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Sample records for freshwater bivalves advances

  1. Light and scanning electron microscopic studies of Unionicola tetrafurcatus (Acari: Unionicolidae) infecting four freshwater bivalve species with referring to histopathological effect on its hosts.

    Science.gov (United States)

    Abdel-Gaber, Rewaida; Fol, Mona; Al Quraishy, Saleh

    2018-05-08

    Water mites of the genus Unionicola are the most common symbionts of freshwater bivalves. During the current investigation, a total of 120 live freshwater mussels [Corbicula fluminea (Veneroida), Coelatura aegyptiaca (Unionoidea) Mutela rostrata and Chambardia rubens (Mutelidae)], were collected from 2 localities in Tura (Helwan Governorate) and El Kanater (Qaluobiya Governorate), Egypt. Only 3 of the 4 bivalve species listed are considered freshwater bivalves (members of Unionoidea). While, C. fluminea belong to the family Cyrenidae within Veneroida. The collected mussels were dissected and examined for the presence of unionicolid mites. It was found that 30.83% (37/120) were infected with a single mite species Unionicola tetrafurcatus (Unionicolidae). The highest prevalence was observed during the summer with 83.33% (25/30), whereas the least was observed in autumn, i.e. 33.33% (10/30). Mites were recovered from the gills, gonads, and visceral mass of mussel hosts. gills of host mussels were the primary site of oviposition for unionicola mites. Smaller bivalves in size had significantly greater numbers of mites than larger ones in size. Numbers of mites per host species was variable and the highest prevalence level of 83.33% (25/30) was recorded in C. fluminea, while, the lowest one of 16.66% (5/30) was found in C. rubens. Morphological and morphometric characterizations of mites revealed some differences between the present species and other related Unionicola. Histopathological responses of host mussels to the eggs, larvae, and cuticular remnants of U. tetrafurcatus were also studied. Therefore, the present study demonstrated that freshwater bivalves have a new host and locality records for infection with U. tetrafurcatus. Future studies are recommended to include advanced molecular characteristics for these mites.

  2. First records of Freshwater Bivalves of Ilha Grande National Park, Paraná, Brazil

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    Flávio Henrique Ragonha

    2014-03-01

    Full Text Available The Ilha Grande National Park, Paraná, Brazil, is located in the Upper Paraná River and has characteristics typical of a floodplains. This protected area includes lagoons connected and disconnected to the Paraná River, although the latter also connect during periods of high water level, thus composing a heterogeneous group of lacustrine environments. The enormous potential the flora and fauna diversities are still little known to the region, as can be seen through benthic invertebrates, inclunding bivalves mollusks. The granulometric composition of these floodplain lagoons was formed mainly by mud and very fine sand. Furthermore, organic matter composition was predominantly of fine particulate. The other abiotic factors differed from lagoons located within the island of the park to those located in the left margin of Paraná River. The results demonstrated the importance of abiotic factors such as the physical composition of granulometric texture, organic matter and macrophyte banks, to the establishment of bivalves in these floodplain lagoons. We recorded bivalves of Pisidium (native, Diplodon (native, and Corbicula (invasive. The highest values of Diplodon sp. density were observed at São João/C lake, for Pisidium sterkianum (Pilsbry, 1897 at São João/M lake, and to Jatobá/C lagoon with high density of invasive species Corbicula fluminea (Müller, 1774. This study to obtain conduct the first records of freshwater bivalves in floodplains lagoon in the Ilha Grande National Park, and provides contributions to better understanding the ecology of these mollusks. The recording of native species in the region of Upper Paraná River floodplain after a lomg period without new records, demonstrated the importance of protecting the lagoons of the Ilha Grande National Park as they can be a possible refuge to some species of native freshwater bivalves.

  3. Zoochorous dispersal of freshwater bivalves: an overlooked vector in biological invasions?

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    Coughlan Neil E.

    2017-01-01

    Full Text Available Vectors that underpin the natural dispersal of invasive alien species are frequently unknown. In particular, the passive dispersal (zoochory of one organism (or propagule by another, usually more mobile animal, remains poorly understood. Field observations of the adherence of invasive freshwater bivalves to other organisms have prompted us to assess the importance of zoochory in the spread of three prolific invaders: zebra mussel Dreissena polymorpha; quagga mussel Dreissena bugensis; and Asian clam Corbicula fluminea. An extensive, systematic search of the literature was conducted across multiple on-line scientific databases using various search terms and associated synonyms. In total, only five publications fully satisfied the search criteria. It appears that some fish species can internally transport viable adult D. polymorpha and C. fluminea specimens. Additionally, literature indicates that veligers and juvenile D. polymorpha can adhere to the external surfaces of waterbirds. Overall, literature suggests that zoochorous dispersal of invasive bivalves is possible, but likely a rare occurrence. However, even the establishment of a few individuals (or a single self-fertilising C. fluminea specimen can, over-time, result in a substantial population. Here, we highlight knowledge gaps, identify realistic opportunities for data collection, and suggest management protocols to mitigate the spread of invasive alien species.

  4. Linking changes in subcellular cadmium distribution to growth and mortality rates in transplanted freshwater bivalves (Pyganodon grandis)

    International Nuclear Information System (INIS)

    Perceval, Olivier; Couillard, Yves; Pinel-Alloul, Bernadette; Campbell, Peter G.C.

    2006-01-01

    Relationships between Cd accumulation and subcellular distribution, and growth and mortality rates were examined in the freshwater bivalve Pyganodon grandis in a transplant experiment. Organisms were transferred from a clean lacustrine site to four lakes situated along a Cd concentration gradient in the mining region of Rouyn-Noranda. The bivalves were maintained in open enclosures placed in the bottom sediments of the littoral zone of all five lakes for 400 days. At the end of the experiment, metallothionein (MT) was measured in the bivalve gills with a Hg-saturation assay and Cd partitioning among the various cytosolic protein pools was determined by size-exclusion chromatography. Marked differences were observed among the five sites: the range in calculated free-cadmium ion concentrations in water overlying the sediments was 35-fold whereas Cd concentrations in the gill cytosol of the transplanted bivalves varied three-fold. In the transplanted bivalves, the distribution of gill Cd among the various cytosolic complexes also varied significantly among sites. For bivalves transplanted to the three most contaminated sites, Cd concentrations in the high molecular weight pool (HMW > 25 kDa) were significantly higher than the baseline levels determined from bivalves caged at the reference site; a similar trend was seen for Cd concentrations in the metallothionein pool (Cd-MT). For bivalves transferred to two of the high contamination sites, proportionately less of the gill cytosolic Cd was sequestered (i.e. detoxified) by MT-like proteins. Reductions in survival were also observed at these two sites, and these elevated mortalities, in turn, were consistent with the absence of indigenous bivalve populations at these sites. This result is compatible with our recent work on P. grandis populations living in lakes of the Rouyn-Noranda area, in which we demonstrated that excessive accumulation of Cd in the HMW pool of the gill cytosol of the individual mollusks could be

  5. Inducing the Alternative Oxidase Forms Part of the Molecular Strategy of Anoxic Survival in Freshwater Bivalves

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    Yusseppone, Maria S.; Rocchetta, Iara; Sabatini, Sebastian E.; Luquet, Carlos M.; Ríos de Molina, Maria del Carmen; Held, Christoph; Abele, Doris

    2018-01-01

    Hypoxia in freshwater ecosystems is spreading as a consequence of global change, including pollution and eutrophication. In the Patagonian Andes, a decline in precipitation causes reduced lake water volumes and stagnant conditions that limit oxygen transport and exacerbate hypoxia below the upper mixed layer. We analyzed the molecular and biochemical response of the North Patagonian bivalve Diplodon chilensis after 10 days of experimental anoxia (<0.2 mg O2/L), hypoxia (2 mg O2/L), and normoxia (9 mg O2/L). Specifically, we investigated the expression of an alternative oxidase (AOX) pathway assumed to shortcut the regular mitochondrial electron transport system (ETS) during metabolic rate depression (MRD) in hypoxia-tolerant invertebrates. Whereas, the AOX system was strongly upregulated during anoxia in gills, ETS activities and energy mobilization decreased [less transcription of glycogen phosphorylase (GlyP) and succinate dehydrogenase (SDH) in gills and mantle]. Accumulation of succinate and induction of malate dehydrogenase (MDH) activity could indicate activation of anaerobic mitochondrial pathways to support anoxic survival in D. chilensis. Oxidative stress [protein carbonylation, glutathione peroxidase (GPx) expression] and apoptotic intensity (caspase 3/7 activity) decreased, whereas an unfolded protein response (HSP90) was induced under anoxia. This is the first clear evidence of the concerted regulation of the AOX and ETS genes in a hypoxia-tolerant freshwater bivalve and yet another example that exposure to hypoxia and anoxia is not necessarily accompanied by oxidative stress in hypoxia-tolerant mollusks. PMID:29527172

  6. Inducing the Alternative Oxidase Forms Part of the Molecular Strategy of Anoxic Survival in Freshwater Bivalves

    Directory of Open Access Journals (Sweden)

    Maria S. Yusseppone

    2018-02-01

    Full Text Available Hypoxia in freshwater ecosystems is spreading as a consequence of global change, including pollution and eutrophication. In the Patagonian Andes, a decline in precipitation causes reduced lake water volumes and stagnant conditions that limit oxygen transport and exacerbate hypoxia below the upper mixed layer. We analyzed the molecular and biochemical response of the North Patagonian bivalve Diplodon chilensis after 10 days of experimental anoxia (<0.2 mg O2/L, hypoxia (2 mg O2/L, and normoxia (9 mg O2/L. Specifically, we investigated the expression of an alternative oxidase (AOX pathway assumed to shortcut the regular mitochondrial electron transport system (ETS during metabolic rate depression (MRD in hypoxia-tolerant invertebrates. Whereas, the AOX system was strongly upregulated during anoxia in gills, ETS activities and energy mobilization decreased [less transcription of glycogen phosphorylase (GlyP and succinate dehydrogenase (SDH in gills and mantle]. Accumulation of succinate and induction of malate dehydrogenase (MDH activity could indicate activation of anaerobic mitochondrial pathways to support anoxic survival in D. chilensis. Oxidative stress [protein carbonylation, glutathione peroxidase (GPx expression] and apoptotic intensity (caspase 3/7 activity decreased, whereas an unfolded protein response (HSP90 was induced under anoxia. This is the first clear evidence of the concerted regulation of the AOX and ETS genes in a hypoxia-tolerant freshwater bivalve and yet another example that exposure to hypoxia and anoxia is not necessarily accompanied by oxidative stress in hypoxia-tolerant mollusks.

  7. Anodontites trapesialis (LAMARCK, 1819: a bivalve parasite of freshwater fishes / Anodontites trapesialis (LAMARCK, 1819: um bivalve parasito de peixes de água doce

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    Ângela Teresa Silva-Souza

    2008-08-01

    Full Text Available The bivalve mollusk Anodontites trapesialis has been indicated as an alternative source for aquaculture because it is considered a food of good nutritional value with a protein content close to that of fish. Its shells can be utilized as fertilizer and mixed to the food of domestic animals, and the nacre can be used to manufacture buttons and crafts. However, the larvae of A. trapesialis, which are the lasidium type, are obligatory parasites of freshwater fishes, and the introduction of this bivalve in fish farm tanks have caused trouble and losses for producers. Nothing is known, however, about their development in these environments. On the other hand, it should be pointed out that A. trapesialis is on Brazil’s list of species threatened with extinction. This article provides a compilation of information present in the literature, offering a detailed review, with the aim of presenting a general panorama of what is known about Anodontites trapesialis and its larval parasitism of fishes.O molusco bivalve, Anodontites trapesialis, tem sido indicado como fonte alternativa para a aqüicultura, por ser considerado um alimento de bom valor nutricional com um conteúdo protéico próximo ao do pescado. Suas conchas podem ser utilizadas como fertilizantes calcáreos e ser agregadas a alimentos de animais domésticos e o nácar pode ser utilizado para fabricar botões e artesanatos. No entanto, as larvas de A. trapesialis, que são do tipo lasidium, são parasitas obrigatórias de peixes de água doce e a introdução desse bivalve em tanques de piscicultura tem causado transtornos e prejuízos aos produtores. Nada se conhece, porém, sobre o seu desenvolvimento nesses ambientes. Por outro lado, ressalta-se que A. trapesialis consta da lista brasileira de espécies ameaçadas de extinção. No presente artigo são compiladas as informações presentes na literatura, em uma revisão detalhada, com o objetivo de apresentar o panorama geral do

  8. Characterization of freshwater bivalves as radio contamination (57Co, 110mAg, 134Cs) bio-indicators in a metallic multi pollution context (Cd, Zn)

    International Nuclear Information System (INIS)

    Fraysse, B.

    2001-07-01

    This study concerns freshwater bio-indicators of radio-contamination, in a metallic multi-pollution context. Metals, such as cadmium (Cd) and zinc (Zn), are widely represented in aquatic ecosystems, and their concentrations can induce physiological effects. This chronicle exposure generates both metabolic and behaviour stress of individuals, and can also yield to detoxification mechanisms induction. The main goal of this work was to estimate the influence of metals on the radionuclides ( 57 Co, 110m Ag, 134 Cs) bioaccumulation by two different bivalve species (Corbicula fluminea et Dreissena polymorpha), by studying the contamination level, the kinetic of the radionuclide transfer and the soft-body repartition. As the exploratory feature of this study, two parts have been developed: (i) testing the problematic suitability in a really bio-monitoring situation, and (ii) analysing the metal/radionuclide interaction mechanisms under controlled and standardised conditions (laboratory). For the different experimental conditions explored (laboratory and field), radionuclide bioaccumulation by freshwater bivalves has been influenced by metal exposure. This result was obtained after assessing a decrease of the organisms contamination level by radionuclide and their accumulation rate, an increase of their depuration rate and tissue and cellular repartition changes. (author)

  9. Effect of chronic selenium exposure on the freshwater bivalve Corbicula fluminea

    Energy Technology Data Exchange (ETDEWEB)

    Fournier, E.; Adam, C.; Massabuau, J.C.; Garnier-Laplace, J. [CEA Cadarache (DEI/SECRE/LRE), Laboratory of Radioecology and Ecotoxicology, Institute for Radioprotection and Nuclear Safety, 13 - Saint-Paul-lez-Durance (France)

    2004-07-01

    Selenium is essential for most of living organisms. In oxic to moderately oxic fresh-waters, Se exists predominantly in the (+VI) and (+IV) oxidation states as selenate (SeO{sub 4}{sup 2-}) and selenite (SeO{sub 3}{sup 2-}) respectively, whereas in the biota it is incorporated as Se(-II) into seleno-proteins or amino-acids, or as elemental selenium Se(0). At low concentrations, it acts against oxidative damages mainly as the glutathione peroxidase seleno-dependant, but it may be toxic at higher levels (for example, by replacing sulphur in important biomolecules). In filter feeders, such as the freshwater bivalve Corbicula fluminea, selected as biological model, the ventilation activity is a primary limiting step that controls the water influx and therefore the delivery of contaminants. Consequently, a series of short-term experiments were performed to study the effects of different dissolved Se concentrations and forms (selenite; selenate; selenomethionine) on the ventilation activity of Corbicula fluminea and Se tissular distribution. The modification of the ventilation activity of the Se-exposed groups, in comparison to this of reference groups (not exposed to Se) varied greatly according to the form and the concentrations of the Se used. Se concentrations in tissues indicated that selenite was the less bioavailable form whereas selenomethionine displayed the opposite trend. On the basis of this set of experiments, a limited number of conditions have been selected to provide highly contrasting ventilation flow rates and selenium bioaccumulation levels, in order to study the effects of long term exposures, i) at the molecular level, by measuring bio-markers of oxidative stress (forms of glutathione, glutathione peroxidase, glutathione reductase, superoxide dismutase, catalase, and bio-marker of genotoxicity (comet assay), ii) at the (sub)cellular level by analysing Se micro-localisation in target organs and iii) at the individual level by monitoring the variation

  10. Subcellular partitioning of cadmium in the freshwater bivalve, Pyganodon grandis, after separate short-term exposures to waterborne or diet-borne metal

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Sophie; Hare, Landis [INRS-Eau, Terre et Environnement, Universite du Quebec, 490 rue de la Couronne, Quebec, QC, G1K 9A9 (Canada); Campbell, Peter G.C., E-mail: peter.campbell@ete.inrs.ca [INRS-Eau, Terre et Environnement, Universite du Quebec, 490 rue de la Couronne, Quebec, QC, G1K 9A9 (Canada)

    2010-11-15

    The dynamics of cadmium uptake and subcellular partitioning were studied in laboratory experiments conducted on Pyganodon grandis, a freshwater unionid bivalve that shows promise as a biomonitor for metal pollution. Bivalves were collected from an uncontaminated lake, allowed to acclimate to laboratory conditions ({>=}25 days), and then either exposed to a low, environmentally relevant, concentration of dissolved Cd (5 nM; 6, 12 and 24 h), or fed Cd-contaminated algae ({approx}70 nmol Cd g{sup -1} dry weight; 4 x 4 h). In this latter case, the bivalves were allowed to depurate for up to 8 days after the end of the feeding phase. As anticipated, the gills were the main target organ during the aqueous Cd exposure whereas the intestine was the initial site of Cd accumulation during the dietary exposure; during the subsequent depuration period, the dietary Cd accumulated in both the digestive gland and in the gills. For the gills, the distribution of Cd among the subcellular fractions (i.e., granules > heat-denatured proteins (HDP) {approx} heat-stable proteins (HSP) > mitochondria {approx} lysosomes + microsomes) was insensitive to the exposure route; both waterborne and diet-borne Cd ended up largely bound to the granule fraction. The subcellular distribution of Cd in the digestive gland differed markedly from that in the gills (HDP > HSP {approx} granules {approx} mitochondria > lysosomes + microsomes), but as in the case of the gills, this distribution was relatively insensitive to the exposure route. For both the gills and the digestive gland, the subcellular distributions of Cd differed from those observed in native bivalves that are chronically exposed to Cd in the field - in the short-term experimental exposures of P. grandis, metal detoxification was less effective than in chronically exposed native bivalves.

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

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

    2016-01-01

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

  12. Influence of a step-change in metal exposure (Cd, Cu, Zn) on metal accumulation and subcellular partitioning in a freshwater bivalve, Pyganodon grandis: A long-term transplantation experiment between lakes with contrasting ambient metal levels

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Sophie [INRS-Eau, Terre et Environnement, Université du Québec, 490 de la Couronne, Québec, QC G1K 9A9 (Canada); Bonneris, Emmanuelle [INRS-Eau, Terre et Environnement, Université du Québec, 490 de la Couronne, Québec, QC G1K 9A9 (Canada) and Bayer S.A.S., Bayer CropScience, 16 Rue Jean-Marie Leclair, CP 90106, F 69266 Lyon Cedex 09 (France); Michaud, Annick [INRS-Eau, Terre et Environnement, Université du Québec, 490 de la Couronne, Québec, QC G1K 9A9 (Canada) and Direction des Évaluations environnementales, Ministère du Développement durable, de l’Environnement et des Parcs, 675, boul. René-Lévesque Est, 6e étage, Québec, QC G1R 5V7 (Canada); Pinel-Alloul, Bernadette [Groupe de Recherche Interuniversitaire en Limnologie et Environnement Aquatique (GRIL), Département de Sciences Biologiques, Université de Montréal, C.P. 6128, Montréal, QC H3C 3J7 (Canada); Campbell, Peter G.C., E-mail: peter.campbell@ete.inrs.ca [INRS-Eau, Terre et Environnement, Université du Québec, 490 de la Couronne, Québec, QC G1K 9A9 (Canada)

    2013-05-15

    Highlights: ? We transferred freshwater bivalves from a reference lake to a Cd and Zn contaminated lake. ? Changes in metal accumulation and subcellular partitioning were followed over time (up to 860 d). ? Metal detoxification strategies differed between target organs (gills vs. digestive gland). ? The ability to handle Cd is inherent in P. grandis, not a trait acquired after long-term adaptation. -- Abstract: The objective of the present field experiment was to identify detoxification responses in the gills and digestive gland of a freshwater unionid bivalve, Pyganodon grandis, subjected to a step-change in metal exposure. Adult bivalves were transferred from a reference site (Lake Opasatica) and a metal-contaminated lake (Lake Héva) to a second contaminated lake (Lake Vaudray) in northwestern Quebec, Canada. Changes in organ metal concentrations, in the subcellular distribution of metals and in metallothionein concentrations were followed over time (t = 0, 132, (400) and 860 days). At each collection time and for each bivalve, the gills and digestive gland were excised and gently homogenized; six sub-cellular fractions were separated by differential centrifugation and analyzed for their Cd, Cu and Zn content, and metallothionein was quantified independently. Metal detoxification strategies were shown to differ between target organs: in the gills, incoming metals were sequestered largely in the granules, whereas in the digestive gland the same metals primarily accumulated in the cytosol, in the metallothionein-like protein fraction. These metal-handling strategies, as employed by the metal-naïve bivalves originating in the reference lake, closely resemble those identified in free-living P. grandis chronically exposed in the metal-contaminated lake, suggesting that the ability to handle incoming metals (Cd in particular) is inherent in P. grandis and is not a trait acquired after long-term adaptation of the bivalve to metal-contaminated environments. The

  13. Dioxin-like chemicals in bivalves and sediment collected from around Australia

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, J.F.; Muller, R.; Goudkamp, K. [EnTox, The University of Queensland, Brisbane (AU)] (and others)

    2004-09-15

    The aquatic environment is a significant sink for persistent organic pollutants including dioxin-like chemicals. Besides continuous investigations into sources of higher chlorinated PCDD that have initially been found in soils, and later in dugong and sediments little is known about the levels of dioxin-like chemicals in Australia's aquatic environment. In 2002 the National Dioxin Program (NDP) was commissioned by the Department of Environment and Heritage, Australia. One focus of the NDP was to evaluate background levels of dioxin-like chemicals in Australia's environment. One component of the 'Environmental Levels' project aimed to identify dioxinlike chemicals in the aquatic environment including bivalves collected in both marine, estuarine and freshwater systems. Here we report results from the NDP aquatic study with a particular emphasis on the levels of dioxin-like chemicals in bivalves and sediments respectively in areas from where the bivalves were collected.

  14. Calibration of hydroclimate proxies in freshwater bivalve shells from Central and West Africa

    Science.gov (United States)

    Kelemen, Zita; Gillikin, David P.; Graniero, Lauren E.; Havel, Holly; Darchambeau, François; Borges, Alberto V.; Yambélé, Athanase; Bassirou, Alhou; Bouillon, Steven

    2017-07-01

    Freshwater bivalve shell oxygen and carbon stable isotope ratios (δ18O, δ13C) may act as recorders of hydroclimate (e.g., precipitation-evaporation balance, discharge) and aquatic biogeochemistry. We investigate the potential of these hydroclimate proxies measured along the growth axis of shells collected from the Oubangui River (Bangui, Central African Republic) and the Niger River (Niamey, Niger). Biweekly water samples and in situ measurements collected over several years, along with daily discharge data from both sites allowed a direct comparison with proxies recorded in the shells. Data from a total of 14 unionid shells, including three species (Chambardia wissmanni, Aspatharia dahomeyensis, and Aspatharia chaiziana), confirmed that shells precipitate carbonate in oxygen isotope equilibrium with ambient water. Because water temperature variations were small, shell δ18O values (δ18Oshell) also accurately record the seasonality and the range observed in water δ18O (δ18Ow) values when calculated using an average temperature. Calculated δ18Ow values were in good agreement over the entire record of measured δ18Ow values, thus δ18Oshell records can be reliably used to reconstruct past δ18Ow values. Discharge and δ18Ow values from both rivers fit a logarithmic relationship, which was used to attempt reconstruction of past hydrological conditions, after calculating δ18Ow values from δ18Oshell values. A comparison with measured discharge data suggests that for the two rivers considered, δ18Oshell data are good proxies for recording discharge conditions during low(er) discharge levels, but that high discharge values cannot be accurately reconstructed due to the large scatter in the discharge-δ18Ow relationship. Moreover, periods of bivalve shell growth cessation due to high turbidity or air exposure should be taken into account. While δ13C values of dissolved inorganic carbon in both rivers showed clear seasonality and correlated well with discharge

  15. Using biochemical and isotope geochemistry to understand the environmental and public health implications of lead pollution in the lower Guadiana River, Iberia: A freshwater bivalve study

    Energy Technology Data Exchange (ETDEWEB)

    Company, R. [CIMA, Faculty of Marine and Environmental Sciences, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)], E-mail: rcompany@ualg.pt; Serafim, A.; Lopes, B.; Cravo, A. [CIMA, Faculty of Marine and Environmental Sciences, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Shepherd, T.J.; Pearson, G. [Department of Earth Sciences, Durham University, Science Labs., Durham DH1 3LE (United Kingdom); Bebianno, M.J. [CIMA, Faculty of Marine and Environmental Sciences, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)], E-mail: mbebian@ualg.pt

    2008-11-01

    Lead is a natural component of aquatic ecosystems with no known biological role and is highly toxic. Its toxicity stems from its ability to mimic biologically important metals and to produce membrane damage through lipid peroxidation (LPO). Most lead poisoning symptoms are thought to occur by interfering with an essential enzyme, {delta}-aminolevulinic acid dehydratase (ALAD), the activity of which is markedly inhibited by lead. The purpose of this work was to study the levels and effects of lead pollution (responses of ALAD and oxidative stress biomarker LPO) in the freshwater bivalve Corbicula fluminea along the lower Guadiana River (Portugal and Spain); a major river system impacted by historic mining pollution and more recent anthropogenic inputs. The results show that the enzymatic activity of ALAD is negatively correlated with the total Pb concentration of the whole tissue suggesting that ALAD has considerable potential as a biomarker of lead exposure in C. fluminea. To identify the sources of lead to which bivalves have been exposed, high precision {sup 206}Pb/{sup 204}Pb, {sup 207}Pb/{sup 204}Pb, {sup 208}Pb/{sup 204}/Pb ratios for C. fluminea confirm that historical mining activities in the Iberian Pyrite Belt are the dominant source of lead pollution in the lower Guadiana River. The isotope patterns however exhibit marked seasonal and geographic variation in response to rainfall and river water management. Locally, other anthropogenic sources of lead have been detected in C. fluminea close to population centres, thus adding to its versatility as a freshwater bio-indicator. Overall, the study highlights the value of natural ecosystems as monitors of water quality and their importance for public health assessment and surveillance.

  16. Using biochemical and isotope geochemistry to understand the environmental and public health implications of lead pollution in the lower Guadiana River, Iberia: a freshwater bivalve study.

    Science.gov (United States)

    Company, R; Serafim, A; Lopes, B; Cravo, A; Shepherd, T J; Pearson, G; Bebianno, M J

    2008-11-01

    Lead is a natural component of aquatic ecosystems with no known biological role and is highly toxic. Its toxicity stems from its ability to mimic biologically important metals and to produce membrane damage through lipid peroxidation (LPO). Most lead poisoning symptoms are thought to occur by interfering with an essential enzyme, delta-aminolevulinic acid dehydratase (ALAD), the activity of which is markedly inhibited by lead. The purpose of this work was to study the levels and effects of lead pollution (responses of ALAD and oxidative stress biomarker LPO) in the freshwater bivalve Corbicula fluminea along the lower Guadiana River (Portugal and Spain); a major river system impacted by historic mining pollution and more recent anthropogenic inputs. The results show that the enzymatic activity of ALAD is negatively correlated with the total Pb concentration of the whole tissue suggesting that ALAD has considerable potential as a biomarker of lead exposure in C. fluminea. To identify the sources of lead to which bivalves have been exposed, high precision (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)/Pb ratios for C. fluminea confirm that historical mining activities in the Iberian Pyrite Belt are the dominant source of lead pollution in the lower Guadiana River. The isotope patterns however exhibit marked seasonal and geographic variation in response to rainfall and river water management. Locally, other anthropogenic sources of lead have been detected in C. fluminea close to population centres, thus adding to its versatility as a freshwater bio-indicator. Overall, the study highlights the value of natural ecosystems as monitors of water quality and their importance for public health assessment and surveillance.

  17. Using biochemical and isotope geochemistry to understand the environmental and public health implications of lead pollution in the lower Guadiana River, Iberia: A freshwater bivalve study

    International Nuclear Information System (INIS)

    Company, R.; Serafim, A.; Lopes, B.; Cravo, A.; Shepherd, T.J.; Pearson, G.; Bebianno, M.J.

    2008-01-01

    Lead is a natural component of aquatic ecosystems with no known biological role and is highly toxic. Its toxicity stems from its ability to mimic biologically important metals and to produce membrane damage through lipid peroxidation (LPO). Most lead poisoning symptoms are thought to occur by interfering with an essential enzyme, δ-aminolevulinic acid dehydratase (ALAD), the activity of which is markedly inhibited by lead. The purpose of this work was to study the levels and effects of lead pollution (responses of ALAD and oxidative stress biomarker LPO) in the freshwater bivalve Corbicula fluminea along the lower Guadiana River (Portugal and Spain); a major river system impacted by historic mining pollution and more recent anthropogenic inputs. The results show that the enzymatic activity of ALAD is negatively correlated with the total Pb concentration of the whole tissue suggesting that ALAD has considerable potential as a biomarker of lead exposure in C. fluminea. To identify the sources of lead to which bivalves have been exposed, high precision 206 Pb/ 204 Pb, 207 Pb/ 204 Pb, 208 Pb/ 204 /Pb ratios for C. fluminea confirm that historical mining activities in the Iberian Pyrite Belt are the dominant source of lead pollution in the lower Guadiana River. The isotope patterns however exhibit marked seasonal and geographic variation in response to rainfall and river water management. Locally, other anthropogenic sources of lead have been detected in C. fluminea close to population centres, thus adding to its versatility as a freshwater bio-indicator. Overall, the study highlights the value of natural ecosystems as monitors of water quality and their importance for public health assessment and surveillance

  18. Proteomic Profiling of Cytosolic Glutathione Transferases from Three Bivalve Species: Corbicula fluminea, Mytilus galloprovincialis and Anodonta cygnea

    Directory of Open Access Journals (Sweden)

    José Carlos Martins

    2014-01-01

    Full Text Available Suspension-feeding bivalves are considered efficient toxin vectors with a relative insensitivity to toxicants compared to other aquatic organisms. This fact highlights the potential role of detoxification enzymes, such as glutathione transferases (GSTs, in this bivalve resistance. Nevertheless, the GST system has not been extensively described in these organisms. In the present study, cytosolic GSTs isoforms (cGST were surveyed in three bivalves with different habitats and life strategies: Corbicula fluminea, Anodonta cygnea and Mytilus galloprovincialis. GSTs were purified by glutathione-agarose affinity chromatography, and the collection of expressed cGST classes of each bivalve were identified using a proteomic approach. All the purified extracts were also characterized kinetically. Results reveal variations in cGST subunits collection (diversity and properties between the three tested bivalves. Using proteomics, four pi-class and two sigma-class GST subunits were identified in M. galloprovincialis. C. fluminea also yielded four pi-class and one sigma-class GST subunits. For A. cygnea, two mu-class and one pi-class GST subunits were identified, these being the first record of GSTs from these freshwater mussels. The affinity purified extracts also show differences regarding enzymatic behavior among species. The variations found in cGST collection and kinetics might justify diverse selective advantages for each bivalve organism.

  19. Bivalve aquaculture-environment interactions in the context of climate change.

    Science.gov (United States)

    Filgueira, Ramón; Guyondet, Thomas; Comeau, Luc A; Tremblay, Réjean

    2016-12-01

    Coastal embayments are at risk of impacts by climate change drivers such as ocean warming, sea level rise and alteration in precipitation regimes. The response of the ecosystem to these drivers is highly dependent on their magnitude of change, but also on physical characteristics such as bay morphology and river discharge, which play key roles in water residence time and hence estuarine functioning. These considerations are especially relevant for bivalve aquaculture sites, where the cultured biomass can alter ecosystem dynamics. The combination of climate change, physical and aquaculture drivers can result in synergistic/antagonistic and nonlinear processes. A spatially explicit model was constructed to explore effects of the physical environment (bay geomorphic type, freshwater inputs), climate change drivers (sea level, temperature, precipitation) and aquaculture (bivalve species, stock) on ecosystem functioning. A factorial design led to 336 scenarios (48 hydrodynamic × 7 management). Model outcomes suggest that the physical environment controls estuarine functioning given its influence on primary productivity (bottom-up control dominated by riverine nutrients) and horizontal advection with the open ocean (dominated by bay geomorphic type). The intensity of bivalve aquaculture ultimately determines the bivalve-phytoplankton trophic interaction, which can range from a bottom-up control triggered by ammonia excretion to a top-down control via feeding. Results also suggest that temperature is the strongest climate change driver due to its influence on the metabolism of poikilothermic organisms (e.g. zooplankton and bivalves), which ultimately causes a concomitant increase of top-down pressure on phytoplankton. Given the different thermal tolerance of cultured species, temperature is also critical to sort winners from losers, benefiting Crassostrea virginica over Mytilus edulis under the specific conditions tested in this numerical exercise. In general, it is

  20. Can bivalve veligers escape feeding currents of adult bivalves?

    NARCIS (Netherlands)

    Troost, K.; Veldhuizen, R.; Stamhuis, E.J.; Wolff, W.J.

    2008-01-01

    While the stock of introduced Pacific oysters (Crassostrea gigas) increased in the Oosterschelde estuary (SW Netherlands), so did the filtration pressure of all bivalve species together. In the same period, stocks of native bivalves declined slightly. The expansion of Pacific oysters in Dutch

  1. Disease and disorders of freshwater unionid mussels: a brief overview of recent studies

    Directory of Open Access Journals (Sweden)

    Francesca Carella

    2016-11-01

    Full Text Available The use of aquatic invertebrates in biomedical research and as environmental sentinels has dramatically grown in recent decades, with an increased need in understanding of comparative pathology. The Unionids freshwater mussels are a group of worldwide distributed bivalves residing small ditches and ponds, lakes, canals and rivers, often used as animal test in eco-toxicological studies. Once one of the most abundant bivalve molluscs in ancient rivers around the world, now many of them are declining in many countries and consequently are nearly extinct in many areas. The causes of this decline are not fully understood but alteration and degradation of the freshwater habitat seemed to play a central role. To date, link causality to the observed losses during episode of mussel die-offs has been more difficult to establish, and disease and pathogen presence have been scarcely considered. In this article we provide a brief overview of unionids freshwater mussel conservation status, also describing reported diseases and pathogens and illustrating a few relatively well-documented studies.

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  3. The use of bivalves as rapid, real-time indicators of aquatic pollution

    International Nuclear Information System (INIS)

    Markich, S.J.

    1995-01-01

    The ability of bivalves to filter large volumes of water on a daily basis, combined with the relatively high permeability of their cell membranes, make them valuable organisms to use in the contemporary detection of pollution. Bivalves are well known to respond to chemical contaminants by isolating their soft tissues from the aquatic medium by valve closure. The sensory acuity (via specialized sensory regions including the osphradium) and associated repertoire of this behavioral response can be employed to assess subtle effects exerted by chemical contaminants, such as complex effluents, that may ultimately influence the survival of these organisms. As hazard assessment tools, behavioral studies reflect sublethal toxicity and often yield a highly sensitive estimate of the lowest observable effect concentration (LOEC). Moreover, valve movement behavior has been identified as one of the more sensitive biological early warning measures to a variety of aquatic contaminants, in comparison with those used in other aquatic animal phyla. Therefore, the valve movement behavior of both freshwater (Hyridella depressa, Velesunio angasi and V. ambiguus) and marine (Mytilus edulis) bivalves was continuously monitored, using an on-line computer based data acquisition system, during exposure to either trace metals (e.g. Cu, Cd, Mn and U) or complex effluents (ie treated sewage effluent and acid leachate derived from contaminated Sydney Harbour sediments), in the context of using the valve movement behavior of the bivalve species to indicate the biological significance of exposure to the above-mentioned pollutants. The results indicate that several components of the valve movement behavior of each bivalve provide quantifiable and ecologically interpretable sub-lethal endpoints for the rapid and sensitive evaluation of waters containing either complex effluents or elevated levels of trace metals

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-01-15

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

  5. [Radioecological studies of freshwater mollusks in the Chernobyl accident exclusion zone].

    Science.gov (United States)

    Gudkov, D I; Nazarov, A B; Dziubenko, E V; Kaglian, A E; Klenus, V G

    2009-01-01

    Species-specificity and dynamics of 90Sr, 137Cs and some transuranic elements accumulation in bivalve and gastropod freshwater molluscs of the Chernobyl exclusion zone during 1997-2008 was analyzed. The results of radiation dose and chromosome aberration rate estimation and the analysis of hemolymph composition of freshwater snail (Lymnaea stagnalis L.) was produced. The absorbed dose rate was registered in the range of 0.3-85.0 microGy/h. In closed water bodies the heightened chromosome aberration rate (up to 27%) in embryo tissues, and also the change of haematological indexes for the adult individuals of snails was registered.

  6. Genotoxic and Cytotoxic Effects on the Immune Cells of the Freshwater Bivalve Dreissena polymorpha Exposed to the Environmental Neurotoxin BMAA.

    Science.gov (United States)

    Lepoutre, Alexandra; Milliote, Nadia; Bonnard, Marc; Palos-Ladeiro, Mélissa; Rioult, Damien; Bonnard, Isabelle; Bastien, Fanny; Faassen, Elisabeth; Geffard, Alain; Lance, Emilie

    2018-03-01

    The environmental neurotoxin β- N -Methylamino-l-alanine (BMAA) has been pointed out to be involved in human neurodegenerative diseases. This molecule is known to be bioaccumulated by bivalves. However, little data about its toxic effects on freshwater mussels is available, particularly on the hemolymphatic compartment and its hemocyte cells involved in various physiological processes such as immune defenses, digestion and excretion, tissue repair, and shell production. Here we exposed Dreissena polymorpha to dissolved BMAA, at the environmental concentration of 7.5 µg of /mussel/3 days, during 21 days followed by 14 days of depuration in clear water, with the objective of assessing the BMAA presence in the hemolymphatic compartment, as well as the impact of the hemocyte cells in terms of potential cytotoxicity, immunotoxicity, and genotoxiciy. Data showed that hemocytes were in contact with BMAA. The presence of BMAA in hemolymph did not induce significant effect on hemocytes phagocytosis activity. However, significant DNA damage on hemocytes occurred during the first week (days 3 and 8) of BMAA exposure, followed by an increase of hemocyte mortality after 2 weeks of exposure. Those effects might be an indirect consequence of the BMAA-induced oxidative stress in cells. However, DNA strand breaks and mortality did not persist during the entire exposure, despite the BMAA persistence in the hemolymph, suggesting potential induction of some DNA-repair mechanisms.

  7. Genotoxic and Cytotoxic Effects on the Immune Cells of the Freshwater Bivalve Dreissena polymorpha Exposed to the Environmental Neurotoxin BMAA

    Directory of Open Access Journals (Sweden)

    Alexandra Lepoutre

    2018-03-01

    Full Text Available The environmental neurotoxin β-N-Methylamino-l-alanine (BMAA has been pointed out to be involved in human neurodegenerative diseases. This molecule is known to be bioaccumulated by bivalves. However, little data about its toxic effects on freshwater mussels is available, particularly on the hemolymphatic compartment and its hemocyte cells involved in various physiological processes such as immune defenses, digestion and excretion, tissue repair, and shell production. Here we exposed Dreissena polymorpha to dissolved BMAA, at the environmental concentration of 7.5 µg of /mussel/3 days, during 21 days followed by 14 days of depuration in clear water, with the objective of assessing the BMAA presence in the hemolymphatic compartment, as well as the impact of the hemocyte cells in terms of potential cytotoxicity, immunotoxicity, and genotoxiciy. Data showed that hemocytes were in contact with BMAA. The presence of BMAA in hemolymph did not induce significant effect on hemocytes phagocytosis activity. However, significant DNA damage on hemocytes occurred during the first week (days 3 and 8 of BMAA exposure, followed by an increase of hemocyte mortality after 2 weeks of exposure. Those effects might be an indirect consequence of the BMAA-induced oxidative stress in cells. However, DNA strand breaks and mortality did not persist during the entire exposure, despite the BMAA persistence in the hemolymph, suggesting potential induction of some DNA-repair mechanisms.

  8. Bioavailability and toxicity of metals from a contaminated sediment by acid mine drainage: linking exposure-response relationships of the freshwater bivalve Corbicula fluminea to contaminated sediment.

    Science.gov (United States)

    Sarmiento, Aguasanta M; Bonnail, Estefanía; Nieto, José Miguel; DelValls, Ángel

    2016-11-01

    Streams and rivers strongly affected by acid mine drainage (AMD) have legal vacuum in terms of assessing the water toxicity, since the use of conventional environmental quality biomarkers is not possible due to the absence of macroinvertebrate organisms. The Asian clam Corbicula fluminea has been widely used as a biomonitor of metal contamination by AMD in freshwater systems. However, these clams are considered an invasive species in Spain and the transplantation in the field study is not allowed by the Environmental Protection Agency. To evaluate the use of the freshwater bivalve C. fluminea as a potential biomonitor for sediments contaminated by AMD, the metal bioavailability and toxicity were investigated in laboratory by exposure of clams to polluted sediments for 14 days. The studied sediments were classified as slightly contaminated with As, Cr, and Ni; moderately contaminated with Co; considerably contaminated with Pb; and heavily contaminated with Cd, Zn, and specially Cu, being reported as very toxic to Microtox. On the fourth day of the exposure, the clams exhibited an increase in concentration of Ga, Ba, Sb, and Bi (more than 100 %), followed by Co, Ni, and Pb (more than 60 %). After the fourth day, a decrease in concentration was observed for almost all metals studied except Ni. An allometric function was used to determine the relationship between the increases in metal concentration in soft tissue and the increasing bioavailable metal concentrations in sediments.

  9. Deciphering the link between doubly uniparental inheritance of mtDNA and sex determination in bivalves: Clues from comparative transcriptomics

    Science.gov (United States)

    Capt, Charlotte; Renaut, Sébastien; Ghiselli, Fabrizio; Milani, Liliana; Johnson, Nathan A.; Sietman, Bernard E.; Stewart, Donald; Breton, Sophie

    2018-01-01

    Bivalves exhibit an astonishing diversity of sexual systems and sex-determining mechanisms. They can be gonochoric, hermaphroditic or androgenetic, with both genetic and environmental factors known to determine or influence sex. One unique sex-determining system involving the mitochondrial genome has also been hypothesized to exist in bivalves with doubly uniparental inheritance (DUI) of mtDNA. However, the link between DUI and sex determination remains obscure. In this study, we performed a comparative gonad transcriptomics analysis for two DUI-possessing freshwater mussel species to better understand the mechanisms underlying sex determination and DUI in these bivalves. We used a BLAST reciprocal analysis to identify orthologs between Venustaconcha ellipsiformis and Utterbackia peninsularis and compared our results with previously published sex-specific bivalve transcriptomes to identify conserved sex-determining genes. We also compared our data with other DUI species to identify candidate genes possibly involved in the regulation of DUI. A total of ∼12,000 orthologous relationships were found, with 2,583 genes differentially expressed in both species. Among these genes, key sex-determining factors previously reported in vertebrates and in bivalves (e.g., Sry, Dmrt1, Foxl2) were identified, suggesting that some steps of the sex-determination pathway may be deeply conserved in metazoans. Our results also support the hypothesis that a modified ubiquitination mechanism could be responsible for the retention of the paternal mtDNA in male bivalves, and revealed that DNA methylation could also be involved in the regulation of DUI. Globally, our results suggest that sets of genes associated with sex determination and DUI are similar in distantly-related DUI species.

  10. Microplastics in commercial bivalves from China

    International Nuclear Information System (INIS)

    Li, Jiana; Yang, Dongqi; Li, Lan; Jabeen, Khalida; Shi, Huahong

    2015-01-01

    We investigated microplastic pollution in 9 commercial bivalves from a fishery market in China. Multiple types of microplastics, including fibers, fragments and pellets, occurred in the tissue of all bivalves. The number of total microplastics varied from 2.1 to 10.5 items/g and from 4.3 to 57.2 items/individual for bivalves. Scapharca subcrenata contained on average 10.5 items/g and exhibited the highest levels of microplastics by weight. Fibers were the most common microplastics and consisted of more than half of the total microplastics in each of the 8 species. In Alectryonella plicatula, pellets accounted for 60% of the total microplastics. The most common size class was less than 250 μm and accounted for 33–84% of the total microplastics calculated by species. Our results suggest that microplastic pollution was widespread and exhibited a relatively high level in commercial bivalves from China. More intensive investigations on microplastics should be conducted in seafood. - Highlights: • Fiber, fragment and pellet microplastics were found in 9 bivalves. • The abundance of microplastics was 2.1–10.5 items/g. • Fibers were the most common microplastics. • The most common size class of microplastics was less than 250 μm. • Microplastic pollution was widespread and serious in commercial bivalves. - Fiber, fragment and pellet microplastics in the range of 2.1–10.5 items/g were observed in 9 species of commercially popular bivalves from China.

  11. Recirculation nursery systems for bivalves

    NARCIS (Netherlands)

    Kamermans, P.; Blanco Garcia, A.; Joaquim, Sandra; Matias, Domitilia; Magnesen, Thorolf; Nicolas, J.; Petten, Bruno; Robert, Rene

    2016-01-01

    n order to increase production of bivalves in hatcheries and nurseries, the development of new technology and its integration into commercial bivalve hatcheries is important. Recirculation aquaculture systems (RASs) have several advantages: high densities of the species can be cultured resulting in

  12. Ecological drivers and habitat associations of estuarine bivalves

    Directory of Open Access Journals (Sweden)

    C. Seabird McKeon

    2015-11-01

    Full Text Available Community composition of the infaunal bivalve fauna of the St. Lucie Estuary and southern Indian River Lagoon, eastern Florida was sampled quarterly for 10 years as part of a long-term benthic monitoring program. A total of 38,514 bivalves of 137 taxa were collected and identified. We utilized this data, along with sediment samples and environmental measurements gathered concurrently, to assess the community composition, distribution, and ecological drivers of the infaunal bivalves of this estuary system. Salinity had the strongest influence on bivalve assemblage across the 15 sites, superseding the influences of sediment type, water turbidity, temperature and other environmental parameters. The greatest diversity was found in higher salinity euhaline sites, while the greatest abundance of individual bivalves was found in medium salinity mixohaline sites, the lowest diversity and abundances were found in the low salinity oligohaline sites, demonstrating a strong positive association between salinity and diversity/abundance. Water management decisions for the estuary should incorporate understanding of the role of salinity on bivalve diversity, abundance, and ecosystem function.

  13. Ecological drivers and habitat associations of estuarine bivalves.

    Science.gov (United States)

    McKeon, C Seabird; Tunberg, Björn G; Johnston, Cora A; Barshis, Daniel J

    2015-01-01

    Community composition of the infaunal bivalve fauna of the St. Lucie Estuary and southern Indian River Lagoon, eastern Florida was sampled quarterly for 10 years as part of a long-term benthic monitoring program. A total of 38,514 bivalves of 137 taxa were collected and identified. We utilized this data, along with sediment samples and environmental measurements gathered concurrently, to assess the community composition, distribution, and ecological drivers of the infaunal bivalves of this estuary system. Salinity had the strongest influence on bivalve assemblage across the 15 sites, superseding the influences of sediment type, water turbidity, temperature and other environmental parameters. The greatest diversity was found in higher salinity euhaline sites, while the greatest abundance of individual bivalves was found in medium salinity mixohaline sites, the lowest diversity and abundances were found in the low salinity oligohaline sites, demonstrating a strong positive association between salinity and diversity/abundance. Water management decisions for the estuary should incorporate understanding of the role of salinity on bivalve diversity, abundance, and ecosystem function.

  14. Microplastics in commercial bivalves from China.

    Science.gov (United States)

    Li, Jiana; Yang, Dongqi; Li, Lan; Jabeen, Khalida; Shi, Huahong

    2015-12-01

    We investigated microplastic pollution in 9 commercial bivalves from a fishery market in China. Multiple types of microplastics, including fibers, fragments and pellets, occurred in the tissue of all bivalves. The number of total microplastics varied from 2.1 to 10.5 items/g and from 4.3 to 57.2 items/individual for bivalves. Scapharca subcrenata contained on average 10.5 items/g and exhibited the highest levels of microplastics by weight. Fibers were the most common microplastics and consisted of more than half of the total microplastics in each of the 8 species. In Alectryonella plicatula, pellets accounted for 60% of the total microplastics. The most common size class was less than 250 μm and accounted for 33-84% of the total microplastics calculated by species. Our results suggest that microplastic pollution was widespread and exhibited a relatively high level in commercial bivalves from China. More intensive investigations on microplastics should be conducted in seafood. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Ecological drivers and habitat associations of estuarine bivalves

    OpenAIRE

    McKeon, C. Seabird; Tunberg, Bj?rn G.; Johnston, Cora A.; Barshis, Daniel J.

    2015-01-01

    Community composition of the infaunal bivalve fauna of the St. Lucie Estuary and southern Indian River Lagoon, eastern Florida was sampled quarterly for 10 years as part of a long-term benthic monitoring program. A total of 38,514 bivalves of 137 taxa were collected and identified. We utilized this data, along with sediment samples and environmental measurements gathered concurrently, to assess the community composition, distribution, and ecological drivers of the infaunal bivalves of this es...

  16. Bivalve grazing can shape phytoplankton communities

    Science.gov (United States)

    Lucas, Lisa; Cloern, James E.; Thompson, Janet K.; Stacey, Mark T.; Koseff, Jeffrey K.

    2016-01-01

    The ability of bivalve filter feeders to limit phytoplankton biomass in shallow waters is well-documented, but the role of bivalves in shaping phytoplankton communities is not. The coupled effect of bivalve grazing at the sediment-water interface and sinking of phytoplankton cells to that bottom filtration zone could influence the relative biomass of sinking (diatoms) and non-sinking phytoplankton. Simulations with a pseudo-2D numerical model showed that benthic filter feeding can interact with sinking to alter diatom:non-diatom ratios. Cases with the smallest proportion of diatom biomass were those with the fastest sinking speeds and strongest bivalve grazing rates. Hydrodynamics modulated the coupled sinking-grazing influence on phytoplankton communities. For example, in simulations with persistent stratification, the non-sinking forms accumulated in the surface layer away from bottom grazers while the sinking forms dropped out of the surface layer toward bottom grazers. Tidal-scale stratification also influenced vertical gradients of the two groups in opposite ways. The model was applied to Suisun Bay, a low-salinity habitat of the San Francisco Bay system that was transformed by the introduction of the exotic clam Potamocorbula amurensis. Simulation results for this Bay were similar to (but more muted than) those for generic habitats, indicating that P. amurensis grazing could have caused a disproportionate loss of diatoms after its introduction. Our model simulations suggest bivalve grazing affects both phytoplankton biomass and community composition in shallow waters. We view these results as hypotheses to be tested with experiments and more complex modeling approaches.

  17. 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

  18. Immunotoxicological effects of environmental contaminants on marine bivalves.

    Science.gov (United States)

    Renault, T

    2015-09-01

    Coastal areas are complex environments frequently contaminated by numerous pollutants that represent a potential threat to marine organisms, especially bivalves. These pollutants may have major ecological consequences. Although effects of different environmental contaminants on the immune system in marine bivalves have been already reported, a few of reviews summarizes these effects. The main purpose of this chapter relies on summarizing recent body of data on immunotoxicity in bivalves subjected to contaminants. Immune effects of heavy metals, pesticides, HAP, PCB and pharmaceuticals are presented and discussed and a particular section is devoted to nanoparticle effects. A large body of literature is now available on this topic. Finally, the urgent need of a better understanding of complex interactions between contaminants, marine bivalves and infectious diseases is noticed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Artificially evolved functional shell morphology of burrowing bivalves

    DEFF Research Database (Denmark)

    Germann, D. P.; Schatz, W.; Hotz, Peter Eggenberger

    2014-01-01

    The morphological evolution of bivalves is documented by a rich fossil record. It is believed that the shell shape and surface sculpture play an important role for the burrowing performance of endobenthic species. While detailed morphometric studies of bivalve shells have been done...... dimensional (3D) objects, the first ever artificial evolution of a physical bivalve shell was performed. The result was a vertically flattened shell occupying only the top sediment layers. Insufficient control of the sediment was the major limitation of the setup and restricted the significance of the results...

  20. Persistent organic pollutants in four bivalve species from Svalbard waters

    International Nuclear Information System (INIS)

    Vieweg, Ireen; Hop, Haakon; Brey, Thomas; Huber, Sandra; Ambrose, William G.; Locke V, William L.; Gabrielsen, Geir W.

    2012-01-01

    Organochlorine compounds (OC) were determined in Arctic bivalves (Mya truncata, Serripes groenlandicus, Hiatella arctica and Chlamys islandica) from Svalbard with regard to differences in geographic location, species and variations related to their size and age. Higher chlorinated polychlorinated biphenyls (PCB 101–PCB 194), chlordanes and α-hexachlorocyclohexane (α-HCH) were consistently detected in the bivalves and PCBs dominated the OC load in the organisms. OC concentrations were highest in Mya truncata and the lowest in Serripes groenlandicus. Species-specific OC levels were likely related to differences in the species’ food source, as indicated by the δ 13 C results, rather than size and age. Higher OC concentrations were observed in bivalves from Kongsfjorden compared to the northern sampling locations Liefdefjorden and Sjuøyane. The spatial differences might be related to different water masses influencing Kongsfjorden (Atlantic) and the northern locations (Arctic), with differing phytoplankton bloom situations. - Highlights: ► Organochlorine compounds (OC) were analyzed in 4 bivalve species from Svalbard. ► Polychlorinated biphenyls dominated the OC load observed in the bivalves. ► Atlantic water influenced bivalves had higher OC levels than those from Arctic water. ► Location and species, rather than size and age, determined the OC pattern found. - New findings of organochlorines in Arctic bivalves that are central for evaluating the importance of geographical location and species for the organochlorine pattern in benthic organisms.

  1. Metabolites of saxitoxin analogues in bivalves contaminated by Gymnodinium catenatum.

    Science.gov (United States)

    Vale, Paulo

    2010-01-01

    Bivalve metabolites of saxitoxin analogues, not present in microalgae, were recently described as an important toxin fraction in mussels contaminated by Alexandrium tamarense. These possess very low fluorescence, and require mass spectrometry detection. HILIC-MS was implemented to look for these metabolites in bivalves contaminated during Gymnodinium catenatum blooms at the Portuguese coast. The presence of M1 was tentatively identified in several bivalves, ranging from estuarine (Mytilus galloprovinciallis, Cerastoderma edule and Ruditapes decussatus) to oceanic habitat (Donax trunculus and Ensis spp.). It was hypothesized that M1 could contribute to an important fraction of the profile of STX analogues. M1 was more abundant in estuarine bivalves that retain longer PSP toxins, in the following order: mussels>cockles>clams. These data highlight that the study by fluorimetry alone of the carbamoyl, N-sulfocarbamoyl, and decarbamoyl families is manifestly insufficient to fully understand toxin dynamics in bivalves feeding on G. catenatum without a proper study of hydroxybenzoate and hydroxylated M-toxins.

  2. Microbial Diseases of Bivalve Mollusks: Infections, Immunology and Antimicrobial Defense.

    Science.gov (United States)

    Zannella, Carla; Mosca, Francesco; Mariani, Francesca; Franci, Gianluigi; Folliero, Veronica; Galdiero, Marilena; Tiscar, Pietro Giorgio; Galdiero, Massimiliano

    2017-06-17

    A variety of bivalve mollusks (phylum Mollusca, class Bivalvia) constitute a prominent commodity in fisheries and aquacultures, but are also crucial in order to preserve our ecosystem's complexity and function. Bivalve mollusks, such as clams, mussels, oysters and scallops, are relevant bred species, and their global farming maintains a high incremental annual growth rate, representing a considerable proportion of the overall fishery activities. Bivalve mollusks are filter feeders; therefore by filtering a great quantity of water, they may bioaccumulate in their tissues a high number of microorganisms that can be considered infectious for humans and higher vertebrates. Moreover, since some pathogens are also able to infect bivalve mollusks, they are a threat for the entire mollusk farming industry. In consideration of the leading role in aquaculture and the growing financial importance of bivalve farming, much interest has been recently devoted to investigate the pathogenesis of infectious diseases of these mollusks in order to be prepared for public health emergencies and to avoid dreadful income losses. Several bacterial and viral pathogens will be described herein. Despite the minor complexity of the organization of the immune system of bivalves, compared to mammalian immune systems, a precise description of the different mechanisms that induce its activation and functioning is still missing. In the present review, a substantial consideration will be devoted in outlining the immune responses of bivalves and their repertoire of immune cells. Finally, we will focus on the description of antimicrobial peptides that have been identified and characterized in bivalve mollusks. Their structural and antimicrobial features are also of great interest for the biotechnology sector as antimicrobial templates to combat the increasing antibiotic-resistance of different pathogenic bacteria that plague the human population all over the world.

  3. A novel filtering mutualism between a sponge host and its endosymbiotic bivalves.

    Science.gov (United States)

    Tsubaki, Remi; Kato, Makoto

    2014-01-01

    Sponges, porous filter-feeding organisms consisting of vast canal systems, provide unique substrates for diverse symbiotic organisms. The Spongia (Spongia) sp. massive sponge is obligately inhabited by the host-specific endosymbiotic bivalve Vulsella vulsella, which benefits from this symbiosis by receiving protection from predators. However, whether the host sponge gains any benefit from this association is unclear. Considering that the bivalves exhale filtered water into the sponge body rather than the ambient environment, the sponge is hypothesized to utilize water exhaled by the bivalves to circulate water around its body more efficiently. We tested this hypothesis by observing the sponge aquiferous structure and comparing the pumping rates of sponges and bivalves. Observations of water currents and the sponge aquiferous structure revealed that the sponge had a unique canal system enabling it to inhale water exhaled from bivalves, indicating that the host sponge adapted morphologically to receive water from the bivalves. In addition, the volume of water circulating in the sponge body was dramatically increased by the water exhaled from bivalves. Therefore, this sponge-bivalve association can be regarded as a novel mutualism in which two filter-feeding symbionts promote mutual filtering rates. This symbiotic association should be called a "filtering mutualism".

  4. Mercury accumulation in marine bivalves: Influences of biodynamics and feeding niche

    Energy Technology Data Exchange (ETDEWEB)

    Pan Ke [Division of Life Science, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon (Hong Kong); Wang Wenxiong, E-mail: wwang@ust.hk [Division of Life Science, Hong Kong University of Science and Technology (HKUST), Clear Water Bay, Kowloon (Hong Kong)

    2011-10-15

    Differences in the accumulation of mercury (Hg) in five species of marine bivalves, including scallops Chlamys nobilis, clams Ruditapes philippinarum, oysters Saccostrea cucullata, green mussels Perna viridis, and black mussels Septifer virgatus, were investigated. The bivalves displayed different patterns of Hg accumulation in terms of the body concentrations of methylmercury (MeHg) and total Hg (THg), as well as the ratio of MeHg to THg. Parameters of the biodynamics of the accumulation of Hg(II) and MeHg could reflect the species-dependent Hg concentrations in the bivalves. With the exception of black mussels, we found a significant relationship between the efflux rates of Hg(II) and the THg concentrations in the bivalves. The interspecific variations in the MeHg to THg ratio were largely controlled by the relative difference between the elimination rates of Hg(II) and MeHg. Stable isotope ({delta}{sup 13}C) analysis indicated that the five bivalve species had contrasting feeding niches, which may also affect the Hg accumulation. - Highlights: > Significant difference in Hg accumulation and MeHg:THg ratio in different bivalves. > THg concentrations in the bivalves were generally related to the efflux rates of Hg(II). > Elimination of Hg(II) and MeHg controlled the interspecific variation in MeHg:THg ratio. > MeHg and THg concentrations reflect the interaction of Hg biodynamics and food. - The species-specific body concentrations of MeHg and THg in bivalves reflect the complicated interaction between the biodynamics of Hg(II) and MeHg and the different food sources.

  5. Environmental influences on the composition and structure of the freshwater mussels in shallow lakes in the Cuiabá River floodplain

    Directory of Open Access Journals (Sweden)

    AC. Colle

    Full Text Available The maintenance of the freshwater mussels' community in lakes is determined by abiotic factors at the local scale and at regional scale by interspecific relations between the larvae of bivalves and fish host. Whereas the distribution pattern at local scale, our goal was to understand the abundance and community composition of bivalves and relate the environmental agents structuring this community. We sampled 20 lakes in the floodplain of the Cuiabá River using a standardized method of sampling. To evaluate the effect of environment on the community we applied multivariate inferential analyses. We found 1.143 individuals alive belonging into six species distributed at the family Hyriidae, Mycetopodidae, Sphaeridae and Corbiculidae. The results showed that in the Pantanal the bivalve assemblage structure is influenced locally by organic matter and particle size, variables that reflect the intense interactions between water-sediment. However it is important to emphasize that these environmental characteristics are the result of the dynamics of this system which is dependent on the flood pulse, a regional factor.

  6. Evaluation of γ-radiation-induced DNA damage in two species of bivalves and their relative sensitivity using comet assay.

    Science.gov (United States)

    Praveen Kumar, M K; Shyama, S K; Sonaye, B S; Naik, U Roshini; Kadam, S B; Bipin, P D; D'costa, A; Chaubey, R C

    2014-05-01

    Ionizing radiation is known to induce genetic damage in diverse groups of organisms. Under accidental situations, large quantities of radioactive elements get released into the environment and radiation emitted from these radionuclides may adversely affect both the man and the non-human biota. The present study is aimed (a) to know the genotoxic effect of gamma radiation on aquatic fauna employing two species of selected bivalves, (b) to evaluate the possible use of 'Comet assay' for detecting genetic damage in haemocytes of bivalves as a biomarker for environmental biomonitoring and also (c) to compare the relative sensitivity of two species of bivalves viz. Paphia malabarica and Meretrix casta to gamma radiation. The comet assays was optimized and validated using different concentrations (18, 32 and 56 mg/L) of ethyl methanesulfonate (EMS), a direct-acting reference genotoxic agent, to which the bivalves were exposed for various times (24, 48 and 72 h). Bivalves were irradiated (single acute exposure) with 5 different doses (viz. 2, 4, 6, 8 and 10 Gy) of gamma radiation and their genotoxic effects on the haemocytes were studied using the comet assay. Haemolymph was collected from the adductor muscle at 24, 48 and 72 h of both EMS-exposed and irradiated bivalves and comet assay was carried out using standard protocol. A significant increase in DNA damage was observed as indicated by an increase in % tail DNA damage at different concentrations of EMS and all the doses of gamma radiation as compared to controls in both bivalve species. This showed a dose-dependent increase of genetic damage induced in bivalves by EMS as well as gamma radiation. Further, the highest DNA damage was observed at 24h. The damage gradually decreased with time, i.e. was smaller at 48 and 72 h than at 24h post irradiation in both species of bivalves. This may indicate repair of the damaged DNA and/or loss of heavily damaged cells as the post irradiation time advanced. The present study

  7. Evaluation of γ-radiation-induced DNA damage in two species of bivalves and their relative sensitivity using comet assay

    International Nuclear Information System (INIS)

    Praveen Kumar, M.K.; Shyama, S.K.; Sonaye, B.S.; Naik, U Roshini; Kadam, S.B.; Bipin, P.D.; D’costa, A.; Chaubey, R.C.

    2014-01-01

    both bivalve species. This showed a dose-dependent increase of genetic damage induced in bivalves by EMS as well as gamma radiation. Further, the highest DNA damage was observed at 24 h. The damage gradually decreased with time, i.e. was smaller at 48 and 72 h than at 24 h post irradiation in both species of bivalves. This may indicate repair of the damaged DNA and/or loss of heavily damaged cells as the post irradiation time advanced. The present study reveals that gamma radiation induces single strand breaks in DNA as measured by alkaline comet assay in bivalves and comet assay serves as a sensitive and rapid method to detect genotoxicity of gamma radiation. This study further indicates that both M. casta and P. malabarica exhibit almost identical sensitivity to gamma radiation as measured by DNA damage

  8. Evaluation of γ-radiation-induced DNA damage in two species of bivalves and their relative sensitivity using comet assay

    Energy Technology Data Exchange (ETDEWEB)

    Praveen Kumar, M.K., E-mail: here.praveen@gmail.com [Department of Zoology, Goa University, Goa 403206 (India); Shyama, S.K., E-mail: skshyama@gmail.com [Department of Zoology, Goa University, Goa 403206 (India); Sonaye, B.S. [Department of Radiation Oncology, Goa Medical College, Goa (India); Naik, U Roshini; Kadam, S.B.; Bipin, P.D.; D’costa, A. [Department of Zoology, Goa University, Goa 403206 (India); Chaubey, R.C. [Radiation Biology and Health Science Division, Bhabha Atomic Research Centre, Mumbai (India)

    2014-05-01

    both bivalve species. This showed a dose-dependent increase of genetic damage induced in bivalves by EMS as well as gamma radiation. Further, the highest DNA damage was observed at 24 h. The damage gradually decreased with time, i.e. was smaller at 48 and 72 h than at 24 h post irradiation in both species of bivalves. This may indicate repair of the damaged DNA and/or loss of heavily damaged cells as the post irradiation time advanced. The present study reveals that gamma radiation induces single strand breaks in DNA as measured by alkaline comet assay in bivalves and comet assay serves as a sensitive and rapid method to detect genotoxicity of gamma radiation. This study further indicates that both M. casta and P. malabarica exhibit almost identical sensitivity to gamma radiation as measured by DNA damage.

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

    African Journals Online (AJOL)

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

  10. Bio-accumulation kinetics of radioruthenium in marine bivalves. Laboratory study

    International Nuclear Information System (INIS)

    Mu, D.H.; Yan, S.P.; Gu, Y.J.; Li, D.J.; Du, J.Z.

    2007-01-01

    Three kinds of marine bivalves (wild Saccostrea cucullata, aquacultured Perna viridis and aquacultured Pinctada martens), collected from Daya Bay, the South China Sea, were used to investigate the bio-accumulation of radioruthenium in the glass aquarium with natural seawater (pH 8.20, 35 per mille salinity, filtered by 0.45 μm) at ambient temperature under laboratory feeding conditions. The experimental results show that the stead-state of biology concentration factor (BCF, ml/g) of radioruthenium was approached around 6 days for most species of bivalves. The values of BCF in shells are the highest in organs all the three bivalves. The orders of BCF values (ml x g -1 ) are as: Perna viridis (33.2) < Saccostrea cucullata (47.0) < Pinctada martensi (208.4) for shells and Saccostrea cucullata (1.5) < Pinctada martensi (2.2) ∼ Perma viridis (2.4) for soft tissues, respectively, after exposed for 14 days. The rate constants of uptake and elimination of radioruthenium on marine bivalves were also discussed by first-order kinetics model. The Pinctada martensi may be applicable to be an indictor for monitoring radioruthenium among the three bivalves. (author)

  11. Galeommatid bivalves from Phuket, Thailand

    DEFF Research Database (Denmark)

    Lützen, Jørgen; Nielsen, Claus

    2005-01-01

    Twenty-seven species of galeommatid bivalves from six genera have been collected at intertidal reef flats near Phuket Marine Biological Center, Thailand (Andaman Sea, Indian Ocean). Fourteen of the species are new to science and a new genus (Nudiscintilla gen. nov.) has been established. The spec......Twenty-seven species of galeommatid bivalves from six genera have been collected at intertidal reef flats near Phuket Marine Biological Center, Thailand (Andaman Sea, Indian Ocean). Fourteen of the species are new to science and a new genus (Nudiscintilla gen. nov.) has been established...... crustacean, the remainder hide under shale, rocks and coral blocks, often in small intra- or interspecific family flocks. The behaviour was also noted for some of the species. It is presumed that galeommatid species go through a lengthy planktonic phase....

  12. Uranium(VI) speciation: modelling, uncertainty and relevance to bioavailability models. Application to uranium uptake by the gills of a freshwater bivalve

    International Nuclear Information System (INIS)

    Denison, F.H.

    2004-07-01

    The effects of varying solution composition on the interactions between uranium(VI) and excised gills of the freshwater bivalve Corbicula fluminea have been investigated in well defined solution media. A significant reduction in the uptake of uranium was observed on increasing the concentrations of the uranium complexing ligands citrate and carbonate. Saturation kinetics as a function of uranium concentration at a pH value of 5.0 were observed, indicating that the uptake of uranium is a facilitated process, probably involving one or several trans-membrane transport systems. A relatively small change in the uptake of uranium was found as a function of pH (factor of ca. 2), despite the extremely large changes to the solution speciation of uranium within the range of pH investigated (5.0 - 7.5). A comprehensive review of the thermodynamic data relevant to the solution composition domain employed for this study was performed. Estimates of the uncertainties for the formation constants of aqueous uranium(VI) species were integrated into a thermodynamic database. A computer program was written to predict the equilibrium distribution of uranium(VI) in simple aqueous systems, using thermodynamic parameter mean-values. The program was extended to perform Monte Carlo and Quasi Monte Carlo uncertainty analyses, incorporating the thermodynamic database uncertainty estimates, to quantitatively predict the uncertainties inherent in predicting the solution speciation of uranium. The use of thermodynamic equilibrium modelling as a tool for interpreting the bioavailability of uranium(VI) was investigated. Observed uranium(VI) uptake behaviour was interpreted as a function of the predicted changes to the solution speciation of uranium. Different steady-state or pre-equilibrium approaches to modelling uranium uptake were tested. Alternative modelling approaches were also tested, considering the potential changes to membrane transport system activity or sorption characteristics on

  13. Modeling the carbon isotope composition of bivalve shells (Invited)

    Science.gov (United States)

    Romanek, C.

    2010-12-01

    The stable carbon isotope composition of bivalve shells is a valuable archive of paleobiological and paleoenvironmental information. Previous work has shown that the carbon isotope composition of the shell is related to the carbon isotope composition of dissolved inorganic carbon (DIC) in the ambient water in which a bivalve lives, as well as metabolic carbon derived from bivalve respiration. The contribution of metabolic carbon varies among organisms, but it is generally thought to be relatively low (e.g., 90%) in the shells from terrestrial organisms. Because metabolic carbon contains significantly more C-12 than DIC, negative excursions from the expected environmental (DIC) signal are interpreted to reflect an increased contribution of metabolic carbon in the shell. This observation contrasts sharply with modeled carbon isotope compositions for shell layers deposited from the inner extrapallial fluid (EPF). Previous studies have shown that growth lines within the inner shell layer of bivalves are produced during periods of anaerobiosis when acidic metabolic byproducts (e.g., succinic acid) are neutralized (or buffered) by shell dissolution. This requires the pH of EPF to decrease below ambient levels (~7.5) until a state of undersaturation is achieved that promotes shell dissolution. This condition may occur when aquatic bivalves are subjected to external stressors originating from ecological (predation) or environmental (exposure to atm; low dissolved oxygen; contaminant release) pressures; normal physiological processes will restore the pH of EPF when the pressure is removed. As a consequence of this process, a temporal window should also exist in EPF at relatively low pH where shell carbonate is deposited at a reduced saturation state and precipitation rate. For example, EPF chemistry should remain slightly supersaturated with respect to aragonite given a drop of one pH unit (6.5), but under closed conditions, equilibrium carbon isotope fractionation

  14. Mercury in freshwater ecosystems of the Canadian Arctic: recent advances on its cycling and fate.

    Science.gov (United States)

    Chételat, John; Amyot, Marc; Arp, Paul; Blais, Jules M; Depew, David; Emmerton, Craig A; Evans, Marlene; Gamberg, Mary; Gantner, Nikolaus; Girard, Catherine; Graydon, Jennifer; Kirk, Jane; Lean, David; Lehnherr, Igor; Muir, Derek; Nasr, Mina; Poulain, Alexandre J; Power, Michael; Roach, Pat; Stern, Gary; Swanson, Heidi; van der Velden, Shannon

    2015-03-15

    The Canadian Arctic has vast freshwater resources, and fish are important in the diet of many Northerners. Mercury is a contaminant of concern because of its potential toxicity and elevated bioaccumulation in some fish populations. Over the last decade, significant advances have been made in characterizing the cycling and fate of mercury in these freshwater environments. Large amounts of new data on concentrations, speciation and fluxes of Hg are provided and summarized for water and sediment, which were virtually absent for the Canadian Arctic a decade ago. The biogeochemical processes that control the speciation of mercury remain poorly resolved, including the sites and controls of methylmercury production. Food web studies have examined the roles of Hg uptake, trophic transfer, and diet for Hg bioaccumulation in fish, and, in particular, advances have been made in identifying determinants of mercury levels in lake-dwelling and sea-run forms of Arctic char. In a comparison of common freshwater fish species that were sampled across the Canadian Arctic between 2002 and 2009, no geographic patterns or regional hotspots were evident. Over the last two to four decades, Hg concentrations have increased in some monitored populations of fish in the Mackenzie River Basin while other populations from the Yukon and Nunavut showed no change or a slight decline. The different Hg trends indicate that the drivers of temporal change may be regional or habitat-specific. The Canadian Arctic is undergoing profound environmental change, and preliminary evidence suggests that it may be impacting the cycling and bioaccumulation of mercury. Further research is needed to investigate climate change impacts on the Hg cycle as well as biogeochemical controls of methylmercury production and the processes leading to increasing Hg levels in some fish populations in the Canadian Arctic. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

  15. Artificially evolved functional shell morphology of burrowing bivalves

    DEFF Research Database (Denmark)

    Germann, D. P.; Schatz, W.; Hotz, Peter Eggenberger

    2014-01-01

    dimensional (3D) objects, the first ever artificial evolution of a physical bivalve shell was performed. The result was a vertically flattened shell occupying only the top sediment layers. Insufficient control of the sediment was the major limitation of the setup and restricted the significance of the results......, there are almost no studies experimentally testing their dynamic properties. To investigate the functional morphology of the bivalve shell, we employed a synthetic methodology and built an experimental setup to simulate the burrowing process. Using an evolutionary algorithm and a printer that prints three...

  16. Veda-scope: More comfortable than the bivalve speculum and cytologically equivalent.

    Science.gov (United States)

    Longmore, Peter G

    2004-04-01

    The aim of the present study was to confirm that the Veda-scope is equivalent to the bivalve speculum in the collection of endocervical cells, as confirmation of adequate cervical sampling for Pap smear testing. The study also aimed to assess the comfort level of the Veda-scope compared to the traditional bivalve speculum and the patient preference of the Veda-scope compared to the bivalve speculum. Multicentre, randomised, controlled crossover, cytologist blinded study. The total number of subjects enrolled in the study were 250. The number of evaluable subjects were 210. In primary efficacy analysis, no significant difference was seen between the presence or absence of endocervical cells in the smears using either the Veda-scope or the bivalve speculum. There was a high concordance level between the diagnosis assigned to each specimen of a paired sample, the diagnosis agreeing in 97.6% cases. The primary reason given by many women for avoidance of regular Pap smear examinations is the discomfort or pain experienced with sample collection with the bivalve speculum. In the present study, 92% of subjects indicated a preference for the Veda-scope for Pap smear collection, while only 8.4% preferred the bivalve speculum. Subject preference was also assessed with respect to how the subject rated the comfort level of her previous Pap smear. In subjects who rated their previous Pap smear as very comfortable or comfortable, 86% expressed a preference for the Veda-scope. This rose to 93% in subjects who rated their previous Pap smear as only tolerable. The results of the present study show that Pap smear collections with the Veda-scope are of equal quality to those collected with the bivalve speculum, with an equivalent diagnostic outcome. A very strong preference for the Veda-scope was shown by the women enrolled in the present study based on the comfort levels experienced with the two devices.

  17. First evidence of immunomodulation in bivalves under seawater acidification and increased temperature.

    Directory of Open Access Journals (Sweden)

    Valerio Matozzo

    Full Text Available Water acidification, temperature increases and changes in seawater salinity are predicted to occur in the near future. In such a global climate change (GCC scenario, there is growing concern for the health status of both wild and farmed organisms. Bivalve molluscs, an important component of coastal marine ecosystems, are at risk. At the immunological level, the ability of an organism to maintain its immunosurveillance unaltered under adverse environmental conditions may enhance its survival capability. To our knowledge, only a few studies have investigated the effects of changing environmental parameters (as predicted in a GCC scenario on the immune responses of bivalves. In the present study, the effects of both decreased pH values and increased temperature on the important immune parameters of two bivalve species were evaluated for the first time. The clam Chamelea gallina and the mussel Mytilus galloprovincialis, widespread along the coast of the Northwestern Adriatic Sea, were chosen as model organisms. Bivalves were exposed for 7 days to three pH values (8.1, 7.7 and 7.4 at two temperatures (22 and 28°C. Three independent experiments were carried out at salinities of 28, 34 and 40 PSU. The total haemocyte count, Neutral Red uptake, haemolymph lysozyme activity and total protein levels were measured. The results obtained demonstrated that tested experimental conditions affected significantly most of the immune parameters measured in bivalves, even if the variation pattern of haemocyte responses was not always linear. Between the two species, C. gallina appeared more vulnerable to changing pH and temperature than M. galloprovincialis. Overall, this study demonstrated that climate changes can strongly affect haemocyte functionality in bivalves. However, further studies are needed to clarify better the mechanisms of action of changing environmental parameters, both individually and in combination, on bivalve haemocytes.

  18. Oxidative stress and histological changes following exposure to diamond nanoparticles in the freshwater Asian clam Corbicula fluminea (Müller, 1774)

    International Nuclear Information System (INIS)

    Cid, Antonio; Picado, Ana; Correia, José Brito; Chaves, Rúben; Silva, Héber; Caldeira, Jorge; Alves de Matos, António P.

    2015-01-01

    Highlights: • We assess the toxicity of NDs in the bivalve Corbiculafluminea. • Exposure to NDs cause a stress oxidative response. • Stress oxidative enzymes increase following exposure to nanodiamonds. • Increase in lipid peroxidation suggests damage in cells membranes. • Histopathology reveals alterations in digestive gland cells. - Abstract: Recently, the scientific community became aware of the potential ability of nanoparticles to cause toxicity in living organisms. Therefore, many of the implications for aquatic ecosystems and its effects on living organisms are still to be evaluated and fully understood. In this study, the toxicity of nanodiamonds (NDs) was assessed in the freshwater bivalve (Corbicula fluminea) following exposure to different nominal concentrations of NDs (0.01, 0.1, 1, and 10 mg l −1 ) throughout 14 days. The NDs were characterized (gravimetry, pH, zeta potential, electron microscopy, and atomic force microscopy) confirming manufacturer information and showing NDs with a size of 4–6 nm. Oxidative stress enzymes activities (glutathione-S-transferase, catalase) and lipid peroxidation were determined. The results show a trend to increase in GST activities after seven days of exposure in bivalves exposed to NDs concentrations (>0.1 mg l −1 ), while for catalase a significant increase was found in bivalves exposed from 0.01 to 1.0 mg l −1 following an exposure of 14 days. The histological analysis revealed alterations in digestive gland cells, such as vacuolization and thickening. The lipid peroxidation showed a trend to increase for the different tested NDs concentrations which is compatible with the observed cellular damage

  19. Oxidative stress and histological changes following exposure to diamond nanoparticles in the freshwater Asian clam Corbicula fluminea (Müller, 1774)

    Energy Technology Data Exchange (ETDEWEB)

    Cid, Antonio [REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnología, Centro de Química Fina e Biotecnología, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Picado, Ana; Correia, José Brito [LNEG-Laboratório Nacional de Energia e Geologia, I.P. Estrada do Paço do Lumiar 22, 1649-038 Lisboa (Portugal); Chaves, Rúben; Silva, Héber [Centro de Investigação Interdisciplinar Egas Moniz, Instituto Superior de Ciências da Saúde Egas Moniz, 2825-511 Caparica (Portugal); Caldeira, Jorge [REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnología, Centro de Química Fina e Biotecnología, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Centro de Investigação Interdisciplinar Egas Moniz, Instituto Superior de Ciências da Saúde Egas Moniz, 2825-511 Caparica (Portugal); Alves de Matos, António P. [Centro de Investigação Interdisciplinar Egas Moniz, Instituto Superior de Ciências da Saúde Egas Moniz, 2825-511 Caparica (Portugal); Centro de Estudos do Ambiente e do Mar (CESAM/FCUL)—Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa (Portugal); and others

    2015-03-02

    Highlights: • We assess the toxicity of NDs in the bivalve Corbiculafluminea. • Exposure to NDs cause a stress oxidative response. • Stress oxidative enzymes increase following exposure to nanodiamonds. • Increase in lipid peroxidation suggests damage in cells membranes. • Histopathology reveals alterations in digestive gland cells. - Abstract: Recently, the scientific community became aware of the potential ability of nanoparticles to cause toxicity in living organisms. Therefore, many of the implications for aquatic ecosystems and its effects on living organisms are still to be evaluated and fully understood. In this study, the toxicity of nanodiamonds (NDs) was assessed in the freshwater bivalve (Corbicula fluminea) following exposure to different nominal concentrations of NDs (0.01, 0.1, 1, and 10 mg l{sup −1}) throughout 14 days. The NDs were characterized (gravimetry, pH, zeta potential, electron microscopy, and atomic force microscopy) confirming manufacturer information and showing NDs with a size of 4–6 nm. Oxidative stress enzymes activities (glutathione-S-transferase, catalase) and lipid peroxidation were determined. The results show a trend to increase in GST activities after seven days of exposure in bivalves exposed to NDs concentrations (>0.1 mg l{sup −1}), while for catalase a significant increase was found in bivalves exposed from 0.01 to 1.0 mg l{sup −1} following an exposure of 14 days. The histological analysis revealed alterations in digestive gland cells, such as vacuolization and thickening. The lipid peroxidation showed a trend to increase for the different tested NDs concentrations which is compatible with the observed cellular damage.

  20. The isotopic biosignatures of photo- vs. thiotrophic bivalves: are they preserved in fossil shells?

    Science.gov (United States)

    Dreier, A; Loh, W; Blumenberg, M; Thiel, V; Hause-Reitner, D; Hoppert, M

    2014-09-01

    Symbiont-bearing and non-symbiotic marine bivalves were used as model organisms to establish biosignatures for the detection of distinctive symbioses in ancient bivalves. For this purpose, the isotopic composition of lipids (δ13C) and bulk organic shell matrix (δ13C, δ34S, δ15N) from shells of several thiotrophic, phototrophic, or non-symbiotic bivalves were compared (phototrophic: Fragum fragum, Fragum unedo, Tridacna maxima; thiotrophic: Codakia tigerina, Fimbria fimbriata, Anodontia sp.; non-symbiotic: Tapes dorsatus, Vasticardium vertebratum, Scutarcopagia sp.). ∆13C values of bulk organic shell matrices, most likely representing mainly original shell protein/chitin biomass, were depleted in thio- and phototrophic bivalves compared to non-symbiotic bivalves. As the bulk organic shell matrix also showed a major depletion of δ15N (down to -2.2 ‰) for thiotrophic bivalves, combined δ13C and δ15N values are useful to differentiate between thio-, phototrophic, and non-symbiotic lifestyles. However, the use of these isotopic signatures for the study of ancient bivalves is limited by the preservation of the bulk organic shell matrix in fossils. Substantial alteration was clearly shown by detailed microscopic analyses of fossil (late Pleistocene) T. maxima and Trachycardium lacunosum shell, demonstrating a severe loss of quantity and quality of bulk organic shell matrix with time. Likewise, the composition and δ13C-values of lipids from empty shells indicated that a large part of these compounds derived from prokaryotic decomposers. The use of lipids from ancient shells for the reconstruction of the bivalve's life style therefore appears to be restricted. © 2014 John Wiley & Sons Ltd.

  1. Trace Fossil Evidence of Trematode-Bivalve Parasite-Host Interactions in Deep Time.

    Science.gov (United States)

    Huntley, John Warren; De Baets, Kenneth

    2015-01-01

    Parasitism is one of the most pervasive phenomena amongst modern eukaryotic life and yet, relative to other biotic interactions, almost nothing is known about its history in deep time. Digenean trematodes (Platyhelminthes) are complex life cycle parasites, which have practically no body fossil record, but induce the growth of characteristic malformations in the shells of their bivalve hosts. These malformations are readily preserved in the fossil record, but, until recently, have largely been overlooked by students of the fossil record. In this review, we present the various malformations induced by trematodes in bivalves, evaluate their distribution through deep time in the phylogenetic and ecological contexts of their bivalve hosts and explore how various taphonomic processes have likely biased our understanding of trematodes in deep time. Trematodes are known to negatively affect their bivalve hosts in a number of ways including castration, modifying growth rates, causing immobilization and, in some cases, altering host behaviour making the host more susceptible to their own predators. Digeneans are expected to be significant agents of natural selection. To that end, we discuss how bivalves may have adapted to their parasites via heterochrony and suggest a practical methodology for testing such hypotheses in deep time. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. The Bivalve Production Chain in Santa Catarina, Brazil, and its Management and Operational Limitations

    OpenAIRE

    Gallon, Alessandra Vasconcelos; Universidade Federal do Ceará (UFC); Nascimento, Cristiano; Universidade Federal do Paraná - UFPR; Pfitscher, Elisete Dahmer; Universidade Federal de Santa Catarina

    2011-01-01

    Bivalve farming (mussels and oysters), a major component in the socio-economic development of the state of Santa Catarina, Brazil, combines the activities of public and private agencies in fish farming. Current analysis deals with the management and the operational limitations of the local bivalve production chain. Current exploratory research, undertaken by direct observations and the literature on the subject, employs data quality. Results show that the bivalve production chain, comprising ...

  3. Predation and habitat modification synergistically interact to control bivalve recruitment on intertidal mudflats

    NARCIS (Netherlands)

    van der Heide, T.; Tielens, E.; van der Zee, E.M.; Weerman, E.J.; Holthuijsen, S.; Eriksson, B.K.; Piersma, T.; van de Koppel, J.; Olff, H.

    2014-01-01

    Bivalves are key components of coastal ecosystems because they link pelagic and benthic food webs, and shape the landscape through habitat modification. Nevertheless, many bivalve stocks have dramatically declined, and recruitment failure due to (anthropogenically-) increased predation by

  4. Predation and habitat modification synergistically interact to control bivalve recruitment on intertidal mudflats

    NARCIS (Netherlands)

    van der Heide, Tjisse; Tielens, Elske; van der Zee, Els; Weerman, Ellen J.; Holthuijsen, Sander; Eriksson, Britas Klemens; Piersma, Theun; van de Koppel, Johan; Olff, Han

    Bivalves are key components of coastal ecosystems because they link pelagic and benthic food webs, and shape the landscape through habitat modification. Nevertheless, many bivalve stocks have dramatically declined, and recruitment failure due to (anthropogenically-) increased predation by

  5. Short-term fluctuations in bivalve larvae compared with some environmental factors in a coastal lagoon (South Portugal

    Directory of Open Access Journals (Sweden)

    Luis M.Z. Chícaro

    2000-12-01

    Full Text Available In this study, short-term fluctuations in bivalve larvae were compared with some triggering factors for a period of sixteen months. Data on the abundance of planktonic larvae, collected two to three times a week were related to water temperature, salinity, wind velocity, tidal amplitude and chlorophyll a. Higher densities of planktonic bivalve larvae were caught between May and August, but intense fluctuations in abundance were observed. Planktonic bivalve larvae of eighteen taxa were identified. Larvae of Mytilus galloprovincialis, Cerastoderma edule, Ruditapes decussates and Venerupis spp. were the most abundant. The seasonal fluctuations of bivalve abundance seem to be controlled by temperature, the major factor in the timing of the reproduction of bivalves. Nevertheless, advection may be also a key factor during the planktonic life of bivalve species in coastal systems, such as the Ria Formosa.

  6. Bivalves: From individual to population modelling

    NARCIS (Netherlands)

    Saraiva, S.; van der Meer, J.; Kooijman, S.A.L.M.

    2014-01-01

    An individual based population model for bivalves was designed, built and tested in a 0D approach, to simulate the population dynamics of a mussel bed located in an intertidal area. The processes at the individual level were simulated following the dynamic energy budget theory, whereas initial egg

  7. Development of human impact on suspension-feeding bivalves in coastal soft-bottom ecosystems

    NARCIS (Netherlands)

    Wolff, Wim J.; Dame, RF; Olenin, S

    2005-01-01

    Suspension-feeding bivalves often may occur in large concentrations ('beds') on tidal flats. This makes them attractive for human consumers and the archaeological record shows collection of bivalves by coastal populations already tens of thousands of years ago. In modem time human interference with

  8. Histological techniques for marine bivalve mollusks and crustaceans, 2nd edition

    OpenAIRE

    Howard, Dorothy W.; Lewis, Earl J.; Keller, B. Jane; Smith, Cecelia S.

    2004-01-01

    Investigators at the Cooperative Oxford Laboratory (COL) diagnose and study crustaceans, mollusks, finfish, and a variety of other marine and estuarine invertebrates to assess animal health. This edition updates the Histological Techniques for Marine Bivalve Mollusks manual by Howard and Smith (1983) with additional chapters on molluscan and crustacean techniques. The new edition is intended to serve as a guide for histological processing of shellfish, principally bivalve mollusks and crustac...

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

    African Journals Online (AJOL)

    Ksu-network

    2012-07-19

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

  10. Nursery function of coastal temperate benthic habitats: New insight from the bivalve recruitment perspective

    Science.gov (United States)

    Barbier, Pierrick; Meziane, Tarik; Forêt, Martin; Tremblay, Réjean; Robert, René; Olivier, Frédéric

    2017-03-01

    Marine habitat function has been typically investigated in terms of biogeochemical regulation but rarely in terms of population renewal, which is mainly controlled by recruitment dynamics. The recruitment phase is crucial for organisms with a bentho-pelagic life cycle, such as bivalves, and it regulates the population renewal success. This study provides new insight on the role of temperate benthic habitats on bivalve recruitment, as a function of nursery areas. Six dominant benthic habitats of the Chausey archipelago (Normandy, France) were studied. In each habitat, bivalve recruit assemblages were described at the end of two reproductive seasons. Furthermore, Ostrea edulis juveniles were immerged on each habitat during two months to compare growth performances and feeding status, estimated by fatty acid composition. Recruit assemblages differ from each habitat according to sediment grain-size composition and bathymetrical levels. Subtidal habitats, and especially Crepidula fornicata banks and Glycymeris glycymeris coarse sands, supported the highest species abundance and richness of recruits. All O. edulis juveniles fed on the same trophic resources but digestive glands of juveniles from C. fornicata banks were more concentrated in total fatty acids than those from subtidal G. glycymeris coarse sands and maerl banks. Our results depict the key role of subtidal and structured habitats, composed of ecosystem engineers, in enhancing bivalve recruitment and extending the bivalve population renewal. This study suggests that the crucial role of these habitats as bivalve nurseries must be integrated in management perspectives. 2-column fitting image. 1-column fitting image.

  11. A Darriwilian (Middle Ordovician bivalve-dominated molluscan fauna from the Stairway Sandstone, Amadeus Basin, central Australia

    Directory of Open Access Journals (Sweden)

    Kristian G. Jakobsen

    2016-12-01

    Full Text Available A bivalve-dominated molluscan fauna is described from the Darriwilian (Middle Ordovician Stairway Sandstone, Amadeus Basin, central Australia. The fauna comprises 16 species of bivalves and rostroconchs plus six gastropod species which are treated under open nomenclature. Two new bivalves, Sthenodonta paenesymmetrica sp. nov. and Modiolopsis pojetai sp. nov., are described. The relatively low-diverse molluscan fauna constitutes around 62% of the total benthic macrofauna. Approximately 75% of the molluscs comprise bivalves, especially nuculoids, which were biogeographically restricted to low latitudes during the Ordovician. The molluscan assemblage displays a very high degree of endemism at species level, though the bivalve Sthenodonta eastii also occurs in the Georgina Basin farther to the northeast. This indicates a possible marine connective seaway between the Georgina and Amadeus basins during the Darriwilian. Nuculites, Cyrtodonta, and Modiolopsis are cosmopolitan and previously reported from North China, Avalonia, and Southern Gondwana.

  12. Spatial structure of the meroplankton community along a Patagonian fjord - The role of changing freshwater inputs

    Science.gov (United States)

    Meerhoff, Erika; Tapia, Fabián J.; Castro, Leonardo R.

    2014-12-01

    Freshwater inputs are major drivers of circulation, hydrographic structure, and productivity patterns along estuarine systems. We assessed the degree to which meroplankton community structure in the Baker/Martinez fjord complex (Chilean Patagonia, 47.5°S) responds to spatial and temporal changes in hydrographic conditions driven by seasonal changes in Baker river outflow. Zooplankton and hydrographic measurements were conducted along the fjord in early spring (October) and late summer (February), when river outflow was minimal and maximal, respectively. Major meroplankton groups found on these surveys were larval barnacles, crabs, bivalves and gastropods. There was a clear change in community structure between October and February, explained by a switch in the numerically dominant group from barnacle to bivalve larvae. This change in community structure was related to changes in hydrographic structure along the fjord, which are mainly associated with seasonal changes in the Baker river outflow. A variance partition analysis showed no significant spatial trend that could account for the variation in meroplankton along the Martinez channel, whereas temporal variability and environmental variables accounted for 36.6% and 27.6% of the variance, respectively. When comparing meroplankton among the Baker and Martinez channels in October, changes in environmental variables explained 44.9% of total variance, whereas spatial variability accounted for 23.5%. Early and late-stage barnacle larvae (i.e. nauplii and cyprids) were more abundant in water with lower temperature, and higher dissolved oxygen and chlorophyll-a concentration, whereas bivalve larvae were more strongly associated to warmer waters. The seasonal shift in numerical dominance, from barnacle larvae in early spring to bivalve larvae in late summer, suggests that reproduction of these groups is triggered by substantially different sets of conditions, both in terms of hydrography and food availability. The

  13. Bioaccumulation of 210Po in common gastropod and bivalve species from the northern Gulf.

    Science.gov (United States)

    Uddin, S; Bebhehani, M

    2014-06-01

    This study sets the baseline for the concentration of the natural-series radionuclide polonium-210 in two species of gastropods and four species of bivalves that are common to the Northern Arabian/Persian Gulf. (210)Po is primarily absorbed from water and via ingestion of detrital material by gastropoda and bivalves. This concentrated (210)Po can then be passed along to the next trophic level of the marine food web. The lowest (210)Po concentration was measured in the gastropod Stomatella auricular (10.36-12.39Bq kg(-1)dry) and the highest in the bivalve Marica marmorata (193.51-215.60Bq kg(-1)dry). The measured concentration factor for these molluscs in the northern Gulf varied between 4.8 and 115×10(3), values very similar to the IAEA recommended value for bivalves and gastropods of 2×10(4). Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Effect of dietary polyunsaturated fatty acids on reproductive output and larval growth of bivalves

    NARCIS (Netherlands)

    Hendriks, I.E.; Van Duren, L.A.; Herman, P.M.J.

    2003-01-01

    The pre-spawning condition of adult bivalves is influenced by quantity and quality of available food. For bivalves, the essential polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) 20:5(n-3) and docosahexaenoic acid (DHA) 22:6(n-3) are presumed to determine the nutritional value of

  15. Acute and chronic toxicity of boron to a variety of freshwater organisms.

    Science.gov (United States)

    Soucek, David J; Dickinson, Amy; Koch, Brian T

    2011-08-01

    Boron enters the aquatic environment from various sources, including weathering of borates, sewage effluents, coal combustion, use of cleaning compounds, and agrochemicals. The present study was designed to generate data on acute and chronic boron toxicity in support of an update of water quality standards in Illinois, USA. We examined the acute toxicity of boron to eight different freshwater organisms including a fish, an insect, two crustaceans, and four bivalve mollusks. To our knowledge, this is the first study to present data on the toxicity of boron to freshwater mollusks. We also sought to clarify whether hardness or pH affect boron toxicity to aquatic life, and to quantify chronic effect levels in two freshwater species. Sensitivity among the various species ranged widely, with the fathead minnow (Pimephales promelas) being the most sensitive. Neither pH nor hardness had a consistent effect on acute boron toxicity to two crustaceans (Ceriodaphnia dubia and Hyalella azteca), but we observed evidence that chloride reduces boron toxicity to H. azteca. The fathead minnow, while more acutely sensitive than the other species, had a lower acute to chronic ratio than did H. azteca, which had reduced reproduction at 13 mg/L. While we do not know the extent to which the eight tested species represent the range of sensitivities of native but untested species in Illinois, the current water quality standard for Illinois (1 mg/L) is conservative with regard to the native species tested thus far. Copyright © 2011 SETAC.

  16. Travel report Mauritania bivalve Molluscs october 2008

    NARCIS (Netherlands)

    Poelman, M.

    2008-01-01

    During the last four years Mauritania has been working on the completion of a Food Safety Program of Bivalve Mollusks, in order to obtain an export approval by the Europe Union. During the preparations for an inspection by the FVO (Food and Veterinary Office) no fisheries or production activities

  17. Bivalve aquaculture transfers in Atlantic Europe. Part A: Transfer activities and legal framework

    DEFF Research Database (Denmark)

    Muehlbauer, F.; Fraser, D.; Brenner, M.

    2014-01-01

    environment and address economic considerations remains unanswered. This study provides the first overview of bivalve transfer activities for aquaculture purposes along the European Atlantic coast. Existing international and EU legislation is described, and potential weaknesses in the existing legislative......Intentional transfers of numerous bivalve species have had a long tradition and are commonly conducted along the European Atlantic coast. However numerous studies have concluded that intentional transfer of species for aquaculture purposes is one of the most principal vectors for the introduction...... frameworks are discussed. Recommendations for the development of integrated risk assessment methods are given. These may help to minimize the intrinsic threats of transfer activities in marine environments. The resulting impacts and effects of transfer activities of bivalves for aquaculture purpose...

  18. Morphometric Studies on Anodonta Anatine Bivalve Population from the Dognecea Lake

    Directory of Open Access Journals (Sweden)

    Marian Bura

    2011-10-01

    Full Text Available In the Dognecea Lake, near town Bocsa in Caras-Severin county a strong bivalve population has been discovered from the duck mussel specie (Anodonta anatina. Harvested individuals were transported to the Aquaculture laboratory where measurements and correct identification was made. This specie is considered endangered but in Banat area, especially in the Dognecea Lake it is well represented, having an ecological importance, but the bivalve can have an economical importance too, due to the high percentage of edible part of 56.5%.

  19. Freshwater Clam Extract Ameliorates Triglyceride and Cholesterol Metabolism through the Expression of Genes Involved in Hepatic Lipogenesis and Cholesterol Degradation in Rats

    Directory of Open Access Journals (Sweden)

    Thomas Laurent

    2013-01-01

    Full Text Available The freshwater clam (Corbicula spp. is a popular edible bivalve and has been used as a folk remedy for liver disease in Asia. As a Chinese traditional medicine, it is said that freshwater clam ameliorates alcoholic intoxication and cholestasis. In this study, to estimate the practical benefit of freshwater clam extract (FCE, we compared the effects of FCE and soy protein isolate (SPI on triglyceride and cholesterol metabolism in rats. FCE and SPI lowered serum cholesterol, and FCE tended to reduce serum triglycerides. FCE enhanced fecal sterol excretion and hepatic mRNA levels of CYP7A1 and ABCG5 more substantially than SPI; however, both diets reduced hepatic cholesterol. Both of the diets similarly suppressed liver lipids improved Δ9-desaturated fatty acid profile, and FCE was associated with a reduction in FAS and SCD1 mRNA levels. Hepatic transcriptome analysis revealed that inhibition of lipogenesis-related gene expression may contribute to downregulation of hepatic triglycerides by FCE. FCE would have better potential benefits for preventing metabolic disorders, through greater improvement of metabolism of triglycerides and cholesterol, likely through a mechanism similar to SPI.

  20. Tinjauan Keanekaragaman Moluska Air Tawar Di Beberapa Situ Di DAS Ciliwung - Cisadane [Study on the Freshwater Mollusc Diversity of the Small Lakes Along Ciliwung and Cisadane Rivers

    OpenAIRE

    Marwoto, Ristiyanti M; Isnaningsih, Nur R

    2014-01-01

    The freshwater molluscs (snails and bivalves) can be found in many type of water course either flowing or stagnant water. Some of them have survived living in bad condition such as polluted water. There are 199 situ (small lakes) in Jabodetabek (Jakarta, Bogor, Depok, Tangerang, Bekasi) have been reported but only 20 % were in good condition, even 12% have dissapeared that caused by silting up of the situ. The aim of the study was to evaluate the diversity of the molluscs as well as to know t...

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

    Science.gov (United States)

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

    2017-10-01

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

  2. An integrated ecosystem approach for assessing the potential role of cultivated bivalve shells as part of the carbon trading system

    DEFF Research Database (Denmark)

    Filgueira, Ramón; Byron, C.J.; Comeau, L.A.

    2015-01-01

    , is needed to provide a rigorous assessment of the role of bivalve mariculture in the CO2 cycle. On the other hand, the discussion about the inclusion of shells of cultured bivalves into the carbon trading system should be framed in the context of ecosystem goods and services. Humans culture bivalves......The role of bivalve mariculture in the CO2 cycle has been commonly evaluated as the balance between respiration, shell calcium carbonate sequestration and CO2 release during biogenic calcification. However, this approach neglects the ecosystem implications of cultivating bivalves at high densities...... with the aim of producing food, not sequestering CO2 in their shells, therefore the main ecosystem good provided by bivalve aquaculture is meat production, and shells should be considered as by-products of this human activity. This reasoning is key to split the CO2 released due to respiration between meat...

  3. Lower Oligocene bivalves of Ramanian Stage from Kachchh ...

    Indian Academy of Sciences (India)

    Sehe area of western Kachchh considered their. Bed Nos. 4 and 5 as .... with very thin population. The Bermoti stream ...... Recent; Indo–Pacific. Subgenus: .... Type species: Cardium discors Lamarck' 1805; T. Eocene–Miocene; Europe–Asia ..... Shuto Tsugio 1971 Neogene Bivalves from Panay Island, the. Philippines.

  4. 76 FR 65200 - Risk Assessment on Norovirus in Bivalve Molluscan Shellfish: Request for Comments and for...

    Science.gov (United States)

    2011-10-20

    ... transmission of norovirus from infected or ill food workers in food manufacturing or retail establishments to... Molluscan Shellfish Contamination Levels During Food Preparation and Bivalve Molluscan Shellfish Consumption... and other factors influencing bivalve molluscan shellfish contamination levels during food preparation...

  5. Trophic Dynamics of Filter Feeding Bivalves in the Yangtze Estuarine Intertidal Marsh: Stable Isotope and Fatty Acid Analyses

    Science.gov (United States)

    Wang, Sikai; Jin, Binsong; Qin, Haiming; Sheng, Qiang; Wu, Jihua

    2015-01-01

    Benthic bivalves are important links between primary production and consumers, and are essential intermediates in the flow of energy through estuarine systems. However, information on the diet of filter feeding bivalves in estuarine ecosystems is uncertain, as estuarine waters contain particulate matter from a range of sources and as bivalves are opportunistic feeders. We surveyed bivalves at different distances from the creek mouth at the Yangtze estuarine marsh in winter and summer, and analyzed trophic dynamics using stable isotope (SI) and fatty acid (FA) techniques. Different bivalve species had different spatial distributions in the estuary. Glauconome chinensis mainly occurred in marshes near the creek mouth, while Sinonovacula constricta preferred the creek. Differences were found in the diets of different species. S. constricta consumed more diatoms and bacteria than G. chinensis, while G. chinensis assimilated more macrophyte material. FA markers showed that plants contributed the most (38.86 ± 4.25%) to particular organic matter (POM) in summer, while diatoms contributed the most (12.68 ± 1.17%) during winter. Diatoms made the largest contribution to the diet of S. constricta in both summer (24.73 ± 0.44%) and winter (25.51 ± 0.59%), and plants contributed no more than 4%. This inconsistency indicates seasonal changes in food availability and the active feeding habits of the bivalve. Similar FA profiles for S. constricta indicated that the bivalve had a similar diet composition at different sites, while different δ13C results suggested the diet was derived from different carbon sources (C4 plant Spartina alterniflora and C3 plant Phragmites australis and Scirpus mariqueter) at different sites. Species-specific and temporal and/or spatial variability in bivalve feeding may affect their ecological functions in intertidal marshes, which should be considered in the study of food webs and material flows in estuarine ecosystems. PMID:26261984

  6. Environmentally applications of invasive bivalves for water and wastewater decontamination.

    Science.gov (United States)

    Gomes, João; Matos, Ana; Quinta-Ferreira, Rosa M; Martins, Rui C

    2018-07-15

    The environmental and economic impact of invasive bivalve species implies the development of suitable pest management strategies. Chemical control is the most usual approach. However, the production of toxic intermediates as well as the unavoidable impact over non target biota is of special concern. Another approach consists on the physical removal of the animals from the invaded sites. The high biofiltration and bioaccumulation capacity of such animals make them interesting for the removal of contaminants from water and wastewater. In this context, environmental applications can be given for these pests encompassing nutrients removal for the recovery of eutrophic sites, water disinfection, organic and metal contaminants abatement. These approaches may be integrated with pest management where the physical removed animals from the invaded spots could be used for assembling biofilter for water and wastewater decontamination. However, some drawbacks must be addressed before proposing such alternative. In fact, the further spreading of the bivalves into non-invaded sites must be avoided. Moreover, some operational questions must be addressed such as the fate of contaminated animals after biofiltration. Bearing in mind the interesting results already available in this subject, this paper aims to critically overview literature regarding the environmental applications of invasive bivalves. Copyright © 2018 Elsevier B.V. All rights reserved.

  7. Spermatozoan ultrastructure in the trigonioid bivalve Neotrigonia margaritacea Lamarck (Mollusca): Comparison with other bivalves, especially Trigonioida and Unionoida

    Science.gov (United States)

    Healy, J. M.

    1996-06-01

    Spermatozoa of the trigonioid bivalve Neotrigonia margaritacea (Lamarck) (Trigoniidae, Trigonioida) are examined ultrastructurally. A cluster of discoidal, proacrosomal vesicles (between 9 to 15 in number) constitutes the acrosomal complex at the nuclear apex. The nucleus is short (2.4 2.6 μm long, maximum diameter 2.2 μm), blunt-conical in shape, and exhibits irregular lacunae within its contents. Five or sometimes four round mitochondria are impressed into shallow depressions in the base of the nucleus as is a discrete centriolar fossa. The mitochondria surround two orthogonally arranged centrioles to form, collectively, the midpiece region. The distal centriole, anchored by nine satellite fibres to the plasma membrane, acts as a basal body to the sperm flagellum. The presence of numerous proacrosomal vesicles instead of a single, conical acrosomal vesicle sets Neotrigonia (and the Trigonioida) apart from other bivalves, with the exception of the Unionoida which are also known to exhibit this multivesicular condition. Spermatozoa of N. margaritacea are very similar to those of the related species Neotrigonia bednalli (Verco) with the exception that the proacrosomal vesicles of N. margaritacea are noticeably larger than those of N. bednalli.

  8. Geochemical aspects of Meretrix casta (bivalve) shells of Vellar ...

    African Journals Online (AJOL)

    SAM

    2014-05-14

    May 14, 2014 ... The bivalve mollusk, Meretrix casta shells are abundant in the Vellar estuary along the East .... the Shervarayan hills of Salem District in Tamil Nadu, India. .... coast of Peninsular Malaysia and its potential as biomaterial for use.

  9. The miRNA biogenesis in marine bivalves

    Directory of Open Access Journals (Sweden)

    Umberto Rosani

    2016-03-01

    Full Text Available Small non-coding RNAs include powerful regulators of gene expression, transposon mobility and virus activity. Among the various categories, mature microRNAs (miRNAs guide the translational repression and decay of several targeted mRNAs. The biogenesis of miRNAs depends on few gene products, essentially conserved from basal to higher metazoans, whose protein domains allow specific interactions with dsRNA. Here, we report the identification of key genes responsible of the miRNA biogenesis in 32 bivalves, with particular attention to the aquaculture species Mytilus galloprovincialis and Crassostrea gigas. In detail, we have identified and phylogenetically compared eight evolutionary conserved proteins: DROSHA, DGCR8, EXP5, RAN, DICER TARBP2, AGO and PIWI. In mussels, we recognized several other proteins participating in the miRNA biogenesis or in the subsequent RNA silencing. According to digital expression analysis, these genes display low and not inducible expression levels in adult mussels and oysters whereas they are considerably expressed during development. As miRNAs play an important role also in the antiviral responses, knowledge on their production and regulative effects can shed light on essential molecular processes and provide new hints for disease prevention in bivalves.

  10. Microhabitat and biology of Sphaerium striatinum in a central New York stream

    Science.gov (United States)

    Dittman, Dawn E.; Johnson, James H.; Nack, Christopher C.

    2018-01-01

    In many lotic systems, drastic declines in freshwater bivalve populations, including fingernail clams (Sphaeriidae), have created concerns about biodiversity and future ecosystem services. We examined the local occurrence of the historically common fingernail clam, Sphaerium striatinum, in a central New York stream. We sampled the density of sphaeriids and measured the associated habitat variables (substrate, depth, water flow) to test within-stream multivariate benthic microhabitat association. Size distribution, density, and diel feeding periodicity were measured as focal aspects of fingernail clam biology and ecology. S. striatinum tended to be found in microhabitats that had harder substrates and faster flow. The Labrador Creek fingernail clam local population had positive indicators (size distribution, density). There was significant diel periodicity in feeding behavior. The clams fed most actively during the 0400–0800 h periods. This kind of behavioral periodicity can indicate a significant ecological interaction between predators and bivalve prey. Increased understanding of the behavioral ecology of small native freshwater bivalves in an unimpacted headwater stream is a fundamental building block for development of overall ecological conservation goals for freshwater bivalves and their lotic habitats.

  11. An overview of chemosynthetic symbioses in bivalves from the North Atlantic and Mediterranean Sea

    Science.gov (United States)

    Duperron, S.; Gaudron, S. M.; Rodrigues, C. F.; Cunha, M. R.; Decker, C.; Olu, K.

    2013-05-01

    Deep-sea bivalves found at hydrothermal vents, cold seeps and organic falls are sustained by chemosynthetic bacteria that ensure part or all of their carbon nutrition. These symbioses are of prime importance for the functioning of the ecosystems. Similar symbioses occur in other bivalve species living in shallow and coastal reduced habitats worldwide. In recent years, several deep-sea species have been investigated from continental margins around Europe, West Africa, eastern Americas, the Gulf of Mexico, and from hydrothermal vents on the Mid-Atlantic Ridge. In parallel, numerous, more easily accessible shallow marine species have been studied. Herein we provide a summary of the current knowledge available on chemosymbiotic bivalves in the area ranging west-to-east from the Gulf of Mexico to the Sea of Marmara, and north-to-south from the Arctic to the Gulf of Guinea. Characteristics of symbioses in 53 species from the area are summarized for each of the five bivalve families documented to harbor chemosynthetic symbionts (Mytilidae, Vesicomyidae, Solemyidae, Thyasiridae and Lucinidae). Comparisons are made between the families, with special emphasis on ecology, life cycle, and connectivity. Chemosynthetic symbioses are a major adaptation to ecosystems and habitats exposed to reducing conditions. However, relatively little is known regarding their diversity and functioning, apart from a few "model species" on which effort has focused over the last 30 yr. In the context of increasing concern about biodiversity and ecosystems, and increasing anthropogenic pressure on oceans, we advocate a better assessment of the diversity of bivalve symbioses in order to evaluate the capacities of these remarkable ecological and evolutionary units to withstand environmental change.

  12. An overview of chemosynthetic symbioses in bivalves from the North Atlantic and Mediterranean Sea

    Directory of Open Access Journals (Sweden)

    S. Duperron

    2013-05-01

    Full Text Available Deep-sea bivalves found at hydrothermal vents, cold seeps and organic falls are sustained by chemosynthetic bacteria that ensure part or all of their carbon nutrition. These symbioses are of prime importance for the functioning of the ecosystems. Similar symbioses occur in other bivalve species living in shallow and coastal reduced habitats worldwide. In recent years, several deep-sea species have been investigated from continental margins around Europe, West Africa, eastern Americas, the Gulf of Mexico, and from hydrothermal vents on the Mid-Atlantic Ridge. In parallel, numerous, more easily accessible shallow marine species have been studied. Herein we provide a summary of the current knowledge available on chemosymbiotic bivalves in the area ranging west-to-east from the Gulf of Mexico to the Sea of Marmara, and north-to-south from the Arctic to the Gulf of Guinea. Characteristics of symbioses in 53 species from the area are summarized for each of the five bivalve families documented to harbor chemosynthetic symbionts (Mytilidae, Vesicomyidae, Solemyidae, Thyasiridae and Lucinidae. Comparisons are made between the families, with special emphasis on ecology, life cycle, and connectivity. Chemosynthetic symbioses are a major adaptation to ecosystems and habitats exposed to reducing conditions. However, relatively little is known regarding their diversity and functioning, apart from a few "model species" on which effort has focused over the last 30 yr. In the context of increasing concern about biodiversity and ecosystems, and increasing anthropogenic pressure on oceans, we advocate a better assessment of the diversity of bivalve symbioses in order to evaluate the capacities of these remarkable ecological and evolutionary units to withstand environmental change.

  13. Bioaccumulation of selenium and induced biological effects in the filter feeding bivalve Corbicula fluminea: influence of ventilatory activity, selenium speciation and route of transfer

    International Nuclear Information System (INIS)

    Fournier, E.

    2005-10-01

    Selenium is an essential micro-nutrient for most of living organisms. However, toxic effects in several ecosystems have been reported in the literature. Toxicity comprehension is difficult due to the complexity of Se oxidation states in the environment. The aim of this thesis work was to acquire knowledge on the physiological and environmental factors involved in bioaccumulation and toxicity processes in the freshwater filter-feeding bivalve C. fluminea. The aims were: i) to define what the factors involved in Se bioaccumulation processes in the bivalve are, ii) to characterize Se bioaccumulation at different biological organisation levels, iii) to investigate Se toxic effects. First experiments, carried out for short term exposure duration (3 days), have permitted to underline the importance of Se chemical speciation in bioaccumulation processes in C. fluminea. It has been shown that the organic form, seleno-methionine, was much more bio-available than the inorganic forms, selenite and selenate. Moreover, the route of transfer was determinant in those processes. Inorganic forms have been better extracted by trophic route, whereas seleno-methionine has been better extracted by the direct route. In our experimental conditions, ventilation of the bivalve has not been a limiting factor for Se bioaccumulation by the direct route, whereas it has been for bioaccumulation by the trophic route. Ventilation has been largely modified by the presence of dissolved selenite and seleno-methionine. We have shown that the kinetics of seleno-methionine bioaccumulation are much more fast than those of selenite. Moreover, when introduced as SeMet, internalized Se appeared to be relatively remanent in soft tissues of C. fluminea in comparison with Se internalized when introduced as selenite. Subcellular and molecular distributions of these forms were very different. Finally, it has been shown that seleno-methionine and selenite could generate weak alterations of the anti

  14. Ocean Acidification Has Multiple Modes of Action on Bivalve Larvae.

    Directory of Open Access Journals (Sweden)

    George G Waldbusser

    Full Text Available Ocean acidification (OA is altering the chemistry of the world's oceans at rates unparalleled in the past roughly 1 million years. Understanding the impacts of this rapid change in baseline carbonate chemistry on marine organisms needs a precise, mechanistic understanding of physiological responses to carbonate chemistry. Recent experimental work has shown shell development and growth in some bivalve larvae, have direct sensitivities to calcium carbonate saturation state that is not modulated through organismal acid-base chemistry. To understand different modes of action of OA on bivalve larvae, we experimentally tested how pH, PCO2, and saturation state independently affect shell growth and development, respiration rate, and initiation of feeding in Mytilus californianus embryos and larvae. We found, as documented in other bivalve larvae, that shell development and growth were affected by aragonite saturation state, and not by pH or PCO2. Respiration rate was elevated under very low pH (~7.4 with no change between pH of ~ 8.3 to ~7.8. Initiation of feeding appeared to be most sensitive to PCO2, and possibly minor response to pH under elevated PCO2. Although different components of physiology responded to different carbonate system variables, the inability to normally develop a shell due to lower saturation state precludes pH or PCO2 effects later in the life history. However, saturation state effects during early shell development will carry-over to later stages, where pH or PCO2 effects can compound OA effects on bivalve larvae. Our findings suggest OA may be a multi-stressor unto itself. Shell development and growth of the native mussel, M. californianus, was indistinguishable from the Mediterranean mussel, Mytilus galloprovincialis, collected from the southern U.S. Pacific coast, an area not subjected to seasonal upwelling. The concordance in responses suggests a fundamental OA bottleneck during development of the first shell material

  15. Ocean Acidification Has Multiple Modes of Action on Bivalve Larvae.

    Science.gov (United States)

    Waldbusser, George G; Hales, Burke; Langdon, Chris J; Haley, Brian A; Schrader, Paul; Brunner, Elizabeth L; Gray, Matthew W; Miller, Cale A; Gimenez, Iria; Hutchinson, Greg

    2015-01-01

    Ocean acidification (OA) is altering the chemistry of the world's oceans at rates unparalleled in the past roughly 1 million years. Understanding the impacts of this rapid change in baseline carbonate chemistry on marine organisms needs a precise, mechanistic understanding of physiological responses to carbonate chemistry. Recent experimental work has shown shell development and growth in some bivalve larvae, have direct sensitivities to calcium carbonate saturation state that is not modulated through organismal acid-base chemistry. To understand different modes of action of OA on bivalve larvae, we experimentally tested how pH, PCO2, and saturation state independently affect shell growth and development, respiration rate, and initiation of feeding in Mytilus californianus embryos and larvae. We found, as documented in other bivalve larvae, that shell development and growth were affected by aragonite saturation state, and not by pH or PCO2. Respiration rate was elevated under very low pH (~7.4) with no change between pH of ~ 8.3 to ~7.8. Initiation of feeding appeared to be most sensitive to PCO2, and possibly minor response to pH under elevated PCO2. Although different components of physiology responded to different carbonate system variables, the inability to normally develop a shell due to lower saturation state precludes pH or PCO2 effects later in the life history. However, saturation state effects during early shell development will carry-over to later stages, where pH or PCO2 effects can compound OA effects on bivalve larvae. Our findings suggest OA may be a multi-stressor unto itself. Shell development and growth of the native mussel, M. californianus, was indistinguishable from the Mediterranean mussel, Mytilus galloprovincialis, collected from the southern U.S. Pacific coast, an area not subjected to seasonal upwelling. The concordance in responses suggests a fundamental OA bottleneck during development of the first shell material affected only by

  16. Modiolarca lateralis (Pteryomorphia: Mytilidae: bivalve associated to six species of ascidians from Bocas del Toro, Panama

    Directory of Open Access Journals (Sweden)

    Juan I Cañete

    2013-11-01

    Full Text Available We describe the presence of the bivalve Modiolarca lateralis (Say, 1822 in six tropical ascidians Ascidia curvata, A. sydneiensis, A. panamensis, A. interrupta, Herdmania pallida and Polycarpa spongiabilis collected at depths of 1-3 m on coral reefs, mangrove roots and dock supports in Almirante Bay, Bocas del Toro, Panama (9°18'N, 82°13'W during June-July 2011. Bivalve prevalence varied between 9-30% across species, but was mainly associated with A. panamensis, P. spongiabilis and A. interrupta. Prevalence seems to be influenced by tunic thickness rather than by the ascidian size. Bivalves varied in size (0.6-11 mm shell length, with the smallest individual found in A. sydneiensis. There were only one or two bivalves per ascidians, although a maximum of 18 was found in one A. panamensis. M. lateralis seems to behave similarly to its temperate counterparts: it has a variety of hosts, occurs mainly in the anterior region of the ascidians, and has a variable abundance per host.

  17. Po-210 and other radionuclides in terrestrial and freshwater environments

    Energy Technology Data Exchange (ETDEWEB)

    Gjelsvik, Runhild; Brown, Justin [eds.; Norwegian Radiation Protection Authority (Norway); Holm, Elis [Univ. of Lund (Sweden); Roos, Per [Risoe DTU (Denmark); Saxen, Ritva; Outola, Iisa [STUK - Radiation and Nuclear Safety Authority (Finland)

    2009-01-15

    This report provides new information on Po-210 (and where appropriate its grandparent Pb-210) behaviour in environmental systems including humans. This has primarily been achieved through measurements of Po-210 in aquatic and terrestrial environments that has led to the derivation of information on the levels of this radioisotope in plants, animals and the biotic components of their habitat (i.e. water, soil) providing basic information on transfer where practicable. For freshwater environments, Po-210 concentration ratios derived for freshwater benthic fish and bivalve mollusc were substantially different to values collated from earlier review work. For terrestrial environments, activity concentrations of Po-210 in small mammals (although of a preliminary nature because no correction was made for ingrowth from Pb-210) were considerably higher than values derived from earlier data compilations. It was envisaged that data on levels of naturally occurring radionuclides would render underpinning data sets more comprehensive and would thus allow more robust background dose calculations to be performed subsequently. By way of example, unweighted background dose-rates arising from internal distributions of Po-210 were calculated for small mammals in the terrestrial study. The biokinetics of polonium in humans has been studied following chronic and acute oral intakes of selected Po radioisotopes. This work has provided information on gastrointestinal absorption factors and biological retention times thus improving the database upon which committed effective doses to humans are derived. The information generated in the report, in its entirety, should be of direct relevance for both human and non-human impact assessments. (au)

  18. Po-210 and other radionuclides in terrestrial and freshwater environments

    International Nuclear Information System (INIS)

    Gjelsvik, Runhild; Brown, Justin; Roos, Per; Saxen, Ritva; Outola, Iisa

    2009-01-01

    This report provides new information on Po-210 (and where appropriate its grandparent Pb-210) behaviour in environmental systems including humans. This has primarily been achieved through measurements of Po-210 in aquatic and terrestrial environments that has led to the derivation of information on the levels of this radioisotope in plants, animals and the biotic components of their habitat (i.e. water, soil) providing basic information on transfer where practicable. For freshwater environments, Po-210 concentration ratios derived for freshwater benthic fish and bivalve mollusc were substantially different to values collated from earlier review work. For terrestrial environments, activity concentrations of Po-210 in small mammals (although of a preliminary nature because no correction was made for ingrowth from Pb-210) were considerably higher than values derived from earlier data compilations. It was envisaged that data on levels of naturally occurring radionuclides would render underpinning data sets more comprehensive and would thus allow more robust background dose calculations to be performed subsequently. By way of example, unweighted background dose-rates arising from internal distributions of Po-210 were calculated for small mammals in the terrestrial study. The biokinetics of polonium in humans has been studied following chronic and acute oral intakes of selected Po radioisotopes. This work has provided information on gastrointestinal absorption factors and biological retention times thus improving the database upon which committed effective doses to humans are derived. The information generated in the report, in its entirety, should be of direct relevance for both human and non-human impact assessments. (au)

  19. Shell growth and environmental control of methanophyllic Thyasirid bivalves from Svalbard cold seeps

    Science.gov (United States)

    Carroll, Michael; Åström, Emmelie; Ambrose, William; Locke, William; Oliver, Graham; Hong, Wei-Li; Carroll, JoLynn

    2016-04-01

    The analysis of molluscan shell material (sclerochronology) can provide information about an organism's age, growth history, and environmental conditions during its lifetime. Bivalve molluscs are common members of hydrothermal vents and methane cold seeps communities where, supported by chemosynthetic symbionts, they can reach high density and biomass. But little is known about methane-associated bivalve populations inhabiting high-Arctic cold seeps, and sclerochronological analysis of methane-influenced bivalves is rare. We measured growth rates and elemental and isotopic shell signatures in a newly discovered species of bivalve (Thyasiridae) from cold seeps at 350-390m depth southwest of Svalbard. First discovered in 2014, recently described shells of Thyasira capitanea sp.nov. were found at 2 independent seep systems in Storfjordrenna. Mean shell carbon isotopic ratios from inorganic δ13C (mean = -4.8‰) and organic δ13C (mean = -26.9‰) fractions clearly indicate a methane influenced habitat and food source for these organisms. Shell mineral ratios (Li/Ca, Mg/Ca, Mn/Ca, Fe/Ca, Sr/Ca, Ba/Ca, Pb/Ca) sampled along the axis of growth with laser-ablated ICP-MS exhibit variability through time and between sites, suggesting that concentrations of these elements that may be affected by methane emissions. The mineralogical data also elucidates the internal pattern of shell deposition and growth checks, and combined with the isotopic and growth rate data, enables us to interpret the temporal history of methane release from these locations.

  20. Influence of food on the assimilation of selected metals in tropical bivalves from the New Caledonia lagoon: Qualitative and quantitative aspects

    International Nuclear Information System (INIS)

    Hedouin, Laetitia; Metian, Marc; Lacoue-Labarthe, Thomas; Fichez, Renaud; Teyssie, Jean-Louis; Bustamante, Paco; Warnau, Michel

    2010-01-01

    The present study aimed at examining the influence of food quality and quantity on the assimilation efficiency (AE) of metals in two abundant bivalves in the New Caledonia lagoon, the oyster Isognomon isognomon and the clam Gafrarium tumidum. Bivalves were exposed via their food to the radiotracers of three metals of concern in New Caledonia ( 54 Mn, 57 Co and 65 Zn) under different feeding conditions (phytoplankton species, cell density, and cell-associated metal concentration). When bivalves were fed Heterocapsa triquetra, Emiliania huxleyi and Isochrysis galbana, AE of Mn, Co and Zn was strongly influenced by the phytoplankton species and by the metal considered. In contrast, when fed one given phytoplankton species previously exposed to different concentrations of Co, phytoplankton-associated Co load had no influence on the AE and on the retention time of the metal in both bivalves. Metals ingested with I. galbana displayed generally the highest AE in both bivalve species, except for Mn in clams for which the highest AE was observed for H. triquetra. Influence of food quantity was investigated by exposing bivalves to different cell densities of I. galbana (5 x 10 3 , 10 4 or 5 x 10 4 cell ml -1 ). As for food quality, food quantity was found to influence AE of Mn, Co and Zn, the highest AE being observed when bivalves were fed the lowest cell density. Overall, results indicate that the two bivalve species are able to adjust their feeding strategies according to the food conditions prevailing in their environment.

  1. Congener-specific distribution and bioaccumulation of short-chain chlorinated paraffins in sediments and bivalves of the Bohai Sea, China.

    Science.gov (United States)

    Ma, Xindong; Chen, Chen; Zhang, Haijun; Gao, Yuan; Wang, Zhen; Yao, Ziwei; Chen, Jiping; Chen, Jingwen

    2014-02-15

    Short-chain chlorinated paraffins (SCCPs) are a new type of persistent organic pollutants that are of great environmental concern because of their wide distribution. In this study, surface sediments and bivalve samples were collected from the coastal area of the Bohai Sea in China. Total SCCP (ΣSCCP) concentrations in surface sediments and bivalves ranged from 97.4 ng g(-1) dry weight (dw) to 1756.7 ng g(-1) dw and 476.4-3269.5 ng g(-1) dw, respectively. C10-CPs and C11-CPs were the predominant homologue groups in all sediments and bivalves. Specific congener composition analysis and correspondence analysis indicated that the local SCCP source mainly came from CP-42 and CP-52 products, and riverine input had an important function. The biota-sediment accumulation factors of ΣSCCPs for bivalves ranged from 1.08 to 1.61, and a significant correlation indicated that the SCCP congener with higher chlorination degree was more likely to be accumulated in bivalves. Copyright © 2014. Published by Elsevier Ltd.

  2. Uncharted waters: Bivalves of midway atoll and integrating mathematics into biology education

    Science.gov (United States)

    McCully, Kristin M.

    To protect and conserve the Earth's biodiversity and ecosystem services, it is important not only to understand and conserve species and ecosystems, but also to instill an understanding and appreciation for biodiversity and ecosystem services in the next generations of both scientists and citizens. Thus, this dissertation combines research into the ecology and identity of large bivalves at Midway Atoll in the Northwestern Hawaiian Islands (NWHI) with research on pedagogical strategies for integrating mathematics into undergraduate biology education. The NWHI is one of the few remaining large, mainly intact, predator-dominated coral reef ecosystems and one of the world's largest marine protected areas. Previous bivalve studies focused on the black-lipped pearl oyster, Pinctada margaritifera, which was heavily harvested in the late 1920s, has not recovered, and is now a candidate species for restoration. First, I combined remote sensing, geographic information systems, SCUBA, and mathematical modeling to quantify the abundance, spatial distributions, and filtration capacity of large epifaunal bivalves at Midway Atoll. These bivalves are most abundant on the forereef outside the atoll, but densities are much lower than reported on other reefs, and Midway's bivalves are unlikely to affect plankton abundance and productivity inside the lagoon. Second, I used molecular techniques and phylogenetic reconstructions to identify pearl oysters (Pinctada) from Midway Atoll as P. maculata , a species not previously reported in Hawaii. As a small morphologically cryptic species, P. maculata may be a native species that has not been collected previously, a native species that has been identified incorrectly as the morphologically similar P. radiata, or it may be a recent introduction or natural range extension from the western Pacific. Finally, I review science education literature integrating mathematics into undergraduate biology curricula, and then present and evaluate a

  3. Bioaccumulation of selenium and induced biological effects in the filter feeding bivalve Corbicula fluminea: influence of ventilatory activity, selenium speciation and route of transfer; Bioaccumulation du selenium et effets biologiques induits chez le bivalve filtreur Corbicula fluminea: prise en compte de l'activite ventilatoire, de la speciation du selenium et de la voie de contamination

    Energy Technology Data Exchange (ETDEWEB)

    Fournier, E

    2005-10-15

    Selenium is an essential micro-nutrient for most of living organisms. However, toxic effects in several ecosystems have been reported in the literature. Toxicity comprehension is difficult due to the complexity of Se oxidation states in the environment. The aim of this thesis work was to acquire knowledge on the physiological and environmental factors involved in bioaccumulation and toxicity processes in the freshwater filter-feeding bivalve C. fluminea. The aims were: i) to define what the factors involved in Se bioaccumulation processes in the bivalve are, ii) to characterize Se bioaccumulation at different biological organisation levels, iii) to investigate Se toxic effects. First experiments, carried out for short term exposure duration (3 days), have permitted to underline the importance of Se chemical speciation in bioaccumulation processes in C. fluminea. It has been shown that the organic form, seleno-methionine, was much more bio-available than the inorganic forms, selenite and selenate. Moreover, the route of transfer was determinant in those processes. Inorganic forms have been better extracted by trophic route, whereas seleno-methionine has been better extracted by the direct route. In our experimental conditions, ventilation of the bivalve has not been a limiting factor for Se bioaccumulation by the direct route, whereas it has been for bioaccumulation by the trophic route. Ventilation has been largely modified by the presence of dissolved selenite and seleno-methionine. We have shown that the kinetics of seleno-methionine bioaccumulation are much more fast than those of selenite. Moreover, when introduced as SeMet, internalized Se appeared to be relatively remanent in soft tissues of C. fluminea in comparison with Se internalized when introduced as selenite. Subcellular and molecular distributions of these forms were very different. Finally, it has been shown that seleno-methionine and selenite could generate weak alterations of the anti

  4. EU Regulatory Risk Management of Marine Biotoxins in the Marine Bivalve Mollusc Food-Chain.

    Science.gov (United States)

    O'Mahony, Micheál

    2018-03-10

    Food safety risk assessment in the European Union (EU) recognises consumer illness that arises from marine biotoxins as a risk associated with bivalve mollusc consumption. EU food regulations contain various general food safety obligations, which should contribute significantly to managing this risk. EU food regulations additionally impose various specific obligations on both Food Business Operators and Competent Authorities in order to manage the marine biotoxin food safety risk in the bivalve mollusc food-chain. These have a particular focus on the pre-harvest component of the food-chain. A central component of these specific systems is the requirement for ongoing monitoring of phytoplankton and biotoxin concentrations in water and molluscs, respectively. This monitoring explicitly brings a potential outcome of closing production areas delineated by classification to prohibit the harvest of bivalve molluscs as food from those areas when acceptable biotoxin concentrations are exceeded. This review considers the utility of these systems, at conceptual and practical levels, and explores their contribution to an effective regulatory risk management approach.

  5. SHRIMP (CRANGON-CRANGON L) BROWSING UPON SIPHON TIPS INHIBITS FEEDING AND GROWTH IN THE BIVALVE MACOMA-BALTHICA (L)

    NARCIS (Netherlands)

    KAMERMANS, P; HUITEMA, HJ

    1994-01-01

    The influence of siphon browsing on the feeding behaviour and growth of Macoma balthica, a deposit-feeding bivalve, was studied in three manipulative experiments. Browsing was simulated by removing part of the inhalant siphon with scissors, or studied by exposing the bivalves to shrimps (Crangon

  6. Lower Oligocene bivalves of Ramanian Stage from Kachchh, Gujarat, India

    Science.gov (United States)

    Kachhara, R. P.; Jodhawat, R. L.; Devi, K. Bigyapati

    2012-04-01

    Marine Oligocene sequences in India outcrop only in western part of Kachchh. Earlier researchers have recognized the Oligocene strata under the Nari Series (Nagappa 1959; Chatterji and Mathur 1966). The Nari Series has a type area in Pakistan. It has two subdivisions - the Lower Nari (Lower Oligocene) and the Upper Nari (Upper Oligocene). It seems that there is no valid proof about the age of the Lower Nari due to lack of proper fauna (Eames 1975), and according to Pascoe (1962), the Upper Nari slightly transgress into Aquitanian (Lower Miocene), therefore, one has to be very cautious. Biswas and Raju (1971) reclassified the Oligocene strata of Kachchh and lithostratigraphically clubbed them as the Maniyara Fort Formation with type section along the Bermoti stream. This Formation has four members. The lower three members correspond to the Ramanian Stage (Lower Oligocene, Biswas 1971, 1973) while the uppermost to the Waiorian Stage (Upper Oligocene, Biswas 1965, 1971, 1973). The Ramanian Stage is characterized by large forams especially Nummulites fichteli, Nummulites fichteli intermedius, Lepidocyclina ( Eulepidina) dialata and Operculina sp. Several ostracods are also known to occur. Megafauna include bivalves, gastropods, echinoids, corals, mammals and reptiles. Concerning bivalves earlier researchers have recorded a few taxa namely Trisidos semitorta (Lamarck), Cubitostrea angulata (J de C Sowerby), Pecten ( Amussiopecten) labadyei d'Archiac and Haime, Periglypta puerpera (Linne') var. aglaurae Brongniart, Ostrea fraasi Mayer Eymer and listed Pecten laevicostatus J de C Sowerby, Callista pseudoumbonella Vredenburg and Clementia papyracea (Gray) from Kachchh as against overall 42 forms from the Nari Series as a whole (Vredenburg 1928). This tempted us to make an attempt to collect bivalve fauna systematically which are occurring prolifically in the Ramanian Stage. In the present work, for this purpose, sections are worked out around Lakhpat (23°50'N; 68°47'E

  7. Seasonal variability in somatic and reproductive investment of the bivalve

    NARCIS (Netherlands)

    Santos, S.; Cardoso, J.F.M.F.; Carvalho, C.; Luttikhuizen, P.C.; van der Veer, H.W.

    2011-01-01

    Monthly investment in soma and gonads in the bivalve Scrobicularia plana is described for three populations along its distributional range: Minho estuary, Portugal; Westerschelde estuary, The Netherlands and Buvika estuary, Norway. Seasonal cycles in body mass (BMI), somatic mass (SMI) and

  8. Organisms associated with the sandy-beach bivalve Donax serra ...

    African Journals Online (AJOL)

    57: 134-136. BROWN, AC. & WEBB, S.c. 1994. Organisms associated \\.,.,ith burrowing whelks of the genus Bullia. S Afr. 1. Zool. 29: 144-151. BROWN, A.C., STENTON-DOZEY, J.~.E. & TRUEMAN, E.R.. 1989. Sandy-beach bivalves and gastropods; a comparison between Donax serra and Ruilia digitalis. Adv. mar. Bioi. 25:.

  9. Otimização do processo de depuração de moluscos bivalves

    OpenAIRE

    Correia, Maria Helena Oliveira Casimiro

    2016-01-01

    A contaminação microbiológica de moluscos bivalves constitui uma das principais preocupações inerentes à segurança alimentar desta importante fonte de receitas para a economia portuguesa. Os bivalves capturados ou produzidos em zonas estuarinas ou lagunares devem passar por um processo de depuração, para redução dos níveis de contaminação microbiológica, antes da sua comercialização. Este trabalho teve como principal objetivo o desenvolvimento de sistemas modulares de dep...

  10. Phenology of abundance of bivalve spat and of their epibenthic predators: limited evidence for mismatches after cold winters

    NARCIS (Netherlands)

    Dekker, R.; Beukema, J.J.

    2014-01-01

    Annual recruitment of bivalves in the Wadden Sea is usually more successful in summers after cold than after mild winters. The new generation (0-group) of the main predators (shrimps and shore crabs) of early benthic stages of bivalves appear later in spring on tidal flats after colder winters. If

  11. Parasites of economically important bivalves from the southern coast of Bahia State, Brazil Parasitos de bivalves de interesse econômico no Litoral Sul do Estado da Bahia, Brasil

    Directory of Open Access Journals (Sweden)

    Gabriela Calvi Zeidan

    2012-12-01

    Full Text Available This study investigated the parasites of three commercially important bivalve species (Crassostrea rhizophorae, Mytella guyanensis and Lucina pectinata from the southern coast of Bahia, Brazil. A total of 540 specimens were collected in August 2009 and February 2010, at three localities. The bivalve specimens were measured on their longest axis, opened, and macroscopically examined for the presence of parasites or signs of disease. They were then fixed in Davidson' solution and subjected to routine histological processing, with paraffin embedding and H&E staining; next, the specimens were examined under a light microscope. No parasites were observed associated with L. pectinata. Rickettsia-like organisms (RLOs, Sphenophrya sp. (Ciliophora, Nematopsis sp. (Apicomplexa, Urastoma sp. (Turbellaria and Bucephalus sp. (Digenea were observed in both C. rhizophorae and M. guyanensis, as well as Ancistrocoma sp. (Ciliophora and Tylocephalum sp. (Cestoda in the former. A high prevalence of Nematopsis sp. was seen, but caused no apparent damage to the host. Bucephalus sp. caused the destruction of tissues, with castration, but showed low prevalence. The other parasites occurred in low prevalence and intensity, without causing significant damage.Neste estudo foram investigados os parasitos de três espécies de bivalves de interesse econômico (Crassostrea rhizophorae, Mytella guyanensis e Lucina pectinata da Bahia. Foram analisados 540 exemplares, obtidos em duas coletas (agosto-2009 e fevereiro-2010, em três localidades. Os bivalves foram medidos quanto ao seu maior eixo, abertos e examinados macroscopicamente quanto à presença de parasitos ou sinais de enfermidades. Depois disso, foram fixados em solução de Davidson e processados por rotina de histologia, com inclusão em parafina e coloração com H&E. O material foi examinado ao microscópio de luz. Nenhum parasito esteve associado a L. pectinata. Bactérias do tipo RLOs (organismos assemelhados a

  12. EU Regulatory Risk Management of Marine Biotoxins in the Marine Bivalve Mollusc Food-Chain

    Directory of Open Access Journals (Sweden)

    Micheál O’Mahony

    2018-03-01

    Full Text Available Food safety risk assessment in the European Union (EU recognises consumer illness that arises from marine biotoxins as a risk associated with bivalve mollusc consumption. EU food regulations contain various general food safety obligations, which should contribute significantly to managing this risk. EU food regulations additionally impose various specific obligations on both Food Business Operators and Competent Authorities in order to manage the marine biotoxin food safety risk in the bivalve mollusc food-chain. These have a particular focus on the pre-harvest component of the food-chain. A central component of these specific systems is the requirement for ongoing monitoring of phytoplankton and biotoxin concentrations in water and molluscs, respectively. This monitoring explicitly brings a potential outcome of closing production areas delineated by classification to prohibit the harvest of bivalve molluscs as food from those areas when acceptable biotoxin concentrations are exceeded. This review considers the utility of these systems, at conceptual and practical levels, and explores their contribution to an effective regulatory risk management approach.

  13. Field clearance of an intertidal bivalve bed: relative significance of the co-occurring blue mussel Mytilus edulis and Pacific oyster Crassostrea gigas

    DEFF Research Database (Denmark)

    Vismann, Bent; Holm, Mark Wejlemann; Davids, Jens

    2016-01-01

    was estimated by combining field measurements of clearance rates and modelling of the bivalve bed (topography, biomass distribution, temporal and spatial water coverage and depth). The average density of C. gigas and M. edulis was 35 ± 36 and 1001 ± 685 ind. m−2, respectively. The water volume cleared during...... a tidal cycle was estimated at 45 838 m3, of which C. gigas and M. edulis contributed 9169 and 36 669 m3, respectively. Therefore, M. edulis contributed 4 times as much as C. gigas to the bivalve bed’s clearance, and the 2 bivalves were estimated to clear the water volume 1.9 times during each tidal cycle....... However, the estimated water column cleared during low tide is overestimated due to phytoplankton depletion. Hence, it is concluded that the bivalve bed clears the water close to 1 time each tidal cycle. This, together with a low dry weight of soft parts, indicates that the bivalve bed, in general...

  14. In situ method for measurements of community clearance rate on shallow water bivalve populations

    DEFF Research Database (Denmark)

    Hansen, Benni W.; Dolmer, Per; Vismann, Bent

    2011-01-01

    An open-top chamber was designed for measuring ambient community clearance rate on undisturbed bivalve populations in the field. The chamber was pressed 5-10 cm down in the sediment on the mussel bed. It holds approximately 30-40 cm water column equal to a volume of 43-77 L. It was provided...... with an air lift connected to a SCUBA diver pressure tank generating a continuous and gentle water circulation. This ensures a complete mixture of suspended particles, and thereby, a maximum filtration by the bivalves. An in situ fluorometer was mounted to record plant pigment reduction due to mussel...

  15. Thyasirid bivalves from Cretaceous and Paleogene cold seeps

    Directory of Open Access Journals (Sweden)

    Krzysztof Hryniewicz

    2017-11-01

    Full Text Available We present a systematic study of thyasirid bivalves from Cretaceous to Oligocene seep carbonates worldwide. Eleven species of thyasirid bivalves are identified belonging to three genera: Conchocele, Maorithyas, and Thyasira. Two species are new: Maorithyas humptulipsensis sp. nov. from middle Eocene seep carbonates in the Humptulips Formation, Washington State, USA, and Conchocele kiritachiensis sp. nov. from the late Eocene seep deposit at Kiritachi, Hokkaido, Japan. Two new combinations are provided: Conchocele townsendi (White, 1890 from Maastrichtian strata of the James Ross Basin, Antarctica, and Maorithyas folgeri (Wagner and Schilling, 1923 from Oligocene rocks from California, USA. Three species are left in open nomenclature. We show that thyasirids have Mesozoic origins and appear at seeps before appearing in “normal” marine environments. These data are interpreted as a record of seep origination of thyasirids, and their subsequent dispersal to non-seep environments. We discuss the age of origination of thyasirids in the context of the origin of the modern deep sea fauna and conclude that thyasirids could have deep sea origins. This hypothesis is supported by the observed lack of influence of the Cretaceous and Paleogene Oceanic Anoxic Events on the main evolutionary lineages of the thyasirids, as seen in several other members of the deep sea fauna.

  16. Bivalve grazing, nutrient cycling and phytoplankton dynamics in an estuarine ecosystem

    NARCIS (Netherlands)

    Prins, T.C.

    1996-01-01


    This thesis has considered the impact of the suspension feeding bivalve Mytilusedulis on nutrient cycling and phytoplankton in an estuarine ecosystem. The research was started within the framework of an extensive research project with the

  17. An integrated ecosystem approach for assessing the potential role of cultivated bivalve shells as part of the carbon trading system

    NARCIS (Netherlands)

    Filgueira, R.; Byron, C.J.; Comeau, L.A.; Jansen, H.M.; Smaal, A.C.

    2015-01-01

    The role of bivalve mariculture in the CO2 cycle has been commonly evaluated as the balance between respiration, shell calcium carbonate sequestration and CO2 release during biogenic calcification. However, this approach neglects the ecosystem implications of cultivating bivalves at high densities,

  18. Labelling and Marketing of Bivalve and Gastropod Molluscs Retailed in Sardinia, Italy Between 2009 and 2013.

    Science.gov (United States)

    Meloni, Domenico

    2015-05-28

    The aim of the present survey was to investigate the correct enforcement of the Community rules on the labelling and marketing of bivalve and gastropod molluscs retailed in Sardinia, Italy between 2009 and 2013. A total of 1500 packages and labels for live bivalve and gastropod molluscs were considered. A total of 375 labels (25%) presented non-compliance concerning the wrong trade name and additional wrong or missing information. The highest percentage of anomalous labels has been detected in small-scale retail shops (35%) and open-air markets (25%) compared with the big retailing chains (20%). The 5% of packages were not in compliance with the European Community rules on packaging of bivalve and gastropod molluscs. The high percentage of non-compliance with the European regulations on labelling results is a strong limitation for the consumers and highlights the need to improve the control system about labelling of seafood products.

  19. Biota connect aquatic habitats throughout freshwater ecosystem mosaics

    Science.gov (United States)

    Schofield, Kate A.; Alexander, Laurie C.; Ridley, Caroline E.; Vanderhoof, Melanie; Fritz, Ken M.; Autrey, Bradley; DeMeester, Julie; Kepner, William G.; Lane, Charles R.; Leibowitz, Scott; Pollard, Amina I.

    2018-01-01

    Freshwater ecosystems are linked at various spatial and temporal scales by movements of biota adapted to life in water. We review the literature on movements of aquatic organisms that connect different types of freshwater habitats, focusing on linkages from streams and wetlands to downstream waters. Here, streams, wetlands, rivers, lakes, ponds, and other freshwater habitats are viewed as dynamic freshwater ecosystem mosaics (FEMs) that collectively provide the resources needed to sustain aquatic life. Based on existing evidence, it is clear that biotic linkages throughout FEMs have important consequences for biological integrity and biodiversity. All aquatic organisms move within and among FEM components, but differ in the mode, frequency, distance, and timing of their movements. These movements allow biota to recolonize habitats, avoid inbreeding, escape stressors, locate mates, and acquire resources. Cumulatively, these individual movements connect populations within and among FEMs and contribute to local and regional diversity, resilience to disturbance, and persistence of aquatic species in the face of environmental change. Thus, the biological connections established by movement of biota among streams, wetlands, and downstream waters are critical to the ecological integrity of these systems. Future research will help advance our understanding of the movements that link FEMs and their cumulative effects on downstream waters.

  20. Growth rates and geochemical proxies in Late Campanian bivalves - New insights from micro-X-ray Fluorescence mapping and numerical growth modelling

    Science.gov (United States)

    de Winter, Niels; Goderis, Steven; van Malderen, Stijn; Vanhaecke, Frank; Claeys, Philippe

    2017-04-01

    Understanding the Late Cretaceous greenhouse climate is of vital importance for understanding present and future climate change. While a lot of good work has been done to reconstruct climate in this interesting period, most paleoclimatic studies have focused on long-term climate change[1]. Alternatively, multi-proxy records from marine bivalves provide us with a unique opportunity to study past climate on a seasonal scale. However, previous fossil bivalve studies have reported ambiguous results with regard to the interpretation of trace element and stable isotope proxies in marine bivalve shells[2]. One major problem in the interpretation of such records is the bivalve's vital effect and the occurrence of disequilibrium fractionation during bivalve growth. Both these problems are linked to the annual growth cycle of marine bivalves, which introduces internal effects on the incorporation of isotopes and trace elements into the shell[3]. Understanding this growth cycle in extinct bivalves is therefore of great importance for the interpretation of seasonal proxy records in their shells. In this study, three different species of extinct Late Campanian bivalves (two rudist species and one oyster species) that were found in the same stratigraphic interval are studied. Micro-X-Ray Fluorescence line scanning and mapping of trace elements such as Mg, Sr, S and Zn, calibrated by LA-ICP-MS measurements, is combined with microdrilled stable carbon and oxygen isotope analysis on the well-preserved part of the shells. Data of this multi-proxy study is compared with results from a numerical growth model written in the open-source statistics package R[4] and based on annual growth increments observed in the shells and shell thickness. This growth model is used together with proxy data to reconstruct rates of trace element incorporation into the shell and to calculate the mass balance of stable oxygen and carbon isotopes. In order to achieve this goal, 2D mapping of bivalve shell

  1. The potential accumulation of polycyclic aromatic hydrocarbons in phytoplankton and bivalves in Can Gio coastal wetland, Vietnam.

    Science.gov (United States)

    Thuy, Hoang Thi Thanh; Loan, Tu Thi Cam; Phuong, Trinh Hong

    2018-05-12

    Polycyclic aromatic hydrocarbons (PAHs) are one of the most important classes of anthropogenic persistent organic contaminants in the marine environment. This review discusses a whole range of findings that address various aspects of the bioaccumulation of PAHs in two common marine biota (phytoplankton and bivalves) globally and especially for Can Gio coastal wetland, Vietnam. The published information and collected data on the bioconcentration and accumulation mechanisms of PAHs as well as implications for Can Gio coastal wetland are compiled for phytoplankton and bivalves. PAHs are still released to Can Gio coastal environments from various sources and then transported to coastal environments through various physical processes; they may enter marine food chains and be highly accumulated in phytoplankton and bivalves. Thus, PAHs' bioaccumulation should be considered as one important criterion to assess the water's quality, directly linked to human health due to seafood consumption. Ecologically, Can Gio coastal wetland plays an important role to the South Vietnam key economic zone. However, it is also an area of potential PAHs inputs. With the abundant phytoplankton and bivalves in Can Gio coastal wetland, the PAHs bioaccumulation in these biota is inevitably detected. Thus, further study on the bioavailability of these contaminants is urgently needed in order to mitigate their negative effects and protect the ecosystems.

  2. 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 ...

  3. Wood-Boring Bivalves (Mollusca: Teredinidae, Pholadidae) of Pacific coast of Colombia

    International Nuclear Information System (INIS)

    Cantera K, Jaime R

    2010-01-01

    Twelve species of wood-boring bivalves, ten of the family Teredinidae and two of family Pholadidae were collected in mangroves at 6 locations of the Pacific coast of Colombia. This paper presents a brief escription of these species, including size, ecological notes and geographical distribution.

  4. Labelling and marketing of bivalve and gastropod molluscs retailed in Sardinia, Italy between 2009 and 2013

    Directory of Open Access Journals (Sweden)

    Domenico Meloni

    2015-06-01

    Full Text Available The aim of the present survey was to investigate the correct enforcement of the Community rules on the labelling and marketing of bivalve and gastropod molluscs retailed in Sardinia, Italy between 2009 and 2013. A total of 1500 packages and labels for live bivalve and gastropod molluscs were considered. A total of 375 labels (25% presented non-compliance concerning the wrong trade name and additional wrong or missing information. The highest percentage of anomalous labels has been detected in small-scale retail shops (35% and open-air markets (25% compared with the big retailing chains (20%. The 5% of packages were not in compliance with the European Community rules on packaging of bivalve and gastropod molluscs. The high percentage of non-compliance with the European regulations on labelling results is a strong limitation for the consumers and highlights the need to improve the control system about labelling of seafood products.

  5. Semi-automatic surface sediment sampling system - A prototype to be implemented in bivalve fishing surveys

    Science.gov (United States)

    Rufino, Marta M.; Baptista, Paulo; Pereira, Fábio; Gaspar, Miguel B.

    2018-01-01

    In the current work we propose a new method to sample surface sediment during bivalve fishing surveys. Fishing institutes all around the word carry out regular surveys with the aim of monitoring the stocks of commercial species. These surveys comprise often more than one hundred of sampling stations and cover large geographical areas. Although superficial sediment grain sizes are among the main drivers of benthic communities and provide crucial information for studies on coastal dynamics, overall there is a strong lack of this type of data, possibly, because traditional surface sediment sampling methods use grabs, that require considerable time and effort to be carried out on regular basis or on large areas. In face of these aspects, we developed an easy and un-expensive method to sample superficial sediments, during bivalve fisheries monitoring surveys, without increasing survey time or human resources. The method was successfully evaluated and validated during a typical bivalve survey carried out on the Northwest coast of Portugal, confirming that it had any interference with the survey objectives. Furthermore, the method was validated by collecting samples using a traditional Van Veen grabs (traditional method), which showed a similar grain size composition to the ones collected by the new method, on the same localities. We recommend that the procedure is implemented on regular bivalve fishing surveys, together with an image analysis system to analyse the collected samples. The new method will provide substantial quantity of data on surface sediment in coastal areas, using a non-expensive and efficient manner, with a high potential application in different fields of research.

  6. Near infra-red spectroscopy quantitative modelling of bivalve protein, lipid and glycogen composition using single-species versus multi-species calibration and validation sets

    Science.gov (United States)

    Bartlett, Jill K.; Maher, William A.; Purss, Matthew B. J.

    2018-03-01

    Near infrared spectroscopy (NIRS) quantitative modelling was used to measure the protein, lipid and glycogen composition of five marine bivalve species (Saccostrea glomerata, Ostrea angasi, Crassostrea gigas, Mytilus galloprovincialis and Anadara trapezia) from multiple locations and seasons. Predictive models were produced for each component using individual species and aggregated sample populations for the three oyster species (S. glomerata, O. angasi and C. gigas) and for all five bivalve species. Whole animal tissues were freeze dried, ground to > 20 μm and scanned by NIRS. Protein, lipid and glycogen composition were determined by traditional chemical analyses and calibration models developed to allow rapid NIRS-measurement of these components in the five bivalve species. Calibration modelling was performed using wavelet selection, genetic algorithms and partial least squares analysis. Model quality was assessed using RPIQ and RMESP. For protein composition, single species model results had RPIQ values between 2.4 and 3.5 and RMSEP between 8.6 and 18%, the three oyster model had an RPIQ of 2.6 and an RMSEP of 10.8% and the five bivalve species had an RPIQ of 3.6 and RMSEP of 8.7% respectively. For lipid composition, single species models achieved RPIQ values between 2.9 and 5.3 with RMSEP between 9.1 and 11.2%, the oyster model had an RPIQ of 3.6 and RMSEP of 6.8 and the five bivalve model had an RPIQ of 5.2 and RMSEP of 6.8% respectively. For glycogen composition, the single species models had RPIQs between 3.8 and 18.9 with RMSEP between 3.5 and 9.2%, the oyster model had an RPIQ of 5.5 and RMSEP of 7.1% and the five bivalve model had an RPIQ of 4 and RMSEP of 7.6% respectively. Comparison between individual species models and aggregated models for three oyster species and five bivalve species for each component indicate that aggregating data from like species produces high quality models with robust and reliable quantitative application. The benefit of

  7. Marine Bivalve Cellular Responses to Beta Blocker Exposures ...

    Science.gov (United States)

    β blockers are prescription drugs used for medical treatment of hypertension and arrhythmias. They prevent binding of agonists such as catecholamines to β adrenoceptors. In the absence of agonist induced activation of the receptor, adenylate cyclase is not activated which in turn limits cAMP production and protein kinase A activation, preventing increases in blood pressure and arrhythmias. After being taken therapeutically, commonly prescribed β blockers may make their way to coastal habitats via discharge from waste water treatment plants (WWTP) posing a potential risk to aquatic organisms. The aim of our research is to evaluate cellular responses of three commercially important marine bivalves - Eastern oysters, blue mussels and hard clams - upon exposure to two β blocker drugs, propranolol and metoprolol, and to find molecular initiating events (MIEs) indicative of the exposure. Bivalves were obtained from Narragansett Bay (Rhode Island, USA) and acclimated in the laboratory. Following acclimation, gills and hepatopancreas (HP) tissues were harvested and separately exposed to 0, 1, 10, 100 and 1000 ng/l of each drug. Tissues were bathed in 30 parts per thousand (ppt) filtered seawater, antibiotic mix, Leibovitz nutrient media, and the test drug. Exposures were conducted for 24 hours and samples were saved for cellular biomarker assays. A lysosomal destabilization assay, which is a marker of membrane damage, was also performed at the end of each exposure.

  8. Distribution of organotin compounds in the bivalves of the Aegean Sea, Greece

    NARCIS (Netherlands)

    Chandrinou, S.; Pappas, K.; Nikolaou, A.; Stasinakis, A.S.; Wegener, J.W.M.; Alexandropoulos, Th.; Thomaidis, N.S.

    2007-01-01

    Five bivalve species - Mytilus galloprovinciallis (Mediterranean mussels), Venus gallina (stripped venus), Modiola barbatus L. (bearded horse mussels), Pecten jacobeus (scallops) and Callista chione (hard clams) - were collected from seven areas in Aegean Sea, Greece, between August 2001 and January

  9. Indian marine bivalves: Potential source of antiviral drugs

    Digital Repository Service at National Institute of Oceanography (India)

    Chatterji, A.; Ansari, Z.A.; Ingole, B.S.; Bichurina, M.A.; Sovetova, M.; Boikov, Y.A.

    in large quantities by traditional methods and sold live in the market for human consumption. The economically important sp e cies of marine bivalves are green mussel ( Perna viridis ), e s tuarine oyster ( Crassostrea madrasensis ), giant oyster... in developing an effecti ve drug has been the unique characteristics of antigenic variation of virus resulting in the emergence of new variant virus strains 14 . There are a number of antiviral drugs introduced in the market such as tricyclic sy m- metric...

  10. Adaptive morphologies and guild structure in a high-diversity bivalve fauna from an early Campanian rocky shore, Ivö Klack (Sweden)

    DEFF Research Database (Denmark)

    Sørensen, Anne Mehlin; Surlyk, Finn; Jagt, John W. M.

    2012-01-01

    habitats. Study of the functional morphology of bivalve shells and comparison with extant relatives has resulted in a subdivision of the fauna into seven guilds and five habitats. The bivalve fauna represents a withinhabitat, time-averaged assemblage to which none of the species was introduced from...

  11. Comparative in vitro study on free radical scavenging potential of selected bivalve species

    Digital Repository Service at National Institute of Oceanography (India)

    Shenai-Tirodkar, P.S.; Pawar, R.T.; Jagtap, T.G.

    Bivalves such as, Crassostrea spp., Meretrix casta, Placuna placenta and Polymesoda erosa are largely consumed as edible seafood. It forms natural source of nutrition in coastal and worldwide population. Free radical scavenging activities...

  12. Chemosynthetic bacteria found in bivalve species from mud volcanoes of the Gulf of Cadiz.

    Science.gov (United States)

    Rodrigues, Clara F; Webster, Gordon; Cunha, Marina R; Duperron, Sébastien; Weightman, Andrew J

    2010-09-01

    As in other cold seeps, the dominant bivalves in mud volcanoes (MV) from the Gulf of Cadiz are macrofauna belonging to the families Solemyidae (Acharax sp., Petrasma sp.), Lucinidae (Lucinoma sp.), Thyasiridae (Thyasira vulcolutre) and Mytilidae (Bathymodiolus mauritanicus). The delta(13)C values measured in solemyid, lucinid and thyasirid specimens support the hypothesis of thiotrophic nutrition, whereas isotopic signatures of B. mauritanicus suggest methanotrophic nutrition. The indication by stable isotope analysis that chemosynthetic bacteria make a substantial contribution to the nutrition of the bivalves led us to investigate their associated bacteria and their phylogenetic relationships based on comparative 16S rRNA gene sequence analysis. PCR-denaturing gradient gel electrophoresis analysis and cloning of bacterial 16S rRNA-encoding genes confirmed the presence of sulfide-oxidizing symbionts within gill tissues of many of the studied specimens. Phylogenetic analysis of bacterial 16S rRNA gene sequences demonstrated that most bacteria were related to known sulfide-oxidizing endosymbionts found in other deep-sea chemosynthetic environments, with the co-occurrence of methane-oxidizing symbionts in Bathymodiolus specimens. This study confirms the presence of several chemosynthetic bivalves in the Gulf of Cadiz and further highlights the importance of sulfide- and methane-oxidizing symbionts in the trophic ecology of macrobenthic communities in MV.

  13. Mantle biopsy: a technique for nondestructive tissue-sampling of freshwater mussels

    Science.gov (United States)

    David J. Berg; Wendell R. Haag; Sheldon I. Guttman; James B. Sickel

    1995-01-01

    Mantle biopsy is a means of obtaining tissue samples for genetic, physiological, and contaminant studies of bivalves; but the effects of this biopsy on survival have not been determined. We describe a simple technique for obtaining such samples from unionacean bivalves and how we compared survival among biopsied and control organisms in field experiments. Survival was...

  14. Distribution of DTHS3 satellite DNA across 12 bivalve species Eva ...

    Indian Academy of Sciences (India)

    Windows User

    In this work, characterization of DTHS3 satellite DNA was further expanded within the Class. Bivalvia. Monomer variants of DTHS3 satDNA were compared in 12 bivalve species belonging to two different Subclasses, Heterodonta and Pteriomorphia. This satDNA, whose age is estimated to a minimum of 516 Ma, ...

  15. Feeding current characteristics of three morphologically different bivalve suspension feeders, Crassostrea gigas, Mytilus edulis and Cerastoderma edule, in relation to food competition

    NARCIS (Netherlands)

    Troost, K.; Stamhuis, E.J.; van Duren, L.A; Wolff, W.J.

    Introduced Pacific oysters (Crassostrea gigas) have shown rapid expansion in the Oosterschelde estuary, while stocks of native bivalves declined slightly or remained stable. This indicates that they might have an advantage over native bivalve filter feeders. Hence, at the scale of individual

  16. Feeding current characteristics of three morphologically different bivalve suspension feeders, Crassostrea gigas Mytilus edulis and Cerastoderma edule , in relation to food competition

    NARCIS (Netherlands)

    Troost, K.; Stamhuis, E.J.; Duren, L.A.; Wolff, W.

    2009-01-01

    Introduced Pacific oysters (Crassostrea gigas) have shown rapid expansion in the Oosterschelde estuary, while stocks of native bivalves declined slightly or remained stable. This indicates that they might have an advantage over native bivalve filter feeders. Hence, at the scale of individual

  17. Paleoecological insights from fossil freshwater mollusks of the Kanapoi Formation (Omo-Turkana Basin, Kenya).

    Science.gov (United States)

    Van Bocxlaer, Bert

    2017-09-13

    The Early Pliocene Kanapoi Formation of the Omo-Turkana Basin consists of two fluvial/deltaic sedimentary sequences with an intermediate lacustrine sequence that was deposited in Paleolake Lonyumun, the earliest large lake in the basin. Overall, the geology and vertebrate paleontology of the Kanapoi Formation are well studied, but its freshwater mollusks, despite being a major component of the benthic ecosystem, have not been subjected to in-depth study. Here I present the first treatment of these mollusks, which have been retrieved mainly from the lacustrine but also from the upper fluvial sediments, with a focus on paleoecological implications. Overall, the freshwater mollusk fauna is reasonably diverse and contains the gastropods Bellamya (Viviparidae), Melanoides (Thiaridae), Cleopatra (Paludomidae) and Gabbiella (Bithyniidae), as well as the unionoid bivalves Coelatura, Pseudobovaria (Unionidae), Aspatharia, Iridina (Iridinidae) and Etheria (Etheriidae). Material is typically recrystallized and lithified and its taphonomy suggests deposition in a system with intermediate energy, such as a beach, with post-depositional deformation and abrasion. The mollusk assemblage is indicative of perennial, fresh and well-oxygenated waters in the Kanapoi region. It suggests that Paleolake Lonyumun had largely open shores with limited vegetation and that swampy or ephemeral backwaters were rare. Overall, these findings support earlier paleoecological interpretations based on the fish assemblage of Paleolake Lonyumun at Kanapoi. Moreover, mollusk assemblages from this lake are very similar across the Omo-Turkana Basin (Nachukui, Usno, Mursi and Koobi Fora Formations) suggesting that the lacustrine paleoecological conditions found in the Kanapoi Formation existed throughout the basin. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Uranium(VI) speciation: modelling, uncertainty and relevance to bioavailability models. Application to uranium uptake by the gills of a freshwater bivalve; Speciation de l'uranium(6), modelisation, incertitude et implication pour les modeles de biodisponibilite. Application a l'accumulation dans les branchies d'un bivalve d'eau douce

    Energy Technology Data Exchange (ETDEWEB)

    Denison, F.H

    2004-07-01

    The effects of varying solution composition on the interactions between uranium(VI) and excised gills of the freshwater bivalve Corbicula fluminea have been investigated in well defined solution media. A significant reduction in the uptake of uranium was observed on increasing the concentrations of the uranium complexing ligands citrate and carbonate. Saturation kinetics as a function of uranium concentration at a pH value of 5.0 were observed, indicating that the uptake of uranium is a facilitated process, probably involving one or several trans-membrane transport systems. A relatively small change in the uptake of uranium was found as a function of pH (factor of ca. 2), despite the extremely large changes to the solution speciation of uranium within the range of pH investigated (5.0 - 7.5). A comprehensive review of the thermodynamic data relevant to the solution composition domain employed for this study was performed. Estimates of the uncertainties for the formation constants of aqueous uranium(VI) species were integrated into a thermodynamic database. A computer program was written to predict the equilibrium distribution of uranium(VI) in simple aqueous systems, using thermodynamic parameter mean-values. The program was extended to perform Monte Carlo and Quasi Monte Carlo uncertainty analyses, incorporating the thermodynamic database uncertainty estimates, to quantitatively predict the uncertainties inherent in predicting the solution speciation of uranium. The use of thermodynamic equilibrium modelling as a tool for interpreting the bioavailability of uranium(VI) was investigated. Observed uranium(VI) uptake behaviour was interpreted as a function of the predicted changes to the solution speciation of uranium. Different steady-state or pre-equilibrium approaches to modelling uranium uptake were tested. Alternative modelling approaches were also tested, considering the potential changes to membrane transport system activity or sorption characteristics on

  19. Contamination in sediments, bivalves and sponges of McMurdo Sound, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Negri, Andrew [Australian Institute of Marine Science, PMB 3, Townsville, Qld (Australia)]. E-mail: a.negri@aims.gov.au; Burns, Kathryn [Australian Institute of Marine Science, PMB 3, Townsville, Qld (Australia); Boyle, Steve [Australian Institute of Marine Science, PMB 3, Townsville, Qld (Australia); Brinkman, Diane [Australian Institute of Marine Science, PMB 3, Townsville, Qld (Australia); Webster, Nicole [Australian Institute of Marine Science, PMB 3, Townsville, Qld (Australia); Biological Sciences, University of Canterbury, Christchurch (New Zealand)

    2006-10-15

    This study examined the concentrations of total hydrocarbons (THC), polychlorinated biphenyls (PCB), polyaromatic hydrocarbons (PAH), and trace metals (Cu, Zn, Cd, Pb, Hg and As) in marine sediments off Scott Base (NZ) and compared them with sediments near the highly polluted McMurdo Station (US) as well as less impacted sites including Turtle Rock and Cape Evans. The Antarctic mollusc, Laternula elliptica and three common sponge species were also analysed for trace metals. The mean THC concentration in sediments from Scott Base was 3 fold higher than the pristine site, Turtle Rock, but 10 fold lower than samples from McMurdo Station. McMurdo Station sediments also contained the highest concentrations of PAHs, PCBs and the trace metals, Cu, Zn, Pb, Cd and Hg. Copper was significantly higher in bivalves from McMurdo Station than other sites. Trace metal concentrations in sponges were generally consistent within sites but no spatial patterns were apparent. - Analyses of Antarctic marine sediments, bivalves and sponges revealed strong PAH, PCB and trace metal gradients in McMurdo Sound.

  20. Contamination in sediments, bivalves and sponges of McMurdo Sound, Antarctica

    International Nuclear Information System (INIS)

    Negri, Andrew; Burns, Kathryn; Boyle, Steve; Brinkman, Diane; Webster, Nicole

    2006-01-01

    This study examined the concentrations of total hydrocarbons (THC), polychlorinated biphenyls (PCB), polyaromatic hydrocarbons (PAH), and trace metals (Cu, Zn, Cd, Pb, Hg and As) in marine sediments off Scott Base (NZ) and compared them with sediments near the highly polluted McMurdo Station (US) as well as less impacted sites including Turtle Rock and Cape Evans. The Antarctic mollusc, Laternula elliptica and three common sponge species were also analysed for trace metals. The mean THC concentration in sediments from Scott Base was 3 fold higher than the pristine site, Turtle Rock, but 10 fold lower than samples from McMurdo Station. McMurdo Station sediments also contained the highest concentrations of PAHs, PCBs and the trace metals, Cu, Zn, Pb, Cd and Hg. Copper was significantly higher in bivalves from McMurdo Station than other sites. Trace metal concentrations in sponges were generally consistent within sites but no spatial patterns were apparent. - Analyses of Antarctic marine sediments, bivalves and sponges revealed strong PAH, PCB and trace metal gradients in McMurdo Sound

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

    Science.gov (United States)

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

    2017-05-01

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

  2. Availability of pearl producing marine bivalves in south-eastern coast of Bangladesh and culture potentialities

    Directory of Open Access Journals (Sweden)

    Md Ataur Rahman

    2015-12-01

    Full Text Available The present study was conducted during September 2014 to July 2015 to identify the pearl bearing bivalves in south-eastern coast of Bangladesh and culture potentialities of marine oyster in captivity based on field investigation. A total of 7 pearl bearing bivalve species were identified in the coast with a salinity of 18-34 ppt, pH 8.1-8.3 and water depth ranged 0.2-2.0 meter in their habitat. From the collected bivalves, most abundant oyster species windowpane oyster, Placuna placenta (Linnaeus, 1758 was reared in fiber glass tanks with seawater for a period of 6 months. During rearing highest survival rate of 88% was observed in T1 with sandy and gravel substratum and lowest survival rate of 78% was found in T2 with muddy substratum. Average temperature and salinity were varied between 24 °C-25 °C and 21-26 ppt respectively. From the reared oyster, highest 54 nos. small pearls in the month of April and lowest 7 pearls in December from a single P. placenta were obtained. The study proved that pearls can be obtained from the marine oysters in captivity in Bangladesh, and this offers large scale culture potentialities in our coast.

  3. Climate change and body size shift in Mediterranean bivalve assemblages: unexpected role of biological invasions.

    Science.gov (United States)

    Nawrot, Rafał; Albano, Paolo G; Chattopadhyay, Devapriya; Zuschin, Martin

    2017-08-16

    Body size is a synthetic functional trait determining many key ecosystem properties. Reduction in average body size has been suggested as one of the universal responses to global warming in aquatic ecosystems. Climate change, however, coincides with human-enhanced dispersal of alien species and can facilitate their establishment. We address effects of species introductions on the size structure of recipient communities using data on Red Sea bivalves entering the Mediterranean Sea through the Suez Canal. We show that the invasion leads to increase in median body size of the Mediterranean assemblage. Alien species are significantly larger than native Mediterranean bivalves, even though they represent a random subset of the Red Sea species with respect to body size. The observed patterns result primarily from the differences in the taxonomic composition and body-size distributions of the source and recipient species pools. In contrast to the expectations based on the general temperature-size relationships in marine ectotherms, continued warming of the Mediterranean Sea indirectly leads to an increase in the proportion of large-bodied species in bivalve assemblages by accelerating the entry and spread of tropical aliens. These results underscore complex interactions between changing climate and species invasions in driving functional shifts in marine ecosystems. © 2017 The Author(s).

  4. Comparative sensitivity of European native (Anodonta anatina) and exotic (Corbicula fluminea) bivalves to mercury

    Science.gov (United States)

    Oliveira, Patrícia; Lopes-Lima, Manuel; Machado, Jorge; Guilhermino, Lúcia

    2015-12-01

    Pollution is believed to be an important factor modulating the competition between exotic invasive bivalves and their native competitors. Thus, the objective of the present study was to compare the sensitivity of the European native Anodonta anatina and the exotic invasive species Corbicula fluminea to mercury, a ubiquitous environmental contaminant of high concern. In laboratory acute bioassays, adult organisms of both species were exposed independently to mercury for 96 h (31-500 μg/L). The criteria indicative of toxicity were mortality and biomarkers of oxidative stress and damage, neurotoxicity, and energy production changes. Mercury induced mortality in A. anatina (72 h-LC10 and 72 h-LC50 of 14.0 μg/L and 49.6 μg/L, respectively) but not in C. fluminea. The ability of C. fluminea to maintaining the shell closed for considerable periods of time when exposed to high concentrations of mercury and the effective activation (up to 63 μg/L) of mechanisms against the oxidative stress caused by mercury may have contributed to its relatively low sensitivity. In the range of concentrations tested, mercury had no significant effects on the other parameters analysed in C. fluminea. Overall, the findings of the present study, suggest that in real scenarios of competition between C. fluminea and A. anatina populations, the presence of mercury may modulate the process, acting in favour of the exotic species because it is less sensitive to this environmental contaminant than the native bivalve. The results of the present study highlight the need of further investigation on the effects of mercury on the competition between exotic invasive species and their native competitors, especially the effects potentially induced by long-term exposure to low concentrations of this metal, the mechanisms involved in the tolerance to mercury-induced stress, and the potential post-exposure recovery of both exotic invasive and native bivalves. This knowledge is most important for

  5. Ecology of megabenthic bivalve communities from sandy beaches on the south coast of Portugal

    Directory of Open Access Journals (Sweden)

    Marta M. Rufino

    2010-03-01

    Full Text Available Ecological aspects of 75 megabenthic bivalve species found on the south coast of Portugal (from Vila Real to Sagres were studied based on the information provided by seasonal bivalve surveys from 2000 to 2007 (8600 hauls, simultaneously using a razor shell dredge and a clam dredge. Of the 75 species identified, 36 occurred less than 30 times, and thus were considered rare in the area. The remaining 39 bivalves were analysed according to their occurrence, bathymetric distribution, geographic preferences, seasonal preferences, burying-depth, beach exposure and river mouth proximity. All species belonging to the Pharidae and Solenidae families (razor shells and most Tellinidae were significantly more frequent in the razor shell dredge (indicating deeper burying in the sediment, whilst the families Cardiidae and Donacidae were significantly more frequent in the clam dredge (indicating that these species are probably closer to the sediment surface. As for the season, most bivalve species occurred similarly in both seasons (19 sp; 49%, but a large proportion were more abundant during the autumn surveys (17 sp., 44%, whereas only three species were commoner during the spring surveys. Most species belonging to the families Cardiidae and Mactridae were commoner in the autumn surveys. The spatial distribution differed between species and cluster analysis identified four communities with greater geographic affinity. Species belonging to the family Cardiidae were preferably found in the western part (WB and the eastern part (S of the study area, whereas the families Donacidae, Mactridae and Tellinidae occurred mainly in the central area (EB and the eastern (S coastal sectors. Overall, shallower species (modal depth at 3-6 m showed greater occurrences and abundances than the deeper ones, and the depth pattern observed did not change between seasons. Donacidae and Mactridae (except Mactra glauca were represented essentially by shallow species, whereas

  6. Molecular and Biochemical Methods Useful for the Epigenetic Characterization of Chromatin-Associated Proteins in Bivalve Molluscs

    Directory of Open Access Journals (Sweden)

    Ciro Rivera-Casas

    2017-08-01

    Full Text Available Bivalve molluscs constitute a ubiquitous taxonomic group playing key functions in virtually all ecosystems, and encompassing critical commercial relevance. Along with a sessile and filter-feeding lifestyle in most cases, these characteristics make bivalves model sentinel organisms routinely used for environmental monitoring studies in aquatic habitats. The study of epigenetic mechanisms linking environmental exposure and specific physiological responses (i.e., environmental epigenetics stands out as a very innovative monitoring strategy, given the role of epigenetic modifications in acclimatization and adaptation. Furthermore, the heritable nature of many of those modifications constitutes a very promising avenue to explore the applicability of epigenetic conditioning and selection in management and restoration strategies. Chromatin provides a framework for the study of environmental epigenetic responses. Unfortunately, chromatin and epigenetic information are very limited in most non-traditional model organisms and even completely lacking in most environmentally and ecologically relevant organisms. The present work aims to provide a comprehensive and reproducible experimental workflow for the study of bivalve chromatin. First, a series of guidelines for the molecular isolation of genes encoding chromatin-associated proteins is provided, including information on primers suitable for conventional PCR, Rapid Amplification of cDNA Ends (RACE, genome walking and quantitative PCR (qPCR experiments. This section is followed by the description of methods specifically developed for the analysis of histone and SNBP proteins in different bivalve tissues, including protein extraction, purification, separation and immunodetection. Lastly, information about available antibodies, their specificity and performance is also provided. The tools and protocols described here complement current epigenetic analyses (usually limited to DNA methylation by incorporating

  7. Interpopulational variability of molecular responses to ionizing radiation in freshwater bivalves Anodonta anatina (Unionidae)

    Energy Technology Data Exchange (ETDEWEB)

    Falfushynska, H. [Research Laboratory of Comparative Biochemistry and Molecular Biology, Ternopil National Pedagogical University, 2, Kryvonosa Str, Ternopil 46027 (Ukraine); Department of Biological Sciences, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 28223 (United States); Department of General Chemistry, I.Ya. Horbachevsky Ternopil State Medical University, 1, Maidan Voli, Ternopil 46001 (Ukraine); Gnatyshyna, L. [Research Laboratory of Comparative Biochemistry and Molecular Biology, Ternopil National Pedagogical University, 2, Kryvonosa Str, Ternopil 46027 (Ukraine); Department of General Chemistry, I.Ya. Horbachevsky Ternopil State Medical University, 1, Maidan Voli, Ternopil 46001 (Ukraine); Yurchak, I.; Stoliar, O. [Research Laboratory of Comparative Biochemistry and Molecular Biology, Ternopil National Pedagogical University, 2, Kryvonosa Str, Ternopil 46027 (Ukraine); Sokolova, I.M., E-mail: isokolova@uncc.edu [Department of Biological Sciences, University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 28223 (United States)

    2016-10-15

    Freshwater ecosystems are exposed to multiple anthropogenic stressors including chemical pollution and warming that can affect health of the resident organisms and their responses to novel challenges. We investigated the of in situ exposure history on molecular responses to a novel stressor, ionizing radiation, in unionid mollusks Anodonta anatina. Males from pristine (F-), agricultural (A-) sites and a cooling reservoir of a nuclear power plant (N-site) were exposed to acute low dose (2 mGy) X-ray radiation followed by 14 days of recovery (R-groups) or to control conditions (C-groups). Biomarkers of oxidative stress, geno-, cyto- and neurotoxicity were used to assess cellular injury and stress. Control group from the cooling reservoir (CN) had higher background levels of caspase-3 activity, metallothionein concentrations and nuclear lesions and lower levels of superoxide dismutase (SOD) and glutathione in the gills compared to other control groups (CF and CA). Irradiation induced cellular damage in mussels from all three sites including increased levels of nuclear lesions in hemocytes, depletion of caspase-3, suppression of superoxide dismutase and catalase activities, an increase of the lipid peroxidation and oxidized glutathione levels, as well as down-regulation of cholinesterase indicating neurotoxicity. The up-regulation of ethoxyresorufin-O-deethylase activity in the digestive gland and vitellogenin-like protein level in gonads were also found in radiation-exposed groups indicating feminization of males and disturbances of xenobiotic metabolism. The RA-group showed the greatest magnitude of radiation-induced stress responses compared to the other two groups. Overall, unionid mollusks, particularly those from a chronically polluted agricultural site, were highly sensitive to low-dose radiation (2 mGy) indicating limitations of stress protection mechanisms to deal with multiple stressors. - Highlights: • Habitat-specific effects of irradiation were studied

  8. Interpopulational variability of molecular responses to ionizing radiation in freshwater bivalves Anodonta anatina (Unionidae)

    International Nuclear Information System (INIS)

    Falfushynska, H.; Gnatyshyna, L.; Yurchak, I.; Stoliar, O.; Sokolova, I.M.

    2016-01-01

    Freshwater ecosystems are exposed to multiple anthropogenic stressors including chemical pollution and warming that can affect health of the resident organisms and their responses to novel challenges. We investigated the of in situ exposure history on molecular responses to a novel stressor, ionizing radiation, in unionid mollusks Anodonta anatina. Males from pristine (F-), agricultural (A-) sites and a cooling reservoir of a nuclear power plant (N-site) were exposed to acute low dose (2 mGy) X-ray radiation followed by 14 days of recovery (R-groups) or to control conditions (C-groups). Biomarkers of oxidative stress, geno-, cyto- and neurotoxicity were used to assess cellular injury and stress. Control group from the cooling reservoir (CN) had higher background levels of caspase-3 activity, metallothionein concentrations and nuclear lesions and lower levels of superoxide dismutase (SOD) and glutathione in the gills compared to other control groups (CF and CA). Irradiation induced cellular damage in mussels from all three sites including increased levels of nuclear lesions in hemocytes, depletion of caspase-3, suppression of superoxide dismutase and catalase activities, an increase of the lipid peroxidation and oxidized glutathione levels, as well as down-regulation of cholinesterase indicating neurotoxicity. The up-regulation of ethoxyresorufin-O-deethylase activity in the digestive gland and vitellogenin-like protein level in gonads were also found in radiation-exposed groups indicating feminization of males and disturbances of xenobiotic metabolism. The RA-group showed the greatest magnitude of radiation-induced stress responses compared to the other two groups. Overall, unionid mollusks, particularly those from a chronically polluted agricultural site, were highly sensitive to low-dose radiation (2 mGy) indicating limitations of stress protection mechanisms to deal with multiple stressors. - Highlights: • Habitat-specific effects of irradiation were studied

  9. Light indirectly mediates bivalve habitat modification and impacts on seagrass

    DEFF Research Database (Denmark)

    Castorani, Max C. N.; Glud, Ronnie; Hasler-Sheetal, Harald

    2015-01-01

    Environmental context may influence the sign, strength, andmechanisms of species interactions but few studies have experimentally tested the potential for abiotic conditions to mediate interactions through multiple cooccurring stress pathways. Abiotic conditionsmay mediate species interactions...... by directly or indirectly influencing the effects of habitat-modifying organisms that are capable of simultaneously ameliorating and exacerbating multiple stressors. Itwas hypothesized that light availability changes seagrassmetabolismand thereby indirectly regulates bivalve habitat modification...

  10. Freshwater Fish Communities

    Science.gov (United States)

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

  11. Exploring Freshwater Science

    Indian Academy of Sciences (India)

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

  12. Freshwater and fish

    International Nuclear Information System (INIS)

    Saxen, R.

    1997-01-01

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

  13. An ecosystem-based approach and management framework for the integrated evaluation of bivalve aquaculture impacts

    DEFF Research Database (Denmark)

    Cranford, Peter J.; Kamermans, Pauline; Krause, Gesche

    2012-01-01

    for bivalve aquaculture be based on a tiered indicator monitoring system that is structured on the principle that increased environmental risk requires increased monitoring effort. More than 1 threshold for each indicator would permit implementation of predetermined impact prevention and mitigation measures......An ecosystem-based approach to bivalve aquaculture management is a strategy for the integration of aquaculture within the wider ecosystem, including human aspects, in such a way that it promotes sustainable development, equity, and resilience of ecosystems. Given the linkage between social...... and ecological systems, marine regulators require an ecosystem-based decision framework that structures and integrates the relationships between these systems and facilitates communication of aquaculture–environment interactions and policy-related developments and decisions. The Drivers-Pressures-State Change-Impact-Response...

  14. Ocean acidification increases cadmium accumulation in marine bivalves: a potential threat to seafood safety.

    Science.gov (United States)

    Shi, Wei; Zhao, Xinguo; Han, Yu; Che, Zhumei; Chai, Xueliang; Liu, Guangxu

    2016-01-21

    To date, the effects of ocean acidification on toxic metals accumulation and the underlying molecular mechanism remains unknown in marine bivalve species. In the present study, the effects of the realistic future ocean pCO2 levels on the cadmium (Cd) accumulation in the gills, mantle and adductor muscles of three bivalve species, Mytilus edulis, Tegillarca granosa, and Meretrix meretrix, were investigated. The results obtained suggested that all species tested accumulated significantly higher Cd (p ocean acidification-induced increase in Cd accumulation may have occurred due to (i) the ocean acidification increased the concentration of Cd and the Cd(2+)/Ca(2+) in the seawater, which in turn increased the Cd influx through Ca channel; (ii) the acidified seawater may have brought about epithelia damage, resulting in easier Cd penetration; and (iii) ocean acidification hampered Cd exclusion.

  15. Characterizing Photosymbiosis Between Fraginae Bivalves and Symbiodinium Using Phylogenetics and Stable Isotopes

    Directory of Open Access Journals (Sweden)

    Jingchun Li

    2018-04-01

    Full Text Available Photosymbiotic associations between heterotrophic hosts and photosynthetic algae play crucial roles in maintaining the trophic and structural integrity of coral reef ecosystems. The marine bivalve subfamily Fraginae contains both non-symbiotic and photosymbiotic lineages, making it an ideal comparative system to study the origin and evolutionary adaptations of photosymbiosis. The symbiotic species exhibit unique morphological adaptations to photosymbiosis. However, the basic biology of these photosymbiotic relationships, such as symbiont diversity and nutritional benefits, has not been thoroughly characterized. In this study, we examined the general morphology of four Fraginae species occupying different depths (0–10 m: Corculum cardissa, Fragum fragum, Fragum scruposum, and Fragum sueziense. Abundant symbionts were found in the mantle, gill, and part of the foot, contained in tubular networks within host tissues. We used molecular phylogenetics to investigate the algal symbiont community of these Fraginae species. Results showed that symbionts from all four species are dinoflagellates belonging to the Symbiodinium clade C and we did not detect any host-specific or geographic-specific genetic structures within the symbionts. We also used stable carbon isotope analyses to examine whether the cockles are directly utilizing photosynthetically derived carbon sources. All species show less depleted 13C compared to filter-feeding bivalves, suggesting at least part of their organic carbon is derived directly from the symbionts. However, 13C depletion of Fragum sueziense collected from deeper habitats are less distinguishable from filter-feeding bivalves. This indicates that species in deeper habitats may rely less on photosymbiosis due to the reduced light availability. Given that the symbiotic fragines exhibit varying morphologies, habitats, and utilization of symbiont photosynthesis, the subfamily represents an ideal model system to study

  16. High pressure processing of bivalve shellfish and HPP's potential use as a virus intervention

    Science.gov (United States)

    Bivalve shellfish readily bioconcentrate pathogenic microbes and substance, such as algal and dinoflagulate toxins, fecal viruses and bacteria, and naturally present vibrio bacteria. High pressure processing (HPP) is currently used as an intervention for Vibrio vulnificus bacteria within molluscan ...

  17. Dinophysis caudata generated lipophilic shellfish toxins in bivalves from the Nanji Islands, East China Sea

    Science.gov (United States)

    Jiang, Tao; Xu, Yixiao; Li, Yang; Qi, Yuzao; Jiang, Tianjiu; Wu, Feng; Zhang, Fan

    2014-01-01

    A 12-month program of monitoring potentially toxic microalgae (that produce lipophilic shellfish toxins; LSTs) and their toxins in bivalves was conducted from April 2006 to March 2007 in the Nanji Islands, East China Sea. Two Dinophysis species, D. caudata and D. acuminata, were identified, and D. caudata was found to be the dominant species. D. caudata was detected in water samples between April and June 2006, and between February and March 2007. It reached its highest abundances in May, with a mean abundance of 1.38×102 cells/L in surface water and 1.25×102 cells/L in bottom water (cultured bivalves sampled between April and June were contaminated with LSTs, with an average toxicity of 85 μg okadaic acid (OA) eq./100 g meat, which was four times higher than the Chinese regulatory limit (20 μg OA eq./100 g meat). Ten out of fifteen wild samples (66.7%) collected during the same period were positive for LSTs, and contained an average LST toxicity of 45 μg OA eq./100 g meat (more than twice the regulatory value). Cultured Patinopecten yessoensis collected on 15 May 2006 had the highest toxicity, 320 μg OA eq./100 g meat, and relatively high toxicities (80 to 160 μg OA eq./100 g meat) were found in bivalves until the end of July.

  18. Advancing approaches for multi-year high-frequency monitoring of temporal and spatial variability in carbon cycle fluxes and drivers in freshwater lakes

    Science.gov (United States)

    Desai, A. R.; Reed, D. E.; Dugan, H. A.; Loken, L. C.; Schramm, P.; Golub, M.; Huerd, H.; Baldocchi, A. K.; Roberts, R.; Taebel, Z.; Hart, J.; Hanson, P. C.; Stanley, E. H.; Cartwright, E.

    2017-12-01

    Freshwater ecosystems are hotspots of regional to global carbon cycling. However, significant sample biases limit our ability to quantify and predict these fluxes. For lakes, scaled flux estimates suffer biased sampling toward 1) low-nutrient pristine lakes, 2) infrequent temporal sampling, 3) field campaigns limited to the growing season, and 4) replicates limited to near the center of the lake. While these biases partly reflect the realities of ecological sampling, there is a need to extend observations towards the large fraction of freshwater systems worldwide that are impaired by human activities and those facing significant interannual variability owing to climatic change. Also, for seasonally ice-covered lakes, much of the annual budget of carbon fluxes is thought to be explained by variation in the shoulder seasons of spring ice melt and fall turnover. Recent advances in automated, continuous multi-year temporal sampling coupled with rapid methods for spatial mapping of CO2 fluxes has strong potential to rectify these sampling biases. Here, we demonstrate these advances in an eutrophic seasonally-ice covered lake with an urban shoreline and agricultural watershed. Multiple years of half-hourly eddy covariance flux tower observations from two locations are coupled with frequent spatial samples of these fluxes and drivers by speedboat, floating chamber fluxes, automated buoy-based monitoring of lake nutrient and physical profiles, and ensemble of physical-ecosystem models. High primary productivity in the water column leads to an average net carbon sink during the growing season in much of the lake, but annual net carbon fluxes show the lake can act as an annual source or a sink of carbon depending the timing of spring and fall turnover. Trophic interactions and internal waves drive shorter-term variation while nutrients and biology drive seasonal variation. However, discrepancies remain among methods to quantify fluxes, requiring further investigation.

  19. Investigation into Cryptosporidium and Giardia in bivalve mollusks farmed in Sardinia region and destined for human consumption

    Directory of Open Access Journals (Sweden)

    Tiziana Tedde

    2013-06-01

    Full Text Available Cryptosporidium and Giardia are protozoan parasites transmitted by fecal-oral ingestion of (oocysts, and are responsible for enteritis in several animal species and humans worldwide. These (oocysts can survive for over a year in aquatic environments and can accumulate in bivalve mollusks, which filter large volumes of water. The aim of this study is to evaluate the natural occurrence of Cryptosporidium and Giardia contamination in different specimens of edible bivalves mollusks from farming sites of the western and north-eastern coasts of Sardinia. From April 2011 to February 2012, 1095 specimens of Mytilus galloprovincialis and 240 of Crassostrea gigas were sampled from Olbia and Oristano gulf and San Teodoro pond. Hepatopancreas and gills, including the labial palp, were examined for oocysts and cysts after pooling and homogenisation using different techniques: i staining for light and fluorescence microscopy; ii direct immunofluorescence (IF Merifluor® test Cryptosporidium/ Giardia (Meridian Bioscience Inc., Cincinnati, OH, USA; and iii molecular procedures. However, in the context under study, all mollusks examined with the three main diagnostic techniques were negative for both parasites pointing out the hypothetically low zoonotic risk related to Cryptosporidium and Giardia in bivalves, especially Mytilus galloprovincialis and Crassostrea gigas.

  20. Biochemical and behavioural responses of the endobenthic bivalve Scrobicularia plana to silver nanoparticles in seawater and microalgal food.

    Science.gov (United States)

    Buffet, Pierre-Emmanuel; Pan, Jin-Fen; Poirier, Laurence; Amiard-Triquet, Claude; Amiard, Jean-Claude; Gaudin, Pierre; Risso-de Faverney, Christine; Guibbolini, Marielle; Gilliland, Douglas; Valsami-Jones, Eugenia; Mouneyrac, Catherine

    2013-03-01

    Because of their bactericidal effects, Ag nanoparticles (Ag NPs) have promising industrial development but could lead to potential ecological risks. The aim of this study was to examine the uptake and effect of silver (soluble or as lactate Ag NPs of 40 nm) at low concentrations (10 μg L(-1)) in the endobenthic bivalve Scrobicularia plana exposed, for 14 days, directly (water) or via the diet (microalgae). The stability of Ag NPs in seawater was examined using dynamic light scattering. Release of soluble Ag from Ag NPs in the experimental media was quantified by using diffusive gradient in thin film. Bioaccumulation of Ag in bivalves was measured by electrothermal atomic absorption spectrometry. Behavioural and biochemical biomarkers were determined in bivalves. Aggregation of Ag NPs and the release of soluble Ag from Ag NPs were observed in the experimental media. For both forms of Ag, bioaccumulation was much more important for waterborne than for dietary exposure. The response of oxidative stress biomarkers (catalase, glutathion S-transferase, superoxide dismutase) was more important after dietary than waterborne exposure to Ag (soluble and NPs). These defences were relatively efficient since they led to a lack of response of damage biomarkers. Burrowing was not affected for bivalves exposed directly or through the diet to both Ag forms but feeding behaviour was impaired after 10 days of dietary exposure. Since no differences of responses to Ag either soluble or nanoparticulate were observed, it seems that labile Ag released from Ag NPs was mainly responsible for toxicity. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. Assessment of Heavy Metals in Bivalves Molluscs of Apulian Region: a 3-years control activity of a EU Laboratory

    Directory of Open Access Journals (Sweden)

    Miedico O.

    2013-04-01

    Full Text Available The bivalve molluscs represent an important matrix to be studied for several reasons. Their nutritional properties make them valuable to the consumers, so that their consumption and commercial value has risen worldwide. Simultaneously, their significant water-filtering capability and their persistence in the same place make them good bio-indicators of marine ecosystems. The presence of the heavy metal contaminants, as Cd, Pb and Hg, was investigated in bivalve molluscs such as mussels (Mytilus galloprovincialis, clams (Venus gallina and oysters (Ostrea edulis. In the present study, a survey was carried out on 334 samples addressed to the Istituto Zooprofilattico Sperimentale – Puglia e Basilicata, Foggia (ITALY between 2009-2011, and collected by official authorities along the coasts of Apulia Region. The conformity of heavy metal content in bivalve molluscs was verified, in according to EC Reg. 1881/2006. The compliance was found for the total amount of samples. The obtained data on heavy metals concentration in bivalve molluscs were compared with data found in monitoring studies on the incidence of heavy metals in 1981 in North-Western Mediterranean Sea, in 2003 in Tyrrhenian Sea and in 2010 in Pacific Ocean (Chile, reported in literature. The information obtained from this work offer an essential database, not only for the authorities involved in food control, but also for the official institutions responsible of a constant control of the marine ecosystem pollution.

  2. 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.

  3. [Nutrition and biological value of food parts of a trade bivalve mollusk Anadara broughtoni].

    Science.gov (United States)

    Tabakaeva, O V; Tabakaev, A V

    2015-01-01

    Currently, the human diet includes different new products of seafishing, including non-fish--bivalves and gastropods, holothurias, echinoderms, jellyfishes that demands careful studying of their chemical composition. The purpose of the study was to determine the nutritional and biological value of all soft parts of the burrowing bivalve MOLLUSK Anadara broughtoni from the Far East region. It was established thatfood parts of a bivalve were significantly flooded (water content--73.5-84.2%), with the minimum water content in the adductor and maximum in the mantle. Dry solids are presented by organic (89-93%) and mineral (7-11%) components. Organic components consist of protein (14.6-20.7%), lipids (1.8-2.3%), carbohydrates (2.1-2.6%). The analysis of amino-acid composition of proteins of food parts of the mollusk of Anadara broughtonishowed the presence of all essential amino acids with slight differences in their content depending on the localization of the protein. All edible parts have tryptophan as the limiting amino acid. Muscle proteins have maximum level of lysine, methionine, cysteine, phenylalanine and tyrosine; mantle proteins--leucine, isoleucine and threonine; adductor proteins--valine, phenylalanine, tyrosine, methionine and cysteine. Predominant nonessential amino acids forproteins of all food pieces are glycine, aspartic acid, glutamic acid, arginine. The coefficient of amino-acid score differences of adductor protein (31.7%) is less than the same of cloak by 3.7%. The indicator "biological value" is maximal for adductor (68.3%), but the differenceformuscle is only 0.83%. Mantle proteins are characterized by minimum biological value (64.6%). The coefficient of utility of amino acid composition of protein is maximalfor muscle (57.83%), and values for a cloak and an adductor differ slightly (55.81 and 55.96%). Taurine content in food parts of a mollusk Anadara broughtoni is rather high compared to with other bivalve mollusks of the Far East region

  4. Evaluation of the threat of marine CO2 leakage-associated acidification on the toxicity of sediment metals to juvenile bivalves

    International Nuclear Information System (INIS)

    Basallote, M. Dolores; Rodríguez-Romero, Araceli; De Orte, Manoela R.; Del Valls, T. Ángel; Riba, Inmaculada

    2015-01-01

    Highlights: • Short-term tests using juveniles of bivalves to study the effects of CO 2 dissolved. • CO 2 causes effects if the threshold concentration of the organism is overlapped. • Flows of escaped CO 2 would affect the geochemical composition of sediment–seawater. • CO 2 -induced acidification would affect differently to marine sediment toxicity. - Abstract: The effects of the acidification associated with CO 2 leakage from sub-seabed geological storage was studied by the evaluation of the short-term effects of CO 2 -induced acidification on juveniles of the bivalve Ruditapes philippinarum. Laboratory scale experiments were performed using a CO 2 -bubbling system designed to conduct ecotoxicological assays. The organisms were exposed for 10 days to elutriates of sediments collected in different littoral areas that were subjected to various pH treatments (pH 7.1, 6.6, 6.1). The acute pH-associated effects on the bivalves were observed, and the dissolved metals in the elutriates were measured. The median toxic effect pH was calculated, which ranged from 6.33 to 6.45. The amount of dissolved Zn in the sediment elutriates increased in parallel with the pH reductions and was correlated with the proton concentrations. The pH, the pCO 2 and the dissolved metal concentrations (Zn and Fe) were linked with the mortality of the exposed bivalves

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

    Science.gov (United States)

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

    2016-01-21

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

  6. Burrowing Behavior of a Deposit Feeding Bivalve Predicts Change in Intertidal Ecosystem State

    NARCIS (Netherlands)

    Compton, T.J.; Bodnar, W.; Koolhaas, A.; Dekinga, A.; Holthuijsen, S.; Ten Horn, J.; McSweeney, N.; van Gils, J.A.; Piersma, T.

    2016-01-01

    Behavior has a predictive power that is often underutilized as a tool for signaling ecological change. The burrowing behavior of the deposit feeding bivalve Macoma balthica reflects a typical food-safety trade-off. The choice to live close to the sediment surface comes at a risk of predation and is

  7. Burrowing behavior of a deposit feeding bivalve predicts change in intertidal ecosystem state

    NARCIS (Netherlands)

    Compton, Tanya J.; Bodnar, Wanda; Koolhaas, Anita; Dekinga, Anne; Holthuijsen, Sander; ten Horn, Job; McSweeney, Niamh; van Gils, Jan; Piersma, Theunis

    2016-01-01

    Behavior has a predictive power that is often underutilized as a tool for signaling ecological change. The burrowing behavior of the deposit feeding bivalve Macoma balthica reflects a typical food-safety trade-off. The choice to live close to the sediment surface comes at a risk of predation and is

  8. Chemosymbiotic bivalves from the mud volcanoes of the Gulf of Cadiz, NE Atlantic, with descriptions of new species of Solemyidae, Lucinidae and Vesicomyidae.

    Science.gov (United States)

    Olive, Graham; Rodrigues, Clara F; Cunha, Marina R

    2011-01-01

    The chemosymbiotic bivalves collected from the mud volcanoes of the Gulf of Cadiz are reviewed. Of the thirteen species closely associated with chemosynthetic settings two Solemyidae, Solemya (Petrasma) elarraichensissp. n. and Acharax gadiraesp. n., one Lucinidae, Lucinoma asapheussp. n., and one Vesicomyidae, Isorropodon megadesmussp. n. are described and compared to close relatives of their respective families. The biodiversity and distribution of the chemosymbiotic bivalves in the Gulf of Cadiz are discussed and compared to the available information from other cold seeps in the Eastern Atlantic and Mediterranean. Although there is considerable similarity at the genus level between seep/mud volcano fields in the Eastern Atlantic and Mediterranean, there is little overlap at the species level. This indicates a high degree of endemism within chemosymbiotic bivalve assemblages.

  9. Impact of seawater carbonate chemistry on the calcification of marine bivalves

    OpenAIRE

    Thomsen Jörn; Haynert Kristin; Wegner K Mathias; Melzner Frank

    2015-01-01

    Bivalve calcification, particular of the early larval stages is highly sensitive to the change of ocean carbonate chemistry resulting from atmospheric CO2 uptake. Earlier studies suggested that declining seawater [CO32−] and thereby lowered carbonate saturation affect shell production. However, disturbances of physiological processes such as acid-base regulation by adverse seawater pCO2 and pH can affect calcification in a secondary fashion. In order to determine the e...

  10. The use of geochemical speciation modelling to predict the impact of uranium to freshwater biota

    International Nuclear Information System (INIS)

    Markich, S.J.; Brown, P.L.; Jeffree, R.A.

    1996-01-01

    Uranium is the prime potential contaminant in mine waste waters that may be released from the Ranger Uranium Mine (RUM) into the receiving waters of the Magela Creek, Alligator Rivers Region, Northern Australia. The potential ecological impact of the migration of uranium, that would result from an elevation in its concentration above background, in the Magela Creek downstream of the RUM, has been experimentally investigated by integrating biomonitoring with geochemical speciation modelling. The freshwater bivalve Velesunio angasi, abundant throughout the Magela Creek catchment, was exposed to a variety of uranium concentrations in a synthetic Magela Creek water, at four pH levels (5.0, 5.3, 5.5 and 6.0), in the presence (3.05 and 7.50 mg l -1 ) and absence of a model fulvic acid (FA), and its behavioural response was measured. Speciation modelling, using the HARPHRQ code, provided evidence that UO 2+ 2 and UO 2 OH + are the uranium species most responsible (ca. 96%) for eliciting an adverse behavioural response when UO 2+ 2 is assigned twice the toxic effect of UO 2 OH + . This finding rejects the notion that biota respond specifically to the sum total of inorganic uranyl species. (orig.)

  11. Reproductive investment in the intertidal bivalve Macoma balthica

    Science.gov (United States)

    Honkoop, P. J. C.; Van der Meer, J.; Beukema, J. J.; Kwast, D.

    1999-05-01

    Bivalve eggs generally contain large amounts of lipids which, in comparison with proteins and carbohydrates, have high energy contents and are thus costly in energetic terms. As lipid contents vary between species, comparisons of reproductive investments should not only include numbers and sizes of eggs, but also their energy content. We estimated the investment in egg material of mature females of the Baltic tellin Macoma balthica (L.) in terms of both mass and energy content. All mass below a minimum body mass (below which no eggs are produced) was defined as structural mass. This threshold amounts to a body mass index (BMI) of 5.6 (ash-free dry mass per cubic shell length in mg cm -3). More than half (55%) of the mass above the structural mass was invested in egg material and 45% in extra somatic tissue and tissue for production and storage of gametes. This means that the amount of eggs spawned ranged from 0 (at BMI = 5.6 mg cm -3) to 33% of the total ash-free dry mass (at a high BMI value of 14 mg cm -3). Eggs contained a relatively large amount of lipids, about 30% of their ash-free dry mass, whereas non-egg material contained only about 7% lipids. Eggs of two other bivalves in the Wadden Sea, the cockle Cerastoderma edule and the mussel Mytilus edulis, were smaller and contained only about 11% and 20% lipids, respectively. Energy content of M. balthica eggs amounted to ˜0.006 J, in the other two species to ˜0.002 J. The function of the more expensive eggs in M. balthica may be related to its early spawning in spring, causing slower larval development until first feeding.

  12. Predation on intertidal mussels: Influence of biotic factors on the survival of epibenthic bivalve beds

    NARCIS (Netherlands)

    Waser, A.M.

    2018-01-01

    Coastal areas are amongst the most productive ecosystems in the world. Important components of these coastal areas are reef-forming bivalves such as mussels and oysters, as they have important facilitating effects on many associated organisms through the provision of substratum,

  13. Sodium provides unique insights into transgenerational effects of ocean acidification on bivalve shell formation.

    Science.gov (United States)

    Zhao, Liqiang; Schöne, Bernd R; Mertz-Kraus, Regina; Yang, Feng

    2017-01-15

    Ocean acidification is likely to have profound impacts on marine bivalves, especially on their early life stages. Therefore, it is imperative to know whether and to what extent bivalves will be able to acclimate or adapt to an acidifying ocean over multiple generations. Here, we show that reduced seawater pH projected for the end of this century (i.e., pH7.7) led to a significant decrease of shell production of newly settled juvenile Manila clams, Ruditapes philippinarum. However, juveniles from parents exposed to low pH grew significantly faster than those from parents grown at ambient pH, exhibiting a rapid transgenerational acclimation to an acidic environment. The sodium composition of the shells may shed new light on the mechanisms responsible for beneficial transgenerational acclimation. Irrespective of parental exposure, the amount of Na incorporated into shells increased with decreasing pH, implying active removal of excessive protons through the Na + /H + exchanger which is known to depend on the Na + gradient actively built up by the Na + /K + -ATPase as a driving force. However, the shells with a prior history of transgenerational exposure to low pH recorded significantly lower amounts of Na than those with no history of acidic exposure. It therefore seems very likely that the clams may implement less costly and more ATP-efficient ion regulatory mechanisms to maintain pH homeostasis in the calcifying fluid following transgenerational acclimation. Our results suggest that marine bivalves may have a greater capacity to acclimate or adapt to ocean acidification by the end of this century than currently understood. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2011-12-01

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

  15. An ecosystem-based approach and management framework for the integrated evaluation of bivalve aquaculture impacts

    NARCIS (Netherlands)

    Cranford, P.J.; Kamermans, P.; Krause, G.H.M.; Mazurie, J.

    2012-01-01

    An ecosystem-based approach to bivalve aquaculture management is a strategy for the integration of aquaculture within the wider ecosystem, including human aspects, in such a way that it promotes sustainable development, equity, and resilience of ecosystems. Given the linkage between social and

  16. The complete maternally and paternally inherited mitochondrial genomes of the endangered freshwater mussel Solenaia carinatus (Bivalvia: Unionidae and implications for Unionidae taxonomy.

    Directory of Open Access Journals (Sweden)

    Xiao-Chen Huang

    Full Text Available Doubly uniparental inheritance (DUI is an exception to the typical maternal inheritance of mitochondrial (mt DNA in Metazoa, and found only in some bivalves. In species with DUI, there are two highly divergent gender-associated mt genomes: maternal (F and paternal (M, which transmit independently and show different tissue localization. Solenaia carinatus is an endangered freshwater mussel species exclusive to Poyang Lake basin, China. Anthropogenic events in the watershed greatly threaten the survival of this species. Nevertheless, the taxonomy of S. carinatus based on shell morphology is confusing, and the subfamilial placement of the genus Solenaia remains unclear. In order to clarify the taxonomic status and discuss the phylogenetic implications of family Unionidae, the entire F and M mt genomes of S. carinatus were sequenced and compared with the mt genomes of diverse freshwater mussel species. The complete F and M mt genomes of S. carinatus are 16716 bp and 17102 bp in size, respectively. The F and M mt genomes of S. carinatus diverge by about 40% in nucleotide sequence and 48% in amino acid sequence. Compared to F counterparts, the M genome shows a more compact structure. Different gene arrangements are found in these two gender-associated mt genomes. Among these, the F genome cox2-rrnS gene order is considered to be a genome-level synapomorphy for female lineage of the subfamily Gonideinae. From maternal and paternal mtDNA perspectives, the phylogenetic analyses of Unionoida indicate that S. carinatus belongs to Gonideinae. The F and M clades in freshwater mussels are reciprocal monophyly. The phylogenetic trees advocate the classification of sampled Unionidae species into four subfamilies: Gonideinae, Ambleminae, Anodontinae, and Unioninae, which is supported by the morphological characteristics of glochidia.

  17. Exposure dose response relationships of the freshwater bivalve Hyridella australis to cadmium spiked sediments

    International Nuclear Information System (INIS)

    Marasinghe Wadige, Chamani P.M.; Maher, William A.; Taylor, Anne M.; Krikowa, Frank

    2014-01-01

    Highlights: • The exposure–dose–response approach was used to assess cadmium exposure and toxicity. • Accumulated cadmium in H. australis reflected the sediment cadmium exposure. • Spill over of cadmium into the biologically active pool was observed. • Increased cadmium resulted in measurable biological effects. • H. australis has the potential to be a cadmium biomonitor in freshwater environments. - Abstract: To understand how benthic biota may respond to the additive or antagonistic effects of metal mixtures in the environment it is first necessary to examine their responses to the individual metals. In this context, laboratory controlled single metal-spiked sediment toxicity tests are useful to assess this. The exposure–dose–response relationships of Hyridella australis to cadmium-spiked sediments were, therefore, investigated in laboratory microcosms. H. australis was exposed to individual cadmium spiked sediments (<0.05 (control), 4 ± 0.3 (low) and 15 ± 1 (high) μg/g dry mass) for 28 days. Dose was measured as cadmium accumulation in whole soft body and individual tissues at weekly intervals over the exposure period. Dose was further examined as sub-cellular localisation of cadmium in hepatopancreas tissues. The biological responses in terms of enzymatic and cellular biomarkers were measured in hepatopancreas tissues at day 28. H. australis accumulated cadmium from spiked sediments with an 8-fold (low exposure organisms) and 16-fold (high exposure organisms) increase at day 28 compared to control organisms. The accumulated tissue cadmium concentrations reflected the sediment cadmium exposure at day 28. Cadmium accumulation in high exposure organisms was inversely related to the tissue calcium concentrations. Gills of H. australis showed significantly higher cadmium accumulation than the other tissues. Accumulated cadmium in biologically active and biologically detoxified metal pools was not significantly different in cadmium exposed

  18. Uranium bioaccumulation in a freshwater ecosystem: Impact of feeding ecology

    Energy Technology Data Exchange (ETDEWEB)

    Kraemer, Lisa D., E-mail: lisakraemer@trentu.ca [Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 7B8 (Canada); Evans, Douglas [Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 7B8 (Canada)

    2012-11-15

    Uranium bioaccumulation in a lake that had been historically affected by a U mine and (2) to use a combined approach of gut content examination and stable nitrogen and carbon isotope analysis to determine if U bioaccumulation in fish was linked to foodweb ecology. We collected three species of fish: smallmouth bass (Micropterus dolomieu), yellow perch (Perca flavescens) and bluegill (Lepomis macrochirus), in addition to several invertebrate species including freshwater bivalves (family: Sphaeriidae), dragonfly nymphs (order: Odonata), snails (class: Gastropoda) and zooplankton (family: Daphniidae). Results showed significant U bioaccumulation in the lake impacted by historical mining activities. Uranium accumulation was 2-3 orders of magnitude higher in invertebrates than in the fish species. Within fish, U was measured in operculum (bone), liver and muscle tissue and accumulation followed the order: operculum > liver > muscle. There was a negative relationship between stable nitrogen ratios ({sup 15}N/{sup 14}N) and U bioaccumulation, suggesting U biodilution in the foodweb. Uranium bioaccumulation in all three tissues (bone, liver, muscle) varied among fish species in a consistent manner and followed the order: bluegill > yellow perch > smallmouth bass. Collectively, gut content and stable isotope analysis suggests that invertebrate-consuming fish species (i.e. bluegill) have the highest U levels, while fish species that were mainly piscivores (i.e. smallmouth bass) have the lowest U levels. Our study highlights the importance of understanding the feeding ecology of fish when trying to predict U accumulation.

  19. Evaluation of the threat of marine CO{sub 2} leakage-associated acidification on the toxicity of sediment metals to juvenile bivalves

    Energy Technology Data Exchange (ETDEWEB)

    Basallote, M. Dolores, E-mail: dolores.basallote@uca.es [Cátedra UNESCO/UNITWIN WiCop, Departamento de Química-Física, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Polígono Río San Pedro s/n, 11510 Puerto Real, Cádiz (Spain); Rodríguez-Romero, Araceli [Departamento de Ecología y Gestión Costera, Instituto de Ciencias Marinas de Andalucía (CSIC), Campus Río San Pedro, 11510 Puerto Real, Cádiz (Spain); De Orte, Manoela R.; Del Valls, T. Ángel; Riba, Inmaculada [Cátedra UNESCO/UNITWIN WiCop, Departamento de Química-Física, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, Polígono Río San Pedro s/n, 11510 Puerto Real, Cádiz (Spain)

    2015-09-15

    Highlights: • Short-term tests using juveniles of bivalves to study the effects of CO{sub 2} dissolved. • CO{sub 2} causes effects if the threshold concentration of the organism is overlapped. • Flows of escaped CO{sub 2} would affect the geochemical composition of sediment–seawater. • CO{sub 2}-induced acidification would affect differently to marine sediment toxicity. - Abstract: The effects of the acidification associated with CO{sub 2} leakage from sub-seabed geological storage was studied by the evaluation of the short-term effects of CO{sub 2}-induced acidification on juveniles of the bivalve Ruditapes philippinarum. Laboratory scale experiments were performed using a CO{sub 2}-bubbling system designed to conduct ecotoxicological assays. The organisms were exposed for 10 days to elutriates of sediments collected in different littoral areas that were subjected to various pH treatments (pH 7.1, 6.6, 6.1). The acute pH-associated effects on the bivalves were observed, and the dissolved metals in the elutriates were measured. The median toxic effect pH was calculated, which ranged from 6.33 to 6.45. The amount of dissolved Zn in the sediment elutriates increased in parallel with the pH reductions and was correlated with the proton concentrations. The pH, the pCO{sub 2} and the dissolved metal concentrations (Zn and Fe) were linked with the mortality of the exposed bivalves.

  20. Element availability of bivalve with symbiotic zooxanthellae in coral sea area as studied by multielement profiling analysis

    Science.gov (United States)

    Itoh, A.; Kabe, N.

    2008-12-01

    In coral sea, a characteristic ecosystem is formed by many kinds of marine animals and plants, although seawater is uneutrophic. This may be explained by the fact that various chemical species with bioessentiality are effectively taken and used by lower animals and plants in coral sea area. A symbiotic relationship often found among different animals and plants in this area is considered to be working as one of such processes. However, the specific bioavailability of the elements for the marine animals and plants in coral reef area has not been studied from the viewpoints of trace and ultratrace elements. It is found by the present authors that bivalve with symbiotic zooxanthellae (Tridacna crocea) living on coral reef had relatively higher bio- accumulation factors for many bio-essential elements than other kinds of bivalves, although they live in the uneutrophic sea area. The present authors focused on Tridacna crocea as one of the symbiotic animals. Thus, in the present study, at first, multielement determination of major-to-ultratrace elements (about 20 elements) in each organ of Tridacna crocea with symbiotic zooxanthellae, were carried out by ICP-AES, ICP- MS, and CHN coder. At Second, the specific bioavailability of trace and ultratrace elements in Tridacna crocea was discussed on the multielement data for seawater, seaweeds, and other bivalves in coral sea area.

  1. 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…

  2. THE FRESHWATER CRAYFISH AUSTROPOTAMOBIUS PALLIPESIN SOUTH TYROL: HERITAGE SPECIES AND BIOINDICATOR

    Directory of Open Access Journals (Sweden)

    FÜREDER L.

    2003-04-01

    Full Text Available Rapid decline of crayfish in European freshwaters and continuing threat necessitate integrated actions in conservation and management of native crayfish populations. Besides biological reasons (diseases, plague, the impact of toxic and harmful substances (fertilisers, herbicides or wastewater effluents, habitat alteration or fragmentation have been responsible for their decline in some regions. The same is true for the region of South Tyrol, where compared to previous investigations, only 10 of a former total of 15 crayfish locations in the water bodies could be affirmed. Although two new populations of the non-indigenous Astacus astacus were detected, the native Austropotamobius pallipes continues to decline. While many investigations have focused accurately on causal coherences for the decline of native populations, the properties of crayfish facilitate to reverse the situation. In a few examples, the potential of Austropotamobius pallipes, the native crayfish in South Tyrol, as “surrogate species” for effective biological conservation is discussed. Given the various adequate attributes of freshwater crayfish as surrogate species (including indicator species, umbrella species and flagship species qualities, they may help to advance not only the crayfish situation itself but also freshwater ecosystem properties in general.

  3. Abundance, biomass and caloric content of Chukchi Sea bivalves and association with Pacific walrus (Odobenus rosmarus divergens) relative density and distribution in the northeastern Chukchi Sea

    Science.gov (United States)

    Young, Jordann K.; Black, Bryan A.; Clarke, Janet T.; Schonberg, Susan V.; Dunton, Kenneth H.

    2017-10-01

    The northeastern Chukchi Sea is a shallow subarctic shelf ecosystem that supports a substantial benthic infaunal community of which bivalves are a major component. We assessed the patterns in population abundance, biomass, and caloric content of ten dominant bivalve taxa in relation to the distribution of the upper trophic level consumer Pacific walrus (Odobenus rosmarus divergens). Bivalves were collected over four cruises in the northeastern Chukchi Sea (2009, 2010, 2012, 2013). Our samples were largely dominated by calorie-dense, deposit-feeding species, including Macoma spp., Ennucula tenuis, Nuculana spp. and Yoldia spp. Weight-frequency distributions were strongly right-skewed for most taxa, though some showed evidence of a bimodal distribution. Caloric densities as measured through bomb calorimetry significantly differed among taxa (ANOVA F = 32.57, df = 9, p-valueanimal wet weight was found to be a reliable predictor of whole animal caloric content. Bivalve populations and peak caloric densities were centered on and to the southeast of Hanna Shoal, which coincided with peak Pacific walrus relative density (walruses per km surveyed) from July through October. Significant differences in mean caloric values were found between areas with and without walruses present (student's t-test, t=-2.9088, df = 252.24, p-value = 0.003952), as well as between areas with low and high walrus relative densities in the pooled annual dataset and in each individual month except October (ANOVA, p-value<0.05). The high-calorie deposit feeders that dominate these bivalve communities preferentially consume food sources, such as sea ice algae, that are likely to be affected by shifting sea ice dynamics. As such, continued warming has the potential to alter bivalve communities in the northeastern Chukchi Sea, which may have profound implications for upper trophic levels.

  4. Laboratory and field assessment of uranium trophic transfer efficiency in the crayfish Orconectes limosus fed the bivalve C. fluminea

    International Nuclear Information System (INIS)

    Simon, Olivier; Garnier-Laplace, Jacqueline

    2005-01-01

    At present, ecotoxicological information regarding the impact of natural uranium (U) on freshwater ecosystems via the trophic contamination route is scarce. We generated an experimental trophic food chain involving the prey species, Corbicula fluminea, and a predator, Orconectes limosus, for a 10-day and a 30-day feeding periods (food ration: one whole soft body/day/crayfish). We studied the efficiency of U trophic transfer and the distribution of U in the predator. During the test, we varied the quantity of dietary U (from beforehand contaminated bivalves at concentrations ranging from 0.9 ± 0.1 to 20.2 ± 9 μg/g fw provided to each crayfish over the 10 days) applying a daily feeding rate equal to 3.9 ± 0.8% fw. The efficiency of U trophic transfer from clams to crayfish varied between 1 and 13% depending on the prey exposure modalities. Accumulation of U was observed in the digestive gland but also in gills, in the muscle, and in the molt of the crayfish after trophic exposure treatments. Under high-level exposure conditions, the digestive gland was the main target-organ, however a significant accumulation was also observed in the stomach. With regard to low levels of trophic exposure, accumulation of U in gills, in the stomach, and in the digestive gland was of the same order of magnitude. Longer exposure period which incorporated a crayfish molt, resulted in a decrease of trophic transfer ratio and a modified U tissue distribution

  5. Contamination of raw bivalve molluscs available in Poland between 2009 and 2013 with marine biotoxins

    Directory of Open Access Journals (Sweden)

    Michalski Mirosław

    2016-12-01

    Full Text Available Introduction: Growing consumption of shellfish is associated with an increased risk of food poisoning. The study was carried out on live bivalve molluscs available on the Polish market between 2009 and 2013. Material and Methods: ELISA was used for the determination of the following marine biotoxins: paralytic shellfish poison (PSP, amnaesic shellfish poison (ASP, and diarrhoeic shellfish poison (DSP. The molluscs, of which seven species were examined, were obtained from wholesale companies and markets. Results: Marine biotoxins were detected below the permitted levels in 67.6% of the samples. The maximum amounts of PSP and ASP biotoxins were found in great scallops (532.6 μg/kg and 1.0 mg/kg respectively and the peak for DSP was in blue mussels (107 μg/kg. Conclusion: The analysis of toxicological status of raw bivalve molluscs available on the market in Poland indicates that they are safe for consumers.

  6. Cadmium-handling strategies in two chronically exposed indigenous freshwater organisms-the yellow perch (Perca flavescens) and the floater mollusc (Pyganodon grandis)

    International Nuclear Information System (INIS)

    Campbell, Peter G.C.; Giguere, Anik; Bonneris, Emmanuelle; Hare, Landis

    2005-01-01

    Laboratory experiments on a variety of aquatic organisms suggest that metallothionein-like proteins (MT) play an important role in the regulation of essential metals, and in the sequestration and detoxification of non-essential metals (e.g., Cd). However, the importance of metallothionein production relative to alternative strategies of metal detoxification, and its effectiveness in metal detoxification, remain largely unexplored in field situations. In the present study we explored metal-handling strategies in an adult benthic bivalve (Pyganodon grandis) and in juvenile yellow perch (Perca flavescens), exposed to Cd in their natural habitat. The two biomonitor species were collected from lakes located along a Cd concentration gradient. Ambient dissolved Cd concentrations were determined by in situ dialysis as a measure of metal exposure. Sub-cellular Cd partitioning was determined in target tissues (bivalve gills and digestive gland; perch liver) by differential centrifugation, and metallothionein was measured independently by a mercury-saturation assay in the bivalve tissues. Malondialdehyde concentrations were measured as a potential indicator of oxidative stress. Ambient dissolved Cd concentrations ranged from 0.06 to 0.57 nM in the nine lakes from which bivalves were collected, and from max /[Cd] min ratios for the various tissues decreased in the order: bivalve gill Cd (28) > bivalve digestive gland Cd (18) > perch hepatic Cd (14). In the two lakes that were common to both the bivalve and perch studies, i.e. lakes Opasatica and Vaudray, accumulated Cd concentrations were consistently higher in the bivalve than in the perch. Cadmium-handling strategies were similar in the bivalve digestive gland and perch liver, in that Cd was mainly associated with the heat-stable protein (HSP) fraction. Furthermore, in these organs the contributions from the 'mitochondria' and 'lysosomes + microsomes' fractions were consistently higher than in the gill tissue. In the bivalve

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

    Science.gov (United States)

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

    2013-01-01

    various global positioning system and satellite tagging approaches to freshwater. Electronic tagging provides a mechanism to collect detailed information from imperilled animals and species that have no direct economic value. Current and future advances will continue to improve our knowledge of the natural history of aquatic animals and ecological processes in freshwater ecosystems while facilitating evidence-based resource management and conservation.

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

    Science.gov (United States)

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

    2017-08-01

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

  9. Heading south: new records of the invasive quagga mussel Dreissena rostriformis bugensis (Andrusov, 1897 in France and further perspectives

    Directory of Open Access Journals (Sweden)

    Prié Vincent

    2017-01-01

    Full Text Available Intensive malacological surveys coupled with environmental DNA analyses in France has led to the discovery of new populations of the quagga mussel Dreissena rostriformis bugensis (Andrusov, 1897, an introduced and invasive freshwater bivalve species. Molecular analyses confirmed the identification of the species based on a barcoding approach using both CO1 and 16S genes fragments. Discovered in 2011 in the rivers of north-east France, the quagga Mussel has now colonized the Rhône drainage. This advance represents not only the colonization of a new coastal drainage (the Rhône Rivers flows to the Mediterranean side of France, but also a spectacular 400-km leap south of its previously known range. Further expansion routes provided by canals between main coastal drainages are discussed. For the first time, we propose to use environmental DNA to assess absence, thus paving the way for future freshwater invasive species monitoring methods.

  10. Haplosporidium raabei n. sp. (Haplosporidia): a parasite of zebra mussels, Dreissena polymorpha (Pallas, 1771).

    Science.gov (United States)

    Molloy, D P; Giambérini, L; Stokes, N A; Burreson, E M; Ovcharenko, M A

    2012-04-01

    Extensive connective tissue lysis is a common outcome of haplosporidian infection. Although such infections in marine invertebrates are well documented, they are relatively rarely observed in freshwater invertebrates. Herein, we report a field study using a comprehensive series of methodologies (histology, dissection, electron microscopy, gene sequence analysis, and molecular phylogenetics) to investigate the morphology, taxonomy, systematics, geographical distribution, pathogenicity, and seasonal and annual prevalence of a haplosporidian observed in zebra mussels, Dreissena polymorpha. Based on its genetic sequence, morphology, and host, we describe Haplosporidium raabei n. sp. from D. polymorpha - the first haplosporidian species from a freshwater bivalve. Haplosporidium raabei is rare as we observed it in histological sections in only 0·7% of the zebra mussels collected from 43 water bodies across 11 European countries and in none that were collected from 10 water bodies in the United States. In contrast to its low prevalences, disease intensities were quite high with 79·5% of infections advanced to sporogenesis.

  11. Plio-Pleistocene extinctions and immigration credit reflected in the size-frequency distribution of Mediterranean marine bivalves

    Science.gov (United States)

    Nawrot, Rafal; Zuschin, Martin; Chattopadhyay, Devapriya

    2015-04-01

    Following the opening of the Suez Canal hundreds of Red Sea species have entered the Mediterranean Sea making it a global hot spot of marine bioinvasion. With the ongoing influx of the subtropical and tropical alien species and increasing sea surface temperatures, the Mediterranean biota is currently gaining a more tropical character and increasingly becoming a mixture of faunal stocks with different evolutionary histories. This susceptibility to invasion was suggested to reflect the presence of an empty ecological space left after decimation of incumbent warm-water fauna during Plio-Pleistocene climate fluctuations. As molluscs are among the most prolific immigrants, we test this hypothesis using data on taxonomic composition and body size of Pliocene Mediterranean bivalves derived from the literature sources and museum collections. The Pliocene inter-specific size-frequency distribution (SFD) is strikingly similar to the SFDs of the Recent Red Sea bivalve fauna, in spite of different biogeographic provenance and the absence of true reef ecosystems in the Pliocene of the Mediterranean region. In contrast, body-size patterns in both assemblages are significantly different from the present-day Mediterranean fauna characterized by smaller median and modal size. Our preliminary results suggest that the distinct shape of the modern Mediterranean SFD may reflect the selective nature of the late Piacenzian - Galesian (Late Pliocene - Early Pleistocene) extinctions pulses related to the onset of the Northern Hemisphere glaciations. These extinctions affected almost 40% of Pliocene species and were biased towards large-bodied taxa. They were not followed by re-immigration of warm-water species owing to the isolation from the tropical Atlantic biota by the cold upwelling along the NW coasts of Africa. The resulting invasion credit (sensu Jackson & Sax, 2010) is currently being paid by the Red Sea bivalves colonizing the Mediterranean Sea through the Suez Canal. Successful

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

    CSIR Research Space (South Africa)

    Rivers-Moore, NA

    2011-01-01

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

  13. Uniform Variation in Genetic-Traits of a Marine Bivalve Related to Starvation, Pollution and Geographic Clines

    NARCIS (Netherlands)

    Hummel, H.; Bogaards, R.H.; Amiard-Triquet, C.; Bachelet, G.; Desprez, M.; Marchand, J.; Rybarczyk, H.; Sylvand, B.; De Wit, Y.; De Wolf, L.

    1995-01-01

    Consistent patterns of genetic variation in the marine bivalve Macoma balthica (L.) were found after exposure to low levels of copper, starvation, and along geographic dines. The geographic dines were related to temperature and salinity. Genetic differences were primarily found in the LAP (Leucine

  14. Mobile Element Evolution Playing Jigsaw - SINEs in Gastropod and Bivalve Mollusks.

    Science.gov (United States)

    Matetovici, Irina; Sajgo, Szilard; Ianc, Bianca; Ochis, Cornelia; Bulzu, Paul; Popescu, Octavian; Damert, Annette

    2016-01-06

    SINEs (Short INterspersed Elements) are widely distributed among eukaryotes. Some SINE families are organized in superfamilies characterized by a shared central domain. These central domains are conserved across species, classes, and even phyla. Here we report the identification of two novel such superfamilies in the genomes of gastropod and bivalve mollusks. The central conserved domain of the first superfamily is present in SINEs in Caenogastropoda and Vetigastropoda as well as in all four subclasses of Bivalvia. We designated the domain MESC (Romanian for MElc-snail and SCoica-mussel) because it appears to be restricted to snails and mussels. The second superfamily is restricted to Caenogastropoda. Its central conserved domain-Snail-is related to the Nin-DC domain. Furthermore, we provide evidence that a 40-bp subdomain of the SINE V-domain is conserved in SINEs in mollusks and arthropods. It is predicted to form a stable stem-loop structure that is preserved in the context of the overall SINE RNA secondary structure in invertebrates. Our analysis also recovered short retrotransposons with a Long INterspersed Element (LINE)-derived 5' end. These share the body and/or the tail with transfer RNA (tRNA)-derived SINEs within and across species. Finally, we identified CORE SINEs in gastropods and bivalves-extending the distribution range of this superfamily. © The Author(s) 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  15. Biomonitoring of Heavy metals using the bivalve molluscs in sunderban mangrove wetland, Northeast Coast of Bay of bengal (india): possible risks to Human health

    Energy Technology Data Exchange (ETDEWEB)

    Cabral, Henrique; Cardoso, Ines [Departamento de Biologia Animal/Instituto de Oceanografia, Campo Grande, Lisboa (Portugal); Chatterjee, Mousumi; Kumar Bhattacharya, Asok; Aftab Alam, Mohammad [Department of Marine Science, University of Calcutta, Calcutta (India); Kanta Satpathy, Kamala [Indira Gandhi Centre for Atomic Research, Environmental and Industrial Safety Section, Safety Group, Kalpakkam, Tamil Nadu (India); Kumar Sarkar, Santosh

    2008-02-15

    The suitability of using four bivalve molluscs (Sanguinolaria acuminata, Anadara granosa, Meretrix meretrix, and Pelecyora trigona) in biomonitoring of heavy metals (Cu, Pb, Cd, Zn, and Hg) collected from intertidal regions of the Sunderban mangrove wetland, northeastern part of the Bay of Bengal, were evaluated. Both speciesdependent variability and temporal variations were pronounced. A high degree of organ specificity was evident in the bivalves where gill and mantle exhibited higher metal accumulation due to ion exchange property of the mucous layer covering these organs while shells represent very poor accumulation. Elevated values of Zn and Cu reflect high potential for biomagnification through marine food chain. Metal concentrations in different body size groups of the bivalves do not follow uniform trend. Correlation coefficient between different metal couplings as tested statistically revealed significant coupling for Pb-Zn, Pb-Cu, Zn-Cu, and Hg-Cu. Concentrations of all the metals in specific organs (visceral mass, mantle and gill) of the bivalves exceeded the safe levels according to the international standards for metals compiled by Food and Agricultural Organization of the United Nations and would be of great risk for human consumption. It is concluded that the mussel and clam are suitable biomonitors to employ in programs designed to assess changes in metal pollution in the Sunderban mangrove wetland. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  16. Microplastics in bivalves cultured for human consumption.

    Science.gov (United States)

    Van Cauwenberghe, Lisbeth; Janssen, Colin R

    2014-10-01

    Microplastics are present throughout the marine environment and ingestion of these plastic particles (microplastics in two species of commercially grown bivalves: Mytilus edulis and Crassostrea gigas. Microplastics were recovered from the soft tissues of both species. At time of human consumption, M. edulis contains on average 0.36 ± 0.07 particles g(-1) (wet weight), while a plastic load of 0.47 ± 0.16 particles g(-1) ww was detected in C. gigas. As a result, the annual dietary exposure for European shellfish consumers can amount to 11,000 microplastics per year. The presence of marine microplastics in seafood could pose a threat to food safety, however, due to the complexity of estimating microplastic toxicity, estimations of the potential risks for human health posed by microplastics in food stuffs is not (yet) possible. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Desalination - an alternative freshwater resource

    International Nuclear Information System (INIS)

    Shakaib, M.

    2005-01-01

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

  18. Boreholes on three bivalve species found on the sand beach at Sagot Cape, Baengnyeongdo, Korea

    Directory of Open Access Journals (Sweden)

    Dal-Yong Kong

    2017-12-01

    Full Text Available Circular to subcircular boreholes were found on the surfaces of three different bivalve shells (Mactra chinensis, Felaniella usta, and Nuttallia japonica that were pushed onto the sand beach at Sagot Cape, Baengnyeongdo, Korea. The boreholes are characterized by beveled holes that are parabolic in cross section. The boreholes are classified into the ichnospecies Oichnus paraboloides, probably drilled by a naticid gastropod Glossaulax didyma didyma living in the Baengnyeong tidal flat. In the case of Mactrashells, boreholes are observed more or less evenly on left and right valves, and 96% of boreholes are located on the umbo. This may suggest that the life position of the Baengnyeong bivalves did not dictate the preference of G. didyma didyma in the Baengnyeong tidal flat ecosystem. The clustered distribution of the boreholes in the umbo area indicates a strong site selectivity for boreholes that is quite a common phenomenon in many naticid gastropods. Keywords: Baengnyeongdo, Mactra chinensis, Naticid gastropods, Oichnus paraboloides, Prey–predator interactions

  19. Metals and organotins in multiple bivalve species in a one-off global survey

    DEFF Research Database (Denmark)

    Larsen, Martin Mørk; Strand, Jakob; Christensen, Jan H.

    2011-01-01

    contamination levels on a global scale. Metal concentrations in nine bivalve species were normalised to the Mytilidae family using conversion factors based on cosampled species and literature bioconcentration factors. The lowest metal and tributyltin concentrations were below background assessment...... were low, but not always lower than expected impacted areas. The most contaminated areas were harbours, where especially Copenhagen, St Croix and Sydney, can be considered hotspots of tributyltin as well as a number of metals....

  20. Some effects of temperature and starvation on the bivalve @iDonax vittatus@@ (da Costa) in experimental laboratory populations

    Digital Repository Service at National Institute of Oceanography (India)

    Ansell, A.D.; Sivadas, P.

    The effect of temperature on the body weight and composition, and on respiration, filtration and NH, excretion of the bivalve Donax uittatus (da Costa) has been investigated in laboratory-maintained populations under conditions of starvation In all...

  1. 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....

  2. Meeting ecological and societal needs for freshwater

    Science.gov (United States)

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

    2002-01-01

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

  3. The freshwater reservoir effect in radiocarbon dating

    DEFF Research Database (Denmark)

    Philippsen, Bente

    2013-01-01

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

  4. Uptake and metabolism of 14C-chloropyrifos by marine bivalves

    International Nuclear Information System (INIS)

    Zhong, C.G.; Chen, S.; Zhao, X.; Shi, J.; Carvalho, F.P.

    1999-01-01

    The uptake and metabolism of 14 C-chlorpyrifos by two marine bivalves, Paphia undulata and Sinonovacula constricta, were studied in a simulated ecosystem. The experiments were carried out in two 30 L glass tanks containing each 20 L of filtered sea water, contaminated with 14 C-chlorpyrifos 1.85x10 4 Bq.L -1 (16.7 μg.L -1 ) at the beginning of the exposure period. At different time intervals, three specimens of each species were sampled for analysis of the pesticide in the molluscs tissues. The 14 C-chlorpyrifos residues were extracted from the digestive gland of the molluscs and analyzed by co-chromatography with pesticide standards by TLC methods described before

  5. Trace element determination in soft tissues of marine bivalves by activation analysis

    International Nuclear Information System (INIS)

    Fukushima, M.; Tamate, H.; Nakano, Y.

    2003-01-01

    Trace elements in soft tissues of marine bivalves were determined by neutron activation analysis (NAA) and photon activation analysis (PAA). Elemental levels of Ag, As, Br, Co, Cu, Fe, I, Mn, Ni, Rb, Se, and Zn in the organs of giant ezoscallos, rock oysters, and giant crams were obtained. The metal-bound proteins were extracted from the mantles and hepatopancreases of rock oysters. By irradiating the fraction obtained by HPLC gel chromatography, the possibility for the existence of an Ag bound protein in the mantles was found. (author)

  6. Cephalic and limb anatomy of a new Isoxyid from the Burgess Shale and the role of "stem bivalved arthropods" in the disparity of the frontalmost appendage.

    Directory of Open Access Journals (Sweden)

    Cédric Aria

    Full Text Available We herein describe Surusicaris elegans gen. et sp. nov. (in Isoxyidae, amended, a middle (Series 3, Stage 5 Cambrian bivalved arthropod from the new Burgess Shale deposit of Marble Canyon (Kootenay National Park, British Columbia. Surusicaris exhibits 12 simple, partly undivided biramous trunk limbs with long tripartite caeca, which may illustrate a plesiomorphic "fused" condition of exopod and endopod. We construe also that the head is made of five somites (= four segments, including two eyes, one pair of anomalocaridid-like frontalmost appendages, and three pairs of poorly sclerotized uniramous limbs. This fossil may therefore be a candidate for illustrating the origin of the plesiomorphic head condition in euarthropods, and questions the significance of the "two-segmented head" in, e.g., fuxianhuiids. The frontalmost appendage in isoxyids is intriguingly disparate, bearing similarities with both dinocaridids and euarthropods. In order to evaluate the relative importance of bivalved arthropods, such as Surusicaris, in the hypothetical structuro-functional transition between the dinocaridid frontal appendage and the pre-oral-arguably deutocerebral-appendage of euarthropods, we chose a phenetic approach and computed morphospace occupancy for the frontalmost appendages of 36 stem and crown taxa. Results show different levels of evolutionary decoupling between frontalmost appendage disparity and body plans. Variance is greatest in dinocaridids and "stem bivalved" arthropods, but these groups do not occupy the morphospace homogeneously. Rather, the diversity of frontalmost appendages in "stem bivalved" arthropods, distinct in its absence of clear clustering, is found to link the morphologies of "short great appendages," chelicerae and antennules. This find fits the hypothesis of an increase in disparity of the deutocerebral appendage prior to its diversification in euarthropods, and possibly corresponds to its original time of development. The

  7. Cephalic and limb anatomy of a new Isoxyid from the Burgess Shale and the role of "stem bivalved arthropods" in the disparity of the frontalmost appendage.

    Science.gov (United States)

    Aria, Cédric; Caron, Jean-Bernard

    2015-01-01

    We herein describe Surusicaris elegans gen. et sp. nov. (in Isoxyidae, amended), a middle (Series 3, Stage 5) Cambrian bivalved arthropod from the new Burgess Shale deposit of Marble Canyon (Kootenay National Park, British Columbia). Surusicaris exhibits 12 simple, partly undivided biramous trunk limbs with long tripartite caeca, which may illustrate a plesiomorphic "fused" condition of exopod and endopod. We construe also that the head is made of five somites (= four segments), including two eyes, one pair of anomalocaridid-like frontalmost appendages, and three pairs of poorly sclerotized uniramous limbs. This fossil may therefore be a candidate for illustrating the origin of the plesiomorphic head condition in euarthropods, and questions the significance of the "two-segmented head" in, e.g., fuxianhuiids. The frontalmost appendage in isoxyids is intriguingly disparate, bearing similarities with both dinocaridids and euarthropods. In order to evaluate the relative importance of bivalved arthropods, such as Surusicaris, in the hypothetical structuro-functional transition between the dinocaridid frontal appendage and the pre-oral-arguably deutocerebral-appendage of euarthropods, we chose a phenetic approach and computed morphospace occupancy for the frontalmost appendages of 36 stem and crown taxa. Results show different levels of evolutionary decoupling between frontalmost appendage disparity and body plans. Variance is greatest in dinocaridids and "stem bivalved" arthropods, but these groups do not occupy the morphospace homogeneously. Rather, the diversity of frontalmost appendages in "stem bivalved" arthropods, distinct in its absence of clear clustering, is found to link the morphologies of "short great appendages," chelicerae and antennules. This find fits the hypothesis of an increase in disparity of the deutocerebral appendage prior to its diversification in euarthropods, and possibly corresponds to its original time of development. The analysis of this

  8. Accumulation of butyl- and phenyltin compounds in starfish and bivalves from the coastal environment of Korea

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Won Joon [Southern Coastal Environment Research Division, Korea Ocean Research and Development Institute, Jangmok-myon 391, Geoje 656-830 (Korea, Republic of)]. E-mail: wjshim@kordi.re.kr; Yim, Un Hyuk [Southern Coastal Environment Research Division, Korea Ocean Research and Development Institute, Jangmok-myon 391, Geoje 656-830 (Korea, Republic of); Kim, Nam Sook [Southern Coastal Environment Research Division, Korea Ocean Research and Development Institute, Jangmok-myon 391, Geoje 656-830 (Korea, Republic of); Hong, Sang Hee [Southern Coastal Environment Research Division, Korea Ocean Research and Development Institute, Jangmok-myon 391, Geoje 656-830 (Korea, Republic of); Oh, Jae Ryoung [Southern Coastal Environment Research Division, Korea Ocean Research and Development Institute, Jangmok-myon 391, Geoje 656-830 (Korea, Republic of); Jeon, Joong Kyun [Department of Marine Bioscience and Technology, Kangnung National University, Kangnung 210-702 (Korea, Republic of); Okamura, Hideo [Laboratory of Marine Environment Management, Kobe University Mercantile Marine, Fukaeminami 5-1-1, Highshinada, Kobe 658-0022 (Japan)

    2005-02-01

    Triphenyltin (TPT) and tributyltin (TBT) concentrations were determined in two starfish species (Asteria pectinifera and Asterias amurensis), bivalves (Crassostrea gigas or Mytilus edulis), and seawater samples from sites around the coasts of Korea. Both TPT and TBT concentrations in starfish ranged from 8 to 1560 ng/g and from <2 to 797 ng/g as Sn on a dry weight basis, respectively. TPT concentration accounted for 75.4% and 86.4% of total phenyltin concentration in A. pectinifera and A. amurensis, respectively, while monobutyltin, a degradation product of TBT, accounted for 86.3% and 57.2% of total butyltin, respectively. Triphenyltin concentrations in A. pectinifera were significantly correlated to water and bivalve TPT concentrations, which implies that dietary uptake of TPT from contaminated prey as well as direct uptake from surrounding water contribute to TPT body residues in the starfish. Starfish could be target organisms for monitoring TPT compound in the marine environment, due to their high accumulation and low degradation capacity towards TPT. - Starfish are effective organisms for monitoring phenyltin contamination in the marine environment.

  9. Accumulation of butyl- and phenyltin compounds in starfish and bivalves from the coastal environment of Korea

    International Nuclear Information System (INIS)

    Shim, Won Joon; Yim, Un Hyuk; Kim, Nam Sook; Hong, Sang Hee; Oh, Jae Ryoung; Jeon, Joong Kyun; Okamura, Hideo

    2005-01-01

    Triphenyltin (TPT) and tributyltin (TBT) concentrations were determined in two starfish species (Asteria pectinifera and Asterias amurensis), bivalves (Crassostrea gigas or Mytilus edulis), and seawater samples from sites around the coasts of Korea. Both TPT and TBT concentrations in starfish ranged from 8 to 1560 ng/g and from <2 to 797 ng/g as Sn on a dry weight basis, respectively. TPT concentration accounted for 75.4% and 86.4% of total phenyltin concentration in A. pectinifera and A. amurensis, respectively, while monobutyltin, a degradation product of TBT, accounted for 86.3% and 57.2% of total butyltin, respectively. Triphenyltin concentrations in A. pectinifera were significantly correlated to water and bivalve TPT concentrations, which implies that dietary uptake of TPT from contaminated prey as well as direct uptake from surrounding water contribute to TPT body residues in the starfish. Starfish could be target organisms for monitoring TPT compound in the marine environment, due to their high accumulation and low degradation capacity towards TPT. - Starfish are effective organisms for monitoring phenyltin contamination in the marine environment

  10. Status and Impacts of Arctic Freshwater Export

    Science.gov (United States)

    Haine, T. W. N.

    2017-12-01

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

  11. Optimal designs of mollusk shells from bivalves to snails.

    Science.gov (United States)

    Okabe, Takuya; Yoshimura, Jin

    2017-02-10

    Bivalve, ammonite and snail shells are described by a small number of geometrical parameters. Raup noted that the vast majority of theoretically possible shell forms do not occur in nature. The constraint factors that regulate the biased distribution of natural form have long since been an open problem in evolution. The problem of whether natural shell form is a result of optimization remains unsolved despite previous attempts. Here we solve this problem by considering the scaling exponent of shell thickness as a morphological parameter. The scaling exponent has a drastic effect on the optimal design of shell shapes. The observed characteristic shapes of natural shells are explained in a unified manner as a result of optimal utilization of shell material resources, while isometric growth in thickness leads to impossibly tight coiling.

  12. 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

  13. Assessing phototoxicity of petroleum using the bivalve Mulinia lateralis and the mysid Mysidopsis bahia

    International Nuclear Information System (INIS)

    Pelletier, M.; Champlin, D.; Burgess, R.; Ho, K.; Kuhn-Hines, A.

    1995-01-01

    One of the major inputs of PAHs in the marine environment is petroleum products. A large and often catastrophic source of petroleum is an oil spill, which releases concentrated quantities of PAHs into the water column. Intermediate molecular weight compounds remain in the water column for a relatively extended length of time. These compounds include phototoxic PAHs such as anthracene, fluoranthene, pyrene, and their substituted derivatives. Assessments of the environmental impact of marine oil spills have not included phototoxicity tests using pelagic larvae of benthic invertebrates. In this study, the photoreactive toxicity of individual PAHs, including anthracene, pyrene, and fluoranthene, were determined using the bivalve, Mulinia lateralis and the mysid, Mysidopsis bahia. Ultraviolet light exposures increased toxicity relative to fluorescent light for both species but a particularly dramatic response was seen using M. lateralis embryos. This species was relatively insensitive when exposed under fluorescent lights, but exhibited up to a 4,000 fold increase in toxicity under ultraviolet lights. Exposures with different types of petroleum (e.g., fuel oil number-sign 2 and crude oil) under fluorescent and ultraviolet light will demonstrate the utility of this bivalve and mysid for assessing oil spill-related acute and sublethal toxicity in the marine environment

  14. Prodigious polyphyly in imperilled freshwater pearly-mussels (Bivalvia: Unionidae): a phylogenetic test of species and generic designations

    Science.gov (United States)

    Lydeard, Charles; Minton, Russell L.; Williams, James D.

    2000-01-01

    Unionid bivalves or freshwater pearly-mussels (Unionoidea: Unionidae) serve as an exemplary system for examining many of the problems facing systematists and conservation biologists today. Most of the species and genera were described in the late 1800s and early 1900s, but few phylogenetic studies have been conducted to test conventional views of species and classification. Pearly-mussels of Gulf Coastal drainages of the southeastern United States from the Escambia (southern Alabama to Florida) to the Suwannee Rivers (Florida) are a unique fauna comprised of approximately 100 species, with about 30 endemic to the region. In this study, mitochondrial cytochrome c oxidase subunit I and 16S rRNA gene sequences were used to test the monophyly and to estimate evolutionary relationships of five unionid species representing three different genera. The molecular phylogenies depict all three genera as polyphyletic. The prodigious polyphyly exhibited within unionids is due to incorrect notions of homology and false assumptions about missing anatomical data. In contrast, the molecular phylogeny provides evidence to support the recognition of all five unionid species as distinct evolutionary entities. Furthermore, molecular genealogical evidence supports the elevation of Quincuncina infucata (Conrad) of the Suwannee River to species level, for which Q. kleiniana (Lea) is available.

  15. 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...

  16. Local monitoring program for invasion of zebra mussel (Dreissena polymorpha) in the Dam lake Zhrebchevo, Bulgaria

    OpenAIRE

    Stoyanova, Stefka; Nikolov, Galin; Velichkova, Katya; Atanasoff, Alexander; Mumun, Sevdegul

    2015-01-01

    Zebra mussels (Dreissena polymorpha) are bivalve mollusks approximately 1 to 5 cm long that live in freshwater lakes. They have invaded many Bulgarian freshwater ecosystems in recent decades. Because of their ability to settle on almost any substrate, zebra mussels cause severe damage to closed water systems, RAS and intensive fish farming systems. In order to assess the status of the mussel population in the lake in the area of the Forest group fish farm, the distribution, extent of coloniza...

  17. Molecular markers for genetic diversity, gene flow and genetic population structure of freshwater mussel species

    Directory of Open Access Journals (Sweden)

    AB Choupina

    Full Text Available Freshwater mussel species are in global decline. Anthropogenic changes of river channels and the decrease of autochthonous fish population, the natural hosts of mussels larval stages (glochidia, are the main causes. Therefore, the conservation of mussel species depends not only on habitat conservation, but also on the availability of the fish host. In Portugal, information concerning most of the mussel species is remarkably scarce. One of the most known species, Unio pictorum is also in decline however, in the basins of the rivers Tua and Sabor (Northeast of Portugal, there is some indication of relatively large populations. The aforementioned rivers can be extremely important for this species conservation not only in Portugal, but also in the remaining Iberian Peninsula. Thus, it is important to obtain data concerning Unio pictorum bioecology (distribution, habitat requirements, population structure, genetic variability, reproductive cycle and recruitment rates, as well as the genetic variability and structure of the population. Concomitantly, information concerning fish population structure, the importance of the different fish species as “glochidia” hosts and their appropriate density to allow effective mussel recruitment, will also be assessed. The achieved data is crucial to obtain information to develop effective management measures in order to promote the conservation of this bivalve species, the conservation of autochthonous fish populations, and consequently the integrity of the river habitats.

  18. Do Zebra Mussels Grow Faster on Live Unionids than on Inanimate Substrate? A Study with Field Enclosures

    Science.gov (United States)

    Hörmann, Leonhard; Maier, Gerhard

    2006-05-01

    The zebra mussel Dreissena polymorpha has invaded numerous freshwaters in Europe and North America and can foul many types of solid substrates, including unionid bivalves. In field experiments we compared growth rates of dreissenids on live specimens of the freshwater bivalve Anodonta cygnea to growth rates of dreissenids on stones. Dreissena density in the study lake was about 1000 m-2 in most places, Anodonta density approximately 1 m-2 and about 50% of the Anodonta were infested with 10-30 Dreissena . In summer/autumn small dreissenids generally grew faster on live Anodonta than on stones. Similar trends were observed for spring, but differences of growth increments between dreissenids on live Anodonta and stones were usually not significant. Dreissenids settled down or moved towards the ingestion/egestion siphons of Anodonta and ingestion siphons of dreissenids were directed towards siphons of Anodonta . These results suggest that dreissenids can use the food provided by the filter current of the large Anodonta .

  19. 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...

  20. The quagga mussel (Dreissena rostriformis bugensis Andrusov, 1897) – another Ponto-Caspian dreissenid bivalve in the southern Baltic catchment: the first record from the Szczecin Lagoon

    OpenAIRE

    Adam Woźniczka; Brygida Wawrzyniak-Wydrowska; Teresa Radziejewska; Anna Skrzypacz

    2016-01-01

    In 2014, a non-indigenous dreissenid bivalve, the quagga mussel (Dreissena rostriformis bugensis Andrusov, 1897) was for the first time recorded in the Szczecin Lagoon. This was also the first record of the species in the Baltic Sea catchment. The quagga mussel was found to accompany the zebra mussel (Dreissena polymorpha), a non-indigenous bivalve already firmly established in the Lagoon. As indicated by the new immigrant's estimated abundance (4000.0 ± 355.44 ind. m−2) and the zebra mussel ...

  1. Soundscapes and Larval Settlement: Larval Bivalve Responses to Habitat-Associated Underwater Sounds.

    Science.gov (United States)

    Eggleston, David B; Lillis, Ashlee; Bohnenstiehl, DelWayne R

    2016-01-01

    We quantified the effects of habitat-associated sounds on the settlement response of two species of bivalves with contrasting habitat preferences: (1) Crassostrea virginicia (oyster), which prefers to settle on other oysters, and (2) Mercenaria mercenaria (clam), which settles on unstructured habitats. Oyster larval settlement in the laboratory was significantly higher when exposed to oyster reef sound compared with either off-reef or no-sound treatments. Clam larval settlement did not vary according to sound treatments. Similar to laboratory results, field experiments showed that oyster larval settlement in "larval housings" suspended above oyster reefs was significantly higher compared with off-reef sites.

  2. An ecosystem-based approach and management framework for the integrated evaluation of bivalve aquaculture impacts

    OpenAIRE

    Cranford, Peter J.; Kamermans, Pauline; Krause, Gesche; Mazurie, Joseph; Buck, Bela H.; Dolmer, Per; Fraser, David; Van Nieuwenhove, Kris; O'Beirn, Francis X.; Sanchez-mata, Adoracion; Thorarinsdottir, Gudrun G.; Strand, Oivind

    2012-01-01

    An ecosystem-based approach to bivalve aquaculture management is a strategy for the integration of aquaculture within the wider ecosystem, including human aspects, in such a way that it promotes sustainable development, equity, and resilience of ecosystems. Given the linkage between social and ecological systems, marine regulators require an ecosystem-based decision framework that structures and integrates the relationships between these systems and facilitates communication of aquaculture–en...

  3. 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)

  4. Methods for preparing synthetic freshwaters.

    Science.gov (United States)

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

    2002-03-01

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

  5. Molecular systematics of the critically-endangered North American spinymussels (Unionidae: Elliptio and Pleurobema) and description of Parvaspina gen. nov.

    Science.gov (United States)

    Perkins, Michael A.; Johnson, Nathan A.; Gangloff, Michael M.

    2017-01-01

    Despite being common in numerous marine bivalve lineages, lateral spines are extremely rare among freshwater bivalves (Bivalvia: Unionidae), with only three known species characterized by the presence of spines: Elliptio spinosa, Elliptio steinstansana, and Pleurobema collina. All three taxa are endemic to the Atlantic Slope of southeastern North America, critically endangered, and protected by the US Endangered Species Act. Currently, these species are recognized in two genera and remain a source of considerable taxonomic confusion. Because spines are rare in freshwater mussels and restricted to a small region of North America, we hypothesized that spinymussels represent a monophyletic group. We sequenced two mtDNA gene fragments (COI and ND1) and a fragment of the nuclear ITS-1 locus from >70 specimens. Bayesian and maximum-likelihood phylogenetic reconstructions suggest that the spinymussels do not comprise a monophyletic group. Elliptio steinstansana is sister to P. collina, forming a monophyletic clade that was estimated to have diverged from its most recent ancestor in the late Miocene and is distinct from both Elliptio and Pleurobema; we describe a new genus (Parvaspina gen. nov.) to reflect this relationship. Additionally, E. spinosa forms a monophyletic clade that diverged from members of the core Elliptio lineage in the mid-Pliocene. Furthermore, E. spinosa is genetically divergent from the other spinymussel species, suggesting that spines, while extremely rare in freshwater mussels worldwide, may have evolved independently in two bivalve lineages. Recognizing the genetic distinctiveness and inter-generic relationships of the spinymussels is an important first step towards effectively managing these imperiled species and lays the groundwork for future conservation genetics studies.

  6. Sensitivity of Mediterranean bivalve mollusc aquaculture to climate change, ocean acidification, and other environmental pressures: findings from a producers’ survey

    NARCIS (Netherlands)

    Rodrigues, L.; van den Bergh, J.C.J.M.; Mass, F.; Theodorou, J.A.; Ziveri, P.; Gazeau, F.

    2015-01-01

    Human-induced climate change and ocean acidification are global environmental phenomena with a common driver: anthropogenic emissions of carbon dioxide. Both processes potentially threaten the Mediterranean bivalve mollusc aquaculture sector, which is economically relevant to several regions and

  7. Carbon and nitrogen elemental and isotopic ratios of filter-feeding bivalves along the French coasts: An assessment of specific, geographic, seasonal and multi-decadal variations.

    Science.gov (United States)

    Briant, Nicolas; Savoye, Nicolas; Chouvelon, Tiphaine; David, Valérie; Rodriguez, Samuel; Charlier, Karine; Sonke, Jeroen E; Chiffoleau, Jean François; Brach-Papa, Christophe; Knoery, Joël

    2018-02-01

    Primary consumers play a key role in coastal ecosystems by transferring organic matter from primary producers to predators. Among them, suspension-feeders, like bivalve molluscs are widely used in trophic web studies. The main goal of this study was to investigate variations of C and N elemental and isotopic ratios in common bivalves (M. edulis, M. galloprovincialis, and C. gigas) at large spatial (i.e. among three coastal regions) and different temporal (i.e. from seasonal to multi-decadal) scales in France, in order to identify potential general or specific patterns and speculate on their drivers. The observed spatial variability was related to the trophic status of the coastal regions (oligotrophic Mediterranean Sea versus meso- to eutrophic English Channel and Atlantic ocean), but not to ecosystem typology (estuaries, versus lagoons versus bays versus littoral systems). Furthermore, it highlighted local specificities in terms of the origin of the POM assimilated by bivalves (e.g., mainly continental POM vs. marine phytoplankton vs. microphytobenthic algae). Likewise, seasonal variability was related both to the reproduction cycle for C/N ratios of Mytilus spp. and to changes in trophic resources for δ 13 C of species located close to river mouth. Multi-decadal evolution exhibited shifts and trends for part of the 30-year series with decreases in δ 13 C and δ 15 N. Specifically, shifts appeared in the early 2000's, likely linking bivalve isotopic ratios to a cascade of processes affected by local drivers. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. The Complete Maternally and Paternally Inherited Mitochondrial Genomes of a Freshwater Mussel Potamilus alatus (Bivalvia: Unionidae.

    Directory of Open Access Journals (Sweden)

    Hai B Wen

    Full Text Available Doubly uniparental inheritance (DUI of mitochondrial DNA, found only in some bivalve families and characterized by the existence of gender-associated mtDNA lineages that are inherited through males (M-type or females (F-type, is one of the very few exceptions to the general rule of strict maternal mtDNA inheritance in animals. M-type sequences are often undetected and hence still underrepresented in the GenBank, which hinders the progress of the understanding of the DUI phenomenon. We have sequenced and analyzed the complete M and F mitogenomes of a freshwater mussel, Potamilus alatus. The M-type was 493 bp longer (M = 16 560, F = 16 067 bp. Gene contents, order and the distribution of genes between L and H strands were typical for unionid mussels. Candidates for the two ORFan genes (forf and morf were found in respective mitogenomes. Both mitogenomes had a very similar A+T bias: F = 61% and M = 62.2%. The M mitogenome-specific cox2 extension (144 bp is much shorter than in other sequenced unionid mitogenomes (531-576 bp, which might be characteristic for the Potamilus genus. The overall topology of the phylogenetic tree is in very good agreement with the currently accepted phylogenetic relationships within the Unionidae: both studied sequences were placed within the Ambleminae subfamily clusters in the corresponding M and F clades.

  9. Subcellular compartmentalization of Cd and Zn in two bivalves. II. Significance of trophically available metal (TAM)

    Science.gov (United States)

    Wallace, W.G.; Luoma, S.N.

    2003-01-01

    This paper examines how the subcellular partitioning of Cd and Zn in the bivalves Macoma balthica and Potamocorbula amurensis may affect the trophic transfer of metal to predators. Results show that the partitioning of metals to organelles, 'enzymes' and metallothioneins (MT) comprise a subcellular compartment containing trophically available metal (TAM; i.e. metal trophically available to predators), and that because this partitioning varies with species, animal size and metal, TAM is similarly influenced. Clams from San Francisco Bay, California, were exposed for 14 d to 3.5 ??g 1-1 Cd and 20.5 ??g 1-1 Zn, including 109Cd and 65Zn as radiotracers, and were used in feeding experiments with grass shrimp Palaemon macrodatylus, or used to investigate the subcellular partitioning of metal. Grass shrimp fed Cd-contaminated P. amurensis absorbed ???60% of ingested Cd, which was in accordance with the partitioning of Cd to the bivalve's TAM compartment (i.e. Cd associated with organelles, 'enzymes' and MT); a similar relationship was found in previous studies with grass shrimp fed Cd-contaminated oligochaetes. Thus, TAM may be used as a tool to predict the trophic transfer of at least Cd. Subcellular fractionation revealed that ???34% of both the Cd and Zn accumulated by M. balthica was associated with TAM, while partitioning to TAM in P. amurensis was metal-dependent (???60% for TAM-Cd%, ???73% for TAM-Zn%). The greater TAM-Cd% of P. amurensis than M. balthica is due to preferential binding of Cd to MT and 'enzymes', while enhanced TAM-Zn% of P. amurensis results from a greater binding of Zn to organelles. TAM for most species-metal combinations was size-dependent, decreasing with increased clam size. Based on field data, it is estimated that of the 2 bivalves, P. amurensis poses the greater threat of Cd exposure to predators because of higher tissue concentrations and greater partitioning as TAM; exposure of Zn to predators would be similar between these species.

  10. Immunomodulation by different types of N-oxides in the hemocytes of the marine bivalve Mytilus galloprovincialis.

    Directory of Open Access Journals (Sweden)

    Caterina Ciacci

    Full Text Available The potential toxicity of engineered nanoparticles (NPs for humans and the environment represents an emerging issue. Since the aquatic environment represents the ultimate sink for NP deposition, the development of suitable assays is needed to evaluate the potential impact of NPs on aquatic biota. The immune system is a sensitive target for NPs, and conservation of innate immunity represents an useful basis for studying common biological responses to NPs. Suspension-feeding invertebrates, such as bivalves, are particularly at risk to NP exposure, since they have extremely developed systems for uptake of nano and microscale particles integral to intracellular digestion and cellular immunity. Evaluation of the effects of NPs on functional parameters of bivalve immunocytes, the hemocytes, may help understanding the major toxic mechanisms and modes of actions that could be relevant for different NP types in aquatic organisms.In this work, a battery of assays was applied to the hemocytes of the marine bivalve Mytilus galloprovincialis to compare the in vitro effects of different n-oxides (n-TiO(2, n-SiO(2, n-ZnO, n-CeO(2 chosen on the basis of their commercial and environmental relevance. Physico-chemical characterization of both primary particles and NP suspensions in artificial sea water-ASW was performed. Hemocyte lysosomal and mitochondrial parameters, oxyradical and nitric oxide production, phagocytic activity, as well as NP uptake, were evaluated. The results show that different n-oxides rapidly elicited differential responses hemocytes in relation to their chemical properties, concentration, behavior in sea water, and interactions with subcellular compartments. These represent the most extensive data so far available on the effects of NPs in the cells of aquatic organisms. The results indicate that Mytilus hemocytes can be utilized as a suitable model for screening the potential effects of NPs in the cells of aquatic invertebrates, and may

  11. The role of local adaptation in shaping fish-mussel coevolution

    Czech Academy of Sciences Publication Activity Database

    Douda, K.; Liu, H.-Z.; Yu, D.; Rouchet, Romain; Liu, F.; Tang, Q.-Y.; Methling, Caroline; Smith, Carl; Reichard, Martin

    2017-01-01

    Roč. 62, č. 11 (2017), s. 1858-1868 ISSN 0046-5070 R&D Projects: GA ČR GA13-05872S Institutional support: RVO:68081766 Keywords : affiliate species * freshwater bivalves * glochidia * host relationships * Sinanodonta woodiana Subject RIV: EH - Ecology, Behaviour OBOR OECD: Ecology Impact factor: 3.255, year: 2016

  12. A comparison of tools for modeling freshwater ecosystem services.

    Science.gov (United States)

    Vigerstol, Kari L; Aukema, Juliann E

    2011-10-01

    Interest in ecosystem services has grown tremendously among a wide range of sectors, including government agencies, NGO's and the business community. Ecosystem services entailing freshwater (e.g. flood control, the provision of hydropower, and water supply), as well as carbon storage and sequestration, have received the greatest attention in both scientific and on-the-ground applications. Given the newness of the field and the variety of tools for predicting water-based services, it is difficult to know which tools to use for different questions. There are two types of freshwater-related tools--traditional hydrologic tools and newer ecosystem services tools. Here we review two of the most prominent tools of each type and their possible applications. In particular, we compare the data requirements, ease of use, questions addressed, and interpretability of results among the models. We discuss the strengths, challenges and most appropriate applications of the different models. Traditional hydrological tools provide more detail whereas ecosystem services tools tend to be more accessible to non-experts and can provide a good general picture of these ecosystem services. We also suggest gaps in the modeling toolbox that would provide the greatest advances by improving existing tools. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. 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.

  14. Systematics, functional morphology and distribution of a bivalve (Apachecorbula muriatica gen. et sp. nov.) from the rim of the 'Valdivia Deep' brine pool in the Red Sea

    KAUST Repository

    Oliver, Pere Graham

    2014-11-11

    The deep brine pools of the Red Sea comprise extreme, inhospitable habitats yet house microbial communities that potentially may fuel adjacent fauna. We here describe a novel bivalve from a deep-sea (1525 m) brine pool in the Red Sea, where conditions of high salinity, lowered pH, partial anoxia and high temperatures are prevalent. Remotely operated vehicle (ROV) footage showed that the bivalves were present in a narrow (20 cm) band along the rim of the brine pool, suggesting that it is not only tolerant of such extreme conditions but is also limited to them. The bivalve is a member of the Corbulidae and named Apachecorbula muriatica gen. et sp. nov. The shell is atypical of the family in being modioliform and thin. The semi-infaunal habit is seen in ROV images and reflected in the anatomy by the lack of siphons. The ctenidia are large and typical of a suspension feeding bivalve, but the absence of \\'guard cilia\\' and the greatly reduced labial palps suggest that it is non-selective as a response to low food availability. It is proposed that the low body mass observed is a consequence of the extreme habitat and low food availability. It is postulated that the observed morphology of Apachecorbula is a result of paedomorphosis driven by the effects of the extreme environment on growth but is in part mitigated by the absence of high predation pressures. © Marine Biological Association of the United Kingdom, 2014.

  15. Using transplanted bivalves to assess oil exposure and effects in Delaware Bay

    International Nuclear Information System (INIS)

    Salazar, M.; Salazar, S.; Mearns, A.; Venosa, A.; Eberhart, B.

    1995-01-01

    To evaluate the effectiveness of bioremediation, the US EPA oiled intertidal plots in Delaware Bay and monitored oil degradation rates. This controlled release of oil was also used to test the utility of transplanted bivalves in assessing oil spills and to evaluate the extent and potential effects of the release. Measuring the accumulation of oil in bivalve tissues was used to estimate exposure and the extent of contamination. Growth was used to estimate potential bioeffects. Approximately 1,800 mussels and 1,200 oysters were transplanted to 11 intertidal sites. Five treatment sites were within 1 meter of the lower end of the oiled plots. A total of six sites were used as controls, three on either side of the oiled plots at 5, 10, and 100 m. Samples were taken on Day 0, 2, 15, and 28 to estimate the rate of bioaccumulation. All of the mussels died within the first week of exposure; oysters exhibited over 95% survival but growth was minimal. The authors found a statistically significant difference in tissue weights when comparing treatment sites with control sites. The total concentration of polynuclear aromatic hydrocarbons (PAHs) in tissues of oysters nearest the oiled plots increased by a factor of four after an exposure period of two days. PAH concentrations in control oysters nearest the mouth of the bay increased slightly but the differences were not statistically significant. The control oysters nearest the head of the bay received an intermediate dose which was depurated by the end of the 28-day experiment. PAHs in the oysters nearest the oiled plots approached but did not return to background levels by the end of the test

  16. Occurrence of potentially pathogenic Vibrio in oysters (Crassostrea gigas) and waters from bivalve mollusk cultivations in the South Bay of Santa Catarina.

    Science.gov (United States)

    Ramos, Roberta Juliano; Miotto, Letícia Adélia; Miotto, Marília; Silveira Junior, Nelson; Cirolini, Andréia; Silva, Helen Silvestre da; Rodrigues, Dália dos Prazeres; Vieira, Cleide Rosana Werneck

    2014-01-01

    This research aimed to identify and quantify potentially pathogenic Vibrio from different cultivations of bivalve shellfish in the State of Santa Catarina, Brazil, and water regions in the South Bay, as well as correlate the incidence of these microorganisms with the physicochemical parameters of marine waters. Between October 2008 and March 2009, 60 oyster and seawater samples were collected from six regions of bivalve mollusk cultivation, and these samples were submitted for Vibrio counts. Twenty-nine (48.3%) oyster samples were revealed to be contaminated with one or more Vibrio species. The Vibrio parahaemolyticus and Vibrio vulnificus counts in the samples ranged from oyster and from oyster, respectively. Of the 60 seawater samples analyzed, 44 (73.3%) showed signs of contamination with one or more vibrio species. The counts of V. parahaemolyticus and V. vulnificus in the samples ranged from < 0.3 log10 MPN·100mL(-1) to 1.7 log10MPN·100mL(-1) seawater and from < 0.3 log10 MPN·100mL(-1) to 2.0 log10 MPN·100mL(-1) seawater, respectively. A positive correlation between V. vulnificus counts and the seawater temperature as well as a negative correlation between the V. parahaemolyticus counts and salinity were observed. The results suggest the need to implement strategies to prevent vibrio diseases from being transmitted by the consumption of contaminated bivalve shellfish.

  17. Respiration of bivalves from three different deep-sea areas: Cold seeps, hydrothermal vents and organic carbon-rich sediments

    Science.gov (United States)

    Khripounoff, A.; Caprais, J. C.; Decker, C.; Le Bruchec, J.; Noel, P.; Husson, B.

    2017-08-01

    We studied bivalves (vesicomyids and mytilids) inhabiting four different areas of high sulfide and methane production: (1) in the Gulf of Guinea, two pockmarks (650 m and 3150 m depth) and one site rich in organic sediments in the deepest zone (4950 m average depth), (2) at the Azores Triple Junction on the Mid-Atlantic Ridge, one hydrothermal site (Lucky Strike vent field, 1700 m depth). Two types of Calmar benthic chambers were deployed, either directly set into the sediment (standard Calmar chamber) or fitted with a tank to isolate organisms from the sediment (modified Calmar chamber), to assess gas and solute exchanges in relation to bivalve bed metabolism. Fluxes of oxygen, total carbon dioxide, ammonium and methane were measured. At the site with organic-rich sediments, oxygen consumption by clams measured in situ with the standard benthic chamber was variable (1.3-6.7 mmol m-2 h-1) as was total carbon dioxide production (1-9.6 mmol m-2 h-1). The observed gas and solute fluxes were attributed primarily to bivalve respiration (vesicomyids or mytilids), but microbial and geochemical processes in the sediment may be also responsible for some of variations in the deepest stations. The respiration rate of isolated vesicomyids (16.1-0.25.7 μmol g-1 dry weight h-1) was always lower than that of mytilids (33 μmol g-1 dry weight h-1). This difference was attributed to the presence of a commensal scaleworm in the mytilids. The respiratory coefficient (QR) ≥1 indicated high levels of anaerobic metabolism. The O:N index ranged from 5 to 25, confirming that vesicomyids and mytilids, living in symbiosis with bacteria, have a protein-based food diet.

  18. Estimation of food limitation of bivalve larvae in coastal waters of north-western Europe

    DEFF Research Database (Denmark)

    Bos, O.G.; Hendriks, I.E.; Strasser, M.

    2006-01-01

    Marine invertebrate recruitment may be affected by food limitation during the pelagic larval life stages. In the present study, field data on abundance of bivalve larvae along with their prey (small phytoplankton) were examined to see whether they were consistent with predictions made...... assimilation rate averaged 7-26% of the maximum assimilation rate. Under the assumptions made for the present study, it is suggested that growth of larvae in north-west European waters is often food-limited. (c) 2005 Elsevier B.V. All rights reserved...

  19. PAH assessment in the main Brazilian offshore oil and gas production area using semi-permeable membrane devices (SPMD) and transplanted bivalves

    Science.gov (United States)

    André Lourenço, Rafael; Francisco de Oliveira, Fábio; Haddad Nudi, Adriana; Rebello Wagener, Ângela de Luca; Guadalupe Meniconi, Maria de Fátima; Francioni, Eleine

    2015-06-01

    The Campos Basin is Brazil's main oil and gas production area. In 2013, more than 50 million cubic meters of produced water (PW) was discharged into these offshore waters. Despite the large volumes of PW that are discharged in the Campos Basin each day, the ecological concern of the chemicals in the PW are not completely understood. Polycyclic aromatic hydrocarbons (PAH) are the most important contributors to the ecological hazards that are posed by discharged PW. This study aimed to evaluate the potential bioaccumulation of PAH using transplanted bivalves (Nodipecten nodosus) and semi-permeable membrane devices (SPMD). The study was conducted in two platforms that discharge PW (P19 and P40). Another platform that does not discharge PW (P25) was investigated for comparison with the obtained results. Time-integrated hydrocarbon concentrations using SPMD and transplanted bivalves were estimated from the seawater near the three platforms. The bioaccumulation of the PAH in the transplanted bivalves at platforms P19 and P40 were up to fivefold greater than the bioaccumulation of the PAH at platform P25. The lowest PAH concentrations were estimated for platform P25 (4.3-6.2 ng L-1), and the highest PAH concentrations were estimated for platform P19 (9.2-37.3 ng L-1). Both techniques were effective for determining the bioavailability of the PAH and for providing time-integrated hydrocarbon concentrations regarding oil and gas production activities.

  20. Alkylphenols and polycyclic aromatic hydrocarbons in bivalves from Comunidad Valenciana coastal waters; Alquilfenoles e hidrocarburos aromaticos policiclicos en bivalvos de las coastas de la comunidad Valenciana

    Energy Technology Data Exchange (ETDEWEB)

    Marti Ortega, N.; Aguado Garcia, D.; Bouzas Blanco, A.; Segovia Martinez, L.; Albargues Llamas, M.; Sevillano Cabeza, A.; Campins Falco, P.; Seco Torrecillas, A.; Ferrer Polo, J.

    2009-07-01

    This paper reports the results on alkylphenol and polycyclic aromatic hydrocarbons (PAH) pollution in mussels and cleans from Comunidad Valenciana coastal waters, in 2008. The significant presence of nonylphenol observed in both bivalves reflects an exposure to alkyl phenolic surfactants from the discharges of wastewater treatment plants that treat industrial and urban wastewaters, where the presence of alkylphenol polyethoxylated is common due to its extensive use (detergents, solubilizers...). The presence of low levels of PAH was observed in most of the studied areas. However, it must be highlighted that bivalves consumption does not imply any risk for human health. (Author) 21 refs.

  1. Bioaccumulation of selected metals in bivalves (Unionidae) and Phragmites australis inhabiting a municipal water reservoir

    OpenAIRE

    Rzymski, Piotr; Niedzielski, Przemysław; Klimaszyk, Piotr; Poniedziałek, Barbara

    2014-01-01

    Urbanization can considerably affect water reservoirs by, inter alia, input, and accumulation of contaminants including metals. Located in the course of River Cybina, Maltański Reservoir (Western Poland) is an artificial shallow water body built for recreation and sport purposes which undergoes restoration treatment (drainage) every 4 years. In the present study, we demonstrate an accumulation of nine metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in water, sediment, three bivalve species (Anodo...

  2. Plankton and Macrobiota Composition and Diversity of Three Tropical Freshwaters Rivers in Ogun and Ondo States, Southwest Nigeria

    Directory of Open Access Journals (Sweden)

    Taofikat Abosede ADESALU

    2016-06-01

    Full Text Available Three different rivers in Ogun and Ondo states were investigated for both micro and macro-biota of the water bodies. Several physical and chemical properties of these rivers were determined. The pH value of the studied water bodies was essentially neutral with salinity values between 0.02 - 4.0‰. Microalgae communities were represented by three divisions: Cyanophyta, Bacillariophyta and Chlorophyta at Oluwa and Ifara Rivers (Ondo state, while at Ibefun River (Ogun state, five divisions: Cyanophyta, Bacillariophyta, Chlorophyta, Euglenophyta and Pyrrhophyta were identified. Diatoms dominated these water bodies, with Navicula radiosa Kutz. at Ifara River, Fragilaria sp. in Oluwa River, while out of 90 algal taxa identified in Ibefun river, 64 were diatoms species belonging to 26 genera, with Melosira sp. and Synedra sp. recording the highest numbers of cell count. Dinoflagellates recorded only Peridinium sp. while Phacus orbicularis Hubner and Trachelomonas sp. dominated the euglenoids. For the zooplankton composition at Ibefun, rotifers (75.95% were represented by Brachionus sp., which recorded 62.03%, and Gastropus sp. with 13.92% of the total zooplankton, thus dominated the spectrum, while the copepod recorded 22.78% of the total organisms, with Copilia sp. and Euchirella sp. having 8.86% each. The macrobenthic invertebrates were represented by 3 taxa, belonging to 3 groups, with the dominant group Insecta accounted for 57% of the total individuals (7 individuals/m2, while Oligochaeta and Hirudinea accounted for 29% and 14% respectively of the total individuals at Oluwa and Ifara Rivers. At Ibefun River, the macrobenthic invertebrates were represented by 5 taxa, belonging to 3 groups, Bivalves, Oligochaeta and Insecta, with bivalves being the dominant group (51.7% of the total individuals, as 64 individuals/m2, while Oligochaeta and Insecta accounted for 26.6% and 21.9% respectively of the total individuals. The dominant taxon, Macoma cumana

  3. Source and impact of lead contamination on {delta}-aminolevulinic acid dehydratase activity in several marine bivalve species along the Gulf of Cadiz

    Energy Technology Data Exchange (ETDEWEB)

    Company, R.; Serafim, A.; Lopes, B.; Cravo, A. [CIMA, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal); Kalman, J.; Riba, I.; DelValls, T.A. [Catedra UNESCO/UNITWIN/WiCop, Department of Physical-Chemistry, Faculty Marine and Environmental Sciences, University of Cadiz, 11510 Puerto Real, Cadiz (Spain); Blasco, J. [Instituto Ciencias Marinas Andalucia (CSIC), Campus Rio San Pedro, 11510 Puerto Real, Cadiz (Spain); Delgado, J. [Department of Geology, University of Huelva, Avda Fuerzas Armadas s/n, 21071 Huelva (Spain); Sarmiento, A.M. [Catedra UNESCO/UNITWIN/WiCop, Department of Physical-Chemistry, Faculty Marine and Environmental Sciences, University of Cadiz, 11510 Puerto Real, Cadiz (Spain); Department of Geology, University of Huelva, Avda Fuerzas Armadas s/n, 21071 Huelva (Spain); Nieto, J.M. [Department of Geology, University of Huelva, Avda Fuerzas Armadas s/n, 21071 Huelva (Spain); Shepherd, T.J.; Nowell, G. [Department of Earth Sciences, University of Durham, Science Laboratories, Durham DH1 3LE (United Kingdom); Bebianno, M.J., E-mail: mbebian@ualg.pt [CIMA, University of Algarve, Campus de Gambelas, 8005-139 Faro (Portugal)

    2011-01-17

    Coastal areas and estuaries are particularly sensitive to metal contamination from anthropogenic sources and in the last few decades the study of space-time distribution and variation of metals has been extensively researched. The Gulf of Cadiz is no exception, with several rivers draining one of the largest concentrations of sulphide deposits in the world, the Iberian Pyrite Belt (IPB). Of these rivers, the Guadiana, one of the most important in the Iberian Peninsula, together with smaller rivers like the Tinto and Odiel, delivers a very high metal load to the adjacent coastal areas. The purpose of this work was to study the source and impact of lead (Pb) drained from historical or active mining areas in the IPB on the activity of a Pb inhibited enzyme ({delta}-aminolevulinic acid dehydratase, ALAD) in several bivalve species along the Gulf of Cadiz. Seven marine species (Chamelea gallina, Mactra corallina, Donax trunculus, Cerastoderma edule, Mytilus galloprovincialis, Scrobicularia plana and Crassostrea angulata) were collected at 12 sites from Mazagon, near the mouth of the rivers Tinto and Odiel (Spain), to Cacela Velha (Ria Formosa lagoon system, Portugal). Lead concentrations, ALAD activity and lead isotope ratios ({sup 206}Pb/{sup 204}Pb, {sup 207}Pb/{sup 204}Pb and {sup 208}Pb/{sup 204}Pb) were determined in the whole soft tissues. The highest Pb concentrations were determined in S. plana (3.50 {+-} 1.09 {mu}g g{sup -1} Pb d.w.) and D. trunculus (1.95 {+-} 0.10 {mu}g g{sup -1} Pb d.w.), while M. galloprovincialis and C. angulata showed the lowest Pb levels (<0.38 {mu}g g{sup -1} Pb d.w.). In general, ALAD activity is negatively correlated with total Pb concentration. However this relationship is species dependent (e.g. linear for C. gallina ALAD = -0.36[Pb] + 0.79; r = 0.837; or exponential for M. galloprovincialis ALAD = 2.48e{sup -8.3[Pb]}; r = 0.911). This indicates that ALAD activity has considerable potential as a biomarker of Pb and moreover, in

  4. Source and impact of lead contamination on δ-aminolevulinic acid dehydratase activity in several marine bivalve species along the Gulf of Cadiz

    International Nuclear Information System (INIS)

    Company, R.; Serafim, A.; Lopes, B.; Cravo, A.; Kalman, J.; Riba, I.; DelValls, T.A.; Blasco, J.; Delgado, J.; Sarmiento, A.M.; Nieto, J.M.; Shepherd, T.J.; Nowell, G.; Bebianno, M.J.

    2011-01-01

    Coastal areas and estuaries are particularly sensitive to metal contamination from anthropogenic sources and in the last few decades the study of space-time distribution and variation of metals has been extensively researched. The Gulf of Cadiz is no exception, with several rivers draining one of the largest concentrations of sulphide deposits in the world, the Iberian Pyrite Belt (IPB). Of these rivers, the Guadiana, one of the most important in the Iberian Peninsula, together with smaller rivers like the Tinto and Odiel, delivers a very high metal load to the adjacent coastal areas. The purpose of this work was to study the source and impact of lead (Pb) drained from historical or active mining areas in the IPB on the activity of a Pb inhibited enzyme (δ-aminolevulinic acid dehydratase, ALAD) in several bivalve species along the Gulf of Cadiz. Seven marine species (Chamelea gallina, Mactra corallina, Donax trunculus, Cerastoderma edule, Mytilus galloprovincialis, Scrobicularia plana and Crassostrea angulata) were collected at 12 sites from Mazagon, near the mouth of the rivers Tinto and Odiel (Spain), to Cacela Velha (Ria Formosa lagoon system, Portugal). Lead concentrations, ALAD activity and lead isotope ratios ( 206 Pb/ 204 Pb, 207 Pb/ 204 Pb and 208 Pb/ 204 Pb) were determined in the whole soft tissues. The highest Pb concentrations were determined in S. plana (3.50 ± 1.09 μg g -1 Pb d.w.) and D. trunculus (1.95 ± 0.10 μg g -1 Pb d.w.), while M. galloprovincialis and C. angulata showed the lowest Pb levels ( -1 Pb d.w.). In general, ALAD activity is negatively correlated with total Pb concentration. However this relationship is species dependent (e.g. linear for C. gallina ALAD = -0.36[Pb] + 0.79; r = 0.837; or exponential for M. galloprovincialis ALAD = 2.48e -8.3[Pb] ; r = 0.911). This indicates that ALAD activity has considerable potential as a biomarker of Pb and moreover, in marine bivalve species with different feeding habits. Lead isotope data

  5. Farming of Freshwater Rainbow Trout in Denmark

    DEFF Research Database (Denmark)

    Jokumsen, Alfred; Svendsen, Lars Moeslund

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

  6. The assessment of ionising radiation impact on the cooling pond freshwater ecosystem non-human biota from the Ignalina NPP operation beginning to shut down and initial decommissioning.

    Science.gov (United States)

    Mazeika, J; Marciulioniene, D; Nedveckaite, T; Jefanova, O

    2016-01-01

    The radiological doses to non-human biota of freshwater ecosystem in the Ignalina NPP cooling pond - Lake Druksiai were evaluated for several cases including the plant's operation period and initial decommissioning activities, using the ERICA 1.2 code with IAEA SRS-19 models integrated approach and tool. Among the Lake Druksiai freshwater ecosystem reference organisms investigated the highest exposure dose rate was determined for bottom fauna - benthic organisms (mollusc-bivalves, crustaceans, mollusc-gastropods, insect larvae), and among the other reference organisms - for vascular plants. The mean and maximum total dose rate values due to anthropogenic radionuclide ionising radiation impact in all investigated cases were lower than the ERICA screening dose rate value of 10 μGy/h. The main exposure of reference organisms as a result of Ignalina NPP former effluent to Lake Druksiai is due to ionizing radiation of radionuclides (60)Co and (137)Cs, of predicted releases to Lake Druksiai during initial decommissioning period - due to radionuclides (60)Co, (134)Cs and (137)Cs, and as a result of predicted releases to Lake Druksiai from low- and intermediate-level short-lived radioactive waste disposal site in 30-100 year period - due to radionuclides (99)Tc and (3)H. The risk quotient expected values in all investigated cases were <1, and therefore the risk to non-human biota can be considered negligible with the exception of a conservative risk quotient for insect larvae. Radiological protection of non-human biota in Lake Druksiai, the Ignalina NPP cooling pond, is both feasible and acceptable. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. The effects of freshwater inflow, inlet conveyance and sea level rise on the salinity regime in the Loxahatchee Estuary

    International Nuclear Information System (INIS)

    Hu, G.

    2002-01-01

    The upstream migration of salt water into the historic freshwater reaches of the Loxahatchee River is the likely cause of the altered floodplain cypress forest community along the Northwest Fork and some of its tributaries. Mangroves are replacing cypress forest and areas of mixed swamp hardwoods have reacted to different degrees to the saltwater stress. A hydrodynamic/salinity model was developed to study the influence of freshwater input, tidal inlet deepening and sea level rise on the salinity regime in the estuary. Field data analysis and model simulations indicate that the salinity condition in the estuary is sensitive to the amount of freshwater input from the watershed. During dry seasons the salt front advances into areas that were historically freshwater habitats. Historic evidence indicates that the Loxahatchee estuary was periodically closed and opened to the sea. Due to the active long shore sediment transport, the tidal inlet was probably characterized by shifting sandbars through which ran a narrow and unstable channel. Inlet dredging in the past several decades has increased the hydraulic conveyance of the inlet and the tidal influence into the estuary. The sea level record from a site in south Florida indicates that the sea level has been rising at a rate of approximately 2.3-mm per year. The rise of sea level in the past century has probably raised the mean tide level by about 23 centimeters. If the sea level rise continues as predicted, it is foreseeable that the salt front will move further upstream along with the sea level rise. Field data analysis and the preliminary model output led us to believe that the advance of seawater up the estuary is the combined effect of watershed hydrological changes, inlet deepening and sea level rise. (author)

  8. Exploring Freshwater Science

    Indian Academy of Sciences (India)

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

  9. A critical examination of the possible application of zinc stable isotope ratios in bivalve mollusks and suspended particulate matter to trace zinc pollution in a tropical estuary.

    Science.gov (United States)

    Araújo, Daniel; Machado, Wilson; Weiss, Dominik; Mulholland, Daniel S; Boaventura, Geraldo R; Viers, Jerome; Garnier, Jeremie; Dantas, Elton L; Babinski, Marly

    2017-07-01

    The application of zinc (Zn) isotopes in bivalve tissues to identify zinc sources in estuaries was critically assessed. We determined the zinc isotope composition of mollusks (Crassostrea brasiliana and Perna perna) and suspended particulate matter (SPM) in a tropical estuary (Sepetiba Bay, Brazil) historically impacted by metallurgical activities. The zinc isotope systematics of the SPM was in line with mixing of zinc derived from fluvial material and from metallurgical activities. In contrast, source mixing alone cannot account for the isotope ratios observed in the bivalves, which are significantly lighter in the contaminated metallurgical zone (δ 66 Zn JMC  = +0.49 ± 0.06‰, 2σ, n = 3) compared to sampling locations outside (δ 66 Zn JMC  = +0.83 ± 0.10‰, 2σ, n = 22). This observation suggests that additional factors such as speciation, bioavailability and bioaccumulation pathways (via solution or particulate matter) influence the zinc isotope composition of bivalves. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. 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.

  11. Preliminary Results on the Evaluation of the Occurrence of Tetrodotoxin Associated to Marine Vibrio spp. in Bivalves from the Galician Rias (Northwest of Spain

    Directory of Open Access Journals (Sweden)

    Jose Manuel Leão

    2018-03-01

    Full Text Available Tetrodotoxins (TTX are a potent group of natural neurotoxins putatively produced by symbiotic microorganisms and affecting the aquatic environment. These neurotoxins have been recently found in some species of bivalves and gastropods along the European Coasts (Greece, UK, and The Netherlands linked to the presence of high concentrations of Vibrio, in particular Vibrio parahaemolyticus. This study is focused on the evaluation of the presence of Vibrio species and TTX in bivalves (mussels, oysters, cockles, clams, scallops, and razor clams from Galician Rias (northwest of Spain. The detection and isolation of the major Vibrio spp. and other enterobacterial populations have been carried out with the aim of screening for the presence of the pathways genes, poliketide synthase (PKS and non-ribosomal peptide synthetase (NRPS possibly involved in the biosynthesis of these toxins. Samples containing Vibrio spp. were analyzed by biochemical (API20E-galery and genetic tests (PCR-RT. These samples were then screened for TTX toxicity by a neuroblastoma cell-based assay (N2a and the presence of TTX was further confirmed by LC-MS/MS. TTX was detected in two infaunal samples. This is the first confirmation of the presence of TTX in bivalve molluscs from the Galician Rias.

  12. Traces (ichnospecies Oichnus paraboloides of predatory gastropods on bivalve shells from the Seogwipo Formation, Jejudo, Korea

    Directory of Open Access Journals (Sweden)

    Dal-Yong Kong

    2015-12-01

    Full Text Available Circular to subcircular drill holes were identified on the bivalve shells collected from the Seogwipo Formation, Jejudo, Korea. A great majority of the drill holes (>70% were found on the surfaces of a bivalve species Glycymeris rotunda. They are characterized by a beveled sharp edge and paraboloid in cross section with larger outer borehole diameter (OBD; mean 4.21 mm and smaller inner borehole diameter (mean 2.94 mm. Walls of the drill holes are generally smooth, and walls ornamented with etched relief-like structures were also recognized. A slightly raised central boss observed in an incomplete specimen may indicate a failure of predator’s attack. All drill holes collected are classified as a single ichnospecies Oichnus paraboloides Bromley, 1981. They are interpreted as boring traces produced by predatory gastropods, particularly naticid gastropods. Most O. paraboloides boreholes are observed in the central area of shell surfaces; a few boreholes lie marginally, which may reflect a borehole-site selectivity. No correlation between size of prey (shell height and size of predator (OBD is recognized. It is likely, however, that drilled shells of about 30 mm in height represent optimal prey size for naticid predators that lived in a benthic Seogwipo community.

  13. Immunotoxicity of nanoparticle nTiO2 to a commercial marine bivalve species, Tegillarca granosa.

    Science.gov (United States)

    Shi, Wei; Han, Yu; Guo, Cheng; Zhao, Xinguo; Liu, Saixi; Su, Wenhao; Zha, Shanjie; Wang, Yichen; Liu, Guangxu

    2017-07-01

    The increasing production and extensive application of nanoparticles (NPs) inevitably leads to increased release of NPs into the marine environment and therefore poses a potential threat to marine organisms, especially the sessile benthic bivalves. However, the impacts of NPs on the immunity of commercial and ecological important bivalve species, Tegillarca granosa, still remain unknown to date. In addition, the molecular mechanism of the immunotoxicity of NPs still remains unclear in marine invertebrates. Therefore, the immunotoxicity of nTiO 2 exposure to T. granosa at environmental realistic concentrations was investigated in the present study. Results obtained showed that the total number, phagocytic activity, and red granulocytes ratio of the haemocytes were significantly reduced after 30 days nTiO 2 exposures at the concentrations of 10 and 100 μg/L. Furthermore, the expressions of genes encoding Pattern Recognition Receptors (PPRs) and downstream immune-related molecules were significantly down-regulated by nTiO 2 exposures, indicating a reduced sensitivity to pathogen challenges. In conclusion, evident immunotoxicity of nTiO 2 to T. granosa at environmental realistic concentrations was detected by the present study. In addition, the gene expression analysis suggests that the PRRs (both TLRs and RIG1 investigated) may be the molecules for NPs recognition in marine invertebrates. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Evaluating the provenance of fine sediment in degraded Freshwater Pearl Mussel habitats.

    Science.gov (United States)

    Blake, Will; Haley, Steve; Goddard, Rupert; Stone, Peter; Broadhead, Kat

    2015-04-01

    Freshwater Pearl Mussels (FWPM), Margaritifera margaritifera, are among the most critically threatened freshwater bivalves worldwide. In addition to their important roles in particle processing, nutrient release, and sediment mixing, they also serve as an ideal target species for evaluation of aquatic ecosystem functioning especially in the context of their symbiotic relationship with Atlantic salmon Salmo salar and brown or sea trout Salmo trutta. Poor water quality, particularly eutrophication, and siltation are considered major contributory factors in the decline of the species hence management of diffuse water pollution from agriculture (DWPA) is a key priority in catchments that host FWPM habitats. Against this background, this study adopted a combined monitoring, surveying and sediment fingerprinting approach to determine the principal sources of fine sediment impacting FWPM habitats in the River Clun, a Special area of Conservation (SAC) for FWPMs in central western UK. Potential sediment production hotspot areas in the ca 200 km2 catchment area upstream of FWPM habitats were initially evaluated using the SCIMAP risk mapping tool. Suspended sediment monitoring was undertaken on the main stem channel where FWPM habitats are located and wet weather catchment walkover surveys undertaken along the upstream river and stream network. Within this monitoring framework, sediment fingerprinting was undertaken at two levels. The first level aimed to link primary catchment sources (cultivated and uncultivated soil, channel bank erosion, and material transported via roads and tracks) to suspended sediment output from each main tributary upstream of the FWPM beds. The second level linked silt in the FWMP beds to the main tributaries, as integrated source end-members, with the inclusion of main channel bank erosion, a notable feature of walkover surveys as an additional source. Geochemical fingerprints, determined by XRF spectroscopy, were dominated by conservative mineral

  15. Abnormalities in bivalve larvae from the Puck Bay (Gulf of Gdansk, southern Baltic Sea) as an indicator of environmental pollution.

    Science.gov (United States)

    Lasota, Rafal; Gierszewska, Katarzyna; Viard, Frédérique; Wolowicz, Maciej; Dobrzyn, Katarzyna; Comtet, Thierry

    2018-01-01

    This study described the occurrence of abnormalities in bivalve larvae from the Puck Bay. Analyses of plankton samples collected in 2012-2013 showed that larval Mytilus trossulus, Mya arenaria, and Cerastoderma glaucum exhibited abnormalities that could indicate adverse environmental impacts. The deformities were mainly in shells, but missing soft tissue fragments and protruding vela were also noted. In addition to larval studies, we analyzed benthic postlarvae of Mytilus trossulus. Interestingly, grooves and notches at different locations of the prodissoconch, dissoconch, and shell margin were observed. Some of these deformations were reminiscent of the indentations found on the shell edge of larvae. Comparing the proportion of abnormal postlarvae to larvae with shell abnormalities suggested that the survival of larvae with shell abnormalities was low. Overall, our results suggested that the ratio of abnormal bivalve larvae could be used as an indicator of the biological effects of hazardous substances in the pelagic environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Transgenerational exposure of North Atlantic bivalves to ocean acidification renders offspring more vulnerable to low pH and additional stressors.

    Science.gov (United States)

    Griffith, Andrew W; Gobler, Christopher J

    2017-09-12

    While early life-stage marine bivalves are vulnerable to ocean acidification, effects over successive generations are poorly characterized. The objective of this work was to assess the transgenerational effects of ocean acidification on two species of North Atlantic bivalve shellfish, Mercenaria mercenaria and Argopecten irradians. Adults of both species were subjected to high and low pCO 2 conditions during gametogenesis. Resultant larvae were exposed to low and ambient pH conditions in addition to multiple, additional stressors including thermal stress, food-limitation, and exposure to a harmful alga. There were no indications of transgenerational acclimation to ocean acidification during experiments. Offspring of elevated pCO 2 -treatment adults were significantly more vulnerable to acidification as well as the additional stressors. Our results suggest that clams and scallops are unlikely to acclimate to ocean acidification over short time scales and that as coastal oceans continue to acidify, negative effects on these populations may become compounded and more severe.

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

    NARCIS (Netherlands)

    Pauw, P.S.

    2015-01-01

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

  18. Predicting freshwater habitat integrity using land-use surrogates

    CSIR Research Space (South Africa)

    Amis, MA

    2007-04-01

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

  19. Impact of seawater carbonate chemistry on the calcification of marine bivalves

    Science.gov (United States)

    Thomsen, J.; Haynert, K.; Wegner, K. M.; Melzner, F.

    2015-07-01

    Bivalve calcification, particularly of the early larval stages, is highly sensitive to the change in ocean carbonate chemistry resulting from atmospheric CO2 uptake. Earlier studies suggested that declining seawater [CO32-] and thereby lowered carbonate saturation affect shell production. However, disturbances of physiological processes such as acid-base regulation by adverse seawater pCO2 and pH can affect calcification in a secondary fashion. In order to determine the exact carbonate system component by which growth and calcification are affected it is necessary to utilize more complex carbonate chemistry manipulations. As single factors, pCO2 had no effects and [HCO3-] and pH had only limited effects on shell growth, while lowered [CO32-] strongly impacted calcification. Dissolved inorganic carbon (CT) limiting conditions led to strong reductions in calcification, despite high [CO32-], indicating that [HCO3-] rather than [CO32-] is the inorganic carbon source utilized for calcification by mytilid mussels. However, as the ratio [HCO3-] / [H+] is linearly correlated with [CO32-] it is not possible to differentiate between these under natural seawater conditions. An equivalent of about 80 μmol kg-1 [CO32-] is required to saturate inorganic carbon supply for calcification in bivalves. Below this threshold biomineralization rates rapidly decline. A comparison of literature data available for larvae and juvenile mussels and oysters originating from habitats differing substantially with respect to prevailing carbonate chemistry conditions revealed similar response curves. This suggests that the mechanisms which determine sensitivity of calcification in this group are highly conserved. The higher sensitivity of larval calcification seems to primarily result from the much higher relative calcification rates in early life stages. In order to reveal and understand the mechanisms that limit or facilitate adaptation to future ocean acidification, it is necessary to better

  20. Bivalves: From individual to population modelling

    Science.gov (United States)

    Saraiva, S.; van der Meer, J.; Kooijman, S. A. L. M.; Ruardij, P.

    2014-11-01

    An individual based population model for bivalves was designed, built and tested in a 0D approach, to simulate the population dynamics of a mussel bed located in an intertidal area. The processes at the individual level were simulated following the dynamic energy budget theory, whereas initial egg mortality, background mortality, food competition, and predation (including cannibalism) were additional population processes. Model properties were studied through the analysis of theoretical scenarios and by simulation of different mortality parameter combinations in a realistic setup, imposing environmental measurements. Realistic criteria were applied to narrow down the possible combination of parameter values. Field observations obtained in the long-term and multi-station monitoring program were compared with the model scenarios. The realistically selected modeling scenarios were able to reproduce reasonably the timing of some peaks in the individual abundances in the mussel bed and its size distribution but the number of individuals was not well predicted. The results suggest that the mortality in the early life stages (egg and larvae) plays an important role in population dynamics, either by initial egg mortality, larvae dispersion, settlement failure or shrimp predation. Future steps include the coupling of the population model with a hydrodynamic and biogeochemical model to improve the simulation of egg/larvae dispersion, settlement probability, food transport and also to simulate the feedback of the organisms' activity on the water column properties, which will result in an improvement of the food quantity and quality characterization.

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

    Science.gov (United States)

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

    2010-06-30

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

  2. length-weight relationhip of freshwater wild fish species

    African Journals Online (AJOL)

    Dr Naeem

    2012-06-21

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

  3. Polychlorinated biphenyls, organochlorine pesticides and polycyclic aromatic hydrocarbons in a one-off global survey of bivalves

    DEFF Research Database (Denmark)

    Vorkamp, Katrin; Strand, Jakob; Christensen, Jan H.

    2010-01-01

    During the Danish Galathea 3 expedition, bivalve samples were collected at the Faroe Islands, Greenland, Ghana, South Africa, Australia, Solomon Islands, New Zealand, Chile, US Virgin Islands, Boston, Newfoundland and Shetland Islands and analysed for organochlorines and PAHs. Concentration...... in terms of PCB and PAH levels, while other Greenland samples came closest to representing PAH background levels. Several locations had undetectable organochlorine levels, including Hobart and Chile, which had the lowest Sigma PAH concentrations (group the stations...

  4. Uptake and loss of 134Cs and 60Co by the Baltic bivalve Macoma Baltica under laboratory conditions

    International Nuclear Information System (INIS)

    Evans, S.

    1982-01-01

    In order to predict the radiological impact on man via harvestable sea food products, it is essential to make a critical evaluation of the transfer routes and the rates on which radionuclides are transferred through the aquatic food chains. In the Baltic, the bivalve Macoma Baltica comprises a main food item for fish species of commercial interest, such as flounder. The accumulation and release of Cs-134 and Co-60 by Macoma was experimentally investigated. The nuclides were added to the water and the activity content of the bivalves was determined at regular intervals. The uptake was quite rapid, 40 per cent (Cs) and 55 per cent (Co) respectively of the final steady state was obtained after 24 hours. The subsequent release was rapid as well, 50 per cent (Cs) and 40 per cent (Co) respectively of the accumulated activity was lost within 6 days. The experiments demonstrated that the major intake route following short-term releases of activity will be from the water column. The close connection between activity in water and organism can thus be used for predictive purposes without the complication of radionuclide uptake from contaminated sediments. (Author)

  5. The freshwater biodegradation potential of nine Alaskan oils

    International Nuclear Information System (INIS)

    Blenkinsopp, S.; Segy, G.

    1997-01-01

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

  6. 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....

  7. Late Devonian (Frasnian) bivalves from the Nocedo Formation: the results of Wilhelm Kegel’s 1927 field trip to northern Spain

    NARCIS (Netherlands)

    Amler, M.R.W.

    2010-01-01

    During a field trip to the Peña-Corada Unit of the southernmost Esla region of the Cantabrian Mountains in 1927, the German stratigrapher Wilhelm Kegel sampled brachiopods and bivalves from a section in the Laoz valley near La Ercina. The stratigraphic position is believed to be part of the Nocedo

  8. Distribution and density of the bivalve Anomalocardia brasiliana in the estuarine region of Northeastern Brazil

    Directory of Open Access Journals (Sweden)

    A. M. L. Rodrigues Maia

    2017-06-01

    Full Text Available Abstract The objective of this study was to analyze the density and distribution of the bivalve Anomalocardia brasiliana in beaches in the estuarine region of the semiarid in Rio Grande do Norte State, Barra and Pernambuquinho (04°56.978’S and 37°08.961’W and 04°56.792’S and 37°09.375’W, respectively. Samples were collected monthly during 37 months using five transects (300 m long and 400 m apart laid perpendicularly to the beach line toward the sea. Seven collection points, 50 m apart, were set in each transect, and shellfish and sediment samples were collected. Temperature and salinity were measured in each transect. The results showed a temperature variation of average values of 3 °C; the greatest variation (33.2 °C was observed in May of 2009. The lowest average salinity values were observed between April and June of 2009 (5, 8.7, and 7.8, respectively. This fact was due to an atypical rainfall in the region, which resulted in a large freshwater inflow into the estuary; the average salinity values were about 40 in the remaining months. The highest precipitation values were observed in April/09, April/10, and April/11; the highest precipitation occurred in April/09 (316.3 mm. The lower average densities of A. brasiliana were observed in April and May/09 when compared to the other months; the lowest value was observed in April/09 (26 ind/m2. The highest densities occurred between November/10 and July/11, with values ranging from 70 to 322 ind/m2. The highest inflow of young individuals (lengths from 2 to 5 mm was observed between April and June of 2010 and on September/10 while the highest frequency of adults (from 20 to 25 mm occurred between December of 2010 and April of 2011. Hence, the results of this study show that in the months with the greatest rainfall, salinity and the average density of A. brasiliana showed the lowest values.

  9. Study on polychlorobiphenyl serum levels in French consumers of freshwater fish

    International Nuclear Information System (INIS)

    Desvignes, Virginie; Volatier, Jean-Luc; Bels, Frédéric de; Zeghnoun, Abdelkrim; Favrot, Marie-Christine; Marchand, Philippe; Le Bizec, Bruno; Rivière, Gilles; Leblanc, Jean-Charles; Merlo, Mathilde

    2015-01-01

    Introduction: Polychlorobiphenyls (PCBs) are persistent pollutants that are widespread in the environment and in foodstuffs, particularly in freshwater fish, which frequently exceed the maximum levels set by European regulations. Objectives: First, we describe the consumption of freshwater fish and serum PCB levels in French anglers, a population expected to have the highest level of dietary PCB exposure. Second, we investigated whether there is a statistical relationship between serum PCB levels and the angler consumption of freshwater fish with high PCB bioaccumulation potential (PCB-BP + freshwater fish) in order to make recommendations with regard to safe consumption of freshwater fish. Methods: We conducted a survey of anglers from six sites with contrasting PCB contamination levels. The survey included a food consumption frequency questionnaire and blood samples were taken to assess serum PCB levels. We used a regression model to determine the main factors contributing to serum PCB levels. Results: Consumption of PCB-BP + freshwater fish was relatively infrequent. Serum PCB levels of the study population and of women of childbearing age were in the same range as those observed in the French population and in neighbouring European countries, but higher than in the North American population. The two factors with the highest positive association with serum PCB levels were age (R 2 = 61%) and the consumption of PCB-BP + freshwater fish (R 2 = 2%). Using the regression model, we calculated, for several scenarios depending on the age and gender of the population, the maximum annual frequencies for PCB-BP + freshwater fish consumption that do not exceed the critical body burden threshold. Conclusion: Following the results of this study, the French agency for food, environmental and occupational health and safety (ANSES) issued an opinion and recommended some specific maximum freshwater fish consumption frequencies to protect the French general population

  10. Study on polychlorobiphenyl serum levels in French consumers of freshwater fish

    Energy Technology Data Exchange (ETDEWEB)

    Desvignes, Virginie, E-mail: virginie.desvignes@anses.fr [Risk Assessment Department, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), 27–31, avenue du Général Leclerc, Maisons-Alfort, F-94701 (France); Volatier, Jean-Luc [Risk Assessment Department, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), 27–31, avenue du Général Leclerc, Maisons-Alfort, F-94701 (France); Bels, Frédéric de [Division for Public Health and Care, French National Cancer Institute (INCa), 52, avenue André Morizet, Boulogne Billancourt Cedex, F-92513 (France); Zeghnoun, Abdelkrim [Department of Environmental Health, French Institute for Public Health Surveillance (InVS), 12, rue du Val d' Osne, Saint-Maurice, F-94415 (France); Favrot, Marie-Christine [Ministry of Health, 14, avenue Duquesne, Paris, F-75350 (France); Marchand, Philippe; Le Bizec, Bruno [LUNAM Université, Oniris, Laboratoire d' Etude des Résidus et Contaminants dans les Aliments (LABERCA), USC INRA 1329, Nantes, F-44307 (France); Rivière, Gilles; Leblanc, Jean-Charles; Merlo, Mathilde [Risk Assessment Department, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), 27–31, avenue du Général Leclerc, Maisons-Alfort, F-94701 (France)

    2015-02-01

    Introduction: Polychlorobiphenyls (PCBs) are persistent pollutants that are widespread in the environment and in foodstuffs, particularly in freshwater fish, which frequently exceed the maximum levels set by European regulations. Objectives: First, we describe the consumption of freshwater fish and serum PCB levels in French anglers, a population expected to have the highest level of dietary PCB exposure. Second, we investigated whether there is a statistical relationship between serum PCB levels and the angler consumption of freshwater fish with high PCB bioaccumulation potential (PCB-BP{sup +} freshwater fish) in order to make recommendations with regard to safe consumption of freshwater fish. Methods: We conducted a survey of anglers from six sites with contrasting PCB contamination levels. The survey included a food consumption frequency questionnaire and blood samples were taken to assess serum PCB levels. We used a regression model to determine the main factors contributing to serum PCB levels. Results: Consumption of PCB-BP{sup +} freshwater fish was relatively infrequent. Serum PCB levels of the study population and of women of childbearing age were in the same range as those observed in the French population and in neighbouring European countries, but higher than in the North American population. The two factors with the highest positive association with serum PCB levels were age (R{sup 2} = 61%) and the consumption of PCB-BP{sup +} freshwater fish (R{sup 2} = 2%). Using the regression model, we calculated, for several scenarios depending on the age and gender of the population, the maximum annual frequencies for PCB-BP{sup +} freshwater fish consumption that do not exceed the critical body burden threshold. Conclusion: Following the results of this study, the French agency for food, environmental and occupational health and safety (ANSES) issued an opinion and recommended some specific maximum freshwater fish consumption frequencies to protect the French

  11. Assessment of bioavailability of weathered oil residues using caged bivalves (Crassostrea gigas and Mytilus edulis) as indicator organisms

    International Nuclear Information System (INIS)

    Bleczinski, C.F.; Costa, H.J.; Rigatti, M.J.; Wong, M.C.; Boehm, P.D.

    1993-01-01

    In April 1988, an estimated 400,000 gallons of San Joaquin Valley crude oil spilled into Peyton Slough and subsequently into Suisun Bay from an oil refinery in Martinez, California. The crude oil initially impacted a number of ecologically sensitive environments including estuarine water, marsh grasses, marsh and shoreline sediment, and intertidal sediment. A four-year oil weathering study was performed to determine the concentrations of environmentally important compounds in the stranded oil, to monitor changes in these concentrations over time, and to assess the potential long-term impact of the spilled oil in these various environments. As a result of marked differences in the rate of weathering at the different sites, a bioaccumulation component was added to the original study design in order to assess the bioavailability of crude oil residues remaining four-years post spill. Caged bivalves (Crassostrea gigas and Mytilus edulis) were deployed at the three study sites as sentinel organisms and exposed for three months. Sediments and organism tissues were analyzed using gas chromatography/mass spectrometry for polynuclear aromatic hydrocarbon (PAH) assemblages characteristics of the spilled oil. Advanced hydrocarbon fingerprinting techniques (e.g., double ratio plots of characteristic alkyl PAHs) were used to match distributions in the organisms and in the study site sediments

  12. Changing Arctic Ocean freshwater pathways.

    Science.gov (United States)

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

    2012-01-04

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

  13. Meeting the challenge of interacting threats in freshwater ecosystems: A call to scientists and managers

    Directory of Open Access Journals (Sweden)

    Laura S. Craig

    2017-12-01

    Full Text Available Human activities create threats that have consequences for freshwater ecosystems and, in most watersheds, observed ecological responses are the result of complex interactions among multiple threats and their associated ecological alterations. Here we discuss the value of considering multiple threats in research and management, offer suggestions for filling knowledge gaps, and provide guidance for addressing the urgent management challenges posed by multiple threats in freshwater ecosystems. There is a growing literature assessing responses to multiple alterations, and we build off this background to identify three areas that require greater attention: linking observed alterations to threats, understanding when and where threats overlap, and choosing metrics that best quantify the effects of multiple threats. Advancing science in these areas will help us understand existing ecosystem conditions and predict future risk from multiple threats. Because addressing the complex issues and novel ecosystems that arise from the interaction of multiple threats in freshwater ecosystems represents a significant management challenge, and the risks of management failure include loss of biodiversity, ecological goods, and ecosystem services, we also identify actions that could improve decision-making and management outcomes. These actions include drawing insights from management of individual threats, using threat attributes (e.g., causes and spatio-temporal dynamics to identify suitable management approaches, testing management strategies that are likely to be successful despite uncertainties about the nature of interactions among threats, avoiding unintended consequences, and maximizing conservation benefits. We also acknowledge the broadly applicable challenges of decision-making within a socio-political and economic framework, and suggest that multidisciplinary teams will be needed to innovate solutions to meet the current and future challenge of interacting

  14. Meeting the challenge of interacting threats in freshwater ecosystems: A call to scientists and managers

    Science.gov (United States)

    Craig, Laura S.; Olden, Julian D.; Arthington, Angela; Entrekin, Sally; Hawkins, Charles P.; Kelly, John J.; Kennedy, Theodore A.; Maitland, Bryan M.; Rosi, Emma J.; Roy, Allison; Strayer, David L.; Tank, Jennifer L.; West, Amie O.; Wooten, Matthew S.

    2017-01-01

    Human activities create threats that have consequences for freshwater ecosystems and, in most watersheds, observed ecological responses are the result of complex interactions among multiple threats and their associated ecological alterations. Here we discuss the value of considering multiple threats in research and management, offer suggestions for filling knowledge gaps, and provide guidance for addressing the urgent management challenges posed by multiple threats in freshwater ecosystems. There is a growing literature assessing responses to multiple alterations, and we build off this background to identify three areas that require greater attention: linking observed alterations to threats, understanding when and where threats overlap, and choosing metrics that best quantify the effects of multiple threats. Advancing science in these areas will help us understand existing ecosystem conditions and predict future risk from multiple threats. Because addressing the complex issues and novel ecosystems that arise from the interaction of multiple threats in freshwater ecosystems represents a significant management challenge, and the risks of management failure include loss of biodiversity, ecological goods, and ecosystem services, we also identify actions that could improve decision-making and management outcomes. These actions include drawing insights from management of individual threats, using threat attributes (e.g., causes and spatio-temporal dynamics) to identify suitable management approaches, testing management strategies that are likely to be successful despite uncertainties about the nature of interactions among threats, avoiding unintended consequences, and maximizing conservation benefits. We also acknowledge the broadly applicable challenges of decision-making within a socio-political and economic framework, and suggest that multidisciplinary teams will be needed to innovate solutions to meet the current and future challenge of interacting threats in

  15. Physiological effects of hypercapnia in the deep-sea bivalve Acesta excavata (Fabricius, 1779) (Bivalvia; Limidae)

    DEFF Research Database (Denmark)

    Hammer, Karen M.; Kristiansen, Erlend; Zachariassen, Karl Erik

    2011-01-01

    The option of storing CO(2) in subsea rock formations to mitigate future increases in atmospheric CO(2) may induce problems for animals in the deep sea. In the present study the deep-sea bivalve Acesta excavata was subjected to environmental hypercapnia (pHSW 6.35, P(CO2), =33,000 mu atm...... extracellular pH remained significantly lower during recovery. Intracellular non-bicarbonate buffering capacity of the posterior adductor muscle of hypercapnic animals was significantly lower than control values, but this was not the case for the remaining tissues analyzed. Oxygen consumption initially dropped...

  16. Interactive effects of pH and metals on mitochondrial functions of intertidal bivalves Crassostrea virginica and Mercenaria mercenaria

    International Nuclear Information System (INIS)

    Ivanina, Anna V.; Sokolova, Inna M.

    2013-01-01

    Highlights: •Interactive effects of trace metals Cd and Cu and pH were studied in mitochondria of clams and oysters. •Mitochondrial respiration and membrane potential of bivalves were robust to pH variation (6.6–7.8). •Elevated levels of Cd and Cu inhibited mitochondrial respiration in the pH-dependent manner but did not affect the membrane potential. •Negative effects of Cd and Cd on mitochondrial respiration were alleviated at low pH (7.0 and below). •Moderate acidosis may protect molluscan mitochondria from metal toxicity. -- Abstract: Intertidal bivalves experience broad fluctuations of environmental temperature, pH and oxygen content which could change their intracellular pH. They are also exposed to trace metals such as cadmium (Cd) and copper (Cu) that accumulate in their tissues and may negatively affect mitochondrial functions and bioenergetics. We determined the interactive effects of pH and trace metals (25 μM Cd or Cu) on mitochondrial functions (including respiration and membrane potentials in both ADP-stimulated (state 3) and resting (state 4) states) of two common marine bivalves, the hard clams (Mercenaria mercenaria) and eastern oysters (Crassostrea virginica). In the absence of the trace metals, mitochondrial functions of C. virginica and M. mercenaria were insensitive to pH in a broad physiologically relevant range (6.6–7.8). Mitochondrial respiration was generally suppressed by 25 μM Cd or Cu (with the stronger effects observed for ADP-stimulated compared to the resting respiration) while the mitochondrial membrane potential was unaffected. pH modulated the effects of Cu and Cd on mitochondrial respiration of the bivalves. In oysters, Cu suppressed ADP-stimulated mitochondrial respiration at high and low pH values (6.6 and 7.8, respectively), but had no effect in the intermediate pH range (7.0–7.4). In clams, the negative effect of Cu on ADP-stimulated respiration was only observed at extremely high pH (7.8). A decrease in p

  17. Interactive effects of pH and metals on mitochondrial functions of intertidal bivalves Crassostrea virginica and Mercenaria mercenaria

    Energy Technology Data Exchange (ETDEWEB)

    Ivanina, Anna V.; Sokolova, Inna M., E-mail: isokolov@uncc.edu

    2013-11-15

    Highlights: •Interactive effects of trace metals Cd and Cu and pH were studied in mitochondria of clams and oysters. •Mitochondrial respiration and membrane potential of bivalves were robust to pH variation (6.6–7.8). •Elevated levels of Cd and Cu inhibited mitochondrial respiration in the pH-dependent manner but did not affect the membrane potential. •Negative effects of Cd and Cd on mitochondrial respiration were alleviated at low pH (7.0 and below). •Moderate acidosis may protect molluscan mitochondria from metal toxicity. -- Abstract: Intertidal bivalves experience broad fluctuations of environmental temperature, pH and oxygen content which could change their intracellular pH. They are also exposed to trace metals such as cadmium (Cd) and copper (Cu) that accumulate in their tissues and may negatively affect mitochondrial functions and bioenergetics. We determined the interactive effects of pH and trace metals (25 μM Cd or Cu) on mitochondrial functions (including respiration and membrane potentials in both ADP-stimulated (state 3) and resting (state 4) states) of two common marine bivalves, the hard clams (Mercenaria mercenaria) and eastern oysters (Crassostrea virginica). In the absence of the trace metals, mitochondrial functions of C. virginica and M. mercenaria were insensitive to pH in a broad physiologically relevant range (6.6–7.8). Mitochondrial respiration was generally suppressed by 25 μM Cd or Cu (with the stronger effects observed for ADP-stimulated compared to the resting respiration) while the mitochondrial membrane potential was unaffected. pH modulated the effects of Cu and Cd on mitochondrial respiration of the bivalves. In oysters, Cu suppressed ADP-stimulated mitochondrial respiration at high and low pH values (6.6 and 7.8, respectively), but had no effect in the intermediate pH range (7.0–7.4). In clams, the negative effect of Cu on ADP-stimulated respiration was only observed at extremely high pH (7.8). A decrease in p

  18. 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:

  19. 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

  20. Fauna Europaea: Mollusca – Bivalvia

    Directory of Open Access Journals (Sweden)

    Rafael Araujo

    2015-07-01

    European freshwater bivalves belong to the Orders Unionoida and Cardiida. All the European unionoids are included in the superfamily Unionoidea, the freshwater mussels or naiads. The European cardiids belong to the following three superfamilies: Cardioidea, Cyrenoidea and Dreissenoidea. Among the Unionoidea there are the most imperilled animal groups on the planet while the Cardioidea includes the cosmopolitan genus Pisidium, the Cyrenoidea the Asiatic clam (Corbicula fluminea and the Dreissenoidea the famous invasive zebra mussel (Dreissena polymorpha. Basic information is summarized on their taxonomy and biology. Tabulations include a complete list of the current estimated families, genera and species.

  1. Vulnerability of European freshwater catchments to climate change.

    Science.gov (United States)

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

    2017-09-01

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

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

    Science.gov (United States)

    Anthony, S.S.

    1992-01-01

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

  3. Predicting freshwater habitat integrity using land-use surrogates

    African Journals Online (AJOL)

    2007-04-02

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

  4. A Synopsis of Global Mapping of Freshwater Habitats and Biodiversity: Implications for Conservation

    Energy Technology Data Exchange (ETDEWEB)

    McManamay, Ryan A. [ORNL; Griffiths, Natalie A. [ORNL; DeRolph, Christopher R. [ORNL; Pracheil, Brenda M. [ORNL

    2018-01-01

    Accurately mapping freshwater habitats and biodiversity at high-resolutions across the globe is essential for assessing the vulnerability and threats to freshwater organisms and prioritizing conservation efforts. Since the 2000s, extensive efforts have been devoted to mapping global freshwater habitats (rivers, lakes, and wetlands), the spatial representation of which has changed dramatically over time with new geospatial data products and improved remote sensing technologies. Some of these mapping efforts, however, are still coarse representations of actual conditions. Likewise, the resolution and scope of global freshwater biodiversity compilation efforts have also increased, but are yet to mirror the spatial resolution and fidelity of mapped freshwater environments. In our synopsis, we find that efforts to map freshwater habitats have been conducted independently of those for freshwater biodiversity; subsequently, there is little congruence in the spatial representation and resolution of the two efforts. We suggest that global species distribution models are needed to fill this information gap; however, limiting data on habitat characteristics at scales that complement freshwater habitats has prohibited global high-resolution biogeography efforts. Emerging research trends, such as mapping habitat alteration in freshwater ecosystems and trait biogeography, show great promise in mechanistically linking global anthropogenic stressors to freshwater biodiversity decline and extinction risk.

  5. Community structure and decadal changes in macrozoobenthic assemblages in Lake Poyang, the largest freshwater lake in China

    Directory of Open Access Journals (Sweden)

    Cai Y. J.

    2014-01-01

    Full Text Available Lake Poyang is the largest freshwater lake in China and contains unique and diverse biota within the Yangtze floodplain ecosystem. However, knowledge of its macrozoobenthic assemblages remains inadequate. To characterize the current community structure of these assemblages and to portray their decadal changes, quarterly investigations were conducted at 15 sites from February to November 2012. A total of 42 taxa were recorded, and Corbicula fluminea, Limnoperna fortunei, Gammaridae sp., Nephtys polybranchia, Polypedilum scalaenum and Branchiura sowerbyi were found to dominate the community in terms of abundance. The bivalves Corbicula fluminea, Lamprotula rochechouarti, Arconaia lanceolata and Lamprotula caveata dominated the community in biomass due to their large body size. The mean abundance of the total macrozoobenthos varied from 48 to 920 ind·m-2, the mean biomass ranged from 28 to 428 g·m-2. The substrate type affected strongly the abundance, biomass, and diversity of the macrozoobenthos, with muddy sand substrates showing the highest values. Compared with historical data, remarkable changes were observed in the abundance of macrozoobenthos and the identity of the dominant species. The mean total abundance decreased from 724 ind·m-2 in 1992 to 228 ind·m-2 in 2012. The dominant species have shifted dramatically. Large unionids were dominant before 1998, whereas pollution-tolerant species (e.g., Branchiura sowerbyi increased in dominance after 2008. Our findings should have implications for the conservation of the benthic biodiversity of this large Yangtze-connected lake.

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

    Science.gov (United States)

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

    2015-04-01

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

  7. 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.

  8. Global impacts of energy demand on the freshwater resources of nations.

    Science.gov (United States)

    Holland, Robert Alan; Scott, Kate A; Flörke, Martina; Brown, Gareth; Ewers, Robert M; Farmer, Elizabeth; Kapos, Valerie; Muggeridge, Ann; Scharlemann, Jörn P W; Taylor, Gail; Barrett, John; Eigenbrod, Felix

    2015-12-01

    The growing geographic disconnect between consumption of goods, the extraction and processing of resources, and the environmental impacts associated with production activities makes it crucial to factor global trade into sustainability assessments. Using an empirically validated environmentally extended global trade model, we examine the relationship between two key resources underpinning economies and human well--being-energy and freshwater. A comparison of three energy sectors (petroleum, gas, and electricity) reveals that freshwater consumption associated with gas and electricity production is largely confined within the territorial boundaries where demand originates. This finding contrasts with petroleum, which exhibits a varying ratio of territorial to international freshwater consumption, depending on the origin of demand. For example, although the United States and China have similar demand associated with the petroleum sector, international freshwater consumption is three times higher for the former than the latter. Based on mapping patterns of freshwater consumption associated with energy sectors at subnational scales, our analysis also reveals concordance between pressure on freshwater resources associated with energy production and freshwater scarcity in a number of river basins globally. These energy-driven pressures on freshwater resources in areas distant from the origin of energy demand complicate the design of policy to ensure security of fresh water and energy supply. Although much of the debate around energy is focused on greenhouse gas emissions, our findings highlight the need to consider the full range of consequences of energy production when designing policy.

  9. 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.

  10. Wnt signaling and polarity in freshwater sponges.

    Science.gov (United States)

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

    2018-02-02

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

  11. Assessing the presence of marine toxins in bivalve molluscs from southwest India.

    Science.gov (United States)

    Turner, Andrew D; Dhanji-Rapkova, Monika; Rowland-Pilgrim, Stephanie; Turner, Lucy M; Rai, Ashwin; Venugopal, Moleyur N; Karunasagar, Indrani; Godhe, Anna

    2017-12-15

    The south west coast of India has been showing a steady increase in shellfish cultivation both for local consumption and fishery export, over recent years. Perna viridis and Crassostrea madrasensis are two species of bivalve molluscs which grow in some selected regions of southern Karnataka, close to the city of Mangalore. In the early 1980s, shellfish consumers in the region were affected by intoxication from Paralytic Shellfish Poison present in local bivalves (clams and oysters) resulting in hospitalisation of many, including one fatality. Since then, there have been no further reports of serious shellfish intoxication and there is little awareness of the risks from natural toxins and no routine monitoring programme in place to protect shellfish consumers. This study presents the findings from the first ever systematic assessment of the presence of marine toxins in mussels and oysters grown in four different shellfish harvesting areas in the region. Shellfish were collected and subjected to analysis for ASP, PSP and lipophilic toxins, as well as a suite of non-EU regulated toxins such as tetrodotoxin and selected cyclic imines. Results revealed the presence of low levels of PSP toxins in oysters throughout the study period. Overall, total toxicities reached a maximum of 10% of the EU regulatory limit of 800 μg STX eq/kg. Toxin profiles were similar to those reported from the 1980 outbreak. No evidence was found for significant levels of ASP and lipophilic toxins, although some cyclic imines were detected, including gymnodimine. The results indicated that the risk to shellfish consumers during this specific study period would have been low. However, with historical evidence for extremely high levels of PSP toxins in molluscs, there is a strong need for routine surveillance of shellfish production areas for marine toxins, in order to mitigate against human health impacts resulting from unexpected harmful algal blooms, with potentially devastating socio

  12. Study on the bioaccumulation of Polonium-210 on bivalve indicator organisms of Tamilnadu and Pondicherry coast (East Coast of India)

    International Nuclear Information System (INIS)

    Syed Mohamed, H.E.; Sadiq Bukhari, A.; Meeramaideen, M.; Masilamani, V.; Shamsudin, Mohamed; Shahul Hameed, P.

    2012-01-01

    210 Po is a major contributor (90%) of the natural radiation dose from alpha-emitting radionuclides, received by most marine organisms. Among marine organisms, benthic fauna are superior to many other biological groups, since they could be monitored due to their sedentary habits and then must either adapt to environmental stress or perish. They also reflect the water conditions not only at the time of sampling but also for some past time as well. The affinity of 210 Po for protein enables it to pass through the food chain, and increased body burdens of 210 Po have been found where diets include protein-rich meat and seafood. The present study was launched to evaluate the rate of accumulation of 210 Po in the benthic bivalve molluscs such as Perna indica, P.viridis, Meretrix casta, Cardium coronatum, Gafrarium tumidum, Paphia textrix, Vellorita cyprinodea and Pinctada sp., of Tamilnadu and Pondicherry coast. Water samples, sediments and bivalves were collected from Gulf of Mannar (6 sampling stations), Palk Strait (8 sampling stations) of Tamilnadu and Pondicherry (6 sampling stations). 210 Po determination as made was as per standard protocols. The results showed that 210 Po concentration in coastal waters of Gulf of Mannar, Palk Strait and Pondicherry ranged 0.5 - 2.83 mBq/l (mean 1.33 mBq/I), 2.14 - 32.14 mBq/l (mean 15.3 mBq/l) and 1.36 - 2.0 mBq/1 (mean 1.59 mBq/1) respectively. The sediments maintained higher level of 210 Po (mean value of 3.62 Bq/kg in Gulf of Mannar, 107.9 Bq/kg in Palk Strait and 3.0 Bq/kg in Pondicherry) than water. The 210 Po rich sediment therefore serves as a vital link in the transfer of Polonium from water to the marine organisms. The concentration of 210 Po in eight species of bivalves collected from the study area, recorded a maximum level ranging from 65.2 to 2668.9 Bq/kg in soft tissues and from 1.19 to 15.3 Bq/kg in shells. The bioaccumulation ability in bivalve species with reference to 210 Po was observed to be highly variable

  13. 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.

  14. Origin and evolutionary history of freshwater Rhodophyta: further insights based on phylogenomic evidence.

    Science.gov (United States)

    Nan, Fangru; Feng, Jia; Lv, Junping; Liu, Qi; Fang, Kunpeng; Gong, Chaoyan; Xie, Shulian

    2017-06-07

    Freshwater representatives of Rhodophyta were sampled and the complete chloroplast and mitochondrial genomes were determined. Characteristics of the chloroplast and mitochondrial genomes were analyzed and phylogenetic relationship of marine and freshwater Rhodophyta were reconstructed based on the organelle genomes. The freshwater member Compsopogon caeruleus was determined for the largest chloroplast genome among multicellular Rhodophyta up to now. Expansion and subsequent reduction of both the genome size and GC content were observed in the Rhodophyta except for the freshwater Compsopogon caeruleus. It was inferred that the freshwater members of Rhodophyta occurred through diverse origins based on evidence of genome size, GC-content, phylogenomic analysis and divergence time estimation. The freshwater species Compsopogon caeruleus and Hildenbrandia rivularis originated and evolved independently at the inland water, whereas the Bangia atropurpurea, Batrachospermum arcuatum and Thorea hispida are derived from the marine relatives. The typical freshwater representatives Thoreales and Batrachospermales are probably derived from the marine relative Palmaria palmata at approximately 415-484 MYA. The origin and evolutionary history of freshwater Rhodophyta needs to be testified with more organelle genome sequences and wider global sampling.

  15. Occurrence of potentially pathogenic Vibrio in oysters (Crassostrea gigas and waters from bivalve mollusk cultivations in the South Bay of Santa Catarina

    Directory of Open Access Journals (Sweden)

    Roberta Juliano Ramos

    2014-06-01

    Full Text Available Introduction This research aimed to identify and quantify potentially pathogenic Vibrio from different cultivations of bivalve shellfish in the State of Santa Catarina, Brazil, and water regions in the South Bay, as well as correlate the incidence of these microorganisms with the physicochemical parameters of marine waters. Methods Between October 2008 and March 2009, 60 oyster and seawater samples were collected from six regions of bivalve mollusk cultivation, and these samples were submitted for Vibrio counts. Results Twenty-nine (48.3% oyster samples were revealed to be contaminated with one or more Vibrio species. The Vibrio parahaemolyticus and Vibrio vulnificus counts in the samples ranged from < 0.5 log10 Most Probable Number (MPN g–1 to 2.3 log10 MPN g–1 oyster and from < 0.5 log10 MPN g–1 to 2.1 log10 MPN g–1 oyster, respectively. Of the 60 seawater samples analyzed, 44 (73.3% showed signs of contamination with one or more vibrio species. The counts of V. parahaemolyticus and V. vulnificus in the samples ranged from < 0.3 log10 MPN·100mL–1 to 1.7 log10MPN·100mL–1 seawater and from < 0.3 log10 MPN·100mL–1 to 2.0 log10 MPN·100mL–1 seawater, respectively. A positive correlation between V. vulnificus counts and the seawater temperature as well as a negative correlation between the V. parahaemolyticus counts and salinity were observed. Conclusions The results suggest the need to implement strategies to prevent vibrio diseases from being transmitted by the consumption of contaminated bivalve shellfish.

  16. Freshwater savings from marine protein consumption

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  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. Mixed oceanic and freshwater depositional conditions for beach rocks of NE Brazil: Evidence from C and O isotopes

    International Nuclear Information System (INIS)

    Chaves, Nubia S.; Kiang, Chang H.

    1998-01-01

    Full text: Beach rocks, a common feature of northeastern coastline of Brazil are formed in the inter tidal zone, considered as ancient coastal line, cemented by CaCO 3 which have variable extension. They occur parallel to the coastline as linear ridges. Beach rocks are sub horizontally disposed and surfaces are irregular, displacing potholes due to differential erosion, perforations by organisms, diaclasis, cross stratification and rare laminations. The dominant detrital components are quartz and minor fractions of feldspars and rock fragments. Zircon, epi dote, hornblende, garnet, muscovite, rutile, opaque and sillimanite are present in trace quantity. Bivalves, mollusks, gastropods, halimeda, corals, pelecipods and equinoids, constitute the biotic components. Beach rocks cement vary from aragonite to Mg-calcite. The dominant micro facies, consists of isopach crystals of aragonite, enclosing bioclastic and/or clastic grains forming uniform fringe formed in the marine phreatic zone. The second is represented by cryptocrystalline inter-granulate cement like micritic envelop formed in meteoric phreatic environment (Moore 1971). The third is formed by inter granulate cryptocrystalline cement, filling the pores. Beach rock samples locate in the coastal zone show an interval with depleted C and O ratios (average δ 13 C = -1.3%0, δ 18 O = -2.1%0) and an interval of enriched isotopic ratios (average δ 13 C = +3.5%0, δ 18 O +1.2%0). Depleted oxygen isotope values considered to be indicative of meteoric diagenesis with minor freshwater influx (Allan and Mattew 1982). (author)

  19. The potential of freshwater macroalgae as a biofuels feedstock and the influence of nutrient availability on freshwater macroalgal biomass production

    Science.gov (United States)

    Yun, Jin-Ho

    Extensive efforts have been made to evaluate the potential of microalgae as a biofuel feedstock during the past 4-5 decades. However, filamentous freshwater macroalgae have numerous characteristics that favor their potential use as an alternative algal feedstock for biofuels production. Freshwater macroalgae exhibit high rates of areal productivity, and their tendency to form dense floating mats on the water surface imply significant reductions in harvesting and dewater costs compared to microalgae. In Chapter 1, I reviewed the published literature on the elemental composition and energy content of five genera of freshwater macroalgae. This review suggested that freshwater macroalgae compare favorably with traditional bio-based energy sources, including terrestrial residues, wood, and coal. In addition, I performed a semi-continuous culture experiment using the common Chlorophyte genus Oedogonium to investigate whether nutrient availability can influence its higher heating value (HHV), productivity, and proximate analysis. The experimental study suggested that the most nutrient-limited growth conditions resulted in a significant increase in the HHV of the Oedogonium biomass (14.4 MJ/kg to 16.1 MJ/kg). Although there was no significant difference in productivity between the treatments, the average dry weight productivity of Oedogonium (3.37 g/m2/day) was found to be much higher than is achievable with common terrestrial plant crops. Although filamentous freshwater macroalgae, therefore, have significant potential as a renewable source of bioenergy, the ultimate success of freshwater macroalgae as a biofuel feedstock will depend upon the ability to produce biomass at the commercial-scale in a cost-effective and sustainable manner. Aquatic ecology can play an important role to achieve the scale-up of algal crop production by informing the supply rates of nutrients to the cultivation systems, and by helping to create adaptive production systems that are resilient to

  20. 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

  1. 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.

  2. Analysis of consumer behavior in decision making of purchasing ornamental freshwater fish (case of study at ornamental freshwater fish market at Peta Street, Bandung)

    Science.gov (United States)

    Gumilar, I.; Rizal, A.; Sriati; Setiawan Putra, R.

    2018-04-01

    This research aim was to analyzed process of decision making of purchasing ornamental freshwater fish at Peta Street, Bandung City and Analyzed what factors are driving consumers to buy freshwater fish Peta Street. The method used in this research is case study with rating scale and rank spearman analysis. The sampling technique is the accidental random sampling method consist of 30 respondents. The consumer’s decision making process consist of five stages, namely the recognition of needs, information searching, alternative evaluation, process of purchasing, and the evaluation of results. The results showed that at the stage of recognition of needs the motivation of purchasing freshwater fish because respondents are very fond of ornamental freshwater fish, at the stage of information search, the information sources are from the print media and friends or neighborhood. At the stage of alternative evaluation, the reason consumers buy ornamental freshwater fish because the quality of good products. The stage of purchasing decision process consumers bought 1-5 fish with frequency of purchase 1 time per month. The evaluation of results of post-purchasing consumers feel very satisfied with the fish products and the price is very affordable. To observe the factors that influence purchasing motivation of consumers, spearman rank test is the method. The results showed that the quality and price of the product are the factors that most influence the purchase decision of ornamental freshwater fish with the range of student-t value 3,968 and 2,107.

  3. Scientific opinion on the risks for public health related to the presence of tetrodotoxin (TTX) and TTX analogues in marine bivalves and gastropods

    DEFF Research Database (Denmark)

    Petersen, Annette

    Tetrodotoxin (TTX) and its analogues are produced by marine bacteria and have been detected in marine bivalves and gastropods from European waters. The European Commission asked EFSA for a scientific opinion on the risks to public health related to the presence of TTX and TTX analogues in marine...... bivalves and gastropods. The Panel on Contaminants in the Food Chain reviewed the available literature but did not find support for the minimum lethal dose for humans of 2 mg, mentioned in various reviews. Some human case reports describe serious effects at a dose of 0.2 mg, corresponding to 4 μg/kg body...... weight (bw). However, the uncertainties on the actual exposure in the studies preclude their use for derivation of an acute reference dose (ARfD). Instead, a group ARfD of 0.25 μg/kg bw, applying to TTX and its analogues, was derived based on a TTX dose of 25 μg/kg bw at which no apathy was observed...

  4. Multi-proxy reconstructions and the power of integration across marine, terrestrial, and freshwater ecosystems. (Invited)

    Science.gov (United States)

    Black, B.

    2013-12-01

    Over the past decade, dendrochronology (tree-ring analysis) techniques have been increasingly applied to growth increments of various bivalve, fish, and coral species. In particular, the use of crossdating ensures that all increments in a dataset have assigned the correct calendar year of formation and that the resulting chronology is exactly placed in time. Such temporal alignment facilitates direct comparisons among chronologies that span diverse taxa and ecosystems, illustrating the pervasive, synchronizing influence of climate from alpine forests to the continental slope. Such an approach can be particularly beneficial to reconstructions in that each species captures climate signals from its unique 'perspective' of life history and habitat. For example, combinations of tree-ring data and chronologies for the long-lived bivalve Pacific geoduck (Panopea generosa) capture substantially more variance in regional sea surface temperatures than either proxy could explain alone. Just as importantly, networks of chronologies spanning multiple trophic levels can help identify climate variables critical to ecosystem functioning, which can then be targeted to generate most biologically relevant reconstructions possible. Along the west coast of North America, fish and bivalve chronologies in combination with records of seabird reproductive success indicate that winter sea-level pressure is closely associated with California Current productivity, which can be hind-cast over the past six centuries using coastal tree-ring chronologies. Thus, multiple proxies not only increase reconstruction skill, but also help isolate climate variables most closely linked to ecosystem structure and functioning.

  5. Nacre calcification in the freshwater mussel Unio pictorum: carbonic anhydrase activity and purification of a 95 kDa calcium-binding glycoprotein.

    Science.gov (United States)

    Marie, Benjamin; Luquet, Gilles; Bédouet, Laurent; Milet, Christian; Guichard, Nathalie; Medakovic, Davorin; Marin, Frédéric

    2008-10-13

    The formation of the molluscan shell is finely tuned by macromolecules of the shell organic matrix. Previous results have shown that the acid-soluble fraction of the nacre matrix of the freshwater paleoheterodont bivalve Unio pictorum shell displays a number of remarkable properties, such as calcium-binding activity, the presence of extensive glycosylations and the capacity to interfere at low concentration with in vitro calcium carbonate precipitation. Here we have found that the nacre-soluble matrix exhibits a carbonic anhydrase activity, an important function in calcification processes. This matrix is composed of three main proteinaceous discrete fractions. The one with the highest apparent molecular weight is a 95 kDa glycoprotein that is specific to the nacreous layer. P95, as it is provisionally named, is enriched in Gly, Glx and Asx and exhibits an apparent pI value of approximately 4, or approximately 7 when chemically deglycosylated. Furthermore, its glycosyl moiety, consisting of sulfated polysaccharides, is involved in calcium binding. Purified fractions of the three main proteins were digested with trypsin, and the resulting peptides were analysed by mass spectrometry. Our results suggest that identical peptides are constitutive domains of the different proteins. Partial primary structures were obtained by de novo sequencing and compared with known sequences from other mollusc shell proteins. Our results are discussed from an evolutionary viewpoint.

  6. 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...

  7. The quagga mussel (Dreissena rostriformis bugensis Andrusov, 1897 – another Ponto-Caspian dreissenid bivalve in the southern Baltic catchment: the first record from the Szczecin Lagoon

    Directory of Open Access Journals (Sweden)

    Adam Woźniczka

    2016-04-01

    Full Text Available In 2014, a non-indigenous dreissenid bivalve, the quagga mussel (Dreissena rostriformis bugensis Andrusov, 1897 was for the first time recorded in the Szczecin Lagoon. This was also the first record of the species in the Baltic Sea catchment. The quagga mussel was found to accompany the zebra mussel (Dreissena polymorpha, a non-indigenous bivalve already firmly established in the Lagoon. As indicated by the new immigrant's estimated abundance (4000.0 ± 355.44 ind. m−2 and the zebra mussel to quagga mussel abundance ratio (about 60:40, the immigration of D. rostriformis bugensis to the Lagoon can be regarded as successful. The quagga mussel has already formed a strong and reproducing population which co-occurs with that of the zebra mussel in the area.

  8. Restructuring European freshwater aquaculture from family-owned to large-scale firms - lessons from Danish aquaculture

    DEFF Research Database (Denmark)

    Nielsen, Rasmus; Asche, Frank; Nielsen, Max

    2016-01-01

    , farms have been small and often co-managed with larger agriculture production. However, to succeed in a market with global competition, technological innovation and sector-wide specialization, it is necessary to continuously increase productivity and induce investments in larger production facilities...... to take advantage of economies of scale. In Denmark, a structural change was ‘kicked off’ in 2005. In just 6 years, 30% of Danish production in freshwater has been reallocated to larger and more technologically advanced recirculation farms. Labour productivity has increased and the environmental impact...

  9. Pesticides in Brazilian freshwaters: a critical review.

    Science.gov (United States)

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

    2016-07-13

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

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

    Science.gov (United States)

    Bank, M. S.

    2017-12-01

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

  11. 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...

  12. 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.

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

    Science.gov (United States)

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

    2014-01-01

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

  14. 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...

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

    International Nuclear Information System (INIS)

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

    1995-01-01

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

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

    Science.gov (United States)

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

    2017-09-01

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

  17. Gene Expression in the Three-Spined Stickleback (Gasterosteus aculeatus) of Marine and Freshwater Ecotypes.

    Science.gov (United States)

    Rastorguev, S M; Nedoluzhko, A V; Gruzdeva, N M; Boulygina, E S; Tsygankova, S V; Oshchepkov, D Y; Mazur, A M; Prokhortchouk, E B; Skryabin, K G

    2018-01-01

    Three-spine stickleback (Gasterosteus aculeatus) is a well-known model organism that is routinely used to explore microevolution processes and speciation, and the number of studies related to this fish has been growing recently. The main reason for the increased interest is the processes of freshwater adaptation taking place in natural populations of this species. Freshwater three-spined stickleback populations form when marine water three-spined sticklebacks fish start spending their entire lifecycle in freshwater lakes and streams. To boot, these freshwater populations acquire novel biological traits during their adaptation to a freshwater environment. The processes taking place in these populations are of great interest to evolutionary biologists. Here, we present differential gene expression profiling in G. aculeatus gills, which was performed in marine and freshwater populations of sticklebacks. In total, 2,982 differentially expressed genes between marine and freshwater populations were discovered. We assumed that differentially expressed genes were distributed not randomly along stickleback chromosomes and that they are regularly observed in the "divergence islands" that are responsible for stickleback freshwater adaptation.

  18. Hepatitis A and E Viruses in Wastewaters, in River Waters, and in Bivalve Molluscs in Italy.

    Science.gov (United States)

    Iaconelli, M; Purpari, G; Della Libera, S; Petricca, S; Guercio, A; Ciccaglione, A R; Bruni, R; Taffon, S; Equestre, M; Fratini, M; Muscillo, M; La Rosa, Giuseppina

    2015-12-01

    Several studies have reported the detection of hepatitis A (HAV) and E (HEV) virus in sewage waters, indicating a possibility of contamination of aquatic environments. The objective of the present study was to assess the occurrence of HAV and HEV in different water environments, following the route of contamination from raw sewage through treated effluent to the surface waters receiving wastewater discharges . Bivalve molluscan shellfish samples were also analyzed, as sentinel of marine pollution. Samples were tested by RT-PCR nested type in the VP1/2A junction for HAV, and in the ORF1 and ORF2 regions for HEV. Hepatitis A RNA was detected in 12 water samples: 7/21 (33.3%) raw sewage samples, 3/21 (14.3%) treated sewage samples, and 2/27 (7.4%) river water samples. Five sequences were classified as genotype IA, while the remaining 7 sequences belonged to genotype IB. In bivalves, HAV was detected in 13/56 samples (23.2%), 12 genotype IB and one genotype IA. Whether the presence of HAV in the matrices tested indicates the potential for waterborne and foodborne transmission is unknown, since infectivity of the virus was not demonstrated. HEV was detected in one raw sewage sample and in one river sample, both belonging to genotype 3. Sequences were similar to sequences detected previously in Italy in patients with autochthonous HEV (no travel history) and in animals (swine). To our knowledge, this is the first detection of HEV in river waters in Italy, suggesting that surface water can be a potential source for exposure .

  19. Biomarkers of metabolism disturbance in bivalve molluscs induced by environmental pollution with processed by-products of oil

    Directory of Open Access Journals (Sweden)

    E. V. Sukharenko

    2017-05-01

    Full Text Available Processed by-products of oil are the most common pollutants in all river and sea water. The increase in oxidative stress in bivalve molluscs was studied in both tissues of the hepatopancreas and the gill. The model for artificial treatment with processed by-products of oil was performed in a laboratory experiment with the river mollusc Dreissena polymorpha Pallas, 1771. The exposure of the molluscs over 28 days to mazut 50 mg/l induced significant increase of both final product of lipid peroxidation (LPO and antioxidant enzime activity. A significant increase in LPO was observed in the hepatopancreas and gill of D. polymorpha treated with mazut compared to the control group. Antioxidant enzyme activity of cartalase, supeoxide dismutase, glutathione reductase and glutathione-S-transferase showed a greater increase (by almost 1.5 times in the hepatopancreas than in the gill of D. polymorpha. A similar LPO growth and modulation of antioxidant enzyme activity were determined in the hepatopancreas and gill of the mussel Mytilus galloprovincialis Lamarck, 1879 collected in an area polluted with resins, hydrocarbons and asphaltenes, Donuzlav lake in the Kerch gulf. Varied cellular reactivation of the antioxidant enzyme system in the hepatopancreas rather than the gill was observed in both kinds of mollusc Dreissena and Mytilus. The obtained results are evidence of the higher sensitivity of the hepatopancreas cells of bivalve molluscs to organic pollutants compared to the gill cells.

  20. The effectiveness of surrogate taxa to conserve freshwater biodiversity

    Science.gov (United States)

    Stewart, David R.; Underwood, Zachary E.; Rahel, Frank J.; Walters, Annika W.

    2018-01-01

    Establishing protected areas has long been an effective conservation strategy, and is often based on more readily surveyed species. The potential of any freshwater taxa to be a surrogate of other aquatic groups has not been fully explored. We compiled occurrence data on 72 species of freshwater fish, amphibians, mussels, and aquatic reptiles for the Great Plains, Wyoming. We used hierarchical Bayesian multi-species mixture models and MaxEnt models to describe species distributions, and program Zonation to identify conservation priority areas for each aquatic group. The landscape-scale factors that best characterized aquatic species distributions differed among groups. There was low agreement and congruence among taxa-specific conservation priorities (<20%), meaning that no surrogate priority areas would include or protect the best habitats of other aquatic taxa. We found that common, wide-ranging aquatic species were included in taxa-specific priority areas, but rare freshwater species were not included. Thus, the development of conservation priorities based on a single freshwater aquatic group would not protect all species in the other aquatic groups.

  1. Freshwater exposure pathways in the Nordic countries

    International Nuclear Information System (INIS)

    Tveten, U.

    1984-06-01

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

  2. Vodní malakofauna dolního toku Lužnice se zaměřením na stav populace velevruba tupého (Unio crassus Aquatic molluscan fauna of the lower part of the Lužnice River (South Bohemia, Czech Republic with focus on the population of Unio crassus

    Directory of Open Access Journals (Sweden)

    Luboš Beran

    2012-02-01

    Full Text Available This paper presents results of a malacological survey of the Lužnice River in ca 70 km long stretch between the inflow of its main tributary the Nežárka River in Veselí nad Lužnicí and its confluence with the Vltava River in Southern Bohemia (Czech Republic. Thirty-one species of aquatic molluscs (19 gastropods, 12 bivalves representing 40% of freshwater molluscan fauna of the Czech Republic were found at 15 sites. Differences of molluscan assemblages upstream and downstream of Tábor town were probably caused by different characters of the watercourse. The occurrence of rare bivalve Pseudanodonta complanata was confirmed. On the other hand, two non-native species Physella acuta and Sinanodonta woodiana were recorded. The research was preferentially focused on the population of the endangered bivalve Unio crassus. Its occurrence was confirmed at 8 from 15 sites under study but altogether only 31 individuals were found. Less than four specimens were found at particular sites but one.

  3. 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.

  4. 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 ...

  5. A Search for Freshwater in the Saline Aquifers of Coastal Bangladesh

    Science.gov (United States)

    Peters, C.; Hornberger, G. M.

    2017-12-01

    Can we locate pockets of freshwater amidst brackish groundwater in remote villages in Bangladesh? This study explores what we can infer about local groundwater-surface water (GW-SW) interactions in the polders of coastal Bangladesh. In this underdeveloped region, the shallow groundwater is primarily brackish with unpredictable apportioning of freshwater pockets. We use transects of piezometers, cores, electromagnetic induction, and water chemistry surveys to explore two sources of potential fresh groundwater: (1) tidal channel-aquifer exchange and (2) meteoric recharge. Freshwater is difficult to find due to disparate subsurface lithology, asymmetrical tidal dynamics, extreme seasonal fluctuations in rainfall, and limited field data. Observations suggest substantial lateral variability in shallow subsurface conductivity profiles as well as tidal pressure signals in piezometers. Nevertheless, active exchange of freshwater may be limited due to low permeability of banks and surface sediments limits. Small scale heterogeneity in delta formation likely caused much of the groundwater salinity variation. Without adequate ground truthing of groundwater quality, the ability to deduce the exact location of freshwater pockets may be restricted.

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

    Directory of Open Access Journals (Sweden)

    Yusuke Yamanoue

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

  7. Turtles: Freshwater

    Science.gov (United States)

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

    2017-01-01

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

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

    African Journals Online (AJOL)

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

  9. Life cycle environmental impacts of advanced wastewater treatment techniques for removal of pharmaceuticals and personal care products (PPCPs).

    Science.gov (United States)

    Zepon Tarpani, Raphael Ricardo; Azapagic, Adisa

    2018-06-01

    Pharmaceutical and personal care products (PPCPs) are of increasing interest because of their ecotoxicological properties and environmental impacts. Wastewater treatment plants (WWTPs) are the main pathway for their release into freshwaters due to the inefficiency of conventional WWTPs in removing many of these contaminants from effluents. Therefore, different advanced effluent treatment techniques have been proposed for their treatment. However, it is not known at present how effective these treatment methods are and whether on a life cycle basis they cause other environmental impacts which may outweigh the benefits of the treatment. In an effort to provide an insight into this question, this paper considers life cycle environmental impacts of the following advanced treatment techniques aimed at reducing freshwater ecotoxicity potential of PPCPs: granular activated carbon (GAC), nanofiltration (NF), solar photo-Fenton (SPF) and ozonation. The results suggest that on average NF has the lowest impacts for 13 out of 18 categories considered. GAC is the best alternative for five impacts, including metals and water depletion, but it has the highest marine eutrophication. SPF and ozonation are the least sustainable for eight impacts, including ecotoxicity and climate change. GAC and NF are also more efficient in treating heavy metals while avoiding generation of harmful by-products during the treatment, thus being more suitable for potable reuse of wastewater. However, releasing the effluent without advanced treatment to agricultural land achieves a much higher reduction of freshwater ecotoxicity than treating it by any of the advanced treatments and releasing to the environment. Therefore, the use of advanced effluent treatment for agricultural purposes is not recommended. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2010-01-01

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

  11. 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...

  12. Identifying national freshwater ecosystem priority areas

    CSIR Research Space (South Africa)

    Nel, JL

    2012-10-01

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

  13. Extensive behavioural divergence following colonisation of the freshwater environment in threespine sticklebacks.

    Directory of Open Access Journals (Sweden)

    Carole Di-Poi

    Full Text Available Colonisation of novel environments means facing new ecological challenges often resulting in the evolution of striking divergence in phenotypes. However, little is known about behavioural divergence following colonisation, despite the predicted importance of the role of behavioural phenotype-environment associations in adaptive divergence. We studied the threespine stickleback (Gasterosteus aculeatus, a model system for postglacial colonisation of freshwater habitats largely differing in ecological conditions from the ones faced by the descendants of the marine ancestor. We found that common-environment reared freshwater juveniles were less social, more active and more aggressive than their marine counterparts. This behavioural divergence could represent the result of natural selection that acted on individuals following freshwater colonisation, with predation as a key selection agent. Alternatively, the behavioural profile of freshwater juveniles could represent the characteristics of individuals that preferentially invaded freshwater after the glacial retreat, drawn from the standing variation present in the marine population.

  14. 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 ...

  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. 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

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

    Science.gov (United States)

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

    2017-07-01

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

  18. Sources, variability and fate of freshwater in the Bellingshausen Sea, Antarctica

    Science.gov (United States)

    Regan, Heather C.; Holland, Paul R.; Meredith, Michael P.; Pike, Jennifer

    2018-03-01

    During the second half of the twentieth century, the Antarctic Peninsula was subjected to a rapid increase in air temperatures. This was accompanied by a reduction in sea ice extent, increased precipitation and a dramatic retreat of glaciers associated with an increase in heat flux from deep ocean water masses. Isotopic tracers have been used previously to investigate the relative importance of the different freshwater sources to the adjacent Bellingshausen Sea (BS), but the data coverage is strongly biased toward summer. Here we use a regional model to investigate the ocean's response to the observed changes in its different freshwater inputs (sea ice melt/freeze, precipitation, evaporation, iceberg/glacier melt, and ice shelf melt). The model successfully recreates BS water masses and performs well against available freshwater data. By tracing the sources and pathways of the individual components of the freshwater budget, we find that sea ice dominates seasonal changes in the total freshwater content and flux, but all sources make a comparable contribution to the annual-mean. Interannual variability is dominated by sea ice and precipitation. Decadal trends in the salinity and stratification of the ocean are investigated, and a 20-year surface freshening from 1992 to 2011 is found to be predominantly driven by decreasing autumn sea ice growth. These findings will help to elucidate the role of freshwater in driving circulation and water column structure changes in this climatically-sensitive region.

  19. Effects of pollution on freshwater fish

    International Nuclear Information System (INIS)

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

    1976-01-01

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

  20. The mismatch between bioaccumulation in field and laboratory environments: Interpreting the differences for metals in benthic bivalves

    International Nuclear Information System (INIS)

    Belzunce-Segarra, Maria J.; Simpson, Stuart L.; Amato, Elvio D.; Spadaro, David A.; Hamilton, Ian L.; Jarolimek, Chad V.; Jolley, Dianne F.

    2015-01-01

    Laboratory-based bioaccumulation and toxicity bioassays are frequently used to predict the ecological risk of contaminated sediments in the field. This study investigates the bioassay conditions most relevant to achieving environmentally relevant field exposures. An identical series of metal-contaminated marine sediments were deployed in the field and laboratory over 31 days. Changes in metal concentrations and partitioning in both sediments and waters were used to interpret differences in metal exposure and bioaccumulation to the benthic bivalve Tellina deltoidalis. Loss of resuspended sediments and deposition of suspended particulate matter from the overlying water resulted in the concentrations of Cu, Pb and Zn (major contaminants) becoming lower in the 1-cm surface layer of field-deployed sediments. Lower exchange rates of overlying waters in the laboratory resulted in higher dissolved metal exposures. The prediction of metal bioaccumulation by the bivalves in field and laboratory was improved by considering the metal partitioning within the surface sediments. - Highlights: • Particulate metals are the dominant metal exposure route in laboratory and field tests (87). • There is an over-representation of the dissolved metal exposure in the laboratory (81). • Laboratory bioassays result in higher bioaccumulation of major metals, Cu, Pb, Zn (82). • Differences in exposure must be considered for a proper sediment quality evaluation (83). • Traditional measurements are not sufficient to explain bioaccumulation results (79). - To improve the value of field- and laboratory-based sediment bioassays in ecological risk assessments, it is necessary to create exposure conditions that resemble those in the field

  1. The Implications of Ranaviruses to European farmed and wild freshwater fish

    DEFF Research Database (Denmark)

    Jensen, Ann Britt Bang

    The present thesis explores the implications of ranaviruses to European farmed and wild freshwater fish. The work presented was carried out as a part of the EU project “Risk assessment of new and emerging systemic iridoviral diseases for European fish and aquatic ecosystems” which was initiated...... in 2005 as a reaction to the speculation that ranaviruses might pose a serious threat to both farmed and wild-living freshwater fish and amphibians within the European community. In the present thesis, the purpose is to determine the implications of ranaviruses to European freshwater farmed and wild......-living fish. The following specific objectives are addressed: Objective 1: To determine the susceptibility of selected European freshwater fish to a panel of ranaviruses Objective 2: To determine whether ornamental fish are susceptible to or can be carriers of ranaviruses Objective 3: To develop a model...

  2. Successful enrichment of the ubiquitous freshwater acI Actinobacteria.

    Science.gov (United States)

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

    2014-02-01

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

  3. A New Method to Infer Advancement of Saline Front in Coastal Groundwater Systems by 3D: The Case of Bari (Southern Italy Fractured Aquifer

    Directory of Open Access Journals (Sweden)

    Costantino Masciopinto

    2016-02-01

    Full Text Available A new method to study 3D saline front advancement in coastal fractured aquifers has been presented. Field groundwater salinity was measured in boreholes of the Bari (Southern Italy coastal aquifer with depth below water table. Then, the Ghyben-Herzberg freshwater/saltwater (50% sharp interface and saline front position were determined by model simulations of the freshwater flow in groundwater. Afterward, the best-fit procedure between groundwater salinity measurements, at assigned water depth of 1.0 m in boreholes, and distances of each borehole from the modelled freshwater/saltwater saline front was used to convert each position (x, y in groundwater to the water salinity concentration at depth of 1.0 m. Moreover, a second best-fit procedure was applied to the salinity measurements in boreholes with depth z. These results provided a grid file (x, y, z, salinity suitable for plotting the actual Bari aquifer salinity by 3D maps. Subsequently, in order to assess effects of pumping on the saltwater-freshwater transition zone in the coastal aquifer, the Navier-Stokes (N-S equations were applied to study transient density-driven flow and salt mass transport into freshwater of a single fracture. The rate of seawater/freshwater interface advancement given by the N-S solution was used to define the progression of saline front in Bari groundwater, starting from the actual salinity 3D map. The impact of pumping of 335 L·s−1 during the transition period of 112.8 days was easily highlighted on 3D salinity maps of Bari aquifer.

  4. Marine Bacteria with antimicrobials capacity isolated from cultures of bivalve mollusks

    Directory of Open Access Journals (Sweden)

    Fabiola Pellon

    2014-06-01

    Full Text Available Microorganisms have commonly been studied as producers of antibacterial substances; yet they are also considered producers of antifungic, antiviral, antiparasitic, citotoxics and inhibitory of other forms of cellular growth substances. This paper describes the isolation, inhibitory potential and phenotipic characterization of native bacterial strains associated to bivalve mollusks such as Argopecten purpuratus “concha de abanico” and Crassostrea gigas “ostra” in cultivation systems. From 345 marine strains collected, 20 strains were recovered that had the ability of inhibiting a wide spectrum of fish, mollusks and shellfish pathogenic bacteria; being the most sensitive pathogens Aeromonas sobria P-281, Aeromonas hydrophila ATCC 7966, Vibrio vulnificus ATCC 27562 and Vibrio parahaemolyticus ATCC 17803. The phenotipic characterization of this strains with inhibitory capacity allowed the identification of the following genera: Vibrio (40%, Aeromonas (15%, Flavobacterium (10%, Pseudomonas (5%, Moraxella (5%, Flexibacter (5%. A 20% could not be identified. The results suggest that the isolated bacteria could be used as probiotics agents for the biological control of pathogens from marine organisms of interest in mariculture.

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

    Directory of Open Access Journals (Sweden)

    Ronaldo Sousa

    2015-12-01

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

  6. Processes of physical change to the seabed and bivalve recruitment over a 10-year period following experimental hydraulic clam dredging on Banquereau, Scotian Shelf

    Science.gov (United States)

    Gilkinson, K.; King, E. L.; Li, M. Z.; Roddick, D.; Kenchington, E.; Han, G.

    2015-01-01

    A previous study on the effects of experimental hydraulic clam dredging on seabed habitat and commercial bivalve populations revealed a lack of recovery after a 3-year post-dredging period (1998-2001) on a deep (65-75 m) offshore sandy bank on the Scotian Shelf, Canada. Follow-up sidescan sonar surveys were carried out 5 and 10 years after dredging (2003, 2008) in order to identify long-term processes of seabed recovery. Grab sampling was carried out 10 years after dredging to identify post-dredging commercial bivalve recruitment. Changes in the seafloor, including dredge tracks, were documented with a series of 7 sidescan sonar surveys between 1998 and 2008. A sediment mobility model was constructed based on modeled tidal current and hindcast wave data over this time period to quantify natural seabed disturbance and interpret changes to the dredge tracks mapped by sidescan sonar surveys. The model indicated that tidal currents had minimal effect on sediment mobilization. The main driving force associated with re-working of surficial sediments as evidenced by deterioration of dredge tracks in sonograms was annual fall/winter storms. While the annual frequency of storms and associated wave heights was variable, the observations and sediment mobility calculations suggest that the most influential variable is the magnitude of individual large storms, specifically storms with a significant wave height of ∼11 m. These storms are capable of generating mobile sediment layers of 20-30 cm thickness, equivalent to the dredge blade cutting depth. It appears that, with minor exceptions, sediment properties have returned to pre-dredging conditions 10 years after dredging in this habitat. Based on known age-length relationships, the four commercial bivalve species showed very low recruitment at the experimental site over the 10-year post-dredging period. However, this is unlikely due to a dredging effect since a similar pattern was observed in non-dredged areas.

  7. DICKINSARTELLA FAUNA FROM THE SAIWAN FORMATION (OMAN: A BIVALVE FAUNA TESTIFYING TO THE LATE SAKMARIAN (EARLY PERMIAN CLIMATIC AMELIORATION ALONG THE NORTH-EASTERN GONDWANAN FRINGE.

    Directory of Open Access Journals (Sweden)

    CRISTIANO LARGHI

    2005-11-01

    Full Text Available The transitional faunas of the Permian Huqf succession of Oman make it one of the key-sections for the intercalibration of Early to Middle Permian biostratigraphical scales. The abundance of fossils improved the knowledge of some marine faunas which populated the North-Eastern Gondwanan fringe during times of climatic changes in the Permian. A Sterlitamakian (upper Sakmarian, Lower Permian bivalve fauna from the Saiwan Formation in the Huqf area, informally named "Dickinsartella Fauna", is described in the present paper. The specimens examined were collected from the "Pachycyrtella Bed" (Auctorum, the basal bed of the Formation in its type locality. The Dickinsartella Fauna can be identified for the presence of the new genus Dickinsartella, which dominates the bivalve thanatocoenosis with D. pistacina sp. n. (type species. The bivalve fauna from the Pachycyrtella Bed includes the new species Stutchburia sangallii and Promytilus  mazzolenii, and also Astartella obliqua Dickins, 1963, Nuculopsis cf. bangarraensis Dickins, 1963, ?Oriocrassatella sp., and indeterminable aviculopectinids. This fauna shows a low taxonomic diversity. Nevertheless, some species are represented by a high number of generally well-preserved specimens, i.e. some specimens of S. sangallii sp. n. and A. obliqua show part of the ligament.  The good preservation of the shells permitted the microstructural analysis of D. pistacina sp. n. and S. sangallii sp. n. The microstructure of S. sangallii sp. n. supports the close phylogenetical link between modiomorphids and crassatelloids recognized by some previous authors.The new genus Dickinsartella includes the more recent species belonging to the important Paleozoic Order Cyrtodontida Scarlato & Starobogatov, 1971. The discovery of Dickinsartella gen. n. and other taxa of the Pachycyrtella Bed, present also in the Sakmarian levels of the Carnarvon and Perth Basins in Western Australia,  indicates a wider distribution of the

  8. Hydrogeology and management of freshwater lenses on atoll islands: Review of current knowledge and research needs

    Science.gov (United States)

    Werner, Adrian D.; Sharp, Hannah K.; Galvis, Sandra C.; Post, Vincent E. A.; Sinclair, Peter

    2017-08-01

    On atoll islands, fresh groundwater occurs as a buoyant lens-shaped body surrounded by saltwater derived from the sea, forming the main freshwater source for many island communities. A review of the state of knowledge of atoll island groundwater is overdue given their susceptibility to adverse impacts, and the task to address water access and sanitation issues within the United Nations' Sustainable Development Goals framework before the year 2030. In this article, we review available literature to summarise the key processes, investigation techniques and management approaches of atoll island groundwater systems. Over fifty years of investigation has led to important advancements in the understanding of atoll hydrogeology, but a paucity of hydrogeological data persists on all but a small number of atoll islands. We find that the combined effects of buoyancy forces, complex geology, tides, episodic ocean events, strong climatic variability and human impacts create highly dynamic fresh groundwater lenses. Methods used to quantify freshwater availability range from simple empirical relationships to three-dimensional density-dependent models. Generic atoll island numerical models have proven popular in trying to unravel the individual factors controlling fresh groundwater lens behaviour. Major challenges face the inhabitants and custodians of atoll island aquifers, with rising anthropogenic stresses compounded by the threats of climate variability and change, sea-level rise, and some atolls already extracting freshwater at or above sustainability limits. We find that the study of atoll groundwater systems remains a critical area for further research effort to address persistent knowledge gaps, which lead to high uncertainties in water security issues for both island residents and surrounding environs.

  9. Genes of the mitochondrial apoptotic pathway in Mytilus galloprovincialis.

    Directory of Open Access Journals (Sweden)

    Noelia Estévez-Calvar

    Full Text Available Bivalves play vital roles in marine, brackish, freshwater and terrestrial habitats. In recent years, these ecosystems have become affected through anthropogenic activities. The ecological success of marine bivalves is based on the ability to modify their physiological functions in response to environmental changes. One of the most important mechanisms involved in adaptive responses to environmental and biological stresses is apoptosis, which has been scarcely studied in mollusks, although the final consequence of this process, DNA fragmentation, has been frequently used for pollution monitoring. Environmental stressors induce apoptosis in molluscan cells via an intrinsic pathway. Many of the proteins involved in vertebrate apoptosis have been recognized in model invertebrates; however, this process might not be universally conserved. Mytilus galloprovincialis is presented here as a new model to study the linkage between molecular mechanisms that mediate apoptosis and marine bivalve ecological adaptations. Therefore, it is strictly necessary to identify the key elements involved in bivalve apoptosis. In the present study, six mitochondrial apoptotic-related genes were characterized, and their gene expression profiles following UV irradiation were evaluated. This is the first step for the development of potential biomarkers to assess the biological responses of marine organisms to stress. The results confirmed that apoptosis and, more specifically, the expression of the genes involved in this process can be used to assess the biological responses of marine organisms to stress.

  10. Water-to-Wildlife Transfer of Radionuclides in Freshwater Ecosystems around the Gyeongju Nuclear Site

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yong-Ho; Lim, Kwang-Muk; Jun, In; Kim, Byeong-Ho; Keum, Dong-Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    The IAEA and ICRP have recognized that not only humans but also wildlife needs to be protected from the impact of ionizing radiations. In many advanced countries, it is legally required to evaluate the radiological impact to wildlife. Therefore, it can be expected that the wildlife dose assessment will also soon become a legal requirement in Korea. One of the key parameters in evaluating radiation doses to wildlife is the concentration ratio (CR), which is used for quantifying radionuclide transfer from an environmental medium such as soil and water to an organism. CR values can vary greatly with environmental conditions and wildlife species. Accordingly, it is important for a reliable dose assessment that site-specific CR data be used. In this study, CR values of various radionuclides were measured for several freshwater wildlife species living around the Gyeongju nuclear site. CR values of a total of 20 elements were determined for three fish species and three plant species living in freshwater ecosystems around the Gyeongju nuclear site. The CR values showed considerable variations with the elements and with wildlife species. For the establishment of a reliable input data file of K-BIOTA, a Korean wildlife dose assessment model, data on CR values needs to be increased to cover a wider range of domestic wildlife.

  11. Water-to-Wildlife Transfer of Radionuclides in Freshwater Ecosystems around the Gyeongju Nuclear Site

    International Nuclear Information System (INIS)

    Choi, Yong-Ho; Lim, Kwang-Muk; Jun, In; Kim, Byeong-Ho; Keum, Dong-Kwon

    2015-01-01

    The IAEA and ICRP have recognized that not only humans but also wildlife needs to be protected from the impact of ionizing radiations. In many advanced countries, it is legally required to evaluate the radiological impact to wildlife. Therefore, it can be expected that the wildlife dose assessment will also soon become a legal requirement in Korea. One of the key parameters in evaluating radiation doses to wildlife is the concentration ratio (CR), which is used for quantifying radionuclide transfer from an environmental medium such as soil and water to an organism. CR values can vary greatly with environmental conditions and wildlife species. Accordingly, it is important for a reliable dose assessment that site-specific CR data be used. In this study, CR values of various radionuclides were measured for several freshwater wildlife species living around the Gyeongju nuclear site. CR values of a total of 20 elements were determined for three fish species and three plant species living in freshwater ecosystems around the Gyeongju nuclear site. The CR values showed considerable variations with the elements and with wildlife species. For the establishment of a reliable input data file of K-BIOTA, a Korean wildlife dose assessment model, data on CR values needs to be increased to cover a wider range of domestic wildlife

  12. Assessing and managing freshwater ecosystems vulnerable to global change

    Science.gov (United States)

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

    2014-01-01

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

  13. Impact of increasing antarctic glacial freshwater release on regional sea-ice cover in the Southern Ocean

    Science.gov (United States)

    Merino, Nacho; Jourdain, Nicolas C.; Le Sommer, Julien; Goosse, Hugues; Mathiot, Pierre; Durand, Gael

    2018-01-01

    The sensitivity of Antarctic sea-ice to increasing glacial freshwater release into the Southern Ocean is studied in a series of 31-year ocean/sea-ice/iceberg model simulations. Glaciological estimates of ice-shelf melting and iceberg calving are used to better constrain the spatial distribution and magnitude of freshwater forcing around Antarctica. Two scenarios of glacial freshwater forcing have been designed to account for a decadal perturbation in glacial freshwater release to the Southern Ocean. For the first time, this perturbation explicitly takes into consideration the spatial distribution of changes in the volume of Antarctic ice shelves, which is found to be a key component of changes in freshwater release. In addition, glacial freshwater-induced changes in sea ice are compared to typical changes induced by the decadal evolution of atmospheric states. Our results show that, in general, the increase in glacial freshwater release increases Antarctic sea ice extent. But the response is opposite in some regions like the coastal Amundsen Sea, implying that distinct physical mechanisms are involved in the response. We also show that changes in freshwater forcing may induce large changes in sea-ice thickness, explaining about one half of the total change due to the combination of atmospheric and freshwater changes. The regional contrasts in our results suggest a need for improving the representation of freshwater sources and their evolution in climate models.

  14. Biota: Providing often-overlooked connections among freshwater systems

    Science.gov (United States)

    Mushet, David M.; Christensen, Jay R.; Bennett, Michah; Alexander, Laurie C.

    2017-01-01

    When we think about connections in and among aquatic systems, we typically envision clear headwater streams flowing into downstream rivers, river floodwaters spilling out onto adjacent floodplains, or groundwater connecting wetlands to lakes and streams. However, there is another layer of connectivity moving materials among freshwater systems, one with connections that are not always tied to downgradient flows of surface waters and groundwater. These movements are those of organisms, key components of virtually every freshwater system on the planet. In their movements across the landscape, biota connect aquatic systems in often-overlooked ways.

  15. 78 FR 52192 - Final Aquatic Life Ambient Water Quality Criteria For Ammonia-Freshwater 2013

    Science.gov (United States)

    2013-08-22

    ... ambient water quality criteria for the protection of aquatic life from effects of ammonia in freshwater... ammonia to freshwater aquatic life. On December 30, 2009, EPA published draft national recommended water... freshwater are intended to protect aquatic life and do not address human health toxicity data. The water...

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

    Science.gov (United States)

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

    2014-12-01

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

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

    International Nuclear Information System (INIS)

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

    1993-01-01

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

  18. The ecology of freshwater bivalves in the Lake Sapanca basin, Turkey

    Czech Academy of Sciences Publication Activity Database

    Ercan, E.; Gaygusuz, Ö.; Tarkan, A. S.; Reichard, Martin; Smith, C.

    2013-01-01

    Roč. 37, č. 6 (2013), s. 730-738 ISSN 1300-0179 R&D Projects: GA ČR GA13-05872S Institutional support: RVO:68081766 Keywords : Turkey * water quality * invasive species * age * growth Subject RIV: EH - Ecology, Behaviour Impact factor: 0.585, year: 2013

  19. Combining Remote Temperature Sensing with in-Situ Sensing to Track Marine/Freshwater Mixing Dynamics.

    Science.gov (United States)

    McCaul, Margaret; Barland, Jack; Cleary, John; Cahalane, Conor; McCarthy, Tim; Diamond, Dermot

    2016-08-31

    The ability to track the dynamics of processes in natural water bodies on a global scale, and at a resolution that enables highly localised behaviour to be visualized, is an ideal scenario for understanding how local events can influence the global environment. While advances in in-situ chem/bio-sensing continue to be reported, costs and reliability issues still inhibit the implementation of large-scale deployments. In contrast, physical parameters like surface temperature can be tracked on a global scale using satellite remote sensing, and locally at high resolution via flyovers and drones using multi-spectral imaging. In this study, we show how a much more complete picture of submarine and intertidal groundwater discharge patterns in Kinvara Bay, Galway can be achieved using a fusion of data collected from the Earth Observation satellite (Landsat 8), small aircraft and in-situ sensors. Over the course of the four-day field campaign, over 65,000 in-situ temperatures, salinity and nutrient measurements were collected in parallel with high-resolution thermal imaging from aircraft flyovers. The processed in-situ data show highly correlated patterns between temperature and salinity at the southern end of the bay where freshwater springs can be identified at low tide. Salinity values range from 1 to 2 ppt at the southern end of the bay to 30 ppt at the mouth of the bay, indicating the presence of a freshwater wedge. The data clearly show that temperature differences can be used to track the dynamics of freshwater and seawater mixing in the inner bay region. This outcome suggests that combining the tremendous spatial density and wide geographical reach of remote temperature sensing (using drones, flyovers and satellites) with ground-truthing via appropriately located in-situ sensors (temperature, salinity, chemical, and biological) can produce a much more complete and accurate picture of the water dynamics than each modality used in isolation.

  20. Homogenization patterns of the world's freshwater fish faunas.

    Science.gov (United States)

    Villéger, Sébastien; Blanchet, Simon; Beauchard, Olivier; Oberdorff, Thierry; Brosse, Sébastien

    2011-11-01

    The world is currently undergoing an unprecedented decline in biodiversity, which is mainly attributable to human activities. For instance, nonnative species introduction, combined with the extirpation of native species, affects biodiversity patterns, notably by increasing the similarity among species assemblages. This biodiversity change, called taxonomic homogenization, has rarely been assessed at the world scale. Here, we fill this gap by assessing the current homogenization status of one of the most diverse vertebrate groups (i.e., freshwater fishes) at global and regional scales. We demonstrate that current homogenization of the freshwater fish faunas is still low at the world scale (0.5%) but reaches substantial levels (up to 10%) in some highly invaded river basins from the Nearctic and Palearctic realms. In these realms experiencing high changes, nonnative species introductions rather than native species extirpations drive taxonomic homogenization. Our results suggest that the "Homogocene era" is not yet the case for freshwater fish fauna at the worldwide scale. However, the distressingly high level of homogenization noted for some biogeographical realms stresses the need for further understanding of the ecological consequences of homogenization processes.

  1. Predator-induced reduction of freshwater carbon dioxide emissions

    Science.gov (United States)

    Atwood, Trisha B.; Hammill, Edd; Greig, Hamish S.; Kratina, Pavel; Shurin, Jonathan B.; Srivastava, Diane S.; Richardson, John S.

    2013-03-01

    Predators can influence the exchange of carbon dioxide between ecosystems and the atmosphere by altering ecosystem processes such as decomposition and primary production, according to food web theory. Empirical knowledge of such an effect in freshwater systems is limited, but it has been suggested that predators in odd-numbered food chains suppress freshwater carbon dioxide emissions, and predators in even-numbered food chains enhance emissions. Here, we report experiments in three-tier food chains in experimental ponds, streams and bromeliads in Canada and Costa Rica in the presence or absence of fish (Gasterosteus aculeatus) and invertebrate (Hesperoperla pacifica and Mecistogaster modesta) predators. We monitored carbon dioxide fluxes along with prey and primary producer biomass. We found substantially reduced carbon dioxide emissions in the presence of predators in all systems, despite differences in predator type, hydrology, climatic region, ecological zone and level of in situ primary production. We also observed lower amounts of prey biomass and higher amounts of algal and detrital biomass in the presence of predators. We conclude that predators have the potential to markedly influence carbon dioxide dynamics in freshwater systems.

  2. Ultrasound assisted enzymatic hydrolysis for isolating titanium dioxide nanoparticles from bivalve mollusk before sp-ICP-MS.

    Science.gov (United States)

    Taboada-López, María Vanesa; Iglesias-López, Sara; Herbello-Hermelo, Paloma; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio

    2018-08-14

    Applicability of single-particle inductively coupled plasma mass spectrometry (sp-ICP-MS) using dwell times equal to or shorter than 100 μs has been tested for assessing titanium dioxide nanoparticles (TiO 2 NPs) in bivalve mollusks. TiO 2 NPs isolation from fresh mollusk tissues was achieved by ultrasound assisted enzymatic hydrolysis procedure using a pancreatin/lipase mixture. Optimum extraction conditions imply ultrasonication (60% amplitude) for 10 min, and 7.5 mL of a solution containing 3.0 g L -1 of pancreatin and lipase (pH 7.4). The developed method was found to be repeatable (repeatability of 17% for the over-all procedure, TiO 2 NPs concentration of 5.33 × 10 7  ± 8.89 × 10 6 , n = 11), showing a limit of detection of 5.28 × 10 6 NPs g -1 , and a limit of detection in size of 24.4-30.4 nm, based on the 3σ criteria, and on the 3σ/5 σ criteria, respectively. The analytical recovery within the 90-99% range (use of TiO 2 NPs standards of 50 nm at 7 and 14 μg L -1 as Ti). Several bivalve mollusks (clams, cockles, mussels, razor clams, oysters and variegated scallops) were analyzed for total titanium (ICP-MS after microwave assisted acid digestion), and for TiO 2 NPs by the proposed method. TiO 2 NPs concentrations were within the 2.36 × 10 7 -1.25 × 10 8 NPs g -1 range, and the most frequent sizes were from 50 to 70 nm. Copyright © 2018 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2014-01-01

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

  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. Tributyltin-resistant bacteria from estuarine and freshwater sediments.

    Science.gov (United States)

    Wuertz, S; Miller, C E; Pfister, R M; Cooney, J J

    1991-01-01

    Resistance to tributyltin (TBT) was examined in populations from TBT-polluted sediments and nonpolluted sediments from an estuary and from fresh water as well as in pure cultures isolated from those sediments. The 50% effective concentrations (EC50s) for populations were higher at a TBT-polluted freshwater site than at a site without TBT, suggesting that TBT selected for a TBT-resistant population. In contrast, EC50s were significantly lower for populations from a TBT-contaminated estuarine site than for those from a site without TBT, suggesting that other factors in addition to TBT determine whether populations become resistant. EC50s for populations from TBT-contaminated freshwater sediments were nearly 30 times higher than those for populations from TBT-contaminated estuarine sediments. We defined a TBT-resistant bacterium as one which grows on trypticase soy agar containing 8.4 microM TBT, a concentration which prevented the growth of 90% of the culturable bacteria from these sediments. The toxicity of TBT in laboratory media was influenced markedly by the composition of the medium and whether it was liquid or solid. Ten TBT-resistant isolates from estuarine sediments and 19 from freshwater sediments were identified to the genus level. Two isolates, each a Bacillus sp., may be the first gram-positive bacteria isolated from fresh water in the presence of a high concentration of TBT. There was a high incidence of resistance to heavy metals: metal resistance indices were 0.76 for estuarine isolates and 0.68 for freshwater isolates.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1746939

  6. Analysis of the Arctic system for freshwater cycle intensification: Observations and expectations

    Science.gov (United States)

    Rawlins, M.A.; Steele, M.; Holland, M.M.; Adam, J.C.; Cherry, J.E.; Francis, J.A.; Groisman, P.Y.; Hinzman, L.D.; Huntington, T.G.; Kane, D.L.; Kimball, J.S.; Kwok, R.; Lammers, R.B.; Lee, C.M.; Lettenmaier, D.P.; McDonald, K.C.; Podest, E.; Pundsack, J.W.; Rudels, B.; Serreze, Mark C.; Shiklomanov, A.; Skagseth, O.; Troy, T.J.; Vorosmarty, C.J.; Wensnahan, M.; Wood, E.F.; Woodgate, R.; Yang, D.; Zhang, K.; Zhang, T.

    2010-01-01

    Hydrologic cycle intensification is an expected manifestation of a warming climate. Although positive trends in several global average quantities have been reported, no previous studies have documented broad intensification across elements of the Arctic freshwater cycle (FWC). In this study, the authors examine the character and quantitative significance of changes in annual precipitation, evapotranspiration, and river discharge across the terrestrial pan-Arctic over the past several decades from observations and a suite of coupled general circulation models (GCMs). Trends in freshwater flux and storage derived from observations across the Arctic Ocean and surrounding seas are also described. With few exceptions, precipitation, evapotranspiration, and river discharge fluxes from observations and the GCMs exhibit positive trends. Significant positive trends above the 90% confidence level, however, are not present for all of the observations. Greater confidence in the GCM trends arises through lower interannual variability relative to trend magnitude. Put another way, intrinsic variability in the observations tends to limit confidence in trend robustness. Ocean fluxes are less certain, primarily because of the lack of long-term observations. Where available, salinity and volume flux data suggest some decrease in saltwater inflow to the Barents Sea (i.e., a decrease in freshwater outflow) in recent decades. A decline in freshwater storage across the central Arctic Ocean and suggestions that large-scale circulation plays a dominant role in freshwater trends raise questions as to whether Arctic Ocean freshwater flows are intensifying. Although oceanic fluxes of freshwater are highly variable and consistent trends are difficult to verify, the other components of the Arctic FWC do show consistent positive trends over recent decades. The broad-scale increases provide evidence that the Arctic FWC is experiencing intensification. Efforts that aim to develop an adequate

  7. Inactivation of Paragonimus westermani metacercariae in soy sauce-marinated and frozen freshwater crabs.

    Science.gov (United States)

    Kim, Tae Im; Oh, Se-Ra; Dai, Fuhong; Yang, Hyun-Jong; Ha, Sang-Do; Hong, Sung-Jong

    2017-03-01

    Soy sauce-marinated freshwater crabs (Eriocheir japonicus) are a source of human paragonimiasis. The viability of Paragonimus westermani metacercariae (PwMc) in marinated crabs was investigated in an experimental setting. The PwMc collected from freshwater crayfish were inoculated into freshwater crabs, which were then frozen or marinated in soy sauce. All PwMc in the freshwater crabs were inactivated after freezing for 48 h at -20 °C and after freezing for 12 h at -40 °C. After marinating for 32 days, the survival rate of PwMc in 5% NaCl soy sauce was 50%, in 7.5% NaCl soy sauce it was 33.3%, and in 10.0% NaCl soy sauce it was 31.3%. When marinated for 64 days, all PwMc were inactivated in all experimental groups. These results revealed that freezing and soy sauce marination were detrimental to the survival of PwMc in freshwater crabs. Specifically, freezing crabs for more than 48 h or soaking them in soy sauce containing at least 5.0% NaCl for 64 days can inactivate PwMc. These results can inform the production of the traditional Korean soy sauce-marinated freshwater crabs known as gejang.

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

    Directory of Open Access Journals (Sweden)

    Tharoeun Thap

    2016-04-01

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

  9. The development of a GIS atlas of southern African freshwater fish ...

    African Journals Online (AJOL)

    The development of a GIS atlas of southern African freshwater fish. LEP Scott, PH Skelton, AJ Booth, L Verheust. Abstract. A geographic information systems (GIS) based atlas of southern African freshwater fish has been developed for the SADC countries. The JLB Smith Institute of Ichthyology, in collaboration with ALCOM, ...

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

    Science.gov (United States)

    Li, D.; Li, S.

    2016-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Jeanette K Howard

    Full Text Available The ranges and abundances of species that depend on freshwater habitats are declining worldwide. Efforts to counteract those trends are often hampered by a lack of information about species distribution and conservation status and are often strongly biased toward a few well-studied groups. We identified the 3,906 vascular plants, macroinvertebrates, and vertebrates native to California, USA, that depend on fresh water for at least one stage of their life history. We evaluated the conservation status for these taxa using existing government and non-governmental organization assessments (e.g., endangered species act, NatureServe, created a spatial database of locality observations or distribution information from ~400 data sources, and mapped patterns of richness, endemism, and vulnerability. Although nearly half of all taxa with conservation status (n = 1,939 are vulnerable to extinction, only 114 (6% of those vulnerable taxa have a legal mandate for protection in the form of formal inclusion on a state or federal endangered species list. Endemic taxa are at greater risk than non-endemics, with 90% of the 927 endemic taxa vulnerable to extinction. Records with spatial data were available for a total of 2,276 species (61%. The patterns of species richness differ depending on the taxonomic group analyzed, but are similar across taxonomic level. No particular taxonomic group represents an umbrella for all species, but hotspots of high richness for listed species cover 40% of the hotspots for all other species and 58% of the hotspots for vulnerable freshwater species. By mapping freshwater species hotspots we show locations that represent the top priority for conservation action in the state. This study identifies opportunities to fill gaps in the evaluation of conservation status for freshwater taxa in California, to address the lack of occurrence information for nearly 40% of freshwater taxa and nearly 40% of watersheds in the state, and to

  12. Rhythmic patterns in ancient shells: Can we reconstruct sub-annual cyclicity in trace element and stable isotope profiles from rudist bivalves?

    Science.gov (United States)

    de Winter, N.; Sinnesael, M.; Vansteenberge, S.; Goderis, S.; Snoeck, C.; Van Malderen, S. J. M.; Vanhaecke, F. F.; Claeys, P.

    2017-12-01

    Well-preserved shells of Torreites rudists from the Late Campanian Saiwan Formation in Oman exhibit fine internal layering. These fine (±20 µm) laminae are rhythmically bundled (±400 µm) and subdivide the shells' larger scale annual lamination (±15 mm), suggesting the presence of several interfering cycles in shell growth rate. The aim of the present study is to determine the duration and chemical signature of these rhythmic variations in shell composition. To achieve this, a range of micro-analytical techniques is applied on cross sections through the shells. Firstly, microscopy-based layer counting and colorimetric analysis are carried out on thin sections of shell calcite. Secondly, X-Ray Fluorescence (XRF) and Fourier Transform InfraRed (FTIR) mapping of cross sections of the shells reveal chemical and structural differences between laminae in 2D. Thirdly, high-resolution XRF (25 µm) and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS; 10 µm) trace element profiles are used to quantify variations in chemical composition between shell laminae. Fourthly, annual chronology is established based on micro-sampled stable carbon and oxygen stable isotope measurements (250 µm) along the growth axis of the shells. Finally, spectral analysis routines are applied to extract rhythmic patterns matched to the shell laminae from the structural, chemical and colorimetric data. Combining these methods allows for a full evaluation of the structural and chemical characteristics as well as the timing of sub-annual lamination in rudist shells. The results of this study shed light on the external factors that influenced growth rates in rudist bivalves. A better understanding of the timing of deposition of these laminae allows them to be used to improve age models of geochemical records in rudist shells. Characterization of small scale variations in shell composition will characterize the uncertainties contained within lower resolution proxy records from

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

    Science.gov (United States)

    Sammel, Alison; McMartin, Dena; Arbuthnott, Katherine

    2018-01-01

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

  14. 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

  15. Effects of salinity on freshwater fishes in coastal plain drainages in the southeastern U.S.

    Science.gov (United States)

    Peterson, Mark S.; Meador, Michael R.

    1994-01-01

    This review focuses on the influence of salinity on freshwater fishes in coastal rivers and estuaries of the southeastern U.S. Influences of salinity on freshwater fish species can be explained partly through responses evidenced by behavior, physiology, growth, reproduction, and food habits during all aspects of life history. Factors influencing the rate of salinity change affect the community structure and dynamics of freshwater fishes in brackish environments. Our understanding of the relation between salinity and the life history of freshwater fishes is limited because little ecological research has been conducted in low-salinity habitats that we consider an “interface” between freshwater streams and the estuary proper. Much of the available data are descriptive in nature and describe best general patterns, but more specific studies are required to better determine the influence of salinity on freshwater fishes. Improved understanding of the influence of human-induced changes on the productivity and viability of these important systems will require a new research focus.

  16. Salinity tolerances and use of saline environments by freshwater turtles: implications of sea level rise.

    Science.gov (United States)

    Agha, Mickey; Ennen, Joshua R; Bower, Deborah S; Nowakowski, A Justin; Sweat, Sarah C; Todd, Brian D

    2018-03-25

    The projected rise in global mean sea levels places many freshwater turtle species at risk of saltwater intrusion into freshwater habitats. Freshwater turtles are disproportionately more threatened than other taxa; thus, understanding the role of salinity in determining their contemporary distribution and evolution should be a research priority. Freshwater turtles are a slowly evolving lineage; however, they can adapt physiologically or behaviourally to various levels of salinity and, therefore, temporarily occur in marine or brackish environments. Here, we provide the first comprehensive global review on freshwater turtle use and tolerance of brackish water ecosystems. We link together current knowledge of geographic occurrence, salinity tolerance, phylogenetic relationships, and physiological and behavioural mechanisms to generate a baseline understanding of the response of freshwater turtles to changing saline environments. We also review the potential origins of salinity tolerance in freshwater turtles. Finally, we integrate 2100 sea level rise (SLR) projections, species distribution maps, literature gathered on brackish water use, and a phylogeny to predict the exposure of freshwater turtles to projected SLR globally. From our synthesis of published literature and available data, we build a framework for spatial and phylogenetic conservation prioritization of coastal freshwater turtles. Based on our literature review, 70 species (∼30% of coastal freshwater turtle species) from 10 of the 11 freshwater turtle families have been reported in brackish water ecosystems. Most anecdotal records, observations, and descriptions do not imply long-term salinity tolerance among freshwater turtles. Rather, experiments show that some species exhibit potential for adaptation and plasticity in physiological, behavioural, and life-history traits that enable them to endure varying periods (e.g. days or months) and levels of saltwater exposure. Species that specialize on

  17. The effect of Congo River freshwater discharge on Eastern Equatorial Atlantic climate variability

    Energy Technology Data Exchange (ETDEWEB)

    Materia, Stefano [Centro Euro-Mediterraneo per i Cambiamenti Climatici, Bologna (Italy); Gualdi, Silvio; Navarra, Antonio [Centro Euro-Mediterraneo per i Cambiamenti Climatici, Bologna (Italy); Istituto Nazionale di Geofisica e Vulcanologia, Bologna (Italy); Terray, Laurent [Sciences de l' Univers au CERFACS, URA1875 CERFACS/CNRS, Toulouse (France)

    2012-11-15

    The surface ocean explains a considerable part of the inter-annual Tropical Atlantic variability. The present work makes use of observational datasets to investigate the effect of freshwater flow on sea surface salinity (SSS) and temperature (SST) in the Gulf of Guinea. In particular, the Congo River discharges a huge amount of freshwater into the ocean, affecting SSS in the Eastern Equatorial Atlantic (EEA) and stratifying the surface layers. The hypothesis is that an excess of river runoff emphasize stratification, influencing the ocean temperature. In fact, our findings show that SSTs in the Gulf of Guinea are warmer in summers following an anomalously high Congo spring discharge. Vice versa, when the river discharges low freshwater, a cold anomaly appears in the Gulf. The response of SST is not linear: temperature anomalies are considerable and long-lasting in the event of large freshwater flow, while in dry years they are less remarkable, although still significant. An excess of freshwater seems able to form a barrier layer, which inhibits vertical mixing and the entrainment of the cold thermocline water into the surface. Other processes may contribute to SST variability, among which the net input of atmospheric freshwater falling over EEA. Likewise the case of continental runoff from Congo River, warm anomalies occur after anomalously rainy seasons and low temperatures follow dry seasons, confirming the effect of freshwater on SST. However, the two sources of freshwater anomaly are not in phase, so that it is possible to split between atypical SST following continental freshwater anomalies and rainfall anomalies. Also, variations in air-sea fluxes can produce heating and cooling of the Gulf of Guinea. Nevertheless, atypical SSTs cannot be ascribed to fluxes, since the temperature variation induced by them is not sufficient to explain the SST anomalies appearing in the Gulf after anomalous peak discharges. The interaction processes between river runoff, sea

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

    OpenAIRE

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

    2017-01-01

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

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

    OpenAIRE

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

    2011-01-01

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

  20. Freshwater biodiversity and aquatic insect diversification.

    Science.gov (United States)

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

    2014-01-01

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

  1. Freshwater fishes of Tsitsikamma National Park

    Directory of Open Access Journals (Sweden)

    I.A. Russell

    2002-12-01

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

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

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  3. Assessment of human-natural system characteristics influencing global freshwater supply vulnerability

    Science.gov (United States)

    Padowski, Julie C.; Gorelick, Steven M.; Thompson, Barton H.; Rozelle, Scott; Fendorf, Scott

    2015-10-01

    Global freshwater vulnerability is a product of environmental and human dimensions, however, it is rarely assessed as such. Our approach identifies freshwater vulnerability using four broad categories: endowment, demand, infrastructure, and institutions, to capture impacts on natural and managed water systems within the coupled human-hydrologic environment. These categories are represented by 19 different endogenous and exogenous characteristics affecting water supply vulnerability. By evaluating 119 lower per capita income countries (Yemen and Djibouti nearly as vulnerable. Surprising similarities in vulnerability were also found among geographically disparate nations such as Vietnam, Sri Lanka, and Guatemala. Determining shared patterns of freshwater vulnerability provides insights into why water supply vulnerabilities are manifested in human-water systems at the national scale.

  4. 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

  5. RNA sequencing analysis of transcriptional change in the freshwater mussel Elliptio complanata after environmentally relevant sodium chloride exposure.

    Science.gov (United States)

    Robertson, Laura S; Galbraith, Heather S; Iwanowicz, Deborah; Blakeslee, Carrie J; Cornman, R Scott

    2017-09-01

    To identify potential biomarkers of salt stress in a freshwater sentinel species, we examined transcriptional responses of the common mussel Elliptio complanata to controlled sodium chloride (NaCl) exposures. Ribonucleic acid sequencing (RNA-Seq) of mantle tissue identified 481 transcripts differentially expressed in adult mussels exposed to 2 ppt NaCl (1.2 ppt chloride) for 7 d, of which 290 had nonoverlapping intervals. Differentially expressed gene categories included ion and transmembrane transport, oxidoreductase activity, maintenance of protein folding, and amino acid metabolism. The rate-limiting enzyme for synthesis of taurine, an amino acid frequently linked to osmotic stress in aquatic species, was upregulated, as was the transmembrane ion pump sodium/potassium adenosine 5'-triphosphatase. These patterns confirm a primary transcriptional response to the experimental dose, albeit likely overlapping with nonspecific secondary stress responses. Substantial involvement of the heat shock protein 70 chaperone family and the water-transporting aquaporin family was not detected, however, in contrast to some studies in other bivalves. A subset of the most significantly regulated genes was confirmed by quantitative polymerase chain reaction in an independent sample. Cluster analysis showed separation of mussels exposed to 2 ppt NaCl from control mussels in multivariate space, but mussels exposed to 1 ppt NaCl were largely indistinguishable from controls. Transcriptome-scale analysis of salt exposure under laboratory conditions efficiently identified candidate biomarkers for further functional analysis and field validation. Environ Toxicol Chem 2017;36:2352-2366. © Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America. © 2017 SETAC.

  6. [BIODIVERSITY OF ACANTHOCEPHALANS (ACANTHOCEPHALA) IN FRESHWATER FISHES OF ASIATIC SUB-ARCTIC REGION].

    Science.gov (United States)

    Atrashkevich, G I; Mikhailova, E I; Orlovskaya, O M; Pospekhov, V V

    2016-01-01

    The analysis of taxonomical and ecological diversity of acanthocephalans in fishes of Asiatic sub-Arctic region freshwaters, summarizing changes in modern views on species composition, life cycles, and ecology of background groups of these parasites is given. A priority role of studies provided by O. N. Bauer and his scientific school in organization and development of these aspects of acanthocephalology is demonstrated. Special attention is paid to the assessment of acanthocephalan biodiversity of the genus Neoechinorhynchus, the background group of freshwater fish parasites of the Asiatic sub-Arctic region, and an original key for their species is given. The distribution of acanthocephalans of the genus Acanthocephalus in northeastern Asia is analyzed and prospective study of this parasite group, evolutionary associated with freshwater isopods of the genus Asellus as intermediate hosts, is outlined. The absence of documented evidences on intermediate hosts of other background parasites of freshwater fishes in the region, acanthocephalans of the genus Metechinorhynchus, is revealed. It is assumed that subsequent taxonomic revisions based both on morphological and molecular genetic studies are necessary for the reliable revealing of species composition in each genus of the background acanthocephalans from freshwater fishes of Northern Asia. Theoretical significance of the study of acanthocephalan life cycles and revealing their natural intermediate hosts for the reliable estimation of structural and functional organization of their host-parasite systems in different parts of the range is substantiated and the possibility of the distribution of taxonomic conclusions in new territories is analyzed. A brief annotated taxonomical list of freshwater acanthocephalans of the Asiatic sub-Arctic region is given.

  7. Decadal phytoplankton dynamics in response to episodic climatic disturbances in a subtropical deep freshwater ecosystem.

    Science.gov (United States)

    Ko, Chia-Ying; Lai, Chao-Chen; Hsu, Huang-Hsiung; Shiah, Fuh-Kwo

    2017-02-01

    Information of the decadal timescale effects of episodic climatic disturbances (i.e., typhoons) on phytoplankton in freshwater ecosystems have received less attention and fewer seasonal evaluations partly due to the lack of long-term time-series monitoring data in typhoon prevailing areas. Through field observations of a total 36 typhoon cases in a subtropical deep freshwater ecosystem in the period of 2005-2014, we quantified phytoplankton biomass, production and growth rate in response to meteorological and hydrological changes in the weeks before, during and after typhoons between summer and autumn, and also investigated the effects of typhoon characteristics on the aforementioned phytoplankton responses. The results showed that phytoplankton exposed to typhoon disturbances generally exhibited an increasing trend over the weeks before, during and after typhoons in summer but varied in autumn. The correlations and multivariate regressions showed different contributions of meteorological and hydrological variables to individual phytoplankton responses before, during and after typhoons between seasons. The post-typhoon weeks (i.e., within two weeks after a typhoon had passed) were especially important for the timeline of phytoplankton increases and with a detectable seasonal variation that the chlorophyll a concentration significantly increased in autumn whereas both primary production and growth rate were associated with significant changes in summer. Additionally, phytoplankton responses during the post-typhoon weeks were significantly different between discrete or continuous types of typhoon events. Our work illustrated the fact that typhoons did influence phytoplankton responses in the subtropical deep freshwater ecosystem and typhoon passages in summer and autumn affected the phytoplankton dynamics differently. Nevertheless, sustained and systematic monitoring in order to advance our understanding of the role of typhoons between seasons in the modulation of

  8. Overwintering of sea trout (Salmo trutta) in freshwater

    DEFF Research Database (Denmark)

    Thomsen, Dennis; Koed, Anders; Nielsen, Christian

    2007-01-01

    Brown trout (Salmo trutta) show large phenotypic plasticity. Juveniles may reside in their native freshwater habitat until maturation or migrate into the ocean as 1- to 3-year-old smolts. Sea-going fish (sea trout) reside at sea for 2-3 years until migrating back to their native stream for reprod......Brown trout (Salmo trutta) show large phenotypic plasticity. Juveniles may reside in their native freshwater habitat until maturation or migrate into the ocean as 1- to 3-year-old smolts. Sea-going fish (sea trout) reside at sea for 2-3 years until migrating back to their native stream...... for reproduction. However, immature fish may leave the ocean during their first or second winter at sea and overwinter in freshwater. The question is why does this occur? We tested the hypothesis that hypo-osmoregulatory capacity is compromised by low temperature in two coastal sea trout populations, one...... representing high salinity and the other, low salinity. Immature sea-run trout were caught in lower parts of two rivers during winter and acclimated to laboratory conditions. Subgroups were challenged with high salinity or low water temperature or both, and their osmoregulatory performance was investigated...

  9. 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.

  10. An ultrasonic method for separation of epiphytic microbes from freshwater submerged macrophytes.

    Science.gov (United States)

    Cai, Xianlei; Gao, Guang; Yang, Jing; Tang, Xiangming; Dai, Jiangyu; Chen, Dan; Song, Yuzhi

    2014-07-01

    Epiphytic microbes are common inhabitants of freshwater submerged macrophytes, which play an important role in aquatic ecosystems. An important precondition for studying the epiphytic microbes is having an effective method of separating the attached microbes from the host macrophytes. We developed an ultrasound-based method for separating epiphytic microbes from freshwater submerged macrophytes, optimized the conditions of ultrasonic separation with an orthogonal experimental design, and compared the optimized ultrasonic method with manual separation. This method can be particularly useful for freshwater submerged macrophytes having a complex morphology. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. 2008 NWFSC Tidal Freshwater Genetics Results

    Energy Technology Data Exchange (ETDEWEB)

    David Teel

    2009-05-01

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

  12. Validated methodology for quantifying infestation levels of dreissenid mussels in environmental DNA (eDNA) samples

    OpenAIRE

    Peñarrubia Lozano, Luis; Alcaraz Cazorla, Carles; Vaate, Abraham bij de; Sanz Ball-llosera, Núria; Pla Zanuy, Carles; Vidal Fàbrega, Oriol; Viñas de Puig, Jordi

    2016-01-01

    The zebra mussel (Dreissena polymorpha Pallas, 1771) and the quagga mussel (D. rostriformis Deshayes, 1838) are successful invasive bivalves with substantial ecological and economic impacts in freshwater systems once they become established. Since their eradication is extremely difficult, their detection at an early stage is crucial to prevent spread. In this study, we optimized and validated a qPCR detection method based on the histone H2B gene to quantify combined infestation levels of zebr...

  13. Outline of design and construction work related to the installation of freshwater storage tank at Higashidori Nuclear Power Station

    International Nuclear Information System (INIS)

    Ozaki, Mitsuhiro; Yamaguchi, Kazuhide; Suzuki, Takeshi

    2017-01-01

    Tohoku Electric Power Co., Ltd., at its Higashidori Nuclear Power Station, is promoting the installation of safety measure facilities as an effort to restart the operation. It is implementing a freshwater storage tank installation work to secure core cooling function at the time of severe accident occurrence. Construction started in June 2014, drilling and construction of the framework have advanced while paying due attention to quality assurance, and affiliated facilities are currently under construction. This paper reports the outline of planning, design, and construction work of this project. (A.O.)

  14. Fast evolution from precast bricks: genomics of young freshwater populations of threespine stickleback Gasterosteus aculeatus.

    Directory of Open Access Journals (Sweden)

    Nadezhda V Terekhanova

    2014-10-01

    Full Text Available Adaptation is driven by natural selection; however, many adaptations are caused by weak selection acting over large timescales, complicating its study. Therefore, it is rarely possible to study selection comprehensively in natural environments. The threespine stickleback (Gasterosteus aculeatus is a well-studied model organism with a short generation time, small genome size, and many genetic and genomic tools available. Within this originally marine species, populations have recurrently adapted to freshwater all over its range. This evolution involved extensive parallelism: pre-existing alleles that adapt sticklebacks to freshwater habitats, but are also present at low frequencies in marine populations, have been recruited repeatedly. While a number of genomic regions responsible for this adaptation have been identified, the details of selection remain poorly understood. Using whole-genome resequencing, we compare pooled genomic samples from marine and freshwater populations of the White Sea basin, and identify 19 short genomic regions that are highly divergent between them, including three known inversions. 17 of these regions overlap protein-coding genes, including a number of genes with predicted functions that are relevant for adaptation to the freshwater environment. We then analyze four additional independently derived young freshwater populations of known ages, two natural and two artificially established, and use the observed shifts of allelic frequencies to estimate the strength of positive selection. Adaptation turns out to be quite rapid, indicating strong selection acting simultaneously at multiple regions of the genome, with selection coefficients of up to 0.27. High divergence between marine and freshwater genotypes, lack of reduction in polymorphism in regions responsible for adaptation, and high frequencies of freshwater alleles observed even in young freshwater populations are all consistent with rapid assembly of G. aculeatus

  15. Fast evolution from precast bricks: genomics of young freshwater populations of threespine stickleback Gasterosteus aculeatus.

    Science.gov (United States)

    Terekhanova, Nadezhda V; Logacheva, Maria D; Penin, Aleksey A; Neretina, Tatiana V; Barmintseva, Anna E; Bazykin, Georgii A; Kondrashov, Alexey S; Mugue, Nikolai S

    2014-10-01

    Adaptation is driven by natural selection; however, many adaptations are caused by weak selection acting over large timescales, complicating its study. Therefore, it is rarely possible to study selection comprehensively in natural environments. The threespine stickleback (Gasterosteus aculeatus) is a well-studied model organism with a short generation time, small genome size, and many genetic and genomic tools available. Within this originally marine species, populations have recurrently adapted to freshwater all over its range. This evolution involved extensive parallelism: pre-existing alleles that adapt sticklebacks to freshwater habitats, but are also present at low frequencies in marine populations, have been recruited repeatedly. While a number of genomic regions responsible for this adaptation have been identified, the details of selection remain poorly understood. Using whole-genome resequencing, we compare pooled genomic samples from marine and freshwater populations of the White Sea basin, and identify 19 short genomic regions that are highly divergent between them, including three known inversions. 17 of these regions overlap protein-coding genes, including a number of genes with predicted functions that are relevant for adaptation to the freshwater environment. We then analyze four additional independently derived young freshwater populations of known ages, two natural and two artificially established, and use the observed shifts of allelic frequencies to estimate the strength of positive selection. Adaptation turns out to be quite rapid, indicating strong selection acting simultaneously at multiple regions of the genome, with selection coefficients of up to 0.27. High divergence between marine and freshwater genotypes, lack of reduction in polymorphism in regions responsible for adaptation, and high frequencies of freshwater alleles observed even in young freshwater populations are all consistent with rapid assembly of G. aculeatus freshwater genotypes

  16. Ecological studies of wood-boring bivalves in the vicinity of the Oyster Creek Nuclear Generating Station. Progress report Sep-Nov 81

    International Nuclear Information System (INIS)

    Hoagland, K.E.; Crocket, L.

    1982-06-01

    The species composition, distribution, and population dynamics of wood-boring bivalves are being studied in the vicinity of the Oyster Creek Nuclear Generating Station, Barnegat Bay, New Jersey. Untreated wood test panels are used to collect organisms at 12 stations. Physiological tolerances of 3 species are also under investigation in the laboratory. Competition among the species is being analyzed. In the fall of 1981, Teredo bartschi remained in Oyster Creek despite continuous prolonged outages of the Oyster Creek Nuclear Generating Station

  17. Value-chain analysis of freshwater apple snail (Pila globosa used for on-farm feeds in the freshwater prawn farming sector in Bangladesh

    Directory of Open Access Journals (Sweden)

    S.A.A. Nahid

    2013-12-01

    Full Text Available Growth of the freshwater prawn (Macrobrachium rosenbergii sector in Bangladesh since 1970s has been supported by natural availability of freshwater apple snail (Pila globosa, used for on-farm prawn feeds. The present study identified the current configuration of the value-chain benefits and constraints of freshwater apple snail in south-western Bangladesh in August 2011, based upon Rapid Market Appraisal (RMA approach. The site of snail collection was Chanda Beel in Gopalganj district, while trading, processing and final consumption was represented by Rayer Mahal Bazar in Khulna district. There were seven different nodes recognized throughout the value chain. Snail marketing was identified as a seasonal business and took place during June to November each year. Between 1995 and 2011 the price of whole snail, meat and shell has increased by 800%, 325% and 315%, respectively. The abundance of snail had been reduced and its demand has increased due to the expansion of the prawn farming industry. Prawn farmers preferred snail meat due to its’ low cost (US$ 0.21 kg-1 as a source of protein compared to commercial prawn feed (US$ 0.41 kg-1. Snail harvesting and processing were considered as additional livelihood options for the poor, where 60% of the labour involved in snail harvesting were women, and 95% the de-shelling workforce. Induced breeding in captivity and sustainable management in nature as well as development of commercial production of apple snails might reduce the pressure on ecosystems and positively contributed to the continued expansion of freshwater prawn farming in Bangladesh.

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

    Science.gov (United States)

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

    2015-12-01

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

  19. Manganese in the shell of the bivalve Mytilus edulis: Seawater Mn or physiological control?

    Science.gov (United States)

    Freitas, Pedro S.; Clarke, Leon J.; Kennedy, Hilary; Richardson, Christopher A.

    2016-12-01

    Manganese in the shell calcite of marine bivalves has been suggested to reflect ambient seawater Mn concentrations, thus providing a high-resolution archive of past seawater Mn concentrations. However, a quantitative relationship between seawater Mn and shell Mn/Ca ratios, as well as clear understanding of which process(es) control(s) shell Mn/Ca, are still lacking. Blue mussels, Mytilus edulis, were grown in a one-year duration field experiment in the Menai Strait, U.K., to study the relationship between seawater particulate and dissolved Mn2+ concentrations and shell calcite Mn/Ca ratios. Shell Mn/Ca showed a well-defined intra-annual double-peak, with maximum values during early spring and early summer and low values during autumn and winter. Seawater particulate Mn peaked during winter and autumn, with a series of smaller peaks during spring and summer, whereas dissolved Mn2+ exhibited a marked single maximum during late-spring to early-summer, being low during the remainder of the year. Consequently, neither seawater particulate Mn nor dissolved Mn2+ concentrations explain the intra-annual variation of shell Mn/Ca ratios. A physiological control on shell Mn/Ca ratios is evident from the strong similarity and timing of the double-peaked intra-annual variations of Mn/Ca and shell growth rate (SGR), the latter corresponding to periods of increased metabolic activity (as indicated by respiration rate). It is thus likely that in M. edulis SGR influences shell Mn/Ca by altering the concentration or activity of Mn2+ within the extra-pallial fluid (EPF), by changing the flux of Mn into or the proportion of protein bound Mn within the EPF. By linking shell Mn/Ca ratios to the endogenous and environmental factors that determine growth and metabolic activity, this study helps to explain the lack of a consistent relationship between shell Mn/Ca in marine bivalve shell calcite and seawater particulate and dissolved Mn2+ concentrations. The use of Mn content from M. edulis

  20. Effects of pollution on freshwater fish

    International Nuclear Information System (INIS)

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

    1974-01-01

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

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

    DEFF Research Database (Denmark)

    Herrmann, Martina; Schramm, Andreas

    2007-01-01

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

  2. 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...

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

    African Journals Online (AJOL)

    SARAH

    2014-01-31

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

  4. The First Detailed 2H and 18O Isoscapes of Freshwater in Scotland

    Science.gov (United States)

    Meier-Augenstein, W.; Hoogewerff, J.; Kemp, H. F.; Frew, D.

    2012-04-01

    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 freshwater quality by the Scottish Environmental Protection Agency (SEPA) fulfils the legislative requirements but new scientific methods involving stable isotope analysis present an opportunity for delivering on current and nascent government policies [1] and gaining a greater understanding of Scottish waters and their importance in the context of climate change, environmental sustainability and the aforementioned functions. In brief, 2H and 18O isoscapes of Scottish freshwater could be used to support fundamental and applied research in: • Climate change - These first ever isoscapes will provide a baseline against which future environmental impact can be assessed due to changes in the characteristic isotope composition of freshwater lochs and reservoirs. • 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 berries and Scottish Whisky. During 2011, freshwater samples were collected with the support of SEPA from more than 80 freshwater lochs and reservoirs across Scotland. Here we present the result of the 2H and 18O stable isotope analyses of these water samples together with the first isoscapes generated based on these data. [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's National Food and Drink Policy (2009); Scottish Planning Policy Environmental Report (2009); Scottish Planning Policy (SPP) 15 Planning for Rural Development (2005); National Planning Policy Guideline (NPPG) 14: Natural Heritage (1999).

  5. Modulation of pumping rate by two species of marine bivalve molluscs in response to neurotransmitters: Comparison of in vitro and in vivo results.

    Science.gov (United States)

    Frank, Dana M; Deaton, Lewis; Shumway, Sandra E; Holohan, Bridget A; Ward, J Evan

    2015-07-01

    Most studies regarding the neuroanatomy and neurophysiology of molluscan ctenidia have focused on isolated ctenidial tissue preparations. This study investigated how bivalve molluscs modulate their feeding rates by examining the effects of a variety of neurotransmitters, including serotonin, dopamine, and the dopamine agonist apomorphine on both isolated ctenidial tissue and in intact members of two commercially important bivalve species: the blue mussel, Mytilus edulis; and the bay scallop Argopecten irradians. In particular, we examined the effect of changes in: 1) beat of the lateral cilia (in vitro), 2) distance between ctenidial filaments and/or plicae (in vivo), and 3) diameter of the siphonal openings (in vivo) on alteration of bulk water flow through the mantle cavity. Important differences were found between isolated tissue and whole animals, and between species. Drugs that stimulated ciliary beat in vitro did not increase water processing rate in vivo. None of the treatments increased water flow through the mantle cavity of intact animals. Results suggest that A. irradians was primarily modulating lateral ciliary activity, while M. edulis appeared to have a number of ways to control water processing activity, signifying that the two species may have different compensatory and regulatory mechanisms controlling feeding activity. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Bioacessibilidade in vitro das biotoxinas marinhas ácido ocadaico, dinofisistoxina-2 e seus derivados em bivalves crus e cozinhados

    OpenAIRE

    Manita, Diana Filipa Pereira

    2017-01-01

    Dissertação de Mestrado em Segurança Alimentar As biotoxinas marinhas mais frequentes e abundantes em Portugal são as toxinas lipofílicas, nomeadamente as toxinas do grupo do ácido ocadaico (AO), que inclui as dinofisistoxinas (DTX1 e DTX2) e os seus derivados (DTX3), responsáveis pela intoxicação diarreica (DSP diarrhetic shellfish poisoning). A investigação da presença, variabilidade e transformação de biotoxinas marinhas em moluscos bivalves é de elevada importância não só p...

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

    International Nuclear Information System (INIS)

    Faupel, Michael; Ristau, Kai; Traunspurger, Walter

    2012-01-01

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

  8. Adaptive management in the context of barriers in European freshwater ecosystems.

    Science.gov (United States)

    Birnie-Gauvin, Kim; Tummers, Jeroen S; Lucas, Martyn C; Aarestrup, Kim

    2017-12-15

    Many natural habitats have been modified to accommodate for the presence of humans and their needs. Infrastructures - such as hydroelectric dams, weirs, culverts and bridges - are now a common occurrence in streams and rivers across the world. As a result, freshwater ecosystems have been altered extensively, affecting both biological and geomorphological components of the habitats. Many fish species rely on these freshwater ecosystems to complete their lifecycles, and the presence of barriers has been shown to reduce their ability to migrate and sustain healthy populations. In the long run, barriers may have severe repercussions on population densities and dynamics of aquatic animal species. There is currently an urgent need to address these issues with adequate conservation approaches. Adaptive management provides a relevant approach to managing barriers in freshwater ecosystems as it addresses the uncertainties of dealing with natural systems, and accommodates for future unexpected events, though this approach may not be suitable in all instances. A literature search on this subject yielded virtually no output. Hence, we propose a step-by-step guide for implementing adaptive management, which could be used to manage freshwater barriers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. A global review of freshwater crayfish temperature tolerance, preference, and optimal growth

    Science.gov (United States)

    Westhoff, Jacob T.; Rosenberger, Amanda E.

    2016-01-01

    Conservation efforts, environmental planning, and management must account for ongoing ecosystem alteration due to a changing climate, introduced species, and shifting land use. This type of management can be facilitated by an understanding of the thermal ecology of aquatic organisms. However, information on thermal ecology for entire taxonomic groups is rarely compiled or summarized, and reviews of the science can facilitate its advancement. Crayfish are one of the most globally threatened taxa, and ongoing declines and extirpation could have serious consequences on aquatic ecosystem function due to their significant biomass and ecosystem roles. Our goal was to review the literature on thermal ecology for freshwater crayfish worldwide, with emphasis on studies that estimated temperature tolerance, temperature preference, or optimal growth. We also explored relationships between temperature metrics and species distributions. We located 56 studies containing information for at least one of those three metrics, which covered approximately 6 % of extant crayfish species worldwide. Information on one or more metrics existed for all 3 genera of Astacidae, 4 of the 12 genera of Cambaridae, and 3 of the 15 genera of Parastacidae. Investigations employed numerous methodological approaches for estimating these parameters, which restricts comparisons among and within species. The only statistically significant relationship we observed between a temperature metric and species range was a negative linear relationship between absolute latitude and optimal growth temperature. We recommend expansion of studies examining the thermal ecology of freshwater crayfish and identify and discuss methodological approaches that can improve standardization and comparability among studies.

  10. 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...

  11. 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...

  12. 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 ...

  13. 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

  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. Persistent organochlorine pesticide residues in freshwater systems ...

    African Journals Online (AJOL)

    DRINIE

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

  16. Practical aids for freshwater spill response

    International Nuclear Information System (INIS)

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

    1993-01-01

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

  17. 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

  18. Dinoflagellates associated with freshwater sponges from the ancient lake baikal.

    Science.gov (United States)

    Annenkova, Natalia V; Lavrov, Dennis V; Belikov, Sergey I

    2011-04-01

    Dinoflagellates are a diverse group of protists that are common in both marine and freshwater environments. While the biology of marine dinoflagellates has been the focus of several recent studies, their freshwater relatives remain little-investigated. In the present study we explore the diversity of dinoflagellates in Lake Baikal by identifying and analyzing dinoflagellate sequences for 18S rDNA and ITS-2 from total DNA extracted from three species of endemic Baikalian sponges (Baikalospongia intermedia,Baikalospongia rectaand Lubomirskia incrustans). Phylogenetic analyses of these sequences revealed extensive dinoflagellate diversity in Lake Baikal. We found two groups of sequences clustering within the order Suessiales, known for its symbiotic relationships with various invertebrates. Thus they may be regarded as potential symbionts of Baikalian sponges. In addition,Gyrodinium helveticum, representatives from the genus Gymnodinium, dinoflagellates close to the family Pfiesteriaceae, and a few dinoflagellates without definite affiliation were detected. No pronounced difference in the distribution of dinoflagellates among the studied sponges was found, except for the absence of the Piscinoodinium-like dinoflagellates inL. incrustans. To the best of our knowledge, this is the first study of the diversity of dinoflagellates in freshwater sponges, the first systematic investigation of dinoflagellate molecular diversity in Lake Baikal and the first finding of members of the order Suessiales as symbionts of freshwater invertebrates. Copyright © 2010 Elsevier GmbH. All rights reserved.

  19. Vegetable oil sources in diets for freshwater angelfish (Pterophyllum scalare, Cichlidae: growth and thermal tolerance

    Directory of Open Access Journals (Sweden)

    A.K. Ikeda

    2011-06-01

    Full Text Available The influence of fatty acid composition of the diets on the productive performance and on cold and heat tolerance of juvenile freshwater angelfish (Pterophyllum scalare, in three different phases, was studied. Phase I studied the productive performance of freshwater angelfish in a completely randomized experimental design with four treatments, canola, linseed, olive and soybean oils and four replicates during 50 days using 192 fish in 16 aquaria. Phase II studied the cold tolerance of juvenile freshwater angelfish using 72 juvenile freshwater angelfish, coming from phase I and maintained in 12 aquaria climatized chamber. The temperature was reduced 1ºC per day, until the observation of 100% fish mortality. Phase III, it was studied the heat tolerance of juvenile freshwater angelfish employing an identical procedure to phase II, but with a daily increase of 1ºC. Significant differences (P>0.05 were not observed for any parameters evaluated. Thus, it was concluded that the type of vegetable oil (canola, linseed, olive and soybean used as a diet supplement did not affect the productive performance, nor the tolerance to cold and heat, of juvenile freshwater angelfish.

  20. 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

  1. Herbivory on freshwater and marine macrophytes

    NARCIS (Netherlands)

    Bakker, Elisabeth S.; Wood, Kevin A.; Pagès, Jordi F.; Veen, G.F.; Christianen, Marjolijn J.A.; Santamaría, Luis; Nolet, Bart A.; Hilt, Sabine

    2016-01-01

    Until the 1990s, herbivory on aquatic vascular plants was considered to be of minor importance, and the predominant view was that freshwater and marine macrophytes did not take part in the food web: their primary fate was the detritivorous pathway. In the last 25 years, a substantial body of

  2. Adaptive management in the context of barriers in European freshwater ecosystems

    DEFF Research Database (Denmark)

    Birnie-Gauvin, Kim; Tummers, Jeroen S.; Lucas, Martyn C.

    2017-01-01

    Many natural habitats have been modified to accommodate for the presence of humans and their needs. Infrastructures e such as hydroelectric dams, weirs, culverts and bridges e are now a common occurrence in streams and rivers across the world. As a result, freshwater ecosystems have been altered...... extensively, affecting both biological and geomorphological components of the habitats. Many fish species rely on these freshwater ecosystems to complete their lifecycles, and the presence of barriers has been shown to reduce their ability to migrate and sustain healthy populations. In the long run, barriers...... may have severe repercussions on population densities and dynamics of aquatic animal species. There is currently an urgent need to address these issues with adequate conservation approaches. Adaptive management provides a relevant approach to managing barriers in freshwater ecosystems as it addresses...

  3. Designing Observation and Modeling Systems to Inform Decisions and Policies on Freshwater Objectives in New Zealand

    Science.gov (United States)

    Baisden, W. T.; Ellis, T.; Rissman, C.; Moore, C.; Matthews, A.

    2016-12-01

    Declines in New Zealand's freshwater quality have led to legislation - the 2014 National Policy Statement on Freshwater Management (NPS-FM) - which requires regional governments to set "objectives" and design policies accordingly. In most regions, increases in freshwater contaminants are derived largely from intensifying agriculture and come as nitrogen, phosphorous or sediment, or a combination thereof. Here, the development and application of N and O isotopes as natural tracers for nitrate is examined as a case study, in the context of a wider hierarchy of observations such as N concentrations, flow and broader hydrochemistry used for NPS-FM implementation. The analysis of N and O isotopes in nitrate provides specific information on sources and removal processes that cannot be obtained by other measurements. Yet, despite considerable development of the technical methodology and environment-specific interpretation, application of measurements has faced barriers. Many may be typical of science in a small advanced nation with a population of 4.5 million, but others are unique due to New Zealand's limited rural population base and large diversity in physical geography, as well as a unique economic reliance on highly productive pastoral agricultural systems. Seventeen different regional governments are empowered to regulate in ways consistent with local consultation and democracy within their catchment boundaries, but with limited resources to align highly technical observational data to policies and decisions, as well as supporting models. The resulting gaps in communication and technical capability combine with a diversity of approaches to pose both challenges and opportunities for development and application of hierarchical observation systems. Success appears to lie in ensuring decision frameworks can be `mapped', so that different frameworks can be compared, and the benefits of sophisticated observations understood directly in relation to influence on regional

  4. Cadmium as toxicant in Freshwater Cyprinid, Labeo rohita

    African Journals Online (AJOL)

    Sajo

    2012-04-24

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

  5. Bryozoans are returning home: recolonization of freshwater ecosystems inferred from phylogenetic relationships.

    Science.gov (United States)

    Koletić, Nikola; Novosel, Maja; Rajević, Nives; Franjević, Damjan

    2015-01-01

    Bryozoans are aquatic invertebrates that inhabit all types of aquatic ecosystems. They are small animals that form large colonies by asexual budding. Colonies can reach the size of several tens of centimeters, while individual units within a colony are the size of a few millimeters. Each individual within a colony works as a separate zooid and is genetically identical to each other individual within the same colony. Most freshwater species of bryozoans belong to the Phylactolaemata class, while several species that tolerate brackish water belong to the Gymnolaemata class. Tissue samples for this study were collected in the rivers of Adriatic and Danube basin and in the wetland areas in the continental part of Croatia (Europe). Freshwater and brackish taxons of bryozoans were genetically analyzed for the purpose of creating phylogenetic relationships between freshwater and brackish taxons of the Phylactolaemata and Gymnolaemata classes and determining the role of brackish species in colonizing freshwater and marine ecosystems. Phylogenetic relationships inferred on the genes for 18S rRNA, 28S rRNA, COI, and ITS2 region confirmed Phylactolaemata bryozoans as radix bryozoan group. Phylogenetic analysis proved Phylactolaemata bryozoan's close relations with taxons from Phoronida phylum as well as the separation of the Lophopodidae family from other families within the Plumatellida genus. Comparative analysis of existing knowledge about the phylogeny of bryozoans and the expansion of known evolutionary hypotheses is proposed with the model of settlement of marine and freshwater ecosystems by the bryozoans group during their evolutionary past. In this case study, brackish bryozoan taxons represent a link for this ecological phylogenetic hypothesis. Comparison of brackish bryozoan species Lophopus crystallinus and Conopeum seurati confirmed a dual colonization of freshwater ecosystems throughout evolution of this group of animals.

  6. Simulations of freshwater lens recharge and salt/freshwater interfaces using the HYDRUS and SWI2 packages for MODFLOW

    Directory of Open Access Journals (Sweden)

    Szymkiewicz Adam

    2018-06-01

    Full Text Available The paper presents an evaluation of the combined use of the HYDRUS and SWI2 packages for MODFLOW as a potential tool for modeling recharge in coastal aquifers subject to saltwater intrusion. The HYDRUS package for MODFLOW solves numerically the one-dimensional form of the Richards equation describing water flow in variablysaturated media. The code computes groundwater recharge to or capillary rise from the groundwater table while considering weather, vegetation, and soil hydraulic property data. The SWI2 package represents in a simplified way variable-density flow associated with saltwater intrusion in coastal aquifers. Combining these two packages within the MODFLOW framework provides a more accurate description of vadose zone processes in subsurface systems with shallow aquifers, which strongly depend upon infiltration. The two packages were applied to a two-dimensional problem of recharge of a freshwater lens in a sandy peninsula, which is a typical geomorphologic form along the Baltic and the North Sea coasts, among other places. Results highlighted the sensitivity of calculated recharge rates to the temporal resolution of weather data. Using daily values of precipitation and potential evapotranspiration produced average recharge rates more than 20% larger than those obtained with weekly or monthly averaged weather data, leading to different trends in the evolution of freshwater-saltwater interfaces. Root water uptake significantly influenced both the recharge rate and the position of the freshwater-saltwater interface. The results were less sensitive to changes in soil hydraulic parameters, which in our study were found to affect average yearly recharge rates by up to 13%.

  7. Combining Remote Temperature Sensing with in-Situ Sensing to Track Marine/Freshwater Mixing Dynamics

    Directory of Open Access Journals (Sweden)

    Margaret McCaul

    2016-08-01

    Full Text Available The ability to track the dynamics of processes in natural water bodies on a global scale, and at a resolution that enables highly localised behaviour to be visualized, is an ideal scenario for understanding how local events can influence the global environment. While advances in in-situ chem/bio-sensing continue to be reported, costs and reliability issues still inhibit the implementation of large-scale deployments. In contrast, physical parameters like surface temperature can be tracked on a global scale using satellite remote sensing, and locally at high resolution via flyovers and drones using multi-spectral imaging. In this study, we show how a much more complete picture of submarine and intertidal groundwater discharge patterns in Kinvara Bay, Galway can be achieved using a fusion of data collected from the Earth Observation satellite (Landsat 8, small aircraft and in-situ sensors. Over the course of the four-day field campaign, over 65,000 in-situ temperatures, salinity and nutrient measurements were collected in parallel with high-resolution thermal imaging from aircraft flyovers. The processed in-situ data show highly correlated patterns between temperature and salinity at the southern end of the bay where freshwater springs can be identified at low tide. Salinity values range from 1 to 2 ppt at the southern end of the bay to 30 ppt at the mouth of the bay, indicating the presence of a freshwater wedge. The data clearly show that temperature differences can be used to track the dynamics of freshwater and seawater mixing in the inner bay region. This outcome suggests that combining the tremendous spatial density and wide geographical reach of remote temperature sensing (using drones, flyovers and satellites with ground-truthing via appropriately located in-situ sensors (temperature, salinity, chemical, and biological can produce a much more complete and accurate picture of the water dynamics than each modality used in isolation.

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

    Science.gov (United States)

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

    2017-04-01

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

  9. Differing responses of the estuarine bivalve Limecola balthica to lowered water pH caused by potential CO2 leaks from a sub-seabed storage site in the Baltic Sea: An experimental study.

    Science.gov (United States)

    Sokołowski, Adam; Brulińska, Dominika; Mirny, Zuzanna; Burska, Dorota; Pryputniewicz-Flis, Dorota

    2018-02-01

    Sub-Seabed CCS is regarded as a key technology for the reduction of CO 2 emissions, but little is known about the mechanisms through which leakages from storage sites impact benthic species. In this study, the biological responses of the infaunal bivalve Limecola balthica to CO 2 -induced seawater acidification (pH7.7, 7.0, and 6.3) were quantified in 56-day mesocosm experiments. Increased water acidity caused changes in behavioral and physiological traits, but even the most acidic conditions did not prove to be fatal. In response to hypercapnia, the bivalves approached the sediment surface and increased respiration rates. Lower seawater pH reduced shell weight and growth, while it simultaneously increased soft tissue weight; this places L. balthica in a somewhat unique position among marine invertebrates. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2017-12-01

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

  11. Heliozoa from Nigeria | Wujek | Tropical Freshwater Biology

    African Journals Online (AJOL)

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

  12. Filling gaps in a large reserve network to address freshwater conservation needs.

    Science.gov (United States)

    Hermoso, Virgilio; Filipe, Ana Filipa; Segurado, Pedro; Beja, Pedro

    2015-09-15

    Freshwater ecosystems and biodiversity are among the most threatened at global scale, but efforts for their conservation have been mostly peripheral to terrestrial conservation. For example, Natura 2000, the world's largest network of protected areas, fails to cover adequately the distribution of rare and endangered aquatic species, and lacks of appropriate spatial design to make conservation for freshwater biodiversity effective. Here, we develop a framework to identify a complementary set of priority areas and enhance the conservation opportunities of Natura 2000 for freshwater biodiversity, using the Iberian Peninsula as a case study. We use a systematic planning approach to identify a minimum set of additional areas that would help i) adequately represent all freshwater fish, amphibians and aquatic reptiles at three different target levels, ii) account for key ecological processes derived from riverscape connectivity, and iii) minimize the impact of threats, both within protected areas and propagated from upstream unprotected areas. Addressing all these goals would need an increase in area between 7 and 46%, depending on the conservation target used and strength of connectivity required. These new priority areas correspond to subcatchments inhabited by endangered and range restricted species, as well as additional subcatchments required to improve connectivity among existing protected areas and to increase protection against upstream threats. Our study should help guide future revisions of the design of Natura 2000, while providing a framework to address deficiencies in reserve networks for adequately protecting freshwater biodiversity elsewhere. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    NARCIS (Netherlands)

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

    2009-01-01

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

  14. Marine nutrient contributions to tidal creeks in Virginia: spawning marine fish as nutrient vectors to freshwater ecosystems

    Science.gov (United States)

    Macavoy, S. E.; Garman, G. C.

    2006-12-01

    Coastal freshwater streams are typically viewed as conduits for the transport of sediment and nutrients to the coasts. Some coastal streams however experience seasonal migrations of anadromous fish returning to the freshwater to spawn. The fish may be vectors for the delivery of marine nutrients to nutrient poor freshwater in the form of excreted waste and post-spawning carcasses. Nutrients derived from marine sources are 13C, 15N and 34S enriched relative to nutrients in freshwater. Here we examine sediment, particulate organic matter (POM), invertebrates and fish in two tidal freshwater tributaries of the James River USA. The d15N of POM became elevated (from 3.8 to 6.5%), coincident with the arrival of anadromous river herring (Alosa sp), indicating a pulse of marine nitrogen. However, the elevated 15N was not observed in sediment samples or among invertebrates, which did not experience a seasonal isotopic shift (there were significant differences however among the guilds of invertebrate). Anadromous Alosa aestivalis captured within the tidal freshwater were 13C and 34S enriched (-19.3 and 17.2%, respectively) relative to resident freshwater fishes (-26.4 and 3.6% respectively) captured within 2 weeks of the Alosa. Although it is likely that marine derived nitrogen was detected in the tidal freshwater, it was not in sufficient abundance to change the isotope signature of most ecosystem components.

  15. Effects of anthropogenic sound on digging behavior, metabolism, Ca2+/Mg2+ ATPase activity, and metabolism-related gene expression of the bivalve Sinonovacula constricta

    Science.gov (United States)

    Peng, Chao; Zhao, Xinguo; Liu, Saixi; Shi, Wei; Han, Yu; Guo, Cheng; Jiang, Jingang; Wan, Haibo; Shen, Tiedong; Liu, Guangxu

    2016-01-01

    Anthropogenic sound has increased significantly in the past decade. However, only a few studies to date have investigated its effects on marine bivalves, with little known about the underlying physiological and molecular mechanisms. In the present study, the effects of different types, frequencies, and intensities of anthropogenic sounds on the digging behavior of razor clams (Sinonovacula constricta) were investigated. The results showed that variations in sound intensity induced deeper digging. Furthermore, anthropogenic sound exposure led to an alteration in the O:N ratios and the expression of ten metabolism-related genes from the glycolysis, fatty acid biosynthesis, tryptophan metabolism, and Tricarboxylic Acid Cycle (TCA cycle) pathways. Expression of all genes under investigation was induced upon exposure to anthropogenic sound at ~80 dB re 1 μPa and repressed at ~100 dB re 1 μPa sound. In addition, the activity of Ca2+/Mg2+-ATPase in the feet tissues, which is directly related to muscular contraction and subsequently to digging behavior, was also found to be affected by anthropogenic sound intensity. The findings suggest that sound may be perceived by bivalves as changes in the water particle motion and lead to the subsequent reactions detected in razor clams. PMID:27063002

  16. Effects of anthropogenic sound on digging behavior, metabolism, Ca(2+)/Mg(2+) ATPase activity, and metabolism-related gene expression of the bivalve Sinonovacula constricta.

    Science.gov (United States)

    Peng, Chao; Zhao, Xinguo; Liu, Saixi; Shi, Wei; Han, Yu; Guo, Cheng; Jiang, Jingang; Wan, Haibo; Shen, Tiedong; Liu, Guangxu

    2016-04-11

    Anthropogenic sound has increased significantly in the past decade. However, only a few studies to date have investigated its effects on marine bivalves, with little known about the underlying physiological and molecular mechanisms. In the present study, the effects of different types, frequencies, and intensities of anthropogenic sounds on the digging behavior of razor clams (Sinonovacula constricta) were investigated. The results showed that variations in sound intensity induced deeper digging. Furthermore, anthropogenic sound exposure led to an alteration in the O:N ratios and the expression of ten metabolism-related genes from the glycolysis, fatty acid biosynthesis, tryptophan metabolism, and Tricarboxylic Acid Cycle (TCA cycle) pathways. Expression of all genes under investigation was induced upon exposure to anthropogenic sound at ~80 dB re 1 μPa and repressed at ~100 dB re 1 μPa sound. In addition, the activity of Ca(2+)/Mg(2+)-ATPase in the feet tissues, which is directly related to muscular contraction and subsequently to digging behavior, was also found to be affected by anthropogenic sound intensity. The findings suggest that sound may be perceived by bivalves as changes in the water particle motion and lead to the subsequent reactions detected in razor clams.

  17. Effects of anthropogenic sound on digging behavior, metabolism, Ca2+/Mg2+ ATPase activity, and metabolism-related gene expression of the bivalve Sinonovacula constricta

    Science.gov (United States)

    Peng, Chao; Zhao, Xinguo; Liu, Saixi; Shi, Wei; Han, Yu; Guo, Cheng; Jiang, Jingang; Wan, Haibo; Shen, Tiedong; Liu, Guangxu

    2016-04-01

    Anthropogenic sound has increased significantly in the past decade. However, only a few studies to date have investigated its effects on marine bivalves, with little known about the underlying physiological and molecular mechanisms. In the present study, the effects of different types, frequencies, and intensities of anthropogenic sounds on the digging behavior of razor clams (Sinonovacula constricta) were investigated. The results showed that variations in sound intensity induced deeper digging. Furthermore, anthropogenic sound exposure led to an alteration in the O:N ratios and the expression of ten metabolism-related genes from the glycolysis, fatty acid biosynthesis, tryptophan metabolism, and Tricarboxylic Acid Cycle (TCA cycle) pathways. Expression of all genes under investigation was induced upon exposure to anthropogenic sound at ~80 dB re 1 μPa and repressed at ~100 dB re 1 μPa sound. In addition, the activity of Ca2+/Mg2+-ATPase in the feet tissues, which is directly related to muscular contraction and subsequently to digging behavior, was also found to be affected by anthropogenic sound intensity. The findings suggest that sound may be perceived by bivalves as changes in the water particle motion and lead to the subsequent reactions detected in razor clams.

  18. Hypoxia and acidification have additive and synergistic negative effects on the growth, survival, and metamorphosis of early life stage bivalves.

    Science.gov (United States)

    Gobler, Christopher J; DePasquale, Elizabeth L; Griffith, Andrew W; Baumann, Hannes

    2014-01-01

    Low oxygen zones in coastal and open ocean ecosystems have expanded in recent decades, a trend that will accelerate with climatic warming. There is growing recognition that low oxygen regions of the ocean are also acidified, a condition that will intensify with rising levels of atmospheric CO2. Presently, however, the concurrent effects of low oxygen and acidification on marine organisms are largely unknown, as most prior studies of marine hypoxia have not considered pH levels. We experimentally assessed the consequences of hypoxic and acidified water for early life stage bivalves (bay scallops, Argopecten irradians, and hard clams, Mercenaria mercenaria), marine organisms of significant economic and ecological value and sensitive to climate change. In larval scallops, experimental and naturally-occurring acidification (pH, total scale  = 7.4-7.6) reduced survivorship (by >50%), low oxygen (30-50 µM) inhibited growth and metamorphosis (by >50%), and the two stressors combined produced additively negative outcomes. In early life stage clams, however, hypoxic waters led to 30% higher mortality, while acidified waters significantly reduced growth (by 60%). Later stage clams were resistant to hypoxia or acidification separately but experienced significantly (40%) reduced growth rates when exposed to both conditions simultaneously. Collectively, these findings demonstrate that the consequences of low oxygen and acidification for early life stage bivalves, and likely other marine organisms, are more severe than would be predicted by either individual stressor and thus must be considered together when assessing how ocean animals respond to these conditions both today and under future climate change scenarios.

  19. The Implications of Ranaviruses to European farmed and wild freshwater fish

    DEFF Research Database (Denmark)

    Jensen, Ann Britt Bang

    The present thesis explores the implications of ranaviruses to European farmed and wild freshwater fish. The work presented was carried out as a part of the EU project “Risk assessment of new and emerging systemic iridoviral diseases for European fish and aquatic ecosystems” which was initiated...... in 2005 as a reaction to the speculation that ranaviruses might pose a serious threat to both farmed and wild-living freshwater fish and amphibians within the European community. In the present thesis, the purpose is to determine the implications of ranaviruses to European freshwater farmed and wild...... describing the risk of introduction and spread of exotic ranaviruses in European wild and farmed aquatic ecosystems Objectives 1 and 2 have been addressed by experimental trials involving bath challenges of both European farmed and wild fish species and ornamental fish species. The results showed that some...

  20. Cultured branchial epithelia from freshwater fish gills

    Science.gov (United States)

    Wood; PÄRt

    1997-01-01

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

  1. Study on Waste Heat Utilization Device of High-Temperature Freshwater in the Modern Marine Diesel Engine

    Science.gov (United States)

    Wang, Shuaijun; Liu, Chentao; Zhou, Yao

    2018-01-01

    Based on using the waste heat recycling from high temperature freshwater in marine diesel engine to heat fuel oil tank, lubrication oil tank and settling tank and so on to achieve energy saving, improve fuel efficiency as the goal, study on waste heat utilization device of high-temperature freshwater in the modern marine diesel engine to make the combustion chamber effectively cooled by high-temperature freshwater and the inner liner freshwater temperature heat is effectively utilized and so on to improve the overall efficiency of the power plant of the ship and the diesel optimum working condition.

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

    Science.gov (United States)

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

    2011-06-28

    Freshwater ecosystems are being heavily exploited and degraded by human activities all over the world, including in North America, where fishes and fisheries are strongly affected. Despite centuries of taxonomic inquiry, problems inherent to species identification continue to hamper the conservation of North American freshwater fishes. Indeed, nearly 10% of species diversity is thought to remain undescribed. To provide an independent calibration of taxonomic uncertainty and to establish a more accessible molecular identification key for its application, we generated a standard reference library of mtDNA sequences (DNA barcodes) derived from expert-identified museum specimens for 752 North American freshwater fish species. This study demonstrates that 90% of known species can be delineated using barcodes. Moreover, it reveals numerous genetic discontinuities indicative of independently evolving lineages within described species, which points to the presence of morphologically cryptic diversity. From the 752 species analyzed, our survey flagged 138 named species that represent as many as 347 candidate species, which suggests a 28% increase in species diversity. In contrast, several species of parasitic and nonparasitic lampreys lack such discontinuity and may represent alternative life history strategies within single species. Therefore, it appears that the current North American freshwater fish taxonomy at the species level significantly conceals diversity in some groups, although artificially creating diversity in others. In addition to providing an easily accessible digital identification system, this study identifies 151 fish species for which taxonomic revision is required.

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

    International Nuclear Information System (INIS)

    Yankovich, T.; Beresford, N.A.; Fesenko, S.; Fesenko, J.; Phaneuf, M.; Dagher, E.; Outola, I.; Andersson, P.; Thiessen, K.; Ryan, J.; Wood, M.D.; Bollhöfer, A.

    2013-01-01

    Environmental assessments to evaluate potentials risks to humans and wildlife often involve modelling to predict contaminant exposure through key pathways. Such models require input of parameter values, including concentration ratios, to estimate contaminant concentrations in biota based on measurements or estimates of concentrations in environmental media, such as water. Due to the diversity of species and the range in physicochemical conditions in natural ecosystems, concentration ratios can vary by orders of magnitude, even within similar species. Therefore, to improve model input parameter values for application in aquatic systems, freshwater concentration ratios were collated or calculated from national grey literature, Russian language publications, and refereed papers. Collated data were then input into an international database that is being established by the International Atomic Energy Agency. The freshwater database enables entry of information for all radionuclides listed in ICRP (1983), in addition to the corresponding stable elements, and comprises a total of more than 16,500 concentration ratio (CR wo-water ) values. Although data were available for all broad wildlife groups (with the exception of birds), data were sparse for many organism types. For example, zooplankton, crustaceans, insects and insect larvae, amphibians, and mammals, for which there were CR wo-water values for less than eight elements. Coverage was most comprehensive for fish, vascular plants, and molluscs. To our knowledge, the freshwater database that has now been established represents the most comprehensive set of CR wo-water values for freshwater species currently available for use in radiological environmental assessments

  4. The bivalve Anopaea (Inoceramidae) from the Upper Jurassic-lowermost Cretaceous of Mexico

    Science.gov (United States)

    Zell, Patrick; Crame, J. Alistair; Stinnesbeck, Wolfgang; Beckmann, Seija

    2015-07-01

    In Mexico, the Upper Jurassic to lowermost Cretaceous La Casita and coeval La Caja and La Pimienta formations are well-known for their abundant and well-preserved marine vertebrates and invertebrates. The latter include conspicuous inoceramid bivalves of the genus Anopaea not formally described previously from Mexico. Anopaea bassei (Lecolle de Cantú, 1967), Anopaea cf. stoliczkai (Holdhaus, 1913), Anopaea cf. callistoensis Crame and Kelly, 1995 and Anopaea sp. are rare constituents in distinctive Tithonian-lower Berriasian levels of the La Caja Formation and one Tithonian horizon of the La Pimienta Formation. Anopaea bassei was previously documented from the Tithonian of central Mexico and Cuba, while most other members of Anopaea described here are only known from southern high latitudes. The Mexican assemblage also includes taxa which closely resemble Anopaea stoliczkai from the Tithonian of India, Indonesia and the Antarctic Peninsula, and Anopaea callistoensis from the late Tithonian to ?early Berriasian of the Antarctic Peninsula. Our new data expand the palaeogeographical distribution of the high latitude Anopaea to the Gulf of Mexico region and substantiate faunal exchange, in the Late Jurassic-earliest Cretaceous, between Mexico and the Antarctic Realm.

  5. Monitoring endangered freshwater biodiversity using environmental DNA

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  6. Homogenization patterns of the world’s freshwater fish faunas

    Science.gov (United States)

    Villéger, Sébastien; Blanchet, Simon; Beauchard, Olivier; Oberdorff, Thierry; Brosse, Sébastien

    2011-01-01

    The world is currently undergoing an unprecedented decline in biodiversity, which is mainly attributable to human activities. For instance, nonnative species introduction, combined with the extirpation of native species, affects biodiversity patterns, notably by increasing the similarity among species assemblages. This biodiversity change, called taxonomic homogenization, has rarely been assessed at the world scale. Here, we fill this gap by assessing the current homogenization status of one of the most diverse vertebrate groups (i.e., freshwater fishes) at global and regional scales. We demonstrate that current homogenization of the freshwater fish faunas is still low at the world scale (0.5%) but reaches substantial levels (up to 10%) in some highly invaded river basins from the Nearctic and Palearctic realms. In these realms experiencing high changes, nonnative species introductions rather than native species extirpations drive taxonomic homogenization. Our results suggest that the “Homogocene era” is not yet the case for freshwater fish fauna at the worldwide scale. However, the distressingly high level of homogenization noted for some biogeographical realms stresses the need for further understanding of the ecological consequences of homogenization processes. PMID:22025692

  7. Explosive diversification following a benthic to pelagic shift in freshwater fishes

    OpenAIRE

    Hollingsworth, Phillip R; Simons, Andrew M; Fordyce, James A; Hulsey, C Darrin

    2013-01-01

    Background Interspecific divergence along a benthic to pelagic habitat axis is ubiquitous in freshwater fishes inhabiting lentic environments. In this study, we examined the influence of this habitat axis on the macroevolution of a diverse, lotic radiation using mtDNA and nDNA phylogenies for eastern North America’s most species-rich freshwater fish clade, the open posterior myodome (OPM) cyprinids. We used ancestral state reconstruction to identify the earliest benthic to pelagic transition ...

  8. Luminescence properties of a nanoporous freshwater diatom.

    Science.gov (United States)

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

    2012-01-01

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

  9. Coastal aquifers: Scientific advances in the face of global environmental challenges

    Science.gov (United States)

    Post, Vincent E. A.; Werner, Adrian D.

    2017-08-01

    Coastal aquifers embody the subsurface transition between terrestrial and marine systems, and form the almost invisible pathway for tremendous volumes of freshwater that flow to the ocean. Changing conditions of the earth's landscapes and oceans can disrupt the fragile natural equilibrium between fresh and saltwater that exists in coastal zones. Among these, over-abstraction of groundwater is considered the leading man-made cause of seawater intrusion. Moreover, many of the world's largest urban settings, where sources of contamination are profuse, have been built over the freshwater in coastal aquifers. Thus, coastal aquifers are important receptors of human impacts to water on Earth (Michael et al., 2017). This Special Issue on 'Investigation and Management of Coastal Aquifers' contains current scientific advances on the topic, dealing with the storage and quality of water, affected by stressors ranging in scale from point source contamination to global climate change.

  10. The role of local adaptation in shaping fish-mussel coevolution

    DEFF Research Database (Denmark)

    Douda, Karel; Liu, Huan-Zhang; Yu, Dan

    2017-01-01

    impact on the persistence of local populations. Bivalves of the order Unionida (freshwater mussels) are a functionally important but declining group of affiliate species, which are dependent on freshwater fish to host their parasitic larvae. The role of local adaptations and host fish resistance......1. The survival of affiliate (dependent) species in a changing environment is determined by the interactions between the affiliate species and their available hosts. However, the patterns of spatial and temporal changes in host compatibility are often unknown despite host shifts having direct...... associated bitterling fishes was low in its native range (with ancient sympatry). In areas of recent sympatry (non-native S.woodiana range in Europe), S.woodiana glochidia were demonstrated to readily parasitise local, evolutionarily naive bitterling species at high density.4. The results of a population...

  11. The freshwater balance of polar regions in transient simulations from 1500 to 2100 AD using a comprehensive coupled climate model

    Energy Technology Data Exchange (ETDEWEB)

    Lehner, Flavio; Raible, Christoph C.; Hofer, Dominik; Stocker, Thomas F. [University of Bern, Climate and Environmental Physics, Physics Institute, and Oeschger Centre for Climate Change Research, Bern (Switzerland)

    2012-07-15

    The ocean and sea ice in both polar regions are important reservoirs of freshwater within the climate system. While the response of these reservoirs to future climate change has been studied intensively, the sensitivity of the polar freshwater balance to natural forcing variations during preindustrial times has received less attention. Using an ensemble of transient simulations from 1500 to 2100 AD we put present-day and future states of the polar freshwater balance in the context of low frequency variability of the past five centuries. This is done by focusing on different multi-decadal periods of characteristic external forcing. In the Arctic, freshwater is shifted from the ocean to sea ice during the Maunder Minimum while the total amount of freshwater within the Arctic domain remains unchanged. In contrast, the subsequent Dalton Minimum does not leave an imprint on the slow-reacting reservoirs of the ocean and sea ice, but triggers a drop in the import of freshwater through the atmosphere. During the twentieth and twenty-first century the build-up of freshwater in the Arctic Ocean leads to a strengthening of the liquid export. The Arctic freshwater balance is shifted towards being a large source of freshwater to the North Atlantic ocean. The Antarctic freshwater cycle, on the other hand, appears to be insensitive to preindustrial variations in external forcing. In line with the rising temperature during the industrial era the freshwater budget becomes increasingly unbalanced and strengthens the high latitude's Southern Ocean as a source of liquid freshwater to lower latitude oceans. (orig.)

  12. Species persistence: a re-look at the freshwater fish fauna of Chennai, India

    Directory of Open Access Journals (Sweden)

    J.D.M. Knight

    2010-11-01

    Full Text Available Loss of habitat is one of the prime reasons for species extinction. It is generally established that certain classes of animals are more prone to extinction than others due to their restricted use of available habitats. Freshwater fish are among these sensitive animals. While local extinctions have rendered some species rare throughout their geographical range, many others have demonstrated higher levels of persistence. This paper focuses on a recent in-depth study of the primary freshwater fishes in and around Chennai. The study that spanned a period of two years recorded a total of 75 species of primary freshwater fish, of which 17 are new reports.

  13. Macrophytes: Freshwater Forests of Lakes and Rivers.

    Science.gov (United States)

    McDermid, Karla J.; Naiman, Robert J.

    1983-01-01

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

  14. 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, ...

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

    Science.gov (United States)

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

    2016-08-01

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

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

    OpenAIRE

    N. Kolesnyk

    2014-01-01

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

  17. Impacts of Freshwater Impoundment in the West Loch of Pearl Harbor

    Science.gov (United States)

    1993-05-01

    absence of applicable non-point standards, the "Yellow Book" criteria for freshwater aquatic life or domestic water supply could be applied to evaluate the...Waimalu, Waipahu, Wahiawa, and Ewa water use districts and contains the largest groundwater body on Oahu, supplying more than 50 percent of the island’s...irrigation; desalt existing brackish water supplies, and; 3 create a freshwater impoundment in West Loch. 6I I I The Board of Water Supply (BWS) and

  18. 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.

    2016-01-01

    Dissolved organic matter (DOM) composition in freshwater ecosystems is influenced by interactions between 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

  19. Prevalence of Clonorchis sinensis infection in freshwater fishes in northeastern China.

    Science.gov (United States)

    Zhang, Y; Chang, Q C; Zhang, Y; Na, L; Wang, W T; Xu, W W; Gao, D Z; Liu, Z X; Wang, C R; Zhu, X Q

    2014-08-29

    The prevalence of Clonorchis sinensis infection in freshwater fishes was surveyed in Heilongjiang Province, northeastern China, between August 2011 and September 2013. Thirteen species of freshwater fish (n=3221) and one species of shrimp (n=93) were collected from Songhua river, Nenjiang river and other lakes or ponds in 37 sites of 15 representative cities in Heilongjiang Province. They were individually examined by digestion technique, and the C. sinensis metacercariae were identified morphologically followed by confirmation using sequences of the second internal transcribed spacer of ribosomal DNA. Ten of the 13 examined species of freshwater fishes were infected with C. sinensis metacercariae, while all shrimps were negative. The overall prevalence of C. sinensis infection in 3221 examined freshwater fishes was 19.96%, with 42.57% (272/639) in Pseudorasbora parva, 22.55% (83/368) in Hemicculter leuciclus, 20.44% (121/592) in Carassius auratus, 17.71% (68/384) in Saurogobio dabryi, 10.85% (23/212) in Rhodeus ocellatus, 10.54% (48/455) in Phoxinus lagowskii, 8.20% (21/256) in Perccottus glehnii, 6.25% (5/80) in Misgurnus anguillicaudatus, 4.55% (1/22) in Xenocypris davidi, and 1.49% (1/67) in Cyprinus carpio. The average infection intensity in P. parva was 103.3 encysted metacercariae per gram of fish meat in Zhaoyuan city. The average prevalence of C. sinensis infection in Songhua river, Nenjiang river and lakes or ponds were 31.96% (503/1574), 11.30% (102/903) and 7.93% (59/744), respectively. The prevalence of C. sinensis infection in Zhaoyuan city (43.68%) was the highest among all sampling locations. These results revealed a high-prevalence of C. sinensis infection in freshwater fishes in Heilongjiang Province, northeastern China, posing significant public health concern. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Freshwater Choices in China: Options That Will Impact South and Southeast Asia

    Science.gov (United States)

    2014-12-04

    economies in the world. To sustain this economic growth and transform chronic hunger into food self-sufficiency, both China and India have embarked...FRESHWATER CHOICES IN CHINA: OPTIONS THAT WILL IMPACT SOUTH AND SOUTHEAST ASIA A Monograph by Mr. Steven M. Nystrom...TITLE AND SUBTITLE Freshwater Choices in China: Options that will Impact South and Southeast Asia 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c

  1. Global priorities for conservation of threatened species, carbon storage, and freshwater services

    DEFF Research Database (Denmark)

    Larsen, Frank Wugt; Londoño-Murcia, Maria C.; Turner, Will R.

    2011-01-01

    The potential of global biodiversity conservation efforts to also deliver critical benefits, such as carbon storage and freshwater services, is still unclear. Using spatially explicit data on 3,500 range-restricted threatened species, carbon storage, and freshwater provision to people, we conducted...... for which spatial planning and appropriate conservation mechanisms (e.g., payments for ecosystem services) can be used to realize synergies and mitigate tradeoffs....

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

    Science.gov (United States)

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

    2015-11-05

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

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

    African Journals Online (AJOL)

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

  4. Microplastic effect thresholds for freshwater benthic macroinvertebrates

    NARCIS (Netherlands)

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

    2018-01-01

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

  5. 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.

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

    Directory of Open Access Journals (Sweden)

    Leonardo Sáenz

    2016-07-01

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

  7. Byssus Structure and Protein Composition in the Highly Invasive Fouling Mussel Limnoperna fortunei

    Directory of Open Access Journals (Sweden)

    Shiguo Li

    2018-04-01

    Full Text Available Biofouling mediated by byssus adhesion in invasive bivalves has become a global environmental problem in aquatic ecosystems, resulting in negative ecological and economic consequences. Previous studies suggested that mechanisms responsible for byssus adhesion largely vary among bivalves, but it is poorly understood in freshwater species. Understanding of byssus structure and protein composition is the prerequisite for revealing these mechanisms. Here, we used multiple methods, including scanning electron microscope, liquid chromatography–tandem mass spectrometry, transcriptome sequencing, real-time quantitative PCR, inductively coupled plasma mass spectrometry, to investigate structure, and protein composition of byssus in the highly invasive freshwater mussel Limnoperna fortunei. The results indicated that the structure characteristics of adhesive plaque, proximal and distal threads were conducive to byssus adhesion, contributing to the high biofouling capacity of this species. The 3,4-dihydroxyphenyl-α-alanine (Dopa is a major post-transnationally modification in L. fortunei byssus. We identified 16 representative foot proteins with typical repetitive motifs and conserved domains by integrating transcriptomic and proteomic approaches. In these proteins, Lfbp-1, Lffp-2, and Lfbp-3 were specially located in foot tissue and highly expressed in the rapid byssus formation period, suggesting the involvement of these foot proteins in byssus production and adhesion. Multiple metal irons, including Ca2+, Mg2+, Zn2+, Al3+, and Fe3+, were abundant in both foot tissue and byssal thread. The heavy metals in these irons may be directly accumulated by L. fortunei from surrounding environments. Nevertheless, some metal ions (e.g., Ca2+ corresponded well with amino acid preferences of L. fortunei foot proteins, suggesting functional roles of these metal ions by interacting with foot proteins in byssus adhesion. Overall, this study provides structural and

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

    Science.gov (United States)

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

    2018-03-01

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

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

    African Journals Online (AJOL)

    2012-03-01

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

  10. Predicting the 137Cs Contamination of Freshwater Fish in Hong Kong

    International Nuclear Information System (INIS)

    Poon, C.B.; Au, S.M.

    1999-01-01

    A predictive method for estimating the 137 Cs contamination of freshwater fish in Hong Kong after an acute deposition is presented. This method applies a published aquatic model to the freshwater fish culture ponds in Hong Kong. The predicted transfer coefficient, in terms of peak concentration in fish (wet weight) per unit deposition, is found to be generally lower than those observed in some European and UK lakes after the Chernobyl accident. While the water-fish concentration factor is undoubtedly an important factor, some unique features of the local freshwater fish culture systems, such as the absence of further radioactivity input from catchment to the fish ponds after deposition, and high removal of radioactivity by sedimentation, also play significant roles. Sensitivity of model parameters and uncertainties of prediction are also studied. This predictive model can serve as a useful tool in emergency planning and in countermeasure implementation during a nuclear emergency in Hong Kong. (author)

  11. Incipient toxicity of lithium to freshwater organisms representing a salmonid habitat

    International Nuclear Information System (INIS)

    Emery, R.; Klopfer, D.C.; Skalski, J.R.

    1981-07-01

    Because the eventual development of fusion power reactors could increase the mining, use and disposal of lithium five-fold by the year 2000, potential effects from unusual amounts of lithium in aquatic environments were investigated. Freshwater oganisms representing a Pacific Northwest salmonid habitat were exposed to elevated conentrations of lithium. Nine parameters were used to determine the incipient toxicity of lithium to rainbow trout (Salmo gairdneri), insect larvae (Chironomus sp.), and Columbia River periphyton. All three groups of biota were incipiently sensitive to lithium at concentrations ranging between 0.1 and 1 mg/L. These results correspond with the incipient toxicity of beryllium, a chemically similar component of fusion reactor cores. A maximum lithium concentration of 0.01 mg/L occurs naturally in most freshwater environments (beryllium is rarer). Therefore, a concentration range of 0.01 to 0.1 mg/L may be regarded as approaching toxic concentrations when assessing the hazards of lithium in freshwaters

  12. Pharmaceuticals and personal care products (PPCPs in the freshwater aquatic environment

    Directory of Open Access Journals (Sweden)

    Anekwe Jennifer Ebele

    2017-03-01

    Full Text Available Pharmaceuticals and personal care products (PPCPs are a unique group of emerging environmental contaminants, due to their inherent ability to induce physiological effects in human at low doses. An increasing number of studies has confirmed the presence of various PPCPs in different environmental compartments, which raises concerns about the potential adverse effects to humans and wildlife. Therefore, this article reviews the current state-of-knowledge on PPCPs in the freshwater aquatic environment. The environmental risk posed by these contaminants is evaluated in light of the persistence, bioaccumulation and toxicity criteria. Available literature on the sources, transport and degradation of PPCPs in the aquatic environment are evaluated, followed by a comprehensive review of the reported concentrations of different PPCP groups in the freshwater aquatic environment (water, sediment and biota of the five continents. Finally, future perspectives for research on PPCPs in the freshwater aquatic environment are discussed in light of the identified research gaps in current knowledge.

  13. Toxicology of freshwater cyanobacteria.

    Science.gov (United States)

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

    2016-07-02

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

  14. Forest land cover continues to exacerbate freshwater acidification despite decline in sulphate emissions

    International Nuclear Information System (INIS)

    Dunford, Robert W.; Donoghue, Daniel N.M.; Burt, Tim P.

    2012-01-01

    Evidence from a multi-date regional-scale analysis of both high-flow and annual-average water quality data from Galloway, south-west Scotland, demonstrates that forest land cover continues to exacerbate freshwater acidification. This is in spite of significant reductions in airborne pollutants. The relationship between freshwater sulphate and forest cover has decreased from 1996 to 2006 indicating a decrease in pollutant scavenging. The relationship between forest cover and freshwater acidity (pH) is, however, still present over the same period, and does not show conclusive signs of having declined. Furthermore, evidence for forest cover contributing to a chlorine bias in marine ion capture suggests that forest scavenging of sea-salts may mean that the forest acidification effect may continue in the absence of anthropogenic pollutant inputs, particularly in coastal areas. - Highlights: ► Forest cover and water chemistry remain linked despite decreased sulphate emissions. ► Forest cover has significant relationships SO 4 2− , Cl − , Na + , pH, ANC and Na:Cl ratio. ► Forest cover: pH relationships shows some evidence of decline 1996–2006. ► Forest cover: freshwater sulphate relationships show evidence of decline 1996–2006. ► Natural forest-mechanisms may exacerbate acidification, particularly sea-salt scavenging. - Relationships between forest land cover and freshwater pH continue to be evident despite declines in anthropogenic pollutant sulphate deposition; sea-salt scavenging may play a role.

  15. Can environmental impact assessments alone conserve freshwater fish biota? Review of the Chilean experience

    International Nuclear Information System (INIS)

    Lacy, Shaw Nozaki; Meza, Francisco J.; Marquet, Pablo A.

    2017-01-01

    Chile was one of many countries that initiated environmental impact assessments in the 1990s, and has relied on their use for species conservation and territorial planning without the use of larger-scale environmental and ecological planning. The capacity of Chile's environmental impact assessment system (SEIA) to evaluate resident freshwater fishes and the potential impacts of water projects and aquaculture activities – two categories of projects that create direct threats to freshwater fishes – are assessed. Of the 3997 such submissions to the SEIA, only 0.6% conducted any freshwater fish assessment, and only 0.1% conducted any quantitative assessment of expected impacts from the associated project. The small number of assessments was characterized by poor study design, inconsistent sampling methodology, and species misidentification. Traditional assessments failed to include freshwater fish ecology in the general assessment framework. The new strategic environmental evaluation system only underscores the need for vastly improved field sampling protocols and assessment methodologies.

  16. Can environmental impact assessments alone conserve freshwater fish biota? Review of the Chilean experience

    Energy Technology Data Exchange (ETDEWEB)

    Lacy, Shaw Nozaki, E-mail: shaw.lacy@gmail.com [Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago (Chile); Departmento de Ecosistemas y Medio Ambiente, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, Macul (Chile); Centro Interdisciplinario de Cambio Global, Vicuña Mackenna 4860, Macul (Chile); Meza, Francisco J. [Departmento de Ecosistemas y Medio Ambiente, Pontificia Universidad Católica de Chile, Vicuña Mackenna 4860, Macul (Chile); Centro Interdisciplinario de Cambio Global, Vicuña Mackenna 4860, Macul (Chile); Marquet, Pablo A. [Departamento de Ecología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, Santiago (Chile); Instituto de Ecología y Biodiversidad, Las Palmeras 345, Santiago (Chile); Centro Interdisciplinario de Cambio Global, Vicuña Mackenna 4860, Macul (Chile)

    2017-03-15

    Chile was one of many countries that initiated environmental impact assessments in the 1990s, and has relied on their use for species conservation and territorial planning without the use of larger-scale environmental and ecological planning. The capacity of Chile's environmental impact assessment system (SEIA) to evaluate resident freshwater fishes and the potential impacts of water projects and aquaculture activities – two categories of projects that create direct threats to freshwater fishes – are assessed. Of the 3997 such submissions to the SEIA, only 0.6% conducted any freshwater fish assessment, and only 0.1% conducted any quantitative assessment of expected impacts from the associated project. The small number of assessments was characterized by poor study design, inconsistent sampling methodology, and species misidentification. Traditional assessments failed to include freshwater fish ecology in the general assessment framework. The new strategic environmental evaluation system only underscores the need for vastly improved field sampling protocols and assessment methodologies.

  17. Freshwater Availability and Constraints on Thermoelectric Power Generation in the Southeast U.S

    International Nuclear Information System (INIS)

    Feldman, David; Slough, Amanda; Garrett, Gary

    2008-01-01

    There is a myriad of uses to which our country's freshwater supply is currently committed. Together with increasing quantities of consumption, there are growing constraints on water availability. In our future there will be two elements of consumption at the forefront of concern: availability and efficiency. Availability of freshwater is the most important of these and is the subject of this report. To use water efficiently, we must first have it. Efficiency is key to ensuring availability for future needs. As population grows and economic and technology demands increase - especially for thermoelectric power - needs for freshwater will also increase. Thus, using our limited supplies of freshwater must be done as efficiently as possible. Thermoelectric generating industry is the largest user of our nation's water resources, including fresh, surface, ground, and saline water. Saline water use accounts for approximately 30% of thermoelectric use, while the remaining 70% is from freshwater sources. The U.S. Geological Survey (USGS) estimates that thermoelectric generation accounts for roughly 136,000 million gallons per day (MGD), or 39% of freshwater withdrawals. This ranks slightly behind agricultural irrigation as the top source of freshwater withdrawals in the U.S. in 2000. For Americans to preserve their standard of living and maintain a thriving economy it is essential that greater attention be paid to freshwater availability in efforts to meet energy demands - particularly for electric power. According to projections by the Energy Information Administration's (EIA) Annual Energy Outlook 2006 (AEO 2006) anticipated growth of thermoelectric generating capacity will be 22% between 2005 and 2030. In the 2007 Report, EIA estimates that capacity to grow from approximately 709 GW in 2005 to 862 GW in 20303. These large increases in generating capacity will result in increased water demands by thermoelectric power plants and greater competition over water between the

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

    Directory of Open Access Journals (Sweden)

    Shelley Burgin

    2017-02-01

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

  19. Mobile Element Evolution Playing Jigsaw—SINEs in Gastropod and Bivalve Mollusks

    Science.gov (United States)

    Matetovici, Irina; Sajgo, Szilard; Ianc, Bianca; Ochis, Cornelia; Bulzu, Paul; Popescu, Octavian; Damert, Annette

    2016-01-01

    SINEs (Short INterspersed Elements) are widely distributed among eukaryotes. Some SINE families are organized in superfamilies characterized by a shared central domain. These central domains are conserved across species, classes, and even phyla. Here we report the identification of two novel such superfamilies in the genomes of gastropod and bivalve mollusks. The central conserved domain of the first superfamily is present in SINEs in Caenogastropoda and Vetigastropoda as well as in all four subclasses of Bivalvia. We designated the domain MESC (Romanian for MElc—snail and SCoica—mussel) because it appears to be restricted to snails and mussels. The second superfamily is restricted to Caenogastropoda. Its central conserved domain—Snail—is related to the Nin-DC domain. Furthermore, we provide evidence that a 40-bp subdomain of the SINE V-domain is conserved in SINEs in mollusks and arthropods. It is predicted to form a stable stem-loop structure that is preserved in the context of the overall SINE RNA secondary structure in invertebrates. Our analysis also recovered short retrotransposons with a Long INterspersed Element (LINE)-derived 5′ end. These share the body and/or the tail with transfer RNA (tRNA)-derived SINEs within and across species. Finally, we identified CORE SINEs in gastropods and bivalves—extending the distribution range of this superfamily. PMID:26739168

  20. Trophic transfer of metal nanoparticles in freshwater ecosystems

    DEFF Research Database (Denmark)

    Tangaa, Stine Rosendal

    freshwater ecosystems range from a few ng/L in surface waters and up to mg/kg in sediments. Several studies have shown Ag ENPs to be toxic, bioaccumulative and harmful to aquatic biota within these concentration ranges. However, research on potential trophic transfer of Ag ENPs is limited. To investigate...... the aquatic ecosystems, Ag ENPs will undergo several transformation processes, ultimately leading to particles settling out of the water column. This will likely result in an increased concentration of ENPs in the sediment. In fact, predicted environmental concentrations of Ag ENPs in Danish and European...... freshwater food web. Future studies should concentrate on the internal distribution of Me-ENPs after uptake in both prey and predator, as this will increase the understanding of fate and effects of Me-ENPs on aquatic biota. Trophic transfer studies including more trophic levels, and higher pelagic organisms...

  1. How close do we live to water? A global analysis of population distance to freshwater bodies.

    Directory of Open Access Journals (Sweden)

    Matti Kummu

    Full Text Available Traditionally, people have inhabited places with ready access to fresh water. Today, over 50% of the global population lives in urban areas, and water can be directed via tens of kilometres of pipelines. Still, however, a large part of the world's population is directly dependent on access to natural freshwater sources. So how are inhabited places related to the location of freshwater bodies today? We present a high-resolution global analysis of how close present-day populations live to surface freshwater. We aim to increase the understanding of the relationship between inhabited places, distance to surface freshwater bodies, and climatic characteristics in different climate zones and administrative regions. Our results show that over 50% of the world's population lives closer than 3 km to a surface freshwater body, and only 10% of the population lives further than 10 km away. There are, however, remarkable differences between administrative regions and climatic zones. Populations in Australia, Asia, and Europe live closest to water. Although populations in arid zones live furthest away from freshwater bodies in absolute terms, relatively speaking they live closest to water considering the limited number of freshwater bodies in those areas. Population distributions in arid zones show statistically significant relationships with a combination of climatic factors and distance to water, whilst in other zones there is no statistically significant relationship with distance to water. Global studies on development and climate adaptation can benefit from an improved understanding of these relationships between human populations and the distance to fresh water.

  2. Novel Synechococcus genomes reconstructed from freshwater reservoirs

    Czech Academy of Sciences Publication Activity Database

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

    2017-01-01

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

  3. Intrinsic hierarchical structural imperfections in a natural ceramic of bivalve shell with distinctly graded properties.

    Science.gov (United States)

    Jiao, Da; Liu, Zengqian; Zhang, Zhenjun; Zhang, Zhefeng

    2015-07-22

    Despite the extensive investigation on the structure of natural biological materials, insufficient attention has been paid to the structural imperfections by which the mechanical properties of synthetic materials are dominated. In this study, the structure of bivalve Saxidomus purpuratus shell has been systematically characterized quantitatively on multiple length scales from millimeter to sub-nanometer. It is revealed that hierarchical imperfections are intrinsically involved in the crossed-lamellar structure of the shell despite its periodically packed platelets. In particular, various favorable characters which are always pursued in synthetic materials, e.g. nanotwins and low-angle misorientations, have been incorporated herein. The possible contributions of these imperfections to mechanical properties are further discussed. It is suggested that the imperfections may serve as structural adaptations, rather than detrimental defects in the real sense, to help improve the mechanical properties of natural biological materials. This study may aid in understanding the optimizing strategies of structure and properties designed by nature, and accordingly, provide inspiration for the design of synthetic materials.

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

    African Journals Online (AJOL)

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

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

    Science.gov (United States)

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

    2016-11-15

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

  6. Global diversity patterns of freshwater fishes - potential victims of their own success

    OpenAIRE

    Pelayo-Villamil, P.; Guisande, C.; Vari, R. P.; Manjarres-Hernandez, A.; Garcia-Rosello, E.; Gonzalez-Dacosta, J.; Heine, J.; Vilas, L. G.; Patti, B.; Quinci, E. M.; Jimenez, L. F.; Granado-Lorencio, C.; Tedesco, Pablo; Lobo, J. M.

    2015-01-01

    AimTo examine the pattern and cumulative curve of descriptions of freshwater fishes world-wide, the geographical biases in the available information on that fauna, the relationship between species richness and geographical rarity of such fishes, as well as to assess the relative contributions of different environmental factors on these variables. LocationGlobal. MethodsModestR was used to summarize the geographical distribution of freshwater fish species using information available from data-...

  7. FRESHWATER FISH FARMING CONDITIONS IN 1999 AND THE PRODUCTION PLAN FOR 2000

    Directory of Open Access Journals (Sweden)

    Zlatko Homen

    2000-09-01

    Full Text Available One of the activities of the Ministry of Agriculture and Forestry, Fishery and Mediterranean Agriculture Directorate, i. e. Fishery Directorate to be more specific, is the monitoring of conditions in freshwater fish farming. The objective of this work is to show conditions in freshwater fish farming during 1999. and to provide a production plan for 2000. It will also provide detailed insight into the present conditions in freshwater fish farming and into the production trends of this field. Regarding this issue, the »Questionnaire for the Monitoring of Conditions in Freshwater Fish Farming«, was sent to fish farmers aroud the country data was processed from 22 cap ponds and 13 trout ponds. Roughe estimates of conditions were conducted for 2 fish farms, since they haven’t yet returned the mandatoruy questionnaire, i. e. the necessary data. This work features data on the number of employees in fish farms, as well as their qualifications, on the actual production and distribution of farmed freshwater fish, on the areas where production was conducted and on the overall yield. Fish food, raw materials, used tools and incentive funds paid were also taken into consideration. The difficulties faced in this branch of the economy are also inicated. Compared to 1998, a slight decrease in the number of employees of freshwater fish farms has been recorded. The total number of employees in 1999 was 655, of which 555 were on carp ponds and 100 on trout ponds. Data on the qualifications of employees for 1999 show that most of them were unskilled workers, while highly skilled workers make up a minority in this work force. The total production of freshwater in 1999. amoounted to 6.185,51 tons. Of this amount 5.592,52 tons were warm-water fish specied and 592,99 tons were cold-water fish species. Compared to 1998, production decreased by 4,89 percent. Production for 2000 has been planned to increase by 22,15 percent, i. e. the production quantity is projected

  8. Anthropogenic pollutants affect ecosystem services of freshwater sediments. The need for a 'triad plus x' approach

    Energy Technology Data Exchange (ETDEWEB)

    Gerbersdorf, Sabine Ulrike; Wieprecht, Silke [Stuttgart Univ. (Germany). Dept. of Hydraulic Engineering and Water Resources Management; Hollert, Henner; Brinkmann, Markus [RWTH Aachen Univ. (Germany). Dept. of Ecosystem Analysis; Schuettrumpf, Holger [RWTH Aachen Univ. (Germany). Inst. of Hydraulic Engineering and Water Resources Management; Manz, Werner [Koblenz-Landau Univ., Koblenz (Germany). Inst. for Integrated Natural Sciences

    2011-09-15

    Purpose: Freshwater sediments and their attached microbial communities (biofilms) are essential features of rivers and lakes, providing valuable ecosystem services such as nutrient recycling or self-purification which extend beyond the aquatic environment. Anthropogenic pollutants, whether from the industrial era or as a result of our contemporary lifestyles, can negatively affect these functions with hitherto unknown consequences on ecology, the economy and human health. Thus far, the singular view of the involved disciplines such as ecotoxicology, environmental microbiology, hydrology and geomorphology has prevented a deeper understanding of this emerging issue. Main features: This paper discusses briefly the progressions and the state-of-the-art methods within the disciplines of concern related to contaminated sediments, ranging from ecotoxicological test systems, microbiological/molecular approaches to unravel changes of microbial ecosystems, up to the modelling of sediment transport and sorption/desorption of associated pollutants. The first bilateral research efforts on contaminated sediments include efforts to assess ecotoxicological sediment risk including sediment mobility (i.e. ecotoxicology and engineering), enhance bioremediation potential (i.e. microbiology and ecotoxicology) or to understand biostabilisation processes of sediments by microbial assemblages (i.e. microbiology and engineering). Conclusions and perspectives: In freshwater habitats, acute, chronic and mechanism-specific toxic effects on organisms, shifts in composition, structure and functionality of benthic microbial communities, as well as the obstruction of important ecosystem services by continuously discharged and long-deposited pollutants, should be related to the in situ sediment dynamics. To achieve an improved understanding of the ecology of freshwater sediments and the impairment of their important ecosystem functions by human-derived pollutants, we suggest a 'triad plus x

  9. Functional integrity of freshwater forested wetlands, hydrologic alteration, and climate change

    Science.gov (United States)

    Middleton, Beth A.; Souter, Nicholas J.;

    2016-01-01

    Climate change will challenge managers to balance the freshwater needs of humans and wetlands. The Intergovernmental Panel on Climate Change predicts that most regions of the world will be exposed to higher temperatures, CO2, and more erratic precipitation, with some regions likely to have alternating episodes of intense flooding and mega-drought. Coastal areas will be exposed to more frequent saltwater inundation as sea levels rise. Local land managers desperately need intra-regional climate information for site-specific planning, management, and restoration activities. Managers will be challenged to deliver freshwater to floodplains during climate change-induced drought, particularly within hydrologically altered and developed landscapes. Assessment of forest health, both by field and remote sensing techniques, will be essential to signal the need for hydrologic remediation. Studies of the utility of the release of freshwater to remediate stressed forested floodplains along the Murray and Mississippi Rivers suggest that brief episodes of freshwater remediation for trees can have positive health benefits for these forests. The challenges of climate change in forests of the developing world will be considered using the Tonle Sap of Cambodia as an example. With little ecological knowledge of the impacts, managing climate change will add to environmental problems already faced in the developing world with new river engineering projects. These emerging approaches to remediate stressed trees will be of utmost importance for managing worldwide floodplain forests with predicted climate changes.

  10. Calanoid Copepod Behavior in Thin Layer Shear Flows: Freshwater Versus Marine

    Science.gov (United States)

    Skipper, A. N.; Webster, D. R.; Yen, J.

    2015-11-01

    Marine copepods have been shown to behaviorally respond to vertical gradients of horizontal velocity and aggregate around thin layers. The current study addresses whether a freshwater copepod from an alpine lake demonstrates similar behavior response. Hesperodiaptomus shoshone is often the greatest biomass in alpine lakes and is the dominant zooplankton predator within its environment. The hypothesis is that H. shoshone responds to vertical gradients of horizontal velocity, which are associated with river outflows from alpine lakes, with fine-scale changes in swimming kinematics. The two calanoid copepods studied here, H. shoshone (freshwater) and Calanus finmarchicus(marine), are of similar size (2 - 4 mm), have similar morphologies, and utilize cruising as their primary swimming mode. The two animals differ not only in environment, but also in diet; H. shoshone is a carnivore, whereas C. finmarchicusis an herbivore. A laminar, planar jet (Bickley) was used in the laboratory to simulate a free shear flow. Particle image velocimetry (PIV) quantified the flow field. The marine species changed its swimming behavior significantly (increased swimming speed and turning frequency) and spent more time in the layer (40% vs. 70%) from control to treatment. In contrast, the freshwater species exhibited very few changes in either swimming behavior or residence time. Swimming kinematics and residence time results were also similar between males and females. Unlike the marine copepod, the results suggest the environmental flow structure is unimportant to the freshwater species.

  11. Impact of transient freshwater releases in the Southern Ocean on the AMOC and climate

    Energy Technology Data Exchange (ETDEWEB)

    Swingedouw, Didier [Universite Catholique de Louvain, Institut d' Astronomie et de Geophysique Georges Lemaitre, Louvain-la-Neuve (Belgium); CERFACS/GlobC, Toulouse (France); Fichefet, T.; Goosse, H.; Loutre, M.F. [Universite Catholique de Louvain, Institut d' Astronomie et de Geophysique Georges Lemaitre, Louvain-la-Neuve (Belgium)

    2009-08-15

    The bipolar ocean seesaw is a process that explains the competition between deep waters formed in the North Atlantic (NA) and in the Southern Ocean (SO). In this picture, an increase in the rate of formation of one of these water masses is made at the expense of the other. However, recent studies have questioned the effectiveness of this process. Namely, they show that adding freshwater in the SO can reduce deep water formation in the SO as well as in the NA. In this study, we explore the mechanisms and time scales excited by such a SO freshwater release by performing sensitivity experiments where a freshwater input is added abruptly in the ocean, south of 60 S, with different rates and durations. For this purpose, we evaluate the separate effects of wind, temperature and salinity changes, and we put the emphasis on the time evolution of the system. We find three main processes that respond to these freshwater inputs and affect the NA Deep Water (NADW) production: (i) the deep water adjustment, which enhances the NADW cell, (ii) the salinity anomaly spread from the SO, which weakens the NADW cell, and (iii) the increase in the Southern Hemisphere wind stress, which enhances the NADW cell. We show that process (i) affects the Atlantic in a few years, due to an adjustment of the pycnocline depth through oceanic waves in response to the buoyancy perturbation in the SO. The salinity anomalies responsible for the NADW production decrease [process (ii)] invades the NA in around 30 years, while the wind stress from process (iii) increases in around 20 years after the beginning of the freshwater perturbation. Finally, by testing the response of the ocean to a large range of freshwater release fluxes, we show that for fluxes larger than 0.2 Sv, process (ii) dominates over the others and limits NADW production after a few centuries, while for fluxes lower than 0.2 Sv, process (ii) hardly affects the NADW production. On the opposite, the NADW export is increased by processes

  12. Effects of pollution on freshwater fish and amphibians

    International Nuclear Information System (INIS)

    Pickering, Q.H.; Hunt, E.P.; Phipps, G.L.; Roush, T.H.; Smith, W.E.; Spehar, D.L.; Stephan, C.E.; Tanner, D.K.

    1983-01-01

    A literature review is presented dealing with studies on the effects of pollution on freshwater fish and amphibians. The pollutants studied included acid mine drainage, PCBs, cadmium, lead, naphthalene, plutonium, in addition to several studies dealing with pH effects

  13. Reducing the impact of irrigated crops on freshwater availability: the case of Brazilian yellow melons

    NARCIS (Netherlands)

    Brito de Figueirêdo, M.C.; Boer, de I.J.M.; Kroeze, C.; Silva Barros, da V.; Sousa, de J.A.; Souza de Aragão, F.A.; Sonsol Gondim, R.; Potting, J.

    2014-01-01

    Purpose This study quantifies freshwater consumption throughout the life cycle of Brazilian exported yellow melons and assesses the resulting impact on freshwater availability. Results are used to identify improvement options. Moreover, the study explores the further impact of variations in

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

    African Journals Online (AJOL)

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

  15. Effects of arctic temperatures on distribution and retention of the nuclear waste radionuclides 241Am, 57Co, and 137Cs in the bioindicator bivalve Macoma balthica

    Science.gov (United States)

    Hutchins, D.A.; Stupakoff, I.; Hook, S.; Luoma, S.N.; Fisher, N.S.

    1998-01-01

    The disposal of radioactive wastes in Arctic seas has made it important to understand the processes affecting the accumulation of radionuclides in food webs in coldwater ecosystems. We examined the effects of temperature on radionuclide assimilation and retention by the bioindicator bivalve Macoma balthica using three representative nuclear waste components, 241Am, 57Co, and 137Cs. Experiments were designed to determine the kinetics of processes that control uptake from food and water, as well as kinetic constants of loss. 137Cs was not accumulated in soft tissue from water during short exposures, and was rapidly lost from shell with no thermal dependence. No effects of temperature on 57Co assimilation or retention from food were observed. The only substantial effect of polar temperatures was that on the assimilation efficiency of 241Am from food, where 10% was assimilated at 2??C and 26% at 12??C. For all three radionuclides, body distributions were correlated with source, with most radioactivity obtained from water found in the shell and food in the soft tissues. These results suggest that in general Arctic conditions had relatively small effects on the biological processes which influence the bioaccumulation of radioactive wastes, and bivalve concentration factors may not be appreciably different between polar and temperate waters.

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

    Science.gov (United States)

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

    2013-01-01

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

  17. Bibliography on cycling of trace metals in freshwater ecosystems

    International Nuclear Information System (INIS)

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

    1978-07-01

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

  18. North Atlantic Oscillation dynamics recorded in shells of a long-lived bivalve mollusk

    Science.gov (United States)

    Schöne, Bernd R.; Oschmann, Wolfgang; Rössler, Jochen; Freyre Castro, Antuané D.; Houk, Stephen D.; Kröncke, Ingrid; Dreyer, Wolfgang; Janssen, Ronald; Rumohr, Heye; Dunca, Elena

    2003-12-01

    Existing reconstructions of the winter North Atlantic Oscillation (WNAO) are based on terrestrial proxies and historical documents. No direct high-resolution, long-term rec ords from marine settings are available for this major climate-dictating phenomenon, which severely affects a variety of economic aspects of our society. Here we present a 245 yr proxy WNAO index based on shells of the long-lived marine bivalve mollusk Arctica islandica. Variations in annual rates of shell growth are positively correlated with WNAO-related changes in the food supply. Maximum amplitudes in frequency bands of 7 9 and 5 7 yr fall exactly within the range of instrumental and other proxy WNAO indices. These estimates were obtained for specimens collected live, 2000 km apart, in the central North Sea and on the Norwegian Shelf. Hence, the WNAO influences hydrographic regimes of large regions of the ocean. Our study demonstrates that A. islandica can reliably reconstruct WNAO dynamics for time intervals and regions without instrumental records. Our new tool functions as a proxy for the WNAO index prior to the twentieth-century greenhouse forcing and has the potential to further validate other proxy-based WNAO records.

  19. Multibiomarker assessment of cerium dioxide nanoparticle (nCeO{sub 2}) sublethal effects on two freshwater invertebrates, Dreissena polymorpha and Gammarus roeseli

    Energy Technology Data Exchange (ETDEWEB)

    Garaud, M. [Université de Lorraine, CNRS UMR 7360, Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC), Campus Bridoux, Rue du Général Delestraint, 57070 Metz (France); International Consortium for the Environmental Implications of Nanotechnology (iCEINT), Aix en Provence (France); Trapp, J.; Devin, S.; Cossu-Leguille, C.; Pain-Devin, S.; Felten, V. [Université de Lorraine, CNRS UMR 7360, Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC), Campus Bridoux, Rue du Général Delestraint, 57070 Metz (France); Giamberini, L., E-mail: laure.giamberini@univ-lorraine.fr [Université de Lorraine, CNRS UMR 7360, Laboratoire Interdisciplinaire des Environnements Continentaux (LIEC), Campus Bridoux, Rue du Général Delestraint, 57070 Metz (France); International Consortium for the Environmental Implications of Nanotechnology (iCEINT), Aix en Provence (France)

    2015-01-15

    Highlights: • Gammarids and mussels both accumulated significant amount of waterborne nCeO{sub 2}. • nCeO{sub 2} decreased catalase, lysosomal system size and lipoperoxidation in mussels. • nCeO{sub 2} could exert antioxidant protecting activity in mussels. • In contrast with mussels, no effects of nCeO{sub 2} were observed on Gammarids. - Abstract: Cerium nanoparticles (nCeO{sub 2}) are widely used in everyday products, as fuel and paint additives. Meanwhile, very few studies on nCeO{sub 2} sublethal effects on aquatic organisms are available. We tried to fill this knowledge gap by investigating short-term effects of nCeO{sub 2} at environmentally realistic concentrations on two freshwater invertebrates; the amphipod Gammarus roeseli and the bivalve Dreissena polymorpha, using an integrated multibiomarker approach to detect early adverse effects of nCeO{sub 2} on organism biology. Differences in the behaviour of the organisms and of nanoparticles in the water column led to differential nCeO{sub 2} bioaccumulations, G. roeseli accumulating more cerium than D. polymorpha. Exposure to nCeO{sub 2} led to decreases in the size of the lysosomal system, catalase activity and lipoperoxidation in mussel digestive glands that could result from nCeO{sub 2} antioxidant properties, but also negatively impacted haemolymph ion concentrations. At the same time, no strong adverse effects of nCeO{sub 2} could be observed on G. roeseli. Further experiments will be necessary to confirm the absence of severe nCeO{sub 2} adverse effects in long-term environmentally realistic conditions.

  20. An overview of freshwater prawn fishery in Bangladesh: present status and future prospect

    Directory of Open Access Journals (Sweden)

    Ferdous Ahamed

    2014-07-01

    Full Text Available The freshwater prawn fishery plays an important role in the economy of Bangladesh. The fishery is mainly based on the culture of Macrobrachium rosenbergii. The culture fishery has been growing rapidly, thus, masking the dwindling capture fishery which is faced with serious environmental issues augmented by deleterious fishing methods. Despite the high prospects of the freshwater prawn aquaculture in Bangladesh, a lot of research is needed to ensure the sustainable development of the capture fishery which forms a key source of prawn aquaculture seed as well as provide a baseline for future appraisals. Freshwater prawn aquaculture in Bangladesh is based on traditional methods with continuous adaptations by the rural fishers. However, numerous constraints to its full development are evident at all stages of its production. Lack of quality brood stock, seed, feeds and poor technical knowledge at farmers level are but some of the impediments challenging the sustainability of this industry. This paper reviews the freshwater prawn fishery of Bangladesh over the last few decades and outlines approaches for the development of an ecosystem-based management of both the culture and capture sectors of this important fishery.