WorldWideScience

Sample records for benthic macrophyte communities

  1. Phylogenetically diverse macrophyte community promotes species diversity of mobile epi-benthic invertebrates

    Science.gov (United States)

    Nakamoto, Kenta; Hayakawa, Jun; Kawamura, Tomohiko; Kodama, Masafumi; Yamada, Hideaki; Kitagawa, Takashi; Watanabe, Yoshiro

    2018-07-01

    Various aspects of plant diversity such as species diversity and phylogenetic diversity enhance the species diversity of associated animals in terrestrial systems. In marine systems, however, the effects of macrophyte diversity on the species diversity of associated animals have received little attention. Here, we sampled in a subtropical seagrass-seaweed mixed bed to elucidate the effect of the macrophyte phylogenetic diversity based on the taxonomic relatedness as well as the macrophyte species diversity on species diversity of mobile epi-benthic invertebrates. Using regression analyses for each macrophyte parameter as well as multiple regression analyses, we found that the macrophyte phylogenetic diversity (taxonomic diversity index: Delta) positively influenced the invertebrate species richness and diversity index (H‧). Although the macrophyte species richness and H‧ also positively influenced the invertebrate species richness, the best fit model for invertebrate species richness did not include them, suggesting that the macrophyte species diversity indirectly influenced invertebrate species diversity. Possible explanations of the effects of macrophyte Delta on the invertebrate species diversity were the niche complementarity effect and the selection effect. This is the first study which demonstrates that macrophyte phylogenetic diversity has a strong effect on the species diversity of mobile epi-benthic invertebrates.

  2. Multivariate Analysis of Water Quality and Benthic Macrophyte Communities in Florida Bay, USA Reveals Hurricane Effects and Susceptibility to Seagrass Die-Off

    Directory of Open Access Journals (Sweden)

    Amanda M. Cole

    2018-05-01

    Full Text Available Seagrass communities, dominated by Thalassia testudinum, form the principal benthic ecosystem within Florida Bay, Florida USA. The bay has had several large-scale seagrass die-offs in recent decades associated with drought and hypersaline conditions. In addition, three category-5 hurricanes passed in close proximity to the bay during the fall of 2005. This study investigated temporal and spatial trends in macrophyte abundance and water quality from 2006 to 2013 at 15 permanent transect sites, which were co-located with long-term water quality stations. Relationships, by year and by transect location (basin, between antecedent water quality (mean, minimum and maximum for a 6-month period and benthic macrophyte communities were examined using multivariate analyses. Total phosphorus, salinity, pH, turbidity, dissolved inorganic nitrogen (DIN, DIN to phosphate ratio (DIN:PO4-3, chlorophyll a, and dissolved oxygen correlated with temporal and spatial variations in the macrophyte communities. Temporal analysis (MDS and LINKTREE indicated that the fall 2005 hurricanes affected both water quality and macrophyte communities for approximately a 2-year period. Spatial analysis revealed that five basins, which subsequently exhibited a major seagrass die-off during summer 2015, significantly differed from the other ten basins in macrophyte community structure and water quality more than 2 years before this die-off event. High total phosphorus, high pH, low DIN, and low DIN:PO4-3, in combination with deep sediments and high seagrass cover were characteristic of sites that subsequently exhibited severe die-off. Our results indicate basins with more mixed seagrass communities and higher macroalgae abundance are less susceptible to die-off, which is consistent with the management goals of promoting more heterogeneous benthic macrophyte communities.

  3. The role of benthic macrophytes and their associated macroinvertebrate community in coastal lagoon resistance to eutrophication.

    Science.gov (United States)

    Lloret, Javier; Marín, Arnaldo

    2009-12-01

    Eutrophication is widely recognised as one of the major menaces to coastal environments, particularly enclosed bays and lagoons. Although there is a general understanding of the consequences of eutrophication in these systems, there is a lack of sufficient knowledge concerning biotic feedbacks that influence eutrophication patterns and the resistance capacity of coastal environments. In this paper, the isotope ratios of main producers and consumers of a Mediterranean lagoon were examined in order to elucidate the fate of anthropogenic inputs from the main watercourse flowing into the lagoon. The results of the study of stable isotope data in the Mar Menor lagoon reflected that the whole benthic community plays an important role as a natural 'filter' that removes excess nutrients from the water column and stores them in the sediments, thereby enhancing lagoon resistance to eutrophication.

  4. The role of benthic macrophytes and their associated macroinvertebrate community in coastal lagoon resistance to eutrophication

    International Nuclear Information System (INIS)

    Lloret, Javier; Marin, Arnaldo

    2009-01-01

    Eutrophication is widely recognised as one of the major menaces to coastal environments, particularly enclosed bays and lagoons. Although there is a general understanding of the consequences of eutrophication in these systems, there is a lack of sufficient knowledge concerning biotic feedbacks that influence eutrophication patterns and the resistance capacity of coastal environments. In this paper, the isotope ratios of main producers and consumers of a Mediterranean lagoon were examined in order to elucidate the fate of anthropogenic inputs from the main watercourse flowing into the lagoon. The results of the study of stable isotope data in the Mar Menor lagoon reflected that the whole benthic community plays an important role as a natural 'filter' that removes excess nutrients from the water column and stores them in the sediments, thereby enhancing lagoon resistance to eutrophication.

  5. Production in aquatic macrophyte communities

    DEFF Research Database (Denmark)

    Binzer, Thomas; Sand-Jensen, Kaj

    2002-01-01

    -dimensional structure because of the strong drag and shear forces of moving water. This difference in canopy structure has been suggested to account for the three- to fivefold higher gross production rates in terrestrial than aquatic communities. To evaluate the effect of community structure in aquatic habitats, we......Many terrestrial plant canopies regulate spatial patterns in leaf density and leaf inclination to distribute light evenly between the photosynthetic tissue and to optimize light utilization efficiency. Sessile aquatic macrophytes, however, cannot maintain the same well-defined three...... was markedly enhanced by a vertical orientation of thalli when absorptance and community density were both high. This result implies that aquatic macrophytes of high thallus absorptance and community density exposed to high light are limited in attaining high gross production rates because of their inability...

  6. Submerged Macrophytes Mitigate Direct and Indirect Insecticide Effects in Freshwater Communities

    Science.gov (United States)

    Brogan, William R.; Relyea, Rick A.

    2015-01-01

    Understanding how ecological interactions mitigate the impacts of perturbations such as pesticides in biological communities is an important basic and applied question for ecologists. In aquatic ecosystems, new evidence from microcosm experiments suggests that submerged macrophytes can buffer cladocerans from pulse exposures to the widely used insecticide malathion, and that mitigation increases with macrophyte density. However, whether these results scale up to more complex aquatic communities where ecological interactions such as competition can alter toxicity is unknown. Further, macrophyte abilities to mitigate different insecticide exposure scenarios (i.e. single versus repeated pulses) have never been tested. To address these gaps, we performed a factorial mesocosm experiment examining the influence of four macrophyte treatments (0, 10, 50, or 100 Elodea Canadensis shoots planted per mesocosm) crossed with three malathion exposure scenarios (no insecticide, single pulse, repeated pulses) on aquatic communities containing zooplankton, phytoplankton, periphyton, two snail species, and larval amphibians. In the absence of macrophytes, single malathion pulses caused short-term declines in cladoceran abundance followed by their rapid recovery, which precluded any indirect effects (i.e. trophic cascades). However, repeated malathion pulses caused cladoceran extinctions, resulting in persistent phytoplankton blooms and reduced abundance of one snail species. In contrast, with macrophytes present, even at low density, malathion had no effect on any taxa. We also discovered novel effects of macrophytes on the benthic food web. In the two highest macrophyte treatments, we observed trends of reduced periphyton biomass, decreased abundance of one snail species, and decreased amphibian time to and mass at metamorphosis. To our knowledge, this is the first evidence of negative submerged macrophyte effects on amphibians, a taxa of global conservation concern. Our findings

  7. Submerged macrophytes mitigate direct and indirect insecticide effects in freshwater communities.

    Directory of Open Access Journals (Sweden)

    William R Brogan

    Full Text Available Understanding how ecological interactions mitigate the impacts of perturbations such as pesticides in biological communities is an important basic and applied question for ecologists. In aquatic ecosystems, new evidence from microcosm experiments suggests that submerged macrophytes can buffer cladocerans from pulse exposures to the widely used insecticide malathion, and that mitigation increases with macrophyte density. However, whether these results scale up to more complex aquatic communities where ecological interactions such as competition can alter toxicity is unknown. Further, macrophyte abilities to mitigate different insecticide exposure scenarios (i.e. single versus repeated pulses have never been tested. To address these gaps, we performed a factorial mesocosm experiment examining the influence of four macrophyte treatments (0, 10, 50, or 100 Elodea Canadensis shoots planted per mesocosm crossed with three malathion exposure scenarios (no insecticide, single pulse, repeated pulses on aquatic communities containing zooplankton, phytoplankton, periphyton, two snail species, and larval amphibians. In the absence of macrophytes, single malathion pulses caused short-term declines in cladoceran abundance followed by their rapid recovery, which precluded any indirect effects (i.e. trophic cascades. However, repeated malathion pulses caused cladoceran extinctions, resulting in persistent phytoplankton blooms and reduced abundance of one snail species. In contrast, with macrophytes present, even at low density, malathion had no effect on any taxa. We also discovered novel effects of macrophytes on the benthic food web. In the two highest macrophyte treatments, we observed trends of reduced periphyton biomass, decreased abundance of one snail species, and decreased amphibian time to and mass at metamorphosis. To our knowledge, this is the first evidence of negative submerged macrophyte effects on amphibians, a taxa of global conservation concern

  8. Submerged macrophytes mitigate direct and indirect insecticide effects in freshwater communities.

    Science.gov (United States)

    Brogan, William R; Relyea, Rick A

    2015-01-01

    Understanding how ecological interactions mitigate the impacts of perturbations such as pesticides in biological communities is an important basic and applied question for ecologists. In aquatic ecosystems, new evidence from microcosm experiments suggests that submerged macrophytes can buffer cladocerans from pulse exposures to the widely used insecticide malathion, and that mitigation increases with macrophyte density. However, whether these results scale up to more complex aquatic communities where ecological interactions such as competition can alter toxicity is unknown. Further, macrophyte abilities to mitigate different insecticide exposure scenarios (i.e. single versus repeated pulses) have never been tested. To address these gaps, we performed a factorial mesocosm experiment examining the influence of four macrophyte treatments (0, 10, 50, or 100 Elodea Canadensis shoots planted per mesocosm) crossed with three malathion exposure scenarios (no insecticide, single pulse, repeated pulses) on aquatic communities containing zooplankton, phytoplankton, periphyton, two snail species, and larval amphibians. In the absence of macrophytes, single malathion pulses caused short-term declines in cladoceran abundance followed by their rapid recovery, which precluded any indirect effects (i.e. trophic cascades). However, repeated malathion pulses caused cladoceran extinctions, resulting in persistent phytoplankton blooms and reduced abundance of one snail species. In contrast, with macrophytes present, even at low density, malathion had no effect on any taxa. We also discovered novel effects of macrophytes on the benthic food web. In the two highest macrophyte treatments, we observed trends of reduced periphyton biomass, decreased abundance of one snail species, and decreased amphibian time to and mass at metamorphosis. To our knowledge, this is the first evidence of negative submerged macrophyte effects on amphibians, a taxa of global conservation concern. Our findings

  9. Leachates and elemental ratios of macrophytes and benthic algae of an Andean high altitude wetland

    Directory of Open Access Journals (Sweden)

    Beatriz MODENUTTI

    2011-08-01

    Full Text Available In wetlands, macrophytes and filamentous algae constitute an important carbon source for the total content of Dissolved Organic Matter (DOM of the environment. Mallín wetland meadows are highly diverse and rare habitats in Patagonia, that can be characterized as wet meadows with a dense cover mainly dominated by herbaceous plants. We carried out a field study comparing elemental composition (C:N:P of benthic algae (Spirogyra sp. and Zygnema sp. and the submerged macrophyte (Myriophyllum quitense from a high latitude wetland (local name: mallín. Besides we performed laboratory experiments in order to study the effect of ultraviolet radiation (UVR on the optical properties and nutrient release of DOM from leachates of these benthic algae and submerged macrophyte. The obtained results indicated that macrophyte leachates could contribute significantly to changes in the optical characteristics of the wetlands while benthic algae contribute with leachates with low photoreactivity. Finally, nutrient release differs among plant species and season: benthic algae leachates release more P in spring, while M. quitense releases more of this nutrient in autumn. These results suggested that the different colonization may contribute differentially to the chemical environment of the wetland.

  10. Community photosynthesis of aquatic macrophytes

    DEFF Research Database (Denmark)

    Binzer, T.; Sand-Jensen, K.; Middelboe, A. L.

    2006-01-01

    We compared 190 photosynthesis-irradiance (P-E) experiments with single- and multispecies communities of macroalgae and vascular plants from freshwater and marine habitats. We found a typical hyperbolic P-E relation in all communities and no sign of photosaturation or photoinhibition of photosynt......We compared 190 photosynthesis-irradiance (P-E) experiments with single- and multispecies communities of macroalgae and vascular plants from freshwater and marine habitats. We found a typical hyperbolic P-E relation in all communities and no sign of photosaturation or photoinhibition...

  11. Algal communities associated with aquatic macrophytes in some ...

    African Journals Online (AJOL)

    This study describes the algal communities of six ponds colonised by aquatic macrophytes in Nyanza Province, Kenya. Plankton samples were collected from the water column and epiphytic samples from macrophytes such as Azolla, Pistia, Nymphaea, Ipomoea and Ludwigia. Pond pH, temperature, conductivity, ...

  12. Macrophyte Community Response to Nitrogen Loading and ...

    Science.gov (United States)

    Empirical determination of nutrient loading thresholds that negatively impact seagrass communities have been elusive due to the multitude of factors involved. Using a mesocosm system that simulated Pacific Northwest estuaries, we evaluated macrophyte metrics across gradients of NO3 loading (0, 1.5, 3 and 6x ambient) and temperature (10 and 20 °C). Macroalgal growth, biomass, and C:N responded positively to increased NO3 load and floating algal mats developed at 20 ºC. Zostera japonica metrics, including C:N, responded more to temperature than to NO3 loading. Z. marina biomass exhibited a negative temperature effect and in some cases a negative NO3 effect, while growth rate increased with temperature. Shoot survival decreased at 20 ºC but was not influenced by NO3 loading. Wasting disease index exhibited a significant temperature by NO3 interaction consistent with increased disease susceptibility. Community shifts observed were consistent with the nutrient loading hypothesis at 20 ºC, but there was no evidence of other eutrophication symptoms due to the short residence time. The Nutrient Pollution Index tracked the NO3 gradient at 10 ºC but exhibited no response at 20 ºC. We suggest that systems characterized by cool temperatures, high NO3 loads, and short residence time may be resilient to many symptoms of eutrophication. Estuarine systems characterized by cool temperatures, high nutrient loads and rapid flushing may be resilient to some symptoms

  13. The offshore benthic fish community

    Science.gov (United States)

    Lantry, Brian F.; Lantry, Jana R.; Weidel, Brian C.; Walsh, Maureen; Hoyle, James A.; Schaner, Teodore; Neave, Fraser B.; Keir, Michael

    2014-01-01

    Lake Ontario’s offshore benthic fish community includes primarily slimy sculpin, lake whitefish, rainbow smelt, lake trout, burbot, and sea lamprey. Of these, lake trout have been the focus of an international restoration effort for more than three decades (Elrod et al. 1995; Lantry and Lantry 2008). The deepwater sculpin and three species of deepwater ciscoes (Coregonus spp.) that were historically important in the offshore benthic zone became rare or were extirpated by the 1960s (Christie 1973; Owens et al. 2003; Lantry et al. 2007b; Roth et al. 2013). Ecosystem changes continue to influence the offshore benthic fish community, including the effects of dreissenid mussels, the near disappearance of burrowing amphipods (Diporeia spp.) (Dermott et al. 2005; Watkins et al. 2007), and the increased abundance and expanded geographic distribution of round goby (see Nearshore Fish Community chapter) (Lantry et al. 2007b). The fish-community objectives for the offshore benthic fish community, as described by Stewart et al. (1999), are:

  14. Biodiversity patterns of macrophyte and macroinvertebrate communities in two lagoons of Western Greece.

    Science.gov (United States)

    Fyttis, G.; Reizopoulou, S.; Papastergiadou, E.

    2012-04-01

    also showed that environmental variables such as depth, transparency/depth ratio, total P, chl-a, and TSM differed significantly between the two lagoons. In order to assess the ecological quality of the study sites, the functional ISD index has been applied. From the preliminary results it seems that ISD index, based on the biomass size structure of the macroinvertebrate communities, is more appropriate for the assessment of the ecological status for these particular ecosystems. The development of a monitoring team is essential for the protection and management of these ecologically important ecosystems. Further investigation is necessary to examine the relationships between benthic macroinvertebrates and aquatic macrophytes, the use of biotic indices to the evaluation for lagoonal ecosystems' ecological status and the relation between the hydrological processes and the biodiversity patterns of the biotic elements.

  15. The influence of the community of water macrophytes on regulation ...

    African Journals Online (AJOL)

    Natural waterplant communities may help prevent the introduction of pollutants. We explore the role of macrophytes in ameliorating the waters of the Kuibyshev reservoir littoral zones through investigating plant and zooplankton communities. We suggest that water vegetation can play a sanative role to improve water quality ...

  16. Aquatic macrophyte community varies in urban reservoirs with different degrees of eutrophication

    Directory of Open Access Journals (Sweden)

    Suelen Cristina Alves da Silva

    2014-06-01

    Full Text Available AIM: Investigate spatial and temporal variation in the aquatic macrophyte community in four urban reservoirs located in Curitiba metropolitan region, Brazil. We tested the hypothesis that aquatic macrophyte community differ among reservoirs with different degrees of eutrophication. METHODS: The reservoirs selected ranged from oligotrophic/mesotrophic to eutrophic. Sampling occurred in October 2011, January 2012 and June 2012. Twelve aquatic macrophytes stands were sampled at each reservoir. Species were identified and the relative abundance of aquatic macrophytes was estimated. Differences among reservoirs and over sampling periods were analyzed: i through two‑way ANOVAs considering the stand extent (m and the stand biodiversity - species richness, evenness, Shannon-Wiener index and beta diversity (species variation along the aquatic macrophyte stand; and ii through PERMANOVA considering species composition. Indicator species that were characteristic for each reservoir were also identified. RESULTS: The aquatic macrophyte stand extent varied among reservoirs and over sampling periods. Species richness showed only temporal variation. On the other hand, evenness and Shannon-Wiener index varied only among reservoirs. The beta diversity of macrophyte stands did not vary among reservoirs or over time, meaning that species variability among aquatic macrophyte stands was independent of the stand extent and reservoir eutrophication. Community composition depended on the reservoir and sampling period. CONCLUSIONS: Our results support our initial expectation that reservoirs of different degrees of eutrophication have different aquatic macrophyte communities. As a consequence, each reservoir had particular indicator species. Therefore, monitoring and management efforts must be offered for each reservoir individually.

  17. Functional diversity of macrophyte communities within and between Pyrenean lakes

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    Enric BALLESTEROS

    2009-02-01

    Full Text Available Submersed vegetation is a common feature in about 70% Pyrenean high mountain (>1500 m a.s.l. lakes. Isoetids and soft-water elodeids are common elements of this underwater flora and can form distinct vegetation units (i.e. patches of vegetation dominated by different species within complex mosaics of vegetation in shallow waters (<7 m. Since isoetids exert a strong influence on sediment biogeochemistry due to high radial oxygen loss, we examined the small scale characteristics of the lake environment (water and sediment associated to vegetation patches in order to ascertain potential functional differences among them. To do so, we characterised the species composition and biomass of the main vegetation units from 11 lakes, defined plant communities based on biomass data, and then related each community with sediment properties (redox and dissolved nutrient concentration in the pore water and water nutrient concentration within plant canopy. We also characterised lake water and sediment in areas without vegetation as a reference. A total of twenty-one vegetation units were identified, ranging from one to five per lake. A cluster analysis on biomass species composition suggested seven different macrophyte communities that were named after the most dominant species: Nitella sp., Potamogeton praelongus, Myriophyllum alterniflorum, Sparganium angustifolium, Isoetes echinospora, Isoetes lacustris and Carex rostrata. Coupling between macrophyte communities and their immediate environment (overlying water and sediment was manifested mainly as variation in sediment redox conditions and the dominant form of inorganic nitrogen in pore-water. These effects depended on the specific composition of the community, and on the allocation between above- and belowground biomass, and could be predicted with a model relating the average and standard deviation of sediment redox potential from 0 down to -20 cm, across macrophyte communities. Differences in pore

  18. Composition and dynamic of benthic macroinvertebrates community ...

    African Journals Online (AJOL)

    the purpose to analyze the taxonomic composition, the structure of benthic macroinvertebrates community and the composite ... differences relative to the spatial and temporal variation in the taxonomic composition. ... changes in the structure of macroinvertebrates community ... 2007) with an annual growth rate of 2.4% rely.

  19. Macrophyte Species Drive the Variation of Bacterioplankton Community Composition in a Shallow Freshwater Lake

    Science.gov (United States)

    Zeng, Jin; Bian, Yuanqi; Xing, Peng

    2012-01-01

    Macrophytes play an important role in structuring aquatic ecosystems. In this study, we explored whether macrophyte species are involved in determining the bacterioplankton community composition (BCC) in shallow freshwater lakes. The BCC in field areas dominated by different macrophyte species in Taihu Lake, a large, shallow freshwater lake, was investigated over a 1-year period. Subsequently, microcosm experiments were conducted to determine if single species of different types of macrophytes in an isolated environment would alter the BCC. Denaturing gradient gel electrophoresis (DGGE), followed by cloning and sequence analysis of selected samples, was employed to analyze the BCC. The DGGE results of the field investigations indicated that the BCC changed significantly from season to season and that the presence of different macrophyte species resulted in lower BCC similarities in the summer and fall. LIBSHUFF analysis of selected clone libraries from the summer demonstrated different BCCs in the water column surrounding different macrophytes. Relative to the field observations, the microcosm studies indicated that the BCC differed more pronouncedly when associated with different species of macrophytes, which was also supported by LIBSHUFF analysis of the selected clone libraries. Overall, this study suggested that macrophyte species might be an important factor in determining the composition of bacterial communities in this shallow freshwater lake and that the species-specific influence of macrophytes on BCC is variable with the season and distance. PMID:22038598

  20. Primary productivity of marine macrophytes in the coral reef lagoon of the Kadmat Island, Lakshadweep

    Digital Repository Service at National Institute of Oceanography (India)

    Dhargalkar, V.K.; Shaikh, N.

    n situ primary productivity measurements were carried out with different macrophyte species (belonging to four groups) dominating the benthic communities in the coral reef lagoon of the Kadmat Island of the Lakshadweep Archipelago...

  1. Does mechanical disturbance affect the performance and species composition of submerged macrophyte communities?

    Science.gov (United States)

    Zhang, Qian; Xu, Ying-Shou; Huang, Lin; Xue, Wei; Sun, Gong-Qi; Zhang, Ming-Xiang; Yu, Fei-Hai

    2014-05-01

    Submerged macrophyte communities are frequently subjected to disturbance of various frequency and strength. However, there is still little experimental evidence on how mechanical disturbance affects the performance and species composition of such plant communities. In a greenhouse experiment, we constructed wetland communities consisting of five co-occurring clonal submerged macrophyte species (Hydrilla verticillata, Elodea canadensis, Ceratophyllum demersum, Chara fragilis, and Myriophyllum spicatum) and subjected these communities to three mechanical disturbance regimes (no, moderate and strong disturbance). Strong mechanical disturbance greatly decreased overall biomass, number of shoot nodes and total shoot length, and increased species diversity (evenness) of the total community. It also substantially decreased the growth of the most abundant species (H. verticillata), but did not affect growth of the other four species. Our data reveal that strong disturbance can have different effects on different submerged macrophyte species and thus alters the performance and species composition of submerged macrophyte communities.

  2. The impact of an industrial effluent on the water quality, submersed macrophytes and benthic macroinvertebrates in a dammed river of Central Spain.

    Science.gov (United States)

    Gonzalo, Cristina; Camargo, Julio A

    2013-10-01

    This research was conducted in the middle Duratón River (Central Spain), in the vicinity of Burgomillodo Reservoir. An industrial effluent enters the river 300 m downstream from the dam. Fluoride and turbidity levels significantly increased downstream from the effluent, these levels being to some extent affected by differential water releases from the dam. The community of submersed macrophytes exhibited slighter responses and, accordingly, lower discriminatory power than the community of benthic macroinvertebrates, this indicating that metrics and indices based on macroinvertebrates may be more suitable for the biological monitoring of water pollution and habitat degradation in dammed rivers receiving industrial effluents. However, in relation to fluoride bioaccumulation at the organism level, macrophytes (Fontinalis antipyretica and Potamogeton pectinatus) were as suitable bioindicators of fluoride pollution as macroinvertebrates (Ancylus fluviatilis and Pacifastacus leniusculus). Fluoride bioaccumulation in both hard and soft tissues of these aquatic organisms could be used as suitable bioindicator of fluoride pollution (even lower than 1 mg F(-)L(-1)) in freshwater ecosystems. Echinogammarus calvus exhibited a great sensitivity to the toxicity of fluoride ions, with a 96 h LC₅₀ of 7.5 mg F(-)L(-1) and an estimated safe concentration of 0.56 mg F(-)L(-1). The great capacity of E. calvus to take up and retain fluoride during exposures to fluoride ions would be a major cause of its great sensitivity to fluoride toxicity. It is concluded that the observed fluoride pollution might be partly responsible for the absence of this native amphipod downstream from the industrial effluent. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Data for Macrophyte Community Response to Nitrogen Loading and Thermal Stressors in Rapidly Flushed Mesocosm Systems

    Data.gov (United States)

    U.S. Environmental Protection Agency — Data represent response variables from a series of mesocosm experiments to assess how estuarine macrophyte communities respond to nitrogen loading under two...

  4. Deterioration of atlantic soft water macrophyte communities by acidification, eutrophication and alkalinisation

    NARCIS (Netherlands)

    Arts, G.H.P.

    2002-01-01

    This review presents an overview of the most important succession patterns and underlying processes associated with the deterioration of soft water macrophyte communities in atlantic and boreo-atlantic regions. As acidification, eutrophication and alkalinisation are the dominant processes, this

  5. Submerged macrophytes modify bacterial community composition in sediments in a large, shallow, freshwater lake.

    Science.gov (United States)

    Zhao, Da-Yong; Liu, Peng; Fang, Chao; Sun, Yi-Meng; Zeng, Jin; Wang, Jian-Qun; Ma, Ting; Xiao, Yi-Hong; Wu, Qinglong L

    2013-04-01

    Submerged aquatic macrophytes are an important part of the lacustrine ecosystem. In this study, the bacterial community compositions in the rhizosphere sediments from three kinds of submerged macrophytes (Ceratophyllum demersum, Potamogeton crispus, and Vallisneria natans) were investigated to determine whether submerged macrophytes could drive the variation of bacterial community in the eutrophic Taihu Lake, China. Molecular techniques, including terminal restriction fragment length polymorphism (T-RFLP) of PCR-amplified 16S rRNA gene and clone libraries, were employed to analyze the bacterial community compositions. Remarkable differences of the T-RFLP patterns were observed among the different samples, and the results of LIBSHUFF analysis also confirmed that the bacterial community compositions in the rhizosphere sediments of three kinds of submerged macrophytes were statistically different from that of the unvegetated sediment. Acidobacteria, Deltaproteobacteria, and Betaproteobacteria were the dominant bacterial groups in the rhizosphere sediments of Ceratophyllum demersum, Potamogeton crispus, and Vallisneria natans, respectively, accounting for 15.38%, 29.03%, and 18.00% of the total bacterial abundances. Our study demonstrated that submerged macrophytes could influence the bacterial community compositions in their rhizosphere sediments, suggesting that macrophytes have an effect on the cycling and transportation of nutrients in the freshwater lake ecosystem.

  6. Vegetative Propagule Pressure and Water Depth Affect Biomass and Evenness of Submerged Macrophyte Communities.

    Science.gov (United States)

    Li, Hong-Li; Wang, Yong-Yang; Zhang, Qian; Wang, Pu; Zhang, Ming-Xiang; Yu, Fei-Hai

    2015-01-01

    Vegetative propagule pressure may affect the establishment and structure of aquatic plant communities that are commonly dominated by plants capable of clonal growth. We experimentally constructed aquatic communities consisting of four submerged macrophytes (Hydrilla verticillata, Ceratophyllum demersum, Elodea nuttallii and Myriophyllum spicatum) with three levels of vegetative propagule pressure (4, 8 and 16 shoot fragments for communities in each pot) and two levels of water depth (30 cm and 70 cm). Increasing vegetative propagule pressure and decreasing water level significantly increased the growth of the submerged macrophyte communities, suggesting that propagule pressure and water depth should be considered when utilizing vegetative propagules to re-establish submerged macrophyte communities in degraded aquatic ecosystems. However, increasing vegetative propagule pressure and decreasing water level significantly decreased evenness of the submerged macrophyte communities because they markedly increased the dominance of H. verticillata and E. nuttallii, but had little impact on that of C. demersum and M. spicatum. Thus, effects of vegetative propagule pressure and water depth are species-specific and increasing vegetative propagule pressure under lower water level can facilitate the establishment success of submerged macrophyte communities.

  7. Vegetative Propagule Pressure and Water Depth Affect Biomass and Evenness of Submerged Macrophyte Communities.

    Directory of Open Access Journals (Sweden)

    Hong-Li Li

    Full Text Available Vegetative propagule pressure may affect the establishment and structure of aquatic plant communities that are commonly dominated by plants capable of clonal growth. We experimentally constructed aquatic communities consisting of four submerged macrophytes (Hydrilla verticillata, Ceratophyllum demersum, Elodea nuttallii and Myriophyllum spicatum with three levels of vegetative propagule pressure (4, 8 and 16 shoot fragments for communities in each pot and two levels of water depth (30 cm and 70 cm. Increasing vegetative propagule pressure and decreasing water level significantly increased the growth of the submerged macrophyte communities, suggesting that propagule pressure and water depth should be considered when utilizing vegetative propagules to re-establish submerged macrophyte communities in degraded aquatic ecosystems. However, increasing vegetative propagule pressure and decreasing water level significantly decreased evenness of the submerged macrophyte communities because they markedly increased the dominance of H. verticillata and E. nuttallii, but had little impact on that of C. demersum and M. spicatum. Thus, effects of vegetative propagule pressure and water depth are species-specific and increasing vegetative propagule pressure under lower water level can facilitate the establishment success of submerged macrophyte communities.

  8. Responses of bacterial community structure and denitrifying bacteria in biofilm to submerged macrophytes and nitrate

    Science.gov (United States)

    Zhang, Songhe; Pang, Si; Wang, Peifang; Wang, Chao; Guo, Chuan; Addo, Felix Gyawu; Li, Yi

    2016-10-01

    Submerged macrophytes play important roles in constructed wetlands and natural water bodies, as these organisms remove nutrients and provide large surfaces for biofilms, which are beneficial for nitrogen removal, particularly from submerged macrophyte-dominated water columns. However, information on the responses of biofilms to submerged macrophytes and nitrogen molecules is limited. In the present study, bacterial community structure and denitrifiers were investigated in biofilms on the leaves of four submerged macrophytes and artificial plants exposed to two nitrate concentrations. The biofilm cells were evenly distributed on artificial plants but appeared in microcolonies on the surfaces of submerged macrophytes. Proteobacteria was the most abundant phylum in all samples, accounting for 27.3-64.8% of the high-quality bacterial reads, followed by Chloroflexi (3.7-25.4%), Firmicutes (3.0-20.1%), Acidobacteria (2.7-15.7%), Actinobacteria (2.2-8.7%), Bacteroidetes (0.5-9.7%), and Verrucomicrobia (2.4-5.2%). Cluster analysis showed that bacterial community structure can be significantly different on macrophytes versus from those on artificial plants. Redundancy analysis showed that electrical conductivity and nitrate concentration were positively correlated with Shannon index and operational taxonomic unit (OTU) richness (log10 transformed) but somewhat negatively correlated with microbial density. The relative abundances of five denitrifying genes were positively correlated with nitrate concentration and electrical conductivity but negatively correlated with dissolved oxygen.

  9. Macrophyte Communities of Andean Rivers: Composition and Relation with Environmental Factors

    Directory of Open Access Journals (Sweden)

    Alida Marcela Gómez Rodríguez

    2017-01-01

    Full Text Available Small streams of tropical Andes have been poorly studied. Therefore, there is little information about the structure, dynamics and function of their macrophyte communities. In this research, aquatic plant communities of 18 Andean streams of La Vieja (Quindío and Otún (Risaralda river basins were studied; those are some of the basins most affected by anthropic activities in the country. Streams were selected according to their association with the main land’s uses of the region in both basins. The aim of the study was to evaluate the effect of land use on the structure of macrophyte communities. Streams running exclusively through each land use were selected. Sampling was done in two different climatic seasons of year 2006. Vegetation found (54 species belonging to 25 families was dominated by species with high capability of adaptation to changing and disturbed environments. Richness and abundance of macrophytes were lower than those reported in other tropical aquatic systems. Variables associated with land use, such as temperature, conductivity and type of substrate of the streams mainly explained the structure of the macrophyte communities: streams running on meat-cattle areas -with higher temperatures, conductivity and dominance of sandy-slimy substrates- had higher macrophyte species richness and abundance than streams of protected-forest areas, with higher coverage by riparian vegetation, lower temperatures and conductivity and rocky substrates.

  10. Macrophyte community development and its implication for fisheries ...

    African Journals Online (AJOL)

    Agricultural activities, and poor management practices over the years have led to high siltation rates and consequent extensive growth of emergent aquatic macrophytes such as Typha australis, Nymphaea lotus, Echinochloa pyramidalis and Leersia hexandra, as well as marginal plants such as Mimosa pigra and Sesbania ...

  11. Emergent macrophytes modify the abundance and community composition of ammonia oxidizers in their rhizosphere sediments.

    Science.gov (United States)

    Zhao, Dayong; He, Xiaowei; Huang, Rui; Yan, Wenming; Yu, Zhongbo

    2017-07-01

    Ammonia oxidation is a crucial process in global nitrogen cycling, which is catalyzed by the ammonia oxidizers. Emergent plants play important roles in the freshwater ecosystem. Therefore, it is meaningful to investigate the effects of emergent macrophytes on the abundance and community composition of ammonia oxidizers. In the present study, two commonly found emergent macrophytes (Zizania caduciflora and Phragmitas communis) were obtained from freshwater lakes and the abundance and community composition of the ammonia-oxidizing prokaryotes in the rhizosphere sediments of these emergent macrophytes were investigated. The abundance of the bacterial amoA gene was higher in the rhizosphere sediments of the emergent macrophytes than those of bulk sediments. Significant positive correlation was found between the potential nitrification rates (PNRs) and the abundance of bacterial amoA gene, suggesting that ammonia-oxidizing bacteria (AOB) might play an important role in the nitrification process of the rhizosphere sediments of emergent macrophytes. The Nitrosotalea cluster is the dominant ammonia-oxidizing archaea (AOA) group in all the sediment samples. Analysis of AOB group showed that the N. europaeal cluster dominated the rhizosphere sediments of Z. caduciflora and the bulk sediments, whereas the Nitrosospira cluster was the dominant AOB group in the rhizosphere sediments of P. communis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Method for assessment and classification of water courses by using the community of aquatic macrophytes

    International Nuclear Information System (INIS)

    Minciardi, M.R.; Spada, C.D.; Rossi, G.L.; Angius, R.; Orru, G.; Mancini, L.; Pace, G.; Mercheggiani, S.; Puccinelli, C.

    2009-01-01

    Studies about aquatic macrophytes as bio indicator community in Europe have been carried out since 70s. Efficient macrophytes indices, mainly for the assessment of trophic state, have been defined in nineties. In 2000, WFD includes macrophytes among the ecological quality elements for running waters. To implement Directive 2000/60/C E, European countries had to define methodologies to evaluate the ecological status of water bodies by macrophytes assessment, but almost all Member States continue to use trophic indexes. Researches carried out in Italy during last 10 years confirm the presence and the evaluability in all river types, and the efficiency of macrophytes community as bio indicator. Besides, many European indices have been tested to assess their applicability throughout the country. Particularly, the Index Macrofitique Biologique en Riviere (IBMR), formalized in France in 2003 as trophic index and currently used as french national method, is applicable in Italy. This index not only allows to evaluate the trophic level metric, but can also be used, as proposed in France, as index of ecological status, expressed as distance from the expected trophic state. [it

  13. Spatial distribution maps for benthic communities

    DEFF Research Database (Denmark)

    Sørensen, Per S.

    1999-01-01

    ecosystems, were selected. These species are supposed to be good indicators of marine ecosystem health. The hydroacoustic measurements comprise preprocessed echo sounder recordings and side-scan sonar data forming a large and unique collection of datasets based on 4 field campaigns in Øresund...... of the distribution maps and to be combined with biogeochemical models describing spatiotemporal population dynamics. Finally, the use of side-scan sonar data is illustrated in a data fusion exercise combining side-scan sonar data with the results based on echo sounder measurements. The feasible use of side......-scan sonar for mapping of benthic communities remains an open task to be studied in the future. The data processing methodology developed is a contribution to the emerging field of hydroacoustic marine biology. The method of penalised maximum pseudo-likelihood for estimation of the Ising model under a huge...

  14. Response of Submerged Macrophyte Communities to External and Internal Restoration Measures in North Temperate Shallow Lakes

    Science.gov (United States)

    Hilt, Sabine; Alirangues Nuñez, Marta M.; Bakker, Elisabeth S.; Blindow, Irmgard; Davidson, Thomas A.; Gillefalk, Mikael; Hansson, Lars-Anders; Janse, Jan H.; Janssen, Annette B. G.; Jeppesen, Erik; Kabus, Timm; Kelly, Andrea; Köhler, Jan; Lauridsen, Torben L.; Mooij, Wolf M.; Noordhuis, Ruurd; Phillips, Geoff; Rücker, Jacqueline; Schuster, Hans-Heinrich; Søndergaard, Martin; Teurlincx, Sven; van de Weyer, Klaus; van Donk, Ellen; Waterstraat, Arno; Willby, Nigel; Sayer, Carl D.

    2018-01-01

    Submerged macrophytes play a key role in north temperate shallow lakes by stabilizing clear-water conditions. Eutrophication has resulted in macrophyte loss and shifts to turbid conditions in many lakes. Considerable efforts have been devoted to shallow lake restoration in many countries, but long-term success depends on a stable recovery of submerged macrophytes. However, recovery patterns vary widely and remain to be fully understood. We hypothesize that reduced external nutrient loading leads to an intermediate recovery state with clear spring and turbid summer conditions similar to the pattern described for eutrophication. In contrast, lake internal restoration measures can result in transient clear-water conditions both in spring and summer and reversals to turbid conditions. Furthermore, we hypothesize that these contrasting restoration measures result in different macrophyte species composition, with added implications for seasonal dynamics due to differences in plant traits. To test these hypotheses, we analyzed data on water quality and submerged macrophytes from 49 north temperate shallow lakes that were in a turbid state and subjected to restoration measures. To study the dynamics of macrophytes during nutrient load reduction, we adapted the ecosystem model PCLake. Our survey and model simulations revealed the existence of an intermediate recovery state upon reduced external nutrient loading, characterized by spring clear-water phases and turbid summers, whereas internal lake restoration measures often resulted in clear-water conditions in spring and summer with returns to turbid conditions after some years. External and internal lake restoration measures resulted in different macrophyte communities. The intermediate recovery state following reduced nutrient loading is characterized by a few macrophyte species (mainly pondweeds) that can resist wave action allowing survival in shallow areas, germinate early in spring, have energy-rich vegetative

  15. Response of Submerged Macrophyte Communities to External and Internal Restoration Measures in North Temperate Shallow Lakes.

    Science.gov (United States)

    Hilt, Sabine; Alirangues Nuñez, Marta M; Bakker, Elisabeth S; Blindow, Irmgard; Davidson, Thomas A; Gillefalk, Mikael; Hansson, Lars-Anders; Janse, Jan H; Janssen, Annette B G; Jeppesen, Erik; Kabus, Timm; Kelly, Andrea; Köhler, Jan; Lauridsen, Torben L; Mooij, Wolf M; Noordhuis, Ruurd; Phillips, Geoff; Rücker, Jacqueline; Schuster, Hans-Heinrich; Søndergaard, Martin; Teurlincx, Sven; van de Weyer, Klaus; van Donk, Ellen; Waterstraat, Arno; Willby, Nigel; Sayer, Carl D

    2018-01-01

    Submerged macrophytes play a key role in north temperate shallow lakes by stabilizing clear-water conditions. Eutrophication has resulted in macrophyte loss and shifts to turbid conditions in many lakes. Considerable efforts have been devoted to shallow lake restoration in many countries, but long-term success depends on a stable recovery of submerged macrophytes. However, recovery patterns vary widely and remain to be fully understood. We hypothesize that reduced external nutrient loading leads to an intermediate recovery state with clear spring and turbid summer conditions similar to the pattern described for eutrophication. In contrast, lake internal restoration measures can result in transient clear-water conditions both in spring and summer and reversals to turbid conditions. Furthermore, we hypothesize that these contrasting restoration measures result in different macrophyte species composition, with added implications for seasonal dynamics due to differences in plant traits. To test these hypotheses, we analyzed data on water quality and submerged macrophytes from 49 north temperate shallow lakes that were in a turbid state and subjected to restoration measures. To study the dynamics of macrophytes during nutrient load reduction, we adapted the ecosystem model PCLake. Our survey and model simulations revealed the existence of an intermediate recovery state upon reduced external nutrient loading, characterized by spring clear-water phases and turbid summers, whereas internal lake restoration measures often resulted in clear-water conditions in spring and summer with returns to turbid conditions after some years. External and internal lake restoration measures resulted in different macrophyte communities. The intermediate recovery state following reduced nutrient loading is characterized by a few macrophyte species (mainly pondweeds) that can resist wave action allowing survival in shallow areas, germinate early in spring, have energy-rich vegetative

  16. Carbon dioxide and submersed macrophytes in lakes: linking functional ecology to community composition.

    Science.gov (United States)

    Titus, John E; Pagano, Angela M

    2017-12-01

    Evaluating plant community response to atmospheric CO 2 rise is critical to predicting ecosystem level change. Freshwater lakes offer a model system for examining CO 2 effects as submersed macrophyte species differ greatly in their growth responses to CO 2 enrichment, and free CO 2 concentrations among these habitats show a wide range of natural, spatial variation. We determined free CO 2 concentrations in the water column and sediment porewater in littoral zones with pH macrophyte communities coupled with greenhouse-derived growth responses to CO 2 enrichment of constituent species to test two hypotheses: (1) CCRI, which is higher for communities dominated by species with greater growth responses to CO 2 enrichment, is positively correlated to free [CO 2 ] in the water column, and (2) in natural communities, the percent of sediment CO 2 -using species, which are relatively unresponsive to CO 2 enrichment, is negatively correlated to free [CO 2 ]. A significant positive correlation (P = 0.003) between our physiologically based CCRI and the concentration of free CO 2 in the water column supported our primary hypothesis that sites with higher levels of free CO 2 are dominated by species with greater growth responses to CO 2 enrichment. Our CCRI is also highly significantly correlated (P macrophyte community composition. Further, we demonstrate the utility of a physiologically-based index of community composition, our CCRI, as an ecologically valid measure of community response to CO 2 . © 2017 by the Ecological Society of America.

  17. Effect of Hydrologic Alteration on the Community Succession of Macrophytes at Xiangyang Site, Hanjiang River, China.

    Science.gov (United States)

    Yang, Na; Zhang, Yehui; Duan, Kai

    2017-01-01

    With the intensification of human activities over the past three decades in China, adverse effects on river ecosystem become more serious especially in the Hanjiang River. Xiangyang site is an important spawn ground for four domestic fishes in the downstream region of Hanjiang River. Based on the field survey results of macrophytes during 1997-2000 and 2013-2014, community succession of aquatic macrophytes at Xiangyang site was evaluated and discussed. Two-key ecologic-related hydrologic characteristics, flow regime and water level, were identified as the main influence factors. The EFC (environmental flow components) parameters were adopted to evaluate the alteration of flow regimes at Xiangyang site during 1941-2013. Evaluation results demonstrate a highly altered flow process after being regulated by reservoir. The flow patterns tend to be an attenuation process with no large floods occurring but a higher monthly low flow. Furthermore, the water level decreased and fluctuation reduced after the dam was built, which caused the decrease of biomass but favored the submerged macrophytes during 1995-2009. However, with the water level increasing after 2010 and gently fluctuating, due to uplift by the hydraulic projects downstream as well as the flow attenuation, the dominant position of submerged macrophytes will be weakened.

  18. The effects of artificial sandbar breaching on the macrophyte communities of an intermittently open estuary

    Science.gov (United States)

    Ribeiro, Jose Pedro N.; Saggio, Ângelo; Lima, Maria Inês Salgueiro

    2013-04-01

    Artificial sandbar opening of intermittently open estuaries is a practice utilised worldwide to improve water quality, fishing, and recreational amenities and to prevent the flooding of adjacent properties. Breaching causes the water level to drop drastically, exposing plants to two water level extremes. With some exceptions, estuarine communities are adversely affected by this practice. Although breaching can happen naturally, artificial breaching is on the rise, and the impact of manipulating water levels on estuarine communities needs to be investigated. In this work, we described the breaching cycles of the Massaguaçu River Estuary and proposed flooding scenarios for the estuary's macrophyte banks based on our data. We calculated the relationship between plant distribution and flooding conditions and used our calculations to predict the estuary community's composition depending on the water level at breaching time. We discovered a strong relationship between plant distribution and flooding conditions, and we predicted that the estuarine community would be markedly different between flooding scenarios. Low frequency flooding scenarios would be related to submerged macrophytes and, as the flooding frequency increases, macrophytes would be replaced by amphibious plants, and eventually by the arboreal stratus. Therefore, we concluded that an increase in artificial breaching cycles would have a detrimental impact on the estuary community.

  19. Do Amplitudes of Water Level Fluctuations Affect the Growth and Community Structure of Submerged Macrophytes?

    Science.gov (United States)

    Wang, Mo-Zhu; Liu, Zheng-Yuan; Luo, Fang-Li; Lei, Guang-Chun; Li, Hong-Li

    2016-01-01

    Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii) and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm) of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm) were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions.

  20. Do Amplitudes of Water Level Fluctuations Affect the Growth and Community Structure of Submerged Macrophytes?

    Directory of Open Access Journals (Sweden)

    Mo-Zhu Wang

    Full Text Available Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions.

  1. Do Amplitudes of Water Level Fluctuations Affect the Growth and Community Structure of Submerged Macrophytes?

    Science.gov (United States)

    Wang, Mo-Zhu; Liu, Zheng-Yuan; Luo, Fang-Li; Lei, Guang-Chun; Li, Hong-Li

    2016-01-01

    Submerged macrophytes are subjected to potential mechanical stresses associated with fluctuating water levels in natural conditions. However, few experimental studies have been conducted to further understand the effects of water level fluctuating amplitude on submerged macrophyte species and their assemblages or communities. We designed a controlled experiment to investigate the responses of three submerged macrophyte species (Hydrilla verticillata, Ceratophyllum demersum and Elodea nuttallii) and their combinations in communities to three amplitudes (static, ± 30 cm, ± 60 cm) of water level fluctuations. Results showed that water level fluctuating amplitude had little effects on the community performance and the three tested species responded differently. H. verticillata exhibited more growth in static water and it was negatively affected by either of the water level fluctuations amplitude, however, growth parameters of H. verticillata in two fluctuating water level treatments (i.e., ± 30 cm, ± 60 cm) were not significantly different. On the other hand, the growth of C. demersum was not significantly correlated with different amplitude treatments. However, it became more abundant when water levels fluctuated. E. nuttallii was inhibited by the two fluctuating water level treatments, and was less in growth parameters compared to the other species especially in water level fluctuating conditions. The inherent differences in the adaptive capabilities of the tested species indicate that C. demersum or other species with similar responses may be dominant species to restore submerged macrophyte communities with great fluctuating water levels. Otherwise, H. verticillata, E. nuttallii or other species with similar responses could be considered for constructing the community in static water conditions. PMID:26735689

  2. Differences in planktonic microbial communities associated with three types of macrophyte stands in a shallow lake.

    Science.gov (United States)

    Mentes, Anikó; Szabó, Attila; Somogyi, Boglárka; Vajna, Balázs; Tugyi, Nóra; Csitári, Bianka; Vörös, Lajos; Felföldi, Tamás

    2018-02-01

    Little is known about how various substances from living and decomposing aquatic macrophytes affect the horizontal patterns of planktonic bacterial communities. Study sites were located within Lake Kolon, which is a freshwater marsh and can be characterised by open-water sites and small ponds with different macrovegetation (Phragmites australis, Nymphea alba and Utricularia vulgaris). Our aim was to reveal the impact of these macrophytes on the composition of the planktonic microbial communities using comparative analysis of environmental parameters, microscopy and pyrosequencing data. Bacterial 16S rRNA gene sequences were dominated by members of phyla Proteobacteria (36%-72%), Bacteroidetes (12%-33%) and Actinobacteria (5%-26%), but in the anoxic sample the ratio of Chlorobi (54%) was also remarkable. In the phytoplankton community, Cryptomonas sp., Dinobryon divergens, Euglena acus and chrysoflagellates had the highest proportion. Despite the similarities in most of the measured environmental parameters, the inner ponds had different bacterial and algal communities, suggesting that the presence and quality of macrophytes directly and indirectly controlled the composition of microbial plankton. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Benthic freshwater nematode community dynamics under conditions ...

    African Journals Online (AJOL)

    Studies of the influence of fish aquaculture on benthic freshwater nematode assemblages are scarce, but could provide a way of gauging environmental effects. The abundance and diversity of nematode assemblages in response to Oreochromis niloticus aquaculture were investigated in Kafr El-Sheikh Governorate, Egypt, ...

  4. Macrophyte Communities of Andean Rivers: Composition and Relation with Environmental Factors

    OpenAIRE

    Alida Marcela Gómez Rodríguez; Luz Teresa Valderrama Valderrama; Carlos A. Rivera-Rondón

    2017-01-01

    Small streams of tropical Andes have been poorly studied. Therefore, there is little information about the structure, dynamics and function of their macrophyte communities. In this research, aquatic plant communities of 18 Andean streams of La Vieja (Quindío) and Otún (Risaralda) river basins were studied; those are some of the basins most affected by anthropic activities in the country. Streams were selected according to their association with the main land’s uses of the region in both basin...

  5. Benthic macroinvertebrate community of a fourth order stream in ...

    African Journals Online (AJOL)

    cinthia

    Full Length Research Paper. Benthic macroinvertebrate community of a fourth order stream in Kashmir Himalaya, India. Shazia Habib1* and A.R. Yousuf2. 1Department of Environmental Science, University of Kashmir, Srinagar, India. 2National Green Tribunal, Government of India, India. Received 31 December, 2013; ...

  6. Microbial community diversity and composition varies with habitat characteristics and biofilm function in macrophyte-rich streams

    DEFF Research Database (Denmark)

    Levi, Peter S.; Starnawski, Piotr; Poulsen, Britta

    2017-01-01

    Biofilms in streams play an integral role in ecosystem processes and function yet few studies have investigated the broad diversity of these complex prokaryotic and eukaryotic microbial communities. Physical habitat characteristics can affect the composition and abundance of microorganisms...... in these biofilms by creating microhabitats. Here we describe the prokaryotic and eukaryotic microbial diversity of biofilms in sand and macrophyte habitats (i.e. epipsammon and epiphyton, respectively) in five macrophyte-rich streams in Jutland, Denmark. The macrophyte species varied in growth morphology, C......:N stoichiometry, and preferred stream habitat, providing a range in environmental conditions for the epiphyton. Among all habitats and streams, the prokaryotic communities were dominated by common phyla, including Alphaproteobacteria, Bacteriodetes, and Gammaproteobacteria, while the eukaryotic communities were...

  7. Benthic community structures in the North Sea

    Science.gov (United States)

    Heip, C.; Craeymeersch, J. A.

    1995-03-01

    Coherent assemblages of marine benthic species have been recognized from the early twentieth century, and the classical papers of Petersen (1914, 1918) were based on studies of limited areas in the North Sea. In 1986, a synoptic survey of the North Sea north to 57°N was undertaken by a group of ten laboratories from seven North Sea countries. The results of this survey have recently been published (Heip et al., 1992a, b; Künitzer et al., 1992; Huys et al., 1992), and some of the results are summarized in this paper. The analysis of the macrofauna is based on slightly more than 700 taxa. In general, the North Sea macrofauna consists of northern species extending south to the northern margins of the Dogger Bank, and southern species extending north to the 100 m depth line. The central North Sea is an area of overlap of southern and northern species, especially around the 70 m depth contour. Consistent groupings of species are recognized that were summarized in seven faunal groupings. Macrofaunal body weight, density and diversity increase linearly towards the north. Macrofaunal biomass for the whole area averages 7 g adwt. m-2 and decreases from south to north. Distribution patterns and trends within the meiofauna were very different. Nematodes, which are the dominant taxon overall, are least abundant in the sandy sediments of the Southern Bight, then increase to a maximum around 53° 30' N and slowly decrease again towards the north. Copepod density and diversity are highest in the Southern Bight, due to the presence of many interstitial species. A large number of species new to science were recorded by the North Sea Benthos Survey and about 1500 species are expected to occur. Copepods show very distinct assemblages according to water depth and sediment type. The contrasting patterns in latitudinal gradients of body weight and number of species of macro- and meiofauna can be only partially explained. Latitude and sediment characteristics, such as grain size and

  8. Investigation of Darwin’s naturalization hypothesis in invaded macrophyte communities

    Science.gov (United States)

    Although native macrophytes are beneficial in aquatic ecosystems, invasive macrophytes can cause significant ecological and economic harm. Numerous studies have attributed invasiveness to species’ characteristics, whereas others attribute invasion to biotic and abiotic characteristics of the invaded...

  9. Retrospective assessment of macrophytic communities in southern Lake Garda (Italy from in situ and MIVIS (Multispectral Infrared and Visible Imaging Spectrometer data

    Directory of Open Access Journals (Sweden)

    Claudia Giardino

    2012-01-01

    Full Text Available In situ and hyperspectral MIVIS (Multispectral Infrared and Visible Imaging Spectrometer images acquired over a period of 13 years are used to assess changes in macrophyte colonization patterns in the coastal zones of the Sirmione Peninsula in the southern part of Lake Garda (Italy. In situ data (abundance, cover density and diversity of macrophyte communities and MIVIS-derived maps of colonized substrates are analyzed by considering the variability of the main hydrological and physicochemical variables in order to indicate the main factors that explain the spatiotemporal variability of macrophyte communities. The results show a considerable modification in terms of macrophyte structural complexity and colonized areas. Almost 98% of macrophyte meadows (in particular communities with a density of over 70% are lost and subsequently replaced by moderate to extremely rare communities with density from 10% to 40%. Well-established submerged macrophytes are replaced by de-structured communities characterized by moderate to scarce density: on average lower than 30%. The study indicates that macrophyte distribution along the littoral zone of the Sirmione Peninsula is certainly linked to water transparency and water level fluctuation. The results also indicate that the worsening of eutrophication may be associated with the gradual disappearance of macrophyte meadows, but may also be accelerated by herbivorous aquatic birds grazing there. Lastly, the increasing frequency and number of catamaran tours could be considered a threat for the stability of these valuable communities.

  10. Water quality and communities associated with macrophytes in a shallow water-supply reservoir on an aquaculture farm.

    Science.gov (United States)

    Sipaúba-Tavares, L H; Dias, S G

    2014-05-01

    Plankton communities and macrofauna associated to aquatic macrophyte stands in a shallow water-supply reservoir (21°14'09″S; 48°18'38″W) on an aquaculture farm were compared to evaluate the relationship between organism densities and some abiotic features of the reservoir. Water and communities associated were sampled at two sites, one in an area with the predominance of Eichhornia azurea (Sw.) Kunth and the other with the predominance of Salvinia auriculata Aublet. Communities associated with macrophytes were sampled with floating quadrants (0.5 m2); the macrophytes were washed and plankton and macrofauna were fixated with 4% formalin and 1% lugol iodine; the specimens were then identified and counted. Plankton and macrofauna communities associated with S. auriculata and E. azurea had a similar diversity of species but different (pmacrophytes presence in the shallow reservoir is a strong predictor of favourable conditions to maintain great diversity plankton community and macrofauna associated with plants. The role of macrophytes is important for not only stabilising the clear-water state and maintaining high diversity of organisms associated, but also it seems to be a good alternative to maintaining desirable water-supply quality for aquaculture farms.

  11. The role of pH in structuring communities of Maine wetland macrophytes and chironomid larvae (Diptera)

    Science.gov (United States)

    Woodcock, T.S.; Longcore, J.R.; McAuley, D.G.; Mingo, T.M.; Bennatti, C.R.; Stromborg, K.L.

    2005-01-01

    Aquatic vascular plants, or macrophytes, are an important habitat component for many wetland organisms, and larvae of chironomid midges are ubiquitous components of wetland fauna. Many chironomids are primary consumers of algae and detritus and form an essential energetic link between allochthonous and autochthonous primary production and higher trophic levels, while others are predators and feed on smaller invertebrates. Live macrophytes serve mostly as habitat, whereas plant detritus serves as both habitat and as a food source. Assemblages of macrophytes and chironomid larvae were surveyed in ten Maine wetlands, five with low pH (5.5), and explained in terms of physical and chemical habitat variables. Macrophyte richness was significantly greater, and richness of chironomid larvae was lower, in low pH wetlands. There was no difference in chironomid abundance related to pH. However, community structure was related to pH, suggesting that competitive dominance of a few taxa was responsible for lower richness in low pH wetlands, whereas competition was weaker in high pH wetlands, making coexistence of more chironomid taxa possible. An examination of individual chironomid taxa by stepwise multiple regression showed that distribution of most taxa was controlled by water chemistry variables and macrophyte habit (i.e., floating, submergent).

  12. Predicting Changes in Macrophyte Community Structure from Functional Traits in a Freshwater Lake: A Test of Maximum Entropy Model

    Science.gov (United States)

    Fu, Hui; Zhong, Jiayou; Yuan, Guixiang; Guo, Chunjing; Lou, Qian; Zhang, Wei; Xu, Jun; Ni, Leyi; Xie, Ping; Cao, Te

    2015-01-01

    Trait-based approaches have been widely applied to investigate how community dynamics respond to environmental gradients. In this study, we applied a series of maximum entropy (maxent) models incorporating functional traits to unravel the processes governing macrophyte community structure along water depth gradient in a freshwater lake. We sampled 42 plots and 1513 individual plants, and measured 16 functional traits and abundance of 17 macrophyte species. Study results showed that maxent model can be highly robust (99.8%) in predicting the species relative abundance of macrophytes with observed community-weighted mean (CWM) traits as the constraints, while relative low (about 30%) with CWM traits fitted from water depth gradient as the constraints. The measured traits showed notably distinct importance in predicting species abundances, with lowest for perennial growth form and highest for leaf dry mass content. For tuber and leaf nitrogen content, there were significant shifts in their effects on species relative abundance from positive in shallow water to negative in deep water. This result suggests that macrophyte species with tuber organ and greater leaf nitrogen content would become more abundant in shallow water, but would become less abundant in deep water. Our study highlights how functional traits distributed across gradients provide a robust path towards predictive community ecology. PMID:26167856

  13. Spatial and temporal heterogeneity in a subtropical reservoir and their effects over the benthic macroinvertebrate community

    Directory of Open Access Journals (Sweden)

    Frederico Guilherme de Souza Beghelli

    2014-09-01

    Full Text Available AIM: The objective of the present study was to demonstrate the influences of the environment spatial heterogeneity on benthic macroinvertebrates considering transverse and longitudinal gradients as also seasonality. METHODS: Four samplings were performed: two in the wet and two in the dry season in the riverine, transitional and lacustrine zones in the littoral and profundal regions of Itupararanga reservoir, SP, Brazil. Abiotic characterization of the water and of the sediment was performed. The biotic characterization was based on richness, dominance, diversity, and density of organisms, as well as on the relative abundance of predominant taxa. Two-way ANOSIM analyses were performed for both biotic and abiotic components, in order to test the significance of the differences in the longitudinal and transverse directions as well as of the differences between seasons. RESULTS: Compartmentalization was present in both directions, longitudinal and transverse. In a general way, the littoral region presented higher diversity values when compared with the profundal region, and the riverine zone presented high densities and high percentage of taxons, which usually indicate organic pollution. The differentiation between the transitional and lacustrine zones was determined mainly by taxonomic composition. Seasonality was also observed and the transportation of small particles, the entrance of nutrients, and the presence of macrophytes were considered as determinants for differentiation. CONCLUSIONS: Together, these results demonstrate the responses of benthic macroinvertebrate communities considering distinct sources of variation: longitudinal heterogeneity, determined by the increasing distance from the forming rivers that leads to a gradient of physical and chemical conditions; transverse heterogeneity, determined by the proximity with the land environment and depth differences. Seasonal heterogeneity was recorded during the period of this research and

  14. Interlinking backscatter, grain size and benthic community structure

    Science.gov (United States)

    McGonigle, Chris; Collier, Jenny S.

    2014-06-01

    The relationship between acoustic backscatter, sediment grain size and benthic community structure is examined using three different quantitative methods, covering image- and angular response-based approaches. Multibeam time-series backscatter (300 kHz) data acquired in 2008 off the coast of East Anglia (UK) are compared with grain size properties, macrofaunal abundance and biomass from 130 Hamon and 16 Clamshell grab samples. Three predictive methods are used: 1) image-based (mean backscatter intensity); 2) angular response-based (predicted mean grain size), and 3) image-based (1st principal component and classification) from Quester Tangent Corporation Multiview software. Relationships between grain size and backscatter are explored using linear regression. Differences in grain size and benthic community structure between acoustically defined groups are examined using ANOVA and PERMANOVA+. Results for the Hamon grab stations indicate significant correlations between measured mean grain size and mean backscatter intensity, angular response predicted mean grain size, and 1st principal component of QTC analysis (all p PERMANOVA for the Hamon abundance shows benthic community structure was significantly different between acoustic groups for all methods (p ≤ 0.001). Overall these results show considerable promise in that more than 60% of the variance in the mean grain size of the Clamshell grab samples can be explained by mean backscatter or acoustically-predicted grain size. These results show that there is significant predictive capacity for sediment characteristics from multibeam backscatter and that these acoustic classifications can have ecological validity.

  15. Food choice effects on herbivory: Intra-specific seagrass palatability and inter-specific macrophyte palatability in seagrass communities

    Science.gov (United States)

    Jiménez-Ramos, Rocío; Brun, Fernando G.; Egea, Luis G.; Vergara, Juan J.

    2018-05-01

    Interactions between the palatability and abundance of different food sources may influence herbivory patterns in seagrass-dominated communities. In addition, intra-specific differences in nutrient and structural quality of leaves may also alter seagrass palatability and generate different rates of consumption within these communities. We offered two temperate seagrasses species, (Cymodocea nodosa and Zostera noltei) from two different locations to look at intraspecific differences, and two other macrophytes, both of which occur at the same location as seagrasses but represent the extremes of palatability, to a generalist herbivore Paracentrotus lividus (purple sea urchin). Using feeding assays, we compared the consumption rates in individual (single plant species) and combined diets at different food availabilities. Intra-specific differences between seagrass species growing at different locations (inner and outer bay) were indeed found to significantly modify the consumption rate for one species. Structural traits such as carbon content were linked to the low consumption found in Cymodocea nodosa from the inner bay location. In addition, we found that the co-occurrence of different macrophyte species can result in preferential consumption of the more palatable macrophyte with high nutritional content and low structural defence over seagrasses, especially when P. lividus has an abundant food supply. Overall, our findings suggest that intra- and inter-specific differences in seagrass traits and the relative abundance of other macrophytes may explain the variability in patterns of herbivory found within seagrass communities.

  16. [Impacts of large hydropower station on benthic algal communities].

    Science.gov (United States)

    Jia, Xing-Huan; Jiang, Wan-Xiang; Li, Feng-Qing; Tang, Tao; Duan, Shu-Gui; Cai, Qing-Hua

    2009-07-01

    To investigate the impacts of large hydropower station in Gufu River on benthic algae, monthly samplings were conducted from September 2004 to June 2007 at the site GF04 which was impacted by the hydropower station, with the site GL03 in Gaolan River as reference. During sampling period, no significant differences were observed in the main physicochemical variables between GF04 and GL03, but the hydrodynamics differed significantly. GL03 was basically at a status of slow flow; while GF04, owing to the discharging from the reservoir, was at a riffle status during more than 60% of the sampling period. Such a difference in hydrodynamics induced significant differences in the community similarity of benthic algae and the relative abundance of unattached diatoms, erect diatoms, and stalked diatoms between GF04 and GL03, which could better reflect the impacts of irregular draw-off by large hydropower station on river eco-system.

  17. Submerged macrophyte communities in the Forsmark area. Building of a GIS application as a tool for biomass estimations

    International Nuclear Information System (INIS)

    Fredriksson, Ronny

    2005-12-01

    The aim of this study was to compile the information from previous studies to produce a GIS application that both illustrates the distribution of different vegetation communities and also makes it possible to estimate the total biomass of the different vegetation communities and its associated fauna. The GIS application was created by means of the software Arc View 3.3 by Environmental Systems Research Institute, Inc. Distribution readings and quantitative data of submerged macrophyte communities and its associated fauna was obtained from studies by Kautsky et al. and by Borgiel. Information about the macrophyte distribution in Laangoersviken, located in the northern parts of Kallrigafjaerden, was obtained from a report by Upplandsstiftelsen. Information about water depth and bottom substrate was available as USGS DEM file, produced by Geological Survey of Sweden. Complementary data of the covering degree of submerged vegetation was obtained from a study using an under water video camera by Tobiasson. Quantitative data on macrophyte and faunal biomass were either obtained from the primary SKB data base SICADA or directly from reports. Samples were compiled and analysed according to dominating vegetation. The work was carried out as follows: Where information about the bottom substrate was available polygons were created by means of the substrate shape file and depth grid from Geological Survey of Sweden. The vegetation community and the covering degree on a certain depth and substrate combination were determined by compiled information from studies by Kautsky and by Borgiel. All observations from a certain bottom substrate were analysed to find the dominating vegetation within different depth ranges. After determining the dominating vegetation, the covering degrees of different macrophyte classes within each depth range were calculated as a mean of all readings. Areas without information about the bottom substrate, but still adjacent to areas included in the

  18. Submerged macrophyte communities in the Forsmark area. Building of a GIS application as a tool for biomass estimations

    Energy Technology Data Exchange (ETDEWEB)

    Fredriksson, Ronny [Univ. of Kalmar (Sweden)

    2005-12-15

    The aim of this study was to compile the information from previous studies to produce a GIS application that both illustrates the distribution of different vegetation communities and also makes it possible to estimate the total biomass of the different vegetation communities and its associated fauna. The GIS application was created by means of the software Arc View 3.3 by Environmental Systems Research Institute, Inc. Distribution readings and quantitative data of submerged macrophyte communities and its associated fauna was obtained from studies by Kautsky et al. and by Borgiel. Information about the macrophyte distribution in Laangoersviken, located in the northern parts of Kallrigafjaerden, was obtained from a report by Upplandsstiftelsen. Information about water depth and bottom substrate was available as USGS DEM file, produced by Geological Survey of Sweden. Complementary data of the covering degree of submerged vegetation was obtained from a study using an under water video camera by Tobiasson. Quantitative data on macrophyte and faunal biomass were either obtained from the primary SKB data base SICADA or directly from reports. Samples were compiled and analysed according to dominating vegetation. The work was carried out as follows: Where information about the bottom substrate was available polygons were created by means of the substrate shape file and depth grid from Geological Survey of Sweden. The vegetation community and the covering degree on a certain depth and substrate combination were determined by compiled information from studies by Kautsky and by Borgiel. All observations from a certain bottom substrate were analysed to find the dominating vegetation within different depth ranges. After determining the dominating vegetation, the covering degrees of different macrophyte classes within each depth range were calculated as a mean of all readings. Areas without information about the bottom substrate, but still adjacent to areas included in the

  19. Inorganic carbon availability in benthic diatom communities: photosynthesis and migration.

    Science.gov (United States)

    Marques da Silva, Jorge; Cruz, Sónia; Cartaxana, Paulo

    2017-09-05

    Diatom-dominated microphytobenthos (MPB) is the main primary producer of many intertidal and shallow subtidal environments, being therefore of critical importance to estuarine and coastal food webs. Owing to tidal cycles, intertidal MPB diatoms are subjected to environmental conditions far more variable than the ones experienced by pelagic diatoms (e.g. light, temperature, salinity, desiccation and nutrient availability). Nevertheless, benthic diatoms evolved adaptation mechanisms to these harsh conditions, including the capacity to move within steep physical and chemical gradients, allowing them to perform photosynthesis efficiently. In this contribution, we will review present knowledge on the effects of dissolved inorganic carbon (DIC) availability on photosynthesis and productivity of diatom-dominated MPB. We present evidence of carbon limitation of photosynthesis in benthic diatom mats and highly productive MPB natural communities. Furthermore, we hypothesize that active vertical migration of epipelic motile diatoms could overcome local depletion of DIC in the photic layer, providing the cells alternately with light and inorganic carbon supply. The few available longer-term experiments on the effects of inorganic carbon enrichment on the productivity of diatom-dominated MPB have yielded inconsistent results. Therefore, further studies are needed to properly assess the response of MPB communities to increased CO 2 and ocean acidification related to climate change.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'. © 2017 The Author(s).

  20. Fish-derived nutrient hotspots shape coral reef benthic communities.

    Science.gov (United States)

    Shantz, Andrew A; Ladd, Mark C; Schrack, Elizabeth; Burkepile, Deron E

    2015-12-01

    Animal-derived nutrients play an important role in structuring nutrient regimes within and between ecosystems. When animals undergo repetitive, aggregating behavior through time, they can create nutrient hotspots where rates of biogeochemical activity are higher than those found in the surrounding environment. In turn, these hotspots can influence ecosystem processes and community structure. We examined the potential for reef fishes from the family Haemulidae (grunts) to create nutrient hotspots and the potential impact of these hotspots on reef communities. To do so, we tracked the schooling locations of diurnally migrating grunts, which shelter at reef sites during the day but forage off reef each night, and measured the impact of these fish schools on benthic communities. We found that grunt schools showed a high degree of site fidelity, repeatedly returning to the same coral heads. These aggregations created nutrient hotspots around coral heads where nitrogen and phosphorus delivery was roughly 10 and 7 times the respective rates of delivery to structurally similar sites that lacked schools of these fishes. In turn, grazing rates of herbivorous fishes at grunt-derived hotspots were approximately 3 times those of sites where grunts were rare. These differences in nutrient delivery and grazing led to distinct benthic communities with higher cover of crustose coralline algae and less total algal abundance at grunt aggregation sites. Importantly, coral growth was roughly 1.5 times greater at grunt hotspots, likely due to the important nutrient subsidy. Our results suggest that schooling reef fish and their nutrient subsidies play an important role in mediating community structure on coral reefs and that overfishing may have important negative consequences on ecosystem functions. As such, management strategies must consider mesopredatory fishes in addition to current protection often offered to herbivores and top-tier predators. Furthermore, our results suggest that

  1. Human exploitation and benthic community structure on a tropical intertidal mudflat

    NARCIS (Netherlands)

    Boer, de W.F.; Prins, H.H.T.

    2002-01-01

    Human exploitation of intertidal marine invertebrates is known to alter benthic community structure. This study describes the impact that harvesting by women and children has on the intertidal community structure of the mudflats of the Saco on Inhaca Island, Mozambique, by comparing the benthic

  2. Shear Stress and Sediment Resuspension in Canopy-and Meadow-Forming Submersed Macrophyte Communities

    National Research Council Canada - National Science Library

    James, William

    2001-01-01

    .... Studies were conducted at Lake Christina, Minnesota, in late August-early September 1998, when macrophyte biomass levels exceeded 200 g/m2 and in June 2000, when biomass was greatly reduced (<20 g/m2...

  3. Comparison of aquatic macrophyte community structure between natural wetlands and rice fields with different cultivation ages

    OpenAIRE

    Rolon, A. S.; Godoy, R. S.; Maltchik, L.

    2017-01-01

    Abstract Recent studies indicate that rice fields contribute to the conservation of aquatic plants, however, repeated cultivation can reduce the species diversity harbored by rice fields. Repeated tillage, agrochemical application and environmental homogeneity can reduce plant diversity and select for species more tolerant to disturbance. Our hypotheses were: 1) macrophyte richness and biomass decrease with increased rice crop age; and 2) macrophyte species of rice fields are a subsample of n...

  4. Impact of acidification and eutrophication on macrophyte communities in soft waters in The Netherlands

    Energy Technology Data Exchange (ETDEWEB)

    Roelofs, J G.M.

    1983-01-01

    During the last decades a strong decline has been noticed in the number of waters dominated by Littorellion species, mostly isoetids such as Lobelia dortmanna L., Isoetes lacustris L. and Littorella uniflora (L.) Aschers. Sixty-eight waters, which were known to be dominated by L. uniflora after 1950 were investigated. In 1980, L. uniflora appeared to be absent or to have strongly decreased in 53 (78%) of the waters. In 41 of them, Littorella had been replaced by submerged Juncus bulbosus L. and/or Sphagnum spp. These changes seem to have been caused by changed inorganic carbon budgets as a consequence of acidification. In the remaining 12 waters, eutrophication of the water and/or sediment seems to be responsible for the changes in the plant communities. Enrichment with phosphate of the mineral sediment alone, leads to luxurious growth of submerged, rooted macrophyte species such as Myriophyllum alterniflorum DC and Ranunculus peltatus Schrank, whereas phosphate-enrichment of both sediment and water leads to luxurious growth of pleustophytes such as Riccia fluitans L. and Lemna minor L. in small, shallow waters, and to plankton bloom and luxurious growth of epiphytes in larger, deeper waters. In these cases light limitation seems to be responsible for the disappearance or decline of the Littorellion species. 41 references, 1 figure, 4 tables.

  5. Average niche breadths of species in lake macrophyte communities respond to ecological gradients variably in four regions on two continents.

    Science.gov (United States)

    Alahuhta, Janne; Virtala, Antti; Hjort, Jan; Ecke, Frauke; Johnson, Lucinda B; Sass, Laura; Heino, Jani

    2017-05-01

    Different species' niche breadths in relation to ecological gradients are infrequently examined within the same study and, moreover, species niche breadths have rarely been averaged to account for variation in entire ecological communities. We investigated how average environmental niche breadths (climate, water quality and climate-water quality niches) in aquatic macrophyte communities are related to ecological gradients (latitude, longitude, altitude, species richness and lake area) among four distinct regions (Finland, Sweden and US states of Minnesota and Wisconsin) on two continents. We found that correlations between the three different measures of average niche breadths and ecological gradients varied considerably among the study regions, with average climate and average water quality niche breadth models often showing opposite trends. However, consistent patterns were also found, such as widening of average climate niche breadths and narrowing of average water quality niche breadths of aquatic macrophytes along increasing latitudinal and altitudinal gradients. This result suggests that macrophyte species are generalists in relation to temperature variations at higher latitudes and altitudes, whereas species in southern, lowland lakes are more specialised. In contrast, aquatic macrophytes growing in more southern nutrient-rich lakes were generalists in relation to water quality, while specialist species are adapted to low-productivity conditions and are found in highland lakes. Our results emphasise that species niche breadths should not be studied using only coarse-scale data of species distributions and corresponding environmental conditions, but that investigations on different kinds of niche breadths (e.g., climate vs. local niches) also require finer resolution data at broad spatial extents.

  6. Effects of submerged macrophytes on the abundance and community composition of ammonia-oxidizing prokaryotes in a eutrophic lake.

    Science.gov (United States)

    Zhao, Da-yong; Luo, Juan; Zeng, Jin; Wang, Meng; Yan, Wen-ming; Huang, Rui; Wu, Qinglong L

    2014-01-01

    Abundances and community compositions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in unvegetated sediment and the rhizosphere sediments of three submerged macrophytes (Ceratophyllum demersum, Vallisneria spinulosa, and Potamogeton crispus) were investigated in a large, eutrophic freshwater lake, Lake Taihu. Abundances of archaeal ammonia monooxygenase alpha-subunit (amoA) gene (from 6.56 × 10(6) copies to 1.06 × 10(7) copies per gram of dry sediment) were higher than those of bacterial amoA (from 6.13 × 10(5) to 3.21 × 10(6) copies per gram of dry sediment) in all samples. Submerged macrophytes exhibited no significant effect on the abundance and diversity of archaeal amoA gene. C. demersum and V. spinulosa increased the abundance and diversity of bacterial amoA gene in their rhizosphere sediment. However, the diversity of bacterial amoA gene in the rhizosphere sediments of P. crispus was decreased. The data obtained in this study would be helpful to elucidate the roles of submerged macrophytes involved in the nitrogen cycling of eutrophic lake ecosystems.

  7. The Power of Computer-aided Tomography to Investigate Marine Benthic Communities

    Science.gov (United States)

    Utilization of Computer-aided-Tomography (CT) technology is a powerful tool to investigate benthic communities in aquatic systems. In this presentation, we will attempt to summarize our 15 years of experience in developing specific CT methods and applications to marine benthic co...

  8. Benthic communities under anthropogenic pressure show resilience across the Quaternary.

    Science.gov (United States)

    Martinelli, Julieta C; Soto, Luis P; González, Jorge; Rivadeneira, Marcelo M

    2017-09-01

    The Southeast Pacific is characterized by rich upwelling systems that have sustained and been impacted by human groups for at least 12 ka. Recent fishing and aquaculture practices have put a strain on productive coastal ecosystems from Tongoy Bay, in north-central Chile. We use a temporal baseline to determine whether potential changes to community structure and composition over time are due to anthropogenic factors, natural climatic variations or both. We compiled a database ( n  = 33 194) with mollusc species abundances from the Mid-Pleistocene, Late Pleistocene, Holocene, dead shell assemblages and live-sampled communities. Species richness was not significantly different, neither were diversity and evenness indices nor rank abundance distributions. There is, however, an increase in relative abundance for the cultured scallop Argopecten , while the previously dominant clam Mulinia is locally very rare. Results suggest that impacts from both natural and anthropogenic stressors need to be better understood if benthic resources are to be preserved. These findings provide the first Pleistocene temporal baseline for the south Pacific that shows that this highly productive system has had the ability to recover from past alterations, suggesting that if monitoring and management practices continue to be implemented, moderately exploited communities from today have hopes for recovery.

  9. Benthic communities under anthropogenic pressure show resilience across the Quaternary

    Science.gov (United States)

    Martinelli, Julieta C.; Soto, Luis P.; González, Jorge; Rivadeneira, Marcelo M.

    2017-09-01

    The Southeast Pacific is characterized by rich upwelling systems that have sustained and been impacted by human groups for at least 12 ka. Recent fishing and aquaculture practices have put a strain on productive coastal ecosystems from Tongoy Bay, in north-central Chile. We use a temporal baseline to determine whether potential changes to community structure and composition over time are due to anthropogenic factors, natural climatic variations or both. We compiled a database (n = 33 194) with mollusc species abundances from the Mid-Pleistocene, Late Pleistocene, Holocene, dead shell assemblages and live-sampled communities. Species richness was not significantly different, neither were diversity and evenness indices nor rank abundance distributions. There is, however, an increase in relative abundance for the cultured scallop Argopecten, while the previously dominant clam Mulinia is locally very rare. Results suggest that impacts from both natural and anthropogenic stressors need to be better understood if benthic resources are to be preserved. These findings provide the first Pleistocene temporal baseline for the south Pacific that shows that this highly productive system has had the ability to recover from past alterations, suggesting that if monitoring and management practices continue to be implemented, moderately exploited communities from today have hopes for recovery.

  10. Similar effects of bottom trawling and natural disturbance on composition and function of benthic communities across habitats

    NARCIS (Netherlands)

    Denderen, van Daniel; Bolam, Stefan G.; Hiddink, Jan Geert; Jennings, Simon; Kenny, Andrew; Rijnsdorp, Adriaan D.; Kooten, Van Tobias

    2015-01-01

    Bottom trawl fishing has widespread impacts on benthic habitats and communities. The benthic response to trawling seems to be smaller or absent in areas exposed to high natural disturbance, leading to the hypothesis that natural and trawl disturbance affect benthic communities in a similar way.

  11. A multicompartment approach--diatoms, macrophytes, benthic macroinvertebrates and fish--to assess the impact of toxic industrial releases on a small French river.

    Directory of Open Access Journals (Sweden)

    Manon Lainé

    Full Text Available The River Luzou flows through a sandy substrate in the South West of France. According to the results of two assessment surveys, the Water Agency appraised that this river may not achieve the good ecological status by 2015 as required by the Water Framework Directive (2000/60/EC. This ecosystem is impacted by industrial effluents (organic matter, metals and aromatic compounds. In order to assess and characterize the impact, this study aimed to combine a set of taxonomic and non-taxonomic metrics for diatoms, macrophytes, macroinvertebrates and fish along the up- to downstream gradient of the river. Diversity metrics, biological indices, biological and ecological traits were determined for the four biological quality elements (BQE. Various quantitative metrics (biomass estimates were also calculated for diatom communities. The results were compared to physicochemical analysis. Biological measurements were more informative than physicochemical analysis, in the context of the study. Biological responses indicated both the contamination of water and its intensity. Diversity metrics and biological indices strongly decreased with pollution for all BQE but diatoms. Convergent trait selection with pollution was observed among BQE: reproduction, colonization strategies, or trophic regime were clearly modified at impaired sites. Taxon size and relation to the substrate diverged among biological compartments. Multiple anthropogenic pollution calls for alternate assessment methods of rivers' health. Our study exemplifies the fact that, in the case of complex contaminations, biological indicators can be more informative for environmental risk, than a wide screening of contaminants by chemical analysis alone. The combination of diverse biological compartments provided a refined diagnostic about the nature (general mode of action and intensity of the contamination.

  12. A Multicompartment Approach - Diatoms, Macrophytes, Benthic Macroinvertebrates and Fish - To Assess the Impact of Toxic Industrial Releases on a Small French River

    Science.gov (United States)

    Lainé, Manon; Morin, Soizic; Tison-Rosebery, Juliette

    2014-01-01

    The River Luzou flows through a sandy substrate in the South West of France. According to the results of two assessment surveys, the Water Agency appraised that this river may not achieve the good ecological status by 2015 as required by the Water Framework Directive (2000/60/EC). This ecosystem is impacted by industrial effluents (organic matter, metals and aromatic compounds). In order to assess and characterize the impact, this study aimed to combine a set of taxonomic and non-taxonomic metrics for diatoms, macrophytes, macroinvertebrates and fish along the up- to downstream gradient of the river. Diversity metrics, biological indices, biological and ecological traits were determined for the four biological quality elements (BQE). Various quantitative metrics (biomass estimates) were also calculated for diatom communities. The results were compared to physicochemical analysis. Biological measurements were more informative than physicochemical analysis, in the context of the study. Biological responses indicated both the contamination of water and its intensity. Diversity metrics and biological indices strongly decreased with pollution for all BQE but diatoms. Convergent trait selection with pollution was observed among BQE: reproduction, colonization strategies, or trophic regime were clearly modified at impaired sites. Taxon size and relation to the substrate diverged among biological compartments. Multiple anthropogenic pollution calls for alternate assessment methods of rivers' health. Our study exemplifies the fact that, in the case of complex contaminations, biological indicators can be more informative for environmental risk, than a wide screening of contaminants by chemical analysis alone. The combination of diverse biological compartments provided a refined diagnostic about the nature (general mode of action) and intensity of the contamination. PMID:25019954

  13. Baseline assessment of the fish and benthic communities of the Flower Garden Banks (NODC Accession 0118358)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The proposed work develop baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys will employ...

  14. Baseline assessment of fish and benthic communities of the Flower Garden Banks (NODC Accession 0118358)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The proposed work develop baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys will employ...

  15. Baseline assessment of the benthic communities of the Flower Garden Banks

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The work developed baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys employed diving,...

  16. Effects of hydraulic shellfish harvesting on benthic communities and sediment chemistry 2009-2013

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The effects of hydraulic shellfish harvesting on the ecology of biological communities and chemistry of benthic sediments were investigated through a series of...

  17. Guam Community Coral Reef Monitoring Program, Benthic Quadrat Surveys at Guam in 2013

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Guam community members gathered benthic cover data using a 0.25m2 quadrat with 6 intersecting points at each meter along a 25-meter transect. Members identified...

  18. Baseline assessment of fish and benthic communities of the Flower Garden Banks

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The work developed baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys employed diving,...

  19. Baseline assessment of benthic communities of the Flower Garden Banks (2010 - present): 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The proposed work develop baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys will employ...

  20. Ecological periodic tables for nekton and benthic macrofaunal community usage of estuarine habitats Slides

    Science.gov (United States)

    Ecological periodic tables for nekton and benthic macrofaunal community usage of estuarine habitats Steven P. Ferraro, U.S. Environmental Protection Agency, Newport, OR Background/Questions/Methods The chemical periodic table, the Linnaean system of classification, and the Her...

  1. PCB contamination and effects on benthic invertebrate communities at the Irving Whale salvage site

    National Research Council Canada - National Science Library

    Ernst, W

    2000-01-01

    ... patterns of polychlorinated biphenyl (PCB) contamination. In addition, snow crab tissue sampling, toxicity testing of sediments as well as analysis of the integrity of benthic biological communities was conducted around the Irving Whale footprint...

  2. Guam Community Coral Reef Monitoring Program, Benthic Training Surveys at Guam in 2012

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Guam community members gathered benthic cover data using a 0.25m2 quadrat with 6 intersecting points at each meter along a 25-meter transect. Members identified...

  3. Environmental drivers of the benthic macroinvertebrates community in a hypersaline estuary (Northeastern Brazil

    Directory of Open Access Journals (Sweden)

    Carlinda Railly Ferreira Medeiros

    Full Text Available Abstract Introduction The estuarine community of benthic macroinvertebrates spatially varies in response to changes in environmental variables in these ecosystems. Understanding this variability helps our understanding the mechanisms structuring these communities. Aim Assess the structural aspects of the benthic macroinvertebrate community in a hypersaline estuary, and to relate to environmental variables that influence the community structure along the estuary. Methods The study was conducted at Tubarão river estuary in May 2015. We sampled two estuarine areas (upper and lower, and in each zone were sampled six points composed of two replicas, one sampled in sandy bottom and the other in muddy bottom. Samples of benthic macroinvertebrates and estuarine environmental variables were collected. Environmental drivers of the benthic macroinvertebrate community were determined by Distance-based Linear Models analysis. The contribution of individual species to the dissimilarity between the areas and substrate types were determined by analysis of the percentage of similarity. Results The composition of benthic macroinvertebrate community differed between the upper and lower areas, although it was similar between the muddy and sandy bottoms. The variation in the benthic community between areas was mainly related to the influence of salinity in the upper area. In the lower area, the variation of the macroinvertebrates was related to salinity, associated with other variables in the sandy (temperature, turbidity and dissolved oxygen and muddy (temperature, total dissolved solids and dissolved oxygen substrates. Taxa which contributed most to the dissimilarity between the upper and lower areas were Nereididae (17.89%, Anomalocardia brasiliana (15% and Cirratulidae (10.43%. Conclusions Salinity was the main driver of the structural aspects of the benthic macroinvertebrate community in the upper area of the estuary, although in the lower area a set of

  4. Benthic infaunal community structuring in an acidified tropical estuarine system.

    Science.gov (United States)

    Hossain, M Belal; Marshall, David J

    2014-01-01

    Recent studies suggest that increasing ocean acidification (OA) should have strong direct and indirect influences on marine invertebrates. While most theory and application for OA is based on relatively physically-stable oceanic ecological systems, less is known about the effects of acidification on nearshore and estuarine systems. Here, we investigated the structuring of a benthic infaunal community in a tropical estuarine system, along a steep salinity and pH gradient, arising largely from acid-sulphate groundwater inflows (Sungai Brunei Estuary, Borneo, July 2011- June 2012). Preliminary data indicate that sediment pore-water salinity (range: 8.07 - 29.6 psu) declined towards the mainland in correspondence with the above-sediment estuarine water salinity (range: 3.58 - 31.2 psu), whereas the pore-water pH (range: 6.47- 7.72) was generally lower and less variable than the estuarine water pH (range: 5.78- 8.3), along the estuary. Of the thirty six species (taxa) recorded, the polychaetes Neanthes sp., Onuphis conchylega, Nereididae sp. and the amphipod Corophiidae sp., were numerically dominant. Calcified microcrustaceans (e.g., Cyclopoida sp. and Corophiidae sp.) were abundant at all stations and there was no clear distinction in distribution pattern along the estuarine between calcified and non-calcified groups. Species richness increased seawards, though abundance (density) showed no distinct directional trend. Diversity indices were generally positively correlated (Spearman's rank correlation) with salinity and pH (p 0.05). Three faunistic assemblages were distinguished: (1) nereid-cyclopoid-sabellid, (2) corophiid-capitellid and (3) onuphid- nereid-capitellid. These respectively associated with lower salinity/pH and a muddy bottom, low salinity/pH and a sandy bottom, and high salinity/pH and a sandy bottom. However, CCA suggested that species distribution and community structuring is more strongly influenced by sediment particle characteristics than by the

  5. Consequences of increasing hypoxic disturbance on benthic communities and ecosystem functioning.

    Directory of Open Access Journals (Sweden)

    Anna Villnäs

    Full Text Available Disturbance-mediated species loss has prompted research considering how ecosystem functions are changed when biota is impaired. However, there is still limited empirical evidence from natural environments evaluating the direct and indirect (i.e. via biota effects of disturbance on ecosystem functioning. Oxygen deficiency is a widespread threat to coastal and estuarine communities. While the negative impacts of hypoxia on benthic communities are well known, few studies have assessed in situ how benthic communities subjected to different degrees of hypoxic stress alter their contribution to ecosystem functioning. We studied changes in sediment ecosystem function (i.e. oxygen and nutrient fluxes across the sediment water-interface by artificially inducing hypoxia of different durations (0, 3, 7 and 48 days in a subtidal sandy habitat. Benthic chamber incubations were used for measuring responses in sediment oxygen and nutrient fluxes. Changes in benthic species richness, structure and traits were quantified, while stress-induced behavioral changes were documented by observing bivalve reburial rates. The initial change in faunal behavior was followed by non-linear degradation in benthic parameters (abundance, biomass, bioturbation potential, gradually impairing the structural and functional composition of the benthic community. In terms of ecosystem function, the increasing duration of hypoxia altered sediment oxygen consumption and enhanced sediment effluxes of NH(4(+ and dissolved Si. Although effluxes of PO(4(3- were not altered significantly, changes were observed in sediment PO(4(3- sorption capability. The duration of hypoxia (i.e. number of days of stress explained a minor part of the changes in ecosystem function. Instead, the benthic community and disturbance-driven changes within the benthos explained a larger proportion of the variability in sediment oxygen- and nutrient fluxes. Our results emphasize that the level of stress to the

  6. Factors Affecting the Distribution of Wild Rice (Zizania palustris) and the Surrounding Macrophyte Community.

    Science.gov (United States)

    Pillsbury, R. W.; McGuire, M.

    2005-05-01

    A recent decline in wild rice wetlands is cause for concern due to its importance as a food source, refuge for wildlife, and cultural significance. Sixty wetlands in Wisconsin and Minnesota (USA) were sampled, with approximately equal numbers displaying dense, moderate and sparse wild rice production. Chemical, physical, and watershed parameters were measured as well as macrophyte densities. Data were analyzed using multivariate statistics (CCA). Moderate levels of phosphorus appear beneficial to the overall success of wild rice, while free-floating macrophytes show an overwhelming positive response to higher levels of P. The distribution of macrophytes bordering wild rice beds is correlated to pH,with Potamogeton robbinsii and filamentous green algae responding most strongly to its increase. Healthy stands of wild rice exhibit a narrow circum-neutral range of pH (6.1-8.0)which is significantly different from the greater range exhibited by sparse wild rice wetlands (6.5-8.5). This pattern was paralleled when considering depth which suggests that deeper wetlands may be more susceptible to wild rice loss. Management of existing wild rice wetlands should focus monitoring on pH, depth, phosphorus concentrations and shore development. We are currently using this data base to locate the best reintroduction sites for wild rice.

  7. Macrophytes, epipelic biofilm, and invertebrates as biotic indicators of physical habitat degradation of lowland streams (Argentina).

    Science.gov (United States)

    Cortelezzi, Agustina; Sierra, María Victoria; Gómez, Nora; Marinelli, Claudia; Rodrigues Capítulo, Alberto

    2013-07-01

    Our objective was to assess the effect of the physical habitat degradation in three lowland streams of Argentina that are subject to different land uses. To address this matter, we looked into some physical habitat alterations, mainly the water quality and channel changes, the impact on macrophytes' community, and the structural and functional descriptors of the epipelic biofilm and invertebrate assemblages. As a consequence of physical and chemical perturbations, we differentiated sampling sites with different degradation levels. The low degraded sites were affected mainly for the suburban land use, the moderately degraded sites for the rural land use, and the highly degraded sites for the urban land use. The data shows that the biotic descriptors that best reflected the environmental degradation were vegetation cover and macrophytes richness, the dominance of tolerant species (epipelic biofilm and invertebrates), algal biomass, O2 consumption by the epipelic biofilm, and invertebrates' richness and diversity. Furthermore, the results obtained highlight the importance of the macrophytes in the lowland streams, where there is a poor diversification of abiotic substrates and where the macrophytes not only provide shelter but also a food source for invertebrates and other trophic levels such as fish. We also noted that both in benthic communities, invertebrates and epipelic biofilm supplied different information: the habitat's physical structure provided by the macrophytes influenced mainly the invertebrate descriptors; meanwhile, the water quality mainly influenced most of the epipelic biofilm descriptors.

  8. Influence of benthic macrofauna community shifts on ecosystem functioning in shallow estuaries

    Directory of Open Access Journals (Sweden)

    Erik eKristensen

    2014-09-01

    Full Text Available We identify how ecosystem functioning in shallow estuaries is affected by shifts in benthic fauna communities. We use the shallow estuary, Odense Fjord, Denmark, as a case study to test our hypotheses that (1 shifts in benthic fauna composition and species functional traits affect biogeochemical cycling with cascading effects on ecological functioning, which may (2 modulate pelagic primary productivity with feedbacks to the benthic system. Odense Fjord is suitable because it experienced dramatic shifts in benthic fauna community structure from 1998 to 2008. We focused on infaunal species with emphasis on three dominating burrow-dwelling polychaetes: the native Nereis (Hediste diversicolor and Arenicola marina, and the invasive Marenzelleria viridis. The impact of functional traits in the form of particle reworking and ventilation on biogeochemical cycles, i.e. sediment metabolism and nutrient dynamics, was determined from literature data. Historical records of summer nutrient levels in the water column of the inner Odense Fjord show elevated concentrations of NH4+ and NO3- (DIN during the years 2004-2006, exactly when the N. diversicolor population declined and A. marina and M. viridis populations expanded dramatically. In support of our first hypothesis, we show that excess NH4+ delivery from the benthic system during the A. marina and M. viridis expansion period enriched the overlying water in DIN and stimulated phytoplankton concentration. The altered benthic-pelagic coupling and stimulated pelagic production may, in support of our second hypothesis, have feedback to the benthic system by changing the deposition of organic material. We therefore advice to identify the exact functional traits of the species involved in a community shift before studying its impact on ecosystem functioning. We also suggest studying benthic community shifts in shallow environments to obtain knowledge about the drivers and controls before exploring deep

  9. Benthic macroinvertebrate community structure and distribution in the Ayeyarwady continental shelf, Andaman Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari Z.A.; Furtado, R.; Badesab, S.; Mehta, P.; Thwin, S.

    water, Myanmar] Introduction Abundance of benthic fauna is one of the biological indices that support the food chain hypothesis of overall productivity in marine ecosystem1. Changes in benthic community may occur on different spatial scale..., biomass and species diversity of macrobenthos was more in the inshore waters than in the offshore areas of Malaysia and Gulf of Thailand. As indicated earlier, a significant amount of the variation in faunal abundances, not unexpectedly, is a function...

  10. Limited differences in fish and benthic communities and possible cascading effects inside and outside a protected marine area in Sagres (SW Portugal).

    Science.gov (United States)

    Gil Fernández, C; Paulo, D; Serrão, E A; Engelen, A H

    2016-03-01

    Marine protected areas (MPAs) are a relatively recent fisheries management and conservation tool for conservation of marine ecosystems and serve as experimental grounds to assess trophic cascade effects in areas were fishing is restricted to some extent. A series of descriptive field studies were performed to assess fish and benthic communities between two areas within a newly established MPA in SW Portugal. We characterized benthic macroalgal composition and determined the size, density and biomass of the main benthic predatory and herbivorous fish species as well as the main benthic herbivorous invertebrates to assess indications of top-down control on the phytobenthic assemblages. Fish species were identical inside and outside the MPA, in both cases Sarpa salpa was the most abundant fish herbivore and Diplodus spp. accounted for the great majority of the benthic predators. However, size and biomass of D. spp. were higher inside than outside the MPA. The main herbivorous invertebrate was the sea urchin Paracentrotus lividus, which was smaller and predominantly showing a crevice-dwelling behaviour in the MPA. In addition, P. lividus size frequency distribution showed a unimodal pattern outside and a bimodal pattern inside the MPA. We found significant differences in the algal assemblages between inside and outside the MPA, with higher abundance of turf and foliose algae inside, and articulated calcareous and corticated macrophytes outside the MPA, but no differences in the invasive Asparagopsis spp. The obtained results show differences in predatory fish and benthic community structure, but not in species richness, inside and outside the MPA. We hypothesize these differences lead to variation in species interactions: directly through predation and indirectly via affecting sea urchins behavioural patterns, predators might drive changes in macroalgal assemblages via trophic cascade in the study area. However due to non-biological differences between the two areas it

  11. Effects of fishing disturbance on benthic communities and secondary production within an intensively fished area

    NARCIS (Netherlands)

    Reiss, H.; Greenstreet, S.P.R.; Sieben, K.; Ehrich, S.; Piet, G.J.; Quirijns, F.; Wolff, W.J.; Kroncke, I.

    2009-01-01

    Demersal fishing alters seabed habitats and affects the structure and functioning of benthic invertebrate communities. At a critical level of disturbance, such communities may approach an equilibrium disturbed state in which a further increase in disturbance has little additional impact. Such

  12. Benthic macroinvertebrate community and chlorophyll a (chl-a ...

    African Journals Online (AJOL)

    ADOWIE PERE

    consequences of climate change are some of the most visible warning signals ... present; spatial and temporal mobility of species is quite restricted, hence .... taxonomic groups using suitable identification manuals ... describe the structure and composition of benthic .... pollution respond to polluted environment by increase.

  13. Do freshwater macrophytes influence the community structure of ammonia-oxidizing and denitrifying bacteria in the rhizospere?

    DEFF Research Database (Denmark)

    Herrmann, Martina; Schramm, Andreas

    2006-01-01

    to unvegetated sediment, especially with respect to the availability of oxygen, organic carbon, and inorganic nitrogen. We hypothesize that macrophyte species create specific niches for ammonia oxidizing and nitrate-reducing bacteria in their rhizosphere, leading to plant-dependant differences in abundance...... dortmanna have been shown to release oxygen from their roots and to stimulate nitrification and coupled nitrification-denitrification in the rhizosphere. Together with the excretion of root exudates, this effect leads to strongly modified microenvironments at the root surface and in the rhizosphere compared......-denitrification using the 15N isotope pairing technique. Ammonia-oxidizing and nitrate-reducing populations are analyzed based on the ammonia monooxygenase gene (amoA) and the nitrate reductase gene (narG) as functional markers. Preliminary data indicate that there in fact exist differences in the community composition...

  14. Drivers of abundance and community composition of benthic macroinvertebrates in Ottawa River sediment near Chalk River Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Bond, M.J.; Rowan, D.; Silke, R.; Carr, J., E-mail: bondm@aecl.ca [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2013-12-15

    The Ottawa River has received effluent from Chalk River Laboratories (CRL) for more than 60 years. Some radionuclides and contaminants released in effluents are bound rapidly to particles and deposited in bottom sediments where they may be biologically available to benthic invertebrates and other aquatic biota. As part of a larger ecological assessment, we assess the potential impact of contaminated sediments in the vicinity of CRL on local benthic community structure. Using bivariate and multivariate approaches, we demonstrate that CRL operations have had little impact on the local benthic community. Despite elevated anthropogenic radionuclide activity concentrations in sediment near CRL's process outfall, the benthic community is no less abundant or diverse than what is observed upstream at background levels. The Ottawa River benthic invertebrate community is structured predominantly by natural physical and biological conditions in the sediment, specifically sediment water content and organic content. These natural habitat conditions have a stronger influence on macroinvertebrate communities than sediment contamination. (author)

  15. A new cell primo-culture method for freshwater benthic diatom communities

    OpenAIRE

    Debenest, Timothée; Silvestre, Jérôme; Coste, Michel; Delmas, François; Pinelli, Eric

    2009-01-01

    A new cell primo-culture method was developed for the benthic diatom community isolated from biofilm sampled in rivers. The approach comprised three steps: (1) scraping biofilm from river pebbles, (2) diatom isolation from biofilm, and (3) diatom community culture. With a view to designing a method able to stimulate the growth of diatoms, to limit the development of other microorganisms, and to maintain in culture a community similar to the original natural one, different factors were test...

  16. Effects of temperature and irradiance on a benthic microalgal community: A combined two-dimensional oxygen and fluorescence imaging approach

    DEFF Research Database (Denmark)

    Hancke, Kasper; Sorrell, Brian Keith; Lund-Hansen, Lars Chresten

    2014-01-01

    The effects of temperature and light on both oxygen (O2) production and gross photosynthesis were resolved in a benthic microalgae community by combining two-dimensional (2D) imaging of O2 and variable chlorophyll a (Chl a) fluorescence. Images revealed a photosynthetically active community...... microbial community, at different temperatures. The present imaging approach demonstrates a great potential to study consequences of environmental effects on photosynthetic activity and O2 turnover in complex phototrophic benthic communities....

  17. Influence of land-use patterns on benthic diatom communities and ...

    African Journals Online (AJOL)

    The objective of this study was to determine the effects of land-use patterns on both diatom community composition and water quality in tropical streams during the dry season. Benthic diatom collections and water quality sampling were done 4 times at 10 sites. A suite of environmental variables that varied with human ...

  18. Benthic Algae Communities in the Rivers of Different Water Quality in Lithuania

    Directory of Open Access Journals (Sweden)

    Irma Vitonytė

    2011-04-01

    Full Text Available Investigation into benthic algae communities was carried out in the Lithuanian rivers of different water quality during the period 2004–2006. The structure of benthic algae communities in the rivers of different water quality slightly differs. The community of Cladophora glomerata–Vaucheria sessilis–Fontinalis antipyretica mainly dominated in the rivers. Algae communities reiterate in unpolluted rivers (II class, according to biogenes such as Akmena, Babrungas, Bražuolė and Siesartis where Cladophora glomerata–Fontinalis antipyretica, Amblystegium riparium–Cladophora glomerata, and Fontinalis antipyretica–Cladophora glomerata communities predominate. In slightly and moderately polluted rivers, algae communities are unreiteratable. Differences in river water quality could be better determined by frequently appearing algae species in algae communities: in unpolluted rivers – Hildenbrandia rivularis, Audouinella chalybea and A. Hermanii, in slightly polluted – Vaucheria sessilis and Fontinalis antipyretica, and in moderately polluted – Stigeoclonium nanum, S. tenue, Aulacoseira islandica and Melosira varians.The variety of the structure of benthic algae communities could be determined by abiotic environmental factors such as the heterogenity of substratum, stream velocity and depth, the intensity of light and biogenes concentration.Article in Lithuanian

  19. Relationship between bifenthrin sediment toxic units and benthic community metrics in urban California streams.

    Science.gov (United States)

    Hall, Lenwood W; Anderson, Ronald D

    2013-08-01

    The objective of this study was to use ecologically relevant field measurements for determining the relationship between bifenthrin sediment toxic units (TUs) (environmental concentrations/Hyalella acute LC50 value) and 15 benthic metrics in four urban California streams sampled from 2006 to 2011. Data from the following four California streams were used in the analysis: Kirker Creek (2006, 2007), Pleasant Grove Creek (2006, 2007, and 2008), Arcade Creek (2009, 2010, and 2011), and Salinas streams (2009, 2010, and 2011). The results from univariate analysis of benthic metrics versus bifenthrin TU calculations for the four California streams with multiple-year datasets combined by stream showed that there were either nonsignificant relationships or lack of metric data for 93 % of cases. For 7 % of the data (4 cases) where significant relationships were reported between benthic metrics and bifenthrin TUs, these relationships were ecologically meaningful. Three of these significant direct relationships were an expression of tolerant benthic taxa (either % tolerant taxa or tolerance values, which are similar metrics), which would be expected to increase in a stressed environment. These direct significant tolerance relationships were reported for Kirker Creek, Pleasant Grove Creek, and Arcade Creek. The fourth significant relationship was an inverse relationship between taxa richness and bifenthrin TUs for the 3-year Pleasant Grove Creek dataset. In summary, only a small percent of the benthic metric × bifenthrin TU relationships were significant for the four California streams. Therefore, the general summary conclusion from this analysis is that there is no strong case for showing consistent meaningful relationships between various benthic metrics used to characterize the status of benthic communities and bifenthrin TUs for these four California streams.

  20. Assessing Environmental Impact on Aquatic Macrophyte Species ...

    African Journals Online (AJOL)

    Impact of environmental variables on distribution and composition of aquatic macrophyte community in a tropical river was assessed for one year (March 2009 to February 2010). Hypothesis tested was that the spatial variation in environmental variables on the river's longitudinal gradient affects macrophyte species ...

  1. Decline in the deepwater benthic communities abundance in the Onego Lake under multifactor influence

    Directory of Open Access Journals (Sweden)

    Kalinkina Nataliya Michailovna

    2016-06-01

    Full Text Available The dynamics of deepwater benthic communities state between 1988 and 2015 was analyzed. In the last decade the decline in the deepwater benthic communities development indicators is observed in Petrozavodskaya Bay and contiguous central area of the Lake Onego. The abundance of benthos decreased by 6-7 times, biomass dropped in 2-4 times. At the same time the changes in sedimentation processes of organic matter, nutrients, iron and manganese are observed in the water ecosystem. This has resulted in an increase in the concentrations of Fe and Mn in the sediment surface layers; in pore waters up to 13 mg Fe/l and 7 mg Mn/l. The sharp increase in the content of iron and manganese in the bottom sediment can be considered as a possible factor of benthos oppression. Another reason of the benthos decrease is the reduction of anthropogenic load. Now Petrozavodskaya bay receives 3 times less light organic substances than 10 years ago. The third possible reason for the reduction of benthic communities is invasion of baikalian amphipods Gmelinoides fasciatus, resulting in the redistribution of organic matter flow from the littoral zone to the pelagic zone and depletion of deepwater benthic food resources.

  2. Food web flows through a sub-arctic deep-sea benthic community

    Science.gov (United States)

    Gontikaki, E.; van Oevelen, D.; Soetaert, K.; Witte, U.

    2011-11-01

    The benthic food web of the deep Faroe-Shetland Channel (FSC) was modelled by using the linear inverse modelling methodology. The reconstruction of carbon pathways by inverse analysis was based on benthic oxygen uptake rates, biomass data and transfer of labile carbon through the food web as revealed by a pulse-chase experiment. Carbon deposition was estimated at 2.2 mmol C m -2 d -1. Approximately 69% of the deposited carbon was respired by the benthic community with bacteria being responsible for 70% of the total respiration. The major fraction of the labile detritus flux was recycled within the microbial loop leaving merely 2% of the deposited labile phytodetritus available for metazoan consumption. Bacteria assimilated carbon at high efficiency (0.55) but only 24% of bacterial production was grazed by metazoans; the remaining returned to the dissolved organic matter pool due to viral lysis. Refractory detritus was the basal food resource for nematodes covering ∼99% of their carbon requirements. On the contrary, macrofauna seemed to obtain the major part of their metabolic needs from bacteria (49% of macrofaunal consumption). Labile detritus transfer was well-constrained, based on the data from the pulse-chase experiment, but appeared to be of limited importance to the diet of the examined benthic organisms (preferred prey, in this case, was other macrofaunal animals rather than nematodes. Bacteria and detritus contributed 53% and 12% to the total carbon ingestion of carnivorous polychaetes suggesting a high degree of omnivory among higher consumers in the FSC benthic food web. Overall, this study provided a unique insight into the functioning of a deep-sea benthic community and demonstrated how conventional data can be exploited further when combined with state-of-the-art modelling approaches.

  3. Metabarcoding monitoring analysis: the pros and cons of using co-extracted environmental DNA and RNA data to assess offshore oil production impacts on benthic communities

    KAUST Repository

    Laroche, Olivier; Wood, Susanna A.; Tremblay, Louis A.; Lear, Gavin; Ellis, Joanne; Pochon, Xavier

    2017-01-01

    benthic communities collected at increasing distances along a transect from an oil production platform (Taranaki, New Zealand). Macro-infauna (visual classification of benthic invertebrates) and physico-chemical data were analyzed in parallel. We tested

  4. Differences in composition of shallow-water marine benthic communities associated with two ophiolitic rock substrata

    Science.gov (United States)

    Bavestrello, Giorgio; Bo, Marzia; Betti, Federico; Canessa, Martina; Gaggero, Laura; Rindi, Fabio; Cattaneo-Vietti, Riccardo

    2018-01-01

    On marine rocky shores, several physical, chemical and biological processes operate to maintain the benthic assemblages' heterogeneity, but among the abiotic factors, the composition and texture of the rocky substrata have been only sporadically considered. However, biomineralogical studies have demonstrated an unsuspected ability of the benthic organisms to interact at different levels with rocky substrata. Therefore, the mineralogy of the substratum can affect the structure of benthic communities. To evaluate this hypothesis, the macrobenthic assemblages developed on two different ophiolitic rocks (serpentinites and metagabbros) in contact at a restricted stretch of the western Ligurian Riviera (western Mediterranean Sea), with identical environmental and climatic conditions, were analysed. Samplings were carried out at four bathymetric levels (+1m, 0m, -1m, and -3m respect to the mean sea level) and the analysis of the data evidenced differences in terms of species distribution and percent coverage. Algal communities growing on metagabbros were poorer in species richness and showed a much simpler structure when compared to the assemblages occurring on the serpentinites. The most widely distributed animal organism, the barnacle Chthamalus stellatus, was dominant on serpentinites, and virtually absent on metagabbros. Our results suggest a complex pattern of interactions between lithology and benthic organisms operating through processes of inhibition/facilitation related to the mineral properties of the substratum.

  5. Field experiments on responses of a freshwater, benthic macroinvertebrate community to vertebrate predators

    International Nuclear Information System (INIS)

    Thorp, J.H.; Bergey, E.A.

    1981-01-01

    The seasonal importance of vertebrate predators in potentially regulating the abundance and diversity of the benthic macroinvertebrates in the littoral zone of a soft-bottom reservoir that receives thermal effluent from a nuclear production reactor was examined. Thirty-six predator (fish and turtle) exclusion cages (4 m 2 ) were placed in shallow water at six locations along a thermal gradient in Par Pond, a 1100-ha cooling reservoir on the Savannah River Plant near Aiken, South Carolina, USA. An additional 36 control plots (4 m 2 ) were also set up. Cages were in place during three, 3-mo test periods beginning in September 1977. Estimates of benthic density, taxon richness, and distribution within functional groups (defined by feeding mechanism) were calculated for each test period. Effects of temperature on predator-prey relationships were also determined. Experimental results of this study suggest that vertebrate predation was not the fundamental parameter organizing the benthic macroinvertebrate community in the littoral zone of this reservoir. Neither taxon richness nor density of total macroinvertebrates was conclusively related to predator treatment. Relationships between predator treatment and community response (changes in density and taxon richness) were generally unaffected by either plot locality, temperature fluctuations from thermal effluent, or seasonal changes. When data from caged and control plots were pooled, however, both location and water temperature individually had direct impacts on the benthic community. From these results and other field studies it is hypothesized that individual species of keystone benthic predators do not occur in the littoral zone of freshwater lentic environments with soft bottoms

  6. Baseline characterization of benthic and coral communities of the Flower Garden Banks (2010 - 2012) (NODC Accession 0124257)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This study utilized ROV photograph transects to quantify benthic habitat and coral communities among the five habitat types (algal nodule, coralline algal reefs,...

  7. Baseline assessment of benthic communities of the Flower Garden Banks (2010 - 2013) using technical diving operations: 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The proposed work develop baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys will employ...

  8. Baseline assessment of benthic communities of the Flower Garden Banks (2010 - 2013) using technical diving operations: 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The work developed baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys employed diving,...

  9. Benthic community structure on coral reefs exposed to intensive recreational snorkeling.

    Directory of Open Access Journals (Sweden)

    Bobbie Renfro

    Full Text Available Chronic anthropogenic disturbances on coral reefs in the form of overfishing and pollution can shift benthic community composition away from stony corals and toward macroalgae. The use of reefs for recreational snorkeling and diving potentially can lead to similar ecological impacts if not well-managed, but impacts of snorkeling on benthic organisms are not well understood. We quantified variation in benthic community structure along a gradient of snorkeling frequency in an intensively-visited portion of the Mesoamerican Barrier Reef. We determined rates of snorkeling in 6 water sections and rates of beach visitation in 4 adjacent land sections at Akumal Bay, Mexico. For each in-water section at 1-3 m depth, we also assessed the percent cover of benthic organisms including taxa of stony corals and macroalgae. Rates of recreational snorkeling varied from low in the southwestern to very high (>1000 snorkelers d-1 in the northeastern sections of the bay. Stony coral cover decreased and macroalgal cover increased significantly with levels of snorkeling, while trends varied among taxa for other organisms such as gorgonians, fire corals, and sea urchins. We conclude that benthic organisms appear to exhibit taxon-specific variation with levels of recreational snorkeling. To prevent further degradation, we recommend limitation of snorkeler visitation rates, coupled with visitor education and in-water guides to reduce reef-damaging behaviors by snorkelers in high-use areas. These types of management activities, integrated with reef monitoring and subsequent readjustment of management, have the potential to reverse the damage potentially inflicted on coral reefs by the expansion of reef-based recreational snorkeling.

  10. Community and Ecosystem-Level Impacts of an Emergent Macrophyte on the Ventura River, California.

    Science.gov (United States)

    Simpson, J.; Leydecker, A.; Melack, J.

    2005-05-01

    Ludwigia hexapetala is a pervasive, emergent vascular plant on the lower Ventura River. Presence of this plant appears to facilitate growth of shade-tolerant diatoms, while indirectly inhibiting filamentous green macroalgae. Four sites on the river were monitored during 2003; three downstream of a wastewater treatment plant, where Ludwigia is present, and one upstream site where it is absent. Filamentous algae occurred at all four sites, but declined rapidly at the below-treatment plant sites as growth and cover of vascular plants increased. By late summer, percent cover at these sites was dominated by Ludwigia, while the upstream site was consistently dominated by green macroalgae. Submerged plant parts provided substrate for diatom colonization, roughly doubling benthic diatom biomass (measured as chlorophyll a) at the downstream sites. Presence of the Ludwigia population also had strong ecosystem-level effects. The wastewater effluent produced typical stream water nitrate concentrations of 100-200 uM. Nitrate uptake rates downstream of the treatment plant inputs averaged 5 kg N/km/day, and direct uptake by Ludwigia could account for 20-40% of this nitrate drawdown. Further nitrate removal from the water column may be indirectly facilitated by the presence of Ludwigia through facilitation of diatom population growth.

  11. Significance of microcystin production by benthic communities in water treatment systems of arid zones.

    Science.gov (United States)

    Hurtado, I; Aboal, M; Zafra, E; Campillo, D

    2008-02-01

    The study of the dynamics of phytobenthic and phytoplankton communities was undertaken, during a year, in the regulation reservoir associated with a water treatment plant (WTP), which provides the city of Murcia (Spain) with drinking water. Water samples were collected in different stages of the treatment. In the reservoir, the presence of dissolved and intracellular microcystins is constant, both in benthos and in plankton. The collected samples show a positive correlation between the dissolved microcystins and the benthic ones in the reservoir itself, as well as in an upstream reservoir (Ojós Reservoir). The treatment process (ozone+clarification+ozone+activated carbon) is very effective in the removal of toxins, and the drinking water produced is totally free of microcystins. The incorporation of the benthic communities in the routine check for the presence of microcystins is recommended, since it is not compulsory according to the current legislation.

  12. Colonisation and community structure of benthic diatoms on artificial ...

    African Journals Online (AJOL)

    This was undertaken using tiles as artificial substrates so that we could study how the communities developed after the flood disturbance. The diatom community structure was assessed over a 28-day period following a flood event in October 2012. The Mann Whitney test indicated that there was a statistically significant ...

  13. Successional trends of the benthic macroinvertebrate community in a new southeastern cooling reservoir

    International Nuclear Information System (INIS)

    Griffin, M.A.; Herring, M.K.

    1990-01-01

    Lakes created by river impoundments provide new lentic habitats for benthic macroinvertebrates. As new lakes age, benthic macroinvertebrate succession proceeds as first colonizers are replaced and stable populations eventually become established. L Lake, a 400 ha reservoir, was constructed in 1985 on the Department of Energy's Savannah River Site in South Carolina to receive heated effluent from a nuclear production reactor. Benthic macroinvertebrates were collected in L Lake with a ponar grab sampler at 2 and 4 meters at 10 locations in 5 lake regions. Monthly collections were made from 1986 through 1989. Annual average densities of benthic macroinvertebrates increased substantially during the study (ranging from 3955.5--4471.6 organisms/m 2 in 1986 to 8948.1--11,694.1 organisms/m 2 in 1988). Annual mean biomass also increased (ranging from 0.749--0.907g AFDM/m 2 in 1986 to 2074--11,322 g AFDM/m 2 in 1988). Mean annual taxa richness ranged from 9.3--12.2 per ponar in 1986 to 11.8--15.3 per ponar in 1988. Some early colonizers (Chironomidae: Chironomini) dominated throughout the study (ranging from 60.3--79.1% of all organisms). Other chironomids (Tanytarsini and Tanypodinae) declined while slower colonizers (oligochaetes and nematodes) generally increased from 1986 through 1988. The increases in macroinvertebrate density, biomass and changes in community composition observed are typical of early reservoir succession. 14 refs., 12 figs., 1 tab

  14. Do Changes in Current Flow as a Result of Arrays of Tidal Turbines Have an Effect on Benthic Communities?

    Science.gov (United States)

    Kregting, Louise; Elsaesser, Bjoern; Kennedy, Robert; Smyth, David; O'Carroll, Jack; Savidge, Graham

    2016-01-01

    Arrays of tidal energy converters have the potential to provide clean renewable energy for future generations. Benthic communities may, however, be affected by changes in current speeds resulting from arrays of tidal converters located in areas characterised by strong currents. Current speed, together with bottom type and depth, strongly influence benthic community distributions; however the interaction of these factors in controlling benthic dynamics in high energy environments is poorly understood. The Strangford Lough Narrows, the location of SeaGen, the world's first single full-scale, grid-compliant tidal energy extractor, is characterised by spatially heterogenous high current flows. A hydrodynamic model was used to select a range of benthic community study sites that had median flow velocities between 1.5-2.4 m/s in a depth range of 25-30 m. 25 sites were sampled for macrobenthic community structure using drop down video survey to test the sensitivity of the distribution of benthic communities to changes in the flow field. A diverse range of species were recorded which were consistent with those for high current flow environments and corresponding to very tide-swept faunal communities in the EUNIS classification. However, over the velocity range investigated, no changes in benthic communities were observed. This suggested that the high physical disturbance associated with the high current flows in the Strangford Narrows reflected the opportunistic nature of the benthic species present with individuals being continuously and randomly affected by turbulent forces and physical damage. It is concluded that during operation, the removal of energy by marine tidal energy arrays in the far-field is unlikely to have a significant effect on benthic communities in high flow environments. The results are of major significance to developers and regulators in the tidal energy industry when considering the environmental impacts for site licences.

  15. Community structure of benthic macroinvertebrates inhabiting a highly stratified Mediterranean estuary

    Directory of Open Access Journals (Sweden)

    Alfonso Nebra

    2011-04-01

    Full Text Available The community composition and spatial distribution of benthic macroinvertebrates were studied along the Ebro estuary, a highly stratified estuary located in the NE Iberian Peninsula. During the last decade the oligotrophication process occurring in the lower Ebro River and its estuary has allowed a complex benthic macroinvertebrate community to become established; these results contrast with the poor community found there in the early nineties. A total of 214 taxa were identified, and polychaetes dominated the community both in abundance and species richness. The results showed spatial differences in the structure and composition of macroinvertebrates, which suggests that there are two distinct communities along the estuary. Each community was found in a specific stretch (upper and lower estuary in function of the presence of the salt wedge. The macrobenthos of the upper estuary was dominated by freshwater taxa, but some euryhaline species were also found. The lower estuary showed a marine community typical of shallow Mediterranean environments. The transition between these two communities fits an ecotone model. The highest abundances, richness and diversities were recorded at the lower estuarine stations, especially those closer to the river mouth, whereas the lowest values corresponded to the stations adjacent to the tip of the salt wedge.

  16. Regime shift from phytoplankton to macrophyte dominance in a large river: Top-down versus bottom-up effects

    Energy Technology Data Exchange (ETDEWEB)

    Ibanez, Carles, E-mail: carles.ibanez@irta.cat [IRTA Aquatic Ecosystems, Carretera Poble Nou, Km 5.5, 43540 St. Carles de la Rapita, Catalonia (Spain); Alcaraz, Carles; Caiola, Nuno; Rovira, Albert; Trobajo, Rosa [IRTA Aquatic Ecosystems, Carretera Poble Nou, Km 5.5, 43540 St. Carles de la Rapita, Catalonia (Spain); Alonso, Miguel [United Research Services S.L., Urgell 143, 08036 Barcelona, Catalonia (Spain); Duran, Concha [Confederacion Hidrografica del Ebro, Sagasta 24-26, 50071 Zaragoza, Aragon (Spain); Jimenez, Pere J. [Grup Natura Freixe, Major 56, 43750 Flix, Catalonia (Spain); Munne, Antoni [Agencia Catalana de l' Aigua, Provenca 204-208, 08036 Barcelona, Catalonia (Spain); Prat, Narcis [Departament d' Ecologia, Universitat de Barcelona, Diagonal 645, 08028 Barcelona Catalonia (Spain)

    2012-02-01

    The lower Ebro River (Catalonia, Spain) has recently undergone a regime shift from a phytoplankton-dominated to a macrophyte-dominated system. This shift is well known in shallow lakes but apparently it has never been documented in rivers. Two initial hypotheses to explain the collapse of the phytoplankton were considered: a) the diminution of nutrients (bottom-up); b) the filtering effect due to the colonization of the zebra mussel (top-down). Data on water quality, hydrology and biological communities (phytoplankton, macrophytes and zebra mussel) was obtained both from existing data sets and new surveys. Results clearly indicate that the decrease in phosphorus is the main cause of a dramatic decrease in chlorophyll and large increase in water transparency, triggering the subsequent colonization of macrophytes in the river bed. A Generalized Linear Model analysis showed that the decrease in dissolved phosphorus had a relative importance 14 times higher than the increase in zebra mussel density to explain the variation of total chlorophyll. We suggest that the described changes in the lower Ebro River can be considered a novel ecosystem shift. This shift is triggering remarkable changes in the biological communities beyond the decrease of phytoplankton and the proliferation of macrophytes, such as massive colonization of Simulidae (black fly) and other changes in the benthic invertebrate communities that are currently investigated. - Highlights: Black-Right-Pointing-Pointer We show a regime shift in a large river from phytoplankton to macrophyte dominance. Black-Right-Pointing-Pointer Two main hypotheses are considered: nutrient decrease and zebra mussel grazing. Black-Right-Pointing-Pointer Phosphorus depletion is found to be the main cause of the phytoplankton decline. Black-Right-Pointing-Pointer We conclude that oligotrophication triggered the colonization of macrophytes. Black-Right-Pointing-Pointer This new regime shift in a river is similar to that described

  17. Regime shift from phytoplankton to macrophyte dominance in a large river: Top-down versus bottom-up effects

    International Nuclear Information System (INIS)

    Ibáñez, Carles; Alcaraz, Carles; Caiola, Nuno; Rovira, Albert; Trobajo, Rosa; Alonso, Miguel; Duran, Concha; Jiménez, Pere J.; Munné, Antoni; Prat, Narcís

    2012-01-01

    The lower Ebro River (Catalonia, Spain) has recently undergone a regime shift from a phytoplankton-dominated to a macrophyte-dominated system. This shift is well known in shallow lakes but apparently it has never been documented in rivers. Two initial hypotheses to explain the collapse of the phytoplankton were considered: a) the diminution of nutrients (bottom-up); b) the filtering effect due to the colonization of the zebra mussel (top-down). Data on water quality, hydrology and biological communities (phytoplankton, macrophytes and zebra mussel) was obtained both from existing data sets and new surveys. Results clearly indicate that the decrease in phosphorus is the main cause of a dramatic decrease in chlorophyll and large increase in water transparency, triggering the subsequent colonization of macrophytes in the river bed. A Generalized Linear Model analysis showed that the decrease in dissolved phosphorus had a relative importance 14 times higher than the increase in zebra mussel density to explain the variation of total chlorophyll. We suggest that the described changes in the lower Ebro River can be considered a novel ecosystem shift. This shift is triggering remarkable changes in the biological communities beyond the decrease of phytoplankton and the proliferation of macrophytes, such as massive colonization of Simulidae (black fly) and other changes in the benthic invertebrate communities that are currently investigated. - Highlights: ► We show a regime shift in a large river from phytoplankton to macrophyte dominance. ► Two main hypotheses are considered: nutrient decrease and zebra mussel grazing. ► Phosphorus depletion is found to be the main cause of the phytoplankton decline. ► We conclude that oligotrophication triggered the colonization of macrophytes. ► This new regime shift in a river is similar to that described in shallow lakes.

  18. Evaluation of potential relationships between benthic community structure and toxic metals in Laizhou Bay.

    Science.gov (United States)

    Wu, Bin; Song, Jinming; Li, Xuegang

    2014-10-15

    The objective of the present study was to examine the relationships between benthic community structure and toxic metals using bivariate/multivariate techniques at 17 sediment locations in Laizhou Bay, North China. Sediment chemical data were evaluated against geochemical background values and sediment quality guidelines, which identified Cu and As as contaminants of concern with a moderate potential for adverse effects. Benthic community data were subjected to non-metric multidimensional scaling, which generated four groups of stations. Spearman rank correlation was then employed to explore the relationships between the major axes of heavy metals and benthic community structure. However, weak and insignificant correlations were found between these axes, indicating that contaminants of concern may not be the primary explanatory factors. Polychaeta were abundant in southern Laizhou Bay, serving as a warning regarding the health status of the ecosystem. Integrated sediment quality assessment showed sediments from northern central locations were impaired, displaying less diverse benthos and higher metal contamination. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Major methodological constraints to the assessment of environmental status based on the condition of benthic communities

    Science.gov (United States)

    Medeiros, João Paulo; Pinto, Vanessa; Sá, Erica; Silva, Gilda; Azeda, Carla; Pereira, Tadeu; Quintella, Bernardo; Raposo de Almeida, Pedro; Lino Costa, José; José Costa, Maria; Chainho, Paula

    2014-05-01

    The Marine Strategy Framework Directive (MSFD) was published in 2008 and requires Member States to take the necessary measures to achieve or maintain good environmental status in aquatic ecosystems by the year of 2020. The MSFD indicates 11 qualitative descriptors for environmental status assessment, including seafloor integrity, using the condition of the benthic community as an assessment indicator. Member States will have to define monitoring programs for each of the MSFD descriptors based on those indicators in order to understand which areas are in a Good Environmental Status and what measures need to be implemented to improve the status of areas that fail to achieve that major objective. Coastal and offshore marine waters are not frequently monitored in Portugal and assessment tools have only been developed very recently with the implementation of the Water Framework Directive (WFD). The lack of historical data and knowledge on the constraints of benthic indicators in coastal areas requires the development of specific studies addressing this issue. The major objective of the current study was to develop and test and experimental design to assess impacts of offshore projects. The experimental design consisted on the seasonal and interannual assessment of benthic invertebrate communities in the area of future implementation of the structures (impact) and two potential control areas 2 km from the impact area. Seasonal benthic samples were collected at nine random locations within the impact and control areas in two consecutive years. Metrics included in the Portuguese benthic assessment tool (P-BAT) were calculated since this multimetric tool was proposed for the assessment of the ecological status in Portuguese coastal areas under the WFD. Results indicated a high taxonomic richness in this coastal area and no significant differences were found between impact and control areas, indicating the feasibility of establishing adequate control areas in marine

  20. Environmental and Spatial Influences on Biogeography and Community Structure of Benthic Diatoms

    Science.gov (United States)

    Plante, C.; Hill-Spanik, K.; Lowry, J.

    2016-02-01

    Several theoretical and practical reasons suggest that benthic microalgae could be useful bioindicators. For instance, an ideal indicator species or community would be associated with a given habitat due to local physical conditions or biotic interactions (i.e., `environmental filtering'), not due to dispersal limitation. Due to their small size, immense abundances, and reliance on passive dispersal, the popular notion about micro-organisms is that `Everything is everywhere, but, the environment selects' (Baas-Becking 1934). Although much recent research concerning planktonic bacteria and dispersal limitation has been conducted, very little in this regard is known about microeukaryotes, especially benthic microbes. The purpose of our study was to identify and compare spatial and environmental influences on benthic diatom community structure and biogeography. In summer 2015, sediment was sampled at various spatial scales from four barrier island beaches in South Carolina, USA, and high-throughput (Ion Torrent) DNA sequencing was used to characterize diatom assemblages. ANOSIM and principal coordinates analysis revealed that communities were statistically distinct on the four islands. Community dissimilarity was compared to both spatial distance and environmental differences to determine potential influences of these variables on community structure. We found that geographic distance had the strongest correlation with community similarity, with and without one anomalous location, while differences in temperature (air, water, and sediment), nutrients, organic matter, and turbidity also had significant but weaker relationships with community structure. Surprisingly, air temperature, which changes on very short time scales, appeared to be the environmental factor most strongly related to diatom species composition, potentially implicating some unmeasured variable (e.g., cloud cover). However, we also found that temperature and geographic distance were strongly

  1. A knowledge platform to inform on the effects of trawling on benthic communities

    Science.gov (United States)

    Muntadas, Alba; Lample, Michel; Demestre, Montserrat; Ballé-Béganton, Johanna; de Juan, Silvia; Maynou, Francesc; Bailly, Denis

    2018-02-01

    For a successful implementation of an Ecosystem Approach to Fisheries (EAF) management, it is necessary that all stakeholders involved in fisheries management are aware of the implications of fishing impacts on ecosystems and agree with the adopted measures to mitigate these impacts. In this context, there is a need for tools to share knowledge on the ecosystem effects of fisheries among these stakeholders. When managing bottom trawl fisheries under an EAF framework, one of the main concerns is the direct and indirect consequences of trawling impacts on benthic ecosystems. We developed a platform using the ExtendSim® software with a user-friendly interface that combines a simulation model based on existing knowledge, data collection and representation of predicted trawling impacts on the seabed. The platform aims to be a deliberation support tool for fisheries' stakeholders and, simultaneously, raise public awareness of the need for good benthic community knowledge to appropriately inform EAF management plans. The simulation procedure assumes that trawling affects benthic communities with an intensity that depends on the level of fishing effort exerted on benthic communities and on the habitat characteristics (i.e. sediment grain size). Data to build the simulation comes from epifaunal samples from 18 study sites located in Mediterranean continental shelves subjected to different levels of fishing effort. In this work, we present the simulation outputs of a 50% fishing effort increase (and decrease) in four of the study sites which cover different habitats and different levels of fishing effort. We discuss the platform strengths and weaknesses and potential future developments.

  2. Habitat and scale shape the demographic fate of the keystone sea urchin Paracentrotus lividus in Mediterranean macrophyte communities.

    Directory of Open Access Journals (Sweden)

    Patricia Prado

    Full Text Available Demographic processes exert different degrees of control as individuals grow, and in species that span several habitats and spatial scales, this can influence our ability to predict their population at a particular life-history stage given the previous life stage. In particular, when keystone species are involved, this relative coupling between demographic stages can have significant implications for the functioning of ecosystems. We examined benthic and pelagic abundances of the sea urchin Paracentrotus lividus in order to: 1 understand the main life-history bottlenecks by observing the degree of coupling between demographic stages; and 2 explore the processes driving these linkages. P. lividus is the dominant invertebrate herbivore in the Mediterranean Sea, and has been repeatedly observed to overgraze shallow beds of the seagrass Posidonia oceanica and rocky macroalgal communities. We used a hierarchical sampling design at different spatial scales (100 s, 10 s and <1 km and habitats (seagrass and rocky macroalgae to describe the spatial patterns in the abundance of different demographic stages (larvae, settlers, recruits and adults. Our results indicate that large-scale factors (potentially currents, nutrients, temperature, etc. determine larval availability and settlement in the pelagic stages of urchin life history. In rocky macroalgal habitats, benthic processes (like predation acting at large or medium scales drive adult abundances. In contrast, adult numbers in seagrass meadows are most likely influenced by factors like local migration (from adjoining rocky habitats functioning at much smaller scales. The complexity of spatial and habitat-dependent processes shaping urchin populations demands a multiplicity of approaches when addressing habitat conservation actions, yet such actions are currently mostly aimed at managing predation processes and fish numbers. We argue that a more holistic ecosystem management also needs to incorporate the

  3. Benthic meiofaunal community response to the cascading effects of herbivory within an algal halo system of the Great Barrier Reef.

    Science.gov (United States)

    Ollivier, Quinn R; Hammill, Edward; Booth, David J; Madin, Elizabeth M P; Hinchliffe, Charles; Harborne, Alastair R; Lovelock, Catherine E; Macreadie, Peter I; Atwood, Trisha B

    2018-01-01

    Benthic fauna play a crucial role in organic matter decomposition and nutrient cycling at the sediment-water boundary in aquatic ecosystems. In terrestrial systems, grazing herbivores have been shown to influence below-ground communities through alterations to plant distribution and composition, however whether similar cascading effects occur in aquatic systems is unknown. Here, we assess the relationship between benthic invertebrates and above-ground fish grazing across the 'grazing halos' of Heron Island lagoon, Australia. Grazing halos, which occur around patch reefs globally, are caused by removal of seagrass or benthic macroalgae by herbivorous fish that results in distinct bands of unvegetated sediments surrounding patch reefs. We found that benthic algal canopy height significantly increased with distance from patch reef, and that algal canopy height was positively correlated with the abundances of only one invertebrate taxon (Nematoda). Both sediment carbon to nitrogen ratios (C:N) and mean sediment particle size (μm) demonstrated a positive correlation with Nematoda and Arthropoda (predominantly copepod) abundances, respectively. These positive correlations indicate that environmental conditions are a major contributor to benthic invertebrate community distribution, acting on benthic communities in conjunction with the cascading effects of above-ground algal grazing. These results suggest that benthic communities, and the ecosystem functions they perform in this system, may be less responsive to changes in above-ground herbivorous processes than those previously studied in terrestrial systems. Understanding how above-ground organisms, and processes, affect their benthic invertebrate counterparts can shed light on how changes in aquatic communities may affect ecosystem function in previously unknown ways.

  4. Rhythmic behaviour of marine benthopelagic species and the synchronous dynamics of benthic communities

    Science.gov (United States)

    Aguzzi, Jacopo; Sbragaglia, Valerio; Tecchio, Samuele; Navarro, Joan; Company, Joan B.

    2015-01-01

    Light-intensity cycles drive the relentless motion of species in the oceans, and water column migrants may cyclically make contact with the seabed, hence influencing the temporal dynamism of benthic ecosystems. The influence of light on this process remains largely unknown to date. In this study, we focus on the occurrence of day-night changes in benthic communities on the western Mediterranean continental shelf (100 m depth) and slope (400 m depth) as a potential result of a behaviourally sustained benthopelagic coupling. We analysed fluctuations in species abundance based on trawling at hourly intervals over a 4-day period as a proxy of activity rhythms at the seabed. We also measured light in situ to assess how the depth-related decrease of its intensity influences species rhythms and the occurrence of the putative benthopelagic synchronisation. Temporal similarities in the catch patterns for different species were screened by dendrogram analysis. On the continental shelf, species performing diel migrations (i.e., over a 24 h period) that were either vertical (i.e., benthopelagic) or horizontal across depths (i.e., nektobenthic) clustered together separately from the more sedentary endobenthic and epibenthic species. At the same depth, waveform analysis showed a significant diurnal increase in the catch of water column species and benthic species at night. Such coupling was absent on the continental slope, where light intensity was several orders of magnitude lower than that on the shelf. Our data indicate that diel activity rhythms, which are well known for vertical pelagic migrators, are also evident in the benthos. We discuss the role of light as a major evolutionary driver shaping the composition and biodiversity of benthic communities via visual predation.

  5. Historical changes in the structure and functioning of the benthic community in the lagoon of Venice

    Science.gov (United States)

    Pranovi, Fabio; Da Ponte, Filippo; Torricelli, Patrizia

    2008-03-01

    One of the main challenges in environmental management is how to manage the dynamics of natural environments. In this context, having information about historical changes of the structure of the biological communities could represent a useful tool to improve management strategies, contributing to refine the policy objectives, since it gives reference states with which to compare the present. The Venice lagoon represents an interesting case study, since it is a highly dynamic, but sensitive, environment which requires the adoption of prudent management. In its recent history the lagoon ecosystem has been exposed to different kinds of disturbance, from the discharge of pollutants and nutrients, to the invasion of alien species and the exploitation of its biological resources by using highly impacting fishing gears. The analysis of available data about the macro-benthic community, from 1935 to 2004, allows the description of changes of the community structure over almost 70 years, showing a sharp decrease in its diversity. In order to obtain information about its functioning, it is necessary to know how these changes have affected processes at the community and system level. In shallow water ecosystems, as the control is mainly due to the benthic compartment, variations in the structure of the benthic community can induce modifications in processes at different hierarchical levels. The trophic structure analysis has revealed major changes during the period; from a well-assorted structure in 1935, to an herbivore-detritivore dominated one in the 1990s, and finally to a filter feeder dominated structure during the last decade. This has produced variations in the secondary production and it has induced modifications in the type of the ecosystem control. These changes are discussed in the light of the dynamics of the main driving forces.

  6. Response of benthic macroinvertebrate communities to highway construction in an Appalachian watershed

    Science.gov (United States)

    Hedrick, Lara B.; Welsh, S.A.; Anderson, James T.; Lin, L.-S.; Chen, Y.; Wei, X.

    2010-01-01

    Highway construction in mountainous areas can result in sedimentation of streams, negatively impacting stream habitat, water quality, and biotic communities. We assessed the impacts of construction of a segment of Corridor H, a four-lane highway, in the Lost River watershed, West Virginia, by monitoring benthic macroinvertebrate communities and water quality, before, during, and after highway construction and prior to highway use at upstream and downstream sites from 1997 through 2007. Data analysis of temporal impacts of highway construction followed a Before-After-Control-Impact (BACI) study design. Highway construction impacts included an increase in stream sedimentation during the construction phase. This was indicated by an increase in turbidity and total suspended solids. Benthic macroinvertebrate metrics indicated a community more tolerant during and after construction than in the period before construction. The percent of Chironomidae and the Hilsenhoff Biotic Index (HBI) increased, while percent of Ephemeroptera, Plecoptera, and Trichoptera (EPT) decreased. Our 10-year study addressed short-term impacts of highway construction and found that impacts were relatively minimal. A recovery of the number of EPT taxa collected after construction indicated that the benthic macroinvertebrate community may be recovering from impacts of highway construction. However, this study only addressed a period of 3 years before, 3 years during, and 4 years post construction. Inferences cannot be made concerning the long-term impacts of the highway, highway traffic, runoff, and other factors associated with highway use. Continual monitoring of the watershed is necessary to determine if the highway has a continual impact on stream habitat, water quality, and biotic integrity. ?? 2010 Springer Science+Business Media B.V.

  7. Different Oceanographic Regimes in the Vicinity of the Antarctic Peninsula Reflected in Benthic Nematode Communities.

    Directory of Open Access Journals (Sweden)

    Freija Hauquier

    Full Text Available Marine free-living nematode communities were studied at similar depths (~500 m at two sides of the Antarctic Peninsula, characterised by different environmental and oceanographic conditions. At the Weddell Sea side, benthic communities are influenced by cold deep-water formation and seasonal sea-ice conditions, whereas the Drake Passage side experiences milder oceanic conditions and strong dynamics of the Antarctic Circumpolar Current. This resulted in different surface primary productivity, which contrasted with observed benthic pigment patterns and varied according to the area studied: chlorophyll a concentrations (as a proxy for primary production were high in the Weddell Sea sediments, but low in the surface waters above; this pattern was reversed in the Drake Passage. Differences between areas were largely mirrored by the nematode communities: nematode densities peaked in Weddell stations and showed deeper vertical occurrence in the sediment, associated with deeper penetration of chlorophyll a and indicative of a strong bentho-pelagic coupling. Generic composition showed some similarities across both areas, though differences in the relative contribution of certain genera were noted, together with distinct community shifts with depth in the sediment at all locations.

  8. Divergent ecosystem responses within a benthic marine community to ocean acidification.

    Science.gov (United States)

    Kroeker, Kristy J; Micheli, Fiorenza; Gambi, Maria Cristina; Martz, Todd R

    2011-08-30

    Ocean acidification is predicted to impact all areas of the oceans and affect a diversity of marine organisms. However, the diversity of responses among species prevents clear predictions about the impact of acidification at the ecosystem level. Here, we used shallow water CO(2) vents in the Mediterranean Sea as a model system to examine emergent ecosystem responses to ocean acidification in rocky reef communities. We assessed in situ benthic invertebrate communities in three distinct pH zones (ambient, low, and extreme low), which differed in both the mean and variability of seawater pH along a continuous gradient. We found fewer taxa, reduced taxonomic evenness, and lower biomass in the extreme low pH zones. However, the number of individuals did not differ among pH zones, suggesting that there is density compensation through population blooms of small acidification-tolerant taxa. Furthermore, the trophic structure of the invertebrate community shifted to fewer trophic groups and dominance by generalists in extreme low pH, suggesting that there may be a simplification of food webs with ocean acidification. Despite high variation in individual species' responses, our findings indicate that ocean acidification decreases the diversity, biomass, and trophic complexity of benthic marine communities. These results suggest that a loss of biodiversity and ecosystem function is expected under extreme acidification scenarios.

  9. The effects of oil pollution on Antarctic benthic diatom communities over 5 years

    International Nuclear Information System (INIS)

    Polmear, R.; Stark, J.S.; Roberts, D.; McMinn, A.

    2015-01-01

    Highlights: • We examine the impact of hydrocarbon pollution on Antarctic benthic diatoms. • The effect of standard synthetic lubricant oil and a biodegradable oil were examined. • There were significant effects from both treatments for over 5 years. • There was little difference between the different types of oil. - Abstract: Although considered pristine, Antarctica has not been impervious to hydrocarbon pollution. Antarctica’s history is peppered with oil spills and numerous abandoned waste disposal sites. Both spill events and constant leakages contribute to previous and current sources of pollution into marine sediments. Here we compare the response of the benthic diatom communities over 5 years to exposure to a commonly used standard synthetic lubricant oil, an alternative lubricant marketed as more biodegradable, in comparison to a control treatment. Community composition varied significantly over time and between treatments with some high variability within contaminated treatments suggesting community stress. Both lubricants showed evidence of significant effects on community composition after 5 years even though total petroleum hydrocarbon reduction reached approximately 80% over this time period. It appears that even after 5 years toxicity remains high for both the standard and biodegradable lubricants revealing the temporal scale at which pollutants persist in Antarctica

  10. The effects of oil pollution on Antarctic benthic diatom communities over 5 years.

    Science.gov (United States)

    Polmear, R; Stark, J S; Roberts, D; McMinn, A

    2015-01-15

    Although considered pristine, Antarctica has not been impervious to hydrocarbon pollution. Antarctica's history is peppered with oil spills and numerous abandoned waste disposal sites. Both spill events and constant leakages contribute to previous and current sources of pollution into marine sediments. Here we compare the response of the benthic diatom communities over 5 years to exposure to a commonly used standard synthetic lubricant oil, an alternative lubricant marketed as more biodegradable, in comparison to a control treatment. Community composition varied significantly over time and between treatments with some high variability within contaminated treatments suggesting community stress. Both lubricants showed evidence of significant effects on community composition after 5 years even though total petroleum hydrocarbon reduction reached approximately 80% over this time period. It appears that even after 5 years toxicity remains high for both the standard and biodegradable lubricants revealing the temporal scale at which pollutants persist in Antarctica. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Natural disturbance shapes benthic intertidal macroinvertebrate communities of high latitude river deltas

    Science.gov (United States)

    Churchwell, Roy T.; Kendall, Steve J.; Blanchard, Amy L.; Dunton, Kenneth H.; Powell, Abby N.

    2016-01-01

    Unlike lower latitude coastlines, the estuarine nearshore zones of the Alaskan Beaufort Sea are icebound and frozen up to 9 months annually. This annual freezing event represents a dramatic physical disturbance to fauna living within intertidal sediments. The main objectives of this study were to describe the benthic communities of Beaufort Sea deltas, including temporal changes and trophic structure. Understanding benthic invertebrate communities provided a baseline for concurrent research on shorebird foraging ecology at these sites. We found that despite continuous year-to-year episodes of annual freezing, these estuarine deltas are populated by a range of invertebrates that represent both marine and freshwater assemblages. Freshwater organisms like Diptera and Oligochaeta not only survive this extreme event, but a marine invasion of infaunal organisms such as Amphipoda and Polychaeta rapidly recolonizes the delta mudflats following ice ablation. These delta sediments of sand, silt, and clay are fine in structure compared to sediments of other Beaufort Sea coastal intertidal habitats. The relatively depauperate invertebrate community that ultimately develops is composed of marine and freshwater benthic invertebrates. The composition of the infauna also reflects two strategies that make life on Beaufort Sea deltas possible: a migration of marine organisms from deeper lagoons to the intertidal and freshwater biota that survive the 9-month ice-covered period in frozen sediments. Stable isotopic analyses reveal that both infaunal assemblages assimilate marine and terrestrial sources of organic carbon. These results provide some of the first quantitative information on the infaunal food resources of shallow arctic estuarine systems and the long-term persistence of these invertebrate assemblages. Our data help explain the presence of large numbers of shorebirds in these habitats during the brief summer open-water period and their trophic importance to migrating

  12. Impact of exploratory offshore drilling on benthic communities in the Minerva gas field, Port Campbell, Australia

    Energy Technology Data Exchange (ETDEWEB)

    Currie, D.R.; Isaacs, L.R. [Central Queensland Univ., Gladstone (Australia). Centre for Environmental Management

    2005-04-01

    Changes to benthic infauna caused by exploratory gas drilling operations in the Minerva field were examined experimentally using a BACI (before, after, control, impact) design. Analysis of 72 x 0.1 m{sup 2} Smith-McIntyre grab samples obtained from one pre-drilling and three post-drilling periods yielded a diverse fauna consisting of 196 invertebrate species and 5035 individuals. Changes to benthic community structure were assessed using ANOVA and nonmetric multidimensional scaling (MDS). The abundances of two common species (Apseudes sp. 1 and Prionospio coorilla) decreased significantly at the well-head site immediately after drilling. The size of these reductions in abundance ranged between 71% and 88%, and persisted for less than 4 months after drilling. A third common species (Katlysia sp. 1) increased in abundance 200 m east of the well-head following drilling. Most species occurred at densities too low to be analysed individually and so were pooled at higher taxonomic levels. Changes in the abundance of species aggregated by phylum varied, but significant declines in the most abundant phyla (Crustaceans and Polychaetes) of 45-73% were observed at all sites within a 100 m radius of the well-head following drilling. In most cases these changes became undetectable four months after drilling following species recruitments. MDS ordinations confirm that drilling related changes to benthic community structure are most pronounced at stations located closest to the well-head. Additionally, the ordinations indicate that modified communities persist at the well-head for more than 11 months following exploratory drilling. (author)

  13. Incidence of invasive macrophytes on methylmercury budget in temperate lakes: Central role of bacterial periphytic communities

    International Nuclear Information System (INIS)

    Gentès, Sophie; Monperrus, Mathilde; Legeay, Alexia; Maury-Brachet, Régine; Davail, Stephane; André, Jean-Marc; Guyoneaud, Rémy

    2013-01-01

    Several studies demonstrated high mercury (Hg) methylation and demethylation in the periphyton associated with floating roots in tropical ecosystems. The importance of aquatic plants on methylmercury production in three temperate ecosystems from south-western France was evaluated through Hg species concentrations, and Hg methylation/demethylation activities by using stable isotopic tracers ( 199 Hg(II), Me 201 Hg). Hg accumulation and high methylation and demethylation yields were detected in plant roots and periphyton, whereas results for sediment and water were low to insignificant. The presence of sulfate reducing prokaryotes was detected in all compartments (T-RFLP based on dsrAB amplified through nested PCR) and their main role in Hg methylation could be demonstrated. In turn, sulfate reduction inhibition did not affect demethylation activities. The estimation of net MeHg budgets in these ecosystems suggested that aquatic rhizosphere is the principal location for methylmercury production and may represent an important source for the contamination of the aquatic food chain. - Highlights: ► Both Hg methylation and demethylation occur in the periphyton of temperate ecosystems. ► Aquatic rhizosphere is the main compartment for net methylmercury production. ► Sulfate reducers are detected in all ecosystem compartments (water, sediment, periphyton). ► Sulfate reducers are responsible for methylmercury production in aquatic roots. - The incidence of periphytic microbial communities on net methylmercury production is highlighted in temperate aquatic ecosystems.

  14. Cascading effects of flow reduction on the benthic invertebrate community in a lowland river

    DEFF Research Database (Denmark)

    Graeber, Daniel; Pusch, Martin T.; Lorenz, Stefan

    2013-01-01

    on dissolved oxygen concentrations (DO) have not yet received much attention. We compared the macroinvertebrate composition between reference conditions and a situation after several years of discharge reduction in the Spree River (Brandenburg, Germany). Community composition shifted from rheophilic species...... concentration minima of less than 5 mg l−1 which prevailed 74% of the days in summer. This depletion of DO after flow reduction presumably caused the observed species turnover. Hence, flow reduction in lowland rivers may not only directly impair the ecological functions provided by benthic macroinvertebrates...

  15. Effects of fine suspended sediment releases on benthic communities in artificial flumes

    International Nuclear Information System (INIS)

    Bruno, Maria Cristina; Carolli, Mauro; Zolezzi, Guido; Palmia, Beatrice

    2016-01-01

    The Italian Alps feed a large number of reservoirs for hydropower production, which are losing storage capacity due to natural inflow of sediment of different origin (alluvial, glacial). Local government and local environmental agencies authorize periodical sediment flushes with a mandatory release regime when such measure is technically feasible. Management of reservoirs often includes fine sediment pulses, which cause several ecological impacts on downstream water bodies. We conducted a set of simulations in five semi artificial flumes naturally fed by an un-impacted Alpine stream (Trentino region, NE Italy), to: i) identify possible thresholds of concentration of fine suspended sediment inducing drift in the benthic community and, ii) assess the dynamics and intensity of the drift responses in the dominant taxa. The results can help to identify the least impacting release management practices. Sediment pulses were simulated by adding fine material of known concentration to the upstream end of the flumes. The benthic organisms drifting from the whole flume were collected by filtering the whole outflow for consecutive short time intervals. We tested four different concentration values, i.e. 10x,100x, 250x, 500x the base concentration of 4 NTU, and we repeated the simulations in two periods: July, when the community is composed mainly of young larval instars and the sediment wave lasted 10 minutes, and October, when later larval stages are dominant and the wave lasted 20 minutes. In July, the maximum concentration induced a significantly higher drift response than the three lower ones. In October, even if the sediment wave was twice as long as July one, drift responses where lower, and only the responses to the highest and lowest concentrations differed significantly. In our simulation, the only possible cause for the observed increase in drift was the sediment in the suspended phase, as the deposition of sediment was negligible, and discharge did not increase

  16. Internal tides affect benthic community structure in an energetic submarine canyon off SW Taiwan

    Science.gov (United States)

    Liao, Jian-Xiang; Chen, Guan-Ming; Chiou, Ming-Da; Jan, Sen; Wei, Chih-Lin

    2017-07-01

    Submarine canyons are major conduits of terrestrial and shelf organic matter, potentially benefiting the seafloor communities in the food-deprived deep sea; however, strong bottom currents driven by internal tides and the potentially frequent turbidity currents triggered by storm surges, river flooding, and earthquakes may negatively impact the benthos. In this study, we investigated the upper Gaoping Submarine Canyon (GPSC), a high-sediment-yield canyon connected to a small mountain river (SMR) off southwest (SW) Taiwan. By contrasting the benthic meiofaunal and macrofaunal communities within and outside the GPSC, we examined how food supplies and disturbance influenced the benthic community assemblages. The benthic communities in the upper GPSC were mainly a nested subset of the adjacent slope assemblages. Several meiofaunal (e.g. ostracods) and macrofaunal taxa (e.g. peracarid crustaceans and mollusks) that typically occurred on the slope were lost from the canyon. The polychaete families switched from diverse feeding guilds on the slope to motile subsurface deposit feeders dominant in the canyon. The diminishing of epibenthic peracarids and proliferation of deep burrowing polychaetes in the GPSC resulted in macrofauna occurring largely within deeper sediment horizons in the canyon than on the slope. The densities and numbers of taxa were depressed with distinct and more variable composition in the canyon than on the adjacent slope. Both the densities and numbers of taxa were negatively influenced by internal tide flushing and positively influenced by food availability; however, the internal tides also negatively influenced the food supplies. While the meiofauna and macrofauna densities were both depressed by the extreme physical conditions in the GPSC, only the macrofaunal densities increased with depth in the canyon, presumably related to increased frequency and intensity of disturbance toward the canyon head. The population densities of meiofauna, on the

  17. History of benthic research in the English Channel: From general patterns of communities to habitat mosaic description

    Science.gov (United States)

    Dauvin, Jean-Claude

    2015-06-01

    Benthic studies in the English Channel (EC), a shallow megatidal and epicontinental sea, began in the 1960s and 1970s with the work of teams led by Norman Holme (UK) and Louis Cabioch (F). During this period, benthic sampling was mainly qualitative, i.e. using a device such as the 'Rallier du Baty' dredge in the case of the French team and a modified anchor dredge in the case of the British team. Studies were focused on acquiring knowledge of the main distributions of benthic communities and species. Surveys on the scale of the whole EC led to the recognition of general features and two main patterns were identified: 1) the role of hydrodynamics on the spatial distribution of sediment, benthic species and communities; 2) the presence of a west-east climatic gradient of faunal impoverishment. Benthic studies in the 1980s-1990s were focused on the beginning of the implementation of long-term survey at a limited number of sites to identify seasonal and multi-annual changes. In the first decade of the 2000s, the implementation of the European Water Framework Directive and the Marine Strategy Framework Directive to define the Ecological Quality Status of marine environments increased the need to acquire better information of the structure and functioning of benthic communities, since benthic species and habitats were recognised as good indicators of human pressure on marine ecosystems. Faced with the increase of human maritime activities, the appearance of invasive species and the need to preserve sensitive marine habitats, benthic studies have been focused on developing a 'toolkit' to help in the decision-making and planning for both sound governance and sustainable management of marine resources and human activities in the English Channel. Multidisciplinary approaches were used to differentiate habitats in a more precise detail. Both indirect (side-scan sonar, ROV) and direct (grab sampling with benthos identification and grain-size analyses) approaches were used and

  18. 27 years of benthic and coral community dynamics on turbid, highly urbanised reefs off Singapore.

    Science.gov (United States)

    Guest, J R; Tun, K; Low, J; Vergés, A; Marzinelli, E M; Campbell, A H; Bauman, A G; Feary, D A; Chou, L M; Steinberg, P D

    2016-11-08

    Coral cover on reefs is declining globally due to coastal development, overfishing and climate change. Reefs isolated from direct human influence can recover from natural acute disturbances, but little is known about long term recovery of reefs experiencing chronic human disturbances. Here we investigate responses to acute bleaching disturbances on turbid reefs off Singapore, at two depths over a period of 27 years. Coral cover declined and there were marked changes in coral and benthic community structure during the first decade of monitoring at both depths. At shallower reef crest sites (3-4 m), benthic community structure recovered towards pre-disturbance states within a decade. In contrast, there was a net decline in coral cover and continuing shifts in community structure at deeper reef slope sites (6-7 m). There was no evidence of phase shifts to macroalgal dominance but coral habitats at deeper sites were replaced by unstable substrata such as fine sediments and rubble. The persistence of coral dominance at chronically disturbed shallow sites is likely due to an abundance of coral taxa which are tolerant to environmental stress. In addition, high turbidity may interact antagonistically with other disturbances to reduce the impact of thermal stress and limit macroalgal growth rates.

  19. Influence of environmental factors on the benthic invertebrates community distribution in channels of a neotropical floodplain

    Directory of Open Access Journals (Sweden)

    Danielle Katharine Petsch

    2013-09-01

    Full Text Available One of the central themes in ecology is the relative importance of local and regional processes for determining the communities’ structure, since both processes may behave as filters in the composition of local communities. Thus, this study analyzed the influence of environmental factors on the benthic invertebrate community distribution in different channels of the Upper Paraná River floodplain, through quarterly samplings conducted from March to December 2010. Through the biotic and abiotic data, we performed a Canonical Correspondence Analysis, where it was possible to visualize the centers of Ivinhema and Paraná rivers and Ipoitã channel separate from other points by high values of depth and velocity and taxa typical of lotic environments, such as Harpacticoida, Haplotaxidae, and Narapidae, and the center of the Curutuba channel, with L. fortunei. One may conclude that flow velocity, granulometric texture, and sediment organic matter were structuring factors of the benthic community, determining the distribution of invertebrates both among the various channels and between the marginal and central regions in these environments, providing greater or lesser availability of resources and environmental heterogeneity.

  20. Distribution of polycyclic aromatic hydrocarbons (PAHs) and tributyltin (TBT) in Barcelona harbour sediments and their impact on benthic communities

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Llado, Xavier [Environmental Technology Area, CTM-UPC, Avda. Bases de Manresa 1, 08240 Manresa (Spain); Gibert, Oriol [Environmental Technology Area, CTM-UPC, Avda. Bases de Manresa 1, 08240 Manresa (Spain); Marti, Vicens [Environmental Technology Area, CTM-UPC, Avda. Bases de Manresa 1, 08240 Manresa (Spain)]. E-mail: vicens.marti@upc.edu; Diez, Sergi [Environmental Chemistry Department, IIQAB-CSIC, c/Jordi Girona 18-26, 08034 Barcelona (Spain); Environmental Geology Department, ICTJA-CSIC, Lluis Sole i Sabaris, s/n, 08028 Barcelona (Spain); Romo, Javier [Environmental Service of Barcelona Harbour Authority, Carretera de la Circumval.lacio, s/n, Tram VI, Sector 6, Barcelona (Spain); Bayona, Josep Maria [Environmental Chemistry Department, IIQAB-CSIC, c/Jordi Girona 18-26, 08034 Barcelona (Spain); Pablo, Joan de [Environmental Technology Area, CTM-UPC, Avda. Bases de Manresa 1, 08240 Manresa (Spain)

    2007-09-15

    Sediments have long been recognised as a sink for many contaminants like polycyclic aromatic hydrocarbons (PAHs) and tributyltin (TBT), which by virtue of their nature can strongly adsorb onto sediments affecting the benthic community inhabiting them. Using geographical information systems, this study reports and combines the results of several already existing studies along Barcelona harbour in order to assess the potential ecological impacts of these contaminants on the benthos of the harbour ecosystem. Chemical analysis indicated low to moderate contents of PAHs and high contents of TBT in sediments in Barcelona harbour. Comparison against existing sediment quality guidelines (SQGs) indicated that acutely toxic effects would not be expected for PAHs but for TBT, which represents a serious environmental threat for the benthic community. Benthos surveys revealed a deterioration of the benthic community throughout the harbour, especially in the inner port. - A possible correlation exists between TBT concentration in sediments and ecological effects on benthos in Barcelona harbour.

  1. Distribution of polycyclic aromatic hydrocarbons (PAHs) and tributyltin (TBT) in Barcelona harbour sediments and their impact on benthic communities

    International Nuclear Information System (INIS)

    Martinez-Llado, Xavier; Gibert, Oriol; Marti, Vicens; Diez, Sergi; Romo, Javier; Bayona, Josep Maria; Pablo, Joan de

    2007-01-01

    Sediments have long been recognised as a sink for many contaminants like polycyclic aromatic hydrocarbons (PAHs) and tributyltin (TBT), which by virtue of their nature can strongly adsorb onto sediments affecting the benthic community inhabiting them. Using geographical information systems, this study reports and combines the results of several already existing studies along Barcelona harbour in order to assess the potential ecological impacts of these contaminants on the benthos of the harbour ecosystem. Chemical analysis indicated low to moderate contents of PAHs and high contents of TBT in sediments in Barcelona harbour. Comparison against existing sediment quality guidelines (SQGs) indicated that acutely toxic effects would not be expected for PAHs but for TBT, which represents a serious environmental threat for the benthic community. Benthos surveys revealed a deterioration of the benthic community throughout the harbour, especially in the inner port. - A possible correlation exists between TBT concentration in sediments and ecological effects on benthos in Barcelona harbour

  2. Measuring ecological change of aquatic macrophytes in Mediterranean rivers

    OpenAIRE

    Dodkins, Ian; Aguiar, Francisca; Rivaes, Rui; Albuquerque, António; Rodriguez-Gonzalez, Patricia; Ferreira, Maria Teresa

    2012-01-01

    A metric was developed for assessing anthropogenic impacts on aquatic macrophyte ecology by scoring macrophyte species along the main gradient of community change. A measure of ecological quality was then calculated by Weighted Averaging (WA) of these species scores at a monitoring site, and comparison to a reference condition score. This metric was used to illustrate the difficulties of developing aquatic macrophyte indices based on indicator species in Mediterranean rivers. The ...

  3. Benthic Ammonia Oxidizers Differ in Community Structure and Biogeochemical Potential Across a Riverine Delta

    Directory of Open Access Journals (Sweden)

    Julian eDamashek

    2015-01-01

    Full Text Available Nitrogen pollution in coastal zones is a widespread issue, particularly in ecosystems with urban or agricultural watersheds. California’s Sacramento-San Joaquin Delta, at the landward reaches of San Francisco Bay, is highly impacted by both agricultural runoff and sewage effluent, leading to chronically high nutrient loadings. In particular, the massive discharge of ammonium into the Sacramento River has altered this ecosystem by increasing ammonium concentrations and thus changing the stoichiometry of inorganic nitrogen stocks, with potential effects throughout the food web. To date, however, there has been little research examining N biogeochemistry or N-cycling microbial communities in this system. We report the first data on benthic ammonia-oxidizing microbial communities and potential nitrification rates for the Sacramento-San Joaquin Delta, focusing on the functional gene amoA (encoding the α-subunit of ammonia monooxygenase. There were stark regional differences in ammonia-oxidizing communities, with ammonia-oxidizing bacteria (AOB outnumbering ammonia-oxidizing archaea (AOA only in the ammonium-rich Sacramento River. High potential nitrification rates in the Sacramento River suggested these communities may be capable of oxidizing significant amounts of ammonium, compared to the San Joaquin River and the upper reaches of San Francisco Bay. Gene diversity also showed regional patterns, as well as phylogenetically unique ammonia oxidizers in the Sacramento River. The community structure and biogeochemical function of benthic ammonia oxidizers appears related to nutrient loadings. Unraveling the microbial ecology and biogeochemistry of N cycling pathways is a critical step toward understanding how such ecosystems respond to the changing environmental conditions wrought by human development and climate change.

  4. Large-scale assessment of benthic communities across multiple marine protected areas using an autonomous underwater vehicle.

    Science.gov (United States)

    Ferrari, Renata; Marzinelli, Ezequiel M; Ayroza, Camila Rezende; Jordan, Alan; Figueira, Will F; Byrne, Maria; Malcolm, Hamish A; Williams, Stefan B; Steinberg, Peter D

    2018-01-01

    Marine protected areas (MPAs) are designed to reduce threats to biodiversity and ecosystem functioning from anthropogenic activities. Assessment of MPAs effectiveness requires synchronous sampling of protected and non-protected areas at multiple spatial and temporal scales. We used an autonomous underwater vehicle to map benthic communities in replicate 'no-take' and 'general-use' (fishing allowed) zones within three MPAs along 7o of latitude. We recorded 92 taxa and 38 morpho-groups across three large MPAs. We found that important habitat-forming biota (e.g. massive sponges) were more prevalent and abundant in no-take zones, while short ephemeral algae were more abundant in general-use zones, suggesting potential short-term effects of zoning (5-10 years). Yet, short-term effects of zoning were not detected at the community level (community structure or composition), while community structure varied significantly among MPAs. We conclude that by allowing rapid, simultaneous assessments at multiple spatial scales, autonomous underwater vehicles are useful to document changes in marine communities and identify adequate scales to manage them. This study advanced knowledge of marine benthic communities and their conservation in three ways. First, we quantified benthic biodiversity and abundance, generating the first baseline of these benthic communities against which the effectiveness of three large MPAs can be assessed. Second, we identified the taxonomic resolution necessary to assess both short and long-term effects of MPAs, concluding that coarse taxonomic resolution is sufficient given that analyses of community structure at different taxonomic levels were generally consistent. Yet, observed differences were taxa-specific and may have not been evident using our broader taxonomic classifications, a classification of mid to high taxonomic resolution may be necessary to determine zoning effects on key taxa. Third, we provide an example of statistical analyses and

  5. Analysis of a benthic community food web using isotopically labelled potential food

    International Nuclear Information System (INIS)

    Beviss-Challinor, M.H.; Field, J.G.

    1982-01-01

    A series of experiments was designed to reveal the trophic structure of a benthic community using kelp holdfasts as microcosms within the kelp-bed community. The experimental food comprised zooplankton represented by 3 H 2 O-labelled Artemia sp. eggs and nauplii (200 to 300 μm), detritus derived from 14 C-labelled kelp (60 to 90 μm), and phytoplankton represented by 14 C-labelled Dunaliella primolecta (5 to 10 μm) cultures. Separate experiments of short duration (1 to 2 h) were used to indicate the primary consumers on each type of food, while longer experiments (4, 8 and 16 h) suggested the secondary consumers (coprophagous and carnivorous species). Several species were found to be omnivorous. (orig.)

  6. Deep-sea benthic community and environmental impact assessment at the Atlantic Frontier

    Science.gov (United States)

    Gage, John D.

    2001-05-01

    The seabed community provides a sensitive litmus for environmental change. North Sea analysis of benthic populations provides an effective means for monitoring impacts from man's interventions, such as offshore oil exploitation and fishing, against baseline knowledge of the environment. Comparable knowledge of the benthic biology in the deep waters of the Atlantic Frontier beyond the N.E. Atlantic shelf edge is poorly developed. But uncertainties should not encourage assumptions and extrapolations from the better-known conditions on the continental shelf. While sampling at present still provides the best means to assess the health of the deepwater benthic habitat, protocols developed for deep-sea fauna should be applied. These are necessary because of (a) lower faunal densities, (b) higher species richness, (c) smaller body size, and (d) to ensure comparability with other deep-sea data. As in the North Sea, species richness and relative abundance can be analysed from quantitative samples in order to detect impacts. But analysis based on taxonomic sufficiency above species level is premature, even if arguably possible for coastal communities. Measures also need to ensure identifications are not forced to more familiar coastal species without proper study. Species-level analysis may be applied to seabed photographs of megafauna in relation to data on bottom environment, such as currents and the sediment, to monitor the health of the deep-water community. Although the composition of higher taxa in the benthic community is broadly similar to soft sediments on the shelf, concordance in sensitivities is speculative. Moreover, new organisms occur, such as giant protozoan xenophyophores, unknown on the continental shelf, whose sensitivities remain conjectural. Past knowledge of the benthic biology of the deep-water areas off Scotland is based on scattered stations and some more focussed, multidisciplinary studies, and should be significantly augmented by the results from

  7. Effects of offshore oil drilling on benthic invertebrate communities on the Grand Banks (North Atlantic)

    Energy Technology Data Exchange (ETDEWEB)

    DeBlois, E. [Jacques Whitford Ltd., St. John' s, NL (Canada); Wight, F. [Husky Oil Operations Ltd., St. John' s, NL (Canada); Taylor, D. [DG Taylor Inc., Conception Bay South, NL (Canada); Paine, M. [Paine, Ledge and Associates, North Vancouver, BC (Canada)

    2007-07-01

    Drilling occurs at three different drill centres of the White Rose (WR) oil platform that lies 350 km offshore from St. John's Newfoundland. An extensive environmental effects monitoring (EEM) program conducted by Husky Energy is underway at the WR site. The sediment component of the program involves the measurement of physical and chemical characteristics, an assessment of toxicity in laboratory tests, and an assessment of in situ benthic invertebrate communities. Baseline sampling occurred in 2000, followed by post-drilling sampling in 2004 to 2006. The sediment is 95 per cent sand, with polychaetes and bivalves dominating the invertebrate communities. A comparative evaluation was performed for regressions between community variables and distances from drill centres before and after drilling. Concentration-response relationships between community variables and concentrations of major constituents in drilling muds (C10-C21 HCs) were also compared among years. It was shown that the biological effects on invertebrate communities were highly restricted to reductions in the amount of Paraonidae and Amphipoda near drill centres and at higher C10-C21 HC concentrations. The study revealed that the two most abundant invertebrate communities were not influenced by drilling in terms of standing crop, richness, diversity and evenness.

  8. The influence of multiple chemical and non-chemical stressors on benthic communities in a mid-west agricultural stream.

    Science.gov (United States)

    Hall, Lenwood W; Killen, Willian D; Anderson, Ronald D; Alden, Raymond W

    2017-08-24

    The objective of this 3-year study was to characterize benthic communities and physical habitat in an agricultural stream in the mid-west area of the United States (Big Bureau Creek, Illinois). Concurrent basic water quality parameters and seven nutrients were measured in the water column. Sediment measurements from depositional areas were conducted for bifenthrin, Total Organic Carbon, grain size, polychlorinated biphenyls (PCBs) and eight metals. All parameters were measured at 12 sites annually during the late summer for a 3-year period (2014, 2015 and 2016). Univariate regressions, stepwise multiple regressions and canonical correlation statistical analyses were used to determine the relationship between various benthic metrics (i.e., taxa richness and abundance) and all the measured parameters for the 3-year database. Benthic communities comprising 108-110 taxa were collected annually, and were generally dominated by sensitive caddisflies and mayflies. These communities were rated as good to exceptional using the Ohio Invertebrate Community Index. Physical habitat for the various sites was rated as good using the Ohio Qualitative Habitat Evaluation Index, thus suggesting that habitat is not a significant stressor that would likely impact resident benthic communities. Based on a comparison of measured in-stream total nitrogen and total phosphorus concentrations and criterion value exceedances, it appears that the in-stream nutrient concentrations could be potentially stressful to resident benthic biota. Metal concentrations were below established NOAA Threshold Effects Levels at all sites. Measured PCB concentrations were below levels of detection at all sites. Toxic units' (TUs) calculations based on using sensitive laboratory strains of Hyalella were less than 0.1 for bifenthrin, thus suggesting that bifenthrin sediment toxicity was unlikely. Thirty significant relationships reported between benthic metrics and the various environmental variables based on the

  9. The role of pelagic-benthic coupling in structuring littoral benthic communities at Terra Nova Bay (Ross Sea and in the Straits of Magellan

    Directory of Open Access Journals (Sweden)

    Riccardo Cattaneo-Vietti

    1999-12-01

    Full Text Available In Antarctic and peri-Antarctic regions, benthic communities are persistent in time and show high biomass and large numbers of individuals, mainly consisting of suspension and deposit feeders. In fact, apart from recruitment, the major factor structuring these communities is the high flow of organic matter from the pelagic domain to the bottom, representing an important energy source for the benthic organisms. The aim of this paper is to review, compile and compare the data from earlier investigations in Terra Nova Bay (Ross Sea and the Straits of Magellan, in order to come to a more general conclusion about the role of the pelagic-benthic coupling in structuring littoral benthic communities in southern coastal areas. Few measurements of flux rates and the biochemical composition of the sinking particles occurring in Antarctic and peri-Antarctic shallow waters are available, but a compilation of our own data and others allows a comparison of these two systems. The different environmental conditions between Antarctica and the Straits of Magellan lead to differences in the origin of the particulate organic matter and in its biochemical composition, and consequently in the coupling between pelagic and benthic domains. At Terra Nova Bay the summer particulate matter shows a high labile fraction of a good food value: its flux has been evaluated at about 0.67 g m-2d-1. Conversely, the Straits of Magellan show multi-structured ecosystems where the quality and quantity of the organic matter flux towards the bottom change according to the local geomorphology and current dynamics. Moreover, the three-dimensional assemblages of suspension-feeders, so common in Antarctic shallow waters, seem to be absent in the Magellan area. In particular sponges, gorgonarians and bryozoans play a secondary role inside the Straits of Magellan, where polychaetes (60% and molluscs (9-10% are dominant on soft bottoms, and where they reach high values in density and biomass

  10. Effects of microplastics on European flat oysters, Ostrea edulis and their associated benthic communities.

    Science.gov (United States)

    Green, Dannielle Senga

    2016-09-01

    Plastic pollution is recognised as an emerging threat to aquatic ecosystems, with microplastics now the most abundant type of marine debris. Health effects caused by microplastics have been demonstrated at the species level, but impacts on ecological communities remain unknown. In this study, impacts of microplastics on the health and biological functioning of European flat oysters (Ostrea edulis) and on the structure of associated macrofaunal assemblages were assessed in an outdoor mesocosm experiment using intact sediment cores. Biodegradable and conventional microplastics were added at low (0.8 μg L(-1)) and high (80 μg L(-1)) doses in the water column repeatedly for 60 days. Effects on the oysters were minimal, but benthic assemblage structures differed and species richness and the total number of organisms were ∼1.2 and 1.5 times greater in control mesocosms than in those exposed to high doses of microplastics. Notably, abundances of juvenile Littorina sp. (periwinkles) and Idotea balthica (an isopod) were ∼2 and 8 times greater in controls than in mesocosms with the high dose of either type of microplastic. In addition, the biomass of Scrobicularia plana (peppery furrow shell clam) was ∼1.5 times greater in controls than in mesocosms with the high dose of microplastics. This work indicates that repeated exposure to high concentrations of microplastics could alter assemblages in an important marine habitat by reducing the abundance of benthic fauna. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Community shelter use in response to two benthic decapod predators in the Long Island Sound.

    Science.gov (United States)

    Hudson, David M; Reagan, Dugan; Crivello, Joseph F

    2016-01-01

    To investigate community shelter effects of two invasive decapod species, Hemigrapsus sanguineus and Carcinus maenas, in the Long Island Sound (LIS), we deployed artificial shelters in the intertidal and immediate subtidal zones. These consisted of five groups during the summer: a control, a resident H. sanguineus male or female group, and a resident C. maenas male or female group. We quantified utilization of the shelters at 24 h by counting crabs and fish present. We found significant avoidance of H. sanguineus in the field by benthic hermit crabs (Pagurus spp.) and significant avoidance of C. maenas by the seaboard goby (Gobiosoma ginsburgi). The grubby (Myoxocephalus aenaeus) avoided neither treatment, probably since it tends to be a predator of invertebrates. H. sanguineus avoided C. maenas treatments, whereas C. maenas did not avoid any treatment. Seasonal deployments in the subtidal indicated cohabitation of a number of benthic species in the LIS, with peak shelter use corresponding with increased predation and likely reproductive activity in spring and summer for green crabs (C. maenas), hermit crabs (Pagurus spp.), seaboard gobies (G. ginsburgi), and grubbies (Myoxocephalus aenaeus).

  12. Community shelter use in response to two benthic decapod predators in the Long Island Sound

    Directory of Open Access Journals (Sweden)

    David M. Hudson

    2016-07-01

    Full Text Available To investigate community shelter effects of two invasive decapod species, Hemigrapsus sanguineus and Carcinus maenas, in the Long Island Sound (LIS, we deployed artificial shelters in the intertidal and immediate subtidal zones. These consisted of five groups during the summer: a control, a resident H. sanguineus male or female group, and a resident C. maenas male or female group. We quantified utilization of the shelters at 24 h by counting crabs and fish present. We found significant avoidance of H. sanguineus in the field by benthic hermit crabs (Pagurus spp. and significant avoidance of C. maenas by the seaboard goby (Gobiosoma ginsburgi. The grubby (Myoxocephalus aenaeus avoided neither treatment, probably since it tends to be a predator of invertebrates. H. sanguineus avoided C. maenas treatments, whereas C. maenas did not avoid any treatment. Seasonal deployments in the subtidal indicated cohabitation of a number of benthic species in the LIS, with peak shelter use corresponding with increased predation and likely reproductive activity in spring and summer for green crabs (C. maenas, hermit crabs (Pagurus spp., seaboard gobies (G. ginsburgi, and grubbies (Myoxocephalus aenaeus.

  13. Recent changes in estuarine benthic and suprabenthic communities resulting from the development of harbour infrastructure.

    Science.gov (United States)

    Dauvin, J C; Desroy, N; Janson, A L; Vallet, C; Duhamel, S

    2006-01-01

    Using a Before/During/After sampling protocol, the effects of the Le Havre harbour extension, which was started at the end of 2001, on the macrobenthic and suprabenthic communities in the eastern Bay of Seine (English Channel) were examined. As the construction phase has not yet been completed, the results presented here reflect only the data collected before and during the operations (September 2000 and 2002 for benthos sampling and March 2001, September 2001, October 2002 and March 2003 for suprabenthos sampling). Although bio-sedimentary changes did occur at the mouth of the Seine river, an analysis of benthic assemblages reveals that the dredging and construction operations do not seem to have influenced assemblage structure or the spatial distribution of organisms. Comparisons of the suprabenthic assemblages at each sampling date indicate that seasonal dynamics was mainly responsible for determining species distribution. We conclude that, 1 year into the harbour management plan, the observed changes in benthic and suprabenthic assemblage abundance do not exceed the range of spatial variability that exists naturally in the Seine estuary. Despite this compensatory actions designed to protect the aquatic habitats and to preserve a sustainable and healthy ecosystem have been added to the infrastructure development plan.

  14. Phanerozoic changes in hardpart availability and utilization in benthic communities: evolutionary ecology or evolutionary stratigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Kidwell, S.M.

    1985-01-01

    Published experiments on modern communities and quantitative data from Miocene assemblages indicate that the accumulation of dead hardparts can drive specific changes in the composition of benthic communities (taphonomic feedback). Both opportunities and pathways of taphonomic feedback have changed over the Phanerozoic, however, owing to the evolution and environmental expansion of hardpart producers, utilizers, and destroyers. These changes were tracked using semi-quantitative estimates of hardpart availability based on familial diversity of the most abundant taxa, scored according to preservation potential at or near the seafloor. The data suggest a dramatic increase in hardpart availability from the Cambrian into the later Paleozoic, with a decline through the Mesozoic and Cenozoic related to the loss or dramatic reduction in calcitic epifauna, recliners on soft substrata, and large shelled nekton/plankton. The reduction in opportunities for taphonomic feedback among epifauna was accompanied by an increase in levels of infaunal interactions in the Cenozoic, which is characterized by fully three-dimensional shell gravels. In addition to evolutionary change in body sizes of hardpart producers and biotically-driven declines in certain benthic life habits, the change in pathways of taphonomic feedback was also a consequence of the large-scale shift from predominantly carbonate sedimentation in the Paleozoic to predominantly terrigenous sedimentation in the Cenozoic. For example, the waning of epifauna-dominated communities is closely associated with the restriction of level-bottom carbonate environments through the late Mesozoic and Cenozoic. The global evolution of sedimentary environments and their relative representation is important not only in its consequences for sampling but as a driving mechanism of evolutionary ecology of marine benthos.

  15. The gut microbial community of Midas cichlid fish in repeatedly evolved limnetic-benthic species pairs.

    Science.gov (United States)

    Franchini, Paolo; Fruciano, Carmelo; Frickey, Tancred; Jones, Julia C; Meyer, Axel

    2014-01-01

    Gut bacterial communities are now known to influence a range of fitness related aspects of organisms. But how different the microbial community is in closely related species, and if these differences can be interpreted as adaptive is still unclear. In this study we compared microbial communities in two sets of closely related sympatric crater lake cichlid fish species pairs that show similar adaptations along the limnetic-benthic axis. The gut microbial community composition differs in the species pair inhabiting the older of two crater lakes. One major difference, relative to other fish, is that in these cichlids that live in hypersaline crater lakes, the microbial community is largely made up of Oceanospirillales (52.28%) which are halotolerant or halophilic bacteria. This analysis opens up further avenues to identify candidate symbiotic or co-evolved bacteria playing a role in adaptation to similar diets and life-styles or even have a role in speciation. Future functional and phylosymbiotic analyses might help to address these issues.

  16. Inferring community properties of benthic macroinvertebrates in streams using Shannon index and exergy

    Science.gov (United States)

    Nguyen, Tuyen Van; Cho, Woon-Seok; Kim, Hungsoo; Jung, Il Hyo; Kim, YongKuk; Chon, Tae-Soo

    2014-03-01

    Definition of ecological integrity based on community analysis has long been a critical issue in risk assessment for sustainable ecosystem management. In this work, two indices (i.e., Shannon index and exergy) were selected for the analysis of community properties of benthic macroinvertebrate community in streams in Korea. For this purpose, the means and variances of both indices were analyzed. The results found an extra scope of structural and functional properties in communities in response to environmental variabilities and anthropogenic disturbances. The combination of these two parameters (four indices) was feasible in identification of disturbance agents (e.g., industrial pollution or organic pollution) and specifying states of communities. The four-aforementioned parameters (means and variances of Shannon index and exergy) were further used as input data in a self-organizing map for the characterization of water quality. Our results suggested that Shannon index and exergy in combination could be utilized as a suitable reference system and would be an efficient tool for assessment of the health of aquatic ecosystems exposed to environmental disturbances.

  17. Biodiversity and spatial patterns of benthic habitat and associated demersal fish communities at two tropical submerged reef ecosystems

    Science.gov (United States)

    Abdul Wahab, Muhammad Azmi; Radford, Ben; Cappo, Mike; Colquhoun, Jamie; Stowar, Marcus; Depczynski, Martial; Miller, Karen; Heyward, Andrew

    2018-06-01

    Submerged reef ecosystems can be very diverse and may serve as important refugia for shallow-water conspecifics. This study quantified the benthic and fish communities of two proximate, predominantly mesophotic coral ecosystems (MCEs), Glomar Shoal and Rankin Bank, which are geographically isolated from other similar features in the region. Glomar Shoal is identified as a key ecological feature (KEF) in the North West Marine Region of Australia. Multibeam surveys were performed to characterise the seafloor and to derive secondary environmental variables, used to explain patterns in benthic and fish communities. Towed video surveys quantified benthic cover, and stereo baited remote underwater stations were used to survey fish abundance and diversity. Surveys were completed in depths of 20-115 m. The two MCEs exhibited distinct communities; Rankin Bank consistently had higher cover (up to 30×) of benthic taxa across depths, and fish communities that were twice as abundant and 1.5× more diverse than Glomar Shoal. The location of the MCEs, depth and rugosity were most influential in structuring benthic communities. Phototrophic taxa, specifically macroalgae and hard corals, had up to 22 × higher cover at Rankin Bank than at Glomar Shoal and were dominant to 80 m (compared to 60 m at Glomar Shoal), presumably due to greater light penetration (lower turbidity) and lower sand cover at greater depths. The 20% coral cover at Rankin Bank was comparable to that reported for shallow reefs. The cover of sand, hard corals and sponges influenced fish communities, with higher abundance and diversity of fish associated with shallow hard coral habitats. This study demonstrated that the two MCEs were unique within the local context, and when coupled with their geographical isolation and biodiversity, presents compelling support for the additional recognition of Rankin Bank as a KEF.

  18. Benthic macrofauna variations and community structure in Cenomanian cyclic chalk-marl from Southerham Grey Pit, SE England

    DEFF Research Database (Denmark)

    Lauridsen, Bodil Wesenberg; Gale, A. S.; Surlyk, Finn

    2009-01-01

    Cenomanian chalk-marl couplets from England represent the 20 ka Milankovitch precession cycle. Fossil communities from both chalk and marl are identified to test if the orbital fluctuations and the associated changes in substrate lithology and climate exerted any control on the benthic macrofauna...

  19. Interactions Between Hydropeaking and Thermopeaking Waves and Their Effect on the Benthic Community in Flume Simulations

    Science.gov (United States)

    Bruno, M.; Carolli, M.; Maiolini, B.; Siviglia, A.; Zolezzi, G.

    2013-12-01

    M. C. Bruno1*, M. Carolli2, B. Maiolini1, A. Siviglia2, Zolezzi, G.2 1 Fondazione Edmund Mach, Research and Innovation Centre. S. Michele all'Adige, I-38010, Italy 2 Department of Civil, Environmental and Mechanical Engineering, University of Trento, I-38100, Trento, Italy * cristina.bruno@fmach.it In Alpine regions, hydroelectricity generation is a key power source and its ability to quickly respond to short-term changes in energy demand makes it an ideal source to meet the needs of the deregulated energy market. This economic need is reflected in the temporal patterns of dam operations with consequences for the water bodies that receive downstream releases in the form of ';hydropeaking', typically consisting of sharp water releases in river reaches below dams. The unsteadiness related to this highly intermittent phenomenon has cascading effects on both biotic and abiotic river resources. Regulation by dams may also significantly affect the thermal regime of riversespecially in mountain areas, where releases from high-elevation reservoirs are often characterized by a markedly different temperature from that of the receiving body, thus causing also sharp water temperature variations, named ';thermopeaking'. While interacting with external forcing, the hydrodynamic and thermal waves propagate downstream with different celerities and a first phase of mutual overlap is followed by a second phase in which the two waves proceed separately. The asynchronous propagation of the two waves produces two distinct but consecutive impacts on the benthic community. Because it is difficult to disentangle the multiple effects of hydropeaking and thermopeaking on benthic macroinvertebrates in experiments conducted in natural conditions, we conducted our studies in an experimental structure of five steel channels directly fed by an alpine stream, the Fersina, a tributary to the Adige River of northern Italy. We simulated two sets of cold and warm thermopeaking waves, and measured the

  20. Temperature effects on respiration and photosynthesis in three diatom-dominated benthic communities

    DEFF Research Database (Denmark)

    Hancke, Kasper; Glud, R.N.

    2004-01-01

    ABSTRACT: Short-term temperature effects on respiration and photosynthesis were investigated in intact diatom-dominated benthic communities, collected at 2 temperate and 1 high-arctic subtidal sites. Areal rates of total (TOE) and diffusive (DOE) O2 exchange were determined from O2-microsensor....... This can be ascribed to changes in physical and biological controls during resuspension. Gross photosynthesis was measured with the light-dark shift method at the 2 temperate sites. Both areal (Pgross) and volumetric (Pgross,vol) rates increased with temperature to an optimum temperature at 12 and 15°C......, with a Q10 for Pgross of 2.2 and 2.6 for the 2 sites, respectively. The gross photosynthesis response could be categorised as psychrotrophic for both sites and no temperature adaptation was observed between the 2 sites. Our measurements document that temperature stimulates heterotrophic activity more than...

  1. CLASSIFICATION OF BENTHIC BIOCENOSES OF THE LOWLAND RIVER TUDOVKA (TVER REGION, RUSSIA USING COMMUNITY FEATURES

    Directory of Open Access Journals (Sweden)

    M. Schletterer

    2017-01-01

    Full Text Available Within the joint Russian-Austrian monitoring programme “REFCOND_VOLGA (2006 – 20XX”, monitoring sites were established in the headwaters of the Volga (Tver Region. River Tudovka, a right tributary to the Volga River, was included within this monitoring programme as its catchment is partly protected and has only few anthropogenic activities. The monitoring activities include physico-chemical and hydraulic parameters as well as biota with a focus is on benthic organisms (diatoms and macrozoobenthos. In this work, the longitudinal patterns in community structure are classified in the lowland river Tudovka using a novel feature-based approach taken from signal processing theory. The method first clusters field sampling data into longitudinal classes (upper, middle, lower course. Community features based on the relative frequency of individual species occurring per class are then generated. We apply both generative and discriminative classification methods. The application of generative methods provides data models which predict the probability of a new sample to belong to an existing class. In contrast, discriminative approaches search for differences between classes and allocate new data accordingly. Leveraging both methods allows for the creation of stable classifications. On this basis we show how the community features can be used to predict the longitudinal class. The community features approach also allows for a robust cross-comparison of investigation reaches over time. In cases where suitable long-term data set are available, predictive models using this approach can also be developed.

  2. Drivers of temporal beta diversity of a benthic community in a seasonally hypoxic fjord

    Science.gov (United States)

    Chu, Jackson W. F.; Curkan, Curtis; Tunnicliffe, Verena

    2018-04-01

    Global expansion of oxygen-deficient (hypoxic) waters will have detrimental effects on marine life in the Northeast Pacific Ocean (NEP) where some of the largest proportional losses in aerobic habitat are predicted to occur. However, few in situ studies have accounted for the high environmental variability in this region while including natural community-assembly dynamics. Here, we present results from a 14-month deployment of a benthic camera platform tethered to the VENUS cabled observatory in the seasonally hypoxic Saanich Inlet. Our time series continuously recorded natural cycles of deoxygenation and reoxygenation that allowed us to test whether a community from the NEP showed hysteresis in its recovery compared to hypoxia-induced decline, and to address the processes driving temporal beta diversity under variable states of hypoxia. Using high-frequency ecological time series, we reveal (i) differences in the response and recovery of the epibenthic community are rate-limited by recovery of the sessile species assemblage; (ii) both environmental and biological processes influence community assembly patterns at multiple timescales; and (iii) interspecific processes can drive temporal beta diversity in seasonal hypoxia. Ultimately, our results illustrate how different timescale-dependent drivers can influence the response and recovery of a marine habitat under increasing stress from environmental change.

  3. Research regarding the changes that occur in the structure of benthic macro invertebrates communities as a result of anthropogenic activities

    Directory of Open Access Journals (Sweden)

    Anca-Andreea Marin

    2016-05-01

    Full Text Available An important role in the monitoring of the water quality is represented by the benthic macro invertebrates. They are a key component in the transfer of matter and energy in the aquatic ecosystems. In May 2015, 20 quantitative samples of benthic sample were collected at different seasons in the Bega River water. Samples were collected from the upstream, middle and downstream of Timisoara city. The aim of this paper is to identify the changes that occur in the structure of benthic macro invertebrates communities due to anthropogenic activities. Once the identification of  saprobionte organisms has done, it have been performed the density, abundance and frequency of the sample. Based on these values, we can say that the upstream segment waters falls into the category of superior quality compared to the waters of the central segment, especially in the downstream segment.

  4. THE INFLUENCE OF SUBMERGED MACROPHYTES ON SEDIMENTARY DIATOM ASSEMBLAGES(1).

    Science.gov (United States)

    Vermaire, Jesse C; Prairie, Yves T; Gregory-Eaves, Irene

    2011-12-01

    Submerged macrophytes are a central component of lake ecosystems; however, little is known regarding their long-term response to environmental change. We have examined the potential of diatoms as indicators of past macrophyte biomass. We first sampled periphyton to determine whether habitat was a predictor of diatom assemblage. We then sampled 41 lakes in Quebec, Canada, to evaluate whether whole-lake submerged macrophyte biomass (BiomEpiV) influenced surface sediment diatom assemblages. A multivariate regression tree (MRT) was used to construct a semiquantitative model to reconstruct past macrophyte biomass. We determined that periphytic diatom assemblages on macrophytes were significantly different from those on wood and rocks (ANOSIM R = 0.63, P macrophyte, nutrient-limited lakes (BiomEpiV ≥525 μg · L(-1) ; total phosphorus [TP] macrophyte, nutrient-limited lakes (BiomEpiV macrophytes have a significant influence on diatom community structure and that sedimentary diatom assemblages can be used to infer past macrophyte abundance. © 2011 Phycological Society of America.

  5. Richness, biomass, and nutrient content of a wetland macrophyte community affect soil nitrogen cycling in a diversity-ecosystem functioning experiment

    Science.gov (United States)

    Korol, Alicia R.; Ahn, Changwoo; Noe, Gregory

    2016-01-01

    The development of soil nitrogen (N) cycling in created wetlands promotes the maturation of multiple biogeochemical cycles necessary for ecosystem functioning. This development proceeds from gradual changes in soil physicochemical properties and influential characteristics of the plant community, such as competitive behavior, phenology, productivity, and nutrient composition. In the context of a 2-year diversity experiment in freshwater mesocosms (0, 1, 2, 3, or 4 richness levels), we assessed the direct and indirect impacts of three plant community characteristics – species richness, total biomass, and tissue N concentration – on three processes in the soil N cycle – soil net ammonification, net nitrification, and denitrification potentials. Species richness had a positive effect on net ammonification potential (NAP) through higher redox potentials and likely faster microbial respiration. All NAP rates were negative, however, due to immobilization and high rates of ammonium removal. Net nitrification was inhibited at higher species richness without mediation from the measured soil properties. Higher species richness also inhibited denitrification potential through increased redox potential and decreased nitrification. Both lower biomass and/or higher tissue ratios of carbon to nitrogen, characteristics indicative of the two annual plants, were shown to have stimulatory effects on all three soil N processes. The two mediating physicochemical links between the young macrophyte community and microbial N processes were soil redox potential and temperature. Our results suggest that early-successional annual plant communities play an important role in the development of ecosystem N multifunctionality in newly created wetland soils.

  6. Spatial variation in coral reef fish and benthic communities in the central Saudi Arabian Red Sea

    KAUST Repository

    Khalil, Maha T.

    2017-06-06

    Local-scale ecological information is critical as a sound basis for spatial management and conservation and as support for ongoing research in relatively unstudied areas. We conducted visual surveys of fish and benthic communities on nine reefs (3–24 km from shore) in the Thuwal area of the central Saudi Arabian Red Sea. Fish biomass increased with increasing distance from shore, but was generally low compared to reefs experiencing minimal human influence around the world. All reefs had a herbivore-dominated trophic structure and few top predators, such as sharks, jacks, or large groupers. Coral cover was considerably lower on inshore reefs, likely due to a 2010 bleaching event. Community analyses showed inshore reefs to be characterized by turf algae, slower-growing corals, lower herbivore diversity, and highly abundant turf-farming damselfishes. Offshore reefs had more planktivorous fishes, a more diverse herbivore assemblage, and faster-growing corals. All reefs appear to be impacted by overfishing, and inshore reefs seem more vulnerable to thermal bleaching. The study provides a description of the spatial variation in biomass and community structure in the central Saudi Arabian Red Sea and provides a basis for spatial prioritization and subsequent marine protected area design in Thuwal.

  7. Spatial variation in coral reef fish and benthic communities in the central Saudi Arabian Red Sea.

    Science.gov (United States)

    Khalil, Maha T; Bouwmeester, Jessica; Berumen, Michael L

    2017-01-01

    Local-scale ecological information is critical as a sound basis for spatial management and conservation and as support for ongoing research in relatively unstudied areas. We conducted visual surveys of fish and benthic communities on nine reefs (3-24 km from shore) in the Thuwal area of the central Saudi Arabian Red Sea. Fish biomass increased with increasing distance from shore, but was generally low compared to reefs experiencing minimal human influence around the world. All reefs had a herbivore-dominated trophic structure and few top predators, such as sharks, jacks, or large groupers. Coral cover was considerably lower on inshore reefs, likely due to a 2010 bleaching event. Community analyses showed inshore reefs to be characterized by turf algae, slower-growing corals, lower herbivore diversity, and highly abundant turf-farming damselfishes. Offshore reefs had more planktivorous fishes, a more diverse herbivore assemblage, and faster-growing corals . All reefs appear to be impacted by overfishing, and inshore reefs seem more vulnerable to thermal bleaching. The study provides a description of the spatial variation in biomass and community structure in the central Saudi Arabian Red Sea and provides a basis for spatial prioritization and subsequent marine protected area design in Thuwal.

  8. Spatial variation in coral reef fish and benthic communities in the central Saudi Arabian Red Sea

    Directory of Open Access Journals (Sweden)

    Maha T. Khalil

    2017-06-01

    Full Text Available Local-scale ecological information is critical as a sound basis for spatial management and conservation and as support for ongoing research in relatively unstudied areas. We conducted visual surveys of fish and benthic communities on nine reefs (3–24 km from shore in the Thuwal area of the central Saudi Arabian Red Sea. Fish biomass increased with increasing distance from shore, but was generally low compared to reefs experiencing minimal human influence around the world. All reefs had a herbivore-dominated trophic structure and few top predators, such as sharks, jacks, or large groupers. Coral cover was considerably lower on inshore reefs, likely due to a 2010 bleaching event. Community analyses showed inshore reefs to be characterized by turf algae, slower-growing corals, lower herbivore diversity, and highly abundant turf-farming damselfishes. Offshore reefs had more planktivorous fishes, a more diverse herbivore assemblage, and faster-growing corals. All reefs appear to be impacted by overfishing, and inshore reefs seem more vulnerable to thermal bleaching. The study provides a description of the spatial variation in biomass and community structure in the central Saudi Arabian Red Sea and provides a basis for spatial prioritization and subsequent marine protected area design in Thuwal.

  9. Ecological and evolutionary consequences of benthic community stasis in the very deep sea (>1500 m)

    Science.gov (United States)

    Buzas, Martin A.; Hayek, Lee-Ann C.; Culver, Stephen J.; Hayward, Bruce W.; Osterman, Lisa E.

    2014-01-01

    An enigma of deep-sea biodiversity research is that the abyss with its low productivity and densities appears to have a biodiversity similar to that of shallower depths. This conceptualization of similarity is based mainly on per-sample estimates (point diversity, within-habitat, or α-diversity). Here, we use a measure of between-sample within-community diversity (β1H) to examine benthic foraminiferal diversity between 333 stations within 49 communties from New Zealand, the South Atlantic, the Gulf of Mexico, the Norwegian Sea, and the Arctic. The communities are grouped into two depth categories: 200–1500 m and >1500 m. β1H diversity exhibits no evidence of regional differences. Instead, higher values at shallower depths are observed worldwide. At depths of >1500 m the average β1H is zero, indicating stasis or no biodiversity gradient. The difference in β1H-diversity explains why, despite species richness often being greater per sample at deeper depths, the total number of species is greater at shallower depths. The greater number of communities and higher rate of evolution resulting in shorter species durations at shallower depths is also consistent with higher β1H values.

  10. Spatial variation in coral reef fish and benthic communities in the central Saudi Arabian Red Sea

    KAUST Repository

    Khalil, Maha T.; Bouwmeester, Jessica; Berumen, Michael L.

    2017-01-01

    Local-scale ecological information is critical as a sound basis for spatial management and conservation and as support for ongoing research in relatively unstudied areas. We conducted visual surveys of fish and benthic communities on nine reefs (3–24 km from shore) in the Thuwal area of the central Saudi Arabian Red Sea. Fish biomass increased with increasing distance from shore, but was generally low compared to reefs experiencing minimal human influence around the world. All reefs had a herbivore-dominated trophic structure and few top predators, such as sharks, jacks, or large groupers. Coral cover was considerably lower on inshore reefs, likely due to a 2010 bleaching event. Community analyses showed inshore reefs to be characterized by turf algae, slower-growing corals, lower herbivore diversity, and highly abundant turf-farming damselfishes. Offshore reefs had more planktivorous fishes, a more diverse herbivore assemblage, and faster-growing corals. All reefs appear to be impacted by overfishing, and inshore reefs seem more vulnerable to thermal bleaching. The study provides a description of the spatial variation in biomass and community structure in the central Saudi Arabian Red Sea and provides a basis for spatial prioritization and subsequent marine protected area design in Thuwal.

  11. Functional diversity of benthic ciliate communities in response to environmental gradients in a wetland of Yangtze Estuary, China.

    Science.gov (United States)

    Xu, Yuan; Fan, Xinpeng; Warren, Alan; Zhang, Liquan; Xu, Henglong

    2018-02-01

    Researches on the functional diversity of benthic ecosystems have mainly focused on macrofauna, and studies on functional structure of ciliate communities have been based only on trophic- or size-groups. Current research was carried out on the changing patterns of classical and functional diversity of benthic ciliates in response to environmental gradients at three sites in a wetland in Yangtze Estuary. The results showed that changes of environmental factors (e.g. salinity, sediment grain size and hydrodynamic conditions) in the Yangtze Estuary induce variability in species composition and functional trait distribution. Furthermore, increased species richness and diversity did not lead to significant changes in functional diversity due to functional redundancy. However, salt water intrusion of Yangtze Estuary during the dry season could cause reduced functional diversity of ciliate communities. Current study provides the first insight into the functional diversity of ciliate communities in response to environmental gradients. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. Fringing reefs exposed to different levels of eutrophication and sedimentation can support similar benthic communities

    International Nuclear Information System (INIS)

    Rouzé, H.; Lecellier, G.; Langlade, M.J.; Planes, S.; Berteaux-Lecellier, V.

    2015-01-01

    Highlights: • We assess anthropogenic pressures on coral reef health. • We present a spatio-temporal survey of environmental parameters as bio-indicators. • Poor water quality (e.g. high turbidity and high sediments) was not correlated with lower coral cover. • Phytoplankton community size-composition and habitat stability were important predictors of coral reef health. - Abstract: Benthic communities are sensitive to anthropogenic disturbances which can result in changes in species assemblages. A spatio-temporal survey of environmental parameters was conducted over an 18-month period on four different fringing reefs of Moorea, French Polynesia, with unusual vs. frequent human pressures. This survey included assessment of biological, chemical, and physical parameters. First, the results showed a surprising lack of a seasonal trend, which was likely obscured by short-term variability in lagoons. More frequent sampling periods would likely improve the evaluation of a seasonal effect on biological and ecological processes. Second, the three reef habitats studied that were dominated by corals were highly stable, despite displaying antagonistic environmental conditions through eutrophication and sedimentation gradients, whereas the reef dominated by macroalgae was relatively unstable. Altogether, our data challenge the paradigm of labelling environmental parameters such as turbidity, sedimentation, and nutrient-richness as stress indicators

  13. Defining thresholds of sustainable impact on benthic communities in relation to fishing disturbance.

    Science.gov (United States)

    Lambert, G I; Murray, L G; Hiddink, J G; Hinz, H; Lincoln, H; Hold, N; Cambiè, G; Kaiser, M J

    2017-07-14

    While the direct physical impact on seabed biota is well understood, no studies have defined thresholds to inform an ecosystem-based approach to managing fishing impacts. We addressed this knowledge gap using a large-scale experiment that created a controlled gradient of fishing intensity and assessed the immediate impacts and short-term recovery. We observed a mosaic of taxon-specific responses at various thresholds. The lowest threshold of significant lasting impact occurred between 1 and 3 times fished and elicited a decrease in abundance of 39 to 70% for some sessile epifaunal organisms (cnidarians, bryozoans). This contrasted with significant increases in abundance and/or biomass of scavenging species (epifaunal echinoderms, infaunal crustaceans) by two to four-fold in areas fished twice and more. In spite of these significant specific responses, the benthic community structure, biomass and abundance at the population level appeared resilient to fishing. Overall, natural temporal variation in community metrics exceeded the effects of fishing in this highly dynamic study site, suggesting that an acute level of disturbance (fished over six times) would match the level of natural variation. We discuss the implications of our findings for natural resources management with respect to context-specific human disturbance and provide guidance for best fishing practices.

  14. Recruitment and Succession in a Tropical Benthic Community in Response to In-Situ Ocean Acidification

    Science.gov (United States)

    Crook, Elizabeth Derse; Kroeker, Kristy J.; Potts, Donald C.; Rebolledo-Vieyra, Mario; Hernandez-Terrones, Laura M.; Paytan, Adina

    2016-01-01

    Ocean acidification is a pervasive threat to coral reef ecosystems, and our understanding of the ecological processes driving patterns in tropical benthic community development in conditions of acidification is limited. We deployed limestone recruitment tiles in low aragonite saturation (Ωarag) waters during an in-situ field experiment at Puerto Morelos, Mexico, and compared them to tiles placed in control zones over a 14-month investigation. The early stages of succession showed relatively little difference in coverage of calcifying organisms between the low Ωarag and control zones. However, after 14 months of development, tiles from the low Ωarag zones had up to 70% less cover of calcifying organisms coincident with 42% more fleshy algae than the controls. The percent cover of biofilm and turf algae was also significantly greater in the low Ωarag zones, while the number of key grazing taxa remained constant. We hypothesize that fleshy algae have a competitive edge over the primary calcified space holders, coralline algae, and that acidification leads to altered competitive dynamics between various taxa. We suggest that as acidification impacts reefs in the future, there will be a shift in community assemblages away from upright and crustose coralline algae toward more fleshy algae and turf, established in the early stages of succession. PMID:26784986

  15. Recruitment and Succession in a Tropical Benthic Community in Response to In-Situ Ocean Acidification.

    Directory of Open Access Journals (Sweden)

    Elizabeth Derse Crook

    Full Text Available Ocean acidification is a pervasive threat to coral reef ecosystems, and our understanding of the ecological processes driving patterns in tropical benthic community development in conditions of acidification is limited. We deployed limestone recruitment tiles in low aragonite saturation (Ωarag waters during an in-situ field experiment at Puerto Morelos, Mexico, and compared them to tiles placed in control zones over a 14-month investigation. The early stages of succession showed relatively little difference in coverage of calcifying organisms between the low Ωarag and control zones. However, after 14 months of development, tiles from the low Ωarag zones had up to 70% less cover of calcifying organisms coincident with 42% more fleshy algae than the controls. The percent cover of biofilm and turf algae was also significantly greater in the low Ωarag zones, while the number of key grazing taxa remained constant. We hypothesize that fleshy algae have a competitive edge over the primary calcified space holders, coralline algae, and that acidification leads to altered competitive dynamics between various taxa. We suggest that as acidification impacts reefs in the future, there will be a shift in community assemblages away from upright and crustose coralline algae toward more fleshy algae and turf, established in the early stages of succession.

  16. Coastal habitats as surrogates for taxonomic, functional and trophic structures of benthic faunal communities.

    Science.gov (United States)

    Törnroos, Anna; Nordström, Marie C; Bonsdorff, Erik

    2013-01-01

    Due to human impact, there is extensive degradation and loss of marine habitats, which calls for measures that incorporate taxonomic as well as functional and trophic aspects of biodiversity. Since such data is less easily quantifiable in nature, the use of habitats as surrogates or proxies for biodiversity is on the rise in marine conservation and management. However, there is a critical gap in knowledge of whether pre-defined habitat units adequately represent the functional and trophic structure of communities. We also lack comparisons of different measures of community structure in terms of both between- (β) and within-habitat (α) variability when accounting for species densities. Thus, we evaluated a priori defined coastal habitats as surrogates for traditional taxonomic, functional and trophic zoobenthic community structure. We focused on four habitats (bare sand, canopy-forming algae, seagrass above- and belowground), all easily delineated in nature and defined through classification systems. We analyzed uni- and multivariate data on species and trait diversity as well as stable isotope ratios of benthic macrofauna. A good fit between habitat types and taxonomic and functional structure was found, although habitats were more similar functionally. This was attributed to within-habitat heterogeneity so when habitat divisions matched the taxonomic structure, only bare sand was functionally distinct. The pre-defined habitats did not meet the variability of trophic structure, which also proved to differentiate on a smaller spatial scale. The quantification of trophic structure using species density only identified an epi- and an infaunal unit. To summarize the results we present a conceptual model illustrating the match between pre-defined habitat types and the taxonomic, functional and trophic community structure. Our results show the importance of including functional and trophic aspects more comprehensively in marine management and spatial planning.

  17. Spatial and temporal changes in benthic communities of the Galician continental shelf after the Prestige oil spill

    International Nuclear Information System (INIS)

    Serrano, Alberto . E-mail aserrano@st.ieo.es; Sanchez, Francisco; Preciado, Izaskun; Parra, Santiago; Frutos, Inmaculada

    2006-01-01

    Two years after the Prestige oil spill (POS) an assessment of the effects on benthic fauna was carried out using the data obtained in five multidisciplinary surveys. Otter trawl, beam trawl, suprabenthic sled and box corer were used to study the main benthic compartments, along eight transects perpendicular to the coastline. Beam trawl was also employed to quantify the amount of tar aggregates on the continental shelf. No significant correlations between tar aggregates and species richness, biomass and diversity of benthic communities were found. This result was corroborated when the role of depth, season, latitude and sediment characteristics was examined by canonical ordination, in which POS-related variables had low influence on spatial distribution patterns. Depth and sediment grain diameter profoundly influence epibenthic communities. Sediment organic content is a third key variable for the infaunal, suprabenthic and lower-sized epibenthic communities, but not for the larger epibenthic communities. Nevertheless, a decrease in the densities of several epibenthic indicators was detected the first year after spill, followed by a noteworthy recovery in 2004. Non-macroscopic toxicity and some oceanographic agents are suggested as possible causes of these shifts

  18. Spatial and temporal changes in benthic communities of the Galician continental shelf after the Prestige oil spill

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, Alberto [Instituto Espanol de Oceanografia, P.O. Box 240, 39080 Santander (Spain)]. E-mail aserrano@st.ieo.es; Sanchez, Francisco [Instituto Espanol de Oceanografia, P.O. Box 240, 39080 Santander (Spain); Preciado, Izaskun [Instituto Espanol de Oceanografia, P.O. Box 240, 39080 Santander (Spain); Parra, Santiago [Instituto Espanol de Oceanografia, P.O. Box 130, 15080 La Coruna (Spain); Frutos, Inmaculada [Instituto Espanol de Oceanografia, P.O. Box 130, 15080 La Coruna (Spain)

    2006-07-01

    Two years after the Prestige oil spill (POS) an assessment of the effects on benthic fauna was carried out using the data obtained in five multidisciplinary surveys. Otter trawl, beam trawl, suprabenthic sled and box corer were used to study the main benthic compartments, along eight transects perpendicular to the coastline. Beam trawl was also employed to quantify the amount of tar aggregates on the continental shelf. No significant correlations between tar aggregates and species richness, biomass and diversity of benthic communities were found. This result was corroborated when the role of depth, season, latitude and sediment characteristics was examined by canonical ordination, in which POS-related variables had low influence on spatial distribution patterns. Depth and sediment grain diameter profoundly influence epibenthic communities. Sediment organic content is a third key variable for the infaunal, suprabenthic and lower-sized epibenthic communities, but not for the larger epibenthic communities. Nevertheless, a decrease in the densities of several epibenthic indicators was detected the first year after spill, followed by a noteworthy recovery in 2004. Non-macroscopic toxicity and some oceanographic agents are suggested as possible causes of these shifts.

  19. Baseline assessment of fish and benthic communities of the Flower Garden Banks (2010 - present) using remotely operated vehicle (ROV) survey methods: 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The proposed work develop baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys will employ...

  20. A survey by Texas A & M University to characterize the principal components of benthic communities over the entire northern Gulf of Mexico, 1999 - 2002 (NODC Accession 0002295)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A research program has been initiated by the Minerals Management Service (Contract No. 1435-01-99-CT-30991)to gain better knowledge of the benthic communities of the...

  1. Baseline characterization of benthic and coral communities of the Flower Garden Banks, Texas from 2010-05-01 to 2012-08-31 (NODC Accession 0124257)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This study utilized ROV photograph transects to quantify benthic habitat and coral communities among the five habitat types (algal nodule, coralline algal reefs,...

  2. A survey to characterize the principal components of benthic communities over the entire northern Gulf of Mexico, 1999 - 2002 (NODC Accession 0002198)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A research program has been initiated by the Minerals Management Service (Contract No.1435-01-99-CT-30991) to gain better knowledge of the benthic communities of the...

  3. A survey to characterize the principal components of benthic communities over the entire northern Gulf of Mexico from 1999 to 2002 (NODC Accession 0002192)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A research program has been initiated by the Minerals Management Service (Contract No. 1435-01-99-CT-30991) to gain better knowledge of the benthic communities of...

  4. A survey by Texas A & M University to characterize the principal components of benthic communities over the entire northern Gulf of Mexico, 1999 - 2002 (NODC Accession 0002193)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A research program has been initiated by the Minerals Management Service (Contract No. 1435-01-99-CT-30991) to gain better knowledge of the benthic communities of...

  5. The effects of a pesticide mixture on aquatic ecosystems differing in trophic status: responses of the macrophyte Myriophyllum spicatum and the periphytic algal community.

    Science.gov (United States)

    Wendt-Rasch, L; Van den Brink, P J; Crum, S J H; Woin, P

    2004-03-01

    The effects of a pesticide mixture (asulam, fluazinam, lambda-cyhalothrin, and metamitron) on aquatic ecosystems were investigated in 20 outdoor aquatic microcosms. Ten of the microcosms simulated mesotrophic aquatic ecosystems dominated by submerged macrophytes (Elodea). The others simulated eutrophic ecosystems with a high Lemna surface coverage (Lemna). This paper describes the fate of the chemicals as well as their effects on the growth of Myriophyllum spicatum and the periphytic algal community. In the Elodea-dominated microcosms significant increase in the biomass and alterations of species composition of the periphytic algae were observed, but no effect on M. spicatum growth could be recorded in response to the treatment. The opposite was found in the Lemna-dominated microcosms, in which decreased growth of M. spicatum was observed but no alterations could be found in the periphytic community. In the Elodea-dominated microcosms the species composition of the periphytic algae diverged from that of the control following treatment with 0.5% spray drift emission of the label-recommended rate (5% for lambda-cyhalothrin), while reduced growth of M. spicatum in the Lemna-dominated microcosms was recorded at 2% drift (20% for lambda-cyhalothrin). This study shows that the structure of the ecosystem influences the final effect of pesticide exposure.

  6. Bottom trawling and oxygen minimum zone influences on continental slope benthic community structure off Vancouver Island (NE Pacific)

    Science.gov (United States)

    De Leo, Fabio C.; Gauthier, Maéva; Nephin, Jessica; Mihály, Steven; Juniper, S. Kim

    2017-03-01

    Understanding responses of benthic ecosystems to cumulative impacts of natural stressors, long-term ocean change and increasing resource exploitation is an emerging area of interest for marine ecologists and environmental managers. Few, if any, studies have quantitatively addressed cumulative effects in the deep sea. We report here on a study from the continental slope off Vancouver Island (Canada) in the northeast Pacific Ocean, where the Oxygen Minimum Zone impinges on seabed habitats that are subjected to widespread bottom trawling, primarily by the fishery for thornyhead (Sebastolobus ssp.). We examined how the benthic megafauna in this area was influenced by varying levels of dissolved oxygen and trawling activity, along a depth gradient that was also likely to shape community composition. Continuous video and sonar records from two ROV surveys (50 linear km total; depth range 300-1400 m) respectively provided data on faunal attributes (composition, abundance and diversity) and the frequency of trawl door marks on the seabed. Faunal and trawl data were compiled in a geo-referenced database along with corresponding dissolved oxygen data, and pooled into 500 m segments for statistical analysis. Trawl mark occurrence peaked between 500 and 1100 m, corresponding to areas of slope subjected to hypoxia (PERMANOVA analyses, with characterizing taxa identified for all three factors. Depth, dissolved oxygen and trawl mark density accounted for 21% to 52% of the variability in benthic community structure according to multiple regression (DISTLM) models. Species richness was highest at intermediate depths and in areas subject to intermediate levels of trawling, and higher under hypoxia than under severe hypoxia. These statistically significant trends demonstrate that the structuring influences of bottom trawling on deep-sea benthic communities can be observed even where communities are being shaped by strong environmental gradients.

  7. Succession in rocky intertidal benthic communities in areas with different pollution levels at Guanabara Bay (RJ-Brazil)

    OpenAIRE

    Breves-Ramos, André; Lavrado, Helena Passeri; Junqueira, Andrea de Oliveira Ribeiro; Silva, Sérgio Henrique Gonçalves da

    2005-01-01

    The aim of this study was to describe and compare the succession of intertidal benthic communities in two areas at Guanabara Bay, RJ, Brazil: Urca, an area submitted to moderated organic pollution and Catalão, an extremely polluted area. Three transects in each area were scraped one month before the beginning of this study in order to evaluate the recruitment (recruitment-treatments). Three other transects were monitored without manipulation (monitoring treatments). Species composition and re...

  8. Flow controls on lowland river macrophytes: a review.

    Science.gov (United States)

    Franklin, Paul; Dunbar, Michael; Whitehead, Paul

    2008-08-01

    We review the current status of knowledge regarding the role that flow parameters play in controlling the macrophyte communities of temperate lowland rivers. We consider both direct and indirect effects and the interaction with other factors known to control macrophyte communities. Knowledge gaps are identified and implications for the management of river systems considered. The main factors and processes controlling the status of macrophytes in lowland rivers are velocity (hence also discharge), light, substrate, competition, nutrient status and river management practices. We suggest that whilst the characteristics of any particular macrophyte community reflect the integral effects of a combination of the factors, fundamental importance can be attributed to the role of discharge and velocity in controlling instream macrophyte colonisation, establishment and persistence. Velocity and discharge also appear to control the relative influence of some of the other controlling factors. Despite the apparent importance of velocity in determining the status of macrophyte communities in lowland rivers, relatively little is understood about the nature of the processes controlling this relationship. Quantitative knowledge is particularly lacking. Consequently, the ability to predict macrophyte abundance and distribution in rivers is still limited. This is further complicated by the likely existence of feedback effects between the growth of macrophytes and velocity. Demand for water resources increases the pressure on lowland aquatic ecosystems. Despite growing recognition of the need to allocate water for the needs of instream biota, the inability to assess the flow requirements of macrophyte communities limits the scope to achieve this. This increases the likelihood of overexploitation of the water resource as other users, whose demands are quantifiable, are prioritised.

  9. Comparing macrophyte herbivory by introduced Louisiana crayfish ...

    African Journals Online (AJOL)

    The omnivorous Louisiana crayfish, Procambarus clarkii, has caused significant changes to macrophyte communities worldwide and may have similar negative effects in Kenya if used as a biological control agent for snails harbouring human schistosomes. Here we examine how herbivory by the introduced Louisiana ...

  10. Long-Term Benthic Macroinvertebrate Community Monitoring to Assess Pollution Abatement Effectiveness

    Energy Technology Data Exchange (ETDEWEB)

    Smith, John G [ORNL; Brandt, Craig C [ORNL; Christensen, Sigurd W [ORNL

    2011-01-01

    The benthic macroinvertebrate community of East Fork Poplar Creek (EFPC) in East Tennessee was monitored for 18 years to evaluate the effectiveness of a water pollution control program implemented at a major United States (U.S.) Department of Energy facility. Several actions were implemented to reduce and control releases of pollutants into the headwaters of the stream. Four of the most significant actions were implemented during different time periods, which allowed assessment of each action. Macroinvertebrate samples were collected annually in April from three locations in EFPC (EFK24, EFK23, and EFK14) and two nearby reference streams from 1986 through 2003. Significant improvements occurred in the macroinvertebrate community at the headwater sites (EFK24 and EFK23) after implementation of each action, while changes detected 9 km further downstream (EFK14) could not be clearly attributed to any of the actions. Because the stream was impacted at its origin, invertebrate recolonization was primarily limited to aerial immigration, thus, recovery has been slow. As recovery progressed, abundances of small pollution-tolerant taxa (e.g., Orthocladiinae chironomids) decreased and longer lived taxa colonized (e.g., hydropsychid caddisflies, riffle beetles, Baetis). While assessments lasting three to four years may be long enough to detect a response to new pollution controls at highly impacted locations, more time may be needed to understand the full effects. Studies on the effectiveness of pollution controls can be improved if impacted and reference sites are selected to maximize spatial and temporal trending, and if a multidisciplinary approach is used to broadly assess environmental responses (e.g., water quality trends, invertebrate and fish community assessments, toxicity testing, etc.).

  11. PAH effects on meio- and microbial benthic communities strongly depend on bioavailability.

    Science.gov (United States)

    Lindgren, J Fredrik; Hassellöv, Ida-Maja; Dahllöf, Ingela

    2014-01-01

    bioavailability are important to include. In addition, these results add to the understanding that bioavailability measurements of PAHs are a more correct assessment compared to measurements of total PAH concentrations, and need to be included when estimating effects of PAHs in marine benthic communities. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. Diversity and activity of benthic microbial communities at the North Alex mud volcano, Eastern Mediterranean

    Science.gov (United States)

    Makarow, Dorothee; Feseker, Tomas; Schmitz, Ruth; Treude, Tina

    2010-05-01

    North Alex mud volcano, located on the upper slope of the western Nile deep-sea fan, is characterized by an active seepage center transporting pore fluids, hydrocarbons and gases from deep subsurface sources to the sediment-water interface. Surface sediments feature steep temperature gradient of 8.5°C m-1. We sampled the top 40 cm of the sediments at different locations between the center and rim of the mud volcano to study the diversity, activity, and physiological characteristics of benthic microorganisms. The sediments revealed the activity of anaerobic oxidation of methane coupled to sulfate reduction with a mesophilic temperature optimum. Organisms involved in the process include consortia of methanotrophic archaea (ANME-2 group) and an unknown bacterial partner. Besides methanotrophic organisms the sediments harbored a variety of other bacterial and archaeal groups - including potentially thermophilic bacteria that could be involved in sulfur cycling. This poster presentation will provide an overview of microbial activities and community compositions of North Alex mud volcano sediments.

  13. Restoring rocky intertidal communities: Lessons from a benthic macroalgal ecosystem engineer

    International Nuclear Information System (INIS)

    Bellgrove, Alecia; McKenzie, Prudence F.; Cameron, Hayley; Pocklington, Jacqueline B.

    2017-01-01

    As coastal population growth increases globally, effective waste management practices are required to protect biodiversity. Water authorities are under increasing pressure to reduce the impact of sewage effluent discharged into the coastal environment and restore disturbed ecosystems. We review the role of benthic macroalgae as ecosystem engineers and focus particularly on the temperate Australasian fucoid Hormosira banksii as a case study for rocky intertidal restoration efforts. Research focussing on the roles of ecosystem engineers is lagging behind restoration research of ecosystem engineers. As such, management decisions are being made without a sound understanding of the ecology of ecosystem engineers. For successful restoration of rocky intertidal shores it is important that we assess the thresholds of engineering traits (discussed herein) and the environmental conditions under which they are important. - Highlights: • Fucoid algae can be important ecosystem engineers in rocky reef ecosystems • Sewage-effluent disposal negatively affects fucoids and associated communities • Restoring fucoid populations can improve biodiversity of degraded systems • Clarifying the roles of fucoids in ecosystem function can improve restoration efforts • Thresholds of engineering traits and associated environmental conditions important

  14. The effects of a pesticide mixture on aquatic ecosystems differing in trophic status: responses of the macrophyte Myriophyllum spicatum and the periphytic algal community

    NARCIS (Netherlands)

    Wendt-Rasch, L.; Brink, van den P.J.; Crum, S.J.H.; Woin, P.

    2004-01-01

    The effects of a pesticide mixture (asulam, fluazinam, lambda-cyhalothrin, and metamitron) on aquatic ecosystems were investigated in 20 outdoor aquatic microcosms. Ten of the microcosms simulated mesotrophic aquatic ecosystems dominated by submerged macrophytes (Elodea). The others simulated

  15. Linking environmental forcing and trophic supply to benthic communities in the Vercelli Seamount area (Tyrrhenian Sea.

    Directory of Open Access Journals (Sweden)

    Anabella Covazzi Harriague

    Full Text Available Seamounts and their influence on the surrounding environment are currently being extensively debated but, surprisingly, scant information is available for the Mediterranean area. Furthermore, although the deep Tyrrhenian Sea is characterised by a complex bottom morphology and peculiar hydrodynamic features, which would suggest a variable influence on the benthic domain, few studies have been carried out there, especially for soft-bottom macrofaunal assemblages. In order to fill this gap, the structure of the meio-and macrofaunal assemblages of the Vercelli Seamount and the surrounding deep area (northern Tyrrhenian Sea - western Mediterranean were studied in relation to environmental features. Sediment was collected with a box-corer from the seamount summit and flanks and at two far-field sites in spring 2009, in order to analyse the metazoan communities, the sediment texture and the sedimentary organic matter. At the summit station, the heterogeneity of the habitat, the shallowness of the site and the higher trophic supply (water column phytopigments and macroalgal detritus, for instance supported a very rich macrofaunal community, with high abundance, biomass and diversity. In fact, its trophic features resembled those observed in coastal environments next to seagrass meadows. At the flank and far-field stations, sediment heterogeneity and depth especially influenced the meiofaunal distribution. From a trophic point of view, the low content of the valuable sedimentary proteins that was found confirmed the general oligotrophy of the Tyrrhenian Sea, and exerted a limiting influence on the abundance and biomass of the assemblages. In this scenario, the rather refractory sedimentary carbohydrates became a food source for metazoans, which increased their abundance and biomass at the stations where the hydrolytic-enzyme-mediated turnover of carbohydrates was faster, highlighting high lability.

  16. Ecological energetics of benthic communities of an estuarine system of the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A.; Parulekar, A.H.

    An attempt has been made to measure the biomass and quantify the production rates of different size groups of benthic organisms. The average annual production rates of microphytobenthos, meiobenthos and macrobenthos were estimated to be 42.68, 6...

  17. Benthic communities associated with ferromanganese nodules from the Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Pavithran, S.; Goltekar, R.

    for grazers, shelter for burrowers and sessile organisms as well as protection for mobile fauna. It is concluded that benthic organisms like nematodes, polychaetes and foraminiferas may have strong influence on nodule formation and growth....

  18. Environmental impact assessment of benthic community stability in an estuarine complex

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A.; Abidi, S.A.H.

    . There was also a substantial decrease in clam production during the 10 year time under consideration. The implication of ever increasing mining rejects in the estuarine system and the utilization of quantitative benthic parameters in environmental impact studies...

  19. Diagnosis of potential stressors adversely affecting benthic invertebrate communities in Greenwich Bay, Rhode Island, USA

    Science.gov (United States)

    Greenwich Bay is an urbanized embayment of Narragansett Bay potentially impacted by multiple stressors. The present study identified the important stressors affecting Greenwich Bay benthic fauna. First, existing data and information were used to confirm that the waterbody was imp...

  20. Benthic communities at two remote Pacific coral reefs: effects of reef habitat, depth, and wave energy gradients on spatial patterns.

    Science.gov (United States)

    Williams, Gareth J; Smith, Jennifer E; Conklin, Eric J; Gove, Jamison M; Sala, Enric; Sandin, Stuart A

    2013-01-01

    Kingman Reef and Palmyra Atoll in the central Pacific are among the most remote coral reefs on the planet. Here we describe spatial patterns in their benthic communities across reef habitats and depths, and consider these in the context of oceanographic gradients. Benthic communities at both locations were dominated by calcifying organisms (54-86% cover), namely hard corals (20-74%) and crustose coralline algae (CCA) (10-36%). While turf algae were relatively common at both locations (8-22%), larger fleshy macroalgae were virtually absent at Kingman (wave energy, with hard coral cover decreasing and becoming more spatially clustered with increased wave energy, likely as a result of physical damage leading to patches of coral in localized shelter. In contrast, the cover of turf algae at Kingman was positively related to wave energy, reflecting their ability to rapidly colonize newly available space. No significant patterns with wave energy were observed on Palmyra's forereef, suggesting that a more detailed model is required to study biophysical coupling there. Kingman, Palmyra, and other remote oceanic reefs provide interesting case studies to explore biophysical influences on benthic ecology and dynamics.

  1. Benthic O-2 uptake of two cold-water coral communities estimated with the non-invasive eddy correlation technique

    DEFF Research Database (Denmark)

    Rovelli, Lorenzo; Attard, Karl M.; Bryant, Lee D.

    2015-01-01

    , was a channel-like sound in Northern Norway at a depth of 220 m. Both sites were characterized by the presence of live mounds of the reef framework-forming scleractinian Lophelia pertusa and reef-associated fauna such as sponges, crustaceans and other corals. The measured O-2 uptake at the 2 sites varied...... times higher than the global mean for soft sediment communities at comparable depths. The measurements document the importance of CWC communities for local and regional carbon cycling and demonstrate that the EC technique is a valuable tool for assessing rates of benthic O2 uptake in such complex...

  2. Comparative Evaluation of Anaerobic Bacterial Communities Associated with Roots of Submerged Macrophytes Growing in Marine or Brackish Water Sediments

    Science.gov (United States)

    Sediment microbial communities are important for seagrass growth and carbon cycling, however relatively few studies have addressed the composition of prokaryotic communities in seagrass bed sediments. Selective media were used enumerate culturable anaerobic bacteria associated ...

  3. A summary of the benthic-invertebrate and fish-community data from streams in the Indianapolis metropolitan area, Indiana, 1981-2012

    Science.gov (United States)

    Voelker, David C.; Bunch, Aubrey R.; Dobrowolski, Edward G.; Shoda, Megan E.

    2015-01-01

    Intermittently, during 1981–2012, the U.S. Geological Survey sampled sites in the White River and several tributaries in the Indianapolis metropolitan area of Indiana for benthic invertebrates and fish communities. During 1981–87, one study focused on benthic-invertebrate data collection at three sites along the White River. During 1994–96, 21 sites were sampled for benthic invertebrates; after 1999, up to 13 sites were sampled for benthic invertebrates and fish communities. The information collected during these studies was used in conjunction with the Indianapolis Department of Public Works and CWA Authority, Inc., programs to help improve overall health of the White River and its tributaries by reducing combined sewer overflows and other point and non-point sources of pollution in the Indianapolis area.

  4. Aquatic macrophytes in natural and managed wetlands of Rio Grande do Sul State, Southern Brazil Macrófitas aquáticas em áreas úmidas naturais e manejadas do Rio Grande do Sul, sul do Brasil

    OpenAIRE

    Ana Silvia Rolon; Henrique Flores Homem; Leonardo Maltchik

    2010-01-01

    AIM: This study gathers the main results obtained from studies regarding dynamic of aquatic macrophyte community in natural and managed wetlands of Southern Brazil. We analyzed the aquatic macrophytes diversity in wetlands of Southern Brazil, the environmental factors that determine the structure of the aquatic macrophyte community in fragmented wetlands, the effects of floods on the dynamics of macrophytes, and the contributions to the rice field for the conservation of aquatic macrophytes; ...

  5. Assessment of Streamside Management Zones for Conserving Benthic Macroinvertebrate Communities Following Timber Harvest in Eastern Kentucky Headwater Catchments

    Directory of Open Access Journals (Sweden)

    Joshua K. Adkins

    2016-06-01

    Full Text Available Headwater streams generally comprise the majority of stream area in a watershed and can have a strong influence on downstream food webs. Our objective was to determine the effect of altering streamside management zone (SMZ configurations on headwater aquatic insect communities. Timber harvests were implemented within six watersheds in eastern Kentucky. The SMZ configurations varied in width, canopy retention and best management practice (BMP utilization at the watershed scale. Benthic macroinvertebrate samples collected one year before and four years after harvest indicated few differences among treatments, although post-treatment abundance was elevated in some of the treatment streams relative to the unharvested controls. Jaccard index values were similar across SMZ treatments after logging, indicating strong community overlap. These findings suggest that stream invertebrate communities did respond to the timber harvest, though not negatively. Results also suggest that SMZ criteria for aquatic habitats in steeply sloping topography, including at least 50 percent canopy retention and widths of at least 16.8 m, appear to be adequate for protecting benthic macroinvertebrate communities from logging impacts.

  6. Method for assessment and classification of water courses by using the community of aquatic macrophytes; Metodo per la valutazione e la classificazione dei corsi d'acqua utilizzando la comunita delle macrofite acquatiche

    Energy Technology Data Exchange (ETDEWEB)

    Minciardi, M R; Spada, C D; Rossi, G L; Angius, R; Orru, G [Sezione Biologia Ambientale e Conservazione della Natura Centro Ricerche Saluggia, ENEA, Vercelli (Italy); Mancini, L; Pace, G; Mercheggiani, S; Puccinelli, C [Dipt. di ambiente e connessa prevenzione primaria, Istituto Superiore di Sanita, Roma (Italy)

    2009-07-01

    Studies about aquatic macrophytes as bio indicator community in Europe have been carried out since 70s. Efficient macrophytes indices, mainly for the assessment of trophic state, have been defined in nineties. In 2000, WFD includes macrophytes among the ecological quality elements for running waters. To implement Directive 2000/60/C E, European countries had to define methodologies to evaluate the ecological status of water bodies by macrophytes assessment, but almost all Member States continue to use trophic indexes. Researches carried out in Italy during last 10 years confirm the presence and the evaluability in all river types, and the efficiency of macrophytes community as bio indicator. Besides, many European indices have been tested to assess their applicability throughout the country. Particularly, the Index Macrofitique Biologique en Riviere (IBMR), formalized in France in 2003 as trophic index and currently used as french national method, is applicable in Italy. This index not only allows to evaluate the trophic level metric, but can also be used, as proposed in France, as index of ecological status, expressed as distance from the expected trophic state. [Italian] In Europa, sin dagli anni '70, le macrofite acquatiche sono studiate come comunita bioindicatrice. E degli anni '90 la formalizzazione di Indici Macrofitici efficienti, soprattutto nella valutazione dello stato trofico. Nel 2000 la WFD include le macrofite tra gli elementi di qualita' ecologica per le acque correnti. Per il corretto recepimento della Direttiva 2000/60/CE i vari paesi europei hanno dovuto definire metodologie di valutazione stato ecologico dei corpi idrici in funzione dello stato della comunita' macrofitica, ma, in quasi tutti gli Stati membri si e continuato ad utilizzare anche indici macrofitici di stato trofico nell'ambito del monitoraggio dei corpi idrici. Le ricerche condotte in Italia negli ultimi 10 anni confermano la presenza di comunita' significative e valutabili in ogni

  7. BENTHIC MACROINVERTEBRATE COMMUNITY STRUCTURE IN THE UPPER HYDROGRAPHIC BASIN OF CERNA RIVER IN RELATION TO WATER QUALITY (WEST AND SOUTH-WESTERN ROMANIA

    Directory of Open Access Journals (Sweden)

    CORINA TUDORESCU

    2009-01-01

    Full Text Available The quality of an hydrographic basin may be reflected by the composition of benthic macroinvertebrates communities as they can be influenced by the quality degradations of physical and chemical water parameters. The structure of the benthic community in the upper basin of the Cerna river was characterized by the presence of 13 groups. Abundance and frequency values recorded for benthic communities varied according to the physical-chemical conditions specific to each sample collecting station. Plecoptera, Ephemeroptera, Trichoptera and Amphipoda were influenced by changes in water quality, changes that were reflected in the composition and structure of such communities with low levels of abundance, reaching extinction in some areas of the basin.

  8. A workshop model simulating fate and effect of drilling muds and cuttings on benthic communities

    Science.gov (United States)

    Auble, Gregor T.; Andrews, Austin K.; Hamilton, David B.; Roelle, James E.; Shoemaker, Thomas G.

    1984-01-01

    Oil and gas exploration and production at marine sites has generated concern over potential environmental impacts resulting from the discharge of spent drilling muds and cuttings. This concern has led to a broad array of publicly and privately sponsored research. This report described a cooperative modeling effort designed to focus information resulting from this research through construction of explicit equations that simulate the potential impacts of discharge drilling fluids (muds) and cuttings on marine communities. The model is the result of collaboration among more than 30 scientists. The principal cooperating organizations were the E.S. Environmental Protection Agency, the U.S. Minerals Management Service, the Offshore Operators Committee, and the Alaska Oil and Gas Association. The overall simulation model can be conceptualized as three connected submodels: Discharge and Plume Fate, Sediment Redistribution, and Benthic Community Effects. On each day of simulation, these submodels are executed in sequence, with flows of information between submodels. The Benthic Community Effects submodel can be further divided into sections that calculate mortality due to burial, mortality due to toxicity, mortality due to resuspension disturbance, and growth of the community. The model represents a series of seven discrete 1-m2 plots at specified distances along a transect in one direction away from a discharge point. It consists of coupled difference equations for which parameter values can easily be set to evaluate different conditions or to examine the sensitivity of output to various assumptions. Sets of parameter values were developed to represent four general cases or scenarios: (1) a shallow (5 m), cold environment with ice cover during a substantial fraction of the year, such as might be encountered in the Beaufort Sea, Alaska; (2) a shallow (20 m), temperate environment, such as might be encountered in the Gulf of Mexico; (3) a deeper (80 m), temperate environment

  9. An Integrated Approach to Understand Relationships Between Shallow Water Benthic Community Structure and Ecosystem Function

    Science.gov (United States)

    2008-11-01

    REFERENCES Aarnio, K., E. Bonsdorff, and N. Rosenback. 1996. Food and feeding habits of juvenile flounder Platichthys flesus (L.), and turbot...physiological and ecological characteristics of higher taxa, such that crustaceans (especially amphipods and harpacticoid copepods) and echinoderms are...control on benthic processes by feeding on primary producers, bacteria, and detritus. They also serve as major sources of food for higher trophic

  10. EFFECTS OF HURRICANE KATRINA ON BENTHIC MACROINVERTEBRATE COMMUNITIES ALONG THE NORTHERN GULF OF MEXICO COAST

    Science.gov (United States)

    A study was initiated in fall 2005 to assess potential effects on benthic fauna and habitat quality in coastal waters of Louisiana, Mississippi, and Alabama following Hurricane Katrina, which struck the coast of Louisiana, between New Orleans and Bioloxi, Mississippi on August 29...

  11. Benthic-pelagic coupling: effects on nematode communities along southern European continental margins.

    Directory of Open Access Journals (Sweden)

    Ellen Pape

    Full Text Available Along a west-to-east axis spanning the Galicia Bank region (Iberian margin and the Mediterranean basin, a reduction in surface primary productivity and in seafloor flux of particulate organic carbon was mirrored in the in situ organic matter quantity and quality within the underlying deep-sea sediments at different water depths (1200, 1900 and 3000 m. Nematode standing stock (abundance and biomass and genus and trophic composition were investigated to evaluate downward benthic-pelagic coupling. The longitudinal decline in seafloor particulate organic carbon flux was reflected by a reduction in benthic phytopigment concentrations and nematode standing stock. An exception was the station sampled at the Galicia Bank seamount, where despite the maximal particulate organic carbon flux estimate, we observed reduced pigment levels and nematode standing stock. The strong hydrodynamic forcing at this station was believed to be the main cause of the local decoupling between pelagic and benthic processes. Besides a longitudinal cline in nematode standing stock, we noticed a west-to-east gradient in nematode genus and feeding type composition (owing to an increasing importance of predatory/scavenging nematodes with longitude governed by potential proxies for food availability (percentage of nitrogen, organic carbon, and total organic matter. Within-station variability in generic composition was elevated in sediments with lower phytopigment concentrations. Standing stock appeared to be regulated by sedimentation rates and benthic environmental variables, whereas genus composition covaried only with benthic environmental variables. The coupling between deep-sea nematode assemblages and surface water processes evidenced in the present study suggests that it is likely that climate change will affect the composition and function of deep-sea nematodes.

  12. Benthic Community Structure and Sediment Geochemical Properties at Hydrocarbon Seeps Along the Continental Slope of the Western North Atlantic

    Science.gov (United States)

    Demopoulos, A. W.; Bourque, J. R.; Brooke, S.

    2015-12-01

    Hydrocarbon seeps support distinct benthic communities capable of utilizing reduced chemical compounds for nutrition. In recent years, methane seepage has been increasingly documented along the continental slope of the U.S. Atlantic margin. In 2012 and 2013, two seeps were investigated in this region: a shallow site near Baltimore Canyon (410-450 m) and a deep site near Norfolk Canyon (1600 m). Both sites contain extensive mussel beds and microbial mats. Sediment cores and grab samples were collected to quantify the abundance, diversity, and community structure of benthic macrofauna (>300 mm) in relationship to the associated sediment environment (organic carbon and nitrogen, stable isotopes 13C and 15N, grain size, and depth) of mussel beds, mats, and slope habitats. Macrofaunal densities in microbial mats were four times greater than those present in mussel beds and slope sediments. Macrofaunal communities were distinctly different both between depths and among habitat types. Specifically, microbial mat sediments were dominated by the annelid families Dorvilleidae, Capitellidae, and Tubificidae, while mussel habitats had higher proportions of crustaceans. Diversity was lower in Baltimore microbial mat habitats, but higher in mussel and slope sediments compared to Norfolk seep habitats found at deeper depths. Multivariate statistical analysis identified sediment carbon:nitrogen (C:N) ratios and 13C values as important variables for structuring the macrofaunal communities. Higher C:N ratios were present within microbial mat habitats and depleted 13C values occurred in sediments adjacent to mussel beds found in Norfolk Canyon seeps. Differences in the quality and source of organic matter present in the seep habitats are known to be important drivers in macrofaunal community structure and associated food webs. The multivariate analysis provides new insight into the relative importance of the seep sediment quality in supporting dense macrofaunal communities compared

  13. Benthic communities at two remote Pacific coral reefs: effects of reef habitat, depth, and wave energy gradients on spatial patterns

    Directory of Open Access Journals (Sweden)

    Gareth J. Williams

    2013-05-01

    Full Text Available Kingman Reef and Palmyra Atoll in the central Pacific are among the most remote coral reefs on the planet. Here we describe spatial patterns in their benthic communities across reef habitats and depths, and consider these in the context of oceanographic gradients. Benthic communities at both locations were dominated by calcifying organisms (54–86% cover, namely hard corals (20–74% and crustose coralline algae (CCA (10–36%. While turf algae were relatively common at both locations (8–22%, larger fleshy macroalgae were virtually absent at Kingman (<1% and rare at Palmyra (0.7–9.3%. Hard coral cover was higher, but with low diversity, in more sheltered habitats such as Palmyra’s backreef and Kingman’s patch reefs. Almost exclusive dominance by slow-growing Porites on Kingman’s patch reefs provides indirect evidence of competitive exclusion, probably late in a successional sequence. In contrast, the more exposed forereef habitats at both Kingman and Palmyra had higher coral diversity and were characterized by fast-growing corals (e.g., Acropora and Pocillopora, indicative of more dynamic environments. In general at both locations, soft coral cover increased with depth, likely reflecting increasingly efficient heterotrophic abilities. CCA and fleshy macroalgae cover decreased with depth, likely due to reduced light. Cover of other calcified macroalgae, predominantly Halimeda, increased with depth. This likely reflects the ability of many calcifying macroalgae to efficiently harvest light at deeper depths, in combination with an increased nutrient supply from upwelling promoting growth. At Palmyra, patterns of hard coral cover with depth were inconsistent, but cover peaked at mid-depths at Kingman. On Kingman’s forereef, benthic community composition was strongly related to wave energy, with hard coral cover decreasing and becoming more spatially clustered with increased wave energy, likely as a result of physical damage leading to

  14. The Impact of Global Warming and Anoxia on Marine Benthic Community Dynamics: an Example from the Toarcian (Early Jurassic)

    Science.gov (United States)

    Danise, Silvia; Twitchett, Richard J.; Little, Crispin T. S.; Clémence, Marie-Emilie

    2013-01-01

    The Pliensbachian-Toarcian (Early Jurassic) fossil record is an archive of natural data of benthic community response to global warming and marine long-term hypoxia and anoxia. In the early Toarcian mean temperatures increased by the same order of magnitude as that predicted for the near future; laminated, organic-rich, black shales were deposited in many shallow water epicontinental basins; and a biotic crisis occurred in the marine realm, with the extinction of approximately 5% of families and 26% of genera. High-resolution quantitative abundance data of benthic invertebrates were collected from the Cleveland Basin (North Yorkshire, UK), and analysed with multivariate statistical methods to detect how the fauna responded to environmental changes during the early Toarcian. Twelve biofacies were identified. Their changes through time closely resemble the pattern of faunal degradation and recovery observed in modern habitats affected by anoxia. All four successional stages of community structure recorded in modern studies are recognised in the fossil data (i.e. Stage III: climax; II: transitional; I: pioneer; 0: highly disturbed). Two main faunal turnover events occurred: (i) at the onset of anoxia, with the extinction of most benthic species and the survival of a few adapted to thrive in low-oxygen conditions (Stages I to 0) and (ii) in the recovery, when newly evolved species colonized the re-oxygenated soft sediments and the path of recovery did not retrace of pattern of ecological degradation (Stages I to II). The ordination of samples coupled with sedimentological and palaeotemperature proxy data indicate that the onset of anoxia and the extinction horizon coincide with both a rise in temperature and sea level. Our study of how faunal associations co-vary with long and short term sea level and temperature changes has implications for predicting the long-term effects of “dead zones” in modern oceans. PMID:23457537

  15. Archaea Dominate the Ammonia-Oxidizing Community in the Rhizosphere of the Freshwater Macrophyte Littorella uniflora

    DEFF Research Database (Denmark)

    Herrmann, Martina; Saunders, Aaron M.; Schramm, Andreas

    2008-01-01

    Archaeal and bacterial ammonia monooxygenase genes (amoA) had similar low relative abundances in freshwater sediment. In the rhizosphere of the submersed macrophyte Littorella uniflora, archaeal amoA was 500- to >8,000-fold enriched compared to bacterial amoA, suggesting that the enhanced nitrifi...

  16. Effects of organic pollution and physical stress on benthic macroinvertebrate communities from two intermittently closed and open coastal lagoons (ICOLLs)

    Science.gov (United States)

    Coelho, Susana; Pérez-Ruzafa, Angel; Gamito, Sofia

    2015-12-01

    Benthic macroinvertebrate communities and environmental conditions were studied in two intermittently closed and open coastal lakes and lagoons (ICOLLs), located in southern Algarve (Foz do Almargem e Salgados), with the purpose of evaluating the effects of organic pollution, originated mainly from wastewater discharges, and the physical stress caused by the irregular opening of the lagoons. Most of the year, lagoons were isolated from the sea, receiving the freshwater inputs from small rivers and in Salgados, also from the effluents of a wastewater plant. According to environmental and biotic conditions, Foz do Almargem presented a greater marine influence and a lower trophic state (mesotrophic) than Salgados (hypereutrophic). Benthic macroinvertebrate communities in the lagoons were distinct, just as their relations with environmental parameters. Mollusca were the most abundant macroinvertebrates in Foz do Almargem, while Insecta, Oligochaeta and Crustacea were more relevant in Salgados. Corophium multisetosum occurred exclusively in Salgados stations and, just as Chironomus sp., other Insecta and Oligochaeta, densities were positively related to total phosphorus, clay content and chlorophyll a concentration in the sediment, chlorophyll a concentration in water and with total dissolved inorganic nitrogen. Abra segmentum, Cerastoderma glaucum, Peringia ulvae and Ecrobia ventrosa occurred only in Foz do Almargem, with lower values of the above mentioned parameters. Both lagoons were dominated by deposit feeders and taxa tolerant to environmental stress, although in Salgados there was a greater occurrence of opportunistic taxa associated to pronounced unbalanced situations, due to excess organic matter enrichment.

  17. Variable responses of benthic communities to anomalously warm sea temperatures on a high-latitude coral reef.

    Science.gov (United States)

    Bridge, Tom C L; Ferrari, Renata; Bryson, Mitch; Hovey, Renae; Figueira, Will F; Williams, Stefan B; Pizarro, Oscar; Harborne, Alastair R; Byrne, Maria

    2014-01-01

    High-latitude reefs support unique ecological communities occurring at the biogeographic boundaries between tropical and temperate marine ecosystems. Due to their lower ambient temperatures, they are regarded as potential refugia for tropical species shifting poleward due to rising sea temperatures. However, acute warming events can cause rapid shifts in the composition of high-latitude reef communities, including range contractions of temperate macroalgae and bleaching-induced mortality in corals. While bleaching has been reported on numerous high-latitude reefs, post-bleaching trajectories of benthic communities are poorly described. Consequently, the longer-term effects of thermal anomalies on high-latitude reefs are difficult to predict. Here, we use an autonomous underwater vehicle to conduct repeated surveys of three 625 m(2) plots on a coral-dominated high-latitude reef in the Houtman Abrolhos Islands, Western Australia, over a four-year period spanning a large-magnitude thermal anomaly. Quantification of benthic communities revealed high coral cover (>70%, comprising three main morphospecies) prior to the bleaching event. Plating Montipora was most susceptible to bleaching, but in the plot where it was most abundant, coral cover did not change significantly because of post-bleaching increases in branching Acropora. In the other two plots, coral cover decreased while macroalgal cover increased markedly. Overall, coral cover declined from 73% to 59% over the course of the study, while macroalgal cover increased from 11% to 24%. The significant differences in impacts and post-bleaching trajectories among plots underline the importance of understanding the underlying causes of such variation to improve predictions of how climate change will affect reefs, especially at high-latitudes.

  18. Variable responses of benthic communities to anomalously warm sea temperatures on a high-latitude coral reef.

    Directory of Open Access Journals (Sweden)

    Tom C L Bridge

    Full Text Available High-latitude reefs support unique ecological communities occurring at the biogeographic boundaries between tropical and temperate marine ecosystems. Due to their lower ambient temperatures, they are regarded as potential refugia for tropical species shifting poleward due to rising sea temperatures. However, acute warming events can cause rapid shifts in the composition of high-latitude reef communities, including range contractions of temperate macroalgae and bleaching-induced mortality in corals. While bleaching has been reported on numerous high-latitude reefs, post-bleaching trajectories of benthic communities are poorly described. Consequently, the longer-term effects of thermal anomalies on high-latitude reefs are difficult to predict. Here, we use an autonomous underwater vehicle to conduct repeated surveys of three 625 m(2 plots on a coral-dominated high-latitude reef in the Houtman Abrolhos Islands, Western Australia, over a four-year period spanning a large-magnitude thermal anomaly. Quantification of benthic communities revealed high coral cover (>70%, comprising three main morphospecies prior to the bleaching event. Plating Montipora was most susceptible to bleaching, but in the plot where it was most abundant, coral cover did not change significantly because of post-bleaching increases in branching Acropora. In the other two plots, coral cover decreased while macroalgal cover increased markedly. Overall, coral cover declined from 73% to 59% over the course of the study, while macroalgal cover increased from 11% to 24%. The significant differences in impacts and post-bleaching trajectories among plots underline the importance of understanding the underlying causes of such variation to improve predictions of how climate change will affect reefs, especially at high-latitudes.

  19. Benthic communities associated to Thalassia testudinum (Hydrocharitaceae at three localities of Morrocoy National Park, Venezuela

    Directory of Open Access Journals (Sweden)

    Ricardo Bitter - Soto

    1999-09-01

    Full Text Available The benthic community associated with the turtlegrass Thalassia testudinum beds was analized at three localities of Morrocoy National Park, Venezuela. The localities were selected according to their exposure to the open sea : A (protected, B (intermediate and C (exposed. At each locality, a 20 x 20 m area was randomly chosen, delimited and divided into 400 1x1 m quadrats. Inside each, ten randomly selected quadrats/month were sampled during 13 consecutive months. At each site all macroinvertebrates and several physical variables were recorded, as well as leaf and rhizome biomass of T. testudinum. All parameters had a step- wise gradient from A through C: organic matter, carbon nitrogen, oxygen, salinity and temperature gradient was: ABC. Percentages of sand, silt and clay showed an inverse gradient; ASe analizó la comunidad bentónica asociada a Thalassia testudinum y su relación con algunos parámetros bióticos y abióticos, en tres localidades del Parque Nacional Morrocoy, Falcón-Venezuela; éstas fueron seleccionadas de acuerdo al grado de exposición al mar abierto: A(protegída, B (intermedia y C (expuesta. En cada localidad se demarcó un área de 20 x 20m, se muestrearon aleatoriamente 10cuadrantes/mes, (130 cuadrantes/localidad. Se efectuaron registros de oxígeno disuelto, salinidad, temperatura, porcentajes de materia orgánica, carbono y nitrógeno, textura del sedimento, biomasa foliar y de rizoma de T. testudinum. Todos los parámetros analizados presentaron un gradiente escalonado. Materia Orgánica, Carbono y Nitrógeno, Oxígeno disuelto, Salinidad y Temperatura presentaron el gradiente: ABC. Los porcentages de Arena, Limo y Arcilla presentaron un gradiente inverso. El patrón en la Diversidad, Equidad y Dominancia fue: BCA. La fauna colectada estuvo compuesta por los grupos: Coelenterata (Anthozoa, Polichaeta, Sipuncula, Molusca, Crustacea y Echinodermata. Se identificaron 15 especies de moluscos (gastrópodos y bivalvos, (3

  20. Effect of water chemistry on zooplanktonic and microbial communities across freshwater ecotones in different macrophyte-dominated shallow lakes

    Directory of Open Access Journals (Sweden)

    Tomasz Mieczan

    2015-12-01

    Full Text Available Complex interactions between zooplankton and microbial food webs are vital to the ecosystem ecology of shallow lakes. However, little is known about how horizontal changes in environmental conditions may influence microbial and metazoan communities in shallow lakes. The specific goals of the study were i to describe environmental variables responsible for the distribution of bacteria, flagellates, ciliates and crustaceans in an adjacent canal, ecotone and reservoir (littoral-pelagic zone in two different types of lakes (Ceratophyllum-dominated and Potamogeton-dominated lakes; ii to determine whether the contact zone waters differ in hydrochemical and biological terms from the waters of the canal and the open water zone; iii and to evaluate the influence of particular macro-habitats (canal, canal/reservoir, littoral and pelagic zone on the interactions between components of the planktonic food web. We studied four shallow, eutrophic lakes in Polesie Lubelskie (eastern Poland. The highest diversity and abundance of microorganisms and crustaceans were observed in the canal-reservoir contact zone, while the lowest values were noted in the pelagic zone. Hence, the contact zone in the investigated lakes could fulfil the function of an ecotone, distinguished by a significant increase in biodiversity, abundance, and species specificity of micro- and macroorganisms. Weak relations between food web components were found in the Ceratophyllum-dominated lakes, where environmental variables explained the bulk of the total variance in plankton abundance, whereas in the Potamogeton-dominated lakes, where environmental variables had a minor role in the total variance in plankton abundance, strong predator-prey relations were noted. Spatial structure of habitats proved to be another important factor for relationships between food web components, as our study indicated that habitat complexity can reduce negative correlations between food web components. Our study

  1. New climatic targets against global warming: will the maximum 2 °C temperature rise affect estuarine benthic communities?

    Science.gov (United States)

    Crespo, Daniel; Grilo, Tiago Fernandes; Baptista, Joana; Coelho, João Pedro; Lillebø, Ana Isabel; Cássio, Fernanda; Fernandes, Isabel; Pascoal, Cláudia; Pardal, Miguel Ângelo; Dolbeth, Marina

    2017-06-20

    The Paris Agreement signed by 195 countries in 2015 sets out a global action plan to avoid dangerous climate change by limiting global warming to remain below 2 °C. Under that premise, in situ experiments were run to test the effects of 2 °C temperature increase on the benthic communities in a seagrass bed and adjacent bare sediment, from a temperate European estuary. Temperature was artificially increased in situ and diversity and ecosystem functioning components measured after 10 and 30 days. Despite some warmness effects on the analysed components, significant impacts were not verified on macro and microfauna structure, bioturbation or in the fluxes of nutrients. The effect of site/habitat seemed more important than the effects of the warmness, with the seagrass habitat providing more homogenous results and being less impacted by warmness than the adjacent bare sediment. The results reinforce that most ecological responses to global changes are context dependent and that ecosystem stability depends not only on biological diversity but also on the availability of different habitats and niches, highlighting the role of coastal wetlands. In the context of the Paris Agreement it seems that estuarine benthic ecosystems will be able to cope if global warming remains below 2 °C.

  2. Benthic community structure and composition in sediment from the northern Gulf of Mexico shoreline, Texas to Florida

    Science.gov (United States)

    Demopoulos, Amanda W.J.; Strom, Douglas G.

    2012-01-01

    From April 20 through July 15, 2010, approximately 4.93 million barrels of crude oil spilled into the Gulf of Mexico from the British Petroleum Macondo-1 well, representing the largest spill in U.S. waters. Baseline benthic community conditions were assessed from shoreline sediment samples collected from 56 stations within the swash zone (for example, sample depth ranged from 0 to 1.5 feet) along the northern Gulf of Mexico coastline. These sites were selected because they had a high probability of being impacted by the oil. Cores collected at 24 stations contained no sediment infauna. Benthic community metrics varied greatly among the remaining stations. Mississippi stations had the highest mean abundances (38.9 ± 23.9 individuals per 32 square centimeters (cm2); range: 0 to 186), while Texas had the lowest abundances, 4.9 ± 3 individuals per 32 cm2 (range: 0 to 25). Dominant phyla included Annelida, Arthropoda, and Mollusca, but proportional contributions of each group varied by State. Diversity indices Margalef's richness (d) and Shannon-Wiener diversity (H') were highest at Louisiana and Mississippi stations (0.4 and 0.4, for both, respectively) and lowest at Texas (values for both indices were 0.1 ± 0.1). Evenness (J') was low for all the States, ranging from 0.2 to 0.3, indicating a high degree of patchiness at these sites. Across stations within a State, average similarity ranged from 11.1 percent (Mississippi) to 41.1 percent (Louisiana). Low within-state similarity may be a consequence of differing habitat and physical environment conditions. Results provide necessary baseline information that will facilitate future comparisons with post-spill community metrics.

  3. Variation partitioning of diatom species data matrices: Understanding the influence of multiple factors on benthic diatom communities in tropical streams

    Energy Technology Data Exchange (ETDEWEB)

    Bere, Taurai, E-mail: tbere2015@gmail.com; Mangadze, Tinotenda; Mwedzi, Tongai

    2016-10-01

    Elucidating the confounding influence of multiple environmental factors on benthic diatom communities is important in developing water quality predictive models for better guidance of stream management efforts. The objective of this study was to explore the relative impact of metal pollution and hydromorphological alterations in, addition to nutrient enrichment and organic pollution, on diatom taxonomic composition with the view to improve stream diatom-based water quality inference models. Samples were collected twice at 20 sampling stations in the tropical Manyame Catchment, Zimbabwe. Diatom, macroinvertebrate communities and environmental factors were sampled and analysed. The variations in diatom community composition explained by different categories of environmental factors were analysed using canonical correspondence analysis using variance partitioning (partial CCA). The following variations were explained by the different predictor matrices: nutrient levels and organic pollution - 10.4%, metal pollution - 8.3% and hydromorphological factors - 7.9%. Thus, factors other than nutrient levels and organic pollution explain additional significant variation in these diatom communities. Development of diatom-based stream water quality inference models that incorporate metal pollution and hydromorphological alterations, where these are key issues, is thus deemed necessary. - Highlights: • Confounding influences of multiple environmental factors on diatom communities are elucidated. • Variation explained: nutrients + organic pollution - 10.4%, metals - 8.3% and hydromorphological factors - 7.9%. • Calibration of existing or development of new indices may be necessary.

  4. Variation partitioning of diatom species data matrices: Understanding the influence of multiple factors on benthic diatom communities in tropical streams

    International Nuclear Information System (INIS)

    Bere, Taurai; Mangadze, Tinotenda; Mwedzi, Tongai

    2016-01-01

    Elucidating the confounding influence of multiple environmental factors on benthic diatom communities is important in developing water quality predictive models for better guidance of stream management efforts. The objective of this study was to explore the relative impact of metal pollution and hydromorphological alterations in, addition to nutrient enrichment and organic pollution, on diatom taxonomic composition with the view to improve stream diatom-based water quality inference models. Samples were collected twice at 20 sampling stations in the tropical Manyame Catchment, Zimbabwe. Diatom, macroinvertebrate communities and environmental factors were sampled and analysed. The variations in diatom community composition explained by different categories of environmental factors were analysed using canonical correspondence analysis using variance partitioning (partial CCA). The following variations were explained by the different predictor matrices: nutrient levels and organic pollution - 10.4%, metal pollution - 8.3% and hydromorphological factors - 7.9%. Thus, factors other than nutrient levels and organic pollution explain additional significant variation in these diatom communities. Development of diatom-based stream water quality inference models that incorporate metal pollution and hydromorphological alterations, where these are key issues, is thus deemed necessary. - Highlights: • Confounding influences of multiple environmental factors on diatom communities are elucidated. • Variation explained: nutrients + organic pollution - 10.4%, metals - 8.3% and hydromorphological factors - 7.9%. • Calibration of existing or development of new indices may be necessary.

  5. Benthic Community Composition and Seabed Characteristics of a Chukchi Sea Pockmark

    Science.gov (United States)

    MacDonald, I. R.; Bluhm, B.; Iken, K.; Gagaev, S.; Robinson, S.

    2005-12-01

    Several dozen seafloor features were mapped by Larry Mayer and his colleagues using swath bathymetry during a 2003 cruise with the USCGC HEALY near the eastern edge of the Chukchi Plateau (Chukchi Sea 76.6N, 163.9W). These were sub-circular depressions ranging from approximately 250 to over 1000m in width, with depths of up to 50m below the surrounding seabed, and situated in water depths from 500 to 950m. The origin of these features was undetermined, but one possibility was that they were pockmarks formed as a result of gas or fluid expulsion processes. We report here on benthic sampling undertaken at one of these pockmarks on 18 July 2005, also from USCGC HEALY. This elongated feature had maximum water depth of approximately 940m, was 1200m in maximum width, and was depressed approximately 40m below the surrounding seabed. The ocean in the vicinity of the pockmark was heavily ice-covered, which tightly restricted the ship's mobility during sampling operations. We used an ROV to collect and photograph the benthic epifauna during a 6h transit that crossed from the outside of the pockmark to near the center over a distance of 900m. We used a down-looking digital camera to collect over 800 pictures of the benthos at altitudes of 2 to 3m above the seabed. We also collected three cores with a 25x25cm box corer. Our investigations did not provide any direct evidence for gas or fluid flux through the seabed of this feature. Neither did we see any secondary indications of methane flux such as authigenic carbonates or bacterial mats. The abundance and diversity of benthic epifauna at this station was the highest among 8 stations sampled using similar methods during a 30 day cruise. The ROV observed brittle stars, various types of anemones, shrimps, eel pouts, stalked crinoids, benthic ctenophore (likely new species), burrows and mounts, gooseneck barnacles, mysids. Holothurians (c.f. Peneagone sp.) were the single most abundant group and were often photographed in

  6. Spatio-Temporal Patterns in the Coral Reef Communities of the Spermonde Archipelago, 2012–2014, II: Fish Assemblages Display Structured Variation Related to Benthic Condition

    Directory of Open Access Journals (Sweden)

    Jeremiah G. Plass-Johnson

    2018-02-01

    Full Text Available The Spermonde Archipelago is a complex of ~70 mostly populated islands off Southwest Sulawesi, Indonesia, in the center of the Coral Triangle. The reefs in this area are exposed to a high level of anthropogenic disturbances. Previous studies have shown that variation in the benthos is strongly linked to water quality and distance from the mainland. However, little is known about the fish assemblages of the region and if their community structure also follows a relationship with benthic structure and distance from shore. In this study, we used eight islands of the archipelago, varying in distance from 1 to 55 km relative to the mainland, and 3 years of surveys, to describe benthic and fish assemblages and to examine the spatial and temporal influence of benthic composition on the structure of the fish assemblages. Cluster analysis indicated that distinct groups of fish were associated with distance, while few species were present across the entire range of sites. Relating fish communities to benthic composition using a multivariate generalized linear model confirmed that fish groups relate to structural complexity (rugosity or differing benthic groups; either algae, reef builders (coral and crustose coralline algae or invertebrates and rubble. From these relationships we can identify sets of fish species that may be lost given continued degradation of the Spermonde reefs. Lastly, the incorporation of water quality, benthic and fish indices indicates that local coral reefs responded positively after an acute disturbance in 2013 with increases in reef builders and fish diversity over relatively short (1 year time frames. This study contributes an important, missing component (fish community structure to the growing literature on the Spermonde Archipelago, a system that features environmental pressures common in the greater Southeast Asian region.

  7. New insights on the species-specific allelopathic interactions between macrophytes and marine HAB dinoflagellates.

    Directory of Open Access Journals (Sweden)

    Hela Ben Gharbia

    Full Text Available Macrophytes are known to release allelochemicals that have the ability to inhibit the proliferation of their competitors. Here, we investigated the effects of the fresh leaves of two magnoliophytes (Zostera noltei and Cymodocea nodosa and thalli of the macroalgae Ulva rigida on three HAB-forming benthic dinoflagellates (Ostreopsis cf. ovata, Prorocentrum lima, and Coolia monotis. The effects of C. nodosa and U. rigida were also tested against the neurotoxic planktonic dinoflagellate Alexandrium pacificum Litaker sp. nov (former Alexandrium catenella. Co-culture experiments were conducted under controlled laboratory conditions and potential allelopathic effects of the macrophytes on the growth, photosynthesis and toxin production of the targeted dinoflagellates were evaluated. Results showed that U. rigida had the strongest algicidal effect and that the planktonic A. pacificum was the most vulnerable species. Benthic dinoflagellates seemed more tolerant to potential allelochemicals produced by macrophytes. Depending on the dinoflagellate/macrophyte pairs and the weight of leaves/thalli tested, the studied physiological processes were moderately to heavily altered. Our results suggest that the allelopathic activity of the macrophytes could influence the development of HAB species.

  8. New insights on the species-specific allelopathic interactions between macrophytes and marine HAB dinoflagellates.

    Science.gov (United States)

    Ben Gharbia, Hela; Kéfi-Daly Yahia, Ons; Cecchi, Philippe; Masseret, Estelle; Amzil, Zouher; Herve, Fabienne; Rovillon, Georges; Nouri, Habiba; M'Rabet, Charaf; Couet, Douglas; Zmerli Triki, Habiba; Laabir, Mohamed

    2017-01-01

    Macrophytes are known to release allelochemicals that have the ability to inhibit the proliferation of their competitors. Here, we investigated the effects of the fresh leaves of two magnoliophytes (Zostera noltei and Cymodocea nodosa) and thalli of the macroalgae Ulva rigida on three HAB-forming benthic dinoflagellates (Ostreopsis cf. ovata, Prorocentrum lima, and Coolia monotis). The effects of C. nodosa and U. rigida were also tested against the neurotoxic planktonic dinoflagellate Alexandrium pacificum Litaker sp. nov (former Alexandrium catenella). Co-culture experiments were conducted under controlled laboratory conditions and potential allelopathic effects of the macrophytes on the growth, photosynthesis and toxin production of the targeted dinoflagellates were evaluated. Results showed that U. rigida had the strongest algicidal effect and that the planktonic A. pacificum was the most vulnerable species. Benthic dinoflagellates seemed more tolerant to potential allelochemicals produced by macrophytes. Depending on the dinoflagellate/macrophyte pairs and the weight of leaves/thalli tested, the studied physiological processes were moderately to heavily altered. Our results suggest that the allelopathic activity of the macrophytes could influence the development of HAB species.

  9. Microfouling communities from pelagic and benthic marine plastic debris sampled across Mediterranean coastal waters

    Directory of Open Access Journals (Sweden)

    Mercedes Masó

    2016-09-01

    Full Text Available The present study used scanning electron microscopy to characterize the organisms colonizing marine plastic debris collected from pelagic and benthic habitats across Mediterranean coastal waters of Greece, Italy and Spain. A total of 42 fragments of plastic were collected during the COMSOM experimental cruise, 16 from the seafloor and 26 from surface waters. The results showed that diatoms were the most abundant organisms on both pelagic and benthic plastics. The diatom Ceratoneis closterium, frequently observed on surface plastics (73%, is a harmful microalgae associated with mucilage events in the Mediterranean. The abundance of marine plastic in coastal and oceanic waters may provide new habitats that offer an easy substrate for these invasive organisms. Furthermore, the colonization of these new environments might reduce the success of life strategies, or drive the organisms out of their essential habitat by dispersion and rafting phenomena. The results of the present work highlight the need to increase our knowledge of the consequences of colonization of plastics introduced into the marine environment, and the need to raise awareness of the potential impacts of debris accumulation on biodiversity of marine ecosystems.

  10. Metabarcoding of benthic eukaryote communities predicts the ecological condition of estuaries

    International Nuclear Information System (INIS)

    Chariton, Anthony A.; Stephenson, Sarah; Morgan, Matthew J.; Steven, Andrew D.L.; Colloff, Matthew J.; Court, Leon N.; Hardy, Christopher M.

    2015-01-01

    DNA-derived measurements of biological composition have the potential to produce data covering all of life, and provide a tantalizing proposition for researchers and managers. We used metabarcoding to compare benthic eukaryote composition from five estuaries of varying condition. In contrast to traditional studies, we found biotic richness was greatest in the most disturbed estuary, with this being due to the large volume of extraneous material (i.e. run-off from aquaculture, agriculture and other catchment activities) being deposited in the system. In addition, we found strong correlations between composition and a number of environmental variables, including nutrients, pH and turbidity. A wide range of taxa responded to these environmental gradients, providing new insights into their sensitivities to natural and anthropogenic stressors. Metabarcoding has the capacity to bolster current monitoring techniques, enabling the decisions regarding ecological condition to be based on a more holistic view of biodiversity. - Highlights: • We used metabarcoding to examine the benthic eukaryote composition of five estuaries. • Biotic richness (based on MOTUs) was greater in the most impacted estuary. • Similarities among estuaries reflected their environmental condition. • Composition was strongly correlated with nutrients, turbidity and pH. • Metabarcoding can provide fast, comprehensive and ecologically informative data. - Using metabarcoding we were able discriminate benthos from five estuaries, and identify those taxa which responded negatively and positivity to the key environmental stressors

  11. Relations between water physico-chemistry and benthic algal communities in a northern Canadian watershed: defining reference conditions using multiple descriptors of community structure.

    Science.gov (United States)

    Thomas, Kathryn E; Hall, Roland I; Scrimgeour, Garry J

    2015-09-01

    Defining reference conditions is central to identifying environmental effects of anthropogenic activities. Using a watershed approach, we quantified reference conditions for benthic algal communities and their relations to physico-chemical conditions in rivers in the South Nahanni River watershed, NWT, Canada, in 2008 and 2009. We also compared the ability of three descriptors that vary in terms of analytical costs to define algal community structure based on relative abundances of (i) all algal taxa, (ii) only diatom taxa, and (iii) photosynthetic pigments. Ordination analyses showed that variance in algal community structure was strongly related to gradients in environmental variables describing water physico-chemistry, stream habitats, and sub-watershed structure. Water physico-chemistry and local watershed-scale descriptors differed significantly between algal communities from sites in the Selwyn Mountain ecoregion compared to sites in the Nahanni-Hyland ecoregions. Distinct differences in algal community types between ecoregions were apparent irrespective of whether algal community structure was defined using all algal taxa, diatom taxa, or photosynthetic pigments. Two algal community types were highly predictable using environmental variables, a core consideration in the development of Reference Condition Approach (RCA) models. These results suggest that assessments of environmental impacts could be completed using RCA models for each ecoregion. We suggest that use of algal pigments, a high through-put analysis, is a promising alternative compared to more labor-intensive and costly taxonomic approaches for defining algal community structure.

  12. Fertilization of Earth Ponds. III: Effects on Benthic Macro ...

    African Journals Online (AJOL)

    Organic fertilizers in form of cow and chicken manure were applied in oligotrophic or unproductive pond water over a period of one year to stimulate the production of benthic macro invertebrates for the benefit of trout culture, while maintaining adequate water quality. Development of aquatic macrophytes during both ...

  13. The effects of top-down versus bottom-up control on benthic coral reef community structure.

    Science.gov (United States)

    Smith, Jennifer E; Hunter, Cynthia L; Smith, Celia M

    2010-06-01

    While climate change and associated increases in sea surface temperature and ocean acidification, are among the most important global stressors to coral reefs, overfishing and nutrient pollution are among the most significant local threats. Here we examined the independent and interactive effects of reduced grazing pressure and nutrient enrichment using settlement tiles on a coral-dominated reef via long-term manipulative experimentation. We found that unique assemblages developed in each treatment combination confirming that both nutrients and herbivores are important drivers of reef community structure. When herbivores were removed, fleshy algae dominated, while crustose coralline algae (CCA) and coral were more abundant when herbivores were present. The effects of fertilization varied depending on herbivore treatment; without herbivores fleshy algae increased in abundance and with herbivores, CCA increased. Coral recruits only persisted in treatments exposed to grazers. Herbivore removal resulted in rapid changes in community structure while there was a lag in response to fertilization. Lastly, re-exposure of communities to natural herbivore populations caused reversals in benthic community trajectories but the effects of fertilization remained for at least 2 months. These results suggest that increasing herbivore populations on degraded reefs may be an effective strategy for restoring ecosystem structure and function and in reversing coral-algal phase-shifts but that this strategy may be most effective in the absence of other confounding disturbances such as nutrient pollution.

  14. Benthic diatom community response to environmental variables and metal concentrations in a contaminated bay adjacent to Casey Station, Antarctica

    International Nuclear Information System (INIS)

    Cunningham, Laura; Snape, Ian; Stark, Jonathan S.; Riddle, Martin J.

    2005-01-01

    This study examined the effects of anthropogenic contaminants and environmental variables on the composition of benthic diatom communities within a contaminated bay adjacent to an abandoned waste disposal site in Antarctica. The combination of geographical, environmental and chemical data included in the study explained all of the variation observed within the diatom communities. The chemical data, particularly metal concentrations, explained 45.9% of variation in the diatom communities, once the effects of grain-size and spatial structure had been excluded. Of the metals, tin explained the greatest proportion of variation in the diatom communities (28%). Tin was very highly correlated (R 2 > 0.95) with several other variables (copper, iron, lead, and sum of metals), all of which explained similarly high proportions of total variation. Grain-size data explained 23% of variation once the effects of spatial structure and the chemical data had been excluded. The pure spatial component explained only 1.8% of the total variance. The study demonstrates that much of the compositional variability observed in the bay can be explained by concentrations of metal contaminants

  15. Impaired Short-Term Functioning of a Benthic Community from a Deep Norwegian Fjord Following Deposition of Mine Tailings and Sediments

    Directory of Open Access Journals (Sweden)

    Lisa Mevenkamp

    2017-05-01

    Full Text Available The extraction of minerals from land-based mines necessitates the disposal of large amounts of mine tailings. Dumping and storage of tailings into the marine environment, such as fjords, is currently being performed without knowing the potential ecological consequences. This study investigated the effect of short-term exposure to different deposition depths of inert iron ore tailings (0.1, 0.5, and 3 cm and dead subsurface sediment (0.5 and 3 cm on a deep water (200 m fjord benthic assemblage in a microcosm experiment. Biotic and abiotic variables were measured to determine structural and functional changes of the benthic community following an 11 and 16 day exposure with tailings and dead sediment, respectively. Structural changes of macrofauna, meiofauna, and bacteria were measured in terms of biomass, density, community composition and mortality while measures of oxygen penetration depth, sediment community oxygen consumption and 13C-uptake and processing by biota revealed changes in the functioning of the system. Burial with mine tailings and natural sediments modified the structure and functioning of the benthic community albeit in a different way. Mine tailings deposition of 0.1 cm and more resulted in a reduced capacity of the benthic community to remineralize fresh 13C-labeled algal material, as evidenced by the reduced sediment community oxygen consumption and uptake rates in all biological compartments. At 3 cm of tailings deposition, it was evident that nematode mortality was higher inside the tailings layer, likely caused by reduced food availability. In contrast, dead sediment addition led to an increase in oxygen consumption and bacterial carbon uptake comparable to control conditions, thereby leaving deeper sediment layers anoxic and in turn causing nematode mortality at 3 cm deposition. This study clearly shows that even small levels (0.1 cm of instantaneous burial by mine tailings may significantly reduce benthic ecosystem

  16. Assessment of sediment metal contamination in the Mar Menor coastal lagoon (SE Spain: Metal distribution, toxicity, bioaccumulation and benthic community structure

    Directory of Open Access Journals (Sweden)

    2005-01-01

    Full Text Available The Mar Menor coastal lagoon is one of the largest of the Mediterranean Sea. Ancient mining activities in the mountains near its southern basin have resulted in metal contamination in the sediment. The metal bioavailability of these sediments was determined through laboratory toxicity bioassays using three Mediterranean sea urchin species and two amphipod species, and by means of field bioaccumulation measurements involving the seagrass Cymodocea nodosa. The effect of sediment metal contamination on benthic communities was assessed through benthic infaunal analyses, applying classical descriptive parameters and multivariate techniques. The sediments affected by the mining activities presented high levels of toxicity and metals were also accumulated in the seagrass tissues, pointing to metal bioavailability. Although the classical benthic indices were not clear indicators of disturbance, the multivariate techniques applied provided more consistent conclusions.

  17. WATER QUALITY EVALUATION OF CRIŞUL ALB AND CRIŞUL NEGRU RIVERS CATCHMENTS, FROM CODRU-MOMA MOUNTAINS (WEST OF ROMANIA, USING BENTHIC INVERTEBRATES COMMUNITIES

    Directory of Open Access Journals (Sweden)

    Andreea VARGA

    2010-01-01

    Full Text Available Water quality evaluation of the two watersheds involved the collection of thirteen samples from the tributaries of Crişul Alb and Crişul Negru rivers. The samples were collected in june 2010 with a benthic net, which had the mesh size of 250 µm, by disturbing the substrate, being thus qualitative samples. To get an overview, a series of physical-chemical parameters (water temperature, pH, oxygen, conductivity, cyanide, nitrates, nitrites, phosphates was studied in parallel with the study of benthic community. In most of the sampling points the major group of benthic macroinvertebrates were found and in some EPT group (Ephemeroptera, Plecoptera, Trichoptera prevailed even, which is known as a clean freshwater group, sensitive to pollution and human impact.

  18. Spatio-temporal patterns in the coral reef communities of the Spermonde Archipelago, 2012–2014, II: Fish assemblages display structured variation related to benthic condition

    DEFF Research Database (Denmark)

    Plass-Johnson, Jeremiah Grahm; Teichberg, Mirta; Bednarz, Vanessa N.

    2018-01-01

    The Spermonde Archipelago is a complex of ~70 mostly populated islands off Southwest Sulawesi, Indonesia, in the center of the Coral Triangle. The reefs in this area are exposed to a high level of anthropogenic disturbances. Previous studies have shown that variation in the benthos is strongly...... with distance, while few species were present across the entire range of sites. Relating fish communities to benthic composition using a multivariate generalized linear model confirmed that fish groups relate to structural complexity (rugosity) or differing benthic groups; either algae, reef builders (coral...... and crustose coralline algae) or invertebrates and rubble. From these relationships we can identify sets of fish species that may be lost given continued degradation of the Spermonde reefs. Lastly, the incorporation of water quality, benthic and fish indices indicates that local coral reefs responded...

  19. Functional Traits for Carbon Access in Macrophytes.

    Science.gov (United States)

    Stepien, Courtney C; Pfister, Catherine A; Wootton, J Timothy

    2016-01-01

    Understanding functional trait distributions among organisms can inform impacts on and responses to environmental change. In marine systems, only 1% of dissolved inorganic carbon in seawater exists as CO2. Thus the majority of marine macrophytes not only passively access CO2 for photosynthesis, but also actively transport CO2 and the more common bicarbonate (HCO3-, 92% of seawater dissolved inorganic carbon) into their cells. Because species with these carbon concentrating mechanisms (CCMs) are non-randomly distributed in ecosystems, we ask whether there is a phylogenetic pattern to the distribution of CCMs among algal species. To determine macrophyte traits that influence carbon uptake, we assessed 40 common macrophyte species from the rocky intertidal community of the Northeast Pacific Ocean to a) query whether macrophytes have a CCM and b) determine the evolutionary history of CCMs, using ancestral state reconstructions and stochastic character mapping based on previously published data. Thirty-two species not only depleted CO2, but also concentrated and depleted HCO3-, indicative of a CCM. While analysis of CCMs as a continuous trait in 30 families within Phylum Rhodophyta showed a significant phylogenetic signal under a Brownian motion model, analysis of CCMs as a discrete trait (presence or absence) indicated that red algal families are more divergent than expected in their CCM presence or absence; CCMs are a labile trait within the Rhodophyta. In contrast, CCMs were present in each of 18 Ochrophyta families surveyed, indicating that CCMs are highly conserved in the brown algae. The trait of CCM presence or absence was largely conserved within Families. Fifteen of 23 species tested also changed the seawater buffering capacity, or Total Alkalinity (TA), shifting DIC composition towards increasing concentrations of HCO3- and CO2 for photosynthesis. Manipulating the external TA of the local environment may influence carbon availability in boundary layers and

  20. Functional Traits for Carbon Access in Macrophytes

    Science.gov (United States)

    Pfister, Catherine A.; Wootton, J. Timothy

    2016-01-01

    Understanding functional trait distributions among organisms can inform impacts on and responses to environmental change. In marine systems, only 1% of dissolved inorganic carbon in seawater exists as CO2. Thus the majority of marine macrophytes not only passively access CO2 for photosynthesis, but also actively transport CO2 and the more common bicarbonate (HCO3-, 92% of seawater dissolved inorganic carbon) into their cells. Because species with these carbon concentrating mechanisms (CCMs) are non-randomly distributed in ecosystems, we ask whether there is a phylogenetic pattern to the distribution of CCMs among algal species. To determine macrophyte traits that influence carbon uptake, we assessed 40 common macrophyte species from the rocky intertidal community of the Northeast Pacific Ocean to a) query whether macrophytes have a CCM and b) determine the evolutionary history of CCMs, using ancestral state reconstructions and stochastic character mapping based on previously published data. Thirty-two species not only depleted CO2, but also concentrated and depleted HCO3-, indicative of a CCM. While analysis of CCMs as a continuous trait in 30 families within Phylum Rhodophyta showed a significant phylogenetic signal under a Brownian motion model, analysis of CCMs as a discrete trait (presence or absence) indicated that red algal families are more divergent than expected in their CCM presence or absence; CCMs are a labile trait within the Rhodophyta. In contrast, CCMs were present in each of 18 Ochrophyta families surveyed, indicating that CCMs are highly conserved in the brown algae. The trait of CCM presence or absence was largely conserved within Families. Fifteen of 23 species tested also changed the seawater buffering capacity, or Total Alkalinity (TA), shifting DIC composition towards increasing concentrations of HCO3- and CO2 for photosynthesis. Manipulating the external TA of the local environment may influence carbon availability in boundary layers and

  1. Restoring rocky intertidal communities: Lessons from a benthic macroalgal ecosystem engineer.

    Science.gov (United States)

    Bellgrove, Alecia; McKenzie, Prudence F; Cameron, Hayley; Pocklington, Jacqueline B

    2017-04-15

    As coastal population growth increases globally, effective waste management practices are required to protect biodiversity. Water authorities are under increasing pressure to reduce the impact of sewage effluent discharged into the coastal environment and restore disturbed ecosystems. We review the role of benthic macroalgae as ecosystem engineers and focus particularly on the temperate Australasian fucoid Hormosira banksii as a case study for rocky intertidal restoration efforts. Research focussing on the roles of ecosystem engineers is lagging behind restoration research of ecosystem engineers. As such, management decisions are being made without a sound understanding of the ecology of ecosystem engineers. For successful restoration of rocky intertidal shores it is important that we assess the thresholds of engineering traits (discussed herein) and the environmental conditions under which they are important. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Native freshwater species get out of the way: Prussian carp (Carassius gibelio) impacts both fish and benthic invertebrate communities in North America.

    Science.gov (United States)

    Ruppert, Jonathan L W; Docherty, Cassandra; Neufeld, Kenton; Hamilton, Kyle; MacPherson, Laura; Poesch, Mark S

    2017-10-01

    Prussian carp ( Carassius gibelio ) are one of the most noxious non-native species in Eurasia. Recently, Prussian carp, a non-native freshwater fish species, were genetically confirmed in Alberta, Canada and have been rapidly expanding their range in North America since establishment. Given their rapid range expansion, there is an increasing need to determine how Prussian carp may impact native species. We assessed the severity of the Prussian carp invasion by (i) determining their impact on fish communities, (ii) assessing their impact on benthic invertebrate communities, (iii) evaluating if Prussian carp alter abiotic conditions, and (iv) identifying where we find higher abundances of Prussian carp. When Prussian carp were established, we found significant changes to the fish community. Correspondingly, the degree of impact to benthic invertebrate communities was related to the stage of invasion (none, early or recent), where changes in fish communities were significantly concordant with changes in benthic invertebrate communities. Finally, we found that higher abundances of Prussian carp were significantly associated with lower abundances of a majority of native fish species. Altogether, using three lines of evidence, we determine that Prussian carp can have wide-ranging impacts on freshwater ecosystems in North America, pressing the need for management intervention.

  3. Effects of acid mine drainage on water, sediment and associated benthic macroinvertebrate communities

    International Nuclear Information System (INIS)

    Rutherford, L.G.; Cherry, D.S.; Dobbs, M.G.; Cairns, J. Jr.; Zipper, C.E.

    1995-01-01

    The toxic constituents of abandoned mined land (AML) discharges (acidic pH, heavy metals, total suspended solids) are extremely toxic to aquatic life . Studies were undertaken to ascertain environmental impacts to the upper Powell River, Lee and Wise Counties, Va. These impacts included disruptions in physical water quality, sediment quality, altered benthic macroinvertebrate assemblages, and toxicity of the water column and sediments from short-term impairment bioassays, and the potential to bioaccumulate selected metals (Al, Fe, Mn, P, Zn, Cu, Mg, S, Ni, Cd) by periphyton and resident bivalves. Water chemistry and macroinvertebrate assemblages were collected at upstream control, just below acid mine drainage and other downstream sites. Selected trace metal concentrations (Al, Fe, Mn, P, Zn, Cu, Mg, S, Ni, Cd) were determined for water, sediment and resident bivalves using ICP-AES. Acidic pH ranged from 2.15--3.3 at three AML-influenced seeps and varied from 6.4--8.0 at reference stations. At one AML-influenced creek, acidic pH conditions worsened from summer to fall and eradicated aquatic life throughout a 1.5 km stretch of that creek as it flowed into another creek. An additional dilution of 3.4 km in the second creek was needed to nearly neutralize the acidic pH problem. Conductivity (umhos/cm) ranged from 32--278 at reference sites and from 245--4,180 at AML-impact sites. Benthic macroinvertebrate abundance and taxon richness were essentially eliminated in the seeps or reached numbers of 1 -3 taxa totaling < 10 organisms relative to reference areas where richness values were 12--17 and comprised 300--977 organisms. Concentrations of Fe, Al, Mg and Cu and Zn were highest in the environmentally stressed stations of low pH and high conductivity relative to the reference stations. Iron was, by far, the element in highest concentration followed by Al and Mg

  4. Effects of cutting disturbance in Schoenoplectus californicus (C.A. Mey. Soják on the benthic macroinvertebrates - doi: 10.4025/actascibiolsci.v33i1.6383 Effects of cutting disturbance in Schoenoplectus californicus (C.A. Mey. Soják on the benthic macroinvertebrates - doi: 10.4025/actascibiolsci.v33i1.6383

    Directory of Open Access Journals (Sweden)

    Norma Luiza Würdig

    2011-02-01

    Full Text Available Lagoons are considered protected areas because these systems play a key ecological role. However, the extraction of macrophyte Schoenoplectus californicus is held for manufacture of handcrafts, being an alternative income for riverbank communities. This study evaluated the impact of S. californicus experimental cutting on benthic macroinvertebrates trough a field experiment. Macroinvertebrates were sampled at 1, 12, 26 and 60 days after the macrophyte cutting in demarked plots (1 m², as well at control plots. The families number was not statistically different (ANOVA, p > 0.05, but the total density of invertebrates, and the density of Ceratopogonidae were significant (ANOVA, p S. californicus, in this area, as the intensity of the cut held, did not affect considerably the aquatic macroinvertebrates. The results suggest that the small-scale extractivism in these regions carries little effect because the fauna of adjacent areas probably can quickly colonize the disturbed areas.Lagoons are considered protected areas because these systems play a key ecological role. However, the extraction of macrophyte Schoenoplectus californicus is held for manufacture of handcrafts, being an alternative income for riverbank communities. This study evaluated the impact of S. californicus experimental cutting on benthic macroinvertebrates trough a field experiment. Macroinvertebrates were sampled at 1, 12, 26 and 60 days after the macrophyte cutting in demarked plots (1 m², as well at control plots. The families number was not statistically different (ANOVA, p > 0.05, but the total density of invertebrates, and the density of Ceratopogonidae were significant (ANOVA, p S. californicus, in this area, as the intensity of the cut held, did not affect considerably the aquatic macroinvertebrates. The results suggest that the small-scale extractivism in these regions carries little effect because the fauna of adjacent areas probably can quickly colonize the disturbed

  5. Natural products mediating ecological interactions in Antarctic benthic communities: a mini-review of the known molecules.

    Science.gov (United States)

    Núñez-Pons, L; Avila, C

    2015-07-01

    Out of the many bioactive compounds described from the oceans, only a small fraction have been studied for their ecological significance. Similarly, most chemically mediated interactions are not well understood, because the molecules involved remain unrevealed. In Antarctica, this gap in knowledge is even more acute in comparison to tropical or temperate regions, even though polar organisms are also prolific producers of chemical defenses, and pharmacologically relevant products are being reported from the Southern Ocean. The extreme and unique marine environments surrounding Antarctica along with the numerous unusual interactions taking place in benthic communities are expected to select for novel functional secondary metabolites. There is an urgent need to comprehend the evolutionary role of marine derived substances in general, and particularly at the Poles, since molecules of keystone significance are vital in species survival, and therefore, in structuring the communities. Here we provide a mini-review on the identified marine natural products proven to have an ecological function in Antarctic ecosystems. This report recapitulates some of the bibliography from original Antarctic reviews, and updates the new literature in the field from 2009 to the present.

  6. The impact of heavy metal pollution gradients in sediments on benthic macrofauna at population and community levels

    International Nuclear Information System (INIS)

    Ryu, Jongseong; Khim, Jong Seong; Kang, Seong-Gil; Kang, Daeseok; Lee, Chang-hee; Koh, Chul-hwan

    2011-01-01

    The effect of sediment pollution on benthos was investigated in the vicinity of a large sewage treatment outflow at Incheon North Harbor, Korea. Animal size, vertical distribution and standard community parameters were analyzed along a 3 km transect line (n = 7). Univariate parameters showed a general trend of increasing species diversity with increasing distance from the pollution source. Multi-dimensional scaling analysis led to the clear separation of 3 locational groups, supporting gradient-dependent faunal composition. The innermost location was dominated by small sub-surface dwellers while the outer locations by large mid to deep burrowers. Looking for the size-frequency distribution, most abundance species (Heteromastus filiformis) showed the presence of larger size animals with increasing proximity to the pollution source. Meanwhile, species-specific vertical distributions, regardless of the pollution gradient, indicated that such shifts were due to species replacement resulting from a higher tolerance to pollutants over some species. - Highlights: → Hypotheses on benthic responses to sediment pollution were tested. → Decrease of species diversity with the proximity to the pollution source. → Shift of vertical distribution along the transect line attributes to species replacement. → Larger-size species occurred distant from the pollution source. → Larger individuals of Heteromastus filiformis occurred closer to the pollution source. - Community and population level response to the polluted environment of the harbor reflected an integration effect, together with biological interactions.

  7. Identifying community thresholds for lotic benthic diatoms in response to human disturbance.

    Science.gov (United States)

    Tang, Tao; Tang, Ting; Tan, Lu; Gu, Yuan; Jiang, Wanxiang; Cai, Qinghua

    2017-06-23

    Although human disturbance indirectly influences lotic assemblages through modifying physical and chemical conditions, identifying thresholds of human disturbance would provide direct evidence for preventing anthropogenic degradation of biological conditions. In the present study, we used data obtained from tributaries of the Three Gorges Reservoir in China to detect effects of human disturbance on streams and to identify disturbance thresholds for benthic diatoms. Diatom species composition was significantly affected by three in-stream stressors including TP, TN and pH. Diatoms were also influenced by watershed % farmland and natural environmental variables. Considering three in-stream stressors, TP was positively influenced by % farmland and % impervious surface area (ISA). In contrast, TN and pH were principally affected by natural environmental variables. Among measured natural environmental variables, average annual air temperature, average annual precipitation, and topsoil % CaCO 3 , % gravel, and total exchangeable bases had significant effects on study streams. When effects of natural variables were accounted for, substantial compositional changes in diatoms occurred when farmland or ISA land use exceeded 25% or 0.3%, respectively. Our study demonstrated the rationale for identifying thresholds of human disturbance for lotic assemblages and addressed the importance of accounting for effects of natural factors for accurate disturbance thresholds.

  8. Ammonia-oxidizing Bacteria and Archaea in the Rhizosphere of Freshwater Macrophytes

    DEFF Research Database (Denmark)

    Herrmann, Martina; Schramm, Andreas

    2007-01-01

    AMMONIA-OXIDIZING ARCHAEA AND BACTERIA IN THE RHIZOSPHERE OF FRESHWATER MACROPHYTES Martina Herrmann and Andreas Schramm Department of Biological Sciences, Microbiology, University of Aarhus, Denmark Aquatic macrophytes such as Littorella uniflora and Lobelia dortmanna release oxygen from...... their roots and thereby stimulate nitrification and coupled nitrification-denitrification in their rhizosphere. However, oxygen release and inorganic nitrogen concentrations differ markedly between macrophyte species. We therefore propose (i) that the rhizosphere of freshwater macrophytes harbours a species......-specific microbial community distinct from that of unvegetated sediment and (ii) that aquatic macrophytes have an impact on abundance and activity of nitrifying and denitrifying bacteria in freshwater sediment. The goal of this study was to test these hypotheses for the key functional group for coupled nitrification...

  9. Fluoride remediation using floating macrophytes

    Directory of Open Access Journals (Sweden)

    Naba Kumar Mondal

    2014-04-01

    Full Text Available Six aquatic macrophytes, such as Pistia stratiotes, Ceratophyllum demersum, Nymphoides indica, Lemna major, Azolla pinnata,and Eichhornia crassipes were considered for remove fluoride from aqueous solution. Five different concentrations (10, 30, 50, and 100 ppm of fluoride solution were taken in 1 L plastic container. Fixed weight (20 g of macrophytes along with 500 ml fluoride solution was taken in each plastic container for 72 hours observation. Results demonstrated all the macrophytes show highest fluoride removal during 24 h to 48 h, but after 72 h their efficiency reduced drastically. The species N. indica showed better removal efficiency than other experimental macrophytes. In general, pigment measurement data indicated higher concentration at 72 h. However, Pistia sp. showed higher concentration of pigmentation at intermediate time interval (48 h. Higher level of dry weight to fresh weight ratio was recorded for L. major and A. pinnata at all concentrations, excepting at 10 ppm. In addition, all macrophytes showed lower RGR at higher concentration. Isotherm study indicated that macrophyte C. demersum is a good fitted with Freundlich and Langmuir isotherm whereas L. major with Langmuir isotherm during 24 hours.

  10. Replacement of benthic communities in two Neoproterozoic-Cambrian subtropical-to-temperate rift basins, High Atlas and Anti-Atlas, Morocco

    Science.gov (United States)

    Clausen, Sébastien; Álvaro, J. Javier; Zamora, Samuel

    2014-10-01

    The ‘Cambrian explosion’ is often introduced as a major shift in benthic marine communities with a coeval decline of microbial consortia related to the diversification of metazoans and development of bioturbation (‘Agronomic Revolution’). Successive community replacements have been reported along with ecosystem diversification and increase in guild complexity from Neoproterozoic to Cambrian times. This process is recorded worldwide but with regional diachroneities, some of them directly controlled by the geodynamic conditions of sedimentary basins. The southern High Atlas and Anti-Atlas of Morocco record development of two rifts, Tonian (?) - early Cryogenian and latest Ediacarian-Cambrian in age, separated by the onset of the Pan-African Orogeny. This tectonically controlled, regional geodynamic change played a primary control on pattern and timing of benthic ecosystem replacements. Benthic communities include microbial consortia, archaeocyathan-thromboid reefal complexes, chancelloriid-echinoderm-sponge meadows, and deeper offshore echinoderm-dominated communities. Microbial consortia appeared in deeper parts of the Tonian (?) - early Cryogenian fluvio-deltaic progradational rift sequences, lacustrine environments of the Ediacaran Volcanic Atlasic Chain (Ouarzazate Supergroup) and the Ediacaran-Cambrian boundary interval, characterized by the peritidal-dominated Tifnout Member (Adoudou Formation). They persisted and were largely significant until Cambrian Age 3, as previous restricted marine conditions precluded the immigration of shelly metazoans in the relatively shallow epeiric parts of the Cambrian Atlas Rift. Successive Cambrian benthic communities were replaced as a result of distinct hydrodynamic and substrate conditions, which allow identification of biotic (e.g., antagonistic relationships between microbial consortia and echinoderms, and taphonomic feedback patterns in chancelloriid-echinoderm-sponge meadows) and abiotic (e.g., rifting

  11. Oceanographic and topographic conditions structure benthic meiofauna communities in the Weddell Sea, Bransfield Strait and Drake Passage (Antarctic)

    Science.gov (United States)

    Veit-Köhler, Gritta; Durst, Stephan; Schuckenbrock, Jan; Hauquier, Freija; Durán Suja, Laura; Dorschel, Boris; Vanreusel, Ann; Martínez Arbizu, Pedro

    2018-03-01

    The marine environment of the tip of the Antarctic Peninsula is characterised by three oceanographically distinct regions for which we linked continental-slope meiofaunal patterns and environmental drivers on a large scale (100-300 km among ecoregions). Samples for meiofauna communities and sediment analyses were collected with a multicorer, water-column data were derived from water samples and CTD recordings. Meiofauna communities including individuals from 19 higher taxa were compared to a set of 16 environmental variables. We detected significant differences between the communities of Weddell Sea and those of Bransfield Strait and Drake Passage. The amount of phytopigments in the sediment, their freshness and the silt and clay content were driving factors for this separation. The highest meiofauna abundances were found at slopes in the Weddell Sea. Food banks may facilitate high standing stocks. There, the highest ever recorded copepod percentages for the Antarctic were related to the highest phytopigment contents while nematodes were extremely abundant even in deeper sediment layers at stations with fresh organic material. For Bransfield Strait and Drake Passage a sampling scheme of slopes and adjacent troughs was applied. The two regions were divided into three geographical "areas" with the two "habitat" types investigated for each area. Multivariate non-parametric permutational analysis of variance (PERMANOVA) showed that in Bransfield Strait slope and trough meiofauna communities differed significantly in all geographical areas while in Drake Passage this was only the case in the East. These differences were explained best by the regionally and topographically distinct characteristics of 7 out of 11 water-column and sediment-bound factors related to sediment grain size, food quantity and quality, water temperature and salinity. Environmental drivers of the benthic habitat are dependent on large-scale oceanographic conditions and are thus sensitive to changes

  12. Ecological attributes of the benthic community and indices of water quality in urban, rural and preserved environments

    Directory of Open Access Journals (Sweden)

    Claudia Eiko Yoshida

    Full Text Available INTRODUCTION: Reference streams are pristine streams, untouched or unaltered by man, it being possible to use their environmental characteristics as quality threshold values. Besides the organic impacts measured via water quality biological monitoring programs, it has become necessary to evaluate the relationship between alterations in the landscape of streams and surrounding areas and changes in the structure of the macroinvertebrate community; AIM: The objective of the present study was to correlate the changes in the landscape with the ecological attributes of the community and indices of water quality, and to recommend reference condition values for the integrity of streams in the region of Jundiai (SP; METHODS: The benthic fauna were sampled in three urban streams, three rural streams and three preserved streams during July 2010, using a Surber-type sampler. The characteristics of the landscape were evaluated by means of Diversity of Habitat; the community, analyzed for several biodiversity indices, and; the water quality assessed using the indices River-BCI, BMWP-CETEC (CETEC - Science and Technology Center, ASPT and SOMI (SOMI - Serra dos Órgãos Multimetric Index (Serra dos Órgãos is a mountain range national park in the state of Rio de Janeiro; RESULTS: The structure and the composition of the communities varied according to the stream and this was reflected in the values of the biological and environmental quality indices. The best conditions were found in preserved streams, intermediate streams and rural streams while the worst conditions were found in the urban streams. The significant Pearson correlations (r > 0.73 and P < 0.05 between the diversity of habitat index and the ecological and water quality index attributes in the streams of Jundiai demonstrated that diversity of habitat may be a good predictor of the environmental characteristics evaluated.

  13. Distribution and habitat use of the Missouri River and Lower Yellowstone River benthic fishes from 1996 to 1998: A baseline for fish community recovery

    Science.gov (United States)

    Wildhaber, M.L.; Gladish, D.W.; Arab, A.

    2011-01-01

    Past and present Missouri River management practices have resulted in native fishes being identified as in jeopardy. In 1995, the Missouri River Benthic Fishes Study was initiated to provide improved information on Missouri River fish populations and how alterations might affect them. The study produced a baseline against which to evaluate future changes in Missouri River operating criteria. The objective was to evaluate population structure and habitat use of benthic fishes along the entire mainstem Missouri River, exclusive of reservoirs. Here we use the data from this study to provide a recent-past baseline for on-going Missouri River fish population monitoring programmes along with a more powerful method for analysing data containing large percentages of zero values. This is carried out by describing the distribution and habitat use of 21 species of Missouri River benthic fishes based on catch-per-unit area data from multiple gears. We employ a Bayesian zero-inflated Poisson model expanded to include continuous measures of habitat quality (i.e. substrate composition, depth, velocity, temperature, turbidity and conductivity). Along with presenting the method, we provide a relatively complete picture of the Missouri River benthic fish community and the relationship between their relative population numbers and habitat conditions. We demonstrate that our single model provides all the information that is often obtained by a myriad of analytical techniques. An important advantage of the present approach is reliable inference for patterns of relative abundance using multiple gears without using gear efficiencies.

  14. Short-term versus long-term changes in the benthic communities of a small coastal lagoon: implications for ecological status assessment

    OpenAIRE

    Félix, PM; Chainho, P; Costa, Jl; Correia, MJ; Chaves, ML; Medeiros, JP; Cabral, HN; Wouters, N; Bernardo, J; Costa, AM; Cristo, M; Silva, G; Azeda, C; Tavares, P; Costa, MJ

    2013-01-01

    The characteristic high variability and low predictability of coastal lagoons, due to strong changes in marine and freshwater inputs, make these ecosystems an interesting casestudy. The small Melides landlocked coastal lagoon in SW Portugal is a paradigmatic example, with a biological community highly stressed by these phenomena. Benthic macroinvertebrate samples were collected in 1998/99 and 2009 and each year, in different seasons and addressing different environmental conditions i...

  15. Relation of periphyton and benthic invertebrate communities to environmental factors and land use at selected sites in part of the upper Mississippi River basin, 1996-98

    Science.gov (United States)

    ZumBerge, Jeremy Ryan; Lee, Kathy E.; Goldstein, Robert M.

    2003-01-01

    The Upper Mississippi River Basin is one of the hydrologic systems selected for study by the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey. NAWQA utilizes a multi-disciplinary approach to explain factors that affect water quality. Part of the NAWQA design addresses the relation of land use and environmental factors to periphyton and benthic invertebrate communities in streams.

  16. Biogeochemical and microbial variation across 5500 km of Antarctic surface sediment implicates organic matter as a driver of benthic community structure

    Directory of Open Access Journals (Sweden)

    Deric R Learman

    2016-03-01

    Full Text Available Western Antarctica, one of the fastest warming locations on Earth, is a unique environment that is underexplored with regards to biodiversity. Although pelagic microbial communities in the Southern Ocean and coastal Antarctic waters have been well studied, there are fewer investigations of benthic communities and most have a focused geographic range. We sampled surface sediment from 24 sites across a 5,500 km region of Western Antarctica (covering the Ross Sea to the Weddell Sea to examine relationships between microbial communities and sediment geochemistry. Sequencing of the 16S and 18S rRNA genes showed microbial communities in sediments from the Antarctic Peninsula (AP and Western Antarctica (WA, including the Ross, Amundsen, and Bellingshausen Seas, could be distinguished by correlations with organic matter concentrations and stable isotope fractionation (total organic carbon; TOC, nitrogen, and δ13C. Overall, samples from the AP were higher in nutrient content (TOC, nitrogen, and NH4+ and communities in these samples had higher relative abundances of operational taxonomic units (OTUs classified as the diatom, Chaetoceros, a marine cercozoan and four OTUs classified as Cytophaga or Flavobacteria. As these OTUs were strongly correlated with TOC, the data suggests the diatoms could be a source of organic matter and the Bacteroidetes and cercozoan are grazers that consume the organic matter. Additionally, samples from WA have lower nutrients and were dominated by Thaumarchaeota, which could be related to their known ability to thrive as lithotrophs. This study documents the largest analysis of benthic microbial communities to date in the Southern Ocean, representing almost half the continental shoreline of Antarctica, and documents trophic interactions and coupling of pelagic and benthic communities. Our results indicate potential modifications in carbon sequestration processes related to change in community composition, identifying a

  17. Impacts of agricultural irrigation on nearby freshwater ecosystems: the seasonal influence of triazine herbicides in benthic algal communities.

    Science.gov (United States)

    Lorente, Carmen; Causapé, Jesús; Glud, Ronnie N; Hancke, Kasper; Merchán, Daniel; Muñiz, Selene; Val, Jonatan; Navarro, Enrique

    2015-01-15

    A small hydrological basin (Lerma, NE Spain), transformed from its natural state (steppe) to rain-fed agriculture and recently to irrigation agriculture, has been monitored across four seasons of an agricultural year. The goal of this study was to assess how and whether agricultural activities impacted the nearby freshwater ecosystems via runoff. Specifically, we assessed the toxicity of three triazine herbicides, terbuthylazine, atrazine and simazine on the photosynthetic efficiency and structure of algal benthic biofilms (i.e., phototropic periphyton) in the small creek draining the basin. It was expected that the seasonal runoff of the herbicides in the creek affected the sensitivity of the periphyton in accord with the rationale of the Pollution Induced Community Tolerance (PICT): the exposure of the community to pollutants result in the replacement of sensitive species by more tolerant ones. In this way, PICT can serve to establish causal linkages between pollutants and the observed biological impacts. The periphyton presented significantly different sensitivities against terbuthylazine through the year in accord with the seasonal application of this herbicide in the crops nowadays. The sensitivity of already banned herbicides, atrazine and simazine does not display a clear seasonality. The different sensitivities to herbicides were in agreement with the expected exposures scenarios, according to the agricultural calendar, but not with the concentrations measured in water, which altogether indicates that the use of PICT approach may serve for long-term monitoring purposes. That will provide not only causal links between the occurrence of chemicals and their impacts on natural communities, but also information about the occurrence of chemicals that may escape from traditional sampling methods (water analysis). In addition, the EC50 and EC10 of periphyton for terbuthylazine or simazine are the first to be published and can be used for impact assessments

  18. Isonychia spp. and macroinvertebrate community responses to stressors in streams utilizing the benthic in situ toxicity identification evaluation (BiTIE) method

    Energy Technology Data Exchange (ETDEWEB)

    Custer, Kevin W. [Department of Earth and Environmental Sciences, Wright State University, 127 Allyn Hall, 3640 Colonel Glenn Highway, Dayton, OH 45435 (United States)], E-mail: custer.4@wright.edu; Burton, G. Allen [Department of Earth and Environmental Sciences, Wright State University, 127 Allyn Hall, 3640 Colonel Glenn Highway, Dayton, OH 45435 (United States)

    2008-01-15

    Exposures of caged organisms in situ have proven to be a useful way to improve exposure realism and link to stressor effects in aquatic assessments of hazard or risk. A novel cage system, the benthic in situ toxicity identification evaluation (BiTIE), was developed for benthic macroinvertebrates (surrogate species, resident populations and communities) to separate low and high flow effects, and major chemical classes of stressors in streams. Three resin types were used to separate the chemical stressors in the streams Honey Creek and Little Beavercreek, Ohio, USA: Dowex{sup TM} Optipore{sup TM} (non-polar organics), zeolite (ammonia), and polywool (control). Isonychia spp. sensitivity was compared to Chironomus tentans, and no significant differences were found (p > 0.05). Isonychia spp. growth (length) showed a stressor response in the zeolite treatments, and community testing revealed improved metric responses in the Dowex{sup TM} treatments. The BiTIE chamber system demonstrated stressor-response relationships using sublethal and multimetric endpoints. - Use of an indigenous aquatic insect and benthic macroinvertebrate communities allows for discerning the stressors in low and high flows with an in situ TIE approach.

  19. Isonychia spp. and macroinvertebrate community responses to stressors in streams utilizing the benthic in situ toxicity identification evaluation (BiTIE) method

    International Nuclear Information System (INIS)

    Custer, Kevin W.; Burton, G. Allen

    2008-01-01

    Exposures of caged organisms in situ have proven to be a useful way to improve exposure realism and link to stressor effects in aquatic assessments of hazard or risk. A novel cage system, the benthic in situ toxicity identification evaluation (BiTIE), was developed for benthic macroinvertebrates (surrogate species, resident populations and communities) to separate low and high flow effects, and major chemical classes of stressors in streams. Three resin types were used to separate the chemical stressors in the streams Honey Creek and Little Beavercreek, Ohio, USA: Dowex TM Optipore TM (non-polar organics), zeolite (ammonia), and polywool (control). Isonychia spp. sensitivity was compared to Chironomus tentans, and no significant differences were found (p > 0.05). Isonychia spp. growth (length) showed a stressor response in the zeolite treatments, and community testing revealed improved metric responses in the Dowex TM treatments. The BiTIE chamber system demonstrated stressor-response relationships using sublethal and multimetric endpoints. - Use of an indigenous aquatic insect and benthic macroinvertebrate communities allows for discerning the stressors in low and high flows with an in situ TIE approach

  20. Benthic fauna of mangrove environment

    Digital Repository Service at National Institute of Oceanography (India)

    Parulekar, A.H.

    distribution of benthic communities in mangrove environment is governEd. by tidal amplitude, light penetration, nature of substratum and distance from the sea. The littoral zone, neritic zone, Barnacle-oyster zone, Uca zone, Polychaeta zone have been delineated...

  1. Linkages between benthic microbial and feshwater insect communities in degraded peatland ditches

    NARCIS (Netherlands)

    Whatley, M.H.; van Loon, E.E.; Cerli, C.; Vonk, J.A.; van der Geest, H.G.; Admiraal, W.

    2014-01-01

    Many wetlands are heavily modified and identifying the environmental drivers of indicator groups like aquatic insects is complicated by multiple stressors and co-varying environmental factors. Yet, incorporating data from other biological groups, such as microbial communities, potentially reveals

  2. Benthic Macroinvertebrate Communities in the Northern Tributaries of the “Iron Gates” Gorge (Danube River

    Directory of Open Access Journals (Sweden)

    Curtean-Bănăduc Angela

    2014-12-01

    Full Text Available The paper presents the structure of the benthonic macro-invertebrates communities in the Berzasca, Sirinia, Liubcova, and Mraconia rivers. The results are based on quantitative benthos samples (95 samples, collected in July 2014 from 19 sampling stations within the study area. In longitudinal profile, the benthonic macro-invertebrate communities of the Sirinia, Liubcova and Berzasca rivers displays relatively large structural variability, while the communities of the Mraconia River displays smaller structural variability. The structure of the benthonic macro-invertebrate communities correlated with the biotope characteristics indicates the good ecological status of the analysed rivers, with the exception of the Berzasca River sector downstream of the town of Berzasca and immediately upstream of the Danube junction, a sector with moderate ecological status due to negative effects from man-made modifications in the lotic biotope of the sector.

  3. Is benthic food web structure related to diversity of marine macrobenthic communities?

    NARCIS (Netherlands)

    Sokolowski, A.; Wolowicz, M.; Asmus, H.; Asmus, R.; Carlier, A.; Gasiunaite, Z.; Gremare, A.; Hummel, H.; Lesutiene, J.; Razinkovas, A.; Renaud, P.E.; Richard, P.; Kedra, M.

    2012-01-01

    Numerical structure and the organisation of food webs within macrozoobenthic communities has been assessed in the European waters (Svalbard, Barents Sea, Baltic Sea, North Sea, Atlantic Ocean and the Mediterranean Sea) to address the interactions between biodiversity and ecosystem functioning.

  4. Macrophytes as bioindicators of heavy metal pollution in estuarine and coastal environments.

    Science.gov (United States)

    Farias, D R; Hurd, C L; Eriksen, R S; Macleod, C K

    2018-03-01

    The Derwent estuary, in Tasmania (Australia), is highly contaminated with heavy metals with significant levels in both sediments and benthic fauna. However, little is known about metal content in benthic primary producers. We characterized metal content (Arsenic, Cadmium, Copper, Lead, Selenium and Zinc) in twelve species of macrophyte, including red, green, and brown algae, and seagrasses, from the Derwent. The metals, arsenic, copper, lead, and Zinc were detected in all of the macrophytes assessed, but the levels differed between species. Seagrasses accumulated the highest concentrations of all metals; with Zn levels being particularly high in the seagrass Ruppia megacarpa (from the upper Estuary) and Pb was detected in Zostera muelleri (from the middle estuary). Ulva australis was ubiquitous throughout the middle-lower estuary and accumulated Zn in relatively high concentrations. The findings suggest that analysis of multiple species may be necessary for a comprehensive understanding of estuary-wide metal pollution. Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Contribution of sea ice microbial production to Antarctic benthic communities is driven by sea ice dynamics and composition of functional guilds.

    Science.gov (United States)

    Wing, Stephen R; Leichter, James J; Wing, Lucy C; Stokes, Dale; Genovese, Sal J; McMullin, Rebecca M; Shatova, Olya A

    2018-04-28

    Organic matter produced by the sea ice microbial community (SIMCo) is an important link between sea ice dynamics and secondary production in near-shore food webs of Antarctica. Sea ice conditions in McMurdo Sound were quantified from time series of MODIS satellite images for Sept. 1 through Feb. 28 of 2007-2015. A predictable sea ice persistence gradient along the length of the Sound and evidence for a distinct change in sea ice dynamics in 2011 were observed. We used stable isotope analysis (δ 13 C and δ 15 N) of SIMCo, suspended particulate organic matter (SPOM) and shallow water (10-20 m) macroinvertebrates to reveal patterns in trophic structure of, and incorporation of organic matter from SIMCo into, benthic communities at eight sites distributed along the sea ice persistence gradient. Mass-balance analysis revealed distinct trophic architecture among communities and large fluxes of SIMCo into the near-shore food web, with the estimates ranging from 2 to 84% of organic matter derived from SIMCo for individual species. Analysis of patterns in density, and biomass of macroinvertebrate communities among sites allowed us to model net incorporation of organic matter from SIMCo, in terms of biomass per unit area (g/m 2 ), into benthic communities. Here, organic matter derived from SIMCo supported 39 to 71 per cent of total biomass. Furthermore, for six species, we observed declines in contribution of SIMCo between years with persistent sea ice (2008-2009) and years with extensive sea ice breakout (2012-2015). Our data demonstrate the vital role of SIMCo in ecosystem function in Antarctica and strong linkages between sea ice dynamics and near-shore secondary productivity. These results have important implications for our understanding of how benthic communities will respond to changes in sea ice dynamics associated with climate change and highlight the important role of shallow water macroinvertebrate communities as sentinels of change for the Antarctic marine

  6. Benthic Cover

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic cover (habitat) maps are derived from aerial imagery, underwater photos, acoustic surveys, and data gathered from sediment samples. Shallow to moderate-depth...

  7. Benthic foraminifera

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.; Nigam, R.

    (Nolet and Corliss, 1990). Differences in the abundance of oxygen-sensitive and dissolution-prone benthic foraminiferal species between the Last Glacial Maximum (LGM) and the Holocene in the abyssal waters of the southwestern Gulf of Mexico were used... (2009) Deep-sea benthic diversity linked to seasonality of pelagic productivity. Deep Sea Research Part I: Oceanographic Research Papers 56: 835-841. Culver S (1988) New foraminiferal depth zonation of the northwestern Gulf of Mexico. Palaios 3: 69...

  8. The toxic benthic dinoflagellate Ostreopsis ovata: Quantification of proliferation along the coastline of Genoa, Italy

    International Nuclear Information System (INIS)

    Mangialajo, L.; Bertolotto, R.; Cattaneo-Vietti, R.; Chiantore, M.; Grillo, C.; Lemee, R.; Melchiorre, N.; Moretto, P.; Povero, P.; Ruggieri, N.

    2008-01-01

    Toxic harmful algal bloom (HAB) occurrence is becoming more frequent and problematic in highly urbanized coastal zones. In summer 2005 along the urbanized Genoa coastline (Ligurian Sea, North western Mediterranean Sea), local first aid stations treated about 200 people, who all showed similar symptoms following exposure to marine aerosols. The link with proliferation of Ostreopsis ovata was made, and it highlighted for the first time, the risks that benthic HABs may represent in highly urbanised temperate areas. Subsequently, a specific monitoring plan was designed and implemented in the same area in July 2006, before the first signs of Ostreopsis proliferation were detected. Here we report on this quantification of an Ostreopsis ovata bloom in the Ligurian Sea. Cells were quantified both in the water column and in the epiphytic community on macrophytes. Our results suggest a role of sea water temperature and weather conditions in favouring bloom development

  9. In situ effects of titanium dioxide nanoparticles on community structure of freshwater benthic macroinvertebrates.

    Science.gov (United States)

    Jovanović, Boris; Milošević, Djuradj; Piperac, Milica Stojković; Savić, Ana

    2016-06-01

    For the first time in the current literature, the effect of titanium dioxide (TiO2) nanoparticles on the community structure of macroinvertebrates has been investigated in situ. Macroinvertebrates were exposed for 100 days to an environmentally relevant concentration of TiO2 nanoparticles, 25 mg kg(-1) in sediment. Czekanowski's index was 0.61, meaning 39% of the macroinvertebrate community structure was affected by the TiO2 treatment. Non-metric multidimensional scaling (NMDS) visualized the qualitative and quantitative variability of macroinvertebrates at the community level among all samples. A distance-based permutational multivariate analysis of variance (PERMANOVA) revealed the significant effect of TiO2 on the macroinvertebrate community structure. The indicator value analysis showed that the relative frequency and abundance of Planorbarius corneus and Radix labiata were significantly lower in the TiO2 treatment than in the control. Meanwhile, Ceratopogonidae, showed a significantly higher relative frequency and abundance in the TiO2 treatment than in the control. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Long-term divergent tidal flat benthic community recovery following hypoxia-induced mortality

    NARCIS (Netherlands)

    Colen, van C.; Montserrat, F.; Vincx, M.; Herman, P.M.J.; Ysebaert, T.; Degraer, S.

    2010-01-01

    Macrobenthos recovery after hypoxia-induced mass mortality was assessed in an estuarine tidal mudflat during 3 years. During the first 2 years, a Pearson-Rosenberg type of community recovery took place along with the improving bottom water oxygen conditions. After 3 months, spionid polychaetes

  11. Eutrophication induced changes in benthic community structure of a flow-restricted tropical estuary (Cochin backwaters), India

    Digital Repository Service at National Institute of Oceanography (India)

    Martin, G.D.; Nisha, P.A.; Balachandran, K.K.; Madhu, N.V.; Nair, M.; Shaiju, P.; Joseph, T.; Srinivas, K.; Gupta, G.V.M.

    The influence of anthropogenic loading on the distribution of soft bottom benthic organisms of a tropical estuary (Cochin backwaters) was examined. The industrial activities were found to be high in the northern and central part of the estuary...

  12. Benthic megafaunal community structure of cobalt-rich manganese crusts on Necker Ridge

    Science.gov (United States)

    Morgan, Nicole B.; Cairns, Stephen; Reiswig, Henry; Baco, Amy R.

    2015-10-01

    In the North Pacific Ocean, the seamounts of the Hawaiian Archipelago and the Mid-Pacific Mountains are connected by Necker Ridge, a 600 km-long feature spanning a depth range of 1400-4000 m. The Necker Ridge is a part of a large area of the central and western Pacific under consideration for cobalt-rich manganese crust mining. We describe the fauna and community structure of the previously unsampled Necker Ridge based on explorations with the submersible Pisces IV. On five pinnacles and a portion of the Ridge ranging from 1400 to 2000 m deep, 27 transects were recorded using HD video, and voucher specimens were collected to aid in species identification. The video was analyzed to identify and count the megafauna found on each transect and to characterize the substrate. Diversity increased from south to north along the feature. There was a significant difference in community structure between southern and northern pinnacles, with southern pinnacles dominated by crinoids of the Family Charitometridae and northern pinnacles dominated by octocorals, especially the Families Isididae and Chrysogorgiidae. DistLM demonstrated a correlation between community structure on the pinnacles and at least six environmental variables, including latitude, sediment cover, and oxygen concentration, but not including depth. The discontinuous and patchy nature of these distinct megafaunal communities highlights growing evidence that cobalt-rich seamounts are highly heterogeneous habitats, and that managing seamounts may require more complex regulations than treating them as a single ecological unit. These results suggest that extensive community analysis should occur at a given site to determine management priority areas, prior to consideration of that site for exploitation of natural resources.

  13. Benthic communities on hard substrates covered by Limnoperna fortunei Dunker (Bivalvia, Mytilidae at an estuarine beach (Río de la Plata, Argentina

    Directory of Open Access Journals (Sweden)

    Fernando G. Spaccesi

    2012-01-01

    Full Text Available The structure and composition of benthic communities on hard substrates covered by the nonindigenous bivalve Limnoperna fortunei Dunker, the golden mussel, were quantified in the middle zone of the Río de la Plata Estuary (Argentina from April 2001 through March 2002. A total of 26 taxa were recorded. L. fortunei and Nematoda were the central and dominant groups, with a prodigious abundance of over 80%. The prevalence of L. fortunei, rather than the environmental variables, regulated the dynamics of the associated invertebrate fauna. The golden mussel alters both the structure and function of benthic native communities on hard substrates, allows a higher surface available for colonization and refuge, and provides food source to deposit-feeding organisms in the form of organic or residual material. The mussel also increases the abundance and diversity of taxa on hard substrata - such as Oligochaeta, Hirudinea, Tardigrada, Chironomidae, Copepoda, Tanaidacea, and Hydrachnidia. Similarities and nonparametric multidimensional-scaling analyses indicated that the benthic composition had a seasonal variation. L. fortunei has an environmental impact, an ability to invade new freshwater ambiences worldwide and ecological characteristic comparable to those of Dreissena polymorpha Pallas (the zebra mussel of North America and Europe.

  14. Heat waves and their significance for a temperate benthic community: A near-natural experimental approach.

    Science.gov (United States)

    Pansch, Christian; Scotti, Marco; Barboza, Francisco R; Al-Janabi, Balsam; Brakel, Janina; Briski, Elizabeta; Bucholz, Björn; Franz, Markus; Ito, Maysa; Paiva, Filipa; Saha, Mahasweta; Sawall, Yvonne; Weinberger, Florian; Wahl, Martin

    2018-04-23

    Climate change will not only shift environmental means but will also increase the intensity of extreme events, exerting additional stress on ecosystems. While field observations on the ecological consequences of heat waves are emerging, experimental evidence is rare, and lacking at the community level. Using a novel "near-natural" outdoor mesocosms approach, this study tested whether marine summer heat waves have detrimental consequences for macrofauna of a temperate coastal community, and whether sequential heat waves provoke an increase or decrease of sensitivity to thermal stress. Three treatments were applied, defined and characterized through a statistical analysis of 15 years of temperature records from the experimental site: (1) no heat wave, (2) two heat waves in June and July followed by a summer heat wave in August and (3) the summer heat wave only. Overall, 50% of the species showed positive, negative or positive/negative responses in either abundance and/or biomass. We highlight four possible ways in which single species responded to either three subsequent heat waves or one summer heat wave: (1) absence of a response (tolerance, 50% of species), (2) negative accumulative effects by three subsequent heat waves (tellinid bivalve), (3) buffering by proceeding heat waves due to acclimation and/or shifts in phenology (spionid polychaete) and (4) an accumulative positive effect by subsequent heat waves (amphipod). The differential responses to single or sequential heat waves at the species level entailed shifts at the community level. Community-level differences between single and triple heat waves were more pronounced than those between regimes with vs. without heat waves. Detritivory was reduced by the single heat wave while suspension feeding was less common in the triple heat wave regime. Critical extreme events occur already today and will occur more frequently in a changing climate, thus, leading to detrimental impacts on coastal marine systems.

  15. The functional response of a freshwater benthic community to cadmium pollution

    International Nuclear Information System (INIS)

    Faupel, Michael; Ristau, Kai; Traunspurger, Walter

    2012-01-01

    Theory predicts that in freshwater communities under chemical stress secondary production will decrease while the rate of biomass turnover (P/B) will increase. However, this concept has never been tested on organisms of smaller size (bacteria, protozoans, small metazoans), although they form the basis of the heterotrophic food web. The present work describes the results of a 7-month microcosm study, in which the effects of low and high toxic stress on an entire sediment community were examined, with cadmium (Cd) as the model pollutant (50 and 400 mg Cd kg −1 dry sediment). While metazoans and protozoans generally followed the expected trend, in bacteria both production and P/B decreased under Cd stress. These observations provide new insights into the functioning of freshwater ecosystems and demonstrate the functional consequences of toxicants on biological systems. - Highlights: ► Secondary production of freshwater organisms was estimated under cadmium stress. ► Cadmium generally decreased the production of all taxa. ► The corresponding P/B ratio increased for some taxa. ► Secondary production provides insight into the functioning of polluted ecosystems. - Cadmium alters the biomass turnover rate of a freshwater community.

  16. Carbonate Production by Benthic Communities on Shallow Coralgal Reefs of Abrolhos Bank, Brazil.

    Directory of Open Access Journals (Sweden)

    Vanessa Moura Dos Reis

    Full Text Available The abundance of reef builders, non-builders and the calcium carbonate produced by communities established in Calcification Accretion Units (CAUs were determined in three Abrolhos Bank shallow reefs during the period from 2012 to 2014. In addition, the seawater temperature, the irradiance, and the amount and composition of the sediments were determined. The inner and outer reef arcs were compared. CAUs located on the inner reef shelf were under the influence of terrigenous sediments. On the outer reefs, the sediments were composed primarily of marine biogenic carbonates. The mean carbonate production in shallow reefs of Abrolhos was 579 ± 98 g m-2 y-1. The builder community was dominated by crustose coralline algae, while the non-builder community was dominated by turf. A marine heat wave was detected during the summer of 2013-2014, and the number of consecutive days with a temperature above or below the summer mean was positively correlated with the turf cover increase. The mean carbonate production of the shallow reefs of Abrolhos Bank was greater than the estimated carbonate production measured for artificial structures on several other shallow reefs of the world. The calcimass was higher than the non-calcareous mass, suggesting that the Abrolhos reefs are still in a positive carbonate production balance. Given that marine heat waves produce an increase of turf cover on the shallow reefs of the Abrolhos, a decrease in the cover represented by reef builders and shifting carbonate production are expected in the near future.

  17. Comparisons of benthic filter feeder communities before and after a large-scale capital dredging program.

    Science.gov (United States)

    Abdul Wahab, Muhammad Azmi; Fromont, Jane; Gomez, Oliver; Fisher, Rebecca; Jones, Ross

    2017-09-15

    Changes in turbidity, sedimentation and light over a two year large scale capital dredging program at Onslow, northwestern Australia, were quantified to assess their effects on filter feeder communities, in particular sponges. Community functional morphological composition was quantified using towed video surveys, while dive surveys allowed for assessments of species composition and chlorophyll content. Onslow is relatively diverse recording 150 sponge species. The area was naturally turbid (1.1 mean P 80 NTU), with inshore sites recording 6.5× higher turbidity than offshore localities, likely influenced by the Ashburton River discharge. Turbidity and sedimentation increased by up to 146% and 240% through dredging respectively, with corresponding decreases in light levels. The effects of dredging was variable, and despite existing caveats (i.e. bleaching event and passing of a cyclone), the persistence of sponges and the absence of a pronounced response post-dredging suggest environmental filtering or passive adaptation acquired pre-dredging may have benefited these communities. Copyright © 2017. Published by Elsevier Ltd.

  18. Water quality in Danube Delta Lakes: An assessment using benthic macroinvertebrates community

    Directory of Open Access Journals (Sweden)

    IBRAM Orhan

    2016-12-01

    Full Text Available An assessment of the ecological status of selected lakes in the Danube Delta Biosphere Reserve was done based on temporal and spatial variation of macroinvertebrate communities during 2012 and 2013. Macroinvertebrate communities and measures of these communities were evaluated and a baseline characterization of assemblages was determined for the analyzed sites. Each year, three sampling campaigns, one for each ice-free season were organized for data collection. Macroinvertebrate samples have been collected in every lake from three different stations with the use of an Ekmann dredge. The highest taxa richness are recorded in Fortuna and Isac lakes in 2013. Total abundance followed a pattern similar to taxa number with Fortuna and Isac lakes having the highest yearly values (maximum number of individuals – 225 - per sample has been recorded in September 2013, in Isac Lake.Using saprobic index as an indicator of ecological status Isac lake was classifies as moderate and other three lakes, Merhei, Furtuna and Rosu as good ecological status. Lack of correlation between diversity indices and the saprobic values suggests that other assessment methods could be more effective and provide better information than saprobic index does at least for Danube Delta.

  19. Carbonate Production by Benthic Communities on Shallow Coralgal Reefs of Abrolhos Bank, Brazil.

    Science.gov (United States)

    Reis, Vanessa Moura Dos; Karez, Cláudia Santiago; Mariath, Rodrigo; de Moraes, Fernando Coreixas; de Carvalho, Rodrigo Tomazetto; Brasileiro, Poliana Silva; Bahia, Ricardo da Gama; Lotufo, Tito Monteiro da Cruz; Ramalho, Laís Vieira; de Moura, Rodrigo Leão; Francini-Filho, Ronaldo Bastos; Pereira-Filho, Guilherme Henrique; Thompson, Fabiano Lopes; Bastos, Alex Cardoso; Salgado, Leonardo Tavares; Amado-Filho, Gilberto Menezes

    2016-01-01

    The abundance of reef builders, non-builders and the calcium carbonate produced by communities established in Calcification Accretion Units (CAUs) were determined in three Abrolhos Bank shallow reefs during the period from 2012 to 2014. In addition, the seawater temperature, the irradiance, and the amount and composition of the sediments were determined. The inner and outer reef arcs were compared. CAUs located on the inner reef shelf were under the influence of terrigenous sediments. On the outer reefs, the sediments were composed primarily of marine biogenic carbonates. The mean carbonate production in shallow reefs of Abrolhos was 579 ± 98 g m-2 y-1. The builder community was dominated by crustose coralline algae, while the non-builder community was dominated by turf. A marine heat wave was detected during the summer of 2013-2014, and the number of consecutive days with a temperature above or below the summer mean was positively correlated with the turf cover increase. The mean carbonate production of the shallow reefs of Abrolhos Bank was greater than the estimated carbonate production measured for artificial structures on several other shallow reefs of the world. The calcimass was higher than the non-calcareous mass, suggesting that the Abrolhos reefs are still in a positive carbonate production balance. Given that marine heat waves produce an increase of turf cover on the shallow reefs of the Abrolhos, a decrease in the cover represented by reef builders and shifting carbonate production are expected in the near future.

  20. A Multi Size-Level Assessment of Benthic Marine Communities in a Coastal Environment: Are They Different Sides of the Same Coin?

    DEFF Research Database (Denmark)

    Vannini, Claudia; Volpi, Marta; Lardicci, Claudio

    2015-01-01

    Organism body size has been demonstrated to be a discriminating element in shaping the response of living beings to environmental factors, thus playing a fundamental role in community structuring. Despite the importance of studies elucidating relations among communities of different size levels...... have no (or very low) influence on the community composition at other size-levels. Moreover, each community responds in a different way to the environmental parameters and with a degree of sensitivity which seems to increase with organism size. Therefore, our data indicate that the characterization...... in ecosystems, the attempts that have been made in this sense are still very scarce and a reliable approach for these research still has to be defined. We characterized the benthic communities of bacteria, microbial eukaryotes, meiofauna and macrofauna in a coastal environment, encompassing a 10000-fold...

  1. A mine of information: Benthic algal communities as biomonitors of metal contamination from abandoned tailings

    International Nuclear Information System (INIS)

    Lavoie, Isabelle; Lavoie, Michel; Fortin, Claude

    2012-01-01

    Various biomonitoring approaches were tested in the field to assess the response of natural periphythic algal communities to chronic metal contamination downstream from an abandoned mine tailings site. The accumulation of cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) as well as the production of phytochelatins, the presence of diatom taxa known to tolerate high metal concentrations, diatom diversity and the presence of teratologies were determined. We observed highly significant relationships between intracellular metal and calculated free metal ion concentrations. Such relationships are often observed in laboratory studies but have been rarely validated in field studies. These results suggest that the concentration of metal inside the field-collected periphyton, regardless of its species composition, is a good indicator of exposure and is an interesting proxy for bioavailable metal concentrations in natural waters. The presence of teratologies and metal-tolerant taxa at our contaminated sites provided a clear indication that diatom communities were responding to this metal stress. A multi-metric approach integrating various bioassessment methods could be used for the field monitoring of metal contamination and the quantification of its effects. Highlights: ► Various approaches for metal contamination biomonitoring were used in the field. ► Metal accumulation in periphyton is correlated to free ion concentration. ► Teratologies and metal-tolerant taxa provided a clear indication of metal stress. ► Stream periphyton shows great potential as a biomonitor of metal contamination.

  2. Shifting baselines in the Ems Dollard estuary: A comparison across three decades reveals changing benthic communities

    Science.gov (United States)

    Compton, Tanya J.; Holthuijsen, Sander; Mulder, Maarten; van Arkel, Maarten; Schaars, Loran Kleine; Koolhaas, Anita; Dekinga, Anne; ten Horn, Job; Luttikhuizen, Pieternella C.; van der Meer, Jaap; Piersma, Theunis; van der Veer, Henk W.

    2017-09-01

    At a time when there is a growing discussion about the natural state of estuaries, a comparison of macrozoobenthos communities from two surveys conducted 30 years apart in the Ems Dollard estuary, in the eastern Wadden Sea, The Netherlands, provides a unique opportunity to compare changes over time. As expected, our comparison revealed a gradient in species composition from land (the Dollard) to sea (the Outer Ems) at both points in time, with brackish species in the Dollard and more marine species in the Outer Ems (Wadden Sea). Total richness increased over time; however, this mainly reflected the immigration of new species and sampling differences. In the Dollard, total biomass declined over time, most likely reflecting de-eutrophication in this area. Strikingly, at the meeting point between the sea and the brackish Dollard, i.e. the Inner Ems, the community composition changed from one dominated by bivalves (1970s) to one dominated by worms (since 2009). This change involved a reduction in total biomass, mainly of Mya arenaria, and immigration of polychaete worms (Marenzellaria viridis and Alitta succinea). In the Outer Ems, an increase in total biomass was observed, associated with the recent successful recruitment of Cerastoderma edule. This comparison highlights that historical data provides useful insights at large spatial scales. However, a full understanding of the complex dynamics of estuaries requires an analysis of continuous long-term monitoring series.

  3. Benthic microalgae community response to flooding in a tropical salt flat

    Directory of Open Access Journals (Sweden)

    L. S. M. Masuda

    Full Text Available Abstract This research evaluated the effect of flooding on the microphytobenthos community structure in a microbial mat from a tropical salt flat. Field samples were collected during four consecutive days: on the first three days the salt flat was dry, on the fourth day it was flooded by rain. In order to evaluate the community maintained in flood conditions, samples from this area were collected and kept in the laboratory for 10 days with sea water. The results of total abundance of microphytobenthos varied from 4.2 × 108 to 2.9 × 109 organisms L–1, total density increased one order of magnitude under the effect of water for both situations of precipitation in the salt flat and in experimental conditions, an increase due to the high abundance of Microcoleus spp. Shannon index (H’ was higher during the desiccation period. Our data suggest that changes in the abundance of organisms were due to the effect of water. The dominance of the most abundant taxa remained the same under conditions of desiccation and influence of water, and there is probably a consortium of microorganisms in the microbial mat that helps to maintain these dominances.

  4. PCB-induced changes of a benthic community and expected ecosystem recovery following in situ sorbent amendment

    Science.gov (United States)

    Janssen, Elisabeth M.-L.; Thompson, Janet K.; Luoma, Samuel N.; Luthy, Richard G.

    2011-01-01

    The benthic community was analyzed to evaluate pollution-induced changes for the polychlorinated biphenyl (PCB)-contaminated site at Hunters Point (HP) relative to 30 reference sites in San Francisco Bay, California, USA. An analysis based on functional traits of feeding, reproduction, and position in the sediment shows that HP is depauperate in deposit feeders, subsurface carnivores, and species with no protective barrier. Sediment chemistry analysis shows that PCBs are the major risk drivers at HP (1,570 ppb) and that the reference sites contain very low levels of PCB contamination (9 ppb). Different feeding traits support the existence of direct pathways of exposure, which can be mechanistically linked to PCB bioaccumulation by biodynamic modeling. The model shows that the deposit feeder Neanthes arenaceodentata accumulates approximately 20 times more PCBs in its lipids than the facultative deposit feeder Macoma balthica and up to 130 times more than the filter feeder Mytilus edulis. The comparison of different exposure scenarios suggests that PCB tissue concentrations at HP are two orders of magnitude higher than at the reference sites. At full scale, in situ sorbent amendment with activated carbon may reduce PCB bioaccumulation at HP by up to 85 to 90% under favorable field and treatment conditions. The modeling framework further demonstrates that such expected remedial success corresponds to exposure conditions suggested as the cleanup goal for HP. However, concentrations remain slightly higher than at the reference sites. The present study demonstrates how the remedial success of a sorbent amendment, which lowers the PCB availability, can be compared to reference conditions and traditional cleanup goals, which are commonly based on bulk sediment concentrations.

  5. Short-term impact of blue mussel dredging ( Mytilus edulis L.) on a benthic community

    DEFF Research Database (Denmark)

    Dolmer, Per; Kristensen, T.; Christiansen, M.L.

    2001-01-01

    The short-term effect of mussel dredging in a brackish Danish sound was studied. A commercial dredging track was identified and an analysis of the species composition inside the track and at an adjacent control area showed that dredging changed the community structure by reducing the density...... of polychaetes. In order to investigate the extent and the duration of the dredging impact experimental dredging was conducted. The experimental dredging removed 50% of the mussels in two dredged areas. Immediately after dredging, a significantly lower number of species was measured inside the mussel beds...... in dredged areas compared to control and boundary areas. This effect lasted for at least 40 days. The analysis of the species composition showed that the dredged area had a significantly lower density, particularly of polychaetes compared to the boundary area. An increased number of species was recorded...

  6. Macrophytes: Ecology of aquatic plants

    NARCIS (Netherlands)

    Bornette, G.; Puijalon, S.

    2009-01-01

    Aquatic plants contribute to maintaining key functions and related biodiversity in freshwater ecosystems, and to provide the needs of human societies. The way the ecological niches of macrophytes are determined by abiotic filters and biotic ones is considered. A simple, broadly applicable model of

  7. Checklist of the Aquatic Macrophytes

    African Journals Online (AJOL)

    Professor, Department of Plant Science, Obafemi Awolowo University, Ile Ife, Osun State. 3. Professor, Department of Botany, Obafemi Awolowo University, Ile Ife, Osun State. (Received: October, 2010; Accepted: May, 2011). The occurrence and diversity of aquatic macrophytes on Jebba Lake were documented during the ...

  8. Ecosystem stress response : understanding effects on the benthic invertebrate community of Alberta oil-sands wetlands

    International Nuclear Information System (INIS)

    Wytrykush, C.M.; Ciborowski, J.J.H.

    2003-01-01

    The environmental stress response of invertebrates was examined using wetlands in the Alberta oil-sands region as a model. Wetlands in this region occur naturally or they have been affected by oil-sands mining process materials such as mine-tailings, or saline process water. These materials can be toxic to aquatic organisms due to their high concentrations of sulphate ions, ammonia, polycyclic aromatic hydrocarbons (PAHs) and naphthenic acids. Wetlands are classified as either young or mature, and as having low or high sediment organic content. This study examined food web dynamics and structure in wetlands using stable isotopes to determine the effects of stress on ecological communities. Primary and secondary production in the wetlands was measured along with invertebrate diversity in order to determine a relationship. The maximum trophic position was determined using stable carbon and nitrogen isotopes to indicate food chain length which is influenced by energetic constraints, ecosystem size and stressors. The study quantifies the dynamics of vital links between the responses to environmental pressures in aquatic systems and the effects on terrestrial ecosystems

  9. Emergent Macrophytes Support Zooplankton in a Shallow Tropical Lake: A Basis for Wetland Conservation

    Science.gov (United States)

    Gebrehiwot, Mesfin; Kifle, Demeke; Triest, Ludwig

    2017-12-01

    Understanding the biodiversity value of littoral zones of lakes is a priority for aquatic biodiversity conservation. However, less emphasis has been given to the littoral part of tropical African lakes, with many of the previous researches focusing only on the open water side. The aim of the present study was, therefore, to investigate the impact of the littoral zone of a shallow freshwater tropical lake (Ziway, Ethiopia), dominated by two emergent macrophytes, on zooplankton community structure. We hypothesized that the wetland vegetation serves as a preferred microhabitat for zooplankton communities. A lake with substantial coverage of emergent macrophytes was monitored monthly from January to August, 2016. The monitoring included the measurements of physical, chemical, and biological parameters. Sampling sites were selected to represent areas of the macrophyte vegetation ( Typha latifolia and Phragmites australis) and the open water part of the lake. Sites with macrophyte vegetation were found to be the home of more dense and diverse zooplankton community. However, during the period of high vegetation loss, the density of crustacean zooplankton showed significant reduction within the patches of macrophytes. From biodiversity conservation perspective, it was concluded that the preservation of such small areas of macrophytes covering the littoral zone of lakes could be as important as protecting the whole lake. However, the rapid degradation of wetland vegetation by human activities is a real threat to the lake ecosystem. In the not-too-far future, it could displace and evict riparian vegetation and the biota it supports.

  10. Regulation and role of epiphytic nitrification and denitrification in macrophyte-dominated systems

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, Peder G.

    2000-02-01

    This thesis examines mechanisms regulating bacterial nitrification and denitrification in attached microbial communities on surfaces of aquatic macrophytes. It also evaluates the role of epiphytic nitrification and denitrification for the nitrogen turnover in macrophyte-dominated nutrient-rich freshwater. Epiphytic nitrification is promoted in light and epiphytic denitrification occurs mainly in dark, because the metabolic activity of the aquatic macrophyte and its epiphytes induce in light high and in dark low oxygen concentrations in epiphytic communities. Epiphytic nitrification and denitrification are also affected by the physical and chemical characteristics of the aquatic macrophyte. The spatial distribution of nitrification in emergent macrophyte wetlands is related to the species composition of the emergent vegetation, possibly because of a macrophyte species-related release of organic nitrification inhibitors. Contrasting to nitrifying bacteria, which are lithotrophic, denitrifying bacteria use organic substances as an energy source and are therefore stimulated by the release of organic matter from aquatic macrophytes. Epiphytic communities support more denitrification in nutrient-rich than in nutrient-poor environments. In lakes and ponds, epiphytic denitrification is higher at sheltered locations than at locations exposed to wind-induced water movements or currents. In flowing water, epiphytic denitrification occurs mainly at low oxygen concentrations in the surrounding water. However, because aquatic macrophytes impede water flow and induce low oxygen concentrations in dark, epiphytic denitrification can be present within dense vegetation despite of high oxygen concentrations in the surrounding water. Epiphytic nitrification is almost unaffected by flow conditions, and can occur both in light and in dark. In shallow-water systems such as treatment wetlands, aquatic macrophytes often provide most of the accessible surface area for attached nitrifying and

  11. Sediment pollution and predation affect structure and production of benthic macroinvertebrate communities in the Rhine-Meuse delta, The Netherlands

    NARCIS (Netherlands)

    Lange, de H.J.; Jonge, de J.; Besten, den P.J.; Oosterbaan, J.; Peeters, E.T.H.M.

    2004-01-01

    Most floodplain sediments of the rivers Rhine and Meuse in The Netherlands are moderately polluted with trace metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and other chemicals. The effects of these sediment-bound contaminants on the productivity of benthic

  12. Sources of beta diversity in estuarine benthic macro-invertebrate communities in the Baltic Sea - North Sea transition

    DEFF Research Database (Denmark)

    Josefson, Alf B.; Göke, Cordula

    Identification of sources of beta diversity, the change of diversity, is important to understand regulation of overall diversity. Additive partitioning of diversity (species richness and expH) compared to random, was performed on a quantitative benthic macro-invertebrate collection of > 400 speci...

  13. Predicting species diversity of benthic communities within turbid nearshore using full-waveform bathymetric LiDAR and machine learners.

    Directory of Open Access Journals (Sweden)

    Antoine Collin

    Full Text Available Epi-macrobenthic species richness, abundance and composition are linked with type, assemblage and structural complexity of seabed habitat within coastal ecosystems. However, the evaluation of these habitats is highly hindered by limitations related to both waterborne surveys (slow acquisition, shallow water and low reactivity and water clarity (turbid for most coastal areas. Substratum type/diversity and bathymetric features were elucidated using a supervised method applied to airborne bathymetric LiDAR waveforms over Saint-Siméon-Bonaventure's nearshore area (Gulf of Saint-Lawrence, Québec, Canada. High-resolution underwater photographs were taken at three hundred stations across an 8-km(2 study area. Seven models based upon state-of-the-art machine learning techniques such as Naïve Bayes, Regression Tree, Classification Tree, C 4.5, Random Forest, Support Vector Machine, and CN2 learners were tested for predicting eight epi-macrobenthic species diversity metrics as a function of the class number. The Random Forest outperformed other models with a three-discretized Simpson index applied to epi-macrobenthic communities, explaining 69% (Classification Accuracy of its variability by mean bathymetry, time range and skewness derived from the LiDAR waveform. Corroborating marine ecological theory, areas with low Simpson epi-macrobenthic diversity responded to low water depths, high skewness and time range, whereas higher Simpson diversity relied upon deeper bottoms (correlated with stronger hydrodynamics and low skewness and time range. The degree of species heterogeneity was therefore positively linked with the degree of the structural complexity of the benthic cover. This work underpins that fully exploited bathymetric LiDAR (not only bathymetrically derived by-products, coupled with proficient machine learner, is able to rapidly predict habitat characteristics at a spatial resolution relevant to epi-macrobenthos diversity, ranging from clear to

  14. Monitoring of coastal coral reefs near Dahab (Gulf of Aqaba, Red Sea) indicates local eutrophication as potential cause for change in benthic communities.

    Science.gov (United States)

    Naumann, Malik S; Bednarz, Vanessa N; Ferse, Sebastian C A; Niggl, Wolfgang; Wild, Christian

    2015-02-01

    Coral reef ecosystems fringing the coastline of Dahab (South Sinai, Egypt) have experienced increasing anthropogenic disturbance as an emergent international tourism destination. Previous reports covering tourism-related impacts on coastal environments, particularly mechanical damage and destructive fishing, have highlighted the vital necessity for regular ecosystem monitoring of coral reefs near Dahab. However, a continuous scientific monitoring programme of permanent survey sites has not been established to date. Thus, this study conducted in situ monitoring surveys to investigate spatio-temporal variability of benthic reef communities and selected reef-associated herbivores along with reef health indicator organisms by revisiting three of the locally most frequented dive sites during expeditions in March 2010, September 2011 and February 2013. In addition, inorganic nutrient concentrations in reef-surrounding waters were determined to evaluate bottom-up effects of key environmental parameters on benthic reef community shifts in relation to grazer-induced top-down control. Findings revealed that from 2010 to 2013, live hard coral cover declined significantly by 12 % at the current-sheltered site Three Pools (TP), while showing negative trends for the Blue Hole (BH) and Lighthouse (LH) sites. Hard coral cover decline was significantly and highly correlated to a substantial increase in turf algae cover (up to 57 % at TP) at all sites, replacing hard corals as dominant benthic space occupiers in 2013. These changes were correlated to ambient phosphate and ammonium concentrations that exhibited highest values (0.64 ± 0.07 μmol PO4 (3-) l(-1), 1.05 ± 0.07 μmol NH4 (+) l(-1)) at the degraded site TP. While macroalgae appeared to respond to both bottom-up and top-down factors, change in turf algae was consistent with expected indications for bottom-up control. Temporal variability measured in herbivorous reef fish stocks reflected seasonal impacts by

  15. Succession in rocky intertidal benthic communities in areas with different pollution levels at Guanabara Bay (RJ-Brazil

    Directory of Open Access Journals (Sweden)

    André Breves-Ramos

    2005-11-01

    Full Text Available The aim of this study was to describe and compare the succession of intertidal benthic communities in two areas at Guanabara Bay, RJ, Brazil: Urca, an area submitted to moderated organic pollution and Catalão, an extremely polluted area. Three transects in each area were scraped one month before the beginning of this study in order to evaluate the recruitment (recruitment-treatments. Three other transects were monitored without manipulation (monitoring treatments. Species composition and relative abundance were evaluated monthly between September and December, 2000. A total of 26 species was found at Urca and 13 at Catalão. The percent cover of the most abundant organisms was not similar between treatments at Urca after four months, while in Catalão, the similarity was 72% in the second month. The faster community development and recovery at the most polluted area was probably related to the existence of simple and resilient communities in more impacted areas.O objetivo deste estudo foi descrever e comparar a sucessão das comunidades bentônicas da região entre-marés, em duas áreas na Baía de Guanabara, RJ, Brasil: Urca, uma área sujeita a moderado nível de poluição orgânica, e Catalão, uma área extremamente poluída. Em cada área, três transectos verticais foram raspados um mês antes do início do estudo, para se avaliar o recrutamento dos organismos (tratamento Recrutamento, enquanto três outros transectos foram monitorados sem manipulação (tratamento Monitoramento. A porcentagem de cobertura dos organismos foi avaliada pelo método de interseção. A composição específica e a abundância relativa dos organismos foram avaliadas mensalmente entre Setembro e Dezembro de 2000. Um total de 26 espécies foi encontrado na Urca, enquanto 13 foram encontradas no Catalão. Após quatro meses, a composição específica observada no recrutamento na Urca foi muito similar (76% a observada no monitoramento. No Catalão, três meses

  16. Macroinvertebrates associated with two submerged macrophytes ...

    African Journals Online (AJOL)

    Macroinvertebrates associated with two submerged macrophytes, Lagarosiphon ilicifolius and Vallisneria aethiopica , in the Sanyati Basin, Lake Kariba, Zimbabwe: effect of plant morphological complexity.

  17. Microcystin production in epiphytic cyanobacteria on submerged macrophytes.

    Science.gov (United States)

    Mohamed, Zakaria A; Al Shehri, Abdulrahman M

    2010-06-15

    Cyanotoxins have been largely studied in planktonic and benthic cyanobacteria, but microcystin (MCYST) production in epiphytic cyanobacteria has not been reported yet. The present study reports for the first time the MCYST production in epiphytic cyanobacteria on submerged macrophytes. During this study, four common submerged macrophytes in eutrophic pond in Saudi Arabia were surveyed for the presence of toxic epiphytic cyanobacteria. The results showed that chlorophyll-a and total biovolume of epiphytic cyanobacteria differed significantly among submerged plants with highest values obtained in Stratiotes aloides and lowest in Elodea canadensis. Epiphytic materials collected from Ceratophyllum demersum and S. aloides had higher species diversities than materials collected from E. canadensis and Myriophyllum verticillatum. The cyanobacteria, Merismopedia tenuissima and Leptolyngbya boryana were recorded with a high abundance in epiphytic materials collected from all submerged macrohpytes. Based on Enzyme-linked immunosorbent assay (ELISA), these two species were found to produce MCYSTs (MCYSTs) with concentrations of 1438 and 630 microg g(-1) dry weight, respectively. HPLC analysis of the methanolic extracts of the two species showed that M. tenuissima extract contained MCYST-RR and -LR/demethyl LR plus 3 minor unidentified MCYSTs, while L. boryana extract contained MCYST-YR, -LR/demethyl LR, and 2 minor unidentified MCYSTs. This study suggests that epiphytic species should be considered during monitoring of toxic cyanobacteria in water sources. 2010 Elsevier Ltd. All rights reserved.

  18. Benthic protists: the under-charted majority.

    Science.gov (United States)

    Forster, Dominik; Dunthorn, Micah; Mahé, Fréderic; Dolan, John R; Audic, Stéphane; Bass, David; Bittner, Lucie; Boutte, Christophe; Christen, Richard; Claverie, Jean-Michel; Decelle, Johan; Edvardsen, Bente; Egge, Elianne; Eikrem, Wenche; Gobet, Angélique; Kooistra, Wiebe H C F; Logares, Ramiro; Massana, Ramon; Montresor, Marina; Not, Fabrice; Ogata, Hiroyuki; Pawlowski, Jan; Pernice, Massimo C; Romac, Sarah; Shalchian-Tabrizi, Kamran; Simon, Nathalie; Richards, Thomas A; Santini, Sébastien; Sarno, Diana; Siano, Raffaele; Vaulot, Daniel; Wincker, Patrick; Zingone, Adriana; de Vargas, Colomban; Stoeck, Thorsten

    2016-08-01

    Marine protist diversity inventories have largely focused on planktonic environments, while benthic protists have received relatively little attention. We therefore hypothesize that current diversity surveys have only skimmed the surface of protist diversity in marine sediments, which may harbor greater diversity than planktonic environments. We tested this by analyzing sequences of the hypervariable V4 18S rRNA from benthic and planktonic protist communities sampled in European coastal regions. Despite a similar number of OTUs in both realms, richness estimations indicated that we recovered at least 70% of the diversity in planktonic protist communities, but only 33% in benthic communities. There was also little overlap of OTUs between planktonic and benthic communities, as well as between separate benthic communities. We argue that these patterns reflect the heterogeneity and diversity of benthic habitats. A comparison of all OTUs against the Protist Ribosomal Reference database showed that a higher proportion of benthic than planktonic protist diversity is missing from public databases; similar results were obtained by comparing all OTUs against environmental references from NCBI's Short Read Archive. We suggest that the benthic realm may therefore be the world's largest reservoir of marine protist diversity, with most taxa at present undescribed. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  19. Benthic macroinvertebrate assemblages in mangroves and open ...

    African Journals Online (AJOL)

    Benthic macroinvertebrate assemblages in mangroves and open intertidal areas on the Dar es Salaam coast, Tanzania. ... it is recommended that conservation efforts along the Tanzanian coast should focus here. Keywords: benthic macrofauna, community structure, littoral zone, Tanganyika, Western Indian Ocean ...

  20. Vulnerabilities of macrophytes distribution due to climate change

    Science.gov (United States)

    Hossain, Kaizar; Yadav, Sarita; Quaik, Shlrene; Pant, Gaurav; Maruthi, A. Y.; Ismail, Norli

    2017-08-01

    The rise in the earth's surface and water temperature is part of the effect of climatic change that has been observed for the last decade. The rates of climate change are unprecedented, and biological responses to these changes have also been prominent in all levels of species, communities and ecosystems. Aquatic-terrestrial ecotones are vulnerable to climate change, and degradation of the emergent aquatic macrophyte zone would have contributed severe ecological consequences for freshwater, wetland and terrestrial ecosystems. Most researches on climate change effects on biodiversity are contemplating on the terrestrial realm, and considerable changes in terrestrial biodiversity and species' distributions have been detected in response to climate change. This is unfortunate, given the importance of aquatic systems for providing ecosystem goods and services. Thus, if researchers were able to identify early-warning indicators of anthropogenic environmental changes on aquatic species, communities and ecosystems, it would certainly help to manage and conserve these systems in a sustainable way. One of such early-warning indicators concerns the expansion of emergent macrophytes in aquatic-terrestrial ecotones. Hence, this review highlights the impact of climatic changes towards aquatic macrophytes and their possible environmental implications.

  1. Using Benthic Macroinvertebrate and Fish Communities as Bioindicators of the Tanshui River Basin Around the Greater Taipei Area — Multivariate Analysis of Spatial Variation Related to Levels of Water Pollution

    Directory of Open Access Journals (Sweden)

    Shuh-Sen Young

    2014-07-01

    Full Text Available After decades of strict pollution control and municipal sewage treatment, the water quality of the Tanshui River increased significantly after pollution mitigation as indicated by the River Pollution Index (RPI. The pollution level of the estuarine region decreased from severe pollution to mostly moderately impaired. The most polluted waters are presently restricted to a flow track length between 15–35 km relative to the river mouth. From July 2011 to September 2012, four surveys of fish and benthic macroinvertebrates were conducted at 45 sampling sites around the Tanshui River basin. The pollution level of all the study area indicated by the RPI could also be explained by the Family Biotic Index (FBI and Biotic Index (BI from the benthic macroinvertebrate community, and the Index of Biotic Integrity (IBI of the fish community. The result of canonical correlation analysis between aquatic environmental factors and community structure indicated that the community structure was closely related to the level of water pollution. Fish species richness in the estuarine area has increased significantly in recent years. Some catadromous fish and crustaceans could cross the moderate polluted water into the upstream freshwater, and have re-colonized their populations. The benthic macroinvertebrate community relying on the benthic substrate of the estuarine region is still very poor, and the water layer was still moderately polluted.

  2. Using benthic macroinvertebrate and fish communities as bioindicators of the Tanshui River basin around the greater Taipei area - multivariate analysis of spatial variation related to levels of water pollution.

    Science.gov (United States)

    Young, Shuh-Sen; Yang, Hsi-Nan; Huang, Da-Ji; Liu, Su-Miao; Huang, Yueh-Han; Chiang, Chung-Ting; Liu, Jin-Wei

    2014-07-14

    After decades of strict pollution control and municipal sewage treatment, the water quality of the Tanshui River increased significantly after pollution mitigation as indicated by the River Pollution Index (RPI). The pollution level of the estuarine region decreased from severe pollution to mostly moderately impaired. The most polluted waters are presently restricted to a flow track length between 15-35 km relative to the river mouth. From July 2011 to September 2012, four surveys of fish and benthic macroinvertebrates were conducted at 45 sampling sites around the Tanshui River basin. The pollution level of all the study area indicated by the RPI could also be explained by the Family Biotic Index (FBI) and Biotic Index (BI) from the benthic macroinvertebrate community, and the Index of Biotic Integrity (IBI) of the fish community. The result of canonical correlation analysis between aquatic environmental factors and community structure indicated that the community structure was closely related to the level of water pollution. Fish species richness in the estuarine area has increased significantly in recent years. Some catadromous fish and crustaceans could cross the moderate polluted water into the upstream freshwater, and have re-colonized their populations. The benthic macroinvertebrate community relying on the benthic substrate of the estuarine region is still very poor, and the water layer was still moderately polluted.

  3. Using Benthic Macroinvertebrate and Fish Communities as Bioindicators of the Tanshui River Basin Around the Greater Taipei Area — Multivariate Analysis of Spatial Variation Related to Levels of Water Pollution

    Science.gov (United States)

    Young, Shuh-Sen; Yang, Hsi-Nan; Huang, Da-Ji; Liu, Su-Miao; Huang, Yueh-Han; Chiang, Chung-Ting; Liu, Jin-Wei

    2014-01-01

    After decades of strict pollution control and municipal sewage treatment, the water quality of the Tanshui River increased significantly after pollution mitigation as indicated by the River Pollution Index (RPI). The pollution level of the estuarine region decreased from severe pollution to mostly moderately impaired. The most polluted waters are presently restricted to a flow track length between 15–35 km relative to the river mouth. From July 2011 to September 2012, four surveys of fish and benthic macroinvertebrates were conducted at 45 sampling sites around the Tanshui River basin. The pollution level of all the study area indicated by the RPI could also be explained by the Family Biotic Index (FBI) and Biotic Index (BI) from the benthic macroinvertebrate community, and the Index of Biotic Integrity (IBI) of the fish community. The result of canonical correlation analysis between aquatic environmental factors and community structure indicated that the community structure was closely related to the level of water pollution. Fish species richness in the estuarine area has increased significantly in recent years. Some catadromous fish and crustaceans could cross the moderate polluted water into the upstream freshwater, and have re-colonized their populations. The benthic macroinvertebrate community relying on the benthic substrate of the estuarine region is still very poor, and the water layer was still moderately polluted. PMID:25026081

  4. The decomposition of estuarine macrophytes under different ...

    African Journals Online (AJOL)

    The aim of this study was to determine the decomposition characteristics of the most dominant submerged macrophyte and macroalgal species in the Great Brak Estuary. Laboratory experiments were conducted to determine the effect of different temperature regimes on the rate of decomposition of 3 macrophyte species ...

  5. Macrophytes: Freshwater Forests of Lakes and Rivers.

    Science.gov (United States)

    McDermid, Karla J.; Naiman, Robert J.

    1983-01-01

    Physical, chemical, and biological effects on macrophytes (aquatic plants) on the freshwater ecosystem are discussed. Research questions and issues related to these organisms are also discussed, including adaptations for survival in a wet environment, ecological consequences of large-scale macrophyte eradication, seasonal changes in plant…

  6. Transfer of seston lipids during a flagellate bloom from the surface to the benthic community in the Weddell Sea

    Directory of Open Access Journals (Sweden)

    Sergio Rossi

    2013-09-01

    Full Text Available Total lipid and fatty acid concentrations were studied in a late spring-early summer flagellate-dominated bloom in the Weddell Sea. These indicators were considered a good tool for assessing the quality of organic matter settling from surface to deep-water layers (epibenthic water layers. The results showed different patterns between the early (11-15 December 2003 and the late sampling period (18-27 December 2003 at all studied depths (5 m, 50 m and near-bottom water layers. Low phytoplankton biomass (mainly flagellates in the first half of the study corresponded to low total lipid and fatty acid concentrations. In the second sampling period a spring bloom (mainly flagellates and diatoms was detected, increasing the total lipid and fatty acid concentrations in the water column. The amount of settling organic matter from surface waters to the near-bottom water layers was high, especially in the late sampling period. Trophic markers showed evidence of a sink of available organic matter rich in quality and quantity, especially in terms of polyunsaturated fatty acids, for benthic organisms from surface layers to bottom layers in only a few days. The importance of studying short-time cycles in order to detect organic matter availability for benthic biota in view of the pulse-like dynamics of primary production in Antarctic waters is discussed.

  7. Environmental clustering of lakes to evaluate performance of a macrophyte index of biotic integrity

    Science.gov (United States)

    Vondracek, Bruce C.; Vondracek, Bruce; Hatch, Lorin K.

    2013-01-01

    Proper classification of sites is critical for the use of biological indices that can distinguish between natural and human-induced variation in biological response. The macrophyte-based index of biotic integrity was developed to assess the condition of Minnesota lakes in relation to anthropogenic stressors, but macrophyte community composition varies naturally across the state. The goal of the study was to identify environmental characteristics that naturally influence macrophyte index response and establish a preliminary lake classification scheme for biological assessment (bioassessment). Using a comprehensive set of environmental variables, we identified similar groups of lakes by clustering using flexible beta classification. Variance partitioning analysis of IBI response indicated that evaluating similar lake clusters could improve the ability of the macrophyte index to identify community change to anthropogenic stressors, although lake groups did not fully account for the natural variation in macrophyte composition. Diagnostic capabilities of the index could be improved when evaluating lakes with similar environmental characteristics, suggesting the index has potential for accurate bioassessment provided comparable groups of lakes are evaluated.

  8. Biodiversity, Community and Trophic Structure of the Suprabenthos of the Gulf of Cádiz-Guadalquivir Estuary Coupled System: Linking Pelagic-Benthic and Terrestrial-Marine Ecosystems.

    Science.gov (United States)

    Vilas, C.

    2016-02-01

    Suprabenthos biodiversity and species densities on both offshore and coastal systems are largely unknown. Main components like mysids, euphasiids or amphipods are omnivorous and constitute a major dietary component for many benthic and pelagic fishes, mammals, cephalopods and decapods. Despite their relevant ecological role linking pelagic-benthic food webs, suprabenthos have been chronically undersampled and their components underrepresented and underestimated in food web models. Many pelagic and demersal species of high commercial and ecological interest at the Gulf of Cádiz (GoC) feed at a bottom scattering layer identified from 0 to 200 m depth and up to 50 km from coast, related to the Guadalquivir Estuary (GE) influence coastal area, and present life history cycles based on a sequential use of habitats from GoC to GE nursery area, may be adapted to match the horizontal migrations of key suprabenthos prey species. In order to understand the ecological mechanisms through which the GE-GoC coupled ecosystem would influence the recruitment of these fishery resources, the suprabenthos was sampled by suprabenthic sldege (200 μm) from the shallow estuary to 75 m depth during June, August and November of 2013. We identified up to 300 species (H index 0.4-2-9 and Beta diversity 0.55), being copepods, molluscs, cumacea, cladocera, poliquets, decapods, mysids and amphipods the most important groups by biomass (mg/m3), finding densities up to 32.9 mg/m3 for copepods, 6 for mysids and up to 100 mg/m3 for decapods. Multivariate analysis determines depth as the most important variable explaining community structure, decreasing biodiversity with depth, while for sites at depths species show seasonal horizontal migrations between GoC and GE, connecting terrestrial and marine ecosystems.

  9. Response of an estuarine benthic community to application of the pesticide carbaryl and cultivation of Pacific oysters (Crassostrea gigas) in Willapa Bay, Washington.

    Science.gov (United States)

    Dumbauld, B R; Brooks, K M; Posey, M H

    2001-10-01

    Oyster culture operations on the West coast of North America have developed into complete farming operations for the introduced Japanese oyster, Crassostrea gigas, which now covers vast areas of the intertidal landscape, particularly in Washington State where the pesticide carbaryl has also been used to control burrowing thalassinid shrimp for more than 30 years. Field experiments were conducted to examine the effects of these habitat modifications on the benthic community in Willapa, Bay Washington (124 degrees 06'W,46 degrees 24'N) where 50% of the state's oyster production occurs. Results indicated that the primary long-term effect of carbaryl application was removal of the two species of thalassinid shrimp (Neotrypaea californiensis and Upogebia pugettensis), which dominated the community at the start of the experiment and clearly influenced community composition themselves. Small peracarid crustaceans like the amphipods Corophium acherusicum and Eohaustorius estuarius experienced the most significant short-term mortalities, but generally recruited back to treated sites within 3 months, and were often more abundant on treated than untreated sites 1 year after carbaryl application. Results for molluscs were mixed, with no significant effect on Macoma spp, but a significant effect on the commensal clam Crytomya californica and mixed results for the cockle Clinocardium nutalli. Polychaetes were the least susceptible to carbaryl and with the exception of a short-term effect on oligochaetes, no significant negative effects were observed. The addition of oysters did not affect the infaunal community in this study, however greater abundance of epifaunal organisms like mussels, scaleworms, and the amphipod Amphithoe valida, which builds tubes in algae attached to shells, was observed. Carbaryl, which is currently applied to roughly 242 ha (oyster culture operations like the addition of oysters themselves to a community often dominated by burrowing thalassinid shrimp

  10. Genetic and nutritional characterization of some macrophytes, inhabiting the Bardawil Lagoon, Sinai, Egypt

    Directory of Open Access Journals (Sweden)

    Hosam E. Elsaied

    2015-12-01

    Full Text Available The ecological and economical significances of macrophytes, inhabiting the Mediterranean Lagoon, Bardawil, northern Sinai, Egypt, are still ambiguous, due to lack of knowledge. This study focused on genetic and nutritional characterization of three dominant macrophyte species at Bardawil Lagoon. Genetic identifications were done through genomic DNA extraction, followed by PCR amplifications and sequencing of 18S rRNA genes of the studied species. Phylogenetic analyses indicated that two of the recorded species showed homologies with the seagrass species, Posidonia oceanica and Halophila ovalis, with nucleotide identities 94.5% and 96.8%, respectively. The third species showed a unique phylogenetic lineage, representing nucleotide identity average, 86.5%, among the brown seaweeds, Heterokontophyta. Nutritional analyses indicated that the recorded seaweed-like macrophyte had the highest recommended nutritional contents, crude protein, 24.67%, with a total amino acid composition of 6.64 g/100 g protein, and carbohydrate, 38.16%, besides a calorific value of 3.063 K cal/g, among the studied macrophytes. To the best of our knowledge, this is the first attempt to characterize macrophyte community in Bardawil Lagoon, using both genetic and biochemical approaches.

  11. Evaluation of invasions and declines of submersed aquatic macrophytes

    Science.gov (United States)

    Chambers, P.A.; Barko, J.W.; Smith, C.S.

    1993-01-01

    During the past 60 yr, sightings of aquatic macrophyte species in geographic regions where they had previously not been found have occurred with increasing frequency, apparently due to both greater dispersal of the plants as a result of human activities as well as better documentation of plant distribution. Intercontinental invasions, such as Myriophyllum spicatum and Hydrilla into North America, Elodea canadensis into Europe and Elodea nuttallii, Egeria densa and Cabomba caroliniana into Japan, have generally been well documented. However, the spread of an exotic species across a continent after its initial introduction (e.g., Potamogeton crispus in North America) or the expansion of a species native to a continent into hitherto unexploited territory (e.g.,the expansion of the North American native Myriophyllum heterophyllum into New England) have received little attention. Natural declines in aquatic macrophyte communities have also received little scientific study although there are many accounts of macrophyte declines. The best-documented example comes from the marine literature where extensive declines of eelgrass (Zostera) occurred in the 1930s along the Atlantic coast due to a pathogenic marine slime mold (''wasting disease''). The aim of this workshop was to identify examples of invasions or natural declines of aquatic macrophyte species throughout the world and assess the importance of environmental factors in their control. Forty-five scientists and aquatic plant managers from ten countries participated in the workshop. Eleven of the participants contributed written evaluations of species invasions and declines in their geo-graphic region. These were distributed to registered participants prior to the meeting and served as the starting-point of workshop discussions. To address the topics raised in the working papers, the participants divided into four working groups to evaluate: 1. Environmental controls of species invasions. 2. Biotic controls of species

  12. Macrophytes of the Grlište reservoir (Serbia: Fifteen years after its establishment

    Directory of Open Access Journals (Sweden)

    Stanković Ž.

    2009-01-01

    Full Text Available A large number of macrophytes, often in dense populations, have developed on the Grlište Reservoir, Serbia over a period of 15 years. Fast development of vegetation is a consequence of anthropogenic impact in lake management. The methodology used in this research covered 100% of the water body, including all areas with or without aquatic plants. The results indicate that plant communities are still in the early phase of development. This leaves space for future development of competitor macrophyte species (Najas marina, Eleocharis palustris, Typha latifolia, Typha angustifolia, Phragmites australis, etc. capable of endangering stability of the lake, which will tend toward eutrophication.

  13. Multispectral televisional measuring control of the ecological state of waterbodies on the characteristics macrophytes

    Science.gov (United States)

    Petruk, Vasil; Kvaternyuk, Sergii; Kozachuk, Anastasia; Sailarbek, Saltanat; Gromaszek, Konrad

    2015-12-01

    Improved methods for multispectral measuring television monitoring of the ecological state of water bodies on the characteristics of macrophytes groups to assess complex human impact on their environment. Integral assessment of water pollution is based on research products of higher aquatic plants and their communities by optical methods.

  14. Competition between two submersed aquatic macrophytes, Potamogeton pectinatus and Potamogeton gramineus, across a light gradient

    Science.gov (United States)

    Submersed aquatic macrophyte communities, are often limited by the availability of light. Thus, they offer a unique opportunity to evaluate competition when light is the limiting resource. Competitive abilities of Potamogeton pectinatus (L.) Börner and Potamogeton gramineus L. were estimated using a...

  15. Responses of aquatic macrophytes to anthropogenic pressures: comparison between macrophyte metrics and indices.

    Science.gov (United States)

    Camargo, Julio A

    2018-02-26

    Macrophyte responses to anthropogenic pressures in two rivers of Central Spain were assessed to check if simple metrics can exhibit a greater discriminatory and explanatory power than complex indices at small spatial scales. Field surveys were undertaken during the summer of 2014 (Duraton River) and the spring of 2015 (Tajuña River). Aquatic macrophytes were sampled using a sampling square (45 × 45 cm). In the middle Duraton River, macrophytes responded positively to the presence of a hydropower dam and a small weir, with Myriophyllum spicatum and Potamogeton pectinatus being relatively favored. Index of Macrophytes (IM) was better than Macroscopic Aquatic Vegetation Index (MAVI) and Fluvial Macrophyte Index (FMI) in detecting these responses, showing positive and significant correlations with total coverage, species richness, and species diversity. In the upper Tajuña River, macrophytes responded both negatively and positively to the occurrence of a trout farm effluent and a small weir, with Leptodictyum riparium and Veronica anagallis-aquatica being relatively favored. Although IM, MAVI, and FMI detected both negative and positive responses, correlations of IM with total coverage, species richness, and species diversity were higher. Species evenness was not sensitive enough to detect either positive or negative responses of aquatic macrophytes along the study areas. Overall, traditional and simple metrics (species composition, total coverage, species richness, species diversity) exhibited a greater discriminatory and explanatory power than more recent and complex indices (IM, MAVI, FMI) when assessing responses of aquatic macrophytes to anthropogenic pressures at impacted specific sites.

  16. The effects of hydrological dynamics on benthic diatom community structure in a highly stratified estuary: The case of the Ebro Estuary (Catalonia, Spain)

    Science.gov (United States)

    Rovira, L.; Trobajo, R.; Leira, M.; Ibáñez, C.

    2012-04-01

    This study of the distribution of benthic diatom assemblages and their relationship with environmental factors in a highly stratified Mediterranean estuary, i.e. the Ebro Estuary, shows the importance of hydrological dynamics to explain the features of the diatom community in such an estuary, where river flow magnitude and fluctuations imply strong physicochemical variability especially in sites close to the sea. Eight sites along the estuary were sampled during 2007-2008 both at superficial and deep water layers, in order to gather both horizontal and vertical estuarine physicochemical and hydrological gradients. Canonical Variates Analysis and Hierarchical Cluster Analysis segregated diatom community in two assemblages depending on the dynamics of the salt-wedge. The diatom assemblages of riverine conditions (i.e. without salt-wedge influence) where characterised by high abundances of Cocconeis placentula var. euglypta and Amphora pediculus, meanwhile high abundances of Nizschia frustulum and Nitzschia inconspicua were characteristic of estuarine conditions (i.e. under salt-wedge influence). Redundancy Analysis showed that both diatom assemblages responded seasonally to Ebro River flows, especially in estuarine conditions, where fluctuating conditions affected diatom assemblages both at spatial and temporal scale.

  17. Gastropod shells: a dynamic resource that helps shape benthic community structure. [Calliactis tricolor; Pagurus pollicaris; Calappa flammea; Octopus joubini; Panulirus argus

    Energy Technology Data Exchange (ETDEWEB)

    McLean, R

    1983-01-01

    Empty gastropod shells are an important resource for many animals in shallow benthic marine communities. Shells provide shelter for hermit crabs, octopuses, and fishes, provide attachment substratum for hermit crab symbionts, and directly or indirectly modify hermit crab predation. Creation of an empty shell due to predation of one gastropod on another and acquisition of that shell by a hermit crab are two key events in the subsequent use of that shell. Shells of different gastropod species and the species of hermit crab acquiring them affect the symbiont complement that attaches to the shell, which in turn may affect future shell use by other symbionts. Certain shell types worn by the hermit crab, Pagurus pollicaris Say, are positively associated with the symbiotic sea anemone, Calliactis tricolor (Lesueur), which protects the hermit crab from predation by the crab, Calappa flammea (Herbst), and possibly from the octopus, Octopus joubini Robson. Shells of other species of gastropods are resistant to being crushed by the spiny lobster, Panulirus argus (Latreille). The inter- and intraspecific interactions centered on the gastropod shell are termed a ''habitat web.'' The potential of the shell to limit the size and distribution of animal populations demonstrates how this resource helps shape community structure.

  18. Functional response of midsummer planktonic and benthic communities in the Neva Estuary (eastern Gulf of Finland to anthropogenic stress

    Directory of Open Access Journals (Sweden)

    Sergey M. Golubkov

    2003-03-01

    Full Text Available Long-term hydrobiological research has shown that the functioning of the ecosystem of the Neva Estuary, one of the largest Baltic estuaries, has changed greatly since the beginning of the 20th century. Ineffective local water management in St. Petersburg during thelast twenty years has stimulated the development of a natural "biological plug" in the salt barrier zone in the inner part ofthe estuary and has altered the ecosystem's functioning. These changes include an increase in primary production, in the primary production:organic matter decomposition ratio, and in pelagic-benthic coupling. It has also given rise to filamentous algae blooms and intensive secondary pollution in the coastal zone of the Neva Estuary. The primary production of phytoplankton in the inner part of the estuary has reached 2.3 gC m-2, that of the filamentous algae Cladophora glomerata 5.5 gC m-2 these figures are much higher than in other regions of the Gulf of Finland.

  19. Benthic Communities of Low-Order Streams Affected by Acid Mine Drainages: A Case Study from Central Europe

    Directory of Open Access Journals (Sweden)

    Marek Svitok

    2014-05-01

    Full Text Available Only little attention has been paid to the impact of acid mine drainages (AMD on aquatic ecosystems in Central Europe. In this study, we investigate the physico-chemical properties of low-order streams and the response of benthic invertebrates to AMD pollution in the Banská Štiavnica mining region (Slovakia. The studied streams showed typical signs of mine drainage pollution: higher conductivity, elevated iron, aluminum, zinc and copper loads and accumulations of ferric precipitates. Electric conductivity correlated strongly with most of the investigated elements (weighted mean absolute correlation = 0.95 and, therefore, can be recommended as a good proxy indicator for rapid AMD pollution assessments. The diversity and composition of invertebrate assemblages was related to water chemistry. Taxa richness decreased significantly along an AMD-intensity gradient. While moderately affected sites supported relatively rich assemblages, the harshest environmental conditions (pH < 2.5 were typical for the presence of a limited number of very tolerant taxa, such as Oligochaeta and some Diptera (Limnophyes, Forcipomyiinae. The trophic guild structure correlated significantly with AMD chemistry, whereby predators completely disappeared under the most severe AMD conditions. We also provide a brief review of the AMD literature and outline the needs for future detailed studies involving functional descriptors of the impact of AMD on aquatic ecosystems.

  20. Early invasion population structure of quagga mussel and associated benthic invertebrate community composition on soft sediment in a large reservoir

    Science.gov (United States)

    Wittmann, Marion E.; Chandra, Sudeep; Caires, Andrea; Denton, Marianne; Rosen, Michael R.; Wong, Wai Hing; Teitjen, Todd; Turner, Kent; Roefer, Peggy; Holdren, G. Chris

    2010-01-01

    In 2007 an invasive dreissenid mussel species, Dreissena bugensis (quagga mussel), was discovered in Lake Mead reservoir (AZ–NV). Within 2 years, adult populations have spread throughout the lake and are not only colonizing hard substrates, but also establishing in soft sediments at depths ranging from 1 to >100 m. Dreissena bugensis size class and population density distribution differs between basins; cluster analysis revealed 5 adult cohorts within Boulder Basin and Overton Arm but low densities and low cohort survival in the Las Vegas Basin. Regression analysis suggests depth and temperature are not primary controllers of D. bugensis density in Lake Mead, indicating other factors such as sediment type, food availability or other resource competition may be important. Monthly veliger tows showed at least 2 major spawning events per year, with continuous presence of veligers in the water column. Adult mussels have been found in spawn or post-spawn condition in soft sediments in shallow to deep waters (>80 m) indicating the potential for reproduction at multiple depths. Comparisons to a 1986 benthic survey suggest there have been shifts in nondreissenid macroinvertebrate composition; however, it is unclear if this is due to D. bugensis presence. Current distribution of nondreissenid macroinvertebrates is heterogeneous in all 3 basins, and their biodiversity decreased when D. bugensis density was 2500/m2 or greater.

  1. Benthic Macrofaunal Communities at Newly Explored Caribbean Seamounts in the Greater/Lesser Antilles Transition Zone and a Comparison to Nearby Habitats

    Science.gov (United States)

    Demopoulos, A. W.; Bourque, J. R.; Cordes, E. E.; Chaytor, J. D.; Quattrini, A.

    2016-02-01

    Seamounts are topographically and oceanographically complex features with environmental characteristics, including substrate types, carbon flux, and current patterns, that vary greatly within and among seamounts. While seamounts are reputed to be oases and biodiversity hotspots, comparisons across multiple spatial scales of a seamount chain have yet to be explored. Along the margins of the Caribbean Sea basin, numerous seamounts punctuate the seafloor. In 2013 and 2014, we investigated the deep-sea benthic community ecology at Noroît, Dog, and Conrad Seamounts and nearby ridge, bank, and rift environments at depths ranging from 630 to 2930 m. Sediment push cores were collected to quantify macrofaunal (> 300 μm) density, diversity, community composition, grain size, and organic content. In addition, environmental data collected from CTDs and extracted from high resolution multibeam mapping efforts (e.g. slope, rugosity, roughness, slope orientation), allowed us to evaluate the role of microhabitats in structuring these communities. Preliminary results indicate that macrofaunal density across all sites decreased with depth in both seamount and non-seamount sediments, with the highest densities occurring in non-seamount environments. However, macrofaunal density patterns varied on individual seamounts. Macrofaunal densities on shallow seamounts (Conrad and Dog) increased with depth, whereas densities decreased with depth on the deeper Noroît seamount. The relationship between environmental parameters and macrofaunal community structure and biodiversity varied among seamounts and non-seamount environments. This study represents the first investigation of seamount infauna in the region and places this baseline information on seamount faunal biodiversity, spatial distribution of taxa, and overall ecology into a broader biogeographic context.

  2. Metabarcoding monitoring analysis: the pros and cons of using co-extracted environmental DNA and RNA data to assess offshore oil production impacts on benthic communities

    Directory of Open Access Journals (Sweden)

    Olivier Laroche

    2017-05-01

    Full Text Available Sequencing environmental DNA (eDNA is increasingly being used as an alternative to traditional morphological-based identification to characterize biological assemblages and monitor anthropogenic impacts in marine environments. Most studies only assess eDNA which, compared to eRNA, can persist longer in the environment after cell death. Therefore, eRNA may provide a more immediate census of the environment due to its relatively weaker stability, leading some researchers to advocate for the use of eRNA as an additional, or perhaps superior proxy for portraying ecological changes. A variety of pre-treatment techniques for screening eDNA and eRNA derived operational taxonomic units (OTUs have been employed prior to statistical analyses, including removing singleton taxa (i.e., OTUs found only once and discarding those not present in both eDNA and eRNA datasets. In this study, we used bacterial (16S ribosomal RNA gene and eukaryotic (18S ribosomal RNA gene eDNA- and eRNA-derived data from benthic communities collected at increasing distances along a transect from an oil production platform (Taranaki, New Zealand. Macro-infauna (visual classification of benthic invertebrates and physico-chemical data were analyzed in parallel. We tested the effect of removing singleton taxa, and removing taxa not present in the eDNA and eRNA libraries from the same environmental sample (trimmed by shared OTUs, by comparing the impact of the oil production platform on alpha- and beta-diversity of the eDNA/eRNA-based biological assemblages, and by correlating these to the morphologically identified macro-faunal communities and the physico-chemical data. When trimmed by singletons, presence/absence information from eRNA data represented the best proxy to detect changes on species diversity for both bacteria and eukaryotes. However, assessment of quantitative beta-diversity from read abundance information of bacteria eRNA did not, contrary to eDNA, reveal any impact from

  3. Metabarcoding monitoring analysis: the pros and cons of using co-extracted environmental DNA and RNA data to assess offshore oil production impacts on benthic communities

    KAUST Repository

    Laroche, Olivier

    2017-05-17

    Sequencing environmental DNA (eDNA) is increasingly being used as an alternative to traditional morphological-based identification to characterize biological assemblages and monitor anthropogenic impacts in marine environments. Most studies only assess eDNA which, compared to eRNA, can persist longer in the environment after cell death. Therefore, eRNA may provide a more immediate census of the environment due to its relatively weaker stability, leading some researchers to advocate for the use of eRNA as an additional, or perhaps superior proxy for portraying ecological changes. A variety of pre-treatment techniques for screening eDNA and eRNA derived operational taxonomic units (OTUs) have been employed prior to statistical analyses, including removing singleton taxa (i.e., OTUs found only once) and discarding those not present in both eDNA and eRNA datasets. In this study, we used bacterial (16S ribosomal RNA gene) and eukaryotic (18S ribosomal RNA gene) eDNA- and eRNA-derived data from benthic communities collected at increasing distances along a transect from an oil production platform (Taranaki, New Zealand). Macro-infauna (visual classification of benthic invertebrates) and physico-chemical data were analyzed in parallel. We tested the effect of removing singleton taxa, and removing taxa not present in the eDNA and eRNA libraries from the same environmental sample (trimmed by shared OTUs), by comparing the impact of the oil production platform on alpha- and beta-diversity of the eDNA/eRNA-based biological assemblages, and by correlating these to the morphologically identified macro-faunal communities and the physico-chemical data. When trimmed by singletons, presence/absence information from eRNA data represented the best proxy to detect changes on species diversity for both bacteria and eukaryotes. However, assessment of quantitative beta-diversity from read abundance information of bacteria eRNA did not, contrary to eDNA, reveal any impact from the oil

  4. Metabarcoding monitoring analysis: the pros and cons of using co-extracted environmental DNA and RNA data to assess offshore oil production impacts on benthic communities.

    Science.gov (United States)

    Laroche, Olivier; Wood, Susanna A; Tremblay, Louis A; Lear, Gavin; Ellis, Joanne I; Pochon, Xavier

    2017-01-01

    Sequencing environmental DNA (eDNA) is increasingly being used as an alternative to traditional morphological-based identification to characterize biological assemblages and monitor anthropogenic impacts in marine environments. Most studies only assess eDNA which, compared to eRNA, can persist longer in the environment after cell death. Therefore, eRNA may provide a more immediate census of the environment due to its relatively weaker stability, leading some researchers to advocate for the use of eRNA as an additional, or perhaps superior proxy for portraying ecological changes. A variety of pre-treatment techniques for screening eDNA and eRNA derived operational taxonomic units (OTUs) have been employed prior to statistical analyses, including removing singleton taxa (i.e., OTUs found only once) and discarding those not present in both eDNA and eRNA datasets. In this study, we used bacterial (16S ribosomal RNA gene) and eukaryotic (18S ribosomal RNA gene) eDNA- and eRNA-derived data from benthic communities collected at increasing distances along a transect from an oil production platform (Taranaki, New Zealand). Macro-infauna (visual classification of benthic invertebrates) and physico-chemical data were analyzed in parallel. We tested the effect of removing singleton taxa, and removing taxa not present in the eDNA and eRNA libraries from the same environmental sample (trimmed by shared OTUs), by comparing the impact of the oil production platform on alpha- and beta-diversity of the eDNA/eRNA-based biological assemblages, and by correlating these to the morphologically identified macro-faunal communities and the physico-chemical data. When trimmed by singletons, presence/absence information from eRNA data represented the best proxy to detect changes on species diversity for both bacteria and eukaryotes. However, assessment of quantitative beta-diversity from read abundance information of bacteria eRNA did not, contrary to eDNA, reveal any impact from the oil

  5. Ecological assessment of the macrophytes and phytoplankton in El-Rayah Al-Behery, River Nile, Egypt

    Directory of Open Access Journals (Sweden)

    Amany M. Haroon

    2017-09-01

    Full Text Available The present study aimed to assess the effect of ecological factors on distribution and species composition of macrophytes and phytoplankton communities at El-Rayah Al-Behery. Changes in the quantitative and qualitative composition of the macrophytes and phytoplankton communities were detected in relation to season and sampling site. A total of eleven macrophytes and 100 phytoplankton species were identified. Among the macrophytes, the emergent species Echinochloa stagnina was the most dominant and widely distributed. Phytoplankton community is fairly diverse, related to 7 classes, which contains 3 main classes: Bacillariophyceae (28 taxa, Chlorophyceae (33 taxa and Cyanophyceae (23 taxa. According to statistical analysis, occurrence of most macrophytes species were reversely affected by DO, COD, BOD and PO4; and closely correlated with NO2, NO3, Temp. and pH values. However, nitrogen and phosphorus are considered as limiting factors for bacillariohyceae growth (r = 0.7. Both temperature and pH have a positive effect on the growth of chlorophyceae (r = 0.9 and 0.8, respectively; while dissolved oxygen is an important parameter that affects on the growth of cyanphyceae (r = 0.8. In addition, existence of Myriophyllium spicatum was associated with increasing of bacillariohyceae and total phytoplankton density (r = 0.7. However, the presence of Polygonum tomentosum was intensely related with chlorophyceae (r = 0.9 and Potamogeton nodosus and Polygonum tomentosum were positively correlated with cyanphyceae. In conclusion, the investigated area was characterized by different taxonomic composition of macrophytes and phytoplankton communities, which varied as a result of changing in water physiochemical characteristics as well as the interaction between different species. Keywords: Ecological assessment, Phytoplankton, Macrophytes

  6. Similar effects of bottom trawling and natural disturbance on composition and function of benthic communities across habitats

    DEFF Research Database (Denmark)

    van Denderen, Pieter Daniël; Bolam, S.G.; Hiddink, J.G.

    2015-01-01

    communities in similar ways. Both sources of disturbance caused declines in long-living, hard-bodied (exoskeleton) and suspension-feeding organisms. Given these similar impacts, there was no detectable trawling effect on communities exposed to high natural disturbance. Conversely, in 3 out of 5 areas with low...

  7. Observations on marine macrophytes of the republic of Seychelles

    Digital Repository Service at National Institute of Oceanography (India)

    Untawale, A.G.; Jagtap, T.G.

    The distribution of macrophytes was studies from the major islands (Mahe, Praslin and La Digue) of the Seychelles Archipelago. The macrophytes were represented by 72 species of seaweeds, 8 species of mangroves and 6 species of seagrass. The dominant...

  8. Development of a macrophyte-based index of biotic integrity for Minnesota lakes

    Science.gov (United States)

    Beck, M.W.; Hatch, L.K.; Vondracek, B.; Valley, R.D.

    2010-01-01

    Traditional approaches for managing aquatic resources have often failed to account for effects of anthropogenic disturbances on biota that are not directly reflected by chemical and physical proxies of environmental condition. The index of biotic integrity (IBI) is a potentially effective assessment method to integrate ecological, functional, and structural aspects of aquatic systems. A macrophyte-based IBI was developed for Minnesota lakes to assess the ability of aquatic plant communities to indicate environmental condition. The index was developed using quantitative point intercept vegetation surveys for 97 lakes that represent a range of limnological and watershed characteristics. We followed an approach similar to that used in Wisconsin to develop the aquatic macrophyte community index (AMCI). Regional adaptation of the AMCI required the identification of species representative of macrophyte communities in Minnesota. Metrics and scaling methods were also substantially modified to produce a more empirically robust index. Regression analyses indicated that IBI scores reflected statewide differences in lake trophic state (R2 = 0.57, F = 130.3, df = 1, 95, p indicated a unique response of the IBI to human-induced stress separate from a response to natural lake characteristics. The IBI was minimally affected by differences in sample point density as indicated by Monte Carlo analyses of reduced sampling effort. Our analysis indicates that a macrophyte IBI calibrated for Minnesota lakes could be useful for identifying differences in environmental condition attributed to human-induced stress gradients. ?? 2010 Elsevier Ltd.

  9. Effects of habitat-forming species richness, evenness, identity, and abundance on benthic intertidal community establishment and productivity.

    Directory of Open Access Journals (Sweden)

    Julie Lemieux

    Full Text Available In a context of reduced global biodiversity, the potential impacts from the loss of habitat-forming species (HFS on ecosystem structure and functioning must be established. These species are often the main community primary producers and have a major role in the establishment of organisms through facilitation processes. This study focuses on macroalgae and mussels as HFS within an intertidal zone along the St. Lawrence estuary (Quebec, Canada. Over a 16-week period, we manipulated the in situ diversity profile (richness, evenness, identity, and abundance of the dominant HFS (Fucus distichus edentatus, F. vesiculosus, and Mytilus spp. in order to define their role in both the establishment of associated species and community primary production. Contrary to expectation, no general change in HFS richness, evenness, abundance, or identity on associated species community establishment was observed. However, over the study period, the HFS diversity profile modified the structure within the trophic guilds, which may potentially affect further community functions. Also, our results showed that the low abundance of HFS had a negative impact on the primary productivity of the community. Our results suggest that HFS diversity profiles have a limited short-term role in our study habitat and may indicate that biological forcing in these intertidal communities is less important than environmental conditions. As such, there was an opportunistic establishment of species that ensured rapid colonization regardless of the absence, or the diversity profile, of facilitators such as HFS.

  10. The effects of short term exposure to Bass Strait crude oil and Corexit 8667 on benthic community metabolism in Posidonia australis Hook. f. dominated microcosms

    Energy Technology Data Exchange (ETDEWEB)

    Hatcher, A.I.; Larkum, A.W.D.

    1982-03-01

    Microcosms consisting of a sublittoral seagrass meadow from Botany Bay, N.S.W. were maintained in aquaria in a controlled environment room from March to August 1979. Oxygen production and consumption in the microcosms and leaf turnover of the seagrass, Posidonia australis Hook.f. were measured before, during and after a 7-day treatment in June with Bass Strait crude oil and the dispersant Corexit 8667. Four microcosms received oil and two of these received dispersant. The leaf turnover of P. australis was not significantly affected by the addition of oil and dispersant. Photosynthetic oxygen production decreased and respiration increased in the microcosms during treatment. In August, 40 days after treatment, oxygen production rates and P/R ratios in the oil-treated microcosms were higher than rates measured before treatment. The oil-and-dispersant-treated microcosms did not show this trend. The results of this study indicate that a more severe stress is placed on the P. australis dominated benthic community by oil and dispersant than by oil alone.

  11. Chemosynthetic trophic support for the benthic community at an intertidal cold seep site at Mocha Island off central Chile

    Science.gov (United States)

    Sellanes, Javier; Zapata-Hernández, Germán; Pantoja, Silvio; Jessen, Gerdhard L.

    2011-12-01

    We analyzed C and N stable isotope ratios of benthic fauna and their potential food sources at an intertidal methane seep site and a control site without emanation at Mocha Island (central Chile). The objective was to trace the origin of the main food sources used by the local heterotrophic fauna, based on the hypothesis that chemosynthetic production could be partially fueling the local food web at the seep site. Food sources sampled at both sites included macroalgae, particulate organic matter and bacteria-like filaments found growing over the red algae Gelidium lingulatum within the areas of active methane release. At the control site, located 11 km away from the gas emanation, fauna exhibited moderate δ 13C values ranging from -16.2‰ (in a nereid polychaete) to -14.8‰ (in a cirolanid isopod), which were consistent with those of the potential photosynthetic food sources sampled at this site (-20.2 to -16.5‰). δ 13C values of the photosynthetic food sources at the seep site similarly ranged between -25.4 and -17.9‰. However, a portion of the animals at this site were consistently more 13C-depleted, with δ 13C values close to that of the seeping methane (-43.8‰) and the bacteria-like filaments (-39.2 ± 2.5‰) also collected at this site. Specific examples were the Marphysa sp. polychaetes (δ 13C = -44.7 ± 0.6‰), the Schistomeringos sp. dorvilleid polychaetes (δ 13C = -42.9‰), and the tanaid crustacean Zeuxo marmoratus (δ 13C = -37.3 ± 0.2‰). The significantly higher δ 13C values of the herbivorous gastropod Tegula atra at the seep site (-29.3 ± 3.1‰) than at the control site (-12.6 ± 0.3‰) also indicated differences among sites of the preferred carbon sources of this species. Mixing model estimates indicate that at the seep site bacteria-like filaments could be contributing up to ˜60% of the assimilated diet of selected invertebrates. Furthermore, several indicators of trophic structure, based in isotopic niche metrics, indicate a

  12. Shifts in the metabolic function of a benthic estuarine microbial community following a single pulse exposure to silver nanoparticles

    International Nuclear Information System (INIS)

    Echavarri-Bravo, Virginia; Paterson, Lynn; Aspray, Thomas J.; Porter, Joanne S.; Winson, Michael K.; Thornton, Barry; Hartl, Mark G.J.

    2015-01-01

    The increasing use of silver nanoparticles (AgNPs) as a biocidal agent and their potential accumulation in sediments may threaten non-target natural environmental bacterial communities. In this study a microcosm approach was established to investigate the effects of well characterized OECD AgNPs (NM-300) on the function of the bacterial community inhabiting marine estuarine sediments (salinity 31‰). The results showed that a single pulse of NM-300 AgNPs (1 mg L −1 ) that led to sediment concentrations below 6 mg Ag kg −1 dry weight inhibited the bacterial utilization of environmentally relevant carbon substrates. As a result, the functional diversity changed, but recovered after 120 h under the experimental conditions. This microcosm study suggests that AgNPs under environmentally relevant experimental conditions can negatively affect bacterial function and provides an insight into the understanding of the bacterial community response and resilience to AgNPs exposure, important for informing relevant regulatory measures. - Highlights: • AgNPs affected the bacterial community function in estuarine marine sediments. • AgNPs inhibited the bacterial utilization of environmentally relevant substrates. • Heterotrophic bacterial groups showed resilience to AgNPs after 120 h exposure. • AgNPs did not affect the bacterial community structure in sediments. - AgNPs inhibited the bacterial utilization of environmentally relevant substrates and caused temporary shifts in the bacterial functional diversity in marine estuarine sediments

  13. Response of littoral macrophytes to water level fluctuations in a storage reservoir

    Directory of Open Access Journals (Sweden)

    Krolová M.

    2013-05-01

    Full Text Available Lakes and reservoirs that are used for water supply and/or flow regulations have usually poorly developed littoral macrophyte communities, which impairs ecological potential in terms of the EU Water Framework Directive. The aim of our study was to reveal controlling factors for the growth of littoral macrophytes in a storage reservoir with fluctuating water level (Lipno Reservoir, Czech Republic. Macrophytes occurred in this reservoir only in the eulittoral zone i.e., the shoreline region between the highest and the lowest seasonal water levels. Three eulittoral sub-zones could be distinguished: the upper eulittoral with a stable community of perennial species with high cover, the middle eulittoral with relatively high richness of emergent and amphibious species present at low cover values, and the lower eulittoral devoid of permanent vegetation. Cover and species composition in particular sub-zones were primarily influenced by the duration and timing of flooding, followed by nutrient limitation and strongly reducing conditions in the flooded organic sediment. Our results stress the ecological importance of eulittoral zone in reservoirs with fluctuating water levels where macrophyte growth can be supported by targeted management of water level, thus helping reservoir managers in improving the ecological potential of this type of water bodies.

  14. Phytoremediation potential of aquatic macrophyte, Azolla.

    Science.gov (United States)

    Sood, Anjuli; Uniyal, Perm L; Prasanna, Radha; Ahluwalia, Amrik S

    2012-03-01

    Aquatic macrophytes play an important role in the structural and functional aspects of aquatic ecosystems by altering water movement regimes, providing shelter to fish and aquatic invertebrates, serving as a food source, and altering water quality by regulating oxygen balance, nutrient cycles, and accumulating heavy metals. The ability to hyperaccumulate heavy metals makes them interesting research candidates, especially for the treatment of industrial effluents and sewage waste water. The use of aquatic macrophytes, such as Azolla with hyper accumulating ability is known to be an environmentally friendly option to restore polluted aquatic resources. The present review highlights the phytoaccumulation potential of macrophytes with emphasis on utilization of Azolla as a promising candidate for phytoremediation. The impact of uptake of heavy metals on morphology and metabolic processes of Azolla has also been discussed for a better understanding and utilization of this symbiotic association in the field of phytoremediation.

  15. Biogeographic characterization of fish and benthic communities, St Thomas, US Virgin Islands 2012-06-12 to 2012-06-22 (NODC Accession 0125418)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This fish and benthic composition database is the result of a multifaceted effort described below. The intent of this work is five fold: 1) To spatially characterize...

  16. National Coral Reef Monitoring Program: Assessment of coral reef benthic communities in Puerto Rico from 2014-05-19 to 2014-12-03 (NCEI Accession 0151729)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic data collection for the National Coral Reef Ecosystem Monitoring Program (NCRMP) consists of two survey types: the Line Point-Intercept (LPI) method and the...

  17. Biogeographic characterization of fish and benthic communities, Parguera, Puerto Rico 2000-08-21 to 2009-08-21 (NODC Accession 0125202)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This fish and benthic composition database is the result of a multifaceted effort described below. The intent of this work is five fold: 1) To spatially characterize...

  18. Biogeographic characterization of fish and benthic communities, Parguera, Puerto Rico 2010-08-10 to 2012-09-21 (NODC Accession 0125201)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This fish and benthic composition database is the result of a multifaceted effort described below. The intent of this work is five fold: 1) To spatially characterize...

  19. Indirect effects of predators control herbivore richness and abundance in a benthic eelgrass (Zostera marina) mesograzer community.

    Science.gov (United States)

    Amundrud, Sarah L; Srivastava, Diane S; O'Connor, Mary I

    2015-07-01

    Herbivore communities can be sensitive to changes in predator pressure (top-down effects) and resource availability (bottom-up effects) in a wide range of systems. However, it remains unclear whether such top-down and bottom-up effects reflect direct impacts of predators and/or resources on herbivores, or are indirect, reflecting altered interactions among herbivore species. We quantified direct and indirect effects of bottom-up and top-down processes on an eelgrass (Zostera marina) herbivore assemblage. In a field experiment, we factorially manipulated water column nutrients (with Osmocote(™) slow-release fertilizer) and predation pressure (with predator exclusion cages) and measured the effects on herbivore abundance, richness and beta diversity. We examined likely mechanisms of community responses by statistically exploring the response of individual herbivore species to trophic manipulations. Predators increased herbivore richness and total abundance, in both cases through indirect shifts in community composition. Increases in richness occurred through predator suppression of common gammarid amphipod species (Monocorophium acherusicum and Photis brevipes), permitting the inclusion of rarer gammarid species (Aoroides columbiae and Pontogeneia rostrata). Increased total herbivore abundance reflected increased abundance of a caprellid amphipod species (Caprella sp.), concurrent with declines in the abundance of other common species. Furthermore, predators decreased beta diversity by decreasing variability in Caprella sp. abundance among habitat patches. Osmocote(™) fertilization increased nutrient concentrations locally, but nutrients dissipated to background levels within 3 m of the fertilizer. Nutrient addition weakly affected the herbivore assemblage, not affecting richness and increasing total abundance by increasing one herbivore species (Caprella sp.). Nutrient addition did not affect beta diversity. We demonstrated that assemblage-level effects of

  20. Occurrence of polycyclic aromatic hydrocarbons below coal-tar-sealed parking lots and effects on stream benthic macroinvertebrate communities

    Energy Technology Data Exchange (ETDEWEB)

    Scoggins, M.; McClintock, N.L.; Gosselink, L.; Bryer, P. [City Austin, Austin, TX (United States)

    2007-12-15

    Parking-lot pavement sealants recently have been recognized as a major source of polycyclic aromatic hydrocarbons (PAHs) in urban stream sediments in Austin, Texas. Laboratory and field studies have shown that PAHs in sediments can be toxic to aquatic organisms and can degrade aquatic communities. After identifying increases in concentrations of PAHs in sediments below seal-coated parking lots, we investigated whether the increases had significant effects on stream biota in 5 Austin streams. We sampled sediment chemistry and biological communities above and below the point at which stormwater runoff from the parking lots discharged into the streams, thus providing 5 upstream reference sites and 5 downstream treatment sites. Differences between upstream and downstream concentrations of total PAH ranged from 3.9 to 32 mg/kg. Analysis of the species occurrence data from pool and riffle habitats indicated a significant decrease in community health at the downstream sites, including decreases in richness, intolerant taxa, Diptera taxa, and density. In pool sediments, Chironomidae density was negatively correlated with PAH concentrations, whereas Oligochaeta density responded positively to PAH concentrations. In general, pool taxa responded more strongly than riffle taxa to PAHs, but riffle taxa responded more broadly than pool taxa. Increases in PAH sediment-toxicity units between upstream and downstream sites explained decreases in taxon richness and density in pools between upstream and downstream sites.

  1. Benthic communities in chemical munitions dumping site areas within the Baltic deeps with special focus on nematodes

    Science.gov (United States)

    Kotwicki, Lech; Grzelak, Katarzyna; Bełdowski, Jacek

    2016-06-01

    Assessment of biological effects of chemical warfare agents (CWAs) dumped in the Baltic Sea has been one of the tasks of the Chemical Munitions Search & Assessment (CHEMSEA) project. Three sites have been selected for investigation: Bornholm Deep, Gotland Deep and Gdansk Deep. Fauna collected from these locations were compared with the reference area located between the studied regions at similar depths below 70 m. In total, four scientific cruises occurred in different seasons between 2011 and 2013. The total lack of any representatives of macrozoobenthos in all of the investigated dumping sites was noted. As a practical matter, the Baltic deeps were inhabited by nematodes as the only meiofauna representatives. Therefore, nematodes were used as a key group to explore the faunal communities inhabiting chemical dumping sites in the Baltic deeps. In total, 42 nematode genera belonging to 18 families were identified, and the dominant genus was Sabatieria (Comesomatidae), which constituted 37.6% of the overall nematode community. There were significant differences in nematode community structure (abundance and taxa composition) between the dumping areas and the reference site (Kruskal-Wallis H=30.96, pnematode assemblages could mirror the environmental conditions.

  2. Eutrophication and Dreissena invasion as drivers of biodiversity: a century of change in the mollusc community of Oneida Lake.

    Directory of Open Access Journals (Sweden)

    Vadim A Karatayev

    Full Text Available Changes in nutrient loading and invasive species are among the strongest human-driven disturbances in freshwater ecosystems, but our knowledge on how they affect the biodiversity of lakes is still limited. We conducted a detailed historical analysis of the mollusc community of Oneida Lake based on our comprehensive lakewide study in 2012 and previous surveys dating back to 1915. In the early 20th century, the lake had a high water clarity, with abundant macrophytes and benthic algae, and hosted the most diverse molluscan community in New York State, including 32 gastropod and 9 unionid species. By the 1960s, lake turbidity increased during a period of anthropogenic eutrophication, resulting in a 38% decline in species richness and a 95% reduction in abundance of native gastropods grazing on benthic algae. Following the invasion of Dreissena spp. in 1991 and subsequent increases in water clarity, native gastropod species richness expanded by 37% and abundance increased 20-fold by 2012. In contrast, filter-feeding unionids were unaffected by increased turbidity during the period of eutrophication but were extirpated by dreissenids. Through contrasting effects on turbidity, eutrophication and Dreissena spp. have likely driven the observed changes in native grazing gastropods by affecting the abundance of light-limited benthic algae. Given the high species richness and ecological importance of benthic grazers, monitoring and managing turbidity is important in preserving molluscan diversity.

  3. Herbivory on freshwater and marine macrophytes

    NARCIS (Netherlands)

    Bakker, Elisabeth S.; Wood, Kevin A.; Pagès, Jordi F.; Veen, G.F.; Christianen, Marjolijn J.A.; Santamaría, Luis; Nolet, Bart A.; Hilt, Sabine

    2016-01-01

    Until the 1990s, herbivory on aquatic vascular plants was considered to be of minor importance, and the predominant view was that freshwater and marine macrophytes did not take part in the food web: their primary fate was the detritivorous pathway. In the last 25 years, a substantial body of

  4. Possible recovery of Acropora palmata (Scleractinia:Acroporidae within the Veracruz Reef System, Gulf of Mexico: a survey of 24 reefs to assess the benthic communities

    Directory of Open Access Journals (Sweden)

    Elizabeth A. Larson

    2014-09-01

    Full Text Available Recent evidence shows that Acropora palmata within the Veracruz Reef System, located in the southwestern Gulf of Mexico, may be recovering after the die off from the flooding of the Jamapa River and a dramatic cold water event in the 1970s. Since this decline, few surveys have documented the status of A. palmata. The 28 named reefs in the system are divided into 13 northern and 15 southern groups by the River. Between 2007 and 2013, we surveyed 24 reefs to assess the benthic communities. Seven of the 11 reefs surveyed in the northern group and all in the southern group had A. palmata. Colonies were typically found on the windward side of the reefs in shallow waters along the reef edges or crest. We also recorded colony diameter and condition along belt transects at two reefs in the north (Anegada de Adentro and Verde and two in the south (Periferico and Sargazo, between 2011 and 2013. In addition, eight permanent transects were surveyed at Rizo (south. A total of 1 804 colonies were assessed; densities ranged from 0.02 to 0.28 colonies/m² (mean (±SD, colony diameter of 58 ± 73cm, and 89 ± 18% live tissue per colony. Total prevalence of predation by damselfish was 5%, by snails 2%, and <1% by fireworms, disease prevalence was <3%. Size frequency distributions indicated that all of the sites had a moderate to high spawning potential, 15-68% of the colonies at each site were mature, measuring over 1 600cm². The presence of these healthy and potentially reproductive colonies is important for species recovery, particularly because much of the greater Caribbean still shows little to no signs of recovery. Conservation and management efforts of these reefs are vital.

  5. Insights into the benthic communities response to the inflow of Black Sea mesotrophic waters in the North Aegean Sea

    Science.gov (United States)

    Lampadariou, Nikolaos; Sevastou, Katerina; Podaras, Dimitrios; Tselepides, Anastasios

    2017-10-01

    The effects of the Dardanelles inflow of buoyant, modified Black Sea waters (BSW) of low salinity and temperature, on the meio- and macrobenthic communities of the north Aegean ecosystem was investigated during two cruises in October 2013 and March 2014. Sediment samples were collected from two stations subjected to the BSW effect, one shallow and one deep north of the Dardanelles Straits, and from two stations of similar bathymetry, which were considered to be outside the influence of BSW and were located to the south of the Dardanelles Straits. Results suggest that there is an effect of the BSW on benthos, as both meiofaunal and macrofaunal standing stocks were lower at the most distant, and therefore least affected from the inflow, station, and higher at the station of similar bathymetry which was affected the most by the BSW inflow. Univariate and multivariate non-parametric analyses (nMDS, PERMANOVA) provided further support, indicating differences between the two areas (North vs. South) in the case of the deep stations, while differences between depth categories were evident in the area outside the BSW influence zone. Distance-based linear modeling (DISTLM) indicated that meiofauna correlated with proxies of food availability and sediment characteristics. Macrofauna, on the other hand, showed a rather high significant correlation with depth only. Nematode species composition was statistically significant different between depth categories only, yet the nMDS ordination clearly separated the deep southern station from the rest, with non-selective deposit feeders dominating the stations under the influence of the BSW, and epistratum feeders being important at the stations outside the influence of the BSW. It is concluded that both the meiofaunal and macrofaunal communities at the northern stations benefit from a constant input of high amounts of organic matter to the seafloor, while those at the southern area may be occasionally affected by the thermohaline BSW

  6. AMEG: the new SETAC advisory group on aquatic macrophyte ecotoxicology.

    Science.gov (United States)

    Arts, Gertie; Davies, Jo; Dobbs, Michael; Ebke, Peter; Hanson, Mark; Hommen, Udo; Knauer, Katja; Loutseti, Stefania; Maltby, Lorraine; Mohr, Silvia; Poovey, Angela; Poulsen, Véronique

    2010-05-01

    Primary producers play critical structural and functional roles in aquatic ecosystems; therefore, it is imperative that the potential risks of toxicants to aquatic plants are adequately assessed in the risk assessment of chemicals. The standard required macrophyte test species is the floating (non-sediment-rooted) duckweed Lemna spp. This macrophyte species might not be representative of all floating, rooted, emergent, and submerged macrophyte species because of differences in the duration and mode of exposure; sensitivity to the specific toxic mode of action of the chemical; and species-specific traits (e.g., duckweed's very short generation time). These topics were addressed during the workshop entitled "Aquatic Macrophyte Risk Assessment for Pesticides" (AMRAP) where a risk assessment scheme for aquatic macrophytes was proposed. Four working groups evolved from this workshop and were charged with the task of developing Tier 1 and higher-tier aquatic macrophyte risk assessment procedures. Subsequently, a SETAC Advisory Group, the Macrophyte Ecotoxicology Group (AMEG) was formed as an umbrella organization for various macrophyte working groups. The purpose of AMEG is to provide scientifically based guidance in all aspects of aquatic macrophyte testing in the laboratory and field, including prospective as well as retrospective risk assessments for chemicals. As AMEG expands, it will begin to address new topics including bioremediation and sustainable management of aquatic macrophytes in the context of ecosystem services.

  7. Benthic-planktonic coupling, regime shifts, and whole-lake primary production in shallow lakes.

    Science.gov (United States)

    Genkai-Kato, Motomi; Vadeboncoeur, Yvonne; Liboriussen, Lone; Jeppesen, Erik

    2012-03-01

    Alternative stable states in shallow lakes are typically characterized by submerged macrophyte (clear-water state) or phytoplankton (turbid state) dominance. However, a clear-water state may occur in eutrophic lakes even when macrophytes are absent. To test whether sediment algae could cause a regime shift in the absence of macrophytes, we developed a model of benthic (periphyton) and planktonic (phytoplankton) primary production using parameters derived from a shallow macrophyte-free lake that shifted from a turbid to a clear-water state following fish removal (biomanipulation). The model includes a negative feedback effect of periphyton on phosphorus (P) release from sediments. This in turn induces a positive feedback between phytoplankton production and P release. Scenarios incorporating a gradient of external P loading rates revealed that (1) periphyton and phytoplankton both contributed substantially to whole-lake production over a broad range of external P loading in a clear-water state; (2) during the clear-water state, the loss of benthic production was gradually replaced by phytoplankton production, leaving whole-lake production largely unchanged; (3) the responses of lakes to biomanipulation and increased external P loading were both dependent on lake morphometry; and (4) the capacity of periphyton to buffer the effects of increased external P loading and maintain a clear-water state was highly sensitive to relationships between light availability at the sediment surface and the of P release. Our model suggests a mechanism for the persistence of alternative states in shallow macrophyte-free lakes and demonstrates that regime shifts may trigger profound changes in ecosystem structure and function.

  8. Benthic metabolism and denitrification in a river reach: a comparison between vegetated and bare sediments

    Directory of Open Access Journals (Sweden)

    Pierluigi VIAROLI

    2009-02-01

    Full Text Available This study aims at comparing biogeochemical processes in a Vallisneria spiralis meadow and in unvegetated sediments in the upper reach of the Mincio River (Northern Italy. The main hypothesis of this work is that meadows of rooted macrophytes affect benthic metabolism, enhancing capacity to retain nutrients (assimilation and dissipate (denitrification nitrogen loadings. In order to highlight how plants affect benthic processes in the riverbed, oxygen, dissolved inorganic carbon (DIC, soluble reactive phosphorus (SRP and inorganic nitrogen fluxes, together with denitrification rates, were measured from February to November 2007 in intact cores collected from stands of V. spiralis and bare sediments. V. spiralis biomass, elemental composition and growth rates were concurrently measured. Macrophyte biomass ranged from 60 to 120 g m-2 (as dry matter; growth rates followed a seasonal pattern from 0.001 in winter up to 0.080 d-1 in summer. On an annual basis, the macrophyte meadow was autotrophic with net O2 production and dissolved inorganic carbon uptake, while the bare sediment was net heterotrophic. The concurrent N assimilation by macrophytes and losses through denitrification led to similar N uptake/dissipation rates, up to 2500 mmol m-2 y-1. Under the very high NO3 - concentrations of the Mincio River, the competition between primary production and denitrification processes was also avoided. A significant ammonium regeneration from sediments to the water column occurred in the V. spiralis meadow, where plant debris and particulate matter accumulated. Here, SRP was also released into the water column, whilst in the bare sediment SRP fluxes were close to zero. Overall, V. spiralis affected the benthic metabolism enhancing the ecosystem capacity to control nitrogen contamination. However, the actual N removal rates were not sufficient to mitigate the pollution discharge.

  9. Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California: 2014

    Science.gov (United States)

    Cain, Daniel J.; Thompson, Janet K.; Crauder, Jeff; Parcheso, Francis; Stewart, Robin; Kleckner, Amy E.; Dyke, Jessica; Hornberger, Michelle I.; Luoma, Samuel N.

    2015-01-01

    Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer (km) south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in South San Francisco Bay, Calif. This report includes the data collected by U.S. Geological Survey (USGS) scientists for the period January 2014 to December 2014. These append to long-term datasets extending back to 1974, and serve as the basis for the City of Palo Alto’s Near-Field Receiving Water Monitoring Program, initiated in 1994. 

  10. Influence of unreasoned economic activity on the condition of macrophytes of the Bol’shoye Goluboye Lake

    Science.gov (United States)

    Palagushkina, O. V.; Zaripova, N. R.; Mingazova, N. M.; Yarutkin, T. O.

    2018-01-01

    The ecosystem of Lake Bolshoye Goluboe had undergone a strong anthropogenic impact in 2013 as a result of the implementation of the dam reconstruction project. Studies in 2014 have shown that the implementation of the project for the reconstruction of the Bolshoye Goluboe dam has negatively affected on the species richness of macrophytes. The total species composition of the lake and species richness of the water core decreased twofold, Hippuris vulgaris L., Zannichellia palustris L, Ceratophyllum demersum L., and the species listed in the Red Book of the Republic of Tatarstan - Batrachium circinatum (Sibth.) Spach disappeared from the species composition. The area occupied by macrophyte communities has decreased by 55%.

  11. AMEG: the new SETAC advisory group on aquatic macrophyte ecotoxicology

    OpenAIRE

    Arts, G.; Davies, J.; Dobbs, M.; Ebke, P.; Hanson, M.; Hommen, U.; Knauer, K.; Loutseti, S.; Maltby, L.; Mohr, S.; Poovey, A.; Poulsen, V.

    2010-01-01

    \\ud Introduction and background\\ud \\ud Primary producers play critical structural and functional roles in aquatic ecosystems; therefore, it is imperative that the potential risks of toxicants to aquatic plants are adequately assessed in the risk assessment of chemicals. The standard required macrophyte test species is the floating (non-sediment-rooted) duckweed Lemna spp. This macrophyte species might not be representative of all floating, rooted, emergent, and submerged macrophyte species be...

  12. AMEG: the new SETAC advisory group on auqatic macrophyte ecotoxicology

    OpenAIRE

    Arts, G.H.P.; Davies, J.; Dobbs, M.; Ebke, P.; Hanson, M.A.

    2010-01-01

    ntroduction and background Primary producers play critical structural and functional roles in aquatic ecosystems; therefore, it is imperative that the potential risks of toxicants to aquatic plants are adequately assessed in the risk assessment of chemicals. The standard required macrophyte test species is the floating (non-sediment-rooted) duckweed Lemna spp. This macrophyte species might not be representative of all floating, rooted, emergent, and submerged macrophyte species because of dif...

  13. AN INTERACTIVE DEMONSTRATION OF 3D COMPUTER-AIDED TOMOGRAPHY IMAGERY FOR INTERPRETING AND QUANTIFYING ANTHROPOGENIC IMPACTS TO MARINE BENTHIC COMMUNITIES

    Science.gov (United States)

    Two dimensional CT analysis has allowed the quantification of biologically derived structures (tubes and tunnels) within benthic sediments. The percent tube and tunnel area (PTTA) and the sediment bulk density (SXA) resulting from these activities have been shown be to highly cor...

  14. Hydrologic cycle and dynamics of aquatic macrophytes in two intermittent rivers of the semi-arid region of Brazil

    Directory of Open Access Journals (Sweden)

    F. Pedro

    Full Text Available The dynamics of aquatic macrophytes in intermittent rivers is generally related to the characteristics of the resistance and resilience of plants to hydrologic disturbances of flood and drought. In the semi-arid region of Brazil, intermittent rivers and streams are affected by disturbances with variable intensity, frequency, and duration throughout their hydrologic cycles. The aim of the present study is to determine the occurrence and variation of biomass of aquatic macrophyte species in two intermittent rivers of distinct hydrologic regimes. Their dynamics were determined with respect to resistance and resilience responses of macrophytes to flood and drought events by estimating the variation of biomass and productivity throughout two hydrologic cycles. Twenty-one visits were undertaken in the rewetting, drying, and drought phases in a permanent puddle in the Avelós stream and two temporary puddles in the Taperoá river, state of Paraíba, Northeast Brazil. The sampling was carried out by using the square method. Floods of different magnitudes occurred during the present study in the river and in the stream. The results showed that floods and droughts are determining factors in the occurrence of macrophytes and in the structure of their aquatic communities. The species richness of the aquatic macrophyte communities was lower in the puddles of the river and stream subject to flood events, when compared to areas where the run-off water is retained. At the beginning of the recolonization process, the intensity of the floods was decisive in the productivity and biomass of the aquatic macrophytes in the Taperoá river and the Avelós stream. In intermediate levels of disturbance, the largest values of productivity and biomass and the shortest time for starting the recolonization process occurred.

  15. Review of alien marine macrophytes in Tunisia

    Directory of Open Access Journals (Sweden)

    Y. R. SGHAIER

    2015-01-01

    Full Text Available In the present study, the list of alien marine macrophytes introduced into Tunisia was updated in the light of available data and new observations. A total of 27 alien marine macrophytes have been recorded so far from Tunisia: 18 Rhodophyta, 3 Ochrophyta, 5 Chlorophyta and 1 Magnoliophyta. For each species, the locality (-ies, the year (or period and the source of the first observation in Tunisia are given. The distribution and the status (casual, cryptogenic, established or questionable of species in Tunisia were evaluated and, where appropriate, discussed. Among them, Hypnea cornuta is reported for the first time from Tunisia. Fourteen alien marine macrophytes are established, whereas seven cryptogenic and two casual species require further investigation. Eleven species are considered as invasive or potentially invasive in the Mediterranean Sea: Acrothamnion preissii, Asparagopsis armata, A. taxiformis Indo-Pacific lineage, Hypnea cornuta, Lophocladia lallemandii, Womersleyella setacea, Caulerpa chemnitzia, C. cylindracea, C. taxifolia, Codium fragile subsp. fragile and Halophila stipulacea. Finally, the case of four questionable species is also discussed.

  16. Variation in composition of macro-benthic invertebrates as an ...

    African Journals Online (AJOL)

    Mo

    1 Makerere University Institute of Environment & Natural Resources, P.O. Box 7062 Kampala-Uganda ... benthic macro-invertebrates communities were evaluated using GIS techniques along an ...... Kendall Hunt Publishing Company, Iowa.

  17. Infaunal macrobenthic community of soft bottom sediment in a tropical shelf

    Digital Repository Service at National Institute of Oceanography (India)

    Jayaraj, K.A.; Jacob, J.; DineshKumar, P.K.

    Studies of benthic communities in tropical shelf waters are limited. In this study, we deal with the infaunal benthic community of soft bottom sediment of the tropical eastern Arabian Sea shelf. Benthic macroinfauna was sampled with a Smith...

  18. Oligochaeta (Annelida, Clitellata in the Aquatic Macrophytes in Dam of Ribeirão of Anhumas Screamers (Américo Brasiliense-Sp

    Directory of Open Access Journals (Sweden)

    Nathalie Aparecida De Oliveira Sanches

    2014-06-01

    Full Text Available Macrophytes have different morphological structural complexities, offering to animals the availability of various niches. These plants are also an important substrate for the development of periphyton, which has a high nutritional value and is one of the main foods of aquatic invertebrates, mainly Naididae. This study aimed at examinining the diversity of Oligochaeta community in macrophytes belonging to genus Egeria sp. and Salvinia sp., in lagoons of Ribeirão das Anhumas dam. These macrophytes have distinct three-dimensional characteristics and different habits, being Egeria fixed submerged and Salvinia free floating. The collections of macrophytes were carried out between the months of August 2012 and April 2013. Samples of 100g (wet weight of each genus were taken from plant biomass and the removal of the plants from the environment was made with the aid of a sieve with 0.21 mm mesh. Considering the two macrophytes analyzed, Egeria sp. was the one that presented greater diversity, richness and abundance in relation to Salvinia sp. These results demonstrate that macrophytes are important for the establishment of oligochaetes, mainly providing protection and food, and possibly the morphology and habit of the plants are the most influential factors in the association of oligofauna with these plants.

  19. MACROPHYTE RICHNESS AND AQUATIC VEGETATION COMPLEXITY OF THE LAKE IDRO (NORTHERN ITALY

    Directory of Open Access Journals (Sweden)

    R. Bolpagni

    2013-04-01

    Full Text Available A detailed survey was performed to examine the floristic richness and the structural complexity, spatial patterns and conservation value of aquatic plant communities within the littorals of Lake Idro (northern Italy. During the summers of 2010-2011 we proceeded to characterize aquatic macrophyte meadows applying standardized procedures using transects (44 and plots (49 arrayed perpendicular to the shoreline and randomly positioned within the vegetated belt, respectively. Lake Idro is characterized by rather high floristic richness (20 macrophytes but low levels of vegetation structural complexity (8 vegetation units. Nevertheless, a clear zonation of the littoral vegetation was identified with two main macro-layers: a deeper layer (between 6-10 m of depth dominated by Chara globularis and an upper one (from 6 m of depth to water-air atmosphere mainly colonized by alien elodeids (mainly Elodea nuttallii and Lagarosiphon major. For the first time a complete floristic-vegetation analysis of the Lake Idro was presented. Our data confirm the poor ecological status of the basin, even though the lacustrine vegetation can be considered of conservation concern. Further investigations are needed to improve present evaluations, especially with respect to the impact of eutrophication on macrophytic communities.

  20. Species pool versus site limitations of macrophytes in urban waters

    DEFF Research Database (Denmark)

    Vermonden, K.; Leuven, R.S.E.W.; van der Velde, G.

    2010-01-01

    of species expected from species-area relationships of artificial water bodies in rural areas. In urban areas, the number of macrophyte species was similar to artificial water systems in rural areas. Macrophyte species present in the study areas also were generally found within 20-30 km distance to the study...

  1. Have grass carp driven declines in macrophyte occurrence and ...

    African Journals Online (AJOL)

    The Vaal River, South Africa, historically had a rich diversity of native submerged macrophytes with at least 13 species from 5 families recorded. Over the past 10 years there has been a noticeable reduction in the occurrence and diversity of submerged macrophytes in the river. It is possible that this is linked to the recent ...

  2. Fish Diversity in Relation to Aquatic Macrophytes and ...

    African Journals Online (AJOL)

    An investigation of fish diversity in relation to aquatic macrophytes and physicochemical parameters of Ona Lake in Asaba was carried out within a period of eighteen months. Fish samples were collected fortnightly from three sampling sites using cast, gill and trigger nets. Aquatic macrophytes found in close association with ...

  3. [Algal control ability of allelopathically active submerged macrophytes: a review].

    Science.gov (United States)

    Xiao, Xi; Lou, Li-ping; Li, Hua; Chen, Ying-xu

    2009-03-01

    The inhibitory effect of allelochemicals released by submerged macrophytes on phytoplankton is considered as one of the mechanisms that contribute to the stabilization of clear-water status in shallow lakes. This paper reviewed the research progress in the allelopathy of submerged macrophytes on algae from the aspects of the occurrence frequency and coverage of allelopathically active submerged macrophytes in lakes, and the kinds and allelopathical effects of the allelochemicals released from the macrophytes. The previous researches indicated that allelopathically active submerged macrophyte species such as Myriophyllum, Ceratophyllum, and Elodea were efficient to control phytoplankton, especially when their biomass was high enough, and the dominant algae were sensitive species. The allelochemicals such as hydroxybenzene released by the submerged macrophytes could inhibit the growth of algae. Different phytoplankton species exhibited different sensitivity against allelochemicals, e.g., cyanobacteria and diatom were more sensitive than green algae, while epiphytic species were less sensitive than phytoplankton. Environmental factors such as light, temperature, and nutrients could significantly affect the allelopathical effect of submerged macrophytes. The research of the allelopathy of submerged macrophytes is still at its beginning, and further researches are needed on the effects of environmental factors on the allelopathy, extraction and identification of allelochemicals, selective algal control mechanisms, and metabolism of the allelochmicals.

  4. Environmental study of some metals on several aquatic macrophytes

    African Journals Online (AJOL)

    Aquatic macrophytes can be used in the study of quality of water ecosystems and in monitoring of metals and other pollutants. This study was focused on assessment of metals accumulation in certain aquatic macrophytes (biomonitors), in comparison with water and sediment (abiotic monitors) of the lake. Concentrations of ...

  5. Multielement stoichiometry of submerged macrophytes across Yunnan plateau lakes (China).

    Science.gov (United States)

    Xing, Wei; Wu, Haoping; Shi, Qiao; Hao, Beibei; Liu, Han; Wang, Zhixiu; Liu, Guihua

    2015-05-13

    Stoichiometric homeostasis of element composition is one of the central concepts of ecological stoichiometry. We analyzed concentrations of macroelements (C, N, P, Ca, K, Mg, S), microelements (Cu, Fe, Mn, Mo, Ni, Zn) and beneficial elements (Na, Se, Si) in submerged macrophytes, water and sediments across 20 Yunnan plateau lakes. We predicted that tissue element composition in submerged macrophytes is affected by lake trophic level and taxonomy, and submerged macrophytes have weak stoichiometric homeostasis for all above 16 elements. Canonical discriminant analyses successfully discriminated among trophic level groups and taxa groups. Of all the elements, C, N, P and S most effectively discriminated among trophic level groups across 20 lakes, revealing lake trophic level mostly affect tissue macroelement composition in submerged macrophytes; while Ca, K and Se most effectively discriminated among submerged macrophytes taxa groups, suggesting taxonomy mostly affect compositions of macroelements and beneficial elements in submerged macrophytes. In addition, the stoichiometric homeostatic coefficient of 1/HCa:C for all five taxa of submerged macrophytes were less than zero, suggesting submerged macrophytes in Yunnan plateau lakes have strong Ca stoichiometric homeostasis. Our findings, not only broaden the knowledge of multielement stoichiometric homeostasis, but also help to choose most appropriate lake management strategy.

  6. Depth distribution of benthic dinoflagellates in the Caribbean Sea

    Science.gov (United States)

    Boisnoir, Aurélie; Pascal, Pierre-Yves; Cordonnier, Sébastien; Lemée, Rodolophe

    2018-05-01

    Monitoring of benthic dinoflagellates is usually conducted between sub-surface and 5 m depth, where these organisms are supposed to be in highest abundances. However, only few studies have focused on the small-scale depth distribution of benthic dinoflagellates. In the present study, abundances of dinoflagellates were evaluated on an invasive macrophyte Halophila stipulacea in two coastal sites in Guadeloupe (Caribbean Sea) along a depth gradient from sub-surface to 3 m at Gosier and until 20 m at Rivière Sens during the tropical wet and dry seasons. Species of genus Ostreopsis and Prorocentrum were the most abundant. Depth did not influence total dinoflagellate abundance but several genera showed particular depth-distribution preferences. The highest abundances of Ostreopsis and Gambierdiscus species were estimated preferentially in surface waters, whereas Coolia spp. were found in the same proportions but in deeper waters. Halophila stipulacea biomass was positively correlated with Ostreopsis spp. abundance. Our study suggests that sampling of benthic dinoflagellates should be conducted at different water depths taking into account the presence of the macroalgal substrate as well. In the Caribbean area, special attention should be addressed to the presence of H. stipulacea which tends to homogenize the marine landscape and represents a substrate for hosting dinoflagellate growth.

  7. Estrutura da comunidade de macroinvertebrados bentônicos de um riacho de serra em Itatinga, São Paulo, Brasil Structure of a benthic macroinvertebrates community in a mountain stream in Itatinga, São Paulo, Brazil

    Directory of Open Access Journals (Sweden)

    Ludmilla O. Ribeiro

    2005-09-01

    Full Text Available A comunidade de macroinvertebrados bentônicos de um riacho de terceira ordem foi analisada em duas estações do ano, chuvosa e seca. Substratos artificiais foram amostrados semanalmente, ao longo de 56 dias para a coleta de macroinvertebrados, nas duas estações do ano. A composição da comunidade foi caracterizada por uma baixa diversidade, ou seja, presença de muitas espécies raras e poucas espécies abundantes nas duas estações do ano. Uma alta dominância de Chironomidae (Diptera nas duas estações, seguida de Baetidae (Ephemeroptera e Ancylidae (Mollusca, respectivamente nas estações chuvosa e seca, foi característico. Os resultados obtidos reforçam a grande importância de Chironomidae na comunidade bentônica de riachos e salientam a influência da sazonalidade sobre a estruturação destes organismos.The benthic macroinvertebrates community of a third order stream was studied during the wet and dry seasons. The community was analyzed using artificial substrates sampled weekly during 56 days in each season. The community composition was characterized by low species diversity, with high number of rare species and few abundant species for both seasons. A high dominance of Chinonomidae (Diptera for both seasons, followed by Baetidae (Ephemeroptera and Ancylidae (Mollusca, respectively for the wet and dry seasons, was found. The results reinforced the high importance of Chironomidae and the seasonal effect determining the stream benthic community structure.

  8. Optimum water depth ranges of dominant submersed macrophytes in a natural freshwater lake.

    Science.gov (United States)

    Ye, Bibi; Chu, Zhaosheng; Wu, Aiping; Hou, Zeying; Wang, Shengrui

    2018-01-01

    Macrophytes show a zonal distribution along the lake littoral zone because of their specific preferred water depths while the optimum growth water depths of dominant submersed macrophytes in natural lakes are not well known. We studied the seasonal biomass and frequency patterns of dominant and companion submersed macrophytes along the water depth gradient in Lake Erhai in 2013. The results showed that the species richness and community biomass showed hump-back shaped patterns along the water depth gradient both in polydominant and monodominant communities. Biomass percentage of Potamogenton maackianus showed a hump-back pattern while biomass percentages of Ceratophyllum demersum and Vallisneria natans appeared U-shaped patterns across the water depth gradient in polydominant communities whereas biomass percentage of V. natans increased with the water depth in monodominant communities. Dominant species demonstrated a broader distribution range of water depth than companion species. Frequency and biomass of companion species declined drastically with the water depth whereas those of dominant species showed non-linear patterns across the water depth gradient. Namely, along the water depth gradient, biomass of P. maackianus and V. natans showed hump-back patterns and biomasses of C. demersum displayed a U-shaped pattern in the polydominant communities but biomass of V. natans demonstrated a hump-back pattern in the monodominant communities; frequency of P. maackianus showed a hump-back pattern and C. demersum and V. natans maintained high frequencies in the two types of communities. We can speculate that in Lake Erhai the optimum growth water depths of P. maackianus and C. demersum in the polydominant communities are 2.5-4.5 m and 1-2 m or 5-6 m, respectively and that of V. natans is 3-5 m in the polydominant communities and 2.5-5 m in the monodominant communities. This is the first report that the optimum water depth ranges in the horizontal direction of three

  9. Variation of a benthic heterotrophic bacteria community with different respiratory metabolisms in Coyuca de Benítez coastal lagoon (Guerrero, Mexico

    Directory of Open Access Journals (Sweden)

    María Jesús Ferrara-Guerrero

    2007-03-01

    Full Text Available The fluctuations of the number, biomass and composition of the heterotrophic community were studied daily for two days, according to depth, pH, Eh, O2 and organic carbon concentration within a zone of the canal between the Coyuca de Benítez lagoon (Guerrero, Mexico and the coastal waters. At the three moments of the day studied (6 am, 2 pm and 10 pm, the oxygen concentrations in the overlying water and in the superficial sediment layer were near air-saturation in the diurnal samplings (582 µM at 6 am and 665 µM at 2 pm, and sub-satured during the night (158 µM. In the sediments, the models of vertical distribution of Eh and organic carbon distributions were very irregular due to the bio-perturbation of the benthic, meio- and macrofauna, whose activity allows the superficial organic carbon to migrate towards sediment deeper layers. Vertical distribution of the different viable bacteria populations seems to be related to the hydrodynamic patterns of the communicating canal and sediments heterogeneity. In the sediment column, the heterotrophic bacteria total number varied from 6.8 to 20.3 x 108 cells cm-3. The highest heterotrophic bacterial biomass values were encountered during the diurnal samplings (39.2 µgC.l-1 at 6 am and 34.4 µgC.l-1 at 2 pm and the lowest during the night (9.7 µgC.l-1. The fluctuations of viable heterotrophic bacteria populations with different respiratory metabolisms (aerobic, microaerophilic and anaerobic can be explained by the existence of suboxic microniches that appear when particles of sediment are resuspended due to the water circulation and the benthic infauna excavating activity, that allows the supernatant water oxygen to penetrate through its galleries towards deeper sediment zones. The statistical analysis (Multiple lineal regression model r²≥ 0.5 showed that the on the whole, the hydrological parameters are not influence over the bacterial number and bacterial biomass distribution (r²≤ 0

  10. Estrutura da comunidade de invertebrados bentônicos em dois cursos d'água do Rio Grande do Sul, Brasil Community structure of benthic invertebrates in two watercourses in Rio Grande do Sul State, southern Brazil

    Directory of Open Access Journals (Sweden)

    Alessandra A. P. Bueno

    2003-03-01

    Full Text Available The benthic fauna has an important role in the trophic chain of limnic environments, serving as food for fishes and crustaceans. This work aimed to identify and compare, quantitative and qualitatively, the macrobenthic communities from two watercourses in Rio Grande do Sul State. Samplings were done with a Surber sampler, monthly, from September 1999 to August 2000, in one of the creeks forming Tainhas River(29º15'30,2"S, 50º13'12,5"W, around São Francisco de Paula city and in Mineiro Creek (29º30'0,2"S, 50º46'50"W, around Taquara city. At each sampling point, physical and chemical variables of the waters were registered. In the laboratory, the samples were sorted out and the animals identified and quantified. Dissolved oxigen, pH and stream speed were very similar for both environments, whilst conductivity had extreme values. Insects, crustaceans, acari and molluscs dominated in the samples. Abundance, richness and diversity indexes in Tainhas subsidiary had relatively higher average values than Mineiro Creek. Similarity matrix groupings between sampling units indicate three groups. Our research revealed important characteristics of the ecology and distribution of benthic invertebrates, information that can subsidise future environmental monitoring in the region of São Francisco de Paula and Taquara.

  11. Uranium accumulation by aquatic macrophyte, Pistia stratiotes

    International Nuclear Information System (INIS)

    Bhainsa, K.C.; D'Souza, S.F.

    2012-01-01

    Uranium accumulation by aquatic macrophyte, Pistia stratiotes from aqueous solution was investigated in laboratory condition. The objective was to evaluate the uranium accumulation potential and adopt the plant in uranium containing medium to improve its uptake capacity. The plant was found to tolerate and grow in the pH range of 3-7. Accumulation of uranium improved with increasing pH and the plant could remove 70% uranium from the medium (20 mg/L) within 24 hours of incubation at pH 5-6. Uptake of uranium on either side of this pH range decreased

  12. Predicting estuarine benthic production using functional diversity

    Directory of Open Access Journals (Sweden)

    Marina Dolbeth

    2014-05-01

    Full Text Available We considered an estuarine system having naturally low levels of diversity, but attaining considerable high production levels, and being subjected to different sorts of anthropogenic impacts and climate events to investigate the relationship between diversity and secondary production. Functional diversity measures were used to predict benthic production, which is considered as a proxy of the ecosystem provisioning services. To this end, we used a 14-year dataset on benthic invertebrate community production from a seagrass and a sandflat habitat and we adopted a sequential modeling approach, where abiotic, trait community weighted means (CWM and functional diversity indices were tested by generalized linear models (GLM, and their significant variables were then combined to produce a final model. Almost 90% of variance of the benthic production could be predicted by combining the number of locomotion types, the absolute maximum atmospheric temperature (proxy of the heat waves occurrence, the type of habitat and the mean body mass, by order of importance. This result is in agreement with the mass ratio hypothesis, where ecosystem functions/services can be chiefly predicted by the dominant trait in the community, here measured as CWM. The increase of benthic production with the number of locomotion types may be seen as greater possibility of using the resources available in the system. Such greater efficiency would increase production. The other variables were also discussed in line of the previous hypothesis and taking into account the general positive relationship obtained between production and functional diversity indices. Overall, it was concluded that traits representative of wider possibilities of using available resources and higher functional diversity are related with higher benthic production.

  13. Shade and flow effects on ammonia retention in macrophyte-rich streams: implications for water quality

    International Nuclear Information System (INIS)

    Wilcock, Robert J.; Scarsbrook, Mike R.; Cooke, James G.; Costley, Kerry J.; Nagels, John W.

    2004-01-01

    Controlled releases of NH 4 -N and conservative tracers (Br - and Cl - ) to five reaches of four streams with contrasting macrophyte communities have shown differing retentions, largely as a result of the way plants interact with stream flow and velocity. First-order constants (k) were 1.0-4.8 d -1 and retention of NH 4 -N was 6-71% of amounts added to each reach. Distance travelled before a 50% reduction in concentration was achieved were 40-450 m in three streams under low-flow conditions, and 2400-3800 m at higher flows. Retention (%) of NH 4 -N can be approximated by a simple function of travel time and k, highlighting the importance of the relationship between macrophytes and stream velocity on nutrient processing. This finding has significant management implications, particularly with respect to restoration of riparian shade. Small streams with predominantly marginal emergent plants are likely to have improved retention of NH 4 -N as a result of shading or other means of reducing plant biomass. Streams dominated by submerged macrophytes will have impaired NH 4 -N retention if plant biomass is reduced because of reduced contact times between NH 4 -N molecules and reactive sites. In these conditions water resource managers should utilise riparian shading in concert with unshaded vegetated reaches to achieve a balance between enhanced in-stream habitat and nutrient processing capacity

  14. Functional and Taxonomic Differentiation of Macrophyte Assemblages Across the Yangtze River Floodplain Under Human Impacts.

    Science.gov (United States)

    Zhang, Min; García Molinos, Jorge; Zhang, Xiaolin; Xu, Jun

    2018-01-01

    Human activities and the consequent extirpations of species have been changing the composition of species assemblages worldwide. These anthropogenic impacts alter not only the richness of assemblages but also the biological dissimilarity among them. One of the main gaps in the assessment of biodiversity change in freshwater ecosystems is our limited understanding regarding how taxonomic and functional facets of macrophyte assemblages respond to human impacts on regional scales. Here, we assess the temporal (before 1970s against after 2000s) changes in taxonomic and functional richness and compositional dissimilarities, partitioned into its turnover and nestedness components, of freshwater macrophyte assemblages across the floodplain lakes of the Yangtze River in China. We found that functional and taxonomic assemblage differentiation occurred simultaneously under increasing human impact, concomitant to a general decrease in functional and taxonomic richness. However, this effect weakened when the historical level of taxonomic dissimilarity among assemblages was high. Macrophyte species with large dispersal range and submersed life form were significantly more susceptible to extirpation. The impact of human activities on differentiation was complex but habitat loss and fishery intensity were consistently the main drivers of assemblage change in these lakes, whereas water quality (i.e., light pollution and nutrient enrichment) had weaker effects. Further, macrophyte taxonomic and functional differentiation was mainly driven by the nestedness component of dissimilarity, accounting for changes in assemblage composition related to changes in species richness independent of species replacement. This result, markedly different from previous studies on freshwater fish assemblages conducted in these lakes, represents a novel contribution toward achieving a more holistic understanding of how human impacts contribute to shape community assemblages in natural ecosystems.

  15. Modeling Refuge Effect of Submerged Macrophytes in Lake System.

    Science.gov (United States)

    Lv, Dongyu; Fan, Meng; Kang, Yun; Blanco, Krystal

    2016-04-01

    This paper considers a significant problem in biological control of algae issue in ecological environment. A four-dimensional dynamic model is carefully formulated to characterize the interactions among phytoplankton, submerged macrophyte, zooplankton, and general fish class in a lake ecosystem. The predation relationship is modeled by Beddington-DeAngelis functional responses derived from the classical Holling time budget arguments. Qualitative analyses of the global dynamics show that the system can generate very rich dynamics with potentially 10 different equilibria and several bistable scenarios. We perform analysis on the existence and local stability of equilibria and explore the refuge effect of macrophyte on the zooplankton with numerical simulations on aquatic ecosystems. We also discuss effective methods of biological control used to restrain the increase of phytoplankton. Our study shows the proposed model could have rich and complex dynamics including but not limited to bistable and chaotic phenomenon. Numerical simulation results demonstrate that both the refuge constant and the density of the macrophytes are two key factors where refuge effects take place. In addition, the intraspecific competition between the macrophyte and the phytoplankton can also affect the macrophyte's refuge effect. Our analytical and simulation results suggest that macrophytes provide structure and shelter against predation for zooplankton such that it could restore the zooplankton population, and that planting macrophyte properly might achieve the purpose of controlling algae growth.

  16. Biodiversity in Benthic Ecology

    DEFF Research Database (Denmark)

    Friberg, Nikolai; Carl, J. D.

    Foreword: This proceeding is based on a set of papers presented at the second Nordic Benthological Meeting held in Silkeborg, November 13-14, 1997. The main theme of the meeting was biodiversity in benthic ecology and the majority of contributions touch on this subject. In addition, the proceeding...... contains papers which cover other themes thus continuing with the spirit of the meetings in the Nordic Benthological Society (NORBS) by being an open forum for exchanging knowledge on all aspects of benthic ecology. Overall, we feel the proceeding contains a wide selection of very interesting papers...... representing the state-of-the-art of benthic ecology research within, and to a lesser degree, outside the Nordic countries. We wish to thank all the authors for their inspirational contributions to the proceeding, but we feel that a special thanks is due to the invited speakers for their readiness to produce...

  17. Effects of taxonomy, sediment, and water column on C:N:P stoichiometry of submerged macrophytes in Yangtze floodplain shallow lakes, China.

    Science.gov (United States)

    Su, Haojie; Wu, Yao; Xie, Ping; Chen, Jun; Cao, Te; Xia, Wulai

    2016-11-01

    Carbon (C), nitrogen (N) and phosphorus (P) are the three most important essential elements limiting growth of primary producers. Submerged macrophytes generally absorb nutrients from sediments by root uptake. However, the C:N:P stoichiometric signatures of plant tissue are affected by many additional factors such as taxonomy, nutrient availability, and light availability. We first revealed the relative importance of taxonomy, sediment, and water column on plant C:N:P stoichiometry using variance partitioning based on partial redundancy analyses. Results showed that taxonomy was the most important factor in determining C:N:P stoichiometry, then the water column and finally the sediment. In this study, a significant positive relationship was found between community C concentration and macrophyte community biomass, indicating that the local low C availability in macrophytes probably was the main reason why submerged macrophytes declined in Yangtze floodplain shallow lakes. Based on our study, it is suggested that submerged macrophytes in Yangtze floodplain shallow lakes are primarily limited by low light levels rather than nutrient availability.

  18. Aquatic arsenic: phytoremediation using floating macrophytes.

    Science.gov (United States)

    Rahman, M Azizur; Hasegawa, H

    2011-04-01

    Phytoremediation, a plant based green technology, has received increasing attention after the discovery of hyperaccumulating plants which are able to accumulate, translocate, and concentrate high amount of certain toxic elements in their above-ground/harvestable parts. Phytoremediation includes several processes namely, phytoextraction, phytodegradation, rhizofiltration, phytostabilization and phytovolatilization. Both terrestrial and aquatic plants have been tested to remediate contaminated soils and waters, respectively. A number of aquatic plant species have been investigated for the remediation of toxic contaminants such as As, Zn, Cd, Cu, Pb, Cr, Hg, etc. Arsenic, one of the deadly toxic elements, is widely distributed in the aquatic systems as a result of mineral dissolution from volcanic or sedimentary rocks as well as from the dilution of geothermal waters. In addition, the agricultural and industrial effluent discharges are also considered for arsenic contamination in natural waters. Some aquatic plants have been reported to accumulate high level of arsenic from contaminated water. Water hyacinth (Eichhornia crassipes), duckweeds (Lemna gibba, Lemna minor, Spirodela polyrhiza), water spinach (Ipomoea aquatica), water ferns (Azolla caroliniana, Azolla filiculoides, and Azolla pinnata), water cabbage (Pistia stratiotes), hydrilla (Hydrilla verticillata) and watercress (Lepidium sativum) have been studied to investigate their arsenic uptake ability and mechanisms, and to evaluate their potential in phytoremediation technology. It has been suggested that the aquatic macrophytes would be potential for arsenic phytoremediation, and this paper reviews up to date knowledge on arsenic phytoremediation by common aquatic macrophytes. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Biological control of trace metal and organometal benthic fluxes in a eutrophic lagoon (Thau Lagoon, Mediterranean Sea, France)

    Science.gov (United States)

    Point, D.; Monperrus, M.; Tessier, E.; Amouroux, D.; Chauvaud, L.; Thouzeau, G.; Jean, F.; Amice, E.; Grall, J.; Leynaert, A.; Clavier, J.; Donard, O. F. X.

    2007-04-01

    In situ benthic chamber experiments were conducted in the Thau Lagoon that allowed the simultaneous determination of the benthic exchanges of trace metals (Cd, Co, Cu, Mn, Pb and U) and mercury species (iHg and MMHg). Fluxes of organotin compounds (MBT, DBT and TBT) were also investigated for the first time. The benthic incubations were performed during two campaigns at four stations that presented different macrobenthic and macrophytic species distribution and abundance (see [Thouzeau, G., Grall, J., Clavier, J., Chauvaud, L., Jean, F., Leynaert, A., Longpuirt, S., Amice, E., Amouroux, D., 2007. Spatial and temporal variability of benthic biogeochemical fluxes associated with macrophytic and macrofaunal distributions in the Thau lagoon (France). Estuarine, Coastal and Shelf Science 72 (3), 432 446.]). The results indicate that most of the flux intensity as well as the temporal and spatial variability can be explained by the combined influence of microscale and macroscale processes. Microscale changes were identified using Mn flux as a good indicator of the redox conditions at the sediment water interface, and by extension, as an accurate proxy of benthic fluxes for most trace metals and mercury species. We also observed that the redox gradient at the interface is promoted by both microbial and macrobenthic species activity that governs O2 budgets. Macroscale processes have been investigated considering macrobenthic organisms activity (macrofauna and macroalgal cover). The density of such macroorganisms is able to explain most of the spatial and temporal variability of the benthic metal fluxes within a specific site. A tentative estimation of the flux of metals and organometals associated with deposit feeder and suspension feeder activity was found to be in the range of the flux determined within the chambers for most considered elements. Furthermore, a light/dark incubation investigating a dense macroalgal cover present at the sediment surface illustrates the role

  20. Benthic ecological status of Algerian harbours.

    Science.gov (United States)

    Dauvin, J C; Bakalem, A; Baffreau, A; Grimes, S

    2017-12-15

    This work is an overview of all available benthic data collected in the Algerian harbours between 1983 and 2001. So, total of 571 stations were reported in the 10 major Algerian harbours along the Algerian coast (1200km). Two main categories of harbours were distinguished according to their hydrodynamic regime and volume of water exchange between inner harbour basins and the entrance of the harbours. Univariate, multivariate, benthic indices and Biological Traits of Life approaches were applied on stations sampled in the late 1990s and long-term observations in six out of these ten harbours. These approaches assessed the main characteristics and ecological statuses from these south Mediterranean harbours. One of the main characteristics of the Algerian harbours was the very high species diversity (847 species). Although all the fauna was dominated by pollution-tolerant species; some harbours such as Bethioua and Djendjen hosted normal benthic communities as found in the open sea, but also included some pollution indicator species typical of a slight polluted system. On the contrary, the newly constructed port of Skikda showed perturbed benthic communities in relation to hydrocarbon pollution. Biological Traits of Life analysis reinforced the separation of benthic species along a gradient reflecting their sensitivity or tolerance to pollution. This response was related to an increase in organic matter content, probably associated with a general organic and metal contamination, from the entrance of the harbour to the innermost basins in areas with weak circulation, high sedimentation rate and concentrations of pollutants. Except for Oran harbour, where the poor to moderate ecological status remained unchanged with time, the other harbours showed an improvement or a slight degradation. A strategy of long-term monitoring should be promoted, based on a restricted and selected number of stations characteristic of the different basins and water masses occupying the

  1. Effect of paclobutrazol on three different aquatic macrophytes under ...

    African Journals Online (AJOL)

    Effect of paclobutrazol on three different aquatic macrophytes under in vitro monoculture or polyculture conditions. Kitti Bodhipadma, Sompoch Noichinda, Thanaphol Maneeruang, Koravisd Nathalang, Luepol Punnakanta, David WM Leung ...

  2. SUBMERGED MACROPHYTE EFFECTS ON NUTRIENT EXCHANGES IN RIVERINE SEDIMENTS

    Science.gov (United States)

    Submersed macrophytes are important in nutrient cycling in marine and lacustrine systems, although their role in nutrient exchange in tidally-influenced riverine systems is not well studied. In the laboratory, plants significantly lowered porewater nutrient pools of riverine sedi...

  3. Near-Field Receiving Water Monitoring of Trace Metals and a Benthic Community Near the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay, California: 2008

    Science.gov (United States)

    Cain, Daniel J.; Thompson, Janet K.; Dyke, Jessica; Parcheso, Francis; Luoma, Samuel N.; Hornberger, Michelle I.

    2009-01-01

    Results reported herein include trace element concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica (Cohen and Carlton, 1995)), clam reproductive activity, and benthic macroinvertebrate community structure for a mudflat one kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in South San Francisco Bay. This report includes data collected for the period January 2008 to December 2008 and extends a critical long-term biogeochemical record dating back to 1974. These data serve as the basis for the City of Palo Alto's Near-Field Receiving Water Monitoring Program, initiated in 1994. In 2008, metal concentrations in both sediments and clam tissue were among the lowest concentrations on record and consistent with results observed since 1991. Following significant reductions in the late 1980's, silver (Ag) and copper (Cu) concentrations appeared to have stabilized. Annual mean concentrations have fluctuated modestly (2-4 fold) in a nondirectional manner. Data for other metals, including chromium, mercury, nickel, selenium, vanadium, and zinc, have been collected since 1994. Over this period, concentrations of these elements, which more likely reflect regional inputs and systemwide processes, have remained relatively constant, aside from typical seasonal variation that is common to all elements. Within years, concentrations generally reach maximum in winter months (January-March) and decline to annual minima in spring through fall. Mercury (Hg) in sediments spiked to the highest observed level in January 2008. However, sedimentary concentrations for the rest of the year and concentrations of Hg in M. petalum for the entire year were consistent with data from previous years. Average selenium (Se) concentrations in sediment were the highest on record, but there is no evidence, yet, to suggest a temporal trend of increasing sedimentary Se. Selenium in M. petalum was not elevated relative to

  4. First data on benthic and fish communities from the Mid-Atlantic Ridge, 16°40‧- 17°14‧N

    Science.gov (United States)

    Molodtsova, Tina N.; Galkin, Sergey V.; Kobyliansky, Stanislav G.; Simakova, Ulyana V.; Vedenin, Andrey A.; Dobretsova, Irina G.; Gebruk, Andrey V.

    2017-03-01

    The first ecological survey in the tropical part of the northern Mid-Atlantic Ridge (MAR) was conducted between 17°14‧N and 16°40‧N in February-March 2015 during the 37th cruise of the RV Professor Logachev. Significant effort of the survey was aimed at studies of benthic non-vent soft sediment fauna at depths from 2270 m to 3900 m. Samples of this fauna at seven stations revealed 780 specimens and at least 136 species. The most common species was the hermit crab Parapagurus cf. nudus. Also common were the ophiuroids Ophiotypa simplex and Ophiomusium cf. lymani. Most benthic organisms were the depth range from 0 to 3850 m included 1128 specimens represented by 48 species from 16 families. The highest number of species was in the families Myctophidae (18), Gonostomatidae (9) and Sternoptychidae (5). In the course of the cruise, two new fields of massive sulphide deposits were discovered on the south-western slope of the seamount on the eastern flank of the rift valley, one at 17°08.7‧N and second at 17°07.45‧N. During video profiling in this area indications of modern hydrothermal activity were recorded. Extensive fields of shells of Bathymodiolus puteoserpentis and Thyasira sp. were discovered and samples of bivalves were taken using the TV-grab and geological square corer. Surprisingly high concentration of drowned pelagic algae Sargassum sp. (Phaeophyceae, Fucales) in different state of degradation was observed at TV transects at the seafloor both on soft and hard substrates. Thalli of Sargassum fluitans appeared in trawl catches. Massive aggregations of Sargassum also were abundant at the sea surface in the area from December 2014 to April 2015.

  5. Arsenic accumulation by edible aquatic macrophytes.

    Science.gov (United States)

    Falinski, K A; Yost, R S; Sampaga, E; Peard, J

    2014-01-01

    Edible aquatic macrophytes grown in arsenic (As)-contaminated soil and sediment were investigated to determine the extent of As accumulation and potential risk to humans when consumed. Nasturtium officinale (watercress) and Diplazium esculentum (warabi) are two aquatic macrophytes grown and consumed in Hawaii. Neither has been assessed for potential to accumulate As when grown in As-contaminated soil. Some former sugarcane plantation soils in eastern Hawaii have been shown to have concentrations of total As over 500 mg kg(-1). It was hypothesized that both species will accumulate more As in contaminated soils than in non-contaminated soils. N. officinale and D. esculentum were collected in areas with and without As-contaminated soil and sediment. High soil As concentrations averaged 356 mg kg(-1), while low soil As concentrations were 0.75 mg kg(-1). Average N. officinale and D. esculentum total As concentrations were 0.572 mg kg(-1) and 0.075 mg kg(-1), respectively, corresponding to hazard indices of 0.12 and 0.03 for adults. Unlike previous studies where watercress was grown in As-contaminated water, N. officinale did not show properties of a hyperaccumulator, yet plant concentrations in high As areas were more than double those in low As areas. There was a slight correlation between high total As in sediment and soil and total As concentrations in watercress leaves and stems, resulting in a plant uptake factor of 0.010, an order of magnitude higher than previous studies. D. esculentum did not show signs of accumulating As in the edible fiddleheads. Hawaii is unique in having volcanic ash soils with extremely high sorption characteristics of As and P that limit release into groundwater. This study presents a case where soils and sediments were significantly enriched in total As concentration, but the water As concentration was below detection limits. © 2013 Published by Elsevier Inc.

  6. Spatiotemporal dynamics of submerged macrophytes in a Mediterranean coastal lagoon

    Science.gov (United States)

    Obrador, Biel; Pretus, Joan Lluís

    2010-03-01

    The seasonal and interannual dynamics of the biomass and spatial distribution of a macrophyte meadow were explored in a Mediterranean coastal lagoon (Albufera des Grau, Balearic Islands) from 2002 to 2007. The dynamics in the main physicochemical variables were also analysed to assess the factors involved in the spatiotemporal variability of the submerged macrophytes. The meadows were dominated by Ruppia cirrhosa, which showed a marked seasonal cycle with winter quiescence and complete annual regrowth. The annual production of R. cirrhosa had high interannual variability and was amongst the highest described for this species in the literature, ranging 327-919 gDW m -2. The spatial distribution of macrophytes was determined by light availability and wave exposure, with the highest abundances found in shallow and gently sloped areas sheltered from the strong northerly winds. The interannual variations in macrophyte descriptors (area of occurrence, average depth of the meadows, and maximum biomass) were mainly related to water turbidity and salinity, but the effect of these variables was constrained to the spring and summer months, respectively. A significant negative correlation between the extent of coverage of R. cirrhosa and the water level at the end of the previous annual cycle was observed, suggesting a positive effect of desiccation on the extent of coverage of the macrophytes. After six years of apparent stability, the macrophytes abruptly disappeared from the lagoon. Although the mechanisms are not clear, this shift was likely attributable to a combination of several factors.

  7. Effects of Exposed Artificial Substrate on the Competition between Phytoplankton and Benthic Algae: Implications for Shallow Lake Restoration

    Directory of Open Access Journals (Sweden)

    Hu He

    2017-01-01

    Full Text Available Phytoplankton and benthic algae coexist in shallow lakes and the outcome of the competition between these two photoautotrophs can markedly influence water clarity. It is well established that exposed artificial substrate in eutrophic waters can remove nutrients and fine particles from the water column via the attached periphyton canopy. However, the effects of the introduction of artificial substrate on the competition between planktonic and benthic primary producers remain to be elucidated. We conducted a short-term outdoor mesocosm experiment to test the hypothesis that the nutrient and light changes induced by exposed artificial substrate (polythene nets would benefit the benthic algae. Artificial substrate significantly reduced total nitrogen and phosphorus concentrations and water clarity improved, the latter due to the substrate-induced reduction of both organic and inorganic suspended solids. Consequently, as judged from changes in chlorophyll a (Chl-a concentrations in water and sediment, respectively, exposed artificial substrate significantly reduced the phytoplankton biomass, while benthic algae biomass increased. Our results thus indicate that exposed artificial substrate may be used as a tool to re-establish benthic primary production in eutrophic shallow lakes after an external nutrient loading reduction, paving the way for a benthic- or a macrophyte-dominated system. Longer term and larger scale experiments are, however, needed before any firm conclusions can be drawn on this.

  8. Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California: 2011

    Science.gov (United States)

    Dyke, Jessica; Thompson, Janet K.; Cain, Daniel J.; Kleckner, Amy E.; Parcheso, Francis; Luoma, Samuel N.; Hornberger, Michelle I.

    2012-01-01

    Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in South San Francisco Bay, Calif. This report includes the data collected by U.S. Geological Survey (USGS) scientists for the period January 2011 to December 2011. These data serve as the basis for the City of Palo Alto's Near-Field Receiving Water Monitoring Program, initiated in 1994. Following significant reductions in the late 1980s, silver (Ag) and copper (Cu) concentrations in sediment and M. petalum appear to have stabilized. Data for other metals, including chromium, mercury, nickel, selenium, and zinc, have been collected since 1994. Over this period, concentrations of these elements have remained relatively constant, aside from seasonal variation that is common to all elements. In 2011, concentrations of Ag and Cu in M. petalum varied seasonally in response to a combination of site-specific metal exposures and annual growth and reproduction, as reported previously. Seasonal patterns for other elements, including Cr, Hg, Ni, Se, and Zn, were generally similar in timing and magnitude as those for Ag and Cu. In 2011, metal concentrations in both sediments and clam tissue were among the lowest concentrations on record. This record suggests that regional-scale factors now largely control sedimentary and bioavailable concentrations of Ag and Cu, as well as other elements of regulatory interest, at the Palo Alto site. Analyses of the benthic community structure of a mudflat in South San Francisco Bay over a 38-year period show that changes in the community have occurred concurrent with reduced concentrations of metals in the sediment and in the tissues of the biosentinel clam, M. petalum, from the same area. Analysis of the M. petalum community

  9. The Future of Freshwater Macrophytes in a Changing World: Dissolved Organic Carbon Quantity and Quality and Its Interactions With Macrophytes

    Directory of Open Access Journals (Sweden)

    Rosanne E. Reitsema

    2018-05-01

    Full Text Available Freshwater ecosystems are confronted with the effects of climate change. One of the major changes is an increased concentration of aquatic carbon. Macrophytes are important in the aquatic carbon cycle and play as primary producers a crucial role in carbon storage in aquatic systems. However, macrophytes are affected by increasing carbon concentrations. The focus of this review lies on dissolved organic carbon (DOC, one of the most abundant forms of carbon in aquatic ecosystems which has many effects on macrophytes. DOC concentrations are rising; the exact cause of this increase is not known, although it is hypothesized that climate change is one of the drivers. The quality of DOC is also changing; for example, in urban areas DOC composition is different from the composition in natural watersheds, resulting in DOC that is more resistant to photo-degradation. Plants can benefit from DOC as it attenuates UV-B radiation, it binds potentially harmful heavy metals and provides CO2 as it breaks down. Yet plant growth can also be impaired under high DOC concentrations, especially by humic substances (HS. HS turn the water brown and attenuate light, which limits macrophyte photosynthesis at greater depths. This leads to lower macrophyte abundance and lower species diversity. HS form a wide class of chemicals with many different functional groups and they therefore have the ability to interfere with many biochemical processes that occur in freshwater organisms. Few studies have looked into the direct effects of HS on macrophytes, but there is evidence that HS can interfere with photosynthesis by entering macrophyte cells and causing damage. DOC can also affect reactivity of heavy metals, water and sediment chemistry. This indirectly affects macrophytes too, so they are exposed to multiple stressors that may have contradictive effects. Finally, macrophytes can affect DOC quality and quantity as they produce DOC themselves and provide a substrate to

  10. Hydrodynamic effects of macrophyte microtopography: spatial consequences of interspecific benthic transitions

    NARCIS (Netherlands)

    Lara, M.; Bouma, T.J.; Peralta, G.; van Soelen, J.; Pérez-Llorens, J.L.

    2016-01-01

    Rhizophytic green algae of the genus Caulerpa are potential competitors with seagrass-dominated habitats. At Cadiz Bay Natural Park, Caulerpa prolifera and the seagrass Cymodocea nodosa co-occur in overlapping patches, which may be considered as transition zones. In these zones, changes in

  11. Interactions between crayfish, benthic invertebrates, macrophyte roots and sediment in a littoral zone

    Czech Academy of Sciences Publication Activity Database

    Ságová-Marečková, Markéta

    2002-01-01

    Roč. 155, č. 4 (2002), s. 645-665 ISSN 0003-9136 Grant - others:GA the Center for Limnology of the UW-Madison(XX) BSR8514330 Institutional research plan: CEZ:AV0Z5020903 Keywords : predation * food * crayfish Subject RIV: EE - Microbiology, Virology Impact factor: 1.195, year: 2002

  12. Macrophyte loss drives decadal change in benthic invertebrates in peatland drainage ditches

    NARCIS (Netherlands)

    Whatley, M.H.; van Loon, E.; van Dam, H.; Vonk, J.A.; van der Geest, H.G.; Admiraal, W.

    2014-01-01

    1. Agricultural peatlands and their associated drainage systems are often highly managed and exposed to anthropogenic pressures, such as eutrophication and stable water tables, maintained via drainage during periods of high rainfall and inlet of, alkaline-rich, waters during dry periods. These

  13. Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay, California: 2013

    Science.gov (United States)

    Dyke, Jessica; Cain, Daniel J.; Thompson, Janet K.; Kleckner, Amy E.; Parcheso, Francis; Hornberger, Michelle I.; Luoma, Samuel N.

    2014-01-01

    Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in South San Francisco Bay, Calif. This report includes the data collected by U.S. Geological Survey (USGS) scientists for the period January 2013 to December 2013. These data serve as the basis for the City of Palo Alto’s Near-Field Receiving Water Monitoring Program, initiated in 1994. Following significant reductions in the late 1980s, silver (Ag) and copper (Cu) concentrations in sediment and M. petalum appear to have stabilized. Data for other metals, including chromium (Cr), mercury (Hg), nickel (Ni), selenium (Se), and zinc (Zn), have been collected since 1994. Over this period, concentrations of these elements have remained relatively constant, aside from seasonal variation that is common to all elements. In 2013, concentrations of Ag and Cu in M. petalum varied seasonally in response to a combination of site-specific metal exposures and annual growth and reproduction, as reported previously. Seasonal patterns for other elements, including Cr, Ni, Zn, Hg, and Se, were generally similar in timing and magnitude as those for Ag and Cu. In M. petalum, all observed elements showed annual maxima in January–February and minima in April, except for Zn, which was lowest in December. In sediments, annual maxima also occurred in January–February, and minima were measured in June and September. In 2013, metal concentrations in both sediments and clam tissue were among the lowest concentrations on record. This record suggests that regional-scale factors now largely control sedimentary and bioavailable concentrations of Ag and Cu, as well as other elements of regulatory interest, at the Palo Alto site. Analyses of the benthic community structure of a

  14. Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California, 2012

    Science.gov (United States)

    Dyke, Jessica; Thompson, Janet K.; Cain, Daniel J.; Kleckner, Amy E.; Parcheso, Francis; Luoma, Samuel N.; Hornberger, Michelle I.

    2013-01-01

    Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in South San Francisco Bay, Calif. This report includes the data collected by U.S. Geological Survey (USGS) scientists for the period January to December 2012. These data serve as the basis for the City of Palo Alto’s Near-Field Receiving Water Monitoring Program, initiated in 1994. Following significant reductions in the late 1980s, silver (Ag) and copper (Cu) concentrations in sediment and in M. petalum appear to have stabilized. Data for other metals, including chromium (Cr), mercury (Hg), nickel (Ni), selenium (Se), and zinc (Zn), have been collected since 1994. Over this period, concentrations of these elements have remained relatively constant, aside from seasonal variation that is common to all elements. In 2012, concentrations of Ag and Cu in M. petalum varied seasonally in response to a combination of site-specific metal exposures and annual growth and reproduction, as reported for previous time periods. Seasonal patterns for other elements, including Cr, Ni, Zn, Hg, and Se were generally similar in timing and magnitude as those for Ag and Cu. In 2012, metal concentrations in both sediments and clam tissue were among the lowest concentrations on record. This record suggests that regional-scale factors now largely control sedimentary and bioavailable concentrations of Ag and Cu, as well as other elements of regulatory interest, at the Palo Alto site. Analyses of the benthic community structure of a mudflat in South San Francisco Bay over a 39-year period show that changes in the community have occurred concurrent with reduced concentrations of metals in the sediment and in the tissues of the biosentinel clam, M. petalum, from the same area

  15. Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California; 2016

    Science.gov (United States)

    Cain, Daniel J.; Thompson, Janet K.; Parchaso, Francis; Pearson, Sarah; Stewart, Robin; Turner, Mathew; Barasch, David; Luoma, Samuel N.

    2017-10-30

    Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in south San Francisco Bay, Calif. This report includes the data collected by U.S. Geological Survey (USGS) scientists for the period January 2014 to December 2016. These append to long-term datasets extending back to 1974. A major focus of the report is an integrated description of the 2016 data within the context of the longer, multi-decadal dataset. This dataset supports the City of Palo Alto’s Near-Field Receiving Water Monitoring Program, initiated in 1994.Significant reductions in silver and copper concentrations in sediment and M. petalum occurred at the site in the 1980s following the implementation by PARWQCP of advanced wastewater treatment and source control measures. Since the 1990s, concentrations of these elements appear to have stabilized at concentrations somewhat above (silver) or near (copper) regional background concentrations Data for other metals, including chromium (Cr), mercury (Hg), nickel (Ni), selenium (Se), and zinc (Zn), have been collected since 1994. Over this period, concentrations of these elements have remained relatively constant, aside from seasonal variation that is common to all elements. In 2016, concentrations of silver and copper in M. petalum varied seasonally in response to a combination of site-specific metal exposures and annual growth and reproduction, as reported previously. Seasonal patterns for other elements, including Cr, Ni, Zn, Hg, and Se, were generally similar in timing and magnitude as those for Ag and Cu. This record suggests that legacy contamination and regional-scale factors now largely control sedimentary and bioavailable concentrations of silver and copper, as well as other elements of

  16. Response of aquatic macrophytes to human land use perturbations in the watersheds of Wisconsin lakes, U.S.A.

    Science.gov (United States)

    Sass, Laura L.; Bozek, Michael A.; Hauxwell, Jennifer A.; Wagner, Kelly; Knight, Susan

    2010-01-01

    Aquatic macrophyte communities were assessed in 53 lakes in Wisconsin, U.S.A. along environmental and land use development gradients to determine effects human land use perturbations have on aquatic macrophytes at the watershed and riparian development scales. Species richness and relative frequency were surveyed in lakes from two ecoregions: the Northern Lakes and Forests Ecoregion and the Southeastern Wisconsin Till Plain Ecoregion. Lakes were selected along a gradient of watershed development ranging from undeveloped (i.e., forested), to agricultural to urban development. Land uses occurring in the watershed and in perimeters of different width (0–100, 0–200, 0–500, and 0–1000 m from shore, in the watershed) were used to assess effects on macrophyte communities. Snorkel and SCUBA were used to survey aquatic macrophyte species in 18 quadrats of 0.25 m2 along 14 transects placed perpendicular to shore in each lake. Effects of watershed development (e.g., agriculture and/or urban) were tested at whole-lake (entire littoral zone) and near-shore (within 7 m of shore) scales using canonical correspondence analysis (CCA) and linear regression. Overall, species richness was negatively related to watershed development, while frequencies of individual species and groups differed in level of response to different land use perturbations. Effects of land use in the perimeters on macrophytes, with a few exceptions, did not provide higher correlations compared to land use at the watershed scale. In lakes with higher total watershed development levels, introduced species, particularly Myriophyllumspicatum, increased in abundance and native species, especially potamids, isoetids, and floating-leaved plants, declined in abundance. Correlations within the northern and southeastern ecoregions separately were not significant. Multivariate analyses suggested species composition is driven by environmental responses as well as human development pressures. Both water

  17. Coexistence of fish species in a large lowland river: food niche partitioning between small-sized percids, cyprinids and sticklebacks in submersed macrophytes.

    Science.gov (United States)

    Dukowska, Małgorzata; Grzybkowska, Maria

    2014-01-01

    In the spring and summer of each year, large patches of submersed aquatic macrophytes overgrow the bottom of the alluvial Warta River downstream of a large dam reservoir owing to water management practices. Environmental variables, macroinvertebrates (zoobenthos and epiphytic fauna, zooplankton) and fish abundance and biomass were assessed at this biologically productive habitat to learn intraseasonal dynamics of food types, and their occurrence in the gut contents of small-sized roach, dace, perch, ruffe and three-spined stickleback. Gut fullness coefficient, niche breadth and niche overlap indicated how the fishes coexist in the macrophytes. Chironomidae dominated in the diet of the percids. However, ruffe consumed mostly benthic chironomids, while perch epiphytic chironomids and zooplankton. The diet of dace resembled that in fast flowing water although this rheophilic species occurred at unusual density there. The generalist roach displayed the lowest gut fullness coefficient values and widest niche breadth; consequently, intraspecific rather than interspecific competition decided the fate of roach. Three-spined stickleback differed from the other fishes by consuming epiphytic simuliids and fish eggs. The diet overlap between fishes reaching higher gut fullness coefficient values was rather low when the food associated with the submersed aquatic macrophytes was most abundant; this is congruent with the niche overlap hypothesis that maximal tolerable niche overlap can be higher in less intensely competitive conditions.

  18. Macrophyte assemblage composition as a simple tool to assess global change in coastal areas. Freshwater impacts and climatic changes.

    Science.gov (United States)

    Buosi, Alessandro; Sfriso, Adriano

    2017-12-15

    Macrophyte assemblages are one of the most sensitive biological communities to assess anthropogenic impacts and climate changes. Community composition responds very quickly to environmental changes driving towards a predictable composition. The increase or decrease of the trophic status (i.e. nutrient concentrations, suspended particulate matter, Chlorophyll-a) and temperature are the most important factors responsible for the replacement of taxa of high ecological value (sensitive taxa) with opportunistic species. A qualitative and quantitative study of macrophytes in 4 areas along the coasts of the Northern Adriatic Sea, from Venice (Italy) to Savudrija (Croatia) and the analysis of river outflows in this region during one year (May 2012-April 2013) provided information about their spatial variability. The coasts of the Veneto Region and Friuli-Venezia Giulia, which are affected by significant freshwater inputs, showed a strong biodiversity reduction or a dominance of thionitrophilic taxa. No seagrasses colonized these areas. On the other hand, the coasts of Croatia had negligible fresh water inputs and macrophyte communities were dominated by sensitive taxa such as the seagrass Cymodocea nodosa and some species belonging to genus Cystoseira. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Marine benthic faunal successional stages and related sedimentary activity

    Directory of Open Access Journals (Sweden)

    Rutger Rosenberg

    2001-12-01

    Full Text Available This paper is a brief review of successional stages and activity of benthic soft-bottom communities. Benthic communities was first described by Petersen in the 1910s and further developed by Molander, Thorson and Margalef. Successional stages of benthic communities chance in a predictable way in relation to environmental disturbance and food availability. Food supply to the bottom can occur as a vertical flux, but transport through lateral advection is more important in some areas. While at the bottom, the infauna processes the food in many different ways, and the feeding modes can be categorised into more than 20 functional groups, but fewer are present in brackish water. This categorisation is based on animal mobility and where and how they ingest the food. Animal activity in the sediment, bioturbation, has a significant effect on redox conditions and diagenetic processes. Structures in the sediment due to infaunal presence and activity can be observed in situ by sediment profile imaging, and the biogenic structures and redox conditions can be parameterised and have been shown to correlate to benthic community successional stages. The largest threat to benthic faunal biodiversity is the spread of near-bottom oxygen deficiency in many enclosed are stratified coastal areas.

  20. Macrophytes shape trophic niche variation among generalist fishes.

    Directory of Open Access Journals (Sweden)

    Ivana Vejříková

    Full Text Available Generalist species commonly have a fundamental role in ecosystems as they can integrate spatially distinct habitats and food-web compartments, as well as control the composition, abundance and behavior of organisms at different trophic levels. Generalist populations typically consist of specialized individuals, but the potential for and hence degree of individual niche variation can be largely determined by habitat complexity. We compared individual niche variation within three generalist fishes between two comparable lakes in the Czech Republic differing in macrophyte cover, i.e. macrophyte-rich Milada and macrophyte-poor Most. We tested the hypothesis that large individual niche variation among generalist fishes is facilitated by the presence of macrophytes, which provides niches and predation shelter for fish and their prey items. Based on results from stable nitrogen (δ15N and carbon (δ13C isotopic mixing models, perch (Perca fluviatilis L. and rudd (Scardinius erythrophthalmus (L. showed larger individual variation (i.e., variance in trophic position in Milada as compared to Most, whereas no significant between-lake differences were observed for roach (Rutilus rutilus (L.. Contrary to our hypothesis, all the three species showed significantly lower individual variation in the relative reliance on littoral food resources in Milada than in Most. Rudd relied significantly more whereas perch and roach relied less on littoral food resources in Milada than in Most, likely due to prevalent herbivory by rudd and prevalent zooplanktivory by perch and roach in the macrophyte-rich Milada as compared to macrophyte-poor Most. Our study demonstrates how the succession of macrophyte vegetation, via its effects on the physical and biological complexity of the littoral zone and on the availability of small prey fish and zooplankton, can strongly influence individual niche variation among generalist fishes with different ontogenetic trajectories, and hence

  1. Macrophytes shape trophic niche variation among generalist fishes

    Science.gov (United States)

    Vejřík, Lukáš; Šmejkal, Marek; Čech, Martin; Sajdlová, Zuzana; Frouzová, Jaroslava; Kiljunen, Mikko; Peterka, Jiří

    2017-01-01

    Generalist species commonly have a fundamental role in ecosystems as they can integrate spatially distinct habitats and food-web compartments, as well as control the composition, abundance and behavior of organisms at different trophic levels. Generalist populations typically consist of specialized individuals, but the potential for and hence degree of individual niche variation can be largely determined by habitat complexity. We compared individual niche variation within three generalist fishes between two comparable lakes in the Czech Republic differing in macrophyte cover, i.e. macrophyte-rich Milada and macrophyte-poor Most. We tested the hypothesis that large individual niche variation among generalist fishes is facilitated by the presence of macrophytes, which provides niches and predation shelter for fish and their prey items. Based on results from stable nitrogen (δ15N) and carbon (δ13C) isotopic mixing models, perch (Perca fluviatilis L.) and rudd (Scardinius erythrophthalmus (L.)) showed larger individual variation (i.e., variance) in trophic position in Milada as compared to Most, whereas no significant between-lake differences were observed for roach (Rutilus rutilus (L.)). Contrary to our hypothesis, all the three species showed significantly lower individual variation in the relative reliance on littoral food resources in Milada than in Most. Rudd relied significantly more whereas perch and roach relied less on littoral food resources in Milada than in Most, likely due to prevalent herbivory by rudd and prevalent zooplanktivory by perch and roach in the macrophyte-rich Milada as compared to macrophyte-poor Most. Our study demonstrates how the succession of macrophyte vegetation, via its effects on the physical and biological complexity of the littoral zone and on the availability of small prey fish and zooplankton, can strongly influence individual niche variation among generalist fishes with different ontogenetic trajectories, and hence the overall

  2. Sensitivity of submersed freshwater macrophytes and endpoints in laboratory toxicity tests

    International Nuclear Information System (INIS)

    Arts, Gertie H.P.; Belgers, J. Dick M.; Hoekzema, Conny H.; Thissen, Jac T.N.M.

    2008-01-01

    The toxicological sensitivity and variability of a range of macrophyte endpoints were statistically tested with data from chronic, non-axenic, macrophyte toxicity tests. Five submersed freshwater macrophytes, four pesticides/biocides and 13 endpoints were included in the statistical analyses. Root endpoints, reflecting root growth, were most sensitive in the toxicity tests, while endpoints relating to biomass, growth and shoot length were less sensitive. The endpoints with the lowest coefficients of variation were not necessarily the endpoints, which were toxicologically most sensitive. Differences in sensitivity were in the range of 10-1000 for different macrophyte-specific endpoints. No macrophyte species was consistently the most sensitive. Criteria to select endpoints in macrophyte toxicity tests should include toxicological sensitivity, variance and ecological relevance. Hence, macrophyte toxicity tests should comprise an array of endpoints, including very sensitive endpoints like those relating to root growth. - A range of endpoints is more representative of macrophyte fitness than biomass and growth only

  3. Effect of removal of free-floating macrophytes on zooplankton habitat in shallow wetland

    OpenAIRE

    Choi Jong-Yun; Jeong Kwang-Seuk; La Geung-Hwan; Joo Gea-Jae

    2014-01-01

    Submerged macrophytes improve the structural heterogeneity of microhabitats in aquatic ecosystems, often providing an important habitat for zooplankton. However, excessive development of free-floating macrophytes on the water surface can reduce the biomass of submerged macrophytes and result in a relatively simple habitat structure. We hypothesized that controlling the development of free-floating macrophytes would result in a more complex habitat structure by promoting the development of sub...

  4. TOXICITY OF INDUSTRIAL EFFLUENT ON TOTAL CHLOROPHYLL CONTENT OF CERTAIN AQUATIC MACROPHYTES

    OpenAIRE

    Singh Priti; Vishen Ashish; Wadhwani R; Pandey Y.N

    2012-01-01

    To assess the toxicity of industrial effluents on certain macrophytes, the total chlorophyll content of free floating, submerged and emergent macrophytes were estimated in concentrations of industrial effluents at varying exposure duration. The result revealed reduction in total chlorophyll content of exposed macrophytes at higher concentrations of industrial effluents on prolonged duration.

  5. Physiological performance and thermal tolerance of major Red Sea macrophytes

    KAUST Repository

    Weinzierl, Michael S.

    2017-12-01

    As anthropogenically-forced ocean temperatures continue to rise, the physiological response of marine macrophytes becomes exceedingly relevant. The Red Sea is a semi-isolated sea- the warmest in the world (SST up to 34°C) - already exhibiting signs of rapid warming rates exceeding those of other tropical oceans. This will have profound effects on the physiology of marine organisms, specifically marine macrophytes, which have direct influence on the dynamic carbonate system of the Red Sea. The aim of this paper is to define the physiological capability and thermal optima and limits of six ecologically important Red Sea macrophytes- ranging from seagrasses to calcifying and non-calcifying algae- and to describe the effects of increasing thermal stress on the performance and limits of each macrophyte in terms of activation energy. Of the species considered, Halophila stipulacae, Halimeda optunia, Halimeda monile and Padina pavonica thrive in thermal extremes and may be more successful in future Red Sea warming scenarios. Specifically, Halimeda opuntia increased productivity and calcification rates up to 38°C, making it the most thermally resilient macrophyte. Halophila stipulacae is the most productive seagrass, and hence has the greatest positive effect on Omega saturation state and offers chemical buffer capacity to future ocean acidification.

  6. Efeito de metais Cobre (Cu e Zinco (Zn sobre a comunidade de macroinvertebrados bentônicos em riachos do sul do Brasil - DOI: 10.4025/actascibiolsci.v30i3.677 The effect of metals (Cu and Zn on the benthic macroinvertebrate community in streams in southern Brazil - DOI: 10.4025/actascibiolsci.v30i3.677

    Directory of Open Access Journals (Sweden)

    Luiz Ubiratan Hepp

    2008-10-01

    Full Text Available O objetivo deste estudo foi avaliar os efeitos de metais (Cu e Zn sobre a comunidade de macroinverterados bentônicos. Foram amostrados, trimestralmente, entre setembro de 2006 e junho de 2007, organismos e água em oito trechos de riachos de duas bacias hidrográficas influenciadas por urbanização e agricultura. Foram estimados os valores de densidade de organismos, riqueza taxonômica e diversidade de Shannon. Para avaliação dos dados, foram utilizados testes de variância e regressão linear simples. Os resultados demonstraram variabilidade das concentrações dos metais e da macrofauna entre as estações do ano e riachos estudados. O metal Cobre (Cu apresentou influência apenas sobre a densidade Chironomidae e o metal Zinco (Zn apresentou efeito sobre a densidade total da macrofauna bentônica e de Chironomidae. Nenhum dos metais apresentou efeitos sobre a riqueza e diversidade de macroinvertebrados. Os resultados indicam potencial bioindicador da comunidade bentônica na avaliação da qualidade integrada do ambiente.The aim of this study was to evaluate the effect of metals (Cu and Zn on the benthic macroinvertebrate community. The organisms and water were collected quarterly between September 2006 and June 2007, in eight sites in streams of two hydrographic basins, influenced by urbanization and agriculture. The values of organism density, taxonomic richness and the Shannon diversity index were calculated. For data evaluation, tests of variance and simple linear regression were used. The results showed variability in the metal concentration and benthic community among seasons and studied streams. Cu showed influence only on Chironomidae density. Zn demonstrated effect on the benthic community and Chironomidae density. None of the metals presented effect on the macroinvertebrate richness and diversity. The results indicate a bioindicator potential of the benthic community in the evaluation of integral quality of the environment.

  7. Biogeographic characterization of fish and benthic communities, St Croix, US Virgin Islands 2012-05-07 to 2012-05-18 (NODC Accession 0125237)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Reef fish populations are a conspicuous and essential component of USVI coral reef ecosystems. Yet despite their importance, striking population and community level...

  8. Diversity and biomass of native macrophytes are negatively related to dominance of an invasive Poaceae in Brazilian sub-tropical streams

    Directory of Open Access Journals (Sweden)

    Luiz Felipe Gonçalves Fernandes

    2013-06-01

    Full Text Available Besides exacerbated exploitation, pollution, flow alteration and habitats degradation, freshwater biodiversity is also threatened by biological invasions. This paper addresses how native aquatic macrophyte communities are affected by the non-native species Urochloa arrecta, a current successful invader in Brazilian freshwater systems. We compared the native macrophytes colonizing patches dominated and non-dominated by this invader species. We surveyed eight streams in Northwest Paraná State (Brazil. In each stream, we recorded native macrophytes' richness and biomass in sites where U. arrecta was dominant and in sites where it was not dominant or absent. No native species were found in seven, out of the eight investigated sites where U. arrecta was dominant. Thus, we found higher native species richness, Shannon index and native biomass values in sites without dominance of U. arrecta than in sites dominated by this invader. Although difficult to conclude about causes of such differences, we infer that the elevated biomass production by this grass might be the primary reason for alterations in invaded environments and for the consequent impacts on macrophytes' native communities. However, biotic resistance offered by native richer sites could be an alternative explanation for our results. To mitigate potential impacts and to prevent future environmental perturbations, we propose mechanical removal of the invasive species and maintenance or restoration of riparian vegetation, for freshwater ecosystems have vital importance for the maintenance of ecological services and biodiversity and should be preserved.

  9. Performance assessment of aquatic macrophytes for treatment of municipal wastewater.

    Science.gov (United States)

    Shah, Mumtaz; Hashmi, Hashim Nisar; Ali, Arshad; Ghumman, Abdul Razzaq

    2014-01-01

    The objective of the study was to evaluate the performance of three different aquatic macrophytes for treatment of municipal wastewater collected from Taxila (Pakistan). A physical model of treatment plant was constructed and was operated for six experimental runs with each species of macrophyte. Every experimental run consist of thirty days period. Regular monitoring of influent and effluent concentrations were made during each experimental run. For the treatment locally available macrophyte species i.e. water hyacinth, duckweed & water lettuce were selected to use. To evaluate the treatment performance of each macrophyte, BOD5, COD, and Nutrients (Nitrogen and Phosphorus) were monitored in effluent from model at different detention time of every experimental run after ensuring steady state conditions. The average reduction of effluent value of each parameter using water hyacinth were 50.61% for BOD5, 46.38% for COD, 40.34% for Nitrogen and 18.76% for Phosphorus. For duckweed the average removal efficiency for selected parameters were 33.43% for BOD5, 26.37% for COD, 17.59% for Nitrogen and 15.25% for Phosphorus and for Water Lettuce the average removal efficiency were 33.43% for BOD5, 26.37% for COD, 17.59% for Nitrogen and 15.25% for Phosphorus. The mechanisms of pollutant removal in this system include both aerobic and anaerobic microbiological conversions, sorption, sedimentation, volatilization and chemical transformations. The rapid growth of the biomass was measured within first ten days detention time. It was also observed that performance of macrophytes is influenced by variation of pH and Temperature. A pH of 6-9 and Temperature of 15-38°C is most favorable for treatment of wastewater by macrophytes. The option of macrophytes for treatment of Municipal sewage under local environmental conditions can be explored by further verifying the removal efficiency under variation of different environmental conditions. Also this is need of time that macrophyte

  10. Can aquatic macrophytes mobilize technetium by oxidizing their rhizosphere?

    International Nuclear Information System (INIS)

    Sheppard, S.C.; Evenden, W.G.

    1991-01-01

    Technetium (Tc) is very mobile in aerated surface environments, but is essentially immobile and biologically unavailable in anaerobic sediments. Aquatic macrophyte roots penetrate anaerobic sediments, carrying O 2 downward and frequently creating oxidizing conditions in their rhizosphere. The authors hypothesized that this process could mobilize otherwise unavailable Tc, possibly leading to incorporation of Tc into human or animal foods. Through experiments with rice (Oryza sativa L.), and with a novel artificial macrophyte root, they concluded that this pathway is unlikely to be important for annual plants, especially in soils with a high biological oxygen demand. The relatively slow oxidation of Tc limited its mobilization by short-lived root systems

  11. Modelling temporal and spatial dynamics of benthic fauna in North-West-European shelf seas

    Science.gov (United States)

    Lessin, Gennadi; Bruggeman, Jorn; Artioli, Yuri; Butenschön, Momme; Blackford, Jerry

    2017-04-01

    Benthic zones of shallow shelf seas receive high amounts of organic material. Physical processes such as resuspension, as well as complex transformations mediated by diverse faunal and microbial communities, define fate of this material, which can be returned to the water column, reworked within sediments or ultimately buried. In recent years, numerical models of various complexity and serving different goals have been developed and applied in order to better understand and predict dynamics of benthic processes. ERSEM includes explicit parameterisations of several groups of benthic biota, which makes it particularly applicable for studies of benthic biodiversity, biological interactions within sediments and benthic-pelagic coupling. To assess model skill in reproducing temporal (inter-annual and seasonal) dynamics of major benthic macrofaunal groups, 1D model simulation results were compared with data from the Western Channel Observatory (WCO) benthic survey. The benthic model was forced with organic matter deposition rates inferred from observed phytoplankton abundance and model parameters were subsequently recalibrated. Based on model results and WCO data comparison, deposit-feeders exert clear seasonal variability, while for suspension-feeders inter-annual variability is more pronounced. Spatial distribution of benthic fauna was investigated using results of a full-scale NEMO-ERSEM hindcast simulation of the North-West European Shelf Seas area, covering the period of 1981-2014. Results suggest close relationship between spatial distribution of biomass of benthic faunal functional groups in relation to bathymetry, hydrodynamic conditions and organic matter supply. Our work highlights that it is feasible to construct, implement and validate models that explicitly include functional groups of benthic macrofauna. Moreover, the modelling approach delivers detailed information on benthic biogeochemistry and food-web at spatial and temporal scales that are unavailable

  12. Survival under stress : benthic foraminiferal patterns and Cenozoic biotic crises

    NARCIS (Netherlands)

    Kouwenhoven, T.J.

    2000-01-01

    A principal conclusion of this thesis is, that benthic foraminifera are excellent recorders of paleoenvironments and paleoenvironmental change. Insight in their community structure, and changes in this through time, is still increasing and will add to their usefulness in the reconstruction of past

  13. Survival under stress : benthic foraminiferal patterns and Cenozoic biotic crises

    NARCIS (Netherlands)

    Kouwenhoven, T.J.

    2000-01-01

    A principal conclusion of this thesis is, that benthic foraminifera are excellent recorders of paleoenvironments and paleoenvironmental change. Insight in their community structure, and changes in this through time, is still increasing and will add to their usefulness in the reconstruction of

  14. Does the Lagoa do Peixe sandbar opening influence the macrophyte richness and composition in Southern Brazil wetlands?

    Directory of Open Access Journals (Sweden)

    Ana Silvia Rolon

    2013-03-01

    Full Text Available The Lagoa do Peixe has its connection with the sea artificially opened every year at the end of winter. However, this management has been carried out without the evaluation of the impact of this opening in the aquatic biodiversity. This information is crucial for the management of the natural resources of the Lagoa do Peixe National Park, the unique Ramsar site in Southern Brazil. The following questions were analyzed: (1 Do richness and composition of aquatic macrophytes from Lagoa do Peixe floodplain varies temporarily according to the sandbar opening and closing? (2 Does the variation pattern of the macrophyte community changed according to the sandbar opening and closing? A set of eight sampling sites of 1ha were selected over the Lagoa do Peixe floodplain: four sites not influenced by the artificial sandbar opening and four sites influenced by this event, being two sites closer to the sandbar opening and the two sites distant to the sandbar opening. The samplings were carried out between November 2007 and October 2009. The results show that although the artificial sandbar breaching does not affect the aquatic macrophyte richness at the floodplain, it affects the dynamics of species composition. The hydrological variation related to this management can be the main factor of the continuous change in the species composition in the floodplain, especially in the Southern portion. In order to avoid impacts in the macrophyte conservation, the artificial sandbar opening should be considered carefully, since the area of study is one of the most important conservation units to wetland systems in Southern Brazil.

  15. Does the Lagoa do peixe sandbar opening influence the macrophyte richness and composition in Southern Brazil wetlands?

    Science.gov (United States)

    Rolon, Ana Silvia; Rocha, Odete; Maltchik, Leonardo

    2013-03-01

    The Lagoa do Peixe has its connection with the sea artificially opened every year at the end of winter. However, this management has been carried out without the evaluation of the impact of this opening in the aquatic biodiversity. This information is crucial for the management of the natural resources of the Lagoa do Peixe National Park, the unique Ramsar site in Southern Brazil. The following questions were analyzed: (1) Do richness and composition of aquatic macrophytes from Lagoa do Peixe floodplain varies temporarily according to the sandbar opening and closing? (2) Does the variation pattern of the macrophyte community changed according to the sandbar opening and closing? A set of eight sampling sites of 1ha were selected over the Lagoa do Peixe floodplain: four sites not influenced by the artificial sandbar opening and four sites influenced by this event, being two sites closer to the sandbar opening and the two sites distant to the sandbar opening. The samplings were carried out between November 2007 and October 2009. The results show that although the artificial sandbar breaching does not affect the aquatic macrophyte richness at the floodplain, it affects the dynamics of species composition. The hydrological variation related to this management can be the main factor of the continuous change in the species composition in the floodplain, especially in the Southern portion. In order to avoid impacts in the macrophyte conservation, the artificial sandbar opening should be considered carefully, since the area of study is one of the most important conservation units to wetland systems in Southern Brazil.

  16. Six decades of change in pollution and benthic invertebrate biodiversity in a southern New England estuary

    Science.gov (United States)

    Pollution has led to a decline of benthic invertebrate biodiversity of Narragansett Bay, raising questions about effects on ecosystem functions and services including shellfish production, energy flow to fishes, and biogeochemical cycles. Changes in community composition and taxo...

  17. Relationship between benthic foraminifera and sediment in the estuarine complex of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Dalal, S.G.

    Two indices of community association were used to elucidate the relationship between changes in species composition of benthic foraminifera and changes in the grain size composition of the sediment in estuarine complex of Goa. The degree...

  18. Ecotoxicological effect of grounded MV River Princess on the intertidal benthic organisms off Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Sivadas, S.; Goltekar, R.; Clemente, S.; Nanajkar, M.; Sawant, R.; DeSilva, C.; Sarkar, A.; Ansari, Z.A.

    –biomass curves showed significant negative impact of TPH on macrofauna. The benthic community structure also showed measurable changes, as there was significant decrease (60%) in the number of species. Given that the microalgal counts were low in sediment...

  19. From Greenland to green lakes: Cultural eutrophication and the loss of benthic pathways in lakes

    DEFF Research Database (Denmark)

    Vadeboncoeur, Y.; Jeppesen, E.; Zanden, M. J. V.

    2003-01-01

    Benthic community responses to lake eutrophication are poorly understood relative to pelagic responses. We compared phytoplankton and periphyton productivity along a eutrophication gradient in Greenland, U.S., and Danish lakes. Phytoplankton productivity increased along the phosphorus gradient (t...

  20. Geographic Information System (GIS) characterizations of benthic habitats near South Florida coast (NODC Accession 0000600)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data collection uses a Geographic Information System (GIS) to organize and characterize information about benthic communities and substrates, which are...

  1. A preliminary study of an eastern Mediterranean coastal ecosystem: Summer Resorts and Benthic ecosystems

    Directory of Open Access Journals (Sweden)

    S. REIZOPOULOU

    2006-06-01

    Full Text Available The present study investigates whether coastal benthic communities are affected by tourist activities along the coast, which persist for a limited time period. The analysis of benthic macrofauna is based on the ecological parameters (quantitative analyses as well as on the ecological identity of the species (qualitative analyses. Microbial contamination and some population statistics are correlated with ecological parameters. The disturbance of benthic communities in the vicinity of summer resorts is summarized by a reduction in species number and dominance of opportunistic species characteristic of disturbed and polluted environments. It is found that community diversity and evenness of distribution decrease with the deterioration of water quality, expressed as grade of microbial contamination, which implies that benthic community is also a significant element in assessing the quality of coastal waters. The above parameters were statistically negatively correlated with the number of tourists.

  2. Assessing the effectiveness of pollutant removal by macrophytes in a floating wetland for wastewater treatment

    Science.gov (United States)

    Prajapati, Meera; van Bruggen, Johan J. A.; Dalu, Tatenda; Malla, Rabin

    2017-12-01

    The study aimed to evaluate the removal of pollutants by floating treatment wetlands (FTWs) using an edible floating plant, and emergent macrophytes. All experiments were performed under ambient conditions. Physico-chemical parameters were measured, along with microbiological analysis of biofilm within the roots, water column, and sludge and gravel zone. Nitrification and denitrification rates were high in the water zone of Azolla filiculoides, Lemna minor, Lactuca sativa, P. stratiotes, and Phragmites australis. Phosphate removal efficiencies were 23, 10, and 15% for the free-floating hydrophytes, emergent macrophytes, and control and edible plants, respectively. The microbial community was relatively more active in the root zone compared to other zones. Pistia stratiotes was found to be the efficient in ammonium (70%) and total nitrogen (59%) removal. Pistia stratiotes also showed the highest microbial activity of 1306 mg day-1, which was 62% of the total volume. Microbial activity was found in the water zone of all FTWs expect for P. australis. The use of P. stratiotes and the edible plant L. sativa could be a potential option to treat domestic wastewater due to relatively high nutrient and organic matter removal efficiency.

  3. Louisiana waterthrush and benthic macroinvertebrate response to shale gas development

    Science.gov (United States)

    Wood, Petra; Frantz, Mack W.; Becker, Douglas A.

    2016-01-01

    Because shale gas development is occurring over large landscapes and consequently is affecting many headwater streams, an understanding of its effects on headwater-stream faunal communities is needed. We examined effects of shale gas development (well pads and associated infrastructure) on Louisiana waterthrush Parkesia motacilla and benthic macroinvertebrate communities in 12 West Virginia headwater streams in 2011. Streams were classed as impacted (n = 6) or unimpacted (n = 6) by shale gas development. We quantified waterthrush demography (nest success, clutch size, number of fledglings, territory density), a waterthrush Habitat Suitability Index, a Rapid Bioassessment Protocol habitat index, and benthic macroinvertebrate metrics including a genus-level stream-quality index for each stream. We compared each benthic metric between impacted and unimpacted streams with a Student's t-test that incorporated adjustments for normalizing data. Impacted streams had lower genus-level stream-quality index scores; lower overall and Ephemeroptera, Plecoptera, and Trichoptera richness; fewer intolerant taxa, more tolerant taxa, and greater density of 0–3-mm individuals (P ≤ 0.10). We then used Pearson correlation to relate waterthrush metrics to benthic metrics across the 12 streams. Territory density (no. of territories/km of stream) was greater on streams with higher genus-level stream-quality index scores; greater density of all taxa and Ephemeroptera, Plecoptera, and Trichoptera taxa; and greater biomass. Clutch size was greater on streams with higher genus-level stream-quality index scores. Nest survival analyses (n = 43 nests) completed with Program MARK suggested minimal influence of benthic metrics compared with nest stage and Habitat Suitability Index score. Although our study spanned only one season, our results suggest that shale gas development affected waterthrush and benthic communities in the headwater streams we studied. Thus, these ecological effects of

  4. Fish stomach contents in benthic macroinvertebrate assemblage assessments

    Directory of Open Access Journals (Sweden)

    TH. Tupinambás

    Full Text Available The choice of sampling gears to assess benthic macroinvertebrate communities depends on environmental characteristics, study objectives, and cost effectiveness. Because of the high foraging capacity and diverse habitats and behaviors of benthophagous fishes, their stomach contents may offer a useful sampling tool in studies of benthic macroinvertebrates, especially in large, deep, fast rivers that are difficult to sample with traditional sediment sampling gear. Our objective was to compare the benthic macroinvertebrate communities sampled from sediments with those sampled from fish stomachs. We collected benthic macroinvertebrates and fish from three different habitat types (backwater, beach, riffle in the wet season, drying season, and dry season along a single reach of the Grande River (Paraná River Basin, southeast Brazil. We sampled sediments through use of a Petersen dredge (total of 216 grabs and used gill nets to sample fish (total of 36 samples. We analyzed the stomach contents of three commonly occurring benthophagous fish species (Eigenmannia virescens, Iheringichthys labrosus, Leporinus amblyrhynchus. Chironomids dominated in both sampling methods. Macroinvertebrate taxonomic composition and abundances from fish stomachs differed from those from sediment samples, but less so from riffles than from backwater and beach habitats. Macroinvertebrate taxa from E. virescens stomachs were more strongly correlated with sediment samples from all three habitats than were those from the other two species. The species accumulation curves and higher mean dispersion values, compared with with sediment samples suggest that E. virescens is more efficient than sediment samples and the other fish studied at collecting benthic taxa. We conclude that by analyzing the stomach contents of benthophagous fishes it is possible to assess important characteristics of benthic communities (dispersion, taxonomic composition and diversity. This is especially true

  5. Environmental study of some metals on several aquatic macrophytes

    African Journals Online (AJOL)

    Administrator

    2011-09-26

    Sep 26, 2011 ... Concentration of Fe, Mn, Cu and Pb (mgkg-1 dry weight) in leaves, stems and roots of five macrophytes (BTS = Bidens tripartitus - stem, BTL = Bidens tripartitus – leaf, PAS = Polygonum amphibium - stem, PAL = Polygonum amphibium – leaf, LES = Lycopus europaeus - stem, LEL = Lycopus europaeus ...

  6. Macrophytes in estuarine gradients : Flow through flexible vegetation

    NARCIS (Netherlands)

    Dijkstra, J.T.

    2012-01-01

    Aquatic plants –or macrophytes- are an important part of coastal, estuarine and freshwater ecosystems worldwide, both from an ecological and an engineering viewpoint. Their meadows provide a wide range of ecosystem services: forming a physical protection of the shoreline, enhancing water quality and

  7. AMEG: the new SETAC advisory group on auqatic macrophyte ecotoxicology

    NARCIS (Netherlands)

    Arts, G.H.P.; Davies, J.; Dobbs, M.; Ebke, P.; Hanson, M.A.

    2010-01-01

    ntroduction and background Primary producers play critical structural and functional roles in aquatic ecosystems; therefore, it is imperative that the potential risks of toxicants to aquatic plants are adequately assessed in the risk assessment of chemicals. The standard required macrophyte test

  8. Macrophyte abundance and water quality status of three impacted ...

    African Journals Online (AJOL)

    Assessment of macrophyte abundance and water quality of three impacted inlet streams along Ikpa River Basin were investigated. A 5m x 5m quadrat through systematic sampling was used to sample the vegetation for density and frequency of species. Sediment and water samples were collected and analyzed using ...

  9. Different response of phytochelatins in two aquatic macrophytes ...

    African Journals Online (AJOL)

    Phytochelatins (PCs) have been proposed as potential biomarkers for an evaluation of metal toxicity. However, most studies have been generally limited to high concentrations of metals. In this study, two submerged macrophytes Ceratophyllum demersum L. and Elodea canadensis Michx. were adopted to investigate the ...

  10. The association between invertebrates and macrophytes in a ...

    African Journals Online (AJOL)

    The invertebrate fauna associated with aquatic macrophytes in the littoral of Lake Kariba was studied over a three-month period in 2002. Animals from seven classes — Hirudinea, Oligochaeta, Turbellaria, Insecta, Crustacea, Bivalvia and Gastropoda — were collected. Two hirudineans, Placobdella sp. and Haemopsis sp., ...

  11. Phytoplankton responses to changes in macrophyte density in a ...

    African Journals Online (AJOL)

    The response of phytoplankton population dynamics to changes in densities of Nymphaea lotus L. and Polygonum limbatum Meisn. was studied in an artificial pond in Zaria, Nigeria, from June to November 2007. Antagonistic effects of these macrophytes on Netrium sp., Staurastrum sp., Ulothrix sp., Marssionella sp. and ...

  12. Note - Des macrophytes pour épurer les eaux ?

    Directory of Open Access Journals (Sweden)

    BOUTIN, Catherine

    2014-12-01

    Full Text Available Utiliser des macrophytes pour mieux satisfaire les besoins humains est une part importante des recherches qui les concernent. Pour l’épuration des eaux usées et les aménagements associés, qu’en est-il ?

  13. Chemical warfare in freshwater, allelopathic effects of macrophytes on phytoplankton

    NARCIS (Netherlands)

    Mulderij, G.

    2006-01-01

    Aquatic macrophytes can excrete chemical substances into their enviroment and these compounds may inhibit the growth of phytoplankton. This process is defined as allelopathy: one organism has effects on another via the excretion of a (mixture of) chemical substance(s). With laboratory and field

  14. Chemical warfare in freshwater. Allelpathic effects of macrophytes on phytoplankton

    NARCIS (Netherlands)

    Mulderij, G.

    2006-01-01

    Aquatic macrophytes can excrete chemical substances into their enviroment and these compounds may inhibit the growth of phytoplankton. This process is defined as allelopathy: one organism has effects on another via the excretion of a (mixture of) chemical substance(s). With laboratory and field

  15. Experiments on growth interactions between two invasive macrophyte species

    NARCIS (Netherlands)

    Barrat-Segretain, M-H.; Elger, A.F.

    2004-01-01

    The success of invasive species has been attributed to the ability to displace other species by direct competition. We studied growth and possible competition between the two macrophyte species Elodea nuttallii and E. canadensis, because the former has been observed to replace the latter in the

  16. Répartition et valorisation des macrophytes envahissantes dans la ...

    African Journals Online (AJOL)

    ... of Littoral (Cameroon) threatened by invasive macrophytes, an ecological study highlighting the ... The floristic inventory showed that 2 species (Eichhornia crassipes and Panicum ... This plant can thus be used for biogas or compost production ... Tanzania (19); Togo (1); Tunisia (2); Uganda (12); Zambia (2); Zimbabwe (12).

  17. African Journal of Science and Technology (AJST) MACROPHYTES ...

    African Journals Online (AJOL)

    opiyo

    incidence des macrophytes aquatiques et du plancton sur la qualité des eaux du lac de Guiers», financé par la région Wallonne de Belgique avec l'appui de la. Fondation Universitaire Luxembourgeoise (Arlon). Nous les remercions pour leur concours.

  18. Biological interactions in the co-occurrence of Eichhornia azurea and free-floating macrophytes - DOI: 10.4025/actascibiolsci.v31i4.5577

    Directory of Open Access Journals (Sweden)

    Sidinei Magela Thomaz

    2009-08-01

    Full Text Available The dynamic of plant communities is strongly influenced by biological interactions. We studied the effects of Eichhornia azurea on the growth of the free-floating macrophytes Eichhornia crassipes, Salvinia minima, Salvinia auriculata and Limnobium laevigatum. The experiments were carried out in three lakes of the upper Paraná river floodplain. We used 0.5 m side squares where these species grew for 11 days (S. auriculata and L. laevigatum and 17 days (E. crassipes and S. minima, in the presence and absence of E. azurea. There were no significant differences between the relative growth rates of macrophytes growing in the absence and presence of E. azurea. The relative interaction index showed the existence of competition between E. azurea and L. laevigatum, and neutrality with the other three species. There was no evidence of facilitation related to the improvement of physico-chemistry characteristics that could enhance macrophytes growth. However, we do not discard a ‘mechanical’ facilitation between E. azurea, which offers protection against wind and waves, and the other species of macrophytes

  19. Colonization of leaf litter of two aquatic macrophytes, Mayaca fluviatilis Aublet and Salvinia auriculata Aublet by aquatic macroinvertebrates in a tropical reservoir

    Directory of Open Access Journals (Sweden)

    Marcia Cristina de Paula

    2011-04-01

    Full Text Available Decomposition and colonization of S. auriculata and M. fluviatilis by macroinvertebrates were analyzed during 40 days to determine whether differences existed on colonization by aquatic macroinvertebrates of two macrophytes with distinct habits (submerged versus fluctuant. Leaf litter of S. auriculata and M. fluviatilis were incubated in 24 litter bags (12 of each species, in a small reservoir surrounded by a cerrado fragment with low level of anthropic impact. After 10, 20, 30 and 40 days, the litter bags were removed and aquatic macroinvertebrates community was analyzed. Two hundred twenty macroinvertebrates were associated with S. auriculata and 261 were associated with M. fluviatilis, identified in 24 taxa. Both macrophyte species were colonized mainly by macroinvertebrate predators. Ablabesmyia with predator and collector food mechanisms was present in all sampling. The data showed an expressive increase of abundance during the process of decomposition and a decrease at the end of the experiment, in both macrophytes. Cluster analysis permitted inference that the colonization of the leaf liter by macroinvertebrates was determinated by incubation time of leaf litter not by the habit of macrophytes (submerged or fluctuant.

  20. Remediation of internal phosphorus loads with modified clays, influence of fluvial suspended particulate matter and response of the benthic macroinvertebrate community.

    Science.gov (United States)

    Yin, Hongbin; Douglas, Grant B; Cai, Yongjiu; Liu, Cheng; Copetti, Diego

    2018-01-01

    Clay-based phosphorus (P) sorbents have been increasingly used as geoengineering materials for the management sediment-derived internal P loading in eutrophic lakes. However, the long-term behavior of these sorbents has remained elusive along with their response to burial under suspended particulate matter (SPM), and their effect on macroinvertebrate communities occupying dynamic regions at the sediment-water interface of shallow and turbid lakes. In this study, field mesocosm experiments were undertaken in Lake Chaohu, China, to study the effects of the application of lanthanum-modified bentonite (LMB) and thermally-modified calcium-rich attapulgite (TCAP) on sediment internal P loading and to assess their influence on macroinvertebrate community structure. A complementary laboratory core incubation study was also undertaken to investigate the effects of SPM deposition on LMB and TCAP performance. In the field, both LMB and TCAP effectively intercepted P released from sediment for up to five months. A P fractionation analysis indicated that LMB and TCAP application results in a substantial increase in inert P fractions in sediment. Laboratory studies indicated that deposition of SPM may increase in mobile P both in the upper sediment and across the new post-SPM deposition sediment-water interface. Importantly, a comparison of sediment chemical extractions and estimated P fluxes suggests that chemically-defined forms of P in the sediment may be used as a proxy to estimate the net sediment P flux. Significantly, the surficial application of either LMB or TCAP did not cause negative effects on macroinvertebrate communities. This study indicates that to sustain a low P flux across the sediment-water interface in shallow, turbid lakes, repeat dosing of geoengineering materials, temporally aligned to the deposition of fluvial SPM, may be required. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. NEPR Benthic Habitat Map 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This benthic habitat map was created from a semi-automated habitat mapping process, using a combination of bathymetry, satellite imagery, aerial imagery and...

  2. National Benthic Infaunal Database (NBID)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NBID is a quantitative database on abundances of individual benthic species by sample and study region, along with other synoptically measured environmental...

  3. Benthic macroinvertebrates in Italian rice fields

    Directory of Open Access Journals (Sweden)

    Daniela Lupi

    2013-02-01

    Full Text Available Rice fields can be considered man-managed temporary wetlands. Five rice fields handled with different management strategies, their adjacent channels, and a spring were analysed by their benthic macroinvertebrate community to i evaluate the role of rice agroe- cosystem in biodiversity conservation; ii find indicator species which can be used to compare the ecological status of natural wetlands with rice agroecosystems; and iii find the influence of environmental variables on biodiversity. Different methods of data analysis with increasing degree of complexity – from diversity index up to sophisticated multivariate analysis – were used. The investigation provided a picture of benthic macroinvertebrates inhabiting rice agroecosystems where 173 taxa were identified, 89 of which detected in rice paddies. Among them, 4 phyla (Mollusca, Annelida, Nematomorpha, and Arthropoda, 8 classes (Bivalvia, Gastropoda, Oligochaeta, Hirudinea, Gordioida, Insecta, Branchiopoda, and Malacostraca, 24 orders, 68 families, 127 genera and 159 species have been found. Ten threatened and 3 invasive species were detected in the habitats examined. The information obtained by the different methods of data analysis allowed a more comprehensive view on the value of the components of rice agroecosystems. Data analyses highlighted significant differences between habitats (feeding channel and rice field, with higher diversity observed in channels, and emphasised the role of the water chemical-physical parameters. The period of water permanence in rice fields resulted to be only one of the factors influencing the community of benthic macroinvertebrates. The presence of rare/endangered species allowed characterising some stations, but it was less informative about management strategies in rice paddies because most of these species were absent in rice fields.

  4. The influence of the community of water macrophytes on regulation ...

    African Journals Online (AJOL)

    plzfg

    to-oxidise organic waste 61%, petrochemicals 92%, ammoniate ions 54%, nitrates 30%, nitrites. 24%, phosphates 25%, sulphates 46%, total mineralization 24%, saprophilic microorganisms. 97%, petroleum-oxidising bacteria 89%, and coliform bacteria 92%. Figures for the littoral zones of Mesha reach (Narmonka and and ...

  5. Bioassessment of Choghakhor Wetland using Benthic Macroinvertebrates

    Directory of Open Access Journals (Sweden)

    P. Fathi

    2016-05-01

    Full Text Available In present study, besides investigating benthic communities and their demographics in Choghakhor wetland, the water quality has been evaluated and classified. Then, 10 stations were selected and sampling of benthos was done every 45 days since April 2010 to March 2011, with 3 replications at each station. Samples were obtained by Ekman grab Sampler (surface 400 cm2. The collected samples were separated and fixed by formalin (4%. The Macroinvertebrates samples were identified and counted in laboratory. Generally 25 families of benthic macroinvertebrates belonging to 5 classes and 12 orders were identified. The results were calculated as community measures, including total richness, Shannon - Wiener diversity index and Hilsenhoff Biological index at family level. The results obtained from temporal and spatial changes of data (Statgeraphics software and water qualitative classification using Shannon diversity index conformed to biological Hilsenhoff index. And finally, water quality of wetland was assessed to be polluted in average to high level. According to this study findings, it seems that, these indicators could be used as useful tools for evaluating water supplies quality.

  6. Repeated 1-cm Resolution Topographic and 2.5-mm Resolution Photomosiac Surveys of Benthic Communities and Fine Scale Bedforms in Monterey Canyon

    Science.gov (United States)

    Caress, D. W.; Hobson, B.; Thomas, H. J.; Henthorn, R.; Martin, E. J.; Bird, L.; Risi, M.; Troni, G.; Paull, C. K.; Rock, S.; Padial, J. A.; Hammond, M. M.

    2014-12-01

    The Monterey Bay Aquarium Research Institute has developed a low altitude, ROV-based seafloor mapping system that combines lidar laser ranging, multibeam sonar, and stereo photographic imagery. When operated at a 3-m altitude, this system maps seafloor topography with a 1-cm lateral resolution and simultaneously collects 2.5-mm resolution color photography. We have twice mapped an 80-m by 80-m area of a chemosynthetic clam community located at 2850-m depth in the Monterey Canyon axis. Both the topography and the photomosaics resolve changes in the clam community over a six-month interval. Many individual animals have moved, and tracks of those animals are visible in the lidar topography. No other changes in the seafloor at this site can be discerned. We have also performed single surveys of bedforms and scours at both 1850-m and 2850-m depths in Monterey Canyon. The highest resolution bathymetry data are collected using a 3DatDepth SL1 lidar laser scanner. This system has a 30° field of view and ranges continuously, achieving a 1 cm sounding spacing at a 3 m altitude and 0.3 m/s speed. Bathymetry data are also collected using a 400-kHz Reson 7125 multibeam sonar. This configuration produces 512 beams across a 135° wide swath; each beam has a 0.5° acrosstrack by 1.0° alongtrack angular width. At a 3-m altitude, the nadir beams have a 2.5 cm acrosstrack and 5 cm alongtrack footprint. Dual Prosilica GX1920 2.4 Mpixel color cameras provide color stereo photography of the seafloor. Illumination is provided by dual xenon strobes. The camera housings have been fitted with corrective optics achieving a 90° field of view with less than 1% distortion. At a 3-m altitude the raw image pixels have a 2.5 mm resolution. Position and attitude data are provided by a Kearfott SeaDevil Inertial Navigation System (INS) integrated with a 300 kHz Teledyne RD Instruments Doppler velocity log (DVL). A separate Paroscientific pressure sensor is mounted adjacent to the INS. The INS

  7. Analysis of the impact of water level fluctuations on macrophytes in Miyun Reservoir after receiving water transferred by the South-to-North Water Diversion Project

    Science.gov (United States)

    Yu, L.; Gu, H.; Lou, C. H.; Zhang, L.; Meng, Q. Y.

    2016-08-01

    As the main primary producers in aquatic ecosystems, macrophytes affect the structure and function of aquatic ecosystems, and their distribution is controlled by water depth. Miyun Reservoir in Beijing will have to experience substantial changes in water level and surface area as it begins to receive water transferred by the South-to-North Water Diversion Project, which will have an adverse impact on the macrophytes growing there. In this study, a hydrodynamic model was constructed with MIKE21 and then used in a simulation in three scenarios: dry year, normal year and wet year. The results suggest that during water diversion, the annual and interannual water level fluctuations will be too significant for them to adapt and as a result, the original macrophytes in the reservoir tend to die and disappear completely. The area of the zone suitable for macrophyte growth, or suitable growth zone (SGZ), fluctuated. Restricted by the main dam and auxiliary dam to its south, the overall suitable growth zone moved toward the northeast and northwest of the reservoir, with a northeastward movement of its centroid. The distance and path of movement varied between scenarios. After the water diversion was completed, the suitable growth zone shrunk in the three scenarios. It is predicted that the macrophyte species diversity and richness of the reservoir can recover to the levels recorded before water diversion only in dry year. These results suggest that manual interventions should be implemented after water diversion to speed up the natural recovery of aquatic plant communities in Miyun Reservoir and thereby maintain the stability of the aquatic ecosystem.

  8. Management of fresh water weeds (macrophytes) by vermicomposting using Eisenia fetida.

    Science.gov (United States)

    Najar, Ishtiyaq Ahmed; Khan, Anisa B

    2013-09-01

    In the present study, potential of Eisenia fetida to recycle the different types of fresh water weeds (macrophytes) used as substrate in different reactors (Azolla pinnata reactor, Trapa natans reactor, Ceratophyllum demersum reactor, free-floating macrophytes mixture reactor, and submerged macrophytes mixture reactor) during 2 months experiment is investigated. E. fetida showed significant variation in number and weight among the reactors and during the different fortnights (P macrophytes mixture reactor (number 105 ± 5.77 %; weight 41.07 ± 3.97 % ). ANOVA showed significant variation in cocoon production (F4 = 15.67, P macrophyte affects the growth and reproduction pattern of E. fetida among the different reactors, further the addition of A. pinnata in other macrophytes reactors can improve their recycling by E. fetida.

  9. Next generation sequencing assays for benthic monitoring of the environmental impact associated with salmon farming (pilot study)

    DEFF Research Database (Denmark)

    Pawlowski, Jan; Esling, Philippe; Lejzerowicz, Franck

    2015-01-01

    This report presents the study of foraminiferal and metazoan benthic community based on next-generation sequencing (NGS) of environmental DNA and RNA (eDNA/RNA). The objective of this study was to test the application of NGS assays for benthic monitoring of salmon farms in Norway, in order to ove...

  10. The Use of Aquatic Macrophyte Ecotoxicological Assays in Monitoring Coastal Effluent Discharges in Southern Australia

    Energy Technology Data Exchange (ETDEWEB)

    Burridge, T.R.; Karistianos, M.; Bidwell, J

    1999-01-01

    Germination inhibition of zoospores of the aquatic, brown algal macrophyte Ecklonia radiata was employed to assess the toxicity of sewage effluents under short to long term exposure and under modified salinity conditions. The rate of germination inhibition was determined for exposure times between 2 and 48 h in salinity modified and unmodified regimes and under reduced salinity conditions alone. The results indicated that rate of germination inhibition increased with duration of exposure to sewage effluents and to salinity reduction alone, and that response to the effluents may be enhanced under conditions of reduced salinity. Whilst the effect of primary treated effluent was primarily that of toxicity, secondary treated effluent effects appeared to be primarily that of reduced salinity although at a greater rate than would be expected for salinity reduction alone. The assay is suggested to provide a mechanism for monitoring sewage effluent quality and to monitor potential impacts of sewage effluent discharge on kelp communities in southern Australia.

  11. The Use of Aquatic Macrophyte Ecotoxicological Assays in Monitoring Coastal Effluent Discharges in Southern Australia

    International Nuclear Information System (INIS)

    Burridge, T.R.; Karistianos, M.; Bidwell, J.

    1999-01-01

    Germination inhibition of zoospores of the aquatic, brown algal macrophyte Ecklonia radiata was employed to assess the toxicity of sewage effluents under short to long term exposure and under modified salinity conditions. The rate of germination inhibition was determined for exposure times between 2 and 48 h in salinity modified and unmodified regimes and under reduced salinity conditions alone. The results indicated that rate of germination inhibition increased with duration of exposure to sewage effluents and to salinity reduction alone, and that response to the effluents may be enhanced under conditions of reduced salinity. Whilst the effect of primary treated effluent was primarily that of toxicity, secondary treated effluent effects appeared to be primarily that of reduced salinity although at a greater rate than would be expected for salinity reduction alone. The assay is suggested to provide a mechanism for monitoring sewage effluent quality and to monitor potential impacts of sewage effluent discharge on kelp communities in southern Australia

  12. Invasive crayfish threaten the development of submerged macrophytes in lake restoration.

    Science.gov (United States)

    van der Wal, Jessica E M; Dorenbosch, Martijn; Immers, Anne K; Vidal Forteza, Constanza; Geurts, Jeroen J M; Peeters, Edwin T H M; Koese, Bram; Bakker, Elisabeth S

    2013-01-01

    Submerged macrophytes enhance water transparency and aquatic biodiversity in shallow water ecosystems. Therefore, the return of submerged macrophytes is the target of many lake restoration projects. However, at present, north-western European aquatic ecosystems are increasingly invaded by omnivorous exotic crayfish. We hypothesize that invasive crayfish pose a novel constraint on the regeneration of submerged macrophytes in restored lakes and may jeopardize restoration efforts. We experimentally investigated whether the invasive crayfish (Procambarus clarkii Girard) affects submerged macrophyte development in a Dutch peat lake where these crayfish are expanding rapidly. Seemingly favourable abiotic conditions for macrophyte growth existed in two 0.5 ha lake enclosures, which provided shelter and reduced turbidity, and in one lake enclosure iron was added to reduce internal nutrient loading, but macrophytes did not emerge. We transplanted three submerged macrophyte species in a full factorial exclosure experiment, where we separated the effect of crayfish from large vertebrates using different mesh sizes combined with a caging treatment stocked with crayfish only. The three transplanted macrophytes grew rapidly when protected from grazing in both lake enclosures, demonstrating that abiotic conditions for growth were suitable. Crayfish strongly reduced biomass and survival of all three macrophyte species while waterfowl and fish had no additive effects. Gut contents showed that crayfish were mostly carnivorous, but also consumed macrophytes. We show that P. clarkii strongly inhibit macrophyte development once favourable abiotic conditions for macrophyte growth are restored. Therefore, expansion of invasive crayfish poses a novel threat to the restoration of shallow water bodies in north-western Europe. Prevention of introduction and spread of crayfish is urgent, as management of invasive crayfish populations is very difficult.

  13. Impacts of Mechanical Macrophyte Removal Devices on Sediment Scouring in Littoral Habitats: II. Experimental Operation in the Littoral Zone of Eau Galle Reservoir, Wisconsin

    National Research Council Canada - National Science Library

    James, William F; Wright, David I; Barko, John W; Eakin, Harry L

    2006-01-01

    ... in Eau Galle Reservoir, Wisconsin. Mechanical macrophyte removal devices are an attractive, low-cost means of removing macrophytes in specific areas without herbicides or repeated mechanical harvesting...

  14. A study of the seasonal dynamics of three phycoperiphytic communities using nuclear track autoradiography. Pt. 1

    International Nuclear Information System (INIS)

    Pip, E.; Robinson, G.G.C.

    1982-01-01

    Net inorganic carbon uptake was examined for algal periphytic communities on Potamogeton richardsonii, P. praelongus and P. zosteriformis in a shallow lake. Nuclear track autoradiography was used to examine uptake for individual taxa comprising the communities. Net uptake rates per unit cell surface area were strongly correlated during the season for certain algal taxa, particularly diatoms, on the same macrophyte. The correlated taxa formed a different correlation cluster for each macrophyte. Although several of the same algal taxa appeared in the correlation clusters for different macrophytes, the behavior of a given taxon was only rarely correlated on different macrophytes. Each cluster behaved as an independent unit. Such organized behavior may be important in algal succession. Principal component analysis of the species-time uptake matrix isolated 3 main principal components that accounted for > 95% of the seasonal variation on all 3 macrophytes. (orig.)

  15. An ultrasonic method for separation of epiphytic microbes from freshwater submerged macrophytes.

    Science.gov (United States)

    Cai, Xianlei; Gao, Guang; Yang, Jing; Tang, Xiangming; Dai, Jiangyu; Chen, Dan; Song, Yuzhi

    2014-07-01

    Epiphytic microbes are common inhabitants of freshwater submerged macrophytes, which play an important role in aquatic ecosystems. An important precondition for studying the epiphytic microbes is having an effective method of separating the attached microbes from the host macrophytes. We developed an ultrasound-based method for separating epiphytic microbes from freshwater submerged macrophytes, optimized the conditions of ultrasonic separation with an orthogonal experimental design, and compared the optimized ultrasonic method with manual separation. This method can be particularly useful for freshwater submerged macrophytes having a complex morphology. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Size-dependent responses of zooplankton to submerged macrophyte restoration in a subtropical shallow lake

    Science.gov (United States)

    Zeng, Lei; He, Feng; Zhang, Yi; Liu, Biyun; Dai, Zhigang; Zhou, Qiaohong; Wu, Zhenbin

    2018-03-01

    To explore the size-dependent responses of zooplankton to submerged macrophyte restoration, we collected macrophyte, zooplankton and water quality samples seasonally from a subtropical shallow lake from 2010 to 2012. Special attention was given to changes in rotifers and crustaceans (cladocerans and copepods). The rotifers were grouped into three size classes (400 μm) to explore their size-related responses to macrophyte restoration. The results showed that during the restoration, the annual mean biomass and macrophyte coverage increased significantly from 0 to 637 g/m2 and 0 to 27%, respectively. In response, the density and biomass of crustaceans and the crustacean-to-rotifer ratio increased significantly, while the rotifer density decreased significantly. Moreover, rotifers showed significant sizedependent responses to macrophyte restoration. Specially, rotifers sized zooplankton tended to boom, while that of small rotifers was inhibited during macrophyte restoration. Redundancy analysis (RDA) revealed positive correlations between macrophytes and crustaceans, rotifers and COD or Chl- a, but negative correlations between macrophytes and COD or Chl- a, and between crustaceans and Chl- a. Moreover, the results indicate that increased predation on phytoplankton by large-sized zooplankton might be an important mechanism for macrophyte restoration during development of aquatic ecosystems, and that this mechanism played a very important role in promoting the formation of a clear-water state in subtropical shallow lakes.

  17. Biomechanical tactics of chiral growth in emergent aquatic macrophytes

    Science.gov (United States)

    Zhao, Zi-Long; Zhao, Hong-Ping; Li, Bing-Wei; Nie, Ben-Dian; Feng, Xi-Qiao; Gao, Huajian

    2015-01-01

    Through natural selection, many plant organs have evolved optimal morphologies at different length scales. However, the biomechanical strategies for different plant species to optimize their organ structures remain unclear. Here, we investigate several species of aquatic macrophytes living in the same natural environment but adopting distinctly different twisting chiral morphologies. To reveal the principle of chiral growth in these plants, we performed systematic observations and measurements of morphologies, multiscale structures, and mechanical properties of their slender emergent stalks or leaves. Theoretical modeling of pre-twisted beams in bending and buckling indicates that the different growth tactics of the plants can be strongly correlated with their biomechanical functions. It is shown that the twisting chirality of aquatic macrophytes can significantly improve their survivability against failure under both internal and external loads. The theoretical predictions for different chiral configurations are in excellent agreement with experimental measurements. PMID:26219724

  18. Reaeration of oxygen in shallow, macrophyte rich streams. 1

    International Nuclear Information System (INIS)

    Thyssen, N.; Erlandsen, M.; Jeppesen, E.

    1987-01-01

    The rate coefficient K 2 for the exchange of oxygen between flowing water and the atmosphere (reaeration) has been studied in six Danish streams covering a relatively wide range of hydraulic conditions, pollutional loading, and macrophyte abundance. 103 K 2 measurements were performed in 1978-85. 82 measurements were obtained applying 5 different indirect methods all balancing the sources and sinks of stream dissolved oxygen under conditions of normal operation of the system (3 methods) and under artificial depletion of the oxygen concentration of the stream water by addition of sodium sulfite (2 methods). 21 K 2 values were determined directly applying the gaseous tracer 85 Kr for reaeration. Guidelines for selecting a proper method to determine K 2 knowing macrophyte biomass and loading characteristics of the particular stream are provided. (author)

  19. Elemental gradients in macrophytes from a reactor effluent gradient

    International Nuclear Information System (INIS)

    Grace, J.B.; Tilly, L.J.

    1978-01-01

    The tissues of submersed macrophtes from along the thermal gradient were analyzed for phosphorus to determine whether any pattern correspondent to standing crop distributions could be detected. Although water concentrations of phosphorus showed no detectable relationship to the thermal effluent, tissue concentrations of this element in submersed macrophytes declined with distance from the effluent entry point. The occurrence of this concentration pattern suggests that phosphorus availability is greater near the discharge. Because phosphorus is the element most often determined to limit aquatic productivity, its greater availability may partially account for the apparent enhancement of macrophte growth near the thermal discharge. A patter of macrophyte abundance which indicated enchancement related to the discharge gradient in the reactor-cooling reservoir, Par Pond is reported. Correlative data tended to implicate light and temperature as important in influencing the differential abundance pattern

  20. Bacterial growth on macrophyte leachate and fate of bacterial production

    International Nuclear Information System (INIS)

    Findlay, S.; Carlough, L.; Crocker, M.T.; Gill, H.K.; Meyer, J.L.; Smith, P.J.

    1986-01-01

    The role bacteria play in transferring organic carbon to other trophic levels in aquatic ecosystems depends on the efficiency with which they convert dissolved organic [ 14 C]-labelled carbon into bacterial biomass and on the ability of consumers to graze bacteria. The authors have measured the conversion efficiency for bacteria growing on macrophyte-derived dissolved organic carbon and estimated the amount of bacterial production removed by grazing. Bacteria converted this DOC into new tissue with an efficiency of 53%, substantially higher than the apparent conversion efficiency of macrophyte-derived particulate organic carbon or other types of DOC. Two estimates of grazing indicate that the decline in bacterial numbers after the bloom was probably due to grazing by flagellates. These results show the significance of the bacterial link between DOC and other trophic levels

  1. Aquatic macrophyte diversity of the Pantanal wetland and upper basin

    Directory of Open Access Journals (Sweden)

    VJ. Pott

    Full Text Available This is a short review of the state of the art concerning diversity of aquatic macrophytes and the main aquatic vegetation types in the Brazilian Pantanal wetland and upper watershed. There are ca. 280 species of aquatic macrophytes on the Pantanal floodplain, with scarce endemism. On the upper watershed, Cerrado wetlands (veredas and limestone springs have a distinct flora from the Pantanal, with twice the species richness. As a representative case of aquatic habitats influenced by river flood, some primary data are presented for the Pantanal Matogrossense National Park and associated Acurizal Preserve, analysing the floristic similarity among aquatic vegetation types. We comment on problems of conservation and observe that Panicum elephantipes Nees is one of the few natives to compete with the invasive Urochloa arrecta (Hack. ex T. Durand & Schinz Morrone & Zuloaga.

  2. Establishing Functional Relationships between Abiotic Environment, Macrophyte Coverage, Resource Gradients and the Distribution of Mytilus trossulus in a Brackish Non-Tidal Environment.

    Directory of Open Access Journals (Sweden)

    Jonne Kotta

    Full Text Available Benthic suspension feeding mussels are an important functional guild in coastal and estuarine ecosystems. To date we lack information on how various environmental gradients and biotic interactions separately and interactively shape the distribution patterns of mussels in non-tidal environments. Opposing to tidal environments, mussels inhabit solely subtidal zone in non-tidal waterbodies and, thereby, driving factors for mussel populations are expected to differ from the tidal areas. In the present study, we used the boosted regression tree modelling (BRT, an ensemble method for statistical techniques and machine learning, in order to explain the distribution and biomass of the suspension feeding mussel Mytilus trossulus in the non-tidal Baltic Sea. BRT models suggested that (1 distribution patterns of M. trossulus are largely driven by separate effects of direct environmental gradients and partly by interactive effects of resource gradients with direct environmental gradients. (2 Within its suitable habitat range, however, resource gradients had an important role in shaping the biomass distribution of M. trossulus. (3 Contrary to tidal areas, mussels were not competitively superior over macrophytes with patterns indicating either facilitative interactions between mussels and macrophytes or co-variance due to common stressor. To conclude, direct environmental gradients seem to define the distribution pattern of M. trossulus, and within the favourable distribution range, resource gradients in interaction with direct environmental gradients are expected to set the biomass level of mussels.

  3. Application of macrophytes as biosorbents for radioactive liquid waste treatment

    International Nuclear Information System (INIS)

    Vieira, Ludmila Cabreira

    2016-01-01

    Radioactive waste as any other type of waste should be treated and disposed adequately. It is necessary to consider its physical, chemical and radiological characteristics for choosing the appropriate action for the treatment and final disposal. Many treatment techniques currently used are economically costly, often invalidating its use and favoring the study of other treatment techniques. One of these techniques is biosorption, which demonstrates high potential when applied to radioactive waste. This technology uses materials of biological origin for removing metals. Among potential biosorbents found, macrophyte aquatics are useful because they may remove uranium present in the liquid radioactive waste at low cost. This study aims to evaluate the biosorption capacity of macrophyte aquatics Pistia stratiotes, Limnobium laevigatum, Lemna sp and Azolla sp in the treatment of liquid radioactive waste. This study was divided into two stages, the first one is characterization and preparation of biosorption and the other is tests, carried out with uranium solutions and real samples. The biomass was tested in its raw form and biosorption assays were performed in polypropylene vials containing 10 ml of solution of uranium or 10ml of radioactive waste and 0.20g of biomass. The behavior of biomass was evaluated by sorption kinetics and isotherm models. The highest sorption capacities found was 162.1 mg / g for the macrophyte Lemna sp and 161.8 mg / g for the Azolla sp. The equilibrium times obtained were 1 hour for Lemna sp, and 30 minutes for Azolla sp. With the real waste, the macrophyte Azolla sp presented a sorption capacity of 2.6 mg / g. These results suggest that Azolla sp has a larger capacity of biosorption, therefore it is more suitable for more detailed studies of treatment of liquid radioactive waste. (author)

  4. Impact of Invertebrate Herbivory on Native Aquatic Macrophytes

    Science.gov (United States)

    2007-08-01

    this macroalga occupied the entire water column, it may have had a competitive advantage for light over V. americana, which grew closer to the...dry biomass of five macrophyte species between two treatments ; an insecticide treatment to remove invertebrate herbivores, and a control where the...Heitmeyer and Vohs 1984, Dibble et al. 1996), improve water clarity and quality, and reduce rates of shoreline erosion and sediment resuspension (Smart

  5. Human impacts on large benthic foraminifers near a densely populated area of Majuro Atoll, Marshall Islands.

    Science.gov (United States)

    Osawa, Yoko; Fujita, Kazuhiko; Umezawa, Yu; Kayanne, Hajime; Ide, Yoichi; Nagaoka, Tatsutoshi; Miyajima, Toshihiro; Yamano, Hiroya

    2010-08-01

    Human impacts on sand-producing, large benthic foraminifers were investigated on ocean reef flats at the northeast Majuro Atoll, Marshall Islands, along a human population gradient. The densities of dominant foraminifers Calcarina and Amphistegina declined with distance from densely populated islands. Macrophyte composition on ocean reef flats differed between locations near sparsely or densely populated islands. Nutrient concentrations in reef-flat seawater and groundwater were high near or on densely populated islands. delta(15)N values in macroalgal tissues indicated that macroalgae in nearshore lagoons assimilate wastewater-derived nitrogen, whereas those on nearshore ocean reef flats assimilate nitrogen from other sources. These results suggest that increases in the human population result in high nutrient loading in groundwater and possibly into nearshore waters. High nutrient inputs into ambient seawater may have both direct and indirect negative effects on sand-producing foraminifers through habitat changes and/or the collapse of algal symbiosis. Copyright 2010 Elsevier Ltd. All rights reserved.

  6. Human impacts on large benthic foraminifers near a densely populated area of Majuro Atoll, Marshall Islands

    International Nuclear Information System (INIS)

    Osawa, Yoko; Fujita, Kazuhiko; Umezawa, Yu; Kayanne, Hajime; Ide, Yoichi; Nagaoka, Tatsutoshi; Miyajima, Toshihiro; Yamano, Hiroya

    2010-01-01

    Human impacts on sand-producing, large benthic foraminifers were investigated on ocean reef flats at the northeast Majuro Atoll, Marshall Islands, along a human population gradient. The densities of dominant foraminifers Calcarina and Amphistegina declined with distance from densely populated islands. Macrophyte composition on ocean reef flats differed between locations near sparsely or densely populated islands. Nutrient concentrations in reef-flat seawater and groundwater were high near or on densely populated islands. δ 15 N values in macroalgal tissues indicated that macroalgae in nearshore lagoons assimilate wastewater-derived nitrogen, whereas those on nearshore ocean reef flats assimilate nitrogen from other sources. These results suggest that increases in the human population result in high nutrient loading in groundwater and possibly into nearshore waters. High nutrient inputs into ambient seawater may have both direct and indirect negative effects on sand-producing foraminifers through habitat changes and/or the collapse of algal symbiosis.

  7. Oxygen uptake from aquatic macrophyte decomposition from Piraju Reservoir (Piraju, SP, Brazil

    Directory of Open Access Journals (Sweden)

    I. Bianchini Jr.

    Full Text Available The kinetics of oxygen consumption related to mineralisation of 18 taxa of aquatic macrophytes (Cyperus sp, Azolla caroliniana, Echinodorus macrophyllus, Eichhornia azurea, Eichhornia crassipes, Eleocharis sp1, Eleocharis sp2, Hetereanthera multiflora, Hydrocotyle raniculoides, Ludwigia sp, Myriophyllum aquaticum, Nymphaea elegans, Oxycaryum cubense, Ricciocarpus natans, Rynchospora corymbosa, Salvinia auriculata, Typha domingensis and Utricularia foliosa from the reservoir of Piraju Hydroelectric Power Plant (São Paulo state, Brazil were described. For each species, two incubations were prepared with ca. 300.0 mg of plant (DW and 1.0 L of reservoir water sample. The incubations were maintained in the dark and at 20 ºC. Periodically the dissolved oxygen (DO concentrations were measured; the accumulated DO values were fitted to 1st order kinetic model and the results showed that: i high oxygen consumption was observed for Ludwigia sp (533 mg g-1 DW, while the lowest was registered for Eleocharis sp1 (205 mg g-1 DW mineralisation; ii the higher deoxygenation rate constants were verified in the mineralisation of A. caroliniana (0.052 day-1, H. raniculoides (0.050 day-1 and U. foliosa (0.049 day-1. The oxygen consumption rate constants of Ludwigia sp and Eleocharis sp2 mineralisation (0.027 day-1 were the lowest. The half-time of oxygen consumption varied from 9 to 26 days. In the short term, the detritus of E. macrophyllus, H. raniculoides, Ludwigia sp, N. elegans and U. foliosa were the critical resources to the reservoir oxygen demand; while in the long term, A. caroliniana, H. multiflora and T. domingensis were the resources that can potentially contribute to the benthic oxygen demand of this reservoir.

  8. Arsenic rich iron plaque on macrophyte roots - an ecotoxicological risk?

    International Nuclear Information System (INIS)

    Taggart, M.A.; Mateo, R.; Charnock, J.M.; Bahrami, F.; Green, A.J.; Meharg, A.A.

    2009-01-01

    Arsenic is known to accumulate with iron plaque on macrophyte roots. Three to four years after the Aznalcollar mine spill (Spain), residual arsenic contamination left in seasonal wetland habitats has been identified in this form by scanning electron microscopy. Total digestion has determined arsenic concentrations in thoroughly washed 'root + plaque' material in excess of 1000 mg kg -1 , and further analysis using X-ray absorption spectroscopy suggests arsenic exists as both arsenate and arsenite. Certain herbivorous species feed on rhizomes and bulbs of macrophytes in a wide range of global environments, and the ecotoxicological impact of consuming arsenic rich iron plaque associated with such food items remains to be quantified. Here, greylag geese which feed on Scirpus maritimus rhizome and bulb material in areas affected by the Aznalcollar spill are shown to have elevated levels of arsenic in their feces, which may originate from arsenic rich iron plaque. - Accumulation of metals with iron plaque on macrophyte roots in wetlands poses an ecotoxicological risk to certain herbivores

  9. Arsenic rich iron plaque on macrophyte roots - an ecotoxicological risk?

    Energy Technology Data Exchange (ETDEWEB)

    Taggart, M.A. [School of Biological Sciences, University of Aberdeen, Cruickshank Bld, St Machar Drive, Aberdeen, AB24 3UU (United Kingdom); Instituto de Investigacion en Recursos Cinegeticos, IREC (CSIC-UCLM-JCCM), Ronda de Toledo s/n, 13005 Ciudad Real (Spain)], E-mail: mark.taggart@uclm.es; Mateo, R. [Instituto de Investigacion en Recursos Cinegeticos, IREC (CSIC-UCLM-JCCM), Ronda de Toledo s/n, 13005 Ciudad Real (Spain); Charnock, J.M.; Bahrami, F. [Synchrotron Radiation Department, CCLRC Daresbury Laboratory, Warrington, Cheshire, WA4 4AD (United Kingdom); Green, A.J. [Department of Wetland Ecology, Estacion Biologica de Donana, CSIC, Pabellon del Peru, Avenida Maria Luisa s/n, 41013 Seville (Spain); Meharg, A.A. [School of Biological Sciences, University of Aberdeen, Cruickshank Bld, St Machar Drive, Aberdeen, AB24 3UU (United Kingdom)

    2009-03-15

    Arsenic is known to accumulate with iron plaque on macrophyte roots. Three to four years after the Aznalcollar mine spill (Spain), residual arsenic contamination left in seasonal wetland habitats has been identified in this form by scanning electron microscopy. Total digestion has determined arsenic concentrations in thoroughly washed 'root + plaque' material in excess of 1000 mg kg{sup -1}, and further analysis using X-ray absorption spectroscopy suggests arsenic exists as both arsenate and arsenite. Certain herbivorous species feed on rhizomes and bulbs of macrophytes in a wide range of global environments, and the ecotoxicological impact of consuming arsenic rich iron plaque associated with such food items remains to be quantified. Here, greylag geese which feed on Scirpus maritimus rhizome and bulb material in areas affected by the Aznalcollar spill are shown to have elevated levels of arsenic in their feces, which may originate from arsenic rich iron plaque. - Accumulation of metals with iron plaque on macrophyte roots in wetlands poses an ecotoxicological risk to certain herbivores.

  10. Monitoring of selenium in macrophytes - the case of Slovenia.

    Science.gov (United States)

    Mechora, Špela; Germ, Mateja; Stibilj, Vekoslava

    2014-09-01

    This paper examines macrophytes from various locations in Slovenian streams for selenium (Se) content in an attempt to discover if Se contamination is present and if Se uptake varies between sampling sites. For this purpose, macrophytes and water from ten locations in the Notranjska and Central regions (Slovenia) with different land use in the catchment were sampled. To assess the environmental conditions of the streams the Riparian, Channel, and Environment (RCE) inventory was applied, which revealed that investigated stretches of streams fall into RCE classes III, IV and V. The concentration of Se in water at all locations was less than 1μgSeL(-1). The Se content in macrophytes differed between sampling sites, with the highest content of Se in samples from Žerovniščica stream and the lowest in samples from Lipsenjščica stream. The content of Se was the highest in moss samples (3038ngSeg(-1) DM) and in the amphibious species Veronica anagallis-aquatica (1507ngSeg(-1) DM). Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Hexabromocyclododecane affects benthic-pelagic coupling in an experimental ecosystem

    International Nuclear Information System (INIS)

    Bradshaw, Clare; Näslund, Johan; Hansen, Joakim; Kozlowsky-Suzuki, Betina; Sundström, Bo; Gustafsson, Kerstin

    2015-01-01

    Hexabromocyclododecane (HBCDD) is an additive brominated flame retardant and a recognized PBT chemical. However, little is known about its effects on coastal species, and even less on ecosystem effects. We investigated the dose–response effects of HBCDD over 8 months in 1000 L experimental mesocosms assembled from coastal Baltic Sea ecosystem components. HBCDD was added via spiked plankton material and a range of structural and functional endpoints were measured during the experiment. Increasing HBCDD concentration decreased the biomass of large Macoma balthica, resulting in a decreased recirculation of nutrients to the water. Changes in plankton communities were also observed, either due to direct toxic HBCDD effects or indirect via changes in benthic-pelagic coupling of nutrients. Such complex ecosystem responses can only be quantified and understood by using realistic experimental set-ups, and including knowledge of system-specific ecological interactions. This is the first study of HBCDD effects on ecosystem level. - Graphical abstract: HBCDD caused direct effects on the population structure of sediment-dwelling Macoma balthica and on the plankton community. Indirect HBCDD effects via reduced nutrient remineralization by M. balthica affected nutrient levels in the water, likely leading to additional changes in plankton community structure. Seasonal effects were large and affected the whole system including nutrient dynamics as well as plankton community structure. Display Omitted - Highlights: • HBCDD caused effects on benthic population structure and ecosystem function. • Large seasonal effects highlight the importance of using relevant experimental conditions. • A realistic exposure pathway was applied by using HBCDD enriched plankton material. • This is the first study of HBCDD effects on ecosystem level, coupling benthic and pelagic communities. - HBCDD has a dose-dependent effect on benthic-pelagic coupling.

  12. Landscapes of facilitation: how self-organized patchiness of aquatic macrophytes promotes diversity in streams.

    Science.gov (United States)

    Cornacchia, Loreta; van de Koppel, Johan; van der Wal, Daphne; Wharton, Geraldene; Puijalon, Sara; Bouma, Tjeerd J

    2018-04-01

    Spatial heterogeneity plays a crucial role in the coexistence of species. Despite recognition of the importance of self-organization in creating environmental heterogeneity in otherwise uniform landscapes, the effects of such self-organized pattern formation in promoting coexistence through facilitation are still unknown. In this study, we investigated the effects of pattern formation on species interactions and community spatial structure in ecosystems with limited underlying environmental heterogeneity, using self-organized patchiness of the aquatic macrophyte Callitriche platycarpa in streams as a model system. Our theoretical model predicted that pattern formation in aquatic vegetation - due to feedback interactions between plant growth, water flow and sedimentation processes - could promote species coexistence, by creating heterogeneous flow conditions inside and around the plant patches. The spatial plant patterns predicted by our model agreed with field observations at the reach scale in naturally vegetated rivers, where we found a significant spatial aggregation of two macrophyte species around C. platycarpa. Field transplantation experiments showed that C. platycarpa had a positive effect on the growth of both beneficiary species, and the intensity of this facilitative effect was correlated with the heterogeneous hydrodynamic conditions created within and around C. platycarpa patches. Our results emphasize the importance of self-organized patchiness in promoting species coexistence by creating a landscape of facilitation, where new niches and facilitative effects arise in different locations. Understanding the interplay between competition and facilitation is therefore essential for successful management of biodiversity in many ecosystems. © 2018 The Authors Ecology published by Wiley Periodicals, Inc. on behalf of Ecological Society of America.

  13. 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.

  14. The structuring role of submerged macrophytes in a large subtropical shallow lake

    NARCIS (Netherlands)

    Finkler Ferreira, Tiago; Crossetti, Luciane O.; Motta Marques, David M.L.; Cardoso, Luciana; Fragoso, Carlos Ruberto; Nes, van Egbert H.

    2018-01-01

    It is well known that submerged macrophytes exert positive feedback effects that enhance the water transparency, stabilizing the clear-water state in shallow temperate lakes. However, the structuring effect of macrophytes on the food web of subtropical and tropical ecosystems is still poorly

  15. A propos de l'EQB macrophytes en cours d'eau dans les DOM : Note

    OpenAIRE

    Chauvin, C.

    2015-01-01

    / Cette note présente les éléments essentiels ressortis de la mission "macrophytes" 2012-2013menée dans les DOM, en ce qui concerne la pertinence et la faisabilité d'un indicateur d'état écologique en cours d'eau basé sur les macrophytes.

  16. Macrophytes in the cooling ponds of Ukrainian nuclear and thermal power plants

    International Nuclear Information System (INIS)

    D'yachenko, T.N.

    2013-01-01

    Attention is focused at the macrophytes role in the functioning of the natural-technological cooling ponds ecosystems, at the features of aquatic plants and station water supply system interaction. It was considered the degree of macrophytes scrutiny and it was pointed out the necessity of monitoring and controlling their condition in the cooling ponds of Ukrainian power plants.

  17. Effects of linuron on a rooted aquatic macrophyte in sediment-dosed test systems

    NARCIS (Netherlands)

    Buresova, H.; Crum, S.J.H.; Belgers, J.D.M.; Adriaanse, P.I.; Arts, G.H.P.

    2013-01-01

    Effects of linuron on the sediment-rooted aquatic macrophyte Myriophyllum spicatum L. were studied in sediment-dosed test systems following a proposed guideline with extended test duration. Sediment, pore water, overlying water and macrophyte shoots were sampled weekly for chemical analyses. Linuron

  18. Competition between free-floating and submerged macrophytes in a future of climate change

    NARCIS (Netherlands)

    Netten, J.J.C.

    2011-01-01


    This research was about the asymmetric competition between free-floating and submerged macrophytes in shallow freshwater ecosystems. I studied the effect of climate change on the dominance of free-floating macrophytes in temperate regions. The research approach was a combination of outdoor

  19. Macrophyte species distribution, indices of biotic integrity and sampling intensity in isolated Florida marshes

    Science.gov (United States)

    This study tested macrophyte condition metrics calculated after decreasing the effort and area of sampling by 33% to 66%, as tested in 74 emergent isolated wetlands. Four belted transects from wetland edge to center were established and rooted macrophytes were identified. The eff...

  20. Estimating benthic secondary production from aquatic insect emergence in streams affected by mountaintop removal coal mining, West Virginia USA

    Science.gov (United States)

    Mountaintop removal and valley fill (MTR/VF) coal mining recountours the Appalachian landscape, buries headwater stream channels, and degrades downstream water quality. The goal of this study was to compare benthic community production estimates, based on seasonal insect emergen...

  1. Benthic grab data from October 1994 in the Lower Bay of New York/New Jersey Harbor

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic grab samples were collected using a Shipek grab at pre-determined locations in the harbor. Taxonomic enumerations and biological community parameters were...

  2. [Effects of light on submerged macrophytes in eutrophic water: research progress].

    Science.gov (United States)

    Li-Sha, Zou; Ze-Yu, Nie; Xiao-Yan, Yao; Ji-Yan, Shi

    2013-07-01

    The restoration of submerged macrophytes is the key to remediate eutrophic water and maintain the health of aquatic ecosystem, while light is the main limiting factor. This paper summarized the factors affecting the light extinction in water and the mechanisms of light intensity affecting the physiology of submerged macrophytes, with the focuses on the metabolic mechanisms of carbon, nitrogen, and phosphorus, the responses of antioxidant enzyme system, and the feedbacks of pigment composition and concentration in the common submerged macrophytes under low light stress. Several engineering techniques applied in the ecological restoration of submerged macrophytes were presented, and the framework of the restoration of submerged macrophytes in eutrophic water was proposed. Some problems in current research and several suggestions on future research were addressed, which could help the related research and engineering practices.

  3. Carbonic anhydrase levels and internal lacunar CO/sub 2/ concentrations in aquatic macrophytes

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, C.I.

    1979-01-01

    Carbonic anhydrase levels were examined in a variety of aquatic macrophytes from different habitats. In general, carbonic anhydrase levels increased across the habitat gradient such that activities were low in submersed aquatic macrophytes and high in emergent macrophytes with floating-leaved and free-floating plants exhibiting intermediate activities. Internal lacunar CO/sub 2/ concentrations were analyzed in relation to carbonic anhydrase activities. There was no correlation between these two parameters. Internal CO/sub 2/ concentrations ranged from low to high in submersed macrophytes, but were low in floating-leaved and emergent macrophytes. The observed internal CO/sub 2/ concentrations are discussed in relation to the individual morphologies of the plants and the environments in which they occurred.

  4. The role of emergent vegetation in structuring aquatic insect communities in peatland drainage ditches

    NARCIS (Netherlands)

    Whatley, M.H.; van Loon, E.E.; Vonk, J.A.; van der Geest, H.G.; Admiraal, W.

    2014-01-01

    Availability of macrophyte habitat is recognized as an important driver of aquatic insect communities in peatland drainage ditches; however, eutrophication can lead to the decline of submerged vegetation. While emergent vegetation is able to persist in eutrophicated ditches, vegetation removal,

  5. Can aquatic macrophytes be biofilters for gadolinium based contrasting agents?

    Science.gov (United States)

    Braun, Mihály; Zavanyi, Györgyi; Laczovics, Attila; Berényi, Ervin; Szabó, Sándor

    2018-05-15

    The use of gadolinium-based contrasting agents (GBCA) is increasing because of the intensive usage of these agents in magnetic resonance imaging (MRI). Waste-water treatment does not reduce anthropogenic Gd-concentration significantly. Anomalous Gd-concentration in surface waters have been reported worldwide. However, removal of GBCA-s by aquatic macrophytes has still hardly been investigated. Four aquatic plant species (Lemna gibba, Ceratophyllum demersum, Elodea nuttallii, E. canadensis) were investigated as potential biological filters for removal of commonly used but structurally different GBCA-s (Omniscan, Dotarem) from water. These plant species are known to accumulate heavy metals and are used for removing pollutants in constructed wetlands. The Gd uptake and release of the plants was examined under laboratory conditions. Concentration-dependent infiltration of Gd into the body of the macrophytes was measured, however significant bioaccumulation was not observed. The tissue concentration of Gd reached its maximum value between day one and four in L. gibba and C. demersum, respectively, and its volume was significantly higher in C. demersum than in L. gibba. In C. demersum, the open-chain ligand Omniscan causes two-times higher tissue Gd concentration than the macrocyclic ligand Dotarem. Gadolinium was released from Gd-treated duckweeds into the water as they were grown further in Gd-free nutrient solution. Tissue Gd concentration dropped by 50% in duckweed treated by Omniscan and by Dotarem within 1.9 and 2.9 days respectively. None of the macrophytes had a significant impact on the Gd concentration of water in low and medium concentration levels (1-256 μg L -1 ). Biofiltration of GBCA-s by common macrophytes could not be detected in our experiments. Therefore it seems that in constructed wetlands, aquatic plants are not able to reduce the concentration of GBCA-s in the water. Furthermore there is a low risk that these plants cause the

  6. Benthic nitrogen loss in the Arabian Sea off Pakistan

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    Sarah eSokoll

    2012-11-01

    Full Text Available A pronounced deficit of nitrogen (N in the oxygen minimum zone (OMZ of theArabian Sea suggests the occurrence of heavy N-loss that is commonly attributed to pelagicprocesses. However, the OMZ water is in direct contact with sediments on three sides of thebasin. Contribution from benthic N-loss to the total N-loss in the Arabian Sea remains largelyunassessed. In October 2007, we sampled the water column and surface sediments along atransect cross-cutting the Arabian Sea OMZ at the Pakistan continental margin, covering arange of station depths from 360 to 1430 m. Benthic denitrification and anammox rates weredetermined by using 15N-stable isotope pairing experiments. Intact core incubations showeddeclining rates of total benthic N-loss with water depth from 0.55 to 0.18 mmol N m-2 d-1.While denitrification rates measured in slurry incubations decreased from 2.73 to 1.46 mmolN m-2 d-1 with water depth, anammox rates increased from 0.21 to 0.89 mmol N m-2 d-1.Hence, the contribution from anammox to total benthic N-loss increased from 7% at 360 m to40% at 1430 m. This trend is further supported by the quantification of nirS, the biomarkerfunctional gene encoding for cytochrome cd1-nitrite reductases of microorganisms involved inboth N-loss processes. Anammox-like nirS genes within the sediments increased in proportionto total nirS gene copies with water depth. Moreover, phylogenetic analyses of nirS revealeddifferent communities of both denitrifying and anammox bacteria between shallow and deepstations. Together, rate measurement and nirS analyses showed that anammox, determined forthe first time in the Arabian Sea sediments, is an important benthic N-loss process at thecontinental margin off Pakistan, especially in the sediments at deeper water depths.Extrapolation from the measured benthic N-loss to all shelf sediments within the basinsuggests that benthic N-loss may be responsible for about half of the overall N-loss in theArabian Sea.

  7. Benthic oxygen consumption on continental shelves off eastern Canada

    Science.gov (United States)

    Grant, Jonathan; Emerson, Craig W.; Hargrave, Barry T.; Shortle, Jeannette L.

    1991-08-01

    The consumption of phytoplankton production by the benthos is an important component of organic carbon budgets for continental shelves. Sediment texture is a major factor regulating benthic processes because fine sediment areas are sites of enhanced deposition from the water column, resulting in increased organic content, bacterial biomass and community metabolism. Although continental shelves at mid- to high latitudes consist primarily of coarse relict sediments ( PIPER, Continental Shelf Research, 11, 1013-1035), shelf regions of boreal and subarctic eastern Canada contain large areas of silt and clay sediments ( FADER, Continental Shelf Research, 11, 1123-1153). We collated estimates of benthic oxygen consumption in coarse (<20% silt-clay, <0.5% organic matter) and fine sediments (20% silt-clay, 0.5% organic matter) for northwest Atlantic continental shelves including new data for Georges Bank, the Scotian Shelf, the Grand Banks of Newfoundland and Labrador Shelf. Estimates were applied to the areal distribution of sediment type on these shelves to obtain a general relationship between sediment texture and benthic carbon consumption. Mean benthic oxygen demand was 2.7 times greater in fine sediment than in coarse sediment, when normalized to mean annual temperature. In terms of carbon equivalents, shelf regions with minimal fine sediment (Georges Bank, the Grand Banks of Newfoundland-northeast Newfoundland) consumed only 5-8% of annual primary production. Benthos of the Gulf of Maine (100% fine sediment) and the Scotian Shelf (35% fine sediment) utilized 16-19% of primary production. Although 32% of the Labrador Shelf area contained fine sediments, benthic consumption of pelagic production (8%) was apparently limited by low mean annual temperature (2°C). These results indicate that incorporation of sediment-specific oxygen uptake into shelf carbon budgets may increase estimates of benthic consumption by 50%. Furthermore, respiration and production by large

  8. Effects of coral reef benthic primary producers on dissolved organic carbon and microbial activity.

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    Andreas F Haas

    Full Text Available Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates of photosynthesis, respiration, and dissolved organic carbon (DOC release were assessed for several common benthic reef organisms from the backreef habitat. We assessed microbial community response to dissolved exudates of each benthic producer by measuring bacterioplankton growth, respiration, and DOC drawdown in two-day dark dilution culture incubations. Experiments were conducted for six benthic producers: three species of macroalgae (each representing a different algal phylum: Turbinaria ornata--Ochrophyta; Amansia rhodantha--Rhodophyta; Halimeda opuntia--Chlorophyta, a mixed assemblage of turf algae, a species of crustose coralline algae (Hydrolithon reinboldii and a dominant hermatypic coral (Porites lobata. Our results show that all five types of algae, but not the coral, exuded significant amounts of labile DOC into their surrounding environment. In general, primary producers with the highest rates of photosynthesis released the most DOC and yielded the greatest bacterioplankton growth; turf algae produced nearly twice as much DOC per unit surface area than the other benthic producers (14.0±2.8 µmol h⁻¹ dm⁻², stimulating rapid bacterioplankton growth (0.044±0.002 log10 cells h⁻¹ and concomitant oxygen drawdown (0.16±0.05 µmol L⁻¹ h⁻¹ dm⁻². Our results demonstrate that benthic reef algae can release a significant fraction of their photosynthetically-fixed carbon as DOC, these release rates vary by species, and this DOC is available to and consumed by reef associated microbes. These data provide compelling evidence that benthic primary producers differentially influence

  9. Assess the environmental health status of macrophyte ecosystems using an oxidative stress biomarker. Case studies: The Gulf of Aqaba and the Lagoon of Venice

    Science.gov (United States)

    Wahsha, Mohammad; Juhmani, Abdul-Salam; Buosi, Alessandro; Sfriso, Andrea; Sfriso, Adriano

    2017-04-01

    Macrophytes play a fundamental role in structuring communities in aquatic environments. They contribute to maintaining the ecosystem services. Unfortunately, nowadays, they are threatened by different sources of pollution. The release of such potentially toxic elements (PTEs) to the environment may influence negatively the ecosystem health, which often limits and sometimes disqualifies the ecosystem biodiversity. Indeed, the increasing concentration and distribution of PTEs in the marine ecosystem by mismanagement of industrial activities, overuse of agrochemicals, and waste disposal are causing worldwide concern. The aim of this work is to describe the developing of an innovative early warning tool, based on the implementation of the lipid peroxidation oxidative stress biomarker for the assessment and monitoring of ecological status in response to PTEs in different marine environments. Six sites were selected along the Jordanian coastline of the Gulf of Aqaba and the lagoon of Venice in Italy according to different morpho