Published by Oxford University Press on behalf of the Annals of Botany Company.

  2. Effects of daily changes in environmental factors on the abundance and richness of Odonata Efeitos das mudanças diárias dos fatores ambientais sobre a abundância e a riqueza de Odonata

    Directory of Open Access Journals (Sweden)

    João Ânderson Fulan

    2011-03-01

    Full Text Available AIM: The aim of this work was to investigate the effects of daily changes in surface water abiotic factors on the abundance of Odonata larvae and the genus richness in a lateral lake isolated from a tropical river during the nycthemeral cycle in dry and wet seasons; METHODS: Macrophytes were sampled on a single day at 6-hours intervals for 24 hours (at 12:00 AM, 6:00 AM, 12:00 PM and 6:00 PM in dry and wet periods. At each site, abiotic factors were measured as follows: air temperature, surface water temperature, dissolved oxygen, pH, and electric conductivity. Canonical correspondence analysis (CCA of abiotic and biological data and sampling periods was made using CANOCO program; RESULTS: A total of 249 and 265 Odonata larvae from six genera (Acanthagrion, Cyanallagma, Telebasis, Erythemis, Erythrodiplax and Tauriphila were sampled in association with macrophytes in wet and dry seasons, respectively. Telebasis presented the highest frequency of occurrence and was collected in all nycthemeral cycle sampling periods in both seasons. The highest abundance of dragonflies was recorded at 6:00 AM and 12:00 AM in wet and dry seasons, respectively. Anoxia was detected in wet season during the entire nycthemeral cycle, while in the dry season, the highest variability in oxygen content was observed during sunlight. Canonical correspondence analysis showed that the abundances of Telebasis and Erythemis were positively related to water electrical conductivity, temperature, and depth, while for Acanthagrion and Tauriphila, abundance showed a positive relationship to water oxygen and pH. The variability of the abundance of Odonata due to surface water temperature, dissolved oxygen, electrical conductivity, pH, and depth during the daily cycle was therefore evidenced; CONCLUSIONS: We suggested that the better sampling period Odonata larvae must to be carried in the morning , since that we recorded the highest densities of both wet and dry stations at that

  3. Seasonal and spatial changes of macrobenthic community structure and diversity in South Yellow Sea

    Science.gov (United States)

    Li, X.; Xu, Y.

    2016-02-01

    The seasonal and spatial characteristics of macrobenthic community in South Yellow Sea were studied based on the data from three voyages carried out in spring, summer and autumn, 2012. A total of 218 species were obtained, including 80 species of Polychaeta, 75 of Crustacea, 35 of Mollusca, 15 of Echinodermata and 13 of other groups. Mean abundance varied from 151.4 ind./m2 in spring to 188 ind./m2 in autumn showing an increasing trend with season and mean biomass ranged from 12.1 g/m2 in spring to 33.4 g/m2 in summer. Mean secondary productivity varied from 2.5 g(AFDW)/(m2·a) in spring to 5.7 g(AFDW)/(m2·a) in summer. Two-way ANOVA indicated that biomass were significantly different among seasons and number of species and Shannon-Weiner index had significant differences among stations. But abundance, Pielou's evenness index and average taxonomic distinctness were not significantly different among either seasons or stations. Non-parametric Kruskal-Wallis test showed significant differences of secondary productivity among tations. Two-way crossed ANOSIM indicated overall significant differences of community structure among both seasons and stations. The stations were divided into four groups in spring and five in summer and autumn through the CLUSTER and nMDS analysis. Depth was an important factor influencing distribution of macrobenthos in the South Yellow Sea.

  4. Seasonality directs contrasting food collection behavior and nutrient regulation strategies in ants.

    Science.gov (United States)

    Cook, Steven C; Eubanks, Micky D; Gold, Roger E; Behmer, Spencer T

    2011-01-01

    Long-lived animals, including social insects, often display seasonal shifts in foraging behavior. Foraging is ultimately a nutrient consumption exercise, but the effect of seasonality per se on changes in foraging behavior, particularly as it relates to nutrient regulation, is poorly understood. Here, we show that field-collected fire ant colonies, returned to the laboratory and maintained under identical photoperiod, temperature, and humidity regimes, and presented with experimental foods that had different protein (p) to carbohydrate (c) ratios, practice summer- and fall-specific foraging behaviors with respect to protein-carbohydrate regulation. Summer colonies increased the amount of food collected as the p:c ratio of their food became increasingly imbalanced, but fall colonies collected similar amounts of food regardless of the p:c ratio of their food. Choice experiments revealed that feeding was non-random, and that both fall and summer ants preferred carbohydrate-biased food. However, ants rarely ate all the food they collected, and their cached or discarded food always contained little carbohydrate relative to protein. From a nutrient regulation strategy, ants consumed most of the carbohydrate they collected, but regulated protein consumption to a similar level, regardless of season. We suggest that varied seasonal food collection behaviors and nutrient regulation strategies may be an adaptation that allows long-lived animals to meet current and future nutrient demands when nutrient-rich foods are abundant (e.g. spring and summer), and to conserve energy and be metabolically more efficient when nutritionally balanced foods are less abundant.

  5. Seasonal dynamics and micro-climatic preference of two Alpine endemic hypogean beetles

    Directory of Open Access Journals (Sweden)

    Stefano Mammola

    2015-09-01

    Full Text Available Hypogean beetles generally live in stable environments, characterized by constant temperature and high relative humidity. Changes in the underground microclimatic conditions generally induce local migrations of the beetles through the hypogean environment in search of suitable microhabitats. We studied the seasonal dynamics and the micro-climatic preference of two Alpine endemic hypogean beetles - Sphodropsis ghilianii (Coleoptera, Carabidae and Dellabeffaella roccae (Coleoptera, Cholevidae - in the hypogean complex of Pugnetto (Graian Alps, Italy. We surveyed the two species for one year, using baited pitfall traps and measuring temperature and humidity along the two main caves. We used logistic regression mixed models (GLMMs to relate the presence of the two species to several variables, namely microclimate (seasonality, temperature, and humidity, subjacency and cave length. In addition, we tested the attractive power of the bait on the two species. The thermic optimum for S. ghilianii was found to be around 7°C, with an increasing probability of finding the species in the vicinity of the cave entrance during summer, autumn and spring. The species migrates inside the cave in winter, in response to the drop in the mean daily temperature and in the relative humidity occurring in the outer parts of the cave. On the contrary, D. roccae showed a significant preference for the deeper sections of the cave, characterized by an almost constant temperature of 9°C in air saturated with water vapour. Males and females individuals of both species were found to be equally affected by the environmental variables included in the analysis. We also provided information on the life history of the two species and methodological insights about the use of the bait in the traps

  6. Seasonal dynamics, age structure and reproduction of four Carabus species (Coleoptera: Carabidae) living in forested landscapes in Hungary

    DEFF Research Database (Denmark)

    Kádár, Ferenc; Fazekas, Judit P.; Sárospataki, Miklós

    2015-01-01

    Seasonal dynamics and reproductive phenological parameters of four Carabus species (C. convexus, C. coriaceus, C. germarii and C. hortensis) common in Hungary were studied by pitfall trapping and dissection. Beetles were collected in an abandoned apple orchard and in the bordering oak forest near...... Budapest (Central Hungary), in 1988–1991. The sex ratio was male-dominated, but this was significant only for C. coriaceus. The catch of C. germarii adults showed relatively short activity period with unimodal curve, but activity was longer and bimodal for the other three species. Adults of C. germarii...

  7. Seasonal temperature variation influences climate suitability for dengue, chikungunya, and Zika transmission.

    Science.gov (United States)

    Huber, John H; Childs, Marissa L; Caldwell, Jamie M; Mordecai, Erin A

    2018-05-01

    Dengue, chikungunya, and Zika virus epidemics transmitted by Aedes aegypti mosquitoes have recently (re)emerged and spread throughout the Americas, Southeast Asia, the Pacific Islands, and elsewhere. Understanding how environmental conditions affect epidemic dynamics is critical for predicting and responding to the geographic and seasonal spread of disease. Specifically, we lack a mechanistic understanding of how seasonal variation in temperature affects epidemic magnitude and duration. Here, we develop a dynamic disease transmission model for dengue virus and Aedes aegypti mosquitoes that integrates mechanistic, empirically parameterized, and independently validated mosquito and virus trait thermal responses under seasonally varying temperatures. We examine the influence of seasonal temperature mean, variation, and temperature at the start of the epidemic on disease dynamics. We find that at both constant and seasonally varying temperatures, warmer temperatures at the start of epidemics promote more rapid epidemics due to faster burnout of the susceptible population. By contrast, intermediate temperatures (24-25°C) at epidemic onset produced the largest epidemics in both constant and seasonally varying temperature regimes. When seasonal temperature variation was low, 25-35°C annual average temperatures produced the largest epidemics, but this range shifted to cooler temperatures as seasonal temperature variation increased (analogous to previous results for diurnal temperature variation). Tropical and sub-tropical cities such as Rio de Janeiro, Fortaleza, and Salvador, Brazil; Cali, Cartagena, and Barranquilla, Colombia; Delhi, India; Guangzhou, China; and Manila, Philippines have mean annual temperatures and seasonal temperature ranges that produced the largest epidemics. However, more temperate cities like Shanghai, China had high epidemic suitability because large seasonal variation offset moderate annual average temperatures. By accounting for seasonal

  8. Seasonal temperature variation influences climate suitability for dengue, chikungunya, and Zika transmission.

    Directory of Open Access Journals (Sweden)

    John H Huber

    2018-05-01

    Full Text Available Dengue, chikungunya, and Zika virus epidemics transmitted by Aedes aegypti mosquitoes have recently (reemerged and spread throughout the Americas, Southeast Asia, the Pacific Islands, and elsewhere. Understanding how environmental conditions affect epidemic dynamics is critical for predicting and responding to the geographic and seasonal spread of disease. Specifically, we lack a mechanistic understanding of how seasonal variation in temperature affects epidemic magnitude and duration. Here, we develop a dynamic disease transmission model for dengue virus and Aedes aegypti mosquitoes that integrates mechanistic, empirically parameterized, and independently validated mosquito and virus trait thermal responses under seasonally varying temperatures. We examine the influence of seasonal temperature mean, variation, and temperature at the start of the epidemic on disease dynamics. We find that at both constant and seasonally varying temperatures, warmer temperatures at the start of epidemics promote more rapid epidemics due to faster burnout of the susceptible population. By contrast, intermediate temperatures (24-25°C at epidemic onset produced the largest epidemics in both constant and seasonally varying temperature regimes. When seasonal temperature variation was low, 25-35°C annual average temperatures produced the largest epidemics, but this range shifted to cooler temperatures as seasonal temperature variation increased (analogous to previous results for diurnal temperature variation. Tropical and sub-tropical cities such as Rio de Janeiro, Fortaleza, and Salvador, Brazil; Cali, Cartagena, and Barranquilla, Colombia; Delhi, India; Guangzhou, China; and Manila, Philippines have mean annual temperatures and seasonal temperature ranges that produced the largest epidemics. However, more temperate cities like Shanghai, China had high epidemic suitability because large seasonal variation offset moderate annual average temperatures. By accounting

  9. Dynamical Downscaling of Seasonal Climate Prediction over Nordeste Brazil with ECHAM3 and NCEP's Regional Spectral Models at IRI.

    Science.gov (United States)

    Nobre, Paulo; Moura, Antonio D.; Sun, Liqiang

    2001-12-01

    This study presents an evaluation of a seasonal climate forecast done with the International Research Institute for Climate Prediction (IRI) dynamical forecast system (regional model nested into a general circulation model) over northern South America for January-April 1999, encompassing the rainy season over Brazil's Nordeste. The one-way nesting is one in two tiers: first the NCEP's Regional Spectral Model (RSM) runs with an 80-km grid mesh forced by the ECHAM3 atmospheric general circulation model (AGCM) outputs; then the RSM runs with a finer grid mesh (20 km) forced by the forecasts generated by the RSM-80. An ensemble of three realizations is done. Lower boundary conditions over the oceans for both ECHAM and RSM model runs are sea surface temperature forecasts over the tropical oceans. Soil moisture is initialized by ECHAM's inputs. The rainfall forecasts generated by the regional model are compared with those of the AGCM and observations. It is shown that the regional model at 80-km resolution improves upon the AGCM rainfall forecast, reducing both seasonal bias and root-mean-square error. On the other hand, the RSM-20 forecasts presented larger errors, with spatial patterns that resemble those of local topography. The better forecast of the position and width of the intertropical convergence zone (ITCZ) over the tropical Atlantic by the RSM-80 model is one of the principal reasons for better-forecast scores of the RSM-80 relative to the AGCM. The regional model improved the spatial as well as the temporal details of rainfall distribution, and also presenting the minimum spread among the ensemble members. The statistics of synoptic-scale weather variability on seasonal timescales were best forecast with the regional 80-km model over the Nordeste. The possibility of forecasting the frequency distribution of dry and wet spells within the rainy season is encouraging.

  10. Seasonal dynamics in the relative density of aquatic flora along some coastal areas of the Red Sea, Tabuk, Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Abid Ali Ansari

    2016-09-01

    Full Text Available Plants are the producers of all autotrophic ecosystems’ and are the base of the food chain taking energy from the sun and converting it into food for all other organisms through photosynthesis. Plants grow in certain places and seasons when the environmental factors are suitable for their germination, growth and developments that influence their diversity. Environmental factors can include abiotic factors such as temperature, light, moisture, soil nutrients; or biotic factors like competition from other plants or grazing by animals. Anthropogenic perturbations can also influence distribution patterns. Monitoring of ecological habitats and diversity of some aquatic flora along some coastal areas of Red Sea has been done to understand the dynamics of aquatic plants influenced by prevailing environmental and anthropogenic perturbations The results of this research showed that the summer season is the most suitable period for the study of aquatic plant diversity along the coastal sites of Red Sea. The aquatic flora had high relative density and diversity in April, May, June and July and these four months of the summer season are best for collection of aquatic plants from the selected coastal areas of Red Sea for medicinal purposes and ecological studies.

  11. Prediction of the Arctic Oscillation in Boreal Winter by Dynamical Seasonal Forecasting Systems

    Science.gov (United States)

    Kang, Daehyun; Lee, Myong-In; Im, Jungho; Kim, Daehyun; Kim, Hye-Mi; Kang, Hyun-Suk; Schubert, Siegfried D.; Arribas, Alberto; MacLachlan, Craig

    2014-01-01

    This study assesses the skill of boreal winter Arctic Oscillation (AO) predictions with state-of-the-art dynamical ensemble prediction systems (EPSs): GloSea4, CFSv2, GEOS-5, CanCM3, CanCM4, and CM2.1. Long-term reforecasts with the EPSs are used to evaluate how well they represent the AO and to assess the skill of both deterministic and probabilistic forecasts of the AO. The reforecasts reproduce the observed changes in the large-scale patterns of the Northern Hemispheric surface temperature, upper level wind, and precipitation associated with the different phases of the AO. The results demonstrate that most EPSs improve upon persistence skill scores for lead times up to 2 months in boreal winter, suggesting some potential for skillful prediction of the AO and its associated climate anomalies at seasonal time scales. It is also found that the skill of AO forecasts during the recent period (1997-2010) is higher than that of the earlier period (1983-1996).

  12. El Niño, host plant growth, and migratory butterfly abundance in a changing climate

    Science.gov (United States)

    In the wet forests of Panama, El Niño typically brings a more prolonged and severe dry season. Interestingly, many trees and lianas that comprise the wet forests increase their productivity as a response to El Niño. Here we quantify the abundance of migrating Marpesia chiron butterflies over 17 yea...

  13. Dogwood borer (Lepidoptera: Sesiidae) abundance and seasonal flight activity in apple orchards, urban landscapes, and woodlands in five eastern states.

    Science.gov (United States)

    Bergh, J C; Leskey, T C; Walgenbach, J F; Klingeman, W E; Kain, D P; Zhang, A

    2009-06-01

    The relative abundance and seasonal flight activity of dogwood borer, Synanthedon scitula Harris (Lepidoptera: Sesiidae), was measured using weekly records from traps baited with its sex pheromone and deployed in apple orchards, urban landscapes, and native woodland sites in New York, West Virginia, Virginia, North Carolina, and Tennessee in 2005 and 2006. The mean total number of moths captured per site in apple orchards was 3,146 +/- 644 and 3095 +/- 584 SE in 2005 and 2006, respectively, exceeding captures at urban sites by 16 and 13 times and at woodland sites by 210 and 206 times in 2005 and 2006, respectively. Mean total captures at urban sites exceeded those in woodland habitats by 13 and 16 times in 2005 and 2006, respectively. The mean duration (wk) of the flight period did not differ significantly between apple orchards (22.6 +/- 0.6 SE) and urban sites (20.3 +/- 1.2 SE). The onset of flight was somewhat later in New York (around early June) than further south (around early to mid-May), but moth captures continued into October in all states. Captures in apple orchards and at urban sites with higher populations were essentially continuous throughout the flight period, with substantial weekly fluctuations, and tended to show a bimodal pattern with peaks from late May through mid-July and from late August through mid-September. Captures at woodland sites tended to occur predominantly from mid-May through about mid-June and were very sporadic thereafter.

  14. Diversity and Transcriptional Levels of RuBisCO Form II of Sulfur-Oxidizing γ-Proteobacteria in Coastal-Upwelling Waters with Seasonal Anoxia

    Directory of Open Access Journals (Sweden)

    Bárbara Léniz

    2017-07-01

    Full Text Available Seasonal wind-driven upwelling, high primary production in surface waters, and oxygen deficiency in subsurface waters characterize the coastal ecosystem of the subtropical eastern South Pacific (ESP, and shape the nature and dynamics of the microbial community structure and function. We investigated the diversity, abundance, and transcriptional levels of the gene encoding the large subunit form II of the RuBisCO enzyme (cbbM in the pelagic microbial community at a continental-shelf site off central Chile over 2 years. We focused on cbbM genes affiliated with the sulfur-oxidizing γ-proteobacteria cluster, whose members are known to dominate in oxygen-deficient marine environments and are highly abundant in the study area. Phylogenetic analysis of cbbM sequences suggests the presence of a novel group of chemolithoautotrophs, closely related to the SUP05/ARCTIC96BD-19 clade. Through (RT-qPCR, we studied the cbbM gene abundance and transcript dynamics over an annual cycle, finding a significantly higher number of cbbM copies per unit volume in months of active upwelling and at depths in which oxygen was scarce or absent. The same temporal pattern was observed at the transcriptional level. We also analyzed the relative expression of key genes for carbon, nitrogen and sulfur cycling in six metatranscriptomic datasets, for two characteristic periods within the annual cycle: the anoxic upwelling and the suboxic downwelling. Our results indicate that coastal waters of the subtropical ESP contain transcriptionally active populations of carbon fixing pelagic bacteria, whose dynamics is controlled, in large part, by fluctuations in oxygen levels. They also suggest that chemolithoautotrophic processes coupled to the sulfur and nitrogen cycles become increasingly important for the carbon economy of marine coastal waters as oxygen concentrations decline.

  15. Seasonal-dial shifts of ichthyoplankton assemblages and plastic debris around an Equatorial Atlantic archipelago

    Directory of Open Access Journals (Sweden)

    André Araújo Lima

    2016-08-01

    Full Text Available Seasonality was a stronger influence in the ichthyoplankton assemblages around the Saint Peter and Saint Paul Archipelago (SPSPA than distance from the islands. Plastic debris were ubiquitous and although it presented diel trends, no other spatiotemporal patterns was showed. Larval Oxyporhamphus micropterus was the most important taxa (29.37% of the total catch, followed by Ceratoscopelus warmingii and Entomacrodus vomerianus. Exocoetidae eggs represented 41.01%. Mesopelagic fish larvae dominated the community. Myctophidae had the highest species richness (15. Four larval fish assemblages occured: (1 nighttime demersal/bathydemersal (Anguillidae, Congridae; (2 daytime mesopelagic/bathypelagic/epipelagic (Myctophidae, Cyclothone acclinidens; (3 daytime epipelagic (Exocoetidae, Coryphaena hippurus, Thunnus albacares and (4 nighttime reef and demersal (Blennidae, Pomacentridae, Lutjanidae. The dry season (lower temperature, higher chlorophyll a and higher SW wind velocity influenced the first two assemblages. The rainy season (higher temperatures and lower NW wind velocity influenced the last two. Nighttime abundance of dominant species in the rainy season suggests diel vertical migration nearshore. Plastics were 2.12 times more abundant than the most abundant fish larvae. Comparable amounts of larvae and plastics in the water column increase the chances of interaction between these two compartments and might disturb the local marine food web and promote the transfer of microplastic from one habitat to another, especially when smaller taxa contaminated by ingested fragments are preyed by migratory animals such as marine birds and tuna. A study around the area concluded that at least a part of the plastic debris can have local source due to fishing activities. Small-scale oceanographic mechanisms such as the interaction between the topography and currents (SEC and EUC seem to be responsible for the retention of fish eggs, fish larvae and plastics

  16. Body-size spectra of biofilm-dwelling protozoa and their seasonal shift in coastal ecosystems.

    Science.gov (United States)

    Zhao, Lu; Xu, Guangjian; Wang, Zheng; Xu, Henglong

    2016-10-01

    Community-based assessment of protozoa is usually performed at a taxon-dependent resolution. As an inherent 'taxon-free' trait, however, body-size spectrum has proved to be a highly informative indicator to summarize the functional structure of a community in both community research and monitoring programs in aquatic ecosystems. To demonstrate the relationships between the taxon-free resolution of protozoan communities and water conditions, the body-size spectra of biofilm-dwelling protozoa and their seasonal shift and environmental drivers were explored based on an annual dataset collected monthly from coastal waters of the Yellow Sea, northern China. Body sizes were calculated in equivalent spherical diameter (ESD). Among a total of 8 body-size ranks, S2 (19-27μm), S3 (28-36μm), S4 (37-50μm) and S5 (53-71μm) were the top four levels in frequency of occurrence, while rank S1 (13-17μm), S2 and S4 were the dominant levels in abundance. These dominants showed a clear seasonal succession: S2/S4 (spring)→S2/S4 (summer)→S4 (autumn)→S2 (winter) in frequency of occurrence; S1 (spring)→S4 (summer)→S2 (autumn)→S1 (winter) in abundance. Bootstrapped average analysis showed a clear seasonal shift in body-size spectra of the protozoa during a 1-year cycle, and the best-matching analysis demonstrated that the temporal variations in frequency of occurrence and abundance were significantly correlated with water temperature, pH, dissolved oxygen (DO), alone or in combination with chemical oxygen demand (COD) and nutrients. Thus, the body-size spectra of biofilm-dwelling protozoa were seasonally shaped and might be used as a time and cost efficient bioindicator of water quality in marine ecosystems. Copyright © 2016 Elsevier GmbH. All rights reserved.

  17. Fish assemblage in a semi-arid Neotropical reservoir: composition, structure and patterns of diversity and abundance.

    Science.gov (United States)

    Novaes, J L C; Moreira, S I L; Freire, C E C; Sousa, M M O; Costa, R S

    2014-05-01

    The aim of this study was to analyse the composition, structure and spatial and temporal patterns of diversity and abundance of the ichthyofauna of the Santa Cruz Reservoir in semi-arid Brazil. Data were collected quarterly at eight sampling locations on the reservoir between February 2010 and November 2011 using gillnets from 12- to 70-mm mesh that were left in the water for 12h00min during the night. We evaluated the composition, structure and assemblage descriptors (Shannon-Wiener diversity index and equitability, respectively) and catch per unit effort by the number (CPUEn) and biomass (CPUEb) of the ichthyofauna. The 6,047 individuals (399,211.6 g) captured represented three orders, ten families and 20 species, of which four belonged to introduced species. The family Characidae was the most abundant with a total of 2,772 (45.8%) individuals captured. The species-abundance curve fit the log-normal model. In the spatial analysis of diversity, there were significant differences between sampling sites in the lacustrine and fluvial regions, and the highest values were found in the lacustrine region. In the temporal analysis of diversity, significant differences were also observed between the rainy and dry seasons, and the higher values were found during the dry season. Equitability followed the same spatiotemporal pattern as diversity. The Spearman correlation was significantly negative between diversity and rainfall. A cluster analysis spatially separated the ichthyofauna into two groups: one group formed by sampling sites in the fluvial region and another group formed by the remainder of the points in the lacustrine region. Both the CPUEn and CPUEb values were higher at point 8 (fluvial region) and during the rainy season. A two-way ANOVA showed that the CPUEn and CPUEb values were spatially and temporally significant. We conclude that the spatial and temporal trends of diversity in the Santa Cruz reservoir differ from those of other Brazilian reservoirs but that

  18. Seasonal Dynamics of Academic Achievement Inequality by Socioeconomic Status and Race/Ethnicity

    Science.gov (United States)

    Quinn, David M.; Cooc, North; McIntyre, Joe; Gomez, Celia J.

    2016-01-01

    Early studies examining seasonal variation in academic achievement inequality generally concluded that socioeconomic test score gaps grew more over the summer than the school year, suggesting schools served as "equalizers." In this study, we analyze seasonal trends in socioeconomic status (SES) and racial/ethnic test score gaps using…

  19. Are the Formation and Abundances of Metal-poor Stars the Result of Dust Dynamics?

    Energy Technology Data Exchange (ETDEWEB)

    Hopkins, Philip F. [TAPIR, Mailcode 350-17, California Institute of Technology, Pasadena, CA 91125 (United States); Conroy, Charlie, E-mail: phopkins@caltech.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2017-02-01

    Large dust grains can fluctuate dramatically in their local density, relative to the gas, in neutral turbulent disks. Small, high-redshift galaxies (before reionization) represent ideal environments for this process. We show via simple arguments and simulations that order-of-magnitude fluctuations are expected in local abundances of large grains (>100 Å) under these conditions. This can have important consequences for star formation and stellar metal abundances in extremely metal-poor stars. Low-mass stars can form in dust-enhanced regions almost immediately after some dust forms even if the galaxy-average metallicity is too low for fragmentation to occur. We argue that the metal abundances of these “promoted” stars may contain interesting signatures as the CNO abundances (concentrated in large carbonaceous grains and ices) and Mg and Si (in large silicate grains) can be enhanced and/or fluctuate almost independently. Remarkably, the otherwise puzzling abundance patterns of some metal-poor stars can be well fit by standard IMF-averaged core-collapse SNe yields if we allow for fluctuating local dust-to-gas ratios. We also show that the observed log-normal distribution of enhancements in pure SNe yields, shows very large enhancements and variations up to factors of ≳100 as expected in the dust-promoted model, preferentially in the [C/Fe]-enhanced metal-poor stars. Together, this suggests that (1) dust exists in second-generation star formation, (2) local dust-to-gas ratio fluctuations occur in protogalaxies and can be important for star formation, and (3) the light element abundances of these stars may be affected by the local chemistry of dust where they formed, rather than directly tracing nucleosynthesis from earlier populations.

  20. Are the Formation and Abundances of Metal-poor Stars the Result of Dust Dynamics?

    International Nuclear Information System (INIS)

    Hopkins, Philip F.; Conroy, Charlie

    2017-01-01

    Large dust grains can fluctuate dramatically in their local density, relative to the gas, in neutral turbulent disks. Small, high-redshift galaxies (before reionization) represent ideal environments for this process. We show via simple arguments and simulations that order-of-magnitude fluctuations are expected in local abundances of large grains (>100 Å) under these conditions. This can have important consequences for star formation and stellar metal abundances in extremely metal-poor stars. Low-mass stars can form in dust-enhanced regions almost immediately after some dust forms even if the galaxy-average metallicity is too low for fragmentation to occur. We argue that the metal abundances of these “promoted” stars may contain interesting signatures as the CNO abundances (concentrated in large carbonaceous grains and ices) and Mg and Si (in large silicate grains) can be enhanced and/or fluctuate almost independently. Remarkably, the otherwise puzzling abundance patterns of some metal-poor stars can be well fit by standard IMF-averaged core-collapse SNe yields if we allow for fluctuating local dust-to-gas ratios. We also show that the observed log-normal distribution of enhancements in pure SNe yields, shows very large enhancements and variations up to factors of ≳100 as expected in the dust-promoted model, preferentially in the [C/Fe]-enhanced metal-poor stars. Together, this suggests that (1) dust exists in second-generation star formation, (2) local dust-to-gas ratio fluctuations occur in protogalaxies and can be important for star formation, and (3) the light element abundances of these stars may be affected by the local chemistry of dust where they formed, rather than directly tracing nucleosynthesis from earlier populations.

  1. Towards the use of dynamic growing seasons in a chemical transport model

    Science.gov (United States)

    Sakalli, A.; Simpson, D.

    2012-12-01

    Chemical transport models (CTMs), used for the prediction of, for example, nitrogen deposition or air quality changes, require estimates of the growing season of plants for a number of reasons. Typically, the growing seasons are defined in a very simplified way in CTMs, using fixed dates or simple functions. In order to explore the importance of more realistic growing season estimates, we have developed a new and simple method (the T5 method) for calculating the start of the growing season (SGS) of birch (which we use as a surrogate for deciduous trees), suitable for use in CTMs and other modelling systems. We developed the T5 method from observations, and here we compare with these and other methodologies, and show that with just two parameters T5 captures well the spatial variation in SGS across Europe. We use the EMEP MSC-W chemical transport model to illustrate the importance of improved SGS estimates for ozone and two metrics associated with ozone damage to vegetation. This study shows that although inclusion of more realistic growing seasons has only small effects on annual average concentrations of pollutants such as ozone, the metrics associated with vegetation risk from ozone are significantly affected. This work demonstrates a strong need to include more realistic treatments of growing seasons in CTMs. The method used here could also be suitable for other types of models that require information on vegetation cover, such as meteorological and regional climate models. In future work, the T5 and other methods will be further evaluated for other forest species, as well as for agricultural and grassland land covers, which are important for emissions and deposition of reactive nitrogen compounds.

  2. Cost of living in free-ranging degus (Octodon degus) : seasonal dynamics of energy expenditure

    NARCIS (Netherlands)

    Bozinovic, F; Bacigalupe, LD; Vasquez, RA; Visser, GH; Veloso, C; Kenagy, GJ

    Animals process and allocate energy at different seasons at variable rates, depending on their breeding season and changes in environmental conditions and resulting physiological demands. Overall total energy expenditure, in turn, should either increase in some seasons due to special added demands

  3. Response of biological soil crust diazotrophs to season, altered summer precipitation and year-round increased temperature in an arid grassland of the Colorado Plateau, USA

    Directory of Open Access Journals (Sweden)

    Chris M Yeager

    2012-10-01

    Full Text Available Biological soil crusts (biocrusts, which supply significant amounts of fixed nitrogen into terrestrial ecosystems worldwide (~33 Tg y-1, are likely to respond to changes in temperature and precipitation associated with climate change. Using nifH gene-based surveys, we explored variation in the diazotrophic community of biocrusts of the Colorado Plateau, USA in response to season (autumn vs. spring, as well as field manipulations that increased the frequency of small-volume precipitation events and year-round soil temperature. Abundance of nifH genes in biocrusts ranged from 3x106 – 1x108 g-1 soil, and nifH from heterocystous cyanobacteria closely related to Scytonema hyalinum, Spirirestis rafaelensis, and Nostoc commune comprised > 98% of the total. Although there was no apparent seasonal effect on total nifH gene abundance in the biocrusts, T-RFLP analysis revealed a strong seasonal pattern in nifH composition. Spirirestis nifH abundance was estimated to oscillate 1 to >2 orders of magnitude between autumn (low and spring (high. A year-round increase of soil temperature (2 − 3 °C had little effect on the diazotroph community structure over 2 years. Altered summer precipitation had little impact on diazotroph community structure over the first 1.5 years of the study, when natural background patterns across years and seasons superseded any treatment effects. However, after the second summer of treatments, nifH abundance was 2.6 fold lower in biocrusts receiving altered precipitation. Heterocystous cyanobacteria were apparently more resilient to altered precipitation than other cyanobacteria. The results demonstrate that diazotrophic community composition of biocrusts in this semi-arid grassland undergoes strong seasonal shifts and that the abundance of its dominant members decreased in response to more frequent, small-volume precipitation events.

  4. Response of biological soil crust diazotrophs to season, altered summer precipitation, and year-round increased temperature in an arid grassland of the Colorado Plateau, USA

    Science.gov (United States)

    Yeager, Chris M.; Kuske, Cheryl R.; Carney, Travis D.; Johnson, Shannon L.; Ticknor, Lawrence O.; Belnap, Jayne

    2012-01-01

    Biological soil crusts (biocrusts), which supply significant amounts of fixed nitrogen into terrestrial ecosystems worldwide (~33Tg y-1), are likely to respond to changes in temperature and precipitation associated with climate change. Using nifH gene-based surveys, we explored variation in the diazotrophic community of biocrusts of the Colorado Plateau, USA in response to season (autumn vs. spring), as well as field manipulations that increased the frequency of small volume precipitation events and year-round soil temperature. Abundance of nifH genes in biocrusts ranged from 3×106 to 1×8 g-1 soil, and nifH from heterocystous cyanobacteria closely related to Scytonema hyalinum, Spirirestis rafaelensis, and Nostoc commune comprised >98% of the total. Although there was no apparent seasonal effect on total nifH gene abundance in the biocrusts, T-RFLP analysis revealed a strong seasonal pattern in nifH composition. Spirirestis nifH abundance was estimated to oscillate 1 to >2 orders of magnitude between autumn (low) and spring (high). A year-round increase of soil temperature (2–3°C) had little effect on the diazotroph community structure over 2 years. Altered summer precipitation had little impact on diazotroph community structure over the first 1.5years of the study, when natural background patterns across years and seasons superseded any treatment effects. However, after the second summer of treatments, nifH abundance was 2.6-fold lower in biocrusts receiving altered precipitation. Heterocystous cyanobacteria were apparently more resilient to altered precipitation than other cyanobacteria. The results demonstrate that diazotrophic community composition of biocrusts in this semi-arid grassland undergoes strong seasonal shifts and that the abundance of its dominant members decreased in response to more frequent, small volume precipitation events.

  5. Detection of human muscle glycogen by natural abundance 13C NMR

    International Nuclear Information System (INIS)

    Avison, M.J.; Rothman, D.L.; Nadel, E.; Shulman, R.G.

    1988-01-01

    Natural abundance 13 C nuclear magnetic resonance spectroscopy was used to detect signals from glycogen in the human gastrocnemius muscle. The reproducibility of the measurement was demonstrated, and the ability to detect dynamic changes was confirmed by measuring a decrease in muscle glycogen levels after exercise and its subsequent repletion. Single frequency gated 1 H decoupling was used to obtain decoupled natural abundance 13 C NMR spectra of the C-1 position of muscle glycogen

  6. Host plant development, water level and water parameters shape Phragmites australis-associated oomycete communities and determine reed pathogen dynamics in a large lake.

    Science.gov (United States)

    Wielgoss, Anna; Nechwatal, Jan; Bogs, Carolin; Mendgen, Kurt

    2009-08-01

    In a 3-year-study, we analysed the population dynamics of the reed pathogen Pythium phragmitis and other reed-associated oomycetes colonizing fresh and dried reed leaves in the littoral zone of a large lake. Oomycete communities derived from internal transcribed spacer clone libraries were clearly differentiated according to substrate and seasonal influences. In fresh leaves, diverse communities consisting of P. phragmitis and other reed-associated pathogens were generally dominant. Pythium phragmitis populations peaked in spring with the emergence of young reed shoots, and in autumn after extreme flooding events. In summer it decreased with falling water levels, changing water chemistry and rising temperatures. Another Pythium species was also highly abundant in fresh leaves throughout the year and might represent a new, as-yet uncultured reed pathogen. In dried leaves, reed pathogens were rarely detected, whereas saprophytic species occurred abundantly during all seasons. Saprophyte communities were less diverse, less temperature sensitive and independent of reed development. In general, our results provide evidence for the occurrence of highly specialized sets of reed-associated oomycetes in a natural reed ecosystem. Quantitative analyses (clone abundances and quantitative real-time PCR) revealed that the reed pathogen P. phragmitis is particularly affected by changing water levels, water chemistry and the stage of reed development.

  7. Effect of rainfall cessation on the plankton abundance and diversity ...

    African Journals Online (AJOL)

    The physico-chemical characteristics of the creek were influenced by the seasonal change in water chemistry. Surface water was characterized by high total ... study were Nitzschia, Ulnaria, Oscillatoriaand Pinnularia. Keywords: Organic pollution, physico-chemical characteristics, tidal dynamics, phytoplankton, zooplankton ...

  8. Influence of temporal and spatial factors on abundance and richness of fish early stages in shallow tropical estuaries

    NARCIS (Netherlands)

    Arévalo-Frías, W.; Mendoza-Carranza, M.

    2015-01-01

    Accurate determination of abundance and richness of fish early stages in estuarine zones is critical to support management and protection plans; it is therefore necessary to consider all influential factors. Habitat diversity, seasonality, moon phase and diel variations, and their interactions are

  9. Seasonal predictability of Kiremt rainfall in coupled general circulation models

    Science.gov (United States)

    Gleixner, Stephanie; Keenlyside, Noel S.; Demissie, Teferi D.; Counillon, François; Wang, Yiguo; Viste, Ellen

    2017-11-01

    The Ethiopian economy and population is strongly dependent on rainfall. Operational seasonal predictions for the main rainy season (Kiremt, June-September) are based on statistical approaches with Pacific sea surface temperatures (SST) as the main predictor. Here we analyse dynamical predictions from 11 coupled general circulation models for the Kiremt seasons from 1985-2005 with the forecasts starting from the beginning of May. We find skillful predictions from three of the 11 models, but no model beats a simple linear prediction model based on the predicted Niño3.4 indices. The skill of the individual models for dynamically predicting Kiremt rainfall depends on the strength of the teleconnection between Kiremt rainfall and concurrent Pacific SST in the models. Models that do not simulate this teleconnection fail to capture the observed relationship between Kiremt rainfall and the large-scale Walker circulation.

  10. Estimating Cyanobacteria Community Dynamics and its Relationship with Environmental Factors

    Science.gov (United States)

    Luo, Wenhuai; Chen, Huirong; Lei, Anping; Lu, Jun; Hu, Zhangli

    2014-01-01

    The cyanobacteria community dynamics in two eutrophic freshwater bodies (Tiegang Reservoir and Shiyan Reservoir) was studied with both a traditional microscopic counting method and a PCR-DGGE genotyping method. Results showed that cyanobacterium Phormidium tenue was the predominant species; twenty-six cyanobacteria species were identified in water samples collected from the two reservoirs, among which fourteen were identified with the morphological method and sixteen with the PCR-DGGE method. The cyanobacteria community composition analysis showed a seasonal fluctuation from July to December. The cyanobacteria population peaked in August in both reservoirs, with cell abundances of 3.78 × 108 cells L-1 and 1.92 × 108 cells L-1 in the Tiegang and Shiyan reservoirs, respectively. Canonical Correspondence Analysis (CCA) was applied to further investigate the correlation between cyanobacteria community dynamics and environmental factors. The result indicated that the cyanobacteria community dynamics was mostly correlated with pH, temperature and total nitrogen. This study demonstrated that data obtained from PCR-DGGE combined with a traditional morphological method could reflect cyanobacteria community dynamics and its correlation with environmental factors in eutrophic freshwater bodies. PMID:24448632

  11. Seasonal phenology and species composition of the aphid fauna in a northern crop production area.

    Directory of Open Access Journals (Sweden)

    Sascha M Kirchner

    Full Text Available BACKGROUND: The species diversity of aphids and seasonal timing of their flight activity can have significant impacts on crop production, as aphid species differ in their ability to transmit plant viruses and flight timing affects virus epidemiology. The aim of the study was to characterise the species composition and phenology of aphid fauna in Finland in one of the northernmost intensive crop production areas of the world (latitude 64°. METHODOLOGY/PRINCIPAL FINDINGS: Flight activity was monitored in four growing seasons (2007-010 using yellow pan traps (YPTs placed in 4-8 seed potato fields and a Rothamsted suction trap. A total of 58,528 winged aphids were obtained, identified to 83 taxa based on morphology, and 34 species were additionally characterised by DNA barcoding. Seasonal flight activity patterns analysed based on YPT catch fell into three main phenology clusters. Monoecious taxa showed early or middle-season flight activity and belonged to species living on shrubs/trees or herbaceous plants, respectively. Heteroecious taxa occurred over the entire potato growing season (ca. 90 days. Abundance of aphids followed a clear 3-year cycle based on suction trap data covering a decade. Rhopalosiphum padi occurring at the end of the potato growing season was the most abundant species. The flight activity of Aphis fabae, the main vector of Potato virus Y in the region, and Aphis gossypii peaked in the beginning of potato growing season. CONCLUSIONS/SIGNIFICANCE: Detailed information was obtained on phenology of a large number aphid species, of which many are agriculturally important pests acting as vectors of plant viruses. Aphis gossypii is known as a pest in greenhouses, but our study shows that it occurs also in the field, even far in the north. The novel information on aphid phenology and ecology has wide implications for prospective pest management, particularly in light of climate change.

  12. Seasonality directs contrasting food collection behavior and nutrient regulation strategies in ants.

    Directory of Open Access Journals (Sweden)

    Steven C Cook

    Full Text Available Long-lived animals, including social insects, often display seasonal shifts in foraging behavior. Foraging is ultimately a nutrient consumption exercise, but the effect of seasonality per se on changes in foraging behavior, particularly as it relates to nutrient regulation, is poorly understood. Here, we show that field-collected fire ant colonies, returned to the laboratory and maintained under identical photoperiod, temperature, and humidity regimes, and presented with experimental foods that had different protein (p to carbohydrate (c ratios, practice summer- and fall-specific foraging behaviors with respect to protein-carbohydrate regulation. Summer colonies increased the amount of food collected as the p:c ratio of their food became increasingly imbalanced, but fall colonies collected similar amounts of food regardless of the p:c ratio of their food. Choice experiments revealed that feeding was non-random, and that both fall and summer ants preferred carbohydrate-biased food. However, ants rarely ate all the food they collected, and their cached or discarded food always contained little carbohydrate relative to protein. From a nutrient regulation strategy, ants consumed most of the carbohydrate they collected, but regulated protein consumption to a similar level, regardless of season. We suggest that varied seasonal food collection behaviors and nutrient regulation strategies may be an adaptation that allows long-lived animals to meet current and future nutrient demands when nutrient-rich foods are abundant (e.g. spring and summer, and to conserve energy and be metabolically more efficient when nutritionally balanced foods are less abundant.

  13. Bacterial Abundance and Activity across Sites within Two Northern Wisconsin Sphagnum Bogs.

    Science.gov (United States)

    Fisher; Graham; Graham

    1998-11-01

    Abstract Bacterial abundance, temperature, pH, and dissolved organic carbon (DOC) concentration were compared across surface sites within and between two northern Wisconsin Sphagnum peatlands over the summer seasons in 1995 and 1996. Sites of interest were the Sphagnum mat surface, the water-filled moat (lagg) at the bog margin, and the bog lake littoral zone. Significant differences in both bacterial populations and water chemistry were observed between sites. pH was highest in the lake and lowest in the mat at both bogs; the opposite was true for DOC. Large populations of bacteria were present in surface interstitial water from the mat; abundance in this site was consistently higher than in the moat or lake. Bacterial abundance also increased across sites of increasing DOC concentration and declining pH. Bacterial activities (rates of [3H]leucine incorporation) and growth in dilution cultures (with grazers removed) were also assessed in lake, moat, and mat sites. Results using these measures generally supported the trends observed in abundance, although high rates of [3H]leucine incorporation were recorded in the moat at one of the bogs. Our results indicate that bacterial populations in Sphagnum peatlands are not adversely affected by acidity, and that DOC may be more important than pH in determining bacterial abundance in these environments.

  14. Vector species richness increases haemorrhagic disease prevalence through functional diversity modulating the duration of seasonal transmission.

    Science.gov (United States)

    Park, Andrew W; Cleveland, Christopher A; Dallas, Tad A; Corn, Joseph L

    2016-06-01

    Although many parasites are transmitted between hosts by a suite of arthropod vectors, the impact of vector biodiversity on parasite transmission is poorly understood. Positive relationships between host infection prevalence and vector species richness (SR) may operate through multiple mechanisms, including (i) increased vector abundance, (ii) a sampling effect in which species of high vectorial capacity are more likely to occur in species-rich communities, and (iii) functional diversity whereby communities comprised species with distinct phenologies may extend the duration of seasonal transmission. Teasing such mechanisms apart is impeded by a lack of appropriate data, yet could highlight a neglected role for functional diversity in parasite transmission. We used statistical modelling of extensive host, vector and microparasite data to test the hypothesis that functional diversity leading to longer seasonal transmission explained variable levels of disease in a wildlife population. We additionally developed a simple transmission model to guide our expectation of how an increased transmission season translates to infection prevalence. Our study demonstrates that vector SR is associated with increased levels of disease reporting, but not via increases in vector abundance or via a sampling effect. Rather, the relationship operates by extending the length of seasonal transmission, in line with theoretical predictions.

  15. Seasonal dynamics of soil CO2 efflux and soil profile CO2 concentrations in arboretum of Moscow botanical garden

    Science.gov (United States)

    Goncharova, Olga; Udovenko, Maria; Matyshak, Georgy

    2016-04-01

    To analyse and predict recent and future climate change on a global scale exchange processes of greenhouse gases - primarily carbon dioxide - over various ecosystems are of rising interest. In order to upscale land-use dependent sources and sinks of CO2, knowledge of the local variability of carbon fluxes is needed. Among terrestrial ecosystems, urban areas play an important role because most of anthropogenic emissions of carbon dioxide originate from these areas. On the other hand, urban soils have the potential to store large amounts of soil organic carbon and, thus, contribute to mitigating increases in atmospheric CO2 concentrations. Research objectives: 1) estimate the seasonal dynamics of carbon dioxide production (emission - closed chamber technique and profile concentration - soil air sampling tubes method) by soils of Moscow State University Botanical Garden Arboretum planted with Picea obovata and Pinus sylvestris, 1) identification the factors that control CO2 production. The study was conducted with 1-2 weeks intervals between October 2013 and November 2015 at two sites. Carbon dioxide soil surface efflux during the year ranged from 0 to 800 mgCO2/(m2hr). Efflux values above 0 mgCO2/(m2hr) was observed during the all cold period except for only 3 weeks. Soil CO2 concentration ranged from 1600-3000 ppm in upper 10-cm layer to 10000-40000 ppm at a depth of 60 cm. The maximum concentrations of CO2 were recorded in late winter and late summer. We associate it with high biological activity (both heterotrophic and autotrophic) during the summer, and with physical gas jamming in the winter. The high value of annual CO2 production of the studied soils is caused by high organic matter content, slightly alkaline reaction, good structure and texture of urban soils. Differences in soil CO2 production by spruce and pine urban forest soils (in the pine forest 1.5-2.0 times higher) are caused by urban soil profiles construction, but not temperature regimes. Seasonal

  16. Benthic assemblages of rock pools in northern Portugal: seasonal and between-pool variability

    Directory of Open Access Journals (Sweden)

    Iacopo Bertocci

    2012-11-01

    Full Text Available We investigated the seasonal (winter vs summer and within season and spatial (between-pool variability of benthic assemblages of rock pools at mid-intertidal level along the shore of Viana do Castelo (North Portugal. Physical traits of rock pools, including size, depth and position along the shore, were also compared between pools. While pools did not differ for any of the examined physical traits, results indicated a clear seasonal difference in the structure of assemblages, including a total of 49 macroalgal and 13 animal taxa. This finding was driven by six taxa that are more abundant in winter (the reef-forming polychaete Sabellaria alveolata, the articulated coralline algae Corallina spp., the brown alga Bifurcaria bifurcata, the encrusting coralline alga Lithophyllum incrustans, the red alga Chondracanthus acicularis and the grazing snails Gibbula spp. and four algal taxa that are more abundant in summer (the invasive brown Sargassum muticum, the green Ulva spp., the kelp Laminaria ochroleuca and the filamentous red Ceramium spp.. These data provide a new contribution to the knowledge of rock pool systems and have potential implications for monitoring programmes aimed at assessing ecological modifications related to natural and anthropogenic disturbances and for identifying processes responsible for the variability of rock pool assemblages.

  17. CHEMICAL ABUNDANCES IN NGC 5053: A VERY METAL-POOR AND DYNAMICALLY COMPLEX GLOBULAR CLUSTER

    Energy Technology Data Exchange (ETDEWEB)

    Boberg, Owen M.; Friel, Eileen D.; Vesperini, Enrico [Astronomy Department, Indiana University, Bloomington, IN 47405 (United States)

    2015-05-10

    NGC 5053 provides a rich environment to test our understanding of the complex evolution of globular clusters (GCs). Recent studies have found that this cluster has interesting morphological features beyond the typical spherical distribution of GCs, suggesting that external tidal effects have played an important role in its evolution and current properties. Additionally, simulations have shown that NGC 5053 could be a likely candidate to belong to the Sagittarius dwarf galaxy (Sgr dSph) stream. Using the Wisconsin–Indiana–Yale–NOAO–Hydra multi-object spectrograph, we have collected high quality (signal-to-noise ratio ∼ 75–90), medium-resolution spectra for red giant branch stars in NGC 5053. Using these spectra we have measured the Fe, Ca, Ti, Ni, Ba, Na, and O abundances in the cluster. We measure an average cluster [Fe/H] abundance of −2.45 with a standard deviation of 0.04 dex, making NGC 5053 one of the most metal-poor GCs in the Milky Way (MW). The [Ca/Fe], [Ti/Fe], and [Ba/Fe] we measure are consistent with the abundances of MW halo stars at a similar metallicity, with alpha-enhanced ratios and slightly depleted [Ba/Fe]. The Na and O abundances show the Na–O anti-correlation found in most GCs. From our abundance analysis it appears that NGC 5053 is at least chemically similar to other GCs found in the MW. This does not, however, rule out NGC 5053 being associated with the Sgr dSph stream.

  18. Chemical Abundances in NGC 5053: A Very Metal-poor and Dynamically Complex Globular Cluster

    Science.gov (United States)

    Boberg, Owen M.; Friel, Eileen D.; Vesperini, Enrico

    2015-05-01

    NGC 5053 provides a rich environment to test our understanding of the complex evolution of globular clusters (GCs). Recent studies have found that this cluster has interesting morphological features beyond the typical spherical distribution of GCs, suggesting that external tidal effects have played an important role in its evolution and current properties. Additionally, simulations have shown that NGC 5053 could be a likely candidate to belong to the Sagittarius dwarf galaxy (Sgr dSph) stream. Using the Wisconsin-Indiana-Yale-NOAO-Hydra multi-object spectrograph, we have collected high quality (signal-to-noise ratio ˜ 75-90), medium-resolution spectra for red giant branch stars in NGC 5053. Using these spectra we have measured the Fe, Ca, Ti, Ni, Ba, Na, and O abundances in the cluster. We measure an average cluster [Fe/H] abundance of -2.45 with a standard deviation of 0.04 dex, making NGC 5053 one of the most metal-poor GCs in the Milky Way (MW). The [Ca/Fe], [Ti/Fe], and [Ba/Fe] we measure are consistent with the abundances of MW halo stars at a similar metallicity, with alpha-enhanced ratios and slightly depleted [Ba/Fe]. The Na and O abundances show the Na-O anti-correlation found in most GCs. From our abundance analysis it appears that NGC 5053 is at least chemically similar to other GCs found in the MW. This does not, however, rule out NGC 5053 being associated with the Sgr dSph stream.

  19. Population dynamics of the diamondback moth, Plutella xylostella (L.), in northern China: the effects of migration, cropping patterns and climate.

    Science.gov (United States)

    Zhu, Liuhong; Li, Zhenyu; Zhang, Shufa; Xu, Baoyun; Zhang, Youjun; Zalucki, Myron P; Wu, Qingjun; Yin, Xianhui

    2018-02-08

    The diamondback moth, Plutella xylostella (L.), is the most widely distributed pest of Brassica vegetables. Control of P. xylostella has relied on insecticides and it has developed resistance to most insecticides. Although research has clarified the resistance status of P. xylostella and the mechanisms of its resistance in northern China, little work has been conducted on long-term population dynamics in the key vegetable-growing areas of the region. We reviewed and summarized the history of P. xylostella field management practices in northern China (Haidian, Changping, Xuanhua and Zhangbei). Moths were caught in pheromone traps throughout the cropping season and P. xylostella phenology and the general trends in abundance were analysed using DYMEX modelling software. The initial input in the spring determined population size in all years. The seasonal phenology and variation in abundance in most years and sites were simulated, suggesting that the suitable climate creates the conditions for population outbreaks, and growers' actual management level (spraying and crop hygiene) influenced population abundance. Based on climate and using the timing of the initial peak in pheromone trap captures as a biofix, the timing of emergence of the next generation can be forecast, and more effective scouting and regional management strategies against this pest can be developed. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

  20. Multi-annual and seasonal patterns of waterbird assemblages in a Mediterranean coastal lagoon (El Mellah lagoon of Northeastern Algeria

    Directory of Open Access Journals (Sweden)

    Telailia Salah

    2017-06-01

    Full Text Available Recently, Mediterranean coastal lagoons have raised considerable environmental concerns. Long-term studies of seasonal changes in waterbird assemblages are therefore extremely important in terms of ecological relevance and conservation of these sensitive ecosystems. An ornithological survey of four years was carried out in a typical costal wetland (El Mellah lagoon of Northeastern Algeria. Intra-seasonal comparison of waterbird assemblages (diversity indices demonstrates clear changes between the wintering and the breeding periods. It seems that the first one was rich in term of species number than the second season (43 against 24. In contrast, the breeding seasons were more equilibrate (high values of Simpson, Shannon and evenness index. Additionally, curves in the diversity/dominance diagram revealed that both wintering and breeding assemblages share the same characteristics of community structure, few dominant species (with intermediate relative abundance and many rare species with the relative abundance lower than 0.1. Invertebrates (25 species and piscivorous (11 species are the most abundant guilds over the four years of study (no significant differences among years have been calculated. The marked decline in bird species diversity recorded in this study (in comparison with previous studies is mainly due to salinity oscillations (due to aquaculture activities and may be of concern to wetland managers and it might be useful to provide some guidelines about the characteristics that coastal lagoons have to follow in the construction process to enhance the biodiversity.