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Sample records for vicinal freshwater lentic

  1. Fish species composition in a tropical lentic freshwater ecosystem ...

    African Journals Online (AJOL)

    Fish species composition of a tropical lentic freshwater ecosystem (Umudike Water Reservoir, Umuahia, Nigeria) belonging to the National Root Crops Research Institute (NRCRI) was investigated from July 2004 to December 2004. The fishes were sampled twice every week using cast nets, traditional baskets traps (drum ...

  2. Habitat availability does not explain the species richness patterns of European lentic and lotic freshwater animals

    DEFF Research Database (Denmark)

    Dehling, D.M.; Hof, C.; Brandle, M.

    2010-01-01

    Aim In Europe, the relationships between species richness and latitude differ for lentic (standing water) and lotic (running water) species. Freshwater animals are highly dependent on suitable habitat, and thus the distribution of available habitat should strongly influence large-scale patterns...... of species richness. We tested whether habitat availability can account for the differences in species richness patterns between European lentic and lotic freshwater animals. Location Europe. Methods We compiled occurrence data of 1959 lentic and 2445 lotic species as well as data on the amount of lentic...... and lotic habitats across 25 pre-defined biogeographical regions of European freshwaters. We used the range of elevation of each region as a proxy for habitat diversity. We investigated the relationships between species richness, habitat availability and habitat diversity with univariate and multiple...

  3. Characterizing lentic freshwater fish assemblages using multiple sampling methods.

    Science.gov (United States)

    Fischer, Jesse R; Quist, Michael C

    2014-07-01

    Characterizing fish assemblages in lentic ecosystems is difficult, and multiple sampling methods are almost always necessary to gain reliable estimates of indices such as species richness. However, most research focused on lentic fish sampling methodology has targeted recreationally important species, and little to no information is available regarding the influence of multiple methods and timing (i.e., temporal variation) on characterizing entire fish assemblages. Therefore, six lakes and impoundments (48-1,557 ha surface area) were sampled seasonally with seven gear types to evaluate the combined influence of sampling methods and timing on the number of species and individuals sampled. Probabilities of detection for species indicated strong selectivities and seasonal trends that provide guidance on optimal seasons to use gears when targeting multiple species. The evaluation of species richness and number of individuals sampled using multiple gear combinations demonstrated that appreciable benefits over relatively few gears (e.g., to four) used in optimal seasons were not present. Specifically, over 90 % of the species encountered with all gear types and season combinations (N = 19) from six lakes and reservoirs were sampled with nighttime boat electrofishing in the fall and benthic trawling, modified-fyke, and mini-fyke netting during the summer. Our results indicated that the characterization of lentic fish assemblages was highly influenced by the selection of sampling gears and seasons, but did not appear to be influenced by waterbody type (i.e., natural lake, impoundment). The standardization of data collected with multiple methods and seasons to account for bias is imperative to monitoring of lentic ecosystems and will provide researchers with increased reliability in their interpretations and decisions made using information on lentic fish assemblages.

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

    Science.gov (United States)

    Fischer, Jesse R.; Quist, Michael C.

    2014-01-01

    the future development of standardized sampling methods for freshwater fish in lentic ecosystems.

  5. Not going with the flow: a comprehensive time-calibrated phylogeny of dragonflies (Anisoptera: Odonata: Insecta) provides evidence for the role of lentic habitats on diversification.

    Science.gov (United States)

    Letsch, Harald; Gottsberger, Brigitte; Ware, Jessica L

    2016-03-01

    Ecological diversification of aquatic insects has long been suspected to have been driven by differences in freshwater habitats, which can be classified into flowing (lotic) waters and standing (lentic) waters. The contrasting characteristics of lotic and lentic freshwater systems imply different ecological constraints on their inhabitants. The ephemeral and discontinuous character of most lentic water bodies may encourage dispersal by lentic species in turn reducing geographical isolation among populations. Hence, speciation probability would be lower in lentic species. Here, we assess the impact of habitat use on diversification patterns in dragonflies (Anisoptera: Odonata). Based on the eight nuclear and mitochondrial genes, we inferred species diversification with a model-based evolutionary framework, to account for rate variation through time and among lineages and to estimate the impact of larval habitat on the potentially nonrandom diversification among anisopteran groups. Ancestral state reconstruction revealed lotic fresh water systems as their original primary habitat, while lentic waters have been colonized independently in Aeshnidae, Corduliidae and Libellulidae. Furthermore, our results indicate a positive correlation of speciation and lentic habitat colonization by dragonflies: speciation rates increased in lentic Aeshnidae and Libellulidae, whereas they remain mostly uniform among lotic groups. This contradicts the hypothesis of inherently lower speciation in lentic groups and suggests species with larger ranges are more likely to diversify, perhaps due to higher probability of larger areas being dissected by geographical barriers. Furthermore, larger range sizes may comprise more habitat types, which could also promote speciation by providing additional niches, allowing the coexistence of emerging species. © 2016 John Wiley & Sons Ltd.

  6. Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2007

    Energy Technology Data Exchange (ETDEWEB)

    Sobocinski, Kathryn L.; Johnson, Gary E.; Sather, Nichole K.; Storch, Adam; Jones, Tucker A.; Mallette, Christine; Dawley, Earl M.; Skalski, John R.; Teel, David; Moran, Paul

    2008-03-18

    This document is the first annual report for the study titled “Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta in the Lower Columbia River.” Hereafter, we refer to this research as the Tidal Freshwater Monitoring (TFM) Study. The study is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act as a result of operation of the Federal Columbia River Power System (FCRPS). The project is performed under the auspices of the Northwest Power and Conservation Council’s Columbia Basin Fish and Wildlife Program.

  7. Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2007 Annual Report.

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    Sobocinski, Kathryn; Johnson, Gary; Sather, Nichole [Pacific Northwest National Laboratory

    2008-03-17

    This document is the first annual report for the study titled 'Ecology of Juvenile Salmonids in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta in the Lower Columbia River'. Hereafter, we refer to this research as the Tidal Freshwater Monitoring (TFM) Study. The study is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, U.S. Army Corps of Engineers, U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act as a result of operation of the Federal Columbia River Power System (FCRPS). The project is performed under the auspices of the Northwest Power and Conservation Council's Columbia Basin Fish and Wildlife Program. The goal of the 2007-2009 Tidal Freshwater Monitoring Study is to answer the following questions: In what types of habitats within the tidal freshwater area of the lower Columbia River and estuary (LCRE; Figure 1) are yearling and subyearling salmonids found, when are they present, and under what environmental conditions?1 And, what is the ecological importance2 of shallow (0-5 m) tidal freshwater habitats to the recovery of Upper Columbia River spring Chinook salmon and steelhead and Snake River fall Chinook salmon? Research in 2007 focused mainly on the first question, with fish stock identification data providing some indication of Chinook salmon presence at the variety of habitat types sampled. The objectives and sub-objectives for the 2007 study were as follows: (1) Habitat and Fish Community Characteristics-Provide basic data on habitat and fish community characteristics for yearling and subyearling salmonids at selected sites in the tidal freshwater reach in the vicinity of the Sandy River delta. (1a) Characterize vegetation assemblage percent cover, conventional water quality, substrate composition, and beach slope at each of six sampling sites in various tidal freshwater habitat types. (1b

  8. Temperature and precipitation shape the distribution of harmful cyanobacteria in subtropical lotic and lentic ecosystems.

    Science.gov (United States)

    Haakonsson, Signe; Rodríguez-Gallego, Lorena; Somma, Andrea; Bonilla, Sylvia

    2017-12-31

    Cyanobacterial blooms are expected to become more frequent in freshwaters globally due to eutrophication and climate change effects. However, our knowledge about cyanobacterial biogeography in the subtropics, particularly in lotic ecosystems, is still very limited and the relationship of blooms to temperature and precipitation remains unclear. We took advantage of a comprehensive database of field data compiled over several years (1997 to 2015) to compare cyanobacteria biomass and distribution between lentic and lotic subtropical freshwaters (36 ecosystems, 30°-35°S) and to investigate the role of water temperature and precipitation as significant predictors in eutrophic ecosystems. A filamentous Nostocales, Dolichospermum (Anabaena), was the most widely distributed and frequent genus in the region of the study, followed by the colonial Microcystis, supporting observations of a global latitudinal pattern. Similar total cyanobacteria biovolumes (TCB) were found in lentic and lotic ecosystems, but the proportion of Dolichospermum was higher in lotic ecosystems. Using generalized linear models (GLMs), we found that temperature and rainfall explained 27% of the variation in TCB in lotic ecosystems, while temperature explained 19 and 28% of Dolichospermum and Microcystis biovolume, respectively. In lentic ecosystems, accumulated rainfall explained 34% of the variation of Microcystis biovolume while temperature explained 64%. Our results imply that the increase in extreme meteorological events and temperature predicted by climate models will promote increasingly severe cyanobacterial blooms in eutrophic subtropical freshwaters. Our analysis provides new information about the occurrence of bloom-forming cyanobacteria for southeastern South America and thus fills an important knowledge gap for subtropical freshwaters. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2008 Annual Report.

    Energy Technology Data Exchange (ETDEWEB)

    Sather, NK; Johnson, GE; Storch, AJ [Pacific Northwest National Laboratory

    2009-07-06

    The tidal freshwater monitoring (TFM) project reported herein is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, the U.S. Army Corps of Engineers [USACE], and the U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act (ESA) as a result of operation of the Federal Columbia River Power System. The project is being performed under the auspices of the Northwest Power and Conservation Council's Columbia Basin Fish and Wildlife Program (Project No. 2005-001-00). The research is a collaborative effort among the Pacific Northwest National Laboratory, the Oregon Department of Fish and Wildlife, the National Marine Fisheries Service, and the University of Washington. The overarching goal of the TFM project is to bridge the gap in knowledge between tidal freshwater habitats and the early life history attributes of migrating salmon. The research questions include: In what types of habitats within the tidal freshwater area of the Columbia River are juvenile salmon found, when are they present, and under what environmental conditions? What is the ecological contribution of shallow (0-5 m) tidal freshwater habitats to the recovery of ESA-listed salmon in the Columbia River basin? Field data collection for the TFM project commenced in June 2007 and since then has continued monthly at six to nine sites in the vicinity of the Sandy River delta (river kilometer 192-208). While this report includes summary data spanning the 19-month period of study from June 2007 through December 2008, it highlights sampling conducted during calendar year 2008. Detailed data for calendar year 2007 were reported previously. The 2008 research objectives were as follows: (1) Characterize the vegetation composition and percent cover, conventional water quality, water surface elevation, substrate composition, bathymetry, and beach slope at the study sites within the vicinity of the Sandy

  10. Habitat type predicts genetic population differentiation in freshwater invertebrates.

    Science.gov (United States)

    Marten, Andreas; Brändle, Martin; Brandl, Roland

    2006-08-01

    A basic challenge in evolutionary biology is to establish links between ecology and evolution of species. One important link is the habitat template. It has been hypothesized, that the spatial and temporal settings of a habitat strongly influence the evolution of species dispersal propensity. Here, we evaluate the importance of the habitat type on genetic population differentiation of species using freshwater habitats as a model system. Freshwater habitats are either lentic (standing) or lotic (running). On average, lotic habitats are more stable and predictable over space and time than lentic habitats. Therefore, lentic habitats should favour the evolution of higher dispersal propensity which ensures population survival of lentic species. To test for such a relationship, we used extensive data on species' genetic population differentiation of lentic and lotic freshwater invertebrates retrieved from published allozyme studies. Overall, we analysed more than 150 species from all over the world. Controlling for several experimental, biological and geographical confounding effects, we always found that lentic invertebrates exhibit, on average, lower genetic population differentiation than lotic species. This pattern was consistent across insects, crustaceans and molluscs. Our results imply fundamental differences in genetic population differentiation among species adapted to either lentic or lotic habitats. We propose that such differences should occur in a number of other habitat types that differ in spatio-temporal stability. Furthermore, our results highlight the important role of lotic habitats as reservoirs for evolutionary processes and the potential for rapid speciation.

  11. Latitudinal variation of diversity in European freshwater animals is not concordant across habitat types

    DEFF Research Database (Denmark)

    Hof, Christian; Brändle, Martin; Brandl, Roland

    2008-01-01

    Aim We analysed the variation of species richness in the European freshwater fauna across latitude. In particular, we compared latitudinal patterns in species richness and ß -diversity among species adapted to different habitat types. Location Europe. Methods We compiled data on occurrence for 14...... (standing water) habitats. We analysed latitudinal patterns of species richness, the proportion of lentic species and ß -diversity. Results Only lentic species showed a significant species-area relationship. We found a monotonic decline of species richness with latitude for groundwater and lotic habitats......, but a hump-shaped relationship for lentic habitats. The proportion of lentic species increased from southern to northern latitudes. ß -Diversity declined from groundwater to lentic habitats and from southern to northern latitudes. Main conclusions The differences in the latitudinal variation of species...

  12. Does the lentic-lotic character of rivers affect invertebrate metrics used in the assessment of ecological quality?

    Directory of Open Access Journals (Sweden)

    Stefania ERBA

    2009-02-01

    Full Text Available The importance of local hydraulic conditions on the structuring of freshwater biotic communities is widely recognized by the scientific community. In spite of this, most current methods based upon invertebrates do not take this factor into account in their assessment of ecological quality. The aim of this paper is to investigate the influence of local hydraulic conditions on invertebrate community metrics and to estimate their potential weight in the evaluation of river water quality. The dataset used consisted of 130 stream sites located in four broad European geographical contexts: Alps, Central mountains, Mediterranean mountains and Lowland streams. Using River Habitat Survey data, the river hydromorphology was evaluated by means of the Lentic-lotic River Descriptor and the Habitat Modification Score. To quantify the level of water pollution, a synoptic Organic Pollution Descriptor was calculated. For their established, wide applicability, STAR Intercalibration Common Metrics and index were selected as biological quality indices. Significant relationships between selected environmental variables and biological metrics devoted to the evaluation of ecological quality were obtained by means of Partial Least Squares regression analysis. The lentic-lotic character was the most significant factor affecting invertebrate communities in the Mediterranean mountains, even if it is a relevant factor for most quality metrics also in the Alpine and Central mountain rivers. Therefore, this character should be taken into account when assessing ecological quality of rivers because it can greatly affect the assignment of ecological status.

  13. Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats in the Vicinity of the Sandy River Delta, Lower Columbia River, 2008

    Energy Technology Data Exchange (ETDEWEB)

    Sather, Nichole K.; Johnson, Gary E.; Storch, Adam; Teel, David; Skalski, John R.; Jones, Tucker A.; Dawley, Earl M.; Zimmerman, Shon A.; Borde, Amy B.; Mallette, Christine; Farr, R.

    2009-05-29

    The tidal freshwater monitoring (TFM) project reported herein is part of the research, monitoring, and evaluation effort developed by the Action Agencies (Bonneville Power Administration, the U.S. Army Corps of Engineers [USACE], and the U.S. Bureau of Reclamation) in response to obligations arising from the Endangered Species Act (ESA) as a result of operation of the Federal Columbia River Power System. The project is being performed under the auspices of the Northwest Power and Conservation Council’s Columbia Basin Fish and Wildlife Program (Project No. 2005-001-00). The research is a collaborative effort among the Pacific Northwest National Laboratory, the Oregon Department of Fish and Wildlife, the National Marine Fisheries Service, and the University of Washington.

  14. Microcystin Prevalence throughout Lentic Waterbodies in Coastal Southern California

    Directory of Open Access Journals (Sweden)

    Meredith D. A. Howard

    2017-07-01

    Full Text Available Toxin producing cyanobacterial blooms have increased globally in recent decades in both frequency and intensity. Despite the recognition of this growing risk, the extent and magnitude of cyanobacterial blooms and cyanotoxin prevalence is poorly characterized in the heavily populated region of southern California. Recent assessments of lentic waterbodies (depressional wetlands, lakes, reservoirs and coastal lagoons determined the prevalence of microcystins and, in some cases, additional cyanotoxins. Microcystins were present in all waterbody types surveyed although toxin concentrations were generally low across most habitats, as only a small number of sites exceeded California’s recreational health thresholds for acute toxicity. Results from passive samplers (Solid Phase Adsorption Toxin Tracking (SPATT indicated microcystins were prevalent throughout lentic waterbodies and that traditional discrete samples underestimated the presence of microcystins. Multiple cyanotoxins were detected simultaneously in some systems, indicating multiple stressors, the risk of which is uncertain since health thresholds are based on exposures to single toxins. Anatoxin-a was detected for the first time from lakes in southern California. The persistence of detectable microcystins across years and seasons indicates a low-level, chronic risk through both direct and indirect exposure. The influence of toxic cyanobacterial blooms is a more complex stressor than presently recognized and should be included in water quality monitoring programs.

  15. Periphytic algae dynamics in lentic ecosystems in the Brazilian semiarid.

    Science.gov (United States)

    Cordeiro, R S; Barbosa, J E L; Lima, G Q; Barbosa, L G

    2017-01-01

    The hydrological periods drive the structure and organization of aquatic communities in semiarid regions. We hypothesize that a decrease of the precipitation during the dry period will favor the development of the periphytic algal community, leading to higher richness and density in this period. To test this hypothesis, we investigated the changes in the periphytic algal community structure in three shallow and eutrophic ecosystems of the Brazilian semiarid. The sampling was performed between 2007 and 2010 at two-mensal intervals. The sampling of periphytic algal was performed in aquatic macrophytes and rocks. The abiotic variables were analyzed simultaneously. Dominance in diatoms, cyanobacteria and chlorophytes, respectively, was observed in two periods. In the dry period, waters were alkaline and had high concentrations of nitrate and total phosphorus associated with the highest densities of Bacillariophyceae. In the rainy period the water was warmer, oxygenated and high concentrations of ammonia and soluble reactive phosphorus with diatoms remained dominant but with reduced density, while cyanobacteria and chlorophytes increased. Overall, periphytic algal community composition no responded to changes in the hydrological periods. However, the hydrological periods altered the dynamics of periphytic algal community, supported by the alternation of the most representative classes (diatoms and cyanobacteria) between the hydrologic periods. Our data suggest that the morphometric and chemical and physical characteristics of lentic aquatic ecosystems studied were more important in the dynamics of periphytic algal community than the hydrological periods and types of substrates.

  16. Freshwater biodiversity of Guam. 1. Introduction, with new records of ciliates and a heliozoan

    OpenAIRE

    LOBBAN, CHRISTOPHER S.; SCHEFTER, MARÍA

    2008-01-01

    Inland waters are the most endangered ecosystems in the world because of complex threats and management problems, yet the freshwater microbial eukaryotes and microinvertebrates are generally not well known and from Guam are virtually unknown. Photodocumentation can provide useful information on such organisms. In this paper we document protists from mostly lentic inland waters of Guam and report twelve freshwater ciliates, especially peritrichs, which are the first records of ciliates from Gu...

  17. Efficiency comparisons of fish sampling gears for a lentic ecosystem health assessments in Korea

    Directory of Open Access Journals (Sweden)

    Jeong-Ho Han

    2016-12-01

    Full Text Available The key objective of this study was to analyze the sampling efficiency of various fish sampling gears for a lentic ecosystem health assessment. A fish survey for the lentic ecosystem health assessment model was sampled twice from 30 reservoirs during 2008–2012. During the study, fishes of 81 species comprising 53,792 individuals were sampled from 30 reservoirs. A comparison of sampling gears showed that casting nets were the best sampling gear with high species richness (69 species, whereas minnow traps were the worst gear with low richness (16 species. Fish sampling efficiency, based on the number of individual catch per unit effort, was best in fyke nets (28,028 individuals and worst in minnow traps (352 individuals. When we compared trammel nets and kick nets versus fyke nets and casting nets, the former were useful in terms of the number of fish individuals but not in terms of the number of fish species.

  18. Riverine phytoplankton shifting along a lentic-lotic continuum under hydrological, physiochemical conditions and species dispersal.

    Science.gov (United States)

    Qu, Yueming; Wu, Naicheng; Guse, Björn; Fohrer, Nicola

    2017-10-21

    The importance of phytoplankton-based bio-assessment has been recently recognized in lowland rivers which are affected by multi-environmental factors. However, some basic questions remain unclear to date, such as: (i) spatial and temporal variations of phytoplankton, (ii) the impact of upstream lakes on downstream community, (iii) the main drivers for species composition or (iv) the regional biodiversity along a lentic-lotic continuum. To answer these questions, we collected and analyzed the fluvial phytoplankton communities along a lentic-lotic continuum from a German lowland catchment, where a well-established ecohydrological modeling predicted long-term discharges at each sampling site. Our results revealed very high spatial and temporal variations of phytoplankton community. The changes of a lake on downstream phytoplankton assemblages were significant, especially the nearest reach after the lake. However, these influences varied along with seasons and limited in a relatively short distance to the lake. Redundancy analysis and Mantel tests showed that phytoplankton composition and dissimilarities along the lentic-lotic continuum attributed more to local hydrological and physicochemical variables than species dispersal, which confirmed the suitability of lowland phytoplankton-based bioassessment. In addition, our findings highlighted the importance of flow regime in shaping phytoplankton community composition and regional beta diversities. This study emphasized the necessity to include the hydrological variables and their relationship with phytoplankton community in future bio-monitoring investigations. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Detritus processing in lentic cave habitats in the neotropics

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    Marconi Silva

    2013-04-01

    Full Text Available Lentic cave habitats are almost always heterotrophic habitats where there are food and oxygen input from the surface. This hydrological exchange seems to be the key factor shaping most groundwater communities. Litter processing in cave water environments has not been experimentally studied as much as it has in lotic subterranean systems, although detritus is likely a critical resource for organisms inhabiting shallow groundwater habitats. The present study sought to evaluate the processing rates and the nitrogen and phosphorous dynamics in plant debris deposited in lentic habitats of two Neotropical limestone caves during 99 days. 84–10×10 cm2 litterbags with mesh sizes of 0.04 mm2 and 9 mm2 were used. In each weighed litter bag, 50 green, intact plant leaf disks (± 2.0 gr/bag were conditioned. At the end of the experiment, the average weight loss was only 17.4%. No macroinvertebrates were found associated to the debris, but significant differences in the processing rate in relation to the cave and mesh size were observed. The weight loss rate of the plant debris was considered slow (average 0.003 K-day. The amount of nitrogen and remaining phosphorous in the plant debris in the two caves showed variations over time with a tendency to increase probably due to the development of microorganisms which assimilate nitrogen and phosphorus. The slow processing rate of the plant debris can be due mainly to the fact that these lentic cave habitats are restrictive to colonization by shredder invertebrates. Furthermore, the abrasive force of the water, which plays an important role in the processing and availability of fragmented debris for colonization by microorganisms, is absent.

  20. Occupancy patterns of mammals and lentic amphibians in the Elwha River riparian zone before dam removal

    Science.gov (United States)

    Jenkins, Kurt J.; Chelgren, Nathan; Sager-Fradkin, K.A.; Happe, P.J.; Adams, Michael J.

    2015-01-01

    The downstream transport of sediments and organics and upstream migration of anadromous fishes are key ecological processes in unregulated riverine ecosystems of the North Pacific coast, but their influence on wildlife habitats and populations is poorly documented. Removal of two large hydroelectric dams in Washington’s Elwha Valley provides an unprecedented opportunity to study long-term responses of wildlife populations to dam removal and restoration of these key ecological processes. We compared pre-dam removal patterns in the relative abundance and occupancy of mesocarnivores, small mammals and lentic amphibians of the Elwha River riparian zone above, between and below the dams. Occupancy of riparian habitats by three mesocarnivore species diminished upriver but did not appear to be closely linked with the absence of salmon in the upper river. Although the importance of salmon in the lower river cannot be discounted, other gradients in food resources also likely contributed to observed distribution patterns of mesocarnivores. Abundance and occupancy patterns within congeneric pairs of new world mice (Peromyscus spp.) and shrews (Sorex spp.) indicated that closely related species were negatively associated with each other and responded to habitat gradients in the riparian zone. The availability of lentic habitats of amphibians was highly variable, and occupancy was low as a result of rapidly changing flows during the larval development period. We speculate that long-term changes in habitat conditions and salmon availability following dam removal will elicit long-term changes in distribution of mesocarnivores, small mammals and amphibians. Long-term monitoring will enhance understanding of the role of fish and restored ecosystem processes on wildlife communities along salmon-bearing rivers in the region.

  1. Diet shift of lentic dragonfly larvae in response to reduced terrestrial prey subsidies

    Science.gov (United States)

    Kraus, Johanna M.

    2010-01-01

    Inputs of terrestrial plant detritus and nutrients play an important role in aquatic food webs, but the importance of terrestrial prey inputs in determining aquatic predator distribution and abundance has been appreciated only recently. I examined the numerical, biomass, and diet responses of a common predator, dragonfly larvae, to experimental reduction of terrestrial arthropod input into ponds. I distributed paired enclosures (n  =  7), one with a screen between the land and water (reduced subsidy) and one without a screen (ambient subsidy), near the shoreline of 2 small fishless ponds and sampled each month during the growing season in the southern Appalachian Mountains, Virginia (USA). Screens between water and land reduced the number of terrestrial arthropods that fell into screened enclosures relative to the number that fell into unscreened enclosures and open reference plots by 36%. The δ13C isotopic signatures of dragonfly larvae shifted towards those of aquatic prey in reduced-subsidy enclosures, a result suggesting that dragonflies consumed fewer terrestrial prey when fewer were available (ambient subsidy: 30%, reduced subsidy: 19% of diet). Overall abundance and biomass of dragonfly larvae did not change in response to reduced terrestrial arthropod inputs, despite the fact that enclosures permitted immigration/emigration. These results suggest that terrestrial arthropods can provide resources to aquatic predators in lentic systems, but that their effects on abundance and distribution might be subtle and confounded by in situ factors.

  2. Zooplankton assembly in mountain lentic waters is primarily driven by local processes

    Science.gov (United States)

    Tavernini, Silvia; Primicerio, Raul; Rossetti, Giampaolo

    2009-01-01

    The influence of local (i.e. physico-chemical constraints) and regional (i.e. dispersal) processes in determining the structure of zooplankton communities in lentic waters was analysed in a mountain district of 4500 km 2 (northern Apennines, Italy). In the 47 lakes and ponds considered in this study, a total of 139 taxa were found. Surface area (SA) and maximum depth ( Zmax) significantly influenced species richness and nestedness, stressing the importance of habitat availability for zooplankton diversity and composition. Species richness and nestedness did not correlate with site isolation, indicating low influence of dispersal for these community properties. A negative relationship between the similarity in species composition among sites and their mutual geographic distance was also found. The relative importance of different sources of compositional variation was quantified by direct ordination. Local environmental conditions (i.e. Zmax, altitude, pH and conductivity) accounted for 65.9 % of the variation in rotifer assemblages. The importance of environmental constraints in structuring zooplankton communities was best documented by the microcrustacean distribution in the study area, which was mainly correlated (73.4 % of the variation in the species data) with water ionic content, surface area and hydroperiod of the habitats. Although previous studies on processes shaping zooplankton assemblages that operate at different scales have yielded contrasting results, our data provide clear evidence for a major role of local constraints.

  3. Cyclic variations of gonad development of an air-breathing fish, Channa striata in the lentic and lotic environments

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    Nasim Al Mahmud

    2016-03-01

    Full Text Available Abstract The study was conducted to know the cyclic changes in gonadal maturation and to investigate the developmental stages of oocytes and testicular germ cells of an air-breathing fish, Channa striata. Fish were sampled monthly from lentic and lotic environments of three geographical locations of Bangladesh from December to November and the histological analysis of their gonad was done to evaluate the objectives. The highest mean GSI was 5.95 ± 0.20 for female in July and 0.14 ± 0.01 for male also in July showing that the gonadal development reached its peak during this month. The highest mean oocyte diameter was 1257.50 ± 24.17 μm observed in July implying that the oocyte reached maturity in this month. Histological study of ovary revealed the evidence of early yolk granule stage and late yolk granule stage from April to July. In case of male four stages of spermatogenesis were distinguished and spermatozoa were highly abundant in June and July. So the monthly pooled values of GSI and the analysis of gonadal histology indicated that the peak breeding season of C. striata occurred in July in the lentic and lotic environments. Samples collected from lentic and lotic habitats are suggestive of no difference in the development of the gonad. The results of the present study will be useful for selective breeding programme, conservation and sustainable fishery management of C. striata in its natural habitat.

  4. Cyanobacteria and cyanotoxins in freshwaters of Uruguay

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    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.

  5. First report of freshwater rotifers (Rotifera: Eurotatoria from south Andaman, India: Composition and interesting elements

    Directory of Open Access Journals (Sweden)

    Bhushan Kumar Sharma

    2017-06-01

    Full Text Available Plankton samples collected from freshwater lentic ecosystems of south Andaman, India, revealed 70 species of Rotifera belonging to 25 genera and 16 families. The reports of Australasian Lecane batillifer, Oriental endemic Lecane bulla diabolica and three Paleotropical species, and 68 new records of Eurotatoria from Andaman and Nicobar Islands contribute to biodiversity and biogeography of the Indian Rotifera. The rotifers are characterized by diverse Lecanidae>Lepadellidae>Brachionidae and common nature of species of “tropic-centered” Lecane and Brachionus. The occurrences of a large number of cosmopolitan species, and several tropicopolitan and pantropical species are notable. This report indicates a further scope for biodiversity update on these metazoans from the insular freshwater of Andaman and Nicobar Islands located in the Andaman Sea.

  6. Diatoms from lentic and lotic systems in Antioquia, Chocó and Santander Departments in Colombia

    Directory of Open Access Journals (Sweden)

    Silvia E Sala

    2008-09-01

    Full Text Available In the tropical and subtropical regions, there is a large number of species which has not been yet described. The high possibility of extinction makes their inventory a priority. In this paper, 23 diatoms taxa from Andean lotic systems and lentic waterbodies localized in the Departments of Antioquia, Santander and Chocó, Colombia, are analyzed with light and scanning electron microscopy. Each taxon is described and information about environmental characteristic of the sites where they were collected and distribution in Colombia is given. The studied taxa belong to the orders Thalassiosirales (1, Aulacoseirales (1, Fragilariales (4, Cymbellales (7, Achnanthales (2, Naviculales (7, and Thalassiophysales (1. Fifteen of them are recorded for the first time in Colombia and Encyonema jemtlandicum in South America. A comparison with the diatom flora of the Colombian Amazonia showed that there were only three taxa in common to these two equatorial regions probably due to the influence of altitudinal gradient. Rev. Biol. Trop. 56 (3: 1159-1178. Epub 2008 September 30.En este artículo se analizan con microscopios de luz y electrónico de barrido 23 taxones de diatomeas provenientes de sistemas lénticos y lóticos andinos localizados en los Departamentos de Antioquia, Santander y Chocó, Colombia. Cada taxon es descrito e ilustrado y se brinda información acerca de su distribución en Colombia y de las condiciones físicas y químicas en las que fueron colectados. Los taxones estudiados pertenecen a los órdenes Thalassiosirales (1, Aulacoseirales (1, Fragilariales (4, Cymbellales (7, Achnanthales (2, Naviculales (7 y Thalassiophysales (1. 15 de ellos son registrados por primera vez para Colombia y Encyonema jemtlandicum es primer registro para América del Sur. Una comparación con la flora diatomológica de la Amazonía Colombiana, mostró que únicamente 3 taxones fueron hallados en ambas regiones, probablemente debido a la influencia de los

  7. Spatial autocorrelation and dispersal limitation in freshwater organisms.

    Science.gov (United States)

    Shurin, Jonathan B; Cottenie, Karl; Hillebrand, Helmut

    2009-02-01

    Dispersal can limit the ranges of species and the diversity of communities. Despite its importance, little is known about its role in freshwater habitats and its relation to habitat type (lentic vs. lotic), especially for organisms with cryptic dispersal methods such as plankton. Poor dispersers are expected to show more clumped distributions or greater spatial autocorrelation (SA) in community composition than good dispersers. We examined patterns of SA across freshwater taxa with different dispersal modes (active vs. passive) and their association with habitat type (lake vs. stream) using 18 spatially explicit community composition data sets. We found significant relationships between SA and body size among taxa in lake habitats, but not in streams. However, the increase in SA with body size in lakes was driven entirely by fishes-organisms ranging in size from diatoms to macro-invertebrates showed equivalent levels of SA. These results support the idea that large organisms are less effective dispersers in aquatic environments, resulting in greater SA in community structure over broad scales. Streams may be effectively more connected than lakes as patterns of SA and body size were weaker in lotic habitats. Our data suggest that the critical threshold where greater body size increases dispersal limitation seems to come at the juncture between invertebrates and vertebrates rather than that between unicellular and multicellular organisms as has been previously suggested.

  8. Ecomorphological variation in shell shape of the freshwater turtle Pseudemys concinna inhabiting different aquatic flow regimes.

    Science.gov (United States)

    Rivera, Gabriel

    2008-12-01

    Populations of species that inhabit a range of environments frequently display divergent morphologies that correlate with differences in ecological parameters. The velocity of water flow (i.e., flow velocity) is a critical feature of aquatic environments that has been shown to influence morphology in a broad range of taxa. The focus of this study was to evaluate the relationship between flow velocity and shell morphology for males and females of the semi-aquatic freshwater turtle Pseudemys concinna. For both sexes, the carapace and plastron show significant morphological differences between habitats characterized by slow-flowing (i.e., lentic) and fast-flowing (i.e., lotic) water. In general, the most prominent pattern for both sexes is that the shells of individuals from lotic habitats are more streamlined (small height-to-length ratio) than the shells of individuals from lentic habitats. Of the two shell components (carapace and plastron), the carapace shows greater divergence between habitats, particularly for males. These results are consistent with adaptations to flow velocity, and suggest that variation in shape may be more constrained in females. I also provide empirical evidence for an adaptive benefit of the observed shape change (i.e., drag reduction) and a brief comment on the relative roles of genetic divergence and phenotypic plasticity in generating shape differences observed in this species.

  9. 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 ...

  10. Salinity structure of a tidal freshwater ecosystem under multiple tidal conditions, Mission River, TX, USA

    Science.gov (United States)

    Jones, A.; Befus, K. M.; Cardenas, M.; McClelland, J. W.; Moffett, K. B.

    2013-12-01

    The ecological health and integrity of coastal estuaries critically depends on the balance between the quantity, quality, and timing of freshwater inflow. This balance may be upset by subtle changes in numerous hydrologic conditions, including precipitation rates and frequencies, runoff conditions, and tides. Certain hydrologic conditions will create an abnormally long freshwater residence time in a lower river reach--on the order of months between episodic storms--which will drastically alter the quantity, quality, and timing of estuarine freshwater inflow. We term this fresh, tidal, lentic river reach the 'tidal freshwater ecosystem' (TFE) and find that it remains largely overlooked by hydrologic and estuarine sciences. We hypothesize that TFEs occur in coastal rivers with small bed slope and riverine discharge, enabling denser saltwater intruding inland via tidal motion to impede freshwater discharge to the estuary. However, the balance of forces governing the relative rates and volumes of freshwater discharge, saltwater intrusion, and freshwater-saltwater mixing are not well understood in TFEs, especially with regard to the influence of vertical salinity structure (whether stratified, well-mixed, or a combination) on the retardation of freshwater discharge. In this study we sought to empirically characterize the salinity structure of a river known to contain a tidal freshwater reach, the Mission River of southern Texas. During high and low spring and neap tides, we surveyed a ~ 22 km-long tidal section of the river by towing two instruments: a multi-parameter probe measuring temperature, electrical conductivity (EC), and dissolved oxygen (DO) at mid-channel depth; and, at the water surface, an electrical resistivity geophysical cable measuring water and channel bed sediment electrical resistivity. We also profiled the water column every 0.25 km using a second multi-parameter probe. The data successfully resolved longitudinal and vertical salinity variations

  11. Effect of wetland management: Are lentic wetlands refuges of plant-species diversity in the Andean-Orinoco Piedmont of Colombia?

    OpenAIRE

    Murillo-Pacheco, Johanna I.; Rös, Matthias; Escobar, Federico; Castro-Lima, Francisco; Verdú, José R.; Germán M. López-Iborra

    2016-01-01

    Accelerated degradation of the wetlands and fragmentation of surrounding vegetation in the Andean-Orinoco Piedmont are the main threats to diversity and ecological integrity of these ecosystems; however, information on this topic is of limited availability. In this region, we evaluated the value of 37 lentic wetlands as reservoirs of woody and aquatic plants and, analyzed diversity and changes in species composition within and among groups defined according to management given by: 1) type (sw...

  12. Effect of wetland management: are lentic wetlands refuges of plant-species diversity in the Andean–Orinoco Piedmont of Colombia?

    OpenAIRE

    Murillo-Pacheco, Johanna I.; Matthias Rös; Federico Escobar; Francisco Castro-Lima; Verdú, José R.; Germán M. López-Iborra

    2016-01-01

    Accelerated degradation of the wetlands and fragmentation of surrounding vegetation in the Andean–Orinoco Piedmont are the main threats to diversity and ecological integrity of these ecosystems; however, information on this topic is of limited availability. In this region, we evaluated the value of 37 lentic wetlands as reservoirs of woody and aquatic plants and analyzed diversity and changes in species composition within and among groups defined according to management given by: (1) type (sw...

  13. Areal Changes of Lentic Water Bodies Within an Agricultural Basin of the Argentinean Pampas. Disentangling Land Management from Climatic Causes

    Science.gov (United States)

    Booman, Gisel Carolina; Calandroni, Mirta; Laterra, Pedro; Cabria, Fabián; Iribarne, Oscar; Vázquez, Pablo

    2012-12-01

    Wetland loss is a frequent concern for the environmental management of rural landscapes, but poor disentanglement between climatic and land management causes frequently constrains both proper diagnoses and planning. The aim of this study is to address areal changes induced by non-climatic factors on lentic water bodies (LWB) within an agricultural basin of the Argentinean Pampas, and the human activities that might be involved. The LWB of the Mar Chiquita basin (Buenos Aires province, Argentina) were mapped using Landsat images from 1998-2008 and then corrected for precipitation variability by considering the regional hydrological status on each date. LWB areal changes were statistically and spatially analyzed in relation to land use changes, channelization of streams, and drainage of small SWB in the catchment areas. We found that 12 % of the total LWB in the basin had changed ( P changed size had decreased while 70 % showed steady increases in area. The number of altered LWB within watersheds lineally increased or decreased according to the proportion of grasslands replaced by sown pastures, or the proportion of sown pastures replaced by crop fields, respectively. Drainage and channelization do not appear to be related to the alteration of LWB; however some of these hydrologic modifications may predate 1998, and thus earlier effects cannot be discarded. This study shows that large-scale changes in land cover (e.g., grasslands reduction) can cause a noticeable loss of hydrologic regulation at the catchment scale within a decade.

  14. Are Vicinal Metal Surfaces Stable?

    DEFF Research Database (Denmark)

    Frenken, J. W. M.; Stoltze, Per

    1999-01-01

    We use effective medium theory to demonstrate that the energies of many metal surfaces are lowered when these surfaces are replaced by facets with lower-index orientations. This implies that the low-temperature equilibrium shapes of many metal crystals should be heavily faceted. The predicted ins...... instability of vicinal metal surfaces is at variance with the almost generally observed stability of these surfaces. We argue that the unstable orientations undergo a defaceting transition at relatively low temperatures, driven by the high vibrational entropy of steps....

  15. Biodiversity in South East Asia: an overview of freshwater sponges (Porifera: Demospongiae: Spongillina

    Directory of Open Access Journals (Sweden)

    Renata Manconi

    2013-08-01

    Full Text Available Despite the fact that South East (SE Asia is considered as a biodiversity hotspot, knowledge of sessile invertebrates such as freshwater sponges (Porifera: Haplosclerida: Spongillina in this region is poor and scarcely reported. For this synopsis, diversity and distribution of SE Asian inland water sponges is reported on the basis of available literature and a recent biodiversity assessment of the Lower Mekong basin. A diagnostic key of families/genera from SE Asia is provided together with Light Microscopy and Scanning Electron Microscopy protocols to prepare the basic spicular complement for taxonomic identification. So far, SE Asian freshwater sponges consist of widespread and/or endemic species belonging to the families Metaniidae, Potamolepidae, and Spongillidae. The highest diversity is recorded from Indonesia, Philippines, Thailand, and Myanmar, respectively. Data from the other countries are necessary for our understanding of their diversity and distribution. Biodiversity in SE Asia is strongly underestimated, as indicated by recent new records and the discovery of new species of freshwater sponges in Thailand. Further investigations should reveal higher values of taxonomic richness, highlighting biogeographic patterns at the family/genus/species levels. A cooperative network involving Thai, Laotian and Italian researchers, was set up to contribute and fulfil knowledge on taxonomy, ecology and biotechnological potentialities of these neglected filter feeders, playing a key role in water purification and biomass production in both lentic and lotic ecosystems in the tropics.

  16. Effect of wetland management: are lentic wetlands refuges of plant-species diversity in the Andean-Orinoco Piedmont of Colombia?

    Science.gov (United States)

    Murillo-Pacheco, Johanna I; Rös, Matthias; Escobar, Federico; Castro-Lima, Francisco; Verdú, José R; López-Iborra, Germán M

    2016-01-01

    Accelerated degradation of the wetlands and fragmentation of surrounding vegetation in the Andean-Orinoco Piedmont are the main threats to diversity and ecological integrity of these ecosystems; however, information on this topic is of limited availability. In this region, we evaluated the value of 37 lentic wetlands as reservoirs of woody and aquatic plants and analyzed diversity and changes in species composition within and among groups defined according to management given by: (1) type (swamps, heronries, rice fields, semi-natural lakes, constructed lakes and fish farms) and (2) origins (natural, mixed and artificial). A total of 506 plant species were recorded: 80% woody and 20% aquatic. Of these, 411 species (81%) were considered species typical of the area (Meta Piedmont distribution). Diversity patterns seem to be driven by high landscape heterogeneity and wetland management. The fish farms presented the highest diversity of woody plants, while swamps ranked highest for aquatic plant diversity. Regarding wetland origin, the artificial systems were the most diverse, but natural wetlands presented the highest diversity of typical species and can therefore be considered representative ecosystems at the regional scale. Our results suggest that lentic wetlands act as refuges for native vegetation of Meta Piedmont forest, hosting 55% of the woody of Piedmont species and 29% of the aquatic species of Orinoco basin. The wetlands showed a high species turnover and the results indicated that small wetlands (mean ± SD: size = 11 ± 18.7 ha), with a small area of surrounding forest (10 ± 8.6 ha) supported high local and regional plant diversity. To ensure long-term conservation of lentic wetlands, it is necessary to develop management and conservation strategies that take both natural and created wetlands into account.

  17. Effect of wetland management: are lentic wetlands refuges of plant-species diversity in the Andean–Orinoco Piedmont of Colombia?

    Science.gov (United States)

    Murillo-Pacheco, Johanna I.; Rös, Matthias; Castro-Lima, Francisco; Verdú, José R.; López-Iborra, Germán M.

    2016-01-01

    Accelerated degradation of the wetlands and fragmentation of surrounding vegetation in the Andean–Orinoco Piedmont are the main threats to diversity and ecological integrity of these ecosystems; however, information on this topic is of limited availability. In this region, we evaluated the value of 37 lentic wetlands as reservoirs of woody and aquatic plants and analyzed diversity and changes in species composition within and among groups defined according to management given by: (1) type (swamps, heronries, rice fields, semi-natural lakes, constructed lakes and fish farms) and (2) origins (natural, mixed and artificial). A total of 506 plant species were recorded: 80% woody and 20% aquatic. Of these, 411 species (81%) were considered species typical of the area (Meta Piedmont distribution). Diversity patterns seem to be driven by high landscape heterogeneity and wetland management. The fish farms presented the highest diversity of woody plants, while swamps ranked highest for aquatic plant diversity. Regarding wetland origin, the artificial systems were the most diverse, but natural wetlands presented the highest diversity of typical species and can therefore be considered representative ecosystems at the regional scale. Our results suggest that lentic wetlands act as refuges for native vegetation of Meta Piedmont forest, hosting 55% of the woody of Piedmont species and 29% of the aquatic species of Orinoco basin. The wetlands showed a high species turnover and the results indicated that small wetlands (mean ± SD: size = 11 ± 18.7 ha), with a small area of surrounding forest (10 ± 8.6 ha) supported high local and regional plant diversity. To ensure long-term conservation of lentic wetlands, it is necessary to develop management and conservation strategies that take both natural and created wetlands into account. PMID:27602263

  18. Effect of wetland management: are lentic wetlands refuges of plant-species diversity in the Andean–Orinoco Piedmont of Colombia?

    Directory of Open Access Journals (Sweden)

    Johanna I. Murillo-Pacheco

    2016-08-01

    Full Text Available Accelerated degradation of the wetlands and fragmentation of surrounding vegetation in the Andean–Orinoco Piedmont are the main threats to diversity and ecological integrity of these ecosystems; however, information on this topic is of limited availability. In this region, we evaluated the value of 37 lentic wetlands as reservoirs of woody and aquatic plants and analyzed diversity and changes in species composition within and among groups defined according to management given by: (1 type (swamps, heronries, rice fields, semi-natural lakes, constructed lakes and fish farms and (2 origins (natural, mixed and artificial. A total of 506 plant species were recorded: 80% woody and 20% aquatic. Of these, 411 species (81% were considered species typical of the area (Meta Piedmont distribution. Diversity patterns seem to be driven by high landscape heterogeneity and wetland management. The fish farms presented the highest diversity of woody plants, while swamps ranked highest for aquatic plant diversity. Regarding wetland origin, the artificial systems were the most diverse, but natural wetlands presented the highest diversity of typical species and can therefore be considered representative ecosystems at the regional scale. Our results suggest that lentic wetlands act as refuges for native vegetation of Meta Piedmont forest, hosting 55% of the woody of Piedmont species and 29% of the aquatic species of Orinoco basin. The wetlands showed a high species turnover and the results indicated that small wetlands (mean ± SD: size = 11 ± 18.7 ha, with a small area of surrounding forest (10 ± 8.6 ha supported high local and regional plant diversity. To ensure long-term conservation of lentic wetlands, it is necessary to develop management and conservation strategies that take both natural and created wetlands into account.

  19. Human activities cause distinct dissolved organic matter composition across freshwater ecosystems.

    Science.gov (United States)

    Williams, Clayton J; Frost, Paul C; Morales-Williams, Ana M; Larson, James H; Richardson, William B; Chiandet, Aisha S; Xenopoulos, Marguerite A

    2016-02-01

    Dissolved organic matter (DOM) composition in freshwater ecosystems is influenced by the interactions among physical, chemical, and biological processes that are controlled, at one level, by watershed landscape, hydrology, and their connections. Against this environmental template, humans may strongly influence DOM composition. Yet, we lack a comprehensive understanding of DOM composition variation across freshwater ecosystems differentially affected by human activity. Using optical properties, we described DOM variation across five ecosystem groups of the Laurentian Great Lakes region: large lakes, Kawartha Lakes, Experimental Lakes Area, urban stormwater ponds, and rivers (n = 184 sites). We determined how between ecosystem variation in DOM composition related to watershed size, land use and cover, water quality measures (conductivity, dissolved organic carbon (DOC), nutrient concentration, chlorophyll a), and human population density. The five freshwater ecosystem groups had distinctive DOM composition from each other. These significant differences were not explained completely through differences in watershed size nor spatial autocorrelation. Instead, multivariate partial least squares regression showed that DOM composition was related to differences in human impact across freshwater ecosystems. In particular, urban/developed watersheds with higher human population densities had a unique DOM composition with a clear anthropogenic influence that was distinct from DOM composition in natural land cover and/or agricultural watersheds. This nonagricultural, human developed impact on aquatic DOM was most evident through increased levels of a microbial, humic-like parallel factor analysis component (C6). Lotic and lentic ecosystems with low human population densities had DOM compositions more typical of clear water to humic-rich freshwater ecosystems but C6 was only present at trace to background levels. Consequently, humans are strongly altering the quality of DOM in

  20. 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.

  1. Habitat--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the habitat map of the seafloor of the Monterey Canyon and Vicinity map area, California. The vector data file is included in...

  2. Contours--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents bathymetric contours for several seafloor maps of the Monterey Canyon and Vicinity map area, California. The raster data file is...

  3. Environmental versus anthropogenic effects on population adaptive divergence in the freshwater snail Lymnaea stagnalis.

    Directory of Open Access Journals (Sweden)

    Anthony Bouétard

    Full Text Available Repeated pesticide contaminations of lentic freshwater systems located within agricultural landscapes may affect population evolution in non-target organisms, especially in species with a fully aquatic life cycle and low dispersal ability. The issue of evolutionary impact of pollutants is therefore conceptually important for ecotoxicologists. The impact of historical exposure to pesticides on genetic divergence was investigated in the freshwater gastropod Lymnaea stagnalis, using a set of 14 populations from contrasted environments in terms of pesticide and other anthropogenic pressures. The hypothesis of population adaptive divergence was tested on 11 life-history traits, using Q(ST-F(ST comparisons. Despite strong neutral differentiation (mean F(ST = 0.291, five adult traits or parameters were found to be under divergent selection. Conversely, two early expressed traits showed a pattern consistent with uniform selection or trait canalization, and four adult traits appeared to evolve neutrally. Divergent selection patterns were mostly consistent with a habitat effect, opposing pond to ditch and channel populations. Comparatively, pesticide and other human pressures had little correspondence with evolutionary patterns, despite hatching rate impairment associated with global anthropogenic pressure. Globally, analyses revealed high genetic variation both at neutral markers and fitness-related traits in a species used as model in ecotoxicology, providing empirical support for the need to account for genetic and evolutionary components of population response in ecological risk assessment.

  4. CROATIAN FRESHWATER FISHERY

    Directory of Open Access Journals (Sweden)

    Višnja Knjaz

    2007-07-01

    Full Text Available The basic characteristics of freshwater fishery in Croatia are predominantly negative trend in the past twenty years. Even though the total fish pond area covers more than 12,000 hectares, only 6,200 hectares of carp ponds and 58,700 m2 of trout ponds have been exploited. In 2006 the production of total freshwater fish reached 6,547 tons, out of which the production of consumable fish amounted to 5,067 tons and the juveniles 1,480 tons. The export of freshwater fish to EU countries, Macedonia, Bosnia and Herzegovina, Serbia and Monte Negro shows the positive trend and the Republic of Croatia continuously records a foreign trade surplus (987,000 US$. It must be pointed out, though, that the import of trout from Bosnia and Herzegovina significantly increased in the past three years which resulted in the decrease of the foreign trade surplus in that sector. The freshwater fishery in Croatia has been overly burdened by many problems

  5. Combating freshwater scarcity

    OpenAIRE

    Maheshwari, Ramesh

    2005-01-01

    Pushpangadan et al.1 have 'offered the idea of discovering and exploiting waterfixing/harvesting/synthesizing organisms from desert organisms or thermophilic bacteria' for combating freshwater scarcity in plants. Their idea is based on the false notion that 'certain living organisms (both flora and fauna) grow and thrive well in sand dunes of deserts like Sahara, but certain thermophilic bacteria and some higher forms of life have also been located in the sand dunes'. Further, they write,'Pla...

  6. 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

  7. Marine and freshwater toxins.

    Science.gov (United States)

    Hungerford, James M

    2006-01-01

    In a very busy and exciting year, 2005 included First Action approval of a much needed official method for paralytic shellfish toxins and multiple international toxin symposia highlighted by groundbreaking research. These are the first-year milestones and activities of the Marine and Freshwater Toxins Task Force and Analytical Community. Inaugurated in 2004 and described in detail in last year's General Referee Report (1) this international toxins group has grown to 150 members from many regions and countries. Perhaps most important they are now making important and global contributions to food safety and to providing alternatives to animal-based assays. Official Method 2005.06 was first approved in late 2004 by the Task Force and subsequently Official First Action in 2005 (2) by the Methods Committee on Natural Toxins and Food Allergens and the Official Methods Board. This nonproprietary method (3) is a precolumn oxidation, liquid chromatographic method that makes good use of fluorescence detection to provide high sensitivity detection of the saxitoxins. It has also proven to be rugged enough for regulatory use and the highest level of validation. As pointed out in the report of method principle investigator and Study Director James Lawrence, approval of 2005.06 now provides the first official alternative to the mouse bioassay after many decades of shellfish monitoring. This past year in April 2005 the group also held their first international conference, "Marine and Freshwater Toxins Analysis: Ist Joint Symposium and AOAC Task Force Meeting," in Baiona, Spain. The 4-day conference consisted of research and stakeholder presentations and symposium-integrated subgroup sessions on ciguatoxins, saxitoxin assays and liquid chromatography (LC) methods for saxitoxins and domoic acids, okadaiates and azaspiracids, and yessotoxins. Many of these subgroups were recently formed in 2005 and are working towards their goals of producing officially validated analytical methods

  8. Microbial Quality and Phylogenetic Diversity of Fresh Rainwater and Tropical Freshwater Reservoir

    OpenAIRE

    Rajni Kaushik; Rajasekhar Balasubramanian; Hugh Dunstan

    2014-01-01

    The impact of rainwater on the microbial quality of a tropical freshwater reservoir through atmospheric wet deposition of microorganisms was studied for the first time. Reservoir water samples were collected at four different sampling points and rainwater samples were collected in the immediate vicinity of the reservoir sites for a period of four months (January to April, 2012) during the Northeast monsoon period. Microbial quality of all fresh rainwater and reservoir water samples was assess...

  9. 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...

  10. Implications of Climate Change on the Heat Budget of Lentic Systems Used for Power Station Cooling: Case Study Clinton Lake, Illinois.

    Science.gov (United States)

    Quijano, Juan C; Jackson, P Ryan; Santacruz, Santiago; Morales, Viviana M; García, Marcelo H

    2016-01-05

    We use a numerical model to analyze the impact of climate change-in particular higher air temperatures-on a nuclear power station that recirculates the water from a reservoir for cooling. The model solves the hydrodynamics, the transfer of heat in the reservoir, and the energy balance at the surface. We use the numerical model to (i) quantify the heat budget in the reservoir and determine how this budget is affected by the combined effect of the power station and climate change and (ii) quantify the impact of climate change on both the downstream thermal pollution and the power station capacity. We consider four different scenarios of climate change. Results of simulations show that climate change will reduce the ability to dissipate heat to the atmosphere and therefore the cooling capacity of the reservoir. We observed an increase of 25% in the thermal load downstream of the reservoir, and a reduction in the capacity of the power station of 18% during the summer months for the worst-case climate change scenario tested. These results suggest that climate change is an important threat for both the downstream thermal pollution and the generation of electricity by power stations that use lentic systems for cooling.

  11. Cypermethrin toxicity to aquatic life: bioassays for the freshwater prawn Palaemonetes argentinus.

    Science.gov (United States)

    Collins, P; Cappello, S

    2006-07-01

    Cypermethrin (CY) effects were evaluated in freshwater prawn Palaemonetes argentinus, a common member of the aquatic fauna in the vegetated littoral of lotic and lentic environment of La Plata basin. LC50 was calculated, and oxygen uptakes together with ammonia-N excretion were related to biocide concentrations. Behavioral and growth changes were analyzed, and a unique application of CY was evaluated in P. argentinus micropopulations. LC50 and their 95% confidence limit were 0.0031 microg CY L(-1) (0.0023-0.0039) for 24 h and 0.0020 microg CY L(-1) (0.0014-0.0027) for 96 h. Oxygen uptake and ammonia-N excretion increased in the prawns kept in CY solutions. The behavioral effect was hyperactivity. Although prawns in biocide groups have null or negative growth, the intermolt period was 246% larger than in the control group. Moreover, the mortality in the second cycle was 100%. A unique application of pyrethoid provoked high mortality after 50 days. The low concentrations of this biocide affected the survival and altered the prawn metabolic activity, behavioral and ecdysis cycle. These results suggest that juveniles of P. argentinus are much more sensitive to CY pollution than other crustaceans, fish, and tadpoles.

  12. Host specificity, pathogenicity, and mixed infections of trypanoplasms from freshwater fishes.

    Science.gov (United States)

    Losev, Alexander; Grybchuk-Ieremenko, Anastasiia; Kostygov, Alexei Yu; Lukeš, Julius; Yurchenko, Vyacheslav

    2015-03-01

    This work summarizes the results of the 8-year study focused on Trypanoplasma sp. parasitizing freshwater fishes in the vicinity of Kyiv, Ukraine. Out of 570 fish specimens of 2 different species analyzed, 440 individuals were found to be infected. The prevalence of infection ranged from 24 % in Abramis brama Linnaeus (freshwater bream) to 100 % in Cobitis taenia Linnaeus (spined loach). The level of parasitemia also varied between moderate in freshwater bream and very high in spined loach. Interestingly, no clinical manifestations of trypanoplasmosis were observed even in extremely heavily infected C. taenia. We hypothesize that different species may differ in evolutionary timing allowing for reciprocal adaptation of the members of the "host-parasite" system. Molecular analysis of the 18S rRNA sequences revealed that several specimens were simultaneously infected with at least two different trypanoplasm species. To the best of our knowledge, this is the first report of the mixed infection with fish trypanoplasms.

  13. Self-assembled nanostructures on vicinal surfaces

    Science.gov (United States)

    Petrovykh, Dmitri Yourievich

    2000-10-01

    One of the first methods for visualizing crystal planes and atomic steps has been step decoration with gold on alkali-halide surfaces. An impressive body of work has been conducted since then on the role of steps in controlling surface diffusion and adsorption rates, catalytic and chemical activity, and other physical and chemical surface properties. Due to these special characteristics, vicinal surfaces offer an approach for creating self-assembled structures with one or more dimensions on nanometer scale. The storage and communications industries have been revolutionized by applications of two-dimensional electron gas confined in thin films, so an interest in one and zero-dimensional systems is not surprising. This work demonstrates how macroscopic amounts of low-dimensional structures can be produced by self-assembly using stepped surfaces as nanometer-scale templates. High-quality templates of step arrays can be prepared on vicinal Si(111) surfaces. Sub-monolayer CaF2/Si(111) heteroepitaxial growth is examined in a series of experiments. A new growth mode is observed in addition to the ones typical in three dimensions. With increasing coverage, the growth front changes from rough to smooth geometry, driven by the elastic interactions between the multiple growth fronts and the surface steps. The mechanism is thus unique to the two-dimensional growth on stepped surfaces. The possible arrangements of the CaF2 self-assembled nanostructures are arrays of stripes or islands, both interesting as potential masks for silicon nanolithography. Anisotropic surface reconstructions, such as Ca and Au induced 3 x 1 and 5 x 2 on Si(111), are effectively self-assembled one-dimensional atomic chains. Reconstructions are single-domain on vicinal surfaces and with odd electron count a metallic one-dimensional state is expected in both the above examples. However in angular-resolved photoemission both appear as semiconductors, and Au-Si(111)5 x 2 exhibits a continuous one

  14. Quantitative fidelity of recent freshwater mollusk assemblages from the Touro Passo River, Rio Grande do Sul, Brazil Fidelidade quantitativa de associações de moluscos límnicos recentes na bacia do rio Touro Passo, Rio Grande do Sul, Brasil

    Directory of Open Access Journals (Sweden)

    Alcemar R. Martello

    Full Text Available This study represents one of the first contributions to the knowledge on the quantitative fidelity of the recent freshwater molluscan assemblages in subtropical rivers. Thanatocoenoses and biocoenoses were studied in straight and meandering to braided sectors, in the middle course of the Touro Passo River, a fourth-order tributary of the Uruguay River, located in the westernmost part of the State of Rio Grande do Sul. Samplings were carried out through quadrats of 5 m², five in each sector. A total area of 50 m² was sampled. Samplings were also made in a lentic environment (abandoned meander, with intermittent communication with the Touro Passo River, aiming to record out-of-habitat shell transportation from the lentic communities to the main river channel. The results show that, despite the frequent oscillation of the water level, the biocoenosis of the Touro Passo River shows high ecological fidelity and undergoes little influence from the lentic vicinal environments. The taxonomic composition and some features of the structure of communities, especially the dominant species, also reflect some ecological differences between the two main sectors sampled, such as the complexity of habitats in the meandering-sector. Regarding the quantitative fidelity, 60% of the species found alive were also found dead and 47.3% of the species found dead were also found alive, at river-scale. However, 72% of the dead individuals belong to species also found alive. This value might be related with the good rank order correlation obtained for live/dead assemblages. Consequently, the dominant species of the thanatocoenoses could be used to infer the ecological attributes of the biocoenoses. The values of all the indexes analyzed were very variable in small-scale samplings (quadrat, but were more similar to others registered in previous studies, when they were analyzed in a station and river scale.O presente estudo teve como objetivo apresentar uma das primeiras

  15. 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...

  16. Salting our freshwater lakes

    Science.gov (United States)

    Bartlett, Sarah L.; Burke, Samantha M.; Doubek, Jonathan P.; Krivak-Tetley, Flora E.; Skaff, Nicholas K.; Summers, Jamie C.; Farrell, Kaitlin J.; McCullough, Ian M.; Morales-Williams, Ana M.; Roberts, Derek C.; Ouyang, Zutao; Scordo, Facundo; Hanson, Paul C.; Weathers, Kathleen C.

    2017-01-01

    The highest densities of lakes on Earth are in north temperate ecosystems, where increasing urbanization and associated chloride runoff can salinize freshwaters and threaten lake water quality and the many ecosystem services lakes provide. However, the extent to which lake salinity may be changing at broad spatial scales remains unknown, leading us to first identify spatial patterns and then investigate the drivers of these patterns. Significant decadal trends in lake salinization were identified using a dataset of long-term chloride concentrations from 371 North American lakes. Landscape and climate metrics calculated for each site demonstrated that impervious land cover was a strong predictor of chloride trends in Northeast and Midwest North American lakes. As little as 1% impervious land cover surrounding a lake increased the likelihood of long-term salinization. Considering that 27% of large lakes in the United States have >1% impervious land cover around their perimeters, the potential for steady and long-term salinization of these aquatic systems is high. This study predicts that many lakes will exceed the aquatic life threshold criterion for chronic chloride exposure (230 mg L−1), stipulated by the US Environmental Protection Agency (EPA), in the next 50 y if current trends continue. PMID:28396392

  17. Ecology of Juvenile Salmon in Shallow Tidal Freshwater Habitats of the Lower Columbia River, 2007–2010

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Gary E.; Storch, Adam; Skalski, J. R.; Bryson, Amanda J.; Mallette, Christine; Borde, Amy B.; Van Dyke, E.; Sobocinski, Kathryn L.; Sather, Nichole K.; Teel, David; Dawley, Earl M.; Ploskey, Gene R.; Jones, Tucker A.; Zimmerman, Shon A.; Kuligowski, D. R.

    2011-03-01

    The TFM study was designed to investigate the ecology and early life history of juvenile salmonids within shallow (<5 m) tidal freshwater habitats of the LCRE. We started collecting field data in June 2007. Since then, monthly sampling has occurred in the vicinity of the Sandy River delta (rkm 192–208) and at other sites and times in lower river reaches of tidal freshwater (rkm 110 to 141). This report provides a comprehensive synthesis of data covering the field period from June 2007 through April 2010.

  18. Determining the energetics of vicinal perovskite oxide surfaces

    NARCIS (Netherlands)

    Wessels, W.A.; Bollmann, Tjeerd Rogier Johannes; Koster, Gertjan; Zandvliet, Henricus J.W.; Rijnders, Augustinus J.H.M.

    2017-01-01

    The energetics of vicinal SrTiO3(001) and DyScO3(110), prototypical perovskite vicinal surfaces, has been studied using topographic atomic force microscopy imaging. The kink formation and strain relaxation energies are extracted from a statistical analysis of the step meandering. Both perovskite

  19. Progress and challenges in freshwater conservation planning

    CSIR Research Space (South Africa)

    Nel, JL

    2009-06-01

    Full Text Available Freshwater ecosystems and their associated biota are among the most endangered in the world. This, combined with escalating human pressure on water resources, demands that urgent measures be taken to conserve freshwater ecosystems and the services...

  20. 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...

  1. Susceptibility of 7 freshwater gastropod species in Zimbabwe to infection with Gastrodiscus aegyptiacus (Cobbold, 1876) Looss, 1896 : short communication

    OpenAIRE

    S. Mukaratirwa; I.F. Munjere; M. Takawira; G. Chingwena

    2004-01-01

    Gastrodiscosis outbreaks due to Gastrodiscus aegyptiacus were recorded in horses in the vicinity of Harare, Zimbabwe, in the absence of Bulinus forskalii, B. senegalensis and Cleopatra sp. which are considered to be the only intermediate host snails. This suggested the possibility of other snail species acting as intermediate hosts in the life cycle of the trematode. A study was carried out to determine the susceptibility of 7 freshwater snail species to infection with G. aegyptiacus. First g...

  2. Effect of water chemistry on the planktonic communities and relationships among food web components across a freshwater ecotone

    Directory of Open Access Journals (Sweden)

    Mieczan T.

    2013-01-01

    Full Text Available Most ecological research on the food web has been focused more on the pelagic zone than on the transitional zone - ecotones between lentic and lotic habitats. The specific goals of this study were to determine whether the contact zone of waters differs in hydrochemical and biological terms from the waters of the canal and the open water zone, and to evaluate the influence of particular macro-habitats on the interactions between components of the planktonic food web. The distribution of samples in ordination space led us to conclude that the studied habitats are distributed along the rising gradient of total organic carbon and nutrients. Assemblages of all investigated groups showed a strong compositional gradient correlated with conductivity and total phosphorus, while a second strong gradient in species composition was explained by nitrate nitrogen and/or phosphate concentrations. The analysis of trophic relationships in the system bacteriaciliates- crustaceans reveals a clear differentiation and strength of mutual relations between the analyzed zones. The highest number of significant correlations was determined in the contact zone. It can also be a place of very efficient matter and energy flow in freshwater ecosystems.

  3. 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…

  4. Arctic freshwater export: Status, mechanisms, and prospects

    NARCIS (Netherlands)

    Haine, T.W.N.; Curry, B.; Gerdes, R.; Hansen, E.; Karcher, M.; Lee, C.; Rudels, B.; Spreen, G.; de Steur, L.; Stewart, K.D.; Woodgate, R.

    2015-01-01

    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

  5. High prevalence of trypanosome co-infections in freshwater fishes.

    Science.gov (United States)

    Grybchuk-Ieremenko, Anastasiia; Losev, Alexander; Kostygov, Alexei Yu; Lukeš, Julius; Yurchenko, Vyacheslav

    2014-12-01

    One thousand three hundred seventy three fish specimens of eight different species from the vicinity of Kyiv, Ukraine, were examined for the presence of trypanosomes and 921 individuals were found to be infected. The prevalence of infection ranged from 24% in freshwater bream, Abramis brama (Linnaeus), to 100% in spined loach, Cobitis 'taenia' Linnaeus. The level of parasitaemia also varied significantly between generally mild infections in pikeperch, Sander lucioperca (Linnaeus), and heavy ones in C. 'taenia'. In most cases the infections with trypanosomes were asymptomatic. Cases of co-infection with species of Trypanoplasma Laveran et Mesnil, 1901 were documented for five out of eight examined host species. Molecular analysis of the 18S rDNA sequences revealed that four hosts, namely northern pike, Esox lucius Linnaeus, freshwater bream, spined loach and European perch, Perca fluviatilis Linnaeus, were simultaneously infected with two different trypanosome species. Our findings advocate the view that to avoid the risk posed by mixed infections, subsequent molecular taxonomic studies should be performed on clonal lines derived from laboratory cultures of fish trypanosomes.

  6. Caribbean brackish and freshwater Cyanophyceae

    NARCIS (Netherlands)

    Koster, Joséphine Th.

    1960-01-01

    Among the extensive collections of algae made by Dr P. Wagenaar Hummelinck (Utrecht) in the Antilles and adjacent regions during the years 1930, 1936, 1937, 1948—1949, 1955, a number of chiefly brackish, but also freshwater, Cyanophyceae were incorporated. This collection was kindly committed for

  7. Nearctic freshwater tardigrades: a review

    Directory of Open Access Journals (Sweden)

    Juliana G. HINTON

    2007-09-01

    Full Text Available The distribution and ecology of limno-terrestrial Tardigrada in the Nearctic realm remain poorly known. This is especially true of freshwater tardigrades (i.e., species found in permanently submerged habitats, which have received much less attention than terrestrial species. We reviewed the literature on Nearctic freshwater tardigrades. Of 204 Nearctic limno-terrestrial tardigrade species, 44 have been collected from sediments and aquatic vegetation of streams, rivers, ponds, lakes, groundwater and cryoconite holes. Of these, 17 are hydrophilous species found exclusively or primarily in aquatic environments. Most of the remainder are probably washed in accidentally from terrestrial substrates. Among the hydrophilous species, five are endemic to the Nearctic realm and three cosmopolitan. Hypsibius dujardini is the most widely-distributed hydrophilous species. There are no regional collections of Nearctic freshwater tardigrades comparable to those for terrestrial species. Aquatic tardigrades are benthic, and are found in sediments and on aquatic vegetation. Hypsibius dujardini and other widespread species are found in both substrates, and there is thus no evidence of substrate specificity. Numerically, tardigrades usually comprise a minor component of benthic invertebrate communities. Nothing is known of their trophic relationships or dispersal in these habitats. The density of Nearctic freshwater tardigrade species peaks in the spring and/or fall. Future research should increase the spatial and temporal scale of study, and employ adequate replication.

  8. Methane emission from freshwater marshes

    NARCIS (Netherlands)

    Nat, Frans-Jaco Willy Anthony van der

    2000-01-01

    This thesis describes the results of a four-year study into the CH4 cycle of freshwater marshes dominated by reed and bulrush. This research was conducted in the framework of the research theme carbon and nutrient dynamics in vegetated littoral systems of the department of Littoral Vegetation of

  9. From vicinal to rough crystal surfaces

    Science.gov (United States)

    Balibar, S.; Guthmann, C.; Rolley, E.

    1993-06-01

    One generally expects the properties of a vicinal surface to be independent of the existence of steps as soon as these steps overlap, i.e. when their mutual distance is smaller than their width. By using the roughening theory by Nozières and Gallet [1], we show that, at least for surfaces weakly coupled to the lattice, this overlap occurs for distances significantly larger than the commonly defined width. Our prediction is supported by an analysis of the various measurements of the angular variation of the surface stiffness of helium crystals, which were performed by Wolf et al. [2], Andreeva et al. [3] and Babkin et al. [4]. As a consequence, the interaction between crystal steps should be studied on vicinal surfaces with a much smaller tilt angle than previously thought. This article is also an opportunity to return to the relation between the step width and the correlation length on smooth surfaces, as well as to the treatment of the various finite size effects which occur in the problem of roughening. We finally reconsider how the weak coupling hypothesis applies to the case of helium crystals. On s'attend généralement à ce que les propriétés d'une surface vicinale ne soient plus contrôlées par l'existence des marches lorsque celles-ci se recouvrent, donc lorsque leur distance mutuelle devient inférieure à leur largeur. En reprenant la théorie de la transition rugueuse élaborée par Nozières et Gallet [1], nous montrons que, pour des surfaces faiblement couplées au réseau cristallin, ce recouvrement doit se produire pour des distances nettement plus grandes que la largeur (telle qu'elle est habituellement définie). Notre prédiction est confirmée par l'analyse des différentes mesures de la variation angulaire de la rigidité de surface des cristaux d'hélium réalisées par Wolf et al. [2], Andreeva et al. [3] and Babkin et al. [4]. Il s'ensuit que l'étude de l'interaction entre marches cristallines doit être effectuée sur des surfaces

  10. Faults--Drakes Bay and Vicinity Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data of faults for the geologic and geomorphologic map of the Drakes Bay and Vicinity map area, California. The vector data file is...

  11. BackscatterB [EM300]--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Monterey Canyon and Vicinity map area, California. Backscatter data are provided as separate...

  12. BackscatterC [7125]--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Monterey Canyon and Vicinity map area, California. Backscatter data are provided as separate...

  13. Folds--Monterey Canyon and Vicinity Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the folds for the geologic and geomorphic map of Monterey Canyon and Vicinity, California. The vector data file is included in...

  14. Backscatter A [8101]--Drakes Bay and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Drakes bay and Vicinity map area, California. Backscatter data are provided as separate grids...

  15. Backscatter C [7125]--Drakes Bay and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Drakes bay and Vicinity map area, California. Backscatter data are provided as separate grids...

  16. Faults--Monterey Canyon and Vicinity Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the faults for the geologic and geomorphic map of Monterey Canyon and Vicinity, California. The vector data file is included in...

  17. establishment of background radiation dose rate in the vicinity

    African Journals Online (AJOL)

    nb

    .ac.tz). *Permanent address: Department of Physics, University of Dodoma. P. O. Box 339 Dodoma. ABSTRACT. The absorbed dose rate in air in the vicinity of the proposed Manyoni uranium mining project located in Singida region, Tanzania, ...

  18. Folds--Drakes Bay and Vicinity Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data of folds for the geologic and geomorphologic map of the Drakes Bay and Vicinity map area, California. The vector data file is...

  19. Paleoshorelines--Monterey Canyon and Vicinity Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the paleoshorelines for the geologic and geomorphic map of Monterey Canyon and Vicinity, California. The vector data file is...

  20. Aerial survey of sea otters in the Cordova vicinity

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The movement of significantly large numbers of sea otters into the Cordova vicinity has generated a local storm of protest concerning the ability of sea otters to...

  1. 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...

  2. Submesoscale Dispersion in the Vicinity of the Deepwater Horizon Spill

    Science.gov (United States)

    2014-09-02

    RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) 11-03-2014 Journal Article Submesoscale dispersion in the vicinity of the Deepwater ...ecosystems, society, and the economy as evidenced by the Deepwater Horizon oil spill in the Gulf of Mexico in 2010 and the Fukushima nuclear plant...vicinity of the Deepwater Horizon spill Andrew C. Pojea, Tamay M. Özgökmenb,1, Bruce L. Lipphardt, Jr.c, Brian K. Hausb, Edward H. Ryanb, Angelique C

  3. Lentic Basommatophora molluscs and hygrophilous land snails as indicators of habitat and climate in the Early-Middle Pleistocene (0.78 Ma) at the site of Gesher Benot Ya'aqov (GBY), Israel.

    Science.gov (United States)

    Mienis, H K; Ashkenazi, S

    2011-04-01

    The lentic Basommatophora molluscs and hygrophilous land snails of the Early-Middle Pleistocene site of Gesher Benot Ya'aqov (GBY), 0.78 Ma, crossed by the Matuyama-Brunhes chron boundary [MBB] were studied in order to reconstruct their specific habitats and possible reactions to climate change along the site sequence. Samples of equal sizes from 27 of the 46 layers along the 100 k.yr. time-span of the site were examined. About 2000 specimens of 21 lentic and hygrophilous species belonging to five families: Planorbidae (11), Lymnaeidae (6), Acroloxidae (2), Carychiidae (1) and Succineidae (1) were identified. The family with the largest biodiversity is the Planorbidae and of these, the most abundant species include Gyraulus piscinarum (937), Planorbarius corneus (210) and Radix labiata (160). The recent known zoogeographic origin of 81% of the species is Palaearctic and Holarctic. The MBB coincides with remarkable environmental changes reflected in molluscs, other faunal and floral elements and stable isotopes. The Planorbidae and Lymnaeidae reach greater abundance (90% and 80% of their assemblages, respectively) pre-MBB, while Acroloxidae, Succineidae and Carychiidae are more abundant (74%, 64% and 90%) post-MBB. Our data indicate that GBY molluscs show a two-phase pattern (shallow and deep lake) in each of the five defined cycles. Their numbers increase during the shallow water phases, thus the site climate changes from cold and humid in the oldest layers, to dry and cold up to the MBB and few succeeding layers. Between cycles 2 and 3, post-MBB, we see a short period of warm and humid climate that enables the influx of African and Asian elements. At the same time, cold climate species of Euro-Siberian and Palaearctic origin disappear. The succeeding layers indicate a cooler and humid climate. Finally, the sequence indicates deep water in the oldest layers and desiccation towards MBB and deeper water post-MBB. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. MAJOR OIL PLAYS IN UTAH AND VICINITY

    Energy Technology Data Exchange (ETDEWEB)

    Thomas C. Chidsey; Craig D. Morgan; Kevin McClure; Grant C. Willis

    2003-09-01

    Arizona. Outcrop analogs are found in the stratigraphically equivalent Navajo Sandstone of southern Utah which displays large-scale dunal cross-strata with excellent reservoir properties and interdunal features such as oases, wadi, and playa lithofacies with poor reservoir properties. Hydrocarbons in the Paradox Formation are stratigraphically trapped in carbonate buildups (or phylloid-algal mounds). Similar carbonate buildups are exposed in the Paradox along the San Juan River of southeastern Utah. Reservoir-quality porosity may develop in the types of facies associated with buildups such as troughs, detrital wedges, and fans, identified from these outcrops. When combined with subsurface geological and production data, these outcrop analogs can improve (1) development drilling and production strategies such as horizontal drilling, (2) reservoir-simulation models, (3) reserve calculations, and (4) design and implementation of secondary/tertiary oil recovery programs and other best practices used in the oil fields of Utah and vicinity. During this quarter, technology transfer activities consisted of exhibiting the project plans, objectives, and products at a booth at the 2003 annual convention of the American Association of Petroleum Geologists. The project home page was updated on the Utah Geological Survey Internet web site.

  5. The Freshwater Information Platform - an online network supporting freshwater biodiversity research and policy

    Science.gov (United States)

    Schmidt-Kloiber, Astrid; De Wever, Aaike; Bremerich, Vanessa; Strackbein, Jörg; Hering, Daniel; Jähnig, Sonja; Kiesel, Jens; Martens, Koen; Tockner, Klement

    2017-04-01

    Species distribution data is crucial for improving our understanding of biodiversity and its threats. This is especially the case for freshwater environments, which are heavily affected by the global biodiversity crisis. Currently, a huge body of freshwater biodiversity data is often difficult to access, because systematic data publishing practices have not yet been adopted by the freshwater research community. The Freshwater Information Platform (FIP; www.freshwaterplatform.eu) - initiated through the BioFresh project - aims at pooling freshwater related research information from a variety of projects and initiatives to make it easily accessible for scientists, water managers and conservationists as well as the interested public. It consists of several major components, three of which we want to specifically address: (1) The Freshwater Biodiversity Data Portal aims at mobilising freshwater biodiversity data, making them online available Datasets in the portal are described and documented in the (2) Freshwater Metadatabase and published as open access articles in the Freshwater Metadata Journal. The use of collected datasets for large-scale analyses and models is demonstrated in the (3) Global Freshwater Biodiversity Atlas that publishes interactive online maps featuring research results on freshwater biodiversity, resources, threats and conservation priorities. Here we present the main components of the FIP as tools to streamline open access freshwater data publication arguing this will improve the capacity to protect and manage freshwater biodiversity in the face of global change.

  6. The freshwater reservoir effect in radiocarbon dating

    OpenAIRE

    Philippsen, Bente

    2012-01-01

    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 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 a...

  7. The freshwater reservoir effect in radiocarbon dating

    DEFF Research Database (Denmark)

    Philippsen, Bente

    2013-01-01

    effect on radiocarbon dating in an estuarine environment is examined. Here, freshwater influence causes reservoir ages to vary between 250 and 700 14C years during the period 5400 BC - AD 700. The examples in this study show clearly that the freshwater reservoir effect can seriously corrupt radiocarbon...... for radiocarbon dating of Mesolithic pottery from inland sites of the Ertebølle culture in Northern Germany. The surprisingly old ages of the earliest pottery most probably are caused by a freshwater reservoir effect. In a sediment core from the Limfjord, northern Denmark, the impact of the freshwater reservoir...

  8. Major Oil Plays in Utah and Vicinity

    Energy Technology Data Exchange (ETDEWEB)

    Thomas C. Chidsey; Craig D. Morgan; Kevin McClure; Douglas A. Sprinkel; Roger L. Bon; Hellmut H. Doelling

    2003-12-31

    fractured and sealed by overlying argillaceous and non-fractured units. The best outcrop analogs for Twin Creek reservoirs are found at Devils Slide and near the town of Peoa, Utah, where fractures in dense, homogeneous non-porous limestone beds are in contact with the basal siltstone units (containing sealed fractures) of the overlying units. The shallow marine, Mississippian Leadville Limestone is a major oil and gas reservoir in the Paradox Basin of Utah and Colorado. Hydrocarbons are produced from basement-involved, northwest-trending structural traps with closure on both anticlines and faults. Excellent outcrops of Leadville-equivalent rocks are found along the south flank of the Uinta Mountains, Utah. For example, like the Leadville, the Mississippian Madison Limestone contains zones of solution breccia, fractures, and facies variations. When combined with subsurface geological and production data, these outcrop analogs can improve (1) development drilling and production strategies such as horizontal drilling, (2) reservoir-simulation models, (3) reserve calculations, and (4) design and implementation of secondary/tertiary oil recovery programs and other best practices used in the oil fields of Utah and vicinity. In the southern Green River Formation play of the Uinta Basin, optimal drilling, development, and production practices consist of: (1) owning drilling rigs and frac holding tanks; (2) perforating sandstone beds with more than 8 percent neutron porosity and stimulate with separate fracture treatments; (3) placing completed wells on primary production using artificial lift; (4) converting wells relatively soon to secondary waterflooding maintaining reservoir pressure above the bubble point to maximize oil recovery; (5) developing waterflood units using an alternating injector--producer pattern on 40-acre (16-ha) spacing; and (6) recompleting producing wells by perforating all beds that are productive in the waterflood unit. As part of technology transfer

  9. Tentacle structure in freshwater bryozoans.

    Science.gov (United States)

    Tamberg, Yuta; Shunatova, Natalia

    2017-05-01

    Tentacles are the main food-gathering organs of bryozoans. The most common design is a hollow tube of extracellular matrix (ECM), covered with ten columns of epithelial cells on the outside, and a coelothelium on the inside. Nerves follow the ECM, going between the bases of some epidermal cells. The tentacle musculature includes two bundles formed by myoepithelial cells of the coelothelium. The tentacles of freshwater (phylactolaemate) bryozoans, however, differ somewhat in structure from those of marine bryozoans. Here, we describe the tentacles of three species of phylactolaemates, comparing them to gymnolaemates and stenolaemates. Phylactolaemate tentacles tend to be longer, and with more voluminous coeloms. The composition of the frontal cell row and the number of frontal nerves is variable in freshwater bryozoans, but constant in marine groups. Abfrontal cells form a continuous row in Phylactolaemata, but occur intermittently in other two classes. Phylactolaemata lack the microvillar cuticle reported in Gymnolaemata. Abfrontal sensory tufts are always composed of pairs of mono- and/or biciliated cells. This arrangement differs from individual abfrontal ciliary cells of other bryozoans: monociliated in Stenolaemata and monociliated and multiciliated ones in Gymnolaemata. In all three groups, however, ciliated abfrontal cells probably serve as mechanoreceptors. We confirm previously described phylactolemate traits: an unusual arrangement of two-layered coelothelium lining the lateral sides of the tentacle and oral slits in the intertentacular membrane. As previously reported, tentacle movements involved in feeding differ between bryozoan groups, with phylactolaemates tending to have slower movements than both gymnolaemates and stenolaemates, and a narrower behavioral repertoire than gymnolaemates. The morphological and ultrastructural differences between the freshwater species we studied and marine bryozoans may be related to these functional differences. Muscle

  10. 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.

  11. 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...

  12. Freshwater Ecology. LC Science Tracer Bullet.

    Science.gov (United States)

    Niskern, Diana, Comp.

    Freshwater ecosystems include lakes, ponds, streams, rivers, and certain types of wetlands. This literature and resources guide is not intended to be a comprehensive bibliography on freshwater ecology; the guide is designed--as the name of the series implies--to put the reader or student "on target." Other literature guides related to…

  13. 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)

  14. 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....

  15. Terrestrial freshwater lenses: Unexplored subterranean oases

    Science.gov (United States)

    Laattoe, Tariq; Werner, Adrian D.; Woods, Juliette A.; Cartwright, Ian

    2017-10-01

    Freshwater lenses are lenticular bodies of fresh (TDS lenses in coastal aquifers, the formation, location and persistence of freshwater lenses in terrestrial settings are poorly understood. This is despite inland aquifers commonly containing saline groundwater, particularly in arid and semi-arid climates, and the local occurrences of freshwater being critical for ecosystems and human endeavour. We identify and classify known terrestrial freshwater lenses (TFLs) using four formation categories, namely topography, geology, groundwater-surface water interaction and recharge mechanisms. The resulting typology highlights the importance of buoyancy in the formation of TFLs in otherwise unlikely situations, implying that TFLs may be more prevalent than previously thought. TFLs represent some of the most vulnerable and precious freshwater resources on Earth that require considerably more research into mechanisms of formation and threats to their existence.

  16. Freshwater to seawater transitions in migratory fishes

    Science.gov (United States)

    Zydlewski, Joseph D.; Michael P. Wilkie,

    2012-01-01

    The transition from freshwater to seawater is integral to the life history of many fishes. Diverse migratory fishes express anadromous, catadromous, and amphidromous life histories, while others make incomplete transits between freshwater and seawater. The physiological mechanisms of osmoregulation are widely conserved among phylogenetically diverse species. Diadromous fishes moving between freshwater and seawater develop osmoregulatory mechanisms for different environmental salinities. Freshwater to seawater transition involves hormonally mediated changes in gill ionocytes and the transport proteins associated with hypoosmoregulation, increased seawater ingestion and water absorption in the intestine, and reduced urinary water losses. Fishes attain salinity tolerance through early development, gradual acclimation, or environmentally or developmentally cued adaptations. This chapter describes adaptations in diverse taxa and the effects of salinity on growth. Identifying common strategies in diadromous fishes moving between freshwater and seawater will reveal the ecological and physiological basis for maintaining homeostasis in different salinities, and inform efforts to conserve and manage migratory euryhaline fishes.

  17. Bathymetry of the Republic of the Marshall Islands and vicinity

    Science.gov (United States)

    Hein, James R.; Wong, Florence L.; Mosier, Dan L.

    1999-01-01

    The bathymetric map of the Republic of the Marshall Islands and vicinity is bounded by a window of latitude 3 to 17 degrees North, longitude 153 to 175 degrees East. The map was compiled from surveys conducted by the USGS, Korean Ocean Research and Development Institute, and published gridded data. In addition to national jurisdictions, island and atoll coastlines are indicated on the map.

  18. Chemo- and Regioselective Oxidation of Secondary Alcohols in Vicinal Diols

    NARCIS (Netherlands)

    Eisink, Niek; Minnaard, Adriaan; Witte, Martin

    Oxidation of secondary hydroxyl groups in vicinal diols enables the straightforward functionalization of biomolecules and biomaterials. The resulting hydroxy ketone can for example be used to form derivatives, such as the epimeric alcohol and imines, and it may be employed for chemical probe

  19. 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.

  20. Novel Synechococcus Genomes Reconstructed from Freshwater Reservoirs

    Science.gov (United States)

    Cabello-Yeves, Pedro J.; Haro-Moreno, Jose M.; Martin-Cuadrado, Ana-Belen; Ghai, Rohit; Picazo, Antonio; Camacho, Antonio; Rodriguez-Valera, Francisco

    2017-01-01

    Freshwater picocyanobacteria including Synechococcus remain poorly studied at the genomic level, compared to their marine representatives. Here, using a metagenomic assembly approach we discovered two novel Synechococcus sp. genomes from two freshwater reservoirs Tous and Lake Lanier, both sharing 96% average nucleotide identity and displaying high abundance levels in these two lakes located at similar altitudes and temperate latitudes. These new genomes have the smallest estimated size (2.2 Mb) and average intergenic spacer length (20 bp) of any previously sequenced freshwater Synechococcus, which may contribute to their success in oligotrophic freshwater systems. Fluorescent in situ hybridization confirmed that Synechococcus sp. Tous comprises small cells (0.987 ± 0.139 μm length, 0.723 ± 0.119 μm width) that amount to 90% of the picocyanobacteria in Tous. They appear together in a phylogenomic tree with Synechococcus sp. RCC307 strain, the main representative of sub-cluster 5.3 that has itself one of the smallest marine Synechococcus genomes. We detected a type II phycobilisome (PBS) gene cluster in both genomes, which suggests that they belong to a phycoerythrin-rich pink low-light ecotype. The decrease of acidic proteins and the higher content of basic transporters and membrane proteins in the novel Synechococcus genomes, compared to marine representatives, support their freshwater specialization. A sulfate Cys transporter which is absent in marine but has been identified in many freshwater cyanobacteria was also detected in Synechococcus sp. Tous. The RuBisCo subunits from this microbe are phylogenetically close to the freshwater amoeba Paulinella chromatophora symbiont, hinting to a freshwater origin of the carboxysome operon of this protist. The novel genomes enlarge the known diversity of freshwater Synechococcus and improve the overall knowledge of the relationships among members of this genus at large. PMID:28680419

  1. Novel Synechococcus Genomes Reconstructed from Freshwater Reservoirs

    Directory of Open Access Journals (Sweden)

    Pedro J. Cabello-Yeves

    2017-06-01

    Full Text Available Freshwater picocyanobacteria including Synechococcus remain poorly studied at the genomic level, compared to their marine representatives. Here, using a metagenomic assembly approach we discovered two novel Synechococcus sp. genomes from two freshwater reservoirs Tous and Lake Lanier, both sharing 96% average nucleotide identity and displaying high abundance levels in these two lakes located at similar altitudes and temperate latitudes. These new genomes have the smallest estimated size (2.2 Mb and average intergenic spacer length (20 bp of any previously sequenced freshwater Synechococcus, which may contribute to their success in oligotrophic freshwater systems. Fluorescent in situ hybridization confirmed that Synechococcus sp. Tous comprises small cells (0.987 ± 0.139 μm length, 0.723 ± 0.119 μm width that amount to 90% of the picocyanobacteria in Tous. They appear together in a phylogenomic tree with Synechococcus sp. RCC307 strain, the main representative of sub-cluster 5.3 that has itself one of the smallest marine Synechococcus genomes. We detected a type II phycobilisome (PBS gene cluster in both genomes, which suggests that they belong to a phycoerythrin-rich pink low-light ecotype. The decrease of acidic proteins and the higher content of basic transporters and membrane proteins in the novel Synechococcus genomes, compared to marine representatives, support their freshwater specialization. A sulfate Cys transporter which is absent in marine but has been identified in many freshwater cyanobacteria was also detected in Synechococcus sp. Tous. The RuBisCo subunits from this microbe are phylogenetically close to the freshwater amoeba Paulinella chromatophora symbiont, hinting to a freshwater origin of the carboxysome operon of this protist. The novel genomes enlarge the known diversity of freshwater Synechococcus and improve the overall knowledge of the relationships among members of this genus at large.

  2. 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

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

    African Journals Online (AJOL)

    , heptachlor and endosulfan were determined in water and sediment samples of freshwater systems in the Eastern Cape Province of South Africa that receive runoff from agricultural lands and effluents from industries. The organochlorine ...

  4. Seasonal dynamic of a shallow freshwater lens due to irrigation in the coastal plain of Ravenna, Italy

    Science.gov (United States)

    Vandenbohede, Alexander; Mollema, Pauline N.; Greggio, Nicolas; Antonellini, Marco

    2014-06-01

    Irrigation in low-lying coastal plains may enhance the formation of fresh groundwater lenses, which counteract salinization of groundwater and soil. This study presents seasonal dynamics of such a freshwater lens and discusses its influence on the salinity distribution of the unconfined aquifer in the coastal plain of Ravenna, Italy, combining field observations with numerical modeling (SEAWAT). The lens originates from an irrigation ditch used as a water reservoir for spray irrigation. The geometry of the freshwater lens shows seasonal differences because of freshwater infiltration during the irrigation season and upconing of deeper saltwater for the remainder of the year. The extent of the freshwater lens is controlled by the presence of nearby drainage ditches. Irrigation also results in a temperature anomaly in the aquifer because of the infiltration of warm water during the irrigation season. The surficial zone in the vicinity of the irrigation ditch is increased considerably in thickness. Finally, different irrigation alternatives and the influence of sea-level rise are simulated. This shows that it is necessary to integrate irrigation planning into the water management strategy of the coastal zone to have maximum benefits for freshening of the aquifer and to make optimal use of the existing infrastructure.

  5. Climate changes: effects of secondary salinisation in freshwater organisms

    OpenAIRE

    Leitão, João Luís Vieira

    2011-01-01

    As global climate patterns change, so will freshwater availability. Specially, salinisation of freshwater costal ecosystem is a major point of concern; either by surface flooding or by groundwater intrusions of seawater. This may be potentiated by the decrease of freshwater availability provoked by longer drought periods, evaporation, and increased freshwater extraction (for example for agriculture and other human uses). According, the present work aimed at evaluating how freshwater organi...

  6. Native Freshwater Fish and Mussel Species Richness

    Science.gov (United States)

    These data represent predicted current distributions of all native freshwater fish and freshwater mussels in the Middle-Atlantic region. The data are available for both 8-digit HUCs and EMAP hexagons and represent total species counts for each spatial unit. More information about these resources, including the variables used in this study, may be found here: https://edg.epa.gov/data/Public/ORD/NERL/ReVA/ReVA_Data.zip.

  7. Freshwater Commercial Bycatch: an Understated Conservation Problem

    Energy Technology Data Exchange (ETDEWEB)

    Raby, Graham D.; Colotelo, Alison HA; Blouin-Demers, Gabriel; Cooke, Steven J.

    2011-04-01

    Commercial fisheries bycatch in marine systems has been regarded as a global conservation concern by environmental groups, scientists, government, and the public for decades. Fortunately, some headway has been made to mitigate the negative impacts of bycatch in marine environments. In a survey of the literature, we found that despite freshwater commercial fisheries yields comprising 11% of the global commercial catch, bycatch research focusing on freshwater commercial fisheries represented only {approx}3% of the total bycatch literature. This paucity of research is particularly alarming given that freshwater animals and habitats are some of the world's most imperiled. The limited inland bycatch literature that does exist includes examples of population declines attributed to commercial bycatch (e.g., freshwater dolphins in the Yangtze River in China) and illustrates that in some systems bycatch can be substantial (e.g., lake trout bycatch in the Laurentian Great Lakes). Encouraging results from the marine realm can serve as models for bycatch research in freshwater, and lead to measurable gains in conservation of freshwater ecosystems. We summarize existing work on inland bycatch in an effort to draw attention to this understated and understudied conservation problem.

  8. Radiation Field in the Vicinity of the Collider Center

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, A. J. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    1994-10-26

    The Collider Center and the adjoining cryogenic support building are unique among the buildings close to the collider tunnel because these are locations where the occupancy by non-radiation workers is high. This note describes calculations of the dose equivalent from local beam loss at both the nearest point of these buildings to the collider ring and on the berm in the vicinity of these buildings.

  9. Environmental surveillance in the vicinity of Hanford for January 1968

    Energy Technology Data Exchange (ETDEWEB)

    Wooldridge, C.B. (ed.)

    1968-04-15

    The concentrations of most radionuclides in the vicinity of Hanford during January 1968 were below comparable measurements for a year ago. Slightly increased concentrations of I-131 in Richland drinking water were observed during the last two weeks of the month. Radioiodine detected in several milk samples (maximum 25 pCi/l) was attributed to fallout from an announced nuclear weapons test of December 24, 1967. Increased beta activities on air filters were also attributed to fallout.

  10. Evolution of the Freshwater Eels

    Science.gov (United States)

    Aoyama, Jun; Tsukamoto, Katsumi

    The freshwater anguillid eels have an unusual life history and world-wide distribution. Questions about the phylogenetic relationships of this group and how their long spawning migrations and larval phase may contribute to their global distribution have not been addressed. This paper is first presentation of molecular phylogeny of Anguilla species, and based on this phylogenetic tree we suggest new aspect of the evolution of this group. Namely, ancestral eels originated during the Eocene or earlier, in the western Pacific Ocean near present-day Indonesia. A group derived from this ancestor dispersed westward, probably by larval transport in the global circum-equatorial current through the northern edge of the Tethys Sea. This group split into the ancestor of the European and American eels, which entered into the Atlantic Ocean, and a second group, which dispersed southward and split into the east African species and Australian species. Thus the world-wide distribution of the eel family can be understood from knowledge of continental drift, ocean currents, a specialized larva and evolutionary forces favoring dispersal and speciation of segregated gene pool.

  11. COMMUNITY DEVELOPMENT IN FRESHWATER MICROCOSMS

    Energy Technology Data Exchange (ETDEWEB)

    Rees, John T.

    1978-01-01

    Two cylindrical freshwater microcosms with a volume of 700 {ell} were maintained under controlled laboratory conditions for 190 days. The two microcosms were identical with regard to initial chemical composition and biological inocula, with the exceptions that in one microcosm (designated Tank 2) mosquitofish (Gambusia) and herbivorous catfish (Placostomas) were added. Three distinct communities developed in the tanks: (1) a phytoplankton-zooplankton assemblage and (2) two periphyton-zoobenthos communities associated with the sides and bottom of the tank, respectively. Community development and successional patterns were similar in both tanks. Major differences between the tanks involved timing of succession of the zooplankton and zoobenthos, attributable to predation by fish, principally Gambusia. A major drawback for these microcosms as use for experimental analogs such as lakes was a luxuriant periphyton growth which eventually overwhelmed the biomass of the system. The tanks displayed a degree of successional replicability, a large number of species, and a diversity of community development. Microcosms of this size could find use as experimental systems for higher level trophic manipulation and observation of life cycles not amenable to field studies.

  12. Kinetics and mechanism of the oxidation of some vicinal and non ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 115; Issue 2. Kinetics and ... Kinetics of oxidation of five vicinal and four non-vicinal diols, and two of their monoethers, by tetrabutylammonium tribromide (TBATB) has been studied. The vicinal diols ... Department of Chemistry, JNV University, Jodhpur 342 005, India ...

  13. 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

  14. Effects on Freshwater Organisms of Magnetic Fields Associated with Hydrokinetic Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Cada, Glenn F [ORNL; Bevelhimer, Mark S [ORNL; Riemer, Kristina P [ORNL; Turner, Julie W [ORNL

    2011-07-01

    Underwater cables will be used to transmit electricity between turbines in an array (interturbine cables), between the array and a submerged step-up transformer (if part of the design), and from the transformer or array to shore. All types of electrical transmitting cables (as well as the generator itself) will emit EMF into the surrounding water. The electric current will induce magnetic fields in the immediate vicinity, which may affect the behavior or viability of animals. Because direct electrical field emissions can be prevented by shielding and armoring, we focused our studies on the magnetic fields that are unavoidably induced by electric current moving through a generator or transmission cable. These initial experiments were carried out to evaluate whether a static magnetic field, such as would be produced by a direct current (DC) transmitting cable, would affect the behavior of common freshwater fish and invertebrates.

  15. Scheme Transformations in the Vicinity of an Infrared Fixed Point

    DEFF Research Database (Denmark)

    Ryttov, Thomas; Shrock, Robert

    2012-01-01

    We analyze the effect of scheme transformations in the vicinity of an exact or approximate infrared fixed point in an asymptotically free gauge theory with fermions. We show that there is far less freedom in carrying out such scheme transformations in this case than at an ultraviolet fixed point....... We construct a transformation from the $\\bar{MS}$ scheme to a scheme with a vanishing three-loop term in the $\\beta$ function and use this to assess the scheme dependence of an infrared fixed point in SU($N$) theories with fermions. Implications for the anomalous dimension of the fermion bilinear...

  16. 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.

  17. 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...

  18. Freshwater reservoir effect variability in Northern Germany

    OpenAIRE

    Philippsen, Bente; Heinemeier, Jan

    2012-01-01

    The freshwater reservoir effect is a potential problem when radiocarbon dating fishbones, shells, human bones or food crusts on pottery from sites next to rivers or lakes. The reservoir age in rivers containing considerable amounts of dissolved 14C-free carbonates can be up to several thousand years and may be highly variable. For accurate radiocarbon dating of freshwater-based samples, the order of magnitude of the reservoir effect as well as the degree of variability has to be known.The ini...

  19. 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....

  20. Freshwater algae of North America: ecology and classification

    National Research Council Canada - National Science Library

    Wehr, John D; Sheath, R.G; Kociolek, J.P

    2015-01-01

    Freshwater Algae of North America: Ecology and Classification, Second Edition is an authoritative and practical treatise on the classification, biodiversity, and ecology of all known genera of freshwater algae from North America...

  1. Health effects of living in the vicinity of the landfills

    Directory of Open Access Journals (Sweden)

    Katarzyna Lar

    2013-12-01

    Full Text Available Landfill sites are the easiest, the cheapest and the most common way of waste management and disposal. In the face of the increasing amount of waste, the dynamics of globalization and urbanization process, waste management is an important issue of ecological policy in highly developed countries. Landfill sites intensify environmental threats for the neighborhood and give rise to toxic substances which impair human health being released from the landfills. These are persistent organic pollutants (POPs, heavy metals and also biological gas, bioaerosols, bacteria and viruses. Scientists have conducted a lot of research to evaluate the impact of landfill sites on human health living in their vicinity. They found increased occurrence of congenital anomalies, increased risk of certain cancers and low birth weight of infants. The results of the studies didn’t deliver absolute proof of relation between the impact of landfill sites on the induction of cancer and other diseases. There is a necessity to conduct further research to evaluate the impact of landfill sites on people health living in the vicinity

  2. Energetic particle fluxes in vicinity of Jupiter's moon Europa

    Science.gov (United States)

    Podzolko, Mikhail; Getselev, Igor; Gubar, Yuriy; Veselovsky, Igor

    Currently several projects of sending research space vehicles to Jupiter and its Galilean moons in 2020 are being developed. In particular, Russian Space Agency proposed the project of Europa lander. During the mission the spacecraft will be affected by charged particles of various origins. The greatest hazard will originate from powerful Jupiter's radiation belts, especially during the time of spacecraft operation near Europa and on its surface. The absorbed radiation dose during 2 months in Europa's orbit under shielding compared to that for "Galileo" spacecraft will amount to almost 1 megarad, the major contribution to it will originate from relativistic electrons. However, near Europa part of the charged particle flux will be shaded by the moon. Obviously, fluxes of particles of all energies on its surface will be lower by at least 2 times, than in the same point of space without Europa. But furthermore, the reduction of the fluxes in vicinity of Europa is nonuniform, and differs for the surface and the low-altitude orbit. This is caused by several factors: the complexity of particle trajectories near Europa and in Jupiter's magnetosphere in general, difference of Europa's orbital plane from Jupiter's geomagnetic equator plane, certain disturbance of Jupiter's magnetic field in vicinity of Europa, possible influence of electric fields and Europa's tenuous atmosphere. In the current study computations of energetic particle flux distribution near Europa and on its surface are made, taking into account several of the above-mentioned factors.

  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. Freshwater resources in the insular Caribbean: an environmental perspective

    Science.gov (United States)

    T. Heartsill Scalley

    2012-01-01

    From islands with no permanent flowing streams to those with navigable inland waters, the insular Caribbean contains a great range of conditions regarding the access to freshwater resources. Because of the variation in topography and size, the ability of islands to retain freshwater also varies widely. The usage of freshwater in this region is being led by two major...

  5. 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.

  6. Microbial quality and phylogenetic diversity of fresh rainwater and tropical freshwater reservoir.

    Science.gov (United States)

    Kaushik, Rajni; Balasubramanian, Rajasekhar; Dunstan, Hugh

    2014-01-01

    The impact of rainwater on the microbial quality of a tropical freshwater reservoir through atmospheric wet deposition of microorganisms was studied for the first time. Reservoir water samples were collected at four different sampling points and rainwater samples were collected in the immediate vicinity of the reservoir sites for a period of four months (January to April, 2012) during the Northeast monsoon period. Microbial quality of all fresh rainwater and reservoir water samples was assessed based on the counts for the microbial indicators: Escherichia coli (E. coli), total coliforms, and Enterococci along with total heterotrophic plate counts (HPC). The taxonomic richness and phylogenetic relationship of the freshwater reservoir with those of the fresh rainwater were also assessed using 16 S rRNA gene clone library construction. The levels of E. coli were found to be in the range of 0 CFU/100 mL-75 CFU/100 mL for the rainwater, and were 10-94 CFU/100 mL for the reservoir water. The sampling sites that were influenced by highway traffic emissions showed the maximum counts for all the bacterial indicators assessed. There was no significant increase in the bacterial abundances observed in the reservoir water immediately following rainfall. However, the composite fresh rainwater and reservoir water samples exhibited broad phylogenetic diversity, including sequences representing Betaproteobacteria, Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, Lentisphaerae and Bacteriodetes. Members of the Betaproteobacteria group were the most dominant in both fresh rainwater and reservoir water, followed by Alphaproteobacteria, Sphingobacteria, Actinobacteria and Gammaproteobacteria.

  7. Microbial quality and phylogenetic diversity of fresh rainwater and tropical freshwater reservoir.

    Directory of Open Access Journals (Sweden)

    Rajni Kaushik

    Full Text Available The impact of rainwater on the microbial quality of a tropical freshwater reservoir through atmospheric wet deposition of microorganisms was studied for the first time. Reservoir water samples were collected at four different sampling points and rainwater samples were collected in the immediate vicinity of the reservoir sites for a period of four months (January to April, 2012 during the Northeast monsoon period. Microbial quality of all fresh rainwater and reservoir water samples was assessed based on the counts for the microbial indicators: Escherichia coli (E. coli, total coliforms, and Enterococci along with total heterotrophic plate counts (HPC. The taxonomic richness and phylogenetic relationship of the freshwater reservoir with those of the fresh rainwater were also assessed using 16 S rRNA gene clone library construction. The levels of E. coli were found to be in the range of 0 CFU/100 mL-75 CFU/100 mL for the rainwater, and were 10-94 CFU/100 mL for the reservoir water. The sampling sites that were influenced by highway traffic emissions showed the maximum counts for all the bacterial indicators assessed. There was no significant increase in the bacterial abundances observed in the reservoir water immediately following rainfall. However, the composite fresh rainwater and reservoir water samples exhibited broad phylogenetic diversity, including sequences representing Betaproteobacteria, Alphaproteobacteria, Gammaproteobacteria, Actinobacteria, Lentisphaerae and Bacteriodetes. Members of the Betaproteobacteria group were the most dominant in both fresh rainwater and reservoir water, followed by Alphaproteobacteria, Sphingobacteria, Actinobacteria and Gammaproteobacteria.

  8. Chemical footprint method for improved communication of freshwater ecotoxicity impacts in the context of ecological limits.

    Science.gov (United States)

    Bjørn, Anders; Diamond, Miriam; Birkved, Morten; Hauschild, Michael Zwicky

    2014-11-18

    The ecological footprint method has been successful in communicating environmental impacts of anthropogenic activities in the context of ecological limits. We introduce a chemical footprint method that expresses ecotoxicity impacts from anthropogenic chemical emissions as the dilution needed to avoid freshwater ecosystem damage. The indicator is based on USEtox characterization factors with a modified toxicity reference point. Chemical footprint results can be compared to the actual dilution capacity within the geographic vicinity receiving the emissions to estimate whether its ecological limit has been exceeded and hence whether emissions can be expected to be environmentally sustainable. The footprint method was illustrated using two case studies. The first was all inventoried emissions from European countries and selected metropolitan areas in 2004, which indicated that the dilution capacity was likely exceeded for most European countries and all landlocked metropolitan areas. The second case study indicated that peak application of pesticides alone was likely to exceed Denmark's freshwater dilution capacity in 1999-2011. The uncertainty assessment showed that better spatially differentiated fate factors would be useful and pointed out other major sources of uncertainty and some opportunities to reduce these.

  9. Quantal Response Of Freshwater Shrimp ( Desmocaris trispinosa ...

    African Journals Online (AJOL)

    The quantal-response of freshwater shrimp (Desmocaris trispinosa) to the toxicity of five azo dyes was studied. Generally, increase in percentage mortality of the organisms was obtained with increases in concentration of the toxicants and exposure time. The median lethal concentration50 (LC50) and median lethal ...

  10. 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

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

    African Journals Online (AJOL)

    Since the 1970s, at approximately 10-year intervals, 4 national-scale freshwater conservation plans have been developed for South Africa. These 4 plans reflect different but broadly advancing approaches to conservation planning. We provide an overview of 3 historical plans and a more detailed discussion of the most ...

  12. 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

  13. Petroleum hydrocarbon degrading capability of freshwater ...

    African Journals Online (AJOL)

    Petroleum hydrocarbon degrading capability and growth profile of indigenous filamentous freshwater fungi from four (4) different streams were determined in vitro. The result indicated that the streams under investigation contained an average heterotrophic fungal count of 5.55 0.25x105 cfu ml-1 while the mean count of ...

  14. 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)

  15. 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, ...

  16. Ocean Freshwater Lenses: Prevalence and Persistence

    Science.gov (United States)

    Schanze, Julian; Lagerloef, Gary; Schmitt, Raymond

    2017-04-01

    During the Salinity Processes in the Upper Ocean Regional Study II (SPURS-II), a novel dataset was collected from an underway system sampling seawater at the surface, 2m, 3m and 5m. The surface measurements are performed using a boom-mounted suction hose and a peristaltic pump, as well as a shipboard apparatus with multiple de-bubbling stages. The data collected during this cruise reveal approximately fifty freshwater lenses in the Intertropical Convergence Zone (ITCZ), sampled between August 15 and September 20 under several different wind- and precipitation-regimes. Preliminary analysis shows that that the persistence of oceanic freshwater lenses is strongly dependent on the evolution of wind speed as well as the total amount of precipitated water. The results are analyzed in a number of case studies of different types of freshwater lenses, in which the balance between precipitation and wind-driven mixing is elucidated. While the limited sample size restricts the validity of the findings to the SPURS-II region, centered around 125°W, 10°N, during the late boreal summer of 2016, it has important consequences for modelling of freshwater lenses and their impact on satellite retrievals of salinity.

  17. Thiaminase activity in native freshwater mussels

    Science.gov (United States)

    Blakeslee, Carrie J.; Sweet, Stephanie; Galbraith, Heather S.; Honeyfield, Dale C.

    2015-01-01

    Thiamine (vitamin B1) deficiency in the Great Lakes has been attributed to elevated levels of thiaminase I enzyme activity in invasive prey species; however, few studies have investigated thiaminase activity in native prey species. Some of the highest levels of thiaminase activity have been measured in invasive dreissenid mussels with little understanding of background levels contributed by native freshwater mussels (Bivalvia: Unionidae). In this study, thiaminase activity was measured in two freshwater mussel species, Elliptio complanata and Strophitus undulatus, from the Delaware and Susquehanna River drainage basins located in north eastern United States. Thiaminase activity was also measured in gravid and non-gravid S. undulatus. Average thiaminase activity differed significantly between species (7.2 and 42.4 μmol/g/min, for E. complanata and S. undulatus respectively) with no differences observed between drainage basins. Gravid S. undulatus had significantly lower thiaminase activity (28.0 μmol/g/min) than non-gravid mussels (42.4 μmol/g/min). Our results suggest that a suite of factors may regulate thiaminase activity in freshwater mussels and that native freshwater mussel thiaminase activity is within the range observed for invasive dreissenids. These results add to our understanding of the complexities in identifying the ecological conditions that set the stage for thiamine deficiency.

  18. 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.

  19. Quantifying Mapping Orbit Performance in the Vicinity of Primitive Bodies

    Science.gov (United States)

    Pavlak, Thomas A.; Broschart, Stephen B.; Lantoine, Gregory

    2015-01-01

    Predicting and quantifying the capability of mapping orbits in the vicinity of primitive bodies is challenging given the complex orbit geometries that exist and the irregular shape of the bodies themselves. This paper employs various quantitative metrics to characterize the performance and relative effectiveness of various types of mapping orbits including terminator, quasi-terminator, hovering, ping pong, and conic-like trajectories. Metrics of interest include surface area coverage, lighting conditions, and the variety of viewing angles achieved. The metrics discussed in this investigation are intended to enable mission designers and project stakeholders to better characterize candidate mapping orbits during preliminary mission formulation activities. The goal of this investigation is to understand the trade space associated with carrying out remote sensing campaigns at small primitive bodies in the context of a robotic space mission. Specifically, this study seeks to understand the surface viewing geometries, ranges, etc. that are available from several commonly proposed mapping orbits architectures

  20. Particle transport in the vicinity of divertor separatrix

    Science.gov (United States)

    Nishimura, Y.; Lyu, J. C.

    2017-10-01

    Guiding center orbit following code in a tokamak edge geometry is developed which connects straight field line coordinate system (away from the separatrix) and Cartesian coordinate system (in the vicinity of the separatrix) smoothly in the equation of motion. In the presence of magnetic stochasticity charged particles in the closed magnetic field line region can be transported to the open field line region and then hit the divertor plates within several toroidal transits. Our preliminary studies suggest finite heat load both on the inner and outer divertor plates. Energy spectrum of particles reaching the plates (which differs from that of the bulk plasma) as function of imposed magnetic stochasticity, is analyzed. This work is supported by Taiwan MOST 104-2112-M-006-019.

  1. Lithologic and physicochemical properties and hydraulics of flow in and near the freshwater/saline-water transition zone, San Antonio segment of the Edwards aquifer, south-central Texas, based on water-level and borehole geophysical log data, 1999-2007

    Science.gov (United States)

    Lambert, Rebecca B.; Hunt, Andrew G.; Stanton, Gregory P.; Nyman, Michael B.

    2010-01-01

    The freshwater zone of the San Antonio segment of the Edwards aquifer in south-central Texas (hereinafter, the Edwards aquifer) is bounded to the south and southeast by a zone of transition from freshwater to saline water (hereinafter, the transition zone). The boundary between the two zones is the freshwater/saline-water interface (hereinafter, the interface), defined as the 1,000-milligrams per liter dissolved solids concentration threshold. This report presents the findings of a study, done by the U.S. Geological Survey in cooperation with the San Antonio Water System, to obtain lithologic properties (rock properties associated with known stratigraphic units) and physicochemical properties (fluid conductivity and temperature) and to analyze the hydraulics of flow in and near the transition zone of the Edwards aquifer on the basis of water-level and borehole geophysical log data collected from 15 monitoring wells in four transects during 1999-2007. No identifiable relation between conductivity values from geophysical logs in monitoring wells in all transects and equivalent freshwater heads in the wells at the times the logs were run is evident; and no identifiable relation between conductivity values and vertical flow in the boreholes concurrent with the times the logs were run is evident. The direction of the lateral equivalent freshwater head gradient and thus the potential lateral flow at the interface in the vicinity of the East Uvalde transect fluctuates between into and out of the freshwater zone, depending on recharge and withdrawals. Whether the prevailing direction on average is into or out of the freshwater zone is not clearly indicated. Equivalent freshwater head data do not indicate a prevailing direction of the lateral gradient at the interface in the vicinity of the Tri-County transect. The prevailing direction on average of the lateral gradient and thus potential lateral flow at the interface in the vicinity of the Kyle transect likely is from the

  2. Freshwater reservoir effect variability in Northern Germany

    DEFF Research Database (Denmark)

    Philippsen, Bente; Heinemeier, Jan

    2012-01-01

    The freshwater reservoir effect is a potential problem when radiocarbon dating fishbones, shells, human bones or food crusts on pottery from sites next to rivers or lakes. The reservoir age in rivers containing considerable amounts of dissolved 14C-free carbonates can be up to several thousand...... years and may be highly variable. For accurate radiocarbon dating of freshwater-based samples, the order of magnitude of the reservoir effect as well as the degree of variability has to be known. The initial problem in this case was the accurate dating of food crusts on pottery from the Mesolithic sites...... and variability that can also be expected for the past. Water DIC from different seasons, and from the same season in different years, has been dated because it is the carbon source in photosynthesis and thus at the basis of the rivers’ food webs. The radiocarbon ages of underwater plants and different parts...

  3. 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.

  4. Assessing the freshwater distribution of yellow eel

    Directory of Open Access Journals (Sweden)

    Lasne É.

    2009-04-01

    Full Text Available In the global context of the decline in wild species, modeling the distribution of populations is a crucial aspect of ecological management. This can be a major challenge, especially for species, such as the European eel, that have complex life cycles, exhibit cryptic behavior, or migrate over long distances. A review of the literature suggests that eel size data could be used to assess and analyze freshwater distribution of eel. We argue that analyses based on small yellow eels (≤ 300 mm along the longitudinal course of rivers could provide a valuable tool for population monitoring. We propose a standardized catchment recruitment index and a colonization index based on the probability of occurrence (presence/absence data using logistic models for different size classes. The model developed here provides a convenient guide for assessing yellow eel stages in freshwater areas, and should have concrete applications for management of the species.

  5. Three new ascomycetes from freshwater in China.

    Science.gov (United States)

    Hu, Dian-Ming; Cai, Lei; Hyde, Kevin D

    2012-01-01

    Three new freshwater ascomycetes, Diaporthe aquatica sp. nov. (Diaporthaceae), Ophioceras aquaticus sp. nov. (Magnaporthaceae) and Togninia aquatica sp. nov. (Togniniaceae), are described and illustrated based on morphological and molecular data (ITS, 18S, 28S rDNA sequences). Diaporthe aquatica is characterized by globose to subglobose, black ascomata with long necks, broadly cylindrical to obclavate asci, and small, ellipsoidal to fusiform, one-septate, hyaline ascospores; it is unusual among Diaporthe species in the fact that it lacks a stroma and has freshwater habitat. Ophioceras aquaticus is characterized by globose ascomata with a long beak, cylindrical, eight-spored asci with J- subapical rings and 3-5-septate filiform ascospores with slightly acute ends. Togninia aquatica is characterized by globose ascomata with long necks, clavate and truncate asci clustered on distinct ascogenous hyphae, and small, reniform, hyaline ascospores. Differences among the new taxa and similar species are discussed.

  6. Freshwater fish of the Wilderness National Park

    Directory of Open Access Journals (Sweden)

    I.A. Russell

    1999-01-01

    Full Text Available The study aimed to determine the distribution and relative abundance of freshwater fish in the Wilderness National Park. Fish assemblages in the Touw and Duiwe rivers were sampled in 1997 and 1998, with a total of 327 fish from nine species recorded. Indigenous species included two freshwater species (Pseudobarbus afer, Sandelia capensis, two catadromous species (Anguilla mossambicus, Myxus capensis, and two estuarine species (Monodactylusfalciformis, Caffrogobius multifasciatus. Three of the nine recorded species were alien (Micropterus dolomieu, Micropterus salmoides, Gambusia affinis, with the Micropterus spp., in particular, likely to have a substantial negative influence on indigenous species. A further one indigenous species, two translocated indigenous species, and five estuarine species could potentially be recorded in these rivers. River catchment management actions to restore perennial flow to the Duiwe River, to prevent the attenuation of floods, and to prevent further establishment and spread of alien and translocated biota are required to conserve indigenous fish assemblages.

  7. Chesapeake Bay Low Freshwater Inflow Study.

    Science.gov (United States)

    1984-09-01

    and sale: itsI~ (distibution is unlimited. US Army Corps ’c:: gj-n1 contains color of Engineers r: All DTIC reproduct - Ba Eninrs Ti1 be in black and...Cyathurapolita (isopod) food. Changes in freshwater inflow Gammarus daiberi (amphiad) could further reduce this vegetation or Alosa pso ri gs (alewife) prevent...polychaete worm) Cyathura polita (isopod) Gammarus daiberi (amphipod) Alosa sapidissima (Am. shad) A losa pseudoharengus (alewife) Morone saxatilis

  8. Dominance and population structure of freshwater crabs ...

    African Journals Online (AJOL)

    1997-02-06

    Feb 6, 1997 ... E-mail: mjs@m-web.co.za. Despite freshwater crabs of the genus Potamonautes being locally abundant (up .... mm deep, and 10-20 m below the dam wall. At site 2 the river was ca 2 m wide and 400 mm deep and 600 m down- stream from the dam. Crabs were collected from both sites on. 22 October 1993 ...

  9. 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.

  10. Monitoring Global Freshwater Resources with GRACE

    Science.gov (United States)

    Rodell, M.; Famiglietti, J. S.; Velicogna, I.; Swenson, S. C.; Chambers, D. P.

    2011-12-01

    Freshwater resources include surface waters, groundwater, and seasonal snowpack. Given adequate ground based measurements, all of these can be monitored effectively, however, outside of the developed world such measurements often are not systematic and the data not centralized, and as a result reports of freshwater availability may be largely anecdotal. Even in the developed world it can be difficult to quantify changes in groundwater storage over large scales. Owing to its global coverage, satellite remote sensing has become a valuable tool for freshwater resources assessment. In particular, the Gravity Recovery and Climate Experiment (GRACE) has demonstrated an unequaled ability to monitor total terrestrial water storage including groundwater at regional to continental scales. In this presentation we will identify apparent trends in terrestrial water storage observed by GRACE over the past nine years and attempt to explain their origins and predict whether they are likely to continue. Trends in certain regions where groundwater extraction has significantly depleted aquifers, including northern India and California's Central Valley, will be discussed in detail.

  11. Evidence for dispersal syndromes in freshwater fishes.

    Science.gov (United States)

    Comte, Lise; Olden, Julian D

    2018-01-31

    Dispersal is a fundamental process defining the distribution of organisms and has long been a topic of inquiry in ecology and evolution. Emerging research points to an interdependency of dispersal with a diverse suite of traits in terrestrial organisms, however the extent to which such dispersal syndromes exist in freshwater species remains uncertain. Here, we test whether dispersal in freshwater fishes (1) is a fixed property of species, and (2) correlates with life-history, morphological, ecological and behavioural traits, using a global dataset of dispersal distances collected from the literature encompassing 116 riverine species and 196 locations. Our meta-analysis revealed a high degree of repeatability and heritability in the dispersal estimates and strong associations with traits related to life-history strategies, energy allocation to reproduction, ecological specialization and swimming skills. Together, these results demonstrate that similar to terrestrial organisms, the multi-dimensional nature of dispersal syndromes in freshwater species offer opportunities for the development of a unifying paradigm of movement ecology that transcend taxonomic and biogeographical realms. The high explanatory power of the models also suggests that trait-based and phylogenetic approaches hold considerable promises to inform conservation efforts in a rapidly changing world. © 2018 The Author(s).

  12. 33 CFR 110.190 - Tortugas Harbor, in vicinity of Garden Key, Dry Tortugas, Fla.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Tortugas Harbor, in vicinity of Garden Key, Dry Tortugas, Fla. 110.190 Section 110.190 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Anchorage Grounds § 110.190 Tortugas Harbor, in vicinity of Garden Key, Dry Tortugas,...

  13. North American freshwater mussels: natural history, ecology, and conservation

    National Research Council Canada - National Science Library

    Haag, Wendell R

    2012-01-01

    "Synthesizes ecology and natural history of North American freshwater mussels for scientists, natural resource professionals, students and natural history enthusiasts"-- "This well-illustrated book...

  14. 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

  15. Monitoring endangered freshwater biodiversity using environmental DNA

    DEFF Research Database (Denmark)

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

    2012-01-01

    that depend on practical and taxonomic expertise, which is rapidly declining. Here, we show that a diversity of rare and threatened freshwater animals-representing amphibians, fish, mammals, insects and crustaceans-can be detected and quantified based on DNA obtained directly from small water samples of lakes...... of amphibians and fish can be detected by high-throughput sequencing of DNA extracted from pond water. Our findings underpin the ubiquitous nature of DNA traces in the environment and establish environmental DNA as a tool for monitoring rare and threatened species across a wide range of taxonomic groups....

  16. 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....

  17. Freshwater rotifers from Hordaland, western Norway, with a survey of freshwater rotifers previously found in Norway

    Directory of Open Access Journals (Sweden)

    Brit Godske Bjørklund

    2010-01-01

    Full Text Available   Bjørklund BG. 2009. Freshwater rotifers from Hordaland western Norway with a u survey of freshwater rotifers previously found in Norway. Fauna Norvegica29: 11-54. A total of 156 species (or subspecies o rotifers, mostly non-planktonic, have been identified from freshwater or slightly brackish-water localities in the county of Hordaland; 83 are new to Norway and 24 others are new to the county. One hundred of the species were collected from the two valleys of Eksingedalen and Teigdalen in spring and summer 1967. Samples were taken on the shallow shores of lake-like parts of the rivers, and in pools, tarns and small lakes. Forty more or less euryhaline fresh­water rotifers were also collected during studies of slightly brackish-water localities around Bergen in 1963-1969. A number of freshwater rotifers were collected at several localities in and around Bergen in 1968-1970, and on the western part of Hardangervidda. Of those so far identified ,23 are new to Norway and 8 more are new to the county. They are therefore included in the species list. A few additional ones are referred to in the taxonomical notes. All the species are listed with localities and habitat categories, or, in the case of the last-mentioned ones, just the district where they were collected. The paper includes notes, measurements and ,in most cases, figures regarding 44 little known, variable or taxonomically problematical species, especially in the genera Cephalodella and Trichocerca. Comments are given on the distribution , abundance and diversity of the species. The paper presents asurvey of previous investigations on rotifers in Norway, listing 200 previously recorded freshwater (a few euryhaline rotifers, giving other names, the authors who recorded the finds and, in most cases, the counties where the species were collected. 

  18. 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).

  19. 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%.

  20. 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%. PMID:21149727

  1. 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.

  2. Monitoring endangered freshwater biodiversity using environmental DNA.

    Science.gov (United States)

    Thomsen, Philip Francis; Kielgast, Jos; Iversen, Lars L; Wiuf, Carsten; Rasmussen, Morten; Gilbert, M Thomas P; Orlando, Ludovic; Willerslev, Eske

    2012-06-01

    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 that depend on practical and taxonomic expertise, which is rapidly declining. Here, we show that a diversity of rare and threatened freshwater animals--representing amphibians, fish, mammals, insects and crustaceans--can be detected and quantified based on DNA obtained directly from small water samples of lakes, ponds and streams. We successfully validate our findings in a controlled mesocosm experiment and show that DNA becomes undetectable within 2 weeks after removal of animals, indicating that DNA traces are near contemporary with presence of the species. We further demonstrate that entire faunas of amphibians and fish can be detected by high-throughput sequencing of DNA extracted from pond water. Our findings underpin the ubiquitous nature of DNA traces in the environment and establish environmental DNA as a tool for monitoring rare and threatened species across a wide range of taxonomic groups. © 2011 Blackwell Publishing Ltd.

  3. Freshwater nematodes from South Africa. 4. The genus Monhystera ...

    African Journals Online (AJOL)

    During a survey of freshwater nematodes in South Africa, five species of Monhystera Bastian, 1865, were encountered. The ..... in any other South African freshwater Monhystera. Vaginal muscles small and inconspicuous. ... taken from the deep muddy silt together with rotting plant material from the Vaal River and from deep ...

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

    NARCIS (Netherlands)

    Gribsholt, B.; Struyf, E.; Tramper, A.; Andersson, M.G.I.; Brion, N.; de Brabandere, L.; van Damme, S.; Meire, P.; Middelburg, J.J.; Dehairs, F.; 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-NH 4 + to the flood water entering a 3477 m2 tidal freshwater marsh

  5. Greater diversification of freshwater than marine parasites of fish.

    Science.gov (United States)

    Poulin, Robert

    2016-04-01

    The species richness of freshwater environments is disproportionately high compared with that of the oceans, given their respective sizes. If diversification rates are higher in freshwaters because they are isolated and heterogeneous, this should apply to parasites as well. Using 14 large datasets comprising 677 species of freshwater and marine fish, the hypothesis that freshwater parasites experience higher rates of diversification than marine ones is tested by contrasting the relative numbers of species per parasite genus between the regional endohelminth faunas of fish in both environments. The relationship between the number of parasite genera and the number of parasite species per host was well described by a power function, in both environments; although the exponent of this function was slightly lower for freshwater parasite faunas than marine ones, the difference was not significant. However, the ratio between the number of parasite species and the number of parasite genera per host species was significantly higher in freshwater fish than in marine ones. These findings suggest fundamental differences between the way parasite faunas diversify in freshwater versus marine habitats, with the independent evolution of conspecific parasite populations in isolated host populations being a more common phenomenon in freshwater environments. Copyright © 2016 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

  6. Page 1 Tropical Freshwater Biology, 7 (1998) 73 - 80 73 ...

    African Journals Online (AJOL)

    fishes from Europe (Wisniewski, 1932; Arme & Owen, 1968) and mong African freshwater fishes (including among others the cichlids and cyprinid fishes) from. Sudan and East Africa (Paperna, 1980). The present report represents the first of such reports on pleurocercosis from Nigerian freshwater fishes. In the present study ...

  7. Collections of freshwater shrimps along the southern coast of South ...

    African Journals Online (AJOL)

    Collections of freshwater shrimps along the southern coast of South Africa. D.J. Coetzee. Abstract. During the period February 1983 to November 1986 a total of 38 rivers along the south-western, southem and eastern Cape coasts and Ciskei were investigated for the occurrence of freshwater shrimps. Five species were ...

  8. North American freshwater mussels: natural history, ecology, and conservation

    Science.gov (United States)

    Wendell R. Haag

    2012-01-01

    Interest in freshwater mussels is growing for two important reasons. First, freshwater mussels are among the most endangered organisms on Earth, and many species are already extinct or face imminent extinction. Their desperate conservation plight has gained intense interest from natural resource agencies, nongovernmental conservation organizations, academia, and...

  9. 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

  10. 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 ...

  11. The rediscovery of the freshwater shrimp Macrobrachium crenulatum in Jamaica

    NARCIS (Netherlands)

    Hunte, Waine

    1979-01-01

    A record of the freshwater shrimps of Jamaica has been provided by Hart (1961b). His study includes taxonomical comments and notes on the locations at which the various species were caught. Since then Holthuis (1963a) has described a new subterranean freshwater shrimp, Troglocubanus jamaicensis,

  12. Tracking salinity intrusions in a coastal forested freshwater wetland system

    Science.gov (United States)

    Anand D. Jayakaran; Thomas M. Williams; William H. Conner

    2016-01-01

    Coastal forested freshwater wetlands are sentinel sites for salinity intrusions associated with large, tidally influenced, storm-driven or drought-induced incursions of estuarine waters into freshwater ecosystems. These incursions may also be exacerbated by rising sea levels associated with climate change.

  13. Culture of the freshwater rotifer, Brachionus calyciflorus , and its ...

    African Journals Online (AJOL)

    This paper attempts to review the principles and procedures involved in the culture of the freshwater rotifer, Brachionus calyciflorus as starter food for most freshwater fish fry. There are several strains of different sizes of this rotifer, thus making them suitable for fry of a variety of sizes. This rotifer can be isolated, continuously ...

  14. 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 ...

  15. 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, ...

  16. BackscatterA [USGS SWATH]--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Monterey Canyon and Vicinity map area, California. Backscatter data are provided as separate...

  17. BackscatterD [CSUMB Swath]--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the acoustic-backscatter map of Monterey Canyon and Vicinity map area, California. Backscatter data are provided as separate...

  18. Digital Geologic Map of Rocky Mountain National Park and Vicinity, Colorado (NPS, GRD, GRE, ROMO)

    Data.gov (United States)

    National Park Service, Department of the Interior — The Digital Geologic Map of Rocky Mountain National Park and Vicinity, Coloradois comprised of GIS data layers, two ancillary GIS tables, a Windows Help File with...

  19. Geology and geomorphology--Drakes Bay and Vicinity Bay Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the geologic and geomorphic map of the Drakes Bay and Vicinity map area, California. The polygon shapefile is included in...

  20. Basalt microlapilli in deep sea sediments of Indian Ocean in the vicinity of Vityaz fracture zone

    Digital Repository Service at National Institute of Oceanography (India)

    Nath, B.N.; Iyer, S.D.

    Two cores recovered from the flanks of Mid-India oceanic ridge in the vicinity of Vityaz fracture zone consist of discrete pyroclastic layers at various depths. These layers are composed of coarse-grained, angular basaltic microlapilli in which...

  1. Digital Geologic Map of Great Basin National Park and Vicinity, Nevada (NPS, GRD, GRE, GRBA)

    Data.gov (United States)

    National Park Service, Department of the Interior — The Digital Geologic Map of Great Basin National Park and Vicinity, Nevada is composed of GIS data layers, two ancillary GIS tables, a Windows Help File with...

  2. Geology and geomorphology--Monterey Canyon and Vicinity Map Area, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for the geologic and geomorphic map of Monterey Canyon and Vicinity, California. The vector data file is included in...

  3. Life in wind turbines vicinity, effects on health – a review

    Directory of Open Access Journals (Sweden)

    Krystyna Pawlas

    2012-12-01

    Full Text Available The paper presents a short review of scientific papers , and other sources concerning health effects of exposure to noise, infrasounds, electromagnetic radiation and mechanical hazards induced in dwellers living in vicinity of wind farm.

  4. Effect of the Antibiotic Neomycin on the Toxicity of the Glycoside Vicine in Rats

    National Research Council Canada - National Science Library

    Arbid, Mahmoud S; Koriem, Khaled M. M; Asaad, Gihan F; Megahed, Hoda A

    2013-01-01

    .... Hemoglobin (Hb) concentration, hematocrit (Hct) value, and red blood cells (RBCs) count were significantly decreased after injection of vicine and the improvement of these values in the group pretreated with neomycin...

  5. Transformation of Tertiary Benzyl Alcohols into the Vicinal Halo-Substituted Derivatives Using N-Halosuccinimides

    Directory of Open Access Journals (Sweden)

    Njomza Ajvazi

    2016-10-01

    Full Text Available The efficiency of direct conversion of tertiary alcohols bearing a β-hydrogen atom to vicinal halohydrins—chlorohydrins and bromohydrins—under green reaction conditions was tested preliminarily on model tertiary benzyl alcohols. Tertiary alcohols were successfully directly halogenated to vicinal halohydrins with N-halosuccinimide in aqueous media. The efficiency of the reaction in water was significantly improved in the presence of sodium dodecyl sulphate as the surfactant.

  6. 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

    presence of diatoms and their exudates. During photosynthetic activity and the pH rising above 9 in the vicinity of diatom cells, the adsorption of AuNPs strongly decreases, which indicates a decreasing potential toxicity of AuNPs for photosynthesizing cells. The present study demonstrates the efficiency of a thermodynamic and kinetic approach for understanding gold nanoparticles interaction with aquatic freshwater peryphytic microorganisms.

  7. Landsat - SRTM Shaded Relief Comparison, Los Angeles and Vicinity

    Science.gov (United States)

    2002-01-01

    Digital elevation models (DEMs), such as those produced by the Shuttle Radar Topography Mission (SRTM), allow user-controlled visualization of the Earth's landforms that is not possible using satellite imagery alone. This three-view comparison shows Los Angeles, Calif., and vicinity, with a Landsat image (only) on the left, a shaded relief rendering of the SRTM DEM on the right, and a merge of the two data sets in the middle. Note that topographic expression in the Landsat image alone is very subtle due to the fairly high sun angle (63 degrees above the horizon) during the satellite overflight in late morning of a mid-Spring day (May 4, 2001). In contrast, computer generated topographic shading of the DEM provides a pure and bold image of topographic expression with a user specified illumination direction. The middle image shows how combining the Landsat and DEM shaded relief can result in a topographically enhanced satellite image in which the information content of both data sets is merged into a single view.Landsat has been providing visible and infrared views of the Earth since 1972. SRTM elevation data matches the 30-meter (98-foot) resolution of most Landsat images and helps in analyzing the large and growing Landsat image archive, managed by the U.S. Geological Survey (USGS).Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect 3-D measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter (approximately 200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between NASA, the National Imagery and Mapping Agency (NIMA) of the U

  8. Eutrophication of freshwater and marine ecosystems

    Science.gov (United States)

    Smith, Val H.; Joye, Samantha B.; Howarth, Robert W.

    2006-01-01

    Initial understanding of the links between nutrients and aquatic productivity originated in Europe in the early 1900s, and our knowledge base has expanded greatly during the past 40 yr. This explosion of eutrophication-related research has made it unequivocally clear that a comprehensive strategy to prevent excessive amounts of nitrogen and phosphorus from entering our waterways is needed to protect our lakes, rivers, and coasts from water quality deterioration. However, despite these very significant advances, cultural eutrophication remains one of the foremost problems for protecting our valuable surface water resources. The papers in this special issue provide a valuable cross section and synthesis of our current understanding of both freshwater and marine eutrophication science. They also serve to identify gaps in our knowledge and will help to guide future research.

  9. 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.

  10. Simulated effects of groundwater withdrawals from aquifers in Ocean County and vicinity, New Jersey

    Science.gov (United States)

    Cauller, Stephen J.; Voronin, Lois M.; Chepiga, Mary M.

    2016-10-21

    Rapid population growth since the 1930s in Ocean County and vicinity, New Jersey, has placed increasing demands upon the area’s freshwater resources. To examine effects of groundwater withdrawals, a three-dimensional groundwater-flow model was developed to simulate the groundwater-flow systems of five area aquifers: the unconfined Kirkwood-Cohansey aquifer system and Vincentown aquifer, and three confined aquifers— the Rio Grande water-bearing zone, the Atlantic City 800-foot sand, and the Piney Point aquifer. The influence of withdrawals is evaluated by using transient groundwater-flow model simulations that incorporate three withdrawal schemes. These are (1) no-withdrawal conditions; (2) 2000–03 withdrawal conditions, using reported monthly withdrawals at all production wells from January 2000 through December 2003; and (3) maximum-allocation withdrawal conditions using the maximum withdrawal allowed by New Jersey Department of Environmental Protection permits at each well. Particle tracking analysis, using results from model simulations, delineated particle flow paths from production wells to the point of recharge, and estimated particle travel times.Compared with no-withdrawal conditions, 2000–03 withdrawal conditions reduced the amount of groundwater flow out of the Kirkwood-Cohansey aquifer system into streams, increased the net flow of water into other layers, reduced net flow into or out of storage, and reduced flow from the Kirkwood-Cohansey aquifer system to constant head cells.Freshwater discharging to the Barnegat Bay-Little Egg Harbor estuary from streams and groundwater is essential to maintaining the ecology of the bay. Examination of selected stress periods indicates that simulated base flow in streams flowing into the Barnegat Bay-Little Egg Harbor estuary is reduced by as much as 49 cubic feet per second for 2000 to 2003 withdrawal conditions when compared with no-withdrawal conditions.In the three confined aquifers, water levels during

  11. How northern freshwater input can stabilise thermohaline circulation

    Directory of Open Access Journals (Sweden)

    Erwin Lambert

    2016-11-01

    Full Text Available The North Atlantic thermohaline circulation (THC carries heat and salt towards the Arctic. This circulation is partly sustained by buoyancy loss and is generally believed to be inhibited by northern freshwater input as indicated by the ‘box-model’ of Stommel (1961. The inferred freshwater-sensitivity of the THC, however, varies considerably between studies, both quantitatively and qualitatively. The northernmost branch of the Atlantic THC, which forms a double estuarine circulation in the Arctic Mediterranean, is one example where both buoyancy loss and buoyancy gain facilitate circulation. We have built on Stommel's original concept to examine the freshwater-sensitivity of a double estuarine circulation. The net inflow into the double estuary is found to be more sensitive to a change in the distribution of freshwater than to a change in the total freshwater input. A double estuarine circulation is more stable than a single overturning, requiring a larger amount and more localised freshwater input into regions of buoyancy loss to induce a thermohaline ‘collapse’. For the Arctic Mediterranean, these findings imply that the Atlantic inflow may be relatively insensitive to increased freshwater input. Complementing Stommel's thermal and haline flow regimes, the double estuarine circulation allows for a third: the throughflow regime. In this regime, a THC with warm poleward surface flow can be sustained without production of dense water; a decrease in high-latitude dense water formation does therefore not necessarily affect regional surface conditions as strongly as generally thought.

  12. FRESHWATER FISHERY OF THE REPUBLIC OF CROATIA

    Directory of Open Access Journals (Sweden)

    Zlatko Homen

    1999-09-01

    Full Text Available As fishery, including freshwater, is very important for economy of the Republic of Croatia, the aim of this paper is to show its condition from 1995 to 1998. and also to draw a plan for fish production in 1999. The period from 1998-1999. is more stressed in order to have a total and detailed view into the present condition of the freshwater fishery and into the direction in wish that production is going. Data about carp ponds and also about trout ponds is presented. Twentynine fish-ponds are processed out of which 20 are carp ponds and 9 trout ponds. Data was delivered to the Ministry of Agriculture and Forestry Fisheries Directorate. An assessment of the condition is made for 3 fish-ponds as the desired data was not provided. As to the number of employees on fish-ponds, a slight decline could be percived in the period from 1995 to 1997. In 1998 a number of employees considerably increased for 10.07% in relation to 1997. qualification of the employees in 1998. show that the most of them are unqualified what is in accord with the requirements of a job on a fish-pond. Overall surface of the carp ponds in 1998 was 12,708 and the production surface was 9,782 ha. The most of the fish-ponds have up to 500 ha of total surface (45.45%, while 50% of the fish-ponds have production surface from 500-100 ha. The production in the trout ponds is made on 165,905 m 2 of the overall surface of the ponds, and only 40,538 m 2 are the production surface of the ponds. The production of fish in that period was in constant increase and that increasing trend in expected in 1999, and it will be an 28.30 % increase in relation to 1998. The increase is expected for all kids of fish except for big head carps, silver carps and tinch fishs. As a part of the production of tinch fishs an increase in production of consumption tinch fish is expected, but a decrease in production of one-year and two-year old fishs and two-year old fish. Out of all kinds of fish, the most produced

  13. Panbiogeographical analysis of Costa Rican freshwater fishes

    Directory of Open Access Journals (Sweden)

    Jonathan Herrera-Vásquez

    2008-03-01

    Full Text Available Track analysis and Parsimony analysis of endemicity (PAE were performed to analyze the distribution pattern of Costa Rican freshwater fishes. A basic matrix (presence/absence was prepared using the distribution of 77 freshwater fish. The data were analyzed with CLIQUE software in order to find generalized tracks (cliques. Data also were analyzed with the software NONA and Winclada version 1.00.08 in order to perform the Parsimony Analysis of Endemicity (PAE. Fourteen equally probable cliques were found with 31 species in each and the intersection of the amount was selected as a generalized track dividing the country in two main zones: Atlantic slope from Matina to Lake Nicaragua and Pacific slope from the Coto River to the basin of the Tempisque River connected with some branches oriented to the central part of the country. PAE analysis found ten cladogram areas (72 steps, CI=0.45, RI=0.64, using the "strict consensus option" two grouping zones were identified: Atlantic slope and Pacific slope. Both PAE and Track Analysis show the division of the two slopes and the orientation of the generalized track suggests new biogeographical evidence on the influence of both old and new southern elements to explain the migrations of freshwater fish into Central America during two different geological events. Rev. Biol. Trop. 56 (1: 165-170. Epub 2008 March 31.Con el objetivo de analizar el patrón de distribución de peces de agua dulce de Costa Rica se aplicó un análisis de trazos y de parsimonía de endemismos (PAE. Se construyó una matriz básica utilizando la distribución de 77 especies. Se utilizó el programa CLIQUE con la intención de encontrar los trazos generalizados y NONA y Winclada, versión 1.00.08, con el fin de llevar a cabo el PAE. Se encontró un total de 14 cliques igualmente probables con 31 especies. De esta cantidad se construyó un trazo generalizado que constituye la intersección del total, dividiendo el país en dos zonas: Atl

  14. 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.

  15. Ecobiological studies of the freshwater lakes at Schirmacher Oasis, Antarctica

    Digital Repository Service at National Institute of Oceanography (India)

    Verlecar, X.N.; Dhargalkar, V.K.; Matondkar, S.G.P.

    Ecological studies of the freshwater lakes at the Schirmacher Oasis have been reported. Physical variables such as atmospheric temperature, solar radiation, winds, etc. showed that the environment at Schirmacher Oasis is less extreme than near...

  16. Book Review Guides to the freshwater invertebrates of southern ...

    African Journals Online (AJOL)

    Book Review Guides to the freshwater invertebrates of southern Africa. Volume 2: Crustacea I. Notostraca, Anostraca, Conchostraca and Cladocera by JA Day, BA Stewart, IJ de Moor and AE Louw (Editors), December 1999.

  17. Book Review Guides to the Freshwater Invertebrates of Southern ...

    African Journals Online (AJOL)

    Book Review Guides to the Freshwater Invertebrates of Southern Africa. Volume 8: Insecta II. Hemiptera, Megaloptera, Neuroptera, Trichoptera and Lepidoptera By IJ de Moor, JA Day and FC de Moor (editors) 2003.

  18. Macroinvertebrate Fauna Of A Tropical Freshwater Stream In Nigeria

    African Journals Online (AJOL)

    ... recorded in station 6 The macroinvertebrate composition, distribution abundance and diversity were influenced by substrate composition, good water quality and availability of food. Keywords: Tropical freshwater stream, Macroinvertebrate composition, Abundance, Distribution, Diversity Animal Research International Vol.

  19. 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.

  20. 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.

  1. Caernarvon freshwater diversion: Contaminants monitoring study (interim report)

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The Caernarvon Freshwater Diversion Structure was completed in January 1991 by the U.S. Army Corps of Engineers. The purpose of the structure is to divert...

  2. [Latin American malacology. Freshwater mollusks from Argentina].

    Science.gov (United States)

    Rumi, Alejandra; Gregoric, Diego E Gutiérrez; Núñez, Verónica; Darrigran, Gustavo A

    2008-03-01

    A report and an updated list with comments on the species of freshwater molluscs of Argentina which covers an area of 2 777 815 km2 is presented. Distributions of Gastropoda and Bivalvia families, endemic, exotic, invasive as well as entities of sanitary importance are also studied and recommendations on their conservation are provided. Molluscs related to the Del Plata Basin have been thoroughly studied in comparison to others areas of the country. This fauna exhibits relatively the biggest specific richness and keeps its affinity with the fauna of other regions of the basin in areas of Paraguay and Brasil. The 4 500 records of molluscs considered in this paper arise from the study of the collections of Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires; Museo de La Plata, La Plata and Fundación "Miguel Lillo", Tucumán. These institutions keep very important collections of molluscs in southern South America. Field information has recently been obtained and localities cited by other authors are also included in the data base. Until today, 166 species have been described, 101 belonging to 10 families of Gastropoda and 65 to 7 of Bivalvia. Families with highest specific richness are Lithoglyphidae (22) and Sphaeriidae (25), respectively. The number of endemic species (those present only in Argentina) by family is: Gastropoda: Ampullariidae (1), Cochliopidae (10), Lithoglyphidae (11), Thiariidae (3), Chilinidae (11), Lymnaeidae (2) and Physidae (2?); Bivalvia: Hyriidae (1?); Etheriidae (1?) and Sphaeriidae (10). Families with a distribution that comprise almost the whole country are: the Sphaeriidae and the gastropods Cochliopidae, Chilinidae and Lymnaeidae. Families Erodonidae and Solecurtidae (Bivalvia) were registered in mixohaline environments from Buenos Aires province. Gastropod families Thiaridae and Glacidorbiidae show a very restricted distribution. The rest of the families are present mainly in the center and north of the country

  3. Institutional development of freshwater fish stocking in Mexico.

    Science.gov (United States)

    Ibáñez, A L; Pérez-Ramírez, M; García-Calderón, J L

    2014-12-01

    By using freshwater fish stocking information from the Mexican government, this work described the current situation of the national stocking and its associated fishery policy. There is a lack of effective freshwater stocking programmes as a result of limited fisheries management, unharmonized fisheries regulations and institutional performance. The fry production has decreased from 140 to 20 million in the past 11 years. © 2014 The Fisheries Society of the British Isles.

  4. The first freshwater molluscs from Wrangel Island, Arctic Russia

    Directory of Open Access Journals (Sweden)

    Maxim V. Vinarski

    2015-08-01

    Full Text Available The first finding of a freshwater snail, Sibirenauta sibiricus (Westerlund, 1877, in one of the lakes on Wrangel Island (north-eastern Russia is reported. No freshwater mollusc species have hitherto been known from this island. Specimens from the island are morphologically compared with the type series of the species. How aquatic molluscs may have migrated to the Arctic island is briefly discussed.

  5. The fossil recordand evolution of freshwater plants: A review

    OpenAIRE

    Martín-Closas, Carles

    2003-01-01

    Palaeobotany applied to freshwater plants is an emerging field of palaeontology. Hydrophytic plants reveal evolutionary trends of their own, clearly distinct from those of the terrestrial and marine flora. During the Precambrian, two groups stand out in the fossil record of freshwater plants: the Cyanobacteria (stromatolites) in benthic environments and the prasinophytes (leiosphaeridian acritarchs) in transitional planktonic environments. During the Palaeozoic, green algae (Chlorococcales, Z...

  6. The fossil record and evolution of freshwater plants: a review /

    OpenAIRE

    Martin-Closas, Carles

    2009-01-01

    Palaeobotany applied to freshwater plants is an emerging field of palaeontology. Hydrophytic plants reveal evolutionary trends of their own, clearly distinct from those of the terrestrial and marine flora. During the Precambrian, two groups stand out in the fossil record of freshwater plants: the Cyanobacteria (stromatolites) in benthic environments and the prasinophytes (leiosphaeridian acritarchs) in transitional planktonic environments. During the Palaeozoic, green algae (Chlorococcales, Z...

  7. 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

  8. Biodiversity and distribution of polar freshwater DNA viruses

    OpenAIRE

    Aguirre de C?rcer, Daniel; L?pez-Bueno, Alberto; Pearce, David A.; Alcam?, Antonio

    2015-01-01

    Viruses constitute the most abundant biological entities and a large reservoir of genetic diversity on Earth. Despite the recent surge in their study, our knowledge on their actual biodiversity and distribution remains sparse. We report the first metagenomic analysis of Arctic freshwater viral DNA communities and a comparative analysis with other freshwater environments. Arctic viromes are dominated by unknown and single-stranded DNA viruses with no close relatives in the database. These uniq...

  9. Assessing the antibiotic susceptibility of freshwater Cyanobacteria spp.

    OpenAIRE

    Dias, Elsa; Oliveira, Micaela; Jones-Dias, Daniela; Vasconcelos, Vitor; Ferreira, Eugénia; Manageiro, Vera; Caniça, Manuela

    2015-01-01

    Freshwater is a vehicle for the emergence and dissemination of antibiotic resistance. Cyanobacteria are ubiquitous in freshwater, where they are exposed to antibiotics and resistant organisms, but their role on water resistome was never evaluated. Data concerning the effects of antibiotics on cyanobacteria, obtained by distinct methodologies, is often contradictory. This emphasizes the importance of developing procedures to understand the trends of antibiotic susceptibility in cyanobacteria. ...

  10. Threatened and Endangered Freshwater Fish and Mussel Species Richness

    Science.gov (United States)

    These data represent predicted current distributions of all US listed Threatened and Endangered freshwater fish and freshwater mussels in the Middle-Atlantic region. The data are available for both 8-digit HUCs and EMAP hexagons and represent total species counts for each spatial unit. More information about these resources, including the variables used in this study, may be found here: https://edg.epa.gov/data/Public/ORD/NERL/ReVA/ReVA_Data.zip.

  11. Acute toxicity of vanadium to two species of freshwater fish

    Energy Technology Data Exchange (ETDEWEB)

    Knudtson, B.K.

    1979-09-01

    Goldfish (Carassius auratus) and guppies (Lebistes reticulatus) were the two freshwater, thermophilous fishes chosen for use in this study. These species were selected for the following reasons: (1) low cost/individual, (2) ready availability, (3) ease of care and handling, (4) suspected differences between the two species in their responses to this metal, and (5) the usefulness of both as generalized models for the response of freshwater and marine fishes to vanadium.

  12. Unidirectional lateral nanowire formation during the epitaxial growth of GaAsBi on vicinal substrates

    Science.gov (United States)

    Collar, Kristen N.; Li, Jincheng; Jiao, Wenyuan; Kong, Wei; Brown, April S.

    2018-01-01

    We report on enhanced control of the growth of lateral GaAs nanowires (NWs) embedded in epitaxial (100) GaAsBi thin films enabled by the use of vicinal substrates and the growth-condition dependent role of Bi as a surfactant. Enhanced step-flow growth is achieved through the use of vicinal substrates and yields unidirectional nanowire growth. The addition of Bi during GaAsBi growth enhances Ga adatom diffusion anisotropy and modifies incorporation rates at steps in comparison to GaAs growth yielding lower density but longer NWs. The NWs grown on vicinal substrates grew unidirectionally towards the misorientation direction when Bi was present. The III/V flux ratio significantly impacts the size, shape and density of the resulting NWs. These results suggest that utilizing growth conditions which enhance step-flow growth enable enhanced control of lateral nanostructures.

  13. Experimental photophysical characterization of fluorophores in the vicinity of gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Rosa, J P; Baptista, P V [CIGMH, Departamento de Ciencias da Vida, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Lima, J C, E-mail: pmvb@fct.unl.pt, E-mail: lima@dq.fct.unl.pt [REQUIMTE, Departamento de Quimica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

    2011-10-14

    We propose an experimental-based tool for dealing with fluorescence modulation close to nanoparticles for application in studies of fluorophores in the vicinity of gold nanoparticles (AuNPs), typically addressed via theoretical models. We performed a photophysical characterization of fluorophores in the vicinity of AuNPs, showing that correct {Phi}{sub F} determination suffers from a local pH effect, and address the observed radiative enhancement. Our approach is based on the experimental assurance that the reference fluorophores are in the same optical conditions as those of the AuNP-fluorophore conjugates. We demonstrate the relevance for introducing corrections for the inner filter effect and the reabsorption of the emitted light caused by AuNPs. The proposed approach could circumvent the need for theoretical based corrections and allow for more accurate determination of fluorescence emission in the vicinity of gold nanoparticles.

  14. Cost-Performance Parametrics for Transporting Small Packages to the Mars Vicinity

    Science.gov (United States)

    McCleskey, C.; Lepsch, Roger A.; Martin, J.; Popescu, M.

    2015-01-01

    This paper explores the costs and performance required to deliver a small-sized payload package (CubeSat-sized, for instance) to various transportation nodes en route to Mars and near-Mars destinations (such as Mars moons, Phobos and Deimos). Needed is a contemporary assessment and summary compilation of transportation metrics that factor both performance and affordability of modern and emerging delivery capabilities. The paper brings together: (a) required mass transport gear ratios in delivering payload from Earths surface to the Mars vicinity, (b) the cyclical energy required for delivery, and (c) the affordability and availability of various means of transporting material across various Earth-Moon vicinity and Near-Mars vicinity nodes relevant to Mars transportation. Examples for unit deliveries are computed and tabulated, using a CubeSat as a unit, for periodic near-Mars delivery campaign scenarios.

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

    Directory of Open Access Journals (Sweden)

    Kurt E. Williamson

    2014-03-01

    Full Text Available 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.

  16. 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

  17. Predicting spatial similarity of freshwater fish biodiversity.

    Science.gov (United States)

    Azaele, Sandro; Muneepeerakul, Rachata; Maritan, Amos; Rinaldo, Andrea; Rodriguez-Iturbe, Ignacio

    2009-04-28

    A major issue in modern ecology is to understand how ecological complexity at broad scales is regulated by mechanisms operating at the organismic level. What specific underlying processes are essential for a macroecological pattern to emerge? Here, we analyze the analytical predictions of a general model suitable for describing the spatial biodiversity similarity in river ecosystems, and benchmark them against the empirical occurrence data of freshwater fish species collected in the Mississippi-Missouri river system. Encapsulating immigration, emigration, and stochastic noise, and without resorting to species abundance data, the model is able to reproduce the observed probability distribution of the Jaccard similarity index at any given distance. In addition to providing an excellent agreement with the empirical data, this approach accounts for heterogeneities of different subbasins, suggesting a strong dependence of biodiversity similarity on their respective climates. Strikingly, the model can also predict the actual probability distribution of the Jaccard similarity index for any distance when considering just a relatively small sample. The proposed framework supports the notion that simplified macroecological models are capable of predicting fundamental patterns-a theme at the heart of modern community ecology.

  18. Investigation of strength properties of freshwater ice

    Directory of Open Access Journals (Sweden)

    Bragov A.

    2015-01-01

    Full Text Available A study of the strength and deformation properties of freshwater ice under compression, tension and shear in a wide range of strain rates (10−4 − 3 ⋅ 103 s−1 and temperatures of − 5∘ C, − 20∘ C, − 40∘ C and − 60∘ C was performed. Static stress-strain curves of ice under compression were obtained on which the identified strength properties of ice as well as compressive modulus. To determine the mechanical properties of ice at high-speed loading the Kolsky method was used with various embodiments of split Hopkinson bar. The deformation curves were obtained at various loading conditions. Thereon breaking points were defined as well as their dependence on the strain rate and temperature. Also static and dynamic strength properties of ice at splitting and circular shear were defined. Increase in the dynamic strength properties upon the static ones for all loading conditions was marked.

  19. 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.

  20. 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

  1. Biomass of freshwater turtles: a geographic comparison

    Energy Technology Data Exchange (ETDEWEB)

    Congdon, J.D.; Greene, J.L.; Gibbons, J.W.

    1986-01-01

    Standing crop biomass of freshwater turtles and minimum annual biomass of egg production were calculated for marsh and farm pond habitats in South Caroling and in Michigan. The species in South Carolina included Chelydra serpentina, Deirochelys reticularia, Kinosternon subrubrum, Pseudemys floridana, P. scripta and Sternotherus odoratus. The species in Michigan were Chelydra serpentina, Chrysemys picta and Emydoidea blandingi. Biomass was also determined for a single species population of P. scripta on a barrier island near Charleston, South Carolina. Population density and biomass of Pseudemys scripta in Green Pond on Capers Island were higher than densities and biomass of the entire six-species community studied on the mainland. In both the farm pond and marsh habitat in South Carolina P. scripta was the numerically dominant species and had the highest biomass. In Michigan, Chrysemys picta was the numerically dominant species; however, the biomass of Chelydra serpentina was higher. The three-species community in Michigan in two marshes (58 kg ha/sup -1/ and 46 kg ha/sup -1/) and farm ponds (23 kg ha/sup -1/) had lower biomasses than did the six-species community in a South Carolina marsh (73 kg/sup -1/). Minimum annual egg production by all species in South Carolina averaged 1.93 kg ha/sup -1/ and in Michigan averaged 2.89 kg ha/sup -1/ of marsh.

  2. Ingestion of Microplastics by Freshwater Tubifex Worms.

    Science.gov (United States)

    Hurley, Rachel R; Woodward, Jamie C; Rothwell, James J

    2017-11-07

    Microplastic contamination of the aquatic environment is a global issue. Microplastics can be ingested by organisms leading to negative physiological impacts. The ingestion of microplastics by freshwater invertebrates has not been reported outside the laboratory. Here we demonstrate the ingestion of microplastic particles by Tubifex tubifex from bottom sediments in a major urban waterbody fed by the River Irwell, Manchester, UK. The host sediments had microplastic concentrations ranging from 56 to 2543 particles kg-1. 87% of the Tubifex-ingested microplastic particles were microfibers (55-4100 μm in length), while the remaining 13% were microplastic fragments (50-4500 μm in length). FT-IR analysis revealed ingestion of a range of polymers, including polyester and acrylic fibers. While microbeads were present in the host sediment matrix, they were not detected in Tubifex worm tissue. The mean concentration of ingested microplastics was 129 ± 65.4 particles g-1 tissue. We also show that Tubifex worms retain microplastics for longer than they retain other particulate components of the ingested sediment matrix. Microplastic ingestion by Tubifex worms poses a significant risk for trophic transfer and biomagnification of microplastics up the aquatic food chain.

  3. Cadmium neurotoxicity to a freshwater planarian.

    Science.gov (United States)

    Wu, Jui-Pin; Lee, Hui-Ling; Li, Mei-Hui

    2014-11-01

    Although freshwater planarians are evolutionarily primitive, they are some of the simplest bilateral animals possessing integrated neural networks similar to those in vertebrates. We attempted to develop planarian Dugesia japonica as a model for investigating the neurotoxicity of environmental pollutants such as cadmium (Cd). This study was therefore designed to study the effects of Cd on the locomotor activity, neurobehavior, and neurological enzymes of D. japonica. After planarians were exposed to Cd at high concentrations, altered neurobehavior was observed that exhibited concentration-dependent patterns. Morphological alterations in Cd-treated planarians included irregular shape, body elongation, screw-like hyperkinesia, and bridge-like position. To study the direct effects of Cd on neurological enzymes, tissue homogenates of planarians were incubated in vitro with Cd before their activity was measured. Results showed that acetylcholinesterase (AChE), adenosine triphosphatase (ATPase), and monoamine oxidase A (MAO-A) activities were inhibited in a concentration-dependent manner. MAO-B activity was significantly induced by Cd at low concentrations and inhibited at high concentrations. Changes in the in vivo activity of AChE and ATPase were also found after planarians were treated with Cd at a sublethal concentration (5.56 μM). These observations indicate that neurotransmission systems in planarians are disturbed after Cd exposure.

  4. The Nature of Surface States on Vicinal Cu (775): An STM and Photoemission Study

    OpenAIRE

    Zaki, Nader; Knox, Kevin; Osgood, Richard M.; Johnson, Peter D.; Fujii, Jun; Vobornik, Ivana; Panaccione, Giancarlo

    2014-01-01

    We report ARPES and a set of in situ STM measurements on a narrow-terrace-width vicinal Cu(111) crystal surface, Cu(775), whose vicinal cut lies close to the transition between terrace and step modulation. These measurements show sharp zone-folding (or Umklapp) features with a periodicity in k||, indicating that the predominant reference plane is that of Cu(775), i.e. that the surface is predominately step-modulated. Our measurements also show variation in Umklapp intensity with photon energy...

  5. Availability, usage, and threats to freshwater resources on low carbonate islands in Micronesia

    Science.gov (United States)

    Taboroši, Danko; Jenson, John W.; Sánchez Collazo, Maricruz; Zega, Mojca

    2010-05-01

    resources are meager and vulnerable. The miniscule size and elongated shape of atoll islets mean that they contain diminutive and dispersed groundwater bodies. Unlike groundwater lenses of typical islands, they are long sausage-shaped "groundwater cylinders", with inconsistent depth and width, and discontinuities depending on local geography. As land reaches barely a few meters above the sea, water penetrating from the surface to base level undergoes practically no filtration in the vadose zone. Furthermore, atoll islets' highly permeable compacted sediments and diagenetically immature reef limestone means that groundwater moves in all directions via high primary porosity and undergoes little filtering even within the phreatic zone. For those reasons, groundwater is easily contaminated by human and animal waste (from outdoor toilets and piggeries) and certain household waste (such as detergent and battery acid), as well as by human burials (for traditional reasons performed in immediate vicinity of households). Local people extract groundwater from shallow hand-dug wells and use it for laundry, showering, and watering animals. During major droughts or other emergencies, groundwater is used for other purposes as well, even for drinking when situation is dire. However, groundwater on some islands is losing its potential as emergency source due to excessive pollution and saltwater intrusion from storm waves and overwhelming tides. The extent of specific problems is different on various islands, but cannot be presently evaluated due to lack of data. This study is the first systematic effort to examine the current availability, usage, and condition of freshwater resources on each and every low island in the FSM. Results are being released in individual island reports as they become available, and are being provided to government planners, resource managers, engineers, educators, environmental scientists, and others dedicated to sustainable use of freshwater resources and

  6. 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 freshwater biodiversity under 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.

  7. Anthropogenic litter in urban freshwater ecosystems: distribution and microbial interactions.

    Directory of Open Access Journals (Sweden)

    Timothy Hoellein

    Full Text Available Accumulation of anthropogenic litter (i.e. garbage; AL and its ecosystem effects in marine environments are well documented. Rivers receive AL from terrestrial habitats and represent a major source of AL to marine environments, but AL is rarely studied within freshwater ecosystems. Our objectives were to 1 quantify AL density in urban freshwaters, 2 compare AL abundance among freshwater, terrestrial, and marine ecosystems, and 3 characterize the activity and composition of AL biofilms in freshwater habitats. We quantified AL from the Chicago River and Chicago's Lake Michigan shoreline, and found that AL abundance in Chicago freshwater ecosystems was comparable to previously reported data for marine and terrestrial ecosystems, although AL density and composition differed among habitats. To assess microbial interactions with AL, we incubated AL and natural substrates in 3 freshwater ecosystems, quantified biofilm metabolism as gross primary production (GPP and community respiration (CR, and characterized biofilm bacterial community composition via high-throughput sequencing of 16S rRNA genes. The main driver of biofilm community composition was incubation location (e.g., river vs pond, but there were some significant differences in biofilm composition and metabolism among substrates. For example, biofilms on organic substrates (cardboard and leaves had lower GPP than hard substrates (glass, plastic, aluminum and tiles. In addition, bacterial communities on organic substrates were distinct in composition from those on hard substrates, with higher relative abundances of bacteria associated with cellulose decomposition. Finally, we used our results to develop a conceptual diagram designed to unite the study of AL in terrestrial and freshwater environments with the well-established field of marine debris research. We suggest this broad perspective will be useful for future studies which synthesize AL sources, ecosystem effects, and fate across

  8. 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.

  9. 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.

  10. 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.

  11. BathymetryB Hillshade [5m]--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for 2-m and 5-m bathymetry and shaded-relief maps of Monterey Canyon and Vicinity, California. The raster data file is included in...

  12. BathymetryA [2m]--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for 2-m and 5-m bathymetry and shaded-relief maps of Monterey Canyon and Vicinity, California. The raster data file is included in...

  13. BathymetryB [5m]--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for 2-m and 5-m bathymetry and shaded-relief maps of Monterey Canyon and Vicinity, California. The raster data file is included in...

  14. BathymetryA Hillshade [2m]--Monterey Canyon and Vicinity, California

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This part of DS 781 presents data for 2-m and 5-m bathymetry and shaded-relief maps of Monterey Canyon and Vicinity, California. The raster data file is included in...

  15. Properties of Soils and Plants Uptake within the Vicinity of Selected ...

    African Journals Online (AJOL)

    Backyard farming is becoming popular among the auto mechanics near their workshops where spent engine oil and carcass of vehicles are continuously dumped in Nigeria. The properties of soil and maize plants sampled from the vicinity of selected auto mechanic workshops in Ile-Ife, Nigeria were investigated. The results ...

  16. Assessment of pollution trend of heavy metals in soils in the vicinity ...

    African Journals Online (AJOL)

    Topsoil and subsoil obtained in the vicinity of the Nigerian Gas Company were digested and analysed for some selected trace metals using atomic absorption spectrophotometer of model pye unicam SP 2900. The trace metals determined include nickel, copper, iron, barium, lead, cadmium and zinc respectively.

  17. Formation and sintering of Pt nanopartictes on vicinal rutile TiO2 surfaces

    DEFF Research Database (Denmark)

    Rieboldt, Felix; Helveg, S.; Bechstein, Ralf

    2014-01-01

    By means of scanning tunnelling microscopy (STM) the nucleation, growth and sintering of platinum nanoparticles (Pt NP's) was studied on vicinal and flat rutile titanium dioxide (TiO2) surfaces. Utilising physical vapour deposition, the nucleation of Pt NP's on TiO2 surfaces at room temperature (...

  18. [Analysis of optical emission spectra from ICP of Ar in the vicinity of plasma sheath].

    Science.gov (United States)

    Zhao, Wen-Feng; Chen, Jun-Fang; Meng, Ran

    2009-11-01

    In order to control the ion density and energy distribution in the vicinity of plasma sheath independently, the inductively coupled plasma and its glow discharge mechanism in the vicinity of plasma sheath were studied by means of optical emission spectroscopy (OES) under different RF power, different discharge and different substrate DC bias voltage. It was shown that the ion density is higher and the electron temperature is lower in the vicinity of inductively coupled plasma sheath according to the ionic line and atomic line. With changing the discharge pressure and RF power, the spectral characteristics analysis shows that the ion density in the vicinity of plasma sheath linearly increases with the RF power and rises with the pressure under the low pressure. The atomic spectral intensity of low excitation states increases rapidly. The atomic spectral intensity of high excitation states rises slowly and the intensity of ion spectrum increases not obviously. By applying the DC bias voltage to substrate, the intensity of emission spectroscopy was analyzed. The result shows that the intensity of spectra rises with the increase in positive bias voltage, while first reduces then increases with the increase in negative bias voltage, and is the weakest in the case of DC bias at -30 V. This shows that the fast ions and the electrons are the main source of energy for Ar ionization and excitation.

  19. Revised Hydrogeology for the Suprabasalt Aquifer System, 200-West Area and Vicinity, Hanford Site, Washington

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Bruce A.; Bjornstad, Bruce N.; Schalla, Ronald; Webber, William D.

    2002-05-14

    The primary objective of this study was to refine the conceptual groundwater flow model for the 200-West Area and vicinity. This is the second of two reports that combine to cover the 200 Area Plateau, an area that holds the largest inventory of radionuclide and chemical waste on the Hanford Site.

  20. Revised Hydrogeology for the Suprabasalt Aquifer System, 200-East Area and Vicinity, Hanford Site, Washington

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Bruce A.; Bjornstad, Bruce N.; Schalla, Ronald; Webber, William D.

    2000-04-20

    This study supports the Hanford Groundwater/Vadose integration project objectives to better understand the risk of groundwater contamination and potential risk to the public via groundwater flow paths. The primary objective of this study was to refine the conceptual groundwater flow model for the 200-East Area and vicinity.

  1. Surface-water quality, Oneida Reservation and vicinity, Wisconsin, 1997-98

    Science.gov (United States)

    Schmidt, Morgan A.; Scudder, Barbara C.; Richards, Kevin D.

    2000-01-01

    Streamwater samples were collected at 19 sites in the vicinity of the Oneida Tribe of Indians of Wisconsin Reservation. Samples were collected during 5 sampling periods in 1997-98. Field measurements were made and samples were analyzed for nutrients, suspended sediment, major ions, and pesticides.

  2. Parental smoking in the vicinity of children and tobacco control policies in the European region

    NARCIS (Netherlands)

    Kovess, V.; Pilowsky, D.J.; Boyd, A.; Pez, O.; Bitfoi, A.; Carta, M.G.; Eke, C.; Golitz, D.; Kuijpers, R.C.W.M.; Lesinskiene, S.; Mihova, Z.; Otten, R.; Susser, E.

    2013-01-01

    Objective: To ascertain patterns of parental smoking in the vicinity of children in Eastern and Western Europe and their relation to Tobacco Control Scale (TCS) scores. Methods: Data on parental smoking patterns were obtained from the School Child Mental Health Europe (SCMHE), a 2010

  3. 14 CFR 91.137 - Temporary flight restrictions in the vicinity of disaster/hazard areas.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Temporary flight restrictions in the vicinity of disaster/hazard areas. 91.137 Section 91.137 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT RULES Flight Rules General §...

  4. Series Resistance Monitoring for Photovoltaic Modules in the Vicinity of MPP

    DEFF Research Database (Denmark)

    Sera, Dezso

    2010-01-01

    the time period with reduced power production. This paper focuses on the estimation of series resistance of flat silicone PV panels or arrays during operation, in the vicinity of their MPP. The method presented in this paper helps to detect failures by monitoring changes in the panel’s or array’s series...

  5. Establishment of background radiation dose rate in the vicinity of the ...

    African Journals Online (AJOL)

    The absorbed dose rate in air in the vicinity of the proposed Manyoni uranium mining project located in Singida region, Tanzania, was determined so as to establish the baseline data for background radiation dose rate data prior to commencement of uranium mining activities. Twenty stations in seven villages were selected ...

  6. 77 FR 71493 - Amendment of VOR Federal Airway V-8 in the Vicinity of Rifle, CO

    Science.gov (United States)

    2012-12-03

    ...This action amends VHF Omnidirectional Range (VOR) Federal Airway V-8 in the vicinity of Rifle, CO, to correct the description contained in part 71 to ensure it matches the information contained in the FAA's aeronautical database, matches the depiction on the associated charts, and to ensure the safety and efficiency of the National Airspace System (NAS).

  7. Parental smoking in the vicinity of children and tobacco control policies in the European region

    NARCIS (Netherlands)

    Kovess, V.; Pilowsky, D.J.; Boyd, A.; Pez, O.; Bitfoi, A.; Carta, M.G.; Eke, C.; Golitz, D.; Kuijpers, R.C.W.M.; Lesinskiene, S.; Mihova, Z.; Otten, R.; Susser, E.S.

    2013-01-01

    Objective: To ascertain patterns of parental smoking in the vicinity of children in Eastern and Western Europe and their relation to Tobacco Control Scale (TCS) scores. Methods: Data on parental smoking patterns were obtained from the School Child Mental Health Europe (SCMHE), a 2010 cross-sectional

  8. Freshwater biodiversity: importance, threats, status and conservation challenges.

    Science.gov (United States)

    Dudgeon, David; Arthington, Angela H; Gessner, Mark O; Kawabata, Zen-Ichiro; Knowler, Duncan J; Lévêque, Christian; Naiman, Robert J; Prieur-Richard, Anne-Hélène; Soto, Doris; Stiassny, Melanie L J; Sullivan, Caroline A

    2006-05-01

    Freshwater biodiversity is the over-riding conservation priority during the International Decade for Action - 'Water for Life' - 2005 to 2015. Fresh water makes up only 0.01% of the World's water and approximately 0.8% of the Earth's surface, yet this tiny fraction of global water supports at least 100000 species out of approximately 1.8 million - almost 6% of all described species. Inland waters and freshwater biodiversity constitute a valuable natural resource, in economic, cultural, aesthetic, scientific and educational terms. Their conservation and management are critical to the interests of all humans, nations and governments. Yet this precious heritage is in crisis. Fresh waters are experiencing declines in biodiversity far greater than those in the most affected terrestrial ecosystems, and if trends in human demands for water remain unaltered and species losses continue at current rates, the opportunity to conserve much of the remaining biodiversity in fresh water will vanish before the 'Water for Life' decade ends in 2015. Why is this so, and what is being done about it? This article explores the special features of freshwater habitats and the biodiversity they support that makes them especially vulnerable to human activities. We document threats to global freshwater biodiversity under five headings: overexploitation; water pollution; flow modification; destruction or degradation of habitat; and invasion by exotic species. Their combined and interacting influences have resulted in population declines and range reduction of freshwater biodiversity worldwide. Conservation of biodiversity is complicated by the landscape position of rivers and wetlands as 'receivers' of land-use effluents, and the problems posed by endemism and thus non-substitutability. In addition, in many parts of the world, fresh water is subject to severe competition among multiple human stakeholders. Protection of freshwater biodiversity is perhaps the ultimate conservation challenge

  9. Parental smoking in the vicinity of children and tobacco control policies in the European region.

    Science.gov (United States)

    Kovess, Viviane; Pilowsky, Daniel J; Boyd, Anders; Pez, Ondine; Bitfoi, Adina; Carta, Mauro; Eke, Ceyda; Golitz, Dietmar; Kuijpers, Rowella; Lesinskiene, Sigita; Mihova, Zlatka; Otten, Roy; Susser, Ezra

    2013-01-01

    To ascertain patterns of parental smoking in the vicinity of children in Eastern and Western Europe and their relation to Tobacco Control Scale (TCS) scores. Data on parental smoking patterns were obtained from the School Child Mental Health Europe (SCMHE), a 2010 cross-sectional survey of 5141 school children aged 6 to 11 years and their parents in six countries: Germany, Netherlands, Lithuania, Romania, Bulgaria and Turkey ranked by TCS into three level categories toward tobacco control policies. A slightly higher proportion of Eastern compared to Western European mothers (42.4 vs. 35.1%) were currently smoking in but the difference was not statistically significant after adjusting for maternal age and maternal educational attainment. About a fifth (19.3%) and a tenth (10.0%) of Eastern and Western European mothers, respectively, smoked in the vicinity of their children, and the difference was significant even after adjustment for potential confounders (pParents with the highest educational attainment were significantly less likely to smoke in the vicinity of their children than those with the lowest attainment. After control of these covariates lax tobacco control policies, compared to intermediate policies, were associated with a 50% increase in the likelihood of maternal smoking in the vicinity of children adjusted odds ratio (AOR) = 1.52 and 1.64. Among fathers, however, the relationship with paternal smoking and TCS seems more complex since strict policy increases the risk as well AOR = 1,40. Only one country, however belongs to the strict group. Tobacco control policies seem to have influenced maternal smoking behaviors overall to a limited degree and smoking in the vicinity of children to a much greater degree. Children living in European countries with lax tobacco control policies are more likely to be exposed to second hand smoking from maternal and paternal smoking.

  10. Parental smoking in the vicinity of children and tobacco control policies in the European region.

    Directory of Open Access Journals (Sweden)

    Viviane Kovess

    Full Text Available OBJECTIVE: To ascertain patterns of parental smoking in the vicinity of children in Eastern and Western Europe and their relation to Tobacco Control Scale (TCS scores. METHODS: Data on parental smoking patterns were obtained from the School Child Mental Health Europe (SCMHE, a 2010 cross-sectional survey of 5141 school children aged 6 to 11 years and their parents in six countries: Germany, Netherlands, Lithuania, Romania, Bulgaria and Turkey ranked by TCS into three level categories toward tobacco control policies. RESULTS: A slightly higher proportion of Eastern compared to Western European mothers (42.4 vs. 35.1% were currently smoking in but the difference was not statistically significant after adjusting for maternal age and maternal educational attainment. About a fifth (19.3% and a tenth (10.0% of Eastern and Western European mothers, respectively, smoked in the vicinity of their children, and the difference was significant even after adjustment for potential confounders (p<0.001. Parents with the highest educational attainment were significantly less likely to smoke in the vicinity of their children than those with the lowest attainment. After control of these covariates lax tobacco control policies, compared to intermediate policies, were associated with a 50% increase in the likelihood of maternal smoking in the vicinity of children adjusted odds ratio (AOR = 1.52 and 1.64. Among fathers, however, the relationship with paternal smoking and TCS seems more complex since strict policy increases the risk as well AOR = 1,40. Only one country, however belongs to the strict group. SIGNIFICANCE: Tobacco control policies seem to have influenced maternal smoking behaviors overall to a limited degree and smoking in the vicinity of children to a much greater degree. Children living in European countries with lax tobacco control policies are more likely to be exposed to second hand smoking from maternal and paternal smoking.

  11. Impact of freshwater diversion projects on diversity and activity of methanotrophic communities in freshwater wetlands

    Science.gov (United States)

    Isaac, J.; Schulz, C. J.; Childers, G. W.

    2009-12-01

    Methanotrophic bacteria are key players in the carbon cycle capable of using methane as a sole carbon and energy source. Methanotrophs are ubiquitous in soil environments and play a key role in decreasing methane flux from anaerobic environments to the atmosphere, reducing the concentration of this greenhouse gas. Wetlands are a particularly important source of methane to the atmosphere, even though methanotrophs can consume the majority of the methane produced. Decreases in methanotrophic activity in wetland environments due to disturbance can have negative impacts with regard to greenhouse gas emissions, especially if the impact is widespread. Currently, several freshwater diversion projects are active and/or scheduled to come online in south Louisiana, delivering freshwater, sediments, and nutrients to coastal wetlands en masse to help combat subsidence and coastal erosion. Along with freshwater, these diversions also deliver other components of the Mississippi River including substantial bicarbonate alkalinity, reactive nitrogen, and sulfate. Analogous to the large scale diversion projects are smaller restoration projects that deliver treated wastewater effluent to wetlands. In particular, the Joyce Wildlife Management Area (JWMA) in southeast Louisiana has been the recipient of ~5 million gallons of treated domestic effluent per day since 2006. Both the composition of the marsh receiving the effluent and the effluent itself have similarities to Mississippi River diversions. We collected pre and post JWMA sediment microbial community DNA and created cloned libraries of genes encoding particulate methane monooxygenase (pmoA) as a proxy for methanotrophic community composition. Water chemistry data was also collected. Shifts in methanotrophic community composition were apparent as well as shifts in water chemistry. The most notable shift in water chemistry was pH, which changed from mildly acidic to slightly alkaline conditions, due to the increased alkalinity of

  12. 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.

  13. Fungi in freshwaters: ecology, physiology and biochemical potential.

    Science.gov (United States)

    Krauss, Gerd-Joachim; Solé, Magali; Krauss, Gudrun; Schlosser, Dietmar; Wesenberg, Dirk; Bärlocher, Felix

    2011-07-01

    Research on freshwater fungi has concentrated on their role in plant litter decomposition in streams. Higher fungi dominate over bacteria in terms of biomass, production and enzymatic substrate degradation. Microscopy-based studies suggest the prevalence of aquatic hyphomycetes, characterized by tetraradiate or sigmoid spores. Molecular studies have consistently demonstrated the presence of other fungal groups, whose contributions to decomposition are largely unknown. Molecular methods will allow quantification of these and other microorganisms. The ability of aquatic hyphomycetes to withstand or mitigate anthropogenic stresses is becoming increasingly important. Metal avoidance and tolerance in freshwater fungi implicate a sophisticated network of mechanisms involving external and intracellular detoxification. Examining adaptive responses under metal stress will unravel the dynamics of biochemical processes and their ecological consequences. Freshwater fungi can metabolize organic xenobiotics. For many such compounds, terrestrial fungal activity is characterized by cometabolic biotransformations involving initial attack by intracellular and extracellular oxidative enzymes, further metabolization of the primary oxidation products via conjugate formation and a considerable versatility as to the range of metabolized pollutants. The same capabilities occur in freshwater fungi. This suggests a largely ignored role of these organisms in attenuating pollutant loads in freshwaters and their potential use in environmental biotechnology. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  14. 33 CFR 334.1120 - Pacific Ocean in the vicinity of Point Mugu, Calif.; naval small arms firing range.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Pacific Ocean in the vicinity of Point Mugu, Calif.; naval small arms firing range. 334.1120 Section 334.1120 Navigation and Navigable... REGULATIONS § 334.1120 Pacific Ocean in the vicinity of Point Mugu, Calif.; naval small arms firing range. (a...

  15. 33 CFR 334.620 - Straits of Florida and Florida Bay in vicinity of Key West, Fla.; operational training area...

    Science.gov (United States)

    2010-07-01

    ... Bay in vicinity of Key West, Fla.; operational training area, aerial gunnery range, and bombing and strafing target areas, Naval Air Station, Key West, Fla. 334.620 Section 334.620 Navigation and Navigable... REGULATIONS § 334.620 Straits of Florida and Florida Bay in vicinity of Key West, Fla.; operational training...

  16. Tidal freshwater wetland herbivory in Anacostia Park

    Science.gov (United States)

    Krafft, Cairn; Hatfield, Jeff S.; Hammerschlag, Richard S.

    2010-01-01

    Herbivory has played a major role in dictating vegetation abundance and species composition at Kingman Marsh in Anacostia Park, Washington, D.C., since restoration of this tidal freshwater wetland was initiated in 2000. In June 2009 an herbivory study was established to document the impacts of resident Canada goose (Branta canadensis maxima) herbivory to vegetation at Kingman Marsh. Sixteen modules consisting of paired exclosed plots and unfenced control plots were constructed. Eight of the modules were installed in vegetated portions of the restoration site that had been protected over time by fencing, while the remaining eight modules were placed in portions of the site that had not been protected over time and were basically unvegetated at the start of the experiment. Since the experiment was designed to determine the impacts of herbivory by resident Canada geese as opposed to other herbivores, exclosure fencing was elevated 0.2 m to permit access by herbivores such as fish and turtles while excluding mature Canada geese. Repeated measures analysis of variance (ANOVA) was used to analyze the differences between paired exclosure and control plots for a number of variables including total vegetative cover. Differences in total vegetative cover were not significant for the baseline data collected in June. By contrast, two months after the old protective fencing was removed from the initially-vegetated areas to allow Canada geese access to the control plots, total vegetative cover had declined dramatically in the initially-vegetated control plots, and differences between paired exclosed and control plots were significant (P = 0.0026). No herbivory by Canada geese or other herbivores such as fish or turtles was observed in the exclosures. These results show that Canada goose herbivory has inflicted significant damage to the native wetland vegetation in the portions of Kingman Marsh that had been refenced and replanted. Significant differences in total vegetative

  17. Assessing and managing freshwater ecosystems vulnerable to environmental change.

    Science.gov (United States)

    Angeler, David G; Allen, Craig R; Birgé, 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.

  18. 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 (conservation priorities based on a single freshwater aquatic group would not protect all species in the other aquatic groups.

  19. There and back again: migration in freshwater fishes

    DEFF Research Database (Denmark)

    Brönmark, C.; Hulthén, K.; Nilsson, P.A.

    2013-01-01

    that migration occurs in a range of freshwater fish taxa from many different habitats. In this review we focus on the causes and consequences of migration in freshwater fishes. We start with an introduction of concepts and categories of migration, and then address the evolutionary causes that drive individuals...... to make these migratory journeys. The basis for the decision of an individual fish to migrate or stay resident is an evaluation of the costs and benefits of different strategies to maximize its lifetime reproductive effort. We provide examples by discussing our own work on the causes behind seasonal......Animal migration is an amazing phenomenon that has fascinated humans for long. Many freshwater fishes also show remarkable migrations, whereof the spectacular mass migrations of salmonids from the spawning streams are the most well known and well studied. However, recent studies have shown...

  20. 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

  1. Patterns of Freshwater Species Richness, Endemism, and Vulnerability in California.

    Science.gov (United States)

    Howard, Jeanette K; Klausmeyer, Kirk R; Fesenmyer, Kurt A; Furnish, Joseph; Gardali, Thomas; Grantham, Ted; Katz, Jacob V E; Kupferberg, Sarah; McIntyre, Patrick; Moyle, Peter B; Ode, Peter R; Peek, Ryan; Quiñones, Rebecca M; Rehn, Andrew C; Santos, Nick; Schoenig, Steve; Serpa, Larry; Shedd, Jackson D; Slusark, Joe; Viers, Joshua H; Wright, Amber; Morrison, Scott A

    2015-01-01

    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 implement adequate

  2. 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

  3. 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.

  4. Susceptibility of 7 freshwater gastropod species in Zimbabwe to infection with Gastrodiscus aegyptiacus (Cobbold, 1876) Looss, 1896.

    Science.gov (United States)

    Mukaratirwa, S; Munjere, I F; Takawira, M; Chingwena, G

    2004-12-01

    Gastrodiscosis outbreaks due to Gastrodiscus aegyptiacus were recorded in horses in the vicinity of Harare, Zimbabwe, in the absence of Bulinus forskalii, B. senegalensis and Cleopatra sp. which are considered to be the only intermediate host snails. This suggested the possibility of other snail species acting as intermediate hosts in the life cycle of the trematode. A study was carried out to determine the susceptibility of 7 freshwater snail species to infection with G. aegyptiacus. First generation (F-1) of 5 freshwater pulmonate snail species, Bulinus tropicus, Bulinus globosus, Biomphalaria pfeifferi, Helisoma dyuri and Physa acuta that were bred in the laboratory, and 2 prosobranch snail species, Melanoides tuberculata and Cleopatra sp. that were collected from the field were used in this study. Data pertaining to mortalities and cercariae shedding were recorded throughout the experimental period. The prosobranch snails, M. tuberculata and Cleopatra sp. were susceptible to G. aegyptiacus with a minimum prepatent period of 45 days and 54 days, respectively. Bulinus tropicus, P. acuta and H. duryi were susceptible as evidenced by the presence of different generations of rediae and mature cercariae on dissection at 59 days post-infection although attempts to induce the snails to shed from 28 days post-infection did not produce cercariae. Bulinus globosus and Bio. pfeifferi were refractory to infection. The results revealed the ability of G. aegyptiacus to infect M. tuberculata, Cleopatara sp., B. tropicus, P. acuta and H. duryi under experimental conditions and this may explain the recorded outbreaks of gastrodiscosis in equine populations in Zimbabwe in the absence of the known intermediate hosts. Bulinus tropicus is considered as the most likely major intermediate host of G. aegyptiacus because of its wide distribution in Zimbabwe and is well adapted to a wide variety of environments.

  5. Susceptibility of 7 freshwater gastropod species in Zimbabwe to infection with Gastrodiscus aegyptiacus (Cobbold, 1876 Looss, 1896 : short communication

    Directory of Open Access Journals (Sweden)

    S. Mukaratirwa

    2004-06-01

    Full Text Available Gastrodiscosis outbreaks due to Gastrodiscus aegyptiacus were recorded in horses in the vicinity of Harare, Zimbabwe, in the absence of Bulinus forskalii, B. senegalensis and Cleopatra sp. which are considered to be the only intermediate host snails. This suggested the possibility of other snail species acting as intermediate hosts in the life cycle of the trematode. A study was carried out to determine the susceptibility of 7 freshwater snail species to infection with G. aegyptiacus. First generation (F-1 of 5 freshwater pulmonate snail species, Bulinus tropicus, Bulinus globosus, Biomphalaria pfeifferi, Helisoma dyuri and Physa acuta that were bred in the laboratory, and 2 prosobranch snail species, Melanoides tuberculata and Cleopatra sp. that were collected from the field were used in this study. Data pertaining to mortalities and cercariae shedding were recorded throughout the experimental period. The prosobranch snails, M. tuberculata and Cleopatra sp. were susceptible to G. aegyptiacus with a minimum prepatent period of 45 days and 54 days, respectively. Bulinus tropicus, P. acuta and H. duryi were susceptible as evidenced by the presence of different generations of rediae and mature cercariae on dissection at 59 days post-infection although attempts to induce the snails to shed from 28 days post-infection did not produce cercariae. Bulinus globosus and Bio. Pfeifferi were refractory to infection. The results revealed the ability of G. aegyptiacus to infect M. tuberculata, Cleopatara sp., B. tropicus, P. acuta and H. duryi under experimental conditions and this may explain the recorded outbreaks of gastrodiscosis in equine populations in Zimbabwe in the absence of the known intermediate hosts. Bulinus tropicus is considered as the most likely major intermediate host of G. aegyptiacus because of its wide distribution in Zimbabwe and is well adapted to a wide variety of environments.

  6. 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

  7. Freshwater flushing time scales of the Vashishti Estuary, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    DineshKumar, P.K.; Sarma, R.V.; Zingde, M.D.

    Results are presented for the Vashishti estuary, Kerala, India to evaluate its freshwater flushing time scales based on 8 sets of observations of longitudinal salinity distributions. The results of the flushing time using the fraction of freshwater...

  8. Salinity tolerances of two Australian freshwater turtles, Chelodina expansa and Emydura macquarii (Testudinata: Chelidae)

    OpenAIRE

    Bower, Deborah S; Scheltinga, David M.; Clulow, Simon; Clulow, John; Franklin, Craig E.; Georges, Arthur

    2016-01-01

    Freshwater biota experience physiological challenges in regions affected by salinization, but often the effects on particular species are poorly understood. Freshwater turtles are of particular concern as they appear to have limited ability to cope with environmental conditions that are hyperosmotic to their body fluids. Here, we determined the physiological responses of two Australian freshwater chelid turtles, Emydura macquarii and Chelodina expansa, exposed to freshwater (0?) and brackish ...

  9. Electric and magnetic field testing in vicinity of 110/x kV substations

    Directory of Open Access Journals (Sweden)

    Grbić Maja

    2016-01-01

    Full Text Available The levels of non-ionizing radiation (electric and magnetic fields at power frequency, which occur near 110/x kV substations are analyzed in this paper. The results of electric field strength and magnetic flux density measurements in the vicinity of three typical substations of the aforementioned voltage level are shown. With the purpose of estimating the exposure of the population to these fields, the obtained results were compared to the reference maximum levels set for increased sensitivity areas, which amount to 2 kV/m for electric field and 40 μT for magnetic flux density. The objective of the conducted analysis is to reach general conclusions on the levels of electric and magnetic fields, which may occur in the vicinity of the substations mentioned above, and evaluate their compliance with the national regulations on the population protection from non-ionizing radiation.

  10. DFT Study of the Molybdenum-Catalyzed Deoxydehydration of Vicinal Diols

    DEFF Research Database (Denmark)

    Lupp, Daniel; Christensen, Niels Johan; Dethlefsen, Johannes Rytter

    2015-01-01

    The mechanism of the molybdenum-catalyzed deoxydehydration (DODH) of vicinal diols has been investigated using density functional theory. The proposed catalytic cycle involves condensation of the diol with an MoVI oxo complex, oxidative cleavage of the diol resulting in an MoIV complex, and extru......The mechanism of the molybdenum-catalyzed deoxydehydration (DODH) of vicinal diols has been investigated using density functional theory. The proposed catalytic cycle involves condensation of the diol with an MoVI oxo complex, oxidative cleavage of the diol resulting in an MoIV complex......, and extrusion of the alkene. We have compared the proposed pathway with several alternatives, and the results have been corroborated by comparison with the molybdenum- catalyzed sulfoxide reduction recently published by Sanz et al. and with experimental observations for the DODH itself. Improved understanding...

  11. Temperature dependence of magnetic anisotropies in ultrathin Fe film on vicinal Si(111)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yong-Sheng; He, Wei; Ye, Jun; Hu, Bo; Tang, Jin; Zhang, Xiang-Qun [State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Cheng, Zhao-Hua, E-mail: zhcheng@aphy.iphy.ac.cn [State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190 (China)

    2017-05-01

    The temperature dependence of magnetic anisotropy of ultrathin Fe film with different thickness epitaxially grown on vicinal Si(111) substrate has been quantitatively investigated using the anisotropic magnetoresistance(AMR) measurements. Due to the effect of the vicinal substrate, the magnetic anisotropy is the superposition of a four-fold, a two-fold and a weakly six-fold contribution. It is found that the temperature dependence of the first-order magnetocrystalline anisotropies coefficient follows power laws of the reduced magnetization m(T)(=M(T)/M(0)) being consistent with the Callen and Callen's theory. However the temperature dependence of uniaxial magnetic anisotropy (UMA) shows novel behavior that decreases roughly as a function of temperature with different power law for samples with different thickness. We also found that the six-fold magnetocrystalline anisotropy is almost invariable over a wide temperature range. Possible mechanisms leading to the different exponents are discussed.

  12. Impact of nucleation on step-meandering instabilities during step-flow growth on vicinal surfaces.

    Science.gov (United States)

    Beausoleil, A; Desjardins, P; Rochefort, A

    2014-03-01

    Step-meandering instabilities can manifest during step-flow growth on vicinal surfaces [Bales and Zangwill, Phys. Rev. B 41, 5500 (1990); Pierre-Louis, D'Orsogna, and Einstein, Phys. Rev. Lett. 82, 3661 (1999)]. A phase diagram based on the various growth regimes of a vicinal surface allows us to study the impact of nucleation on these meanders and to predict a meandering instability caused by the nucleation and the coalescence of both islands and steps. Using an accelerated kinetic Monte Carlo method, we find that the coalescence of islands with steps produces large protrusions and deep ripples and that the resulting meandering instability is reinforced by the growth of the islands at almost the same positions from one monolayer to the other. A coarsening phenomenon occurs for the instability wavelength until mounds appear, favored by a large Ehrlich-Schwoebel barrier. Such a meandering instability could be exploited for periodic self-assembly.

  13. 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.

  14. Host diversity and latitude drive trematode diversity patterns in the European freshwater fauna

    NARCIS (Netherlands)

    Thieltges, D.W.; Hof, C.; Dehling, D.M.; Brändle, M.; Brändl, R.; Poulin, R.

    2011-01-01

    Aim We investigated the relationship between host and parasite diversity as well as latitudinal gradients in parasite diversity on a continental scale in European freshwater trematodes.
    Location European freshwaters.
    Methods We extracted distributional data for 564 freshwater trematodes across

  15. 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...

  16. 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:

  17. Stable isotope study of a new chondrichthyan fauna (Kimmeridgian, Porrentruy, Swiss Jura): an unusual freshwater-influenced isotopic composition for the hybodont shark Asteracanthus

    Science.gov (United States)

    Leuzinger, L.; Kocsis, L.; Billon-Bruyat, J.-P.; Spezzaferri, S.; Vennemann, T.

    2015-12-01

    Chondrichthyan teeth (sharks, rays, and chimaeras) are mineralized in isotopic equilibrium with the surrounding water, and parameters such as water temperature and salinity can be inferred from the oxygen isotopic composition (δ18Op) of their bioapatite. We analysed a new chondrichthyan assemblage, as well as teeth from bony fish (Pycnodontiformes). All specimens are from Kimmeridgian coastal marine deposits of the Swiss Jura (vicinity of Porrentruy, Ajoie district, NW Switzerland). While the overall faunal composition and the isotopic composition of bony fish are generally consistent with marine conditions, unusually low δ18Op values were measured for the hybodont shark Asteracanthus. These values are also lower compared to previously published data from older European Jurassic localities. Additional analyses on material from Solothurn (Kimmeridgian, NW Switzerland) also have comparable, low-18O isotopic compositions for Asteracanthus. The data are hence interpreted to represent a so far unique, freshwater-influenced isotopic composition for this shark that is classically considered a marine genus. While reproduction in freshwater or brackish realms is established for other hybodonts, a similar behaviour for Asteracanthus is proposed here. Regular excursions into lower salinity waters can be linked to the age of the deposits and correspond to an ecological adaptation, most likely driven by the Kimmeridgian transgression and by the competition of the hybodont shark Asteracanthus with the rapidly diversifying neoselachians (modern sharks).

  18. Electric and magnetic field testing in vicinity of 110/x kV substations

    OpenAIRE

    Grbić Maja; Pavlović Aleksandar; Hrvić Dejan; Vulević Branislav

    2016-01-01

    The levels of non-ionizing radiation (electric and magnetic fields) at power frequency, which occur near 110/x kV substations are analyzed in this paper. The results of electric field strength and magnetic flux density measurements in the vicinity of three typical substations of the aforementioned voltage level are shown. With the purpose of estimating the exposure of the population to these fields, the obtained results were compared to the reference maximum levels set for increased sensitivi...

  19. Turbulent flow in a ribbed channel: Flow structures in the vicinity of a rib

    DEFF Research Database (Denmark)

    Wang, Lei; Salewski, Mirko; Sundén, Bengt

    2010-01-01

    PIV measurements are performed in a channel with periodic ribs on one wall. The emphasis of this study is to investigate the flow structures in the vicinity of a rib in terms of mean velocities, Reynolds stresses, probability density functions (PDF), and two-point correlations. The PDF distribution......-based visualization is applied to the separation bubble upstream of the rib. Salient critical points and limit cycles are extracted, which gives clues to the physical processes occurring in the flow....

  20. Flow- topography Interactions in the Vicinity of a Deep Ocean Island and a Ridge

    Science.gov (United States)

    2015-09-30

    moored platforms. 2 WORK COMPLETED Attend the FLEAT planning meeting in June 2015 at Scripps Institute of Oceanography. Preliminary deep -mooring...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Flow-topography Interactions in the Vicinity of a Deep ...located north of Palau covers the submarine ridge, while the second mooring-line coveres deep slopes and the shallow bank just north of Palau (Figure 1

  1. Magnetostrictive hypersound generation by spiral magnets in the vicinity of magnetic field induced phase transition

    Energy Technology Data Exchange (ETDEWEB)

    Bychkov, Igor V. [Chelyabinsk State University, 129 Br. Kashirinykh Str., Chelyabinsk 454001 (Russian Federation); South Ural State University (National Research University), 76 Lenin Prospekt, Chelyabinsk 454080 (Russian Federation); Kuzmin, Dmitry A., E-mail: kuzminda@csu.ru [Chelyabinsk State University, 129 Br. Kashirinykh Str., Chelyabinsk 454001 (Russian Federation); South Ural State University (National Research University), 76 Lenin Prospekt, Chelyabinsk 454080 (Russian Federation); Kamantsev, Alexander P.; Koledov, Victor V.; Shavrov, Vladimir G. [Kotelnikov Institute of Radio-engineering and Electronics of RAS, Mokhovaya Street 11-7, Moscow 125009 (Russian Federation)

    2016-11-01

    In present work we have investigated magnetostrictive ultrasound generation by spiral magnets in the vicinity of magnetic field induced phase transition from spiral to collinear state. We found that such magnets may generate transverse sound waves with the wavelength equal to the spiral period. We have examined two types of spiral magnetic structures: with inhomogeneous exchange and Dzyaloshinskii–Moriya interactions. Frequency of the waves from exchange-caused spiral magnetic structure may reach some THz, while in case of Dzyaloshinskii–Moriya interaction-caused spiral it may reach some GHz. These waves will be emitted like a sound pulses. Amplitude of the waves is strictly depends on the phase transition speed. Some aspects of microwaves to hypersound transformation by spiral magnets in the vicinity of phase transition have been investigated as well. Results of the work may be interesting for investigation of phase transition kinetics as well, as for various hypersound applications. - Highlights: • Magnetostrictive ultrasound generation by spiral magnets at phase transition (PT) is studied. • Spiral magnets during PT may generate transverse sound with wavelength equal to spiral period. • Amplitude of the sound is strictly depends on the phase transition speed. • Microwave-to-sound transformation in the vicinity of PT is investigated as well.

  2. Vectors of invasions in freshwater invertebrates and fishes

    Science.gov (United States)

    Fuller, Pamela L.; Canning-Clode, João

    2015-01-01

    Without human assistance, the terrestrial environment and oceans represent barriers to the dispersal of freshwater aquatic organisms. The ability to overcome such barriers depends on the existence of anthropogenic vectors that can transport live organisms to new areas, and the species’ biology to survive the transportation and transplantation into the new environment (Johnson et al., 2006).

  3. Biomass, Mineral Elements and Protein Contents of Six Freshwater ...

    African Journals Online (AJOL)

    Biomass, Mineral Elements and Protein Contents of Six Freshwater Macrophytes from Ghana. ... Ghana Journal of Science ... The fresh and dry weights of the plants were measured and the concentration of six elements: calcium, magnesium, nitrogen, phosphorus, potassium and sodium in the tissues of the plants were ...

  4. Evidence of Bald Eagles feeding on freshwater mussels

    Science.gov (United States)

    Teryl G. Grubb; Michael A. Coffey

    1982-01-01

    A 1978 study of the winter habitat of the Bald Eagle (Haliaeetus leucocephalus) in the Coconino National Forest, Arizona, indicated repeated and potentially heavy use of a freshwater mussel (Anodonta corpulenta) in the eagles’ diet. As many as 10 eagles (five adults and five immatures) were observed at Upper Lake Mary near...

  5. Stimulatory activity of four green freshwater sponges on aquatic ...

    African Journals Online (AJOL)

    SMG

    African Journal of Biotechnology. Full Length Research Paper. Stimulatory activity of four green freshwater sponges on aquatic mycotal communities. Bazyli Czeczuga*, Ewa Czeczuga- Semeniuk, Adrianna Semeniuk- Grell and. Janusz Semeniuk. Department of General Biology, Medical University, Mickiewicza 2C, 15-222 ...

  6. Tropical Freshwater Biology - Vol 18, No 2 (2009)

    African Journals Online (AJOL)

    A mesocosm analytical study on the ecological interactions of certain benthos in response to the biodeposition and bioturbation activities of the freshwater mussel Lamellidens ... Impacts of petroleum hydrocarbons on fish communities of river Areba, Niger Delta, Southern Nigeria · EMAIL FULL TEXT EMAIL FULL TEXT

  7. Establishing a database of radionuclide transfer parameters for freshwater wildlife.

    Science.gov (United States)

    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; Barnett, C L; Copplestone, D

    2013-12-01

    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 (CRwo-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 CRwo-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 CRwo-water values for freshwater species currently available for use in radiological environmental assessments. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Herbivory on freshwater and marine macrophytes : A review and perspective

    NARCIS (Netherlands)

    Bakker, Elisabeth S.; Wood, Kevin A.; Pages, Jordi F.; Veen, G. F. (Ciska); Christianen, Marjolijn J. A.; Santamaria, 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

  9. Herbivory on freshwater and marine macrophytes: a review and perspective

    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

  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. researcii note haematological studies on some freshwater teleosts

    African Journals Online (AJOL)

    order to provide an economical source of high protein diets. ... therefore of the utmost importance to establish base line ... lactic acid, ATP and total protein concentrations, com- ... Fourie (1974) for common carp in their natural habitat. .... Bloodsugar as an indicator of stress in the freshwater fishl,abeo capensis (Smith).

  12. Population growth of three freshwater prawns ( Macrobrachium spp ...

    African Journals Online (AJOL)

    Growth parameters of the populations of three freshwater prawns: Macrobrachium vollenhovenii, M. macrobrachion and M. felicinum in the Lower Ogun River were determined. For each population, lengthfrequency data for twenty-four month period (January 2006-December 2007) were analysed to determine the growth ...

  13. Review of the Freshwater Eels of Iran (Family Anguillidae)

    OpenAIRE

    Brian W. Coad

    2016-01-01

    The systematics, morphology, distribution, biology, economic importance and conservation of the freshwater eel (Anguilla anguilla) of Iran are described, the species is illustrated, and a bibliography on this fish in Iran is provided. The species is found in the Caspian Sea basin as an exotic.

  14. Effect of aeration on selected water quality parameters in freshwater ...

    African Journals Online (AJOL)

    Freshwater fish culture water was passed through the devices and analysed for Temperature, pH, Alkalinity and Dissolved oxygen (DO) in the morning, afternoon and evening. The percentage modification was used to measure the effect of aeration on the selected water quality parameters. Temperature modification ranged ...

  15. Viruses of freshwater finfish in the asian-pacific region.

    Science.gov (United States)

    Sahoo, P K; Goodwin, A E

    2012-09-01

    There has been a tremendous increase in global demand for marine and freshwater fish to meet the protein needs of our expanding human population. However, due to the limited capacity of the wild-capture sector and a levelling of production from capture fisheries, the practice of farming aquatic animals has expanded rapidly to become a major global industry. Aquaculture, particularly freshwater aquaculture is now integral to the economies of many countries. A large number of aquatic animal species are farmed in high density in freshwater, brackish and marine systems, where they are exposed to new environments and potentially new diseases. Further, environmental stress factors, the use of manufactured feeds, and prolific global trade has led to the emergence and spread of new diseases. Viral pathogens, established for decades or newly emerging as disease threats, are particularly challenging since there are few efficacious treatments. Vaccines have been developed for some viral fish pathogens in salmonids, but vaccines are not available for many of the viral pathogens important in Asia. Control and eradication programs are difficult because many viral infections remain latent until adverse environmental conditions, such as overcrowding or poor water quality, trigger the onset of disease. Here, we review the more significant viral pathogens of finfish in the Asia-Pacific including both those with a long history in Asian aquaculture and emerging pathogens including betanodaviruses and koi herpes virus that have caused massive losses in the freshwater aquaculture and ornamental fish industries.

  16. 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

  17. Modeling the fate and transport of plastic debris in freshwaters

    NARCIS (Netherlands)

    Kooi, Merel; Besseling, Ellen; Kroeze, Carolien; Wenzel, van Annemarie P.; Koelmans, Albert A.

    2018-01-01

    Contamination with plastic debris has been recognized as one of today’s major environmental quality problems. Because most of the sources are land based, concerns are increasingly focused on the freshwater and terrestrial environment. Fate and transport models for plastic debris can complement

  18. Effect of exposure to cadmium on the tropical freshwater prawn ...

    African Journals Online (AJOL)

    The effect of cadmium (Cd) on mortality, resistance and bioaccumulation in the tropical freshwater prawn Macrobrachium rosenbergii from Egypt were studied. Survival of prawns exposed to Cd doses over 60 μg l-1 were sig nificantly lower than that of prawns exposed to lower doses. After 96 h prawns ex posed to >40 μg ...

  19. Macro-invertebrate predatorsof freshwater pulmonate snails in Africa ...

    African Journals Online (AJOL)

    A range of African and alien macro-invertebrates has been reported preying on freshwater pulmonate snails, including those that serve as intermediate hosts for bloodflukes of the genus Schistosoma. Predation by five molluscivorous taxa is reviewed here: indigenous leeches (Glossiphoniidae), marsh fly larvae ...

  20. Aquaculture research at the Conservation Fund Freshwater Institute

    Science.gov (United States)

    The Conservation Fund Freshwater Institute (TCFFI), working through cooperative agreements with the USDA Agriculture Research Service, has become a global leader in research and development of land-based closed containment water recirculation aquaculture systems (RAS) following three decades of appl...

  1. 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...

  2. Molecular diversity of avian schistosomes in Danish freshwater snails

    DEFF Research Database (Denmark)

    Christiansen, Anne Ø.; Olsen, Annette; Buchmann, Kurt

    2016-01-01

    to identify the parasites at species level. In order to do that, 499 pulmonate freshwater snails (Radix sp., Lymnaea stagnalis, Stagnicola sp. and Planorbarius corneus) were sampled from 12 lakes, ponds, and marshes in the greater Copenhagen area. Avian schistosome cercariae were identified by microscopy...

  3. Estimating the recreational value of freshwater inflows into the Klein ...

    African Journals Online (AJOL)

    This study estimates the change in aggregate consumer surplus associated with increased freshwater supply into two South African estuaries, namely, the Klein and the Kwelera. The estimation entailed the application of a contingent behaviour, single-site Clawson-Knetsch travel cost model. The value estimates derived ...

  4. Aspects of Water Quality of Freshwater Systems Harbouring Snail ...

    African Journals Online (AJOL)

    A study of some aspects of water quality of freshwater systems harbouring snail vectors of schistosome parasites was conducted in Jos, Nigeria. Calcium ion concentration of the water bodies was a mean value of 31 mg.l-1. The range of temperature was 15 - 30OC. The occurrence of Biomphalaria pferifferi was attributed to ...

  5. Agriculture and eutrophication of freshwaters: a review of control ...

    African Journals Online (AJOL)

    Agriculture contributes a larger percentage of phosphorus (P) to freshwaters eutrophication. Fertilizers and manures applications over a period of time lead to P soil build up exceeding the required needs of the crops. Excess P is transferred into the waters through runoff, erosion, leaching and artificial drainage which ...

  6. SOME PARASITIC WORMS IN FRESHWATER FISHES AND FISH ...

    African Journals Online (AJOL)

    appear that more studies on the parasitic worms from African freshwater fishes and amphibians might produce more evidence of their ancient zoogeography, particularly in relation to con- tinental drift. MATERIALS AND METHODS. The material described in this paper was obtained by Mr B. C. W. van der Waal from fishes.

  7. Insights into the bacterial diversity in a freshwater-deprived ...

    African Journals Online (AJOL)

    The aim of this study was to conduct an investigation into the bacterial diversity in the freshwater-deprived Kariega Estuary, situated along the Eastern Cape coastline, using ribosomal RNA gene sequences obtained by pyrosequencing. Shifts in the microbial diversity were correlated to selected physico-chemical variables ...

  8. Ecological survey of freshwater ecosystems of Ovia, Edo state ...

    African Journals Online (AJOL)

    The survey for freshwater snails in streams, rivers and a lake in Ovia Southwest LGA of Edo State, Nigeria was carried out from June to November, 2013. Samples were collected by using sweep-net and by hand picking of snails within the open water habitat, at marginal areas and on submerged vegetation at edges of the ...

  9. Snails promote methane release from a freshwater lake ecosystem

    Directory of Open Access Journals (Sweden)

    Xiao eXu

    2014-05-01

    Full Text Available Benthic fauna, as ecosystem engineers, can strongly affect microbial-driven ecosystem biogeochemical cycling. However, the effects of benthic fauna, especially epifauna, on CH4 cycling remain still elusive. In this study, CH4 effluxes were both measured along a gradient of snail density in a freshwater lake ecosystem in China, and monitored in manipulated laboratory microcosms with and without snails. Field CH4 efflux was significantly increased with snail density. Likewise, the stimulating effects of freshwater snails on CH4 effluxes were evident in the homogenised indoor microcosms. These results show that snails can stimulate CH4 efflux in the freshwater lake ecosystem. Moreover, the average efflux of CH4 emitted from snails’ habitats has reached 15.33 mg CH4-C m-2 d-1. By comparing with those emitted from vegetated coastal marsh and alpine wetland, this data indicates that snails’ habitats are strong sources of CH4 in a freshwater ecosystem. This study suggests identifying and modeling epifauna activity as a function of CH4 cycling could improve the mechanistic understanding of wetland biogeochemical cycling responses to climate change.

  10. Tropical Freshwater Biology - Vol 17, No 2 (2008)

    African Journals Online (AJOL)

    Description of a new freshwater species of Thaumatomastix (Protista, Thaumatomonadida) from Nigeria, West Africa · EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. DE Wujek, LE Pershon, MO Kadiri. http://dx.doi.org/10.4314/tfb.v17i2.45810 ...

  11. Annoted checklist of the freshwater fishes of Kenya (excluding the ...

    African Journals Online (AJOL)

    A checklist of the freshwater fishes of Kenya is presented. Pending more accurate information on their status, the lacustrine Lake Victoria haplochromines have been omitted from the list. Currently 206 species belonging to 38 families are known from Kenyan fresh waters. With at least 50 species, Cyprinidae are by far the ...

  12. 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...

  13. Helminth parasites of freshwater fish in Chiapas, Mexico.

    Science.gov (United States)

    Salgado-Maldonado, Guillermo; Caspeta-Mandujano, Juan Manuel; Moravec, František; Soto-Galera, Eduardo; Rodiles-Hernández, Rocío; Cabañas-Carranza, Guillermina; Montoya-Mendoza, Jesús

    2011-01-01

    An inventory based on previously published records and original data is presented for the helminth parasites reported in 54 fish species from 17 families from the state of Chiapas, southeast Mexico. This survey reports the presence of 43 helminth species in Chiapas for the first time. The actualized inventory of helminth parasites of freshwater fish from Chiapas contains 88 species from 67 genera and 40 helminth families. Trematodes and nematodes were the most abundant taxonomic groups. The helminth fauna in freshwater fishes from Chiapas consists of Central American species. All the helminth species recorded in Chiapas have also been collected from bodies of freshwater between the Isthmus of Tehuantepec and the Isthmus of Panama. This inventory shows that this fauna is quite similar to that from the neighboring basins of the lower Grijalva-Usumacinta system and the Yucatan Peninsula. The taxonomic composition and distribution data reported here for the helminth fauna of Chiapas' freshwater fish, contribute to a better understanding of this faunal component in Central America.

  14. Ecological risks of pesticides in freshwater ecosystems; Part 2: insecticides

    NARCIS (Netherlands)

    Brock, T.C.M.; Wijngaarden, van R.P.A.; Geest, van G.J.

    2000-01-01

    A literature review of freshwater model ecosystem studies with insecticides was performed to assess the NOEC 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

  15. Avoidance responses of some indigenous and exotic freshwater ...

    African Journals Online (AJOL)

    1990-04-17

    Apr 17, 1990 ... 48: 1050-1053. SAWYER, R.T. 1986. Leech biology, ecology and systematics. Oarendon Press, Oxford. TOWNSEND, C.R. & McCARTIlY. T.K. 1980. On the defence strategy of Physa/ontinalis. a freshwater pulmonate snail. Oecologia 46: 75--79. WREDE, W.L. 1927. Ueber einen Abwehrreflex bei Physa.

  16. Traditional exploitation of edible freshwater oyster Etheria elliptica ...

    African Journals Online (AJOL)

    Finally, oyster`s shell, a main substrate for larval settlement and bed restoration, were left on riverbanks after exploitation, reducing stocks reconstitution potential. Appropriate measures were suggested to Reserve staff for sustainable management. Keywords: Freshwater mollusk, harvesting activities, human pressure, ...

  17. Extensive culture of two mullet species in freshwater impoundments ...

    African Journals Online (AJOL)

    Cape Department of Nature and Environmental Conservation, Grahamstown. The feasibility of using freshwater ... (Bar-Ilan 1975). Mullet catches today form an important com- ponent of the extensive fisheries in these waters. Such exten- sive mullet culture could have special significance for South. Africa where intensive ...

  18. Review: Sublethal effects of temperature on freshwater organisms ...

    African Journals Online (AJOL)

    Review: Sublethal effects of temperature on freshwater organisms, with special reference to aquatic insects. HF Dallas, V Ross-Gillespie. Abstract. Water temperature is a key variable affecting aquatic organisms. Understanding their response to elevated water temperatures is important for estimating upper thermal limits, ...

  19. Fossil freshwater sponges: Taxonomy, geographic distribution, and critical review

    OpenAIRE

    Roberto Pronzato; Andrzej Pisera; Renata Manconi

    2017-01-01

    Sponges are one of the most ancient animal phyla with about 8850 living species and about 5000 described fossil taxa. Most sponges are marine and live at all depths of all oceans. Freshwater bodies (lakes, rivers) are inhabited only by a small minority of species, ca. 240 (

  20. Freshwater Decapod Crustaceans from Pulau Tioman, West Malaysia

    NARCIS (Netherlands)

    Ng, P.K.L.

    1985-01-01

    Two new freshwater crabs, Stoliczia (Johora) punicea spec. nov. and S. (J.) tiomanensis counsilmani subspec. nov., are described from streams in Pulau Tioman, West Malaysia. Taxonomic notes are added of S (J.) tiomanensis tiomanensis Ng & Tan, 1984. New records of the carideans Macrobrachium

  1. Toxicity of rotenone to giant river freshwater prawn Macrobrachium rosenbergii

    Science.gov (United States)

    Aquaculturists have often suffered predation losses in the production of freshwater giant river prawn Macrobrachium rosenbergii due to the presence of wild fish species in culture ponds. The piscicide rotenone is widely used to remove undesirable fish species from ponds. Although evidence in the t...

  2. Page 1 Tropical Freshwater Biology, 7 (1998) 17 - 26 17 ...

    African Journals Online (AJOL)

    A molt-staging scheme was developed for live. Macrobrachium rosenbergii, an economically important species of freshwater prawns, based upon external changes in the exoskeleton and internal setal development within the pleopods and in antennal scale. The premolt, intermolt and post-molt stages were subdivided into ...

  3. 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 ...

  4. Escherichia coli and fecal coliforms in freshwater and estuarine sediments

    Science.gov (United States)

    It has been known for some time that substantial populations of fecal coliforms and E. coli are harbored in freshwater bottom sediments, bank soils, and beach sands. However, the relative importance of sediments as bacterial habitats and as a source of water-borne fecal coliforms and E. coli has not...

  5. Survival and growth of Clarias gariepinus larvae fed with freshwater ...

    African Journals Online (AJOL)

    Survival and growth performance of Clarias gariepinus larvae fed with freshwater zooplankton was compared to those fed with Artémia salina. Clarias gariepinus larvae at the end of yolk sac resorption with 2.8 ± 0.1 mg initial weight were fed ad libitum to live zooplankton for 08 days in concrete basins (without water ...

  6. Oxygen consumption and responses of the freshwater snail Bulinus ...

    African Journals Online (AJOL)

    A gradient or choice apparatus, based on the 'fluvarium' principle and suitable for testing the responses of the freshwater snail Bulinus (Physopsis) globosus to different partial oxygen tensions was used. In a gradual oxygen gradient established with this apparatus, B. (P.) globosus shows a significant preference for ...

  7. Patterns of distribution and conservation status of freshwater fishes ...

    African Journals Online (AJOL)

    1995-02-15

    Feb 15, 1995 ... tion concern for freshwater fishes is emphasized, and highlights the importance of well-preserved voucher spec- imens for biodiversity ...... comm.), where the fish community is an important part of the floodplain ecology. Conclusions - the value of museum collections for conservation. Drinkrow, Cherry ...

  8. researcii note haematological studies on some freshwater teleosts

    African Journals Online (AJOL)

    The diagnostic value of hameatological indices for fish blood has been discused by lleser (1960) and. Blaxhall and Daisley (1973). Their results signify the importance of such basic information when investigating the ecophysiology of the various freshwater lsh species in South Africa where fish farms are being established ...

  9. Effects of severe drought on freshwater mussel assemblages

    Science.gov (United States)

    Wendell Hagg; Jr. Warren Melvin L.

    2008-01-01

    We examined changes in freshwater mussel abundance and species composition at eight sites in Alabama and Mississippi in response to a severe drought in 2000. Five small-stream sites in Bankhead National Forest were heavily impacted by drought; one site dried almost completely, and four sites experienced total or near cessation of flow but retained water in their...

  10. Laboratory mass culture of the freshwater oligochaete Dero digitata

    Science.gov (United States)

    Proliferative gill disease (PGD) in channel catfish Ictalurus punctatus is caused by the myxozoan parasite Henneguya ictaluri, which uses the freshwater oligochaete Dero digitata as an alternate host. Controlled studies on the transmission of PGD require sustainable D. digitata mass cultures. We d...

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

    African Journals Online (AJOL)

    2012-03-01

    Mar 1, 2012 ... Since the 1970s, at approximately 10-year intervals, 4 national-scale freshwater conservation plans have been developed for South Africa. These 4 plans reflect different but broadly advancing approaches to conservation planning. We provide an overview of 3 historical plans and a more detailed ...

  12. Marine and freshwater sponges (Porifera) of the Netherlands

    NARCIS (Netherlands)

    Soest, van R.W.M.

    1977-01-01

    The collections of the Rijksmuseum van Natuurlijke Historie at Leiden and the Zoologisch Museum of Amsterdam contain 19 species of Porifera (15 marine and 4 freshwater species) originating from the Netherlands. Among the marine species, Halichondria panicea (Pallas, 1766), Halichondria bowerbanki

  13. 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 ...

  14. 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

  15. Arctic Ocean freshwater: How robust are model simulations?

    NARCIS (Netherlands)

    Jahn, A.; Aksenov, Y.; de Cuevas, B.A.; de Steur, L.; Häkkinen, S.; Hansen, E.; Herbaut, C.; Houssais, M.N.; Karcher, M.; Kauker, F.; Lique, C.; Nguyen, A.; Pemberton, P.; Worthen, D.; Zhang, J.

    2012-01-01

    The Arctic freshwater (FW) has been the focus of many modeling studies, due to the potential impact of Arctic FW on the deep water formation in the North Atlantic. A comparison of the hindcasts from ten ocean-sea ice models shows that the simulation of the Arctic FW budget is quite different in the

  16. 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

  17. Effect of cypermethrin toxicity on enzyme activities in the freshwater ...

    African Journals Online (AJOL)

    Cyprinus carpio a freshwater fish, was exposed to lethal concentration (7.5 μg/L) for one, three, five, seven and nine days and, sublethal concentration (1.5 μg/L) for 1, 7, 14, 21 and 28 days of cypermethrin, respectively to observe the enzyme activity in functionally three different tissues; that is, muscle, gill and liver.

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

    African Journals Online (AJOL)

    In addition to confirming the persistence of O. mossambicus and G. affinis in the system, the current study also reports the presence of a new invader, Cyprinus carpio (common carp). M. salmoides were absent from 2009 and 2010 samples. Key words: freshwater fish, invasive alien fishes, estuary, RAMSAR site, diversity.

  19. Histopathological alterations in spleen of freshwater fish Cyprinus ...

    African Journals Online (AJOL)

    Aquatic ecosystems in areas with intense mining activity are often subject to cyanide contamination; the present study was aimed to evaluate the harmful effects of sodium cyanide on histoarchitechtural aspect of spleen of freshwater fish Cyprinus carpio using an in vivo approach. The fishes were exposed to a sublethal ...

  20. Nature of freshwater influx in Indian estuaries -5mm

    Indian Academy of Sciences (India)

    D Shankar 4mmCollaborator: Suprit Kumar

    2010-11-12

    Nov 12, 2010 ... Modelling discharge. Nature of freshwater influx in Indian estuaries. D Shankar. Collaborator: Suprit Kumar. National Institute of Oceanography,. Dona Paula, Goa 403004 shankar@nio.org http://www.nio.org. Symposium on Indian estuaries. Seventy-sixth annual meeting of the. Indian Academy of Sciences ...

  1. Growth and longevity in freshwater mussels: evolutionary and conservation implications

    Science.gov (United States)

    Wendell R. Haag; Andrew L.. Rypel

    2010-01-01

    The amount of energy allocated to growth versus other functions is a fundamental feature of an organism’s life history. Constraints on energy availability result in characteristic trade-offs among life-history traits and reflect strategies by which organisms adapt to their environments. Freshwater mussels are a diverse and imperiled component of aquatic ecosystems but...

  2. Estimating the recreational value of freshwater inflows into the Klein ...

    African Journals Online (AJOL)

    2009-12-14

    Dec 14, 2009 ... This study estimates the change in aggregate consumer surplus associated with increased freshwater supply into two South. African estuaries ... One way of doing this is by estimating the recreational value of estuarine goods ..... is a problem in the case of the zonal method as it may be oner- ous to locate ...

  3. Transitioning to Zero Freshwater Withdrawal for Thermoelectric Generation

    Science.gov (United States)

    Macknick, J.; Tidwell, V. C.; Zemlick, K. M.; Sanchez, J.; Woldeyesus, T.

    2013-12-01

    The electricity sector is the largest withdrawer of freshwater in the United States. The primary demand for water from the electricity sector is for cooling thermoelectric power plants. Droughts and potential changes in water resources resulting from climate change pose important risks to thermoelectric power production in the United States. Power plants can minimize risk in a variety of ways. One method of reducing risk is to move away from dependency on freshwater resources. Here a scoping level analysis is performed to identify the technical tradeoffs and initial cost estimates for retrofitting all existing steam-powered generation to achieve zero freshwater withdrawal. Specifically, the conversion of existing freshwater-cooled plants to dry cooling or a wet cooling system utilizing non-potable water is considered. The least cost alternative is determined for each of the 1,178 freshwater using power plants in the United States. The use of non-potable water resources, such as municipal wastewater and shallow brackish groundwater, is considered based on the availability and proximity of those resources to the power plant, as well as the costs to transport and treat those resources to an acceptable level. The projected increase in levelized cost of electricity due to power plant retrofits ranges roughly from 0.20 to 20/MWh with a median value of 3.53/MWh. With a wholesale price of electricity running about 35/MWh, many retrofits could be accomplished at levels that would add less than 10% to current power plant generation expenses. Such retrofits could alleviate power plant vulnerabilities to thermal discharge limits in times of drought (particularly in the East) and would save 3.2 Mm3/d of freshwater consumption in watersheds with limited water availability (principally in the West). The estimated impact of retrofits on wastewater and brackish water supply is minimal requiring only a fraction of the available resource. Total parasitic energy requirements to

  4. 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

  5. Early warning of freshwater salinization due to upward brine displacement by species transport simulations combined with a hydrochemical genesis model

    Science.gov (United States)

    Langer, Maria; Kühn, Michael

    2016-04-01

    fault or an erosional channel which both allows an exchange between the shallow freshwater and the deeper saline water complex. The salinization potential of a drinking water well in vicinity to the brine source was determined for different scenarios. [1] Tillner E., Kempka T., Nakaten B., Kühn M. (2013) Brine migration through fault zones: 3D numerical simulations for a prospective CO2 storage site in Northeast Germany. International Journal of Greenhouse Gas Control 19, 689-703. doi: 10.1016/ j.ijggc.2013.03.012 [2] Langer M., Tillner E., Kempka T., Kühn M. (2015) Effective damage zone volume of fault zones and initial salinity distribution determine intensity of shallow aquifer salinization in geological underground utilization. Hydrology and Earth System Sciences Discussion, 12, 5703-5748. doi: 10.5194/hessd-12-5703-2015 [3] Hotzan, G., and Voss, T. (2013): Complex hydrogeochemic-genetic mapping for evaluation of the endangerment of pleistocene and tertiary aquifers by saline waters in the region Storkow-Frankfurt (Oder)-Eisenhüttenstadt. Brandenburgische Geowissenschaftliche Beiträge, 20 (1/2), 62-82. (in German) [4] Clauser C. (2003) SHEMAT and Processing SHEMAT - Numerical simulation of reactive flow in hot aquifers, Springer Publishers, Heidelberg [5] Rechlin, B., Hoffknecht, A., Scholz, H., Helms, A. (2010): Genetic evaluation of analyses from the hydrosphere. Software GEBAH Vers. 1.1 LBGR/GCI, Cottbus, Königs Wusterhausen (in German) [6] Rechlin, B. (2008): A method for a concentration free early detection of saltwater intrusions into freshwater aquifers and surface water. Brandenburgische Geowissenschaftliche Beiträge, 15 (1/2), 57-68. (in German)

  6. Development of a feeding behavioural bioassay using the freshwater amphipod Gammarus pulex and the Multispecies Freshwater Biomonitor.

    NARCIS (Netherlands)

    Alonso, A.; Lange, de H.J.; Peeters, E.T.H.M.

    2009-01-01

    The present study reports the development of a feeding behavioural bioassay using the Multispecies Freshwater Biomonitor (MFB). This device is based on the quadruple impedance conversion technique to record online different behaviours of animals. Animal movements in the water generate specific

  7. Digital Geologic Map of Congaree National Park and Vicinity, South Carolina (NPS, GRD, GRI, CONG, CONG digital map)

    Data.gov (United States)

    National Park Service, Department of the Interior — The Digital Geologic Map of Congaree National Park and Vicinity, South Carolina is composed of GIS data layers complete with ArcMap 9.3 layer (.LYR) files, two...

  8. Digital Geologic Map of Bryce Canyon National Park and Vicinity, Utah (NPS, GRD, GRI, BRCA, BRCA digital map)

    Data.gov (United States)

    National Park Service, Department of the Interior — The Digital Geologic Map of Bryce Canyon National Park and Vicinity, Utah is composed of GIS data layers complete with ArcMap 9.3 layer (.LYR) files, two ancillary...

  9. Digital Geologic Map of San Juan Island National Historical Park and vicinity, Washington (NPS, GRD, GRE, SAJH, SAJH digital map)

    Data.gov (United States)

    National Park Service, Department of the Interior — The Digital Geologic Map of San Juan Island National Historical Park and vicinity, Washington is composed of GIS data layers complete with ArcMap 9.2 layer (.LYR)...

  10. Digital Geologic Map of the American Camp Unit and vicinity, Washington (NPS, GRD, GRE, SAJH, SJIS digital map)

    Data.gov (United States)

    National Park Service, Department of the Interior — The Digital Geologic Map of the American Camp Unit and vicinity, Washington is composed of GIS data layers complete with ArcMap 9.2 layer (.LYR) files, two ancillary...

  11. Digital Geologic Map of Palo Alto Battlefield National Historic Site and vicinity, Texas (NPS, GRD, GRE, PAAL, PAAL digital map)

    Data.gov (United States)

    National Park Service, Department of the Interior — The Digital Geologic Map of Palo Alto Battlefield National Historic Site and vicinity, Texas is composed of GIS data layers complete with ArcMap 9.2 layer (.LYR)...

  12. 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

  13. Concentration of NOX in the vicinity of the power plants Vojany EVO 1 and EVO 2

    Directory of Open Access Journals (Sweden)

    Ján Brehuv

    2006-12-01

    Full Text Available The paper presents a calculation of the maximal concentration of nitrogen oxides in the vicinity of point sources (main chimneys of power plants Vojany EVO1 and EVO2. The wind velocity u10,M (7, at which the concentration on a given place in the surrounding of the pollution source attains a maximal value, is calculated. The relation (8 for a calculation of the place with the maximal concentration for a given class of air stability (Table 1 and 2 and for a given wind velocity is derived. According to equation (3 and Table 3, a thermal capacity of EVO1 and EVO2 is calculated, considering a flat country in the vicinity of the sources (x3 = 0 in relation (1. Subsequently, it is also considered that the wind direction has the direction joining the source and the place of concentration calculation (x2 = 0. The calculations of concentration are performed for the 5th class of air stability. As to this class, favourable conditions for the pollutants dispersion are there. Thus, the maximum concentration is in a relatively small distance from the source with a sharp concentration maximum. As to other classes of the air stability (Table 1 and 2, the maximum concentration is located in larger distances from the source, i.e. about 10 km, as it is considered in Table 4 and 5. The theoretical calculation of NOX concentration in the vicinity of the sources, EVO1 and EVO2, shows (Table 4 and 5 that it does not exceed the allowable limit of 150 µg.m-3.

  14. Atmospheric BTEX concentrations in the vicinity of the crude oil refinery of the Baltic region.

    Science.gov (United States)

    Baltrėnas, Pranas; Baltrėnaitė, Edita; Serevičienė, Vaida; Pereira, Paulo

    2011-11-01

    Among chemical industries, petroleum refineries have been identified as large emitters of a wide variety of pollutants. Benzene, toluene, ethylbenzene, and xylene (BTEX) form an important group of aromatic volatile organic compounds (VOCs) because of their role in the troposphere chemistry and the risk posed to human health. A very large crude oil refinery of the Baltic States (200,000 bbl/day) is situated in the northern, rural part of Lithuania, 10 km from the town of Mažeikiai (Lithuania). The objectives of this study were: (1) to determine of atmospheric levels of BTEX in the region rural and urban parts at the vicinity of the crude oil refinery; and (2) to investigate the effect of meteorological parameters (wind speed, wind direction, temperature, pressure, humidity) on the concentrations measured. The averaged concentration of benzene varied from 2.12 ppbv in the rural areas to 2.75 ppbv in the urban areas where the traffic was determined to be a dominant source of BTEX emissions. Our study showed that concentration of benzene, as strictly regulated air pollutant by EU Directive 2008/50/EC, did not exceed the limit of 5 ppbv in the region in the vicinity of the crude oil refinery during the investigated period. No significant change in air quality in the vicinity of the oil refinery was discovered, however, an impact of the industry on the background air quality was detected. The T/B ratio (0.50-0.81) that was much lower than 2.0, identified other sources of pollution than traffic.

  15. Monitoring the ordering in biomolecular films on vicinal silicon surfaces by reflectance difference/anisotropy spectroscopy

    Science.gov (United States)

    Silaghi, Simona D.; Zahn, Dietrich R. T.

    2006-05-01

    DNA base molecules, adenine, thymine, guanine, and cytosine may be employed as charge transport molecules in biomolecular electronic devices. Their electronic properties are comparable with those of inorganic wide bandgap materials, e.g. GaN with the absorption onset in the near ultra-violet (UV) range. A recent field effect transistor study based on a modified DNA base revealed that the prototype bio-transistor gives rise to a better voltage gain compared to one based on carbon nanotubes (CNTs) [G. Mauricio, P. Visconti, V. Arima, S. D'Amico, A. Biasco, E. D'Amone, R. Cingolani, R. Rinaldi, Nanoletters 3 (2003) 479]. Here, in situ reflectance difference/anisotropy spectroscopy (RDS/RAS) is employed under ultra-high vacuum (UHV) conditions for monitoring the growth of DNA base molecules on vicinal hydrogen passivated Si(1 1 1) surfaces. Such vicinal substrates consisting of steps and terraces may serves as suitable templates for molecular ordering. Indeed, RDS/RAS measurements reveal information about molecular ordering of DNA bases induced by the density of steps on silicon surfaces. All four molecules, however, behave differently on the vicinal substrates. The first transition dipole moments corresponding to adenine and thymine molecules align mainly perpendicular to the step edge direction while for guanine and cytosine they align parallel to this direction, however, only in very thin layers. The RDS/RAS signal of the guanine and cytosine layers with thicknesses above 20 nm saturates due to a loss of ordering at higher coverages. Additionally, time-resolved RDS/RAS measurements at the silicon E 2 (4.25 eV) critical point (CP) demonstrate the sensitivity to the biomolecular/inorganic interface formation.

  16. Contribution to the knowledge of jumping spiders (Araneae: Salticidae from vicinity of Jagodina, Central Serbia

    Directory of Open Access Journals (Sweden)

    Stanković, B.

    2012-09-01

    Full Text Available During last 10 years, based on personal collectings, 21 species from 14 genera of Salticidae (Araneae are recorded from vicinity of Jagodina: Ballus chalybeius, Carrhotus xanthogramma, Evarcha arcuata, Evarcha falcata, Heliophanus auratus, Heliophanus cupreus, Heliophanus flavipes, Heliophanus kochii, Icius hamatus, Icius subinermis, Leptorchestes berolinensis, Macaroeris nidicolens, Marpissa muscosa, Marpissa nivoyi, Mendoza canestrinii, Pellenes tripunctatus, Phintella castriesiana, Phlegra fasciata, Pseudeuophrys erratica, Pseudeuophrys lanigera, Salticus scenicus. All those species are provided with habitat notes and global distribution. New records for the spider fauna of Serbia are Heliophanus kochii (Simon 1868, Icius subinermis (Simon, 1937, Marpissa nivoyi (Lucas, 1846 and Mendoza canestrinii (Ninni, 1868.

  17. Anisotropic Spin-Orbit Coupling and Magnetocrystalline Anisotropy in Vicinal Co Films

    Energy Technology Data Exchange (ETDEWEB)

    Dhesi, Sarnjeet S.; van der Laan, Gerrit; Dudzik, Esther; Shick, Alexander B.

    2001-08-06

    The anisotropy of the spin-orbit interaction, <<{lambda}{sub a}> , in vicinal Co films has been measured using x-ray magnetic linear dichroism (XMLD). A linear increase in <{lambda}{sub a}> with Co step density is found using a new sum rule and represents the first experimental confirmation that XMLD probes the magnetocrystalline anisotropy energy (MAE). X-ray magnetic circular dichroism is used to confirm that the XMLD arises from changes in the local step-edge electronic structure. The XMLD sum rule gives a larger MAE compared to macroscopic values and is discussed with respect to other local probes of the MAE.

  18. Investigation of the conductivity distribution in the vicinity of a cascade volcano

    Energy Technology Data Exchange (ETDEWEB)

    Mozley, E.C.

    1982-11-01

    Magnetotelluric and telluric data were acquired in the vicinity of Mount Hood Oregon as part of a multidisciplinary exploration program to evaluate the geothermal potential of this stratocone volcano. Eleven field components were acquired simultaneously over the frequency band of 50. to .001 hertz. These data consisted of one five component magnetotelluric base site, two sets of two component remote electric field measurements and one set of remote horizontal magnetic field measurements. The data were recorded digitally in the field and processed later using the remote electric and magnetic signals to obtain unbiased tensor impedance and geomagnetic transfer function (tipper) estimates.

  19. Current-phase relations in SIsFS junctions in the vicinity of 0-π transition

    Science.gov (United States)

    Bakurskiy, S. V.; Filippov, V. I.; Ruzhickiy, V. I.; Klenov, N. V.; Soloviev, I. I.; Kupriyanov, M. Yu.; Golubov, A. A.

    2017-03-01

    We consider the current-phase relation (CPR) in Josephson junctions with complex insulator-superconductor-ferromagnetic interlayers in the vicinity of the 0-π transition. We find a strong impact of the second harmonic on the CPR of the junctions. It is shown that the critical current can be kept constant in the region of 0-π transition, while the CPR transforms through multivalued hysteretic states depending on the relative values of tunnel transparency and magnetic thickness. Moreover, the CPR in the transition region has multiple branches with distinct ground states.

  20. Wave-induced nearshore flow patterns in the vicinity of Cochin harbour, India

    Digital Repository Service at National Institute of Oceanography (India)

    PrasannaKumar, S.; Vethamony, P.; Murty, C.S.

    , C. S. Murty Refraction function Wave length Wave period Wave orbital velocity 1 INTRODUCTION The dynamics of sediment movement in the littoral zone is governed primarily by wave-induced currents. Specific knowledge of these currents...) _\\] (2) The wave orbital velocities (Umax) at the lower boundary of the fluid Nearshore flow patterns in the vicinity of Cochin Harbour 115 75 ° &5' 7,6" 76~ 15' -- 10 ° i 15' 300 ec N I -10° :hin leltana ~ntnak~ ;Ranaz 30 Fig. 2. A typical...

  1. Electromagnetic fields in the vicinity of DECT cordless telephones and mobile phones

    Directory of Open Access Journals (Sweden)

    Paweł Mamrot

    2015-12-01

    Full Text Available Background: Mobile telephones belong to the most frequently used personal devices. In their surroundings they produce the electromagnetic field (EMF, in which exposure range there are not only users but also nearby bystanders. The aim of the investigations and EMF measurements in the vicinity of phones was to identify the electric field levels with regard to various working modes. Material and methods: Twelve sets of DECT (digital enhanced cordless telecommunications cordless phones (12 base units and 15 handsets, 21 mobile telephones produced by different manufactures, and 16 smartphones in various applications, (including multimedia in the conditions of daily use in living rooms were measured. Measurements were taken using the point method in predetermined distances of 0.05–1 m from the devices without the presence of users. Results: In the vicinity of DECT cordless phone handsets, electric field strength ranged from 0.26 to 2.30 V/m in the distance of 0.05 m – 0.18–0.26 V/m (1 m. In surroundings of DECT cordless telephones base units the values of EMF were from 1.78–5.44 V/m (0.05 m to 0.19– 0.41 V/m (1 m. In the vicinity of mobile phones working in GSM mode with voice transmission, the electric field strength ranged from 2.34–9.14 V/m (0.05 m to 0.18–0.47 V/m (1 m while in the vicinity of mobile phones working in WCDMA (Wideband Code Division Multiple Access mode the electric field strength ranged from 0.22–1.83 V/m (0.05 m to 0.18–0.20 V/m (1 m. Conclusions: The mean values of the electric field strength for each group of devices, mobile phones and DECT wireless phones sets do not exceed the reference value of 7 V/m, adopted as the limit for general public exposure. Med Pr 2015;66(6:803–814

  2. Relativistic theory for picosecond time transfer in the vicinity of Earth

    Science.gov (United States)

    Petit, G.; Wolf, P.

    1994-01-01

    The problem of light propagation is treated in a geocentric reference system with the goal of ensuring picosecond accuracy for time transfer techniques using electromagnetic signals in the vicinity of the Earth. We give an explicit formula for a one way time transfer, to be applied when the spatial coordinates of the time transfer stations are known in a geocentric reference system rotating with the Earth. This expression is extended, at the same accuracy level of one picosecond, to the special cases of two way and LASSO time transfers via geostationary satellites.

  3. Shell model calculation for Te and Sn isotopes in the vicinity of {sup 100}Sn

    Energy Technology Data Exchange (ETDEWEB)

    Yakhelef, A.; Bouldjedri, A. [Physics Department, Farhat abbas University, Setif (Algeria); Physics Department, Hadj Lakhdar University, Batna (Algeria)

    2012-06-27

    New Shell Model calculations for even-even isotopes {sup 104-108}Sn and {sup 106,108}Te, in the vicinity of {sup 100}Sn have been performed. The calculations have been carried out using the windows version of NuShell-MSU. The two body matrix elements TBMEs of the effective interaction between valence nucleons are obtained from the renormalized two body effective interaction based on G-matrix derived from the CD-bonn nucleon-nucleon potential. The single particle energies of the proton and neutron valence spaces orbitals are defined from the available spectra of lightest odd isotopes of Sb and Sn respectively.

  4. A review of the Acanthocephala parasitising freshwater fishes in Australia.

    Science.gov (United States)

    Smales, L R; Adlard, R D; Elliot, A; Kelly, E; Lymbery, A J; Miller, T L; Shamsi, S

    2017-09-25

    The acanthocephalan fauna of Australian freshwater fishes was documented from field surveys, a literature survey and examination of specimens registered in Australian museums. From the 4030 fishes, representing 78 of the 354 Australian freshwater fish species (22%), examined for infection seven species of acanthocephalan were recovered. These species comprised five endemic species, three in endemic genera, two species in cosmopolitan genera, one species not fully identified and 1 putative exotic species recovered from eight species of fish. Of these Edmonsacanthus blairi from Melanotaenia splendida, was the only acanthocephalan found at a relatively high prevalence of 38·6%. These findings are indicative of a highly endemic and possibly depauperate acanthocephalan fauna. Species richness was higher in the tropical regions than the temperate regions of the country. Exotic acanthocephalan species have either not been introduced with their exotic hosts or have been unable to establish their life cycles in Australian conditions. Consequently, acanthocephalans have not yet invaded endemic Australian fish hosts.

  5. 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.

  6. 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.

  7. 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...... area, and traced the ammonium processing and retention in four subsequent tide cycles. In this paper we present the results for the water-phase components of the marsh system and compare them to a similar experiment conducted in spring/early summer (May). Changes in concentration and isotopic......, but the absolute ammonium transformation rate was 3 times higher in May. While the marsh surface area was crucial for nitrification in May this was less pronounced in September. Denitrification, on the other hand, appeared more important in September compared to May....

  8. Occupational health issues in marine and freshwater research.

    Science.gov (United States)

    Courtenay, Glenn; Smith, Derek R; Gladstone, William

    2012-03-19

    Marine and freshwater scientists are potentially exposed to a wide variety of occupational hazards. Depending on the focus of their research, risks may include animal attacks, physiological stresses, exposure to toxins and carcinogens, and dangerous environmental conditions. Many of these hazards have been investigated amongst the general population in their recreational use of the environment; however, very few studies have specifically related potential hazards to occupational exposure. For example, while the incidence of shark and crocodile attacks may invoke strong emotions and the occupational risk of working with these animals is certainly real, many more people are stung by jellyfish or bitten by snakes or dogs each year. Furthermore, a large proportion of SCUBA-related injuries and deaths are incurred by novice or uncertified divers, rather than professional divers using aquatic environments. Nonetheless, marine and freshwater research remains a potentially risky occupation, and the likelihood of death, injury and long-term health impacts still needs to be seriously considered.

  9. 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).

  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. Facing the Freshwater Crisis; Globaler Wassermangel... muss nicht sein

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Peter

    2009-06-15

    As demand for freshwater soars, planetary supplies are becoming unpredictable. Existing technologies could avert a global water crisis, but they must be implemented soon Global freshwater resources are threatened by rising demands from many quarters. Growing populations need ever more water for drinking, hygiene, sanitation, food production and industry. Climate change, meanwhile, is expected to contribute to droughts. Policymakers need to figure out how to supply water without degrading the natural ecosystems that provide it. Existing low-tech approaches can help prevent scarcity, as can ways to boost supplies, such as improved methods to desalinate water. But governments at all levels need to start setting policies and making investments in infrastructure for water conservation now. (orig./GL) [German] Suesswasser wird immer knapper, denn der weltweite Bedarf waechst rapide. Die Technologien, mit denen man den Notstand abwenden kann, stehen zur Verfuegung. Nur muessten die Verantwortlichen sie jetzt einsetzen. (orig.)

  12. Occupational health issues in marine and freshwater research

    Science.gov (United States)

    2012-01-01

    Marine and freshwater scientists are potentially exposed to a wide variety of occupational hazards. Depending on the focus of their research, risks may include animal attacks, physiological stresses, exposure to toxins and carcinogens, and dangerous environmental conditions. Many of these hazards have been investigated amongst the general population in their recreational use of the environment; however, very few studies have specifically related potential hazards to occupational exposure. For example, while the incidence of shark and crocodile attacks may invoke strong emotions and the occupational risk of working with these animals is certainly real, many more people are stung by jellyfish or bitten by snakes or dogs each year. Furthermore, a large proportion of SCUBA-related injuries and deaths are incurred by novice or uncertified divers, rather than professional divers using aquatic environments. Nonetheless, marine and freshwater research remains a potentially risky occupation, and the likelihood of death, injury and long-term health impacts still needs to be seriously considered. PMID:22429712

  13. The relation between international trade and freshwater scarcity

    OpenAIRE

    Hoekstra, Arjen

    2010-01-01

    It is becoming increasingly important to put freshwater issues in a global context. Local water depletion and pollution are often closely tied to the structure of the global economy. With increasing trade between nations and continents, water is more frequently used to produce exported goods. International trade in commodities implies long-distance transfers of water in virtual form, where virtual water is understood as the volume of water that has been used to produce a commodity and that is...

  14. The effects of the herbicide atrazine on freshwater snails.

    Science.gov (United States)

    Gustafson, Kyle D; Belden, Jason B; Bolek, Matthew G

    2015-07-01

    Atrazine has been shown to affect freshwater snails from the subcellular to community level. However, most studies have used different snail species, methods, endpoints, and atrazine exposure concentrations, resulting in some conflicting results and limiting our understanding. The goal of this study was to address these concerns by (1) investigating the acute and chronic effects of atrazine on four species of freshwater snails (Biomphalaria glabrata, Helisoma trivolvis, Physa acuta, and Stagnicola elodes) using the same methods, endpoints, and concentrations, and (2) summarizing the current literature pertaining to the effects of atrazine on freshwater snails. We conducted a 48 h acute toxicity test with an atrazine concentration higher than what typically occurs in aquatic environments (1000 µg/L). Additionally, we exposed snails to environmentally relevant atrazine concentrations (0, 0.3, 3, and 30 µg/L) for 28 days and assessed snail survival, growth, and reproduction. We also summarized all known literature pertaining to atrazine effects on freshwater snails. The literature summary suggests snails are often affected by environmentally relevant atrazine concentrations at the subcellular and cellular levels. These effects are typically not transitive to effects on survival, growth, or reproduction at the same concentrations. Our acute exposures corroborate the general trend of no direct effect on snail populations as atrazine did not directly affect the survival of any of the four snail species. Similarly, environmentally relevant concentrations did not significantly affect the survival, growth, or reproduction of any snail species. These results indicate that, in the absence of other possible stressors, the direct effects of environmentally relevant atrazine concentrations may not be realized at the snail population level.

  15. Early Student Support for Process Studies of Surface Freshwater Dispersal

    Science.gov (United States)

    2016-06-24

    region to the north, and intrusions of saline w::tter are seen subsurface in the southern part of the section. (c) Black : Amount of heat contained ... Hole Oceanographic Institution REPORT NUMBER Department of Physical Oceanography - MS #29 FINAL Woods Hole , MA 02543 9. SPONSORING/MONITORING AGENCY...ONRREPORT Early Student Support Process Studies of Surface Freshwater Dispersal June 24, 2016 Amala Mahadevan Woods Hole Oceanographic Institution

  16. Harmful Freshwater Algal Blooms, With an Emphasis on Cyanobacteria

    OpenAIRE

    Paerl, Hans W.; Rolland S. Fulton; Moisander, Pia H.; Julianne Dyble

    2001-01-01

    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. Bl...

  17. Identifying and prioritising services in European terrestrial and freshwater ecosystems

    OpenAIRE

    Harrison, P. A.; Vandewalle, M; Sykes, M.T.; Berry, P. M. (Peter M.); Bugter, R.J.F.; Bello,; Feld, C.K.; Grandin, U.; Harrington, R.; Haslett, J.R.; Jongman, R. H. G.; Luck, G.W.; Martins da Silva, P.; Moora, M.; Settele, J.

    2010-01-01

    Ecosystems are multifunctional and provide humanity with a broad array of vital services. Effective management of services requires an improved evidence base, identifying the role of ecosystems in delivering multiple services, which can assist policy-makers in maintaining them. Here, information from the literature and scientific experts was used to systematically document the importance of services and identify trends in their use and status over time for the main terrestrial and freshwater ...

  18. Utilization of protein by fingerlings of a threatened freshwater catfish ...

    African Journals Online (AJOL)

    A feeding trial was made to evaluate the utilization of protein as a dietary energy source by the fingerlings of the threatened freshwater catfish Mystus montanus. Six different diets were formulated from semi-purified ingredients with six different levels of proteins (6.97, 24.77, 30.70, 36.64, 42.57 and 46.72%) and were fed to ...

  19. 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

  20. Serum antileptospiral agglutinins in freshwater turtles from Southern Brazil

    Science.gov (United States)

    Silva, Éverton F; Seyffert, Núbia; Cerqueira, Gustavo M.; Leihs, Karl P.; Athanazio, Daniel A.; Valente, Ana L. S.; Dellagostin, Odir A.; Brod, Claudiomar S.

    2009-01-01

    In this study, we observed the presence of antileptospiral agglutinins in freshwater turtles of two urban lakes of Pelotas, Southern Brazil. Forty animals (29 Trachemys dorbigny and 11 Phrynops hilarii) were captured and studied. Attempts to isolate leptospires from blood and urine samples were unsuccessful. Serum samples (titer > 100) reactive to pathogenic strains were observed in 11 animals. These data encourage surveys of pet turtles to evaluate the risk of transmission of pathogenic leptospires to humans. PMID:24031348

  1. Calcium uptake in the skin of a freshwater teleost.

    OpenAIRE

    McCormick, S D; Hasegawa, S; Hirano, T

    1992-01-01

    The skin, particularly the opercular membrane of some teleosts, contains mitochondrion-rich "chloride" cells and has been widely used as a model to study branchial salt-extrusion mechanisms in seawater fish. Skin isolated from the operculum of the freshwater Nile tilapia (Oreochromis niloticus) can transport Ca2+ against an ionic and electrical gradient. Adaptation of Nile tilapia to a low-Ca2+ environment increased the capacity of the opercular membrane to transport Ca2+. The density of mito...

  2. Risk Levels of Toxic Cyanobacteria in Portuguese Recreational Freshwaters

    OpenAIRE

    Menezes, Carina; Churro, Catarina; Dias, Elsa

    2017-01-01

    Portuguese freshwater reservoirs are important socio-economic resources, namely for recreational use. National legislation concerning bathing waters does not include mandatory levels or guidelines for cyanobacteria and cyanotoxins. This is an issue of concern since cyanotoxin-based evidence is insufficient to change the law, and the collection of scientific evidence has been hampered by the lack of regulatory levels for cyanotoxins in bathing waters. In this work, we evaluate the profile of c...

  3. Quantifying habitat interactions: sediment transport and freshwater mussels

    Science.gov (United States)

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

    2016-12-01

    Freshwater mussel abundance and distribution are integrally linked with their habitat through sediment transport processes in moving waters, including suspended sediment loads and bed mobility. This research seeks to quantify these complex interactions using a combination of field data collection in the intensively agricultural Minnesota River Basin, and laboratory experiments in the Outdoor StreamLab (OSL) and flumes at St. Anthony Falls Laboratory (SAFL) 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). Experiments in the OSL focused on the interactions between moving bedload and freshwater mussel behavior. Flooding experiments were used to quantify the movement during and post flood for three mussel species with different shell sculptures: threeridge (Amblema plicata), plain pockebook (Lampsilus cardium), and white heelsplitter (Lasmigona complanata). Flow fields, bed shear stress, bedform migration, and bar topography were measured during each flooding event with and without mussels present (density = 4/m2) to examine the influence of flooding on mussel movement, and to quantify the influence of mussels on channel morphology under steady state bedload transport. Additional experiments were conducted with threeridge at low flow (no bedload), under aggrading and degrading bed conditions, and doubled mussel density (8/m2). Mussel response to suspended sediment loads was examined in a complementary series of experiments in an indoor flume with Mississippi River water. Mussels outfitted with gape sensors were utilized in paired control/treatment experiments to examine the influence of moderate term (48 hours) exposure to elevated suspended sediment loads on mussel filtering activity. Together, these experiments provide multiple measures of mussel stress under high sediment loads and reveal how freshwater mussels

  4. Mercury transfer from bed sediments to freshwater fish (guppies)

    Energy Technology Data Exchange (ETDEWEB)

    Kudo, A.

    1976-01-01

    Mercury transfer from river sediments (treated with labelled mercuric chloride) to freshwater fish (Lebistes reticulata) (wet weight, 29 to 869 mg) was observed for 150 days. Release rate from the sediment indicates a half-life of 12 to 20 years. The amount taken up by the fish varied widely (up to 600 percent differences), but half-lives for clearance were all between 38 and 75 days. No correlation was found between mercury uptake rate and either size or sex of fish.

  5. Temperature-induced activation of freshwater Cyanophage AS-1 prophage

    OpenAIRE

    Chu, Tin-Chun; Murray, Sean R.; Hsu, Shi-Fang; Vega, Quinn; Lee, Lee H

    2010-01-01

    Synechococcus sp. IU 625 is one of the freshwater cyanobacteria responsible for harmful algal blooms (HAB). Cyanophages can serve as natural control agents and may be responsible for algal bloom prevention and disappearance. Cyanophage AS-1, which infects Synechococcus sp. IU 625 (Anacystis nidulans) and Synechococcus cedrorum, plays an important role in the environment, significantly altering the numbers of its hosts. Since seasonal (temperature-dependent) lytic induction of cyanobacterial p...

  6. Evolution of growth by genetic accommodation in Icelandic freshwater stickleback.

    Science.gov (United States)

    Robinson, Beren W

    2013-12-07

    Classical Darwinian adaptation to a change in environment can ensue when selection favours beneficial genetic variation. How plastic trait responses to new conditions affect this process depends on how plasticity reveals to selection the influence of genotype on phenotype. Genetic accommodation theory predicts that evolutionary rate may sharply increase when a new environment induces plastic responses and selects on sufficient genetic variation in those responses to produce an immediate evolutionary response, but natural examples are rare. In Iceland, marine threespine stickleback that have colonized freshwater habitats have evolved more rapid individual growth. Heritable variation in growth is greater for marine full-siblings reared at low versus high salinity, and genetic variation exists in plastic growth responses to low salinity. In fish from recently founded freshwater populations reared at low salinity, the plastic response was strongly correlated with growth. Plasticity and growth were not correlated in full-siblings reared at high salinity nor in marine fish at either salinity. In well-adapted lake populations, rapid growth evolved jointly with stronger plastic responses to low salinity and the persistence of strong plastic responses indicates that growth is not genetically assimilated. Thus, beneficial plastic growth responses to low salinity have both guided and evolved along with rapid growth as stickleback adapted to freshwater.

  7. Complexation of cobalt by natural ligands in freshwater

    Energy Technology Data Exchange (ETDEWEB)

    Qian, J.; Xue, H.B. [Swiss Federal Inst. for Environmental Science and Technology, Kastanienbaum (Switzerland); Sigg, L.; Albrecht, A. [Swiss Federal Inst. for Environmental Science and Technology, Duebendorf (Switzerland)

    1998-07-15

    Ligand exchange with dimethylglyoxime (DMG) and differential pulse cathodic stripping voltammetry (DPCSV) was applied to determine free Co(II) ionic concentrations [Co{sup 2+}] and Co(II) complexation by natural organic ligands in freshwater. [Co{sup 2+}] and the complexing parameters were calculated on the basis of the thermodynamic equilibria between added and natural ligands. The optimal working conditions were carefully evaluated in synthetic solutions and in natural freshwater samples. The results from samples collected at various sites from the Aare and Rhine Rivers and the Biel and Lucerne Lakes, Switzerland, are presented. The total dissolved Co concentrations are in the range of 0.5--6.5 nM, and [Co{sup 2+}] is in the range of 0.05--0.5 nM. Organic complexes of Co are predominant in most samples with 80--96% of total dissolved Co. A one-ligand model could well fit the titrations of freshwater samples with Co(II) (using the FITEQL program). The conditional stability constants of the natural ligands were computed to be log K = 9.5--11.6 (pH 8.0 {+-} 0.1), and the ligand concentrations were [L] = 1.4--7.6 nM. The reliability and applicability of the technique and the implications of the results are discussed.

  8. Fossil freshwater sponges: Taxonomy, geographic distribution, and critical review

    Directory of Open Access Journals (Sweden)

    Roberto Pronzato

    2017-09-01

    Full Text Available Sponges are one of the most ancient animal phyla with about 8850 living species and about 5000 described fossil taxa. Most sponges are marine and live at all depths of all oceans. Freshwater bodies (lakes, rivers are inhabited only by a small minority of species, ca. 240 (<3% comprising the order Spongillida (Demospongiae most of which are able to produce specialized resting bodies to survive harsh terrestrial environmental conditions. This highly disproportionate ratio of marine and freshwater sponges is even more accentuated in the field of palaeontology with rare records reported up to the Miocene (<0.4% of all known fossil sponges. Only a few fossil taxa were correctly supported by strong and convincing taxonomic morphotraits at genus and species level, thus we provide here an overview of fossil freshwater sponges focusing on their morphotraits and distribution in time and space. Each recorded taxon is described in detail following the modern taxonomy and nomenclature. All fossil data suggest a clear trend of long term conservative morphology in the evolutionary history of Spongillida, although some traits of Recent gemmules evolved in a wide array of adaptive morpho-functional novelties. The majority of accepted fossil species belongs to the cosmopolitan family Spongillidae. The genera Oncosclera and Potamophloios of the family Potamolepidae seem to have had, in the past, a much larger geographic range than today. A synthesis of fossil taxa morphotraits is also provided in an Appendix 1.

  9. A plea for the use of copepods in freshwater ecotoxicology.

    Science.gov (United States)

    Kulkarni, Devdutt; Gergs, André; Hommen, Udo; Ratte, Hans Toni; Preuss, Thomas G

    2013-01-01

    Standard species used in ecological risk assessment are chosen based on their sensitivity to various toxicants and the ease of rearing them for laboratory experiments. However, this mostly overlooks the fact that species in the field that may employ variable life-history strategies, which may have consequences concerning the vulnerability of such species to exposure with contaminants. We aimed to highlight the importance of copepods in ecology and to underline the need to include freshwater copepods in ecotoxicology. We carried out a literature search on copepods and Daphnia in ecology and ecotoxicology to compare the recognition given to these two taxa in these respective fields. We also conducted a detailed analysis of the literature on copepods and their current role in ecotoxicology to characterize the scale and depth of the studies and the ecotoxicological information therein. The literature on the ecology of copepods outweighed that in ecotoxicology when compared with daphnids. Copepods, like other zooplankton, were found to be sensitive to toxicants and important organisms in aquatic ecosystems. The few studies that were conducted on the ecotoxicology of copepods mainly focused on marine copepods. However, very little is known about the ecotoxicology of freshwater copepods. To enable a more realistic risk higher tier environmental risk assessment, we recommend considering freshwater copepods as part of the hazard assessment process. This could include the establishment of laboratory experiments to analyse the effects of toxicants on copepods and the development of individual-based models to extrapolate effects across species and scenarios.

  10. Anthropogenic climate change detected in European renewable freshwater resources

    Science.gov (United States)

    Gudmundsson, Lukas; Seneviratne, Sonia I.; Zhang, Xuebin

    2017-11-01

    Although there is overwhelming evidence showing that human emissions are affecting a wide range of atmospheric variables, it is not clear whether anthropogenic climate change is detectable in continental-scale freshwater resources. Owing to the complexity of terrestrial hydro-systems there is to date only limited evidence suggesting that climate change has altered river discharge in specific regions. Here we show that it is likely that anthropogenic emissions have left a detectable fingerprint in renewable freshwater resources in Europe. We use the detection and attribution approach to compare river-flow observations with state-of-the-art climate model simulations. The analysis shows that the previously observed amplification of the south (dry)-north (wet) contrast in pan-European river flow is captured by climate models only if human emissions are accounted for, although the models significantly underestimate the response. A regional analysis highlights that a strong and significant decrease is observed in the Mediterranean, generally along with a weak increase in northern Europe, whereas there is little change in transitional central Europe. As river and streamflow are indicators for renewable freshwater resources, the results highlight the necessity of raising awareness on climate change projections that indicate increasing water scarcity in southern Europe.

  11. Ammonia excretion in the freshwater planarian Schmidtea mediterranea.

    Science.gov (United States)

    Weihrauch, Dirk; Chan, Ainsely C; Meyer, Heiko; Döring, Carmen; Sourial, Mary; O'Donnell, Michael J

    2012-09-15

    In aquatic invertebrates, metabolic nitrogenous waste is excreted predominately as ammonia. Very little is known, however, of the underlying mechanisms of ammonia excretion, particularly in freshwater species. Our results indicate that in the non-parasitic freshwater planarian Schmidtea mediterranea, ammonia excretion depends on acidification of the apical unstirred layer of the body surface and consequent ammonia trapping. Buffering of the environment to a pH of 7 or higher decreased the excretion rate. Inhibitor experiments suggested further that the excretion mechanism involves the participation of the V-type H(+)-ATPase and carbonic anhydrase and possibly also the Na(+)/K(+)-ATPase and Na(+)/H(+) exchangers. Alkalinization (pH 8.5, 2 days) of the environment led to a 1.9-fold increase in body ammonia levels and to a downregulation of V-ATPase (subunit A) and Rh-protein mRNA. Further, a 2 day exposure to non-lethal ammonia concentrations (1 mmol l(-1)) caused a doubling of body ammonia levels and led to an increase in Rh-protein and Na(+)/K(+)-ATPase (α-subunit) mRNA expression levels. In situ hybridization studies indicated a strong mRNA expression of the Rh-protein in the epidermal epithelium. The ammonia excretion mechanism proposed for S. mediterranea reveals striking similarities to the current model suggested to function in the gills of freshwater fish.

  12. 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 soft tissues of live freshwater mussels, Eastern elliptio Elliptio complanata, via magnetic resonance imaging (MRI), acquiring data with a widely available human whole-body MRI system. Anatomical features depicted in the profile images included the foot, stomach, intestine, anterior and posterior adductor muscles, and pericardial cavity. Noteworthy observations on soft tissue morphology included a concentration of lipids at the most posterior aspect of the foot, the presence of hemolymph-filled fissures in the posterior adductor muscle, the presence of a relatively large hemolymph-filled sinus adjacent to the posterior adductor muscle (at the ventral-anterior aspect), and segmentation of the intestine (a diagnostic description not reported previously in Unionidae). Relatively little is known about the basic biology and ecological physiology of freshwater mussels. Traditional approaches for studying anatomy and tissue processes, and for measuring sub-lethal physiological stress, are destructive or invasive. Our study, the first to evaluate freshwater mussel soft tissues by MRI, clarifies the body plan of unionid mussels and demonstrates the efficacy of this technology for in vivoevaluation of the structure, function, and integrity of mussel soft tissues.

  13. Temperature-induced activation of freshwater Cyanophage AS-1 prophage.

    Science.gov (United States)

    Chu, Tin-Chun; Murray, Sean R; Hsu, Shi-Fang; Vega, Quinn; Lee, Lee H

    2011-05-01

    Synechococcus sp. IU 625 is one of the freshwater cyanobacteria responsible for harmful algal blooms (HAB). Cyanophages can serve as natural control agents and may be responsible for algal bloom prevention and disappearance. Cyanophage AS-1, which infects Synechococcus sp. IU 625 (Anacystis nidulans) and Synechococcus cedrorum, plays an important role in the environment, significantly altering the numbers of its hosts. Since seasonal (temperature-dependent) lytic induction of cyanobacterial prophage has been proposed to affect seawater algal blooms, we investigated if the AS-1 lytic cycle could be induced by a shift to high temperature. Our hypothesis was confirmed, as more phages were released at 35°C than at 24°C, with maximal induction observed with a shift from 24 to 35°C. Furthermore, transmission electron microscopy (TEM) images provide direct evidence of lysogenic to lytic conversion with temperature shift. Thus, temperature is an important inducer for AS-1 conversion from lysogenic to lytic cycle and could have applications in terms of modulating cyanobacterial populations in freshwater aquatic environments. The study gives insight into the effect of climate change on the interaction between cyanophage and cyanobacteria in freshwater ecosystems. Copyright © 2009 Elsevier GmbH. All rights reserved.

  14. Pulsed-laser deposition of vicinal and c-axis oriented high temperature superconducting thin films

    CERN Document Server

    Rössler, R

    2000-01-01

    respect to the temperature, oxygen pressure and laser fluence. (Re,Hg)Ba sub 2 Ca sub ( n-1)Cu sub n O sub x films are synthesized on (001) and vicinal SrTiO sub 3 substrates in a two step process employing pulsed-laser deposition of Hg-free precursor films and Hg-vapour annealing in a sealed quartz tube. The sealed quartz tube technique is described in detail and the thermodynamics and the phase formation are discussed. The influence of the Hg-vapour pressure and the annealing temperature on the film properties are investigated. The influence of Hg-vapour annealing on Bi sub 2 Sr sub 2 CaCu sub 2 O sub x films is described. YBa sub 2 Cu sub 3 O sub x films with thicknesses 20 to 480 nm are deposited on vicinal SrTiO sub 3 substrates (10 degrees tilt angle). Variation of the resistivities and changes in the film morphology depending on film thickness are described. The influence of post-annealing treatments on the film properties is discussed. Pulsed-laser deposition (PLD) of high temperature superconducting ...

  15. Chemistry of spring and well waters on Kilauea Volcano, Hawaii, and vicinity

    Energy Technology Data Exchange (ETDEWEB)

    Janik, C.J.; Nathenson, M.; Scholl, M.A.

    1994-12-31

    Published and new data for chemical and isotopic samples from wells and springs on Kilauea Volcano and vicinity are presented. These data are used to understand processes that determine the chemistry of dilute meteoric water, mixtures with sea water, and thermal water. Data for well and spring samples of non-thermal water indicate that mixing with sea water and dissolution of rock from weathering are the major processes that determine the composition of dissolved constituents in water. Data from coastal springs demonstrate that there is a large thermal system south of the lower east rift of Kilauea. Samples of thermal water from shallow wells in the lower east rift and vicinity have rather variable chemistry indicating that a number of processes operate in the near surface. Water sampled from the available deep wells is different in composition from the shallow thermal water, indicating that generally there is not a significant component of deep water in the shallow wells. Data for samples from available deep wells show significant gradients in chemistry and steam content of the reservoir fluid. These gradients are interpreted to indicate that the reservoir tapped by the existing wells is an evolving vapor-dominated system.

  16. Mapping human vulnerability to chemical accidents in the vicinity of chemical industry parks.

    Science.gov (United States)

    Li, Fengying; Bi, Jun; Huang, Lei; Qu, Changsheng; Yang, Jie; Bu, Quanmin

    2010-07-15

    China is suffering from severe pollution accidents which may have catastrophic impacts on the local population and environment. Some questions are unclear to local governments and industry operators like "who are vulnerable to the chemical risks?" and "what is the magnitude of vulnerability?". This paper concentrates on exploring the concepts of human vulnerability and the methodology of analyzing human vulnerability to chemical accidents in the vicinity of chemical industry parks. A conceptual model of human vulnerability to chemical accidents is developed, revealing the roots of human vulnerability and emphasizing its role in risk management. A geographical information system (GIS)-based methodology for mapping vulnerability is proposed and applied to the Nanjing Chemical Industry Park in China. By combining physical vulnerability and social vulnerability spatially, the total vulnerability is revealed to better respond to accidents. It is proposed to improve traffic lines and allocation of medical services, and include vulnerability assessment in land-use planning to reduce future risks. In other words, it seems feasible and effective to reveal physical, social and total vulnerability of residents in the vicinity of chemical risk sources. 2010 Elsevier B.V. All rights reserved.

  17. Neutron diffraction analysis of residual strain/stress distribution in the vicinity of high strength welds

    Directory of Open Access Journals (Sweden)

    Hamák I.

    2010-06-01

    Full Text Available Residual stresses resulting from non homogeneous heat distribution during welding process belong to most significant factor influencing behavior of welded structures. These stresses are responsible for defect occurrence during welding and they are also responsible for crack initiation and propagation at the either static or dynamic load. The significant effect of weld metal chemical composition as well as the effect of fatigue load and local plastic deformation on residual stress distribution and fatigue life have been recognized for high strength steels welds. The changes in residual stress distribution have then positive effect on cold cracking behavior and also on fatigue properties of the welds [1-3]. Several experimental methods, both destructive and non-destructive, such as hole drilling method, X-ray diffraction, neutron diffraction and others, have been used to examine residual stress distribution in all three significant orientations in the vicinity of the welds. The present contribution summarizes the results of neutron diffraction measurements of residual stress distribution in the vicinity of single-pass high-strength-steel welds having different chemical composition as well as the influence of fatigue load and local plastic deformation. It has been observed that the chemical composition of the weld metal has a significant influence on the stress distribution around the weld. Similarly, by aplying both cyclic load or pre-stress load on the specimens, stress relaxation was observed even in the region of approximately 40 mm far from the weld toe.

  18. Local temperature measurement in the vicinity of electromagnetically heated magnetite and gold nanoparticles

    Science.gov (United States)

    Gupta, Amit; Kane, Ravi S.; Borca-Tasciuc, Diana-Andra

    2010-09-01

    This paper describes a new technique employing fluorescent quantum dots as temperature probes for measuring the temperature rise in the proximity of nanoparticles heated by a radio frequency (rf) electromagnetic field. The remote heating of nanoparticles by an rf field is a promising approach to control biological transformations at the molecular level. In principle, the heat dissipated by each nanoparticle might produce a temperature increase in its proximity, facilitating a change in the molecules directly attached to it but not in the others. Although this method has been demonstrated to provide control over biological transformations, the proposed mechanism involves producing and maintaining large temperature differences across small distances, in the range of several degrees Celsius across tens of nanometers. Existing theories for heat generation and transfer in rf heated nanoparticle systems cannot account for these gradients. To better understand the limitations of local heating, the temperature in the vicinity of rf heated nanoparticles was measured. Dilute aqueous suspensions of gold and magnetite nanoparticles were remotely heated by an rf field between 600-800 kHz. Two systems were investigated: a control sample consisting of quantum dots mixed with nanoparticles and a solution of quantum dots covalently linked to nanoparticles. The temperature of the fluorescent probes represents the average temperature in the former and the local temperature in the later. For the experimental conditions employed in this study, the measured temperature rise in the vicinity of rf heated nanoparticles were similar to the average or "bulk" temperature, in agreement with theoretical predictions.

  19. Tracking an electronic wave packet in the vicinity of a conical intersection

    Science.gov (United States)

    Qi, Da-Long; Duan, Hong-Guang; Sun, Zhen-Rong; Miller, R. J. Dwayne; Thorwart, Michael

    2017-08-01

    This work treats the impact of vibrational coherence on the quantum efficiency of a dissipative electronic wave packet in the vicinity of a conical intersection by monitoring the time-dependent wave packet projection onto the tuning and the coupling mode. The vibrational coherence of the wave packet is tuned by varying the strength of the dissipative vibrational coupling of the tuning and the coupling modes to their thermal baths. We observe that the most coherent wave packet yields a quantum efficiency of 93%, but with a large transfer time constant. The quantum yield is dramatically decreased to 50% for a strongly damped incoherent wave packet, but the associated transfer time of the strongly localized wave packet is short. In addition, we find for the strongly damped wave packet that the transfer occurs via tunneling of the wave packet between the potential energy surfaces before the seam of the conical intersection is reached and a direct passage takes over. Our results provide direct evidence that vibrational coherence of the electronic wave packet is a decisive factor which determines the dynamical behavior of a wave packet in the vicinity of the conical intersection.

  20. Group V adsorbate structures on vicinal Ge(001) surfaces determined from the optical spectrum

    Science.gov (United States)

    Banerjee, S.; Patterson, C. H.; McGilp, J. F.

    2017-06-01

    Vicinal Ge(001) is the standard substrate for the fabrication of high-performance solar cells by metal-organic vapour phase epitaxy, where growth of the III-V material on single domain Ge surfaces, with a single dimer orientation, minimizes the formation of anti-phase domain defects. Reflectance anisotropy spectroscopy has proved to be a powerful and sensitive optical probe of such anisotropic surface structures, but moving beyond fingerprinting to atomic structure determination from the optical spectra has been held back by the high computational cost. It is shown that an empirical, local-orbital-based hybrid density functional theory approach produces very good agreement between the theory and the experiment for (2 × 1)-As and (2 × 1)-Sb structures grown on vicinal Ge(001). These results, when taken together with previous work on Si interfaces, show that this computationally efficient approach is likely to prove to be an important general technique for determining the structure of anisotropic semiconductor surfaces and interfaces by comparing the experimental and calculated optical spectrum.

  1. Nanoscale patterning, macroscopic reconstruction, and enhanced surface stress by organic adsorption on vicinal surfaces

    Science.gov (United States)

    Pollinger, Florian; Schmitt, Stefan; Sander, Dirk; Tian, Zhen; Kirschner, Jürgen; Vrdoljak, Pavo; Stadler, Christoph; Maier, Florian; Marchetto, Helder; Schmidt, Thomas; Schöll, Achim; Umbach, Eberhard

    2017-01-01

    Self-organization is a promising method within the framework of bottom-up architectures to generate nanostructures in an efficient way. The present work demonstrates that self-organization on the length scale of a few to several tens of nanometers can be achieved by a proper combination of a large (organic) molecule and a vicinal metal surface if the local bonding of the molecule on steps is significantly stronger than that on low-index surfaces. In this case thermal annealing may lead to large mass transport of the subjacent substrate atoms such that nanometer-wide and micrometer-long molecular stripes or other patterns are being formed on high-index planes. The formation of these patterns can be controlled by the initial surface orientation and adsorbate coverage. The patterns arrange self-organized in regular arrays by repulsive mechanical interactions over long distances accompanied by a significant enhancement of surface stress. We demonstrate this effect using the planar organic molecule PTCDA as adsorbate and Ag(10 8 7) and Ag(775) surfaces as substrate. The patterns are directly observed by STM, the formation of vicinal surfaces is monitored by high-resolution electron diffraction, the microscopic surface morphology changes are followed by spectro-microscopy, and the macroscopic changes of surface stress are measured by a cantilever bending method. The in situ combination of these complementary techniques provides compelling evidence for elastic interaction and a significant stress contribution to long-range order and nanopattern formation.

  2. Scanning Tunneling Microscopy Study of a Vicinal Anatase TiO2 Surface

    Science.gov (United States)

    Li, Shao-Chun; Dulub, Olga; Diebold, Ulrike

    2009-03-01

    Titanium dioxide finds versatile applications in various technical fields including gas sensing, coatings, pigments, heterogeneous catalysis, photocatalytic degradation of pollutants, and solar cells. TiO2 is found in three main crystallographic phases: rutile, anatase and brookite. Rutile is the thermodynamically most stable form and is considered a model system for basic research. However, anatase TiO2 is often considered to be catalytically more active than rutile for reasons not yet completely understood. In this work, using scanning tunneling microscopy (STM) and low energy electron diffraction (LEED), the structure of the anatase TiO2(5 14) surface, ˜10 vicinal to the -- lowest energy -- (101) plane, has been studied. The surface was found to facet into a structure composed of ridges with a uniform width of 5 lattice units. Based on atomically-resolved STM and electron counting rules, it is proposed that the sides of the ridges are parallel to (1 10) and (112) planes. These sides might be reconstructed to stabilize the microfaceted structure. Vapor-deposited gold shows pronounced clustering between the ridges, indicating a one-dimensional template effect of the vicinal surface, which supports denser and more uniformly sized Au clusters, as compared to the flat (101) surface.

  3. Localization of the electromagnetic field in the vicinity of gold nanoparticles: Surface modification of different substrates

    Energy Technology Data Exchange (ETDEWEB)

    Atanasov, Petar A. [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko Shousse 72, Sofia 1784 (Bulgaria)], E-mail: paatanas@ie.bas.bg; Nedyalkov, Nikolay N. [Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko Shousse 72, Sofia 1784 (Bulgaria); Sakai, Tetsuo; Obara, Minoru [Department of Electronics and Electrical Engineering, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)

    2007-12-15

    Theoretical predictions and experimental results for nanosized modification of metal (Au), semiconductor (Si), or dielectric (soda lime glass) substrates using near-electromagnetic field enhancement in the vicinity of gold nanoparticles are presented. The near field properties for the system consisting of an isolated gold nanoparticle or nanoparticle aggregate deposited on the substrates, which is irradiated by electromagnetic wave, are investigated using Finite Difference Time Domain Simulation technique. The influence of the substrate material on the near field distribution characteristics is predicted. The results reveal that the field on the substrate surface is enhanced in the three investigated cases, but its spatial distribution and magnitude depend on the substrate material. In the case of the metal and semiconductor substrate the enhanced near field is strongly localized in the vicinity of the contact point with the particle, in an area with diameter smaller than the particle's one. The intensity of the enhanced field on the glass is more than an order of magnitude lower than the case of using silicon substrate. The properties of the near field on the substrate surface also depend on the particle arrangement. For a two-dimensional gold nanoparticle array, when the particles are closely arrayed, the intensity of the enhanced field on the substrate surface is minimal. With the increase of the interparticle distance the near field intensity increases. The validity of the obtained theoretical results is confirmed experimentally.

  4. 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 for migratory fish species, is applicable to any freshwater conservation plan to favour planning unit selection within selected basins, while facilitating connectivity in upstream?downstream subcatchments. Keywords: connectivity, MARXAN, nested hierarchy... et al., this issue). Protec- tion of river fragments alone will not achieve conser- vation goals. Innovative solutions that recognise this ?nested hierarchy? in the aquatic environment ? i.e. placing aquatic systems in a catchment context, from...

  5. Ficoflora de ambientes lênticos: estudo preliminar da região de Charqueadas, Rio Grande do Sul, Brasil, com vistas à avaliação ambiental Metaphyton, benthos and phytoplantonic communities in lentic systems in the region of Charqueadas Rio Grande do Sul, Brazil

    Directory of Open Access Journals (Sweden)

    Zulanira Meyer Rosa

    1987-07-01

    Full Text Available São apresentados os resultados do estudo do metafíton, bentos e de comunidades fitoplanctônicas ocorrentes em ambientes lênticos de Charqueadas e municípios vizinhos, região esta sujeita à influência de mineração e processamento de carvão mineral. O estudo baseou-se em 46 amostras coletadas em julho e agosto de 1986. Dos 213 táxons específicos e infra-específicos identificados, 95 constituem-se em primeiro registro de ocorrência no Estado. Os grupos melhor representados quanto ao número de espécies ocorrentes foram Chlorophyta (Desmídias e Bacillariophyta (Diatomáceas. Foi constatada presença de espécies indicadas na literatura como organismos de ambientes ácidos, com maior representatividade no bentos e metafíton de biótopos sujeitos à influência direta de rejeito de carvão. Nesses sistemas ácidos, foi registrada no fitoplâncton dominância de organismos nanoplanctônicos da classe Chrysophyceae, estando quantitativamente bem representadas, no bentos, as Euglenophyta, Bacillariophyta e Chlorophyta. A estrutura das comunidades fitoplanctônicas mostrou baixos índices de diversidade, caracterizando um desequilíbrio na composição específica das mesmas.Metaphyton, benthos and phytoplanktonic communities occurring in lentic systems were studied in July and August 1986. The study was based on 46 samples collected in Charqueadas and other neighboring areas in the State of Rio Grande do Sul, a region which suffers the effects of coal mining and processing. Out of the 213 specific and infraspecific taxa identified, 95 are a first record in the State of Rio Grande do Sul. As far as the number of occurring species is concerned, the best represented groups were Chlorophyta (Desmids and Bacillariophyta (Diatoms. Organisms indicative of acid systems were found, mostly in benthos and metaphyton environments subject to the influence of coal wastes. In these acid systems, phytoplankton showed nanoplanktonic organisms of the

  6. Euglenophyceae de ambientes lênticos na planície costeira do Rio Grande do Sul, Sul do Brasil: gêneros Euglena Ehr. e Lepocinclis Perty Euglenophyceae of lentic environments at the coastal plain of Rio Grande do Sul State, South of Brazil: genera Euglena Ehr. and Lepocinclis Perty

    Directory of Open Access Journals (Sweden)

    Sandra Maria Alves-da-Silva

    2006-06-01

    Full Text Available São apresentados 28 táxons específicos e infra-específicos dos gêneros Euglena Ehr. e Lepocinclis Perty como resultado do estudo do fitoplâncton e perifíton em ambientes lênticos (lagoas, açude e banhados da Lagoa do Casamento e ecossistemas associados (30º03'- 30º34'S e 50º25'- 50º47'W e ecossistemas próximos ao Butiazal de Tapes (30º23'- 30º38'S e 51º16'- 51º29'W na planície costeira do Rio Grande do Sul. As coletas abrangeram as estações de outono e primavera de 2003. As áreas úmidas (banhados associadas à Lagoa do Casamento na primavera de 2003 apresentaram maior riqueza específica destes dois gêneros. Lepocinclis salina Fritsch var. salina foi a espécie que se distinguiu quanto a distribuição por ter ocorrido em 41,2% do total de amostras analisadas. São novos registros para o estado do Rio Grande do Sul e país, L. playfairiana Defl. var. playfairiana e L. boseensis Xie, Qiu & Ling.Twenty eight specific and infra-specific taxa of the genera Euglena Ehr. and Lepocinclis Perty are presented as a result of phytoplankton and periphyton study in lentic systems next to Lagoa do Casamento (30º03'- 30º34'S and 50º25'- 50º47'W and Butiazal de Tapes (30º23'- 30º38'S and 51º16'- 51º29'W, coastal zone of Rio Grande do Sul State. Samples were collected in autumn and spring seasons in 2003. The swamps associated to Lagoa do Casamento in spring of 2003 presented more specific richness of these two genera. Lepocinclis salina Fritsch var. salina distinguished by its distribution, occuring in 41,2% of the analized samples. Two taxa are new records for the State and Brazil: L. playfairiana Defl. var. playfairiana and L. boseensis Xie, Qiu & Ling.

  7. Description of seven candidate species affiliated with the phylum Actinobacteria, representing planktonic freshwater bacteria

    OpenAIRE

    Hahn, Martin W.

    2009-01-01

    Actinobacteria comprise a substantial fraction of the bacterioplankton in freshwater lakes and streams. Numerous cultivation-independent investigations have retrieved actinobacterial 16S rRNA gene sequences from such habitats. The taxa detected in freshwater habitats are usually absent from terrestrial and marine systems. So far, none of the indigenous freshwater lineages is represented by a taxon with a validly published name. The seven organisms for which Candidatus status is described here...

  8. Contrasting sensitivities to toxicants of the freshwater amphipods Gammarus pulex and G. fossarum

    OpenAIRE

    ALONSO, A.; Lange, de, H.J.; Peeters, E.T.H.M.

    2010-01-01

    Amphipods are an important component of freshwater ecosystems. They are very often used in ecotoxicology, particularly the freshwater amphipod Gammarus pulex. However, there is scarce information on the sensitivity to toxicants of other species within the genus Gammarus. The present study aims to: (1) to compare sensitivities to ivermectin and cadmium between two species of freshwater amphipods (G. pulex and G. fossarum); (2) to compare sensitivities to these toxicants between juveniles and a...

  9. A checklist of freshwater fishes of the New Amarambalam Reserve Forest (NARF, Kerala, India

    Directory of Open Access Journals (Sweden)

    F. Baby

    2010-11-01

    Full Text Available The freshwater fish fauna of New Amarambalam Reserve Forest (NARF in the Southern Western Ghats (Kerala is constituted by 43 species belonging to 13 families and 28 genera. Family Cyprinidae dominated with 20 species followed by Balitoridae and Bagridae (four species each. NARF may harbour higher freshwater fish species diversity than in protected areas in North Kerala. The area around Maanchery in the Karimpuzha tributary of River Chaliyar needs to be designated as a priority area for freshwater fish conservation.

  10. Laboratory Studies of the Effects of Static and Variable Magnetic Fields on Freshwater Fish

    Energy Technology Data Exchange (ETDEWEB)

    Cada, Glenn F [ORNL; Bevelhimer, Mark S [ORNL; Fortner, Allison M [ORNL; Riemer, Kristina P [ORNL; Schweizer, Peter E [ORNL

    2012-04-01

    There is considerable interest in the development of marine and hydrokinetic energy projects in rivers, estuaries, and coastal ocean waters of the United States. Hydrokinetic (HK) technologies convert the energy of moving water in river or tidal currents into electricity, without the impacts of dams and impoundments associated with conventional hydropower or the extraction and combustion of fossil fuels. The Federal Energy Regulatory Commission (FERC) maintains a database that displays the geographical distribution of proposed HK projects in inland and tidal waters (FERC 2012). As of March 2012, 77 preliminary permits had been issued to private developers to study HK projects in inland waters, the development of which would total over 8,000 MW. Most of these projects are proposed for the lower Mississippi River. In addition, the issuance of another 27 preliminary permits for HK projects in inland waters, and 3 preliminary permits for HK tidal projects (totaling over 3,100 MW) were under consideration by FERC. Although numerous HK designs are under development (see DOE 2009 for a description of the technologies and their potential environmental effects), the most commonly proposed projects entail arrays of rotating devices, much like submerged wind turbines, that are positioned in the high-velocity (high energy) river channels. The many diverse HK designs imply a diversity of environmental impacts, but a potential impact common to most is the effect on aquatic organisms of electromagnetic fields (EMF) created by the projects. The submerged electrical generator will emit an EMF into the surrounding water, as will underwater cables used to transmit electricity from the generator to the shore, between individual units in an array (inter-turbine cables), and between the array and a submerged step-up transformer. The electric current moving through these cables will induce magnetic fields in the immediate vicinity, which may affect the behavior or viability of fish and

  11. The Value and limitations of various approaches to the monitoring of water quality for freshwater fish

    National Research Council Canada - National Science Library

    1978-01-01

    Concomitant with the general desire to protect freshwater fisheries has been an expansion of research into their water quality requirements and, for important contaminants, the maximum concentrations...

  12. A Comparative study on the nonspecific immunity of juvenile Litopenaeus vannamei ever inhabiting freshwater and seawater

    Science.gov (United States)

    Jia, Xuying; Ding, Sen; Wang, Fang; Dong, Shuanglin

    2014-06-01

    A study on the nonspecific immunity of Litopenaeus vannamei ever inhabiting freshwater and seawater was carried out at different molt stages by comparing their total hemocyte count (THC) and respiratory burst (RB) and activity of phenol oxidase (PO), nitric oxide synthase (NOS) and lysozyme (LY). Two-way ANOVA showed that salinity and molt stage independently affected THC and RB and the activity of PO, NOS and LY of juvenile L. vannamei significantly ( P vannamei were significantly lower in freshwater than in seawater; whereas THC was significantly higher in freshwater than in seawater ( P vannamei was cultured in freshwater.

  13. Culturally significant fisheries: keystones for management of freshwater social-ecological systems

    Directory of Open Access Journals (Sweden)

    Mae Noble

    2016-06-01

    Full Text Available Indigenous peoples of North America, Australia, and New Zealand have a long tradition of harvesting freshwater animals. Over generations of reliance and subsistence harvesting, Indigenous peoples have acquired a profound understanding of these freshwater animals and ecosystems that have become embedded within their cultural identity. We have identified trans-Pacific parallels in the cultural significance of several freshwater animal groups, such as eels, other finfish, bivalves, and crayfish, to Indigenous peoples and their understanding and respect for the freshwater ecosystems on which their community survival depends. In recognizing such cultural connections, we found that non-Indigenous peoples can appreciate the deep significance of freshwater animals to Indigenous peoples and integrate Indigenous stewardship and Indigenous ecological knowledge into effective comanagement strategies for sustainable freshwater fisheries, such as Indigenous rangers, research partnerships, and Indigenous Protected Areas. Given that many of these culturally significant freshwater species also play key ecological roles in freshwater ecosystems, their recognition and prioritization in management and monitoring approaches should help sustain the health and well-being of both the social and ecological components of freshwater ecosystems.

  14. Lead and cadmium in mushrooms from the vicinity of two large emission sources in Slovenia

    Energy Technology Data Exchange (ETDEWEB)

    Petkovšek, Samar Al Sayegh, E-mail: samar.petkovsek@erico.si; Pokorny, Boštjan

    2013-01-15

    Cd and Pb contents were determined in 699 samples of fruiting bodies of 55 mushrooms species, collected in the period 2000–2007 in the vicinity of the largest Slovenian thermal power plant (the Šalek Valley) and near an abandoned lead smelter (the Upper Meža Valley). The present study is the first regarding lead and cadmium in mushrooms from those exposed areas. Therefore, there was a significant lack of prior data. Among 55 studied mushroom species 36 species are edible and important from an ecotoxicological perspective. However, the remaining non-edible species are important for bioindication and allowed us to compare our results with other studies carried out in other polluted areas in Europe. The highest contents of Cd were found in Agaricus arvensis Schff.: Fr. (117 mg/kg dw) and Agaricus silvicola L.: Fr. (67.9 mg/kg dw), while the highest contents of Pb were found in Macrolepiota procera (Scop.) Singer (53.8 mg/kg dw) and Lycoperdon perlatum Pers. (50 mg/kg dw), respectively. Considering the high contents of both metals in fruiting bodies of edible fungi, together with FAO/WHO directives on tolerable levels of weekly intake of Pb/Cd by humans, it is evident that consumption of some mushroom species originating from both study areas may pose a significant human health risk. A. arvensis Schff.: Fr., A. silvicola L.: Fr. and Cortinarius caperatus (Pers.) Fr. originating from the Šalek Valley, and Armillaria mellea Vahl. P. Kumm., Boletus edulis Bull., L. perlatum Pers., Leccinum versipelle (Fr. and Hök) Snell, and M. procera (Scop.) Singer originating from the Upper Meža Valley should not be consumed at all. Our findings are consistent with some other studies, which emphasized that mushrooms from heavily polluted areas, such as in the vicinity of smelters, accumulate extremely high amounts of metals, and should therefore be omitted from human consumption. - Highlights: ► The Pb contents were higher in saprophytic fungi in comparison with mycorrhizal

  15. EISCAT and Cluster observations in the vicinity of the dynamical polar cap boundary

    Directory of Open Access Journals (Sweden)

    A. T. Aikio

    2008-02-01

    Full Text Available The dynamics of the polar cap boundary and auroral oval in the nightside ionosphere are studied during late expansion and recovery of a substorm from the region between Tromsø (66.6° cgmLat and Longyearbyen (75.2° cgmLat on 27 February 2004 by using the coordinated EISCAT incoherent scatter radar, MIRACLE magnetometer and Cluster satellite measurements. During the late substorm expansion/early recovery phase, the polar cap boundary (PCB made zig-zag-type motion with amplitude of 2.5° cgmLat and period of about 30 min near magnetic midnight. We suggest that the poleward motions of the PCB were produced by bursts of enhanced reconnection at the near-Earth neutral line (NENL. The subsequent equatorward motions of the PCB would then represent the recovery of the merging line towards the equilibrium state (Cowley and Lockwood, 1992. The observed bursts of enhanced westward electrojet just equatorward of the polar cap boundary during poleward expansions were produced plausibly by particles accelerated in the vicinity of the neutral line and thus lend evidence to the Cowley-Lockwood paradigm. During the substorm recovery phase, the footpoints of the Cluster satellites at a geocentric distance of 4.4 RE mapped in the vicinity of EISCAT measurements. Cluster data indicate that outflow of H+ and O+ ions took place within the plasma sheet boundary layer (PSBL as noted in some earlier studies as well. We show that in this case the PSBL corresponded to a region of enhanced electron temperature in the ionospheric F region. It is suggested that the ion outflow originates from the F region as a result of increased ambipolar diffusion. At higher altitudes, the ions could be further energized by waves, which at Cluster altitudes were observed as BBELF (broad band extra low frequency fluctuations. The four-satellite configuration of Cluster revealed a sudden poleward expansion of the PSBL by 2° during ~5 min. The beginning of the poleward motion of the PCB

  16. EISCAT and Cluster observations in the vicinity of the dynamical polar cap boundary

    Directory of Open Access Journals (Sweden)

    A. T. Aikio

    2008-02-01

    Full Text Available The dynamics of the polar cap boundary and auroral oval in the nightside ionosphere are studied during late expansion and recovery of a substorm from the region between Tromsø (66.6° cgmLat and Longyearbyen (75.2° cgmLat on 27 February 2004 by using the coordinated EISCAT incoherent scatter radar, MIRACLE magnetometer and Cluster satellite measurements. During the late substorm expansion/early recovery phase, the polar cap boundary (PCB made zig-zag-type motion with amplitude of 2.5° cgmLat and period of about 30 min near magnetic midnight. We suggest that the poleward motions of the PCB were produced by bursts of enhanced reconnection at the near-Earth neutral line (NENL. The subsequent equatorward motions of the PCB would then represent the recovery of the merging line towards the equilibrium state (Cowley and Lockwood, 1992. The observed bursts of enhanced westward electrojet just equatorward of the polar cap boundary during poleward expansions were produced plausibly by particles accelerated in the vicinity of the neutral line and thus lend evidence to the Cowley-Lockwood paradigm.

    During the substorm recovery phase, the footpoints of the Cluster satellites at a geocentric distance of 4.4 RE mapped in the vicinity of EISCAT measurements. Cluster data indicate that outflow of H+ and O+ ions took place within the plasma sheet boundary layer (PSBL as noted in some earlier studies as well. We show that in this case the PSBL corresponded to a region of enhanced electron temperature in the ionospheric F region. It is suggested that the ion outflow originates from the F region as a result of increased ambipolar diffusion. At higher altitudes, the ions could be further energized by waves, which at Cluster altitudes were observed as BBELF (broad band extra low frequency fluctuations.

    The four-satellite configuration of Cluster revealed a sudden poleward expansion of the PSBL by 2° during

  17. Laboratory modelling of resonant wave-current interaction in the vicinity wind farm masts

    Science.gov (United States)

    Gunnoo, Hans; Abcha, Nizar; Garcia-Hermosa, Maria-Isabel; Ezersky, Alexander

    2015-04-01

    In the nearest future, by 2020, about 4% of electricity in Europe will be supplied by sea stations operating from renewable sources: ocean thermal energy, wave and tidal energy, wind farms. By now the wind stations located in the coastal zone, provide the most part of electricity in different European countries. Meanwhile, effects of wind farms on the environment are not sufficiently studied. We report results of laboratory simulations aimed at investigation of hydrodynamic fields arising in the vicinity of wind farm masts under the action of currents and surface waves. The main attention is paid to modeling the resonance effects when the amplitude of velocity pulsations in the vicinity of the masts under the joint action of currents and harmonic waves demonstrate significant growth. This resonance can lead to an increase in Reynolds stress on the bottom, intensification of sediment transport and sound generation. The experiments are performed in the 17 meters hydrodynamical channel of laboratory Morphodynamique Continentale et Côtière UMR CNRS 6143. Mast are modeled by vertical cylinder placed in a steady flow. Behind the cylinder turbulent Karman vortex street occurs. Results are obtained in interval of Reynolds numbers Re=103 - 104(Re=Ud/v, where U is the velocity of the flow, d is diameter of the cylinder, ν is cinematic viscosity). Harmonic surface waves of small amplitude propagating upstream are excited by computer controlled wave maker. In the absence of surface waves, turbulent Karman street with averaged frequency f is observed. It is revealed experimentally that harmonic surface waves with a frequencies closed to 2f can synchronize vortex shedding and increase the amplitude of velocity fluctuations in the wake of the cylinder. Map of regimes is found on the parameter plane amplitude of the surface wave - wave frequency. In order to distinguish the synchronization regimes, we defined phase of oscillations using the Hilbert transform technique. We

  18. Microphotoluminescence spectroscopy of CdSe quantum dots grown on vicinal-surface and exact-orientation substrates

    Energy Technology Data Exchange (ETDEWEB)

    Makino, T.; Andre, R.; Romestain, R.; Dang, Le Si [CEA-CNRS-UJF Joint Group Nanophysics and Semiconductors (France); Laboratoire de Spectrometrie Physique, CNRS UMR 5588, Universite J. Fourier-Grenoble 1, 38402 Saint-Martin-d' Heres (France); Gerard, J.M. [CEA-CNRS-UJF Joint Group Nanophysics and Semiconductors (France); CEA-Grenoble, Departement de Recherche Fondamentale sur la Matiere Condensee/SP2M, 17 avenue des Martyrs, 38054 Grenoble Cedex 9 (France); Bartels, M.; Lischka, K.; Schikora, D. [Department of Physics, University of Paderborn, Warburger Strasse 100, 33098 Paderborn (Germany)

    2004-03-01

    We investigated the optical properties of CdSe quantum dots (QDs) grown by molecular-beam epitaxy on GaAs substrates using micro-photoluminescence spectroscopy. Comparison was made between the QDs grown on a substrate with a vicinal tilt of 2 in the [111] direction and those on an on-axis substrate. We have studied the evolution of lineshapes of QD photoluminescence spectra under the improved condition of spatial resolution. It was found that the use of a substrate with the vicinal surface leads to the suppression of excitonic PL emitted from a wetting layer. The PL studies revealed that the thermo-stability up to 150 K was obtained in the sample on the on-axis substrate, whereas rapid temperature-induced quenching starting from 6 K was observed in that grown on the vicinal substrate. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Microphotoluminescence spectroscopy of CdSe quantum dots grown on vicinal-surface and exact-orientation substrates

    Science.gov (United States)

    Makino, T.; André, R.; Gérard, J. M.; Romestain, R.; Dang, Le Si; Bartels, M.; Lischka, K.; Schikora, D.

    2004-03-01

    We investigated the optical properties of CdSe quantum dots (QDs) grown by molecular-beam epitaxy on GaAs substrates using micro-photoluminescence spectroscopy. Comparison was made between the QDs grown on a substrate with a vicinal tilt of 2° in the [111] direction and those on an on-axis substrate. We have studied the evolution of lineshapes of QD photoluminescence spectra under the improved condition of spatial resolution. It was found that the use of a substrate with the vicinal surface leads to the suppression of excitonic PL emitted from a wetting layer. The PL studies revealed that the thermo-stability up to 150 K was obtained in the sample on the on-axis substrate, whereas rapid temperature-induced quenching starting from 6 K was observed in that grown on the vicinal substrate.

  20. Growth dynamic of Naegleria fowleri in a microbial freshwater biofilm.

    Science.gov (United States)

    Goudot, Sébastien; Herbelin, Pascaline; Mathieu, Laurence; Soreau, Sylvie; Banas, Sandrine; Jorand, Frédéric

    2012-09-01

    The presence of pathogenic free-living amoebae (FLA) such as Naegleria fowleri in freshwater environments is a potential public health risk. Although its occurrence in various water sources has been well reported, its presence and associated factors in biofilm remain unknown. In this study, the density of N. fowleri in biofilms spontaneously growing on glass slides fed by raw freshwater were followed at 32 °C and 42 °C for 45 days. The biofilms were collected with their substrata and characterized for their structure, numbered for their bacterial density, thermophilic free-living amoebae, and pathogenic N. fowleri. The cell density of N. fowleri within the biofilms was significantly affected both by the temperature and the nutrient level (bacteria/amoeba ratio). At 32 °C, the density remained constantly low (1-10 N. fowleri/cm(2)) indicating that the amoebae were in a survival state, whereas at 42 °C the density reached 30-900 N. fowleri/cm(2) indicating an active growth phase. The nutrient level, as well, strongly affected the apparent specific growth rate (μ) of N. fowleri in the range of 0.03-0.23 h(-1). At 42 °C a hyperbolic relationship was found between μ and the bacteria/amoeba ratio. A ratio of 10(6) to 10(7) bacteria/amoeba was needed to approach the apparent μ(max) value (0.23 h(-1)). Data analysis also showed that a threshold for the nutrient level of close to 10(4) bacteria/amoeba is needed to detect the growth of N. fowleri in freshwater biofilm. This study emphasizes the important role of the temperature and bacteria as prey to promote not only the growth of N. fowleri, but also its survival. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. DOMESTICATION OF FRESHWATER PUFFER FISH OR BUNTAL (Tetraodon palembangensis

    Directory of Open Access Journals (Sweden)

    I Wayan Subamia

    2008-12-01

    Full Text Available The Research Institute for Freshwater Ornamental Fish Culture has been conducting domestication research since 2004 on adult freshwater puffer fish or buntal broodstock in which the fish were reared in aquaria and fed with small feed fish teri (anchovy and earthworm (Lumbricus sp.. The domestication of freshwater puffer fish or buntal has resulted in successful environmental adaptation and reproductive ability of the fish and further rearing of its fry. The adaptive ability was indicated by its high survival rate, good growth and development, and the reproductive success in spawning, egg production, hatching as well as growing of the larvae to fry stages. The mature gonad stage of the fish was reached at an average body weight of 150 g with a reproductive period of 5 months. The spawning occurred naturally and the eggs were gradually released at interval periods of 14—18 days with egg production rates of 1,000—1,900 eggs per spawning. The highest egg fertilization rate was 96%, with the highest egg hatching rate of 78.6%. Hatching process took place on the 6th to 13th days after spawning process. The surviving larvae began feeding filtered natural foods Moina sp. on the 3rd day up to the 6th day, whereas unfiltered Moina sp. was given from the 7th to 14th days. The fish were fed the live feed Culex sp. from the 15th to 30th days. In the following period the fish was fed earthworm and small feed fish teri (anchovy.

  2. Critically evaluating best management practices for preventing freshwater turtle extinctions.

    Science.gov (United States)

    Spencer, R-J; Van Dyke, J U; Thompson, Michael B

    2017-12-01

    Ex situ conservation tools, such as captive breeding for reintroduction, are considered a last resort to recover threatened or endangered species, but they may also help reduce anthropogenic threats where it is difficult or impossible to address them directly. Headstarting, or captive rearing of eggs or neonate animals for subsequent release into the wild, is controversial because it treats only a symptom of a larger conservation problem; however, it may provide a mechanism to address multiple threats, particularly near population centers. We conducted a population viability analysis of Australia's most widespread freshwater turtle, Chelodina longicollis, to determine the effect of adult roadkill (death by collision with motor vehicles), which is increasing, and reduced recruitment through nest predation from introduced European red foxes (Vulpes vulpes). We also modeled management scenarios to test the effectiveness of headstarting, fox management, and measures to reduce mortality on roads. Only scenarios with headstarting from source populations eliminated all risks of extinction and allowed population growth. Small increases in adult mortality (2%) had the greatest effect on population growth and extinction risk. Where threats simultaneously affected other life-history stages (e.g., recruitment), eliminating harvest pressures on adult females alone did not eliminate the risk of population extinction. In our models, one source population could supply enough hatchlings annually to supplement 25 other similar-sized populations such that extinction was avoided. Based on our results, we believe headstarting should be a primary tool for managing freshwater turtles for which threats affect multiple life-history stages. We advocate the creation of source populations for managing freshwater turtles that are greatly threatened at multiple life-history stages, such as depredation of eggs by invasive species and adult mortality via roadkill. © 2017 Society for Conservation

  3. In-depth tanscriptomic analysis on giant freshwater prawns.

    Directory of Open Access Journals (Sweden)

    Maizatul Izzah Mohd-Shamsudin

    Full Text Available Gene discovery in the Malaysian giant freshwater prawn (Macrobrachium rosenbergii has been limited to small scale data collection, despite great interest in various research fields related to the commercial significance of this species. Next generation sequencing technologies that have been developed recently and enabled whole transcriptome sequencing (RNA-seq, have allowed generation of large scale functional genomics data sets in a shorter time than was previously possible. Using this technology, transcriptome sequencing of three tissue types: hepatopancreas, gill and muscle, has been undertaken to generate functional genomics data for M. rosenbergii at a massive scale. De novo assembly of 75-bp paired end Ilumina reads has generated 102,230 unigenes. Sequence homology search and in silico prediction have identified known and novel protein coding candidate genes (∼24%, non-coding RNA, and repetitive elements in the transcriptome. Potential markers consisting of simple sequence repeats associated with known protein coding genes have been successfully identified. Using KEGG pathway enrichment, differentially expressed genes in different tissues were systematically represented. The functions of gill and hepatopancreas in the context of neuroactive regulation, metabolism, reproduction, environmental stress and disease responses are described and support relevant experimental studies conducted previously in M. rosenbergii and other crustaceans. This large scale gene discovery represents the most extensive transcriptome data for freshwater prawn. Comparison with model organisms has paved the path to address the possible conserved biological entities shared between vertebrates and crustaceans. The functional genomics resources generated from this study provide the basis for constructing hypotheses for future molecular research in the freshwater shrimp.

  4. Upper thermal tolerances of early life stages of freshwater mussels

    Science.gov (United States)

    Pandolfo, Tamara J.; Cope, W. Gregory; Arellano, Consuelo; Bringolf, Robert B.; Barnhart, M. Christopher; Hammer, E

    2010-01-01

    Freshwater mussels (order Unioniformes) fulfill an essential role in benthic aquatic communities, but also are among the most sensitive and rapidly declining faunal groups in North America. Rising water temperatures, caused by global climate change, industrial discharges, drought, or land development, could further challenge imperiled unionid communities. The aim of our study was to determine the upper thermal tolerances of the larval (glochidia) and juvenile life stages of freshwater mussels. Glochidia of 8 species of mussels were tested: Lampsilis siliquoidea, Potamilus alatus, Ligumia recta, Ellipsaria lineolata,Lasmigona complanata, Megalonaias nervosa, Alasmidonta varicosa, and Villosa delumbis. Seven of these species also were tested as juveniles. Survival trends were monitored while mussels held at 3 acclimation temperatures (17, 22, and 27°C) were exposed to a range of common and extreme water temperatures (20–42°C) in standard acute laboratory tests. The average median lethal temperature (LT50) among species in 24-h tests with glochidia was 31.6°C and ranged from 21.4 to 42.7°C. The mean LT50 in 96-h juvenile tests was 34.7°C and ranged from 32.5 to 38.8°C. Based on comparisons of LT50s, thermal tolerances differed among species for glochidia, but not for juveniles. Acclimation temperature did not affect thermal tolerance for either life stage. Our results indicate that freshwater mussels already might be living close to their upper thermal tolerances in some systems and, thus, might be at risk from rising environmental temperatures.

  5. Oxygen Isotope Composition of Nitrate Produced by Freshwater Nitrification

    Science.gov (United States)

    Boshers, D.; Granger, J.; Bohlke, J. K.

    2016-12-01

    Measurements of the naturally occurring nitrogen and oxygen stable isotope ratios of nitrate (NO3-), δ15N and δ18O, can be used to determine the source, dispersal, and fate of natural and contaminant NO3- in aquatic environments. To this end, it is necessary to know the extent to which NO3- isotopologues are modified by biological reactions, as heavy and light isotopes have different reaction rates. The purpose of this study was to determine the influence of the δ18O of ambient water on the isotope composition of NO3- produced during nitrification, the biological oxidation of ammonium (NH4+) to nitrite (NO2-) and then NO3-, which is poorly constrained in freshwater systems. To determine the δ18O of NO3- produced by nitrification in freshwater, we collected water from a stream in New England, which we amended with NH4+ and with increments of 18O-enriched water, to monitor the isotope composition of NO3- produced by a natural consortium of nitrifiers. Added NH4+ was completely oxidized to NO3- over 26 days. The final δ18O of nitrified NO3- revealed sensitivity to the δ18O of water mediated by (a) isotopic equilibration between water and NO2- and (b) kinetic isotope fractionation during O-atom incorporation from water into NO2- and NO3-. Our results concur with nitrifying culture experiments that have demonstrated analogous sensitivity of the δ18O of nitrified NO3- to equilibrium and kinetic O isotope effects (Buchwald et al. 2012), as well as show that these dynamics need to be considered to interpret NO3- isotope distribution in freshwater environments.

  6. Multicriteria Decision Analysis of Freshwater Resource Management in Southwestern Bangladesh

    Science.gov (United States)

    Peters, C.; Baroud, H.; Hornberger, G. M.

    2016-12-01

    Freshwater resources in coastal Bangladesh fluctuate with extreme periods of shortage and abundance. Bangladeshis have adapted to these alternating periods but are still plagued with scarce drinking water resources due to pond water pathogens, salinity of groundwater, and arsenic contamination. The success of attempts to correct the problem of unsafe drinking water have varied across the southern Bangladesh as a result of physical and social factors. We use a multicriteria decision analysis (MCDA) to explore the various physical and social factors that influence decisions about freshwater technologies and management schemes in southern Bangladesh. To determine the best freshwater technologies and management schemes, we examine four alternatives, including managed aquifer recharge (MAR), pond sand filter (PSF), rain water harvesting (RWH), and tubewells (TW). Criteria are grouped into four categories (environmental, technical, social, and economic) and weighting of social factors will be determined by community surveys, non-governmental organizations (NGO) opinions, and academic interviews. Social data include regional water quality perceptions, perceptions of management/technology success, MAR community surveys, and interviews with NGO partners. Environmental and technical feasibility factors are determined from regional water quality data, geospatial information, land use/land change, and regional stratigraphy. Survey data suggest a wide range of criteria based on location and stakeholder perception. MAR and PSF technologies likely have the greatest environmental and technical potential for success but are highly influenced by community dynamics, individual perspective, and NGO involvement. RWH solutions are used frequently and are successful at reducing the water security threats of contamination by pathogens, arsenic, and salts. This MCDA informs us of community and stakeholder water resource decisions, specifically related to their objectives and preferences.

  7. Characteristics of ageostrophic flow in the vicinity of a severe weather outbreak - AVE-SESAME I

    Science.gov (United States)

    Arnold, J. E.

    1982-01-01

    GOES satellite data was used to examine the ageostrophic flow in the vicinity of severe weather outbreaks along the Red River between Texas and Oklahoma in April 1979. The observations were part of the NASA AVE-SESAME I data on atmospheric states close to severe weather conditions. The Barnes Objective Analysis Technique was employed to analyze the data on a 100 km grid. The ageostrophic wind was defined on a regional scale from satellite data on different levels of cloud wind vectors, with a height change signalling a short-wave system in a long-wave trough. The percentage of deviation of the subgeostrophic winds from the geostrophic wind was calculated, and maximum departure corresponded with the region of greatest storm development. Time cross sections of additions to the ageostrophic flow were made as a function of pressure at 100 mb intervals from 900-100 mb. The ageostrophic acceleration was consistently twice the geostrophic acceleration.

  8. New evidence for prehistoric copper metallurgy in the vicinity of Bor

    Directory of Open Access Journals (Sweden)

    Kapuran Aleksandar

    2016-01-01

    Full Text Available The last three years of archaeological investigations at the site Ru`ana in Banjsko Polje, in the immediate vicinity of Bor, have provided new evidence regarding the role of non-ferrous metallurgy in the economy of the prehistoric communities of north-eastern Serbia. The remains of metallurgical furnaces and a large amount of metallic slags at two neighbouring sites in the mentioned settlement reveal that locations with many installations for the thermal processing of copper ore existed in the Bronze Age. We believe, judging by the finds of material culture, that metallurgical activities in this area also continued into the Iron Age and, possibly, into the 4th century AD. [Projekat Ministarstva nauke Republike Srbije, br. 177020: Archaeology of Serbia: Cultural identity, integration factors, technological processes and the role of the central Balkans in the development of European prehistory

  9. Vibrational characterization of different benzene phases on flat and vicinal Si(100) surfaces.

    Science.gov (United States)

    Naydenov, Borislav; Widdra, Wolf

    2007-10-21

    Based on high-resolution electron energy loss spectroscopy and temperature-programmable desorption, benzene chemisorption on vicinal and nominally flat Si(100) surfaces has been studied for various adsorption, annealing, and site blocking treatments. Three different chemisorbed benzene (C6H6 and C6D6) phases with distinct thermal desorption characteristics and different vibrational spectra have been separated and characterized on both substrates. All three phases are identified as 1,4-cyclohexadiene-like structures with butterfly geometry. Whereas the dominant phase is di-sigma bonded to the two Si atoms of a single Si-Si dimer, the benzene orientation (double bond orientation) in the other phases is rotated. Di-sigma bonding to Si atoms of adjacent Si-Si dimer for the latter cases is most likely. Coverage and temperature dependent conversions between the different phases have been addressed by vibrational spectroscopy.

  10. The fauna of small mammals in the vicinity of Temerin, The Vojvodina providence

    Directory of Open Access Journals (Sweden)

    Popović Ester J.

    2006-01-01

    Full Text Available The samples collected by traps in the vicinity of Temerin and the analysis of pellets of the long-eared owl (Asia otus and the barn owl (Tyto alba served as a basis for the determination of 409 individuals of small mammals of the orders Insectivora and Rodentia. A total of 13 species from the families Soricidae (6, Muridae (4 and Arvi-colidae (3 was recorded. The representatives of the species Apodemus sylvaticus prevailed in the sample obtained by traps while the pellet analysis showed the domination of Micro-tus arvalis in the owl diet. The presence of five of the total of thirteen species found by the pellet analysis was confirmed by means of traps.

  11. A floristic survey of Yucca Mountain and vicinity, Nye County, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Niles, W.E.; Leary, P.J.; Holland, J.S.; Landau, F.H.

    1995-12-01

    A survey of the vascular flora of Yucca Mountain and vicinity, Nye County, Nevada, was conducted from March to June 1994, and from March to October 1995. An annotated checklist of recorded taxa was compiled. Voucher plant specimens were collected and accessioned into the Herbarium at the University of Nevada, Las Vegas. Collection data accompanying these specimens were entered into that herbarium`s electronic data base. Combined results from this survey and the works of other investigators reveal the presence of a total of 375 specific and intraspecific taxa within the area these allocated to 179 genera and 54 families. No taxon currently listed as threatened or endangered under the Endangered Species Act was encountered during this study. Several candidate species for listing under this Act were present, and distributional data for these were recorded. No change in the status of these candidate species is recommended as the result of this study.

  12. Monitoring of radionuclides in the vicinities of Finnish nuclear power plants in 1993 and 1994

    Energy Technology Data Exchange (ETDEWEB)

    Klemola, S.; Ilus, E.; Ikaeheimonen, T.K

    1998-08-01

    Monitoring of radioactive substances around Finnish nuclear power plants continued in 1993-1994 in accordance with the regular programmes. Some 1000 samples are analysed annually from the terrestrial and aquatic environments of the two power plant sites. Trace amounts of activation products originating from airborne releases from the local power plants were detected in several air, deposition and soil samples. Discharged nuclides were more abundant in the aquatic environment, especially in samples of indicator organisms, sinking matter and sediments. However, the concentrations were so low that they did not significantly increase the radiation burden in the environment. The dominant artificial radionuclides in the vicinity of the power plants remained the cesium isotopes, especially {sup 137}Cs but also {sup 134}Cs, originating from the Chernobyl accident. (orig.) 14 refs.

  13. Optical characterization of gold chains and steps on the vicinal Si(557) surface: Theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Hogan, Conor [Consiglio Nazionale delle Ricerche, Istituto di Struttura della Materia, via Fosso del Cavaliere 100, 00133 Rome (Italy); Department of Physics and European Theoretical Spectroscopy Facility (ETSF), University of Rome ' ' Tor Vergata' ' , Via della Ricerca Scientifica 1, 00133 Rome (Italy); McAlinden, Niall; McGilp, John F. [School of Physics, Trinity College Dublin, Dublin 2 (Ireland)

    2012-06-15

    We present a joint experimental-theoretical study of the reflectance anisotropy of clean and gold-covered Si(557), a vicinal surface of Si(111) upon which gold forms quasi-one-dimensional (1D) chains parallel to the steps. By means of first-principles calculations, we analyse the close relationship between the various surface structural motifs and the optical properties. Good agreement is found between experimental and computed spectra of single-step models of both clean and Au-adsorbed surfaces. Spectral fingerprints of monoatomic gold chains and silicon step edges are identified. The role of spin-orbit coupling (SOC) on the surface optical properties is examined, and found to have little effect. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Water quality in the vicinity of Fenton Hill: Progress report, 1983 and 1984

    Energy Technology Data Exchange (ETDEWEB)

    Purtymun, W.D.; Ferenbaugh, R.W.; Becker, N.M.; Williams, M.C.; Maes, M.

    1987-01-01

    Water quality data have been collected since 1974 from established surface and groundwater stations at and in the vicinity of Fenton Hill (Hot Dry Rock Geothermal Demonstration Site) located in the Jemez Mountains. This is part of a continued program of environmental studies. There has been a slight variation in chemical quality of water from the surface and groundwater stations; however, these variations are within normal seasonal fluctuations. Water supply at the site is pumped from the aquifer in the Abiquiu Tuff. Cumulative production from 1976 through 1984 has been 41.5 x 10/sup 6/ gal. The water level in the supply well declined from 365 ft in 1976 to 379 ft in 1984.

  15. DFT study of the molybdenum-catalyzed deoxydehydration of vicinal diols.

    Science.gov (United States)

    Lupp, Daniel; Christensen, Niels Johan; Dethlefsen, Johannes R; Fristrup, Peter

    2015-02-16

    The mechanism of the molybdenum-catalyzed deoxydehydration (DODH) of vicinal diols has been investigated using density functional theory. The proposed catalytic cycle involves condensation of the diol with an Mo(VI) oxo complex, oxidative cleavage of the diol resulting in an Mo(IV) complex, and extrusion of the alkene. We have compared the proposed pathway with several alternatives, and the results have been corroborated by comparison with the molybdenum-catalyzed sulfoxide reduction recently published by Sanz et al. and with experimental observations for the DODH itself. Improved understanding of the mechanism should expedite future optimization of molybdenum-catalyzed biomass transformations. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Surface-Step-Induced Double Magnetic Switching of Fe on Vicinal W(100)

    Energy Technology Data Exchange (ETDEWEB)

    Mireles, Hector C.; Erskine, J. L.

    2001-07-16

    Two-level magnetic switching of a bilayer epitaxial Fe film grown on a graded stepped W(100) surface is observed using the magneto-optic Kerr effect. Hysteresis loops produced by the film at a location on the curved W(100) surface corresponding to a vicinal angle of 6.4{sup o} exhibit two abrupt jumps in magnetization following spin orientation perpendicular to the steps resulting from surface-step-induced anisotropy. The two-step process can be understood in terms of abrupt depinning of spins in two inequivalent microdomains associated with the stepped surface. The results suggest a new realm of ultrathin film micromagnetics in which characteristic dimensions of 20--30{angstrom} can play a dominant role.

  17. Surface-step-induced double magnetic switching of Fe on vicinal W(100).

    Science.gov (United States)

    Mireles, H C; Erskine, J L

    2001-07-16

    Two-level magnetic switching of a bilayer epitaxial Fe film grown on a graded stepped W(100) surface is observed using the magneto-optic Kerr effect. Hysteresis loops produced by the film at a location on the curved W(100) surface corresponding to a vicinal angle of 6.4 degrees exhibit two abrupt jumps in magnetization following spin orientation perpendicular to the steps resulting from surface-step-induced anisotropy. The two-step process can be understood in terms of abrupt depinning of spins in two inequivalent microdomains associated with the stepped surface. The results suggest a new realm of ultrathin film micromagnetics in which characteristic dimensions of 20-30 A can play a dominant role.

  18. Indoor Rn-222 concentrations in the vicinity of a Turkish coal-fired power plant

    Energy Technology Data Exchange (ETDEWEB)

    Yaprak, G. [Ege University, Izmir (Turkey). Inst. of Nuclear Science

    1999-10-01

    Coal, like most materials found in nature, contains natural radionuclides and their products in small quantities. Therefore, depending on their concentration in the coal, a coal-fired power plant might potentially contaminate the environment. Indoor Rn-222 concentration in 100 houses located in the vicinity of Yatagan coal-fired power plant in the southwestern part of Turkey were measured using solid state nuclear track detectors. The time-integrated Rn-222 concentrations in the houses ranged from 10 to 120 Bq m{sup -3}. This corresponds to an annual effective dose equivalent ranging from 0.6 to 7/3 mSv. In 96% of the homes, an Rn-222 concentration of 100 Bq m{sup -3} (taken as the limit for future buildings, recommended by ICRP) was not exceeded.

  19. Surface plasmon resonance on vicinity of gold-coated fiber tip

    Energy Technology Data Exchange (ETDEWEB)

    Abrahamyan, T. [Department of Radio Physics, Yerevan State University (Armenia); Nerkararyan, Kh. [Department of Radio Physics, Yerevan State University (Armenia)]. E-mail: knerkar@ysu.am

    2007-05-14

    The possibility of excitation of Surface Plasmon Polaritons (SPP) in the vicinity of the tip of a gold covered optical fiber is investigated when the tip is in the medium with a certain dielectric permittivity. In the experiment the medium was a solution consisting of dimethyl sulfoxide and ethanol liquids in which, as a result of evaporation, a smooth changing of the dielectric permittivity of the solution was taking place. During the evaporation a peak of the power of output radiation was observed from the tip of the fiber, which is explained by the resonant excitation of SPP. This mechanism of SPP excitation in the region of the tip of the optical waveguide opens up new possibilities for increasing the resolution of the nanometric scanning optical microscope and for creation of a new type of optochemical fiber sensors.

  20. Spatial distribution of marine crenarchaeota group I in the vicinity of deep-sea hydrothermal systems.

    Science.gov (United States)

    Takai, Ken; Oida, Hanako; Suzuki, Yohey; Hirayama, Hisako; Nakagawa, Satoshi; Nunoura, Takuro; Inagaki, Fumio; Nealson, Kenneth H; Horikoshi, Koki

    2004-04-01

    Distribution profiles of marine crenarchaeota group I in the vicinity of deep-sea hydrothermal systems were mapped with culture-independent molecular techniques. Planktonic samples were obtained from the waters surrounding two geographically and geologically distinct hydrothermal systems, and the abundance of marine crenarchaeota group I was examined by 16S ribosomal DNA clone analysis, quantitative PCR, and whole-cell fluorescence in situ hybridization. A much higher proportion of marine crenarchaeota group I within the microbial community was detected in deep-sea hydrothermal environments than in normal deep and surface seawaters. The highest proportion was always obtained from the ambient seawater adjacent to hydrothermal emissions and chimneys but not from the hydrothermal plumes. These profiles were markedly different from the profiles of epsilon-Proteobacteria, which are abundant in the low temperatures of deep-sea hydrothermal environments.

  1. Vinča-Belo Brdo: Vernissages of eneolithic belgrade and its vicinity I

    Directory of Open Access Journals (Sweden)

    Spasić Miloš

    2009-01-01

    Full Text Available The following paper will discuss the problems of Eneolithic settlements of Baden and Kostolac culture at Vinča near Belgrade. Eneolithic horizons from Vinča site were scarcely published owing to the fact that both Baden and Kostolac layers are not well stratified because of heavy medieval devastations. In spite of all post-depositional destructions Eneolithic settlements at Vinča show enormous significance for understanding the life of the period, both on the micro and macro-regional scale. At the same time, this work is a sort of an insight into the results of ongoing analysis of material culture and socio-economic patterns of Eneolithic period settlements in Belgrade and its vicinity.

  2. Nanostructured sapphire vicinal surfaces as templates for the growth of self-organized oxide nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Thune, E., E-mail: elsa.thune@unilim.fr [Laboratoire Sciences des Procedes Ceramiques et de Traitements de Surface (SPCTS), UMR CNRS 6638, ENSCI, 47-73 Avenue Albert Thomas, F-87065 Limoges Cedex (France); Boulle, A. [Laboratoire Sciences des Procedes Ceramiques et de Traitements de Surface (SPCTS), UMR CNRS 6638, ENSCI, 47-73 Avenue Albert Thomas, F-87065 Limoges Cedex (France); Babonneau, D.; Pailloux, F. [Laboratoire de Physique des Materiaux (PHYMAT), UMR CNRS 6630, Universite de Poitiers, Boulevard Marie et Pierre Curie - Teleport 2, BP 30179, F-86962 Futuroscope - Chasseneuil Cedex (France); Hamd, W.; Guinebretiere, R. [Laboratoire Sciences des Procedes Ceramiques et de Traitements de Surface (SPCTS), UMR CNRS 6638, ENSCI, 47-73 Avenue Albert Thomas, F-87065 Limoges Cedex (France)

    2009-11-15

    Vicinal substrates of sapphire with miscut angle of 10 deg. from the (0 0 1) planes towards the [1 1 0] direction have been annealed in air in the range from 1000 to 1500 deg. C. The behaviour of these surfaces has been characterized as a function of the temperature and the thermal treatment time by Atomic Force Microscopy observations. A thermal treatment at 1250 deg. C allows to stabilize a surface made of periodically spaced nanosized step-bunches. Such stepped surfaces were used as template to grow self-patterned epitaxial oxide nanoparticles by thermal annealing of yttria-stabilized zirconia thin films produced by sol-gel dip-coating. Grazing Incidence Small Angle X-ray Scattering and High-Resolution Transmission Electron Microscopy were used to study the morphology of the nanoparticles and their epitaxial relationships with the substrate.

  3. Wavepacket dynamics in the scattering of hydrogen anions off vicinally nano-stepped metal surfaces

    Science.gov (United States)

    Shaw, John; Chakraborty, Himadri; Monismith, David

    2017-04-01

    We study the electron dynamics in monocrystalline Cu, Au and Pd surfaces with stepped vicinal structures modeled in a Kronig-Penney scheme. The unoccupied bands of the surface is resonantly excited via the charge transfer interaction of the surface with a moving hydrogen anion. The interaction dynamics are simulated in a quantum mechanical wavepacket propagation approach that used parallel computations. The survival probability of the interacting ion is calculated as well as the electron probability density at all times during the interaction. Animated videos are produced of the electron probability density which show that, when the electron is transferred to the metal, the first two image states are the most likely locations of the electron as it evolves through the superlattice. The survival probability shows peaks at those energies that produce standing waves between the steps on the surface when the electron is in the image state subbands. The work is supported by the XSEDE allocation Grant for high performance computation.

  4. Environmental Impact Research Program. An Instruction Report on Freshwater Mussels.

    Science.gov (United States)

    1983-09-01

    freshwater mussels in soft substrates. This dredge or basket sampler can be constructed from bamboo and is stil I used in the 3-10 Orient to collect...handle) is secured in two places to the iron frame with heavy twine. Heavy rods are attached to the base (0.3 cm in diameter) as well as to the back and...sides (0.1-5 cm). The rods on the base, sides, and back are about 1.0 cmn apart and are secured to the iron frame with three sizes of wire: No. 20, No

  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. Collating data for freshwater biodiversity planning in South Africa

    CSIR Research Space (South Africa)

    Petersen, C

    2010-03-01

    Full Text Available Introduction box4 National Freshwater Ecosystem Priority Areas (NFEPA) Project started in 2008 box4 NFEPA is supported by SANBI, CSIR, DWAF, WRC and WWF South Africa, SANParks, SAIAB) and DEAT. box4 The aims of NFEPA are: square6 To identify a national... engaging with key stakeholders and through pilot projects box4 Focus will be on the input data layers and methods used in collation thereof Rivers box4 DWAF’s Present Ecological State (PES) (1999) box4 6 categories e.g. A category = natural, while D...

  7. Helminth parasites of freshwater fishes, Nazas River basin, northern Mexico

    Directory of Open Access Journals (Sweden)

    León, G. Pérez-Ponce

    2010-01-01

    Full Text Available This paper represents the first study of the helminth parasites of freshwater fishes from the Nazas River basinin northern Mexico. Between July 2005 and December 2008, 906 individual fish were collected and examined for helminthparasites in 23 localities along the river basin. Twenty-three species of fish were examined as a part of this inventory work.In total, 41 helminth species were identified: 19 monogeneans, 10 digeneans, seven cestodes, one acanthocephalan, andfour nematodes. The biogeographical implications of our findings are briefly discussed.

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

    Directory of Open Access Journals (Sweden)

    M. Heistermann

    2017-07-01

    Full Text Available 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

  9. Characterization of geologic deposits in the vicinity of US Ecology, Amargosa Basin, southern Nevada

    Science.gov (United States)

    Taylor, Emily M.

    2010-01-01

    Multiple approaches have been applied to better understand the characteristics of geologic units exposed at the surface and buried at depth in the vicinity of US Ecology (USE), a low-level commercial waste site in the northern Amargosa Desert, Nevada. Techniques include surficial geologic mapping and interpretation of the subsurface using borehole data. Dated deposits at depth were used to estimate rates of sediment accumulation. The subsurface lithologies have been modeled in three dimensions. Lithologic cross sections have been created from the three-dimensional model and have been compared to resistivity data at the same location. Where deposits appear offset, a fault was suspected. Global Positioning System elevation transects were measured and trenches were excavated to locate a strand of the Carrara Fault. The presence of the fault helps to better understand the shape of the potentiometric surface. These data will be used to better understand the hydrologic parameters controlling the containment of the waste at US Ecology.Quaternary geologic units exposed at the surface, in the vicinity of US Ecology, are derived from the alluvium shed off the adjacent range front and the Amargosa River. These deposits vary from modern to early Pleistocene in age. At depth, heterogeneous sands and gravel occur. Observed in deep trenches and boreholes, the subsurface deposits are characterized as fining-upward sequence of sediment from 5- to 8-meters thick. No volcanic units or fine-grained playa deposits were described in the boreholes to a depth of 200 meters. Based on Infrared Stimulated Luminescence dated core samples, short-term rates of sediment accumulation (Ecology successfully exposed offset Quaternary deposits on a splay of the Carrara Fault. Holocene deposits do not appear to be faulted, however, a fault zone does intersect middle and late Pleistocene aged units.

  10. Paleohydrologic investigations in the vicinity of Yucca Mountain: Late Quaternary paleobotanical and polynological records

    Energy Technology Data Exchange (ETDEWEB)

    Spaulding, W.G.

    1994-10-05

    The primary objective of this research in the vicinity of the proposed Yucca Mountain Nuclear Waste Repository is the detection of episodes of increased runoff and groundwater discharge in this presently arid area. Ancient, inactive spring deposits in nearby valley bottoms (Haynes, 1967; Quade, 1986; Quade and Pratt, 1989), evidence for perennial water in presently dry canyons (Spaulding, 1992), and recent claims for extraordinary increases in precipitation during the last glacial age (Forester, 1994), provide good reason to further investigate both lowland spring-discharge habitats, and upland drainages. The ultimate purpose is to assess the long-term variability of the hydrologic system in the vicinity of Yucca Mountain in response to naturally occurring climatic changes. The data generated in the course of this study are derived from radiocarbon dated packrat (Neotoma) middens. This report presents the results of an initial assessment of the hydrologic stability of the candidate area based on a limited suite of middens from localities that, on geomorphic and hydrologic grounds, could have been close to ancient stream-side or spring environments. Paleoclimatic reconstructions are another means of studying the long-term climatic hydrologic stability of the Candidate Area include, and are also generated from packrat midden data. A different flora characterized the Candidate Area during the last glacial age in response to a cooler and wetter climate, and the plant species that comprised this flora can be used to reconstruct specific components of past climatic regimes. Thus, a secondary objective of this study is to compare the plant macrofossil data generated in this study to other records from the Candidate Area (Spaulding, 1985; Wigand, 1990) to determine if these new data are consistent with prior reconstructions. 66 refs., 4 figs., 13 tabs.

  11. Step density waves on growing vicinal crystal surfaces - Theory and experiment

    Science.gov (United States)

    Ranguelov, Bogdan; Müller, Pierre; Metois, Jean-Jacques; Stoyanov, Stoyan

    2017-01-01

    The Burton, Cabrera and Frank (BCF) theory plays a key conceptual role in understanding and modeling the crystal growth of vicinal surfaces. In BCF theory the adatom concentration on a vicinal surface obeys to a diffusion equation, generally solved within quasi-static approximation where the adatom concentration at a given distance x from a step has a steady state value n (x) . Recently, we show that going beyond this approximation (Ranguelov and Stoyanov, 2007) [6], for fast surface diffusion and slow attachment/detachment kinetics of adatoms at the steps, a train of fast-moving steps is unstable against the formation of steps density waves. More precisely, the step density waves are generated if the step velocity exceeds a critical value related to the strength of the step-step repulsion. This theoretical treatment corresponds to the case when the time to reach a steady state concentration of adatoms on a given terrace is comparable to the time for a non-negligible change of the step configuration leading to a terrace adatom concentration n (x , t) that depends not only on the terrace width, but also on its "past width". This formation of step density waves originates from the high velocity of step motion and has nothing to do with usual kinetic instabilities of step bunching induced by Ehrlich-Schwoebel effect, surface electromigration and/or the impact of impurities on the step rate. The so-predicted formation of step density waves is illustrated by numerical integration of the equations for step motion. In order to complete our previous theoretical treatment of the non-stationary BCF problem, we perform an in-situ reflection electron microscopy experiment at specific temperature interval and direction of the heating current, in which, for the first time, the step density waves instability is evidenced on Si(111) surface during highest possible Si adatoms deposition rates.

  12. Visual impairment and blindness among the students of blind schools in Allahabad and its vicinity: A causal assessment

    OpenAIRE

    Sushank Ashok Bhalerao; Mahesh Tandon; Satyaprakash Singh; Shraddha Dwivedi; Santosh Kumar; Jagriti Rana

    2015-01-01

    Background/Aims: Information on eye diseases in blind school children in Allahabad is rare and sketchy. A cross-sectional study was performed to identify causes of blindness (BL) in blind school children with an aim to gather information on ocular morbidity in the blind schools in Allahabad and in its vicinity. Study Design and Setting: A cross-sectional study was carried out in all the four blind schools in Allahabad and its vicinity. Materials and Methods: The students in the blind schools ...

  13. Influence of vicinal sapphire substrate on the properties of N-polar GaN films grown by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zhiyu; Zhang, Jincheng, E-mail: jchzhang@xidian.edu.cn; Xu, Shengrui; Chen, Zhibin; Yang, Shuangyong; Tian, Kun; Hao, Yue [Key Lab of Wide Band-Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi' an, Shaanxi 710071 (China); Su, Xujun [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou, Jiangsu 215123 (China); Shi, Xuefang [School of Advanced Materials and Nanotechnology, Xidian University, Xi' an, Shaanxi 710071 (China)

    2014-08-25

    The influence of vicinal sapphire substrates on the growth of N-polar GaN films by metal-organic chemical vapor deposition is investigated. Smooth GaN films without hexagonal surface feature are obtained on vicinal substrate. Transmission electron microscope results reveal that basal-plane stacking faults are formed in GaN on vicinal substrate, leading to a reduction in threading dislocation density. Furthermore, it has been found that there is a weaker yellow luminescence in GaN on vicinal substrate than that on (0001) substrate, which might be explained by the different trends of the carbon impurity incorporation.

  14. Gulf-Wide Information System, Environmental Sensitivity Index Freshwater Fish Database, Geographic NAD83, LDWF (2001) [esi_freshwater_fish_LDWF_2001

    Data.gov (United States)

    Louisiana Geographic Information Center — This data set contains sensitive biological resource data for freshwater (inland) fish species in coastal Louisiana. Vector polygons represent water-bodies and other...

  15. Assessing environmental DNA detection in controlled lentic systems.

    Directory of Open Access Journals (Sweden)

    Gregory R Moyer

    Full Text Available Little consideration has been given to environmental DNA (eDNA sampling strategies for rare species. The certainty of species detection relies on understanding false positive and false negative error rates. We used artificial ponds together with logistic regression models to assess the detection of African jewelfish eDNA at varying fish densities (0, 0.32, 1.75, and 5.25 fish/m3. Our objectives were to determine the most effective water stratum for eDNA detection, estimate true and false positive eDNA detection rates, and assess the number of water samples necessary to minimize the risk of false negatives. There were 28 eDNA detections in 324, 1-L, water samples collected from four experimental ponds. The best-approximating model indicated that the per-L-sample probability of eDNA detection was 4.86 times more likely for every 2.53 fish/m3 (1 SD increase in fish density and 1.67 times less likely for every 1.02 C (1 SD increase in water temperature. The best section of the water column to detect eDNA was the surface and to a lesser extent the bottom. Although no false positives were detected, the estimated likely number of false positives in samples from ponds that contained fish averaged 3.62. At high densities of African jewelfish, 3-5 L of water provided a >95% probability for the presence/absence of its eDNA. Conversely, at moderate and low densities, the number of water samples necessary to achieve a >95% probability of eDNA detection approximated 42-73 and >100 L, respectively. Potential biases associated with incomplete detection of eDNA could be alleviated via formal estimation of eDNA detection probabilities under an occupancy modeling framework; alternatively, the filtration of hundreds of liters of water may be required to achieve a high (e.g., 95% level of certainty that African jewelfish eDNA will be detected at low densities (i.e., <0.32 fish/m3 or 1.75 g/m3.

  16. SOIL CARBON SEQUESTRATION IN COASTAL FRESHWATER WETLANDS OF VERACRUZ

    Directory of Open Access Journals (Sweden)

    José Luis Marín-Muñiz

    2011-11-01

    Full Text Available Wetlands play an important role in the global carbon (C cycle because they act as sinks of this element. Vegetation in the wetlands is a factor that influences C storage in these ecosystems. We investigated C storage in freshwater wetland soils with different types of vegetation (swamps and marshes in the coastal plain of Veracruz, Mexico. The study sites were: Estero Dulce (ED, Tecolutla and Laguna Chica (LCH, Vega de Alatorre. Bulk densities observed ranged from 0.1 to 1.15 g cm3. Average C stored in LCH was higher in swamp (13.30±0.11 % than in marsh soils (4.52±0.02 %. However, in ED the C content was similar in swamp (5.88±0.03 % and marsh soils (5.28±0.02 %. In LCH marshes, there was approximately 50 % less total C in the soil compared to the C content in the swamps. In ED, the C stored in the marshes was only 7.15 % lower than the C stored in the swamps. When the total C storage of freshwater swamps (35.04±4.0 kg cm-2 and marshes (24.8±4.0 kg cm-2 was compared, there was no effect caused by the type of vegetation (P = 0.213.

  17. Development of intermediate foodstuff derived from freshwater fish in China

    Science.gov (United States)

    Wang, Xichang; Fukuda, Yutaka; Chen, Shunsheng; Yokoyama, Masahito; Cheng, Yudong; Yuan, Chunhong; Qu, Yinghong; Sakaguchi, Morihiko

    2005-07-01

    According to the three-dimensional contour maps showing the gel-forming properties of surimi derived from freshwater fish, 8 species of surimi were classified into two types. The V-valley type surimi (silver carp, big-head carp, Chinese snake head and blunt snout bream) shows easy setting, low resistance to gel collapse, high enhancement ability with two-step heating, and narrow optimum heating temperature and time area, which are of the same characteristics as the wall-eye pollack surimi. In contrast, the Plateau type surimi (tilapia, grass carp, mud carp and common carp) exhibits difficult setting, high resistance to gel collapse, no enhancement ability with two-step heating, and wide optimum heating temperature and time area. There are seasonal changes of gelling properties of silver carp surimi, and the setting ability of surimi gel is higher in winter and lower in summer. The marine fish meat gels and the freshwater fish meat gels have the same acceptability for inland Chinese according to the sensory evaluation results. A slight increase in sensory scorings of kamaboko gels occurred when the extract from walleye pollack muscle was added, especially in the odor scoring of silver carp kamaboko gels.

  18. Predation of freshwater fish in environments with elevated carbon dioxide

    Science.gov (United States)

    Midway, Stephen R.; Hasler, Caleb T.; Wagner, Tyler; Suski, Cory D.

    2017-01-01

    Carbon dioxide (CO2) in fresh-water environments is poorly understood, yet in marine environments CO2 can affect fish behaviour, including predator–prey relationships. To examine changes in predator success in elevated CO2, we experimented with predatory Micropterus salmoides and Pimephales promelas prey. We used a two-factor fully crossed experimental design; one factor was 4-day (acclimation) CO2 concentration and the second factor CO2 concentration during 20-min predation experiments. Both factors had three treatment levels, including ambient partial pressure of CO2(pCO2; 0–1000 μatm), low pCO2 (4000–5000 μatm) and high pCO2 (8000–10 000 μatm). Micropterus salmoides was exposed to both factors, whereas P. promelas was not exposed to the acclimation factor. In total, 83 of the 96 P. promelas were consumed (n = 96 trials) and we saw no discernible effect of CO2 on predator success or time to predation. Failed strikes and time between failed strikes were too infrequent to model. Compared with marine systems, our findings are unique in that we not only saw no changes in prey capture success with increasing CO2, but we also used CO2 treatments that were substantially higher than those in past experiments. Our work demonstrated a pronounced resiliency of freshwater predators to elevated CO2 exposure, and a starting point for future work in this area.

  19. Competition and niche separation of pelagic bacteria in freshwater habitats.

    Science.gov (United States)

    Pernthaler, Jakob

    2017-06-01

    Freshwater bacterioplankton assemblages are composed of sympatric populations that can be delineated, for example, by ribosomal RNA gene relatedness and that differ in key ecophysiological properties. They may be free-living or attached, specialized for particular concentrations or subsets of substrates, or invest a variable amount of their resources in defence traits against protistan predators and viruses. Some may be motile and tactic whereas others are not, with far-reaching implications for their respective life styles and niche partitioning. The co-occurrence of competitors with overlapping growth requirements has profound consequences for the stability of community functions; it can to some extent be explained by habitat factors such as the microscale complexity and spatiotemporal variability of the lacustrine environments. On the other hand, the composition and diversity of freshwater microbial assemblages also reflects non-equilibrium states, dispersal and the stochasticity of community assembly processes. This review synoptically discusses the competition and niche separation of heterotrophic bacterial populations (defined at various levels of phylogenetic resolution) in the pelagic zone of inland surface waters from a variety of angles, focusing on habitat heterogeneity and the resulting biogeographic distribution patterns, the ecophysiological adaptations to the substrate field and the interactions of prokaryotes with predators and viruses. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  20. Molecular diversity of avian schistosomes in Danish freshwater snails.

    Science.gov (United States)

    Christiansen, Anne Ø; Olsen, Annette; Buchmann, Kurt; Kania, Per W; Nejsum, Peter; Vennervald, Birgitte J

    2016-03-01

    Avian schistosomes are widespread parasites of snails and waterfowl and may cause cercarial dermatitis (swimmer's itch) in humans, a disease that is frequently reported in European countries. These parasites are known to occur in Denmark, but here, we applied a new approach using molecular tools to identify the parasites at species level. In order to do that, 499 pulmonate freshwater snails (Radix sp., Lymnaea stagnalis, Stagnicola sp. and Planorbarius corneus) were sampled from 12 lakes, ponds, and marshes in the greater Copenhagen area. Avian schistosome cercariae were identified by microscopy and subjected to molecular investigation by sequencing and phylogenetic analysis of the 5.8S and ITS2 ribosomal DNA for species identification. Additionally, snail hosts belonging to the genus Radix were identified by sequencing and phylogenetic analysis of partial ITS2 ribosomal DNA. Three out of 499 snails shed different species of Trichobilharzia cercariae: Trichobilharzia szidati was isolated from L. stagnalis, Trichobilharzia franki from Radix auricularia and Trichobilharzia regenti from Radix peregra. In the light of the public health risk represented by bird schistosomes, these findings are of concern and, particularly, the presence of the potentially neuro-pathogenic species, T. regenti, in Danish freshwaters calls for attention.

  1. Temporal Variability of Microplastic Concentrations in Freshwater Streams

    Science.gov (United States)

    Watkins, L.; Walter, M. T.

    2016-12-01

    Plastic pollution, specifically the size fraction less than 5mm known as microplastics, is an emerging contaminant in waterways worldwide. The ability of microplastics to adsorb and transport contaminants and microbes, as well as be ingested by organisms, makes them a concern in both freshwater and marine ecosystems. Recent efforts to determine the extent of microplastic pollution are increasingly focused on freshwater systems, but most studies have reported concentrations at a single time-point; few have begun to uncover how plastic concentrations in riverine systems may change through time. We hypothesize the time of day and season of sampling influences the concentrations of microplastics in water samples and more specifically, that daytime stormflow samples contain the highest microplastic concentrations due to maximized runoff and wastewater discharge. In order to test this hypothesis, we sampled in two similar streams in Ithaca, New York using a 333µm mesh net deployed within the thalweg. Repeat samples were collected to identify diurnal patterns as well as monthly variation. Samples were processed in the laboratory following the NOAA wet peroxide oxidation protocol. This work improves our ability to interpret existing single-time-point survey results by providing information on how microplastic concentrations change over time and whether concentrations in existing stream studies are likely representative of their location. Additionally, these results will inform future studies by providing insight into representative sample timing and capturing temporal trends for the purposes of modeling and of developing regulations for microplastic pollution.

  2. Diversity of methanogenic archaea in freshwater sediments of lacustrine ecosystems.

    Science.gov (United States)

    Laskar, Folguni; Das Purkayastha, Sumi; Sen, Aniruddha; Bhattacharya, Mrinal K; Misra, Biswapriya B

    2017-10-30

    About half of the global methane (CH4 ) emission is contributed by the methanogenic archaeal communities leading to a significant increase in global warming. This unprecedented situation has increased the ever growing necessity of evaluating the control measures for limiting CH4 emission to the atmosphere. Unfortunately, research endeavors on the diversity and functional interactions of methanogens are not extensive till date. We anticipate that the study of the diversity of methanogenic community is paramount for understanding the metabolic processes in freshwater lake ecosystems. Although there are several disadvantages of conventional culture-based methods for determining the diversity of methanogenic archaeal communities, in order to understand their ecological roles in natural environments it is required to culture the microbes. Recently different molecular techniques have been developed for determining the structure of methanogenic archaeal communities thriving in freshwater lake ecosystem. The two gene based cloning techniques required for this purpose are 16S rRNA and methyl coenzyme M reductase (mcrA) in addition to the recently developed metagenomics approaches and high throughput next generation sequencing efforts. This review discusses the various methods of culture-dependent and -independent measures of determining the diversity of methanogen communities in lake sediments in lieu of the different molecular approaches and inter-relationships of diversity of methanogenic archaea. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Remobilisation of uranium from contaminated freshwater sediments by bioturbation

    Science.gov (United States)

    Lagauzère, S.; Motelica-Heino, M.; Viollier, E.; Stora, G.; Bonzom, J. M.

    2014-06-01

    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.

  4. RESEARCH METHODOLOGY ON NATURAL NUTRITION OF FRESH-WATER FISH

    Directory of Open Access Journals (Sweden)

    Marina Piria

    2001-03-01

    Full Text Available This paper offers the entire review on the research methodology in natural nutrition of fresh-water fish. The data on fresh-water fish nutrition, particularly on fish of lower economic value, is inadequate. Reviewing the literature on assesment of nutritional parameters, the authors obviously use differenet approaches and methods. This paper is about most frequently used parameteres in qualitative and quantitative analysis. The qualitative analysis of food structure is the overall list of determinable taxa (mostlyu species and genera. The quantitative analysis comprises the assessment of particular nutritional categories by nutritional indices and coefficients. Bio-identification and numeric data processing can have numerous drawbacsk such as effect of regurgitation or the degree of digestion of the prey. The analyses of those effects proceed through statistical data processing in order to include spatial distribution of certain prey categories as well. The importance of this data is to determine the nutritional needs of potential species for culture as well as to come up with new insights on a particular aquatic ecosystem.

  5. 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.

  6. Toxicity of Metals to a Freshwater Snail, Melanoides tuberculata

    Directory of Open Access Journals (Sweden)

    M. Shuhaimi-Othman

    2012-01-01

    Full Text Available Adult freshwater snails Melanoides tuberculata (Gastropod, Thiaridae 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. The LC50 values for the 96-hour exposures to Cu, Cd, Zn, Pb, Ni, Fe, Al, and Mn were 0.14, 1.49, 3.90, 6.82, 8.46, 8.49, 68.23, and 45.59 mg L−1, respectively. Cu was the most toxic metal to M. tuberculata, followed by Cd, Zn, Pb, Ni, Fe, Mn, and Al (Cu > Cd > Zn > Pb > Ni > Fe > Mn > Al. Metals bioconcentration in M. tuberculata increases with exposure to increasing concentrations and Cu has the highest accumulation (concentration factor in the soft tissues. A comparison of LC50 values for metals for this species with those for other freshwater gastropods reveals that M. tuberculata is equally sensitive to metals.

  7. Quantifying Greenland freshwater flux underestimates in climate models

    Science.gov (United States)

    Little, Christopher M.; Piecuch, Christopher G.; Chaudhuri, Ayan H.

    2016-05-01

    Key processes regulating the mass balance of the Greenland Ice Sheet (GIS) are not represented in current-generation climate models. Here using output from 19 different climate models forced with a high-end business-as-usual emissions pathway, we compare modeled freshwater fluxes (FWF) to a parameterization based on midtropospheric temperature. By the mid 21st century, parameterized GIS FWF is 478 ± 215 km3 yr-1 larger than modeled—over 3 times the 1992-2011 rate of GIS mass loss. By the late 21st century, ensemble mean parameterized GIS FWF anomalies are comparable to FWF anomalies over the northern North Atlantic Ocean, equivalent to approximately 11 cm of global mean sea level rise. The magnitude and spread of these underestimates underscores the need for assessments of the coupled response of the ocean to increased FWF that recognize: (1) the widely varying freshwater budgets of each model and (2) uncertainty in the relationship between GIS FWF and atmospheric temperature.

  8. Arctic freshwater forcing of the Younger Dryas cold reversal.

    Science.gov (United States)

    Tarasov, Lev; Peltier, W R

    2005-06-02

    The last deglaciation was abruptly interrupted by a millennial-scale reversal to glacial conditions, the Younger Dryas cold event. This cold interval has been connected to a decrease in the rate of North Atlantic Deep Water formation and to a resulting weakening of the meridional overturning circulation owing to surface water freshening. In contrast, an earlier input of fresh water (meltwater pulse 1a), whose origin is disputed, apparently did not lead to a reduction of the meridional overturning circulation. Here we analyse an ensemble of simulations of the drainage chronology of the North American ice sheet in order to identify the geographical release points of freshwater forcing during deglaciation. According to the simulations with our calibrated glacial systems model, the North American ice sheet contributed about half the fresh water of meltwater pulse 1a. During the onset of the Younger Dryas, we find that the largest combined meltwater/iceberg discharge was directed into the Arctic Ocean. Given that the only drainage outlet from the Arctic Ocean was via the Fram Strait into the Greenland-Iceland-Norwegian seas, where North Atlantic Deep Water is formed today, we hypothesize that it was this Arctic freshwater flux that triggered the Younger Dryas cold reversal.

  9. 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.

  10. Euxinic freshwater hypolimnia promote bacterial endemicity in continental areas.

    Science.gov (United States)

    Barberán, Albert; Casamayor, Emilio O

    2011-02-01

    Bacteria and archaea represent the vast majority of biodiversity on Earth. The ways that dynamic ecological and evolutionary processes interact in the microbial world are, however, poorly known. Here, we have explored community patterns of planktonic freshwater bacteria inhabiting stratified lakes with oxic/anoxic interfaces and euxinic (anoxic and sulfurous) water masses. The interface separates a well-oxygenated upper water mass (epilimnion) from a lower anoxic water compartment (hypolimnion). We assessed whether or not the vertical zonation of lakes promoted endemism in deeper layers by analyzing bacterial 16S rRNA gene sequences from the water column of worldwide distributed stratified lakes and applying a community ecology approach. Community similarity based on the phylogenetic relatedness showed that bacterial assemblages from the same water layer were more similar across lakes than to communities from different layer within lakes and that anoxic hypolimnia presented greater β-diversity than oxic epilimnia. Higher β-diversity values are attributable to low dispersal and small connectivity between community patches. In addition, surface waters had significant spatial but non-significant environmental components controlling phylogenetic β-diversity patterns, respectively. Conversely, the bottom layers were significantly correlated with environment but not with geographic distance. Thus, we observed different ecological mechanisms simultaneously acting on the same water body. Overall, bacterial endemicity is probably more common than previously thought, particularly in isolated and environmentally heterogeneous freshwater habitats. We argue for a microbial diversity conservation perspective still lacking in the global and local biodiversity preservation policies.

  11. The freshwater dolphin Inia geoffrensis geoffrensis produces high frequency whistles.

    Science.gov (United States)

    May-Collado, Laura J; Wartzok, Douglas

    2007-02-01

    Because whistles are most commonly associated with social delphinids, they have been largely overlooked, ignored, or presumed absent, in solitary freshwater dolphin species. Whistle production in the freshwater dolphin, the boto (Inia geoffrensis geoffrensis), has been controversial. Because of its sympatry with tucuxi dolphins (Sotalia fluviatilis), a whistling species, some presume tucuxi whistles might have been erroneously assigned to the boto. Using a broadband recording system, we recorded over 100 whistles from boto dolphins in the Yasunf River, Ecuador, where the tucuxi dolphins are absent. Our results therefore provide conclusive evidence for whistle production in Inia geoffrensis geoffrensis. Furthermore, boto whistles are significantly different from tucuxi whistles recorded in nearby rivers. The Ecuadorian boto whistle has a significantly greater frequency range (5.30-48.10 kHz) than previously reported in other populations (Peru and Colombia) that were recorded with more bandwidth limited equipment. In addition, the top frequency and the range are greater than in any other toothed whale species recorded to date. Whistle production was higher during resting activities, alone or in the presence of other animals. The confirmation of whistles in the boto has important implications for the evolution of whistles in Cetacea and their association with sociality.

  12. Marine and freshwater microplastic research in South Africa.

    Science.gov (United States)

    Verster, Carina; Minnaar, Karin; Bouwman, Hindrik

    2017-05-01

    South Africa has a vibrant plastics manufacturing industry, but recycling is limited and insufficient with a notable proportion of the unmanaged waste entering the environment. South Africa is a developing country with microplastics research in its inception. Very little is known about freshwater microplastics, and studies on South African marine microplastics are limited but actively being pursued. In a water-scarce country, protection of freshwater resources remains a priority, but in the face of other socioeconomic issues (poverty, unemployment, and HIV/AIDS), it receives insufficiently effective attention. The full impact and risks of microplastics pollution in water is yet to be discovered. The risks may be enhanced in a developing country where many communities remain largely dependent on the land and natural waters. With South Africa being a water-scarce country, the quality of its aquatic resources is at an even greater risk with an assumed increasing background of microplastics, emphasizing the need for further research. A South African Water Research Commission-funded project is being undertaken to derive research priorities, but there is an immediate need for improved recycling and waste management. Integr Environ Assess Manag 2017;13:533-535. © 2017 SETAC. © 2017 SETAC.

  13. Freshwater processing of terrestrial dissolved organic matter: What governs lability?

    Science.gov (United States)

    D'Andrilli, J.; Smith, H. J.; Junker, J. R.; Scholl, E. A.; Foreman, C. M.

    2016-12-01

    Aquatic and terrestrial ecosystems are linked through the transfer of energy and materials. Allochthonous organic matter (OM) is central to freshwater ecosystem function, influencing local food webs, trophic state, and nutrient availability. In order to understand the nature and fate of OM from inland headwaters to the open ocean, it is imperative to understand the links between OM lability and ecosystem function. Thus, biological, chemical, and physical factors need to be evaluated together to inform our understanding of environmental lability. We performed a laboratory processing experiment on naturally occurring OM leachates from riparian leaves, grasses, and pine needles. Measures of water chemistry, OM optical and molecular characterization, bacterial abundances, microbial assemblage composition, respiration, and C:N:P were integrated to discern the nature and fate of labile and recalcitrant OM in a freshwater stream. Peak processing of all OM sources in the stream water occurred after two days, with spikes in bacterial cell abundances, respiration rates, microbial assemblage shifts, and maximum C utilization. Respiration rates and microbial assemblages were dependent on the degree of lability of the OM molecular composition. Within the first few days, no differences in respiration rates were observed between leachate sources, however, beyond day five, the rates diverged with C processing efficiency correlated with OM lability. Originally comprised of amino acid-like, labile fluorescent species, the inoculated stream water OM became more recalcitrant after 16 days, indicating humification processing over time. Our study highlights the importance of interdisciplinary approaches for understanding the processing and fate of OM in aquatic ecosystems.

  14. Freshwater Sediment Characterization Factors of Copper Oxide Nanoparticles

    Science.gov (United States)

    Pu, Yubing; Laratte, Bertrand; Ionescu, Rodica Elena

    2017-01-01

    Wide use of engineered nanoparticles (ENPs) is likely to result in the eventually accumulation of ENPs in sediment. The benthic organisms living in sediments may suffer relatively high toxic effects of ENPs. This study has selected copper oxide nanoparticles (nano-CuO) as a research object. To consider the impacts of spatial heterogeneity on ENPs toxicity, the characterization factor (CF) derived from life cycle assessment (LCA) methodology is used as an indicator in this study. A nano-specific fate model has been used to calculate the freshwater sediment fate factor (FF) of nano-CuO. A literature survey of the nano-CuO toxicology values has been performed to calculate the effect factor (EF). Seventeen freshwater sediment CFs of nano-CuO are proposed as recommended values for subcontinental regions. The region most likely to be affected by nano-CuO is northern Australia (CF of 21.01·103 CTUe, comparative toxic units) and the least likely is northern Europe and northern Canada (CF of 8.55·103 CTUe). These sediment CFs for nano-CuO could be used in the future when evaluating the ecosystem impacts of products containing nano-CuO by LCA method.

  15. Standard methods for sampling freshwater fishes: Opportunities for international collaboration

    Science.gov (United States)

    Bonar, Scott A.; Mercado-Silva, Norman; Hubert, Wayne A.; Beard, Douglas; Dave, Göran; Kubečka, Jan; Graeb, Brian D. S.; Lester, Nigel P.; Porath, Mark T.; 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 state and federal agencies, universities, nongovernmental organizations, and consulting businesses. Currently, standardization is practiced mostly in North America and Europe. Participants described how standardization has been important for management of long-term data sets, promoting fundamental scientific understanding, and assessing efficacy of large spatial scale management strategies. Academics indicated that standardization has been useful in fisheries education because time previously used to teach how sampling methods are developed is now more devoted to diagnosis and treatment of problem fish communities. Researchers reported that standardization allowed increased sample size for method validation and calibration. Group consensus was to retain continental standards where they currently exist but to further explore international and intercontinental standardization, specifically identifying where synergies and bridges exist, and identify means to collaborate with scientists where standardization is limited but interest and need occur.

  16. Novel virophages discovered in a freshwater lake in China

    Directory of Open Access Journals (Sweden)

    Chaowen eGong

    2016-01-01

    Full Text Available Virophages are small double-stranded DNA viruses that are parasites of giant DNA viruses that infect unicellular eukaryotes. Here we identify a novel group of virophages, named Dishui Lake virophages (DSLVs that were discovered in Dishui Lake (DSL: an artificial freshwater lake in Shanghai, China. Based on PCR and metagenomic analysis, the complete genome of DSLV1 was found to be circular and 28,788 base pairs in length, with a G+C content 43.2%, and 28 predicted open reading frames (ORFs. Fifteen of the DSLV1 ORFs have sequence similarity to known virophages. Two DSLV1 ORFs exhibited sequence similarity to that of prasinoviruses (Phycodnaviridae and chloroviruses (Phycodnaviridae, respectively, suggesting horizontal gene transfer occurred between these large algal DNA viruses and DSLV1. 46 other virophages-related contigs were also obtained, including six homologous major capsid protein (MCP gene. Phylogenetic analysis of these MCPs showed that DSLVs are closely related to OLV (Organic Lake virophage and YSLVs (Yellowstone Lake virophages, especially to YSLV3, except for YSLV7. These results indicate that freshwater ecotopes are the hotbed for discovering novel virophages as well as understanding their diversity and properties.

  17. Risk Levels of Toxic Cyanobacteria in Portuguese Recreational Freshwaters.

    Science.gov (United States)

    Menezes, Carina; Churro, Catarina; Dias, Elsa

    2017-10-18

    Portuguese freshwater reservoirs are important socio-economic resources, namely for recreational use. National legislation concerning bathing waters does not include mandatory levels or guidelines for cyanobacteria and cyanotoxins. This is an issue of concern since cyanotoxin-based evidence is insufficient to change the law, and the collection of scientific evidence has been hampered by the lack of regulatory levels for cyanotoxins in bathing waters. In this work, we evaluate the profile of cyanobacteria and microcystins (MC) in eight freshwater reservoirs from the center of Portugal, used for bathing/recreation, in order to determine the risk levels concerning toxic cyanobacteria occurrence. Three of the reservoirs did not pose a risk of MC contamination. However, two reservoirs presented a high risk in 7% of the samples according to the World Health Organization (WHO) guidelines for MC in bathing waters (above 20 µg/L). In the remaining three reservoirs, the risk concerning microcystins occurrence was low. However, they exhibited recurrent blooms and persistent contamination with MC up to 4 µg/L. Thus, the risk of exposure to MC and potential acute and/or chronic health outcomes should not be disregarded in these reservoirs. These results contribute to characterize the cyanobacterial blooms profile and to map the risk of toxic cyanobacteria and microcystins occurrence in Portuguese inland waters.

  18. Risk Levels of Toxic Cyanobacteria in Portuguese Recreational Freshwaters

    Directory of Open Access Journals (Sweden)

    Carina Menezes

    2017-10-01

    Full Text Available Portuguese freshwater reservoirs are important socio-economic resources, namely for recreational use. National legislation concerning bathing waters does not include mandatory levels or guidelines for cyanobacteria and cyanotoxins. This is an issue of concern since cyanotoxin-based evidence is insufficient to change the law, and the collection of scientific evidence has been hampered by the lack of regulatory levels for cyanotoxins in bathing waters. In this work, we evaluate the profile of cyanobacteria and microcystins (MC in eight freshwater reservoirs from the center of Portugal, used for bathing/recreation, in order to determine the risk levels concerning toxic cyanobacteria occurrence. Three of the reservoirs did not pose a risk of MC contamination. However, two reservoirs presented a high risk in 7% of the samples according to the World Health Organization (WHO guidelines for MC in bathing waters (above 20 µg/L. In the remaining three reservoirs, the risk concerning microcystins occurrence was low. However, they exhibited recurrent blooms and persistent contamination with MC up to 4 µg/L. Thus, the risk of exposure to MC and potential acute and/or chronic health outcomes should not be disregarded in these reservoirs. These results contribute to characterize the cyanobacterial blooms profile and to map the risk of toxic cyanobacteria and microcystins occurrence in Portuguese inland waters.

  19. Occupational health issues in marine and freshwater research

    Directory of Open Access Journals (Sweden)

    Courtenay Glenn

    2012-03-01

    Full Text Available Abstract Marine and freshwater scientists are potentially exposed to a wide variety of occupational hazards. Depending on the focus of their research, risks may include animal attacks, physiological stresses, exposure to toxins and carcinogens, and dangerous environmental conditions. Many of these hazards have been investigated amongst the general population in their recreational use of the environment; however, very few studies have specifically related potential hazards to occupational exposure. For example, while the incidence of shark and crocodile attacks may invoke strong emotions and the occupational risk of working with these animals is certainly real, many more people are stung by jellyfish or bitten by snakes or dogs each year. Furthermore, a large proportion of SCUBA-related injuries and deaths are incurred by novice or uncertified divers, rather than professional divers using aquatic environments. Nonetheless, marine and freshwater research remains a potentially risky occupation, and the likelihood of death, injury and long-term health impacts still needs to be seriously considered.

  20. Contribution of conservation genetics in assessing neotropical freshwater fish biodiversity

    Directory of Open Access Journals (Sweden)

    NM. Piorski

    Full Text Available Human activities have a considerable impact on hydrographic systems and fish fauna. The present review on conservation genetics of neotropical freshwater fish reveals that DNA analyses have been promoting increased knowledge on the genetic structure of fish species and their response to environmental changes. This knowledge is fundamental to the management of wild fish populations and the establishment of Evolutionary Significant Units capable of conserving genetic integrity. While population structuring can occur even in long-distance migratory fish, isolated populations can show reduced genetic variation and be at greater risk of extinction. Phylogeography and phylogeny have been powerful tools in understanding the evolution of fish populations, species and communities in distinct neotropic environments. Captive fish can be used to introduce new individuals and genes into the wild and their benefits and disadvantages can be monitored through genetic analysis. Understanding how fish biodiversity in neotropical freshwaters is generated and maintained is highly important, as these habitats are transformed by human development and fish communities are increasingly exploited as food sources to sustain a growing human population.

  1. Whitemouth croaker, Micropogonias furnieri, trapped in a freshwater coastal lagoon: a natural comparison of freshwater and marine influences on otolith chemistry

    Directory of Open Access Journals (Sweden)

    Cristiano Q. de Albuquerque

    Full Text Available Strontium and barium incorporation into otoliths was compared between whitemouth croaker, Micropogonias furnieri, collected from an entrapped freshwater population (Mirim Lagoon and a normal marine/estuarine population in southern Brazil. Chemical analysis was performed using LA-ICPMS with the objective of validating the effects of marine and freshwater environments on Sr and Ba incorporation as a basis for further investigation of marine and freshwater connectivity of M. furnieri. The freshwater population was dominated by older fish with mean ±SD age of 34±1 y, whereas the coastal samples were dominated by younger fish of 14±7 y. Comparison of strontium and barium incorporation among otolith life-history profiles indicated significantly higher barium and lower strontium for the freshwater population compared to the marine population. Furthermore, comparison of otolith material deposited in the freshwater, estuarine and marine life-history phases demonstrated clear differences among these environments. Mean concentrations of strontium and barium in otoliths of M. furnieri were respectively 710 and 112 µg g-1 for freshwater, 2069 and 16.7 µg g-1 for estuarine, and 2990 and 2.7 µg g-1 for marine life-history phases. Barium concentrations in otoliths from the freshwater population of M. furnieri appeared high relative to other freshwater species. Strontium levels across life-history profiles of marine fish increased with age from 2000 to 2900 µg g-1, possibly indicating more time spent in marine than estuarine waters with age. In contrast, for the freshwater population, strontium levels decreased during the first year of life approximately to 700 µg g-1, and remained low and stable thereafter, consistent with the early life-history occurring in an estuarine environment prior to entrapment in Mirim Lagoon. The results confirm the strong and opposite effects of marine and freshwater environments on incorporation of barium and strontium into

  2. Phylogeography of an island endemic: the Puerto Rican freshwater crab, Epilobocera sinuatifrons

    Science.gov (United States)

    Benjamin D. Cook; Catherine M. Pringle; Jane M. Hughes

    2008-01-01

    The endemic Puerto Rican crab, Epilobocera sinuatifrons (Pseudothelphusidae), has a freshwater-dependant life-history strategy, although the species has some capabilities for terrestrial movement as adults. In contrast to all other freshwater decapods on the island (e.g., caridean shrimp), E. sinuatifrons does not undertake amphidromous migration, and is restricted to...

  3. Contrasting sensitivities to toxicants of the freshwater amphipods Gammarus pulex and G. fossarum

    NARCIS (Netherlands)

    Alonso, A.; Lange, de H.J.; Peeters, E.T.H.M.

    2010-01-01

    Amphipods are an important component of freshwater ecosystems. They are very often used in ecotoxicology, particularly the freshwater amphipod Gammarus pulex. However, there is scarce information on the sensitivity to toxicants of other species within the genus Gammarus. The present study aims to:

  4. Conservation status of the freshwater mussels of the United States and Canada

    Science.gov (United States)

    James D. Williams; Melvin L. Warren; Kevin S. Cummings; John L. Harris; Richard J. Neves

    1992-01-01

    The American Fisheries Society (AFS) herein provides a list of all native freshwater mussels (families Margaritiferidae and Unionidae) in the United States and Canada. This report also provides state and provincial distributions; a comprehensive review of the conservation status of all taxa; and references on biology, conservation, and distribution of freshwater...

  5. Dose-Time Effect of Crude Oil and Hydro-test Effluent on Freshwater ...

    African Journals Online (AJOL)

    This work was undertaken to investigate the dose-time effect of crude oil and hydro-test effluent on freshwater and brackish water habitats. The species used for the acute toxicity were freshwater fish, Tilapia guineenis (fry) and a brackish water shrimp, Palaemonetes africanus. Test results indicated that the brackish water ...

  6. 77 FR 61383 - Freshwater Crawfish Tail Meat From the People's Republic of China: Antidumping Duty...

    Science.gov (United States)

    2012-10-09

    ... International Trade Administration Freshwater Crawfish Tail Meat From the People's Republic of China: Antidumping Duty Administrative Review; 2010-2011 AGENCY: Import Administration, International Trade... administrative review of the antidumping duty order on freshwater crawfish tail meat from the People's Republic...

  7. 78 FR 61331 - Freshwater Crawfish Tail Meat From the People's Republic of China: Preliminary Results of...

    Science.gov (United States)

    2013-10-03

    ... International Trade Administration Freshwater Crawfish Tail Meat From the People's Republic of China: Preliminary Results of Antidumping Duty Administrative Review and New Shipper Review; 2011-2012 AGENCY: Import... order on freshwater crawfish tail meat from the People's Republic of China (PRC). The period of review...

  8. Growth of Vibrio cholerae O1 Ogawa Eltor in freshwater.

    Science.gov (United States)

    Vital, Marius; Füchslin, Hans Peter; Hammes, Frederik; Egli, Thomas

    2007-07-01

    Growth of Vibrio cholerae O1 Ogawa Eltor was studied with a growth assay in which autoclaved and filtered (0.22 microm) freshwater was inoculated at low cell density (5 x 10(3) cells ml(-1)) and proliferation was followed with flow cytometry. Against the common view, V. cholerae was able to grow extensively in different kinds of freshwater. The bacterium multiplied in river water, lake water and effluent of a wastewater treatment plant up to a cell density of 1.55 x 10(6) cells ml(-1). In these samples, apparent assimilable organic carbon (AOC(app)) concentrations ranged from 52 up to 800 microg l(-1) and the results demonstrate a positive trend between the AOC(app) concentration and final cell concentration, suggesting that AOC was a key parameter governing growth of V. cholerae. No growth was observed in waters (tap and bottled drinking water) containing less than approximately 60 microg AOC(app) l(-1). When pure cultures of V. cholerae were grown on identical lake water at different temperatures (20, 25 and 30 degrees C) the maximum specific growth rates (micromax) achieved were 0.22 h(-1), 0.32 h(-1) and 0.45 h(-1), respectively. In addition, growth was characterized in lake water samples amended with different concentrations of NaCl. The highest micromax of V. cholerae was recorded at moderate salinity levels (5 g NaCl l(-1), micromax=0.84 h(-1)), whereas at 30 g NaCl l(-1) (micromax=0.30 h(-1)) or 0 g NaCl l(-1) (micromax)=0.40 h(-1)) specific growth rates were significantly reduced. In the water tested here, micro(max) of V. cholerae was always around 50 % of that exhibited by a freshwater community of indigenous bacteria enriched from the water sampling site. Direct batch competition experiments between V. cholerae and the lake water bacterial community were performed at different temperatures in which V. cholerae was enumerated in the total community using fluorescent-surface antibodies. In all cases V. cholerae was able to grow and constituted around 10

  9. 78 FR 37205 - Freshwater Crawfish Tail Meat From the People's Republic of China: Rescission of Antidumping Duty...

    Science.gov (United States)

    2013-06-20

    ... International Trade Administration Freshwater Crawfish Tail Meat From the People's Republic of China: Rescission of Antidumping Duty New Shipper Review AGENCY: Import Administration, International Trade...) initiated the antidumping duty new shipper review of freshwater crawfish tail meat from the People's...

  10. The diatom flora in the vicinity of the Pretoria Salt Pan, Transvaal, Republic of South Africa. Part III (final)

    CSIR Research Space (South Africa)

    Schoeman, FR

    1984-03-12

    Full Text Available This is the third and final contribution on the diatom flora recorded in the vicinity of the pretoria salt pan. In the taxonomic section notes and illustrations (light and electron microscopy) are given for 19 of the 35 listed species....

  11. 76 FR 60733 - Safety Zone; Mississippi River, Mile Marker 230 to Mile Marker 234, in the Vicinity of Baton...

    Science.gov (United States)

    2011-09-30

    .... Basis and Purpose The Captain of the Port New Orleans has implemented a safety zone from mile marker 230... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Mississippi River, Mile Marker 230 to Mile Marker 234, in the Vicinity of Baton Rouge, LA AGENCY: Coast Guard, DHS. ACTION: Temporary final rule...

  12. 78 FR 35567 - Safety Zone; Lower Mississippi River, Mile Marker 219 to Mile Marker 229, in the Vicinity of Port...

    Science.gov (United States)

    2013-06-13

    ... Captain of the Port, New Orleans has implemented a safety zone from mile marker 219 to mile marker 225... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Lower Mississippi River, Mile Marker 219 to Mile Marker 229, in the Vicinity of Port Allen Lock AGENCY: Coast Guard, DHS. ACTION: Temporary final...

  13. 33 CFR 334.210 - Chesapeake Bay, in vicinity of Tangier Island; naval guided missiles test operations area.

    Science.gov (United States)

    2010-07-01

    ... Tangier Island; naval guided missiles test operations area. 334.210 Section 334.210 Navigation and... RESTRICTED AREA REGULATIONS § 334.210 Chesapeake Bay, in vicinity of Tangier Island; naval guided missiles test operations area. (a) The danger zone—(1) Prohibited area. A circle 1,000 yards in radius with its...

  14. 29 CFR 1915.95 - Ship repairing and shipbuilding work on or in the vicinity of radar and radio.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Ship repairing and shipbuilding work on or in the vicinity... STANDARDS FOR SHIPYARD EMPLOYMENT General Working Conditions § 1915.95 Ship repairing and shipbuilding work... repairing and shipbuilding. (a) No employees other than radar or radio repairmen shall be permitted to work...

  15. 14 CFR Appendix to Subpart U of... - Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ Appendix to Subpart U of Part 93 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES Special Flight Rules i...

  16. 14 CFR Special Federal Aviation... - 2-Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false 2-Special Flight Rules in the Vicinity of the Grand Canyon National Park, AZ Federal Special Federal Aviation Regulation No. 50 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES GENERAL OPERATING AND FLIGHT...

  17. 129I and 137Cs in groundwater in the vicinity of Fukushima Dai-ichi nuclear power plant

    DEFF Research Database (Denmark)

    Xu, Sheng; Zhang, Luyuan; Freeman, Stewart P.H.T.

    2016-01-01

    This paper reports iodine (127I and 129I) and cesium (137Cs) isotope concentrations in groundwater of confined and unconfined aquifers in the vicinity of the Fukushima Dai-ichi nuclear power plant (FDNPP). 127I and 129I concentrations range from 2–13 μg/L and 5 × 107–8 × 1010 atom/L respectively...

  18. Monitoring of Heavy Metals Spread in the Vicinity of Combined Heat and Power Plant-3, Using Indicator Plants

    Directory of Open Access Journals (Sweden)

    Manara A. Mukasheva

    2013-01-01

    Full Text Available Examination of heavy metals content in the vicinity of Combined Heat and Power Plant-3 in Karaganda showed that all the examined plants store the detectable chemical elements in concentrations, exceeding the background ones several times. The examined plants look more suppressed, have different distortions of morphological characteristics, if compared to the background ones

  19. Surveys of forest bird populations found in the vicinity of proposed geothermal project subzones in the district of Puna, Hawaii

    Energy Technology Data Exchange (ETDEWEB)

    Jacobi, J.D.; Reynolds, M.; Ritchotte, G.; Nielsen, B.; Viggiano, A.; Dwyer, J.

    1994-10-01

    This report presents data on the distribution and status of forest bird species found within the vicinity of proposed geothermal resource development on the Island of Hawaii. Potential impacts of the proposed development on the native bird populations found in the project are are addressed.

  20. Condition and Extent of the Natural Oyster Beds and Barren Bottoms in the Vicinity of Apalachicola, Fla.

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — A survey of oyster beds in the vicinity of Apalachicola, FL was conducted in 1915. The area of the oyster beds is 7,135 acres, or 11.1 square miles, of which...