WorldWideScience

Sample records for underlies major freshwater

  1. Freshwater Megafauna: Flagships for Freshwater Biodiversity under Threat.

    Science.gov (United States)

    Carrizo, Savrina F; Jähnig, Sonja C; Bremerich, Vanessa; Freyhof, Jörg; Harrison, Ian; He, Fengzhi; Langhans, Simone D; Tockner, Klement; Zarfl, Christiane; Darwall, William

    2017-10-01

    Freshwater biodiversity is highly threatened and is decreasing more rapidly than its terrestrial or marine counterparts; however, freshwaters receive less attention and conservation investment than other ecosystems do. The diverse group of freshwater megafauna, including iconic species such as sturgeons, river dolphins, and turtles, could, if promoted, provide a valuable tool to raise awareness and funding for conservation. We found that freshwater megafauna inhabit every continent except Antarctica, with South America, Central Africa, and South and Southeast Asia being particularly species rich. Freshwater megafauna co-occur with up to 93% of mapped overall freshwater biodiversity. Fifty-eight percent of the 132 megafauna species included in the study are threatened, with 84% of their collective range falling outside of protected areas. Of all threatened freshwater species, 83% are found within the megafauna range, revealing the megafauna's capacity as flagship and umbrella species for fostering freshwater conservation.

  2. Identification of major planktonic sulfur oxidizers in stratified freshwater lake.

    Directory of Open Access Journals (Sweden)

    Hisaya Kojima

    Full Text Available Planktonic sulfur oxidizers are important constituents of ecosystems in stratified water bodies, and contribute to sulfide detoxification. In contrast to marine environments, taxonomic identities of major planktonic sulfur oxidizers in freshwater lakes still remain largely unknown. Bacterioplankton community structure was analyzed in a stratified freshwater lake, Lake Mizugaki in Japan. In the clone libraries of 16S rRNA gene, clones very closely related to a sulfur oxidizer isolated from this lake, Sulfuritalea hydrogenivorans, were detected in deep anoxic water, and occupied up to 12.5% in each library of different water depth. Assemblages of planktonic sulfur oxidizers were specifically analyzed by constructing clone libraries of genes involved in sulfur oxidation, aprA, dsrA, soxB and sqr. In the libraries, clones related to betaproteobacteria were detected with high frequencies, including the close relatives of Sulfuritalea hydrogenivorans.

  3. Toxicity of Metals to a Freshwater Ostracod: Stenocypris major

    Directory of Open Access Journals (Sweden)

    Mohammad Shuhaimi-Othman

    2011-01-01

    Full Text Available Adults of freshwater ostracod Stenocypris major (Crustacea, Candonidae were exposed for a four-day period in laboratory conditions to a range of copper (Cu, cadmium (Cd, zinc (Zn, lead (Pb, nickel (Ni, iron (Fe, aluminium (Al, and manganese (Mn concentrations. Mortality was assessed, and median lethal times (LT50 and concentrations (LC50 were calculated. LT50 and LC50 increased with the decrease in mean exposure concentrations and times, respectively, for all metals. LC50s for 96 hours for Cu, Cd, Zn, Pb, Ni, Fe, Al, and Mn were 25.2, 13.1, 1189.8, 526.2, 19743.7, 278.9, 3101.9, and 510.2 μg/L, respectively. Metals bioconcentration in S. major increases with exposure to increasing concentrations, and Cd was the most toxic to S. major, followed by Cu, Fe, Mn, Pb, Zn, Al, and Ni (Cd>Cu>Fe>Mn>Pb>Zn>Al>Ni. Comparison of LC50 values for metals for this species with those for other freshwater crustacean reveals that S. major is equally or more sensitive to metals than most other tested crustacean.

  4. 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, ...

  5. Mapping potential freshwater services, and their representation within Protected Areas (PAs, under conditions of sparse data. Pilot implementation for Cambodia

    Directory of Open Access Journals (Sweden)

    Leonardo Sáenz

    2016-07-01

    Full Text Available Freshwater is arguably one of Earth’s most threatened natural resources, on which more than 7 billion people depend. Pressures on freshwater resources from infrastructure, resource development, agricultural pollution and deforestation are mounting, particularly in developing countries. To date, conservation responses such as Protected Areas (PAs have not typically targeted freshwater ecosystems and their services, and thus little is known about the effectiveness of these efforts in protecting them. This paper proposes and pilots an innovative freshwater services metrics framework to quantify the representation of potential freshwater services in PAs under conditions of scarce data, with a pilot application for Cambodia. Our results indicate that conservation actions have more effectively represented potential freshwater regulation services than potential freshwater provisioning services, with major rivers remaining generally unprotected. Results from the framework are then used to propose a series of context and region specific management options to improve the conservation of freshwater services in Cambodia. There is an acute need for such management options, as the country’s food security depends largely on important freshwater ecosystems such as the Tonle Sap Lake and the deep water pools systems of the Mekong River. The framework proposed can be applied in other countries or large river basins to explore the degree of representation of freshwater services within PAs systems, under conditions of sparse data.

  6. Evolutionary refugia and ecological refuges: key concepts for conserving Australian arid zone freshwater biodiversity under climate change

    OpenAIRE

    Davis, Jenny; Pavlova, Alexandra; Thompson, Ross; Sunnucks, Paul

    2013-01-01

    Refugia have been suggested as priority sites for conservation under climate change because of their ability to facilitate survival of biota under adverse conditions. Here, we review the likely role of refugial habitats in conserving freshwater biota in arid Australian aquatic systems where the major long-term climatic influence has been aridification. We introduce a conceptual model that characterizes evolutionary refugia and ecological refuges based on our review of the attributes of aquati...

  7. The Prototypical Majority Effect Under Social Influence.

    Science.gov (United States)

    Koriat, Asher; Adiv-Mashinsky, Shiri; Undorf, Monika; Schwarz, Norbert

    2018-05-01

    Majority views are reported with greater confidence and fluency than minority views, with the difference increasing with majority size. This Prototypical Majority Effect (PME) was attributed generally to conformity pressure, but Koriat et al. showed that it can arise from the processes underlying decision and confidence independent of social influence. Here we examined the PME under conditions that differ in social influence. In Experiment 1, a robust PME emerged in the absence of information about the majority views, but the provision sof that information increased the choice of the majority view and magnified the PME. In Experiment 2, a PME emerged in a minority-biased condition that misled participants to believe that the majority view was the minority view, but the PME was stronger in a majority-biased condition. The results were discussed in terms of a dual-process view: The PME observed under social influence may contain externally driven and internally driven components.

  8. Graphite Based Electrode for ECG Monitoring: Evaluation under Freshwater and Saltwater Conditions

    Directory of Open Access Journals (Sweden)

    Tharoeun Thap

    2016-04-01

    Full Text Available We proposed new electrodes that are applicable for electrocardiogram (ECG monitoring under freshwater- and saltwater-immersion conditions. Our proposed electrodes are made of graphite pencil lead (GPL, a general-purpose writing pencil. We have fabricated two types of electrode: a pencil lead solid type (PLS electrode and a pencil lead powder type (PLP electrode. In order to assess the qualities of the PLS and PLP electrodes, we compared their performance with that of a commercial Ag/AgCl electrode, under a total of seven different conditions: dry, freshwater immersion with/without movement, post-freshwater wet condition, saltwater immersion with/without movement, and post-saltwater wet condition. In both dry and post-freshwater wet conditions, all ECG-recorded PQRST waves were clearly discernible, with all types of electrodes, Ag/AgCl, PLS, and PLP. On the other hand, under the freshwater- and saltwater-immersion conditions with/without movement, as well as post-saltwater wet conditions, we found that the proposed PLS and PLP electrodes provided better ECG waveform quality, with significant statistical differences compared with the quality provided by Ag/AgCl electrodes.

  9. First freshwater coralline alga and the role of local features in a major biome transition.

    Science.gov (United States)

    Žuljević, A; Kaleb, S; Peña, V; Despalatović, M; Cvitković, I; De Clerck, O; Le Gall, L; Falace, A; Vita, F; Braga, Juan C; Antolić, B

    2016-01-21

    Coralline red algae are significant components of sea bottom and up to now considered as exclusively marine species. Here we present the first coralline alga from a freshwater environment, found in the Cetina River (Adriatic Sea watershed). The alga is fully adapted to freshwater, as attested by reproductive structures, sporelings, and an inability to survive brackish conditions. Morphological and molecular phylogenetic analyses reveal the species belongs to Pneophyllum and is described as P. cetinaensis sp. nov. The marine-freshwater transition most probably occurred during the last glaciation. The brackish-water ancestor was preadapted to osmotic stress and rapid changes in water salinity and temperature. The particular characteristics of the karst Cetina River, such as hard water enriched with dissolved calcium carbonate and a pH similar to the marine environment, favoured colonization of the river by a marine species. The upstream advance and dispersal is facilitated by exceptionally pronounced zoochory by freshwater gastropods. Pneophyllum cetinaensis defies the paradigm of Corallinales as an exclusively marine group.

  10. BROOKHAVEN: Major detectors for RHIC under construction

    International Nuclear Information System (INIS)

    Ludlam, Thomas W.

    1994-01-01

    On March 9-10, a cost and schedule review at Brookhaven verified construction readiness for the PHENIX detector (May 1993, page 10). PHENIX thus joins STAR (Solenoidal Tracking at RHIC - November 1991, page 17), whose construction plan was ratified in January 1993, as a major detector to take data when the RHIC heavy ion collider is completed in mid-1999. The goal of both detectors is to search for the transition from ordinary nuclear matter to a new state of matter consisting of (momentarily) unconfined quarks and gluons. This transition to a ''quark-gluon plasma'' (QGP) is predicted to occur under extreme conditions of temperature and energy density, as is likely to be the case in the collision of heavy ions of sufficient energy. RHIC is expected to produce the highest energy densities ever observed on the nuclear scale

  11. Evolutionary refugia and ecological refuges: key concepts for conserving Australian arid zone freshwater biodiversity under climate change

    Science.gov (United States)

    Davis, Jenny; Pavlova, Alexandra; Thompson, Ross; Sunnucks, Paul

    2013-01-01

    Refugia have been suggested as priority sites for conservation under climate change because of their ability to facilitate survival of biota under adverse conditions. Here, we review the likely role of refugial habitats in conserving freshwater biota in arid Australian aquatic systems where the major long-term climatic influence has been aridification. We introduce a conceptual model that characterizes evolutionary refugia and ecological refuges based on our review of the attributes of aquatic habitats and freshwater taxa (fishes and aquatic invertebrates) in arid Australia. We also identify methods of recognizing likely future refugia and approaches to assessing the vulnerability of arid-adapted freshwater biota to a warming and drying climate. Evolutionary refugia in arid areas are characterized as permanent, groundwater-dependent habitats (subterranean aquifers and springs) supporting vicariant relicts and short-range endemics. Ecological refuges can vary across space and time, depending on the dispersal abilities of aquatic taxa and the geographical proximity and hydrological connectivity of aquatic habitats. The most important are the perennial waterbodies (both groundwater and surface water fed) that support obligate aquatic organisms. These species will persist where suitable habitats are available and dispersal pathways are maintained. For very mobile species (invertebrates with an aerial dispersal phase) evolutionary refugia may also act as ecological refuges. Evolutionary refugia are likely future refugia because their water source (groundwater) is decoupled from local precipitation. However, their biota is extremely vulnerable to changes in local conditions because population extinction risks cannot be abated by the dispersal of individuals from other sites. Conservation planning must incorporate a high level of protection for aquifers that support refugial sites. Ecological refuges are vulnerable to changes in regional climate because they have little

  12. Seasonal dynamics of 60Co uptake by freshwater algae under natural conditions

    International Nuclear Information System (INIS)

    Koulikov, N.V.; Trapeznikov, A.V.

    1988-08-01

    The data presented in the present report show that the values of 60 Co uptake coefficient in freshwater algae under naturel conditions can change 5-6 times depending on seasons, reaching maximum values in summer. Specific activity of the radionuclide in water can be essentially changed depending on the nuclear power plant operation mode. In such a nonequilibrium system it is rather questionable to use the uptake coefficient as a constant parameter for the determination of the radionuclide specific activity in water [fr

  13. A freshwater biodiversity hotspot under pressure - assessing threats and identifying conservation needs for ancient Lake Ohrid

    Science.gov (United States)

    Kostoski, G.; Albrecht, C.; Trajanovski, S.; Wilke, T.

    2010-12-01

    Immediate conservation measures for world-wide freshwater resources are of eminent importance. This is particularly true for so-called ancient lakes. While these lakes are famous for being evolutionary theatres, often displaying an extraordinarily high degree of biodiversity and endemism, in many cases these biota are also experiencing extreme anthropogenic impact. Lake Ohrid, a major European biodiversity hotspot situated in a trans-frontier setting on the Balkans, is a prime example for a lake with a magnitude of narrow range endemic taxa that are under increasing anthropogenic pressure. Unfortunately, evidence for a "creeping biodiversity crisis" has accumulated over the last decades, and major socio-political changes have gone along with human-mediated environmental changes. Based on field surveys, monitoring data, published records, and expert interviews, we aimed to (1) assess threats to Lake Ohrids' (endemic) biodiversity, (2) summarize existing conservation activities and strategies, and (3) outline future conservation needs for Lake Ohrid. We compiled threats to both specific taxa (and in cases to particular species) as well as to the lake ecosystems itself. Major conservation concerns identified for Lake Ohrid are: (1) watershed impacts, (2) agriculture and forestry, (3) tourism and population growth, (4) non-indigenous species, (5) habitat alteration or loss, (6) unsustainable exploitation of fisheries, and (7) global climate change. Among the major (well-known) threats with high impact are nutrient input (particularly of phosphorus), habitat conversion and silt load. Other threats are potentially of high impact but less well known. Such threats include pollution with hazardous substances (from sources such as mines, former industries, agriculture) or climate change. We review and discuss institutional responsibilities, environmental monitoring and ecosystem management, existing parks and reserves, biodiversity and species measures, international

  14. Field studies of estuarine turbidity under different freshwater flow conditions, Kaipara River, New Zealand

    Science.gov (United States)

    Mitchell, Steven B.; Green, Malcolm O.; MacDonald, Iain T.; Pritchard, Mark

    2017-11-01

    We present a first interpretation of three days of measurements made in 2013 from the tidal reaches of the Kaipara River (New Zealand) under both low and high freshwater inputs and a neap tidal cycle. During the first day, we occupied two stations that were approximately 6 km apart in a tidal reach that runs for 25 km from the river mouth to the upstream limit of tidal influence. During the second day, longitudinal surveys were conducted over a distance of 6 km centred on the upstream station. The data reveal a turbidity maximum in the form of a high-concentration 'plug' of suspended mud that was advected downstream on the ebbing tide past the upper (HB) measurement station and which exchanged sediment with the seabed by settling at low slack water and by resuspension in the early flooding tide. The data suggest that fine sediment is transported landwards and trapped in the upper part of the tidal reach under these low-flow conditions. On the third day of measurements we repeated the experiments of the first day but later in the year, for a much higher freshwater flow. This interpretation of our data set highlights the potential contribution of a range of processes to the generation of the observed suspended-sediment signals, including resuspension of local bed sediment, advection by the tidal current, settling of suspended sediment over a long timescale compared to the advection timescale, advection of longitudinal gradients in suspended sediment, and suppression of vertical mixing by density stratification of the water column. The level of temporal and spatial detail afforded by these measurements allows a much clearer understanding of the timing and importance of vertical stratification on the transport of suspended particulate matter than is generally possible using fixed-point sensors.

  15. Evolutionary history of Otophysi (Teleostei, a major clade of the modern freshwater fishes: Pangaean origin and Mesozoic radiation

    Directory of Open Access Journals (Sweden)

    Saitoh Kenji

    2011-06-01

    Full Text Available Abstract Background Freshwater harbors approximately 12,000 fish species accounting for 43% of the diversity of all modern fish. A single ancestral lineage evolved into about two-thirds of this enormous biodiversity (≈ 7900 spp. and is currently distributed throughout the world's continents except Antarctica. Despite such remarkable species diversity and ubiquity, the evolutionary history of this major freshwater fish clade, Otophysi, remains largely unexplored. To gain insight into the history of otophysan diversification, we constructed a timetree based on whole mitogenome sequences across 110 species representing 55 of the 64 families. Results Partitioned maximum likelihood analysis based on unambiguously aligned sequences (9923 bp confidently recovered the monophyly of Otophysi and the two constituent subgroups (Cypriniformes and Characiphysi. The latter clade comprised three orders (Gymnotiformes, Characiformes, Siluriformes, and Gymnotiformes was sister to the latter two groups. One of the two suborders in Characiformes (Characoidei was more closely related to Siluriformes than to its own suborder (Citharinoidei, rendering the characiforms paraphyletic. Although this novel relationship did not receive strong statistical support, it was supported by analyzing independent nuclear markers. A relaxed molecular clock Bayesian analysis of the divergence times and reconstruction of ancestral habitats on the timetree suggest a Pangaean origin and Mesozoic radiation of otophysans. Conclusions The present timetree demonstrates that survival of the ancestral lineages through the two consecutive mass extinctions on Pangaea, and subsequent radiations during the Jurassic through early Cretaceous shaped the modern familial diversity of otophysans. This evolutionary scenario is consistent with recent arguments based on biogeographic inferences and molecular divergence time estimates. No fossil otophysan, however, has been recorded before the Albian, the

  16. Evolutionary history of Otophysi (Teleostei), a major clade of the modern freshwater fishes: Pangaean origin and Mesozoic radiation.

    Science.gov (United States)

    Nakatani, Masanori; Miya, Masaki; Mabuchi, Kohji; Saitoh, Kenji; Nishida, Mutsumi

    2011-06-22

    Freshwater harbors approximately 12,000 fish species accounting for 43% of the diversity of all modern fish. A single ancestral lineage evolved into about two-thirds of this enormous biodiversity (≈ 7900 spp.) and is currently distributed throughout the world's continents except Antarctica. Despite such remarkable species diversity and ubiquity, the evolutionary history of this major freshwater fish clade, Otophysi, remains largely unexplored. To gain insight into the history of otophysan diversification, we constructed a timetree based on whole mitogenome sequences across 110 species representing 55 of the 64 families. Partitioned maximum likelihood analysis based on unambiguously aligned sequences (9923 bp) confidently recovered the monophyly of Otophysi and the two constituent subgroups (Cypriniformes and Characiphysi). The latter clade comprised three orders (Gymnotiformes, Characiformes, Siluriformes), and Gymnotiformes was sister to the latter two groups. One of the two suborders in Characiformes (Characoidei) was more closely related to Siluriformes than to its own suborder (Citharinoidei), rendering the characiforms paraphyletic. Although this novel relationship did not receive strong statistical support, it was supported by analyzing independent nuclear markers. A relaxed molecular clock Bayesian analysis of the divergence times and reconstruction of ancestral habitats on the timetree suggest a Pangaean origin and Mesozoic radiation of otophysans. The present timetree demonstrates that survival of the ancestral lineages through the two consecutive mass extinctions on Pangaea, and subsequent radiations during the Jurassic through early Cretaceous shaped the modern familial diversity of otophysans. This evolutionary scenario is consistent with recent arguments based on biogeographic inferences and molecular divergence time estimates. No fossil otophysan, however, has been recorded before the Albian, the early Cretaceous 100-112 Ma, creating an over 100

  17. Adaptive genomic divergence under high gene flow between freshwater and brackish-water ecotypes of prickly sculpin (Cottus asper) revealed by Pool-Seq.

    Science.gov (United States)

    Dennenmoser, Stefan; Vamosi, Steven M; Nolte, Arne W; Rogers, Sean M

    2017-01-01

    Understanding the genomic basis of adaptive divergence in the presence of gene flow remains a major challenge in evolutionary biology. In prickly sculpin (Cottus asper), an abundant euryhaline fish in northwestern North America, high genetic connectivity among brackish-water (estuarine) and freshwater (tributary) habitats of coastal rivers does not preclude the build-up of neutral genetic differentiation and emergence of different life history strategies. Because these two habitats present different osmotic niches, we predicted high genetic differentiation at known teleost candidate genes underlying salinity tolerance and osmoregulation. We applied whole-genome sequencing of pooled DNA samples (Pool-Seq) to explore adaptive divergence between two estuarine and two tributary habitats. Paired-end sequence reads were mapped against genomic contigs of European Cottus, and the gene content of candidate regions was explored based on comparisons with the threespine stickleback genome. Genes showing signals of repeated differentiation among brackish-water and freshwater habitats included functions such as ion transport and structural permeability in freshwater gills, which suggests that local adaptation to different osmotic niches might contribute to genomic divergence among habitats. Overall, the presence of both repeated and unique signatures of differentiation across many loci scattered throughout the genome is consistent with polygenic adaptation from standing genetic variation and locally variable selection pressures in the early stages of life history divergence. © 2016 John Wiley & Sons Ltd.

  18. When trends intersect: The challenge of protecting freshwater ecosystems under multiple land use and hydrological intensification scenarios.

    Science.gov (United States)

    Davis, Jenny; O'Grady, Anthony P; Dale, Allan; Arthington, Angela H; Gell, Peter A; Driver, Patrick D; Bond, Nick; Casanova, Michelle; Finlayson, Max; Watts, Robyn J; Capon, Samantha J; Nagelkerken, Ivan; Tingley, Reid; Fry, Brian; Page, Timothy J; Specht, Alison

    2015-11-15

    Intensification of the use of natural resources is a world-wide trend driven by the increasing demand for water, food, fibre, minerals and energy. These demands are the result of a rising world population, increasing wealth and greater global focus on economic growth. Land use intensification, together with climate change, is also driving intensification of the global hydrological cycle. Both processes will have major socio-economic and ecological implications for global water availability. In this paper we focus on the implications of land use intensification for the conservation and management of freshwater ecosystems using Australia as an example. We consider this in the light of intensification of the hydrologic cycle due to climate change, and associated hydrological scenarios that include the occurrence of more intense hydrological events (extreme storms, larger floods and longer droughts). We highlight the importance of managing water quality, the value of providing environmental flows within a watershed framework and the critical role that innovative science and adaptive management must play in developing proactive and robust responses to intensification. We also suggest research priorities to support improved systemic governance, including adaptation planning and management to maximise freshwater biodiversity outcomes while supporting the socio-economic objectives driving land use intensification. Further research priorities include: i) determining the relative contributions of surface water and groundwater in supporting freshwater ecosystems; ii) identifying and protecting freshwater biodiversity hotspots and refugia; iii) improving our capacity to model hydro-ecological relationships and predict ecological outcomes from land use intensification and climate change; iv) developing an understanding of long term ecosystem behaviour; and v) exploring systemic approaches to enhancing governance systems, including planning and management systems affecting

  19. Comparison of upconing under vertical and horizontal wells in freshwater lenses: sand-box experiments and numerical modeling

    Science.gov (United States)

    Stoeckl, Leonard; Stefan, Loeffler; Houben, Georg

    2013-04-01

    Freshwater lenses on islands and in inland areas are often the primary freshwater resource there. The fragile equilibrium between saline and fresh groundwater can be disrupted by excessive pumping, leading to an upward migration of the saline water underneath the well. Sand-box experiments were conducted to compare the upconing at vertical and horizontal wells pumping from a freshwater lens. Results were then compared to numerical simulations. To simulate the cross-section of an "infinite strip island", an acrylic box with a spacing of 5 cm was filled with coarse sand. After saturating the model with degassed saltwater from bottom to top, freshwater recharge was applied from above. By coloring the infiltrating freshwater with different tracer colors using uranine and indigotine we were able to visualize flow paths during pumping. A horizontal and a vertical well were placed at the left and right side of the symmetric island. Both had equal diameter, screen length, depth of placement, and distance to shore. Three increasing pumping rates were applied to each well successively and the electrical conductivity of the abstracted water was continuously measured using a through-flow cell. Results show that no saltwater entered the wells when pumping at the lowest rate. Still, slight saltwater upconing and a shift of the freshwater divide in the island were observed. At the second rate a clear saltwater breakthrough into the vertical well occurred, while the electrical conductivity remained nearly unchanged in the horizontal well. Applying the third (highest) abstraction rate to each of the wells saltwater entered both wells, exceeding drinking water standards in the vertical well. The described behavior indicates the advantage of horizontal over vertical wells on islands and in coastal zones prone to saltwater up-coning. Numerical simulations show similar patterns, even though deviations exist between the second and the third pumping rate, which are under and

  20. Arsenic uptake, transformation, and release by three freshwater algae under conditions with and without growth stress.

    Science.gov (United States)

    Xie, Shaowen; Liu, Jinxin; Yang, Fen; Feng, Hanxiao; Wei, Chaoyang; Wu, Fengchang

    2018-05-04

    This study was carried out using indoor controlled experiments to study the arsenic (As) uptake, biotransformation, and release behaviors of freshwater algae under growth stress. Three freshwater algae, Microcystis aeruginosa, Anabaena flosaquae, and Chlorella sp., were chosen. Two types of inhibitors, e.g., Cu 2+ and isothiazolinone, were employed to inhibit the growth of the algae. The algae were cultivated to a logarithmic stage in growth media containing 0.1 mg/L P; then, 0.8 mg/L As in the form of arsenate (iAs V ) was added, while both inhibitors were simultaneously added at dosages of 0.1 and 0.3 mg/L, with no addition of inhibitors in the control. After 2 days of exposure, the average growth rate (μ 2d ) was measured to represent the growth rates of the algae cells; the extra- and intracellular As concentrations in various forms, i.e., arsenate, arsenite (iAs III ), monomethyl arsenic (MMA), and dimethyl arsenic (DMA), were also measured. Without inhibitors, the average growth rate followed the order of M. aeruginosa, Chlorella sp., and A. flosaquae, with the growth rate of M. aeruginosa significantly higher than that of the other two algae. However, when Cu 2+ was added as an external inhibitor, the order of the average growth rate for the three algae became partially reversed, suggesting differentiation of the algae in response to the inhibitor. This differentiation can be seen by the reduction in the average growth rate of M. aeruginosa, which was as high as 1730% at the 0.3-mg/L Cu 2+ dosage when compared with the control, while for the other two algae, much fewer changes were seen. The great reduction in M. aeruginosa growth rate was accompanied by increases in extracellular iAs V and iAs III and intracellular iAs V concentrations in the algae, indicating that As transformation is related to the growth of this algae. Much fewer or neglectable changes in growth were observed that were consistent with the few changes in the extra- and intracellular

  1. A freshwater biodiversity hotspot under pressure – assessing threats and identifying conservation needs for ancient Lake Ohrid

    Directory of Open Access Journals (Sweden)

    G. Kostoski

    2010-12-01

    Full Text Available Immediate conservation measures for world-wide freshwater resources are of eminent importance. This is particularly true for so-called ancient lakes. While these lakes are famous for being evolutionary theatres, often displaying an extraordinarily high degree of biodiversity and endemism, in many cases these biota are also experiencing extreme anthropogenic impact.

    Lake Ohrid, a major European biodiversity hotspot situated in a trans-frontier setting on the Balkans, is a prime example for a lake with a magnitude of narrow range endemic taxa that are under increasing anthropogenic pressure. Unfortunately, evidence for a "creeping biodiversity crisis" has accumulated over the last decades, and major socio-political changes have gone along with human-mediated environmental changes.

    Based on field surveys, monitoring data, published records, and expert interviews, we aimed to (1 assess threats to Lake Ohrids' (endemic biodiversity, (2 summarize existing conservation activities and strategies, and (3 outline future conservation needs for Lake Ohrid. We compiled threats to both specific taxa (and in cases to particular species as well as to the lake ecosystems itself. Major conservation concerns identified for Lake Ohrid are: (1 watershed impacts, (2 agriculture and forestry, (3 tourism and population growth, (4 non-indigenous species, (5 habitat alteration or loss, (6 unsustainable exploitation of fisheries, and (7 global climate change.

    Among the major (well-known threats with high impact are nutrient input (particularly of phosphorus, habitat conversion and silt load. Other threats are potentially of high impact but less well known. Such threats include pollution with hazardous substances (from sources such as mines, former industries, agriculture or climate change. We review and discuss institutional responsibilities, environmental monitoring and ecosystem management, existing parks and reserves, biodiversity and species

  2. Modeling tidal freshwater marsh sustainability in the Sacramento-San Joaquin Delta under a broad suite of potential future scenarios

    Science.gov (United States)

    Swanson, Kathleen M.; Drexler, Judith Z.; Fuller, Christopher C.; Schoellhamer, David H.

    2015-01-01

    In this paper, we report on the adaptation and application of a one-dimensional marsh surface elevation model, the Wetland Accretion Rate Model of Ecosystem Resilience (WARMER), to explore the conditions that lead to sustainable tidal freshwater marshes in the Sacramento–San Joaquin Delta. We defined marsh accretion parameters to encapsulate the range of observed values over historic and modern time-scales based on measurements from four marshes in high and low energy fluvial environments as well as possible future trends in sediment supply and mean sea level. A sensitivity analysis of 450 simulations was conducted encompassing a range of eScholarship provides open access, scholarly publishing services to the University of California and delivers a dynamic research platform to scholars worldwide. porosity values, initial elevations, organic and inorganic matter accumulation rates, and sea-level rise rates. For the range of inputs considered, the magnitude of SLR over the next century was the primary driver of marsh surface elevation change. Sediment supply was the secondary control. More than 84% of the scenarios resulted in sustainable marshes with 88 cm of SLR by 2100, but only 32% and 11% of the scenarios resulted in surviving marshes when SLR was increased to 133 cm and 179 cm, respectively. Marshes situated in high-energy zones were marginally more resilient than those in low-energy zones because of their higher inorganic sediment supply. Overall, the results from this modeling exercise suggest that marshes at the upstream reaches of the Delta—where SLR may be attenuated—and high energy marshes along major channels with high inorganic sediment accumulation rates will be more resilient to global SLR in excess of 88 cm over the next century than their downstream and low-energy counterparts. However, considerable uncertainties exist in the projected rates of sea-level rise and sediment avail-ability. In addition, more research is needed to constrain future

  3. Contrasting trends in distribution of four major planktonic betaproteobacterial groups along a pH gradient of epilimnia of 72 freshwater habitats.

    Science.gov (United States)

    Jezbera, Jan; Jezberová, Jitka; Koll, Ulrike; Horňák, Karel; Šimek, Karel; Hahn, Martin W

    2012-08-01

    The distribution and abundance of Betaproteobacteria and three of its genera - Limnohabitans (R-BT065 lineage), Polynucleobacter (including subclusters Polynucleobacter necessarius and Polynucleobacter acidiphobus/Polynucleobacter difficilis), and Methylophilus - across the epilimnia of 72 limnologically diverse freshwater habitats were investigated using fluorescence in situ hybridization. Moreover, seasonal development of Betaproteobacteria subgroups along the longitudinal axis of a reservoir was followed. Betaproteobacteria comprised on average 29.1%, Polynucleobacter 11.6%, P. necessarius 10.1%, P. acidiphobus/difficilis 0.5%, Limnohabitans 8.9%, and Methylophilus 0.9% of total bacterioplankton cells in the investigated habitats. Polynucleobacter necessarius and Limnohabitans coexisted in the majority of habitats but showed contrasting abundance patterns along the pH gradient of habitats (pH, 3.8-8.5). The observed distribution patterns could theoretically be explained by different preferences for substrate sources, that is, substances of humic origin in acidic waters and algal-derived substances in alkaline waters. However, substrate utilization patterns observed in laboratory experiments indicate no coherent group-specific differences in substrate preferences. Interestingly, similar distribution patterns were revealed for Limnohabitans and P. acidiphobus/difficilis, suggesting similar ecological adaptations of these distantly related taxa. Our findings further emphasize that at least two taxa of freshwater Betaproteobacteria represent ecologically diversified groups. Investigations at higher phylogenetic resolution are required for obtaining further insights into their ecology. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  4. Hydrogen production under salt stress conditions by a freshwater Rhodopseudomonas palustris strain.

    Science.gov (United States)

    Adessi, Alessandra; Concato, Margherita; Sanchini, Andrea; Rossi, Federico; De Philippis, Roberto

    2016-03-01

    Hydrogen represents a possible alternative energy carrier to face the growing request for energy and the shortage of fossil fuels. Photofermentation for the production of H2 constitutes a promising way for integrating the production of energy with waste treatments. Many wastes are characterized by high salinity, and polluted seawater can as well be considered as a substrate. Moreover, the application of seawater for bacterial culturing is considered cost-effective. The aims of this study were to assess the capability of the metabolically versatile freshwater Rhodopseudomonas palustris 42OL of producing hydrogen on salt-containing substrates and to investigate its salt stress response strategy, never described before. R. palustris 42OL was able to produce hydrogen in media containing up to 3 % added salt concentration and to grow in media containing up to 4.5 % salinity without the addition of exogenous osmoprotectants. While the hydrogen production performances in absence of sea salts were higher than in their presence, there was no significant difference in performances between 1 and 2 % of added sea salts. Nitrogenase expression levels indicated that the enzyme was not directly inhibited during salt stress, but a regulation of its expression may have occurred in response to salt concentration increase. During cell growth and hydrogen production in the presence of salts, trehalose was accumulated as a compatible solute; it protected the enzymatic functionality against salt stress, thus allowing hydrogen production. The possibility of producing hydrogen on salt-containing substrates widens the range of wastes that can be efficiently used in production processes.

  5. Turtles: Freshwater

    Science.gov (United States)

    Gibbons, J. Whitfield; Lovich, Jeffrey E.; Bowden, R.M.

    2017-01-01

    With their iconic shells, turtles are morphologically distinct in being the only extant or extinct vertebrate animals to have their shoulders and hips inside their rib cages. By the time an asteroid hit the earth 65.5 million years ago, causing the extinction of dinosaurs, turtles were already an ancient lineage that was 70% through their evolutionary history to date. The remarkable evolutionary success of turtles over 220 million years is due to a combination of both conservative and effective life history traits and an essentially unchanging morphology that withstood the test of time. However, the life history traits of many species make them particularly susceptible to overharvest and habitat destruction in the modern world, and a majority of the world’s species face serious conservation challenges with several extinctions documented in modern times. The global plight of turtles is underscored by the fact that the percentage of imperiled species exceeds that of even the critically endangered primates.Freshwater turtles, with over 260 recognized species, have become a focus on a worldwide scale for many conservation issues. This article is a synthesis of a diverse body of information on the general biology of freshwater turtles, with particular emphasis on the extensive research on ecology, life history, and behavior that has been accomplished in the last half century. Much of the research has been applicable to the aforementioned conservation challenges. The studies presented include a combination of laboratory and field experiments and observational studies on this intriguing group of animals.

  6. Exploring Freshwater Science

    Indian Academy of Sciences (India)

    Freshwater ecosystems and associated habitats harbor incrediblebiodiversity. They offer various ecosystem services andsustain human livelihoods. However, due to increasing developmentalpressure and rising water demand, these systemsare under huge threat. As a result, many aquatic species arefeared to become ...

  7. Projected freshwater withdrawals in the United States under a changing climate

    Science.gov (United States)

    Thomas C. Brown; Romano Foti; Jorge A. Ramirez

    2013-01-01

    Relying on the U.S. Geological Survey water use data for the period 1960 2005, this paper summarizes past water use and then projects future water use based on the trends in water use efficiency and major drivers of water use. Water use efficiency has improved in most sectors. Over the past 45 years, withdrawals in industry and at thermoelectric plants have steadily...

  8. Contemporary temperature-driven divergence in a Nordic freshwater fish under conditions commonly thought to hinder adaptation

    Directory of Open Access Journals (Sweden)

    Gregersen Finn

    2010-11-01

    Full Text Available Abstract Background Evaluating the limits of adaptation to temperature is important given the IPCC-predicted rise in global temperatures. The rate and scope of evolutionary adaptation can be limited by low genetic diversity, gene flow, and costs associated with adaptive change. Freshwater organisms are physically confined to lakes and rivers, and must therefore deal directly with climate variation and change. In this study, we take advantage of a system characterised by low genetic variation, small population size, gene flow and between-trait trade-offs to study how such conditions affect the ability of a freshwater fish to adapt to climate change. We test for genetically-based differences in developmental traits indicating local adaptation, by conducting a common-garden experiment using embryos and larvae from replicate pairs of sympatric grayling demes that spawn and develop in natural cold and warm water, respectively. These demes have common ancestors from a colonization event 22 generations ago. Consequently, we explore if diversification may occur under severely constraining conditions. Results We found evidence for divergence in ontogenetic rates. The divergence pattern followed adaptation predictions as cold-deme individuals displayed higher growth rates and yolk conversion efficiency than warm-deme individuals at the same temperature. The cold-deme embryos had a higher rate of muscle mass development. Most of the growth- and development differences occurred prior to hatch. The divergence was probably not caused by genetic drift as there was a strong degree of parallelism in the divergence pattern and because phenotypic differentiation (QST was larger than estimated genetic drift levels (microsatellite FST between demes from different temperature groups. We also document that these particular grayling populations cannot develop successfully at temperatures above 12°C, whereas other European populations can, and that increasing the

  9. Flow regime alterations under changing climate in two river basins: Implications for freshwater ecosystems

    Science.gov (United States)

    Gibson, C.A.; Meyer, J.L.; Poff, N.L.; Hay, L.E.; Georgakakos, A.

    2005-01-01

    We examined impacts of future climate scenarios on flow regimes and how predicted changes might affect river ecosystems. We examined two case studies: Cle Elum River, Washington, and Chattahoochee-Apalachicola River Basin, Georgia and Florida. These rivers had available downscaled global circulation model (GCM) data and allowed us to analyse the effects of future climate scenarios on rivers with (1) different hydrographs, (2) high future water demands, and (3) a river-floodplain system. We compared observed flow regimes to those predicted under future climate scenarios to describe the extent and type of changes predicted to occur. Daily stream flow under future climate scenarios was created by either statistically downscaling GCMs (Cle Elum) or creating a regression model between climatological parameters predicted from GCMs and stream flow (Chattahoochee-Apalachicola). Flow regimes were examined for changes from current conditions with respect to ecologically relevant features including the magnitude and timing of minimum and maximum flows. The Cle Elum's hydrograph under future climate scenarios showed a dramatic shift in the timing of peak flows and lower low flow of a longer duration. These changes could mean higher summer water temperatures, lower summer dissolved oxygen, and reduced survival of larval fishes. The Chattahoochee-Apalachicola basin is heavily impacted by dams and water withdrawals for human consumption; therefore, we made comparisons between pre-large dam conditions, current conditions, current conditions with future demand, and future climate scenarios with future demand to separate climate change effects and other anthropogenic impacts. Dam construction, future climate, and future demand decreased the flow variability of the river. In addition, minimum flows were lower under future climate scenarios. These changes could decrease the connectivity of the channel and the floodplain, decrease habitat availability, and potentially lower the ability

  10. Identification and Characterization of Differentially Expressed Transcripts in the Gills of Freshwater Prawn (Macrobrachium rosenbergii under Salt Stress

    Directory of Open Access Journals (Sweden)

    Hirak Kumar Barman

    2012-01-01

    Full Text Available The giant freshwater prawn, Macrobrachium rosenbergii, is an economically important species. It is a euryhaline shrimp, surviving in wide-range salinity conditions. A change in gene expression has been suggested as an important component for stress management. To better understand the osmoregulatory mechanisms mediated by the gill, a subtractive and suppressive hybridization (SSH tool was used to identify expressed transcripts linked to adaptations in saline water. A total of 117 transcripts represented potentially expressed under salinity conditions. BLAST analysis identified 22% as known genes, 9% as uncharacterized showing homologous to unannotated ESTs, and 69% as unknown sequences. All the identified known genes representing broad spectrum of biological pathways were particularly linked to stress tolerance including salinity tolerance. Expression analysis of 10 known genes and 7 unknown/uncharacterized genes suggested their upregulation in the gills of prawn exposed to saline water as compared to control indicating that these are likely to be associated with salinity acclimation. Rapid amplification of cDNA ends (RACE was used for obtaining full-length cDNA of MRSW-40 clone that was highly upregulated during salt exposure. The sequenced ESTs presented here will have potential implications for future understanding about salinity acclimation and/or tolerance of the prawn.

  11. Morphological and molecular features of some freshwater prawn species under genus Macrobrachium Spence Bate, 1868 (Crustacea: Decapoda: Palaemonidae) from Myanmar.

    Science.gov (United States)

    Mar, Win; Kang, Peng-Fei; Mao, Bin; Wang, Yu-Feng

    2018-02-28

    Myanmar is abundant in lakes and rivers, yet only a few investigations on the fauna of shrimps and prawns have been conducted and no molecular characteristics of prawn species have been described. This study reveals the morphologically identification of five freshwater prawn species under the genus Macrobrachium, including M. cavernicola, M. australiense, M. johnsoni, M. josephi and Macrobrachium sp.WMY-2017. As there was no previous record and information concerning with M. australiense, M. johnsoni, M. josephi and Macrobrachium sp. WMY-2017, they were regarded as the first record from Myanmar. A fragment of Mitochondrial Cytochrome Oxidase I Gene (COI) was amplified successfully from three studied species: M. australiense, M. josephi, and Macrobrachium sp.WMY-2017. The interspecific divergences of studied species varied from 0.01 to 0.15. The phylogenetic tree based on COI fragment sequences showed that M. australiense was closely related to M. rosenbergii, while Macrobrachium sp. WMY-2017 was closest to M. josephi. The results of molecular phylogeny has clarified the relationship within the genus Macrobrachium and represents the first step toward understanding the pattern of speciation base on molecular approach in Myanmar.

  12. Bioaccumulation of lead nitrate in freshwater crayfish (Astacus leptodactylus) tissues under aquaculture conditions.

    Science.gov (United States)

    Naghshbandi, N; Zare, S; Heidari, R; Soleimani Palcheglu, S

    2007-09-15

    The aim of this research was to evaluate the amount of lead in the tissue of Astacus leptodactylus especially in their muscle which the consumed part of their body. In this study the crayfish was exposed to intermediate concentration of lead nitrate (500 microg L(-1)) for periods up to 3 weeks. In the first, second and third weeks bioaccumulation in various tissues was under investigation. The data of toxicological analysis obtained by the method of atomic absorption revealed that the levels of bioaccumulation of metal are different in various tissues of this crayfish. The accumulation of the lead in gills was the highest and in muscles was lowest degree. The amount of heavy metals in the tissues of crayfish was as follow. Gills>exoskeleton>hepatopancreas (digestive glands)>digestive tract>green gland>testis and ovary>muscles.

  13. Effects of a larval mosquito biopesticide and Culex larvae on a freshwater nanophytoplankton (Selenastrum capricornatum) under axenic conditions.

    Science.gov (United States)

    Duguma, Dagne; Ortiz, Sara L; Lin, Youjian; Wilson, P Chris; Walton, William E

    2017-06-01

    The effects of microbial biopesticides used for mosquito control on autotrophic microorganisms such as nanophytoplankton are equivocal. We examined impacts of mosquito biopesticides and mosquito larvae on primary producers in two independent experiments. In the first experiment, we examined the effects of a commonly used microbial biopesticide formulation (VectoMax ® CG) on a unicellular microalga, Selenastrum capricornatum Printz, under axenic laboratory conditions. The biopesticide treatments included two concentrations (0.008 and 0.016 g liter -1 ) of VectoMax ® CG and two controls (one untreated and another with autoclaved 0.016 g VectoMax ® CG liter -1 ) in replicated axenic experimental microcosms. Spectrophotometric analysis of chlorophyll a (proxy for algal biomass) and direct enumeration of algal cells following the treatments revealed no significant effects of the microbial biopesticide on algal population growth during the four-week study. In the second experiment, we tested the effects of different densities of Culex larvae on the population of S. capricornatum. Effects of mosquito larvae feeding on S. capricornatum were significant with a curvilinear relationship between larval density and algal abundance in the water column. Together, these studies demonstrated a lack of direct cytological/toxicological effects of Bacillus-based microbial pesticides on freshwater primary production and support the hypothesis that the reduction in algal primary production previously reported when Bti products were applied to aquatic environments was likely independent of the Bacillus-based larvicidal toxins. Instead, it was likely mediated by microbial interactions in the water column and the trophic cascade effects that resulted from the removal of larval mosquitoes. These studies suggest that mosquito larvae independent of pesticide application can influence primary production. Our method of evaluating biopesticides against small photoautotrophs can be very useful

  14. Toxicological perspective on the osmoregulation and ionoregulation physiology of major ions by freshwater animals: Teleost fish, crustacea, aquatic insects, and Mollusca.

    Science.gov (United States)

    Griffith, Michael B

    2017-03-01

    Anthropogenic sources increase freshwater salinity and produce differences in constituent ions compared with natural waters. Moreover, ions differ in physiological roles and concentrations in intracellular and extracellular fluids. Four freshwater taxa groups are compared, to investigate similarities and differences in ion transport processes and what ion transport mechanisms suggest about the toxicity of these or other ions in freshwater. Although differences exist, many ion transporters are functionally similar and may belong to evolutionarily conserved protein families. For example, the Na + /H + -exchanger in teleost fish differs from the H + /2Na + (or Ca 2+ )-exchanger in crustaceans. In osmoregulation, Na + and Cl - predominate. Stenohaline freshwater animals hyperregulate until they are no longer able to maintain hypertonic extracellular Na + and Cl - concentrations with increasing salinity and become isotonic. Toxic effects of K + are related to ionoregulation and volume regulation. The ionic balance between intracellular and extracellular fluids is maintained by Na + /K + -adenosine triphosphatase (ATPase), but details are lacking on apical K + transporters. Elevated H + affects the maintenance of internal Na + by Na + /H + exchange; elevated HCO 3 - inhibits Cl - uptake. The uptake of Mg 2+ occurs by the gills or intestine, but details are lacking on Mg 2+ transporters. In unionid gills, SO 4 2- is actively transported, but most epithelia are generally impermeant to SO 4 2- . Transporters of Ca 2+ maintain homeostasis of dissolved Ca 2+ . More integration of physiology with toxicology is needed to fully understand freshwater ion effects. Environ Toxicol Chem 2017;36:576-600. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the

  15. TiO2 nanoparticles for the remediation of eutrophic shallow freshwater systems: Efficiency and impacts on aquatic biota under a microcosm experiment.

    Science.gov (United States)

    Bessa da Silva, Márcia; Abrantes, Nelson; Nogueira, Verónica; Gonçalves, Fernando; Pereira, Ruth

    2016-09-01

    The application of nanomaterials (NMs) in the remediation of eutrophic waters, particularly in the control of internal loading of nutrients, has been started, but limited investigations evaluated the effectiveness of these new treatment approaches and of their potential impacts on species from shallow freshwater lakes. The present work investigated, under a microcosm experiment, the application of a TiO2 nanomaterial both for reducing nutrient (mainly phosphorus and nitrogen forms) desorption and release from sediments (preventive treatment-PT) and for eliminating algal blooms (remediation treatment-RT). Furthermore, we also intended to assess the potential impacts of nano-TiO2 application on key freshwater species. The results showed the effectiveness of nano-TiO2 in controlling the release of phosphates from surface sediment and the subsequent reduction of total phosphorus in the water column. A reduction in total nitrogen was also observed. Such changes in nutrient dynamics contributed to a progressive inhibition of development of algae after the application of the NM in PT microcosms. Concerning the ability of nano-TiO2 to interact with algal cells, this interaction has likely occurred, mainly in RT, enhancing the formation of aggregates and their rapid settlement, thus reducing the algal bloom. Both treatments caused deleterious effects on freshwater species. In PT, Daphnia magna and Lemna minor showed a significant inhibition of several endpoints. Conversely, no inhibitory effect on the growth of Chironomus riparius was recorded. In opposite, C. riparius was the most affected species in RT microcosms. Such difference was probably caused by the formation of larger TiO2-algae aggregates in RT, under a high algal density, that rapidly settled in the sediment, becoming less available for pelagic species. In summary, despite the effectiveness of both treatments in controlling internal nutrient loading and in the mitigating algal bloom episodes, their negative

  16. Identity of major sulfur-cycle prokaryotes in freshwater lake ecosystems revealed by a comprehensive phylogenetic study of the dissimilatory adenylylsulfate reductase.

    Science.gov (United States)

    Watanabe, Tomohiro; Kojima, Hisaya; Fukui, Manabu

    2016-11-08

    Adenylylsulfate reductase is a heterodimeric complex of two subunits, AprB and AprA, and is a key enzyme in dissimilatory sulfate reduction and sulfur oxidation. Common use of aprA as a functional marker gene has revealed the diversity of sulfur-cycle prokaryotes in diverse environments. In this study, we established a comprehensive sequence set of apr genes and employed it to reanalyze apr phylogeny, evaluate the coverage of a widely used primer set (AprA-1-FW/AprA-5-RV), and categorize environmental aprA sequences. Phylogenetic tree construction revealed new members of Apr lineage II and several previously unrecognized lateral gene transfer events. Using the established phylogenetic tree, we classified all previously reported aprA sequences amplified from freshwater lakes with the primer pair AprA-1-FW/AprA-5-RV in addition to the aprA sequences newly retrieved from freshwater lakes; the obtained results were complemented by 16S rRNA clone library analysis. Apr-based classifications of some of operational taxonomic units were supported by 16S rRNA-based analysis. This study updates our knowledge on the phylogeny of aprBA and shows the identities of several sulfur-cycle bacteria, which could not be classified to a known taxa until now. The established apr sequence set is publicly available and can be applied to assign environmental sequences to known lineages.

  17. Toxicity of TiO2, in nanoparticle or bulk form to freshwater and marine microalgae under visible light and UV-A radiation.

    Science.gov (United States)

    Sendra, M; Moreno-Garrido, I; Yeste, M P; Gatica, J M; Blasco, J

    2017-08-01

    Use of titanium dioxide nanoparticles (TiO 2 NPs) has become a part of our daily life and the high environmental concentrations predicted to accumulate in aquatic ecosystems are cause for concern. Although TiO 2 has only limited reactivity, at the nanoscale level its physico-chemical properties and toxicity are different compared with bulk material. Phytoplankton is a key trophic level in fresh and marine ecosystems, and the toxicity provoked by these nanoparticles can affect the structure and functioning of ecosystems. Two microalgae species, one freshwater (Chlamydomonas reinhardtii) and the other marine (Phaeodactylum tricornutum), have been selected for testing the toxicity of TiO 2 in NP and conventional bulk form and, given its photo-catalytic properties, the effect of UV-A was also checked. Growth inhibition, quantum yield reduction, increase of intracellular ROS production, membrane cell damage and production of exo-polymeric substances (EPS) were selected as variables to measure. TiO 2 NPs and bulk TiO 2 show a relationship between the size of agglomerates and time in freshwater and saltwater, but not in ultrapure water. Under two treatments, UV-A (6 h per day) and no UV-A exposure, NPs triggered stronger cytotoxic responses than bulk material. TiO 2 NPs were also associated with greater production of reactive oxygen species and damage to membrane. However, microalgae exposed to TiO 2 NPs and bulk TiO 2 under UV-A were found to be more sensitive than in the visible light condition. The marine species (P. tricornutum) was more sensitive than the freshwater species, and higher Ti internalization was measured. Exopolymeric substances (EPS) were released from microalgae in the culture media, in the presence of TiO 2 in both forms. This may be a possible defense mechanism by these cells, which would enhance processes of homoagglomeration and settling, and thus reduce bioavailability. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Major Problems and Countermeasures of Foreign Trade in China under the Background of Expanding Domestic Demand

    OpenAIRE

    Ruan, Wei-tong; Li, Yu-hong

    2010-01-01

    Starting from China's macro-economic policy level and combining with the status of foreign trade in China, major problems in the development of foreign trade are analyzed under the background of expanding domestic demand, which is guided by the macro-economy, international finance, international trade and other related disciplines. Problems are mainly the inflation, the reduction of import, the trade protection, the increase in export costs, the reduction of export, the scale shrinkage of for...

  19. Field and model investigations of freshwater lenses in coastal aquifers

    NARCIS (Netherlands)

    Pauw, P.S.

    2015-01-01

    A major problem of sustaining freshwater supply from freshwater lens is the invasion of saline groundwater into a fresh groundwater body. In many coastal areas saltwater intrusion has led to well closure and reduced freshwater supply. Furthermore, in the future saltwater intrusion is expected to

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

    Science.gov (United States)

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

    2016-12-01

    Tidal Spartina-dominated saltmarshes and estuaries on the Southeast US coast are global hotspots of productivity. In coastal Georgia, tidal amplitudes and saltmarsh productivity are the highest along the Southeast US coast. Coastal Georgia is characterized by a humid subtropical seasonal climate, and inter-annual variability in precipitation, and freshwater discharge. The 2012-2013 timeframe encompassed contrasting levels of discharge for the Savannah River, a major Georgia river, with a 4.3-fold greater discharge in summer 2013 relative to summer 2012. In situ measurements of temperature, salinity, precipitation and Secchi depth, and water samples were collected weekly at high tide throughout 2012 and 2013 from the Skidaway River Estuary, a tidal saltmarsh-dominated estuary in coastal Georgia influenced by Savannah River hydrology. The effects of elevated discharge on the seasonal trends of water column components were evaluated. The shift from low discharge (2012) to high discharge (2013) led to decreased salinity in summer 2013, but no significant increases in inorganic nutrient (NH4, NOx, SiO2 and PO4) concentrations. Dissolved inorganic carbon (DIC) concentrations decreased, and DIC stable isotopic signatures (δ13C-DIC values) were depleted in summer 2013 relative to summer 2012. In 2013 dissolved organic carbon (DOC) concentrations, chromophoric and fluorescent dissolved organic matter (DOM: CDOM, FDOM) intensities, specific UV-absorbance (SUVA254) and relative humic-like fluorescence were all higher than in 2012, indicating that, as discharge increased in 2013, estuarine water became enriched in terrigenous DOM. Secchi depth and particulate organic carbon (POC) and nitrogen (PON) concentrations displayed clear seasonal patterns that were not significantly altered by discharge. However, δ13C-POC and δ15N-PON isotopic signatures indicated higher terrigenous contributions at elevated discharge. Discharge influenced cyanobacterial composition, but did not

  1. Essential concepts and underlying theories from physics, chemistry, and mathematics for "biochemistry and molecular biology" majors.

    Science.gov (United States)

    Wright, Ann; Provost, Joseph; Roecklein-Canfield, Jennifer A; Bell, Ellis

    2013-01-01

    Over the past two years, through an NSF RCN UBE grant, the ASBMB has held regional workshops for faculty members from around the country. The workshops have focused on developing lists of Core Principles or Foundational Concepts in Biochemistry and Molecular Biology, a list of foundational skills, and foundational concepts from Physics, Chemistry, and Mathematics that all Biochemistry or Molecular Biology majors must understand to complete their major coursework. The allied fields working group created a survey to validate foundational concepts from Physics, Chemistry, and Mathematics identified from participant feedback at various workshops. One-hundred twenty participants responded to the survey and 68% of the respondents answered yes to the question: "We have identified the following as the core concepts and underlying theories from Physics, Chemistry, and Mathematics that Biochemistry majors or Molecular Biology majors need to understand after they complete their major courses: 1) mechanical concepts from Physics, 2) energy and thermodynamic concepts from Physics, 3) critical concepts of structure from chemistry, 4) critical concepts of reactions from Chemistry, and 5) essential Mathematics. In your opinion, is the above list complete?" Respondents also delineated subcategories they felt should be included in these broad categories. From the results of the survey and this analysis the allied fields working group constructed a consensus list of allied fields concepts, which will help inform Biochemistry and Molecular Biology educators when considering the ASBMB recommended curriculum for Biochemistry or Molecular Biology majors and in the development of appropriate assessment tools to gauge student understanding of how these concepts relate to biochemistry and molecular biology. © 2013 by The International Union of Biochemistry and Molecular Biology.

  2. Methods for preparing synthetic freshwaters.

    Science.gov (United States)

    Smith, E J; Davison, W; Hamilton-Taylor, J

    2002-03-01

    Synthetic solutions that emulate the major ion compositions of natural waters are useful in experiments aimed at understanding biogeochemical processes. Standard recipes exist for preparing synthetic analogues of seawater, with its relatively constant composition, but, due to the diversity of freshwaters, a range of compositions and recipes is required. Generic protocols are developed for preparing synthetic freshwaters of any desired composition. The major problems encountered in preparing hard and soft waters include dissolving sparingly soluble calcium carbonate, ensuring that the ionic components of each concentrated stock solution cannot form an insoluble salt and dealing with the supersaturation of calcium carbonate in many hard waters. For acidic waters the poor solubility of aluminium salts requires attention. These problems are overcome by preparing concentrated stock solutions according to carefully designed reaction paths that were tested using a combination of experiment and equilibrium modeling. These stock solutions must then be added in a prescribed order to prepare a final solution that is brought into equilibrium with the atmosphere. The example calculations for preparing hard, soft and acidic freshwater surrogates with major ion compositions the same as published analyses, are presented in a generalized fashion that should allow preparation of any synthetic freshwater according to its known analysis.

  3. Exploring Freshwater Science

    Indian Academy of Sciences (India)

    and long term studies on mapping freshwater biodiversity1. 1. R J Ranjit Daniels ... The hierarchical nature of stream organization offers opportunity to ecologists to ask .... threats, freshwater systems are losing their aesthetic value (Fig- ure 4).

  4. Freshwater Fish Communities

    Science.gov (United States)

    Freshwater fish are ecologically important in stream ecosystems, and they provide people with significant food, recreation, and conservation value as biological indicator of freshwater streams. Historically, the streams and rivers of southern New England supported moderately dive...

  5. Quantitative Analysis of Major Phytochemicals in Orthodox tea (Camellia sinensis), Oxidized under Compressed Air Environment.

    Science.gov (United States)

    Panda, Brajesh Kumar; Datta, Ashis Kumar

    2016-04-01

    This study describes major changes in phytochemical composition of orthodox tea (Camellia sinensis var. Assamica) oxidized under compressed air (CA). The experiments for oxidation were conducted under air pressure (101, 202, and 303 kPa) for 150 min. Relative change in the concentrations of caffeine, catechins, theaflavins (TF), and thearubigins (TR) were analyzed. Effect of CA pressure was found to be nonsignificant in regulating caffeine concentration during oxidation. But degradation in different catechins as well as formation of different TF was significantly affected by CA pressure. At high CA pressure, TF showed highest peak value. TR was found to have slower rate of formation during initial phase of oxidation than TF. Even though the rate of TR formation was significantly influenced by CA, a portion of catechins remained unoxidized at end of oxidation. Except caffeine, the percent change in rate of formation or degradation were more prominent at 202 kPa. © 2016 Institute of Food Technologists®

  6. Tropical Freshwater Biology

    African Journals Online (AJOL)

    Tropical Freshwater Biology promotes the publication of scientific contributions in the field of freshwater biology in the tropical and subtropical regions of the world. One issue is published annually but this number may be increased. Original research papers and short communications on any aspect of tropical freshwater ...

  7. Halotolerant PGPRs Prevent Major Shifts in Indigenous Microbial Community Structure Under Salinity Stress.

    Science.gov (United States)

    Bharti, Nidhi; Barnawal, Deepti; Maji, Deepamala; Kalra, Alok

    2015-07-01

    The resilience of soil microbial populations and processes to environmental perturbation is of increasing interest as alteration in rhizosphere microbial community dynamics impacts the combined functions of plant-microbe interactions. The present study was conducted to investigate the effect of inoculation with halotolerant rhizobacteria Bacillus pumilus (STR2), Halomonas desiderata (STR8), and Exiguobacterium oxidotolerans (STR36) on the indigenous root-associated microbial (bacterial and fungal) communities in maize under non-saline and salinity stress. Plants inoculated with halotolerant rhizobacteria recorded improved growth as illustrated by significantly higher shoot and root dry weight and elongation in comparison to un-inoculated control plants under both non-saline and saline conditions. Additive main effect and multiplicative interaction ordination analysis revealed that plant growth promoting rhizobacteria (PGPR) inoculations as well as salinity are major drivers of microbial community shift in maize rhizosphere. Salinity negatively impacts microbial community as analysed through diversity indices; among the PGPR-inoculated plants, STR2-inoculated plants recorded higher values of diversity indices. As observed in the terminal-restriction fragment length polymorphism analysis, the inoculation of halotolerant rhizobacteria prevents major shift of the microbial community structure, thus enhancing the resilience capacity of the microbial communities.

  8. Is Supramolecular Filament Chirality the Underlying Cause of Major Morphology Differences in Amyloid Fibrils?

    Science.gov (United States)

    2015-01-01

    The unique enhanced sensitivity of vibrational circular dichroism (VCD) to the formation and development of amyloid fibrils in solution is extended to four additional fibril-forming proteins or peptides where it is shown that the sign of the fibril VCD pattern correlates with the sense of supramolecular filament chirality and, without exception, to the dominant fibril morphology as observed in AFM or SEM images. Previously for insulin, it has been demonstrated that the sign of the VCD band pattern from filament chirality can be controlled by adjusting the pH of the incubating solution, above pH 2 for “normal” left-hand-helical filaments and below pH 2 for “reversed” right-hand-helical filaments. From AFM or SEM images, left-helical filaments form multifilament braids of left-twisted fibrils while the right-helical filaments form parallel filament rows of fibrils with a flat tape-like morphology, the two major classes of fibril morphology that from deep UV resonance Raman scattering exhibit the same cross-β-core secondary structure. Here we investigate whether fibril supramolecular chirality is the underlying cause of the major morphology differences in all amyloid fibrils by showing that the morphology (twisted versus flat) of fibrils of lysozyme, apo-α-lactalbumin, HET-s (218–289) prion, and a short polypeptide fragment of transthyretin, TTR (105–115), directly correlates to their supramolecular chirality as revealed by VCD. The result is strong evidence that the chiral supramolecular organization of filaments is the principal underlying cause of the morphological heterogeneity of amyloid fibrils. Because fibril morphology is linked to cell toxicity, the chirality of amyloid aggregates should be explored in the widely used in vitro models of amyloid-associated diseases. PMID:24484302

  9. Is supramolecular filament chirality the underlying cause of major morphology differences in amyloid fibrils?

    Science.gov (United States)

    Kurouski, Dmitry; Lu, Xuefang; Popova, Ludmila; Wan, William; Shanmugasundaram, Maruda; Stubbs, Gerald; Dukor, Rina K; Lednev, Igor K; Nafie, Laurence A

    2014-02-12

    The unique enhanced sensitivity of vibrational circular dichroism (VCD) to the formation and development of amyloid fibrils in solution is extended to four additional fibril-forming proteins or peptides where it is shown that the sign of the fibril VCD pattern correlates with the sense of supramolecular filament chirality and, without exception, to the dominant fibril morphology as observed in AFM or SEM images. Previously for insulin, it has been demonstrated that the sign of the VCD band pattern from filament chirality can be controlled by adjusting the pH of the incubating solution, above pH 2 for "normal" left-hand-helical filaments and below pH 2 for "reversed" right-hand-helical filaments. From AFM or SEM images, left-helical filaments form multifilament braids of left-twisted fibrils while the right-helical filaments form parallel filament rows of fibrils with a flat tape-like morphology, the two major classes of fibril morphology that from deep UV resonance Raman scattering exhibit the same cross-β-core secondary structure. Here we investigate whether fibril supramolecular chirality is the underlying cause of the major morphology differences in all amyloid fibrils by showing that the morphology (twisted versus flat) of fibrils of lysozyme, apo-α-lactalbumin, HET-s (218-289) prion, and a short polypeptide fragment of transthyretin, TTR (105-115), directly correlates to their supramolecular chirality as revealed by VCD. The result is strong evidence that the chiral supramolecular organization of filaments is the principal underlying cause of the morphological heterogeneity of amyloid fibrils. Because fibril morphology is linked to cell toxicity, the chirality of amyloid aggregates should be explored in the widely used in vitro models of amyloid-associated diseases.

  10. Density and mobility effects of the majority carriers in organic semiconductors under light excitation

    Energy Technology Data Exchange (ETDEWEB)

    Vagenas, N.; Giannopoulou, A.; Kounavis, P., E-mail: pkounavis@upatras.gr [Department of Electrical and Computer Engineering, University of Patras, 26504 Patra (Greece)

    2015-01-21

    This study demonstrates that the effect of light excitation on the density and the mobility of the majority carriers can be explored in organic semiconductors by modulated photocurrent spectroscopy. The spectra of phase and amplitude of the modulated photocurrent of pentacene films indicate a significant increase in the density of the photogenerated mobile holes (majority carriers). This increase is accompanied by a comparatively much smaller increase of the steady state photocurrent response which can be reconciled with a decrease in the mobility (μ) of holes. The decrease of μ is supported from an unusual increase of the Y/μ ratio of the out-of-phase modulated photocurrent (Y) signal to the mobility under light excitation. It is proposed that the mobile holes, which are generated from the dissociation of the light-created excitons more likely near the pentacene-substrate interface by electron trapping, populate grain boundaries charging them and producing a downward band bending. As a result, potential energy barriers are build up which limit the transport of holes interacting through trapping-detrapping with deep partially occupied traps in the charged grain boundaries. On the other hand, the transport of holes interacting through trapping-detrapping with empty traps is found unaffected.

  11. Biokinetics of cadmium, selenium, and zinc in freshwater alga Scenedesmus obliquus under different phosphorus and nitrogen conditions and metal transfer to Daphnia magna

    International Nuclear Information System (INIS)

    Yu Riqing; Wang Wenxiong

    2004-01-01

    The uptake of Cd, Se(IV) and Zn by the freshwater alga Scenedesmus obliquus and the subsequent transfer and release budget in Daphnia magna were investigated under different nutrient additions and cell incubation conditions. An increase in ambient phosphate concentrations from 0.5 μmol l -1 to 50 μmol l -1 significantly increased the intracellular accumulation of Cd (by 18x) and Zn (by 5x), but decreased the accumulation of Se (by 126x) in the alga. The percentage of these metals distributing in the intracellular pool of algae also increased substantially with increasing ambient P concentrations. Nitrate addition from 5.0 to 200 μmol l -1 did not influence the uptake of any of the three metals, although a significant decrease in the intracellular Se distribution was observed. Radiolabeled algae under different nutrient manipulations (semi-continuous culture, starvation, and P-pulse treatments) were used to measure trophic transfer assimilation efficiency (AE) in Daphnia. When the algal cells were grown in a semi-continuous culture, starved for N and P, or were treated with P-pulse, the AEs of Cd and Zn were generally independent of the nutritional conditions, but the Se AE was significantly affected by different P levels. The efflux rate constants, determined during 10 d depuration following 7 days of dietary uptake, decreased significantly for Cd and Zn, but were relatively constant for Se with increasing P concentration. N-addition caused no effect on the metal efflux rate constants. P- or N-additions did not influence the release budget (including molting, neonates, excretion and feces) for all three elements in Daphnia. Our study indicated that phosphate enrichment may substantially increase metal uptake in green alga S. obliquus. Responses of trophic transfer in Daphnia to nutrient enrichment were metal specific. P-enrichment can possibly lead to considerable decrease on Se transfer from algae to zooplankton. - Phosphorous enrichment influences metal uptake

  12. Biokinetics of cadmium, selenium, and zinc in freshwater alga Scenedesmus obliquus under different phosphorus and nitrogen conditions and metal transfer to Daphnia magna

    Energy Technology Data Exchange (ETDEWEB)

    Yu Riqing; Wang Wenxiong

    2004-06-01

    The uptake of Cd, Se(IV) and Zn by the freshwater alga Scenedesmus obliquus and the subsequent transfer and release budget in Daphnia magna were investigated under different nutrient additions and cell incubation conditions. An increase in ambient phosphate concentrations from 0.5 {mu}mol l{sup -1} to 50 {mu}mol l{sup -1} significantly increased the intracellular accumulation of Cd (by 18x) and Zn (by 5x), but decreased the accumulation of Se (by 126x) in the alga. The percentage of these metals distributing in the intracellular pool of algae also increased substantially with increasing ambient P concentrations. Nitrate addition from 5.0 to 200 {mu}mol l{sup -1} did not influence the uptake of any of the three metals, although a significant decrease in the intracellular Se distribution was observed. Radiolabeled algae under different nutrient manipulations (semi-continuous culture, starvation, and P-pulse treatments) were used to measure trophic transfer assimilation efficiency (AE) in Daphnia. When the algal cells were grown in a semi-continuous culture, starved for N and P, or were treated with P-pulse, the AEs of Cd and Zn were generally independent of the nutritional conditions, but the Se AE was significantly affected by different P levels. The efflux rate constants, determined during 10 d depuration following 7 days of dietary uptake, decreased significantly for Cd and Zn, but were relatively constant for Se with increasing P concentration. N-addition caused no effect on the metal efflux rate constants. P- or N-additions did not influence the release budget (including molting, neonates, excretion and feces) for all three elements in Daphnia. Our study indicated that phosphate enrichment may substantially increase metal uptake in green alga S. obliquus. Responses of trophic transfer in Daphnia to nutrient enrichment were metal specific. P-enrichment can possibly lead to considerable decrease on Se transfer from algae to zooplankton. - Phosphorous enrichment

  13. Model Projections of Future Fluvial Sediment Delivery to Major Deltas Under Environmental Change

    Science.gov (United States)

    Darby, S. E.; Dunn, F.; Nicholls, R. J.; Cohen, S.; Zarfl, C.

    2017-12-01

    Deltas are important hot spots for climate change impacts on which over half a billion people live worldwide. Most of the world's deltas are sinking as a result of natural and anthropogenic subsidence and due to eustatic sea level rise. The ability to predict rates of delta aggradation is therefore critical to assessments of the extent to which sedimentation can potentially offset sea level rise, but our ability to make such predictions is severely hindered by a lack of insight into future trends of the fluvial sediment load supplied to their deltas by feeder watersheds. To address this gap we investigate fluvial sediment fluxes under future environmental change for a selection (47) of the world's major river deltas. Specifically, we employed the numerical model WBMsed to project future variations in mean annual fluvial sediment loads under a range of environmental change scenarios that account for changes in climate, socio-economics and dam construction. Our projections indicate a clear decrease (by 34 to 41% on average, depending on the specific scenario) in future fluvial sediment supply to most of the 47 deltas. These reductions in sediment delivery are driven primarily by anthropogenic disturbances, with reservoir construction being the most influential factor globally. Our results indicate the importance of developing new management strategies for reservoir construction and operation.

  14. Marine and freshwater toxins.

    Science.gov (United States)

    Hungerford, James M

    2006-01-01

    . (Abstracts from the Baiona 2005 meeting cited in this report can be found in the online version of the conference abstract book in the Files and Folders section of the Marine and Freshwater Toxins online community at www.aoac.org.) An active topic for discussion in Baiona and subsequent Task Force activities was the expert consultation for Codex which met in Oslo, Norway in 2004 (previously described and cited in last year's GR report, ref 1). The consultation group's executive summary report (http://www.fao.org/es/ESN/food/risk_biotoxin en.stm) describes suggested changes in action levels as well as methods, method validation, and other issues. September 2005 saw the AOAC Task Force efforts further supported by another symposium, "Marine and Freshwater Toxins: Quality Methods for Food Safety and International Trade," at the AOAC INTERNATIONAL Annual Conference in Orlando, Florida. The multidisciplinary talks at this full day symposium ranged from ciguatoxins to cyanobacterial toxins, and spanned toxicology, biochemistry, molecular biology and analytical chemistry. Again, the symposium preceded Task Force meetings. Toxin subgroups, including a new group on cyanobacterial toxins, met for engaging and productive subgroup discussions. All of these activities were preceded by a Wiley Award symposium for Task Force member Mike Quilliam of NRC Canada. These talks, presented at a half-day symposium on the first day of the Annual Meeting, focused on Quilliam's work with LC tandem mass spectrometry (LC/MS/MS) and certified reference standards and materials, and included related presentations by some of his many research collaborators. To maintain flow and continuity between symposia and between Task Force meetings, the group now uses new electronic discussion forums. Individual subgroup areas, under the Marine and Freshwater Toxins Task Force, comprise this online community. First introduced by AOAC INTERNATIONAL in early 2005, these new resources are being used to distribute

  15. Major transcriptome reprogramming underlies floral mimicry induced by the rust fungus Puccinia monoica in Boechera stricta.

    Directory of Open Access Journals (Sweden)

    Liliana M Cano

    Full Text Available Pucciniamonoica is a spectacular plant parasitic rust fungus that triggers the formation of flower-like structures (pseudoflowers in its Brassicaceae host plant Boecherastricta. Pseudoflowers mimic in shape, color, nectar and scent co-occurring and unrelated flowers such as buttercups. They act to attract insects thereby aiding spore dispersal and sexual reproduction of the rust fungus. Although much ecological research has been performed on P. monoica-induced pseudoflowers, this system has yet to be investigated at the molecular or genomic level. To date, the molecular alterations underlying the development of pseudoflowers and the genes involved have not been described. To address this, we performed gene expression profiling to reveal 256 plant biological processes that are significantly altered in pseudoflowers. Among these biological processes, plant genes involved in cell fate specification, regulation of transcription, reproduction, floral organ development, anthocyanin (major floral pigments and terpenoid biosynthesis (major floral volatile compounds were down-regulated in pseudoflowers. In contrast, plant genes involved in shoot, cotyledon and leaf development, carbohydrate transport, wax biosynthesis, cutin transport and L-phenylalanine metabolism (pathway that results in phenylethanol and phenylacetaldehyde volatile production were up-regulated. These findings point to an extensive reprogramming of host genes by the rust pathogen to induce floral mimicry. We also highlight 31 differentially regulated plant genes that are enriched in the biological processes mentioned above, and are potentially involved in the formation of pseudoflowers. This work illustrates the complex perturbations induced by rust pathogens in their host plants, and provides a starting point for understanding the molecular mechanisms of pathogen-induced floral mimicry.

  16. The community dynamics of major bioleaching microorganisms during chalcopyrite leaching under the effect of organics.

    Science.gov (United States)

    Li, Qihou; Tian, Ye; Fu, Xian; Yin, Huaqun; Zhou, Zhijun; Liang, Yiting; Qiu, Guanzhou; Liu, Jie; Liu, Hongwei; Liang, Yili; Shen, Li; Cong, Jing; Liu, Xueduan

    2011-08-01

    To determine the effect of organics (yeast extract) on microbial community during chalcopyrite bioleaching at different temperature, real-time polymerase chain reaction (PCR) was employed to analyze community dynamics of major bacteria applied in bioleaching. The results showed that yeast extract exerted great impact on microbial community, and therefore influencing bioleaching rate. To be specific, yeast extract was adverse to this bioleaching process at 30°C due to decreased proportion of important chemolithotrophs such as Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. However, yeast extract could promote bioleaching rate at 40°C on account of the increased number and enhanced work of Ferroplasma thermophilum, a kind of facultative bacteria. Similarly, bioleaching rate was enhanced under the effect of yeast extract at 50°C owing to the work of Acidianus brierleyi. At 60°C, bioleaching rate was close to 100% and temperature was the dominant factor determining bioleaching rate. Interestingly, the existence of yeast extract greatly enhanced the relative competitiveness of Ferroplasma thermophilum in this complex bioleaching microbial community.

  17. Indoleamine 2,3-dioxygenase and immune changes under antidepressive treatment in major depression in females.

    Science.gov (United States)

    Zoga, Margarita; Oulis, Panagiotis; Chatzipanagiotou, Stylianos; Masdrakis, Vasilios G; Pliatsika, Paraskevi; Boufidou, Fotini; Foteli, Stefania; Soldatos, Constantin R; Nikolaou, Chryssoula; Papageorgiou, Charalampos

    2014-01-01

    Indoleamine 2, 3-dioxygenase (IDO) induction has been suggested as a mechanism by which immune activation affects tryptophan metabolism and serotonin synthesis in major depressive disorder (MDD). We investigated IDO and changes in inflammatory mediators in patients with MDD undergoing effective treatment. Forty female patients with MDD and 40 controls were recruited. Serum IDO was assessed by enzyme-linked immunosorbent assay (ELISA). We also determined tumor necrosis factor-α (TNFα), interferon-γ (IFNγ), C-reactive protein (CRP) and serotonin concentrations. Patients' baseline concentrations of IDO and immune mediators were higher and serotonin concentrations were lower compared to controls. IDO and TNFα concentrations decreased under treatment and IDO changes were positively correlated with patient improvement. IFNγ and CRP concentrations remained unchanged. Serotonin concentration tended to increase. IDO might play an important role in the pathophysiology of MDD. Moreover, antidepressant therapy might reduce IDO production through an IFNγ-independent pathway. Finally, peripheral concentration of IDO assessed by ELISA might be a useful marker of MDD. Copyright © 2014 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  18. Increased pericarp cell length underlies a major quantitative trait locus for grain weight in hexaploid wheat.

    Science.gov (United States)

    Brinton, Jemima; Simmonds, James; Minter, Francesca; Leverington-Waite, Michelle; Snape, John; Uauy, Cristobal

    2017-08-01

    Crop yields must increase to address food insecurity. Grain weight, determined by grain length and width, is an important yield component, but our understanding of the underlying genes and mechanisms is limited. We used genetic mapping and near isogenic lines (NILs) to identify, validate and fine-map a major quantitative trait locus (QTL) on wheat chromosome 5A associated with grain weight. Detailed phenotypic characterisation of developing and mature grains from the NILs was performed. We identified a stable and robust QTL associated with a 6.9% increase in grain weight. The positive interval leads to 4.0% longer grains, with differences first visible 12 d after fertilization. This grain length effect was fine-mapped to a 4.3 cM interval. The locus also has a pleiotropic effect on grain width (1.5%) during late grain development that determines the relative magnitude of the grain weight increase. Positive NILs have increased maternal pericarp cell length, an effect which is independent of absolute grain length. These results provide direct genetic evidence that pericarp cell length affects final grain size and weight in polyploid wheat. We propose that combining genes that control distinct biological mechanisms, such as cell expansion and proliferation, will enhance crop yields. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  19. Using Marine and Freshwater Fish Environmental Intelligence Networks Under Different Climate Change Scenarios to Evaluate the Effectiveness of the Minamata Convention on Mercury

    Science.gov (United States)

    Bank, M. S.

    2017-12-01

    The Minamata Convention on Mercury was recently ratified and will go into effect on August 16, 2017. As noted in the convention text, fish are an important source of nutrition to consumers worldwide and several marine and freshwater species represent important links in the global source-receptor dynamics of methylmercury. However, despite its importance, a coordinated global program for marine and freshwater fish species using accredited laboratories, reproducible data and reliable models is still lacking. In recent years fish mercury science has evolved significantly with its use of advanced technologies and computational models to address this complex and ubiquitous environmental and public health issue. These advances in the field have made it essential that transparency be enhanced to ensure that fish mercury studies used in support of the convention are truly reproducible and scientifically sound. One primary goal of this presentation is to evaluate fish bioinformatics and methods, results and inferential reproducibility as it relates to aggregated uncertainty in mercury fish research models, science, and biomonitoring. I use models, environmental intelligence networks and simulations of the effects of a changing climate on methylmercury in marine and freshwater fish to examine how climate change and the convention itself may create further uncertainties for policymakers to consider. Lastly, I will also present an environmental intelligence framework for fish mercury bioaccumulation models and biomonitoring in support of the evaluation of the effectiveness of the Minamata Convention on Mercury.

  20. Dro1, a major QTL involved in deep rooting of rice under upland field conditions.

    Science.gov (United States)

    Uga, Yusaku; Okuno, Kazutoshi; Yano, Masahiro

    2011-05-01

    Developing a deep root system is an important strategy for avoiding drought stress in rice. Using the 'basket' method, the ratio of deep rooting (RDR; the proportion of total roots that elongated through the basket bottom) was calculated to evaluate deep rooting. A new major quantitative trait locus (QTL) controlling RDR was detected on chromosome 9 by using 117 recombinant inbred lines (RILs) derived from a cross between the lowland cultivar IR64, with shallow rooting, and the upland cultivar Kinandang Patong (KP), with deep rooting. This QTL explained 66.6% of the total phenotypic variance in RDR in the RILs. A BC(2)F(3) line homozygous for the KP allele of the QTL had an RDR of 40.4%, compared with 2.6% for the homozygous IR64 allele. Fine mapping of this QTL was undertaken using eight BC(2)F(3) recombinant lines. The RDR QTL Dro1 (Deeper rooting 1) was mapped between the markers RM24393 and RM7424, which delimit a 608.4 kb interval in the reference cultivar Nipponbare. To clarify the influence of Dro1 in an upland field, the root distribution in different soil layers was quantified by means of core sampling. A line homozygous for the KP allele of Dro1 (Dro1-KP) and IR64 did not differ in root dry weight in the shallow soil layers (0-25 cm), but root dry weight of Dro1-KP in deep soil layers (25-50 cm) was significantly greater than that of IR64, suggesting that Dro1 plays a crucial role in increased deep rooting under upland field conditions.

  1. Quantitative proteomics reveals protein profiles underlying major transitions in aspen wood development.

    Science.gov (United States)

    Obudulu, Ogonna; Bygdell, Joakim; Sundberg, Björn; Moritz, Thomas; Hvidsten, Torgeir R; Trygg, Johan; Wingsle, Gunnar

    2016-02-18

    Wood development is of outstanding interest both to basic research and industry due to the associated cellulose and lignin biomass production. Efforts to elucidate wood formation (which is essential for numerous aspects of both pure and applied plant science) have been made using transcriptomic analyses and/or low-resolution sampling. However, transcriptomic data do not correlate perfectly with levels of expressed proteins due to effects of post-translational modifications and variations in turnover rates. In addition, high-resolution analysis is needed to characterize key transitions. In order to identify protein profiles across the developmental region of wood formation, an in-depth and tissue specific sampling was performed. We examined protein profiles, using an ultra-performance liquid chromatography/quadrupole time of flight mass spectrometry system, in high-resolution tangential sections spanning all wood development zones in Populus tremula from undifferentiated cambium to mature phloem and xylem, including cell expansion and cell death zones. In total, we analyzed 482 sections, 20-160 μm thick, from four 47-year-old trees growing wild in Sweden. We obtained high quality expression profiles for 3,082 proteins exhibiting consistency across the replicates, considering that the trees were growing in an uncontrolled environment. A combination of Principal Component Analysis (PCA), Orthogonal Projections to Latent Structures (OPLS) modeling and an enhanced stepwise linear modeling approach identified several major transitions in global protein expression profiles, pinpointing (for example) locations of the cambial division leading to phloem and xylem cells, and secondary cell wall formation zones. We also identified key proteins and associated pathways underlying these developmental landmarks. For example, many of the lignocellulosic related proteins were upregulated in the expansion to the early developmental xylem zone, and for laccases with a rapid decrease

  2. Phytoremediation of azoxystrobin and its degradation products in soil by P. major L. under cold and salinity stress.

    Science.gov (United States)

    Romeh, Ahmed Ali Ali

    2017-10-01

    Azoxystrobin is a broad-spectrum, systemic and soil-applied fungicide used for crop protection against the four major classes of pathogenic fungi. The use of azoxystrobin use has induced water pollution and ecotoxicological effects upon aquatic organisms, long half-life in soils, as well as heath issues. Such issues may be solved by phytoremediation. Here, we tested the uptake and translocation of azoxystrobin and its degradation products by Plantago major, under cold stress and salt stress. The result demonstrated that azoxystrobin significantly accumulated in P. major roots under salinity conditions more than that in the P. major roots under cold conditions and natural condition within two days of experimental period. In P. major roots and leaves, the chromatograms of HPLC for azoxystrobin and metabolites under natural condition (control) and stressed samples (cold stress and salt stress) show different patterns of metabolism pathways reflecting changes in the degradation products. Azoxystrobin carboxylic acid (AZ-acid) formed by methyl ester hydrolysis was an important route in the roots and the leaves. AZ-pyOH and AZ-benzoic were detected in P. major roots under cold and salt stress, while did not detected in P. major roots under natural condition. In the leaves, AZ-pyOH and AZ-benzoic were detected in all treatments between 4 and 12days of exposure. Shoots of the stressed plants had greater H 2 O 2 and proline contents than was observed in the control plants. The level of 100mM NaCl treatment induced significantly higher peroxidase (POD) activity than the non-treated control group. Leaf Chlorophyll contents in the plants at 80 and 100mM NaCl were significantly reduced than was observed in the control plants. I concluded that P. major had a high potential to contribute to remediation of saline-soil contaminated with azoxystrobin. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Bottom-Up Determination of Air-Sea Momentum Exchange Under a Major Tropical Cyclone

    National Research Council Canada - National Science Library

    Jarosz, Ewa; Mitchell, Douglas A; Wang, David W; Teague, William J

    2007-01-01

    .... Using current observations recorded during a major tropical cyclone, we have estimated this momentum transfer from the ocean side of the air-sea interface, and we discuss it in terms of the drag coefficient...

  4. Freshwater Fungal Infections

    Directory of Open Access Journals (Sweden)

    Dennis J. Baumgardner

    2017-01-01

    Full Text Available Fungal infections as a result of freshwater exposure or trauma are fortunately rare. Etiologic agents are varied, but commonly include filamentous fungi and Candida. This narrative review describes various sources of potential freshwater fungal exposure and the diseases that may result, including fungal keratitis, acute otitis externa and tinea pedis, as well as rare deep soft tissue or bone infections and pulmonary or central nervous system infections following traumatic freshwater exposure during natural disasters or near-drowning episodes. Fungal etiology should be suspected in appropriate scenarios when bacterial cultures or molecular tests are normal or when the infection worsens or fails to resolve with appropriate antibacterial therapy.

  5. Oil majors under states pressure: two examples in the Caspian basin

    International Nuclear Information System (INIS)

    Lussac, Samuel; Raballand, Gael

    2011-01-01

    All over the world, and especially in developing countries, governments strive to strengthen national oil companies over oil and gas majors. The Caspian, and notably Azerbaijan and Kazakhstan, is not an exception to this current trend. This article sheds light on the leverages both Azerbaijani and Kazakhstani governments have used to increase pressure over oil and gas multinationals. In a first step, they both established a publicly-owned integrated company managed by the presidential entourage. Then, Azerbaijan and Kazakhstan have applied various instruments. Baku has sought to increase its own oil production to decrease the role of majors while Astana has preferred to use ecological, fiscal, legal and logistical leverages. However, in both cases, the outcome has been rather similar since the increasing pressure over majors has not necessarily led to benefit local populations

  6. Courage under Fire: Duval County's School Board Chair Faces a Major Leadership Challenge

    Science.gov (United States)

    Fossey, Richard; Jenkins, Lynn

    2011-01-01

    This case set in Jacksonville, Florida, covers the years 1998 to 2001. A new nontraditional superintendent, Major General John C. Fryer, focuses on student achievement, but financial needs and Florida law require him to bid contracts for student transportation, upsetting a 50-year pattern of contracting without competitive bidding with more than…

  7. Changing Arctic Ocean freshwater pathways.

    Science.gov (United States)

    Morison, James; Kwok, Ron; Peralta-Ferriz, Cecilia; Alkire, Matt; Rigor, Ignatius; Andersen, Roger; Steele, Mike

    2012-01-04

    Freshening in the Canada basin of the Arctic Ocean began in the 1990s and continued to at least the end of 2008. By then, the Arctic Ocean might have gained four times as much fresh water as comprised the Great Salinity Anomaly of the 1970s, raising the spectre of slowing global ocean circulation. Freshening has been attributed to increased sea ice melting and contributions from runoff, but a leading explanation has been a strengthening of the Beaufort High--a characteristic peak in sea level atmospheric pressure--which tends to accelerate an anticyclonic (clockwise) wind pattern causing convergence of fresh surface water. Limited observations have made this explanation difficult to verify, and observations of increasing freshwater content under a weakened Beaufort High suggest that other factors must be affecting freshwater content. Here we use observations to show that during a time of record reductions in ice extent from 2005 to 2008, the dominant freshwater content changes were an increase in the Canada basin balanced by a decrease in the Eurasian basin. Observations are drawn from satellite data (sea surface height and ocean-bottom pressure) and in situ data. The freshwater changes were due to a cyclonic (anticlockwise) shift in the ocean pathway of Eurasian runoff forced by strengthening of the west-to-east Northern Hemisphere atmospheric circulation characterized by an increased Arctic Oscillation index. Our results confirm that runoff is an important influence on the Arctic Ocean and establish that the spatial and temporal manifestations of the runoff pathways are modulated by the Arctic Oscillation, rather than the strength of the wind-driven Beaufort Gyre circulation.

  8. Foundational Concepts and Underlying Theories for Majors in "Biochemistry and Molecular Biology"

    Science.gov (United States)

    Tansey, John T.; Baird, Teaster, Jr.; Cox, Michael M.; Fox, Kristin M.; Knight, Jennifer; Sears, Duane; Bell, Ellis

    2013-01-01

    Over the past two years, through an NSF RCN UBE grant, the ASBMB has held regional workshops for faculty members and science educators from around the country that focused on identifying: 1) core principles of biochemistry and molecular biology, 2) essential concepts and underlying theories from physics, chemistry, and mathematics, and 3)…

  9. Shell's Role in the Future European Gas Scene - Is a Major Market Restructuring Under Way?

    International Nuclear Information System (INIS)

    Segundo, Karen de

    1999-01-01

    The European gas market is being restructured by a combination of major global forces. Environmental considerations like the Kyoto Agreement favour the use of gas. But in the medium-term, supplies may be limited by low energy prices. The political drive for increased competition has manifested itself as the EU Gas Directive, which came into force in 1998. Shell believes that the European industry must progressively adapt to this restructuring. Flexible mechanisms like tradable emission permits should be used to generate investment capital for new gas supply projects. Moreover, both industry and regulators should take a positive and constructive approach towards increasing competition in the marketplace

  10. Song Leading Effectiveness of Undergraduate Education Majors: A Comparison of Student Self Ratings and Expert Ratings under Three Conditions.

    Science.gov (United States)

    Barry, Nancy H.; Orlofsky, Diane DeNicola

    1997-01-01

    Examines the song leading effectiveness of undergraduate education majors under three conditions: unaccompanied, accompanied with autoharp, and accompanied by recording. Finds that students rate themselves higher than experts do; there is greater eye contact using rote or recording; and there is greater tempo accuracy using rote and autoharp. (DSK)

  11. Family Conflict – The Major Underlying Influence in Suicide Attempts in Northern Bihar, India.

    Directory of Open Access Journals (Sweden)

    Sangeeta Nair

    2015-01-01

    Full Text Available Suicide attempts in North India are generally underreported but have been considered to be rising. The number of admissions due to attempted suicide at Duncan Hospital, North Bihar, rose from 82 in 2007 to 419 in 2011.A structured interview and the WHO (World Health Organization Major (ICD-10 Depression Inventory were completed by 157 suicide-attempt survivors. Immediate relatives were also interviewed. Only 23% of patients came from India; 77% of patients came from Nepal. The highest incidence was in the age group 16-20 years. Females have higher rates in the 21-30 year age group (p=0.012, but after 30 years of age, the number of males becomes higher than the females (p=0.048; 81.5% of the respondents were below the age of 30 years.Pesticide poisoning was the major mode of attempted suicide (94.3%. Using the WHO Major (ICD-10 Depression Inventory, 28 of the participants suffered from depression (17.7%. Ninety people (56.9% admitted to previous thoughts of suicide, and nine (5.7% people had attempted suicide previously.Hindus made up 84.0% of the respondents. Almost 50% of respondents only carried out their religious rituals on an occasional basis or not at all. 70.2% had not completed education beyond primary school, and 49.7% earned less than Rs10,000 per month (US$200. Eighty percent of the participants stated conflicts with family members led to the attempted suicide. Relatives did not expect the attempted suicide in 97.4% of cases. Knowledge of the suicide of a neighbour, friends, or relative influenced 77.0% of the participants to attempt suicide.Efforts to prevent suicide attempts and deaths need to be multifaceted. Banning the most poisonous pesticides and improving poison storage in the community must be encouraged. Prevention, early intervention and treatment all are required in a suicide prevention plan. The lack of psychiatrists necessitates that other professionals and trained non-professionals be utilised in the mental health team

  12. Thermal-structural response of EBR-II major components under reactor operational transients

    International Nuclear Information System (INIS)

    Chang, L.K.; Lee, M.J.

    1983-01-01

    Until recently, the LMFBR safety research has been focused primarily on severe but highly unlikely accident, such as hypothetical-core-disruptive accidents (HCDA's), and not enough attention has been given to accident prevention, which is less severe but more likely sequence. The objective of the EBR-II operational reliability testing (ORT) is to demonstrate that the reactor can be designed and operated to prevent accident. A series of mild duty cycles and overpower transients were designed for accident prevention tests. An assessment of the EBR-II major plant components has been performed to assure structural integrity of the reactor plant for the ORT program. In this paper, the thermal-structural response and structural evaluation of the reactor vessel, the reactor-vessel cover, the intermediate heat exchanger (IHX) and the superheater are presented

  13. Aviation safety and maintenance under major organizational changes, investigating non-existing accidents.

    Science.gov (United States)

    Herrera, Ivonne A; Nordskag, Arve O; Myhre, Grete; Halvorsen, Kåre

    2009-11-01

    The objective of this paper is to discuss the following questions: Do concurrent organizational changes have a direct impact on aviation maintenance and safety, if so, how can this be measured? These questions were part of the investigation carried out by the Accident Investigation Board, Norway (AIBN). The AIBN investigated whether Norwegian aviation safety had been affected due to major organizational changes between 2000 and 2004. The main concern was the reduction in safety margins and its consequences. This paper presents a summary of the techniques used and explains how they were applied in three airlines and by two offshore helicopter operators. The paper also discusses the development of safety related indicators in the aviation industry. In addition, there is a summary of the lessons learned and safety recommendations. The Norwegian Ministry of Transport has required all players in the aviation industry to follow up the findings and recommendations of the AIBN study.

  14. Greenhouse gases emission from soils under major crops in Northwest India

    Energy Technology Data Exchange (ETDEWEB)

    Jain, N., E-mail: nivetajain@gmail.com [Centre for Environment Science and Climate Resilient Agriculture, ICAR-Indian Agricultural Research Institute, New Delhi 110 012 (India); Arora, P.; Tomer, R.; Mishra, Shashi Vind; Bhatia, A.; Pathak, H. [Centre for Environment Science and Climate Resilient Agriculture, ICAR-Indian Agricultural Research Institute, New Delhi 110 012 (India); Chakraborty, D. [Division of Agricultural Physics, ICAR-Indian Agricultural Research Institute, New Delhi 110 012 (India); Kumar, Vinod; Dubey, D.S.; Harit, R.C.; Singh, J.P. [Centre for Environment Science and Climate Resilient Agriculture, ICAR-Indian Agricultural Research Institute, New Delhi 110 012 (India)

    2016-01-15

    Quantification of greenhouse gases (GHGs) emissions from agriculture is necessary to prepare the national inventories and to develop the mitigation strategies. Field experiments were conducted during 2008–2010 at the experimental farm of the Indian Agricultural Research Institute, New Delhi, India to quantify nitrous oxide (N{sub 2}O), methane (CH{sub 4}), and carbon dioxide (CO{sub 2}) emissions from soils under cereals, pulses, millets, and oilseed crops. Total cumulative N{sub 2}O emissions were significantly different (P > 0.05) among the crop types. Emission of N{sub 2}O as percentage of applied N was the highest in pulses (0.67%) followed by oilseeds (0.55%), millets (0.43%) and cereals (0.40%). The emission increased with increasing rate of N application (r{sup 2} = 0.74, P < 0.05). The cumulative flux of CH{sub 4} from the rice crop was 28.64 ± 4.40 kg ha{sup −1}, while the mean seasonal integrated flux of CO{sub 2} from soils ranged from 3058 ± 236 to 3616 ± 157 kg CO{sub 2} ha{sup −1} under different crops. The global warming potential (GWP) of crops varied between 3053 kg CO{sub 2} eq. ha{sup −1} (pigeon pea) and 3968 kg CO{sub 2} eq. ha{sup −1} (wheat). The carbon equivalent emission (CEE) was least in pigeon pea (833 kg C ha{sup −1}) and largest in wheat (1042 kg C ha{sup −1}). The GWP per unit of economic yield was the highest in pulses and the lowest in cereal crops. The uncertainties in emission values varied from 4.6 to 22.0%. These emission values will be useful in updating the GHGs emission inventory of Indian agriculture. - Highlights: • Nitrous oxide, methane and carbon dioxide emission were quantified from soils under cereals, millets, oilseeds, and pulses in northwest India. • The emission of nitrous oxide ranged from 0.57–1.3 kg ha{sup −1}, methane from 27.78–29.50 kg ha{sup −1} and carbon dioxide from 2377–3910 kg ha{sup −1}. • Emission of nitrous oxide as percent of applied N was highest in pulses (0

  15. Greenhouse gases emission from soils under major crops in Northwest India

    International Nuclear Information System (INIS)

    Jain, N.; Arora, P.; Tomer, R.; Mishra, Shashi Vind; Bhatia, A.; Pathak, H.; Chakraborty, D.; Kumar, Vinod; Dubey, D.S.; Harit, R.C.; Singh, J.P.

    2016-01-01

    Quantification of greenhouse gases (GHGs) emissions from agriculture is necessary to prepare the national inventories and to develop the mitigation strategies. Field experiments were conducted during 2008–2010 at the experimental farm of the Indian Agricultural Research Institute, New Delhi, India to quantify nitrous oxide (N 2 O), methane (CH 4 ), and carbon dioxide (CO 2 ) emissions from soils under cereals, pulses, millets, and oilseed crops. Total cumulative N 2 O emissions were significantly different (P > 0.05) among the crop types. Emission of N 2 O as percentage of applied N was the highest in pulses (0.67%) followed by oilseeds (0.55%), millets (0.43%) and cereals (0.40%). The emission increased with increasing rate of N application (r 2 = 0.74, P < 0.05). The cumulative flux of CH 4 from the rice crop was 28.64 ± 4.40 kg ha −1 , while the mean seasonal integrated flux of CO 2 from soils ranged from 3058 ± 236 to 3616 ± 157 kg CO 2 ha −1 under different crops. The global warming potential (GWP) of crops varied between 3053 kg CO 2 eq. ha −1 (pigeon pea) and 3968 kg CO 2 eq. ha −1 (wheat). The carbon equivalent emission (CEE) was least in pigeon pea (833 kg C ha −1 ) and largest in wheat (1042 kg C ha −1 ). The GWP per unit of economic yield was the highest in pulses and the lowest in cereal crops. The uncertainties in emission values varied from 4.6 to 22.0%. These emission values will be useful in updating the GHGs emission inventory of Indian agriculture. - Highlights: • Nitrous oxide, methane and carbon dioxide emission were quantified from soils under cereals, millets, oilseeds, and pulses in northwest India. • The emission of nitrous oxide ranged from 0.57–1.3 kg ha −1 , methane from 27.78–29.50 kg ha −1 and carbon dioxide from 2377–3910 kg ha −1 . • Emission of nitrous oxide as percent of applied N was highest in pulses (0.67%) followed by oilseeds (0.55%). • Global warming potential (GWP) of soils under different

  16. Certification of CCHEN's products and services under ISO 9001/2000. A major and opportune challenge

    International Nuclear Information System (INIS)

    Silva Gundelach, Carmen

    2003-01-01

    The quality revolution and the ISO 9000 standards were among the most important management tools created during the second half of the 20th century. ISO 9000 is a management standard that allows an organization to demonstrate its quality level. It is a marketing instrument used for the difficult task of maintaining and winning new markets. More importantly, it is a proven and accepted worldwide model for an organizational system to attain a world quality level and to focus on 'continuous improvement'. For this reason, CCHEN cannot remain out of this new way of working. CCHEN must generate a record of its processes within the concept of Continuous Improvement, in order to be present and considered in today's marketplace. 'Continuous improving' is defined as a permanent activity and attitude aimed at increasing the ability to respond to a client's requirements. Taking into account the impact and importance of its products and services, CCHEN decided to request certification under ISO 9001/2000 of: Personal Dosimetry Service, Irradiation in the Multipurpose Sterilization Plant for the Pharmaceutical and Cosmetics Industry, Technetium-99m and MDP Production,and Production of MTR type Fuel Elements. This certification will demonstrate the quality level and the efficacy of each one of CCHEN's processes. Working under ISO 9001/2000 will allow CCHEN to organize and systematize information related to continuous improvement and focusing on client satisfaction clients, by defining their needs and expectations with the use of a management tool and most importantly by using information, facts and optimizing resources (Au)

  17. Freshwater and fish

    International Nuclear Information System (INIS)

    Saxen, R.

    1997-01-01

    Severe radioactive contamination of the freshwater environment could have serious consequences for both drinking water and fish. Most of the Nordic countries have an abundance of freshwater lakes and rivers. Finland alone has about 56,000 lakes, each with a surface area of 1 hectare or more. Nearly 10% of Finland's surface is covered with lakes and rivers. In Sweden, about 9% of the surface area is freshwater, in Norway about 5%, and in Denmark only about 2%. Freshwater plays a minor role in Iceland, but even there numerous rivers discharge from the volcanic soils to the Ocean. Cs-137 and 90 Sr are likely to be the most important radionuclides with respect to long term radioactive contamination of freshwater. If radioactive deposition occurs in the absence of snow and ice radionuclides will contaminate the surface water directly and may rapidly enter the aquatic food chain. Fish which eat contaminated plankton become contaminated almost immediately. Deposition during summer increases the transfer for radionuclides to fish since fish metabolism is faster during the warm season. During the cold period, fish metabolism is slow and thus uptake and excretion of radiocaesium are also slow. (EG)

  18. Physiological characteristics of Plantago major under SO2 exposure as affected by foliar iron spray.

    Science.gov (United States)

    Mohasseli, Vahid; Khoshgoftarmanesh, Amir Hossein; Shariatmadari, Hossein

    2017-08-01

    Sulfur dioxide (SO 2 ) is considered as a main air pollutant in industrialized areas that can damage vegetation. In the present study, we investigated how exposure to SO 2 and foliar application of iron (Fe) would affect certain physiological characteristics of Plantago major. The plant seedlings exposed or unexposed to SO 2 (3900 μg m -3 ) were non-supplemented or supplemented with Fe (3 g L -1 ) as foliar spray. Plants were exposed to SO 2 for 6 weeks in 100 × 70 × 70 cm chambers. Fumigation of plants with SO 2 was performed for 3 h daily for 3 days per week (alternate day). Lower leaf Fe concentration in the plants exposed to SO 2 at no added Fe treatment was accompanied with incidence of chlorosis symptoms and reduced chlorophyll concentration. No visible chlorotic symptoms were observed on the SO 2 -exposed plants supplied with Fe that accumulated higher Fe in their leaves. Both at with and without added Fe treatments, catalase (CAT) and peroxidase (POD) activity was higher in the plants fumigated with SO 2 in comparison with those non-fumigated with SO 2 . Foliar application of Fe was also effective in increasing activity of antioxidant enzymes CAT and POD. Exposure to SO 2 led to reduced cellulose but enhanced lignin content of plant leaf cell wall. The results obtained showed that foliar application of Fe was effective in reducing the effects of exposure to SO 2 on cell wall composition. In contrast to SO 2 , application of Fe increased cellulose while decreased lignin content of the leaf cell wall. This might be due to reduced oxidative stress induced by SO 2 in plants supplied with Fe compared with those unsupplied with Fe.

  19. Effects of the pyrethroid insecticide, cypermethrin, on a freshwater community studied under field conditions. I. Direct and indirect effects on abundance measures of organisms at different trophic levels

    Energy Technology Data Exchange (ETDEWEB)

    Friberg-Jensen, Ursula; Wendt-Rasch, Lina; Woin, Per; Christoffersen, Kirsten

    2003-05-29

    The effects of the pyrethroid insecticide cypermethrin on a natural freshwater community were studied in small in situ enclosures over an 11-day period. The experiment was conducted in a eutrophic lake using a regression design that included three untreated controls and a gradient of six unreplicated cypermethrin concentrations, ranging from 0.01 to 6.1 {mu}g/l. This paper is the first in a series of two, and describes the fate of cypermethrin and its effects on the abundance of crustaceans, rotifers, protozoans (cilliates and heterotrophic nanoflagellates (HNF)) and bacteria and the biomass of periphytic and planktonic algae. The concentration of cypermethrin decreased quickly during the experiment, with a half-life of 48 h for the total and 25 h for the dissolved fractions of cypermethrin, respectively. Cypermethrin proved to be acutely toxic to crustaceans in enclosures receiving nominal cypermethrin concentrations of {>=}0.13 {mu}g/l. No Effect Concentration (NEC) and median Effect Concentration (EC{sub 50}) for the total crustacean community and cladoceran and copepod subgroups ranged between 0.02-0.07 and 0.04-0.17 {mu}g/l, respectively, with copepods being less sensitive than cladocerans. The abundance of rotifers, protozoans and bacteria and the chlorophyll-a concentration of planktonic and periphytic algae was significantly related to the concentration of cypermethrin. All groups proliferated within 2-7 days after the cypermethrin application in those enclosures where the abundance of crustaceans was seriously affected by cypermethrin (i.e. {>=}0.13 {mu}g/l). We hypothesise that the proliferation of rotifers, protozoans, bacteria and algae was due to a reduced grazer control from crustaceans and thereby mediated indirectly by cypermethrin. The results of this experiment provide knowledge on how an entire microplankton community may respond to pyrethroids in nature, and the indirect effects observed on the community clearly demonstrates the necessity of

  20. Effects of the pyrethroid insecticide, cypermethrin, on a freshwater community studied under field conditions. I. Direct and indirect effects on abundance measures of organisms at different trophic levels

    International Nuclear Information System (INIS)

    Friberg-Jensen, Ursula; Wendt-Rasch, Lina; Woin, Per; Christoffersen, Kirsten

    2003-01-01

    The effects of the pyrethroid insecticide cypermethrin on a natural freshwater community were studied in small in situ enclosures over an 11-day period. The experiment was conducted in a eutrophic lake using a regression design that included three untreated controls and a gradient of six unreplicated cypermethrin concentrations, ranging from 0.01 to 6.1 μg/l. This paper is the first in a series of two, and describes the fate of cypermethrin and its effects on the abundance of crustaceans, rotifers, protozoans (cilliates and heterotrophic nanoflagellates (HNF)) and bacteria and the biomass of periphytic and planktonic algae. The concentration of cypermethrin decreased quickly during the experiment, with a half-life of 48 h for the total and 25 h for the dissolved fractions of cypermethrin, respectively. Cypermethrin proved to be acutely toxic to crustaceans in enclosures receiving nominal cypermethrin concentrations of ≥0.13 μg/l. No Effect Concentration (NEC) and median Effect Concentration (EC 50 ) for the total crustacean community and cladoceran and copepod subgroups ranged between 0.02-0.07 and 0.04-0.17 μg/l, respectively, with copepods being less sensitive than cladocerans. The abundance of rotifers, protozoans and bacteria and the chlorophyll-a concentration of planktonic and periphytic algae was significantly related to the concentration of cypermethrin. All groups proliferated within 2-7 days after the cypermethrin application in those enclosures where the abundance of crustaceans was seriously affected by cypermethrin (i.e. ≥0.13 μg/l). We hypothesise that the proliferation of rotifers, protozoans, bacteria and algae was due to a reduced grazer control from crustaceans and thereby mediated indirectly by cypermethrin. The results of this experiment provide knowledge on how an entire microplankton community may respond to pyrethroids in nature, and the indirect effects observed on the community clearly demonstrates the necessity of multispecies

  1. Freshwater exposure pathways in the Nordic countries

    International Nuclear Information System (INIS)

    Tveten, U.

    1984-06-01

    The report relates to a subproject under a Nordic project called ''Large reactor accidents - consequences and mitigating actions''. The report summarizes information available, primarily in the Nordic countries, on freshwater exposure pathways. Experimental and theoretical data concerning the deposition and run-off of the nuclides *sp90*Sr and*Sp137*Cs is presented. Internal exposure via drinking water and freshwater fish is dealt with, as well as external exposure due to swimming, boating, contact with fishing utensils and use of beach areas. In addition is exposure via irrigated agricultural products considered. (RF)

  2. Effects of pollution on freshwater fish

    International Nuclear Information System (INIS)

    McKim, J.M.; Christensen, G.M.; Tucker, J.H.; Benoit, D.A.; Lewis, M.J.

    1974-01-01

    Various aspects of pollution effects on fishes are reviewed under the following headings: methodology; water quality; pesticide pollutants; industrial pollutants; domestic pollutants; radioactive pollutants; and other pollutants. A table is presented to show acute and chronic toxicity of inorganic and organic pollutants to freshwater fish. (U.S.)

  3. Sulfate reduction and methanogenesis at a freshwater

    DEFF Research Database (Denmark)

    Iversen, Vibeke Margrethe Nyvang; Andersen, Martin Søgaard; Jakobsen, Rasmus

    The freshwater-seawater interface was studied in a ~9-m thick anaerobic aquifer located in marine sand and gravel with thin peat lenses. Very limited amounts of iron-oxides are present. Consequently, the dominating redox processes are sulfate reduction and methanogenesis, and the groundwater...... is enriched in dissolved sulfide, methane and bicarbonate. Under normal conditions the seawater-freshwater interface is found at a depth of 4 m at the coastline and reaches the bottom of the aquifer 40 m inland. However, occasional flooding of the area occurs, introducing sulfate to the aquifer. Groundwater...... chemistry was studied in a 120 m transect perpendicular to the coast. Cores were taken for radiotracer rate measurements of sulfate reduction and methanogenesis. In the saline part of the aquifer 35 m inland, sulfate reduction was the dominant process with rates of 0.1-10 mM/year. In the freshwater part 100...

  4. Freshwater autotrophic picoplankton: a review

    Directory of Open Access Journals (Sweden)

    John G. STOCKNER

    2002-02-01

    Full Text Available Autotrophic picoplankton (APP are distributed worldwide and are ubiquitous in all types of lakes of varying trophic state. APP are major players in carbon production in all aquatic ecosystems, including extreme environments such as cold ice-covered and/or warm tropical lakes and thermal springs. They often form the base of complex microbial food webs, becoming prey for a multitude of protozoan and micro-invertebrate grazers, that effectively channel APP carbon to higher trophic levels including fish. In this review we examine the existing literature on freshwater autotrophic picoplankton, setting recent findings and current ecological issues within an historic framework, and include a description of the occurrence and distribution of both single-cell and colonial APP (picocyanobacteria in different types of lakes. In this review we place considerable emphasis on methodology and ecology, including sampling, counting, preservation, molecular techniques, measurement of photosynthesis, and include extensive comment on their important role in microbial food webs. The model outlined by Stockner of an increase of APP abundance and biomass and a decrease of its relative importance with the increase of phosphorus concentration in lakes has been widely accepted, and only recently confirmed in marine and freshwater ecosystems. Nevertheless the relationship which drives the APP presence and importance in lakes of differing trophic status appears with considerable variation so we must conclude that the success of APP in oligotrophic lakes worldwide is not a certainty but highly probable.

  5. Pathogenic agents in freshwater resources

    Science.gov (United States)

    Geldreich, Edwin E.

    1996-02-01

    Numerous pathogenic agents have been found in freshwaters used as sources for water supplies, recreational bathing and irrigation. These agents include bacterial pathogens, enteric viruses, several protozoans and parasitic worms more common to tropical waters. Although infected humans are a major source of pathogens, farm animals (cattle, sheep, pigs), animal pets (dogs, cats) and wildlife serve as significant reservoirs and should not be ignored. The range of infected individuals within a given warm-blooded animal group (humans included) may range from 1 to 25%. Survival times for pathogens in the water environment may range from a few days to as much as a year (Ascaris, Taenia eggs), with infective dose levels varying from one viable cell for several primary pathogenic agents to many thousands of cells for a given opportunistic pathogen.As pathogen detection in water is complex and not readily incorporated into routine monitoring, a surrogate is necessary. In general, indicators of faecal contamination provide a positive correlation with intestinal pathogen occurrences only when appropriate sample volumes are examined by sensitive methodology.Pathways by which pathogens reach susceptible water users include ingestion of contaminated water, body contact with polluted recreational waters and consumption of salad crops irrigated by polluted freshwaters. Major contributors to the spread of various water-borne pathogens are sewage, polluted surface waters and stormwater runoff. All of these contributions are intensified during periods of major floods. Several water-borne case histories are cited as examples of breakdowns in public health protection related to water supply, recreational waters and the consumption of contaminated salad crops. In the long term, water resource management must focus on pollution prevention from point sources of waste discharges and the spread of pathogens in watershed stormwater runoff.

  6. Major differences observed in transcript profiles of blueberry during cold acclimation under field and cold room conditions.

    Science.gov (United States)

    Dhanaraj, Anik L; Alkharouf, Nadim W; Beard, Hunter S; Chouikha, Imed B; Matthews, Benjamin F; Wei, Hui; Arora, Rajeev; Rowland, Lisa J

    2007-02-01

    Our laboratory has been working toward increasing our understanding of the genetic control of cold hardiness in blueberry (Vaccinium section Cyanococcus) to ultimately use this information to develop more cold hardy cultivars for the industry. Here, we report using cDNA microarrays to monitor changes in gene expression at multiple times during cold acclimation under field and cold room conditions. Microarrays contained over 2,500 cDNA inserts, approximately half of which had been picked and single-pass sequenced from each of two cDNA libraries that were constructed from cold acclimated floral buds and non-acclimated floral buds of the fairly cold hardy cv. Bluecrop (Vaccinium corymbosum L.). Two biological samples were examined at each time point. Microarray data were analyzed statistically using t tests, ANOVA, clustering algorithms, and online analytical processing (OLAP). Interestingly, more transcripts were found to be upregulated under cold room conditions than under field conditions. Many of the genes induced only under cold room conditions could be divided into three major types: (1) genes associated with stress tolerance; (2) those that encode glycolytic and TCA cycle enzymes, and (3) those associated with protein synthesis machinery. A few of the genes induced only under field conditions appear to be related to light stress. Possible explanations for these differences are discussed in physiological context. Although many similarities exist in how plants respond during cold acclimation in the cold room and in the field environment, there are major differences suggesting caution should be taken in interpreting results based only on artificial, cold room conditions.

  7. A physically based model of global freshwater surface temperature

    Science.gov (United States)

    van Beek, Ludovicus P. H.; Eikelboom, Tessa; van Vliet, Michelle T. H.; Bierkens, Marc F. P.

    2012-09-01

    Temperature determines a range of physical properties of water and exerts a strong control on surface water biogeochemistry. Thus, in freshwater ecosystems the thermal regime directly affects the geographical distribution of aquatic species through their growth and metabolism and indirectly through their tolerance to parasites and diseases. Models used to predict surface water temperature range between physically based deterministic models and statistical approaches. Here we present the initial results of a physically based deterministic model of global freshwater surface temperature. The model adds a surface water energy balance to river discharge modeled by the global hydrological model PCR-GLOBWB. In addition to advection of energy from direct precipitation, runoff, and lateral exchange along the drainage network, energy is exchanged between the water body and the atmosphere by shortwave and longwave radiation and sensible and latent heat fluxes. Also included are ice formation and its effect on heat storage and river hydraulics. We use the coupled surface water and energy balance model to simulate global freshwater surface temperature at daily time steps with a spatial resolution of 0.5° on a regular grid for the period 1976-2000. We opt to parameterize the model with globally available data and apply it without calibration in order to preserve its physical basis with the outlook of evaluating the effects of atmospheric warming on freshwater surface temperature. We validate our simulation results with daily temperature data from rivers and lakes (U.S. Geological Survey (USGS), limited to the USA) and compare mean monthly temperatures with those recorded in the Global Environment Monitoring System (GEMS) data set. Results show that the model is able to capture the mean monthly surface temperature for the majority of the GEMS stations, while the interannual variability as derived from the USGS and NOAA data was captured reasonably well. Results are poorest for

  8. Quantifying the effect of catchment land-use and water nutrient concentrations on freshwater river and stream biodiversity

    NARCIS (Netherlands)

    Weijters, M.J.; Janse, J.H.; Alkemade, J.R.M.; Verhoeven, J.T.A.

    2009-01-01

    A major threat to freshwater taxon diversity is the alteration of natural catchment Land use into agriculture, industry or urban areas and the associated eutrophication of the water. In order to stop freshwater biodiversity loss, it is essential to quantify the relationships between freshwater

  9. Toxicology of freshwater cyanobacteria.

    Science.gov (United States)

    Liyanage, H M; Arachchi, D N Magana; Abeysekara, T; Guneratne, L

    2016-07-02

    Many chemical contaminants in drinking water have been shown to cause adverse health effects in humans after prolonged exposure. Cyanobacteria are one of the most potent and diverse groups of photosynthetic prokaryotes. One key component of cyanobacterial success in the environment is the production of potent toxins as secondary metabolites, which have been responsible for numerous adverse health impacts in humans. Anthropogenic activities have led to the increase of eutrophication in freshwater bodies' worldwide, causing cyanobacterial blooms to become more frequent. The present article will discuss about harmful cyanobacteria and their toxicology with special references to microcystin, nodularin, and cylindrospermopsin.

  10. Pesticides in Brazilian freshwaters: a critical review.

    Science.gov (United States)

    Albuquerque, A F; Ribeiro, J S; Kummrow, F; Nogueira, A J A; Montagner, C C; Umbuzeiro, G A

    2016-07-13

    The widespread use of pesticides in agriculture can lead to water contamination and cause adverse effects on non-target organisms. Brazil has been the world's top pesticide market consumer since 2008, with 381 approved pesticides for crop use. This study provides a comprehensive literature review on the occurrence of pesticide residues in Brazilian freshwaters. We searched for information in official agency records and peer-reviewed scientific literature. Risk quotients were calculated to assess the potential risk posed to aquatic life by the individual pesticides based on their levels of water contamination. Studies about the occurrence of pesticides in freshwaters in Brazil are scarce and concentrated in few sampling sites in 5 of the 27 states. Herbicides (21) accounted for the majority of the substances investigated, followed by fungicides (11), insecticides (10) and plant growth regulators (1). Insecticides are the class of major concern. Brazil would benefit from the implementation of a nationwide pesticide freshwater monitoring program to support preventive, remediation and enforcement actions.

  11. Future Freshwater Stress on Small Islands: Population, Aridity and Global Warming Targets

    Science.gov (United States)

    Karnauskas, K. B.; Schleussner, C. F.; Donnelly, J. P.; Anchukaitis, K. J.

    2017-12-01

    Small island developing states (SIDS) face multiple threats from anthropogenic climate change, including potential changes in freshwater resource availability. Future freshwater stress, including geographic and seasonal variability, has important implications for climate change adaptation scenarios for vulnerable human populations living on islands across the world ocean. Due to a mismatch in spatial scale between SIDS landforms and the horizontal resolution of global climate models (GCMs), SIDS are mostly unaccounted for in GCMs that are used to make future projections of global climate change and its regional impacts. Specific approaches are required to address this gap between broad-scale model projections and regional, policy-relevant outcomes. Here we apply a recently developed methodology to project future changes in aridity in combination with population projections associated with different shared socioeconomic pathways (SSPs) to evaluate overall changes in freshwater stress in SIDS at warming levels of 1.5°C and 2°C above pre-industrial levels. By accounting for evaporative demand a posteriori, we reveal a robust yet spatially variable tendency towards increasing aridity for 16 million people living on islands by mid-century. Although about half of the islands are projected to experience increased rainfall—predominantly in the deep tropics—projected changes in evaporation are more uniform, shifting the global distribution of changes in island freshwater balance towards greater aridity. In many cases, the magnitude of projected drying is comparable to the amplitude of the estimated observed interannual variability, with important consequences for extreme events. While we find that future population growth will dominate changes in projected freshwater stress especially towards the end of the century, projected changes in aridity are found to compound freshwater stress for the vast majority of SIDS. Particularly across the Caribbean region, a

  12. The Zoogeography of North American freshwater fishes

    National Research Council Canada - National Science Library

    Hocutt, Charles H; Wiley, E. O

    1986-01-01

    ..., and Pleistoscene glaciation. The Zoogeography of North American Freshwater Fishes is a comprehensive treatment of the freshwater biogeography of North America, with implications for other disciplines...

  13. Differential co-expression and regulation analyses reveal different mechanisms underlying major depressive disorder and subsyndromal symptomatic depression.

    Science.gov (United States)

    Xu, Fan; Yang, Jing; Chen, Jin; Wu, Qingyuan; Gong, Wei; Zhang, Jianguo; Shao, Weihua; Mu, Jun; Yang, Deyu; Yang, Yongtao; Li, Zhiwei; Xie, Peng

    2015-04-03

    Recent depression research has revealed a growing awareness of how to best classify depression into depressive subtypes. Appropriately subtyping depression can lead to identification of subtypes that are more responsive to current pharmacological treatment and aid in separating out depressed patients in which current antidepressants are not particularly effective. Differential co-expression analysis (DCEA) and differential regulation analysis (DRA) were applied to compare the transcriptomic profiles of peripheral blood lymphocytes from patients with two depressive subtypes: major depressive disorder (MDD) and subsyndromal symptomatic depression (SSD). Six differentially regulated genes (DRGs) (FOSL1, SRF, JUN, TFAP4, SOX9, and HLF) and 16 transcription factor-to-target differentially co-expressed gene links or pairs (TF2target DCLs) appear to be the key differential factors in MDD; in contrast, one DRG (PATZ1) and eight TF2target DCLs appear to be the key differential factors in SSD. There was no overlap between the MDD target genes and SSD target genes. Venlafaxine (Efexor™, Effexor™) appears to have a significant effect on the gene expression profile of MDD patients but no significant effect on the gene expression profile of SSD patients. DCEA and DRA revealed no apparent similarities between the differential regulatory processes underlying MDD and SSD. This bioinformatic analysis may provide novel insights that can support future antidepressant R&D efforts.

  14. Genome-Wide DNA Methylation Profiling Reveals Epigenetic Adaptation of Stickleback to Marine and Freshwater Conditions.

    Science.gov (United States)

    Artemov, Artem V; Mugue, Nikolai S; Rastorguev, Sergey M; Zhenilo, Svetlana; Mazur, Alexander M; Tsygankova, Svetlana V; Boulygina, Eugenia S; Kaplun, Daria; Nedoluzhko, Artem V; Medvedeva, Yulia A; Prokhortchouk, Egor B

    2017-09-01

    The three-spined stickleback (Gasterosteus aculeatus) represents a convenient model to study microevolution-adaptation to a freshwater environment. Although genetic adaptations to freshwater environments are well-studied, epigenetic adaptations have attracted little attention. In this work, we investigated the role of DNA methylation in the adaptation of the marine stickleback population to freshwater conditions. DNA methylation profiling was performed in marine and freshwater populations of sticklebacks, as well as in marine sticklebacks placed into a freshwater environment and freshwater sticklebacks placed into seawater. We showed that the DNA methylation profile after placing a marine stickleback into fresh water partially converged to that of a freshwater stickleback. For six genes including ATP4A ion pump and NELL1, believed to be involved in skeletal ossification, we demonstrated similar changes in DNA methylation in both evolutionary and short-term adaptation. This suggested that an immediate epigenetic response to freshwater conditions can be maintained in freshwater population. Interestingly, we observed enhanced epigenetic plasticity in freshwater sticklebacks that may serve as a compensatory regulatory mechanism for the lack of genetic variation in the freshwater population. For the first time, we demonstrated that genes encoding ion channels KCND3, CACNA1FB, and ATP4A were differentially methylated between the marine and the freshwater populations. Other genes encoding ion channels were previously reported to be under selection in freshwater populations. Nevertheless, the genes that harbor genetic and epigenetic changes were not the same, suggesting that epigenetic adaptation is a complementary mechanism to selection of genetic variants favorable for freshwater environment. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Microplastics ingestion by a common tropical freshwater fishing resource.

    Science.gov (United States)

    Silva-Cavalcanti, Jacqueline Santos; Silva, José Diego B; França, Elton José de; Araújo, Maria Christina Barbosa de; Gusmão, Felipe

    2017-02-01

    Microplastics pollution is widespread in marine ecosystems and a major threat to biodiversity. Nevertheless, our knowledge of the impacts of microplastics in freshwater environments and biota is still very limited. The interaction of microplastics with freshwater organisms and the risks associated with the human consumption of organisms that ingested microplastics remain major knowledge gaps. In this study, we assessed the ingestion of microplastics by Hoplosternum littorale, a common freshwater fish heavily consumed by humans in semi-arid regions of South America. We assessed the abundance and diversity of both plastic debris and other food items found in the gut of fishes caught by local fishermen. We observed that 83% of the fish had plastic debris inside the gut, the highest frequency reported for a fish species so far. Most of the plastic debris (88.6%) recovered from the guts of fish were microplastics (microplastics at the urbanized sections of the river, and that the ingestion of microplastics was negatively correlated with the diversity of other food items in the gut of individual fish. Nevertheless, microplastics ingestion appears to have a limited impact on H. littorale, and the consequences of human consumption of this fish were not assessed. Our results suggest freshwater biota are vulnerable to microplastics pollution and that urbanization is a major factor contributing to the pollution of freshwater environments with microplastics. We suggest the gut content of fish could be used as a tool for the qualitative assessment of microplastics pollution in freshwater ecosystems. Further research is needed to determine the processes responsible for the high incidence of microplastics ingestion by H. littorale, and to evaluate the risk posed to humans by the consumption of freshwater fish that ingested microplastics. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Physical modeling of the effects of climate change on freshwater lenses

    Science.gov (United States)

    Stoeckl, L.; Houben, G.

    2012-04-01

    The investigation of the fragile equilibrium between fresh and saline water on oceanic islands is of major importance for a sustainable management and protection of freshwater lenses. Overexploitation will lead to salt water intrusion (up-coning), in turn causing damages or even destruction of a lens in the long term. We have performed a series of experiments on the laboratory scale to investigate and visualize processes of freshwater lenses under different boundary conditions. In addition these scenarios were numerically simulated using the finite-element model FEFLOW. Results were also compared to analytical solutions for problems regarding e.g. mean travel times of flow paths within a freshwater lens. On the laboratory scale, a cross section of an island was simulated by setting up a sand-box model (200 cm x 50 cm x 5 cm). Lens dynamics are driven by density contrasts of saline and fresh water, recharge rate and Kf-values of the medium. We used a time-dependent, sequential application of the tracers uranine, eosine and indigotine, to represent different recharge events. With a stepwise increase of freshwater recharge, we could show that the maximum thickness of the lens increased in a non-linear behavior. Moreover we measured that the degradation of a freshwater lens after turning off the precipitation does not follow the same function as its development does. This means that a steady state freshwater lens does not degrade as fast as it develops under constant recharge. On the other side, we could show that this is not true for a partial degradation of the lens due to passing forces, like anthropogenic pumping or climate change. This is, because the recovery to equilibrium is always a quasi asymptotic process. Thus, times of re-equilibration to steady state will take longer after e.g. a drought, than the degradation during the draught itself. This behavior could also be verified applying the numerical finite-element model FEFLOW. In addition, numerical

  17. Restricted-range fishes and the conservation of Brazilian freshwaters.

    Directory of Open Access Journals (Sweden)

    Cristiano Nogueira

    Full Text Available BACKGROUND: Freshwaters are the most threatened ecosystems on earth. Although recent assessments provide data on global priority regions for freshwater conservation, local scale priorities remain unknown. Refining the scale of global biodiversity assessments (both at terrestrial and freshwater realms and translating these into conservation priorities on the ground remains a major challenge to biodiversity science, and depends directly on species occurrence data of high taxonomic and geographic resolution. Brazil harbors the richest freshwater ichthyofauna in the world, but knowledge on endemic areas and conservation in Brazilian rivers is still scarce. METHODOLOGY/PRINCIPAL FINDINGS: Using data on environmental threats and revised species distribution data we detect and delineate 540 small watershed areas harboring 819 restricted-range fishes in Brazil. Many of these areas are already highly threatened, as 159 (29% watersheds have lost more than 70% of their original vegetation cover, and only 141 (26% show significant overlap with formally protected areas or indigenous lands. We detected 220 (40% critical watersheds overlapping hydroelectric dams or showing both poor formal protection and widespread habitat loss; these sites harbor 344 endemic fish species that may face extinction if no conservation action is in place in the near future. CONCLUSIONS/SIGNIFICANCE: We provide the first analysis of site-scale conservation priorities in the richest freshwater ecosystems of the globe. Our results corroborate the hypothesis that freshwater biodiversity has been neglected in former conservation assessments. The study provides a simple and straightforward method for detecting freshwater priority areas based on endemism and threat, and represents a starting point for integrating freshwater and terrestrial conservation in representative and biogeographically consistent site-scale conservation strategies, that may be scaled-up following naturally linked

  18. Restricted-range fishes and the conservation of Brazilian freshwaters.

    Science.gov (United States)

    Nogueira, Cristiano; Buckup, Paulo A; Menezes, Naercio A; Oyakawa, Osvaldo T; Kasecker, Thais P; Ramos Neto, Mario B; da Silva, José Maria C

    2010-06-30

    Freshwaters are the most threatened ecosystems on earth. Although recent assessments provide data on global priority regions for freshwater conservation, local scale priorities remain unknown. Refining the scale of global biodiversity assessments (both at terrestrial and freshwater realms) and translating these into conservation priorities on the ground remains a major challenge to biodiversity science, and depends directly on species occurrence data of high taxonomic and geographic resolution. Brazil harbors the richest freshwater ichthyofauna in the world, but knowledge on endemic areas and conservation in Brazilian rivers is still scarce. Using data on environmental threats and revised species distribution data we detect and delineate 540 small watershed areas harboring 819 restricted-range fishes in Brazil. Many of these areas are already highly threatened, as 159 (29%) watersheds have lost more than 70% of their original vegetation cover, and only 141 (26%) show significant overlap with formally protected areas or indigenous lands. We detected 220 (40%) critical watersheds overlapping hydroelectric dams or showing both poor formal protection and widespread habitat loss; these sites harbor 344 endemic fish species that may face extinction if no conservation action is in place in the near future. We provide the first analysis of site-scale conservation priorities in the richest freshwater ecosystems of the globe. Our results corroborate the hypothesis that freshwater biodiversity has been neglected in former conservation assessments. The study provides a simple and straightforward method for detecting freshwater priority areas based on endemism and threat, and represents a starting point for integrating freshwater and terrestrial conservation in representative and biogeographically consistent site-scale conservation strategies, that may be scaled-up following naturally linked drainage systems. Proper management (e. g. forestry code enforcement, landscape

  19. Freshwater Treatment and Test Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Freshwater Treatment and Test Facility, located at SANGB, has direct year-round access to water from Lake St. Clair and has a State of Michigan approved National...

  20. Freshwater Ecosystem Service Flow Model To Evaluate Regional Water Security: A Case Study In Beijing-Tianjin-Hebei Region, China

    Science.gov (United States)

    Li, D.; Li, S.

    2016-12-01

    Freshwater service, as the most important support ecosystem service, is essential to human survival and development. Many studies have evidenced the spatial differences in the supply and demand of ecosystem services and raised the concept of ecosystem service flow. However, rather few studies quantitatively characterize the freshwater service flow. This paper aims to quantify the effect of freshwater ecosystem service flow on downstream areas in Beijing-Tianjin-Hebei (BTH) region, China over 2000, 2005 and 2010. We computed the freshwater ecosystem service provision with InVEST model. We calculated freshwater ecosystem service consumption with water quota method. We simulated the freshwater ecosystem service flow using our simplified flow model and assessed the regional water security with the improved freshwater security index. The freshwater provision service mainly depends on climatic factors that cannot be influenced by management, while the freshwater consumption service is constrained by human activities. Furthermore, the decrease of water quota for agricultural, domestic and industrial water counteracts the impact of increasing freshwater demand. The analysis of freshwater ecosystem service flow reveals that the majority area of the BTH (69.2%) is affected by upstream freshwater. If freshwater ecosystem service flow is considered, the water safety areas of the whole BTH account for 66.9%, 66.1%, 71.3%, which increase 6.4%, 6.8% and 5.7% in 2000, 2005 and 2010, respectively. These results highlight the need to understand the teleconnections between distant freshwater ecosystem service provision and local freshwater ecosystem service use. This approach therefore helps managers choose specific management and investment strategies for critical upstream freshwater provisions across different regions.

  1. Mechanical challenges to freshwater residency in sharks and rays.

    Science.gov (United States)

    Gleiss, Adrian C; Potvin, Jean; Keleher, James J; Whitty, Jeff M; Morgan, David L; Goldbogen, Jeremy A

    2015-04-01

    Major transitions between marine and freshwater habitats are relatively infrequent, primarily as a result of major physiological and ecological challenges. Few species of cartilaginous fish have evolved to occupy freshwater habitats. Current thought suggests that the metabolic physiology of sharks has remained a barrier to the diversification of this taxon in freshwater ecosystems. Here, we demonstrate that the physical properties of water provide an additional constraint for this species-rich group to occupy freshwater systems. Using hydromechanical modeling, we show that occurrence in fresh water results in a two- to three-fold increase in negative buoyancy for sharks and rays. This carries the energetic cost of lift production and results in increased buoyancy-dependent mechanical power requirements for swimming and increased optimal swim speeds. The primary source of buoyancy, the lipid-rich liver, offers only limited compensation for increased negative buoyancy as a result of decreasing water density; maintaining the same submerged weight would involve increasing the liver volume by very large amounts: 3- to 4-fold in scenarios where liver density is also reduced to currently observed minimal levels and 8-fold without any changes in liver density. The first data on body density from two species of elasmobranch occurring in freshwater (the bull shark Carcharhinus leucas, Müller and Henle 1839, and the largetooth sawfish Pristis pristis, Linnaeus 1758) support this hypothesis, showing similar liver sizes as marine forms but lower liver densities, but the greatest negative buoyancies of any elasmobranch studied to date. Our data suggest that the mechanical challenges associated with buoyancy control may have hampered the invasion of freshwater habitats in elasmobranchs, highlighting an additional key factor that may govern the predisposition of marine organisms to successfully establish in freshwater habitats. © 2015. Published by The Company of Biologists Ltd.

  2. Chesapeake Bay Low Freshwater Inflow Study. Appendix E. Biota.

    Science.gov (United States)

    1984-09-01

    selecting representative species for study, mapping potential habitat under various conditions, using expert scientists to interpret the significance of...8217 t " TH H P CHESAPEAKE BAYE Ec LOW FRESHWATER INFLOW STUDY . htp APPENDIX E . . BIOTA TABLE OF ONTENTS...intensive manual searches of journals and other sources. Five abstract services were searched under more than 14 topics each. Journals, reports to

  3. Cultivation of macroscopic marine algae and freshwater aquatic weeds. Progress report, May 1--December 31, 1976

    Energy Technology Data Exchange (ETDEWEB)

    Ryther, J. H.

    1977-01-01

    Research was divided between basic physiological studies of the growth and nutrient-uptake kinetics of macroscopic marine algae and the more applied problems involved in the selection of species and the development of inexpensive, non-energy intensive culture methods for growing seaweeds and freshwater plants as a biomass source for conversion to energy. Best growth of the seaweeds occurs at low (0.1 to 1.0 ..mu..molar) concentration of major nutrients, with ammonia as a nitrogen source, with rapid exchange of the culture medium (residence time of 0.05 days or less). Of 43 species of seaweeds evaluated, representatives of the large red alga genus Gracilaria appear most promising with potential yields, in a highly intensive culture system under optimal conditions, of some 129 metric dry tons per hectare per year (about half of which is organic). Non-intensive culture methods have yielded one-third to one-half that figure. Unexplained periodicity of growth and overgrowth by epiphytes remain the most critical constraint to large-scale seaweed culture. Freshwater weed species in culture include water hyacinth (Eichhornia crassipes), duckweed (Lemna minor), and Hydrilla vertecillata, with yields to date averaging 15, 4, and 8 g dry wt/m/sup 2//day, respectively. However, these plants have not yet been grown through the winter, so average annual yields are expected to be lower. In contrast to the seaweeds, the freshwater plants grow well at high nutrient concentrations and slow culture volume exchange rates (residence time ca. 20 days or more). Experiments were initiated on the recycling of digester residues from the fermentation of the freshwater and marine plants as a possible nutrient source for growth of the same species.

  4. Fatty acid amides from freshwater green alga Rhizoclonium hieroglyphicum.

    Science.gov (United States)

    Dembitsky, V M; Shkrob, I; Rozentsvet, O A

    2000-08-01

    Freshwater green algae Rhizoclonium hieroglyphicum growing in the Ural Mountains were examined for their fatty acid amides using capillary gas chromatography-mass spectrometry (GC-MS). Eight fatty acid amides were identified by GC-MS. (Z)-9-octadecenamide was found to be the major component (2.26%).

  5. Desalination - an alternative freshwater resource

    International Nuclear Information System (INIS)

    Shakaib, M.

    2005-01-01

    Global water constitutes 94 percent salt water that is from the oceans and 6% is in the form of freshwater. Out of this 6% freshwater approximately 27% is trapped in glaciers and 72% is underground. The sea water is important for transportation, fisheries. Oceans regulate climate through air sea interaction. However direct consumption of sea water is too salty to sustain human life. Water with a dissolved solids (salt) content generally below about 1000 milligrams per liter (mg/L) is considered acceptable for human consumption. The application of desalting technologies over the past 50 years have been in many of the arid zone where freshwater is available. Pakistan lies in the Sun Belt. It is considered a wide margin coastal belt (990 km), having an Exclusive Economic Zone of 240,000 km/sup 2/, that strokes trillion cubic meters of sea water that can be made available as freshwater source to meet the shortfall in the supply of domestic water through desalination along the coastal belt of Pakistan. The freshwater obtained from the other desalination processes is slightly expensive, but the cost of desalination can be considerably reduced provided that the available inexpensive or free waste energy is utilized mainly. (author)

  6. Assessing climate change impacts, benefits of mitigation, and uncertainties on major global forest regions under multiple socioeconomic and emissions scenarios

    Science.gov (United States)

    John B Kim; Erwan Monier; Brent Sohngen; G Stephen Pitts; Ray Drapek; James McFarland; Sara Ohrel; Jefferson Cole

    2016-01-01

    We analyze a set of simulations to assess the impact of climate change on global forests where MC2 dynamic global vegetation model (DGVM) was run with climate simulations from the MIT Integrated Global System Model-Community Atmosphere Model (IGSM-CAM) modeling framework. The core study relies on an ensemble of climate simulations under two emissions scenarios: a...

  7. New Zealand Freshwater Management: Changing Policy for a Changing World

    Science.gov (United States)

    Rouse, H. L.; Norton, N.

    2014-12-01

    Fresh water is essential to New Zealand's economic, environmental, cultural and social well-being. In line with global trends, New Zealand's freshwater resources are under pressure from increased abstraction and changes in land-use which contribute contaminants to our freshwater systems. Recent central government policy reform introduces greater national direction and guidance, to bring about a step-change in freshwater management. An existing national policy for freshwater management introduced in 2011 requires regional authorities to produce freshwater management plans containing clear freshwater objectives (measurable statements about the desired environmental state for water bodies) and associated limits to resource use (such as environmental flows and quantity allocation limits, and loads of contaminants to be discharged). These plans must integrate water quantity and quality management, consider climate change, and incorporate tangata whenua (New Zealand māori) roles and interests. In recent (2014) national policy amendments, the regional authorities are also required to implement national 'bottom-line' standards for certain attributes of the system to be managed; undertake accounting for all water takes and all sources of contaminants; and to develop and implement their plans in a collaborative way with communities. This rapid change in national policy has necessitated a new way of working for authorities tasked with implementation; many obstacles lie in their path. The scientific methods required to help set water quantity limits are well established, but water quality methods are less so. Collaborative processes have well documented benefits but also raise many challenges, particularly for the communication of complex and often uncertain scientific information. This paper provides background on the national policy changes and offers some early lessons learned by the regional authorities implementing collaborative freshwater management in New Zealand.

  8. Shell's Role in the Future European Gas Scene - Is a Major Market Restructuring Under Way?

    Energy Technology Data Exchange (ETDEWEB)

    Segundo, Karen de

    1999-07-01

    The European gas market is being restructured by a combination of major global forces. Environmental considerations like the Kyoto Agreement favour the use of gas. But in the medium-term, supplies may be limited by low energy prices. The political drive for increased competition has manifested itself as the EU Gas Directive, which came into force in 1998. Shell believes that the European industry must progressively adapt to this restructuring. Flexible mechanisms like tradable emission permits should be used to generate investment capital for new gas supply projects. Moreover, both industry and regulators should take a positive and constructive approach towards increasing competition in the marketplace.

  9. Phytoplankton succession in a tropical freshwater lake, Bhoj Wetland (Bhopal, India): spatial and temporal perspective

    Digital Repository Service at National Institute of Oceanography (India)

    Ahmed, A.; Wangane, A.

    Bhoj Wetland is tropical freshwater system in central India �Bhopal� serving the citizens as one of the major source of water since its inception Understanding the process of phytoplankton variation can be particularly useful in water quality...

  10. Vulnerability of European freshwater catchments to climate change.

    Science.gov (United States)

    Markovic, Danijela; Carrizo, Savrina F; Kärcher, Oskar; Walz, Ariane; David, Jonathan N W

    2017-09-01

    Climate change is expected to exacerbate the current threats to freshwater ecosystems, yet multifaceted studies on the potential impacts of climate change on freshwater biodiversity at scales that inform management planning are lacking. The aim of this study was to fill this void through the development of a novel framework for assessing climate change vulnerability tailored to freshwater ecosystems. The three dimensions of climate change vulnerability are as follows: (i) exposure to climate change, (ii) sensitivity to altered environmental conditions and (iii) resilience potential. Our vulnerability framework includes 1685 freshwater species of plants, fishes, molluscs, odonates, amphibians, crayfish and turtles alongside key features within and between catchments, such as topography and connectivity. Several methodologies were used to combine these dimensions across a variety of future climate change models and scenarios. The resulting indices were overlaid to assess the vulnerability of European freshwater ecosystems at the catchment scale (18 783 catchments). The Balkan Lakes Ohrid and Prespa and Mediterranean islands emerge as most vulnerable to climate change. For the 2030s, we showed a consensus among the applied methods whereby up to 573 lake and river catchments are highly vulnerable to climate change. The anthropogenic disruption of hydrological habitat connectivity by dams is the major factor reducing climate change resilience. A gap analysis demonstrated that the current European protected area network covers climate change. Priority should be placed on enhancing stakeholder cooperation at the major basin scale towards preventing further degradation of freshwater ecosystems and maintaining connectivity among catchments. The catchments identified as most vulnerable to climate change provide preliminary targets for development of climate change conservation management and mitigation strategies. © 2017 John Wiley & Sons Ltd.

  11. Low dose of caffeine enhances the efficacy of antidepressants in major depressive disorder and the underlying neural substrates.

    Science.gov (United States)

    Liu, Qing-Shan; Deng, Ran; Fan, Yuyan; Li, Keqin; Meng, Fangang; Li, Xueli; Liu, Rui

    2017-08-01

    Caffeine is one of the most frequently used psychoactive substances ingested mainly via beverage or food products. Major depressive disorder is a serious and devastating psychiatric disorder. Emerging evidence indicates that caffeine enhances the antidepressant-like activity of common antidepressant drugs in rodents. However, whether joint administration of low dose of caffeine enhances the antidepressant actions in depressed patients remains unclear. A total of 95 male inpatients were assigned to three groups and were asked to take either caffeine (60, 120 mg) or placebo (soymilk powder) daily for 4 wk on the basis of their current antidepressant medications. Results showed that chronic supplementation with low dose of caffeine (60 mg) produced rapid antidepressant action by reduction of depressive scores. Furthermore, low dose of caffeine improved cognitive performance in depressed patients. However, caffeine did not affect sleep as measured by overnight polysomnography. Moreover, chronic caffeine consumption elicited inhibition of hypothalamic-pituitary-adrenal axis activation by normalization of salivary cortisol induced by Trier social stress test. These findings indicated the potential benefits of further implications of supplementary administration of caffeine to reverse the development of depression and enhance the outcome of antidepressants treatment in major depressive disorder. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Mechanisms underlying major investment projects in the Romanian public administration: strong and long term collaboration among stakeholders

    Directory of Open Access Journals (Sweden)

    Tănăsescu Laurian Gabriel

    2017-07-01

    Full Text Available Starting from the existing situation, in order to understand the mechanisms underlying investment projects financed from public funds in Romania, we analysed the following public sources of information: For projects implemented before 2007, we analysed data available on the Internet, including databases of international donors such as www.dgmarket.com, http://www.ted.europa.eu/, etc. We analysed data made available by the Public Procurement Electronic System through the portal http://data.gov.ro. The data set analysed includes over 8 million awarding contract notices. For the EU funded projects, we requested the Ministry of European Funds to offer us access to the relevant database (SMIS, which includes all the projects financed under the European funding programme 2007 – 2013 (projects implemented before 31.12.2015. Comparing data from all these sources leads to the conclusion that the information is coherent and represents a credible basis for our analysis. We found that 48% of all investment projects implemented in Romania in 2007 – 2016 and co-funded under European funds (in terms of the share of eligible expenses requested outsourcing services for the preparation of the project documentation needed to apply for funds; such expenses represent almost 3 % of the total eligible project expenses approved. Almost 36% (in terms of the share of eligible expenses of all investment projects implemented in Romania in 2007 – 2016 and co-funded under European funds, revealed a strong and long term relationship between the company that participates in the elaboration of the grant application and the beneficiary of funds. This collaboration continued throughout the implementation of the project. These companies delivered services / supplied goods / carried out construction works whose value exceeds 15 billion lei, which represents over 54% of the total eligible costs of the respective projects.

  13. Review: Freshwater conservation planning in South Africa ...

    African Journals Online (AJOL)

    Review: Freshwater conservation planning in South Africa: Milestones to ... Water SA. Journal Home · ABOUT THIS JOURNAL · Advanced Search ... Since the 1970s, at approximately 10-year intervals, 4 national-scale freshwater conservation ...

  14. Native Freshwater Fish and Mussel Species Richness

    Data.gov (United States)

    U.S. Environmental Protection Agency — These data represent predicted current distributions of all native freshwater fish and freshwater mussels in the Middle-Atlantic region. The data are available for...

  15. Bistability of mangrove forests and competition with freshwater plants

    Science.gov (United States)

    Jiang, Jiang; Fuller, Douglas O; Teh, Su Yean; Zhai, Lu; Koh, Hock Lye; DeAngelis, Donald L.; Sternberg, L.D.S.L.

    2015-01-01

    Halophytic communities such as mangrove forests and buttonwood hammocks tend to border freshwater plant communities as sharp ecotones. Most studies attribute this purely to underlying physical templates, such as groundwater salinity gradients caused by tidal flux and topography. However, a few recent studies hypothesize that self-reinforcing feedback between vegetation and vadose zone salinity are also involved and create a bistable situation in which either halophytic dominated habitat or freshwater plant communities may dominate as alternative stable states. Here, we revisit the bistability hypothesis and demonstrate the mechanisms that result in bistability. We demonstrate with remote sensing imagery the sharp boundaries between freshwater hardwood hammock communities in southern Florida and halophytic communities such as buttonwood hammocks and mangroves. We further document from the literature how transpiration of mangroves and freshwater plants respond differently to vadose zone salinity, thus altering the salinity through feedback. Using mathematical models, we show how the self-reinforcing feedback, together with physical template, controls the ecotones between halophytic and freshwater communities. Regions of bistability along environmental gradients of salinity have the potential for large-scale vegetation shifts following pulse disturbances such as hurricane tidal surges in Florida, or tsunamis in other regions. The size of the region of bistability can be large for low-lying coastal habitat due to the saline water table, which extends inland due to salinity intrusion. We suggest coupling ecological and hydrologic processes as a framework for future studies.

  16. Inhabitants of the Fresh-Water Community.

    Science.gov (United States)

    Jorgensen, Joseph; Schroeder, Marlene

    This learner's guide is designed to assist middle school students in studying freshwater organisms. Following a brief introduction to freshwater ecology, simple line drawings facilitate the identification of plants and animals common to Florida's freshwater ecosystems. Emphasis of the short text which accompanies each illustration is upon the…

  17. Morphological alteration, lysosomal membrane fragility and apoptosis of the cells of Indian freshwater sponge exposed to washing soda (sodium carbonate).

    Science.gov (United States)

    Mukherjee, Soumalya; Ray, Mitali; Dutta, Manab Kumar; Acharya, Avanti; Mukhopadhyay, Sandip Kumar; Ray, Sajal

    2015-12-01

    Washing soda is chemically known as sodium carbonate and is a component of laundry detergent. Domestic effluent, drain water and various anthropogenic activities have been identified as major routes of sodium carbonate contamination of the freshwater ecosystem. The freshwater sponge, Eunapius carteri, bears ecological and evolutionary significance and is considered as a bioresource in aquatic ecosystems. The present study involves estimation of morphological damage, lysosomal membrane integrity, activity of phosphatases and apoptosis in the cells of E. carteri under the environmentally realistic concentrations of washing soda. Exposure to washing soda resulted in severe morphological alterations and damages in cells of E. carteri. Fragility and destabilization of lysosomal membranes of E. carteri under the sublethal exposure was indicative to toxin induced physiological stress in sponge. Prolonged exposure to sodium carbonate resulted a reduction in the activity of acid and alkaline phosphatases in the cells of E. carteri. Experimental concentration of 8 mg/l of washing soda for 192 h yielded an increase in the physiological level of cellular apoptosis among the semigranulocytes and granulocytes of E. carteri, which was suggestive to possible shift in apoptosis mediated immunoprotection. The results were indicative of an undesirable shift in the immune status of sponge. Contamination of the freshwater aquifers by washing soda thus poses an alarming ecotoxicological threat to sponges. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. The mammary gland in small ruminants: major morphological and functional events underlying milk production – a review

    DEFF Research Database (Denmark)

    Lérias, Joana R; Hernandez Castellano, Lorenzo E; Suárez-Trujillo, Aridany

    2014-01-01

    the modifications occurring in the mammary gland through the lactation period in production animals, particularly in the small ruminants, sheep (Ovis aries) and goat (Capra hircus). Nevertheless, understanding the different mammary gland patterns throughout lactation is essential to improve dairy production......, as well as a reduction of stroma, corresponding macroscopically to the increase in mammary gland volume. Throughout late lactation, the mammary gland volume decreases owing to the regression of the secretory structure. In general, common mammary gland patterns have been shown for both goats and sheep...... throughout the several lactation stages, although the number of studies is limited. The main objective of this manuscript is to review the colostrogenesis and lactogenesis processes as well as to highlight the mammary gland morphological patterns underlying milk production during the lactation cycle...

  19. Assessing climate change impacts, benefits of mitigation, and uncertainties on major global forest regions under multiple socioeconomic and emissions scenarios

    Science.gov (United States)

    Kim, John B.; Monier, Erwan; Sohngen, Brent; Pitts, G. Stephen; Drapek, Ray; McFarland, James; Ohrel, Sara; Cole, Jefferson

    2017-04-01

    We analyze a set of simulations to assess the impact of climate change on global forests where MC2 dynamic global vegetation model (DGVM) was run with climate simulations from the MIT Integrated Global System Model-Community Atmosphere Model (IGSM-CAM) modeling framework. The core study relies on an ensemble of climate simulations under two emissions scenarios: a business-as-usual reference scenario (REF) analogous to the IPCC RCP8.5 scenario, and a greenhouse gas mitigation scenario, called POL3.7, which is in between the IPCC RCP2.6 and RCP4.5 scenarios, and is consistent with a 2 °C global mean warming from pre-industrial by 2100. Evaluating the outcomes of both climate change scenarios in the MC2 model shows that the carbon stocks of most forests around the world increased, with the greatest gains in tropical forest regions. Temperate forest regions are projected to see strong increases in productivity offset by carbon loss to fire. The greatest cost of mitigation in terms of effects on forest carbon stocks are projected to be borne by regions in the southern hemisphere. We compare three sources of uncertainty in climate change impacts on the world’s forests: emissions scenarios, the global system climate response (i.e. climate sensitivity), and natural variability. The role of natural variability on changes in forest carbon and net primary productivity (NPP) is small, but it is substantial for impacts of wildfire. Forest productivity under the REF scenario benefits substantially from the CO2 fertilization effect and that higher warming alone does not necessarily increase global forest carbon levels. Our analysis underlines why using an ensemble of climate simulations is necessary to derive robust estimates of the benefits of greenhouse gas mitigation. It also demonstrates that constraining estimates of climate sensitivity and advancing our understanding of CO2 fertilization effects may considerably reduce the range of projections.

  20. Hair and stress: A pilot study of hair and cytokine balance alteration in healthy young women under major exam stress.

    Directory of Open Access Journals (Sweden)

    Eva M J Peters

    Full Text Available Mouse models show that experimental stress mimicking prolonged life-stress exposure enhances neurogenic inflammation, induces adaptive immunity cytokine-imbalance characterized by a shift to Type 1 T-helper cell cytokines and increases apoptosis of epithelial cells. This affects hair growth in otherwise healthy animals. In this study, we investigate whether a prolonged naturalistic life-stress exposure affects cytokine balance and hair parameters in healthy humans. 33 (18 exam, 15 comparison female medical students with comparable sociobiological status were analyzed during a stressful final examination period, at three points in time (T 12 weeks apart. T1 was before start of the learning period, T2 between the three-day written exam and an oral examination, and T3 after a 12 week rest and recovery from the stress of the examination period. Assessments included: self-reported distress and coping strategies (Perceived Stress Questionnaire [PSQ], Trier Inventory for the Assessment of Chronic Stress [TICS], COPE, cytokines in supernatants of stimulated peripheral blood mononucleocytes (PBMCs, and trichogram (hair cycle and pigmentation analysis. Comparison between students participating in the final medical exam at T2 and non-exam students, revealed significantly higher stress perception in exam students. Time-wise comparison revealed that stress level, TH1/TH2 cytokine balance and hair parameters changed significantly from T1 to T2 in the exam group, but not the control. However, no group differences were found for cytokine balance or hair parameters at T2. The study concludes that in humans, naturalistic stress, as perceived during participation in a major medical exam, has the potential to shift the immune response to TH1 and transiently hamper hair growth, but these changes stay within a physiological range. Findings are instructive for patients suffering from hair loss in times of high stress. Replication in larger and more diverse sample

  1. MAJOR DEPRESSIVE DISORDER WITHOUT PSYCHOTIC SYMPTOMS IN CHILDREN UNDER THE AGE OF 14 YEAR-OLD RAPE VICTIM.

    Directory of Open Access Journals (Sweden)

    Andika Metrisiawan

    2014-02-01

    Full Text Available Depression is a very large impact on the global disease that affects people worldwide.Lately, an estimated 350 million people suffering from depression. The World MentalHealth Survey in 17 countries stated that 1 in 20 people who reported experiencing adepressive episode in the last 1 year. Depressive disorders often appear early in life andcauses a decrease in a person's interest and often recurrent. For this reason it is said thatdepression is the leading cause of disability in relation to total annual loss due to disability.Therapy should be given a basic psychosocial support combined with antidepressantmedication or psychotherapy such as cognitive behavioral therapy, interpersonal psychotherapy or problem-solving treatment. This case report discusses the severe depression without psychotic symptoms in children under the age of 14 year-old rapevictim. In addition to the victim made an approach to the development of psychological 1 therapy is also given in the form of Psychotherapy and Pharmacotherapy ie 1 x 20 mgfluoxetine oral and Benzodiazepine 1 x 10 mg orally. 

  2. Climate change impact and potential adaptation strategies under alternate realizations of climate scenarios for three major crops in Europe

    Science.gov (United States)

    Donatelli, Marcello; Srivastava, Amit Kumar; Duveiller, Gregory; Niemeyer, Stefan; Fumagalli, Davide

    2015-07-01

    This study presents an estimate of the effects of climate variables and CO2 on three major crops, namely wheat, rapeseed and sunflower, in EU27 Member States. We also investigated some technical adaptation options which could offset climate change impacts. The time-slices 2000, 2020 and 2030 were chosen to represent the baseline and future climate, respectively. Furthermore, two realizations within the A1B emission scenario proposed by the Special Report on Emissions Scenarios (SRES), from the ECHAM5 and HadCM3 GCM, were selected. A time series of 30 years for each GCM and time slice were used as input weather data for simulation. The time series were generated with a stochastic weather generator trained over GCM-RCM time series (downscaled simulations from the ENSEMBLES project which were statistically bias-corrected prior to the use of the weather generator). GCM-RCM simulations differed primarily for rainfall patterns across Europe, whereas the temperature increase was similar in the time horizons considered. Simulations based on the model CropSyst v. 3 were used to estimate crop responses; CropSyst was re-implemented in the modelling framework BioMA. The results presented in this paper refer to abstraction of crop growth with respect to its production system, and consider growth as limited by weather and soil water. How crop growth responds to CO2 concentrations; pests, diseases, and nutrients limitations were not accounted for in simulations. The results show primarily that different realization of the emission scenario lead to noticeably different crop performance projections in the same time slice. Simple adaptation techniques such as changing sowing dates and the use of different varieties, the latter in terms of duration of the crop cycle, may be effective in alleviating the adverse effects of climate change in most areas, although response to best adaptation (within the techniques tested) differed across crops. Although a negative impact of climate

  3. Climate change impact and potential adaptation strategies under alternate realizations of climate scenarios for three major crops in Europe

    International Nuclear Information System (INIS)

    Donatelli, Marcello; Srivastava, Amit Kumar; Duveiller, Gregory; Niemeyer, Stefan; Fumagalli, Davide

    2015-01-01

    This study presents an estimate of the effects of climate variables and CO 2 on three major crops, namely wheat, rapeseed and sunflower, in EU27 Member States. We also investigated some technical adaptation options which could offset climate change impacts. The time-slices 2000, 2020 and 2030 were chosen to represent the baseline and future climate, respectively. Furthermore, two realizations within the A1B emission scenario proposed by the Special Report on Emissions Scenarios (SRES), from the ECHAM5 and HadCM3 GCM, were selected. A time series of 30 years for each GCM and time slice were used as input weather data for simulation. The time series were generated with a stochastic weather generator trained over GCM-RCM time series (downscaled simulations from the ENSEMBLES project which were statistically bias-corrected prior to the use of the weather generator). GCM-RCM simulations differed primarily for rainfall patterns across Europe, whereas the temperature increase was similar in the time horizons considered. Simulations based on the model CropSyst v. 3 were used to estimate crop responses; CropSyst was re-implemented in the modelling framework BioMA. The results presented in this paper refer to abstraction of crop growth with respect to its production system, and consider growth as limited by weather and soil water. How crop growth responds to CO 2 concentrations; pests, diseases, and nutrients limitations were not accounted for in simulations. The results show primarily that different realization of the emission scenario lead to noticeably different crop performance projections in the same time slice. Simple adaptation techniques such as changing sowing dates and the use of different varieties, the latter in terms of duration of the crop cycle, may be effective in alleviating the adverse effects of climate change in most areas, although response to best adaptation (within the techniques tested) differed across crops. Although a negative impact of climate

  4. Major health problems and their economic impact on beef cattle under two different feedlot systems in Brazil

    Directory of Open Access Journals (Sweden)

    Pedro Malafaia

    Full Text Available Abstract: This study aimed to describe the diagnosis of health problems and to evaluate the cost of their treatment for cattle raised in feedlots to be slaughtered or to be sold as sires for cow-calf systems. Bovine respiratory disease and digestive disorders were the main problems diagnosed in the feedlot for slaughter; the cost for treatment was high, accounting for 9.7 to 20.9 kg of live weight (LW or the equivalent of 7 to 15% of total LW gained over the days on feed. Due to the high intake of starch-rich concentrate, rumen and fecal pH was lower, whilst rumen osmolarity and blood lactate were higher in cattle fed for slaughter. Cattle affected by digestive disorders spent on average four additional days in the feedlot. Diseases and cost of treatments were associated with lower average daily gain and considerable economic losses. Health problems commonly observed in the feedlots for slaughter were not observed in the feedlots for males to be sold as sires. The most likely reason for this observation was the more careful nutrition and prophylactic health management in sire production systems, which produce animals of much higher selling price. Results from this study suggest that health problems found in feedlots for slaughter may not only reduce animal productivity and profitability, but also the welfare of the animals. The systemic understaffing of livestock cattle workers and veterinarians in large feedlots in Brazil results in under reporting of diseases and lack to understand epidemiological context and disease prevention.

  5. Fish and mussels: importance of fish for freshwater mussel conservation

    Directory of Open Access Journals (Sweden)

    Ronaldo Sousa

    2015-12-01

    Full Text Available Co-extinctions have received trivial consideration in discussions about the global conservation crisis, even though recent studies have emphasised their importance. This situation is even more pronounced in freshwater ecosystems where this phenomenon is largely unrecognized. In this presentation we explore the role of fish for freshwater mussels’ conservation. Freshwater mussels’ need fish as a host to complete their life cycle and given this premise is expected that changes in the fish community due to species extinctions or additions may have great effects. We reviewed the published information and we found: 1 that most of the studies were published in the last few years; 2 that most of the studies were performed in North America (69%, which is probably due to the high number of endemic threatened species in this continent; 3 that most of the mussel species that are specialists in fish hosting are listed as vulnerable or endangered (55%; 4 most studies were performed in laboratory (83% and 5 that the majority of studies were focused on life cycle or on identifying suitable fish hosts of freshwater mussel species with few studies focusing on threats. Since the interaction between fish and freshwater mussels can be easily disrupted and serious threats to this interaction have arisen (e.g. loss and fragmentation of habitat, changes in river flow, climate change, introduction of invasive species, pollution a more holistic approach is needed to find the best management strategies to conserve these animals. In addition, more field studies are required and more information on African, South American and Asian species is essential. Neglect the possible fundamental role of fish in the decline or extinction of freshwater mussels may impair the success of any measure devoted to their conservation; therefore, this issue cannot be ignored.

  6. Reclaiming freshwater sustainability in the Cadillac Desert

    Science.gov (United States)

    Sabo, John L.; Sinha, Tushar; Bowling, Laura C.; Schoups, Gerrit H.W.; Wallender, Wesley W.; Campana, Michael E.; Cherkauer, Keith A.; Fuller, Pam L.; Graf, William L.; Hopmans, Jan W.; Kominoski, John S.; Taylor, Carissa; Trimble, Stanley W.; Webb, Robert H.; Wohl, Ellen E.

    2010-01-01

    Increasing human appropriation of freshwater resources presents a tangible limit to the sustainability of cities, agriculture, and ecosystems in the western United States. Marc Reisner tackles this theme in his 1986 classic Cadillac Desert: The American West and Its Disappearing Water. Reisner's analysis paints a portrait of region-wide hydrologic dysfunction in the western United States, suggesting that the storage capacity of reservoirs will be impaired by sediment infilling, croplands will be rendered infertile by salt, and water scarcity will pit growing desert cities against agribusiness in the face of dwindling water resources. Here we evaluate these claims using the best available data and scientific tools. Our analysis provides strong scientific support for many of Reisner's claims, except the notion that reservoir storage is imminently threatened by sediment. More broadly, we estimate that the equivalent of nearly 76% of streamflow in the Cadillac Desert region is currently appropriated by humans, and this figure could rise to nearly 86% under a doubling of the region's population. Thus, Reisner's incisive journalism led him to the same conclusions as those rendered by copious data, modern scientific tools, and the application of a more genuine scientific method. We close with a prospectus for reclaiming freshwater sustainability in the Cadillac Desert, including a suite of recommendations for reducing region-wide human appropriation of streamflow to a target level of 60%.

  7. Changes of freshwater-lens thickness in basaltic island aquifers overlain by thick coastal sediments

    Science.gov (United States)

    Rotzoll, Kolja; Oki, Delwyn S.; El-Kadi, Aly I.

    2010-01-01

    Freshwater-lens thickness and long-term changes in freshwater volume in coastal aquifers are commonly assessed through repeated measurement of salinity profiles from monitor wells that penetrate into underlying salt water. In Hawaii, the thickest measured freshwater lens is currently 262 m in dike-free, volcanic-rock aquifers that are overlain by thick coastal sediments. The midpoint depth (depth where salinity is 50% salt water) between freshwater and salt water can serve as an indicator for freshwater thickness. Most measured midpoints have risen over the past 40 years, indicating a shrinking lens. The mean rate of rise of the midpoint from 1999–2009 varied locally, with faster rates in highly developed areas (1.0 m/year) and slower rates in less developed areas (0.5 m/year). The thinning of the freshwater lenses is the result of long-term groundwater withdrawal and reduced recharge. Freshwater/salt-water interface locations predicted from measured water levels and the Ghyben-Herzberg principle may be deeper than measured midpoints during some periods and shallower during other periods, although depths may differ up to 100 m in some cases. Moreover, changes in the midpoint are slower than changes in water level. Thus, water levels may not be a reliable indicator of the amount of freshwater in a coastal aquifer.

  8. Freshwater algae of the Nevada Test Site

    International Nuclear Information System (INIS)

    Taylor, W.D.; Giles, K.R.

    1979-06-01

    Fifty-two species of freshwater algae were identified in samples collected from the eight known natural springs of the Nevada Test Site. Although several species were widespread, 29 species were site specific. Diatoms provided the greatest variety of species at each spring. Three-fifths of all algal species encountered were diatoms. Well-developed mats of filamentous green algae (Chlorophyta) were common in many of the water tanks associated with the springs and accounted for most of the algal biomass. Major nutrients were adequate, if not abundant, in most spring waters - growth being limited primarily by light and physical habitat. There was some evidence of cesium-137 bioconcentration by algae at several of the springs

  9. Cable Bacteria in Freshwater Sediments

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Kristiansen, Michael; Frederiksen, Rasmus

    2015-01-01

    In marine sediments cathodic oxygen reduction at the sediment surface can be coupled to anodic sulfide oxidation in deeper anoxic layers through electrical currents mediated by filamentous, multicellular bacteria of the Desulfobulbaceae family, the so-called cable bacteria. Until now, cable...... bacteria have only been reported from marine environments. In this study, we demonstrate that cable bacteria also occur in freshwater sediments. In a first step, homogenized sediment collected from the freshwater stream Giber Å, Denmark, was incubated in the laboratory. After 2 weeks, pH signatures...... marine cable bacteria, with the genus Desulfobulbus as the closest cultured lineage. The results of the present study indicate that electric currents mediated by cable bacteria could be important for the biogeochemistry in many more environments than anticipated thus far and suggest a common evolutionary...

  10. Alien species recorded in the United Arab Emirates: an initial list of terrestrial and freshwater species

    Directory of Open Access Journals (Sweden)

    Pritpal Soorae

    2015-10-01

    Full Text Available Little is documented on the alien terrestrial and freshwater species in the United Arab Emirates. To address this, an assessment of terrestrial and freshwater alien species was conducted using various techniques such as a questionnaire, fieldwork data, networking with relevant people, and a detailed literature review. The results of the initial assessment show that there are 146 alien species recorded in the following seven major taxonomic groups: invertebrates 49 species, freshwater fish five species, amphibian one species, reptiles six species, birds 71 species, mammals six species and plants eight species. To inform decision makers a full list of the 146 species identified in this assessment is presented. 

  11. Endosulfan and its metabolite, endosulfan sulfate, in freshwater ecosystems of South Florida: a probabilistic aquatic ecological risk assessment.

    Science.gov (United States)

    Rand, Gary M; Carriger, John F; Gardinali, Piero R; Castro, Joffre

    2010-06-01

    Endosulfan is an insecticide-acaricide used in South Florida and is one of the remaining organochlorine insecticides registered under the Federal Insecticide Fungicide and Rodenticide Act by the U.S.EPA. The technical grade material consists of two isomers (alpha-, beta-) and the main environmental metabolite in water, sediment and tissue is endosulfan sulfate through oxidation. A comprehensive probabilistic aquatic ecological risk assessment was conducted to determine the potential risks of existing exposures to endosulfan and endosulfan sulfate in freshwaters of South Florida based on historical data (1992-2007). The assessment included hazard assessment (Tier 1) followed by probabilistic risk assessment (Tier 2). Tier 1 compared actual measured concentrations in surface freshwaters of 47 sites in South Florida from historical data to U.S.EPA numerical water quality criteria. Based on results of Tier 1, Tier 2 focused on the acute and chronic risks of endosulfan at nine sites by comparing distributions of surface water exposure concentrations of endosulfan [i.e., for total endosulfan (summation of concentrations of alpha- and beta-isomers plus the sulfate), alpha- plus beta-endosulfan, and endosulfan sulfate (alone)] with distributions of species effects from laboratory toxicity data. In Tier 2 the distribution of total endosulfan in fish tissue (whole body) from South Florida freshwaters was also used to determine the probability of exceeding a distribution of whole body residues of endosulfan producing mortality (critical lethal residues). Tier 1 showed the majority of endosulfan water quality violations in South Florida were at locations S-178 followed by S-177 in the C-111 system (southeastern boundary of Everglades National Park (ENP)). Nine surface water sampling sites were chosen for Tier 2. Tier 2 showed the highest potentially affected fraction of toxicity values (>10%) by the estimated 90th centile exposure concentration (total endosulfan) was at S-178

  12. DISTRIBUTION OF HEAVY METALS AMONG THE COMPONENTS OF FRESHWATER ECOSYSTEMS (REVIEW)

    OpenAIRE

    N. Kolesnyk

    2014-01-01

    Purpose. To review scientific sources on the distribution of heavy metals among the components of freshwater ecosystems. Findings. The review of the works of many scientists showed that heavy metals are widespread in the biotic and abiotic components of freshwater ecosystems. The article highlights the distribution of heavy metals in water, bottom sediments, natural food base, fish organs and tissues. It has been shown that as a result of global pollution of the ecosystem, the majority of...

  13. Impact of Population Growth and Climate Change on the Freshwater Resources of Lamu Island, Kenya

    Directory of Open Access Journals (Sweden)

    Cornelius Okello

    2015-03-01

    Full Text Available Demand for freshwater is rising with factors, such as population growth, land use change and climate variations, rendering water availability in the future uncertain. Groundwater resources are being increasingly exploited to meet this growing demand. The aim of this study is to identify the influence of population growth induced by land use change and climate change on the future state of freshwater resources of Lamu Island in Kenya where a major port facility is under construction. The results of this study show that the “no industrial development” population scenario (assuming the port was not constructed would be expected to reach ~50,000 people by 2050, while the projected population upon completion is expected to reach 1.25 million in the same year when the Lamu Port-South Sudan-Ethiopia Transport Corridor Program (LAPSSET port reaches its full cargo-handling capacity. The groundwater abstraction in 2009 was 0.06 m3 daily per capita, while the demand is expected to raise to 0.1 m3 by 2050 according to the “LAPSSET development” projection. The modelling results show that the Shela aquifer in Lamu, which is the main source of water on the island, will not experience stress by 2065 for the “no industrial development” population scenario, whereas for the “LAPSSET development projection” population scenario, it will occur sooner (between 2020 and 2028. The modelling results show that the Representative Concentration Pathways (RCP climate change scenarios will have a smaller impact on the effective water volume reserves than Special Report on Emissions Scenarios (SRES for the “no industrial development”, while the impact is expected to be similar for the “LAPSSET development”, suggesting that population growth exacerbated by land use change will be a more significant driving force than climate change in affecting freshwater availability.

  14. Freshwater salinization syndrome on a continental scale.

    Science.gov (United States)

    Kaushal, Sujay S; Likens, Gene E; Pace, Michael L; Utz, Ryan M; Haq, Shahan; Gorman, Julia; Grese, Melissa

    2018-01-23

    Salt pollution and human-accelerated weathering are shifting the chemical composition of major ions in fresh water and increasing salinization and alkalinization across North America. We propose a concept, the freshwater salinization syndrome, which links salinization and alkalinization processes. This syndrome manifests as concurrent trends in specific conductance, pH, alkalinity, and base cations. Although individual trends can vary in strength, changes in salinization and alkalinization have affected 37% and 90%, respectively, of the drainage area of the contiguous United States over the past century. Across 232 United States Geological Survey (USGS) monitoring sites, 66% of stream and river sites showed a statistical increase in pH, which often began decades before acid rain regulations. The syndrome is most prominent in the densely populated eastern and midwestern United States, where salinity and alkalinity have increased most rapidly. The syndrome is caused by salt pollution (e.g., road deicers, irrigation runoff, sewage, potash), accelerated weathering and soil cation exchange, mining and resource extraction, and the presence of easily weathered minerals used in agriculture (lime) and urbanization (concrete). Increasing salts with strong bases and carbonates elevate acid neutralizing capacity and pH, and increasing sodium from salt pollution eventually displaces base cations on soil exchange sites, which further increases pH and alkalinization. Symptoms of the syndrome can include: infrastructure corrosion, contaminant mobilization, and variations in coastal ocean acidification caused by increasingly alkaline river inputs. Unless regulated and managed, the freshwater salinization syndrome can have significant impacts on ecosystem services such as safe drinking water, contaminant retention, and biodiversity. Copyright © 2018 the Author(s). Published by PNAS.

  15. Effect of sustainability information on consumers' liking of freshwater prawn (Macrobrachium rosenbergii).

    Science.gov (United States)

    Simoes, Julia Siqueira; Mársico, Eliane Teixeira; da Cruz, Adriano Gomes; de Freitas, Mônica Queiroz; Doro, Laís Higino; Conte-Junior, Carlos Adam

    2015-12-01

    This research aimed to investigate whether consumer acceptance is affected by information on sustainable practices on the product label. Hedonic evaluations of freshwater prawns were performed by 80 consumers under three aspects: the blind condition - consumers taste samples without information; expected - without tasting samples, consumers evaluated the message 'Freshwater prawns were grown using sustainable practices, reducing environmental impacts caused by traditional breeding'; informed - in which prawns were tasted and the card evaluated. For the entire consumer group, it was observed that the message about sustainability on packaging increased freshwater prawn acceptability (8.25, expected condition (E) versus 6.75, blind condition (B)). High scores were observed under all three test conditions, ranging from 6 (like slightly) to 9 (like extremely), on a 9-point scale. It can be concluded that the use of sustainable information can influence consumers' perception and increase their preference toward freshwater prawns, and even increase the sensory attributes of the product. © 2014 Society of Chemical Industry.

  16. 'I'm Black and I'm Proud': A Majority Ecological Context Protects Affective Aspects of Black Identity Under Stereotype Threat.

    Science.gov (United States)

    Oliver, Andre'; Andemeskel, Ghilamichael; King, Carlise R; Wallace, Lyndsey; McDougal, Serie; Monteiro, Kenneth P; Ben-Zeev, Avi

    2017-12-01

    We provide evidence that stereotype threat, a phenomenon that causes stigmatized individuals to experience group-based evaluative concerns (Steele in Am Psychol 52:613-629, 1997; Whistling Vivaldi and other clues to how stereotypes affect us, W.W. Norton, New York, 2010), impacts affective aspects of Black identity as a function of majority versus minority ecological contexts. Black/African-American students, enrolled in either Africana Studies (Black ecological majority) or Psychology (Black ecological minority), completed private and public regard subscales from the Multidimensional Inventory of Black Identity (Sellers et al. in Pers Soc Psychol Rev 2:18-39, 1998) at baseline (Time 1) and after being randomly assigned to a stereotype threat or no-threat/control condition (Time 2). In threat, participants were introduced to a 'puzzle' task as diagnostic of intellectual abilities, whereas in no-threat the same task was introduced as culture fair, such that people from different racial/ethnic groups had performed similarly on this task in the past. In Psychology, students under threat exhibited a simultaneous decrease and increase in private and public regard, respectively, a pattern shown in the literature to be associated with discrimination-based distress and lesser well-being in Black ecological minority environments. In contrast, Africana Studies students' racial identity under threat remained intact. We discuss the protective effects of Africana Studies on racial identity and implications for educational reform.

  17. Translational new approaches for investigating mood disorders in rodents and what they may reveal about the underlying neurobiology of major depressive disorder.

    Science.gov (United States)

    Robinson, Emma S J

    2018-03-19

    Mood disorders represent one of society's most costly and challenging health burdens. The drug treatments used today were initially discovered serendipitously in the 1950s. Animal models were then developed based on the ability of these drugs to alter specific behaviours. These models have played a major role in the development of the second generation of antidepressants. However, their use has been heavily criticized, particularly in relation to whether they recapitulate similar underlying biology to the psychiatric disorder they are proposed to represent. This article considers our work in the field of affective bias and the development of a translational research programme to try to develop and validate better animal models. We discuss whether the new data that have arisen from these studies support an alternative perspective on the underlying neurobiological processes that lead to major depressive disorder (MDD). Specifically, this article will consider whether a neuropsychological mechanism involving affective biases plays a causal role in the development of MDD and its associated emotional and behavioural symptoms. These animal studies also raise the possibility that neuropsychological mechanisms involving affective biases are a precursor to, rather than a consequence of, the neurotrophic changes linked to MDD.This article is part of a discussion meeting issue 'Of mice and mental health: facilitating dialogue between basic and clinical neuroscientists'. © 2018 The Authors.

  18. 21st Century Global Freshwater Security: Can it Exist and Can Scientists Communicate the Challenges?

    Science.gov (United States)

    Famiglietti, J. S.

    2015-12-01

    Climate models and decades of satellite data are converging on the unfortunate reality that Earth's water cycle is changing. Paleoclimate indicators remind us that this has always been the case. Freshwater is constantly being exchanged among the atmosphere, ocean, land and ice reservoirs, while on land, patterns of precipitation, evapotranspiration, flooding and drought are shifting. The evolving water cycle of the 21st century will likely be stronger, more variable, and will result in broad swaths of mid-latitude drying, accelerated by the depletion of the world's major groundwater aquifers. A well-defined geography of freshwater 'haves' and 'have-nots' is clearly emerging. What does water sustainability mean under such dynamic climate and hydrologic conditions, in particular when coupled with future projections of population growth? How will water managers cope with these new normals, and how will food and energy production be impacted? The responsibility of communicating this changing global water landscape falls squarely on the shoulders of the academic-research community, yet the challenge of doing so is daunting. In this Special Lecture I will review what our latest research tells us, and I will share my personal experiences with science communication and water diplomacy.

  19. Planning for Production of Freshwater Fish Fry in a Variable Climate in Northern Thailand.

    Science.gov (United States)

    Uppanunchai, Anuwat; Apirumanekul, Chusit; Lebel, Louis

    2015-10-01

    Provision of adequate numbers of quality fish fry is often a key constraint on aquaculture development. The management of climate-related risks in hatchery and nursery management operations has not received much attention, but is likely to be a key element of successful adaptation to climate change in the aquaculture sector. This study explored the sensitivities and vulnerability of freshwater fish fry production in 15 government hatcheries across Northern Thailand to climate variability and evaluated the robustness of the proposed adaptation measures. This study found that hatcheries have to consider several factors when planning production, including: taking into account farmer demand; production capacity of the hatchery; availability of water resources; local climate and other area factors; and, individual species requirements. Nile tilapia is the most commonly cultured species of freshwater fish. Most fry production is done in the wet season, as cold spells and drought conditions disrupt hatchery production and reduce fish farm demand in the dry season. In the wet season, some hatcheries are impacted by floods. Using a set of scenarios to capture major uncertainties and variability in climate, this study suggests a couple of strategies that should help make hatchery operations more climate change resilient, in particular: improving hatchery operations and management to deal better with risks under current climate variability; improving monitoring and information systems so that emerging climate-related risks are known sooner and understood better; and, research and development on alternative species, breeding programs, improving water management and other features of hatchery operations.

  20. Survival strategies of freshwater insects in cold environments

    Directory of Open Access Journals (Sweden)

    Valeria LENCIONI

    2004-09-01

    Full Text Available At high latitudes and altitudes, ice formation is a major variable affecting survival of freshwater fauna and hence the abundance and composition of invertebrate communities. Freezing, but also desiccation and anoxia, are lethal threats to all life stages of aquatic insects, from the eggs to the adults. During cold periods, the aquatic stages commonly remain in or move to a portion of the water body that will not freeze or dry (e.g., deep waters of lakes, springs and hyporheic zone where they can remain active. Less frequently they migrate to habitats that will freeze at the onset of winter. Insects have developed a complex of strategies to survive at their physiological temperature minimum, comprising (a morphological (melanism, reduction in size, hairiness/pubescence, brachyptery and aptery, (b behavioural (basking in the sun, changes in feeding and mating habit, parthenogenesis, polyploidy, ovoviviparity, habitat selection and cocoon building, (c ecological (extension of development to several years by quiescence or diapause and reduction of the number of generations per year, (d physiological and biochemical (freezing tolerance and freezing avoidance adaptations. Most species develop a combination of these survival strategies that can be different in the aquatic and terrestrial phase. Freezing avoidance and freezing tolerance may be accompanied by diapause. Both cold hardiness and diapause manifest during the unfavourable season and: (i involve storage of food resources (commonly glycogen and lipids; (ii are under hormonal control (ecdysone and juvenile hormone; (iii involve a depression or suppression of the oxidative metabolism with mitochondrial degradation. However, where the growing season is reduced to a few weeks, insects may develop cold hardiness without entering diapause, maintaining in the haemolymph a high concentration of Thermal Hysteris Proteins (THPs for the entire year and a slow but continuous growth. A synthesis of

  1. Selecting reliable and robust freshwater macroalgae for biomass applications.

    Directory of Open Access Journals (Sweden)

    Rebecca J Lawton

    Full Text Available Intensive cultivation of freshwater macroalgae is likely to increase with the development of an algal biofuels industry and algal bioremediation. However, target freshwater macroalgae species suitable for large-scale intensive cultivation have not yet been identified. Therefore, as a first step to identifying target species, we compared the productivity, growth and biochemical composition of three species representative of key freshwater macroalgae genera across a range of cultivation conditions. We then selected a primary target species and assessed its competitive ability against other species over a range of stocking densities. Oedogonium had the highest productivity (8.0 g ash free dry weight m⁻² day⁻¹, lowest ash content (3-8%, lowest water content (fresh weigh: dry weight ratio of 3.4, highest carbon content (45% and highest bioenergy potential (higher heating value 20 MJ/kg compared to Cladophora and Spirogyra. The higher productivity of Oedogonium relative to Cladophora and Spirogyra was consistent when algae were cultured with and without the addition of CO₂ across three aeration treatments. Therefore, Oedogonium was selected as our primary target species. The competitive ability of Oedogonium was assessed by growing it in bi-cultures and polycultures with Cladophora and Spirogyra over a range of stocking densities. Cultures were initially stocked with equal proportions of each species, but after three weeks of growth the proportion of Oedogonium had increased to at least 96% (±7 S.E. in Oedogonium-Spirogyra bi-cultures, 86% (±16 S.E. in Oedogonium-Cladophora bi-cultures and 82% (±18 S.E. in polycultures. The high productivity, bioenergy potential and competitive dominance of Oedogonium make this species an ideal freshwater macroalgal target for large-scale production and a valuable biomass source for bioenergy applications. These results demonstrate that freshwater macroalgae are thus far an under-utilised feedstock with

  2. Global imprint of historical connectivity on freshwater fish biodiversity

    OpenAIRE

    Dias, M. S.; Oberdorff, Thierry; Hugueny, Bernard; Leprieur, F.; Jézéquel, Céline; Cornu, Jean-François; Brosse, S.; Grenouillet, G.; Tedesco, Pablo

    2014-01-01

    The relative importance of contemporary and historical processes is central for understanding biodiversity patterns. While several studies show that past conditions can partly explain the current biodiversity patterns, the role of history remains elusive. We reconstructed palaeo-drainage basins under lower sea level conditions (Last Glacial Maximum) to test whether the historical connectivity between basins left an imprint on the global patterns of freshwater fish biodiversity. After controll...

  3. Dissolved organic carbon in the freshwater tidal reaches of the Schelde estuary

    DEFF Research Database (Denmark)

    Muylaert, K.; Dasseville, R.; De Brabandere, Loreto

    2005-01-01

    To unravel the factors that regulate DOC dynamics in the freshwater tidal reaches of the Schelde estuary, DOC concentration and biodegradability were monitored in the upper Schelde estuary and its major tributaries. Although the Schelde estuary possesses a densely populated and industrialized...... catchment, our data suggest that the bulk of DOC in the freshwater tidal reaches is not derived from waste water. This was concluded from the low biodegradability of DOC (on average 9%), DOC concentrations that are close to the mean for European rivers (4.61 mg/l) and the absence of an inverse relationship....../l), these blooms did not appear to produce large quantities of DOC in the freshwater tidal reaches as DOC concentrations were low when phytoplankton biomass was high. The fact that DOC concentrations were high in winter and decreased in summer suggests a predominantly terrestrial source of DOC in the freshwater...

  4. PprM is necessary for up-regulation of katE1, encoding the major catalase of Deinococcus radiodurans, under unstressed culture conditions.

    Science.gov (United States)

    Jeong, Sun-Wook; Seo, Ho Seong; Kim, Min-Kyu; Choi, Jong-Il; Lim, Heon-Man; Lim, Sangyong

    2016-06-01

    Deinococcus radiodurans is a poly-extremophilic organism, capable of tolerating a wide variety of different stresses, such as gamma/ultraviolet radiation, desiccation, and oxidative stress. PprM, a cold shock protein homolog, is involved in the radiation resistance of D. radiodurans, but its role in the oxidative stress response has not been investigated. In this study, we investigated the effect of pprM mutation on catalase gene expression. pprM disruption decreased the mRNA and protein levels of KatE1, which is the major catalase in D. radiodurans, under normal culture conditions. A pprM mutant strain (pprM MT) exhibited decreased catalase activity, and its resistance to hydrogen peroxide (H2O2) decreased accordingly compared with that of the wild-type strain. We confirmed that RecG helicase negatively regulates katE1 under normal culture conditions. Among katE1 transcriptional regulators, the positive regulator drRRA was not altered in pprM (-), while the negative regulators perR, dtxR, and recG were activated more than 2.5-fold in pprM MT. These findings suggest that PprM is necessary for KatE1 production under normal culture conditions by down-regulation of katE1 negative regulators.

  5. Farming of Freshwater Rainbow Trout in Denmark

    DEFF Research Database (Denmark)

    Jokumsen, Alfred; Svendsen, Lars Moeslund

    Textbook on Farming of Freshwater Rainbow Trout in Denmark. Danish edition with the title: Opdræt af regnbueørred i Danmark......Textbook on Farming of Freshwater Rainbow Trout in Denmark. Danish edition with the title: Opdræt af regnbueørred i Danmark...

  6. Effects of Pollution on Freshwater Fish.

    Science.gov (United States)

    Brungs, W. A.; And Others

    1978-01-01

    Presents a literature review of the effects of pollution on freshwater fish, covering publications of 1976-77. This review includes: (1) water quality; (2) pesticide pollutants; (3) chemical pollutants; (4) miscellaneous pollutants; and (5) physical factors of pollution on freshwater fish. A list of 338 references is also presented. (HM)

  7. Freshwater ecosystems and aquatic insects: a paradox in biological invasions.

    Science.gov (United States)

    Fenoglio, Stefano; Bonada, Núria; Guareschi, Simone; López-Rodríguez, Manuel J; Millán, Andrés; Tierno de Figueroa, J Manuel

    2016-04-01

    Biological invasions have increased significantly in response to global change and constitute one of the major causes of biodiversity loss. Insects make up a large fraction of invasive species, in general, and freshwaters are among the most invaded ecosystems on our planet. However, even though aquatic insects dominate most inland waters, have unparalleled taxonomic diversity and occupy nearly all trophic niches, there are almost no invasive insects in freshwaters. We present some hypotheses regarding why aquatic insects are not common among aquatic invasive organisms, suggesting that it may be the result of a suite of biological, ecological and anthropogenic factors. Such specific knowledge introduces a paradox in the current scientific discussion on invasive species; therefore, a more in-depth understanding could be an invaluable aid to disentangling how and why biological invasions occur. © 2016 The Author(s).

  8. The biological transport of radionuclides in grassland and freshwater ecosystems

    International Nuclear Information System (INIS)

    Rudge, S.A.

    1989-12-01

    This thesis examines the biological transport of radionuclides through terrestrial and aquatic ecosystems, with particular reference to radiocaesium. The semi-natural grassland habitat was located at Drigg, W. Cumbria, contaminated primarily by radioactive fallout, from several sources over the past decade. Advantage was made of the deposition of radionuclides from the Chernobyl reactor incident, which occurred during the early stages of the investigation. The study examined the distribution of radiocaesium for the major components of the grassland ecosystem, within the soil-plant-invertebrate-small mammal food chain. Data concerning temporal fluctuation of radionuclide transfer factors between food chain components are presented. The final section examines the spatial distribution of radiocaesium in sediment and the freshwater eel (Anguilla anguilla) in a small stream contaminated by radioactive effluent. The relationship between activity levels in eels and the sediments in which they rest and forage was investigated. Factors influencing uptake of radiocaesium in freshwater fish were also examined. (author)

  9. Title: Freshwater phytoplankton responses to global warming.

    Science.gov (United States)

    Wagner, Heiko; Fanesi, Andrea; Wilhelm, Christian

    2016-09-20

    Global warming alters species composition and function of freshwater ecosystems. However, the impact of temperature on primary productivity is not sufficiently understood and water quality models need to be improved in order to assess the quantitative and qualitative changes of aquatic communities. On the basis of experimental data, we demonstrate that the commonly used photosynthetic and water chemistry parameters alone are not sufficient for modeling phytoplankton growth under changing temperature regimes. We present some new aspects of the acclimation process with respect to temperature and how contrasting responses may be explained by a more complete physiological knowledge of the energy flow from photons to new biomass. We further suggest including additional bio-markers/traits for algal growth such as carbon allocation patterns to increase the explanatory power of such models. Although carbon allocation patterns are promising and functional cellular traits for growth prediction under different nutrient and light conditions, their predictive power still waits to be tested with respect to temperature. A great challenge for the near future will be the prediction of primary production efficiencies under the global change scenario using a uniform model for phytoplankton assemblages. Copyright © 2016 Elsevier GmbH. All rights reserved.

  10. The freshwater reservoir effect in radiocarbon dating

    DEFF Research Database (Denmark)

    Philippsen, Bente

    2013-01-01

    of magnitude and degree of variability of the freshwater reservoir effect over short and long timescales. Radiocarbon dating of recent water samples, aquatic plants, and animals, shows that age differences of up to 2000 14C years can occur within one river. The freshwater reservoir effect has also implications......The freshwater reservoir effect can result in anomalously old radiocarbon ages of samples from lakes and rivers. This includes the bones of people whose subsistence was based on freshwater fish, and pottery in which fish was cooked. Water rich in dissolved ancient calcium carbonates, commonly known...... as hard water, is the most common reason for the freshwater reservoir effect. It is therefore also called hardwater effect. Although it has been known for more than 60 years, it is still less well-recognized by archaeologists than the marine reservoir effect. The aim of this study is to examine the order...

  11. The freshwater reservoir effect in radiocarbon dating

    DEFF Research Database (Denmark)

    Philippsen, Bente

    case studies will show the degree of variability of the freshwater reservoir effect over short and long timescales. Radiocarbon dating of recent water samples, aquatic plants and animals, shows that age differences of up to 2000 years can occur within one river. In the Limfjord, freshwater influence......The freshwater reservoir effect can result in too high radiocarbon ages of samples from lakes and rivers, including the bones of people whose subsistence was based on freshwater fish, and pottery in which fish was cooked. In my talk, I will explain the causes and consequences of this effect. Two...... caused reservoir ages to vary between 250 and 700 years during the period 5400 BC - AD 700. Finally, I will discuss the implications of the freshwater reservoir effect for radiocarbon dating of Mesolithic pottery from inland sites of the Ertebølle culture in Northern Germany....

  12. The Impact of climate change on heat-related mortality in six major cities, South Korea, under representative concentration pathways (RCPs

    Directory of Open Access Journals (Sweden)

    Youngmin eKim

    2014-02-01

    Full Text Available Background: We aimed to quantify the excess mortality associated with increased temperature due to climate change in six major Korean cities under Representative Concentration Pathways (RCPs which are new emission scenarios designed for the fifth assessment report of the Intergovernmental Panel on Climate Change (IPCC. Methods: We first examined the association between daily mean temperature and mortality in each during the summertime (June to September from 2001 to 2008. This was done using a generalized linear Poisson model with adjustment for a long-term time trend, relative humidity, air pollutants, and day of the week. We then computed heat-related mortality attributable to future climate change using estimated mortality risks, projected future populations, and temperature increments for both future years 2041-2070 and 2071-2100 under RCP 4.5 and 8.5. We considered effects from added days with high temperatures over thresholds and shifted effects from high to higher temperature.Results: Estimated excess all-cause mortalities for six cities in Korea ranged from 500 (95% CI: 313-703 for 2041-2070 to 2,320 (95% CI: 1,430-3,281 deaths per year for 2071-2100 under two RCPs. Excess cardiovascular mortality was estimated to range from 192 (95% CI: 41-351 to 896 (95% CI: 185-1,694 deaths per year, covering about 38.5% of all-cause excess mortality. Increased rates of heat-related mortality were higher in cities located at relatively lower latitude than cities with higher latitude. Estimated excess mortality under RCP 8.5, a fossil fuel-intensive emission scenario, was more than twice as high compared with RCP 4.5, low to medium emission scenario.Conclusions: Excess mortality due to climate change is expected to be profound in the future showing spatial variation. Efforts to mitigate climate change can cause substantial health benefits via reducing heat-related mortality.

  13. Non-parallel divergence across freshwater and marine three-spined stickleback Gasterosteus aculeatus populations.

    Science.gov (United States)

    Pujolar, J M; Ferchaud, A L; Bekkevold, D; Hansen, M M

    2017-07-01

    This work investigated whether multiple freshwater populations of three-spined stickleback Gasterosteus aculeatus in different freshwater catchments in the Jutland Peninsula, Denmark, derived from the same marine populations show repeated adaptive responses. A total of 327 G. aculeatus collected at 13 sampling locations were screened for genetic variation using a combination of 70 genes putatively under selection and 26 neutral genes along with a marker linked to the ectodysplasin gene (eda), which is strongly correlated with plate armour morphs in the species. A highly significant genetic differentiation was found that was higher among different freshwater samples than between marine-freshwater samples. Tests for selection between marine and freshwater populations showed a very low degree of parallelism and no single nucleotide polymorphism was detected as outlier in all freshwater-marine pairwise comparisons, including the eda. This suggests that G. aculeatus is not necessarily the prime example of parallel local adaptation suggested in much of the literature and that important exceptions exist (i.e. the Jutland Peninsula). While marine populations in the results described here showed a high phenotype-genotype correlation at eda, a low association was found for most of the freshwater populations. The most extreme case was found in the freshwater Lake Hald where all low-plated phenotypes were either homozygotes for the allele supposed to be associated with completely plated morphs or heterozygotes, but none were homozygotes for the putative low-plated allele. Re-examination of data from seven G. aculeatus studies agrees in showing a high but partial association between phenotype-genotype at eda in G. aculeatus freshwater populations and that mismatches occur everywhere in the European regions studied (higher in some areas, i.e. Denmark). This is independent of the eda marker used. © 2017 The Fisheries Society of the British Isles.

  14. Using species sensitivity distribution approach to assess the risks of commonly detected agricultural pesticides to Australia's tropical freshwater ecosystems.

    Science.gov (United States)

    Pathiratne, Asoka; Kroon, Frederieke J

    2016-02-01

    To assess the potential impacts of agricultural pesticides on tropical freshwater ecosystems, the present study developed temperature-specific, freshwater species protection concentrations (i.e., ecotoxicity threshold values) for 8 pesticides commonly detected in Australia's tropical freshwaters. Because relevant toxicity data for native tropical freshwater species to assess the ecological risks were mostly absent, scientifically robust toxicity data obtained at ≥20 °C were used for ecologically relevant taxonomic groups representing primary producers and consumers. Species sensitivity distribution (SSD) curves were subsequently generated for predicted chronic exposure using Burrlioz 2.0 software with mixed chronic and converted acute data relevant to exposure conditions at ≥20 °C. Ecotoxicity threshold values for tropical freshwater ecosystem protection were generated for ametryn, atrazine, diuron, metolachlor, and imidacloprid (all moderate reliability), as well as simazine, hexazinone, and tebuthiuron (all low reliability). Using these SSD curves, the retrospective risk assessments for recently reported pesticide concentrations highlight that the herbicides ametryn, atrazine, and diuron are of major concern for ecological health in Australia's tropical freshwater ecosystems. The insecticide imidacloprid also appears to pose an emerging threat to the most sensitive species in tropical freshwater ecosystems. The exposed temperature-specific approach may be applied to develop water quality guideline values for other environmental contaminants detected in tropical freshwater ecosystems until reliable and relevant toxicity data are generated using representative native species. © 2015 SETAC.

  15. Status and Impacts of Arctic Freshwater Export

    Science.gov (United States)

    Haine, T. W. N.

    2017-12-01

    Large freshwater anomalies clearly exist in the Arctic Ocean. For example, liquid freshwater has accumulated in the Beaufort Gyre in the decade of the 2000s compared to 1980-2000, with an extra ≈5000 km3—about 25%—being stored. The sources of freshwater to the Arctic from precipitation and runoff have increased between these periods (most of the evidence comes from models). Despite flux increases from 2001 to 2011, it is uncertain if the marine freshwater source through Bering Strait for the 2000s has changed, as observations in the 1980s and 1990s are incomplete. The marine freshwater fluxes draining the Arctic through Fram and Davis straits are also insignificantly different. In this way, the balance of sources and sinks of freshwater to the Arctic, Canadian Arctic Archipelago (CAA), and Baffin Bay shifted to about 1200±730 km3yr-1 freshening the region, on average, during the 2000s. The observed accumulation of liquid freshwater is consistent with this increased supply and the loss of freshwater from sea ice (Figure, right). Evidence exists that such discharges can impact the Atlantic meridional overturning circulation, and hence Atlantic sector climate. Nevertheless, it appears that the observed AMOC variability since 2004, when high quality measurements began, is not attributable to anthropogenic influence. This work is based on, and updated from, Haine et al. (2015), Carmack et al. (2016), and Haine (2016). Haine, T. W. N. Ocean science: Vagaries of Atlantic overturning. Nature Geoscience, 9, 479-480, 10.1038/ngeo2748, 2016. T. W. N. Haine et al., Arctic Freshwater Export: Status, Mechanisms, and Prospects, Global Planetary Change, 125, 13-35, 10.1016/j.glopacha.2014.11.013, 2015. E. Carmack et al., Fresh water and its role in the Arctic Marine System: sources, disposition, storage, export, and physical and biogeochemical consequences in the Arctic and global oceans. J. G. Res. Biogeosciences, 10.1002/2015JG003140, 2016.

  16. Major depression

    Science.gov (United States)

    Depression - major; Depression - clinical; Clinical depression; Unipolar depression; Major depressive disorder ... providers do not know the exact causes of depression. It is believed that chemical changes in the ...

  17. INVESTIGATION ON BIODIVERSITY AND CONSERVATION OF FRESHWATER FISHES IN INDONESIA

    Directory of Open Access Journals (Sweden)

    Sudarto Sudarto

    2012-12-01

    Full Text Available Indonesia is one of the richest regions in the world in terms of biodiversity. However, recent evidence has shown that tropical forests destruction has maintained at a high rate over the last few years in this country. At the same time, living resources in Indonesian freshwater ecosystems are important: this country ranks at number seven in terms of production of inland capture fisheries with 323,150 tonnes in 2008. Freshwater fishes represent 42% of the total estimated ichthyofauna, concentrated in 0.01% of the total water covered environment. This environment is closer to human activities, making it critically vulnerable to adverse impacts. Furthermore, there has been some recent debates on the general sustainability of fisheries and aquaculture production systems. This research was focused on initiating a multi-scale study of fish biodiversity in freshwater environments. Two specific actions have been started. A review based on the analyses of the existing scientific literature and of databases on fish taxonomy and distributions. In parallel to this work, a global analysis of the distribution of fish diversity in Indonesia was undertaken. This work aims at identifying the major features of this resource as well as its current and future threats.

  18. Multiple invasions into freshwater by pufferfishes (teleostei: tetraodontidae: a mitogenomic perspective.

    Directory of Open Access Journals (Sweden)

    Yusuke Yamanoue

    Full Text Available Pufferfishes of the Family Tetraodontidae are the most speciose group in the Order Tetraodontiformes and mainly inhabit coastal waters along continents. Although no members of other tetraodontiform families have fully discarded their marine lives, approximately 30 tetraodontid species spend their entire lives in freshwaters in disjunct tropical regions of South America, Central Africa, and Southeast Asia. To investigate the interrelationships of tetraodontid pufferfishes and thereby elucidate the evolutionary origins of their freshwater habitats, we performed phylogenetic analysis based on whole mitochondrial genome sequences from 50 tetraodontid species and closely related species (including 31 newly determined sequences. The resulting phylogenies reveal that the family is composed of four major lineages and that freshwater species from the different continents are independently nested in two of the four lineages. A monophyletic origin of the use of freshwater habitats was statistically rejected, and ancestral habitat reconstruction on the resulting tree demonstrates that tetraodontids independently entered freshwater habitats in different continents at least three times. Relaxed molecular-clock Bayesian divergence time estimation suggests that the timing of these invasions differs between continents, occurring at 0-10 million years ago (MA in South America, 17-38 MA in Central Africa, and 48-78 MA in Southeast Asia. These timings are congruent with geological events that could facilitate adaptation to freshwater habitats in each continent.

  19. Measuring benefits of protected area management: trends across realms and research gaps for freshwater systems.

    Science.gov (United States)

    Adams, Vanessa M; Setterfield, Samantha A; Douglas, Michael M; Kennard, Mark J; Ferdinands, Keith

    2015-11-05

    Protected areas remain a cornerstone for global conservation. However, their effectiveness at halting biodiversity decline is not fully understood. Studies of protected area benefits have largely focused on measuring their impact on halting deforestation and have neglected to measure the impacts of protected areas on other threats. Evaluations that measure the impact of protected area management require more complex evaluation designs and datasets. This is the case across realms (terrestrial, freshwater, marine), but measuring the impact of protected area management in freshwater systems may be even more difficult owing to the high level of connectivity and potential for threat propagation within systems (e.g. downstream flow of pollution). We review the potential barriers to conducting impact evaluation for protected area management in freshwater systems. We contrast the barriers identified for freshwater systems to terrestrial systems and discuss potential measurable outcomes and confounders associated with protected area management across the two realms. We identify key research gaps in conducting impact evaluation in freshwater systems that relate to three of their major characteristics: variability, connectivity and time lags in outcomes. Lastly, we use Kakadu National Park world heritage area, the largest national park in Australia, as a case study to illustrate the challenges of measuring impacts of protected area management programmes for environmental outcomes in freshwater systems. © 2015 The Author(s).

  20. Culture, hydrology, and other situational controls on atoll freshwater availability (Majuro, Republic of the Marshall Islands)

    Science.gov (United States)

    Shuster, W.

    2016-12-01

    The comparatively uncertain rainfall catch and rising seas in isolated North Pacific atoll communities has presented serious challenges to maintain human communities with freshwater volume. Moreover, the feudal hierarchy, which structures social and economic relationships among local governance and citizens contributes equally to problems and potential solutions. These relationships modulate the availability of critical ecosystem services generated by freshwater, with additional constraints contributed by climate change, rainfall variability (e.g., current El Niño climate pattern), and continuous threat of drought. The major freshwater resources for an atoll are the groundwater freshwater lens, residential and commercial rainwater harvesting, large-scale rainfall catchments (e.g., an airport runway), imported-virtual water, or desalinization subsidies. The significance of each of these resources scale across different atolls according to size, topography, soils, population, infrastructure, and land ownership. The potential integration and coordination of these water resources is largely unrealized due to land ownership, the lack of a contiguous catchment area, uneven and fractured governance. The situational aspects are further characterized by feuding among families and communities (some resource rich, some resource poor), and conflicting land use priorities where agriculture placement and practice can compromise the quality of already limited freshwater resources. This presentation uses the example of Majuro atoll (Republic of the Marshall Islands), field data and other observations, to illustrate sociohydrologic-drivers of freshwater availability, and suggests approaches that may improve on current and ongoing threats to public health and well-being.

  1. Bioaccumulation factors for radionuclides in freshwater biota

    International Nuclear Information System (INIS)

    Vanderploeg, H.A.; Parzyck, D.C.; Wilcox, W.H.; Kercher, J.R.; Kaye, S.V.

    1975-11-01

    This report analyzes over 200 carefully selected papers to provide concise data sets and methodology for estimation of bioaccumulation factors for tritium and isotopes of strontium, cesium, iodine, manganese, and cobalt in major biotic components of freshwater environments. Bioaccumulation factors of different tissues are distinguished where significant differences occur. Since conditions in the laboratory are often unnatural in terms of chemical and ecological relationships, this review was restricted as far as possible to bioaccumulation factors determined for natural systems. Because bioaccumulation factors were not available for some shorter-lived radionuclides, a methodology for converting bioaccumulation factors of stable isotopes to those of shorter-lived radionuclides was derived and utilized. The bioaccumulation factor for a radionuclide in a given organism or tissue may exhibit wide variations among bodies of water that are related to differences in ambient concentrations of stable-element and carrier-element analogues. To account for these variations, simple models are presented that relate bioaccumulation factors to stable-element and carrier-element concentrations in water. The effects of physicochemical form and other factors in causing deviations from these models are discussed. Bioaccumulation factor data are examined in the context of these models, and bioaccumulation factor relations for the selected radionuclides are presented

  2. Interaction of Freshwater Diatom with Gold Nanoparticles: Adsorption, Assimilation, and Stabilization by Cell Exometabolites

    Directory of Open Access Journals (Sweden)

    Aridane G. González

    2018-03-01

    Full Text Available The rising concern about the potential toxicity of synthetic gold nanoparticles (AuNPs in aquatic environments requires a rigorous estimation of physico-chemical parameters of reactions between AuNPs and major freshwater microorganisms. This study addresses the interaction of 10-nm size, positively charged AuNPs with periphytic freshwater diatoms (Eolimna minima. The adsorption experiments on viable cells were performed in 10 mM NaCl and 5 mM NaCl + 5 mM NaHCO3 solution at a variable pH (3–10, at an AuNPs concentration from 1 µg/L to 10,000 µg/L, and an exposure time from a few minutes to 55 days. Three types of experiments, adsorption as a function of time (kinetics, pH-dependent adsorption edge, and constant-pH “Langmuirian” type isotherms, were conducted. In addition, long-term interactions (days to weeks of live diatoms (under light and in the darkness were performed. The adsorption was maximal at a pH from 3 to 6 and sizably decreased at a pH of 6 to 10. Results of adsorption experiments were modeled using a second order kinetic model, a Linear Programming Model, Freundlich isotherm, and a ligand binding equation for one site competition. The adsorption of AuNPs(+ most likely occurred on negatively-charged surface sites of diatom cell walls such as carboxylates or phosphorylates, similar to previously studied metal cations. Under light exposure, the AuNPs were stabilized in aqueous solution in the presence of live cells, probably due to the production of exometabolites by diatoms. The adsorbed amount of AuNPs decreased after several days of reaction, suggesting some AuNPs desorption. In the darkness, the adsorption and assimilation were stronger than under light. Overall, the behavior of positively charged AuNPs at the diatom–aqueous solution interface is similar to that of metal cations, but the affinity of aqueous AuNPs to cell exometabolites is higher, which leads to the stabilization of nanoparticles in solution in the

  3. Revealing vilazodone's binding mechanism underlying its partial agonism to the 5-HT1A receptor in the treatment of major depressive disorder.

    Science.gov (United States)

    Zheng, Guoxun; Xue, Weiwei; Yang, Fengyuan; Zhang, Yang; Chen, Yuzong; Yao, Xiaojun; Zhu, Feng

    2017-11-01

    It has been estimated that major depressive disorder (MDD) will become the second largest global burden among all diseases by 2030. Various types of drugs, including selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), and serotonin receptor partial agonist/reuptake inhibitors (SPARIs), have been approved and become the primary or first-line medications prescribed for MDD. SPARI was expected to demonstrate more enhanced drug efficacy and a rapid onset of action as compared to SSRI and SNRI. As one of the most famous SPARIs, vilazodone was approved by the FDA for the treatment of MDD. Because of the great clinical importance of vilazodone, its binding mechanism underlying its partial agonism to the 5-HT 1A receptor (5-HT 1A R) could provide valuable information to SPARIs' drug-like properties. However, this mechanism has not been reported to date; consequently, the rational design of new efficacious SPARI-based MDD drugs is severely hampered. To explore the molecular mechanism of vilazodone, an integrated computational strategy was adopted in this study to reveal its binding mechanism and prospective structural feature at the agonist binding site of 5-HT 1A R. As a result, 22 residues of this receptor were identified as hotspots, consistently favoring the binding of vilazodone and its analogues, and a common binding mechanism underlying their partial agonism to 5-HT 1A R was, therefore, discovered. Moreover, three main interaction features between vilazodone and 5-HT 1A R have been revealed and schematically summarized. In summary, this newly identified binding mechanism will provide valuable information for medicinal chemists working in the field of rational design of novel SPARIs for MDD treatment.

  4. Analysis of data from test-well sites along the downdip limit of freshwater in the Edwards Aquifer, San Antonio, Texas, 1985-87

    Science.gov (United States)

    Groschen, G.E.

    1994-01-01

    Many researchers have studied the downdip limit of freshwater in the Edwards aquifer or various aspects of the saline-water zone and its relation to the freshwater zone. These studies were summarized and used to synthesize a consistent hydrologic and geochemical framework from which to interpret data from field studies. The concept derived from the previous work on the downdip limit of the freshwater zone is that fresh recharge water entered the aquifer and developed a vast flow system controlled by barrier faults. Some recharge water flows into the saline-water zone rather than toward major freshwater discharge points. The water that enters the salinewater zone continues to dissolve gypsum and dolomite, and calcite precipitates out of the water. This process of dedolomitization has helped to develop the large secondary porosity of the freshwater zone as the downdip limit of the freshwater zone progressively moved downdip in recent geologic time.

  5. Davis Pond freshwater prediversion biomonitoring study: freshwater fisheries and eagles

    Science.gov (United States)

    Jenkins, Jill A.; Bourgeois, E. Beth; Jeske, Clint W.

    2008-01-01

    In January 2001, the construction of the Davis Pond freshwater diversion structure was completed by the U.S. Army Corps of Engineers. The diversion of freshwater from the Mississippi River is intended to mitigate saltwater intrusion from the Gulf of Mexico and to lessen the concomitant loss of wetland areas. In addition to the freshwater inflow, Barataria Bay basin would receive nutrients, increased flows of sediments, and water-borne and sediment-bound compounds. The purpose of this biomonitoring study was, therefore, to serve as a baseline for prediversion concentrations of selected contaminants in bald eagle (Haliaeetus leucocephalus) nestlings (hereafter referred to as eaglets), representative freshwater fish, and bivalves. Samples were collected from January through June 2001. Two similarly designed postdiversion studies, as described in the biological monitoring program, are planned. Active bald eagle nests targeted for sampling eaglet blood (n = 6) were generally located southwest and south of the diversion structure. The designated sites for aquatic animal sampling were at Lake Salvador, at Lake Cataouatche, at Bayou Couba, and along the Mississippi River. Aquatic animals representative of eagle prey were collected. Fish were from three different trophic levels and have varying feeding strategies and life histories. These included herbivorous striped mullet (Mugil cephalus), omnivorous blue catfish (Ictalurus furcatus), and carnivorous largemouth bass (Micropterus salmoides). Three individuals per species were collected at each of the four sampling sites. Freshwater Atlantic rangia clams (Rangia cuneata) were collected at the downstream marsh sites, and zebra mussels (Dreissena spp.) were collected on the Mississippi River. The U.S. Geological Survey (USGS) Biomonitoring of Environmental Status and Trends (BEST) protocols served as guides for fish sampling and health assessments. Fish are useful for monitoring aquatic ecosystems because they accumulate

  6. Exotic freshwater planarians currently known from Japan

    NARCIS (Netherlands)

    Sluys, R.; Kawakatsu, M.; Yamamoto, K.

    2010-01-01

    Biogeographical and taxonomic information on the four non-indigenous freshwater planarians of Japan is reviewed, viz. Dugesia austroasiatica Kawakatsu, 1985, Girardia tigrina (Girard, 1850), G. dorotocephala (Woodworth, 1897), and Rhodax evelinae? Marcus, 1947. The occurrence of Girardia

  7. Identifying national freshwater ecosystem priority areas

    CSIR Research Space (South Africa)

    Nel, JL

    2012-10-01

    Full Text Available This presentation highlights the use of systematic conservation planning to identify priority areas for managing the health of freshwater ecosystems and their associated biodiversity and ecosystem services....

  8. Characterization of a Freshwater Crab Sudanonautes aubryi ...

    African Journals Online (AJOL)

    SARAH

    2014-01-31

    Jan 31, 2014 ... 2Faculty of Sciences and Techniques, University Marien Ngouabi - PoB 69 Congo Brazzaville ... to collect and realize a biometric characterization of this common freshwater ... information, which will be used by conservation.

  9. Effects of pollution on freshwater fish

    International Nuclear Information System (INIS)

    McKim, J.M.; Anderson, R.L.; Benoit, D.A.; Spehar, R.L.; Stokes, G.N.

    1976-01-01

    Studies of the effects of pollution on freshwater fish are reviewed. Subjects include: inorganic industrial pollutants, man-made disturbances and radioactive pollutants. Topics include uptake distribution, retention, mortality, and lethal doses

  10. Persistent organochlorine pesticide residues in freshwater systems ...

    African Journals Online (AJOL)

    DRINIE

    determined in water and sediment samples of freshwater systems in the Eastern Cape Province of South Africa that ... The organochlorine pesticides (OCPs) in water and sediments ...... Test Methods For Evaluating Solid Waste (3rd edn.) ...

  11. A synthetic phylogeny of freshwater crayfish: insights for conservation

    Science.gov (United States)

    Owen, Christopher L.; Bracken-Grissom, Heather; Stern, David; Crandall, Keith A.

    2015-01-01

    Phylogenetic systematics is heading for a renaissance where we shift from considering our phylogenetic estimates as a static image in a published paper and taxonomies as a hardcopy checklist to treating both the phylogenetic estimate and dynamic taxonomies as metadata for further analyses. The Open Tree of Life project (opentreeoflife.org) is developing synthesis tools for harnessing the power of phylogenetic inference and robust taxonomy to develop a synthetic tree of life. We capitalize on this approach to estimate a synthesis tree for the freshwater crayfish. The crayfish make an exceptional group to demonstrate the utility of the synthesis approach, as there recently have been a number of phylogenetic studies on the crayfishes along with a robust underlying taxonomic framework. Importantly, the crayfish have also been extensively assessed by an IUCN Red List team and therefore have accurate and up-to-date area and conservation status data available for analysis within a phylogenetic context. Here, we develop a synthesis phylogeny for the world's freshwater crayfish and examine the phylogenetic distribution of threat. We also estimate a molecular phylogeny based on all available GenBank crayfish sequences and use this tree to estimate divergence times and test for divergence rate variation. Finally, we conduct EDGE and HEDGE analyses and identify a number of species of freshwater crayfish of highest priority in conservation efforts. PMID:25561670

  12. Freshwater availability and coastal wetland foundation species: ecological transitions along a rainfall gradient

    Science.gov (United States)

    Osland, Michael J.; Enwright, Nicholas M.; Stagg, Camille L.

    2014-01-01

    Climate gradient-focused ecological research can provide a foundation for better understanding critical ecological transition points and nonlinear climate-ecological relationships, which is information that can be used to better understand, predict, and manage ecological responses to climate change. In this study, we examined the influence of freshwater availability upon the coverage of foundation plant species in coastal wetlands along a northwestern Gulf of Mexico rainfall gradient. Our research addresses the following three questions: (1) what are the region-scale relationships between measures of freshwater availability (e.g., rainfall, aridity, freshwater inflow, salinity) and the relative abundance of foundation plant species in tidal wetlands; (2) How vulnerable are foundation plant species in tidal wetlands to future changes in freshwater availability; and (3) What is the potential future relative abundance of tidal wetland foundation plant species under alternative climate change scenarios? We developed simple freshwater availability-based models to predict the relative abundance (i.e., coverage) of tidal wetland foundation plant species using climate data (1970-2000), estuarine freshwater inflow-focused data, and coastal wetland habitat data. Our results identify regional ecological thresholds and nonlinear relationships between measures of freshwater availability and the relative abundance of foundation plant species in tidal wetlands. In drier coastal zones, relatively small changes in rainfall could produce comparatively large landscape-scale changes in foundation plant species abundance which would affect some ecosystem good and services. Whereas a drier future would result in a decrease in the coverage of foundation plant species, a wetter future would result in an increase in foundation plant species coverage. In many ways, the freshwater-dependent coastal wetland ecological transitions we observed are analogous to those present in dryland

  13. FRESHWATER FISHERY OF THE REPUBLIC OF CROATIA

    Directory of Open Access Journals (Sweden)

    Zlatko Homen

    1999-09-01

    in 1998. was carp (80.93%, then trout (8.30 %, herbivorous kinds of fish (8.01% and all other fish (2.76% out of which sheat fish was the most produced. Only slightly changed structure of the production is expected in 1999. Carp production will still be the most prolific and slightly increased - 81.97%, trout - production - 6.68 %, herbivorous fish - 7.69% and other kinds of fish - 3.69% which in increased percentage in relation to 1998. Taking into consideration production surfaces of the fish ponds and the realized production in 1998., it can be conciuded that the average amount in carp fish ponds was 710.37 kg/ha which is substantially under desired amount of about 1000 kg/ha. Surely, it should be stressed that some fish ponds managed to attain that number and even to exceed it. In trout fish ponds the average amount was 133.17 t/ha. The increased production requires an increased need for food. It is expected that the largest expenditure for fish feeding will be that of corn (60.59%, wheat (14.91%, mixture (10.36%, barley (8.38%, and soya shot (3.29%, meat-bone flour (0.48, fish flour (0.51%, medicines, medicinal food and aditives (0.68% and other food (0.81%. Fish in carp ponds are sold on the domestic market and abroad, while trouts are sold only on the domestic market. Total realization on the freshwater fish market was 45 milions kunas in 1998. As one of the mesaures for improvement of fishery and aquaculture in general are stimuli for production of freshwater fish. On the grounds of the law of monetary incentive in agriculture and fishery. During 1998. A monetary incentive for growing of freshwater fish was payed and it was 5,623,957.01 kunas which is an increase of 77.57% in relation to 1997.

  14. Biofouling problems in freshwater cooling systems

    International Nuclear Information System (INIS)

    Rao, T.S.

    2007-01-01

    In aqueous environments, microorganisms (bacteria, algae, fungi etc.,) are attracted towards surfaces, which they readily colonise resulting in the formation of biofilms. The implications of biofouling are energy losses due to increased fluid frictional resistance and increased heat transfer resistance. The temperatures prevalent inside the condenser system provide a favorable environment for the rapid growth of microorganisms. This results in thick slime deposit, which is responsible for heat transfer losses, thereby enhancing aggregation of deposits on the material surface and induces localised corrosion. There have been instances of increased capital costs due to premature replacement of equipment caused by severe under deposit corrosion due to biofouling. Moreover, fouling of service water systems of nuclear power plants is of concern, because it reduces the heat transfer capacity during an emergency or an accident. The growth of microbial films (slimes) a few tens of microns thick, in a condenser tube is sufficient to induce microbiologically influenced corrosion and cause irreparable damage to the condenser tubes and other structural materials. The down time costs to power plant due to condenser fouling and corrosion are quite large. This paper presents the author's experience in biofouling and corrosion problems in various power plants cooled by freshwater. (author)

  15. Microplastic Effect Thresholds for Freshwater Benthic Macroinvertebrates

    Science.gov (United States)

    2018-01-01

    Now that microplastics have been detected in lakes, rivers, and estuaries all over the globe, evaluating their effects on biota has become an urgent research priority. This is the first study that aims at determining the effect thresholds for a battery of six freshwater benthic macroinvertebrates with different species traits, using a wide range of microplastic concentrations. Standardized 28 days single species bioassays were performed under environmentally relevant exposure conditions using polystyrene microplastics (20–500 μm) mixed with sediment at concentrations ranging from 0 to 40% sediment dry weight (dw). Microplastics caused no effects on the survival of Gammarus pulex, Hyalella azteca, Asellus aquaticus, Sphaerium corneum, and Tubifex spp. and no effects were found on the reproduction of Lumbriculus variegatus. No significant differences in growth were found for H. azteca, A. aquaticus, S. corneum, L. variegatus, and Tubifex spp. However, G. pulex showed a significant reduction in growth (EC10 = 1.07% sediment dw) and microplastic uptake was proportional with microplastic concentrations in sediment. These results indicate that although the risks of environmentally realistic concentrations of microplastics may be low, they still may affect the biodiversity and the functioning of aquatic communities which after all also depend on the sensitive species. PMID:29337537

  16. Meeting ecological and societal needs for freshwater

    Science.gov (United States)

    Baron, Jill S.; Poff, N.L.; Angermeier, P.L.; Dahm, Clifford N.; Gleick, P.H.; Hairston, N.G.; Jackson, R.B.; Johnston, C.A.; Richter, B.D.; Steinman, A.D.

    2002-01-01

    Human society has used freshwater from rivers, lakes, groundwater, and wetlands for many different urban, agricultural, and industrial activities, but in doing so has overlooked its value in supporting ecosystems. Freshwater is vital to human life and societal well-being, and thus its utilization for consumption, irrigation, and transport has long taken precedence over other commodities and services provided by freshwater ecosystems. However, there is growing recognition that functionally intact and biologically complex aquatic ecosystems provide many economically valuable services and long-term benefits to society. The short-term benefits include ecosystem goods and services, such as food supply, flood control, purification of human and industrial wastes, and habitat for plant and animal life—and these are costly, if not impossible, to replace. Long-term benefits include the sustained provision of those goods and services, as well as the adaptive capacity of aquatic ecosystems to respond to future environmental alterations, such as climate change. Thus, maintenance of the processes and properties that support freshwater ecosystem integrity should be included in debates over sustainable water resource allocation.The purpose of this report is to explain how the integrity of freshwater ecosystems depends upon adequate quantity, quality, timing, and temporal variability of water flow. Defining these requirements in a comprehensive but general manner provides a better foundation for their inclusion in current and future debates about allocation of water resources. In this way the needs of freshwater ecosystems can be legitimately recognized and addressed. We also recommend ways in which freshwater ecosystems can be protected, maintained, and restored.Freshwater ecosystem structure and function are tightly linked to the watershed or catchment of which they are a part. Because riverine networks, lakes, wetlands, and their connecting groundwaters, are literally the

  17. Different ecophysiological responses of freshwater fish to warming and acidification.

    Science.gov (United States)

    Jesus, Tiago F; Rosa, Inês C; Repolho, Tiago; Lopes, Ana R; Pimentel, Marta S; Almeida-Val, Vera M F; Coelho, Maria M; Rosa, Rui

    2018-02-01

    Future climate change scenarios predict threatening outcomes to biodiversity. Available empirical data concerning biological response of freshwater fish to climate change remains scarce. In this study, we investigated the physiological and biochemical responses of two Iberian freshwater fish species (Squalius carolitertii and the endangered S. torgalensis), inhabiting different climatic conditions, to projected future scenarios of warming (+3°C) and acidification (ΔpH=-0.4). Herein, metabolic enzyme activities of glycolytic (citrate synthase - CS, lactate dehydrogenase - LDH) and antioxidant (glutathione S-transferase, catalase and superoxide dismutase) pathways, as well as the heat shock response (HSR) and lipid peroxidation were determined. Our results show that, under current water pH, warming causes differential interspecific changes on LDH activity, increasing and decreasing its activity in S. carolitertii and in S. torgalensis, respectively. Furthermore, the synergistic effect of warming and acidification caused an increase in LDH activity of S. torgalensis, comparing with the warming condition. As for CS activity, acidification significantly decreased its activity in S. carolitertii whereas in S. torgalensis no significant effect was observed. These results suggest that S. carolitertii is more vulnerable to climate change, possibly as the result of its evolutionary acclimatization to milder climatic condition, while S. torgalensis evolved in the warmer Mediterranean climate. However, significant changes in HSR were observed under the combined warming and acidification (S. carolitertii) or under acidification (S. torgalensis). Our results underlie the importance of conducting experimental studies and address species endpoint responses under projected climate change scenarios to improve conservation strategies, and to safeguard endangered freshwater fish. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. An Underlying Common Factor, Influenced by Genetics and Unique Environment, Explains the Covariation Between Major Depressive Disorder, Generalized Anxiety Disorder, and Burnout: A Swedish Twin Study.

    Science.gov (United States)

    Mather, Lisa; Blom, Victoria; Bergström, Gunnar; Svedberg, Pia

    2016-12-01

    Depression and anxiety are highly comorbid due to shared genetic risk factors, but less is known about whether burnout shares these risk factors. We aimed to examine whether the covariation between major depressive disorder (MDD), generalized anxiety disorder (GAD), and burnout is explained by common genetic and/or environmental factors. This cross-sectional study included 25,378 Swedish twins responding to a survey in 2005-2006. Structural equation models were used to analyze whether the trait variances and covariances were due to additive genetics, non-additive genetics, shared environment, and unique environment. Univariate analyses tested sex limitation models and multivariate analysis tested Cholesky, independent pathway, and common pathway models. The phenotypic correlations were 0.71 (0.69-0.74) between MDD and GAD, 0.58 (0.56-0.60) between MDD and burnout, and 0.53 (0.50-0.56) between GAD and burnout. Heritabilities were 45% for MDD, 49% for GAD, and 38% for burnout; no statistically significant sex differences were found. A common pathway model was chosen as the final model. The common factor was influenced by genetics (58%) and unique environment (42%), and explained 77% of the variation in MDD, 69% in GAD, and 44% in burnout. GAD and burnout had additive genetic factors unique to the phenotypes (11% each), while MDD did not. Unique environment explained 23% of the variability in MDD, 20% in GAD, and 45% in burnout. In conclusion, the covariation was explained by an underlying common factor, largely influenced by genetics. Burnout was to a large degree influenced by unique environmental factors not shared with MDD and GAD.

  19. Relative invasion risk for plankton across marine and freshwater systems: examining efficacy of proposed international ballast water discharge standards.

    Directory of Open Access Journals (Sweden)

    Oscar Casas-Monroy

    Full Text Available Understanding the implications of different management strategies is necessary to identify best conservation trajectories for ecosystems exposed to anthropogenic stressors. For example, science-based risk assessments at large scales are needed to understand efficacy of different vector management approaches aimed at preventing biological invasions associated with commercial shipping. We conducted a landscape-scale analysis to examine the relative invasion risk of ballast water discharges among different shipping pathways (e.g., Transoceanic, Coastal or Domestic, ecosystems (e.g., freshwater, brackish and marine, and timescales (annual and per discharge event under current and future management regimes. The arrival and survival potential of nonindigenous species (NIS was estimated based on directional shipping networks and their associated propagule pressure, environmental similarity between donor-recipient ecosystems (based on salinity and temperature, and effects of current and future management strategies (i.e., ballast water exchange and treatment to meet proposed international biological discharge standards. Our findings show that current requirements for ballast water exchange effectively reduce invasion risk to freshwater ecosystems but are less protective of marine ecosystems because of greater environmental mismatch between source (oceanic and recipient (freshwater ecoregions. Future requirements for ballast water treatment are expected to reduce risk of zooplankton NIS introductions across ecosystem types but are expected to be less effective in reducing risk of phytoplankton NIS. This large-scale risk assessment across heterogeneous ecosystems represents a major step towards understanding the likelihood of invasion in relation to shipping networks, the relative efficacy of different invasion management regimes and seizing opportunities to reduce the ecological and economic implications of biological invasions.

  20. Diversity, distribution, and conservation status of the native freshwater fishes of the Southern United States

    Science.gov (United States)

    Melvin L. Warren; Brooks M. Burr; Stephen J. Walsh; Henry L. Bart; Robert C. Cashner; David A. Etnier; Byron J. Freeman; Bernard R. Kuhajda; Richard L. Mayden; Henry W. Robison; Stephen T. Ross; Wayne C. Starnes

    2000-01-01

    The Southeastern Fishes Council Technical Advisory Committee reviewed the diversity, distribution, and status of all native freshwater and diadromous fishes across 51 major drainage units of the Southern United States. The Southern United States supports more native fishes than any area of comparable size on the North American continent north of Mexico, but also has a...

  1. Use of artificial nests to investigate predation on freshwater turtle nests

    Science.gov (United States)

    Michael N. Marchand; John A. Litvaitis; Thomas J. Maier; Richard M. DeGraaf

    2002-01-01

    Habitat fragmentation has raised concerns that populations of generalist predators have increased and are affecting a diverse group of prey. Previous research has included the use of artificial nests to investigate the role of predation on birds that nest on or near the ground. Because predation also is a major factor limiting populations of freshwater turtles, we...

  2. Natural and anthropogenic factors affecting freshwater lenses in coastal dunes of the Adriatic coast

    Science.gov (United States)

    Cozzolino, Davide; Greggio, Nicolas; Antonellini, Marco; Giambastiani, Beatrice Maria Sole

    2017-08-01

    This study characterizes the near-shore portion of the shallow coastal aquifer included in the Ravenna area (Northern Italy) with special attention to the roles of coastal dunes as freshwater reservoirs and their buffer on groundwater salinity. The paper focuses on the presence and evolution of freshwater lenses below coastal dunes and highlights the existing differences between preserved natural dunes and dunes strongly affected by human intervention. The influence that multiple natural and anthropogenic factors, such as land cover, local drainage network, and beach erosion have on the presence, size and evolution of the freshwater lenses in the aquifer is quantified and discussed. The methodology includes multiple seasonal monitoring and sampling campaigns of physical (water level, salinity, and temperature) and chemical (major cations and anions) groundwater parameters. Results indicate that freshwater lenses, where existing, are limited in thickness (about 1-2 m). Proximity to drainage ditches as well as limited dune elevation and size do not allow the formation and permanent storage of large freshwater lenses in the aquifer below the dunes. The pine forest land cover, that replaced the typical bush or sand cover, intensifies evapotranspiration reducing net infiltration and freshwater storage. The cation species distribution in the water shows that a freshening process is ongoing in preserved natural sites with stable or advancing beaches, whereas a salinization process is ongoing in anthropogenic-impacted areas with strongly-fragmented dune systems. Currently, the thin freshwater lenses in the shallow Ravenna coastal aquifer are limited in space and have no relevance for irrigation or any other human activity. The dune-beach system, however, is the recharge zone of the coastal aquifer and its protection is important to reduce water and soil salinization, which in turn control the health of the whole coastal ecosystem.

  3. Effects of acidification on olfactory-mediated behaviour in freshwater and marine ecosystems: a synthesis.

    Science.gov (United States)

    Leduc, Antoine O H C; Munday, Philip L; Brown, Grant E; Ferrari, Maud C O

    2013-01-01

    For many aquatic organisms, olfactory-mediated behaviour is essential to the maintenance of numerous fitness-enhancing activities, including foraging, reproduction and predator avoidance. Studies in both freshwater and marine ecosystems have demonstrated significant impacts of anthropogenic acidification on olfactory abilities of fish and macroinvertebrates, leading to impaired behavioural responses, with potentially far-reaching consequences to population dynamics and community structure. Whereas the ecological impacts of impaired olfactory-mediated behaviour may be similar between freshwater and marine ecosystems, the underlying mechanisms are quite distinct. In acidified freshwater, molecular change to chemical cues along with reduced olfaction sensitivity appear to be the primary causes of olfactory-mediated behavioural impairment. By contrast, experiments simulating future ocean acidification suggest that interference of high CO2 with brain neurotransmitter function is the primary cause for olfactory-mediated behavioural impairment in fish. Different physico-chemical characteristics between marine and freshwater systems are probably responsible for these distinct mechanisms of impairment, which, under globally rising CO2 levels, may lead to strikingly different consequences to olfaction. While fluctuations in pH may occur in both freshwater and marine ecosystems, marine habitat will remain alkaline despite future ocean acidification caused by globally rising CO2 levels. In this synthesis, we argue that ecosystem-specific mechanisms affecting olfaction need to be considered for effective management and conservation practices.

  4. Numerical Study of Groundwater Flow and Salinity Distribution Cycling Controlled by Seawater/Freshwater Interaction in Karst Aquifer Using SEAWAT

    Science.gov (United States)

    Xu, Z.; Hu, B.

    2017-12-01

    The interest to predict seawater intrusion and salinity distribution in Woodville Karst Plain (WKP) has increased due to the huge challenge on quality of drinkable water and serious environmental problems. Seawater intrudes into the conduit system from submarine karst caves at Spring Creek Spring due to density difference and sea level rising, nowadays the low salinity has been detected at Wakulla Spring which is 18 km from coastal line. The groundwater discharge at two major springs and salinity distribution in this area is controlled by the seawater/freshwater interaction under different rainfall conditions: during low rainfall periods, seawater flow into the submarine spring through karst windows, then the salinity rising at the submarine spring leads to seawater further intrudes into conduit system; during high rainfall periods, seawater is pushed out by fresh water discharge at submarine spring. The previous numerical studies of WKP mainly focused on the density independent transport modeling and seawater/freshwater discharge at major karst springs, in this study, a SEAWAT model has been developed to fully investigate the salinity distribution in the WKP under repeating phases of low rainfall and high rainfall periods, the conduit system was simulated as porous media with high conductivity and porosity. The precipitation, salinity and discharge at springs were used to calibrate the model. The results showed that the salinity distribution in porous media and conduit system is controlled by the rainfall change, in general, the salinity distribution inland under low rainfall conditions is much higher and wider than the high rainfall conditions. The results propose a prediction on the environmental problem caused by seawater intrusion in karst coastal aquifer, in addition, provide a visual and scientific basis for future groundwater remediation.

  5. Assessing Potential Conservation and Restoration Areas of Freshwater Fish Fauna in the Indian River Basins.

    Science.gov (United States)

    Bhatt, Jay P; Manish, Kumar; Mehta, Rajender; Pandit, Maharaj K

    2016-05-01

    Conservation efforts globally are skewed toward terrestrial ecosystems. To date, conservation of aquatic ecosystems, in particular fish fauna, is largely neglected. We provide a country-wide assessment of Indian river ecosystems in order to identify and prioritize areas for protection and restoration of freshwater fish fauna. Using various biodiversity and anthropogenic attributes, coupled with tools of ecological modeling, we delineated areas for fish fauna conservation and restoration in the 20 major river basins of India. To do this, we used prioritization analyses and reserve selection algorithms to derive conservation value index (CVI) and vulnerability index (VI) of the river basins. CVI was estimated using endemicity, rarity, conservation value, and taxonomic singularity, while VI was estimated using a disturbance index derived from percent geographic area of the basin under human settlements, human population density, predominant land use, and total number of exotic fish species in each basin. The two indices, CVI and VI, were converted into geo-referenced maps, and each map was super-imposed onto species richness and forest cover maps, respectively. After superimposition, areas with high CVI and low VI shade intensities were delineated for conservation, while areas with high CVI and high VI shade intensities were demarcated for restoration. In view of the importance of freshwater fish for human livelihoods and consumption, and ecosystems of India's rivers, we call for urgent attention to the conservation of their fish fauna along with restoration of their degraded habitats.

  6. Predicting recovery of acidified freshwaters in Europe and Canada: an introduction

    Directory of Open Access Journals (Sweden)

    R. C. Ferrier

    2003-01-01

    Full Text Available Abstract: The RECOVER: 2010 project was designed to assess the current and future anthropogenic pressures on sensitive European freshwater ecosystems. This pan–European assessment utilised a standardised predictive modelling approach to evaluate the degree of compliance with respect to the restoration of acidified waters by 2016, as specified under the EU Water Framework Directive (WFD, and evaluated the environmental benefits of proposed UN-ECE protocols on emissions control. Between 1970 and 2000, observations and model simulations show a significant decline in acidic surface water in all regions of Europe. This demonstrated the success of policies aimed at reducing emission of acidifying compounds. The nature and extent of future regional recovery from acidification is, however, dependent upon the historical pattern of deposition, regional ecosystem characteristics and the role of confounding factors, which may delay the onset of recovery or the magnitude of response. Model predictions to 2010 and beyond emphasise the continued benefit of currently proposed reductions, as reflected by the degree of recovery of freshwater ecosystems. A key component was to link such hydrochemical recovery with ecological response, and the project aimed to evaluate this against current WFD criteria of “good status' and “reference conditions'. The RECOVER: 2010 project research has also played a major role in defining the dynamic modelling outputs which will be required to support the review of the Gothenburg Protocol within the work of the UN-ECE CLRTAP Working Group on Effects (WGE, and model outputs have been made available to a range of national agencies throughout Europe. Keyword: recovery, acidification, modelling, policy, good status, reference conditions

  7. Sulfate reduction in freshwater peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Oequist, M.

    1996-12-31

    This text consist of two parts: Part A is a literature review on microbial sulfate reduction with emphasis on freshwater peatlands, and part B presents the results from a study of the relative importance of sulfate reduction and methane formation for the anaerobic decomposition in a boreal peatland. The relative importance of sulfate reduction and methane production for the anaerobic decomposition was studied in a small raised bog situated in the boreal zone of southern Sweden. Depth distribution of sulfate reduction- and methane production rates were measured in peat sampled from three sites (A, B, and C) forming an minerotrophic-ombrotrophic gradient. SO{sub 4}{sup 2-} concentrations in the three profiles were of equal magnitude and ranged from 50 to 150 {mu}M. In contrast, rates of sulfate reduction were vastly different: Maximum rates in the three profiles were obtained at a depth of ca. 20 cm below the water table. In A it was 8 {mu}M h{sup -1} while in B and C they were 1 and 0.05 {mu}M h{sup -1}, respectively. Methane production rates, however, were more uniform across the three nutrient regimes. Maximum rates in A (ca. 1.5 {mu}g d{sup -1} g{sup -1}) were found 10 cm below the water table, in B (ca. 1.0 {mu}g d{sup -1} g{sup -1}) in the vicinity of the water table, and in C (0.75 {mu}g d{sup -1} g{sup -1}) 20 cm below the water table. In all profiles both sulfate reduction and methane production rates were negligible above the water table. The areal estimates of methane production for the profiles were 22.4, 9.0 and 6.4 mmol m{sup -2} d{sup -1}, while the estimates for sulfate reduction were 26.4, 2.5, and 0.1 mmol m{sup -2} d{sup -1}, respectively. The calculated turnover times at the sites were 1.2, 14.2, and 198.7 days, respectively. The study shows that sulfate reducing bacteria are important for the anaerobic degradation in the studied peatland, especially in the minerotrophic sites, while methanogenic bacteria dominate in ombrotrophic sites Examination

  8. CROATIAN FRESHWATER FISHERIES IN 1997

    Directory of Open Access Journals (Sweden)

    Mirko Turk

    1998-10-01

    Full Text Available Data on the production and fish catch according to species, on the surface of the fish ponds, on the means of fish catching and on the distribution of the production and the catch in 1997 is presented. The surface area used for production of fish has decreased for 836 ha or 8.40%. The total fish amount was bigger for 477 tons, or 10,52%. The feeding coefficient is 2.6 kg decreased 35% for in comparison to the bigger compared to the previous year. The amount of the fertilizer used is bigger for 37.30%. The fry carp growing ponds make up 6.50% of the total fish pond surfaces, the young carp ponds 22.04/0, and the ponds with consumption fish 70.31%. The total amount in the carp ponds was 446 kg/ha, and in the trout ponds it was 160.8 tons/ha. The most produced fish species is the carp with 79.32%, followed by the trout with 11.50%, the herbivorous fish with 4.25%, while all the other fish species make up 4.93% of the entire production. In the structure of herbivorous fish the grass carp is leading with 69,23%, followed by the big head carp with 29.74% and the silver carp with 1.03%. Compared to the previous year the production of the carp, grass carp and tench is increased. Fish catch in open waters has decreased by 5.53% in comparison to the previous year. In the production and catch of the total freshwater fish, carp made up 75.34%, herbivorous fish made up 3.89%, trout 10.66%, sheat fish, pike perch and pike 2.70% and all other fish species 7.41%. As far as the distribution of production and catch of fish is concerned, 52,80% were sold on the market, 37.94% were used for reproduction (stocking the fish farms, mortality was 1.43%, and for personal use (sports fishing 7.83%. The number of fisheries workers has decreased for 8.17%, and the production per worker is bigger for 22.25%, compared to the previous year. Average production per worker was 7.17% tons of fish.

  9. CROATIAN FRESHWATER FISHERIES IN 1996.

    Directory of Open Access Journals (Sweden)

    Mirko Turk

    1997-07-01

    Full Text Available Data on the production and fish catch according to species, on the surface of the fish ponds, on the means of fish catching and on the distribution of the production and the catch in 1996 is presented. The surface area used for production of fish has decreased by 1357 ha or 11.99%. The total fish amount has decreased by 1,921.00 tons or 29.76%. The feeding coefficient is 4 kg (33.33% bigger compared to the previous year. The amount of the fertilizer used has decreased by 18.79%. The fry carp growing ponds make up 5.99% of the total fish pond surfaces, the young carp ponds 21.13%, and the ponds with consumption fish 71.53%. The total fish amount in the carp ponds was 376 kg/ha, and in the trout ponds it was 146.6 tons/ha. The most produced fish species is the carp with 82.21 %, followed by the trout with 8.57%, the herbivorous fish with 4.78%, while all the other fish species make up 4.44% of the entire production. In the structure of herbivorous fish the grass carp is leading with 64,28%, followed by the big head carp with 26.02% and the silver carp with 9.70%. Compared to the previous year the production of the trout and tench has somewhat increased, while the production of all the other species of fish has decreased. Fish catch in open waters has increased by 19.23% in comparison to the previous year. In the production and catch of the total freshwater fish, carp made up 77.46%, the herbivorous fish made up 4.32%, trout 4.32%, sheat fish, pike perch and pike 2.99% and all other fish species 7.36%. As far as the distribution of production and catch is concerned, 46.91% were sold on the market, 39.19% were used for reproduction (stocking the fish farms, mortalities were 6.23%, and for personal use (sports fishing 7.67% was used. The number of fisheries workers has decreased by 17.75%, and the production per worker has also decreased by 26.62%, compared to the previous year. Average production per worker was 5.87 tons of fish.

  10. Sulfate reduction in freshwater peatlands

    International Nuclear Information System (INIS)

    Oequist, M.

    1996-01-01

    This text consist of two parts: Part A is a literature review on microbial sulfate reduction with emphasis on freshwater peatlands, and part B presents the results from a study of the relative importance of sulfate reduction and methane formation for the anaerobic decomposition in a boreal peatland. The relative importance of sulfate reduction and methane production for the anaerobic decomposition was studied in a small raised bog situated in the boreal zone of southern Sweden. Depth distribution of sulfate reduction- and methane production rates were measured in peat sampled from three sites (A, B, and C) forming an minerotrophic-ombrotrophic gradient. SO 4 2- concentrations in the three profiles were of equal magnitude and ranged from 50 to 150 μM. In contrast, rates of sulfate reduction were vastly different: Maximum rates in the three profiles were obtained at a depth of ca. 20 cm below the water table. In A it was 8 μM h -1 while in B and C they were 1 and 0.05 μM h -1 , respectively. Methane production rates, however, were more uniform across the three nutrient regimes. Maximum rates in A (ca. 1.5 μg d -1 g -1 ) were found 10 cm below the water table, in B (ca. 1.0 μg d -1 g -1 ) in the vicinity of the water table, and in C (0.75 μg d -1 g -1 ) 20 cm below the water table. In all profiles both sulfate reduction and methane production rates were negligible above the water table. The areal estimates of methane production for the profiles were 22.4, 9.0 and 6.4 mmol m -2 d -1 , while the estimates for sulfate reduction were 26.4, 2.5, and 0.1 mmol m -2 d -1 , respectively. The calculated turnover times at the sites were 1.2, 14.2, and 198.7 days, respectively. The study shows that sulfate reducing bacteria are important for the anaerobic degradation in the studied peatland, especially in the minerotrophic sites, while methanogenic bacteria dominate in ombrotrophic sites Examination paper. 67 refs, 6 figs, 3 tabs

  11. ECONOMIC ANALYSIS OF FRESHWATER AQUACULTURE PRODUCTION: A COMPARATIVE ANALYSIS OF DIFFERENT PRODUCTION SYSTEMS

    Directory of Open Access Journals (Sweden)

    H. Kumar

    2013-01-01

    Full Text Available India produced 8.29 million tonnes of fish in 2010-2011. The industry contributes nearly INR 200 trillion to the national economy, forming 1.4 percent of national gross domestic product (GDP and 5.4 percent of Agricultural GDP. At present, almost 84 percent of the total inland fish production, in the country is contributed by freshwater aquaculture amounting to 3.9 million tonnes in 2008-09. Further, the potential of the vast freshwater resources covering 6.7 million hectare is yet to be fully realized. The freshwater aquaculture which began as small scale activity of stocking ponds with fish seed collected from riverine sources during early fifties in rural Bengal has now transformed into a major economic activity in almost all states. There is a further need to make the sector more vibrant so as to achieve the predicted target of 15 kg per capita fish availability in the country by 2030.

  12. Perfluoroalkyl acid contamination and polyunsaturated fatty acid composition of French freshwater and marine fishes.

    Science.gov (United States)

    Yamada, Ami; Bemrah, Nawel; Veyrand, Bruno; Pollono, Charles; Merlo, Mathilde; Desvignes, Virginie; Sirot, Véronique; Oseredczuk, Marine; Marchand, Philippe; Cariou, Ronan; Antignac, Jean-Phillippe; Le Bizec, Bruno; Leblanc, Jean-Charles

    2014-07-30

    In this study, French marine and freshwater fish perfluoroalkyl acid (PFAA) contamination are presented along with their fatty acid (FA) composition to provide further elements for a risk/benefit balance of fish consumption to be assessed. The 29 most consumed marine fish species were collected in four metropolitan French coastal areas in 2004 to constitute composite samples. Geographical differences in terms of consumed species and contamination level were taken into account. Three hundred and eighty-seven composite samples corresponding to 16 freshwater fish species collected between 2008 and 2010 in the six major French rivers or their tributaries were selected among the French national agency for water and aquatic environments freshwater fish sample library. The raw edible parts were analyzed for FA composition and PFAA contamination. Results show that freshwater fishes are more contaminated by PFAAs than marine fishes and do not share the same contamination profile. Freshwater fish contamination is mostly driven by perfluorooctane sulfonate (PFOS) (75%), whereas marine fish contamination is split between perfluorooctanoic acid (PFOA) (24%), PFOS (20%), perfluorohexanoic acid (PFHxA) (15%), perfluoropentanoic acid (PFHpA) (11%), and perfluorobutanoic acid (PFBA) (11%). Common carp, pike-perch, European perch, thicklip grey mullet, and common roach presented the most unfavorable balance profile due to their high level of PFAAs and low level of n-3 long-chain polyunsaturated fatty acids (LC-PUFAs). These data could be used, if needed, in an updated opinion on fish consumption that takes into account PFAA contamination.

  13. Improved protocols to accelerate the assembly of DNA barcode reference libraries for freshwater zooplankton.

    Science.gov (United States)

    Elías-Gutiérrez, Manuel; Valdez-Moreno, Martha; Topan, Janet; Young, Monica R; Cohuo-Colli, José Angel

    2018-03-01

    Currently, freshwater zooplankton sampling and identification methodologies have remained virtually unchanged since they were first established in the beginning of the XX century. One major contributing factor to this slow progress is the limited success of modern genetic methodologies, such as DNA barcoding, in several of the main groups. This study demonstrates improved protocols which enable the rapid assessment of most animal taxa inhabiting any freshwater system by combining the use of light traps, careful fixation at low temperatures using ethanol, and zooplankton-specific primers. We DNA-barcoded 2,136 specimens from a diverse array of taxonomic assemblages (rotifers, mollusks, mites, crustaceans, insects, and fishes) from several Canadian and Mexican lakes with an average sequence success rate of 85.3%. In total, 325 Barcode Index Numbers (BINs) were detected with only three BINs (two cladocerans and one copepod) shared between Canada and Mexico, suggesting a much narrower distribution range of freshwater zooplankton than previously thought. This study is the first to broadly explore the metazoan biodiversity of freshwater systems with DNA barcodes to construct a reference library that represents the first step for future programs which aim to monitor ecosystem health, track invasive species, or improve knowledge of the ecology and distribution of freshwater zooplankton.

  14. Oil spills into freshwater environments-literature review of fate and effects

    International Nuclear Information System (INIS)

    Taylor, E.; Owens, E.; Craig, A.; Steen, A.; Fritz, D.

    1993-01-01

    A literature search (1984--1992) was performed to summarize the environmental and human health effects of inlands spills. Over 100 major spills that affected freshwater environments were reported through the Emergency Response Notification System (ERNS) in 1991--1992 alone. Spills from pipelines outnumber all other sources combined. The oil types involved are about equally distributed between non-persistent oils and crude. Small rivers, streams, and creeks are the habitats into which most freshwater spills occur. Cleanup of stranded oil, rather than protection or recovery of floating oil, is the norm in most situations because stranding on river and lake banks often occurs before response is possible. The prediction of spill movement commonly is simpler for freshwater spills because freshwater bodies are relatively small and commonly have strong uni-directional flow; however, fast flow in rivers and streams and turnover in cooling lakes serve to distribute oil throughout the water column. Impacts to the environment, through food web structures or groundwater, may persist for months following a spill but seldom persist for years, unlike marine coastal impacts. Chronic impacts of oil spills into freshwater are rarely documented and these impacts are difficult to separate from effects of other hydrocarbons in the environment

  15. Evaluation of Drought Implications on Ecosystem Services: Freshwater Provisioning and Food Provisioning in the Upper Mississippi River Basin.

    Science.gov (United States)

    Li, Ping; Omani, Nina; Chaubey, Indrajeet; Wei, Xiaomei

    2017-05-08

    Drought is one of the most widespread extreme climate events with a potential to alter freshwater availability and related ecosystem services. Given the interconnectedness between freshwater availability and many ecosystem services, including food provisioning, it is important to evaluate the drought implications on freshwater provisioning and food provisioning services. Studies about drought implications on streamflow, nutrient loads, and crop yields have been increased and these variables are all process-based model outputs that could represent ecosystem functions that contribute to the ecosystem services. However, few studies evaluate drought effects on ecosystem services such as freshwater and food provisioning and quantify these services using an index-based ecosystem service approach. In this study, the drought implications on freshwater and food provisioning services were evaluated for 14 four-digit HUC (Hydrological Unit Codes) subbasins in the Upper Mississippi River Basin (UMRB), using three drought indices: standardized precipitation index ( SPI ), standardized soil water content index ( SSWI ), and standardized streamflow index ( SSI ). The results showed that the seasonal freshwater provisioning was highly affected by the precipitation deficits and/or surpluses in summer and autumn. A greater importance of hydrological drought than meteorological drought implications on freshwater provisioning was evident for the majority of the subbasins, as evidenced by higher correlations between freshwater provisioning and SSI 12 than SPI 12. Food provisioning was substantially affected by the precipitation and soil water deficits during summer and early autumn, with relatively less effect observed in winter. A greater importance of agricultural drought effects on food provisioning was evident for most of the subbasins during crop reproductive stages. Results from this study may provide insights to help make effective land management decisions in responding to

  16. Can switching fuels save water? A life cycle quantification of freshwater consumption for Texas coal- and natural gas-fired electricity

    International Nuclear Information System (INIS)

    Grubert, Emily A; Beach, Fred C; Webber, Michael E

    2012-01-01

    Thermal electricity generation is a major consumer of freshwater for cooling, fuel extraction and air emissions controls, but the life cycle water impacts of different fossil fuel cycles are not well understood. Much of the existing literature relies on decades-old estimates for water intensity, particularly regarding water consumed for fuel extraction. This work uses contemporary data from specific resource basins and power plants in Texas to evaluate water intensity at three major stages of coal and natural gas fuel cycles: fuel extraction, power plant cooling and power plant emissions controls. In particular, the water intensity of fuel extraction is quantified for Texas lignite, conventional natural gas and 11 unconventional natural gas basins in Texas, including major second-order impacts associated with multi-stage hydraulic fracturing. Despite the rise of this water-intensive natural gas extraction method, natural gas extraction appears to consume less freshwater than coal per unit of energy extracted in Texas because of the high water intensity of Texas lignite extraction. This work uses new resource basin and power plant level water intensity data to estimate the potential effects of coal to natural gas fuel switching in Texas’ power sector, a shift under consideration due to potential environmental benefits and very low natural gas prices. Replacing Texas’ coal-fired power plants with natural gas combined cycle plants (NGCCs) would reduce annual freshwater consumption in the state by an estimated 53 billion gallons per year, or 60% of Texas coal power’s water footprint, largely due to the higher efficiency of NGCCs. (letter)

  17. Major Links.

    Science.gov (United States)

    Henderson, Tona

    1995-01-01

    Provides electronic mail addresses for resources and discussion groups related to the following academic majors: art, biology, business, chemistry, computer science, economics, health sciences, history, literature, math, music, philosophy, political science, psychology, sociology, and theater. (AEF)

  18. Major Roads

    Data.gov (United States)

    Minnesota Department of Natural Resources — This data set contains roadway centerlines for major roads (interstates and trunk highways) found on the USGS 1:24,000 mapping series. These roadways are current...

  19. Walking the tightrope: trends in African freshwater systematic ichthyology.

    Science.gov (United States)

    Skelton, P H; Swartz, E R

    2011-12-01

    Africa is blessed with an abundance and rich diversity of freshwater fishes, reflecting its Gondwanan history and geographical position astride the equator. Africa is, however, relatively poorly serviced scientifically, in this respect presenting a challenge to the tension between conserving biodiversity and sustainable development. Biosystematics has experienced several paradigm shifts in the past half century, including the rise of cladistics and more recently the adoption of molecular DNA applications to taxonomy and phylogeny and the assembly and manipulation of large data sets in an era of major development of bioinformatics. The richness of African biodiversity is a magnet to the global systematic community that, to a degree, offsets the disadvantage of an impoverished indigenous scientific capacity. Conservation biology, however, is rooted more closely to the local situation and therefore requires indigenous taxonomic services that are inevitably scarce. Balancing this network of tensions between scientific knowledge generation and application is like walking a tightrope for existing African scientific resources, and to cope it is essential to embrace modern innovative approaches such as barcoding to identify organisms. This paper considers the historical development of African freshwater ichthyology, presents a suite of recent examples illustrating trends in systematic ichthyology in Africa and draws conclusions to suggest that both traditional and new-age approaches to taxonomy are necessary for a complete understanding and appreciation of African freshwater fish diversity and its conservation. The chosen examples also suggest that the tensions between the approaches can be effectively managed provided exponents work collaboratively. The emerging evidence indicates that the combined skills and insight of complex scientific teams including systematists, ecologists, molecular biologists and earth scientists are needed to resolve the deep complexity of

  20. Contaminants in the Greenland terrestrial and freshwater environment. National assessment

    International Nuclear Information System (INIS)

    Riget, F.; Aastrup, P.; Dietz, R.

    1997-01-01

    The present report reviews the available information on heavy metals, persistent organic pollutants and radioactivity in the Greenland freshwater and terrestrial environments. Levels in lake sediments, soil, humus and organisms are presented, spatial and temporal trends are discussed and where possible also biological effects. Many of the contaminants that occur in the Greenland environment originate from distant sources outside of the region, and are transported to the Arctic via three major pathways - atmospheric, terrestrial/freshwater and marine. The main sources of pollution in Greenland is considered to be the industrialization of Eurasia. Pollutants are mainly. The organochlorine levels in Greenland char are typically in the low range compared to values reported from Canada. The Greenland sediment samples showed all organochlorine values below the detection limits of 0.1 μg/kg dry weight, thus being among the lowest contaminated sediments within the Arctic. The total content of PAH in the Greenland sediment samples ranged between 78-635 μ3 g/kg dry wight, with a geometric mean of 178 μg/kg, comparable to or lower than reported values from other arctic countries. The lowest concentrations of anthropogenic radionuclides in the Greenland terrestrial and freshwater environment are found in the northern parts of Greenland and the highest in the south western parts. The main source of anthropogenic radioactivity is nuclear weapons testing in the atmosphere and the fallout from this activity is closely related to the amounts of precipitation. The predominant foodchain in the Arctic with regard to transport of radiocaesium to man is: Lichen-reindeer-man. Although the doses from the terrestrial foodchain are 20 times higher than those received from the marine foodchain, they are not considered to be of any relevance for the human health in Greenland. 4 appendices contain experimental results. (EG)

  1. Threatened and Endangered Freshwater Fish and Mussel Species Richness

    Data.gov (United States)

    U.S. Environmental Protection Agency — These data represent predicted current distributions of all US listed Threatened and Endangered freshwater fish and freshwater mussels in the Middle-Atlantic region....

  2. Predicting freshwater habitat integrity using land-use surrogates

    CSIR Research Space (South Africa)

    Amis, MA

    2007-04-01

    Full Text Available Freshwater biodiversity is globally threatened due to human disturbances, but freshwater ecosystems have been accorded less protection than their terrestrial and marine counterparts. Few criteria exist for assessing the habitat integrity of rivers...

  3. CROATIAN FRESHWATER FISHERIES IN 1994

    Directory of Open Access Journals (Sweden)

    Mirko Turk

    1995-09-01

    Full Text Available Data on the production and catch of fish according to species, on the surface of the fish ponds, on the means of fish catching and on the distribution of the product and catch in 1994 is presented. The surface area used for production of fish has decreased by 274 ha or 2,51%. The total amount of fish has decreased by 1.263 tons or 14,78%. The highest production of fish was reached by the fish farm Donji Miholjac with 1.231 kg/ha. The feeding coefficient is 3,10 kg. Only on one fish farm was the feeding coefficient less than 2.0 kg (1,40 and on two large farms this coefficient was greater than 5,00 kg. The main fish food is still wheat followed by corn. The amount of fertilizer used was decreased by 14,40%. The fry carp growing ponds make up 0,92% of the surface area of the entire fish farm, the young carp ponds 21,77% and the culturing ponds for consumption fish 76,55%. The total amount of fish in the carp ponds was 660 kg/ha, and in the trout ponds it was 123.4 tons/ha. The carp is the highest produced fish with 80, 35%, then the herbivorous fish with 5,65 and all other fish make up 14% of the total production. In the structure of herbivorous fish the grass carp is leading with 54, 70%, followed by the big head carp with 25,54% and the silver carp with 19,76%. In comparison with the previous year the production of "all other fish- has significantly increased (287%, and sheat fish 18,90%, while the production of trench has decreased (71%. Fish catch in open waters has increased by 20,57% in comparison to the previous year. Carp made up 78,07% of the total production and catch of freshwater fish, the herbivorous fish made up 5,40%, trout 4,38%, the sheat fish, pike perch and pike 2,86% and all other fish species 9,28%. As far as the distribution of production and catch, 51,60% were sold on the market, 37,54% were used for reproduction (stocking the fish farms , mortalities were 6,35% and for personal use (sports fishing 4,50% was used. The number

  4. Experimental study of a sustainable hybrid system for thermoelectric generation and freshwater production

    Science.gov (United States)

    de Souza, Gabriel Fernandes; Tan, Lippong; Singh, Baljit; Ding, Lai Chet; Date, Abhijit

    2017-04-01

    The paper presents a sustainable hybrid system, which is capable of generating electricity and producing freshwater from seawater using low grade heat source. This proposed system uses low grade heat that can be supplied from solar radiation, industrial waste heat or any other waste heat sources where the temperature is less than 150°C. The concept behind this system uses the Seebeck effect for thermoelectricity generation via incorporating the low boiling point of seawater under sub-atmospheric ambient pressure. A lab-test prototype of the proposed system was built and experimentally tested in RMIT University. The prototype utilised four commercial available thermoelectric generators (Bi2Te3) and a vacuum vessel to achieve the simultaneous production of electricity and freshwater. The temperature profiles, thermoelectric powers and freshwater productions were determined at several levels of salinity to study the influence of different salt concentrations. The theoretical description of system design and experimental results were analysed and discussed in detailed. The experiment results showed that 0.75W of thermoelectricity and 404g of freshwater were produced using inputs of 150W of simulated waste heat and 500g of 3% saline water. The proposed hybrid concept has demonstrated the potential to become the future sustainable system for electricity and freshwater productions.

  5. Observations and analytical modeling of freshwater and rainwater lenses in coastal dune systems

    NARCIS (Netherlands)

    Stuijfzand, Pieter

    2016-01-01

    Observations are reported on (i) groundwater recharge rates under various types of vegetation as measured with megalysimeters in the dunes, (ii) freshwater lenses along the Dutch North Sea coast in the early 1900s, and (iii) rainwater lenses that develop on top of laterally migrating,

  6. Ammonium addition inhibits 13C-methane incorporation into methanotroph membrane lipids in a freshwater sediment

    NARCIS (Netherlands)

    Nold, s.c.; Boschker, H.T.S.; Pel, R.; Laanbroek, H.J.

    1999-01-01

    To investigate the effect of ammonium addition on the species composition and activity of freshwater methane oxidizing bacteria, intact sediment cores were labeled with (CH4)-C-13 and incubated under ambient and elevated ammonium concentrations. After 7 days, methanotroph activity was assessed by

  7. Ammonium addition inhibits 13C-methane incorporation into methanotroph membrane lipids in a freshwater sediment

    NARCIS (Netherlands)

    Nold, S.C.; Boschker, H.T.S.; Pel, R.; Laanbroek, H.J.

    1999-01-01

    To investigate the effect of ammonium addition on the species composition and activity of freshwater methane oxidizing bacteria, intact sediment cores were labeled with 13CH4 and incubated under ambient and elevated ammonium concentrations. After 7 days, methanotroph activity was assessed by

  8. Freshwater crayfish invasions in South Africa: past, present and ...

    African Journals Online (AJOL)

    Freshwater crayfish invasions have been studied around the world, but less so in Africa, a continent devoid of native freshwater crayfish. The present study reviews historical and current information on alien freshwater crayfish species introduced into South Africa and aims to indicate which areas are at risk from invasion.

  9. Scale-based freshwater conservation planning: towards protecting freshwater biodiversity in KwaZulu-Natal, South Africa

    CSIR Research Space (South Africa)

    Rivers-Moore, NA

    2011-01-01

    Full Text Available River systems have strong linear linkages and require innovative solutions to capture these linkages from aquatic conservation planners. The authors applied an approach to freshwater conservation planning to freshwater ecosystems of Kwa...

  10. Dactylobiotus luci , a new freshwater tardigrade (Eutardigrada ...

    African Journals Online (AJOL)

    A new freshwater eutardigrade, Dactylobiotus luci sp. nov., is described from a permanent marsh pool (Zaphania's Pool) at 4225 m elevation in the Alpine zone of the Rwenzori Mountains, Uganda. The new species is most similar to D. dervizi Biserov, 1998 in the shape of the egg processes, absence of papillae and ...

  11. Effects of Pollution on Freshwater Invertebrates.

    Science.gov (United States)

    Buikema, A. L., Jr.; Herricks, E. E.

    1978-01-01

    Presents a literature review of the effects of pollution on freshwater invertebrates, covering publications of 1976-77. Some of the areas covered are: (1) toxicant effects on invertebrates; (2) microcosm and community effects, and (3) biological control of aquatic life. A list of 123 references is also presented. (HM)

  12. 2008 NWFSC Tidal Freshwater Genetics Results

    Energy Technology Data Exchange (ETDEWEB)

    David Teel

    2009-05-01

    Genetic Analysis of Juvenile Chinook Salmon for inclusion in 'Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2008. Annual Report to Bonneville Power Administration, Contract DE-AC05-76RL01830.'

  13. Methane emission from tidal freshwater marshes

    NARCIS (Netherlands)

    Van der Nat, F.J.; Middelburg, J.J.

    2000-01-01

    In two tidal freshwater marshes, methane emission, production and accumulation in the pore-water have been studied. The two sites differ in their dominant vegetation, i.e., reed and bulrush, and in their heights above sea level. The reed site was elevated in relation to the bulrush site and had

  14. Wnt signaling and polarity in freshwater sponges.

    Science.gov (United States)

    Windsor Reid, Pamela J; Matveev, Eugueni; McClymont, Alexandra; Posfai, Dora; Hill, April L; Leys, Sally P

    2018-02-02

    The Wnt signaling pathway is uniquely metazoan and used in many processes during development, including the formation of polarity and body axes. In sponges, one of the earliest diverging animal groups, Wnt pathway genes have diverse expression patterns in different groups including along the anterior-posterior axis of two sponge larvae, and in the osculum and ostia of others. We studied the function of Wnt signaling and body polarity formation through expression, knockdown, and larval manipulation in several freshwater sponge species. Sponge Wnts fall into sponge-specific and sponge-class specific subfamilies of Wnt proteins. Notably Wnt genes were not found in transcriptomes of the glass sponge Aphrocallistes vastus. Wnt and its signaling genes were expressed in archaeocytes of the mesohyl throughout developing freshwater sponges. Osculum formation was enhanced by GSK3 knockdown, and Wnt antagonists inhibited both osculum development and regeneration. Using dye tracking we found that the posterior poles of freshwater sponge larvae give rise to tissue that will form the osculum following metamorphosis. Together the data indicate that while components of canonical Wnt signaling may be used in development and maintenance of osculum tissue, it is likely that Wnt signaling itself occurs between individual cells rather than whole tissues or structures in freshwater sponges.

  15. Heliozoa from Nigeria | Wujek | Tropical Freshwater Biology

    African Journals Online (AJOL)

    A total of seven scaled protistans were observed from four freshwater sites in Nigeria. They include the holiozoan genera Acanthocystis, Polyplacocystis, Pterocystis, and Raphidiophrys. All are new records for Africa. KEY WORDS: Heliozoa, Protozoa, Acanthocystis, Polyplacocystis, Pterocystis, Raphidiophrys Tropical ...

  16. Monitoring endangered freshwater biodiversity using environmental DNA

    DEFF Research Database (Denmark)

    Thomsen, Philip Francis; Kielgast, Jos; Iversen, Lars Lønsmann

    2012-01-01

    Freshwater ecosystems are among the most endangered habitats on Earth, with thousands of animal species known to be threatened or already extinct. Reliable monitoring of threatened organisms is crucial for data-driven conservation actions but remains a challenge owing to nonstandardized methods t...

  17. 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…

  18. River and wetland classifications for freshwater conservation ...

    African Journals Online (AJOL)

    River and wetland classifications for freshwater conservation planning in KwaZulu-Natal, South Africa. ... regional- or provincial-scale conservation planning. The hierarchical structure of the classifications provides scope for finer resolution, by the addition of further levels, for application at a sub-regional or municipal scale.

  19. Novel Synechococcus genomes reconstructed from freshwater reservoirs

    Czech Academy of Sciences Publication Activity Database

    Cabello-Yeves, P.J.; Haro-Moreno, J.M.; Martin-Cuadrado, A.B.; Ghai, Rohit; Picazo, A.; Camacho, A.; Rodriguez-Valera, F.

    2017-01-01

    Roč. 8, June (2017), č. článku 1151. ISSN 1664-302X R&D Projects: GA ČR(CZ) GA17-04828S Institutional support: RVO:60077344 Keywords : Synechococcus * picocyanobacteria * freshwater reservoirs * metagenomics * abundance Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 4.076, year: 2016

  20. Microplastic effect thresholds for freshwater benthic macroinvertebrates

    NARCIS (Netherlands)

    Redondo Hasselerharm, P.E.; Dede Falahudin, Dede; Peeters, E.T.H.M.; Koelmans, A.A.

    2018-01-01

    Now that microplastics have been detected in lakes, rivers and estuaries all over the globe, evaluating their effects on biota has become an urgent research priority. This is the first study that aims at determining the effect thresholds for a battery of six freshwater benthic macroinvertebrates

  1. 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

  2. Urban microbial ecology of a freshwater estuary of Lake Michigan.

    Science.gov (United States)

    Fisher, Jenny C; Newton, Ryan J; Dila, Deborah K; McLellan, Sandra L

    Freshwater estuaries throughout the Great Lakes region receive stormwater runoff and riverine inputs from heavily urbanized population centers. While human and animal feces contained in this runoff are often the focus of source tracking investigations, non-fecal bacterial loads from soil, aerosols, urban infrastructure, and other sources are also transported to estuaries and lakes. We quantified and characterized this non-fecal urban microbial component using bacterial 16S rRNA gene sequences from sewage, stormwater, rivers, harbor/estuary, and the lake surrounding Milwaukee, WI, USA. Bacterial communities from each of these environments had a distinctive composition, but some community members were shared among environments. We used a statistical biomarker discovery tool to identify the components of the microbial community that were most strongly associated with stormwater and sewage to describe an "urban microbial signature," and measured the presence and relative abundance of these organisms in the rivers, estuary, and lake. This urban signature increased in magnitude in the estuary and harbor with increasing rainfall levels, and was more apparent in lake samples with closest proximity to the Milwaukee estuary. The dominant bacterial taxa in the urban signature were Acinetobacter, Aeromonas , and Pseudomonas , which are organisms associated with pipe infrastructure and soil and not typically found in pelagic freshwater environments. These taxa were highly abundant in stormwater and sewage, but sewage also contained a high abundance of Arcobacter and Trichococcus that appeared in lower abundance in stormwater outfalls and in trace amounts in aquatic environments. Urban signature organisms comprised 1.7% of estuary and harbor communities under baseflow conditions, 3.5% after rain, and >10% after a combined sewer overflow. With predicted increases in urbanization across the Great Lakes, further alteration of freshwater communities is likely to occur with potential

  3. Urban microbial ecology of a freshwater estuary of Lake Michigan

    Directory of Open Access Journals (Sweden)

    Jenny C. Fisher

    2015-07-01

    Full Text Available Abstract Freshwater estuaries throughout the Great Lakes region receive stormwater runoff and riverine inputs from heavily urbanized population centers. While human and animal feces contained in this runoff are often the focus of source tracking investigations, non-fecal bacterial loads from soil, aerosols, urban infrastructure, and other sources are also transported to estuaries and lakes. We quantified and characterized this non-fecal urban microbial component using bacterial 16S rRNA gene sequences from sewage, stormwater, rivers, harbor/estuary, and the lake surrounding Milwaukee, WI, USA. Bacterial communities from each of these environments had a distinctive composition, but some community members were shared among environments. We used a statistical biomarker discovery tool to identify the components of the microbial community that were most strongly associated with stormwater and sewage to describe an “urban microbial signature,” and measured the presence and relative abundance of these organisms in the rivers, estuary, and lake. This urban signature increased in magnitude in the estuary and harbor with increasing rainfall levels, and was more apparent in lake samples with closest proximity to the Milwaukee estuary. The dominant bacterial taxa in the urban signature were Acinetobacter, Aeromonas, and Pseudomonas, which are organisms associated with pipe infrastructure and soil and not typically found in pelagic freshwater environments. These taxa were highly abundant in stormwater and sewage, but sewage also contained a high abundance of Arcobacter and Trichococcus that appeared in lower abundance in stormwater outfalls and in trace amounts in aquatic environments. Urban signature organisms comprised 1.7% of estuary and harbor communities under baseflow conditions, 3.5% after rain, and >10% after a combined sewer overflow. With predicted increases in urbanization across the Great Lakes, further alteration of freshwater communities is

  4. Urban microbial ecology of a freshwater estuary of Lake Michigan

    Science.gov (United States)

    Fisher, Jenny C.; Newton, Ryan J.; Dila, Deborah K.

    2015-01-01

    Freshwater estuaries throughout the Great Lakes region receive stormwater runoff and riverine inputs from heavily urbanized population centers. While human and animal feces contained in this runoff are often the focus of source tracking investigations, non-fecal bacterial loads from soil, aerosols, urban infrastructure, and other sources are also transported to estuaries and lakes. We quantified and characterized this non-fecal urban microbial component using bacterial 16S rRNA gene sequences from sewage, stormwater, rivers, harbor/estuary, and the lake surrounding Milwaukee, WI, USA. Bacterial communities from each of these environments had a distinctive composition, but some community members were shared among environments. We used a statistical biomarker discovery tool to identify the components of the microbial community that were most strongly associated with stormwater and sewage to describe an “urban microbial signature,” and measured the presence and relative abundance of these organisms in the rivers, estuary, and lake. This urban signature increased in magnitude in the estuary and harbor with increasing rainfall levels, and was more apparent in lake samples with closest proximity to the Milwaukee estuary. The dominant bacterial taxa in the urban signature were Acinetobacter, Aeromonas, and Pseudomonas, which are organisms associated with pipe infrastructure and soil and not typically found in pelagic freshwater environments. These taxa were highly abundant in stormwater and sewage, but sewage also contained a high abundance of Arcobacter and Trichococcus that appeared in lower abundance in stormwater outfalls and in trace amounts in aquatic environments. Urban signature organisms comprised 1.7% of estuary and harbor communities under baseflow conditions, 3.5% after rain, and >10% after a combined sewer overflow. With predicted increases in urbanization across the Great Lakes, further alteration of freshwater communities is likely to occur with

  5. HESS Opinions: A planetary boundary on freshwater use is misleading

    Science.gov (United States)

    Heistermann, Maik

    2017-07-01

    In 2009, a group of prominent Earth scientists introduced the planetary boundaries (PB) framework: they suggested nine global control variables, and defined corresponding thresholds which, if crossed, could generate unacceptable environmental change. The concept builds on systems theory, and views Earth as a complex adaptive system in which anthropogenic disturbances may trigger non-linear, abrupt, and irreversible changes at the global scale, and push the Earth system outside the stable environmental state of the Holocene. While the idea has been remarkably successful in both science and policy circles, it has also raised fundamental concerns, as the majority of suggested processes and their corresponding planetary boundaries do not operate at the global scale, and thus apparently lack the potential to trigger abrupt planetary changes. This paper picks up the debate with specific regard to the planetary boundary on global freshwater use. While the bio-physical impacts of excessive water consumption are typically confined to the river basin scale, the PB proponents argue that water-induced environmental disasters could build up to planetary-scale feedbacks and system failures. So far, however, no evidence has been presented to corroborate that hypothesis. Furthermore, no coherent approach has been presented to what extent a planetary threshold value could reflect the risk of regional environmental disaster. To be sure, the PB framework was revised in 2015, extending the planetary freshwater boundary with a set of basin-level boundaries inferred from environmental water flow assumptions. Yet, no new evidence was presented, either with respect to the ability of those basin-level boundaries to reflect the risk of regional regime shifts or with respect to a potential mechanism linking river basins to the planetary scale. So while the idea of a planetary boundary on freshwater use appears intriguing, the line of arguments presented so far remains speculative and

  6. Remobilisation of uranium from contaminated freshwater sediments by bioturbation

    Energy Technology Data Exchange (ETDEWEB)

    Lagauzere, S.; Bonzom, J.M. [Institut de Radioprotection et de Surete Nucleaire (IRSN), Saint-Paul-Lez-Durance (France). Lab. d' Ecotoxicologie des Radionucleides; Motelica-Heino, M. [Orleans Univ. (France). ISTO; Viollier, E. [Paris Diderot Univ., Paris (France). Inst. de Physique du Globe de Paris; Stora, G. [Aix-Marseille Univ., Marseille (France). Mediterranean Inst. of Oceanography (MIO)

    2014-07-01

    Benthic macro-invertebrate bioturbation can influence the remobilisation of uranium (U) initially associated with freshwater sediments, resulting in a high release of this pollutant through the overlying water column. Given the potential negative effects on aquatic biocenosis and the global ecological risk, it appears crucial to improve our current knowledge concerning the biogeochemical behaviour of U in sediments. The present study aimed to assess the biogeochemical modifications induced by Tubifex tubifex (Annelida, Clitellata, Tubificidae) bioturbation within the sediment in order to explain such a release of U. To reach this goal, U distribution between solid and solute phases of a reconstructed benthic system (i.e. in mesocosms) inhabited or not by T. tubifex worms was assessed in a 12-day laboratory experiment. Thanks notably to fine-resolution (mm-scale) measurements (e.g. ''diffusive equilibrium in thin-films'' DET gel probes for porewater, bioaccumulation in worms) of U and main chemical species (iron, sulfate, nitrate and nitrite), this work (i) confirmed that the removal of bottom sediment particles to the surface through the digestive tract of worms greatly favoured oxidative loss of U in the water column, and (ii) demonstrated that both U contamination and bioturbation of T. tubifex substantially influenced major microbial-driven biogeochemical reactions in sediments (e.g. stimulation of denitrification, sulfate reduction and iron dissolutive reduction). This study provides the first demonstration of biogeochemical modifications induced by bioturbation in freshwater U-contaminated sediments.

  7. Source, Use, and Disposition of Freshwater in Puerto Rico, 2005

    Science.gov (United States)

    Molina-Rivera, Wanda L.

    2010-01-01

    Water diverted from streams and pumped from wells constitutes the main sources of water for the 78 municipios of the Commonwealth of Puerto Rico. A better understanding is needed about water-use patterns, particularly about the amount of water used, where and how this water is used and disposed, and how human activities impact water resources. Irrigation practices, indoor and outdoor household uses, industrial uses, and commercial and mining withdrawals affect reservoirs, streams, and aquifers. Accurate and accessible water information for Puerto Rico is critical to ensure that water managers have the ability to protect and conserve this natural resource. The population of Puerto Rico increased 15 percent, from 3.4 million in 1985 to 3.9 million people 2005 and resulted in an increased demand for freshwater, mostly for the public-supply water use category. Almost 99 percent of the residents in Puerto Rico were served by public-supply water systems in 2005. One of the major challenges that water managers confront is the need to provide sufficient freshwater availability in the densely populated areas. Public-supply water is provided by the Puerto Rico Aqueducts and Sewers Authority (PRASA) and by non-PRASA systems. Non-PRASA systems refer to community-operated water systems (water systems that serve a rural or suburban housing area).

  8. /sup 60/Co accumulation by freshwater plants under natural conditions

    Energy Technology Data Exchange (ETDEWEB)

    Trapeznikov, A V; Trapeznikova, V N [AN SSSR, Sverdlovsk. Inst. Ehkologii Rastenij i Zhivotnykh

    1979-03-01

    In search for effective bioindicators of radioactive contamination of cooler-reservoirs in atomic power plants the accumulation of /sup 60/Co by four species of higher aquatic plants most widely distributed in the Urals was studied, namely by Elodea canadensis, Ceratophyllum demersum, Lemna minor and Potamogeton pectinatus. It is shown that such plants as Ceratophyllum demersum and Elodea canadensis having the accumulation coefficients of /sup 60/Co 33,500 and 21,500, respectively, can be recommended as bioindicators of this radionuclide in reservoirs contaminated with radioactive cobalt.

  9. On 60Co accumulation by freshwater plants under natural conditions

    International Nuclear Information System (INIS)

    Trapeznikov, A.V.; Trapeznikova, V.N.

    1979-01-01

    In search for effective bioindicators of radioactive contamination of cooler-reservoirs in atomic power plants the accumulation of 60 Co by four species of higher aquatic plants most widely distributed in the Urals was studied, namely by Elodea canadensis, Ceratophyllum demersum, Lemna minor and Potamogeton pectinatus. It is shown that such plants as Ceratophyllum demersum and Elodea canadensis having the accumulation coefficients of 60 Co 33,500 and 21,500, respectively, can be recommended as bioindicators of this radionuclide in reservoirs contaminated with radioactive cobalt

  10. Freshwater flux to Sermilik Fjord, SE Greenland

    Directory of Open Access Journals (Sweden)

    S. H. Mernild

    2010-10-01

    Full Text Available Terrestrial inputs of freshwater flux to Sermilik Fjord, SE Greenland, were estimated, indicating ice discharge to be the dominant source of freshwater. A freshwater flux of 40.4 ± 4.9×109 m3 y−1 was found (1999–2008, with an 85% contribution originated from ice discharge (65% alone from Helheim Glacier, 11% from terrestrial surface runoff (from melt water and rain, 3% from precipitation at the fjord surface area, and 1% from subglacial geothermal and frictional melting due to basal ice motion. The results demonstrate the dominance of ice discharge as a primary mechanism for delivering freshwater to Sermilik Fjord. Time series of ice discharge for Helheim Glacier, Midgård Glacier, and Fenris Glacier were calculated from satellite-derived average surface velocity, glacier width, and estimated ice thickness, and fluctuations in terrestrial surface freshwater runoff were simulated based on observed meteorological data. These simulations were compared and bias corrected against independent glacier catchment runoff observations. Modeled runoff to Sermilik Fjord was variable, ranging from 2.9 ± 0.4×109 m3 y−1 in 1999 to 5.9 ± 0.9×109 m3 y−1 in 2005. The sub-catchment runoff of the Helheim Glacier region accounted for 25% of the total runoff to Sermilik Fjord. The runoff distribution from the different sub-catchments suggested a strong influence from the spatial variation in glacier coverage, indicating high runoff volumes, where glacier cover was present at low elevations.

  11. Biotransformation of gabapentin in surface water matrices under different redox conditions and the occurrence of one major TP in the aquatic environment.

    Science.gov (United States)

    Henning, Nina; Kunkel, Uwe; Wick, Arne; Ternes, Thomas A

    2018-06-15

    Laboratory-scale incubation experiments in water/sediment systems were conducted to test the transformation behavior of the anticonvulsant gabapentin (GBP) under different environmental conditions (aerobic, anaerobic, with abiotic controls). GBP was transformed by biological processes as it was eliminated quickly under aerobic conditions (dissipation time 50% of initial concentration (DT 50 ): 2-7 days) whereas no decrease was observed under anaerobic conditions. Measurements via high resolution mass spectrometry (LC-Orbitrap-MS) revealed eight biological transformation products (TPs). Three of them were identified with reference standards (GBP-Lactam, TP186, TP213), while for the other five TPs tentative structures were proposed from information by MS 2 /MS 3 experiments. Furthermore, the quantitatively most relevant TP GBP-Lactam was formed via intramolecular amidation (up to 18% of initial GBP concentration). Incubation experiments with GBP-Lactam revealed a higher stability against biotic degradation (DT 50 : 12 days) in contrast to GBP, while it was stable under anaerobic and abiotic conditions. Besides GBP, GBP-Lactam was detected in surface water in the μg L -1 range. Finally, GBP and GBP-Lactam were found in potable water with concentrations up to 0.64 and 0.07 μg L -1 , respectively. According to the elevated environmental persistence of GBP-Lactam compared to GBP and its presumed enhanced toxicity, we recommend to involve GBP-Lactam into monitoring programs. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. 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.

  13. Radionuclide transfer to freshwater biota species: review of Russian language studies

    Energy Technology Data Exchange (ETDEWEB)

    Fesenko, S., E-mail: s.fesenko@iaea.or [International Atomic Energy Agency, NAAL, 1400 Vienna (Austria); Fesenko, J.; Sanzharova, N.; Karpenko, E.; Titov, I. [Russian Institute of Agricultural Radiology and Radioecology, 249020 Obninsk (Russian Federation)

    2011-01-15

    Around 130 publications reporting studies on radionuclide transfer to freshwater biota species conducted in the former USSR were reviewed to provide the concentration ratio values. None of these studies were available up to now in the English language reviews or publications. The values derived have been compared with the CR values used for freshwater systems in the International reviews. For some radionuclides reviewed in this paper, the data are in good agreement with the mean CR values presented earlier, however for some of them, in particular, for {sup 241}Am (bivalve molluscs, gastropods and pelagic fish), {sup 60}Co (gastropods, benthic fish and insect larvae), {sup 90}Sr and {sup 137}Cs (benthic fish and zooplankton), the mean values given here are substantially different from those presented earlier. The data reported in this paper for thirty five radionuclides and eleven groups of freshwater species markedly improve the extent of available data for evaluation of radiation impact on freshwater species. - Research highlights: {yields} The paper provides information on concentration ratios to freshwater biota species for 35 radionuclides. Many of the data are for {sup 90}Sr and {sup 137}Cs. {yields} For the majority of radionuclides reviewed in this paper, the CR values are in good agreement with those given in the recent International reviews. {yields} For {sup 241}Am (bivalve molluscs, gastropods and pelagic fish), {sup 60}Co (gastropods, benthic fish and insect larvae), {sup 90}Sr and {sup 137}Cs (benthic fish and zooplankton), the mean values based on review of the Russian language publications are substantially different from those presented in the International reviews. {yields} Information presented in the paper significantly increases the availability of data on radionuclide accumulation in freshwater species.

  14. Factors driving changes in freshwater mussel (Bivalvia, Unionida) diversity and distribution in Peninsular Malaysia.

    Science.gov (United States)

    Zieritz, Alexandra; Lopes-Lima, Manuel; Bogan, Arthur E; Sousa, Ronaldo; Walton, Samuel; Rahim, Khairul Adha A; Wilson, John-James; Ng, Pei-Yin; Froufe, Elsa; McGowan, Suzanne

    2016-11-15

    Freshwater mussels (Bivalvia, Unionida) fulfil important ecosystem functions and are one of the most threatened freshwater taxa globally. Knowledge of freshwater mussel diversity, distribution and ecology in Peninsular Malaysia is extremely poor, and the conservation status of half of the species presumed to occur in the region has yet to be assessed. We conducted the first comprehensive assessment of Peninsular Malaysia's freshwater mussels based on species presence/absence and environmental data collected from 155 sites spanning all major river catchments and diverse habitat types. Through an integrative morphological-molecular approach we recognised nine native and one widespread non-native species, i.e. Sinanodonta woodiana. Two species, i.e. Pilsbryoconcha compressa and Pseudodon cambodjensis, had not been previously recorded from Malaysia, which is likely a result of morphological misidentifications of historical records. Due to their restriction to single river catchments and declining distributions, Hyriopsis bialata, possibly endemic to Peninsular Malaysia, Ensidens ingallsianus, possibly already extinct in the peninsula, and Rectidens sumatrensis, particularly require conservation attention. Equally, the Pahang, the Perak and the north-western river catchments are of particular conservation value due to the presence of a globally unique freshwater mussel fauna. Statistical relationships of 15 water quality parameters and mussel presence/absence identified acidification and nutrient pollution (eutrophication) as the most important anthropogenic factors threatening freshwater mussel diversity in Peninsular Malaysia. These factors can be linked to atmospheric pollution, deforestation, oil-palm plantations and a lack of functioning waste water treatment, and could be mitigated by establishing riparian buffers and improving waste water treatment for rivers running through agricultural and residential land. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Radionuclide transfer to freshwater biota species: review of Russian language studies

    International Nuclear Information System (INIS)

    Fesenko, S.; Fesenko, J.; Sanzharova, N.; Karpenko, E.; Titov, I.

    2011-01-01

    Around 130 publications reporting studies on radionuclide transfer to freshwater biota species conducted in the former USSR were reviewed to provide the concentration ratio values. None of these studies were available up to now in the English language reviews or publications. The values derived have been compared with the CR values used for freshwater systems in the International reviews. For some radionuclides reviewed in this paper, the data are in good agreement with the mean CR values presented earlier, however for some of them, in particular, for 241 Am (bivalve molluscs, gastropods and pelagic fish), 60 Co (gastropods, benthic fish and insect larvae), 90 Sr and 137 Cs (benthic fish and zooplankton), the mean values given here are substantially different from those presented earlier. The data reported in this paper for thirty five radionuclides and eleven groups of freshwater species markedly improve the extent of available data for evaluation of radiation impact on freshwater species. - Research highlights: → The paper provides information on concentration ratios to freshwater biota species for 35 radionuclides. Many of the data are for 90 Sr and 137 Cs. → For the majority of radionuclides reviewed in this paper, the CR values are in good agreement with those given in the recent International reviews. → For 241 Am (bivalve molluscs, gastropods and pelagic fish), 60 Co (gastropods, benthic fish and insect larvae), 90 Sr and 137 Cs (benthic fish and zooplankton), the mean values based on review of the Russian language publications are substantially different from those presented in the International reviews. → Information presented in the paper significantly increases the availability of data on radionuclide accumulation in freshwater species.

  16. CARDIAC FUNCTION AND IRON CHELATION IN THALASSEMIA MAJOR AND INTERMEDIA: A REVIEW OF THE UNDERLYING PATHOPHYSIOLOGY AND APPROACH TO CHELATION MANAGEMENT

    Directory of Open Access Journals (Sweden)

    Athanasios Aessopos

    2009-07-01

    Full Text Available Heart disease is the leading cause of mortality and one of the main causes of morbidity in beta-thalassemia. Patients with homozygous thalassemia may have either a severe phenotype which is usually transfusion dependent or a milder form that is thalassemia intermedia.  The two main factors that determine cardiac disease in homozygous β thalassemia are the high output state that results from chronic tissue hypoxia, hypoxia-induced compensatory reactions and iron overload.  The high output state playing a major role in thalassaemia intermedia and the iron load being more significant in the major form. Arrhythmias, vascular involvement that leads to an increased pulmonary vascular resistance and an increased systemic vascular stiffness and valvular abnormalities also contribute to the cardiac dysfunction in varying degrees according to the severity of the phenotype.  Endocrine abnormalities, infections, renal function and medications can also play a role in the overall cardiac function.  For thalassaemia major, regular and adequate blood transfusions and iron chelation therapy are the mainstays of management. The approach to thalassaemia intermedia, today, is aimed at monitoring for complications and initiating, timely, regular transfusions and/or iron chelation therapy.  Once the patients are on transfusions, then they should be managed in the same way as the thalassaemia major patients.  If cardiac manifestations of dysfunction are present in either form of thalassaemia, high pre transfusion Hb levels need to be maintained in order to reduce cardiac output and appropriate intensive chelation therapy needs to be instituted.  In general recommendations on chelation, today, are usually made according to the Cardiac Magnetic Resonance findings, if available.  With the advances in the latter technology and the ability to tailor chelation therapy according to the MRI findings as well as the availability of three iron chelators, together with

  17. Phorbol ester tumor promoter induced the synthesis of two major cytoplasmic proteins: identity with two proteins induced under heat-shocked and glucose-starved conditions

    International Nuclear Information System (INIS)

    Zhang, H.; Chen, K.Y.; Liu, A.Y.C.

    1987-01-01

    The regulation of specific protein synthesis by the phorbol ester tumor promoter, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), was evaluated using the L-8 and C-2 myoblast and the 3T3-L1 fibroblast cell cultures. TPA increased, by 2-4 fold, the synthesis rates of two cytoplasmic proteins with apparent molecular weights of 89,000 and 74,000 as determined by SDS-polyacrylamide gel electrophoresis and autoradiography. The concentration of TPA and the time of incubation needed to elicit this induction was determined to be 10 μg/ml and 20 hrs, respectively. Increasing the concentration of TPA to 100, 200, and 500 ng/ml did not result in a greater magnitude of induction. The possibility that these two TPA-induced proteins may be identical to proteins with similar molecular weights induced under heat-shocked or glucose-starved conditions was evaluated by 1-D and 2-D gel electrophoresis and autoradiography. Results provided evidence that the TPA-induced 89,000- and 74,000-dalton proteins were identical to hsp 89 and hsp 74, 2 out of a set of 8-9 proteins induced under heat shocked conditions. Furthermore, they are identical to two of the set of glucose-regulated proteins induced under a glucose-starved condition

  18. Immunochemical detection of food-derived polyphenols in the aorta: macrophages as a major target underlying the anti-atherosclerotic activity of polyphenols.

    Science.gov (United States)

    Kawai, Yoshichika

    2011-01-01

    It has been suggested that polyphenol-rich diets decrease the risk of cardiovascular diseases. Although studies of the bioavailability of polyphenols, particularly their absorption and metabolism, have been reported recently, the tissue and cellular distributions underlying their biological mechanisms remain unknown. It is difficult to evaluate the specific localization of tissue and/or cellular polyphenols, because the method is limited to chromatography. To overcome these difficulties, we have developed anti-polyphenol antibodies to characterize immunohistochemically the localization of polyphenols and their metabolites in vivo. Two novel monoclonal antibodies were raised against quercetin and tea catechins, which represent flavonoid-type polyphenols distributed in foods and beverages, and are expected to exhibit anti-oxidative and anti-inflammatory activities in vivo. Using these antibodies, we identified activated macrophages as a specific target of these flavonoids during the development of atherosclerotic lesions. This review describes recent findings on the molecular actions of flavonoids that underly their anti-atherosclerotic activity in vivo.

  19. Low bone mineral density in thalassemia major: Sanjay Gandhi Post Graduate Institute experience and a brief focus on underlying factors behind the cause

    Directory of Open Access Journals (Sweden)

    Kritanjali Singh

    2014-11-01

    Full Text Available Thalassemia major is a genetic disorder and blood transfusion is critical for survival in these patients. Over the course of the past three decades, hyper transfusion therapy in these patients has shown has dramatically extended life expectancy and improved quality of life. Unfortunately, this type of therapy also increased the incidence of complications due to iron overload. The aim of this study was to assess bone mineral density (BMD in patients with β-thalassemia major and to determine their biochemical and hormonal profiles that may affect BMD. A cross- sectional study was carried out in Sanjay Gandhi – PGIMS, a tertiary care hospital over period of 3 years on all β-thalassemia major patients above 7 years receiving regular transfusion. Patients with transfusion dependent anaemia other than β thalassemia major were excluded. Physical examination, laboratory tests and bone density measurements were performed. Then, the data were analyzed. The total number of children over 7 years of age with β-thalassemia major receiving regular blood transfusions during the study period was 150. Mean hemoglobin was 7.8±0.6g/dL and the mean serum ferritin level 5295±2736 ng/mL. Short stature was seen in 54.7% boys and 28.7% of girls. Prevalence of lumbar osteoporosis and osteopenia were 42.5% and 37.5%. Femoral osteoporosis and osteopenia were present in 32.5% and 55% of the patients. Impaired puberty, hypothyroidism, diabetes mellitus, hypoparathyroidism were observed in 26%, 18%, 7%, and 15%, of patients, respectively. Nearly 75% of patients had low bone mineral density. Bone mineral density was significantly associated with short stature (P=0.002, hypogonadism (P=0.006, hypoparathyroidism (P=0.038, hypothyroidism (P=0.044 and vitamin D deficiency (P<0.001. High prevalence of complications among our thalassemics signifies the importance of more detailed studies along with therapeutic interventions. 重型地中海贫血是一种遗传疾病,

  20. Freshwater biodiversity and aquatic insect diversification.

    Science.gov (United States)

    Dijkstra, Klaas-Douwe B; Monaghan, Michael T; Pauls, Steffen U

    2014-01-01

    Inland waters cover less than 1% of Earth's surface but harbor more than 6% of all insect species: Nearly 100,000 species from 12 orders spend one or more life stages in freshwater. Little is known about how this remarkable diversity arose, although allopatric speciation and ecological adaptation are thought to be primary mechanisms. Freshwater habitats are highly susceptible to environmental change and exhibit marked ecological gradients. Standing waters appear to harbor more dispersive species than running waters, but there is little understanding of how this fundamental ecological difference has affected diversification. In contrast to the lack of evolutionary studies, the ecology and habitat preferences of aquatic insects have been intensively studied, in part because of their widespread use as bioindicators. The combination of phylogenetics with the extensive ecological data provides a promising avenue for future research, making aquatic insects highly suitable models for the study of ecological diversification.

  1. Freshwater fishes of Tsitsikamma National Park

    Directory of Open Access Journals (Sweden)

    I.A. Russell

    2002-12-01

    Full Text Available This study aimed to determine the distribution and relative abundance of freshwater fishes in the Tsitsikamma National Park. Fish assemblages in six river systems were sampled in 2001, with a total of 323 fish from eight species recorded. Indigenous fish collected included four freshwater species (Pseudobarbus afer, Pseudobarbus tenuis, Sandelia capensis, Anguilla mossambica, three estuarine species (Monodactylus falciformis, Caffrogobius gilchristi, Myxus capensis, and one alien (Micropterus salmoides. One additional indigenous species (Galaxias zebratus and two aliens (Salmo trutta, Oncorhynchus mykiss could potentially occur within the park. The topography and locality of the park presents a unique opportunity to meaningfully conserve the endangered P. tenuis as well as other fish characteristic of the eastern reaches of the Cape Floristic Region. Management action is required to minimise opportunities for further establishment and spread of alien fish species and to conserve indigenous fish assemblages within the park.

  2. Luminescence properties of a nanoporous freshwater diatom.

    Science.gov (United States)

    Goswami, Bondita; Choudhury, Amarjyoti; Buragohain, Alak K

    2012-01-01

    Freshwater diatom frustules show special optical properties. In this paper we observed luminescence properties of the freshwater diatom Cyclotella meneghiniana. To confirm the morphological properties we present scanning electron microscopy (SEM) images. X-ray diffraction (XRD) studies were carried out to visualize the structural properties of the frustules, confirming that silica present in diatom frustules crystallizes in an α-quartz structure. Study of the optical properties of the silica frustules of diatoms using ultra-violet-visible (UV-vis) spectroscopy and photoluminescence spectroscopy confirmed that the diatom C. meneghiniana shows luminescence in the blue region of the electromagnetic spectrum when irradiated with UV light. This property of diatoms can be exploited to obtain many applications in day-to-day life. Also, using time-resolved photoluminescence spectroscopy (TRPL) it was confirmed that this species of diatom shows bi-exponential decay. Copyright © 2011 John Wiley & Sons, Ltd.

  3. Evaluating the Financial Vulnerability of a Major Electric Utility in the Southeastern U.S. to Drought under Climate Change and an Evolving Generation Mix.

    Science.gov (United States)

    Kern, Jordan D; Characklis, Gregory W

    2017-08-01

    There is increasing recognition of the vulnerability of electric power systems to drought and the potential for both climate change and a shifting generation mix to alter this vulnerability. Nonetheless, the considerable research in this area has not been synthesized to inform electric utilities with respect to a key factor that influences their decisions about critical infrastructure: financial risk for shareholders. This study addresses this gap in knowledge by developing a systems framework for assessing the financial exposure of utilities to drought, with further consideration of the effects of climate change and a shifting generation mix. We then apply this framework to a major utility in the Southeastern U.S. Results suggest that extreme drought could cause profit shortfalls of more than $100 million if water temperature regulations are strictly enforced. However, even losses of this magnitude would not significantly impact returns for shareholders. This may inadvertently reduce pressure internally at utilities to incorporate drought vulnerability into long-term strategic planning, potentially leaving utilities and their customers at greater risk in the future.

  4. The International Editorship of Freshwater Systems

    OpenAIRE

    Karl E. Havens

    2001-01-01

    It is my pleasure to announce that two distinguished internationalscientists have joined the editorship of the FreshwaterSystems domain of TheScientificWorldJOURNAL — Professor BrijGopal of Jawaharlal Nehru University (India) and Dr. Manual Gra柠of the Universityof Coimbra (Portugal). Professor Gopal is the Secretary General of the NationalInstitute of Ecology, Editor of the InternationalJournal of Ecology & Environmental Science,and Chairman of the SIL (International Association of Theoretica...

  5. Freshwater savings from marine protein consumption

    International Nuclear Information System (INIS)

    Gephart, Jessica A; Pace, Michael L; D’Odorico, Paolo

    2014-01-01

    Marine fisheries provide an essential source of protein for many people around the world. Unlike alternative terrestrial sources of protein, marine fish production requires little to no freshwater inputs. Consuming marine fish protein instead of terrestrial protein therefore represents freshwater savings (equivalent to an avoided water cost) and contributes to a low water footprint diet. These water savings are realized by the producers of alternative protein sources, rather than the consumers of marine protein. This study quantifies freshwater savings from marine fish consumption around the world by estimating the water footprint of replacing marine fish with terrestrial protein based on current consumption patterns. An estimated 7 600 km 3  yr −1 of water is used for human food production. Replacing marine protein with terrestrial protein would require an additional 350 km 3  yr −1 of water, meaning that marine protein provides current water savings of 4.6%. The importance of these freshwater savings is highly uneven around the globe, with savings ranging from as little as 0 to as much as 50%. The largest savings as a per cent of current water footprints occur in Asia, Oceania, and several coastal African nations. The greatest national water savings from marine fish protein occur in Southeast Asia and the United States. As the human population increases, future water savings from marine fish consumption will be increasingly important to food and water security and depend on sustainable harvest of capture fisheries and low water footprint growth of marine aquaculture. (paper)

  6. A low-density SNP array for analyzing differential selection in freshwater and marine populations of threespine stickleback (Gasterosteus aculeatus).

    Science.gov (United States)

    Ferchaud, Anne-Laure; Pedersen, Susanne H; Bekkevold, Dorte; Jian, Jianbo; Niu, Yongchao; Hansen, Michael M

    2014-10-06

    The threespine stickleback (Gasterosteus aculeatus) has become an important model species for studying both contemporary and parallel evolution. In particular, differential adaptation to freshwater and marine environments has led to high differentiation between freshwater and marine stickleback populations at the phenotypic trait of lateral plate morphology and the underlying candidate gene Ectodysplacin (EDA). Many studies have focused on this trait and candidate gene, although other genes involved in marine-freshwater adaptation may be equally important. In order to develop a resource for rapid and cost efficient analysis of genetic divergence between freshwater and marine sticklebacks, we generated a low-density SNP (Single Nucleotide Polymorphism) array encompassing markers of chromosome regions under putative directional selection, along with neutral markers for background. RAD (Restriction site Associated DNA) sequencing of sixty individuals representing two freshwater and one marine population led to the identification of 33,993 SNP markers. Ninety-six of these were chosen for the low-density SNP array, among which 70 represented SNPs under putatively directional selection in freshwater vs. marine environments, whereas 26 SNPs were assumed to be neutral. Annotation of these regions revealed several genes that are candidates for affecting stickleback phenotypic variation, some of which have been observed in previous studies whereas others are new. We have developed a cost-efficient low-density SNP array that allows for rapid screening of polymorphisms in threespine stickleback. The array provides a valuable tool for analyzing adaptive divergence between freshwater and marine stickleback populations beyond the well-established candidate gene Ectodysplacin (EDA).

  7. Why are freshwater fish so threatened?

    Science.gov (United States)

    Closs, Gerard P.; Angermeier, Paul; Darwall, William R.T.; Balcombe, Stephen R.

    2015-01-01

    The huge diversity of freshwater fishes is concentrated into an area of habitat that covers only about 1% of the Earth's surface, and much of this limited area has already been extensively impacted and intensively managed to meet human needs (Dudgeon et al., 2006). As outlined in Chapter 1, the number and proportions of threatened species tend to rise wherever fish diversity coincides with dense human populations, intensive resource use and development pressure. Of particular concern is the substantial proportion of the global diversity of freshwater fishes concentrated within the Mekong and Amazon Basins and west-central Africa (Berra, 2001; Abell et al., 2008; Dudgeon, 2011; Chapter 1) with extensive exploitation of water resources planned to accelerate in future years (Dudgeon, 2011; Chapter 1). If current trends continue, and the social, political and economic models that have been used to develop industrialised regions of the world over the past two centuries prevail, then the future of a significant proportion of global diversity of freshwater fish species is clearly uncertain.

  8. Interspecies differences in the accumulation of tributyltin and its metabolites under dietary exposure in sea perch, Lateolabrax japonicus, and red sea bream, Pagrus major.

    Science.gov (United States)

    Uno, Seiichi; Murakami, Masayo; Kokushi, Emiko; Koyama, Jiro

    2011-02-01

    Interspecies differences in the accumulation of dietary tributyltin (TBT) between sea perch, Lateolabrax japonicus, and red sea bream, Pagrus major, were studied. Although TBTs in both species reached steady-state condition in low-concentration group (L-group, 200 ng/g nominal concentration) by 1 week, it increased up to the end of exposure in high-concentration group (H-group, 3000 ng/g nominal concentration). In H-group, the accumulation rate of TBT in sea perch from 1 to 2 weeks was much higher than in red sea bream, which were 2.4-fold for sea perch and 1.7-fold for red sea bream, although TBT concentrations were similar between sea perch and red sea bream in L-group. Furthermore, in the H-group, the concentrations of TBT at 1 and 2 weeks were about 1.3- and 1.9-fold, respectively, higher in the sea perch than in the red sea bream. On the other hand, DBT residue in red sea bream was about 1.4-fold higher in sea perch for the L-group but concentrations were similar in both fishes for the H-group. These results suggest that red sea bream could metabolize faster the TBT to DBT than sea perch. This study also reveals that fish probably could absorb TBT through the food chain. The uptake of TBT by fish should be regarded in the real environment, because TBT concentration in seawater has been decreasing and now already at significantly low level. Copyright © 2009 Wiley Periodicals, Inc.

  9. Current status of parasitic ciliates Chilodonella spp. (Phyllopharyngea: Chilodonellidae) in freshwater fish aquaculture.

    Science.gov (United States)

    Bastos Gomes, G; Jerry, D R; Miller, T L; Hutson, K S

    2017-05-01

    Freshwater fish farming contributes to more than two-thirds of global aquaculture production. Parasitic ciliates are one of the largest causes of production loss in freshwater farmed fishes, with species from the genus Chilodonella being particularly problematic. While Chilodonella spp. include 'free-living' fauna, some species are involved in mortality events of fish, particularly in high-density aquaculture. Indeed, chilodonellosis causes major productivity losses in over 16 species of farmed freshwater fishes in more than 14 countries. Traditionally, Chilodonella species are identified based on morphological features; however, the genus comprises yet uncharacterized cryptic species, which indicates the necessity for molecular diagnostic methods. This review synthesizes current knowledge on the biology, ecology and geographic distribution of harmful Chilodonella spp. and examines pathological signs, diagnostic methods and treatments. Recent advances in molecular diagnostics and the ability to culture Chilodonella spp. in vitro will enable the development of preventative management practices and sustained freshwater fish aquaculture production. © 2016 John Wiley & Sons Ltd.

  10. Global land-water nexus: Agricultural land and freshwater use embodied in worldwide supply chains.

    Science.gov (United States)

    Chen, B; Han, M Y; Peng, K; Zhou, S L; Shao, L; Wu, X F; Wei, W D; Liu, S Y; Li, Z; Li, J S; Chen, G Q

    2018-02-01

    As agricultural land and freshwater inextricably interrelate and interact with each other, the conventional water and land policy in "silos" should give way to nexus thinking when formulating the land and water management strategies. This study constructs a systems multi-regional input-output (MRIO) model to expound global land-water nexus by simultaneously tracking agricultural land and freshwater use flows along the global supply chains. Furthermore, land productivity and irrigation water requirements of 160 crops in different regions are investigated to reflect the land-water linkage. Results show that developed economies (e.g., USA and Japan) and major large developing economies (e.g., mainland China and India) are the overriding drivers of agricultural land and freshwater use globally. In general, significant net transfers of these two resources are identified from resource-rich and less-developed economies to resource-poor and more-developed economies. For some crops, blue water productivity is inversely related to land productivity, indicating that irrigation water consumption is sometimes at odds with land use. The results could stimulus international cooperation for sustainable land and freshwater management targeting on original suppliers and final consumers along the global supply chains. Moreover, crop-specific land-water linkage could provide insights for trade-off decisions on minimizing the environmental impacts on local land and water resources. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Assessing exposure risks for freshwater tilapia species posed by mercury and methylmercury.

    Science.gov (United States)

    Cheng, Yi-Hsien; Lin, Yi-Jun; You, Shu-Han; Yang, Ying-Fei; How, Chun Ming; Tseng, Yi-Ting; Chen, Wei-Yu; Liao, Chung-Min

    2016-08-01

    Waterborne and dietborne exposures of freshwater fish to mercury (Hg) in the forms of inorganic (Hg(II)) and organic (methylmercury or MeHg) affect their growth, development, and reproduction. However, an integrated mechanistic risk model framework to predict the impact of Hg(II)/MeHg on freshwater fish is lacking. Here, we integrated biokinetic, physiological and biogeographic data to calibrate and then establish key risk indices-hazardous quotient and exceedance risk-for freshwater tilapia species across geographic ranges of several major rivers in Taiwan. We found that Hg(II) burden was highest in kidney followed by gill, intestine, liver, blood, and muscle. Our results showed that Hg was less likely to pose mortality risk (mortality rate less than 5 %) for freshwater tilapia species. However, Hg is likely to pose the potential hazard to aquatic environments constrained by safety levels for aquatic organisms. Sensitivity analysis showed that amount of Hg accumulated in tilapia was most influenced by sediment uptake rate. Our approach opens up new possibilities for predicting future fish population health with the impacts of continued Hg exposure to provide information on which fish are deemed safe for human consumption.

  12. Coralline algal barium as indicator for 20th century northwestern North Atlantic surface ocean freshwater variability.

    Science.gov (United States)

    Hetzinger, S; Halfar, J; Zack, T; Mecking, J V; Kunz, B E; Jacob, D E; Adey, W H

    2013-01-01

    During the past decades climate and freshwater dynamics in the northwestern North Atlantic have undergone major changes. Large-scale freshening episodes, related to polar freshwater pulses, have had a strong influence on ocean variability in this climatically important region. However, little is known about variability before 1950, mainly due to the lack of long-term high-resolution marine proxy archives. Here we present the first multidecadal-length records of annually resolved Ba/Ca variations from Northwest Atlantic coralline algae. We observe positive relationships between algal Ba/Ca ratios from two Newfoundland sites and salinity observations back to 1950. Both records capture episodical multi-year freshening events during the 20th century. Variability in algal Ba/Ca is sensitive to freshwater-induced changes in upper ocean stratification, which affect the transport of cold, Ba-enriched deep waters onto the shelf (highly stratified equals less Ba/Ca). Algal Ba/Ca ratios therefore may serve as a new resource for reconstructing past surface ocean freshwater changes.

  13. The endogenous and reactive depression subtypes revisited: integrative animal and human studies implicate multiple distinct molecular mechanisms underlying major depressive disorder.

    Science.gov (United States)

    Malki, Karim; Keers, Robert; Tosto, Maria Grazia; Lourdusamy, Anbarasu; Carboni, Lucia; Domenici, Enrico; Uher, Rudolf; McGuffin, Peter; Schalkwyk, Leonard C

    2014-05-07

    Traditional diagnoses of major depressive disorder (MDD) suggested that the presence or absence of stress prior to onset results in either 'reactive' or 'endogenous' subtypes of the disorder, respectively. Several lines of research suggest that the biological underpinnings of 'reactive' or 'endogenous' subtypes may also differ, resulting in differential response to treatment. We investigated this hypothesis by comparing the gene-expression profiles of three animal models of 'reactive' and 'endogenous' depression. We then translated these findings to clinical samples using a human post-mortem mRNA study. Affymetrix mouse whole-genome oligonucleotide arrays were used to measure gene expression from hippocampal tissues of 144 mice from the Genome-based Therapeutic Drugs for Depression (GENDEP) project. The study used four inbred mouse strains and two depressogenic 'stress' protocols (maternal separation and Unpredictable Chronic Mild Stress) to model 'reactive' depression. Stress-related mRNA differences in mouse were compared with a parallel mRNA study using Flinders Sensitive and Resistant rat lines as a model of 'endogenous' depression. Convergent genes differentially expressed across the animal studies were used to inform candidate gene selection in a human mRNA post-mortem case control study from the Stanley Brain Consortium. In the mouse 'reactive' model, the expression of 350 genes changed in response to early stresses and 370 in response to late stresses. A minimal genetic overlap (less than 8.8%) was detected in response to both stress protocols, but 30% of these genes (21) were also differentially regulated in the 'endogenous' rat study. This overlap is significantly greater than expected by chance. The VAMP-2 gene, differentially expressed across the rodent studies, was also significantly altered in the human study after correcting for multiple testing. Our results suggest that 'endogenous' and 'reactive' subtypes of depression are associated with largely

  14. Amazonian freshwater habitats experiencing environmental and socioeconomic threats affecting subsistence fisheries.

    Science.gov (United States)

    Alho, Cleber J R; Reis, Roberto E; Aquino, Pedro P U

    2015-09-01

    Matching the trend seen among the major large rivers of the globe, the Amazon River and its tributaries are facing aquatic ecosystem disruption that is affecting freshwater habitats and their associated biodiversity, including trends for decline in fishery resources. The Amazon's aquatic ecosystems, linked natural resources, and human communities that depend on them are increasingly at risk from a number of identified threats, including expansion of agriculture; cattle pastures; infrastructure such as hydroelectric dams, logging, mining; and overfishing. The forest, which regulates the hydrological pulse, guaranteeing the distribution of rainfall and stabilizing seasonal flooding, has been affected by deforestation. Flooding dynamics of the Amazon Rivers are a major factor in regulating the intensity and timing of aquatic organisms. This study's objective was to identify threats to the integrity of freshwater ecosystems, and to seek instruments for conservation and sustainable use, taking principally fish diversity and fisheries as factors for analysis.

  15. Reproductive impacts of tributyltin (TBT) and triphenyltin (TPT) in the hermaphroditic freshwater gastropod Lymnaea stagnalis.

    Science.gov (United States)

    Giusti, Arnaud; Barsi, Alpar; Dugué, Maël; Collinet, Marc; Thomé, Jean-Pierre; Joaquim-Justo, Célia; Roig, Benoit; Lagadic, Laurent; Ducrot, Virginie

    2013-07-01

    Tributyltin (TBT) and triphenyltin (TPT) are emblematic endocrine disruptors, which have been mostly studied in gonochoric prosobranchs. Although both compounds can simultaneously occur in the environment, they have mainly been tested separately for their effects on snail reproduction. Because large discrepancies in experimental conditions occurred in these tests, the present study aimed to compare the relative toxicity of TBT and TPT under similar laboratory conditions in the range of 0 ng Sn/L to 600 ng Sn/L. Tests were performed on the simultaneous hermaphrodite Lymnaea stagnalis, a freshwater snail in which effects of TPT were unknown. Survival, shell length, and reproduction were monitored in a 21-d semistatic test. Frequency of abnormal eggs was assessed as an additional endpoint. Triphenyltin hampered survival while TBT did not. Major effects on shell solidity and reproduction were observed for both compounds, reproductive outputs being more severely hampered by TBT than by TPT. Considering the frequency of abnormal eggs allowed increasing test sensitivity, because snail responses to TBT could be detected at concentrations as low as 19 ng Sn/L. However, the putative mode of action of the 2 compounds could not be deduced from the structure of the molecules or from the response of apical endpoints. Sensitivity of L. stagnalis to TBT and TPT was compared with the sensitivity of prosobranch mollusks with different habitats and different reproductive strategies. Copyright © 2013 SETAC.

  16. Plant-associated bacterial populations on native and invasive plant species: comparisons between 2 freshwater environments.

    Science.gov (United States)

    Olapade, Ola A; Pung, Kayleigh

    2012-06-01

    Plant-microbial interactions have been well studied because of the ecological importance of such relationships in aquatic systems. However, general knowledge regarding the composition of these biofilm communities is still evolving, partly as a result of several confounding factors that are attributable to plant host properties and to hydrodynamic conditions in aquatic environments. In this study, the occurrences of various bacterial phylogenetic taxa on 2 native plants, i.e., mayapple (Podophyllum peltatum L.) and cow parsnip (Heracleum maximum Bartram), and on an invasive species, i.e., garlic mustard (Alliaria petiolata (M. Bieb.) Cavara & Grande), were quantitatively examined using nucleic acid staining and fluorescence in situ hybridization. The plants were incubated in triplicates for about a week within the Kalamazoo River and Pierce Cedar Creek as well as in microcosms. The bacterial groups targeted for enumeration are known to globally occur in relatively high abundance and are also ubiquitously distributed in freshwater environments. Fluorescence in situ hybridization analyses of the bacterioplankton assemblages revealed that the majority of bacterial cells that hybridized with the different probes were similar between the 2 sites. In contrast, the plant-associated populations while similar on the 3 plants incubated in Kalamazoo River, their representations were highest on the 2 native plants relative to the invasive species in Pierce Cedar Creek. Overall, our results further suggested that epiphytic bacterial assemblages are probably under the influences of and probably subsequently respond to multiple variables and conditions in aquatic milieus.

  17. Carbon and energy fluxes from China's largest freshwater lake

    Science.gov (United States)

    Gan, G.; LIU, Y.

    2017-12-01

    Carbon and energy fluxes between lakes and the atmosphere are important aspects of hydrology, limnology, and ecology studies. China's largest freshwater lake, the Poyang lake experiences tremendous water-land transitions periodically throughout the year, which provides natural experimental settings for the study of carbon and energy fluxes. In this study, we use the eddy covariance technique to explore the seasonal and diurnal variation patterns of sensible and latent heat fluxes of Poyang lake during its high-water and low-water periods, when the lake is covered by water and mudflat, respectively. We also determine the annual NEE of Poyang lake and the variations of NEE's components: Gross Primary Productivity (GPP) and Ecosystem Respiration (Re). Controlling factors of seasonal and diurnal variations of carbon and energy fluxes are analyzed, and land cover impacts on the variation patterns are also studied. Finally, the coupling between the carbon and energy fluxes are analyzed under different atmospheric, boundary stability and land cover conditions.

  18. [Freshwater malacofauna of medical importance located in Yaguajay municipality, Sancti Spíritus province].

    Science.gov (United States)

    Fimia Duarte, Rigoberto; Vázquez Perera, Antonio A; Luis Rodríguez, Yuodenis; Cepero Rodriguez, Omelio; Pereira Marin, Carlos A

    2010-01-01

    the study carried out in Yaguajay, Sancti Spíritus province was aimed at identifying the mollusk species present in the freshwater ecocystems as well as their distribution and abundance in each reservoir. two years--2005 and 2006--were analyzed through 2 samplings per years covering the rainy and the dry season; 20 reservoirs were sampled to determine the present freshwater mollusks. Data were processed by Excelxp and the statistical analysis used SPSS version 8 processor and 4 x 4 contingency tables. ten species were detected in 2005, being Tarebia granifera the most distributed and abundant followed by Marisa cornuarietis. It was observed that the highest amount of mosquitoes was collected in the rainy season during the two years under study in addition to proving that there was significant correlation between the occurrence of mollusk species and fish in the 20 researched reservoirs. Yaguajay municipality exhibits wide freshwater mollusk fauna if one takes into account the 14 identified species of which 4 turned out to be intermediate hosts for fascioliasis, schistosomiasis and angiostrongyliasis. There is close relation between freshwater malacofauna and vegetation.

  19. Box Model of Freshwater, Salinity and Nutrient in the Delta Mahakam, East Kalimantan

    Directory of Open Access Journals (Sweden)

    Marojahan Simanjuntak

    2011-04-01

    Full Text Available Box Model of Freshwater, Salinity and Nutrient in the Delta Mahakam, East Kalimantan. Research has been conducted in the southern part of the Mahakam Delta, East Kalimantan. Method of measuring temperature, salinity, light transmission and turbidity by using CTD model 603 SBE and current measurement and bathymetry by using ADCP model RDI. Measurement parameters on the nutrient chemistry are based of water samples taken using Nansen bottles from two depths. The purpose of this study to determine the mechanism of freshwater, salinity and nutrient transport from the land of the Mahakam River which interact with seawater by using box models. The results illustrate that the vertical distribution of salinity in the Mahakam Delta has obtained a high stratification, where the freshwater salinity 12.30 psu at the surface of a river flowing toward the sea, and seawater of high salinity 30.07 psu flowing in the direction river under the surface that are separated by a layer of mixture. Freshwater budget of the sea (VSurf obtained for 0,0306 x 109 m3 day-1, and the sea water salinity budget is going into the bottom layer system (VDeep.SOcn-d obtained for 20,727 x 109 psu day-1. While time dilution (Syst obtained for 0.245 day-1 or 5.87 hours. Nutrient budget in the surface layer obtained by the system is autotrophic while in layers near the bottom tend to be heterotrophic

  20. Cadmium as toxicant in Freshwater Cyprinid, Labeo rohita

    African Journals Online (AJOL)

    Sajo

    2012-04-24

    Apr 24, 2012 ... urbanization, expansion of industrial activity, industrial wasteful effluents .... blood capillaries, and sinusoids were randomly distri- buted. ..... cholinesterase activity of freshwater fish, Oreochromis mossambicus. Peters. Asia.

  1. A low-density SNP array for analyzing differential selection in freshwater and marine populations of threespine stickleback (Gasterosteus aculeatus)

    DEFF Research Database (Denmark)

    Ferchaud, Anne-Laure; Pedersen, Susanne H.; Bekkevold, Dorte

    2014-01-01

    for rapid and cost efficient analysis of genetic divergence between freshwater and marine sticklebacks, we generated a low-density SNP (Single Nucleotide Polymorphism) array encompassing markers of chromosome regions under putative directional selection, along with neutral markers for background. Results......: RAD (Restriction site Associated DNA) sequencing of sixty individuals representing two freshwater and one marine population led to the identification of 33,993 SNP markers. Ninety-six of these were chosen for the low-density SNP array, among which 70 represented SNPs under putatively directional...... selection in freshwater vs. marine environments, whereas 26 SNPs were assumed to be neutral. Annotation of these regions revealed several genes that are candidates for affecting stickleback phenotypic variation, some of which have been observed in previous studies whereas others are new. Conclusions: We...

  2. Selection of spatial scale for assessing impacts of groundwater-based water supply on freshwater resources.

    Science.gov (United States)

    Hybel, A-M; Godskesen, B; Rygaard, M

    2015-09-01

    Indicators of the impact on freshwater resources are becoming increasingly important in the evaluation of urban water systems. To reveal the importance of spatial resolution, we investigated how the choice of catchment scale influenced the freshwater impact assessment. Two different indicators were used in this study: the Withdrawal-To-Availability ratio (WTA) and the Water Stress Index (WSI). Results were calculated for three groundwater based Danish urban water supplies (Esbjerg, Aarhus, and Copenhagen). The assessment was carried out at three spatial levels: (1) the groundwater body level, (2) the river basin level, and (3) the regional level. The assessments showed that Copenhagen's water supply had the highest impact on the freshwater resource per cubic meter of water abstracted, with a WSI of 1.75 at Level 1. The WSI values were 1.64 for Aarhus's and 0.81 for Esbjerg's water supply. Spatial resolution was identified as a major factor determining the outcome of the impact assessment. For the three case studies, WTA and WSI were 27%-583% higher at Level 1 than impacts calculated for the regional scale. The results highlight that freshwater impact assessments based on regional data, rather than sub-river basin data, may dramatically underestimate the actual impact on the water resource. Furthermore, this study discusses the strengths and shortcomings of the applied indicator approaches. A sensitivity analysis demonstrates that although WSI has the highest environmental relevance, it also has the highest uncertainty, as it requires estimations of non-measurable environmental water requirements. Hence, the development of a methodology to obtain more site-specific and relevant estimations of environmental water requirements should be prioritized. Finally, the demarcation of the groundwater resource in aquifers remains a challenge for establishing a consistent method for benchmarking freshwater impacts caused by groundwater abstraction. Copyright © 2015 Elsevier

  3. Influence of freshwater input on the skill of decadal forecast of sea ice in the Southern Ocean

    Directory of Open Access Journals (Sweden)

    V. Zunz

    2015-03-01

    Full Text Available Recent studies have investigated the potential link between the freshwater input derived from the melting of the Antarctic ice sheet and the observed recent increase in sea ice extent in the Southern Ocean. In this study, we assess the impact of an additional freshwater flux on the trend in sea ice extent and concentration in simulations with data assimilation, spanning the period 1850–2009, as well as in retrospective forecasts (hindcasts initialised in 1980. In the simulations with data assimilation, the inclusion of an additional freshwater flux that follows an autoregressive process improves the reconstruction of the trend in ice extent and concentration between 1980 and 2009. This is linked to a better efficiency of the data assimilation procedure but can also be due to a better representation of the freshwater cycle in the Southern Ocean. The results of the hindcast simulations show that an adequate initial state, reconstructed thanks to the data assimilation procedure including an additional freshwater flux, can lead to an increase in the sea ice extent spanning several decades that is in agreement with satellite observations. In our hindcast simulations, an increase in sea ice extent is obtained even in the absence of any major change in the freshwater input over the last decades. Therefore, while the additional freshwater flux appears to play a key role in the reconstruction of the evolution of the sea ice in the simulation with data assimilation, it does not seem to be required in the hindcast simulations. The present work thus provides encouraging results for sea ice predictions in the Southern Ocean, as in our simulation the positive trend in ice extent over the last 30 years is largely determined by the state of the system in the late 1970s.

  4. Indirect Consequences of Recreational Fishing in Freshwater Ecosystems: An Exploration from an Australian Perspective

    Directory of Open Access Journals (Sweden)

    Shelley Burgin

    2017-02-01

    Full Text Available Recreational fishing in freshwater ecosystems is a popular pastime in Australia. Although most native fish are endemic, the fauna is depauperate compared to any landmass of similar size. With commercial fishing no longer a major industry in the country’s freshwaters, the future sustainability of these ecosystems will depend heavily on the actions of recreational fishers. However, there has been limited focus on the consequences of recreational fishing in freshwaters. There is particularly a dearth of information on the indirect consequences of fishers on the waterbodies they depend on for their sport. After outlining the respective trends in commercial and recreational fishing in Australia as a basis for placing the sport in context, the indirect impacts of fishers on water quality, movement (walking, off-road vehicles, the introduction/translocation of fauna (particularly fish, the dispersal of flora and the transmission of fish disease and pathogens are reviewed. It is concluded that with the decline of commercial fishing, the competition between commercial fin-fishing and recreational fishing is negligible, at least throughout most of the country. It is also concluded that each of the issues addressed has the potential to be detrimental to the long-term sustainability of the freshwater ecosystems that the fishers depend on for their recreation. However, information on these issues is scant. This is despite the current and predicted popularity of freshwater recreational fishing continuing to increase in Australia. Indeed, there has been insufficient quantitative assessment of the impacts to even determine what is required to ensure a comprehensive, adequate and representative protection of these freshwater ecosystems. To underpin the sustainability of inland recreational fishing in the country, it was concluded that research is required to underpin the development and implementation of appropriate policies. The alternative is that the

  5. Practical aids for freshwater spill response

    International Nuclear Information System (INIS)

    Steen, A.E.; Walker, A.H.

    1993-01-01

    The current research program at API is focused on the environmental and human health effects from oil spills in freshwater habitats. Components of the program include lessons learned from spill response, development of decision-making protocols for the use of chemicals during initial response operations, preparation of a manual for spill response and contingency planning, and a review of the literature on environmental and human health effects from inland spills. API has reviewed past inland spill responses to identify lessons learned. A survey questionnaire has been developed to collect information from freshwater spill responders on their successes and difficulties in response operations. The questionnaire is tailored to focus on the impact to the operations from the absence of technical/scientific data on environmental effects or operation effectiveness/efficiency as well as to identify situations in which the use of particular response or cleanup options is likely to be effective. The questionnaires will be available at the Conference. Published case studies also will be examined for lessons-learned information. The results will be used to identify and prioritize API research needs in freshwater spill response. General concerns about the effectiveness of the toxicity associated with chemicals in spill response has prevented their use in fresh water. API has begun a detailed survey and interview process with state and federal regulatory personnel to identify their concerns and decision criteria to evaluate the use of chemicals in initial spill response. Ten classes of chemicals were identified for consideration: dispersants, shoreline cleaners, shoreline protection agents, herding agents, solidifiers, demulsifiers, emulsion inhibitors, foaming agents, oxidizing agents, and burning agents

  6. Education Agendas and Resistance with the Teaching and Learning of Freshwater and Extreme Freshwater Events

    Science.gov (United States)

    Sammel, Alison; McMartin, Dena; Arbuthnott, Katherine

    2018-01-01

    Despite the essentiality of freshwater to all life on the planet, the populous has inadequate understandings of water. Formal education plays a key role in shaping how individuals and communities make sense of water, its accessibility, management, consumption, and hazards. This article seeks to bring attention to the infuence of cultural framings…

  7. Freshwater reservoir effect variability in Northern Germany

    DEFF Research Database (Denmark)

    Philippsen, B.; Heinemeier, J.

    2013-01-01

    The freshwater reservoir effect is a potential problem when radiocarbon dating fish bones, shells, human bones, or food crusts on pottery from sites near rivers or lakes. The reservoir age in hardwater rivers can be up to several thousand years and may be highly variable. Accurate 14C dating of f...... that can also be expected for the past. This knowledge will be applied to the dating of food crusts on pottery from the Mesolithic sites Kayhude at the Alster River and Schlamersdorf at the Trave River, both in Schleswig-Holstein, northern Germany....

  8. MOLLUSKS IN RADIOECOLOGICAL STUDIES OF FRESHWATER ECOSYSTEMS

    Directory of Open Access Journals (Sweden)

    Д. Гудков

    2012-04-01

    Full Text Available Species-specificity and dynamics of 90Sr, 137Cs and some transuraniс elements accumulation in bivalveand gastropod freshwater molluscs of the Chernobyl exclusion zone during 1998–2010 was analyzed. Theresults of radiation dose as well as chromosome aberration rate estimation and analysis of hemolymphcomposition of molluscs was produced. The radiation absorbed dose rate was registered in the range of 0.3–85.0 μGy h–1. In closed water bodies the heightened chromosome aberration rate (up to 27 % in embryotissues, and also change of haematological indexes for the adult individuals of snails was registered

  9. Cultured branchial epithelia from freshwater fish gills

    Science.gov (United States)

    Wood; PÄRt

    1997-01-01

    We have developed a method for the primary culture of gill epithelial cells from freshwater rainbow trout on permeable supports, polyethylene terephthalate membranes ('filter inserts'). Primary cultures of gill cells (6-9 days in Leibowitz L-15 culture medium plus foetal bovine serum and glutamine) are trypsinized and the cells seeded onto the inserts. After 6 days of growth with L-15 medium on both surfaces (approximately isotonic to trout plasma), the cells form a tight epithelium as judged from a progressive rise in transepithelial resistance which reaches a stable plateau for a further 6 days, as long as L-15 exposure is continued on both surfaces. The cultured epithelium (approximately 8 µm thick) typically consists of 2-4 overlapping cell layers organized as in the lamellae in vivo, with large intercellular spaces, multiple desmosomes and putative tight junctions. The cells appear to be exclusively pavement-type cells with an apical surface glycocalyx, an abundance of rough endoplasmic reticulum, no selective DASPEI staining and relatively few mitochondria. Transepithelial resistance (approximately 3.5 k cm2), permeability to a paracellular marker (polyethylene glycol-4000; 0.17x10(-6) cm s-1) and unidirectional flux of Na+ and Cl- (approximately 300 nmol cm-2 h-1) all appear realistic because they compare well with in vivo values; net fluxes of Na+ and Cl- are zero. The preparation acidifies the apical medium, which accumulates a greater concentration of ammonia. Upon exposure to apical freshwater, resistance increases six- to elevenfold and a basolateral-negative transepithelial potential (TEP) develops as in vivo. These responses occur even when mannitol is used to prevent changes in apical osmotic pressure. Net Na+ and Cl- loss rates are low over the first 12 h (-125 nmol cm-2 h-1) but increase substantially by 48 h. The elevated resistance and negative TEP gradually attenuate but remain significantly higher than pre-exposure values after 48 h of apical

  10. 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.

  11. Comparison of population genetic patterns in two widespread freshwater mussels with contrasting life histories in western North America.

    Science.gov (United States)

    Mock, K E; Brim Box, J C; Chong, J P; Furnish, J; Howard, J K

    2013-12-01

    We investigate population genetic structuring in Margaritifera falcata, a freshwater mussel native to western North America, across the majority of its geographical range. We find shallow rangewide genetic structure, strong population-level structuring and very low population diversity in this species, using both mitochondrial sequence and nuclear microsatellite data. We contrast these patterns with previous findings in another freshwater mussel species group (Anodonta californiensis/A. nuttalliana) occupying the same continental region and many of the same watersheds. We conclude that differences are likely caused by contrasting life history attributes between genera, particularly host fish requirements and hermaphroditism. Further, we demonstrate the occurrence of a 'hotspot' for genetic diversity in both groups of mussels, occurring in the vicinity of the lower Columbia River drainage. We suggest that stream hierarchy may be responsible for this pattern and may produce similar patterns in other widespread freshwater species. © 2013 John Wiley & Sons Ltd.

  12. Freshwater mussel response to bedform movement: experimental stream studies

    Science.gov (United States)

    Kozarek, J. L.; MacGregor, K. R.; Hornbach, D.; Hove, M.

    2017-12-01

    Freshwater mussels are intrinsically linked to near-bed sediment dynamics, but it remains unclear how mussels respond to changing sediment loads across spatial and temporal scales. The interactions between mussels and sediment transport are complex and often involve feedback loops. Mussels are filter feeders removing suspended particles from the water column and the physical presence of mussels can have significant impacts on the structure of riverbed habitat. We investigated the feedbacks between mussels, flow, and migrating bedforms during flood experiments in the St. Anthony Falls Laboratory Outdoor StreamLab (OSL) at the University of Minnesota. The OSL is a field-scale sand-bed meandering stream channel with independent control over sediment feed (recirculated) and water flow (diverted from the Mississippi River). Mussel location, orientation to flow, and protrusion from sediment was surveyed immediately before, after, and one and two days after each flood event. Flow fields, bed shear stress, bedform migration, and bar topography were measured during each flooding event with and without mussels present (density = 4/m2 and 8/m2) to quantify the influence of mussels on channel morphology and bedform migration. Mobile bedforms (up to 14 cm high) were present for all flood events with quasi-equilibrium, aggrading, and degrading bed conditions. Mussels moved little horizontally during all flood events, but were shown to move quickly to deeper water after the flood receded. However, mussels moved vertically, burrowing or being buried under mobile bedforms, during each flood event. The research presented here will focus on feedbacks between three mussel species with different shell sculptures, flow conditions, and migrating bedforms during flooding events. These results reveal how freshwater mussels respond to and affect flow and sediment transport during flood events that are difficult to observe in the field.

  13. Radurization of commercial freshwater fish species

    International Nuclear Information System (INIS)

    Chuaqui-Offermanns, N.; McDougall, T.E.; Sprung, W.; Sullivan, V.

    1988-01-01

    The effect of radurization on the shelf life of fresh Whitefish obtained through ordinary commercial channels has been determined. Whitefish fillets irradiated at 1.2 kGy and stored at 3 0 C have a shelf life three times longer than the unirradiated fish. When the fish was irradiated at 0.82 kGy a two fold shelf-life extension was obtained. The shelf life was estimated by sensory, chemical and microbiological evaluations. Sensory evaluation involved organoleptic assessment of raw and cooked samples. Since freshwater fish do not contain trimethylamine oxide (TMAO), alternate tests for freshness were required. It was found the determination of hypoxanthine and total volatile acid number (VAN) are excellent tests for freshness and quality of freshwater fish; thus, these analyses were adopted. The degree of radiation-induced lipid oxidation was measured by the thiobarbituric acid test (TBA). It was found at doses of 0.82 and 1.2 kGy the TBA number remained within acceptable limits in all samples. Microbiological analyses consisted of the total microbial load assessment in the sample, as well as Pseudomonas and total psychrotrophic counts. The estimated shelf lives as determined by the three separate evaluations were in very good agreement. (author)

  14. Management and the conservation of freshwater ecosystems

    Science.gov (United States)

    Wipfli, Mark S.; Richardson, John S.

    2015-01-01

    Riparian areas are the terrestrial environment adjacent to water that both influences and is influenced by the aquatic feature (Gregory et al., 1991; Naiman et al., 2010). Riparian areas along streams provide shade, sources of wood and organic matter, contribute to bank stability, filter sediments, take up excess nutrients from groundwater inputs, and other key processes that protect freshwaters (e.g. Naiman et al., 2010; Richardson & Danehy, 2007; Figure 9.1). Riparian areas also increase biodiversity through habitat complexity and close juxtaposition of aquatic and terrestrial environments (Quinn et al., 2004; Naiman et al., 2010). Alterations to riparian areas, despite their small area relative to the landscape, have disproportionate effects on habitats and fish communities (Naiman et al., 2010; Wipfli & Baxter, 2010). Key habitat losses and alterations are derived from modification of riparian areas by reducing instream habitat complexity (Bilby & Ward, 1989; Fausch & Northcote, 1992; Naiman et al., 2010), diminishing the productive basis of freshwater food webs (Belsky et al., 1999; Quinn et al., 2004), increasing nutrient, contaminant and sediment intrusion (Muscutt et al., 1993; Daniels & Gilliam, 1996; Nguyen et al., 1998; Waters, 1999).

  15. Radurization of commercial freshwater fish species

    Energy Technology Data Exchange (ETDEWEB)

    Chuaqui-Offermanns, N.; McDougall, T.E.; Sprung, W.; Sullivan, V.

    1988-01-01

    The effect of radurization on the shelf life of fresh Whitefish obtained through ordinary commercial channels has been determined. Whitefish fillets irradiated at 1.2 kGy and stored at 3/sup 0/C have a shelf life three times longer than the unirradiated fish. When the fish was irradiated at 0.82 kGy a two fold shelf-life extension was obtained. The shelf life was estimated by sensory, chemical and microbiological evaluations. Sensory evaluation involved organoleptic assessment of raw and cooked samples. Since freshwater fish do not contain trimethylamine oxide (TMAO), alternate tests for freshness were required. It was found the determination of hypoxanthine and total volatile acid number (VAN) are excellent tests for freshness and quality of freshwater fish;thus, these analyses were adopted. The degree of radiation-induced lipid oxidation was measured by the thiobarbituric acid test (TBA). It was found at doses of 0.82 and 1.2 kGy the TBA number remained within acceptable limits in all samples. Microbiological analyses consisted of the total microbial load assessment in the sample, as well as Pseudomonas and total psychrotrophic counts. The estimated shelf lives as determined by the three separate evaluations were in very good agreement

  16. Persistence of environmental DNA in freshwater ecosystems.

    Directory of Open Access Journals (Sweden)

    Tony Dejean

    Full Text Available The precise knowledge of species distribution is a key step in conservation biology. However, species detection can be extremely difficult in many environments, specific life stages and in populations at very low density. The aim of this study was to improve the knowledge on DNA persistence in water in order to confirm the presence of the focus species in freshwater ecosystems. Aquatic vertebrates (fish: Siberian sturgeon and amphibian: Bullfrog tadpoles were used as target species. In control conditions (tanks and in the field (ponds, the DNA detectability decreases with time after the removal of the species source of DNA. DNA was detectable for less than one month in both conditions. The density of individuals also influences the dynamics of DNA detectability in water samples. The dynamics of detectability reflects the persistence of DNA fragments in freshwater ecosystems. The short time persistence of detectable amounts of DNA opens perspectives in conservation biology, by allowing access to the presence or absence of species e.g. rare, secretive, potentially invasive, or at low density. This knowledge of DNA persistence will greatly influence planning of biodiversity inventories and biosecurity surveys.

  17. length-weight relationhip of freshwater wild fish species

    African Journals Online (AJOL)

    Dr Naeem

    2012-06-21

    Jun 21, 2012 ... Length-weight (LWR) and length-length relationships (LLR) were determined for a freshwater catfish ... Key words: Mystus bleekeri, length-weight relationship, length-length relationship, predictive equations. INTRODUCTION. Mystus bleekeri (freshwater catfish Day, 1877), locally ..... fish farmers, Aquacult.

  18. Recent changes in the freshwater composition east of Greenland

    NARCIS (Netherlands)

    de Steur, L.; Pickart, R.S.; Torres, D.J.; Valdimarsson, H.

    2015-01-01

    Results from three hydrographic surveys across the East Greenland Current between 2011 and 2013 are presented with focus on the freshwater sources. End-member analysis using salinity, d18O, and nutrient data shows that while meteoric water dominated the freshwater content, a significant amount of

  19. Occurrence of digenean larvae in freshwater snails in the Ruvu ...

    African Journals Online (AJOL)

    Occurrence of digenean larvae in freshwater snails in the Ruvu basin, Tanzania. G Nkwengulila, ESP Kigadye. Abstract. A survey was carried out on digenean larvae infecting freshwater snails in five habitats in Dar es Salaam, Ruvu and Morogoro. 9424 snails belonging to 12 species from five families were examined for ...

  20. Potential impacts of alien freshwater crayfish in South Africa | de ...

    African Journals Online (AJOL)

    The habitat preferences and life history characteristics of four alien species of freshwater crayfish (Cherax tenuimanus, C. destructor, C. quadricarinatus and Procambarus clarkii) are reviewed. The potential impact of these species on South African freshwater ecosystems is assessed and the desirability of allowing their ...

  1. Ammonium transformation in a nitrogen-rich tidal freshwater marsh

    DEFF Research Database (Denmark)

    Gribsholt, B.; Andersson, M.; Boschker, H.T.S.

    2006-01-01

    The fate and transport of watershed-derived ammonium in a tidal freshwater marsh fringing the nutrient rich Scheldt River, Belgium, was quantified in a whole ecosystem 15N labeling experiment. In late summer (September) we added 15N-NH4+ to the flood water entering a 3477 m2 tidal freshwater marsh...

  2. Snail abundance in freshwater canals in the eastern province of ...

    African Journals Online (AJOL)

    Ksu-network

    2012-07-19

    Jul 19, 2012 ... Recent Advances in Freshwater Biology. New Delhi. Anmol. Publication. Vol. 2. pp. 187-202. Al-Akel and Suliman. 12261. Supian Z, Ikhwanuddin AM (2002). Population dynamics of freshwater mollusks (Gastropod: Melanoides Tuberculatus) in crocker range park, Sabah. ASEAN Rev. Biodiv. Environ.

  3. Predicting freshwater habitat integrity using land-use surrogates

    African Journals Online (AJOL)

    2007-04-02

    Apr 2, 2007 ... Quantification of potential surrogates of freshwater habitat integrity. We chose a series of land-use variables that might be suitable predictors for assessing freshwater habitat integrity from the land cover map (CSIR 2005) and added separate GIS surfaces for human population density and the distribution of ...

  4. Invasive alien freshwater fishes in the Wilderness Lakes System, a ...

    African Journals Online (AJOL)

    Invasive alien freshwater fishes in the Wilderness Lakes System, a wetland of international importance in the Western Cape Province, South Africa. ... A total of 87 893 fish comprising 16 species were caught. In addition to confirming the ... Key words: freshwater fish, invasive alien fishes, estuary, RAMSAR site, diversity.

  5. Short Communications: First record of freshwater fish on the Cape ...

    African Journals Online (AJOL)

    During a non-exhaustive survey of freshwater bodies on five islands of the archipelago, the first presence of a freshwater fish was recorded. Using barcoding sequences, the species was identified as the guppy (Poecilia reticulata), a highly invasive species alien to the Cape Verdean Islands. Key words: Cape Verde, guppy, ...

  6. Distribution of transuranic elements in a freshwater pond ecosystem

    International Nuclear Information System (INIS)

    Emery, R.M.; Klopfer, D.C.

    1975-05-01

    Preliminary results are reported from a study initiated on the Hanford Reservation concerning the ecological behavior of 238 Pu, 239 Pu, 240 Pu, and 241 Am in a freshwater environment. This study involves a waste pond which has been receiving Pu processing wastes for about 30 years. The pond has a sufficiently established ecosystem to provide an excellent location for limnological characterization. In addition, the ecological distribution of Pu and Am was investigated. The pond is also highly enriched with nutrients, thus supporting a high level of algal and macrophyte production. Seston (30 percent diatoms) appears to be the principal concentrators of Pu transuranics in the pond system. The major sink for Pu and Am in this system is the sediments. Organic floc, overlaying the pond sediments, is also a major concentrator of transuranics in this system []Aside from the seston and floc, no other ecological components of the pond appear to have concentrations significantly greater than those of the sediment. Dragonfly, larvae, watercress, and snails show concentrations which approximate those of the sediments but nearly all other food web components have levels of Pu and Am which are lower than those of the sediments, thus, Pu and Am seem to be relatively immobile in the aquatic ecosystem. (CH)

  7. Roseomonas wooponensis sp. nov., isolated from wetland freshwater.

    Science.gov (United States)

    Lee, Ji Hee; Kim, Mi Sun; Baik, Keun Sik; Kim, Hyang Mi; Lee, Kang Hyun; Seong, Chi Nam

    2015-11-01

    A non-motile, cocobacilli-shaped and pink-pigmented bacterium, designated strain WW53T, was isolated from wetland freshwater (Woopo wetland, Republic of Korea). Cells were Gram-stain-negative, catalase- and oxidase-positive. The major fatty acids were C18 : 1ω7c/C18 : 1ω6c and C16 : 0.The predominant quinone and polyamine were ubiquinone 10 (Q-10) and spermidine, respectively. The DNA G+C content was 71 mol%. The major polar lipids were phosphatidylethanolamine, phosphatidylcholine and an unknown aminolipid. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain WW53T belongs to the family Acetobacteraceae, and is related to the genus Roseomonas. Strain WW53T was most closely related to Roseomonas stagni HS-69T (95.3 % 16S rRNA gene sequence similarity). Results of a polyphasic taxonomy study suggested that the isolate represents a novel species in the genus Roseomonas, for which the name Roseomonas wooponensis sp. nov. is proposed. The type strain is WW53T ( = KCTC 32534T = JCM 19527T).

  8. Sustainable Water Management under Climate Change in Small ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Sustainable Water Management under Climate Change in Small Island States of the Caribbean. In the Caribbean islands, climate change is affecting freshwater availability and other ecosystem services in complex ways. For example, freshwater supply is diminished by droughts and affected by saline intrusion due to sea ...

  9. Molluscs for Sale: Assessment of Freshwater Gastropods and Bivalves in the Ornamental Pet Trade.

    Science.gov (United States)

    Ng, Ting Hui; Tan, Siong Kiat; Wong, Wing Hing; Meier, Rudolf; Chan, Sow-Yan; Tan, Heok Hui; Yeo, Darren C J

    2016-01-01

    The ornamental pet trade is often considered a key culprit for conservation problems such as the introduction of invasive species (including infectious diseases) and overharvesting of rare species. Here, we present the first assessment of the biodiversity of freshwater molluscs in the ornamental pet trade in Singapore, one of the most important global hubs of the ornamental aquarium trade, and discuss associated conservation concerns. We recorded freshwater molluscs from ornamental pet shops and major exporters including non-ornamental species (e.g., hitchhikers, molluscs sold as fish feed). We recorded an unexpectedly high diversity-59 species-of freshwater bivalves and gastropods, with the majority (38 species or 64%) being from the Oriental region. In addition to morphological examination, we sequenced the DNA barcode region of mitochondrial CO1 and 16S genes to provide molecular data for the confirmation of the identification and for future re-identification. DNA barcodes were obtained for 50 species, and all but four were separated by > 3% uncorrected pairwise distances. The trade has been considered a main introduction pathway for non-native species to Singapore, and we found that out of 15 species in the trade as well as in the wild in Singapore, 12 are either introduced or of unknown origin, representing almost half of the known non-native freshwater molluscs in Singapore. Particularly prevalent are non-ornamental species: six hitchhikers on aquarium plants and six species sold as fish feed. We found that a quarter of the trade species have a history of introduction, which includes 11 known or potentially invasive species. We conclude that potential overharvesting is difficult to assess because only half of the trade species have been treated by IUCN. Of these, 21 species are of Least Concern and three are Data Deficient. Our checklist, with accompanying DNA barcodes, images, and museum vouchers, provides an important reference library for future monitoring

  10. Evaluation of the Impact of Groundwater Pumping on Freshwater-Saltwater Interface Fluctuations in a Coastal Aquifer of South Korea

    Science.gov (United States)

    Yoon, H.; Kim, Y.; Lee, S. H.; Ha, K.

    2017-12-01

    It is necessary to monitor the variation of freshwater-saltwater interface for the sustainable use of groundwater resources in coastal areas. In the present study, we developed a device to measure the location of the freshwater-saltwater interface based on the concept of the neutral buoyancy and installed it in a coastal aquifer of the western sea, South Korea. To evaluate the impact of pumping on the groundwater and saltwater-freshwater interface level, we designed nine different pumping scenarios and monitored the groundwater and saltwater-freshwater interface levels of pumping well and two observation wells. The result of monitoring groundwater level shows that the response of observation wells to the pumping is relatively fast and high, however, the response of freshwater-saltwater interface occurred when the pumping rate and duration are over 25m3/day and 48hours, respectively. For the prediction and simulation of the groundwater level fluctuation under groundwater pumping events, we designed a artificial neural network based time series model considering rainfall, tide, and pumping rate as input components. The result of the prediction shows that the correlation coefficient between observed and estimated groundwater levels is as high as 0.7. It is expected that the result of this research can provide useful information for the effective management of groundwater resources in the study area.

  11. 3D Dynamics of the Near-Surface Layer of the Ocean in the Presence of Freshwater Influx

    Science.gov (United States)

    Dean, C.; Soloviev, A.

    2015-12-01

    Freshwater inflow due to convective rains or river runoff produces lenses of freshened water in the near surface layer of the ocean. These lenses are localized in space and typically involve both salinity and temperature anomalies. Due to significant density anomalies, strong pressure gradients develop, which result in lateral spreading of freshwater lenses in a form resembling gravity currents. Gravity currents inherently involve three-dimensional dynamics. The gravity current head can include the Kelvin-Helmholtz billows with vertical density inversions. In this work, we have conducted a series of numerical experiments using computational fluid dynamics tools. These numerical simulations were designed to elucidate the relationship between vertical mixing and horizontal advection of salinity under various environmental conditions and potential impact on the pollution transport including oil spills. The near-surface data from the field experiments in the Gulf of Mexico during the SCOPE experiment were available for validation of numerical simulations. In particular, we observed a freshwater layer within a few-meter depth range and, in some cases, a density inversion at the edge of the freshwater lens, which is consistent with the results of numerical simulations. In conclusion, we discuss applicability of these results to the interpretation of Aquarius and SMOS sea surface salinity satellite measurements. The results of this study indicate that 3D dynamics of the near-surface layer of the ocean are essential in the presence of freshwater inflow.

  12. Acute sensitivity of freshwater mollusks and commonly tested invertebrates to select chemicals with different toxic models of action

    Science.gov (United States)

    Previous studies indicate that freshwater mollusks are more sensitive than commonly tested organisms to some chemicals, such as copper and ammonia. Nevertheless, mollusks are generally under-represented in toxicity databases. Studies are needed to generate data with which to comp...

  13. Influence of Dilution Rate on Enzymes of Intermediary Metabolism in Two Freshwater Bacteria Grown in Continuous Culture

    NARCIS (Netherlands)

    Matin, A.; Grootjans, A.; Hogenhuis, H.

    1976-01-01

    Two freshwater bacteria, a Pseudomonas sp. and a Spirillum sp., were grown in continuous culture under steady-state conditions in L-lactate-, succinate-, ammonium- or phosphate-limited media. In Pseudomonas sp., NAD-independent and NAD-dependent L-lactate dehydrogenases, aconitase, isocitrate

  14. The decline of North American freshwater fishes

    Science.gov (United States)

    Walsh, Stephen J.; Jelks, Howard L.; Burkhead, Noel M.

    2009-01-01

    North America has a broad array of freshwater ecosystems because of the continent's complex geography and geological history. Within a multitude of habitats—that include streams, large rivers, natural lakes, springs, and wetlands—rich assemblages of fishes reside, representing diverse taxonomic groups with unique ecological requirements. They face an unprecedented conservation crisis.1 In the last few decades, the proportion of inland fishes of North America, which are considered imperiled or extinct, increased from 20 to 40%.2 Although extinctions have occurred, many species and populations are declining in range size and abundance. The fish biota of the continent as a whole remains diverse; however, we can take action to stem any further declines.

  15. Toxicities of selected substances to freshwater biota

    Energy Technology Data Exchange (ETDEWEB)

    Hohreiter, D.W.

    1980-05-01

    The amount of data available concerning the toxicity of various substances to freshwater biota is so large that it is difficult to use in a practical situation, such as environmental impact assessment. In this document, summary tables are presented showing acute and/or chronic toxicity of selected substances for various groups of aquatic biota. Each entry is referenced to its original source so that details concerning experimental conditions may be consulted. In addition, general information concerning factors modifying toxicity, synergisms, evidence of bioaccumulation, and water quality standards and criteria for the selected substances is given. The final table is a general toxicity table designed to provide an easily accessible and general indication of toxicity of selected substances in aquatic systems.

  16. Making fate and exposure models for freshwater ecotoxicity in life cycle assessment suitable for organic acids and bases.

    Science.gov (United States)

    van Zelm, Rosalie; Stam, Gea; Huijbregts, Mark A J; van de Meent, Dik

    2013-01-01

    Freshwater fate and exposure factors were determined for organic acids and bases, making use of the knowledge on electrical interaction of ionizing chemicals and their sorption to particles. The fate factor represents the residence time in the environment whereas exposure factors equal the dissolved fraction of a chemical. Multimedia fate, exposure, and effect model USES-LCA was updated to take into account the influence of ionization, based upon the acid dissociation constant (pK(a)) of a chemical, and the environmental pH. Freshwater fate (FF) and exposure (XF) factors were determined for 415 acids and 496 bases emitted to freshwater, air, and soil. The relevance of taking account of the degree of ionization of chemicals was tested by determining the ratio (R) of the new vs. fate and exposure factors determined with USES-LCA suitable for neutral chemicals only. Our results show that the majority of freshwater fate and exposure factors of chemicals that are largely ionized in the environment are larger with the ionics model compared to the factors determined with the neutrals model version. R(FF) ranged from 2.4×10(-1) to 1.6×10(1) for freshwater emissions, from 1.2×10(-2) to 2.0×10(4) for soil emissions and from 5.8×10(-2) to 6.0×10(3) for air emissions, and R(XF) from 5.3×10(-1) to 2.2×10(1). Prediction of changed solid-water partitioning, implying a change in runoff and in removal via sedimentation, and prediction of negligible air-water partition coefficient, leading to negligible volatilization were the main contributors to the changes in freshwater fate factors. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Seawater and Freshwater Circulations through Coastal Forested Wetlands on a Caribbean Island

    Directory of Open Access Journals (Sweden)

    Luc Lambs

    2015-07-01

    Full Text Available Structure and composition of coastal forested wetlands are mainly controlled by local topography and soil salinity. Hydrology plays a major role in relation with tides, seaward, and freshwater inputs, landward. We report here the results of a two-year study undertaken in a coastal plain of the Guadeloupe archipelago (FWI. As elsewhere in the Caribbean islands, the study area is characterized by a micro-tidal regime and a highly seasonal climate. This work aimed at understanding groundwater dynamics and origin (seawater/freshwater both at ecosystems and stand levels. These hydrological processes were assessed through 18O/16O and 2H/1H isotopic analyses, and from monthly monitoring of water level and soil salinity at five study sites located in mangrove (3 and swamp forest (2. Our results highlight the importance of freshwater budget imbalance during low rainfall periods. Sustained and/or delayed dry seasons cause soil salinity to rise at the mangrove/swamp forest ecotone. As current models on climate change project decreasing rainfall amounts over the inner Caribbean region, one may expect for this area an inland progression of the mangrove forest to the expense of the nearby swamp forest.

  18. Tracking animals in freshwater with electronic tags: past, present and future

    Science.gov (United States)

    Cooke, Steven J.; Midwood, Jonathan D.; Thiem, Jason D.; Klimley, Peter; Lucas, Martyn C.; Thorstad, Eva B.; Eiler, John; Holbrook, Chris; Ebner, Brendan C.

    2013-01-01

    Considerable technical developments over the past half century have enabled widespread application of electronic tags to the study of animals in the wild, including in freshwater environments. We review the constraints associated with freshwater telemetry and biologging and the technical developments relevant to their use. Technical constraints for tracking animals are often influenced by the characteristics of the animals being studied and the environment they inhabit. Collectively, they influence which and how technologies can be used and their relative effectiveness. Although radio telemetry has historically been the most commonly used technology in freshwater, passive integrated transponder (PIT) technology, acoustic telemetry and biologgers are becoming more popular. Most telemetry studies have focused on fish, although an increasing number have focused on other taxa, such as turtles, crustaceans and molluscs. Key technical developments for freshwater systems include: miniaturization of tags for tracking small-size life stages and species, fixed stations and coded tags for tracking large samples of animals over long distances and large temporal scales, inexpensive PIT systems that enable mass tagging to yield population- and community-level relevant sample sizes, incorporation of sensors into electronic tags, validation of tag attachment procedures with a focus on maintaining animal welfare, incorporation of different techniques (for example, genetics, stable isotopes) and peripheral technologies (for example, geographic information systems, hydroacoustics), development of novel analytical techniques, and extensive international collaboration. Innovations are still needed in tag miniaturization, data analysis and visualization, and in tracking animals over larger spatial scales (for example, pelagic areas of lakes) and in challenging environments (for example, large dynamic floodplain systems, under ice). There seems to be a particular need for adapting

  19. Microbiological reduction of Sb(V) in anoxic freshwater sediments

    Science.gov (United States)

    Oremland, Ronald S.; Kulp, Thomas R.; Miller, Laurence G.; Braiotta, Franco; Webb, Samuel M.; Kocar, Benjamin D; Blum, Jodi S.

    2014-01-01

    Microbiological reduction of millimolar concentrations of Sb(V) to Sb(III) was observed in anoxic sediments from two freshwater settings: (1) a Sb- and As-contaminated mine site (Stibnite Mine) in central Idaho and 2) an uncontaminated suburban lake (Searsville Lake) in the San Francisco Bay Area. Rates of Sb(V) reduction in anoxic sediment microcosms and enrichment cultures were enhanced by amendment with lactate or acetate as electron donors but not by H2, and no reduction occurred in sterilized controls. Addition of 2-14C-acetate to Stibnite Mine microcosms resulted in the production of 14CO2 coupled to Sb(V) reduction, suggesting that this process proceeds by a dissimilatory respiratory pathway in those sediments. Antimony(V) reduction in Searsville Lake sediments was not coupled to acetate mineralization and may be associated with Sb-resistance. The microcosms and enrichment cultures also reduced sulfate, and the precipitation of insoluble Sb(III)-sulfide complexes was a major sink for reduced Sb. The reduction of Sb(V) by Stibnite Mine sediments was inhibited by As(V), suggesting that As(V) is a preferred electron acceptor for the indigenous community. These findings indicate a novel pathway for anaerobic microbiological respiration and suggest that communities capable of reducing high concentrations of Sb(V) commonly occur naturally in the environment.

  20. Biodegradation of Dimethyl Phthalate by Freshwater Unicellular Cyanobacteria.

    Science.gov (United States)

    Zhang, Xiaohui; Liu, Lincong; Zhang, Siping; Pan, Yan; Li, Jing; Pan, Hongwei; Xu, Shiguo; Luo, Feng

    2016-01-01

    The biodegradation characteristics of dimethyl phthalate (DMP) by three freshwater unicellular organisms were investigated in this study. The findings revealed that all the organisms were capable of metabolizing DMP; among them, Cyanothece sp. PCC7822 achieved the highest degradation efficiency. Lower concentration of DMP supported the growth of the Cyanobacteria; however, with the increase of DMP concentration growth of Cyanobacteria was inhibited remarkably. Phthalic acid (PA) was detected to be an intermediate degradation product of DMP and accumulated in the culture solution. The optimal initial pH value for the degradation was detected to be 9.0, which mitigated the decrease of pH resulting from the production of PA. The optimum temperature for DMP degradation of the three species of organisms is 30°C. After 72 hours' incubation, no more than 11.8% of the residual of DMP aggregated in Cyanobacteria cells while majority of DMP remained in the medium. Moreover, esterase was induced by DMP and the activity kept increasing during the degradation process. This suggested that esterase could assist in the degradation of DMP.

  1. Impact of acid precipitation on freshwater ecosystems in Norway

    Energy Technology Data Exchange (ETDEWEB)

    Wright, R F; Dale, T; Gjessing, E T; Hendrey, G R; Henriksen, A; J Hannesen, M; Muniz, I P

    1975-01-01

    Precipitation in southern Norway contains large amounts of H/sup +/, SO/sub 4//sup 2 -/, and NO/sub 3//sup -/ ions, along with heavy metals such as Cu, Zn, Cd, and Pb. These pollutants are transported over long distances to Scandinavia and are deposited in precipitation and dry-fallout. Large areas of southern Norway have been adversely affected by acid precipitation. The pH of many lakes is below 5.0 and sulfate, rather than bicarbonate, is the major anion. Lakes in these areas are particularly vulnerable to acid precipitation because their watersheds are underlain by highly resistant bedrock with low calcium and magnesium contents. The effects of the increasing acidity of freshwater ecosystems involve interference at every trophic level. Biological surveys indicate that low pH-values inhibit the decomposition of allochthonous organic matter, decrease the species number of phyto- and zooplankton and benthic invertebrates, and promote the growth of benthic mosses. Fish populations have been severely affected - the salmon have been eliminated from many rivers, and hundreds of lakes have lost their sport fisheries.

  2. Biodegradation of Dimethyl Phthalate by Freshwater Unicellular Cyanobacteria

    Science.gov (United States)

    Zhang, Xiaohui; Liu, Lincong; Zhang, Siping; Pan, Yan; Li, Jing; Pan, Hongwei

    2016-01-01

    The biodegradation characteristics of dimethyl phthalate (DMP) by three freshwater unicellular organisms were investigated in this study. The findings revealed that all the organisms were capable of metabolizing DMP; among them, Cyanothece sp. PCC7822 achieved the highest degradation efficiency. Lower concentration of DMP supported the growth of the Cyanobacteria; however, with the increase of DMP concentration growth of Cyanobacteria was inhibited remarkably. Phthalic acid (PA) was detected to be an intermediate degradation product of DMP and accumulated in the culture solution. The optimal initial pH value for the degradation was detected to be 9.0, which mitigated the decrease of pH resulting from the production of PA. The optimum temperature for DMP degradation of the three species of organisms is 30°C. After 72 hours' incubation, no more than 11.8% of the residual of DMP aggregated in Cyanobacteria cells while majority of DMP remained in the medium. Moreover, esterase was induced by DMP and the activity kept increasing during the degradation process. This suggested that esterase could assist in the degradation of DMP. PMID:28078293

  3. Short-term impacts of enhanced Greenland freshwater fluxes in an eddy-permitting ocean model

    Directory of Open Access Journals (Sweden)

    R. Marsh

    2010-07-01

    Full Text Available In a sensitivity experiment, an eddy-permitting ocean general circulation model is forced with realistic freshwater fluxes from the Greenland Ice Sheet, averaged for the period 1991–2000. The fluxes are obtained with a mass balance model for the ice sheet, forced with the ERA-40 reanalysis dataset. The freshwater flux is distributed around Greenland as an additional term in prescribed runoff, representing seasonal melting of the ice sheet and a fixed year-round iceberg calving flux, for 8.5 model years. By adding Greenland freshwater fluxes with realistic geographical distribution and seasonality, the experiment is designed to investigate the oceanic response to a sudden and spatially/temporally uniform amplification of ice sheet melting and discharge, rather than localized or gradual changes in freshwater flux. The impacts on regional hydrography and circulation are investigated by comparing the sensitivity experiment to a control experiment, without additional fluxes. By the end of the sensitivity experiment, the majority of additional fresh water has accumulated in Baffin Bay, and only a small fraction has reached the interior of the Labrador Sea, where winter mixed layer depth is sensitive to small changes in salinity. As a consequence, the impact on large-scale circulation is very slight. An indirect impact of strong freshening off the west coast of Greenland is a small anti-cyclonic component to the circulation around Greenland, which opposes the wind-driven cyclonic circulation and reduces net southward flow through the Canadian Archipelago by ~10%. Implications for the post-2000 acceleration of Greenland mass loss are discussed.

  4. Developing a Phytoplankton Biotic Index as an Indicator of Freshwater Inflow within a Subtropical Estuary

    Science.gov (United States)

    Steichen, J. L.; Quigg, A.; Lucchese, A.; Preischel, H.

    2016-02-01

    Freshwater inflows drive the water and sediment quality in coastal bays and estuaries influencing the ecosystem and health of the biological community. Phytoplankton accessory pigments (used as a proxy for major taxonomic groups) have been utilized to develop a biotic index of physical, chemical and biotic disturbances in Chesapeake Bay (USA) and other estuarine systems. In this study we have used the Chesapeake Bay - Phytoplankton Index of Biotic Integrity model as a guide in developing an index for Galveston Bay, TX (USA) as an indicator of sufficient freshwater inflow to a subtropical estuary. Multivariate statistical analyses were run using PRIMER-E+PERMANOVA to determine the correlations between phytoplankton accessory pigment concentrations and a suite of abiotic factors associated with freshwater inflow (salinity, DIN, PO4, secchi). Phytoplankton pigment concentrations and water quality parameters were collected across Galveston Bay on a monthly basis from 2008-2013. In the upper region of the bay nearest the river source Dinophyceae, Cryptophyceae (winter (Dec-Feb)) and Chlorophyceae (winter and spring (Mar-May)) were significantly correlated to freshwater inflow and nutrient concentrations PO4 (p<0.05). Increased concentrations of Bacillariophyceae and Cyanophyceae (summer (Jun-Aug)) were significantly correlated to lower concentrations of DIN (p<0.05). Near the mouth of the estuary there was a significant correlation between the increase in Bacillariophyceae, Cyanophyceae, Cryptophyceae and Dinophyceae with decreasing PO4 (p<0.05). Within the dynamic system of Galveston Bay we are working to apply a Phytoplankton Index of Biotic Integrity as a means of monitoring the biological health of this ecologically and economically important estuarine ecosystem.

  5. Monthly Sea Surface Salinity and Freshwater Flux Monitoring

    Science.gov (United States)

    Ren, L.; Xie, P.; Wu, S.

    2017-12-01

    Taking advantages of the complementary nature of the Sea Surface Salinity (SSS) measurements from the in-situ (CTDs, shipboard, Argo floats, etc.) and satellite retrievals from Soil Moisture Ocean Salinity (SMOS) satellite of the European Space Agency (ESA), the Aquarius of a joint venture between US and Argentina, and the Soil Moisture Active Passive (SMAP) of national Aeronautics and Space Administration (NASA), a technique is developed at NOAA/NCEP/CPC to construct an analysis of monthly SSS, called the NOAA Blended Analysis of Sea-Surface Salinity (BASS). The algorithm is a two-steps approach, i.e. to remove the bias in the satellite data through Probability Density Function (PDF) matching against co-located in situ measurements; and then to combine the bias-corrected satellite data with the in situ measurements through the Optimal Interpolation (OI) method. The BASS SSS product is on a 1° by 1° grid over the global ocean for a 7-year period from 2010. Combined with the NOAA/NCEP/CPC CMORPH satellite precipitation (P) estimates and the Climate Forecast System Reanalysis (CFSR) evaporation (E) fields, a suite of monthly package of the SSS and oceanic freshwater flux (E and P) was developed to monitor the global oceanic water cycle and SSS on a monthly basis. The SSS in BASS product is a suite of long-term SSS and fresh water flux data sets with temporal homogeneity and inter-component consistency better suited for the examination of the long-term changes and monitoring. It presents complete spatial coverage and improved resolution and accuracy, which facilitates the diagnostic analysis of the relationship and co-variability among SSS, freshwater flux, mixed layer processes, oceanic circulation, and assimilation of SSS into global models. At the AGU meeting, we will provide more details on the CPC salinity and fresh water flux data package and its applications in the monitoring and analysis of SSS variations in association with the ENSO and other major climate

  6. Parasites of freshwater fishes in North America: why so neglected?

    Science.gov (United States)

    Scholz, Tomáš; Choudhury, Anindo

    2014-02-01

    Fish parasitology has a long tradition in North America and numerous parasitologists have contributed considerably to the current knowledge of the diversity and biology of protistan and metazoan parasites of freshwater fishes. The Journal of Parasitology has been essential in disseminating this knowledge and remains a significant contributor to our understanding of fish parasites in North America as well as more broadly at the international level. However, with a few exceptions, the importance of fish parasites has decreased during the last decades, which is reflected in the considerable decline of funding and corresponding decrease of attention paid to these parasites in Canada and the United States of America. After the 'golden age' in the second half of the 20th Century, fish parasitology in Canada and the United States went in a new direction, driven by technology and a shift in priorities. In contrast, fish parasitology in Mexico has undergone rapid development since the early 1990s, partly due to extensive international collaboration and governmental funding. A critical review of the current data on the parasites of freshwater fishes in North America has revealed considerable gaps in the knowledge of their species composition, host specificity, life cycles, evolution, phylogeography, and relationships with their fish hosts. As to the key question, "Why so neglected?" this is probably because: (1) fish parasites are not in the forefront due to their lesser economic importance; (2) there is little funding for this kind of research, especially if a practical application is not immediately apparent; and (3) of shifting interests and a shortage of key personalities to train a new generation (they switched to marine habitats or other fields). Some of the opportunities for future research are outlined, such as climate change and cryptic species diversity. A significant problem challenging future research seems to be the loss of trained and experienced fish

  7. The potential for phosphorus pollution remediation by calcite precipitation in UK freshwaters

    Directory of Open Access Journals (Sweden)

    C. Neal

    2001-01-01

    Full Text Available This paper examines the potential for calcium carbonate to reduce phosphate pollution in freshwaters by co-precipitation, a process known as a "self cleansing mechanism". Calcium carbonate saturation levels and phosphate concentrations (SRP - soluble reactive phosphate across the major eastern UK river basins are examined to test for solubility controls. The study shows that calcite saturation varies for each catchment as a function of flow and biological activity rather than by direct regulation by SRP. Indeed, there is no evidence, for any of the rivers studied, that calcite solubility controls hold. However, for groundwater and groundwater-fed springs in the Chalk of the Thames basin, calcite saturation is observed with associated low SRP levels. A self-cleansing mechanism may well be operative within the Chalk due to two factors. Firstly, there is a high potential for nucleation on the calcite micro-crystals in the aquifer. Secondly, there are within aquifer reactions that remove the calcite nucleating inhibitors (SRP and dissolved organic carbon, DOC to levels lower than those occurring within the rivers do. These inhibitors enter the catchment at very high concentrations in association with agricultural pollution (fertilizer application and animal slurry and household contamination (e.g. sewage sources from septic tanks. Under low flow conditions, when the saturation index for calcite is at its highest, so too is the concentration of the nucleation inhibitor SRP. Companion work shows that calcite precipitation can occur at the water-sediment interface of the river and this may involve SRP removal. The data, as a whole, define an apparent bound for calcite solubility control where in the presence of nucleating centres, SRP must be less than 4 mM-P l-1 and DOC must be less than 150 mM-C l-1: a condition that does not seem to pertain within most UK rivers. Keywords: calcite, calcium carbonate, phosphate, soluble reactive phosphate, dissolved

  8. Assessment of sources of human pathogens and fecal contamination in a Florida freshwater lake.

    Science.gov (United States)

    Staley, Christopher; Reckhow, Kenneth H; Lukasik, Jerzy; Harwood, Valerie J

    2012-11-01

    We investigated the potential for a variety of environmental reservoirs to harbor or contribute fecal indicator bacteria (FIB), DNA markers of human fecal contamination, and human pathogens to a freshwater lake. We hypothesized that submerged aquatic vegetation (SAV), sediments, and stormwater act as reservoirs and/or provide inputs of FIB and human pathogens to this inland water. Analysis included microbial source tracking (MST) markers of sewage contamination (Enterococcus faecium esp gene, human-associated Bacteroides HF183, and human polyomaviruses), pathogens (Salmonella, Cryptosporidium, Giardia, and enteric viruses), and FIB (fecal coliforms, Escherichia coli, and enterococci). Bayesian analysis was used to assess relationships among microbial and physicochemical variables. FIB in the water were correlated with concentrations in SAV and sediment. Furthermore, the correlation of antecedent rainfall and major rain events with FIB concentrations and detection of human markers and pathogens points toward multiple reservoirs for microbial contaminants in this system. Although pathogens and human-source markers were detected in 55% and 21% of samples, respectively, markers rarely coincided with pathogen detection. Bayesian analysis revealed that low concentrations (<45 CFU × 100 ml(-1)) of fecal coliforms were associated with 93% probability that pathogens would not be detected; furthermore the Bayes net model showed associations between elevated temperature and rainfall with fecal coliform and enterococci concentrations, but not E. coli. These data indicate that many under-studied matrices (e.g. SAV, sediment, stormwater) are important reservoirs for FIB and potentially human pathogens and demonstrate the usefulness of Bayes net analysis for water quality assessment. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Extinction rates in North American freshwater fishes, 1900-2010

    Science.gov (United States)

    Burkhead, Noel M.

    2012-01-01

    Widespread evidence shows that the modern rates of extinction in many plants and animals exceed background rates in the fossil record. In the present article, I investigate this issue with regard to North American freshwater fishes. From 1898 to 2006, 57 taxa became extinct, and three distinct populations were extirpated from the continent. Since 1989, the numbers of extinct North American fishes have increased by 25%. From the end of the nineteenth century to the present, modern extinctions varied by decade but significantly increased after 1950 (post-1950s mean = 7.5 extinct taxa per decade). In the twentieth century, freshwater fishes had the highest extinction rate worldwide among vertebrates. The modern extinction rate for North American freshwater fishes is conservatively estimated to be 877 times greater than the background extinction rate for freshwater fishes (one extinction every 3 million years). Reasonable estimates project that future increases in extinctions will range from 53 to 86 species by 2050.

  10. Information to help reduce environmental impacts from freshwater oil spills

    International Nuclear Information System (INIS)

    Fritz, D.E.; Steen, A.E.

    1995-01-01

    The American Petroleum Institute (API) has been working since 1990 to provide information to help the response community minimize the impact of spills to pared jointly with the US inland freshwater. Projects have included a manual, pre National Oceanic and Atmospheric Administration (NOAA), to give guidance on the cleanup techniques that will minimize environmental impacts on spills in freshwater habitats. Nearing completion are a literature review and annotated bibliography of the environmental and human health effects of oil spilled in freshwater habitats. The use of chemical treating agents for freshwater spill applications is being studied with input from other industry and government groups. A project has begun, with funding from API, the Louisiana Applied Oil Spill Research and Development Program, NOAA, the Marine Spill Response Corporation (MSRC), and the US Department of Energy, to evaluate in situ burning of oil spilled in marshes

  11. A NEW FRESHWATER GOBY (TELEOSTEI: GOBIIDAE) FROM THE ...

    African Journals Online (AJOL)

    497. JUDB, R. A. 1967. Freshwater fishes of southern Africa. Cape Town: Balkema. KOUMANS, F. P. 1931. A preliminary revision of the genera of the gobioidfishes with united ventral fins. N. V. Lisse. (Netherlands) 1-174: Drukkerij, Imperator. R.

  12. The freshwater biodegradation potential of nine Alaskan oils

    International Nuclear Information System (INIS)

    Blenkinsopp, S.; Segy, G.

    1997-01-01

    Nine Alaskan representative crude oils and oil products with freshwater spill potential were collected, aged, and incubated in the presence of the standard freshwater inoculum for 28 days at 10 degrees C. Detailed analytical chemistry was performed on all samples to quantify compositional changes. All of the samples tested exhibited measurable hydrocarbon loss as a result of incubation with the freshwater inoculum. Total saturate and total n-alkane biodegradation were greatly enhanced when nutrients were present. The oil products Jet B Fuel and Diesel No. 2 appear to be more biodegradable than the Alaska North Slope and Cook Inlet crude oils tested, while the Bunker C/Diesel mixture appears to be less biodegradable than these crude oils. These results suggest that the screening procedures described here can provide useful information when applying bioremediation technology to the cleanup of selected oiled freshwater environments. 10 refs., 5 tabs., 13 figs

  13. Epigean freshwater Gammaridae (Crustacea, Amphipoda) from La Gomera (Canary Islands)

    NARCIS (Netherlands)

    Beyer, Gabriele; Stock, Jan H.

    1994-01-01

    Description of two new species of freshwater amphipods from La Gomera (Canary Islands), both found in the higher parts of the island: Chaetogammarus chaetocerus n. sp. and Rhipidogammarus gomeranus n. sp. Both species have distinct Afro- Iberian relationships.

  14. Freshwater conservation planning in South Africa: Milestones to ...

    African Journals Online (AJOL)

    2012-03-01

    Mar 1, 2012 ... freshwaters, implemented through a water resource classifica- tion system ... piled for each of South Africa's 19 Water Management Areas, which are ..... et al., 2011) and integrated water and land-use prioritisation. (Nel et al.

  15. New and interesting records of freshwater Verrucaria in Central Poland

    Directory of Open Access Journals (Sweden)

    Beata Krzewicka

    2013-12-01

    Full Text Available Verrucaria madida is reported as new to Poland. Three other associated species, V. aquatilis, V. hydrela and V. rheitrophila, are compared. The known distribution in Poland and the ecology of these freshwater species are presented.

  16. Conservation status and distribution of freshwater fishes in South ...

    African Journals Online (AJOL)

    Indigenous fishes include 43 species of the Zambezian faunal group (70% of the ... andrewi, Pseudobarbus afer) all of which are classified as Endangered. ... support only half of the freshwater fish species occurring in all national parks.

  17. Bibliography on cycling of trace metals in freshwater ecosystems

    International Nuclear Information System (INIS)

    LaRiviere, M.G.; Scott, A.J.; Woodfield, W.G.; Cushing, C.E.

    1978-07-01

    This bibliography is a listing of pertinent literature directly addressing the cycling of trace metals in freshwater ecosystems. Data on cycling, including the influences of environmental mediators, are included. 151 references

  18. The effects of carbamate pesticide on fish in freshwater ecosystems ...

    African Journals Online (AJOL)

    The effects of carbamate pesticide on fish in freshwater ecosystems: A review. ... organisms associated with uncontrolled use of pesticides in agriculture and other ... 85R and used in controlling soil insects and many insect pests of cash crops.

  19. In Silico characterization of growth hormone from freshwater ...

    African Journals Online (AJOL)

    dimensional (3D) structure prediction and evolutionary profile of growth hormone (GH) from 14 ornamental freshwater fishes. The analyses were performed using the sequence data of growth hormone gene (gh) and its encoded GH protein.

  20. Development of a passive sampler based on a polymer inclusion membrane for total ammonia monitoring in freshwaters.

    Science.gov (United States)

    Almeida, M Inês G S; Silva, Adélia M L; Coleman, Rhys A; Pettigrove, Vincent J; Cattrall, Robert W; Kolev, Spas D

    2016-05-01

    A passive sampler for determining the time-weighted average total ammonia (i.e. molecular ammonia and the ammonium cation) concentration (C TWA) in freshwaters, which incorporated a polymer inclusion membrane (PIM) as a semi-permeable barrier separating the aqueous source solution from the receiving solution (i.e. 0.8 mol L(-1) HCl), was developed for the first time. The PIM was composed of dinonylnaphthalene sulfonic acid (DNNS) as a carrier, poly (vinyl chloride) (PVC) as a base polymer and 1-tetradecanol as a modifier. Its optimal composition was found to be 35 wt% commercial DNNS, 55 wt% PVC and 10 wt% 1-tetradecanol. The effect of environmental variables such as the water matrix, pH and temperature were also studied using synthetic freshwaters. The passive sampler was calibrated under laboratory conditions using synthetic freshwaters and exhibited a linear response within the concentration range 0.59-2.8 mg L(-1) NH4(+) (0.46-2.1 mg N L(-1)) at 20 °C. The performance of the sampler was further investigated under field conditions over 7 days. A strong correlation between spot sampling and passive sampling was achieved, thus providing a proof-of-concept for the passive sampler for reliably measuring the C(TWA) of total ammonia in freshwaters, which can be used as an indicator in tracking sources of faecal contamination in stormwater drains.

  1. Gap analysis and conservation network for freshwater wetlands in Central Yangtze Ecoregion.

    Science.gov (United States)

    Xiaowen, Li; Haijin, Zhuge; Li, Mengdi

    2013-01-01

    The Central Yangtze Ecoregion contains a large area of internationally important freshwater wetlands and supports a huge number of endangered waterbirds; however, these unique wetlands and the biodiversity they support are under the constant threats of human development pressures, and the prevailing conservation strategies generated based on the local scale cannot adequately be used as guidelines for ecoregion-based conservation initiatives for Central Yangtze at the broad scale. This paper aims at establishing and optimizing an ecological network for freshwater wetland conservation in the Central Yangtze Ecoregion based on large-scale gap analysis. A group of focal species and GIS-based extrapolation technique were employed to identify the potential habitats and conservation gaps, and the optimized conservation network was then established by combining existing protective system and identified conservation gaps. Our results show that only 23.49% of the potential habitats of the focal species have been included in the existing nature reserves in the Central Yangtze Ecoregion. To effectively conserve over 80% of the potential habitats for the focal species by optimizing the existing conservation network for the freshwater wetlands in Central Yangtze Ecoregion, it is necessary to establish new wetland nature reserves in 22 county units across Hubei, Anhui, and Jiangxi provinces.

  2. Standard methods for sampling freshwater fishes: opportunities for international collaboration

    OpenAIRE

    Bonar, Scott A.; Mercado-Silva, Norman; Hubert, Wayne A.; Beard, T. Douglas; Dave, Göran; Kubečka, Jan; Graeb, Brian D.S.; Lester, Nigel P.; Porath, Mark; Winfield, Ian J.

    2017-01-01

    With publication of Standard Methods for Sampling North American Freshwater Fishes in 2009, the American Fisheries Society (AFS) recommended standard procedures for North America. To explore interest in standardizing at intercontinental scales, a symposium attended by international specialists in freshwater fish sampling was convened at the 145th Annual AFS Meeting in Portland, Oregon, in August 2015. Participants represented all continents except Australia and Antarctica and were employed by...

  3. Genetic calibration of species diversity among North America's freshwater fishes

    OpenAIRE

    April, Julien; Mayden, Richard L.; Hanner, Robert H.; Bernatchez, Louis

    2011-01-01

    Freshwater ecosystems are being heavily exploited and degraded by human activities all over the world, including in North America, where fishes and fisheries are strongly affected. Despite centuries of taxonomic inquiry, problems inherent to species identification continue to hamper the conservation of North American freshwater fishes. Indeed, nearly 10% of species diversity is thought to remain undescribed. To provide an independent calibration of taxonomic uncertainty and to establish a mor...

  4. Investigation of road salts and biotic stressors on freshwater wetland communities.

    Science.gov (United States)

    Jones, Devin K; Mattes, Brian M; Hintz, William D; Schuler, Matthew S; Stoler, Aaron B; Lind, Lovisa A; Cooper, Reilly O; Relyea, Rick A

    2017-02-01

    The application of road deicing salts has led to the salinization of freshwater ecosystems in northern regions worldwide. Increased chloride concentrations in lakes, streams, ponds, and wetlands may negatively affect freshwater biota, potentially threatening ecosystem services. In an effort to reduce the effects of road salt, operators have increased the use of salt alternatives, yet we lack an understanding of how these deicers affect aquatic communities. We examined the direct and indirect effects of the most commonly used road salt (NaCl) and a proprietary salt mixture (NaCl, KCl, MgCl 2 ), at three environmentally relevant concentrations (150, 470, and 780 mg Cl - /L) on freshwater wetland communities in combination with one of three biotic stressors (control, predator cues, and competitors). The communities contained periphyton, phytoplankton, zooplankton, and two tadpole species (American toads, Anaxyrus americanus; wood frogs, Lithobates sylvaticus). Overall, we found the two road salts did not interact with the natural stressors. Both salts decreased pH and reduced zooplankton abundance. The strong decrease in zooplankton abundance in the highest NaCl concentration caused a trophic cascade that resulted in increased phytoplankton abundance. The highest NaCl concentration also reduced toad activity. For the biotic stressors, predatory stress decreased whereas competitive stress increased the activity of both tadpole species. Wood frog survival, time to metamorphosis, and mass at metamorphosis all decreased under competitive stress whereas toad time to metamorphosis increased and mass at metamorphosis decreased. Road salts and biotic stressors can both affect freshwater communities, but their effects are not interactive. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Contrasting Responses of Marine and Freshwater Photosynthetic Organisms to UVB Radiation: A Meta-Analysis

    KAUST Repository

    Jin, Peng

    2017-03-14

    Ultraviolet-B (UVB) radiation is a global stressor that has profound impacts on freshwater and marine ecosystems. However, an analysis of the patterns of sensitivity to UVB radiation across aquatic photosynthetic organisms has not yet been published. Here, we performed a meta-analysis on results reported in 214 studies compiled from the published literature to quantify and compare the magnitude of responses of aquatic photosynthetic organisms to changes in UVB radiation. The meta-analysis was conducted on observations of marine (n = 893) and freshwater macroalgae (n = 126) and of marine (n = 1,087) and freshwater (n = 2,889) microalgae (total n = 4,995). Most of these studies (85%) analyzed the performance of organisms exposed to natural solar radiation when UVB was partially or totally reduced compared with the organismal performance under the full solar radiation spectrum, whereas the remaining 15% of the studies examined the responses of organisms to elevated UVB radiation mostly using artificial lamps. We found that marine photosynthetic organisms tend to be more sensitive than freshwater photosynthetic organisms to UVB radiation; responses to either decreased or increased UVB radiation vary among taxa; the mortality rate is the most sensitive of the trait responses to elevated UVB radiation, followed by changes in cellular and molecular traits; the sensitivity of microalgae to UVB radiation is dependent on size, with small-celled microalgae more sensitive than large-celled microalgae to UVB radiation. Thick macroalgae morphotypes were the less sensitive to UVB, but this effect could not be separated from phylogenetic differences. The high sensitivity of marine species, particularly the smallest photosynthetic organisms, to increased UVB radiation suggests that the oligotrophic ocean, a habitat comprising 70% of the world\\'s oceans with high UVB penetration and dominated by picoautotrophs, is extremely vulnerable to changes in UVB radiation.

  6. Mercury adsorption in the Mississippi River deltaic plain freshwater marsh soil of Louisiana Gulf coastal wetlands.

    Science.gov (United States)

    Park, Jong-Hwan; Wang, Jim J; Xiao, Ran; Pensky, Scott M; Kongchum, Manoch; DeLaune, Ronald D; Seo, Dong-Cheol

    2018-03-01

    Mercury adsorption characteristics of Mississippi River deltaic plain (MRDP) freshwater marsh soil in the Louisiana Gulf coast were evaluated under various conditions. Mercury adsorption was well described by pseudo-second order and Langmuir isotherm models with maximum adsorption capacity of 39.8 mg g -1 . Additional fitting of intraparticle model showed that mercury in the MRDP freshwater marsh soil was controlled by both external surface adsorption and intraparticle diffusion. The partition of adsorbed mercury (mg g -1 ) revealed that mercury was primarily adsorbed into organic-bond fraction (12.09) and soluble/exchangeable fraction (10.85), which accounted for 63.5% of the total adsorption, followed by manganese oxide-bound (7.50), easily mobilizable carbonate-bound (4.53), amorphous iron oxide-bound (0.55), crystalline Fe oxide-bound (0.41), and residual fraction (0.16). Mercury adsorption capacity was generally elevated along with increasing solution pH even though dominant species of mercury were non-ionic HgCl 2 , HgClOH and Hg(OH) 2  at between pH 3 and 9. In addition, increasing background NaCl concentration and the presence of humic acid decreased mercury adsorption, whereas the presence of phosphate, sulfate and nitrate enhanced mercury adsorption. Mercury adsorption in the MRDP freshwater marsh soil was reduced by the presence of Pb, Cu, Cd and Zn with Pb showing the greatest competitive adsorption. Overall the adsorption capacity of mercury in the MRDP freshwater marsh soil was found to be significantly influenced by potential environmental changes, and such factors should be considered in order to manage the risks associated with mercury in this MRDP wetland for responding to future climate change scenarios. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Development of indirect indicators for CO2 intrusion into freshwater

    International Nuclear Information System (INIS)

    Humez, P.

    2012-01-01

    This study deals with the impact of CO 2 leakages out of geological storage into overlying freshwater aquifers. Compared to other existing studies, the major added value of this study lies, on the one hand, in the research of new monitoring tools and isotopic approach in the context of CCS aiming at early and sensitive detection of CO 2 leakage and, on the other hand, in the application of these tools at the (limited) laboratory scale as well as at field scale. In order to test these tools, solid and liquid materials were sampled out of the major strategic drinking water Albian aquifer in the Paris Basin (France). We have then precisely characterized and used them within a batch experiment. This experiment yields interesting results which help understanding and constraining precisely the water-rock-CO 2 interactions as well as the isotopic responses. A real scale application of the method was then performed in Norway. It was an opportunity to develop this isotopic program and to track the isotopic evolution composition, while differentiating the natural processes and the system response to the CO 2 injection. When applied to the detection of CO 2 leakage context, the two case studies open the way for choosing the 'best' isotopic tools as indirect indicators of CO 2 presence in these specific systems. The efficiency of these isotopic tools comes from the recording of the CO 2 footprint all along the water-rock-CO 2 interactions. Using such tools imposes a rigorous methodology, which is tackled in this manuscript. Furthermore, future application will require adapting to the specifics of a proposed site. (author)

  8. Distribution of transuranic elements in a freshwater pond ecosystem

    International Nuclear Information System (INIS)

    Emery, R.M.; Klopfer, D.C.

    1976-01-01

    During the past two years a unique study has been initiated on the Hanford Reservation concerning the ecological behavior of plutonium and americium in a freshwater environment. This study involves a waste pond which has been receiving occasional low-level plutonium processing wastes for about 30 years. The pond has a sufficiently established ecosystem to provide an excellent location for limnological characterization. In addition, the ecological distribution of plutonium and americium is being investigated. The purpose of this work is to explain plutonium and americium concentrations at specific ecological sites, important export routes out of the pond, and potential pathways to man. The pond is also highly enriched with nutrients, thus supporting a high level of algal and macrophyte production. Seston (30 percent diatoms) appears to be the principal concentrator of transuranics in the pond system. The major sink for plutonium and americium in this system is the sediments. Organic floc, overlaying the pond sediments, is also a major concentrator of transuranics in this system. Aside from the seston and floc, no other ecological components of the pond appear to have concentrations significantly greater than those of the sediment. Dragonfly larvae, watercress, and snails show concentrations which approximate those of the sediments but nearly all other food web components have levels of plutonium and americium which are lower than those of the sediments. Thus, plutonium and americium seem to be relatively immobile in the aquatic ecosystem. However, the role of algae as a potential mechanism for the long-range ecological transport of plutonium and americium will receive additional attention

  9. Neoplastic changes in freshwater fishes: Correlation with oil refining

    International Nuclear Information System (INIS)

    Ostrander, G.K.

    1993-01-01

    Traditionally, oil pollution has been viewed as single event, large scale disasters such as the Exxon Valdez spill in Alaska. However, it is becoming increasingly apparent that by products and anthropogenic contaminants resulting from oil exploration, extraction, recovery, refining, and the manufacture and use of oil and oil-based products are negatively impacting the environment. Potential problems of freshwater pollution by oil contaminants are increasing in many parts of the world from both active and abandoned oil production facilities. In the USA many ''Superfund'' sites have been designated for cleanup under the Comprehensive Environmental Response, Compensation and Liability Act of 1980; primarily because of waste discharged on to the sites by the oil industry. Pollution of surface and groundwater from these sites has already occurred and in some cases has led to deleterious effects on the complex aquatic and terrestrial ecosystems on and near these sites. The effect of oil and oil related products on aquatic organisms will be reviewed. Specifically, the discussion will focus on preneoplastic and neoplastic changes in fishes with a primary endpoint of cancer. Finally, a summary of current studies of feral fishes residing on and near an abandoned oil refinery in Oklahoma will be presented

  10. Global imprint of historical connectivity on freshwater fish biodiversity.

    Science.gov (United States)

    Dias, Murilo S; Oberdorff, Thierry; Hugueny, Bernard; Leprieur, Fabien; Jézéquel, Céline; Cornu, Jean-François; Brosse, Sébastien; Grenouillet, Gael; Tedesco, Pablo A

    2014-09-01

    The relative importance of contemporary and historical processes is central for understanding biodiversity patterns. While several studies show that past conditions can partly explain the current biodiversity patterns, the role of history remains elusive. We reconstructed palaeo-drainage basins under lower sea level conditions (Last Glacial Maximum) to test whether the historical connectivity between basins left an imprint on the global patterns of freshwater fish biodiversity. After controlling for contemporary and past environmental conditions, we found that palaeo-connected basins displayed greater species richness but lower levels of endemism and beta diversity than did palaeo-disconnected basins. Palaeo-connected basins exhibited shallower distance decay of compositional similarity, suggesting that palaeo-river connections favoured the exchange of fish species. Finally, we found that a longer period of palaeo-connection resulted in lower levels of beta diversity. These findings reveal the first unambiguous results of the role played by history in explaining the global contemporary patterns of biodiversity. © 2014 John Wiley & Sons Ltd/CNRS.

  11. Exchange of certain radionuclides between environment and freshwater algae

    International Nuclear Information System (INIS)

    Marchyulenene, E. D.P.

    1978-01-01

    Data on the dynamics and levels of accumulation of strontium, cesium, cerium and ruthenium radionuclides by Charophyta and Cladophora fresh-water algae are presented. An attempt has been made to investigate some processes that accompany the accumulation of radionuclides by plants. Under experimental conditions, the intensity and levels of radionuclide accumulation can be presented in the following order: 144 Ce> 106 Ru> 90 Sr> 137 Cs. The dynamics of radionuclide accumulation varied greatly with the radionuclide and the algae species studied. The 144 Ce accumulation coefficients (AC) in the course of experiment (from 3 hours to 16 days) increased 8-, 9-, 23.4-, 27-, 14.3- and 20.4-fold for Cladophora glomerata, Nitella syncarpa, Nitellopsis obtusa, Chara vulgaris, Ch. rudis, and Ch. aspera, respectively. In the case of 106 Ru, AC for C.glomerata, N. syncarapa, Ch. vulgaris and Ch. rudis increased 34-, 18-,24- and 23-fold, respectively. In all algae species studied the equilibrium of radionuclide accumulation was attained after 2-4 days of experiment. Levels of accumulated 90 Sr and 137 Cs in most species depended on the season while that of 144 Cs and 106 Ru remained constant throughout the vegetation period. The levels of radionuclide elimination, like the accumulation levels, are shown to depend on both isotopes and algae species

  12. Electromagnetic methods for mapping freshwater lenses on Micronesian atoll islands

    Science.gov (United States)

    Anthony, S.S.

    1992-01-01

    The overall shape of freshwater lenses can be determined by applying electromagnetic methods and inverse layered-earth modeling to the mapping of atoll island freshwater lenses. Conductivity profiles were run across the width of the inhabited islands at Mwoakilloa, Pingelap, and Sapwuahfik atolls of the Pohnpei State, Federated States of Micronesia using a dual-loop, frequency-domain, electromagnetic profiling system. Six values of apparent conductivity were recorded at each sounding station and were used to interpret layer conductivities and/or thicknesses. A three-layer model that includes the unsaturated, freshwater, and saltwater zones was used to simulate apparent-conductivity data measured in the field. Interpreted results were compared with chloride-concentration data from monitoring wells and indicate that the interface between freshwater and saltwater layers, defined from electromagnetic data, is located in the upper part of the transition zone, where the chloride-concentration profile shows a rapid increase with depth. The electromagnetic method can be used to interpret the thickness of the freshwater between monitoring wells, but can not be used to interpret the thickness of freshwater from monitoring wells to the margin of an island. ?? 1992.

  13. Stormwater runoff drives viral community composition changes in inland freshwaters

    Science.gov (United States)

    Williamson, Kurt E.; Harris, Jamie V.; Green, Jasmin C.; Rahman, Faraz; Chambers, Randolph M.

    2014-01-01

    Storm events impact freshwater microbial communities by transporting terrestrial viruses and other microbes to freshwater systems, and by potentially resuspending microbes from bottom sediments. The magnitude of these impacts on freshwater ecosystems is unknown and largely unexplored. Field studies carried out at two discrete sites in coastal Virginia (USA) were used to characterize the viral load carried by runoff and to test the hypothesis that terrestrial viruses introduced through stormwater runoff change the composition of freshwater microbial communities. Field data gathered from an agricultural watershed indicated that primary runoff can contain viral densities approximating those of receiving waters. Furthermore, viruses attached to suspended colloids made up a large fraction of the total load, particularly in early stages of the storm. At a second field site (stormwater retention pond), RAPD-PCR profiling showed that the viral community of the pond changed dramatically over the course of two intense storms while relatively little change was observed over similar time scales in the absence of disturbance. Comparisons of planktonic and particle-associated viral communities revealed two completely distinct communities, suggesting that particle-associated viruses represent a potentially large and overlooked portion of aquatic viral abundance and diversity. Our findings show that stormwater runoff can quickly change the composition of freshwater microbial communities. Based on these findings, increased storms in the coastal mid-Atlantic region predicted by most climate change models will likely have important impacts on the structure and function of local freshwater microbial communities. PMID:24672520

  14. Climate change, agricultural insecticide exposure, and risk for freshwater communities.

    Science.gov (United States)

    Kattwinkel, Mira; Kühne, Jan-Valentin; Foit, Kaarina; Liess, Matthias

    2011-09-01

    Climate change exerts direct effects on ecosystems but has additional indirect effects due to changes in agricultural practice. These include the increased use of pesticides, changes in the areas that are cultivated, and changes in the crops cultivated. It is well known that pesticides, and in particular insecticides, affect aquatic ecosystems adversely. To implement effective mitigation measures it is necessary to identify areas that are affected currently and those that will be affected in the future. As a consequence, we predicted potential exposure to insecticide (insecticide runoff potential, RP) under current conditions (1990) and under a model scenario of future climate and land use (2090) using a spatially explicit model on a continental scale, with a focus on Europe. Space-for-time substitution was used to predict future levels of insecticide application, intensity of agricultural land use, and cultivated crops. To assess the indirect effects of climate change, evaluation of the risk of insecticide exposure was based on a trait-based, climate-insensitive indicator system (SPEAR, SPEcies At Risk). To this end, RP and landscape characteristics that are relevant for the recovery of affected populations were combined to estimate the ecological risk (ER) of insecticides for freshwater communities. We predicted a strong increase in the application of, and aquatic exposure to, insecticides under the future scenario, especially in central and northern Europe. This, in turn, will result in a severe increase in ER in these regions. Hence, the proportion of stream sites adjacent to arable land that do not meet the requirements for good ecological status as defined by the EU Water Framework Directive will increase (from 33% to 39% for the EU-25 countries), in particular in the Scandinavian and Baltic countries (from 6% to 19%). Such spatially explicit mapping of risk enables the planning of adaptation and mitigation strategies including vegetated buffer strips and

  15. Organic environmental poisons in Norwegian freshwater fish

    International Nuclear Information System (INIS)

    2002-01-01

    According to this article, the level of organic poisons in Norwegian freshwater fish is, on the whole, is too small to threaten human health. It has been found, however, that liver from some species such as burbot, from some lakes, should not be eaten. These lakes are found to contain higher levels of PCB (polychlorinated biphenyls) and DDT (dichlorodiphenyltrichloroethane). Previously, pregnant or breast-feeding women anywhere in Norway have been advised not to eat pike, large perch or large trout because of too much mercury. Other people should not eat these species more often than once per month. In general, the level of organic environmental poisons is higher in the southern part of the country than in the northern part. The sediments of the lakes in large parts of South Norway are contaminated with lead, mercury and cadmium as compared with the conditions before the industrial revolution. However, the level of metals in the lake sediments are relatively low, and these substances are unlikely to appear in the food chain, by and large. The anthropogenic emission of lead was insignificant before the industrial revolution. The exception of lead from German mining industry in the 1700s

  16. Cyanobacteria and cyanotoxins in freshwaters of Uruguay

    Directory of Open Access Journals (Sweden)

    Sylvia Bonilla

    2015-12-01

    Full Text Available Cyanobacterial blooms are a worldwide environmental problem. This phenomenon is typically associated with eutrophication (nutrient enrichment and changes in hydrology. In this study we analysed the distribution of planktonic cyanobacteria in Uruguay and their toxins (microcystin, saxitoxin and cylindrospermopsin, working with an interagency team (OSE, DINAMA, IM, University of the Republic and IIBCE. An historical data base (n = 3061 for 64 ecosystems, years 1980-2014 was generated. Differences between lotic and lentic ecosystems were found in terms of chlorophyll a and nutrient concentrations, usually indicating eutrophication. Two geo-referenced maps for the country were generated with cyanobacteria biomass indicators and the most relevant toxin (microcystin, according to risk levels suggested by the World Health Organization for recreational waters. The areas of greatest risk of exposure were the reservoirs of large rivers (Uruguay and Río Negro and Río de la Plata beaches. In the second part of the study, up to 20 mg L-1of microcystin was quantified in bloom (scum samples, as well as the presence of genes that suggest more microcystin varieties, potentially with greater toxicity. This study provides basic information about the distribution of cyanobacteria in Uruguayan freshwaters that will be useful for national monitoring programs and scientific research.

  17. The International Editorship of Freshwater Systems

    Directory of Open Access Journals (Sweden)

    Karl E. Havens

    2001-01-01

    Full Text Available It is my pleasure to announce that two distinguished internationalscientists have joined the editorship of the FreshwaterSystems domain of TheScientificWorldJOURNAL — Professor BrijGopal of Jawaharlal Nehru University (India and Dr. Manual Gra柠of the Universityof Coimbra (Portugal. Professor Gopal is the Secretary General of the NationalInstitute of Ecology, Editor of the InternationalJournal of Ecology & Environmental Science,and Chairman of the SIL (International Association of Theoretical and AppliedLimnology Committee on Limnology in Developing Countries. His research interestsinclude the ecology, biogeochemistry and biodiversity of wetland ecosystems,the management of wetlands as an integral part of the watershed, and wetlandwater policy–related issues. Dr. Gra柠is a stream ecologist whose researchinterests include the two general areas of organic matter decomposition andbiological monitoring. His specific areas of research focus include quantificationof organic matter and other chemical changes in decomposing leaves, the ecologyof aquatic hyphomycetes, and the ecology of animals feeding on detritus. Hisresearch dealing with biological monitoring is carried out in close cooperationwith the paper and mining industries, facilitating the practical applicationof his work.

  18. Photosynthetic carbon metabolism in freshwater phytoplankton

    International Nuclear Information System (INIS)

    Groeger, A.W.

    1986-01-01

    Photosynthetic carbon metabolism of natural assemblages of freshwater phytoplankton was measured by following the flow of inorganic 14 C into the photosynthetic end products polysaccharide protein, lipid, and soluble metabolites. Data were collected from a wide range of physical, chemical, and trophic conditions in six southern United States reservoirs, with the primary environmental variables of interest being light intensity and nutrient supply. Polysaccharide and protein were consistently the primary products of photosynthetic carbon metabolism, comprising an average of 70% of the total carbon fixation over a wide range of light intensities. Polysaccharide was quantitatively more important at higher light intensities, and protein at lower light intensities, as light intensity varied both with depth within the water column and over diurnal cycles. Polysaccharide synthesis was more variable over the diurnal period than was protein synthesis. Phytoplankton in the downlake epilimnion of Normandy Lake, a central Tennessee reservoir, responded to summer nitrogen (N) deficiency by increasing relative rates of lipid synthesis from 10-15% to 20-25% of the total photosynthetic carbon fixation. Phytoplankton in more nitrogen-sufficient areas of the reservoir maintained lower rates of lipid synthesis throughout the summer. These results document the occurrence in nature of a relationship between N-deficiency and increased lipid synthesis previously observed only in laboratory algal culture studies

  19. IOLOGICAL IMPORTANCE AND TOXICITY OF HEAVY METALS FOR BIOTA OF FRESHWATER BODIES (REVIEW)

    OpenAIRE

    I. Hrytsyniak; N. Kolesnyk

    2014-01-01

    Purpose. To investigate the sources of scientific information on biological functions of heavy metals (Fe, Zn, Mn, Cu, Ni, Co, Pb, Cd) and their negative effect on biota of fresh water bodies. Findings. A review of works of a variety of scientists showed that the majority of the studied heavy metals (Fe, Zn, Mn, Cum and Co) played an important role in vital functions of freshwater organisms. The significance of other studied heavy metals (Ni, Pb, and Cd) is probable or unknown. Besides bi...

  20. Diversity of sulfur-cycle prokaryotes in freshwater lake sediments investigated using aprA as the functional marker gene.

    Science.gov (United States)

    Watanabe, Tomohiro; Kojima, Hisaya; Takano, Yoshinori; Fukui, Manabu

    2013-09-01

    The diversity of sulfate-reducing prokaryotes (SRPs) and sulfur-oxidizing prokaryotes (SOPs) in freshwater lake ecosystems was investigated by cloning and sequencing of the aprA gene, which encodes for a key enzyme in dissimilatory sulfate reduction and sulfur oxidation. To understand their diversity better, the spatial distribution of aprA genes was investigated in sediments collected from six geographically distant lakes in Antarctica and Japan, including a hypersaline lake for comparison. The microbial community compositions of freshwater sediments and a hypersaline sediment showed notable differences. The clones affiliated with Desulfobacteraceae and Desulfobulbaceae were frequently detected in all freshwater lake sediments. The SOP community was mainly composed of four major phylogenetic groups. One of them formed a monophyletic cluster with a sulfur-oxidizing betaproteobacterium, Sulfuricella denitrificans, but the others were not assigned to specific genera. In addition, the AprA sequences, which were not clearly affiliated to either SRP or SOP lineages, dominated the libraries from four freshwater lake sediments. The results showed the wide distribution of some sulfur-cycle prokaryotes across geographical distances and supported the idea that metabolic flexibility is an important feature for SRP survival in low-sulfate environments. Copyright © 2013 Elsevier GmbH. All rights reserved.

  1. Differential effects of P25 TiO2 nanoparticles on freshwater green microalgae: Chlorella and Scenedesmus species.

    Science.gov (United States)

    Roy, Rajdeep; Parashar, Abhinav; Bhuvaneshwari, M; Chandrasekaran, N; Mukherjee, Amitava

    2016-07-01

    P25 TiO2 nanoparticles majorly used in cosmetic products have well known detrimental effects towards the aquatic environment. In a freshwater ecosystem, Chlorella and Scenedesmus are among the most commonly found algal species frequently used to study the effects of metal oxide nanoparticles. A comparative study has been conducted herein to investigate differences in the toxic effects caused by these nanoparticles towards the two algae species. The three different concentrations of P25 TiO2 NPs (0.01, 0.1 & 1μg/mL, i.e., 0.12, 1.25 and 12.52μM) were selected to correlate surface water concentrations of the nanoparticles, and filtered and sterilized fresh water medium was used throughout this study. There was significant increase (pScenedesmus under only visible light (pScenedesmus species, which could easily be correlated with the uptake of the NPs. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Crenothrix are major methane consumers in stratified lakes.

    Science.gov (United States)

    Oswald, Kirsten; Graf, Jon S; Littmann, Sten; Tienken, Daniela; Brand, Andreas; Wehrli, Bernhard; Albertsen, Mads; Daims, Holger; Wagner, Michael; Kuypers, Marcel Mm; Schubert, Carsten J; Milucka, Jana

    2017-09-01

    Methane-oxidizing bacteria represent a major biological sink for methane and are thus Earth's natural protection against this potent greenhouse gas. Here we show that in two stratified freshwater lakes a substantial part of upward-diffusing methane was oxidized by filamentous gamma-proteobacteria related to Crenothrix polyspora. These filamentous bacteria have been known as contaminants of drinking water supplies since 1870, but their role in the environmental methane removal has remained unclear. While oxidizing methane, these organisms were assigned an 'unusual' methane monooxygenase (MMO), which was only distantly related to 'classical' MMO of gamma-proteobacterial methanotrophs. We now correct this assignment and show that Crenothrix encode a typical gamma-proteobacterial PmoA. Stable isotope labeling in combination swith single-cell imaging mass spectrometry revealed methane-dependent growth of the lacustrine Crenothrix with oxygen as well as under oxygen-deficient conditions. Crenothrix genomes encoded pathways for the respiration of oxygen as well as for the reduction of nitrate to N 2 O. The observed abundance and planktonic growth of Crenothrix suggest that these methanotrophs can act as a relevant biological sink for methane in stratified lakes and should be considered in the context of environmental removal of methane.

  3. Determination of thermal stability of specific biomarker lipids of the freshwater fern Azolla through hydrous pyrolysis

    Science.gov (United States)

    Sap, Merel; Speelman, Eveline N.; Lewan, Michael D.; Sinninghe Damsté, Jaap S.; Reichart, Gert-Jan

    2010-05-01

    Enormous blooms of the free-floating freshwater fern Azolla occurred within the Arctic Basin during an extended period of ~1.2 Ma during the middle Eocene (Brinkhuis et al. 2006; Speelman et al., GB, 2009). The sustained growth of Azolla, currently ranking among the fastest growing plants on Earth, in a major anoxic basin may have substantially contributed to decreasing atmospheric CO2 levels by burial of Azolla-derived organic matter. Speelman et al. (OG, 2009) reported biomarkers for Azolla (1,w20 C32 - C36 diols, structurally related C29 ω20,ω21 diols, C29 1,20,21 triols, C29 dihydroxy fatty acids as well as a series of wax esters containing these mono- and dihydroxy lipids), which can be used to reconstruct palaeo-environmental conditions. Here we assess the thermal stability of these compounds, to extend their biomarker potential. We specifically focused on the thermal stability of the Azolla biomarkers using hydrous pyrolysis in order to determine which burial conditions allow reconstruction of past occurrences of Azolla. In addition, hydrous pyrolysis was also performed on samples from the Eocene Arctic Ocean (ACEX core), to test if and how the biomarkers change under higher temperatures and pressures in situ. During hydrous pyrolysis, the biomass was heated under high pressure at temperatures ranging between 220 and 365°C for 72 hours. Four experiments were also run using different durations to explore the kinetics of biomarker degradation at specific temperatures. First results indicate that the Azolla specific diols are still present at 220°C, while the corresponding wax esters are already absent. At 300°C all Azolla specific biomarkers are destroyed. More specific determination of the different biomarkers' stability and kinetics would potentially allow the reconstruction of the temperature and pressure history of Azolla deposits. Literature: • Brinkhuis, H., Schouten, S., Collinson, M. E., Sluijs, A., Sinninghe Damste, J. S., Dickens, G. R., Huber

  4. Mating competitiveness of sterile genetic sexing strain males (GAMA) under laboratory and semi-field conditions: Steps towards the use of the Sterile Insect Technique to control the major malaria vector Anopheles arabiensis in South Africa.

    Science.gov (United States)

    Munhenga, Givemore; Brooke, Basil D; Gilles, Jeremie R L; Slabbert, Kobus; Kemp, Alan; Dandalo, Leonard C; Wood, Oliver R; Lobb, Leanne N; Govender, Danny; Renke, Marius; Koekemoer, Lizette L

    2016-03-02

    Anopheles arabiensis Patton is primarily responsible for malaria transmission in South Africa after successful suppression of other major vector species using indoor spraying of residual insecticides. Control of An. arabiensis using current insecticide based approaches is proving difficult owing to the development of insecticide resistance, and variable feeding and resting behaviours. The use of the sterile insect technique as an area-wide integrated pest management system to supplement the control of An. arabiensis was proposed for South Africa and is currently under investigation. The success of this technique is dependent on the ability of laboratory-reared sterile males to compete with wild males for mates. As part of the research and development of the SIT technique for use against An. arabiensis in South Africa, radio-sensitivity and mating competitiveness of a local An. arabiensis sexing strain were assessed. The optimal irradiation dose inducing male sterility without compromising mating vigour was tested using Cobalt 60 irradiation doses ranging from 70-100 Gy. Relative mating competitiveness of sterile laboratory-reared males (GAMA strain) compared to fertile wild-type males (AMAL strain) for virgin wild-type females (AMAL) was investigated under laboratory and semi-field conditions using large outdoor cages. Three different sterile male to fertile male to wild-type female ratios were evaluated [1:1:1, 5:1:1 and 10:1:1 (sterile males: fertile, wild-type males: fertile, wild-type females)]. Irradiation at the doses tested did not affect adult emergence but had a moderate effect on adult survivorship and mating vigour. A dose of 75 Gy was selected for the competitiveness assays. Mating competitiveness experiments showed that irradiated GAMA male mosquitoes are a third as competitive as their fertile AMAL counterparts under semi-field conditions. However, they were not as competitive under laboratory conditions. An inundative ratio of 10:1 induced the

  5. Growth and biochemical characteristics of an indigenous freshwater microalga, Scenedesmus obtusus, cultivated in an airlift photobioreactor: effect of reactor hydrodynamics, light intensity, and photoperiod.

    Science.gov (United States)

    Sarat Chandra, T; Aditi, S; Maneesh Kumar, M; Mukherji, S; Modak, J; Chauhan, V S; Sarada, R; Mudliar, S N

    2017-07-01

    The freshwater green algae, Scenedesmus obtusus, was cultivated in a 3.4 L airlift photobioreactor. The hydrodynamic parameters were estimated at different inlet gas flow rates (1, 2, 3, and 4 LPM) and their subsequent impact on the growth and biochemical characteristics of microalgae was studied. The biomass concentration and productivity increased with an increase in flow rates from 1 to 4 LPM. A maximum of 0.07 g L -1  day -1 productivity of biomass was attained at 3 LPM. An increase of total carbohydrate content from 19.6 to 26.4% was noticed with increment in the inlet flow rate of gas from 1 to 4 LPM. Major variations in total fatty acid content were not observed. The impact of light irradiance on growth and biochemical characteristics of S. obtusus was also evaluated. A maximum biomass productivity of 0.103 g L -1  day -1 was attained at an illumination of 150 μmol m -2  s -1 under continuous light. The major fatty acids reported were palmitic acid (C16:0), α-linolenic acid (C18:3), linoleic acid (C18:2), and oleic acid (C18:1). Biodiesel properties of the microalgae were estimated under various culture conditions. The light profile inside the airlift reactor was experimentally measured and the predictive modelling of light profile was also attempted.

  6. Effects of UV radiation on freshwater metazooplankton

    International Nuclear Information System (INIS)

    Tartarotti, B.

    1999-06-01

    There is evidence that fluxes of solar ultraviolet-B radiation (UV-B, 290-320 nm) are increasing over wide parts of the earth's surface due to stratospheric ozone depletion. UV radiation (290-400 nm) can have damaging effects on biomolecules and cell components that are common to most living organisms. The aim of this thesis is to gain a more thorough understanding of the potential impacts of solar radiation on freshwater metazooplankton. To detect UV-vulnerability in zooplankton populations dominating the zooplankton community of two clear-water, high mountain lakes located one in the Austrian Alps and another in the Chilean Andes, the survival of two copepod species was studied. The organisms were exposed to a 10- to 100-fold increase in UV-B radiation compared to those levels found at their natural, maximum daytime distribution. Both species vertically migrate and are pigmented. UV-absorbing compounds with a maximum absorption at ∼334 nm were also detected. Cyclops abyssorum tatricus, a common cyclopoid copepod species of Alpine lakes, was highly resistant to UV-B radiation and no significant lethal effect was observed. The calanoid copepod Boeckella gracilipes, frequent in Andean lakes, had a mortality ∼5 times higher in the treatment receiving full sunlight than in the UV-B excluded treatment (3.2 %) only when exposed for 70 h. The resistance of B. gracilipes was higher than that reported in the literature for the same species suggesting the existence of intraspecific differences in UV sensitivity. Survival, fecundity and development of the zooplankton community of a clear-water, high elevation Andean lake (33 o S) were studied with mesocosms experiments after prolonged UV exposure (48 days). When exposed to full sunlight, the population of the cladoceran Chydorus sphaericus and the rotifer Lepadella ovalis were strongly inhibited by UV-B, whereas both species were resistant to UV-A radiation. Conversely, UV-B radiation had no effect on the survival of the

  7. Behavior of technetium in freshwater environments

    Energy Technology Data Exchange (ETDEWEB)

    Blaylock, B.G.; Frank, M.L.; Hoffman, F.O.; DeAngelis, D.L.

    1984-01-01

    In a previous study, /sup 95m/Tc, as a pertechnetate, was released to a small, experimental, freshwater pond, and the concentrations were determined in biotic and abiotic components of the pond ecosystem. A simple mathematical model was developed to predict the concentration of /sup 95m/Tc in fish and snails. Results from this study indicated that uptake through the food chain was an important source of technetium to the higher trophic levels (i.e., fish). In the current study, an experimental pond was spiked with /sup 95m/Tc in the pertechnetate form, and the concentrations of /sup 95m/Tc were measured in the lower trophic levels. Emphasis was placed on measuring the concentration of /sup 95m/Tc in zooplankton, benthic invertebrates, and the aquatic macrophyte Elodea canadensis. Fish were excluded from the pond to allow the development of a large zooplankton population. The concentration of /sup 95m/Tc in water decreased from 0.75 Bq/mL 1 h after the pond was spiked, to 0.21 Bq/mL at 20 d. Throughout the experiment, at least 98% of the /sup 95m/Tc in the water was in the dissolved fraction (0.4 ..mu..m). Zooplankton accumulated /sup 95m/Tc rapidly, having concentration factors (Bq/g sample wet wt. divided by Bq/g water) ranging from 3 at 4 h to 36 at 20 d. Concentration factors ranged from 3 to 8 for benthic insects and from 1 to 62 for the aquatic macrophyte.

  8. Behavior of technetium in freshwater environments

    International Nuclear Information System (INIS)

    Blaylock, B.G.; Frank, M.L.; Hoffman, F.O.; DeAngelis, D.L.

    1984-01-01

    In a previous study, /sup 95m/Tc, as a pertechnetate, was released to a small, experimental, freshwater pond, and the concentrations were determined in biotic and abiotic components of the pond ecosystem. A simple mathematical model was developed to predict the concentration of /sup 95m/Tc in fish and snails. Results from this study indicated that uptake through the food chain was an important source of technetium to the higher trophic levels (i.e., fish). In the current study, an experimental pond was spiked with /sup 95m/Tc in the pertechnetate form, and the concentrations of /sup 95m/Tc were measured in the lower trophic levels. Emphasis was placed on measuring the concentration of /sup 95m/Tc in zooplankton, benthic invertebrates, and the aquatic macrophyte Elodea canadensis. Fish were excluded from the pond to allow the development of a large zooplankton population. The concentration of /sup 95m/Tc in water decreased from 0.75 Bq/mL 1 h after the pond was spiked, to 0.21 Bq/mL at 20 d. Throughout the experiment, at least 98% of the /sup 95m/Tc in the water was in the dissolved fraction (0.4 μm). Zooplankton accumulated /sup 95m/Tc rapidly, having concentration factors (Bq/g sample wet wt. divided by Bq/g water) ranging from 3 at 4 h to 36 at 20 d. Concentration factors ranged from 3 to 8 for benthic insects and from 1 to 62 for the aquatic macrophyte

  9. A Probabilistic Assessment of the Chemical and Radiological Risks of Chronic Exposure to Uranium in Freshwater Ecosystems

    International Nuclear Information System (INIS)

    Mathews, T.; Beaugelin-Seiller, K.; Garnier-Laplace, J.; Gilbin, R.; Adam, Ch.; Della-Vedova, C.

    2009-01-01

    Uranium (U) presents a unique challenge for ecological risk assessments (ERA) because it induces both chemical and radiological toxicity, and the relative importance of these two toxicities differs among the various U source terms (i.e., natural, enriched, depleted). We present a method for the conversion between chemical concentrations (μgL -1 ) and radiological dose rates (μGyh -1 ) for a defined set of reference organisms, and apply this conversion method to previously derived chemical and radiological benchmarks to determine the extent to which these benchmarks ensure radiological and chemical protection, respectively, for U in freshwater ecosystems. Results show that the percentage of species radiologically protected by the chemical benchmark decreases with increasing degrees of U enrichment and with increasing periods of radioactive decay. In contrast, the freshwater ecosystem is almost never chemically protected by the radiological benchmark, regardless of the source term or decay period considered, confirming that the risks to the environment from uranium's chemical toxicity generally outweigh those of its radiological toxicity. These results are relevant to developing water quality criteria that protect freshwater ecosystems from the various risks associated with the nuclear applications of U exploitation, and highlight the need for (1) further research on the speciation, bioavailability, and toxicity of U-series radionuclides under different environmental conditions, and (2) the adoption of both chemical and radiological benchmarks for coherent ERAS to be conducted in U-contaminated freshwater ecosystems. (authors)

  10. The potential impacts of climate-change policy on freshwater use in thermoelectric power generation

    International Nuclear Information System (INIS)

    Chandel, Munish K.; Pratson, Lincoln F.; Jackson, Robert B.

    2011-01-01

    Climate change policy involving a price on carbon would change the mix of power plants and the amount of water they withdraw and consume to generate electricity. We analyze what these changes could entail for electricity generation in the United States under four climate policy scenarios that involve different costs for emitting CO 2 and different technology options for reducing emissions out to the year 2030. The potential impacts of the scenarios on the U.S. electric system are modeled using a modified version of the U.S. National Energy Modeling System and water-use factors for thermoelectric power plants derived from electric utility data compiled by the U.S. Energy Information Administration. Under all the climate-policy scenarios, freshwater withdrawals decline 2-14% relative to a business-as-usual (BAU) scenario of no U.S. climate policy. Furthermore, water use decreases as the price on CO 2 under the climate policies increases. At relatively high carbon prices (>$50/tonne CO 2 ), however, retrofitting coal plants to capture CO 2 increases freshwater consumption compared to BAU in 2030. Our analysis suggests that climate policies and a carbon price will reduce both electricity generation and freshwater withdrawals compared to BAU unless a substantial number of coal plants are retrofitted to capture CO 2 . - Highlights: → We analyze the impact of climate change policy on water use for electricity generation. → Water use decreases with an increase in CO 2 allowance price. → Retrofitting of coal plants with CCS could increase water use considerably.

  11. Potential impacts of global climate change on the hydrology and ecology of ephemeral freshwater systems of the forests of the northeastern United States

    Science.gov (United States)

    Robert T. Brooks

    2009-01-01

    Global, national, and regional assessments of the potential effects of Global Climate Change (GCC) have been recently released, but not one of these assessments has specifically addressed the critical issue of the potential impacts of GCC on ephemeral freshwater systems (EFS). I suggest that this is a major oversight as EFS occur in various forms across the globe. In...

  12. The relative sensitivity of freshwater species to antimony(III): Implications for water quality guidelines and ecological risk assessments.

    Science.gov (United States)

    Obiakor, Maximilian Obinna; Tighe, Matthew; Wang, Zhen; Ezeonyejiaku, Chigozie Damian; Pereg, Lily; Wilson, Susan C

    2017-11-01

    Antimony (Sb) is a pollutant in many jurisdictions, yet its threat to aquatic biota is unclear. Water quality guidelines (WQGs) for Sb are not well established and large uncertainty factors are commonly applied in derivation. We constructed freshwater species sensitivity distributions (SSDs) for Sb(III) using available acute toxicity data sourced from temperate and tropical regional studies. A tiered ecological risk assessment (ERA) approach using risk quotients (RQs) was applied for characterisation of risks presented by Sb(III) concentrations measured in the freshwater environment. Multiple parametric models were fitted for each SSD, with the optimal model used to derive the 5% hazardous concentration (HC5), defined as protective of 95% of species, and the corresponding predicted no effect concentration (PNEC). The HC5 values for whole and temperate SSDs were estimated at 781 and 976 μg L -1 Sb(III), respectively, while the PNECs for both datasets were 156 and 195 μg L -1 Sb(III), respectively. Due to limited tropical data, a temperate-to-tropic extrapolation factor of 10 was used to estimate an interim PNEC for tropical regions of 20 μg L -1 Sb(III). Based on published freshwater Sb(III) concentration values across a range of locations, potential ecological risks posed by Sb(III) in some freshwater systems studied would be classified as medium to high risk, but the majority of locations sampled would fall into the low ecological risk category. Our results facilitate the understanding of toxic effects of Sb(III) to freshwater species but also demonstrate that data for Sb ERA are extremely limited.

  13. In-situ and laboratory study of radiocaesium mobility in freshwater sediments

    International Nuclear Information System (INIS)

    Comans, R.N.J.; Bonouvrie, P.A.; Lange, G.J. de

    1992-09-01

    The title project was designed to identify areas of our understanding of the transport of radionuclides through aquatic environments and uptake by fish which limit the general applicability of the present generation of mathematical models. The initial programme concentrated on four areas: 1. Chemical processes underlying adsorption onto particles; 2. The processes involved in the enhanced transport of radio- caesium from some catchments; 3. Processes of remobilization in sediments and at the seawater/freshwater interface; 4. Effects of water chemistry and the ecology of aquatic organisms on the uptake, storage and excretion of radio- nuclides. (author). 6 refs., 5 figs

  14. Hormesis response of marine and freshwater luminescent bacteria to metal exposure

    Directory of Open Access Journals (Sweden)

    KAILI SHEN

    2009-01-01

    Full Text Available The stimulatory effect of low concentrations of toxic chemicals on organismal metabolism, referred to as hormesis, has been found to be common in the widely used luminescence bioassay. This paper aims to study the hormesis phenomenon in both marine and freshwater luminescent bacteria, named Photobacterium phosphorem and Vibrio qinghaiensis. The effects of Cu (II, Zn (II, Cd (II and Cr (VI on luminescence of these two bacteria were studied for 0 to 75 minutes exposure by establishing dose- and time-response curves. A clear hormesis phenomenon was observed in all four testing metals at low concentrations under the condition of luminescence assays.

  15. Key roles for freshwater Actinobacteria revealed by deep metagenomic sequencing.

    Science.gov (United States)

    Ghai, Rohit; Mizuno, Carolina Megumi; Picazo, Antonio; Camacho, Antonio; Rodriguez-Valera, Francisco

    2014-12-01

    Freshwater ecosystems are critical but fragile environments directly affecting society and its welfare. However, our understanding of genuinely freshwater microbial communities, constrained by our capacity to manipulate its prokaryotic participants in axenic cultures, remains very rudimentary. Even the most abundant components, freshwater Actinobacteria, remain largely unknown. Here, applying deep metagenomic sequencing to the microbial community of a freshwater reservoir, we were able to circumvent this traditional bottleneck and reconstruct de novo seven distinct streamlined actinobacterial genomes. These genomes represent three new groups of photoheterotrophic, planktonic Actinobacteria. We describe for the first time genomes of two novel clades, acMicro (Micrococcineae, related to Luna2,) and acAMD (Actinomycetales, related to acTH1). Besides, an aggregate of contigs belonged to a new branch of the Acidimicrobiales. All are estimated to have small genomes (approximately 1.2 Mb), and their GC content varied from 40 to 61%. One of the Micrococcineae genomes encodes a proteorhodopsin, a rhodopsin type reported for the first time in Actinobacteria. The remarkable potential capacity of some of these genomes to transform recalcitrant plant detrital material, particularly lignin-derived compounds, suggests close linkages between the terrestrial and aquatic realms. Moreover, abundances of Actinobacteria correlate inversely to those of Cyanobacteria that are responsible for prolonged and frequently irretrievable damage to freshwater ecosystems. This suggests that they might serve as sentinels of impending ecological catastrophes. © 2014 John Wiley & Sons Ltd.

  16. IOLOGICAL IMPORTANCE AND TOXICITY OF HEAVY METALS FOR BIOTA OF FRESHWATER BODIES (REVIEW

    Directory of Open Access Journals (Sweden)

    I. Hrytsyniak

    2014-06-01

    Full Text Available Purpose. To investigate the sources of scientific information on biological functions of heavy metals (Fe, Zn, Mn, Cu, Ni, Co, Pb, Cd and their negative effect on biota of fresh water bodies. Findings. A review of works of a variety of scientists showed that the majority of the studied heavy metals (Fe, Zn, Mn, Cum and Co played an important role in vital functions of freshwater organisms. The significance of other studied heavy metals (Ni, Pb, and Cd is probable or unknown. Besides biological importance, we also know about toxicity of heavy metals – a group of mineral polluting substances, which are the most distributed and dangerous for biota. Their negative effect includes drastic deterioration of conditions for existence of the majority of aquatic organisms, some species disappear, others reduce their number, components of trophic chains are lost, links in ecosystems become broken, and productivity of biocenoses decreases. Practical value. An array of generalized information will be useful for scientists who investigate freshwater ecosystems and effect of toxicants on them, in particular heavy metals.

  17. 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

  18. Characterization of Ras k 1 a novel major allergen in Indian mackerel and identification of parvalbumin as the major fish allergen in 33 Asia-Pacific fish species.

    Science.gov (United States)

    Ruethers, T; Raith, M; Sharp, M F; Koeberl, M; Stephen, J N; Nugraha, R; Le, T T K; Quirce, S; Nguyen, H X M; Kamath, S D; Mehr, S S; Campbell, D E; Bridges, C R; Taki, A C; Swoboda, I; Lopata, A L

    2018-04-01

    Fish is a well-recognized cause of food allergy and anaphylaxis. The evolutionary and taxonomic diversity of the various consumed fish species pose a challenge in the identification and characterization of the major fish allergens critical for reliable diagnostics. Globally, fish is a rising cause of food allergy complicated by a large under-investigated variety of species as well as increasing global tourism and trade. This is the first comprehensive study on allergen profiles of heat-processed fish from Vietnam. The aim of this study was to identify the major heat-stable allergens from frequently exported Asia-Pacific freshwater and marine fish and to characterize the major allergen parvalbumin (PV) from one of the most consumed and exported fish species from Asia, the Indian mackerel (Rastrelliger kanagurta). Heated protein extracts from 33 fish species were separated by gel electrophoresis. PV isoforms were identified by immunoblotting utilizing 3 different PV-specific monoclonal and polyclonal antibodies and further characterized by mass spectrometry. IgE reactivity was investigated using sera from 21 patients with confirmed fish allergy. Heat-stable IgE-reactive PVs, with up to 5 isoforms per species, were identified in all 33 analysed fish species. In the Indian mackerel, 7 PV isoforms were identified by 2D-gel electrophoresis combined with mass spectrometric analyses. The amino acid sequence deduced from cDNA of the most expressed isoform showed a high identity (>90%) to PVs from 2 other mackerel species. Different PVs were identified as the major heat-stable allergens in all 33 analysed freshwater and marine fish species from Vietnam, many of which are exported world-wide and 21 species that have never been investigated before. The Indian mackerel PV represents a novel fish allergen, now officially registered as Ras k 1. Improved diagnostics for fish allergy against Asia-Pacific species should be developed with focus on PV. © 2017 John Wiley & Sons Ltd.

  19. Determining paths by which farmers can adapt effectively to scarce freshwater resources

    Science.gov (United States)

    Watson, R.; Hornberger, G.; Carrico, A. R.

    2012-12-01

    Stress on freshwater resources is a significant risk associated with climatic change. The risk is even greater given the expected changes in overall resource use as the developing world develops, as the world's population continues to grow, and as land use changes dramatically. Effective water management has implications for food security, health, and political stability worldwide. This is particularly true in developing regions heavily dependent on agriculture, and where agriculture depends on irrigation. Adaptation to water stress requires both managing water allocation among competing users and ensuring that each user is efficient in his or her use of a limited allotment: the problem is a quintessential common-pool resource (CPR) dilemma. In the future even more so than in the past, adaptation will be essential as the world evolves. The problem that we identify—determining paths by which farmers can adapt effectively to increasingly scarce freshwater resources—is one of great scientific and societal importance. The issue lies at the intersection of water-cycle processes and social-psychological processes that influence and are influenced by water availability and use. This intersection harbors intriguing unresolved scientific questions; advances in natural and social sciences will stem from attacks on the overall problem. The issue is societally compelling because the ability of the world to supply adequate food for a population expected to grow to over 9 billion by 2050 may well be determined by how farmers, consumers, and government institutions adapt to changing conditions of water availability. Major strides have been made in recent decades in understanding why Hardin's envisioned "tragedy of the commons" is avoided under certain circumstances, in some cases through self-organization rather than government intervention originally considered a necessity. Furthermore, we now know that the impacts of decisions about allocation and use of water can be

  20. Freshwater Mussels as Biological Sensors and Cyclers of Aquatic Nitrogen Constituents: An Experimental Investigation

    Science.gov (United States)

    Kruger, A.; Just, C. L.; Mudumbai, R.; Dasgupta, S.; Newton, T. J.; Durst, J.; Boddicker, M. D.; Diken, M. B.; Bril, J.; Baidoo-Williams, H. E.

    2011-12-01

    One of the most extensive manifestations of anthropogenic mismanagement of nitrogen is eutrophication of the Gulf of Mexico. Leaching and runoff transport nitrate compounds-excess agricultural fertilizer and animal waste-via the Mississippi River to the Gulf of Mexico. Phytoplankton then multiplies exponentially, and consumes most of the dissolved oxygen. This hypoxia kills fish and other organisms, leading to so-called dead zones in the Gulf that can cover 6,000-7,000 square miles. Dead zone mitigation plans call for coupling management actions with enhanced monitoring, modeling, and research on nitrogen delivery to, as well as processing within, the Mississippi River. Our vision is to create a biosensor network of native freshwater mussels in a major river to monitor, comprehend, and ultimately model key components of the nitrogen cycle. Native freshwater mussels are a guild of long-lived, suspension feeding bivalves that perform important ecological functions in aquatic systems. Mussels can influence nutrient cycling by transferring nutrients from the water column to the riverbed. A major problem for environmental scientists is that relatively little is known about the diurnal behaviors of freshwater mussels or the impacts these behaviors may have on the aquatic nitrogen cycle. Our multidisciplinary team is performing a series of laboratory experiments exploring the feasibility of using freshwater mussels as sensors of and capacitors for nitrates. For sensing, we place Hall-effect sensors on mussels to monitor the rhythmic opening and closing of their valves (gape). One shortcoming of previous work is that mussels were monitored in artificial conditions: glued fast in laboratory flumes, or tethered in constrained settings. To overcome this shortcoming, our team has built a mussel microhabitat with a constant river water feed stock, solar simulator, and a variety of water chemistry sensor. A main thrust of our work is to develop the technology to monitor mussel

  1. Assessing and managing freshwater ecosystems vulnerable to global change

    Science.gov (United States)

    Angeler, David G.; Allen, Craig R.; Birge, Hannah E.; Drakare, Stina; McKie, Brendan G.; Johnson, Richard K.

    2014-01-01

    Freshwater ecosystems are important for global biodiversity and provide essential ecosystem services. There is consensus in the scientific literature that freshwater ecosystems are vulnerable to the impacts of environmental change, which may trigger irreversible regime shifts upon which biodiversity and ecosystem services may be lost. There are profound uncertainties regarding the management and assessment of the vulnerability of freshwater ecosystems to environmental change. Quantitative approaches are needed to reduce this uncertainty. We describe available statistical and modeling approaches along with case studies that demonstrate how resilience theory can be applied to aid decision-making in natural resources management. We highlight especially how long-term monitoring efforts combined with ecological theory can provide a novel nexus between ecological impact assessment and management, and the quantification of systemic vulnerability and thus the resilience of ecosystems to environmental change.

  2. Successful enrichment of the ubiquitous freshwater acI Actinobacteria.

    Science.gov (United States)

    Garcia, Sarahi L; McMahon, Katherine D; Grossart, Hans-Peter; Warnecke, Falk

    2014-02-01

    Actinobacteria of the acI lineage are often the numerically dominant bacterial phylum in surface freshwaters, where they can account for > 50% of total bacteria. Despite their abundance, there are no described isolates. In an effort to obtain enrichment of these ubiquitous freshwater Actinobacteria, diluted freshwater samples from Lake Grosse Fuchskuhle, Germany, were incubated in 96-well culture plates. With this method, a successful enrichment containing high abundances of a member of the lineage acI was established. Phylogenetic classification showed that the acI Actinobacteria of the enrichment belonged to the acI-B2 tribe, which seems to prefer acidic lakes. This enrichment grows to low cell densities and thus the oligotrophic nature of acI-B2 was confirmed. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

  3. Sulfidization of Organic Freshwater Flocs from a Minerotrophic Peatland: Speciation Changes of Iron, Sulfur, and Arsenic.

    Science.gov (United States)

    ThomasArrigo, Laurel K; Mikutta, Christian; Lohmayer, Regina; Planer-Friedrich, Britta; Kretzschmar, Ruben

    2016-04-05

    Iron-rich organic flocs are frequently observed in surface waters of wetlands and show a high affinity for trace metal(loid)s. Under low-flow stream conditions, flocs may settle, become buried, and eventually be subjected to reducing conditions facilitating trace metal(loid) release. In this study, we reacted freshwater flocs (704-1280 mg As/kg) from a minerotrophic peatland (Gola di Lago, Switzerland) with sulfide (5.2 mM, S(-II)spike/Fe = 0.75-1.62 mol/mol) at neutral pH and studied the speciation changes of Fe, S, and As at 25 ± 1 °C over 1 week through a combination of synchrotron X-ray techniques and wet-chemical analyses. Sulfidization of floc ferrihydrite and nanocrystalline lepidocrocite caused the rapid formation of mackinawite (52-81% of Fesolid at day 7) as well as solid-phase associated S(0) and polysulfides. Ferrihydrite was preferentially reduced over lepidocrocite, although neoformation of lepidocrocite from ferrihydrite could not be excluded. Sulfide-reacted flocs contained primarily arsenate (47-72%) which preferentially adsorbed to Fe(III)-(oxyhydr)oxides, despite abundant mackinawite precipitation. At higher S(-II)spike/Fe molar ratios (≥1.0), the formation of an orpiment-like phase accounted for up to 35% of solid-phase As. Despite Fe and As sulfide precipitation and the presence of residual Fe(III)-(oxyhydr)oxides, mobilization of As was recorded in all samples (Asaq = 0.45-7.0 μM at 7 days). Aqueous As speciation analyses documented the formation of thioarsenates contributing up to 33% of Asaq. Our findings show that freshwater flocs from the Gola di Lago peatland may become a source of As under sulfate-reducing conditions and emphasize the pivotal role Fe-rich organic freshwater flocs play in trace metal(loid) cycling in S-rich wetlands characterized by oscillating redox conditions.

  4. Crystalline phase-dependent eco-toxicity of titania nanoparticles to freshwater biofilms

    International Nuclear Information System (INIS)

    Li, Kun; Qian, Jin; Wang, Peifang; Wang, Chao; Liu, Jingjing; Tian, Xin; Lu, Bianhe; Shen, Mengmeng

    2017-01-01

    The potential toxic impacts of different crystal phases of titania nanoparticles (TNPs) on freshwater biofilms, especially under ultraviolet C irradiation (UVC), are unknown. Here, adverse impacts of three phases (anatase, rutile, and P25, 50 mg L −1 respectively) with UVC irradiation (An-UV, Ru-UV, and P25-UV) on freshwater biofilms were conducted. Characterization experiments revealed that rutile TNPs had a higher water environment stability than anatase and P25 TNPs, possessing a stronger photocatalytic activity under UVC irradiation. Phase-dependent inhibition of cell viability and significant decreases of four- and five-fold in algal biomass at 12 h of exposure were observed compared with unexposed biofilms. Moreover, phase-dependent oxidative stress resulted in remarkably significant reductions (P < 0.01) of the photosynthetic yields of the biofilms, to 40.32% (P25-UV), 48.39% (An-UV), and 46.77% (Ru-UV) of the plateau value obtained in the unexposed biofilms. A shift in community composition that manifested as a strong reduction in diatoms, indicating cyanobacteria and green algae were more tolerant than diatoms when exposed to TNPs. In terms of the toxic mechanisms, rutile TNPs resulted in apoptosis by inducing excessive intracellular reactive oxygen species (ROS) production, whereas P25 and anatase TNPs tended to catalyze enormous acellular ROS lead to cell necrosis under UVC irradiation. - Highlights: • Phase-dependent response of freshwater biofilms to three TNPs was studied with UVC. • Rutile is more stable yet P25 and anatase own better photooxidation level in water. • Decrease in Chl-a and φM and a shift in algae bio-cenosis were phase-dependent. • Phase-dependent stress induced cellular or acellular ROS to reduce cells viability. • Rutile tend to induced apoptosis yet P25 and anatase prefer to cause cell necrosis. - Crystalline-dependent eco-toxicity of TNPs to freshwater biofilms show allotrope of nanoparticles must be considered

  5. An in vitro biotic ligand model (BLM) for silver binding to cultured gill epithelia of freshwater rainbow trout (Oncorhynchus mykiss)

    International Nuclear Information System (INIS)

    Zhou Bingsheng; Nichols, Joel; Playle, Richard C.; Wood, Chris M.

    2005-01-01

    'Reconstructed' gill epithelia on filter supports were grown in primary culture from dispersed gill cells of freshwater rainbow trout (Oncorhynchus mykiss). This preparation contains both pavement cells and chloride cells, and after 7-9 days in culture, permits exposure of the apical surface to true freshwater while maintaining blood-like culture media on the basolateral surface, and exhibits a stable transepithelial resistance (TER) and transepithelial potential (TEP) under these conditions. These epithelia were used to develop a possible in vitro version of the biotic ligand model (BLM) for silver; the in vivo BLM uses short-term gill binding of the metal to predict acute silver toxicity as a function of freshwater chemistry. Radio-labeled silver ( 110m Ag as AgNO 3 ) was placed on the apical side (freshwater), and the appearance of 110m Ag in the epithelia (binding) and in the basolateral media (flux) over 3 h were monitored. Silver binding (greater than the approximate range 0-100 μg l -1 ) and silver flux were concentration-dependent with a 50% saturation point (apparent K d ) value of about 10 μg l -1 or 10 -7 M, very close to the 96-h LC50 in vivo in the same water chemistry. There were no adverse effects of silver on TER, TEP, or Na + , K + -ATPase activity, though the latter declined over longer exposures, as in vivo. Silver flux over 3 h was small ( + and dissolved organic carbon (humic acid) concentrations, increased by elevations in freshwater Cl - and reductions in pH, and insensitive to elevations in Ca 2+ . With the exception of the pH response, these effects were qualitatively and quantitatively similar to in vivo BLM responses. The results suggest that an in vitro BLM approach may provide a simple and cost-effective way for evaluating the protective effects of site-specific waters

  6. Designing Freshwater Resilience for the Mexico City Metropolitan Area

    Science.gov (United States)

    Freeman, S.; Wi, S.; Brown, C.

    2017-12-01

    There are few places in the world where the water management challenges associated with global urbanization are as fully visible as in the Greater Mexico City Metropolitan Area (MCMA). MCMA has a population of 22 million of which only 82% have daily water provision and this figure is projected by local agencies to decrease drastically in the next decade due to population growth, infrastructure degradation and climate change. The city is served by a massive water delivery system, consisting of complex network of infrastructure in the surrounding basins that provides about 40% of the supply for MCMA and is characterized by increasing land use change and competition for water. The remaining 60% of MCMA's water is sourced internally from already depleted groundwater resources whose exploitation also results in significant subsidence throughout the city, further damaging already degraded infrastructure. Consequently, there is interest and need for investments that improve the performance of the freshwater delivery system, including local resources and connected basins, in the face of change and shocks that can be only partially anticipated. The quest for such resilience is a common theme in urban infrastructure design yet practical approaches for achieving it remain nascent. In this study, we use MCMA and the Cutzamala Water supply system to demonstrate a quantitative framework to evaluate investment strategies which seek resilience for the water supply system of MCMA. Multiobjective optimization and decisions under deep uncertainty approaches are used to evaluate the best performing investment portfolios across different resilience performance metrics which encompass social equity, environmental and economic objectives. This analysis shows dynamic system responses that result from different investment portfolios, elucidating difficult planning and management decisions around tradeoffs between allocations as well as performance metrics (e.g short period of total failure

  7. Brackish groundwater and its potential to augment freshwater supplies

    Science.gov (United States)

    Stanton, Jennifer S.; Dennehy, Kevin F.

    2017-07-18

    Secure, reliable, and sustainable water resources are fundamental to the Nation’s food production, energy independence, and ecological and human health and well-being. Indications are that at any given time, water resources are under stress in selected parts of the country. The large-scale development of groundwater resources has caused declines in the amount of groundwater in storage and declines in discharges to surface water bodies (Reilly and others, 2008). Water supply in some regions, particularly in arid and semiarid regions, is not adequate to meet demand, and severe drought intensifies the stresses affecting water resources (National Drought Mitigation Center, the U.S. Department of Agriculture, and the National Oceanic and Atmospheric Association, 2015). If these drought conditions continue, water shortages could adversely affect the human condition and threaten environmental flows necessary to maintain ecosystem health.In support of the national census of water resources, the U.S. Geological Survey (USGS) completed the national brackish groundwater assessment to provide updated information about brackish groundwater as a potential resource to augment or replace freshwater supplies (Stanton and others, 2017). Study objectives were to consolidate available data into a comprehensive database of brackish groundwater resources in the United States and to produce a summary report highlighting the distribution, physical and chemical characteristics, and use of brackish groundwater resources. This assessment was authorized by section 9507 of the Omnibus Public Land Management Act of 2009 (42 U.S.C. 10367), passed by Congress in March 2009. Before this assessment, the last national brackish groundwater compilation was completed in the mid-1960s (Feth, 1965). Since that time, substantially more hydrologic and geochemical data have been collected and now can be used to improve the understanding of the Nation’s brackish groundwater resources.

  8. The maintenance of hybrids by parasitism in a freshwater snail.

    Science.gov (United States)

    Guttel, Yonathan; Ben-Ami, Frida

    2014-11-01

    Hybrids have often been labelled evolutionary dead-ends due to their lower fertility and viability. However, there is growing awareness that hybridisation between different species may play a constructive role in animal evolution as a means to create variability. Thus, hybridisation and introgression may contribute to adaptive evolution, for example with regards to natural antagonists (parasites, predators, competitors) and adaptation to local environmental conditions. Here we investigated whether parasite intensity contributes to the continuous recreation of hybrids in 74 natural populations of Melanopsis, a complex of freshwater snails with three species. We also examined, under laboratory conditions, whether hybrids and their parental taxa differ in their tolerance of low and high temperatures and salinity levels. Infections were consistently less prevalent in males than in females, and lower in snails from deeper habitats. Infection prevalence in hybrids was significantly lower than in the parental taxa. Low hybrid infection rates could not be explained by sediment type, snail density or geographic distribution of the sampling sites. Interestingly, infected hybrid snails did not show signs of parasite-induced gigantism, whereas all parental taxa did. We found that hybrids mostly coped with extreme temperatures and salinity levels as well as their parental taxa did. Taken together, our results suggest that Melanopsis hybrids perform better in the presence of parasites and environmental stress. This may explain the widespread and long-term occurrence of Melanopsis hybrids as evidenced by paleontological and biogeographic data. Hybridisation may be an adaptive host strategy, reducing infection rates and resisting gigantism. Copyright © 2014 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

  9. Effects of three months treatment with sertraline on intraocular pressure and cup-to-disc ratio in patients with anxiety disorders/mixed anxiety and depressive disorder/major depressive disorder and without underlying eye disease

    Directory of Open Access Journals (Sweden)

    Narjes Hendouei

    2017-09-01

    Full Text Available Exposure to selective serotonin reuptake inhibitors causes pupillary dilator muscle stimulation, active mydriasis, rapid rise in the level of the intraocular pressure (IOP, damage to the optic nerve at the back of the eye, and ultimately leads to acute angle closure glaucoma. The aim of this study was to assess the effects of sertraline on the levels of IOP and cup-to-disc ratio (CDR in patients with anxiety disorders or mixed anxiety and depressive disorder or major depressive under daily treatment with sertraline and without underlying eye disease for three months. In this study,30 eligible patients in the sertraline group and 30 healthy volunteers in the control group include the study and were referred to an ophthalmologist. Ophthalmologic examinations were assessed at the baseline and on the first and third months of the study. The average daily dose of sertraline was 95±2.5 mg.During the study, the IOP changes in the sertraline and control groups were 0.26±0.43 and 0.00±0.00 mmHg (p<0.001, p=NS respectively and the CDR changes in sertraline and control groups were 0.03±0.05 and -0.01±0.05 (p=0.002, p=0.03 respectively. There was a significant difference in the IOP and CDR increasement between two groups ([F (1.7, 104.2 = 3.7, p = 0.03] and [F (2, 116 = 8.3, p < 0.001] respectively. In the present study, although changes in the IOP and CDR  levels in the sertraline group were significant and was equal the daily change in the persons without glaucoma or patients with normal-tension glaucoma, but the slight and continuous increase in the IOP level associated with changes in pupil size and CDR, especially in patients at risk of glaucoma in the long term, can cause a disruption in hydrodynamic homeostasis. More studies with longer duration and different dosage of sertraline need to confirm our results.     

  10. 2H and 18O Freshwater Isoscapes of Scotland

    Science.gov (United States)

    Meier-Augenstein, Wolfram; Hoogewerff, Jurian; Kemp, Helen; Frew, Danny

    2013-04-01

    Scotland's freshwater lochs and reservoirs provide a vital resource for sustaining biodiversity, agriculture, food production as well as for human consumption. Regular monitoring of freshwaters by the Scottish Environment Protection Agency (SEPA) fulfils legislative requirements with regards to water quality but new scientific methods involving stable isotope analysis present an opportunity combining these mandatory monitoring schemes with fundamental research to inform and deliver on current and nascent government policies [1] through gaining a greater understanding of Scottish waters and their importance in the context of climate change, environmental sustainability and food security. For example, 2H and 18O isoscapes of Scottish freshwater could be used to underpin research and its applications in: • Climate change - Using longitudinal changes in the characteristic isotope composition of freshwater lochs and reservoirs as proxy, isoscapes will provide a means to assess if and how changes in temperature and weather patterns might impact on precipitation patterns and amount. • Scottish branding - Location specific stable isotope signatures of Scottish freshwater have the potential to be used as a tool for provenancing and thus protecting premium Scottish produce such as Scottish beef, Scottish soft fruit and Scottish Whisky. During 2011 and 2012, with the support of SEPA more than 110 samples from freshwater lochs and reservoirs were collected from 127 different locations across Scotland including the Highlands and Islands. Here we present the results of this sampling and analysis exercise isotope analyses in form of 2H and 18O isoscapes with an unprecedented grid resolution of 26.5 × 26.5 km (or 16.4 × 16.4 miles). [1] Adaptation Framework - Adapting Our Ways: Managing Scotland's Climate Risk (2009): Scotland's Biodiversity: It's in Your Hands - A strategy for the conservation and enhancement of biodiversity in Scotland (2005); Recipe For Success - Scotland

  11. Patterns of Freshwater Species Richness, Endemism, and Vulnerability in California.

    Directory of Open Access Journals (Sweden)

    Jeanette K Howard

    Full Text Available The ranges and abundances of species that depend on freshwater habitats are declining worldwide. Efforts to counteract those trends are often hampered by a lack of information about species distribution and conservation status and are often strongly biased toward a few well-studied groups. We identified the 3,906 vascular plants, macroinvertebrates, and vertebrates native to California, USA, that depend on fresh water for at least one stage of their life history. We evaluated the conservation status for these taxa using existing government and non-governmental organization assessments (e.g., endangered species act, NatureServe, created a spatial database of locality observations or distribution information from ~400 data sources, and mapped patterns of richness, endemism, and vulnerability. Although nearly half of all taxa with conservation status (n = 1,939 are vulnerable to extinction, only 114 (6% of those vulnerable taxa have a legal mandate for protection in the form of formal inclusion on a state or federal endangered species list. Endemic taxa are at greater risk than non-endemics, with 90% of the 927 endemic taxa vulnerable to extinction. Records with spatial data were available for a total of 2,276 species (61%. The patterns of species richness differ depending on the taxonomic group analyzed, but are similar across taxonomic level. No particular taxonomic group represents an umbrella for all species, but hotspots of high richness for listed species cover 40% of the hotspots for all other species and 58% of the hotspots for vulnerable freshwater species. By mapping freshwater species hotspots we show locations that represent the top priority for conservation action in the state. This study identifies opportunities to fill gaps in the evaluation of conservation status for freshwater taxa in California, to address the lack of occurrence information for nearly 40% of freshwater taxa and nearly 40% of watersheds in the state, and to

  12. Major results on the development of high density U-Mo fuel and pin-type fuel elements executed under the Russian RERTR program and in cooperation with ANL (USA)

    International Nuclear Information System (INIS)

    Vatulin, A.; Morozov, A.; Stetsky, Y.; Suprun, V.; Dobrikova, I.; Trifonov, Y.; Mishunin, V.; Sorokin, V.

    2003-01-01

    VNIINM is active participant of 'Russian program on Reduced Enrichment for Research and Test Reactors'. Institute Works in two main directions: 1) development of new high-density fuels (HDF) and 2) development of new design of fuel elements with LEU. The development of the new type fuel element is carried out both for existing reactors, and for developing new advanced reactors. The 'TVEL' concern is coordinator of works of this program. The majority enterprises of branch (NIIAR, PIYaF, RRC KI, NZChK) take part in this work. Since 2000 these works are being conducted in cooperation with Argonne National Laboratory (USA) within the RERTR program under VNIINM with ANL contract. At the present, a large set of pre-pile investigations has been completed. All necessary fabrication procedures have been developed for utilization of U-Mo dispersion fuel in Russian-designed research reactors. For irradiation tests the pin-type mini-fuel elements with HDF dispersion fuel with LEU and the uranium density equaled to 4,0 and 6,0 g/cm 3 (up to 40 vol.%) have been manufactured. Their irradiation began in August 2003 in the MIR reactor (NIIAR, Dimitrovgrad). A large set of works for preparation of lifetime tests (WWR-M reactor in Gatchina) of two full-scale fuel assemblies with new pin-type fuel elements on basis LEU UO 2 -Al and UMo-Al fuels has been completed. The in-pile tests of fuel assemblies began in September 2003. The summary of important results of performed works and their near-term future are presented in paper. (author)

  13. Biota: Providing often-overlooked connections among freshwater systems

    Science.gov (United States)

    Mushet, David M.; Christensen, Jay R.; Bennett, Michah; Alexander, Laurie C.

    2017-01-01

    When we think about connections in and among aquatic systems, we typically envision clear headwater streams flowing into downstream rivers, river floodwaters spilling out onto adjacent floodplains, or groundwater connecting wetlands to lakes and streams. However, there is another layer of connectivity moving materials among freshwater systems, one with connections that are not always tied to downgradient flows of surface waters and groundwater. These movements are those of organisms, key components of virtually every freshwater system on the planet. In their movements across the landscape, biota connect aquatic systems in often-overlooked ways.

  14. Investigating salt and naphthenic acids interactions in the toxicity of oil sands process water to freshwater invertebrates

    International Nuclear Information System (INIS)

    Turcotte, D.; Kautzman, M.; Wojnarowicz, P.; Cutter, J.; Bird, E.; Liber, K.

    2010-01-01

    The hot water extraction process used to produce bitumens from oil sands produces a large volume of oil sands process water (OSPW) that contain elevated concentrations of naphthenic acids (NA) and salts. Many oil sands reclamation projects are proposing the use of OSPW as part of reconstructed wetlands projects. This study investigated the toxicity of OSPW to freshwater invertebrates. The toxic interactions between NA and salinity on freshwater invertebrates were assessed. Bioassays with laboratory-cultured Ceriodaphnia dubia were conducted to determine the toxicity of OSPW from selected water bodies. The study showed that while the concentrations of NAs and salinity were elevated in OSPW waters that caused toxic responses, the concentrations of salinity ions varied greatly among the OSPW samples. Results of the study suggested that ion composition may be a factor in toxicity. Interactions between NAs and salinity were then assessed by performing bioassays with mixtures representing major ion combinations in OSPW.

  15. Increasing pressure on freshwater resources due to terrestrial feed ingredients for aquaculture production.

    Science.gov (United States)

    Pahlow, M; van Oel, P R; Mekonnen, M M; Hoekstra, A Y

    2015-12-01

    As aquaculture becomes more important for feeding the growing world population, so too do the required natural resources needed to produce aquaculture feed. While there is potential to replace fish meal and fish oil with terrestrial feed ingredients, it is important to understand both the positive and negative implications of such a development. The use of feed with a large proportion of terrestrial feed may reduce the pressure on fisheries to provide feed for fish, but at the same time it may significantly increase the pressure on freshwater resources, due to water consumption and pollution in crop production for aquafeed. Here the green, blue and gray water footprint of cultured fish and crustaceans related to the production of commercial feed for the year 2008 has been determined for the major farmed species, representing 88% of total fed production. The green, blue and gray production-weighted average feed water footprints of fish and crustaceans fed commercial aquafeed are estimated at 1629 m3/t, 179 m3/t and 166 m3/t, respectively. The estimated global total water footprint of commercial aquafeed was 31-35 km3 in 2008. The top five contributors to the total water footprint of commercial feed are Nile tilapia, Grass carp, Whiteleg shrimp, Common carp and Atlantic salmon, which together have a water footprint of 18.2 km3. An analysis of alternative diets revealed that the replacement of fish meal and fish oil with terrestrial feed ingredients may further increase pressure on freshwater resources. At the same time economic consumptive water productivity may be reduced, especially for carnivorous species. The results of the present study show that, for the aquaculture sector to grow sustainably, freshwater consumption and pollution due to aquafeed need to be taken into account. Copyright © 2015. Published by Elsevier B.V.

  16. Development of a strontium chronic effects benchmark for aquatic life in freshwater.

    Science.gov (United States)

    McPherson, Cathy A; Lawrence, Gary S; Elphick, James R; Chapman, Peter M

    2014-11-01

    There are no national water-quality guidelines for strontium for the protection of freshwater aquatic life in North America or elsewhere. Available data on the acute and chronic toxicity of strontium to freshwater aquatic life were compiled and reviewed. Acute toxicity was reported to occur at concentrations ranging from 75 mg/L to 15 000 mg/L. The majority of chronic effects occurred at concentrations above 11 mg/L; however, calculation of a representative benchmark was confounded by results from 4 studies indicating that chronic effects occurred at lower concentrations than all other studies, in 2 cases below background concentrations reported for US and European streams. Two of these studies, including 1 reporting effects below background concentrations, were repeated and found not to be reproducible; chronic effects occurred at considerably higher strontium concentrations than in the original studies. Studies with narrow-mouthed toad and goldfish were not repeated; both studies reported chronic effects below background concentrations, and both studies had been conducted by the authors of 1 of the 2 studies that were repeated and shown to be nonreproducible. Studies by these authors (3 of the 4 confounding studies), conducted over 30 yr ago, lacked detail in reporting of methods and results. It is thus likely that repeating the toad and goldfish studies would also have resulted in a higher strontium effects concentration. A strontium chronic effects benchmark of 10.7 mg/L that incorporates the results of additional testing summarized in the present study is proposed for freshwater environments. © 2014 SETAC.

  17. Hydrogeology and management of freshwater lenses on atoll islands: Review of current knowledge and research needs

    Science.gov (United States)

    Werner, Adrian D.; Sharp, Hannah K.; Galvis, Sandra C.; Post, Vincent E. A.; Sinclair, Peter

    2017-08-01

    On atoll islands, fresh groundwater occurs as a buoyant lens-shaped body surrounded by saltwater derived from the sea, forming the main freshwater source for many island communities. A review of the state of knowledge of atoll island groundwater is overdue given their susceptibility to adverse impacts, and the task to address water access and sanitation issues within the United Nations' Sustainable Development Goals framework before the year 2030. In this article, we review available literature to summarise the key processes, investigation techniques and management approaches of atoll island groundwater systems. Over fifty years of investigation has led to important advancements in the understanding of atoll hydrogeology, but a paucity of hydrogeological data persists on all but a small number of atoll islands. We find that the combined effects of buoyancy forces, complex geology, tides, episodic ocean events, strong climatic variability and human impacts create highly dynamic fresh groundwater lenses. Methods used to quantify freshwater availability range from simple empirical relationships to three-dimensional density-dependent models. Generic atoll island numerical models have proven popular in trying to unravel the individual factors controlling fresh groundwater lens behaviour. Major challenges face the inhabitants and custodians of atoll island aquifers, with rising anthropogenic stresses compounded by the threats of climate variability and change, sea-level rise, and some atolls already extracting freshwater at or above sustainability limits. We find that the study of atoll groundwater systems remains a critical area for further research effort to address persistent knowledge gaps, which lead to high uncertainties in water security issues for both island residents and surrounding environs.

  18. Changes in freshwater mussel communities linked to legacy pollution in the Lower Delaware River

    Science.gov (United States)

    Blakeslee, Carrie J.; Silldorff, Erik L.; Galbraith, Heather S.

    2018-01-01

    Freshwater mussels are among the most-imperiled organisms worldwide, although they provide a variety of important functions in the streams and rivers they inhabit. Among Atlantic-slope rivers, the Delaware River is known for its freshwater mussel diversity and biomass; however, limited data are available on the freshwater mussel fauna in the lower, non-tidal portion of the river. This section of the Delaware River has experienced decades of water-quality degradation from both industrial and municipal sources, primarily as a function of one of its major tributaries, the Lehigh River. We completed semi-quantitative snorkel surveys in 53.5 of the 121 km of the river to document mussel community composition and the continued impacts from pollution (particularly inputs from the Lehigh River) on mussel fauna. We detected changes in mussel catch per unit effort (CPUE) below the confluence of the Lehigh River, with significant declines in the dominant species Elliptio complanata (Eastern Elliptio) as we moved downstream from its confluence—CPUE dropped from 179 to 21 mussels/h. Patterns in mussel distribution around the Lehigh confluence matched chemical signatures of Lehigh water input. Specifically, Eastern Elliptio CPUE declined more quickly moving downstream on the Pennsylvania bank, where Lehigh River water input was more concentrated compared to the New Jersey bank. A definitive causal link remains to be established between the Lehigh River and the dramatic shifts in mussel community composition, warranting continued investigation as it relates to mussel conservation and restoration in the basin.

  19. Reducing the impact of irrigated crops on freshwater availability: the case of Brazilian yellow melons

    NARCIS (Netherlands)

    Brito de Figueirêdo, M.C.; Boer, de I.J.M.; Kroeze, C.; Silva Barros, da V.; Sousa, de J.A.; Souza de Aragão, F.A.; Sonsol Gondim, R.; Potting, J.

    2014-01-01

    Purpose This study quantifies freshwater consumption throughout the life cycle of Brazilian exported yellow melons and assesses the resulting impact on freshwater availability. Results are used to identify improvement options. Moreover, the study explores the further impact of variations in

  20. Biogenic silica in tidal freshwater marsh sediments and vegetation (Schelde estuary, Belgium)

    NARCIS (Netherlands)

    Struyf, E.; van Damme, S.; Gribsholt, B.; Middelburg, J.J.; Meire, P.

    2005-01-01

    To date, estuarine ecosystem research has mostly neglected silica cycling in freshwater intertidal marshes. However, tidal marshes can store large amounts of biogenic silica (BSi) in vegetation and sediment. BSi content of the typical freshwater marsh plants Phragmites australis, Impatiens

  1. How to prevent legionella infestation. Pt. 1. Central freshwater heating systems; Wie man Legionellen vermeiden. T. 1. Zentrale Trinkwassererwaermungsanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Kremer, Robert [DVGW-Fachausschuss Trinkwasserhygiene in Gebaeuden, Leverkusen (Germany)

    2009-01-15

    The contribution focuses on hygienically safe freshwater heating. Legionella prophylaxis is discussed, as are new findings concerning practical implementation of new requirements on modern freshwater supply systems. (orig.)

  2. Diversity and distribution of parasites from potentially cultured freshwater fish in Nakhon Si Thammarat

    Directory of Open Access Journals (Sweden)

    Supamattaya, K.

    2005-02-01

    Full Text Available Twenty-one species from 16 genera of potentially cultured freshwater fish were examined for external and internal parasites. Ten individuals of each fish species were sampled from various places in Nakhon Si Thammarat. Eight groups, 72 species were identified and the majority was external (52 spp.. The parasites found were ciliated protozoan (2 spp., myxozoan (2 spp., monogenean (44 spp., digenean (7 spp., cestode (6 spp., nematode (6 spp., acanthocephalan (2 spp. and crustacean (3 spp.. Monogenean was regarded as a major group of parasites with 44 species. Dactylogyrus (Monogenea had the highest number of species (12 spp., whereas Trichodina pediculus (Ciliophora was the most widely distributed species observed from at least 7 fish species (7 families. Most of the parasites (72 % found in this study were specific to their host species.

  3. Bioenvironmental and radiological-safety feasibility studies, Atlantic-Pacific Interoceanic Canal. Phase 2, Freshwater ecology: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Templeton, W.L.; Dean, J.M.; Watson, D.G.; Rancitelli, L.A. [Pacific Northwest Lab., Richland, WA (United States); Loftin, H.G. [Consultant, Florida State Univ. (United States)

    1968-06-28

    The purpose of this program is to conduct studies in the freshwater environment to acquire data needed to evaluate and predict the potential radiation hazards to human populations in the defined regions of proposed nuclear excavations in the Republics of Panama and Colombia. The results of the field surveys conducted in Phase II are presented in this report. Specifically, the data describes the elemental composition of the major components of the ecosystem, and reports the calculated stable element concentration factors for the major food organisms. This data provides baseline values from which predictions can be made of the potential maximum radionuclide intake by populations using this resource.

  4. Do Biology Majors Really Differ from Non-STEM Majors?

    Science.gov (United States)

    Cotner, Sehoya; Thompson, Seth; Wright, Robin

    2017-01-01

    Recent calls to action urge sweeping reform in science education, advocating for improved learning for all students-including those majoring in fields beyond the sciences. However, little work has been done to characterize the differences-if any exist-between students planning a career in science and those studying other disciplines. We describe an attempt to clarify, in broad terms, how non-STEM (science, technology, engineering, and mathematics) majors differ from life sciences majors, and how they are similar. Using survey responses and institutional data, we find that non-STEM majors are not unilaterally science averse; non-STEM majors are more likely than biology majors to hold misconceptions about the nature of science, yet they are not completely ignorant of how science works; non-STEM majors are less likely than biology majors to see science as personally relevant; and non-STEM majors populations are likely to be more diverse-with respect to incoming knowledge, perceptions, backgrounds, and skills-than a biology majors population. We encourage science educators to consider these characteristics when designing curricula for future scientists or simply for a well-informed citizenry. © 2017 S. Cotner et al. CBE—Life Sciences Education © 2017 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  5. Harmful Freshwater Algal Blooms, With an Emphasis on Cyanobacteria

    Directory of Open Access Journals (Sweden)

    Hans W. Paerl

    2001-01-01

    Full Text Available Suspended algae, or phytoplankton, are the prime source of organic matter supporting food webs in freshwater ecosystems. Phytoplankton productivity is reliant on adequate nutrient supplies; however, increasing rates of nutrient supply, much of it manmade, fuels accelerating primary production or eutrophication. An obvious and problematic symptom of eutrophication is rapid growth and accumulations of phytoplankton, leading to discoloration of affected waters. These events are termed blooms. Blooms are a prime agent of water quality deterioration, including foul odors and tastes, deoxygenation of bottom waters (hypoxia and anoxia, toxicity, fish kills, and food web alterations. Toxins produced by blooms can adversely affect animal (including human health in waters used for recreational and drinking purposes. Numerous freshwater genera within the diverse phyla comprising the phytoplankton are capable of forming blooms; however, the blue-green algae (or cyanobacteria are the most notorious bloom formers. This is especially true for harmful toxic, surface-dwelling, scum-forming genera (e.g., Anabaena, Aphanizomenon, Nodularia, Microcystis and some subsurface bloom-formers (Cylindrospermopsis, Oscillatoria that are adept at exploiting nutrient-enriched conditions. They thrive in highly productive waters by being able to rapidly migrate between radiance-rich surface waters and nutrient-rich bottom waters. Furthermore, many harmful species are tolerant of extreme environmental conditions, including very high light levels, high temperatures, various degrees of desiccation, and periodic nutrient deprivation. Some of the most noxious cyanobacterial bloom genera (e.g., Anabaena, Aphanizomenon, Cylindrospermopsis, Nodularia are capable of fixing atmospheric nitrogen (N2, enabling them to periodically dominate under nitrogen-limited conditions. Cyanobacteria produce a range of organic compounds, including those that are toxic to higher-ranked consumers, from

  6. Methane emissions from a freshwater marsh in response to experimentally simulated global warming and nitrogen enrichment

    DEFF Research Database (Denmark)

    Flury, Sabine; McGinnis, Daniel Frank; Gessner, Mark O.

    2010-01-01

    We determined methane (CH4) emissions in a field enclosure experiment in a littoral freshwater marsh under the influence of experimentally simulated warming and enhanced nitrogen deposition. Methane emissions by ebullition from the marsh composed of Phragmites australis were measured with funnel ...... to the atmosphere, even when they occupy only relatively small littoral areas. More detailed investigations are clearly needed to assess whether global warming and nitrogen deposition can have climate feedbacks by altering methane fluxes from these wetlands.  ......We determined methane (CH4) emissions in a field enclosure experiment in a littoral freshwater marsh under the influence of experimentally simulated warming and enhanced nitrogen deposition. Methane emissions by ebullition from the marsh composed of Phragmites australis were measured with funnel...... traps deployed in a series of enclosures for two 3 week periods. Diffusive fluxes were estimated on the basis of measured CH4 concentrations and application of Fick's law. Neither diffusive nor ebullitive fluxes of methane were significantly affected by warming or nitrate enrichment, possibly because...

  7. Responses of plant nutrient resorption to phosphorus addition in freshwater marsh of Northeast China

    Science.gov (United States)

    Mao, Rong; Zeng, De-Hui; Zhang, Xin-Hou; Song, Chang-Chun

    2015-01-01

    Anthropogenic activities have increased phosphorus (P) inputs to most aquatic and terrestrial ecosystems. However, the relationship between plant nutrient resorption and P availability is still unclear, and much less is known about the underlying mechanisms. Here, we used a multi-level P addition experiment (0, 1.2, 4.8, and 9.6 g P m−2 year−1) to assess the effect of P enrichment on nutrient resorption at plant organ, species, and community levels in a freshwater marsh of Northeast China. The response of nutrient resorption to P addition generally did not vary with addition rates. Moreover, nutrient resorption exhibited similar responses to P addition across the three hierarchical levels. Specifically, P addition decreased nitrogen (N) resorption proficiency, P resorption efficiency and proficiency, but did not impact N resorption efficiency. In addition, P resorption efficiency and proficiency were linearly related to the ratio of inorganic P to organic P and organic P fraction in mature plant organs, respectively. Our findings suggest that the allocation pattern of plant P between inorganic and organic P fractions is an underlying mechanism controlling P resorption processes, and that P enrichment could strongly influence plant-mediated biogeochemical cycles through altered nutrient resorption in the freshwater wetlands of Northeast China. PMID:25631373

  8. Multiple drivers of decline in the global status of freshwater crayfish (Decapoda:Astacidea)

    Science.gov (United States)

    Nadia I. Richman; Monika Böhm; Susan B. Adams; Fernando Alvarez; Elizabeth A. Bergey; John J. S. Bunn; Quinton Burnham; Jay Cordeiro; Jason Coughran; Keith A. Crandall; Kathryn L. Dawkins; Robert J. DiStefano; Niall E. Doran; Lennart Edsman; Arnold G. Eversole; Leopold Füreder; James M. Furse; Francesca Gherardi; Premek Hamr; David M. Holdich; Pierre Horwitz; Kerrylyn Johnston; Clive M. Jones; Julia P. G. Jones; Robert L. Jones; Thomas G. Jones; Tadashi Kawai; Susan Lawler; Marilu López-Mejía; Rebecca M. Miller; Carlos Pedraza-Lara; Julian D. Reynolds; Alastair M. M. Richardson; Mark B. Schultz; Guenter A. Schuster; Peter J. Sibley; Catherine Souty-Grosset; Christopher A. Taylor; Roger F. Thoma; Jerry Walls; Todd S. Walsh; Ben Cohen

    2015-01-01

    Rates of biodiversity loss are higher in freshwater ecosystems than in most terrestrial or marine ecosystems, making freshwater conservation a priority. However, prioritization methods are impeded by insufficient knowledge on the distribution and conservation status of freshwater taxa, particularly invertebrates. We evaluated the extinction risk of the world’s 590...

  9. 78 FR 52192 - Final Aquatic Life Ambient Water Quality Criteria For Ammonia-Freshwater 2013

    Science.gov (United States)

    2013-08-22

    ... ambient water quality criteria for the protection of aquatic life from effects of ammonia in freshwater... ammonia to freshwater aquatic life. On December 30, 2009, EPA published draft national recommended water... freshwater are intended to protect aquatic life and do not address human health toxicity data. The water...

  10. Lysogenic infection in sub-tropical freshwater cyanobacteria cultures and natural blooms

    NARCIS (Netherlands)

    Steenhauer, L.M.; Pollard, P.C.; Brussaard, C.P.D.; Säwström, C.

    2014-01-01

    Lysogeny has been reported for a few freshwater cyanobacteria cultures, but it is unknown how prevalent it is in freshwater cyanobacteria in situ. Here we tested for lysogeny in (a) cultures of eight Australian species of subtropical freshwater cyanobacteria; (b) seven strains of one species:

  11. Seasonal comparison of aquatic macroinvertebrate assemblages in a flooded coastal freshwater marsh

    Science.gov (United States)

    Kang, Sung-Ryong; King, Sammy L.

    2013-01-01

    Marsh flooding and drying may be important factors affecting aquatic macroinvertebrate density and distribution in coastal freshwater marshes. Limited availability of water as a result of drying in emergent marsh may decrease density, taxonomic diversity, and taxa richness. The principal objectives of this study are to characterize the seasonal aquatic macroinvertebrate assemblage in a freshwater emergent marsh and compare aquatic macroinvertebrate species composition, density, and taxonomic diversity to that of freshwater marsh ponds. We hypothesize that 1) freshwater emergent marsh has lower seasonal density and taxonomic diversity compared to that of freshwater marsh ponds; and 2) freshwater emergent marsh has lower taxa richness than freshwater marsh ponds. Seasonal aquatic macroinvertebrate density in freshwater emergent marsh ranged from 0 organisms/m2 (summer 2009) to 91.1 ± 20.53 organisms/m2 (mean ± SE; spring 2009). Density in spring was higher than in all other seasons. Taxonomic diversity did not differ and there were no unique species in the freshwater emergent marsh. Our data only partially support our first hypothesis as aquatic macroinvertebrate density and taxonomic diversity between freshwater emergent marsh and ponds did not differ in spring, fall, and winter but ponds supported higher macroinvertebrate densities than freshwater emergent marsh during summer. However, our data did not support our second hypothesis as taxa richness between freshwater emergent marsh and ponds did not statistically differ.

  12. Onset of white striping and progression into wooden breast as defined by myopathic changes underlying Pectoralis major growth. Estimation of growth parameters as predictors for stage of myopathy progression.

    Science.gov (United States)

    Griffin, Jacqueline Reedy; Moraes, Luis; Wick, Macdonald; Lilburn, Michael Snell

    2018-02-01

    The broiler industry has incurred significant economic losses due to two muscle myopathies, white striping (WS) and wooden breast (WB), affecting the Pectoralis major (P. major) of commercial broilers. The present study documented macroscopic changes occurring with age/growth in the P. major and P. minor muscles of commercial broilers from day 2 through day 46 (n = 27/day). Distinct myopathic aberrations observed in both breast muscles corresponded to the onset of WB. These distinct morphological changes were used as determinants in developing a ranking system, defining the ontogeny of WB as the following four stages: (1) WS, (2) petechial epimysium haemorrhages, (3) intramuscular haemorrhages and (4) ischaemia. A cumulative logit proportional odds model was used to relate the rank probabilities with the following growth parameters: body weight, P. major and P. minor weight/yield/length/width/depth. The best-fit model included P. major length/width/depth, P. minor width, P. major and P. minor yield as predictors for rank. Increasing P. major depth, P. minor width and P. major yield increased the odds of falling into higher ranks (more severe myopathy). Conversely, increasing P. major length, P. major width and P. minor yield increased the odds of falling into smaller ranks (less severe myopathy). This study describes the macroscopic changes associated with WB ontogeny in the development of a ranking system and the contribution of growth parameters in the determination of rank (WB severity). Results suggest that physical measurements inherent to selection for high-yielding broiler genotypes are contributing to the occurrence and severity of WS and WB.

  13. A faunistic survey of digenean larvae infecting freshwater snails ...

    African Journals Online (AJOL)

    Biomphalaria and Bulinus spp have been reported in Tanzania as vectors of Schistosoma mansoni and Schistosoma haematobium respectively. Thus most schistosomiasis control efforts have focussed on elimination of these molluscs in freshwater systems or deworming infected persons. In addition almost there is limited ...

  14. Biota connect aquatic habitats throughout freshwater ecosystem mosaics

    Science.gov (United States)

    Schofield, Kate A.; Alexander, Laurie C.; Ridley, Caroline E.; Vanderhoof, Melanie; Fritz, Ken M.; Autrey, Bradley; DeMeester, Julie; Kepner, William G.; Lane, Charles R.; Leibowitz, Scott; Pollard, Amina I.

    2018-01-01

    Freshwater ecosystems are linked at various spatial and temporal scales by movements of biota adapted to life in water. We review the literature on movements of aquatic organisms that connect different types of freshwater habitats, focusing on linkages from streams and wetlands to downstream waters. Here, streams, wetlands, rivers, lakes, ponds, and other freshwater habitats are viewed as dynamic freshwater ecosystem mosaics (FEMs) that collectively provide the resources needed to sustain aquatic life. Based on existing evidence, it is clear that biotic linkages throughout FEMs have important consequences for biological integrity and biodiversity. All aquatic organisms move within and among FEM components, but differ in the mode, frequency, distance, and timing of their movements. These movements allow biota to recolonize habitats, avoid inbreeding, escape stressors, locate mates, and acquire resources. Cumulatively, these individual movements connect populations within and among FEMs and contribute to local and regional diversity, resilience to disturbance, and persistence of aquatic species in the face of environmental change. Thus, the biological connections established by movement of biota among streams, wetlands, and downstream waters are critical to the ecological integrity of these systems. Future research will help advance our understanding of the movements that link FEMs and their cumulative effects on downstream waters.

  15. Differential responses of freshwater wetland soils to sulphate pollution

    NARCIS (Netherlands)

    Lamers, L.P.M.; Dolle, ten G.E.; Berg, van den S.T.G.; Delft, van S.P.J.; Roelofs, J.G.M.

    2001-01-01

    Sulphate (SO42-) reduction rates are generally low in freshwater wetlands and are regulated by the scarce availability of the ion. Increased concentrations of this electron acceptor due to sulphur (S) pollution of groundwater and surface water may, however, lead to high sulphate reduction rates now

  16. Patterns of distribution and conservation status of freshwater fishes ...

    African Journals Online (AJOL)

    Hotspots of fish species richness occur in the north-eastern lowveld sectors of South Africa and along the ecotone between the tropical/ subtropical and temperate ... of conservation concern for freshwater fishes is emphasized, and highlights the importance of well-preserved voucher specimens for biodiversity conservation.

  17. Fatty acid composition and amino acid profile of two freshwater ...

    African Journals Online (AJOL)

    The proximate, fatty and amino acids composition of two commercially important freshwater fish species Clarias gariepinus and Tilapia zillii. purchased from local fishermen in two landing sites in Lagos State, Nigeria were determined. Live specimens of C. gariepinus were purchased while samples of T. zillii were stored in ...

  18. Genetic calibration of species diversity among North America's freshwater fishes.

    Science.gov (United States)

    April, Julien; Mayden, Richard L; Hanner, Robert H; Bernatchez, Louis

    2011-06-28

    Freshwater ecosystems are being heavily exploited and degraded by human activities all over the world, including in North America, where fishes and fisheries are strongly affected. Despite centuries of taxonomic inquiry, problems inherent to species identification continue to hamper the conservation of North American freshwater fishes. Indeed, nearly 10% of species diversity is thought to remain undescribed. To provide an independent calibration of taxonomic uncertainty and to establish a more accessible molecular identification key for its application, we generated a standard reference library of mtDNA sequences (DNA barcodes) derived from expert-identified museum specimens for 752 North American freshwater fish species. This study demonstrates that 90% of known species can be delineated using barcodes. Moreover, it reveals numerous genetic discontinuities indicative of independently evolving lineages within described species, which points to the presence of morphologically cryptic diversity. From the 752 species analyzed, our survey flagged 138 named species that represent as many as 347 candidate species, which suggests a 28% increase in species diversity. In contrast, several species of parasitic and nonparasitic lampreys lack such discontinuity and may represent alternative life history strategies within single species. Therefore, it appears that the current North American freshwater fish taxonomy at the species level significantly conceals diversity in some groups, although artificially creating diversity in others. In addition to providing an easily accessible digital identification system, this study identifies 151 fish species for which taxonomic revision is required.

  19. Fatty Acid Composition of Six Freshwater Wild Cyanobacterial Species

    Czech Academy of Sciences Publication Activity Database

    Řezanka, Tomáš; Dor, I.; Prell, Aleš; Dembitský, V. M.

    2003-01-01

    Roč. 48, č. 1 (2003), s. 71-75 ISSN 0015-5632 Institutional research plan: CEZ:AV0Z5020903 Keywords : cyanobacterial spcies * freshwater wild Subject RIV: EE - Microbiology, Virology Impact factor: 0.857, year: 2003

  20. Tropical Freshwater Biology - Vol 18, No 2 (2009)

    African Journals Online (AJOL)

    Organic fertilizer decomposition and nutrient loads in water reservoir with changing temperature, Wakiso – Ug · EMAIL FULL TEXT EMAIL FULL TEXT ... benthos in response to the biodeposition and bioturbation activities of the freshwater mussel Lamellidens marginalis (Lamarck) · EMAIL FULL TEXT EMAIL FULL TEXT

  1. The occurrence of digenean larvae in freshwater snails at Mbezi ...

    African Journals Online (AJOL)

    The occurrence of digenean larvae in freshwater snails at Mbezi-Temboni pond, Dar es Salaam. ESP Kigadye, G Nkwengulila. Abstract. The abundance of digenean larvae in snails at a pond in Mbezi-Temboni, Dar es Salaam, was investigated from July 1996 to June 1997. A total of 2,112 snails belonging to three species, ...

  2. SOME PARASITIC WORMS IN FRESHWATER FISHES AND FISH ...

    African Journals Online (AJOL)

    and on the other hand to forms in freshwater fishes of the Indo-Malaysian region, it would ... about 25 p.m in total length, of which the sickle-shaped terminal structure .... The ejaculatory duct is short and runs from the genital ...... This larva appears to be very common in C. gariepinus collected ..... Onderstepoort J. vet. Sci.

  3. Interactions between nutrients and toxicants in shallow freshwater model ecosystems

    NARCIS (Netherlands)

    Roessink, I.

    2008-01-01

    This thesis investigates the influence of the trophic status of a shallow freshwater system and/or the presence of persistent pollutants in the sediment on the fate and ecological effects of an insecticide and a fungicide/biocide. Additionally, this thesis aims to shed light on the influence of

  4. Ecological risks of pesticides in freshwater ecosystems; Part 1: herbicides

    NARCIS (Netherlands)

    Brock, T.C.M.; Lahr, J.; Brink, van den P.J.

    2000-01-01

    A literature review of freshwater model ecosystem studies with herbicides was performed to assess the NOEC[sub]ecosystem for individual compounds, to compare these threshold levels with water quality standards, and to evaluate the ecological consequences of exceeding these standards. Studies were

  5. Toxicological evaluation of parathion and azinphosmethyl in freshwater model ecosystems

    NARCIS (Netherlands)

    Dortland, R.J.

    1980-01-01

    A study was made of the possible hazards of long-term exposure of freshwater ecosystems to low (< 1 mg m -3) concentrations of organophosphorus insecticides. Range-finding, acute and sub-acute (3 weeks) laboratory toxicity trials were

  6. Rapid screening of operational freshwater availability using global models

    NARCIS (Netherlands)

    Straatsma, M.W.; Vermeulen, P.; Kuijper, Marijn; Bonte, Matthijs; Niele, Frank; Bierkens, M.F.P.

    Freshwater shortage already affects large parts of the world, and is expected to increase rapidly over the coming decades as a result of increased water demands and the impacts of climate change. Global-scale water risk or stress maps are available online, but these lack quantitative information on

  7. Standard methods for sampling freshwater fishes: Opportunities for international collaboration

    Czech Academy of Sciences Publication Activity Database

    Bonar, S. A.; Mercado-Silva, N.; Hubert, W.A.; Beard, T. D.; Dave, G.; Kubečka, Jan; Graeb, B.D.S.; Lester, N.P.; Porath, M.; Winfield, I. J.

    2017-01-01

    Roč. 42, č. 3 (2017), s. 150-156 ISSN 0363-2415 Institutional support: RVO:60077344 Keywords : European lakes * size structure * conservation * UK Subject RIV: EH - Ecology, Behaviour OBOR OECD: Marine biology, freshwater biology, limnology Impact factor: 3.000, year: 2016

  8. Biomass, Mineral Elements and Protein Contents of Six Freshwater ...

    African Journals Online (AJOL)

    The biomass, mineral elements and protein contents of six freshwater macrophytes found in Ghana are reported in this paper. The plants are Ceratophyllum demersum (a submerged plant), Eichhornia crassipes and Pistia stratiotes (free-floating plants), Echinochloa pyramidalis and Typha domingensis (emergent plants) ...

  9. Preliminary Studies on the Occurrence of Freshwater Epipelic Algae ...

    African Journals Online (AJOL)

    The occurrence and composition of the freshwater algae in the epipelon were determined at three sites, namely Machigeni, Manhean and Weija, located in the coastal savanna thicket and grassland vegetation zone of the River Densu basin in southern Ghana. Samples of sediments from the water-substratum interface ...

  10. Three more Mangrove trees growing locally in nature in freshwater

    NARCIS (Netherlands)

    Steenis, van C.G.G.J.

    1984-01-01

    In Christmas Island (Indian Ocean) the mangrove trees Bruguiera gymnorrhiza (L.) Sav., B. sexangula (Lour.) Poir. (Rhizophoraceae) and Heritiera littoralis Ait. (Sterculiaceae) are found inland near freshwater springs at some 20-30 m altitude, far from the beach. It is concluded that the inland

  11. Dinoflagellates associated with freshwater sponges from the ancient lake baikal.

    Science.gov (United States)

    Annenkova, Natalia V; Lavrov, Dennis V; Belikov, Sergey I

    2011-04-01

    Dinoflagellates are a diverse group of protists that are common in both marine and freshwater environments. While the biology of marine dinoflagellates has been the focus of several recent studies, their freshwater relatives remain little-investigated. In the present study we explore the diversity of dinoflagellates in Lake Baikal by identifying and analyzing dinoflagellate sequences for 18S rDNA and ITS-2 from total DNA extracted from three species of endemic Baikalian sponges (Baikalospongia intermedia,Baikalospongia rectaand Lubomirskia incrustans). Phylogenetic analyses of these sequences revealed extensive dinoflagellate diversity in Lake Baikal. We found two groups of sequences clustering within the order Suessiales, known for its symbiotic relationships with various invertebrates. Thus they may be regarded as potential symbionts of Baikalian sponges. In addition,Gyrodinium helveticum, representatives from the genus Gymnodinium, dinoflagellates close to the family Pfiesteriaceae, and a few dinoflagellates without definite affiliation were detected. No pronounced difference in the distribution of dinoflagellates among the studied sponges was found, except for the absence of the Piscinoodinium-like dinoflagellates inL. incrustans. To the best of our knowledge, this is the first study of the diversity of dinoflagellates in freshwater sponges, the first systematic investigation of dinoflagellate molecular diversity in Lake Baikal and the first finding of members of the order Suessiales as symbionts of freshwater invertebrates. Copyright © 2010 Elsevier GmbH. All rights reserved.

  12. The effectiveness of surrogate taxa to conserve freshwater biodiversity

    Science.gov (United States)

    Stewart, David R.; Underwood, Zachary E.; Rahel, Frank J.; Walters, Annika W.

    2018-01-01

    Establishing protected areas has long been an effective conservation strategy, and is often based on more readily surveyed species. The potential of any freshwater taxa to be a surrogate of other aquatic groups has not been fully explored. We compiled occurrence data on 72 species of freshwater fish, amphibians, mussels, and aquatic reptiles for the Great Plains, Wyoming. We used hierarchical Bayesian multi-species mixture models and MaxEnt models to describe species distributions, and program Zonation to identify conservation priority areas for each aquatic group. The landscape-scale factors that best characterized aquatic species distributions differed among groups. There was low agreement and congruence among taxa-specific conservation priorities (<20%), meaning that no surrogate priority areas would include or protect the best habitats of other aquatic taxa. We found that common, wide-ranging aquatic species were included in taxa-specific priority areas, but rare freshwater species were not included. Thus, the development of conservation priorities based on a single freshwater aquatic group would not protect all species in the other aquatic groups.

  13. Conservation status of imperiled North American freshwater and diadromous fishes

    Science.gov (United States)

    Howard L. Jelks; Stephen J. Walsh; Noel M. Burkhead; Salvador Contreras-Balderas; Edmundo Diaz-Pardo; Dean A. Hendrickson; John Lyons; Nicholas E. Mandrak; Frank McCormick; Joseph S. Nelson; Steven P. Plantania; Brady A. Porter; Claude B. Renaud; Juan Jacobo Schmitter-Soto; Eric B. Taylor; Melvin L. Jr. Warren

    2008-01-01

    This is the third compilation of imperiled (i.e., endangered, threatened, vulnerable) plus extinct freshwater and diadromous fishes of North America prepared by the American Fisheries Society?s Endangered Species Committee. Since the last revision in 1989, imperilment of inland fishes has increased substantially. This list includes 700 extant taxa representing 133...

  14. Effects of pollution on freshwater fish and amphibians

    International Nuclear Information System (INIS)

    Pickering, Q.H.; Hunt, E.P.; Phipps, G.L.; Roush, T.H.; Smith, W.E.; Spehar, D.L.; Stephan, C.E.; Tanner, D.K.

    1983-01-01

    A literature review is presented dealing with studies on the effects of pollution on freshwater fish and amphibians. The pollutants studied included acid mine drainage, PCBs, cadmium, lead, naphthalene, plutonium, in addition to several studies dealing with pH effects

  15. A hierarchical classification of freshwater mussel diversity in North America

    Science.gov (United States)

    Wendell R. Haag

    2010-01-01

    Aim North America harbours the most diverse freshwater mussel fauna on Earth. This fauna has high endemism at the continental scale and within individual river systems. Previous faunal classifications for North America were based on intuitive, subjective assessments of species distributions, primarily the occurrence of endemic species, and do not portray continent-wide...

  16. Freshwater invertebrates of sub-Antarctic Marion Island | Dartnall ...

    African Journals Online (AJOL)

    The aquatic species include five platyhelminthes, a gastrotrich, three tardigrades, 28 rotifers, six nematodes, two annelids and 11 arthropods. Most are familiar species that have been recorded on other sub-Antarctic islands. The invertebrate faunas of the various freshwater habitats were basically similar in species ...

  17. Physiological response of one of South Africa's premier freshwater ...

    African Journals Online (AJOL)

    Physiological response of one of South Africa's premier freshwater sport angling species, the Orange-Vaal smallmouth yellowfish Labeobarbus aeneus, ... These data suggest that catch-and-release causes physiological stress to fish, but nonetheless this practice can be a valuable fisheries management tool to ensure the ...

  18. First record of predation by the alien invasive freshwater fish ...

    African Journals Online (AJOL)

    First record of predation by the alien invasive freshwater fish Micropterus salmoides L. (Centrarchidae) on migrating estuarine fishes in South Africa. ... Estuarine fish species, Monodactylus falciformis, and two species of the family Mugilidae, Mugil cephalus and Myxus capensis, were the most common fish prey in both size ...

  19. Establishing a database of radionuclide transfer parameters for freshwater wildlife

    International Nuclear Information System (INIS)

    Yankovich, T.; Beresford, N.A.; Fesenko, S.; Fesenko, J.; Phaneuf, M.; Dagher, E.; Outola, I.; Andersson, P.; Thiessen, K.; Ryan, J.; Wood, M.D.; Bollhöfer, A.

    2013-01-01

    Environmental assessments to evaluate potentials risks to humans and wildlife often involve modelling to predict contaminant exposure through key pathways. Such models require input of parameter values, including concentration ratios, to estimate contaminant concentrations in biota based on measurements or estimates of concentrations in environmental media, such as water. Due to the diversity of species and the range in physicochemical conditions in natural ecosystems, concentration ratios can vary by orders of magnitude, even within similar species. Therefore, to improve model input parameter values for application in aquatic systems, freshwater concentration ratios were collated or calculated from national grey literature, Russian language publications, and refereed papers. Collated data were then input into an international database that is being established by the International Atomic Energy Agency. The freshwater database enables entry of information for all radionuclides listed in ICRP (1983), in addition to the corresponding stable elements, and comprises a total of more than 16,500 concentration ratio (CR wo-water ) values. Although data were available for all broad wildlife groups (with the exception of birds), data were sparse for many organism types. For example, zooplankton, crustaceans, insects and insect larvae, amphibians, and mammals, for which there were CR wo-water values for less than eight elements. Coverage was most comprehensive for fish, vascular plants, and molluscs. To our knowledge, the freshwater database that has now been established represents the most comprehensive set of CR wo-water values for freshwater species currently available for use in radiological environmental assessments

  20. Anaemia in the freshwater catfish Clarias albopunctatus (Teleostei ...

    African Journals Online (AJOL)

    Haematological changes were studied in freshwater catfish Clarias albopunctatus exposed for 20 days to 25%, 50% and 100% concentrations of brewery wastewater prepared by dilution using tap water. Haemoglobin, haematocrit and erythrocyte counts in fish exposed to wastewater were significantly lower than in a ...

  1. Characterization of CO2 leakage into the freshwater body

    DEFF Research Database (Denmark)

    Singh, Ashok; Delfs, Jens Olaf; Shao, H.

    2013-01-01

    urrent research into CO2 capture and storage is dominated by improving the CO2 storage capacity. In this context, risk related to CO2 leakage is an important issue which may cause environmental problems, particularly when freshwater resources nearby are intruded by the CO2 plume. In this work...

  2. Conceptualising the interactive effects of climate change and biological invasions on subarctic freshwater fish.

    Science.gov (United States)

    Rolls, Robert J; Hayden, Brian; Kahilainen, Kimmo K

    2017-06-01

    Climate change and species invasions represent key threats to global biodiversity. Subarctic freshwaters are sentinels for understanding both stressors because the effects of climate change are disproportionately strong at high latitudes and invasion of temperate species is prevalent. Here, we summarize the environmental effects of climate change and illustrate the ecological responses of freshwater fishes to these effects, spanning individual, population, community and ecosystem levels. Climate change is modifying hydrological cycles across atmospheric, terrestrial and aquatic components of subarctic ecosystems, causing increases in ambient water temperature and nutrient availability. These changes affect the individual behavior, habitat use, growth and metabolism, alter population spawning and recruitment dynamics, leading to changes in species abundance and distribution, modify food web structure, trophic interactions and energy flow within communities and change the sources, quantity and quality of energy and nutrients in ecosystems. Increases in temperature and its variability in aquatic environments underpin many ecological responses; however, altered hydrological regimes, increasing nutrient inputs and shortened ice cover are also important drivers of climate change effects and likely contribute to context-dependent responses. Species invasions are a complex aspect of the ecology of climate change because the phenomena of invasion are both an effect and a driver of the ecological consequences of climate change. Using subarctic freshwaters as an example, we illustrate how climate change can alter three distinct aspects of species invasions: (1) the vulnerability of ecosystems to be invaded, (2) the potential for species to spread and invade new habitats, and (3) the subsequent ecological effects of invaders. We identify three fundamental knowledge gaps focused on the need to determine (1) how environmental and landscape characteristics influence the

  3. Cytotoxicity of TiO{sub 2} nanoparticles and their detoxification in a freshwater system

    Energy Technology Data Exchange (ETDEWEB)

    Dalai, Swayamprava; Pakrashi, Sunandan; Joyce Nirmala, M.; Chaudhri, Apoorvi; Chandrasekaran, N. [Centre for Nanobiotechnology, VIT University, Vellore (India); Mandal, A.B. [Chemical Laboratory, Central Leather Research Institute, Chennai (India); Mukherjee, Amitava, E-mail: amitav@vit.ac.in [Centre for Nanobiotechnology, VIT University, Vellore (India)

    2013-08-15

    Highlights: •TiO{sub 2} NPs cytotoxicity at low exposure levels (≤1 μg/mL) to freshwater algae. •ROS generation, NP adsorption and internalization contributors to toxicity. •Observational evidence of genotoxicity by nanoparticles in an algal cell. •Reduced bioavailability thus detoxification of NPs by microalgae. •Possible role of EPS in detoxification. -- Abstract: In the current study, two aspects concerning (i) the cytotoxicity potential of TiO{sub 2} nanoparticles (NPs) toward freshwater algal isolate Scenedesmus obliquus and (ii) the potential detoxification of NPs by the microalgae were assessed under light (UV-illumination) and dark conditions at low exposure levels (≤1 μg/mL), using sterile freshwater as the test medium. The statistically significant reduction in cell viability, increase in reactive oxygen species production and membrane permeability (light vs. dark) suggested photo-induced toxicity of TiO{sub 2} NPs. The electron micrographs demonstrated adsorption of the NPs onto the cell surface and substantiated their internalization/uptake. The fluorescence micrographs and the confocal laser scanning (CLSM) images suggested the absence of a definite/intact nucleus in the light treated cells pointing toward the probable genotoxic effects of NPs. In a separate three cycle experiment, a continuous decrease in the cytotoxicity was observed, whereas, at the end of each cycle only fresh algae were added to the supernatant containing NPs from the previous cycle. The decreasing concentrations of the NPs in the subsequent cycles owing to agglomeration–sedimentation processes exacerbated by the algal interactions played a crucial role in the detoxification. In addition, the exo-polymeric substances produced by the cells could have rendered the available NPs less reactive, thereby, enhancing the detoxification effects.

  4. Cytotoxicity of TiO2 nanoparticles and their detoxification in a freshwater system

    International Nuclear Information System (INIS)

    Dalai, Swayamprava; Pakrashi, Sunandan; Joyce Nirmala, M.; Chaudhri, Apoorvi; Chandrasekaran, N.; Mandal, A.B.; Mukherjee, Amitava

    2013-01-01

    Highlights: •TiO 2 NPs cytotoxicity at low exposure levels (≤1 μg/mL) to freshwater algae. •ROS generation, NP adsorption and internalization contributors to toxicity. •Observational evidence of genotoxicity by nanoparticles in an algal cell. •Reduced bioavailability thus detoxification of NPs by microalgae. •Possible role of EPS in detoxification. -- Abstract: In the current study, two aspects concerning (i) the cytotoxicity potential of TiO 2 nanoparticles (NPs) toward freshwater algal isolate Scenedesmus obliquus and (ii) the potential detoxification of NPs by the microalgae were assessed under light (UV-illumination) and dark conditions at low exposure levels (≤1 μg/mL), using sterile freshwater as the test medium. The statistically significant reduction in cell viability, increase in reactive oxygen species production and membrane permeability (light vs. dark) suggested photo-induced toxicity of TiO 2 NPs. The electron micrographs demonstrated adsorption of the NPs onto the cell surface and substantiated their internalization/uptake. The fluorescence micrographs and the confocal laser scanning (CLSM) images suggested the absence of a definite/intact nucleus in the light treated cells pointing toward the probable genotoxic effects of NPs. In a separate three cycle experiment, a continuous decrease in the cytotoxicity was observed, whereas, at the end of each cycle only fresh algae were added to the supernatant containing NPs from the previous cycle. The decreasing concentrations of the NPs in the subsequent cycles owing to agglomeration–sedimentation processes exacerbated by the algal interactions played a crucial role in the detoxification. In addition, the exo-polymeric substances produced by the cells could have rendered the available NPs less reactive, thereby, enhancing the detoxification effects

  5. Decadal phytoplankton dynamics in response to episodic climatic disturbances in a subtropical deep freshwater ecosystem.

    Science.gov (United States)

    Ko, Chia-Ying; Lai, Chao-Chen; Hsu, Huang-Hsiung; Shiah, Fuh-Kwo

    2017-02-01

    Information of the decadal timescale effects of episodic climatic disturbances (i.e., typhoons) on phytoplankton in freshwater ecosystems have received less attention and fewer seasonal evaluations partly due to the lack of long-term time-series monitoring data in typhoon prevailing areas. Through field observations of a total 36 typhoon cases in a subtropical deep freshwater ecosystem in the period of 2005-2014, we quantified phytoplankton biomass, production and growth rate in response to meteorological and hydrological changes in the weeks before, during and after typhoons between summer and autumn, and also investigated the effects of typhoon characteristics on the aforementioned phytoplankton responses. The results showed that phytoplankton exposed to typhoon disturbances generally exhibited an increasing trend over the weeks before, during and after typhoons in summer but varied in autumn. The correlations and multivariate regressions showed different contributions of meteorological and hydrological variables to individual phytoplankton responses before, during and after typhoons between seasons. The post-typhoon weeks (i.e., within two weeks after a typhoon had passed) were especially important for the timeline of phytoplankton increases and with a detectable seasonal variation that the chlorophyll a concentration significantly increased in autumn whereas both primary production and growth rate were associated with significant changes in summer. Additionally, phytoplankton responses during the post-typhoon weeks were significantly different between discrete or continuous types of typhoon events. Our work illustrated the fact that typhoons did influence phytoplankton responses in the subtropical deep freshwater ecosystem and typhoon passages in summer and autumn affected the phytoplankton dynamics differently. Nevertheless, sustained and systematic monitoring in order to advance our understanding of the role of typhoons between seasons in the modulation of

  6. Factors affecting assemblage attributes of freshwater Oligochaeta in Neotropical shallow floodplain lakes

    Directory of Open Access Journals (Sweden)

    Vanessa Ernandes de Amo

    2017-12-01

    Full Text Available Abstract Aim: Identify the effects of sediment composition and water conditions on diversity, richness, evenness, density and composition of freshwater Oligochaeta in shallow floodplain lakes. Methods We sampled 13 shallow floodplain lakes quarterly during the year 2010 in the Upper Paraná River floodplain. In each lake, four sediment samples were taken from the shore and central regions, three of them were used for biological analysis, and one for granulometric analysis. Concomitantly, temperature, dissolved oxygen, pH, conductivity, alkalinity, turbidity and chlorophyll-a were also measured. Initially, the biological samples were analyzed by a stereoscopic microscope. Oligochaeta individuals were identified under optical microscope at the lowest possible taxonomic level. For data analysis, we quantified density, richness, evenness and diversity index of freshwater Oligochaeta. In order to show differences between the months and the analyzed lakes, in relation to the percentages of coarse and fine organic material, the nonparametric Kruskal Wallis test was used. We also calculated the sediment granulometric diversity using the Shannon-Wienner index, using a simple regression analysis. We correlated assemblage attributes of Oligochaeta with sediment diversity and the assemblage species with the limnological variables using the Spearman correlation. Results A total of 2,090 individuals were found distributed among 27 species. From the total individuals number, 57% were Pristina americana, followed by Dero (Dero righii with 13%. Assemblage attributes were not significantly correlated with sediment diversity, and 7 of the 27 species recorded showed significant correlations with at least some of the abiotic variables. Conclusions We verified that the abiotic variables of the water present greater influence on the attributes of the assemblage of freshwater Oligochaeta, when compared with sediment influences. Although we found low local diversity of

  7. Distribution and Modeled Transport of Plastic Pollution in the Great Lakes, the World's Largest Freshwater Resource

    Directory of Open Access Journals (Sweden)

    Rachel N. Cable

    2017-07-01

    Full Text Available Most plastic pollution originates on land. As such, freshwater bodies serve as conduits for the transport of plastic litter to the ocean. Understanding the concentrations and fluxes of plastic litter in freshwater ecosystems is critical to our understanding of the global plastic litter budget and underpins the success of future management strategies. We conducted a replicated field survey of surface plastic concentrations in four lakes in the North American Great Lakes system, the largest contiguous freshwater system on the planet. We then modeled plastic transport to resolve spatial and temporal variability of plastic distribution in one of the Great Lakes, Lake Erie. Triplicate surface samples were collected at 38 stations in mid-summer of 2014. Plastic particles >106 μm in size were quantified. Concentrations were highest near populated urban areas and their water infrastructure. In the highest concentration trawl, nearly 2 million fragments km−2 were found in the Detroit River—dwarfing previous reports of Great Lakes plastic abundances by over 4-fold. Yet, the accuracy of single trawl counts was challenged: within-station plastic abundances varied 0- to 3-fold between replicate trawls. In the smallest size class (106–1,000 μm, false positive rates of 12–24% were determined analytically for plastic vs. non-plastic, while false negative rates averaged ~18%. Though predicted to form in summer by the existing Lake Erie circulation model, our transport model did not predict a permanent surface “Lake Erie Garbage Patch” in its central basin—a trend supported by field survey data. Rather, general eastward transport with recirculation in the major basins was predicted. Further, modeled plastic residence times were drastically influenced by plastic buoyancy. Neutrally buoyant plastics—those with the same density as the ambient water—were flushed several times slower than plastics floating at the water's surface and exceeded the

  8. Dietary exposure to perfluoroalkyl acids of specific French adult sub-populations: High seafood consumers, high freshwater fish consumers and pregnant women

    International Nuclear Information System (INIS)

    Yamada, A.; Bemrah, N.; Veyrand, B.; Pollono, C.; Merlo, M.; Desvignes, V.; Sirot, V.

    2014-01-01

    Perfluoroalkyl acids (PFAAs) are globally found in various media, including food and especially fishery products. In the present study, the dietary exposure to 15 perfluoroalkyl acids was assessed for 3 French adult populations, namely high seafood consumers, high freshwater fish consumers, and pregnant women. Purified food extracts were analysed by LC–MS/MS and PFBA, PFPA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFTrDA, PFTeDA, PFBS, PFHxS, PFHpS, PFOS and PFDS were monitored and quantified according to the isotope dilution principle. Under lower bound (LB) hypothesis (i.e. contamination values < LOD considered as 0), high freshwater fish consumers appear as the most exposed to PFOS (7.5 ng.kg −1 bw.d −1 ), PFUnA (1.3 ng.kg −1 bw.d −1 ), PFDA (0.4 ng.kg −1 bw.d −1 ) and PFHpS (0.03 ng.kg −1 bw.d −1 ) while high seafood consumers appear as the most exposed to PFOA (1.2 ng.kg −1 bw.d −1 ), PFNA (0.2 ng.kg −1 bw.d −1 ) and PFHxS (0.06 ng.kg −1 bw.d −1 ). For all considered populations, the major exposure contributors are fish, seafood and water under LB hypothesis, while dairy products, bread and crispbread are the main contributors under upper bound (UB) hypothesis. Besides this food exposure assessment, further studies are needed to assess the more global PFAA exposure, taking into account indoor and outdoor air, dust and cutaneous contact, which could be other important contributors for this particular class of chemicals. - Highlights: • The dietary exposure was estimated for 15 perfluoroalkyl acids. • Despite the overestimation, the FFQ remains useful to evaluate the whole diet. • The high fish consumers are the most dietary exposed population. • Fishery products are the main exposure contributors under LB hypothesis

  9. Dietary exposure to perfluoroalkyl acids of specific French adult sub-populations: High seafood consumers, high freshwater fish consumers and pregnant women

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, A., E-mail: ami.s.yamada@gmail.com [Risk Assessment Directorate, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), 27-31 avenue du Général Leclerc, Maisons-Alfort 94701 (France); Bemrah, N., E-mail: nawel.bemrah@anses.fr [Risk Assessment Directorate, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), 27-31 avenue du Général Leclerc, Maisons-Alfort 94701 (France); Veyrand, B., E-mail: bruno.veyrand@oniris-nantes.fr [LUNAM Université, Oniris, Laboratoire d' Etude des Résidus et Contaminants dans les Aliments (LABERCA), USC INRA 1329, Nantes 44307 (France); Pollono, C., E-mail: charles.pollono@oniris-nantes.fr [LUNAM Université, Oniris, Laboratoire d' Etude des Résidus et Contaminants dans les Aliments (LABERCA), USC INRA 1329, Nantes 44307 (France); Merlo, M., E-mail: mathilde.merlo@anses.fr [Risk Assessment Directorate, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), 27-31 avenue du Général Leclerc, Maisons-Alfort 94701 (France); Desvignes, V., E-mail: virginie.desvignes@anses.fr [Risk Assessment Directorate, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), 27-31 avenue du Général Leclerc, Maisons-Alfort 94701 (France); Sirot, V., E-mail: sirotv@gmail.com [Risk Assessment Directorate, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), 27-31 avenue du Général Leclerc, Maisons-Alfort 94701 (France); and others

    2014-09-01

    Perfluoroalkyl acids (PFAAs) are globally found in various media, including food and especially fishery products. In the present study, the dietary exposure to 15 perfluoroalkyl acids was assessed for 3 French adult populations, namely high seafood consumers, high freshwater fish consumers, and pregnant women. Purified food extracts were analysed by LC–MS/MS and PFBA, PFPA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFTrDA, PFTeDA, PFBS, PFHxS, PFHpS, PFOS and PFDS were monitored and quantified according to the isotope dilution principle. Under lower bound (LB) hypothesis (i.e. contamination values < LOD considered as 0), high freshwater fish consumers appear as the most exposed to PFOS (7.5 ng.kg{sup −1} bw.d{sup −1}), PFUnA (1.3 ng.kg{sup −1} bw.d{sup −1}), PFDA (0.4 ng.kg{sup −1} bw.d{sup −1}) and PFHpS (0.03 ng.kg{sup −1} bw.d{sup −1}) while high seafood consumers appear as the most exposed to PFOA (1.2 ng.kg{sup −1} bw.d{sup −1}), PFNA (0.2 ng.kg{sup −1} bw.d{sup −1}) and PFHxS (0.06 ng.kg{sup −1} bw.d{sup −1}). For all considered populations, the major exposure contributors are fish, seafood and water under LB hypothesis, while dairy products, bread and crispbread are the main contributors under upper bound (UB) hypothesis. Besides this food exposure assessment, further studies are needed to assess the more global PFAA exposure, taking into account indoor and outdoor air, dust and cutaneous contact, which could be other important contributors for this particular class of chemicals. - Highlights: • The dietary exposure was estimated for 15 perfluoroalkyl acids. • Despite the overestimation, the FFQ remains useful to evaluate the whole diet. • The high fish consumers are the most dietary exposed population. • Fishery products are the main exposure contributors under LB hypothesis.

  10. Freshwater gastropods of Neogene and Quaternary lake systems of Europe - state of the art and outlook

    Science.gov (United States)

    Neubauer, Thomas A.; Harzhauser, Mathias; Mandic, Oleg; Kroh, Andreas

    2013-04-01

    the public via the FreshGEN-database (Freshwater Gastropods of the European Neogene). The most important topics to be tackled based on the data are to search for factors, which explain the γ-diversities through time and to look for geographic gradients in species richness and/or faunal composition. Diversity data and inter-lake comparison will allow estimating endemism rates and quantitatively defining biodiversity hotspots in present and past lakes. Shells-sizes of all taxa will be evaluated to search for general patterns and to define phases of conspicuous "gigantism". The well resolved climate history of Europe during the last 23 million years will be a frame for linking species- and supraspecific compositions with climatic trends and events. Ideally, the project will shed light on the origin of modern lake faunas by the intense cooperation between zoologists and paleontologists. A major aim is to map and define a statistics-based Pan-European biogeography and palaeobiogeography of Neogene to Quaternary freshwater systems. Once established, this database will be open for geographic and/or stratigraphic expansion.

  11. Phenotypic and Transcriptomic Responses of Campylobacter jejuni Suspended in an Artificial Freshwater Medium

    Directory of Open Access Journals (Sweden)

    Hana Trigui

    2017-09-01

    Full Text Available Campylobacter jejuni is the leading cause of campylobacteriosis in the developed world. Although most cases are caused by consumption of contaminated meat, a significant proportion is linked to ingestion of contaminated water. The differences between C. jejuni strains originating from food products and those isolated from water are poorly understood. Working under the hypothesis that water-borne C. jejuni strains are better equipped at surviving the nutrient-poor aquatic environment than food-borne strains, the present study aims to characterize these differences using outbreak strains 81116 and 81-176. Strain 81116 caused a campylobacteriosis outbreak linked to consumption of water, while strain 81-176 was linked to consumption of raw milk. CFU counts and viability assays showed that 81116 survives better than 81-176 at 4°C in a defined freshwater medium (Fraquil. Moreover, 81116 was significantly more resistant to oxidative stress and bile salt than strain 81-176 in Fraquil. To better understand the genetic response of 81116 to water, a transcriptomic profiling study was undertaken using microarrays. Compared to rich broth, strain 81116 represses genes involved in amino acid uptake and metabolism, as well as genes involved in costly biosynthetic processes such as replication, translation, flagellum synthesis and virulence in response to Fraquil. In accordance with the observed increase in stress resistance in Fraquil, 81116 induces genes involved in resistance to oxidative stress and bile salt. Interestingly, genes responsible for cell wall synthesis were also induced upon Fraquil exposure. Finally, twelve unique genes were expressed in Fraquil; however, analysis of their distribution in animal and water isolates showed that they are not uniquely and ubiquitously present in water isolates, and thus, unlikely to play a major role in adaptation to water. Our results show that some C. jejuni strains are more resilient than others, thereby

  12. Locating inputs of freshwater to Lynch Cove, Hood Canal, Washington, using aerial infrared photography

    Science.gov (United States)

    Sheibley, Rich W.; Josberger, Edward G.; Chickadel, Chris

    2010-01-01

    The input of freshwater and associated nutrients into Lynch Cove and lower Hood Canal (fig. 1) from sources such as groundwater seeps, small streams, and ephemeral creeks may play a major role in the nutrient loading and hydrodynamics of this low dissolved-oxygen (hypoxic) system. These disbursed sources exhibit a high degree of spatial variability. However, few in-situ measurements of groundwater seepage rates and nutrient concentrations are available and thus may not represent adequately the large spatial variability of groundwater discharge in the area. As a result, our understanding of these processes and their effect on hypoxic conditions in Hood Canal is limited. To determine the spatial variability and relative intensity of these sources, the U.S. Geological Survey Washington Water Science Center collaborated with the University of Washington Applied Physics Laboratory to obtain thermal infrared (TIR) images of the nearshore and intertidal regions of Lynch Cove at or near low tide. In the summer, cool freshwater discharges from seeps and streams, flows across the exposed, sun-warmed beach, and out on the warm surface of the marine water. These temperature differences are readily apparent in aerial thermal infrared imagery that we acquired during the summers of 2008 and 2009. When combined with co-incident video camera images, these temperature differences allow identification of the location, the type, and the relative intensity of the sources.

  13. Freshwater mineral nitrogen and essential elements in autotrophs in James Ross Island, West Antarctica

    Directory of Open Access Journals (Sweden)

    Coufalík Pavel

    2016-12-01

    Full Text Available The lakes and watercourses are habitats for various communities of cyanobacteria and algae, which are among the few primary producers in Antarctica. The amount of nutrients in the mineral-poor Antarctic environment is a limiting factor for the growth of freshwater autotrophs in most cases. In this study, the main aim was to assess the availability of mineral nitrogen for microorganisms in cyanobacterial mats in James Ross Island. The nitrate and ammonium ions in water environment were determined as well as the contents of major elements (C, N, P, S, Na, K, Ca, Mg, Al, Fe, Mn in cyanobacterial mats. The molar ratios of C:N, C:P and N:P in mats were in focus. The growth of freshwater autotrophs seems not to be limited by the level of nitrogen, according to the content of available mineral nitrogen in water and the biogeochemical stoichiometry of C:N:P. The source of nutrients in the Ulu Peninsula is not obvious. The nitrogen fixation could enhance the nitrogen content in mats, which was observed in some samples containing the Nostoc sp.

  14. Enzymes of energy metabolism in hatchlings of amazonian freshwater turtles (Testudines, Podocnemididae

    Directory of Open Access Journals (Sweden)

    WP. Duncan

    Full Text Available The metabolic profiles of selected tissues were analyzed in hatchlings of the Amazonian freshwater turtles Podocnemis expansa, P. unifilis and P. sextuberculata. Metabolic design in these species was judged based on the key enzymes of energy metabolism, with special emphasis on carbohydrate, lipid, amino acid and ketone body metabolism. All species showed a high glycolytic potential in all sampled tissues. Based on low levels of hexokinase, glycogen may be an important fuel for these species. The high lactate dehydrogenase activity in the liver may play a significant role in carbohydrate catabolism, possibly during diving. Oxidative metabolism in P. sextuberculata appears to be designed for the use of lipids, amino acids and ketone bodies. The maximal activities of 3-hydroxyacyl-CoA dehydrogenase, malate dehydrogenase, glutamine dehydrogenase, alanine aminotransferase and succinyl-CoA keto transferase display high aerobic potential, especially in muscle and liver tissues of this species. Although amino acids and ketone bodies may be important fuels for oxidative metabolism, carbohydrates and lipids are the major fuels used by P. expansa and P. unifilis. Our results are consistent with the food habits and lifestyle of Amazonian freshwater turtles. The metabolic design, based on enzyme activities, suggests that hatchlings of P. unifilis and P. expansa are predominately herbivorous, whereas P. sextuberculata rely on a mixed diet of animal matter and vegetation.

  15. Biochemical fractionation and cellular distribution of americium and plutonium in the biomass of freshwater macrophytes

    International Nuclear Information System (INIS)

    Zotina, T.A.; Kalacheva, G.S.; Bolsunovsky, A.Ya.

    2011-01-01

    Accumulation of americium ( 241 Am) and plutonium ( 238,242 Pu) and their distribution in cell compartments and biochemical components of the biomass of freshwater aquatic plants Elodea canadensis, Ceratophyllum demersum and Myrioplyllum spicatum and aquatic moss Fontinalis antipyretica have been investigated in laboratory experiments. Americium and plutonium taken up from water by Elodea canadensis apical shoots were mainly absorbed by structural components of plant cells (90% for 241 Am; 89% for 238 Pu and 82-87% for 242 Pu). About 10-18% of isotope activity was recorded in the cytosol fraction. The major concentration (76-92%) of americium was bound to cell wall cellulose-like polysaccharides of Elodea canadensis, Myriophyllum spicatum, Ceratophyllum demersum and Fontinalis antipyretica, 8-24% of americium activity was registered in the fraction of proteins and carbohydrates, and just a minor concentration (<1%) in the lipid fraction. The distribution of plutonium in the biomass fractions of Elodea was similar to that of americium. Hence, americium and plutonium had the highest affinity to cellulose-like polysaccharides of cell walls of freshwater submerged macrophytes. (author)

  16. Freshwater fish Fauna and Restock Fish Activities of Reservoir in the Dardanelles (Canakkale-Turkey

    Directory of Open Access Journals (Sweden)

    Hüseyin SASI

    2012-06-01

    Full Text Available Turkey has, with geographic location including Istanbul and Çanakkale straits the system, 178,000 km in length streams, 906,000 ha of natural lakes, and 411,800 ha of dam lakes, and 28,000 ha of ponds due to richness inland waters which include freshwater fish. The fingerling fish (fry were restocked approximately 250,000,000 in natural lakes, dam lakes and ponds for fisheries between years of 1979 and 2005. Canakkale has rich freshwater potential with 7 major rivers (Büyükdere, Karamenderes stream, Kavak brook, Kocacay stream, Sarıcay stream, Tuzla brook, Umurbey brook, 7 Dam Lakes (Atikhisar, Zeytinlikoy, Bayramic, Bakacak, Tayfur, Umurbey and Yenice-Gönen Dam lakes. In the studies, it has been determined that 15 fish species belonging to 6 families (Anguillidae, Atherinidae, Salmonidae, Cobitidae, Cyprinidae and Poecilidae can be found in reservoirs. Fish restocking of the activities of the reservoir until today approximately 1,120,000 (Cyprinus carpio L., 1758 is introduced. In this study, the activity of Canakkale province in the fish restocking and reservoir exploiting possibilities were discussed in view of reservoir fisheries potential which is used insufficiently today.

  17. Micronuclei and erythrocytic abnormalities frequencies of freshwater fishes: Establishing a baseline for health status

    Science.gov (United States)

    Sousa, Debora Batista Pinheiro; Torres, Audalio Rebelo; Oliveira, Suelen Rosana Sampaio; Castro, Jonatas da Silva; Neta, Raimunda Nonata Fortes Carvalho

    2017-11-01

    Majority papers shows that micronucleus test and erythrocyte abnormalities are excellent tools such as tools for monitor fish health and the level of impact in aquatic ecosystems. Nevertheless, still do not know the baseline for those changes in freshwater fishes communities in the Brazilian Northeastern river. In this study, we show the level of basis of two species of freshwater fishes (Colossoma macropomum -tambaqui and Oreochromis niloticus - tilápia) with the aim of establish levels of background these species. The animals were collected from Ambude river in the protected area and blood collected from all fish for analysis. Erythrocyte indices—mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC)—were calculated. Blood samples from all fish were examined for micronuclear changes after Giemsa staining. Micronuclei were found in fish from from Ambude River. The baseline values determined for tambaqui was (micronuclei= 0.0071±0.0026; MCV=0.0073±0.0037; MCHV=0.0071±0.0024) and tilapia (micronuclei= 0.0061±0.0026; MCV=0.0037±0.0017; MCHV=0.056±0.0036). We belive that, we propose using the genotoxic approach for estimating fish health status as the technique allows examination in locus of live fish without the need for animal euthanasia. Besides, baseline level can be to establish levels of background and patterns to pathological and physiological research of these species in future biomonitoring programs.

  18. Hydrogeology and geochemistry of the freshwater lens on Roi Namur atoll, the Republic of the Marshall Islands

    Science.gov (United States)

    Swarzenski, P. W.

    2015-12-01

    More than 90% of the world's ~400 larger atoll islands are located in the Pacific and Indian Oceans and are inhabited by ~ 3/4 million people. As ground elevations of these atolls rarely exceed a few meters above mean sea level, atoll communities must rely precariously on finite resources, including fresh water and land. When demand for water exceeds precipitation rates, fresh groundwater may provide an additional, albeit also limited resource. The shape and size of this freshwater lens is controlled by precipitation, infiltration, discharge, and groundwater pumping, as well as hydrogeologic characteristics of the aquifer, and climate. Small atoll islands like Roi Namur on Kwajalein perhaps best illustrate the strong interdependence of the islet's depositional history and geochemical transformations that occur within the shallow aquifer and its host rock. This study utilized electrical resistivity tomography (ERT) to define the position of the freshwater lens above underlying seawater and to examine scales of freshwater /saltwater mixing. Time series Rn-222 measurements were used to evaluate groundwater discharge rates to the coastal waters, and a suite of groundwater geochemical tracers, including select nutrients, trace elements, and water isotopes, were used to develop a better understanding of how the fresh water lens will likely to respond to external perturbations, such as managed recharge, and the inevitability of future marine over wash events that will be become more frequent and severe under expected sea level rise.

  19. Systems-level modeling the effects of arsenic exposure with sequential pulsed and fluctuating patterns for tilapia and freshwater clam

    International Nuclear Information System (INIS)

    Chen, W.-Y.; Tsai, J.-W.; Ju, Y.-R.; Liao, C.-M.

    2010-01-01

    The purpose of this paper was to use quantitative systems-level approach employing biotic ligand model based threshold damage model to examine physiological responses of tilapia and freshwater clam to sequential pulsed and fluctuating arsenic concentrations. We tested present model and triggering mechanisms by carrying out a series of modeling experiments where we used periodic pulses and sine-wave as featured exposures. Our results indicate that changes in the dominant frequencies and pulse timing can shift the safe rate distributions for tilapia, but not for that of freshwater clam. We found that tilapia increase bioenergetic costs to maintain the acclimation during pulsed and sine-wave exposures. Our ability to predict the consequences of physiological variation under time-varying exposure patterns has also implications for optimizing species growing, cultivation strategies, and risk assessment in realistic situations. - Systems-level modeling the pulsed and fluctuating arsenic exposures.

  20. Systems-level modeling the effects of arsenic exposure with sequential pulsed and fluctuating patterns for tilapia and freshwater clam

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W.-Y. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Tsai, J.-W. [Institute of Ecology and Evolutionary Ecology, China Medical University, Taichung 40402, Taiwan (China); Ju, Y.-R. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Liao, C.-M., E-mail: cmliao@ntu.edu.t [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2010-05-15

    The purpose of this paper was to use quantitative systems-level approach employing biotic ligand model based threshold damage model to examine physiological responses of tilapia and freshwater clam to sequential pulsed and fluctuating arsenic concentrations. We tested present model and triggering mechanisms by carrying out a series of modeling experiments where we used periodic pulses and sine-wave as featured exposures. Our results indicate that changes in the dominant frequencies and pulse timing can shift the safe rate distributions for tilapia, but not for that of freshwater clam. We found that tilapia increase bioenergetic costs to maintain the acclimation during pulsed and sine-wave exposures. Our ability to predict the consequences of physiological variation under time-varying exposure patterns has also implications for optimizing species growing, cultivation strategies, and risk assessment in realistic situations. - Systems-level modeling the pulsed and fluctuating arsenic exposures.

  1. Temperature and irradiance influences on cadmium and zinc uptake and toxicity in a freshwater cyanobacterium, Microcystis aeruginosa

    International Nuclear Information System (INIS)

    Zeng Jin; Wang Wenxiong

    2011-01-01

    Highlights: → This study is the first to study the influences of temperature and light irradiance, two critical factors for the occurrence of cyanobacterial blooms, on metal uptake, subcellular distribution, and toxicity in a freshwater cyanobacterium commonly blooming in eutrophic lakes. → With increasing metal exposure, both cellular growth rate and photosynthesis became more sensitive to metal toxicity under elevated irradiance and temperature, primarily as a result of increased uptake and accumulation. → Cd in the metal rich granule faction increased under Cd exposure, suggesting that MRG may partially detoxify Cd in the cyanobacterial cells. → This study implies that temperature and irradiance may influence the chemical cycling of metals during cyanobacterial blooming in eutrophic freshwater ecosystems. - Abstract: Temperature and light irradiance are important factors affecting the occurrence of cyanobacterial blooms. In this study, we examined the influences of different temperatures (15, 24, and 30 ° C ) and irradiances (18, 32, and 55 μmol photons m -2 s -1 ) on the uptake and toxicity of cadmium (Cd) and zinc (Zn) in a freshwater cyanobacterium Microcystis aeruginosa. The subcellular distribution of Cd and Zn was analyzed. Enhanced growth rates were observed for the cyanobacterial cells incubated at higher temperature or irradiance conditions with lower metal concentrations. With increasing ambient Cd or Zn concentrations, both cellular growth rate and photosynthesis were significantly inhibited at elevated irradiance conditions. The observed increase in Cd and Zn toxicity might be attributed to the enhanced metal uptake and accumulation in Microcystis. Based on the intracellular Cd concentration, the 50% inhibition concentration (IC 50 ) values were higher at the higher temperature or irradiance treatment. The subcellular distribution demonstrated that Cd in the metal rich granule (MRG) faction increased with elevated [Cd 2+ ] concentration

  2. Hydrology and Ecology of Freshwater Wetlands in Central Florida - A Primer

    Science.gov (United States)

    Haag, Kim H.; Lee, Terrie M.

    2010-01-01

    how wetlands are affected by human activities. Freshwater wetlands are unique and complex ecosystems defined by characteristic properties. Wetlands usually have standing water during at least part of the year, although water depths can vary from a few inches to as much as several feet from one wetland to another. The hydrologic behavior of wetlands is influenced by drainage basin characteristics, as well as by natural variations in climate. Wetlands in central Florida (especially forested wetlands) often have acidic waters that are darkly stained from organic substances released by decomposing leaves and other plant material. Wetlands are characterized by biogeochemical cycles in which vital elements such as carbon, nitrogen, phosphorus, and others are transformed as they move between wetland soils and sediments, the open water, and the atmosphere. Wetlands are populated with plants that can thrive under conditions of saturated soils and low dissolved-oxygen concentrations. The bottoms of many wetlands, especially marshes, are covered with decayed plant material that can accumulate over time to form brown peat or black muck soils. Wetlands are inhabited by animals that need standing water to complete some or all of their life cycles, and they also provide periodic food, water, and shelter for many other animals that spend most of their lives on dry land. The complex and interrelated components of wetlands directly affect one another and there are numerous feedback mechanisms.

  3. Trait-based prediction of extinction risk of small-bodied freshwater fishes.

    Science.gov (United States)

    Kopf, R Keller; Shaw, Casey; Humphries, Paul

    2017-06-01

    ,000 unclassified freshwater fishes, especially those under threat from proposed dam construction in the world's most biodiverse river basins. © 2016 Society for Conservation Biology.

  4. Factors influencing tropical island freshwater fishes:Species, status, and management implications in puerto rico [Factores que influencian a los peces tropicales de agua dulce: Especies, estado actual e implicaciones para el manejo en Puerto Rico

    Science.gov (United States)

    Wesley, Neal J.; Lilyestrom, Craig G.; Kwak, T.J.

    2009-01-01

    Anthropogenic effects including river regulation, watershed development, contamination, and fish introductions have substantially affected the majority of freshwater habitats in Europe and North America. This pattern of resource development and degradation is widespread in the tropics, and often little is known about the resources before they are lost. This article describes the freshwater resources of Puerto Rico and identifies factors that threaten conservation of native fishes. The fishes found in freshwater habitats of Puerto Rico represent a moderately diverse assemblage composed of 14 orders, 29 families, and 82 species. There are fewer than 10 species of native peripherally-freshwater fish that require a link to marine systems. Introductions of nonindigenous species have greatly expanded fish diversity in freshwater systems, and native estuarine and marine species (18 families) also commonly enter lowland rivers and brackish lagoons. Environmental alterations, including land use and development, stream channelization, pollution, and the impoundment of rivers, combined with nonnative species introductions threaten the health and sustainability of aquatic resources in Puerto Rico. Six principal areas for attention that are important influences on the current and future status of the freshwater fish resources of Puerto Rico are identified and discussed.

  5. Effect of sunlight on the survival of pathogenic E. coli in freshwater and sea water

    DEFF Research Database (Denmark)

    Surendraraj, Alagarsamy; Farvin, Sabeena; Thampuran, N.

    2011-01-01

    An enteropathogenic group of E. coli are the emerging category of pathogen of public health significance. Several recent pathogenic E. coli outbreaks are associated with drinking water. Aquaculture, the fast emerging food production sector also poses a pathogenic EHEC outbreak risk, as it regularly...... uses cow dung, a reservoir of this organism. Hence, a experiment was set up to study the duration of survival of pathogenic E. coli under sunlight and darkness. Eight pathogenic E. coli isolates from clinical (EPEC, ETEC, EHEC, EAEC), veterinary (CTE3, CTE4) and environmental sources (ASHE3, Rao II......) were studied for their survival under sunlight and darkness in fresh water and seawater. Effect of direct sunlight on the viable but nonculturable (VBNC) state of cultures was also studied. The results of the study indicated a distinct pattern between freshwater system and seawater system. Pathogenic E...

  6. Major Sport Venues

    Data.gov (United States)

    Department of Homeland Security — The Major Public Venues dataset is composed of facilities that host events for the National Association for Stock Car Auto Racing, Indy Racing League, Major League...

  7. Major Depression Among Adults

    Science.gov (United States)

    ... Depressive Episode Among Adolescents Data Sources Share Major Depression Definitions Major depression is one of the most ... Bethesda, MD 20892-9663 Follow Us Facebook Twitter YouTube Google Plus NIMH Newsletter NIMH RSS Feed NIMH ...

  8. Inducing the Alternative Oxidase Forms Part of the Molecular Strategy of Anoxic Survival in Freshwater Bivalves

    Directory of Open Access Journals (Sweden)

    Maria S. Yusseppone

    2018-02-01

    Full Text Available Hypoxia in freshwater ecosystems is spreading as a consequence of global change, including pollution and eutrophication. In the Patagonian Andes, a decline in precipitation causes reduced lake water volumes and stagnant conditions that limit oxygen transport and exacerbate hypoxia below the upper mixed layer. We analyzed the molecular and biochemical response of the North Patagonian bivalve Diplodon chilensis after 10 days of experimental anoxia (<0.2 mg O2/L, hypoxia (2 mg O2/L, and normoxia (9 mg O2/L. Specifically, we investigated the expression of an alternative oxidase (AOX pathway assumed to shortcut the regular mitochondrial electron transport system (ETS during metabolic rate depression (MRD in hypoxia-tolerant invertebrates. Whereas, the AOX system was strongly upregulated during anoxia in gills, ETS activities and energy mobilization decreased [less transcription of glycogen phosphorylase (GlyP and succinate dehydrogenase (SDH in gills and mantle]. Accumulation of succinate and induction of malate dehydrogenase (MDH activity could indicate activation of anaerobic mitochondrial pathways to support anoxic survival in D. chilensis. Oxidative stress [protein carbonylation, glutathione peroxidase (GPx expression] and apoptotic intensity (caspase 3/7 activity decreased, whereas an unfolded protein response (HSP90 was induced under anoxia. This is the first clear evidence of the concerted regulation of the AOX and ETS genes in a hypoxia-tolerant freshwater bivalve and yet another example that exposure to hypoxia and anoxia is not necessarily accompanied by oxidative stress in hypoxia-tolerant mollusks.

  9. Inducing the Alternative Oxidase Forms Part of the Molecular Strategy of Anoxic Survival in Freshwater Bivalves

    Science.gov (United States)

    Yusseppone, Maria S.; Rocchetta, Iara; Sabatini, Sebastian E.; Luquet, Carlos M.; Ríos de Molina, Maria del Carmen; Held, Christoph; Abele, Doris

    2018-01-01

    Hypoxia in freshwater ecosystems is spreading as a consequence of global change, including pollution and eutrophication. In the Patagonian Andes, a decline in precipitation causes reduced lake water volumes and stagnant conditions that limit oxygen transport and exacerbate hypoxia below the upper mixed layer. We analyzed the molecular and biochemical response of the North Patagonian bivalve Diplodon chilensis after 10 days of experimental anoxia (<0.2 mg O2/L), hypoxia (2 mg O2/L), and normoxia (9 mg O2/L). Specifically, we investigated the expression of an alternative oxidase (AOX) pathway assumed to shortcut the regular mitochondrial electron transport system (ETS) during metabolic rate depression (MRD) in hypoxia-tolerant invertebrates. Whereas, the AOX system was strongly upregulated during anoxia in gills, ETS activities and energy mobilization decreased [less transcription of glycogen phosphorylase (GlyP) and succinate dehydrogenase (SDH) in gills and mantle]. Accumulation of succinate and induction of malate dehydrogenase (MDH) activity could indicate activation of anaerobic mitochondrial pathways to support anoxic survival in D. chilensis. Oxidative stress [protein carbonylation, glutathione peroxidase (GPx) expression] and apoptotic intensity (caspase 3/7 activity) decreased, whereas an unfolded protein response (HSP90) was induced under anoxia. This is the first clear evidence of the concerted regulation of the AOX and ETS genes in a hypoxia-tolerant freshwater bivalve and yet another example that exposure to hypoxia and anoxia is not necessarily accompanied by oxidative stress in hypoxia-tolerant mollusks. PMID:29527172

  10. Predictive capabilities of the specific activity hypothesis for Cs and Zn in freshwater systems

    International Nuclear Information System (INIS)

    Seelye, J.G.

    1975-01-01

    Predictions of radioisotope concentrations in components of aquatic systems have been attempted using the specific activity concept, an approach that seems theoretically sound. A comprehensive examination of the specific activities of 134 Cs and 65 Zn in the components of a freshwater system, over a 10 month period, was conducted to evaluate the specific activity hypothesis under applied conditions. This study was designed to provide comparisons of predicted and observed specific activities and to test the equivalence of specific activities between all components of the system. One dose of radioisotopes was added to the system in this study and even after 10 months these radioisotopes were not distributed similarly to the stable isotopes. This suggests that the time necessary to reach a specific activity equilibrium might be a matter of years rather than months. More importantly, in natural systems, where the radioisotope addition is continuous a specific activity equilibrium may never be achieved. These things plus the non-conservative nature of the 134 Cs and 65 Zn predicted concentrations indicates that the use of the specific activity concept for predicting radioisotope concentrations of Cs and Zn in freshwater systems is questionable. A more rigorous approach must be used, considering isotope transfer rates between components and the complexity of the system. Problems with statistical comparisons of derived variables, such as specific activities, are discussed and were considered in interpreting the results of this study

  11. Governance conditions for adaptive freshwater management in the Vietnamese Mekong Delta

    Science.gov (United States)

    Ha, T. P.; Dieperink, Carel; Dang Tri, Van Pham; Otter, Henriëtte S.; Hoekstra, Piet

    2018-02-01

    The Vietnamese Mekong Delta (VMD) is a region of utmost importance to Vietnam's national food security. However, the availability of required freshwater resources (from both surface and groundwater sources) is currently under great threats due to dry season salinity intrusion, surface water pollution, and over-exploitation of groundwater. Global climate change, sea level rise, and upstream and in situ development activities may worsen the situation. Assuming that adaptive management could be a promising strategy to address the increasingly complex and unpredictable water-related problems in the VMD, we design and apply a framework to identify the extent to which the governance regime in this region exhibits conditions that are likely to promote adaptive freshwater management. Using both primary and secondary data, our analysis reveals that the prospects for adaptive water management in the study area are limited since several conditions were not present. We observe among others limitations in vertical and horizontal integration and public participation, restraints in knowledge and information sharing, inadequate policy development and implementation, and insufficient diversification of financial resources. Following our findings, we conclude the paper with recommendations both for national, regional and local policy interventions and for future research.

  12. Anthropogenic shift of planktonic food web structure in a coastal lagoon by freshwater flow regulation

    Science.gov (United States)

    Hemraj, Deevesh A.; Hossain, A.; Ye, Qifeng; Qin, Jian G.; Leterme, Sophie C.

    2017-03-01

    Anthropogenic modification of aquatic systems has diverse impacts on food web interactions and ecosystem states. To reverse the adverse effects of modified freshwater flow, adequate management of discharge is required, especially due to higher water requirements and abstractions for human use. Here, we look at the effects of anthropogenically controlled freshwater flow regimes on the planktonic food web of a Ramsar listed coastal lagoon that is under recovery from degradation. Our results show shifts in water quality and plankton community interactions associated to changes in water flow. These shifts in food web interactions represent modifications in habitat complexity and water quality. At high flow, phytoplankton-zooplankton interactions dominate the food web. Conversely, at low flow, bacteria, viruses and nano/picoplankton interactions are more dominant, with a substantial switch of the food web towards heterotrophy. This switch can be associated with excess organic matter loading, decomposition of dead organisms, and synergistic and antagonistic interactions. We suggest that a lower variability in flow amplitude could be beneficial for the long-term sustaining of water quality and food web interactions, while improving the ecosystem health of systems facing similar stresses as the Coorong.

  13. Potential impacts of leakage from deep CO2 geosequestration on overlying freshwater aquifers.

    Science.gov (United States)

    Little, Mark G; Jackson, Robert B

    2010-12-01

    Carbon Capture and Storage may use deep saline aquifers for CO(2) sequestration, but small CO(2) leakage could pose a risk to overlying fresh groundwater. We performed laboratory incubations of CO(2) infiltration under oxidizing conditions for >300 days on samples from four freshwater aquifers to 1) understand how CO(2) leakage affects freshwater quality; 2) develop selection criteria for deep sequestration sites based on inorganic metal contamination caused by CO(2) leaks to shallow aquifers; and 3) identify geochemical signatures for early detection criteria. After exposure to CO(2), water pH declines of 1-2 units were apparent in all aquifer samples. CO(2) caused concentrations of the alkali and alkaline earths and manganese, cobalt, nickel, and iron to increase by more than 2 orders of magnitude. Potentially dangerous uranium and barium increased throughout the entire experiment in some samples. Solid-phase metal mobility, carbonate buffering capacity, and redox state in the shallow overlying aquifers influence the impact of CO(2) leakage and should be considered when selecting deep geosequestration sites. Manganese, iron, calcium, and pH could be used as geochemical markers of a CO(2) leak, as their concentrations increase within 2 weeks of exposure to CO(2).

  14. Colloidal stability of carbonate-coated silver nanoparticles in synthetic and natural freshwater.

    Science.gov (United States)

    Piccapietra, Flavio; Sigg, Laura; Behra, Renata

    2012-01-17

    To gain important information on fate, mobility, and bioavailability of silver nanoparticles (AgNP) in aquatic systems, the influence of pH, ionic strength, and humic substances on the stability of carbonate-coated AgNP (average diameter 29 nm) was systematically investigated in 10 mM carbonate and 10 mM MOPS buffer, and in filtered natural freshwater. Changes in the physicochemical properties of AgNP were measured using nanoparticle tracking analysis, dynamic light scattering, and ultraviolet-visible spectroscopy. According to the pH-dependent carbonate speciation, below pH 4 the negatively charged surface of AgNP became positive and increased agglomeration was observed. Electrolyte concentrations above 2 mM Ca(2+) and 100 mM Na(+) enhanced AgNP agglomeration in the synthetic media. In the considered concentration range of humic substances, no relevant changes in the AgNP agglomeration state were measured. Agglomeration of AgNP exposed in filtered natural freshwater was observed to be primarily controlled by the electrolyte type and concentration. Moreover, agglomerated AgNP were still detected after 7 days of exposure. Consequently, slow sedimentation and high mobility of agglomerated AgNP could be expected under the considered natural conditions. A critical evaluation of the different methods used is presented as well.

  15. Transport and degradation of dissolved organic matter and associated freshwater pathways in the Laptev Sea (Siberian Arctic)

    Science.gov (United States)

    Hoelemann, Jens; Janout, Markus; Koch, Boris; Bauch, Dorothea; Hellmann, Sebastian; Eulenburg, Antje; Heim, Birgit; Kassens, Heidemarie; Timokhov, leonid

    2016-04-01

    The Siberian shelves are seasonally ice-covered and characterized by large freshwater runoff rates from some of the largest rivers on earth. These rivers also provide a considerable amount of dissolved organic carbon (DOC) to the Arctic Ocean. With an annual load of about 6 Tg DOC a-1 the Lena River contributes nearly 20 percent of the annual DOC discharge to the Arctic Ocean. We present a comprehensive dataset collected during multiple Laptev Sea expeditions carried out in spring, summer and fall (2010-15) in order to explore the processes controlling the dispersal and degradation of DOM during the river water's passage across the shelf. Our investigations are focused on CDOM (Colored Dissolved Organic Matter), which resembles the DOC concentration, interacts with solar radiation and forms a major fraction of the organic matter pool. Our results show an inverse correlation between salinity and CDOM, which emphasizes its terrigenous source. Further, the spectral slope of CDOM absorption indicates that photochemical bleaching is the main process that reduces the CDOM absorption (~ 20%) in freshwater along its transport across the shelf. The distribution of the Lena river water is primarily controlled by winds in summer. During summers with easterly or southerly winds, the plume remains on the central and northern Laptev shelf, and is available for export into the Arctic Basin. The CDOM-rich river water increases the absorption of solar radiation and enhances warming of a shallow surface layer. This emphasizes the importance of CDOM for sea surface temperatures and lateral ice melt on the shelf and adjacent basin. DOC concentrations in freshwater vary seasonally and become larger with increasing discharge. Our data indicate that the CDOM concentrations are highest during the freshet when landfast ice is still present. Subsequent mixing with local sea ice meltwater lowers CDOM to values that are characteristic for the Lena freshwater during the rest of the year.

  16. Freshwater Biogeography and Limnological Evolution of the Tibetan Plateau - Insights from a Plateau-Wide Distributed Gastropod Taxon (Radix spp.)

    Science.gov (United States)

    von Oheimb, Parm Viktor; Albrecht, Christian; Riedel, Frank; Du, Lina; Yang, Junxing; Aldridge, David C.; Bößneck, Ulrich; Zhang, Hucai; Wilke, Thomas

    2011-01-01

    Background The Tibetan Plateau is not only the highest and largest plateau on earth; it is also home to numerous freshwater lakes potentially harbouring endemic faunal elements. As it remains largely unknown whether these lakes have continuously existed during the Last Glacial Maximum (LGM), questions arise as to whether taxa have been able to exist on the plateau since before the latest Pleistocene, from where and how often the plateau was colonized, and by which mechanisms organisms conquered remote high altitude lentic freshwater systems. In this study, species of the plateau-wide distributed freshwater gastropod genus Radix are used to answer these biogeographical questions. Methodology/Principal Findings Based on a broad spatial sampling of Radix spp. on the Tibetan Plateau, and phylogenetic analyses of mtDNA sequence data, three probably endemic and one widespread major Radix clade could be identified on the plateau. Two of the endemic clades show a remarkably high genetic diversity, indicating a relatively great phylogenetic age. Phylogeographical analyses of individuals belonging to the most widely distributed clade indicate that intra-plateau distribution cannot be explained by drainage-related dispersal alone. Conclusions/Significance Our study reveals that Radix spp. persisted throughout the LGM on the Tibetan Plateau. Therefore, we assume the continuous existence of suitable water bodies during that time. The extant Radix diversity on the plateau might have been caused by multiple colonization events combined with a relatively long intra-plateau evolution. At least one colonization event has a Palaearctic origin. In contrast to freshwater fishes, passive dispersal, probably by water birds, might be an important mechanism for conquering remote areas on the plateau. Patterns found in Radix spp. are shared with some terrestrial plateau taxa, indicating that Radix may be a suitable model taxon for inferring general patterns of biotic origin, dispersal and

  17. Multilocus Phylogeny of the Afrotropical Freshwater Crab Fauna Reveals Historical Drainage Connectivity and Transoceanic Dispersal Since the Eocene.

    Science.gov (United States)

    Daniels, Savel R; Phiri, Ethel E; Klaus, Sebastian; Albrecht, Christian; Cumberlidge, Neil

    2015-07-01

    Phylogenetic reconstruction, divergence time estimations and ancestral range estimation were undertaken for 66% of the Afrotropical freshwater crab fauna (Potamonautidae) based on four partial DNA loci (12S rRNA, 16S rRNA, cytochrome oxidase one [COI], and histone 3). The present study represents the most comprehensive taxonomic sampling of any freshwater crab family globally, and explores the impact of paleodrainage interconnectivity on cladogenesis among freshwater crabs. Phylogenetic analyses of the total evidence data using maximum-likelihood (ML), maximum parsimony (MP), and Bayesian inference (BI) produced a robust statistically well-supported tree topology that reaffirmed the monophyly of the Afrotropical freshwater crab fauna. The estimated divergence times suggest that the Afrotropical Potamonautidae diverged during the Eocene. Cladogenesis within and among several genera occurred predominantly during the Miocene, which was associated with major tectonic and climatic ameliorations throughout the region. Paleodrainage connectivity was observed with specimens from the Nilo-Sudan and East African coast proving to be sister to specimens from the Upper Guinea Forests in West Africa. In addition, we observed strong sister taxon affinity between specimens from East Africa and the Congo basin, including specimens from Lake Tanganyika, while the southern African fauna was retrieved as sister to the Angolan taxa. Within the East African clade we observed two independent transoceanic dispersal events, one to the Seychelles Archipelago and a second to Madagascar, while we observe a single transoceanic dispersal event from West Africa to São Tomé. The ancestral area estimation suggested a West African/East African ancestral range for the family with multiple dispersal events between southern Africa and East Africa, and between East Africa and Central Africa The taxonomic implications of our results are discussed in light of the widespread paraphyly evident among a

  18. Stenting of major airway constriction

    International Nuclear Information System (INIS)

    Wu Xiaomei

    2002-01-01

    Objective: To investigate the correlated issues in the stenting treatment of major airway constriction. Methods: Nineteen cases of major airway stenting procedure were studied retrospectively. The clinical choice of stents of different advantages or deficiencies were discussed. The importance of intravenous anesthesia supporting, life-parameters monitoring during the procedures and the prevention of complications were analysed. Results: Under intravenous and local anesthesia, 19 Wallstents had been successively placed and relieved 19 cases of major airway constrictions due to malignant or benign diseases (15 of tumors, 3 of tuberculosis, 1 of tracheomalacia). Intravenous anesthesia and life-parameters monitoring had made the procedures more safe and precise. Conclusions: Major airway stenting is an reliable method for relieving tracheobronchial stenosis; and intravenous anesthesia supporting and life-parameters monitoring guarantee the satisfactions of procedures

  19. The potential of freshwater macroalgae as a biofuels feedstock and the influence of nutrient availability on freshwater macroalgal biomass production

    Science.gov (United States)

    Yun, Jin-Ho

    Extensive efforts have been made to evaluate the potential of microalgae as a biofuel feedstock during the past 4-5 decades. However, filamentous freshwater macroalgae have numerous characteristics that favor their potential use as an alternative algal feedstock for biofuels production. Freshwater macroalgae exhibit high rates of areal productivity, and their tendency to form dense floating mats on the water surface imply significant reductions in harvesting and dewater costs compared to microalgae. In Chapter 1, I reviewed the published literature on the elemental composition and energy content of five genera of freshwater macroalgae. This review suggested that freshwater macroalgae compare favorably with traditional bio-based energy sources, including terrestrial residues, wood, and coal. In addition, I performed a semi-continuous culture experiment using the common Chlorophyte genus Oedogonium to investigate whether nutrient availability can influence its higher heating value (HHV), productivity, and proximate analysis. The experimental study suggested that the most nutrient-limited growth conditions resulted in a significant increase in the HHV of the Oedogonium biomass (14.4 MJ/kg to 16.1 MJ/kg). Although there was no significant difference in productivity between the treatments, the average dry weight productivity of Oedogonium (3.37 g/m2/day) was found to be much higher than is achievable with common terrestrial plant crops. Although filamentous freshwater macroalgae, therefore, have significant potential as a renewable source of bioenergy, the ultimate success of freshwater macroalgae as a biofuel feedstock will depend upon the ability to produce biomass at the commercial-scale in a cost-effective and sustainable manner. Aquatic ecology can play an important role to achieve the scale-up of algal crop production by informing the supply rates of nutrients to the cultivation systems, and by helping to create adaptive production systems that are resilient to

  20. Ecotoxicity of engineered nanoparticles to freshwater organisms

    DEFF Research Database (Denmark)

    Hartmann, Nanna Isabella Bloch

    through practical lab-based studies as well as literature studies. The process of testing nanoparticles in aquatic ecotoxicity tests has been as important in the project approach as the test outcomes. Applied test methods have included acute and chronic toxicity tests as well as bioaccumulation studies......A large variety of societal benefits are expected from the development and use of engineered nanoparticles. At present, the majority of ‘nano-products’ put on the market can be classified as consumer products, whereas future applications are expected to have more widespread and societal benefits...... soluble chemicals, many aspects of commonly used test methods for evaluation of potential adverse environmental effects make their applicability to nanoparticles questionable. For this reason the overarching aim of this PhD project has been to acquire information, which can be disseminated and applied...

  1. Context-dependent interactions and the regulation of species richness in freshwater fish

    Science.gov (United States)

    MacDougall, Andrew S.; Harvey, Eric; McCune, Jenny L.; Nilsson, Karin A.; Bennett, Joseph; Firn, Jennifer; Bartley, Timothy; Grace, James B.; Kelly, Jocelyn; Tunney, Tyler D.; McMeans, Bailey; Matsuzaki, Shin-Ichiro S.; Kadoya, Taku; Esch, Ellen; Cazelles, Kevin; Lester, Nigel; McCann, Kevin S.

    2018-01-01

    Species richness is regulated by a complex network of scale-dependent processes. This complexity can obscure the influence of limiting species interactions, making it difficult to determine if abiotic or biotic drivers are more predominant regulators of richness. Using integrative modeling of freshwater fish richness from 721 lakes along an 11olatitudinal gradient, we find negative interactions to be a relatively minor independent predictor of species richness in lakes despite the widespread presence of predators. Instead, interaction effects, when detectable among major functional groups and 231 species pairs, were strong, often positive, but contextually dependent on environment. These results are consistent with the idea that negative interactions internally structure lake communities but do not consistently ‘scale-up’ to regulate richness independently of the environment. The importance of environment for interaction outcomes and its role in the regulation of species richness highlights the potential sensitivity of fish communities to the environmental changes affecting lakes globally.

  2. Sampling in freshwater environments: Suspended particle traps and variability in the final data

    International Nuclear Information System (INIS)

    Barbizzi, Sabrina; Pati, Alessandra

    2008-01-01

    This paper reports one practical method to estimate the measurement uncertainty including sampling, derived by the approach implemented by Ramsey for soil investigations. The methodology has been applied to estimate the measurements uncertainty (sampling and analyses) of 137 Cs activity concentration (Bq kg -1 ) and total carbon content (%) in suspended particle sampling in a freshwater ecosystem. Uncertainty estimates for between locations, sampling and analysis components have been evaluated. For the considered measurands, the relative expanded measurement uncertainties are 12.3% for 137 Cs and 4.5% for total carbon. For 137 Cs, the measurement (sampling+analysis) variance gives the major contribution to the total variance, while for total carbon the spatial variance is the dominant contributor to the total variance. The limitations and advantages of this basic method are discussed

  3. Bioaccumulation and partitioning of cadmium within the freshwater mussel Dreissena polymorpha Pallas

    International Nuclear Information System (INIS)

    Bias, R.; Karbe, L.

    1985-01-01

    Kinetics of uptake, partitioning and elimination of cadmium were investigated in experimental studies with the freshwater mussel, Dreissena polymorpha. 109 Cd and 115 Cd were used as tracers. Shells, soft parts and body fluid of the mussel exhibited considerable differences in accumulation and elimination. Accumulation factors up to more than 70,000 were calculated for the periostracum, whereas accumulation factors for the whole mussels ranging up to 3,000 were calculated. The shells bound a great deal of cadmium, but only loosely, and the metal could be readily eliminated after transfer to uncontaminated water. In contrast, no significant amounts of the cadmium incorporated in the soft parts were eliminated. The results indicate that the major portion of cadmium in the soft parts is strongly bound and cannot be eliminated by exchange processes. (author)

  4. Chemical speciation and bioavailability of transuranics for a freshwater snail (Lymnaea stagnalis L.)

    International Nuclear Information System (INIS)

    Thiels, G.M.; Murray, C.N.; Rade, J.

    1981-01-01

    It is now becoming clear that the determination of the physico-chemical forms of transuranic elements is an important step in assessing their behaviour at very low environmental levels. Data from both simulated environmental systems as well as in-situ investigations have shown the necessity of understanding the source term of contamination, which probably plays a major role in the long-term distribution of these elements. In the present paper an experimental procedure is outlined, which allows a more extensive investigation into some aspects of the biogeochemical behaviour of two transuranics: 237 Pu and 241 Am. Two chemical methods were applied to a study of the freshwater snail Lymnaea stagnalis L.. Data were obtained on the uptake and retention patterns of different oxidation states of 237 Pu and 241 Am at the organ and cellular levels of the pond snail. An attempt was made to relate the environmental chemistry of both radionuclides to the fixation in L. stagnalis. (author)

  5. Sampling in freshwater environments: suspended particle traps and variability in the final data.

    Science.gov (United States)

    Barbizzi, Sabrina; Pati, Alessandra

    2008-11-01

    This paper reports one practical method to estimate the measurement uncertainty including sampling, derived by the approach implemented by Ramsey for soil investigations. The methodology has been applied to estimate the measurements uncertainty (sampling and analyses) of (137)Cs activity concentration (Bq kg(-1)) and total carbon content (%) in suspended particle sampling in a freshwater ecosystem. Uncertainty estimates for between locations, sampling and analysis components have been evaluated. For the considered measurands, the relative expanded measurement uncertainties are 12.3% for (137)Cs and 4.5% for total carbon. For (137)Cs, the measurement (sampling+analysis) variance gives the major contribution to the total variance, while for total carbon the spatial variance is the dominant contributor to the total variance. The limitations and advantages of this basic method are discussed.

  6. Platinum uptake by the freshwater isopod Asellus Aquaticus in urban rivers

    Energy Technology Data Exchange (ETDEWEB)

    Rauch, S.; Morrison, G.M. [Department of Sanitary Engineering, Chalmers University of Technology, S-412 96 Goeteborg (Sweden)

    1999-09-01

    Platinum has been increasing in the environment as a result of emissions from catalytic converters. The platinum emitted is principally located in the vicinity of roads but might be transported to urban rivers through highway and urban run-off water. Platinum concentrations in the freshwater isopod Asellus aquaticus were measured for two urban rivers and a stormwater detention pond. Concentrations ranged from 0.04 to 12.4 {mu}g g{sup -1} for direct analysis and from 0.16 to 4.5 {mu}g g{sup -1} after depuration. Analyses of water, pore water and sediments indicate that platinum in urban rivers is mostly found in the sediments and these provide the major contribution of platinum to Asellus aquaticus. Exposure experiments showed the importance of platinum speciation for uptake.

  7. Differential effects of P25 TiO{sub 2} nanoparticles on freshwater green microalgae: Chlorella and Scenedesmus species

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Rajdeep; Parashar, Abhinav; Bhuvaneshwari, M.; Chandrasekaran, N.; Mukherjee, Amitava, E-mail: amit.mookerjea@gmail.com

    2016-07-15

    Highlights: • Differential effects of P25 TiO{sub 2} NPs on Chlorella and Scenedesmus. • Concentration dependent effects in morphology and viability. • Increased ROS, catalase activity & LPO release with loss in SOD & GSH activity. • Dose dependent differential TiO{sub 2} NPs uptake affected by colonization of algae. - Abstract: P25 TiO{sub 2} nanoparticles majorly used in cosmetic products have well known detrimental effects towards the aquatic environment. In a freshwater ecosystem, Chlorella and Scenedesmus are among the most commonly found algal species frequently used to study the effects of metal oxide nanoparticles. A comparative study has been conducted herein to investigate differences in the toxic effects caused by these nanoparticles towards the two algae species. The three different concentrations of P25 TiO{sub 2} NPs (0.01, 0.1 & 1 μg/mL, i.e., 0.12, 1.25 and 12.52 μM) were selected to correlate surface water concentrations of the nanoparticles, and filtered and sterilized fresh water medium was used throughout this study. There was significant increase (p < 0.001) in hydrodynamic diameter of nanoparticles with respect to both, time (0, 24, 48 and 72 h) as well as concentration under all the exposure conditions. Although, significant dose-dependent morphological (surface area & biovolume) interspecies variations were not observed, it was evident at the highest concentration of exposure within individuals. At 1 μg/mL exposure concentration, a significant difference in toxicity was noted between Chlorella and Scenedesmus under only visible light (p < 0.001) and UVA (p < 0.01) irradiation conditions. The viability data were well supported by the results obtained for oxidative stress induced by NPs on the cells. At the highest exposure concentration, superoxide dismutase and reduced glutathione activities were assessed for both the algae under all the irradiation conditions. Increased catalase activity and LPO release complemented the cytotoxic

  8. Ecology of tidal freshwater forests in coastal deltaic Louisiana and northeastern South Carolina: Chapter 9

    Science.gov (United States)

    Conner, William H.; Krauss, Ken W.; Doyle, Thomas W.

    2007-01-01

    Tidal freshwater swamps in the southeastern United States are subjected to tidal hydroperiods ranging in amplitude from microtidal (forests, scrub-shrub stands, marsh, or open water but are less likely to convert mesotidal swamps. Changes to hydrological patterns tend to be more noticeable in Louisiana than do those in South Carolina.The majority of Louisiana’s coastal wetland forests are found in the Mississippi River deltaic plain region. Coastal wetland forests in the deltaic plain have been shaped by the sediments, water, and energy of the Mississippi River and its major distributaries. Baldcypress (Taxodium distichum [L.] L.C. Rich.) and water tupelo (Nyssa aquatica L.) are the primary tree species in the coastal swamp forests of Louisiana. Sites where these species grow usually hold water for most of the year; however, some of the more seaward sites were historically microtidal, especially where baldcypress currently dominates. In many other locations, baldcypress and water tupelo typically grow in more or less pure stands or as mixtures of the two with common associates such as black willow (Salix nigra Marsh.), red maple (Acer rubrum L.), water locust (Gleditsia aquatic Marsh.), overcup oak (Quercus lyrata Walt.), water hickory (Carya aquatica [Michx. f.] Nutt.), green ash (Fraxinus pennsylvanica Marsh.), pumpkin ash (F. profunda Bush.), and redbay (Persea borbonia [L.] Sprengel) (Brown and Montz 1986).The South Carolina coastal plain occupies about two-thirds of the state and rises gently to 150 m from the Atlantic Ocean up to the Piedmont plateau. Many rivers can be found in the Coastal Plain with swamps near the coast that extend inland along the rivers. Strongly tidal freshwater forests occur along the lower reaches of redwater rivers (Santee, Great Pee Dee, and Savannah) that arise in the mountains and along the numerous blackwater rivers (Ashepoo, Combahee, Cooper, and Waccamaw) that arise in the coastal regions. Most of the tidal freshwater forests

  9. Tributyltin bioaccumulation and toxic effects in freshwater gastropods Pomacea canaliculata after a chronic exposure: field and laboratory studies.

    Science.gov (United States)

    Martínez, María L; Piol, María N; Sbarbati Nudelman, Norma; Verrengia Guerrero, Noemí R

    2017-07-01

    Freshwater samples and gastropod mollusks (Pomacea canaliculata) were collected at 5 sampling stations located along the lower Río de la Plata basin, Argentina, to assess the extent of tributyltin (TBT) contamination. Determined data revealed the presence of TBT and some of its breakdown products (dibutyltin: DBT, and monobutyltin: MBT) in all freshwater samples and also in soft tissues of P. canaliculata gastropods. Chronic bioassays (6 months) were performed using female gastropods that had been reared under laboratory conditions and exposed to a similar TBT concentration than the value determined in freshwater samples (1 µg L -1 ). The aims of this study were to evaluate the extent of TBT accumulation, the tissue distribution, and the effects on selected biomarkers (activity of superoxide dismutasa: SOD, activity of catalase: CAT, levels of total glutathione: t-GSH, lipid peroxidation, and activity of acetylcholinesterase: AChE). Gonads presented the highest accumulation, followed by the cephalopedal region, albumin gland, and finally hepatopancreas. Both metabolites, DBT and MBT, were also found. All exposed female animals presented development of a penis reflecting the potential of TBT as an endocrine disrupting chemical for this gastropod species. Results on the selected biomarkers confirmed additional adverse effects induced by TBT. An increase in CAT activity and changes in t-GSH levels are indicative of alterations on the cellular redox status. The inhibition of AChE could reflect signs of neurotoxicity. Altogether, these results reveal a negative impact on the health of this gastropod population.

  10. Screening of freshwater fungi for decolorizing multiple synthetic dyes.

    Science.gov (United States)

    Yang, Panpan; Shi, Wenxiao; Wang, Hongkai; Liu, Hongmei

    The biodegradation of synthetic dyes by fungi is emerging as an effective and promising approach. In the present study, freshwater fungal strains isolated from submerged woods were screened for the decolorization of 7 synthetic dyes. Subsequently, 13 isolates with high decolorization capability were assessed in a liquid system; they belonged to 9 different fungal species. Several strains exhibited a highly effective decolorization of multiple types of dyes. New absorbance peaks appeared after the treatment with 3 fungal strains, which suggests that a biotransformation process occurred through fungal biodegradation. These results showed the unexploited and valuable capability of freshwater fungi for the treatment of dye-containing effluents. The ability of certain fungi to decolorize dyes is reported here for the first time. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  11. Sensitivity ranking for freshwater invertebrates towards hydrocarbon contaminants.

    Science.gov (United States)

    Gerner, Nadine V; Cailleaud, Kevin; Bassères, Anne; Liess, Matthias; Beketov, Mikhail A

    2017-11-01

    Hydrocarbons have an utmost economical importance but may also cause substantial ecological impacts due to accidents or inadequate transportation and use. Currently, freshwater biomonitoring methods lack an indicator that can unequivocally reflect the impacts caused by hydrocarbons while being independent from effects of other stressors. The aim of the present study was to develop a sensitivity ranking for freshwater invertebrates towards hydrocarbon contaminants, which can be used in hydrocarbon-specific bioindicators. We employed the Relative Sensitivity method and developed the sensitivity ranking S hydrocarbons based on literature ecotoxicological data supplemented with rapid and mesocosm test results. A first validation of the sensitivity ranking based on an earlier field study has been conducted and revealed the S hydrocarbons ranking to be promising for application in sensitivity based indicators. Thus, the first results indicate that the ranking can serve as the core component of future hydrocarbon-specific and sensitivity trait based bioindicators.

  12. Radionuclide data bases available for bioaccumulation factors for freshwater biota

    International Nuclear Information System (INIS)

    Blaylock, B.G.

    1982-01-01

    Aquatic models currently in use for dose assessment simulate the transfer of radionuclides in aquatic environments and the transfer to man. In these models the assimilation of a radionuclide in aquatic biota is calculated by using a simple empirical relationship known as the bioaccumulation factor (BF) to represent the transfer of the radionuclide from water to organism. The purpose of this article is to review data bases that are available for BFs for freshwater biota and to identify the uncertainties associated with them. Data bases for raidoisotopes of Co, Cs, C, H, I, Pu, Ra, Ru, Sr, and U are reviewed. With the exception of ruthenium and carbon, the review is restricted to BFs determined for natural freshwater systems. Factors influencing the variability of BFs are identified, uncertainties associated with the validation of BFs are discussed, and some guidance is given for collecting data and measuring BFs

  13. Trophic transfer of metal nanoparticles in freshwater ecosystems

    DEFF Research Database (Denmark)

    Tangaa, Stine Rosendal

    freshwater ecosystems range from a few ng/L in surface waters and up to mg/kg in sediments. Several studies have shown Ag ENPs to be toxic, bioaccumulative and harmful to aquatic biota within these concentration ranges. However, research on potential trophic transfer of Ag ENPs is limited. To investigate...... the aquatic ecosystems, Ag ENPs will undergo several transformation processes, ultimately leading to particles settling out of the water column. This will likely result in an increased concentration of ENPs in the sediment. In fact, predicted environmental concentrations of Ag ENPs in Danish and European...... freshwater food web. Future studies should concentrate on the internal distribution of Me-ENPs after uptake in both prey and predator, as this will increase the understanding of fate and effects of Me-ENPs on aquatic biota. Trophic transfer studies including more trophic levels, and higher pelagic organisms...

  14. Characterization of freshwater mosses as indicators of radioactive contamination

    International Nuclear Information System (INIS)

    Beaugelin-Seiller, K.

    1994-01-01

    The necessity of indicators of freshwater contamination has developed the interest for aquatic mosses. From a fundamental point of view, studying the influence of some biotic and abiotic factors has permitted to better know the mechanisms of radionuclides accumulation by these bryophytes. From a radioecological point of view, simulating real cases of water contamination has allowed to give results a very interesting representativeness. The use of mosses as bio-indicators was applied for two in situ experiments, the results of which have been interpreted from those obtained in laboratory. Finally, an approach by a mathematical model has showed that it is possible to have, in a middle term, an evaluation tool of freshwater contamination, based on the radionuclides concentrations measured in aquatic mosses. (author). refs., 57 figs., 24 tabs

  15. Histopathology of Marine and Freshwater Fish Lymphocytosis Disease Virus (LCDV)

    International Nuclear Information System (INIS)

    Hossain, M.; Myung-Joo, Oh

    2011-01-01

    Lymphocytosis disease (LCD) in fishes is caused by the agent called lymphocytosis disease virus (LCDV). LCDV is a chronic and benign virus. The disease affects 96 species of marine and fresh water fishes ranged among 34 families in the world. Affected fish with LCD has a typical external symptom with clusters consisted of enormously hypertrophied dermal cells on the skin and fins. The hypertrophied cells, generally named lymphocytosis cells, have a thick hyaline capsule, an enlarged nucleus and prominent basophilic cytoplasmic inclusions. Among the four species of fishes, olive flounder Paralichthys olivaceus, and rockfish Sebastes schlegeli were marine cultured fish, and gourami Trichogaster leeri and painted glass fish Channa baculis were freshwater ornamental fish. Although LCD causes low mortality, the disfigurement of infected fish can make them unsellable. Thus LCD has resulted in an important economic loss in the aquaculture industry. This study of histopathology may be adequate for a presumptive diagnosis of lymphocytosis diseases both in marine and freshwater fish species. (author)

  16. Removal of triazine herbicides from freshwater systems using photosynthetic microorganisms

    International Nuclear Information System (INIS)

    Gonzalez-Barreiro, O.; Rioboo, C.; Herrero, C.; Cid, A.

    2006-01-01

    The uptake of the triazine herbicides, atrazine and terbutryn, was determined for two freshwater photosynthetic microorganisms, the green microalga Chlorella vulgaris and the cyanobacterium Synechococcus elongatus. An extremely rapid uptake of both pesticides was recorded, although uptake rate was lower for the cyanobacterium, mainly for atrazine. Other parameters related to the herbicide bioconcentration capacity of these microorganisms were also studied. Growth rate, biomass, and cell viability in cultures containing herbicide were clearly affected by herbicide uptake. Herbicide toxicity and microalgae sensitivity were used to determine the effectiveness of the bioconcentration process and the stability of herbicide removal. C. vulgaris showed higher bioconcentration capability for these two triazine herbicides than S. elongatus, especially with regard to terbutryn. This study supports the usefulness of such microorganisms, as a bioremediation technique in freshwater systems polluted with triazine herbicides

  17. Removal of triazine herbicides from freshwater systems using photosynthetic microorganisms

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Barreiro, O. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain); Rioboo, C. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain); Herrero, C. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain); Cid, A. [Laboratorio de Microbiologia, Facultad de Ciencias, Universidad de A Coruna, Campus da Zapateira s/n. 15071 A Coruna (Spain)]. E-mail: cid@udc.es

    2006-11-15

    The uptake of the triazine herbicides, atrazine and terbutryn, was determined for two freshwater photosynthetic microorganisms, the green microalga Chlorella vulgaris and the cyanobacterium Synechococcus elongatus. An extremely rapid uptake of both pesticides was recorded, although uptake rate was lower for the cyanobacterium, mainly for atrazine. Other parameters related to the herbicide bioconcentration capacity of these microorganisms were also studied. Growth rate, biomass, and cell viability in cultures containing herbicide were clearly affected by herbicide uptake. Herbicide toxicity and microalgae sensitivity were used to determine the effectiveness of the bioconcentration process and the stability of herbicide removal. C. vulgaris showed higher bioconcentration capability for these two triazine herbicides than S. elongatus, especially with regard to terbutryn. This study supports the usefulness of such microorganisms, as a bioremediation technique in freshwater systems polluted with triazine herbicides.

  18. Metagenomic recovery of phage genomes of uncultured freshwater actinobacteria.

    Science.gov (United States)

    Ghai, Rohit; Mehrshad, Maliheh; Mizuno, Carolina Megumi; Rodriguez-Valera, Francisco

    2017-01-01

    Low-GC Actinobacteria are among the most abundant and widespread microbes in freshwaters and have largely resisted all cultivation efforts. Consequently, their phages have remained totally unknown. In this work, we have used deep metagenomic sequencing to assemble eight complete genomes of the first tailed phages that infect freshwater Actinobacteria. Their genomes encode the actinobacterial-specific transcription factor whiB, frequently found in mycobacteriophages and also in phages infecting marine pelagic Actinobacteria. Its presence suggests a common and widespread strategy of modulation of host transcriptional machinery upon infection via this transcriptional switch. We present evidence that some whiB-carrying phages infect the acI lineage of Actinobacteria. At least one of them encodes the ADP-ribosylating component of the widespread bacterial AB toxins family (for example, clostridial toxin). We posit that the presence of this toxin reflects a 'trojan horse' strategy, providing protection at the population level to the abundant host microbes against eukaryotic predators.

  19. Coastal conduit in southwestern Hudson Bay (Canada) in summer: Rapid transit of freshwater and significant loss of colored dissolved organic matter

    Science.gov (United States)

    Granskog, Mats A.; MacDonald, Robie W.; Kuzyk, Zou Zou A.; Senneville, Simon; Mundy, Christopher-John; Barber, David G.; Stern, Gary A.; Saucier, Francois

    2009-08-01

    Distributions of freshwater (sea-ice melt and runoff) were investigated along inshore-offshore sections in southwestern Hudson Bay for fall conditions. Conductivity-temperature-density profiles and bottle samples collected for salinity, oxygen isotope (δ18O), and colored dissolved organic matter (CDOM) analyses were used to discriminate between contributions of river water (RW) and sea-ice melt (SIM). Stations had a fresh summer surface mixed layer 5-25 m thick overlying a cold subsurface layer indicative of the previous winter's polar mixed layer (PML). The fraction of RW decreased strongly with distance from shore, while the opposite was true for SIM. The majority of RW was constrained in a coastal domain within 100-150 km from shore, which, because of high alongshore velocities, accounts for the majority of freshwater and volume transports. On the basis of freshwater inventories and composition, brine and RW accumulate in the PML over winter because of ice formation and downward mixing. The summer surface circulation results in an annual net export of SIM from the region. Residence times for freshwater components in the southwestern sector of the bay, based on currents derived from a 3-D ocean model for Hudson Bay, are about 1-10 months, implying rapid transit of freshwater. Despite the short residence time for RW (1-3 months), CDOM is significantly photobleached and provides an unreliable tracer for RW. Photobleaching represents an important sink for dissolved organic carbon entering from rivers and could, in part, explain why Hudson Bay is only a minor sink for atmospheric CO2 in the open water season.

  20. Terrestrial carbohydrates support freshwater zooplankton during phytoplankton deficiency

    OpenAIRE

    Taipale, Sami J.; Galloway, Aaron W. E.; Aalto, Sanni L.; Kahilainen, Kimmo K.; Strandberg, Ursula; Kankaala, Paula

    2016-01-01

    Freshwater food webs can be partly supported by terrestrial primary production, often deriving from plant litter of surrounding catchment vegetation. Although consisting mainly of poorly bioavailable lignin, with low protein and lipid content, the carbohydrates from fallen tree leaves and shoreline vegetation may be utilized by aquatic consumers. Here we show that during phytoplankton deficiency, zooplankton (Daphnia magna) can benefit from terrestrial particulate organic matter by using terr...

  1. Tributyltin-resistant bacteria from estuarine and freshwater sediments.

    Science.gov (United States)

    Wuertz, S; Miller, C E; Pfister, R M; Cooney, J J

    1991-01-01

    Resistance to tributyltin (TBT) was examined in populations from TBT-polluted sediments and nonpolluted sediments from an estuary and from fresh water as well as in pure cultures isolated from those sediments. The 50% effective concentrations (EC50s) for populations were higher at a TBT-polluted freshwater site than at a site without TBT, suggesting that TBT selected for a TBT-resistant population. In contrast, EC50s were significantly lower for populations from a TBT-contaminated estuarine site than for those from a site without TBT, suggesting that other factors in addition to TBT determine whether populations become resistant. EC50s for populations from TBT-contaminated freshwater sediments were nearly 30 times higher than those for populations from TBT-contaminated estuarine sediments. We defined a TBT-resistant bacterium as one which grows on trypticase soy agar containing 8.4 microM TBT, a concentration which prevented the growth of 90% of the culturable bacteria from these sediments. The toxicity of TBT in laboratory media was influenced markedly by the composition of the medium and whether it was liquid or solid. Ten TBT-resistant isolates from estuarine sediments and 19 from freshwater sediments were identified to the genus level. Two isolates, each a Bacillus sp., may be the first gram-positive bacteria isolated from fresh water in the presence of a high concentration of TBT. There was a high incidence of resistance to heavy metals: metal resistance indices were 0.76 for estuarine isolates and 0.68 for freshwater isolates.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1746939

  2. Influence of net freshwater supply on salinity in Florida Bay

    Science.gov (United States)

    Nuttle, William K.; Fourqurean, James W.; Cosby, Bernard J.; Zieman, Joseph C.; Robblee, Michael B.

    2000-01-01

    An annual water budget for Florida Bay, the large, seasonally hypersaline estuary in the Everglades National Park, was constructed using physically based models and long‐term (31 years) data on salinity, hydrology, and climate. Effects of seasonal and interannual variations of the net freshwater supply (runoff plus rainfall minus evaporation) on salinity variation within the bay were also examined. Particular attention was paid to the effects of runoff, which are the focus of ambitious plans to restore and conserve the Florida Bay ecosystem. From 1965 to 1995 the annual runoff from the Everglades into the bay was less than one tenth of the annual direct rainfall onto the bay, while estimated annual evaporation slightly exceeded annual rainfall. The average net freshwater supply to the bay over a year was thus approximately zero, and interannual variations in salinity appeared to be affected primarily by interannual fluctuations in rainfall. At the annual scale, runoff apparently had little effect on the bay as a whole during this period. On a seasonal basis, variations in rainfall, evaporation, and runoff were not in phase, and the net freshwater supply to the bay varied between positive and negative values, contributing to a strong seasonal pattern in salinity, especially in regions of the bay relatively isolated from exchanges with the Gulf of Mexico and Atlantic Ocean. Changes in runoff could have a greater effect on salinity in the bay if the seasonal patterns of rainfall and evaporation and the timing of the runoff are considered. One model was also used to simulate spatial and temporal patterns of salinity responses expected to result from changes in net freshwater supply. Simulations in which runoff was increased by a factor of 2 (but with no change in spatial pattern) indicated that increased runoff will lower salinity values in eastern Florida Bay, increase the variability of salinity in the South Region, but have little effect on salinity in the Central

  3. Histopathological study on parasites in freshwater ornamental fishes in Iran

    OpenAIRE

    Nematollahi, A.; Jaberi, S.; Helan, J. Ashrafi; Sheikhzadeh, N.

    2014-01-01

    During March 2012 through February 2013, 100 freshwater ornamental fishes in 22 species from some aquarium fish shops were examined. Specimens were dissected and tissue samples consisted of liver, kidney, spleen, heart, intestine, ovary, brain and eye were fixed in 10 % buffered formalin and sections were provided and stained with hematoxylin and eosin, Periodic Acid-Schiff, Giemsa and acid-fast staining (Ziehl-Neelsen). At present study six species of protozoans consisting of Eimeria spp. Cr...

  4. Nematodes from terrestrial and freshwater habitats in the Arctic

    Science.gov (United States)

    2014-01-01

    Abstract We present an updated list of terrestrial and freshwater nematodes from all regions of the Arctic, for which records of properly identified nematode species are available: Svalbard, Jan Mayen, Iceland, Greenland, Nunavut, Northwest territories, Alaska, Lena River estuary, Taymyr and Severnaya Zemlya and Novaya Zemlya. The list includes 391 species belonging to 146 genera, 54 families and 10 orders of the phylum Nematoda. PMID:25197239

  5. Characterization of Vibrio species isolated from freshwater fishes by ribotyping

    OpenAIRE

    Mishra, P.; Samanta, M.; Mohanty, S.; Maiti, N. K.

    2010-01-01

    Three Vibrio species from the resident microflora of gastrointestinal tract of freshwater carps and prawns were isolated and confirmed biochemically as V. fluvialis from Cyprinus carpio/Labeo rohita; V. parahaemolyticus from Macrobrachium rosenbergii and V. harveyi from Macrobrachium malcomsoni. The genetic relationship among these Vibrio species was carried out by polymerase chain reaction (PCR) amplification of 16S rRNA gene followed by restriction digestion with Hae III, Bam HI and Pst I. ...

  6. CAGE BREEDING OF WARM WATER FRESHWATER FISH SPECIES

    Directory of Open Access Journals (Sweden)

    Roman Safner

    2008-10-01

    Full Text Available In the 1970s, Croatia became actively involved in the contemporary trend of breeding fish in floating cages. In addition to various species of marine fishes, breeding was attempted with trout, carp, catfish, cisco and salmon. Of the above freshwater fish species, specific standards were established only for the cage breeding of rainbow trout. Cage breeding of the remaining species remained at the level of occasional attempts, with more of an experimental than a commercial character. The regular attempts to master this technique for cage breeding of warm water freshwater fish species were aimed at achieving the known benefits of such breeding, such as simplicity of implementing technological measures, easier establishment of the breeding system, simpler manipulation, the possibility of denser colonies per unit volume with a high level of production, easier adaptations to market conditions and fewer initial structural investments. Despite the many advantages, the main reasons for the lack of greater implementation of the cage breeding technology for warm water species of freshwater fish include problems in obtaining the appropriate category and quantity of healthy fry, the specificity and applicability of physical and chemical properties of the recipients and human error. In evaluating the advantages and disadvantages, the final decision on the justification of cage breeding for individual warm water freshwater species must be based on both biological and economic factors. Based on the knowledge of cage breeding acquired to date, the rule for virtually all intensive breeding systems is that it is only recommended for those species with high market demand and a high market price. The technology that demands nutrition with highly concentrated feed and other production expenditures is costly, and is therefore not profitable with less expensive fish species. Furthermore, production must be market oriented, i.e. the appropriate market research measures

  7. Perennial water stratification and the role of freshwater in the mass balance of Arctic ice shelves and multiyear landfast sea ice

    International Nuclear Information System (INIS)

    Jeffries, M.O.

    1991-01-01

    A number of the ice shelves of northern Ellesmere Island in the Canadian High Arctic owe their origin to multiyear landfast sea ice (MLSI) growth during the post-Hypsithermal cooling ca. 3,000-4,000 BP. Since they grew in response to an arctic-wide climatic deterioration and contain evidence of occasional post-4,000 BP climatic ameliorations, they may be expected to be sensitive to future global climate changes manifested in the High Arctic. The purpose of this paper is to examine ice-ocean interactions and feedbacks, and the response of the ice shelves and the MLSI to the improved summer climate of the last ca. 100 years, and implications for the future. There is good evidence that there has been a negative surface mass balance since the turn of the century. Mass balance measurements on the Ward Hunt Ice Shelf between 1966 and 1985 indicate a total ice loss of 1.371 m at a mean annual rate of 68.5 mm. The interannual pattern of accumulation and ablation and the long-term losses on the ice shelf are similar to other Canadian High Arctic glacier mass balance records. It is evident from water and ice core records of salinity, δ 18 0 and tritium, that perennial water stratification is common below and behind the ice shelves and MLSI. The coastal waters are highly stratified, with anything from 0.5 m to 41.0 m of freshwater interposed between the overlying ice and underlying seawater. The primary source of the freshwater is summer run-off of snow-meltwater from the adjacent land and from the ice itself. There is minimal mixing between the influent freshwater and seawater, and the freshwater is either dammed behind the ice shelves and the MLSI, with subsequent under-ice freshwater outflows, or pooled in under-ice depressions

  8. Cytotoxicity of TiO{sub 2} nanoparticles towards freshwater sediment microorganisms at low exposure concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Kumari, Jyoti; Kumar, Deepak; Mathur, Ankita; Naseer, Arif; Kumar, Ravi Ranjan [Centre for Nanobiotechnology, VIT University, Vellore 632014 (India); Thanjavur Chandrasekaran, Prathna [Department of Materials Engineering, Indian Institute of Science, Bangalore (India); Chaudhuri, Gouri; Pulimi, Mrudula [Centre for Nanobiotechnology, VIT University, Vellore 632014 (India); Raichur, Ashok M. [Department of Materials Engineering, Indian Institute of Science, Bangalore (India); Department of Chemical Technology, University of Johannesburg (South Africa); Babu, S. [School of Bio Sciences and Technology, VIT University, Vellore (India); Chandrasekaran, Natarajan [Centre for Nanobiotechnology, VIT University, Vellore 632014 (India); Nagarajan, R. [Department of Chemical Engineering, IIT Madras, Chennai (India); Mukherjee, Amitava, E-mail: amit.mookerjea@gmail.com [Centre for Nanobiotechnology, VIT University, Vellore 632014 (India)

    2014-11-15

    There is a persistent need to assess the effects of TiO{sub 2} nanoparticles on the aquatic ecosystem owing to their increasing usage in consumer products and risk of environmental release. The current study is focused on TiO{sub 2} nanoparticle-induced acute toxicity at sub-ppm level (≤1 ppm) on the three different freshwater sediment bacterial isolates and their consortium under two different irradiation (visible light and dark) conditions. The consortium of the bacterial isolates was found to be less affected by the exposure to the nanoparticles compared to the individual cells. The oxidative stress contributed considerably towards the cytotoxicity under both light and dark conditions. A statistically significant increase in membrane permeability was noted under the dark conditions as compared to the light conditions. The optical and fluorescence microscopic images showed aggregation and chain formation of the bacterial cells, when exposed to the nanoparticles. The electron microscopic (SEM, TEM) observations suggested considerable damage of cells and bio-uptake of nanoparticles. The exopolysaccrides (EPS) production and biofilm formation were noted to increase in the presence of the nanoparticles, and expression of the key genes involved in biofilm formation was studied by RT-PCR. - Highlights: • Toxicity of NPs towards freshwater sediment bacteria at sub-ppm concentrations. • Decreased toxicity of the nanoparticles in the consortium of microorganisms. • Enhanced bacterial resistance through EPS and biofilm formation in the presence of NPs. • Considerable surface damage of cells and internalization of NPs. • Gene expression analyses related to biofilm formation in the presence of NPs.

  9. Cytotoxicity of TiO2 nanoparticles towards freshwater sediment microorganisms at low exposure concentrations

    International Nuclear Information System (INIS)

    Kumari, Jyoti; Kumar, Deepak; Mathur, Ankita; Naseer, Arif; Kumar, Ravi Ranjan; Thanjavur Chandrasekaran, Prathna; Chaudhuri, Gouri; Pulimi, Mrudula; Raichur, Ashok M.; Babu, S.; Chandrasekaran, Natarajan; Nagarajan, R.; Mukherjee, Amitava

    2014-01-01

    There is a persistent need to assess the effects of TiO 2 nanoparticles on the aquatic ecosystem owing to their increasing usage in consumer products and risk of environmental release. The current study is focused on TiO 2 nanoparticle-induced acute toxicity at sub-ppm level (≤1 ppm) on the three different freshwater sediment bacterial isolates and their consortium under two different irradiation (visible light and dark) conditions. The consortium of the bacterial isolates was found to be less affected by the exposure to the nanoparticles compared to the individual cells. The oxidative stress contributed considerably towards the cytotoxicity under both light and dark conditions. A statistically significant increase in membrane permeability was noted under the dark conditions as compared to the light conditions. The optical and fluorescence microscopic images showed aggregation and chain formation of the bacterial cells, when exposed to the nanoparticles. The electron microscopic (SEM, TEM) observations suggested considerable damage of cells and bio-uptake of nanoparticles. The exopolysaccrides (EPS) production and biofilm formation were noted to increase in the presence of the nanoparticles, and expression of the key genes involved in biofilm formation was studied by RT-PCR. - Highlights: • Toxicity of NPs towards freshwater sediment bacteria at sub-ppm concentrations. • Decreased toxicity of the nanoparticles in the consortium of microorganisms. • Enhanced bacterial resistance through EPS and biofilm formation in the presence of NPs. • Considerable surface damage of cells and internalization of NPs. • Gene expression analyses related to biofilm formation in the presence of NPs

  10. Combined ecological risks of nitrogen and phosphorus in European freshwaters

    International Nuclear Information System (INIS)

    Azevedo, Ligia B.; Zelm, Rosalie van; Leuven, Rob S.E.W.; Hendriks, A. Jan; Huijbregts, Mark A.J.

    2015-01-01

    Eutrophication is a key water quality issue triggered by increasing nitrogen (N) and phosphorus (P) levels and potentially posing risks to freshwater biota. We predicted the probability that an invertebrate species within a community assemblage becomes absent due to nutrient stress as the ecological risk (ER) for European lakes and streams subjected to N and P pollution from 1985 to 2011. The ER was calculated as a function of species-specific tolerances to NO 3 − and total P concentrations and water quality monitoring data. Lake and stream ER averaged 50% in the last monitored year (i.e. 2011) and we observed a decrease by 22% and 38% in lake and stream ER (respectively) of river basins since 1985. Additionally, the ER from N stress surpassed that of P in both freshwater systems. The ER can be applied to identify river basins most subjected to eutrophication risks and the main drivers of impacts. - Highlights: • Ecological risk was estimated as response additions of N and P. • The risk posed by N stress is higher than that by P in European freshwaters. • Ecological risks have remained unchanged in most European river basins. - Quantifying the ecological risk of invertebrate losses due to N and P pollution

  11. Predator-induced reduction of freshwater carbon dioxide emissions

    Science.gov (United States)

    Atwood, Trisha B.; Hammill, Edd; Greig, Hamish S.; Kratina, Pavel; Shurin, Jonathan B.; Srivastava, Diane S.; Richardson, John S.

    2013-03-01

    Predators can influence the exchange of carbon dioxide between ecosystems and the atmosphere by altering ecosystem processes such as decomposition and primary production, according to food web theory. Empirical knowledge of such an effect in freshwater systems is limited, but it has been suggested that predators in odd-numbered food chains suppress freshwater carbon dioxide emissions, and predators in even-numbered food chains enhance emissions. Here, we report experiments in three-tier food chains in experimental ponds, streams and bromeliads in Canada and Costa Rica in the presence or absence of fish (Gasterosteus aculeatus) and invertebrate (Hesperoperla pacifica and Mecistogaster modesta) predators. We monitored carbon dioxide fluxes along with prey and primary producer biomass. We found substantially reduced carbon dioxide emissions in the presence of predators in all systems, despite differences in predator type, hydrology, climatic region, ecological zone and level of in situ primary production. We also observed lower amounts of prey biomass and higher amounts of algal and detrital biomass in the presence of predators. We conclude that predators have the potential to markedly influence carbon dioxide dynamics in freshwater systems.

  12. Homogenization patterns of the world’s freshwater fish faunas

    Science.gov (United States)

    Villéger, Sébastien; Blanchet, Simon; Beauchard, Olivier; Oberdorff, Thierry; Brosse, Sébastien

    2011-01-01

    The world is currently undergoing an unprecedented decline in biodiversity, which is mainly attributable to human activities. For instance, nonnative species introduction, combined with the extirpation of native species, affects biodiversity patterns, notably by increasing the similarity among species assemblages. This biodiversity change, called taxonomic homogenization, has rarely been assessed at the world scale. Here, we fill this gap by assessing the current homogenization status of one of the most diverse vertebrate groups (i.e., freshwater fishes) at global and regional scales. We demonstrate that current homogenization of the freshwater fish faunas is still low at the world scale (0.5%) but reaches substantial levels (up to 10%) in some highly invaded river basins from the Nearctic and Palearctic realms. In these realms experiencing high changes, nonnative species introductions rather than native species extirpations drive taxonomic homogenization. Our results suggest that the “Homogocene era” is not yet the case for freshwater fish fauna at the worldwide scale. However, the distressingly high level of homogenization noted for some biogeographical realms stresses the need for further understanding of the ecological consequences of homogenization processes. PMID:22025692

  13. Homogenization patterns of the world's freshwater fish faunas.

    Science.gov (United States)

    Villéger, Sébastien; Blanchet, Simon; Beauchard, Olivier; Oberdorff, Thierry; Brosse, Sébastien

    2011-11-01

    The world is currently undergoing an unprecedented decline in biodiversity, which is mainly attributable to human activities. For instance, nonnative species introduction, combined with the extirpation of native species, affects biodiversity patterns, notably by increasing the similarity among species assemblages. This biodiversity change, called taxonomic homogenization, has rarely been assessed at the world scale. Here, we fill this gap by assessing the current homogenization status of one of the most diverse vertebrate groups (i.e., freshwater fishes) at global and regional scales. We demonstrate that current homogenization of the freshwater fish faunas is still low at the world scale (0.5%) but reaches substantial levels (up to 10%) in some highly invaded river basins from the Nearctic and Palearctic realms. In these realms experiencing high changes, nonnative species introductions rather than native species extirpations drive taxonomic homogenization. Our results suggest that the "Homogocene era" is not yet the case for freshwater fish fauna at the worldwide scale. However, the distressingly high level of homogenization noted for some biogeographical realms stresses the need for further understanding of the ecological consequences of homogenization processes.

  14. PBDEs in freshwater mussels and fish from Flanders, Belgium

    Energy Technology Data Exchange (ETDEWEB)

    Covaci, A.; Voorspoels, S.; Schepens, P. [Antwerp Univ. (Belgium). Toxicological Center; Bervoets, L.; Hoff, P.; Voets, J.; Campenhout, K. van; Blust, R. [Antwerp Univ. (Belgium). Dept. of Ecophysiology, Biochemistry and Toxicology

    2004-09-15

    Polybrominated diphenylethers (PBDEs), a class of brominated flame retardants (BFRs), are widely used in textiles, plastics, electronic equipment and other materials for more than 30 years. Due to their massive use, PBDEs have become ubiquitously present in aquatic organisms and it was recently evidenced that their levels seem to increase rapidly. Higher PBDE concentrations were found in biota from freshwater compared to similar marine species. This is probably due to a higher pollution load found near point pollution sources that are almost exclusively inland located. Zebra mussels (Dreissena polymorpha) fulfil the requirements of a good biomonitoring organism for freshwater ecosystems: they are easy to collect and to handle, are available in sufficient numbers, have a relative long lifespan, are sedentary and resistant to various types of pollution without suffering a too high mortality and have a high filtration rate which favours the bioaccumulation of organic contaminants. Fish species are another suitable tool for the biomonitoring of organic contaminants. The occurrence of PBDEs in fish species from Europe has already received some attention, but the amount of data is still limited. The aim of this study was to evaluate the occurence of PBDEs in zebra mussels and several representative freshwater fish species (eel, carp and gibel carp) at different sites in Flanders, Belgium. In parallel, other organohalogenated contaminants, such as polychlorinated biphenyls (PCBs), p,p'-DDE and hexachlorobenzene (HCB) were also measured and their relationship with PBDEs was investigated.

  15. Overwintering of sea trout (Salmo trutta) in freshwater

    DEFF Research Database (Denmark)

    Thomsen, Dennis; Koed, Anders; Nielsen, Christian

    2007-01-01

    Brown trout (Salmo trutta) show large phenotypic plasticity. Juveniles may reside in their native freshwater habitat until maturation or migrate into the ocean as 1- to 3-year-old smolts. Sea-going fish (sea trout) reside at sea for 2-3 years until migrating back to their native stream for reprod......Brown trout (Salmo trutta) show large phenotypic plasticity. Juveniles may reside in their native freshwater habitat until maturation or migrate into the ocean as 1- to 3-year-old smolts. Sea-going fish (sea trout) reside at sea for 2-3 years until migrating back to their native stream...... for reproduction. However, immature fish may leave the ocean during their first or second winter at sea and overwinter in freshwater. The question is why does this occur? We tested the hypothesis that hypo-osmoregulatory capacity is compromised by low temperature in two coastal sea trout populations, one...... representing high salinity and the other, low salinity. Immature sea-run trout were caught in lower parts of two rivers during winter and acclimated to laboratory conditions. Subgroups were challenged with high salinity or low water temperature or both, and their osmoregulatory performance was investigated...

  16. Magnetic resonance imaging of live freshwater mussels (Unionidae)

    Science.gov (United States)

    Michael, Holliman F.; Davis, Denise; Bogan, Arthur E.; Kwak, Thomas J.; Cope, W. Gregory; Levine, Jay F.

    2008-01-01

    We examined the so