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Sample records for clam mercenaria mercenaria

  1. Biodeposition, respiration, and excretion rates of an introduced clam Mercenaria mercenaria in ponds with implications for potential competition with the native clam Meretrix meretrix in Shuangtaizi estuary, China

    Science.gov (United States)

    Zhang, Anguo; Yuan, Xiutang; Hou, Wenjiu; Li, Xiaodong; Zhao, Kai; Chen, Weixin; Su, Xiurong

    2016-05-01

    This study aimed to evaluate the potential impacts of an introduced clam Mercenaria mercenaria on estuarine ecosystem, and implications for the niche competition with a native clam Meretrix meretrix. The biodeposition, respiration, and excretion rates of M. mercenaria were determined seasonally using a sediment trap and a closed respirator in field. The biodeposition rates of M. mercenaria were 0.06-0.37 g/ (ind.·d), and the respiration rates were 0.31-14.66 mg/(ind.·d). The ammonia and phosphate excretion rates were 0.18-36.70 and 1.44-14.87 μg/(ind.·d), respectively. The hard clam M. mercenaria may discharge dry deposits up to 2.1×105 t, contribute 18.3 t ammonia and 9.0 t phosphate to culture ponds, and consume 7.9×103 t O2 from ponds annually. It suggested that the hard clam M. mercenaria might play an important role in pelagic-benthic coupling in pond ecosystem through biodeposition and excretion. A comparison of the key physiological parameters of the introduced clam M. mercenaria and the native clam Meretrix meretrix suggested that M. mercenaria had a niche similar to that of Meretrix meretrix in Shuangtaizi estuary and might have a potential competition with Meretrix meretrix for habitat and food if M. mercenaria species escaped from the culture pond or artificially released in estuarine ecosystem.

  2. Effects of chronic gamma radiation on the growth and survival of juvenile clams (Mercenaria mercenaria) and scallops (Argopecten irradians)

    International Nuclear Information System (INIS)

    Juvenile clams (Mercenaria mercenaria) and scallops (Argopecten irradians) from North Carolina were exposed to five intensities of chronic γ radiation for 3 to 14 months during 1973/1974. Exposure rates ranged downward from 37 rads/hr to levels slightly higher than background radiation. Deleterious effects on growth and survival of clams occurred only at the highest exposure rate (37 to 16 rads/hr). Clams exposed to low radiation levels (0.007 to 0.008 rads/hr) increased in weight, but not in length, faster than the controls. One-half of the clams exposed to the highest radiation level survived to 159 days, after a cumulative dose of 132 krads, and only 10 % survived to 14 months after a cumulative dose of 150 to 346 krads. No deleterious effects on growth and survival of scallops were apparent during 84 days of exposure to a cumulative radiation dose of 71.7 krads. (author)

  3. Alterations of the immune transcriptome in resistant and susceptible hard clams (Mercenaria mercenaria) in response to Quahog Parasite Unknown (QPX) and temperature.

    Science.gov (United States)

    Wang, Kailai; Pales Espinosa, Emmanuelle; Tanguy, Arnaud; Allam, Bassem

    2016-02-01

    Quahog Parasite Unknown (QPX) is a fatal protistan parasite that causes severe losses in the hard clam (Mercenaria mercenaria) fisheries along the northeastern coast of the US. Field and laboratory studies of QPX disease have demonstrated a major role for water temperature and M. mercenaria genetic origin in disease development. Infections are more likely to occur at cold temperatures, with clam stocks originating from southern states being more susceptible than clams from northern origin where disease is enzootic. Even though the influence of temperature on QPX infection have been examined in susceptible and resistant M. mercenaria at physiological and cellular scales, the underlying molecular mechanisms associated with host-pathogen interactions remain largely unknown. This study was carried out to explore the molecular changes in M. mercenaria in response to temperature and QPX infection on the transcriptomic level, and also to compare molecular responses between susceptible and resistant clam stocks. A M. mercenaria oligoarray (15 K Agilent) platform was produced based on our previously generated transcriptomic data and was used to compare gene expression profiles in naive and QPX-infected susceptible (Florida stock) and resistant (Massachusetts) clams maintained at temperatures favoring disease development (13 °C) or clam healing (21 °C). In addition, transcriptomic changes reflecting focal (the site of infection, mantle) and systemic (circulating hemocytes) responses were also assessed using the oligoarray platform. Results revealed significant regulation of multiple biological pathways by temperature and QPX infection, mainly associated with immune recognition, microbial killing, protein synthesis, oxidative protection and metabolism. Alterations were widely systemic with most changes in gene expression revealed in hemocytes, highlighting the role of circulating hemocytes as the first line of defense against pathogenic stress. A large number of

  4. Short-term acute hypercapnia affects cellular responses to trace metals in the hard clams Mercenaria mercenaria

    International Nuclear Information System (INIS)

    Highlights: •PCO2 alters accumulation of Cd and Cu in clam cells. •Accumulation of Cd induces release of free Zn2+. •Accumulation of Cu induces an increase in free Cu2+ and Fe2+. •Metal-induced oxidative stress is alleviated at high PCO2. •Toxicity of Cu in likely enhanced while that of Cd alleviated by high PCO2. -- Abstract: Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO2 (PCO2) and pH; they also serve as the natural sinks for trace metals. Benthic filter-feeding organisms such as bivalves are exposed to the elevated concentrations of metals in estuarine water and sediments that can strongly affect their physiology. The effects of metals on estuarine organisms may be exacerbated by other environmental factors. Thus, a decrease in pH caused by high PCO2 (hypercapnia) can modulate the effects of trace metals by affecting metal bioavailability, accumulation or binding. To better understand the cellular mechanisms of interactions between PCO2 and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (Mercenaria mercenaria) to different levels of PCO2 (0.05, 1.52 and 3.01 kPa) and two major trace metal pollutants – cadmium (Cd) and copper (Cu). Elevated PCO2 resulted in a decrease in intracellular pH (pHi) of the isolated mantle cells from 7.8 to 7.4. Elevated PCO2 significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated PCO2 levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd2+ concentration remained the same, while intracellular levels of free Zn2+ increased suggesting that Cd2+ substitutes bound Zn2+ in these cells. In contrast, Cu exposure did not affect intracellular Zn2+ but led to a profound increase in the intracellular levels of labile Cu2+ and Fe2+. An increase

  5. Short-term acute hypercapnia affects cellular responses to trace metals in the hard clams Mercenaria mercenaria

    Energy Technology Data Exchange (ETDEWEB)

    Ivanina, Anna V. [Department of Biology, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223 (United States); Beniash, Elia [Department of Oral Biology, University of Pittsburgh, 589 Salk Hall, 3501 Terrace Street, Pittsburgh, PA 15261 (United States); Etzkorn, Markus; Meyers, Tiffany B. [Department of Chemistry, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223 (United States); Ringwood, Amy H. [Department of Biology, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223 (United States); Sokolova, Inna M., E-mail: isokolov@uncc.edu [Department of Biology, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC 28223 (United States)

    2013-09-15

    Highlights: •P{sub CO{sub 2}} alters accumulation of Cd and Cu in clam cells. •Accumulation of Cd induces release of free Zn{sup 2+}. •Accumulation of Cu induces an increase in free Cu{sup 2+} and Fe{sup 2+}. •Metal-induced oxidative stress is alleviated at high P{sub CO{sub 2}}. •Toxicity of Cu in likely enhanced while that of Cd alleviated by high P{sub CO{sub 2}}. -- Abstract: Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO{sub 2} (P{sub CO{sub 2}}) and pH; they also serve as the natural sinks for trace metals. Benthic filter-feeding organisms such as bivalves are exposed to the elevated concentrations of metals in estuarine water and sediments that can strongly affect their physiology. The effects of metals on estuarine organisms may be exacerbated by other environmental factors. Thus, a decrease in pH caused by high P{sub CO{sub 2}} (hypercapnia) can modulate the effects of trace metals by affecting metal bioavailability, accumulation or binding. To better understand the cellular mechanisms of interactions between P{sub CO{sub 2}} and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (Mercenaria mercenaria) to different levels of P{sub CO{sub 2}} (0.05, 1.52 and 3.01 kPa) and two major trace metal pollutants – cadmium (Cd) and copper (Cu). Elevated P{sub CO{sub 2}} resulted in a decrease in intracellular pH (pH{sub i}) of the isolated mantle cells from 7.8 to 7.4. Elevated P{sub CO{sub 2}} significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated P{sub CO{sub 2}} levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd{sup 2+} concentration remained the same, while intracellular levels of free Zn{sup 2+} increased suggesting that Cd{sup 2+} substitutes bound Zn{sup 2

  6. Isolation and characterization of novel microsatellite markers in Mercenaria mercenaria.

    Science.gov (United States)

    Ning, Y F; Li, Z B; Mao, X Q; Li, B B; Huang, Y S; Yuan, Y; Shangguan, J B

    2016-01-01

    Mercenaria mercenaria, also known as the hard clam, is widely distributed in the coastal waters of temperate and tropical areas in the Asian Pacific region. This species is widely popular in the international market, especially in the United States, Europe, and other Western countries, because of its high protein value, taste, and simple farming requirements. In this study, 17 novel microsatellite loci from the M. mercenaria genome were developed using the fast isolation by amplified fragment length polymorphism of sequences containing repeats protocol. Thirty-two wild individuals were used to evaluate the degree of polymorphism of these markers. Results indicated that there were 11 polymorphic loci and six monomorphic loci, and the number of alleles per locus and the polymorphism information content ranged from two to six and from 0.059 to 0.498, respectively. The observed and expected heterozygosity varied from 0.0625 to 0.5333 and 0.0615 to 0.4977, respectively. The Y1-4 locus deviated significantly from Hardy-Weinberg equilibrium (HWE) after Bonferroni correction was applied, while the other loci were in HWE. These loci will provide useful information for M. mercenaria population genetic studies. PMID:27050966

  7. Spermatozoa and spermatogenesis in the northern quahaug Mercenaria mercenaria (Mollusca, Bivalvia)

    Science.gov (United States)

    Ying, Xue-Ping; Yang, Wan-Xi; Dahms, Hans-U.; Lin, Zhihua; Chai, Xueliang

    2008-12-01

    We studied the ultrastructure of spermatogenesis and spermatozoa in the northern quahaug, the clam Mercenaria mercenaria. Spermatogenetic cells gradually elongate. Mitochondria gradually fuse and increase in size and electron density. During spermatid differentiation, proacrosomal vesicles migrate towards the presumptive anterior pole of the nucleus and eventually form the acrosome. The spermatozoon of M. mercenaria is of a primitive type. It is composed of head, mid-piece, and tail. The acrosome shows a subacrosomal space with a short conical contour. The slightly curved nucleus of the spermatozoon contains fine-grained dense chromatin. The middle piece consists of a centriolar complex which is surrounded by four mitochondria. The flagellum has a standard “9 + 2” microtubular structure. The ultrastructure of spermatozoa and spermatogenesis of M. mercenaria shares a number of features with other species of the family Veneridae. M. mercenaria may be a suitable model species for further investigations into the mechanisms of spermatogenesis in the Bivalvia.

  8. Characterization of brevetoxin metabolism in Karenia brevis bloom-exposed clams (Mercenaria sp.) by LC-MS/MS.

    Science.gov (United States)

    Abraham, Ann; Wang, Yuesong; El Said, Kathleen R; Plakas, Steven M

    2012-11-01

    Brevetoxin metabolites were identified and characterized in the hard clam (Mercenaria sp.) after natural exposure to Karenia brevis blooms by using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Principal brevetoxins BTX-1 and BTX-2 produced by K. brevis were not detectable in clams. Metabolites of these brevetoxins found in clams included products of oxidation, reduction, hydrolysis and amino acid/fatty acid conjugation. Of highest abundance were cysteine and taurine conjugates. We also found glutathione, glycine-cysteine, and γ-glutamyl-cysteine conjugates. A series of fatty acid derivatives of cysteine-brevetoxin conjugates were also identified. PMID:22884629

  9. Quantitative Real-Time PCR Assay for QPX (Thraustochytriidae), a Parasite of the Hard Clam (Mercenaria mercenaria)▿

    OpenAIRE

    Liu, Qianqian; Allam, Bassem; Collier, Jackie L.

    2009-01-01

    We developed a real-time quantitative PCR (qPCR) assay targeting the rRNA internal transcribed spacer region of the hard clam pathogen QPX. The qPCR assay was more sensitive than was histology in detecting clams with light QPX infections. QPX was detected in 4 of 43 sediment samples but in none of 40 seawater samples.

  10. Heavy metals in Mercenaria mercenaria and sediments from the New Bedford Harbor region of Buzzard's Bay, Massachusetts

    Energy Technology Data Exchange (ETDEWEB)

    Genest, P.E. (Southeastern Massachusetts Univ., North Dartmouth); Hatch, W.I.

    1981-01-01

    M. mercenaria and sediments from the New Bedford region were analyzed for cadmium, copper, iron, lead, and zinc to investigate some of the relationships between environmental and organismal levels. It appears that at present there is no major contamination of clams or sediments in the areas studied. However, since levels of some metals approached the permissible limits at times, it would obviously be beneficial if all sources of pollution to the area could be identified and regulated. It is suggested that harvesting of clams could be managed seasonally so that tissue contaminants are at their periodic minima. For these metals late summer, fall, and winter appear to be favorable times. It is also suggested that clams harvested in the vicinity of recently dredged areas be monitored for heavy metal levels. The need for a continuous monitoring program for heavy metals and other toxic substances for New Bedford and surrounding areas to insure public safety is recommended.

  11. Interactive effects of copper exposure and environmental hypercapnia on immune functions of marine bivalves Crassostrea virginica and Mercenaria mercenaria.

    Science.gov (United States)

    Ivanina, Anna V; Hawkins, Chelsea; Sokolova, Inna M

    2016-02-01

    Estuarine organisms such as bivalves are commonly exposed to trace metals such as copper (Cu) and hypercapnia (elevated CO2 levels) in their habitats, which may affect their physiology and immune function. This study investigated the combined effects of elevated CO2 levels (∼800-2000 μatm PCO2, such as predicted by the near-future scenarios of global climate change) and Cu (50 μg l(-1)) on immune functions of the sediment dwelling hard clams Mercenaria mercenaria and an epifaunal bivalve, the eastern oyster Crassostrea virginica. Clams and oysters were exposed for 4 weeks to different CO2 and Cu levels, and tissue Cu burdens and immune parameters were assessed to test the hypothesis that hypercapnia will enhance Cu uptake due to the higher bioavailability of free Cu(2+) and increase the immunomodulatory effects of Cu. Exposure to Cu stimulated key immune parameters of clams and oysters leading to increased number of circulating hemocytes, higher phagocytosis and adhesion ability of hemocytes, as well as enhanced antiparasitic and antibacterial properties of the hemolymph reflected in higher activities of lysozyme and inhibitors of cysteine proteases. Lysozyme activation by Cu exposure was most prominent in normocapnia (∼400 μatm PCO2) and an increase in the levels of the protease inhibitors was strongest in hypercapnia (∼800-2000 μatm PCO2), but other immunostimulatory effects of Cu were evident in all PCO2 exposures. Metabolic activity of hemocytes of clams and oysters (measured as routine and mitochondrial oxygen consumption rates) was suppressed by Cu exposure likely reflecting lower rates of ATP synthesis and/or turnover. However, this metabolic suppression had no negative effects of the studied immune functions of hemocytes such as phagocytosis or adhesion capacity. Hypercapnia (∼800-2000 μatm PCO2) slightly but significantly enhanced accumulation of Cu in hemocytes, consistent with higher Cu(2+) bioavailability in CO2-acidified water, but

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

    International Nuclear Information System (INIS)

    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

  13. 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

  14. Interactive effects of CO2 and trace metals on the proteasome activity and cellular stress response of marine bivalves Crassostrea virginica and Mercenaria mercenaria

    International Nuclear Information System (INIS)

    Highlights: • Elevated PCO2 enhanced accumulation of Cu and Cd in the gills of mollusks. • The proteasome activities were affected by metals but robust to elevated PCO2. • Exposure to Cd and Cu had opposite effects on the proteasome activity. • Combined exposure to Cu and elevated PCO2 negatively affected energy status. - Abstract: Increased anthropogenic emission of CO2 changes the carbonate chemistry and decreases the pH of the ocean. This can affect the speciation and the bioavailability of metals in polluted habitats such as estuaries. However, the effects of acidification on metal accumulation and stress response in estuarine organisms including bivalves are poorly understood. We studied the interactive effects of CO2 and two common metal pollutants, copper (Cu) and cadmium (Cd), on metal accumulation, intracellular ATP/ubiquitin-dependent protein degradation, stress response and energy metabolism in two common estuarine bivalves—Crassostrea virginica (eastern oyster) and Mercenaria mercenaria (hard shell clam). Bivalves were exposed for 4–5 weeks to clean seawater (control) and to either 50 μg L−1 Cu or 50 μg L−1 Cd at one of three partial pressures of CO2 (PCO2 ∼395, ∼800 and ∼1500 μatm) representative of the present-day conditions and projections of the Intergovernmental Panel for Climate Change (IPCC) for the years 2100 and 2250, respectively. Clams accumulated lower metal burdens than oysters, and elevated PCO2 enhanced the Cd and Cu accumulation in mantle tissues in both species. Higher Cd and Cu burdens were associated with elevated mRNA expression of metal binding proteins metallothionein and ferritin. In the absence of added metals, proteasome activities of clams and oysters were robust to elevated PCO2, but PCO2 modulated the proteasome response to metals. Cd exposure stimulated the chymotrypsin-like activity of the oyster proteasome at all CO2 levels. In contrast, trypsin- and caspase-like activities of the oyster proteasome

  15. Interactive effects of CO₂ and trace metals on the proteasome activity and cellular stress response of marine bivalves Crassostrea virginica and Mercenaria mercenaria

    Energy Technology Data Exchange (ETDEWEB)

    Götze, Sandra [Alfred Wegener Institute, Helmholtz Centre for Polar, Marine Research, Functional Ecology, 27570 Bremerhaven (Germany); Department of Biology, University of North Carolina at Charlotte, Charlotte, NC 28223 (United States); Matoo, Omera B. [Department of Biology, University of North Carolina at Charlotte, Charlotte, NC 28223 (United States); Beniash, Elia [Department of Oral Biology, University of Pittsburgh, Pittsburgh, PA (United States); Saborowski, Reinhard [Alfred Wegener Institute, Helmholtz Centre for Polar, Marine Research, Functional Ecology, 27570 Bremerhaven (Germany); Sokolova, Inna M., E-mail: isokolov@uncc.edu [Department of Biology, University of North Carolina at Charlotte, Charlotte, NC 28223 (United States)

    2014-04-01

    Highlights: • Elevated PCO₂ enhanced accumulation of Cu and Cd in the gills of mollusks. • The proteasome activities were affected by metals but robust to elevated PCO₂. • Exposure to Cd and Cu had opposite effects on the proteasome activity. • Combined exposure to Cu and elevated PCO₂ negatively affected energy status. - Abstract: Increased anthropogenic emission of CO₂ changes the carbonate chemistry and decreases the pH of the ocean. This can affect the speciation and the bioavailability of metals in polluted habitats such as estuaries. However, the effects of acidification on metal accumulation and stress response in estuarine organisms including bivalves are poorly understood. We studied the interactive effects of CO₂ and two common metal pollutants, copper (Cu) and cadmium (Cd), on metal accumulation, intracellular ATP/ubiquitin-dependent protein degradation, stress response and energy metabolism in two common estuarine bivalves—Crassostrea virginica (eastern oyster) and Mercenaria mercenaria (hard shell clam). Bivalves were exposed for 4–5 weeks to clean seawater (control) and to either 50 μg L⁻¹ Cu or 50 μg L⁻¹ Cd at one of three partial pressures of CO₂ PCO₂ ~395, ~800 and ~1500 μatm) representative of the present-day conditions and projections of the Intergovernmental Panel for Climate Change (IPCC) for the years 2100 and 2250, respectively. Clams accumulated lower metal burdens than oysters, and elevated PCO₂ enhanced the Cd and Cu accumulation in mantle tissues in both species. Higher Cd and Cu burdens were associated with elevated mRNA expression of metal binding proteins metallothionein and ferritin. In the absence of added metals, proteasome activities of clams and oysters were robust to elevated PCO₂, but PCO₂ modulated the proteasome response to metals. Cd exposure stimulated the chymotrypsin-like activity of the oyster proteasome

  16. [Abundance and body size of Menippe mercenaria (Crustacea: Brachyura), in artificial refuges in Quintana Roo, Mexico].

    Science.gov (United States)

    Cervantes-Martínez, A; Ramírez-González, A

    2001-01-01

    In Florida and Cuba the stone crab Menippe mercenaria (Say, 1818) is under strong fishing-pressure; nevertheless in the Mexican Caribbean it is considered as sub-utilized and poorly known resource. Artificial shelters ("condominios cubanos") were used to study relative abundance, age structure, claw length-carapace amplitude relation, and population in three seasons and four sectors at Bahía Ascension, Quintana Roo, Mexico. The abundance varied according to the sector and sampling season: population was higher in the south and during the north wind ("Nortes") season (January to March). The carapace amplitude was directly proportional to claw length (r2 = 0.83, 0.97 and 0.89; p < 0.05 in females, males and total, respectively). The results suggest that specimens with 37.5 and 67.5 mm of carapace amplitude are the most limited regarding refuge availability in the Bay. PMID:12189819

  17. The Toxicity of Ammonia to the Summer Flounder (Paralychtus Dentatus), Atlantic Silverside (Menidia Menidia), and Quahog Clam (Mercenaria Mercenaria)

    OpenAIRE

    Starbuck, Steven M.

    1998-01-01

    The toxicity of ammonia has become an issue in recent years, especially in the Chesapeake Bay watershed. Currently, the EPA has set a chronic criterion of 0.035 mg/L (unionized ammonia). The chronic criterion is a four-day average concentration that cannot be exceeded more than once every three years. However, a lack of data exists on the toxicity of ammonia to saltwater organisms. Prior to this research, the chronic criterion was based on two saltwater and four freshwater organisms. This res...

  18. Accumulation and elimination of Escherichia coli and Salmonella typhimurium by hard clams in an in vitro system.

    OpenAIRE

    Timoney, J F; Abston, A

    1984-01-01

    A simple, in vitro protocol was devised to study contamination by and subsequent elimination of Escherichia coli and Salmonella typhimurium in the hard clam, Mercenaria mercenaria. The test bacteria were eliminated rapidly at similar rates for 8 h after exposure and less rapidly thereafter. At 24 h, numbers of E. coli had declined more than S. typhimurium. Bacteria were cleared in the form of rapidly sedimenting fecal and pseudofecal particulates with which the bacteria were stably associated...

  19. A Marked Gradient in δ13C Values of Clams Mercenaria mercenaria Across a Marine Embayment May Reflect Variations in Ecosystem metabolism

    Science.gov (United States)

    Although stable isotopes of organic carbon (δ13C) are typically used as indicators of terrestrial, intertidal, and offshore organic carbon sources to coastal ecosystems, there is evidence that δ13C values are also sensitive to in situ ecosystem metabolism. To investigate this phe...

  20. Lipid remodeling in wild and selectively bred hard clams at low temperatures in relation to genetic and physiological parameters.

    Science.gov (United States)

    Pernet, Fabrice; Tremblay, Réjean; Gionet, Chantal; Landry, Thomas

    2006-12-01

    A temperature decrease usually induces an ordering effect in membrane phospholipids, which can lead to membrane dysfunction. Poikilotherms inhabiting eurythermal environments typically counteract this temperature effect by remodeling membrane lipids as stipulated in the homeoviscous adaptation theory (HVA). Hard clams, Mercenaria mercenaria, can suffer high overwintering mortalities in the Gulf of St Lawrence, Canada. The selectively bred M. mercenaria var. notata can have higher overwintering mortalities than the wild species, thus suggesting that the two varieties have different degrees of adaptation to low temperatures. The objective of this study was to investigate the changes in lipid composition of soft tissues in wild and selected hard clams in relation to their metabolic and genetic characteristics. Clams were placed at the northern limit of their distribution from August 2003 to May 2004; they were exposed to a gradual temperature decrease and then maintained at <0 degrees C for 3.5 months. This study is the first to report a major remodeling of lipids in this species as predicted by HVA; this remodeling involved a sequential response of the phospholipid to sterol ratio as well as in levels of 22:6n-3 and non-methylene interrupted dienoic fatty acids. Hard clams showed an increase in 20:5n-3 as temperature decreased, but this was not maintained during overwintering, which suggests that 20:5n-3 may have been used for eicosanoid biosynthesis as a stress response to environmental conditions. Selectively bred hard clams were characterized by a higher metabolic demand and a deviation from Hardy-Weinberg equilibrium at several genetic loci due to a deficit in heterozygote frequency compared with wild clams, which is believed to impose additional stress and render these animals more vulnerable to overwintering mortality. Finally, an intriguing finding is that the lower metabolic requirements of wild animals coincide with a lower unsaturation index of their lipids

  1. Interactive effects of mosquito control insecticide toxicity, hypoxia, and increased carbon dioxide on larval and juvenile eastern oysters and hard clams.

    Science.gov (United States)

    Garcia, R N; Chung, K W; Key, P B; Burnett, L E; Coen, L D; Delorenzo, M E

    2014-04-01

    Mosquito control insecticide use in the coastal zone coincides with the habitat and mariculture operations of commercially and ecologically important shellfish species. Few data are available regarding insecticide toxicity to shellfish early life stages, and potential interactions with abiotic stressors, such as low oxygen and increased CO2 (low pH), are less understood. Toxicity was assessed at 4 and 21 days for larval and juvenile stages of the Eastern oyster, Crassostrea virginica, and the hard clam, Mercenaria mercenaria, using two pyrethroids (resmethrin and permethrin), an organophosphate (naled), and a juvenile growth hormone mimic (methoprene). Acute toxicity (4-day LC50) values ranged from 1.59 to >10 mg/L. Overall, clams were more susceptible to mosquito control insecticides than oysters. Naled was the most toxic compound in oyster larvae, whereas resmethrin was the most toxic compound in clam larvae. Mortality for both species generally increased with chronic insecticide exposure (21-day LC50 values ranged from 0.60 to 9.49 mg/L). Insecticide exposure also caused sublethal effects, including decreased swimming activity after 4 days in larval oysters (4-day EC50 values of 0.60 to 2.33 mg/L) and decreased growth (shell area and weight) in juvenile clams and oysters after 21 days (detected at concentrations ranging from 0.625 to 10 mg/L). Hypoxia, hypercapnia, and a combination of hypoxia and hypercapnia caused mortality in larval clams and increased resmethrin toxicity. These data will benefit both shellfish mariculture operations and environmental resource agencies as they manage the use of mosquito control insecticides near coastal ecosystems. PMID:24531857

  2. Effects of Hypoxia on Animal Burrow Constraction and Consequent Effects on Sediment Redox Profiles (SETAC08)

    Science.gov (United States)

    We investigated the effects of mild hypoxia on the burrowing behavior of three marine species (the hard clam Mercenaria mercenaria, the polychaete worm Nereis virens, and the amphipod Leptocheirus plumulosus) and consequent effects on sediment redox profiles. Animals were introdu...

  3. Assimilation efficiencies and turnover rates of trace elements in marine bivalves: A comparison of oysters, clams and mussels

    Science.gov (United States)

    Reinfelder, J.R.; Wang, W.-X.; Luoma, S. N.; Fisher, N.S.

    1997-01-01

    Assimilation efficiencies (AEs) and physiological turnover-rate constants (k) of six trace elements (Ag, Am, Cd, Co, Se, Zn) in four marine bivalves (Crassostrea virginica Gmelin,Macoma balthica Linnaeus, Mercenaria mercenaria Linnaeus, and Mytilus edulis Linnaeus) were measured in radiotracer-depuration experiments. Egestion rates of unassimilated elements were highest during the first 24 h of depuration and declined thereafter. Significant egestion of unassimilated Co, however, continued for up to 5 d in Macoma balthica,Mercenaria mercenaria and Mytilus edulis. With the exception of the extremely low values for110 mAg, 109Cd, and 65Zn in C. virginica, physiological turnover-rate constants (k) showed no general pattern of variation among elements, bivalve species or food types, and were relatively invariant. Values from  ≤0.001 to 0.1 d−1 were observed, but excluding those for Co, most values were  ≤0.04 d−1. In all four species, the AEs of Ag, Am, and Co were generally lower than those of Cd, Se, and Zn. The AEs of Ag, Cd, Se, and Zn in these bivalves are directly related to the proportion of each element in the cytoplasmic fraction of ingested phytoplankton, indicating that >80% of elements in a prey alga's cytoplasm was assimilated. C. virginica, Macoma balthica, and Mercenaria mercenaria assimilated ∼36% of the Ag and Cd associated with the non-cytoplasmic (membrane/organelle) fraction of ingested cells in addition to the cytoplasmic fraction. The ratio of AE:k, which is proportional to the consumer–prey trace-element bioaccumulation factor (concentration in consumer:concentration in prey) was generally greater for Cd, Se, and Zn than for Ag, Am, and Co. This ratio was lowest in Mytilus edulis, suggesting that this bivalve, the most widely employed organism in global biomonitoring, is relatively inefficient at accumulating important elements such as Ag, Cd, and Zn from ingested phytoplankton.

  4. Processing clam meat into pickles

    OpenAIRE

    P. K. Vijayan; Perigreen, P.A.; Surendran, P.K.; K. K. Balachandran

    1982-01-01

    Methods have been worked out for the production of pickles from clam (Velorita sp.) meat. The bacteriological quality of the clam meat at different stages of processing was studied. The clam pickles packed in glass bottles and sealed air tight remained in good condition for six months at ambient temperatures.

  5. The effects of the contemporary-use insecticide (fipronil) in an estuarine mesocosm

    International Nuclear Information System (INIS)

    To examine the effects of environmentally realistic fipronil concentrations on estuarine ecosystems, replicated mesocosms containing intact marsh plots and seawater were exposed to three treatments of fipronil (150, 355, and 5000 ng/L) and a Control. Juvenile fish (Cyprinidon variegatus), juvenile clams (Mercenaria mercenaria), oysters (Crassostrea virginica), and grass shrimp (Palaemonetes pugio) were added prior to fipronil in an effort to quantify survival, growth, and the persistence of toxicity during the planned 28-day exposure. Results indicated that there were no fipronil-associated effects on the clams, oysters, or fish. Shrimp were sensitive to the highest two concentrations (40% survival at 355 ng/L and 0% survival at 5000 ng/L). Additionally, the highest fipronil treatment (5000 ng/L) was toxic to shrimp for 6 weeks post dose. These results suggest that fipronil may impact shrimp populations at low concentrations and further use in coastal areas should be carefully assessed

  6. DGGE-based detection method for Quahog Parasite Unknown (QPX).

    Science.gov (United States)

    Gast, R J; Cushman, E; Moran, D M; Uhlinger, K R; Leavitt, D; Smolowitz, R

    2006-06-12

    Quahog Parasite Unknown (QPX) is a significant cause of hard clam Mercenaria mercenaria mortality along the northeast coast of the United States. It infects both wild and cultured clams, often annually in plots that are heavily farmed. Subclinically infected clams can be identified by histological examination of the mantle tissue, but there is currently no method available to monitor the presence of QPX in the environment. Here, we report on a polymerase chain reaction (PCR)-based method that will facilitate the detection of QPX in natural samples and seed clams. With our method, between 10 and 100 QPX cells can be detected in 1 l of water, 1 g of sediment and 100 mg of clam tissue. Denaturing gradient gel electrophoresis (DGGE) is used to establish whether the PCR products are the same as those in the control QPX culture. We used the method to screen 100 seed clams of 15 mm, and found that 10 to 12% of the clams were positive for the presence of the QPX organism. This method represents a reliable and sensitive procedure for screening both environmental samples and potentially contaminated small clams. PMID:16875398

  7. Visualization System for Burrowing Organisms in Granular Substrates

    CERN Document Server

    Winter, Amos G

    2008-01-01

    This fluid dynamics video demonstrates the capabilities of an experimental setup to visualize organisms burrowing in granular substrates. The setup consists of a tank filled with 1mm soda-lime glass beads, backlit by halogen lights. The walls can be moved such that the space bound by them can expand or contract to fit various organisms. A recirculation system oxygenates and cools the salt water that flows through the substrate. The video shows the burrowing behavior of a razor clam (Ensis directus) and a quahog (Mercenaria mercenaria). Both animals inflate their foot with blood, making the foot a terminal anchor against which they pull their shell downwards. Deformation of the granular substrate can be seen around the animals as they advance downwards.

  8. Environmental distribution and persistence of Quahog Parasite Unknown (QPX).

    Science.gov (United States)

    Gast, Rebecca J; Moran, Dawn M; Audemard, Corinne; Lyons, M Maille; DeFavari, Jackie; Reece, Kimberly S; Leavitt, Dale; Smolowitz, Roxanna

    2008-09-24

    Quahog Parasite Unknown (QPX) is the cause of mass mortality events of hard clams Mercenaria mercenaria from Virginia, USA, to New Brunswick, Canada. Aquaculture areas in Massachusetts, USA, have been particularly hard hit. The parasite has been shown to be a directly infective organism, but it is unclear whether it could exist or persist outside of its clam host. We used molecular methods to examine water, sediment, seaweeds, seagrass and various invertebrates for the presence of QPX. Sites in Virginia and Massachusetts were selected based upon the incidence of QPX-induced clam die-offs, and they were monitored seasonally. QPX was detectable in almost all of our different sample types from Massachusetts, indicating that the parasite was widely distributed in the environment. Significantly more samples from Massachusetts were positive than from Virginia, and there was a seasonal pattern to the types of samples positive from Massachusetts. The data suggest that, although it may be difficult to completely eradicate QPX from the environment, it may be possible to keep the incidence of disease under control through good plot husbandry and the removal of infected and dying clams. PMID:18998586

  9. Potential of irradiation technology for improved shellfish sanitation

    International Nuclear Information System (INIS)

    Ionizing radiation is shown capable of serving as an effective sanitizing treatment improving the sanitary quality of shellfish and providing an increased margin of safety for shellfish consumers. 60Co irradiation of the hard-shelled clam, Mercenaria mercenaria, and the oyster, Crassostrea virginica, significantly reduced virus carriage numbers without unduly affecting shellfish survival rates or desirable organoleptic qualities. A D10 value of 2 kGy was determined for depletion of hepatitis A virus in clams and oysters as measured by in situ hybridization fluorescent foci and cytopathology enumeration methods. A D10 value of 2.4 kGy was determined for depletion of rotavirus SA11 in clams and oysters as measured by a plaque forming unit enumeration method. Study results showed ionizing radiation capable of providing an extra, highly effective safeguard of shellfish sanitary quality when combined with traditional depuration treatment. Data drawn from other studies is introduced which shows D10 values as low as 1.0 kGy effectively eliminate Vibrio cholerae, and V. parahemolyticus, from shellfish

  10. A non-native prey mediates the effects of a shared predator on an ecosystem service.

    Directory of Open Access Journals (Sweden)

    James E Byers

    Full Text Available Non-native species can alter ecosystem functions performed by native species often by displacing influential native species. However, little is known about how ecosystem functions may be modified by trait-mediated indirect effects of non-native species. Oysters and other reef-associated filter feeders enhance water quality by controlling nutrients and contaminants in many estuarine environments. However, this ecosystem service may be mitigated by predation, competition, or other species interactions, especially when such interactions involve non-native species that share little evolutionary history. We assessed trophic and other interference effects on the critical ecosystem service of water filtration in mesocosm experiments. In single-species trials, typical field densities of oysters (Crassostrea virginica reduced water-column chlorophyll a more strongly than clams (Mercenaria mercenaria. The non-native filter-feeding reef crab Petrolisthes armatus did not draw down chlorophyll a. In multi-species treatments, oysters and clams combined additively to influence chlorophyll a drawdown. Petrolisthes did not affect net filtration when added to the bivalve-only treatments. Addition of the predatory mud crab Panopeus herbstii did not influence oyster feeding rates, but it did stop chlorophyll a drawdown by clams. However, when Petrolisthes was also added in with the clams, the clams filtered at their previously unadulterated rates, possibly because Petrolisthes drew the focus of predators or habituated the clams to crab stimuli. In sum, oysters were the most influential filter feeder, and neither predators nor competitors interfered with their net effect on water-column chlorophyll. In contrast, clams filtered less, but were more sensitive to predators as well as a facilitative buffering effect of Petrolisthes, illustrating that non-native species can indirectly affect an ecosystem service by aiding the performance of a native species.

  11. Strong biological controls on Sr/Ca ratios in aragonitic marine bivalve shells

    Science.gov (United States)

    Gillikin, David Paul; Lorrain, Anne; Navez, Jacques; Taylor, James W.; André, Luc; Keppens, Eddy; Baeyens, Willy; Dehairs, Frank

    2005-05-01

    It is well known that skeletal remains of carbonate secreting organisms can provide a wealth of information about past environments. Sr/Ca ratios have been successfully used as a temperature proxy in corals and sclerosponges. Previous work on aragonitic bivalve shells has not been conclusive but suggests a major control of growth rate on Sr/Ca ratios. As many studies have used bivalve growth rates to determine temperature, we tested if Sr/Ca ratios could predict temperature through its relationship with growth rate. Shells from the two species of clams from the same family (veneroidea) studied here, Saxidomus giganteus and Mercenaria mercenaria, show vastly different seasonal Sr/Ca profiles. A strong relationship between average annual Sr/Ca ratios and annual growth rate was found in S. giganteus shells from both Washington (R2 = 0.87) and Alaska (R2 = 0.64), USA, but not in M. mercenaria shells from North Carolina, USA. Furthermore, the Sr/Ca-growth rate relationship was also evident upon a more detailed inspection of subannual growth rates in S. giganteus (R2 = 0.73). Although there were significant positive correlations between Sr/Ca ratios and temperature in S. giganteus shells, the correlations were weak (0.09 control in either clam species, since thermodynamics predict a negative correlation between Sr/Ca ratios and temperature in aragonite. This points toward dominance of biological processes in the regulation of Sr2+. This is also reflected by the largely differing Sr/Ca partition coefficients (DSr) in these shells (DSr ≈ 0.25), when compared to inorganic, coral, and sclerosponge studies (DSr ≈ 1), all of which show a negative dependence of Sr/Ca on temperature. We suggest that caution be taken when using Sr/Ca in any biogenic aragonite as a temperature proxy when the DSr greatly deviates from one, as this indicates the dominance of biological controls on Sr/Ca ratios.

  12. Dead zones enhance key fisheries species by providing predation refuge.

    Science.gov (United States)

    Altieri, Andrew H

    2008-10-01

    Natural stress gradients can reduce predation intensity and increase prey abundances. Whether the harsh conditions of anthropogenic habitat degradation can similarly reduce predation intensity and structure community dynamics remains largely unexplored. Oxygen depletion in coastal waters (hypoxia) is a form of degradation that has recently emerged as one of the greatest threats to coastal ecosystems worldwide due to increased rates of eutrophication and climate change. I conducted field experiments and surveys to test whether relaxed predation could explain the paradoxically high abundance of clams that have sustained a fishery in a degraded estuary with chronic hypoxic conditions. Hypoxia reduced predation on all experimental species but enhanced the long-term survivorship of only sufficiently hypoxia-tolerant prey due to periodic extreme conditions. As a consequence, only the harvested quahog clam (Mercenaria mercenaria) thrived in hypoxic areas that were otherwise rendered dead zones with depauperate diversity and low abundances of other species. This suggests that enhanced populations of some key species may be part of a predictable nonlinear community response that sustains ecosystem services and masks overall downward trends of habitat degradation. PMID:18959318

  13. Optimal escapement in stage-structured fisheries with environmental stochasticity.

    Science.gov (United States)

    Holden, Matthew H; Conrad, Jon M

    2015-11-01

    Stage-structured population models are commonly used to understand fish population dynamics and additionally for stock assessment. Unfortunately, there is little theory on the optimal harvest of stage-structured populations, especially in the presence of stochastic fluctuations. In this paper, we find closed form optimal equilibrium escapement policies for a three-dimensional, discrete-time, stage-structured population model with linear growth, post-harvest nonlinear recruitment, and stage-specific pricing and extend the analytic results to structured populations with environmental stochasticity. When only fishing reproductive adults, stochasticity does not affect optimal escapement policies. However, when harvesting immature fish, the addition of stochasticity can increase or decrease optimal escapement depending on the second and third derivative of the recruitment function. For logistic recruitment, stochasticity reduces optimal immature escapement by a multiplicative factor of one over one plus the variance of the environmental noise. Using hard clam, Mercenaria mercenaria, as an example and assuming Beverton-Holt recruitment, we show that optimal fishing of hard clam targets the immature stage class exclusively and that environmental stochasticity increases optimal escapement for low discount rates and decreases optimal escapement for high discount rates. PMID:26362229

  14. The Clam Trail: Blending Science Education, Public Art, and Tourism

    Science.gov (United States)

    Muscio, Cara; Flimlin, Gef; Bushnell, Rick

    2011-01-01

    The Barnegat Bay Shellfish Restoration's Clam Trail is an award-winning scavenger hunt that combines science education, public art, and tourism. This family adventure has participants seeking out giant painted fiberglass clams, upweller clam nurseries, and points of interest in search of science facts to record on their forms. Upon returning these…

  15. 50 CFR 648.72 - Minimum surf clam size.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Minimum surf clam size. 648.72 Section 648.72 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... Atlantic Surf Clam and Ocean Quahog Fisheries § 648.72 Minimum surf clam size. (a) Minimum length....

  16. Response of the Asiatic clam, Corbicula manilensis, to gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Tilly, L.J.; Corey, J.C.; Bibler, N.E.

    1977-01-01

    When heat exchangers for reactors were plugged by the Asiatic clam, acute gamma radiation was considered as a possible control. Clams were collected and sorted by size; during irradiation the clams were submerged in natural water. Clams of both sizes survived large doses with no radiation damage evident in 30 days. Mortality rose steeply at doses of 2.4 x 10/sup 4/ Rad and above; smaller clams showed a greater resistance than large ones. The feasibility of using periodic exposure to gamma radiation as a means for controlling corbicula infestations is discussed. (HLW)

  17. Analysis of Hongdao Clam Industrial Structure Based on Industry Chain

    Institute of Scientific and Technical Information of China (English)

    Jiang; Xianqiong

    2014-01-01

    The vertical and transverse structures of Hongdao clam industry are described and analyzed objectively based on the perspective of industry chain. On the basis of field investigation,the key nodes of Hongdao clam industry chain,including nursery,breeding,processing,transportation and sale,are analyzed. It can be concluded that the development of clam industry chain is unbalanced,especially the deep-processing capacity is not strong,and the development of supporting industy lags behind. The horizontal industry chain of clam needs to be further improved. The corresponding suggestions are put forward: strengthening research on new nursery technology in later period,further extending the horizontal industry chain of clam,mining the depth of clam-related leisure industry,and upgrading service level of leisure travel.

  18. Analysis of trace elements in the shell of asari clams

    International Nuclear Information System (INIS)

    Strontium concentration in the shells of asari clams collected at different locations was analyzed by PIXE. The Sr concentration of external surface of shell umbo was ranged from 1000 to 3500 ppm for individuals. The Sr concentration of clams collected at Shirahama showed positive correlation with shell length, whereas clams collected at Maizuru did not show significant correlation. This result may be caused from the difference of the spawning seasons between two areas. (author)

  19. Toxicity of fishery chemicals to the asiatic clam, Corbicula manilensis

    Science.gov (United States)

    Chandler, Jack H.; Marking, L.L.

    1979-01-01

    The Asiatic clam (Corbicula manilensis), a species introduced into U. S. waters, has spread rapidly, and its ability to survive, reproduce, and spread has caused concern. Aquatic biologists suspect that the clams may crowd out indigenous mollusks, and the animals sometimes plug water intakes and leave shell deposits that interfere with sand and gravel operations. The toxicity of 20 commonly used fishery chemicals to the Asiatic clam was determined to evaluate hazards to a nontarget aquatic invertebrate and to assess the potential of the chemicals for controlling clam populations. Among six piscicides and two lampricides tested, antimycin was most toxic to the clam; the 96-h LC50 was 0.065 mg/L. Among three therapeutants and two disinfectants tested, nifurpirinol was the most toxic; the 96-h LC50 was 7.60 mg/L. All of the compounds were less toxic to the clam than to fish. As a nontarget organism, this clam would be safe in water treated with any of the tested fishery chemicals at recommended use pattern concentrations. None of the chemicals have potential for controlling unwanted populations of these clams.

  20. Manila clam Venerupis philippinarum as a biomonitor to metal pollution

    Science.gov (United States)

    Wu, Huifeng; Ji, Chenglong; Wang, Qing; Liu, Xiaoli; Zhao, Jianmin; Feng, Jianghua

    2013-01-01

    The Manila clam Venerupis philippinarum is a good biomonitor/bioindicator to marine metal pollution and is frequently used in aquatic toxicology. Two dominant pedigrees (white and zebra) of clam are distributed in the Bohai Sea; however, little attention has been paid to potential biological differences between these two pedigrees. In this study, we tested the sensitivity of both pedigrees to marine metal (cadmium and zinc) pollution biomonitoring and marine environmental toxicology. Results demonstrate significant biological differences in gills of white and zebra clams based on metabolic profiles and antioxidant enzyme activities. In addition, we found that hypotaurine, malonate and homarine were relatively high in white clam gills, while alanine, arginine, glutamate, succinate, 4-aminobutyrate, taurine and betaine were high in zebra clam gills. Zebra clam gills were also more sensitive to a mixture of Cd and Zn, as shown by antioxidant enzyme activities and metabolic profiles, but white clam gills could accumulate more Zn. Therefore, we suggest that the white pedigree can be used as a biomonitor to marine Zn pollution, whereas the zebra pedigree can be used for toxicology studies on Cd and Zn mixed pollution.

  1. Manila clam Venerupis philippinarum as a biomonitor to metal pollution

    Institute of Scientific and Technical Information of China (English)

    WU Huifeng; JI Chenglong; WANG Qing; LIU Xiaoli; ZHAO Jianmin; FENG Jianghua

    2013-01-01

    The Manila clam Venerupis philippinarum is a good biomonitor/bioindicator to marine metal pollution and is frequently used in aquatic toxicology.Two dominant pedigrees (white and zebra) of clam are distributed in the Bohai Sea; however,little attention has been paid to potential biological differences between these two pedigrees.In this study,we tested the sensitivity of both pedigrees to marine metal (cadmium and zinc) pollution biomonitoring and marine environmental toxicology.Results demonstrate significant biological differences in gills of white and zebra clams based on metabolic profiles and antioxidant enzyme activities.In addition,we found that hypotaurine,malonate and homarine were relatively high in white clam gills,while alanine,arginine,glutamate,succinate,4-aminobutyrate,taurine and betaine were high in zebra clam gills.Zebra clam gills were also more sensitive to a mixture of Cd and Zn,as shown by antioxidant enzyme activities and metabolic profiles,but white clam gills could accumulate more Zn.Therefore,we suggest that the white pedigree can be used as a biomonitor to marine Zn pollution,whereas the zebra pedigree can be used for toxicology studies on Cd and Zn mixed pollution.

  2. Historic and Present-Day Environmental Issues Involving Tomato Plasticulture and Shellfish Aquaculture on Virginia’s Eastern Shore

    OpenAIRE

    Templeton, Jennifer

    2013-01-01

    The Eastern Shore of Virginia, located on the Delmarva Peninsula, is known for its agricultural commodities, especially Solanum lycopersicum, Crassostrea Virginia, and Mercenaria mercenaria. For decades, controversy has surrounded the two industries. Runoff from fields of tomatoes grown in plastic mulch was thought to have caused mass casualties of shellfish in hatcheries in the tidal creeks and bays of the Eastern Shore. The impervious surface of the plastic mulch decreases infiltration of r...

  3. Razor clam to RoboClam: burrowing drag reduction mechanisms and their robotic adaptation

    International Nuclear Information System (INIS)

    Estimates based on the strength, size, and shape of the Atlantic razor clam (Ensis directus) indicate that the animal's burrow depth should be physically limited to a few centimeters; yet razor clams can dig as deep as 70 cm. By measuring soil deformations around burrowing E. directus, we have found the animal reduces drag by contracting its valves to initially fail, and then fluidize, the surrounding substrate. The characteristic contraction time to achieve fluidization can be calculated directly from soil properties. The geometry of the fluidized zone is dictated by two commonly-measured geotechnical parameters: coefficient of lateral earth pressure and friction angle. Calculations using full ranges for both parameters indicate that the fluidized zone is a local effect, occurring between 1–5 body radii away from the animal. The energy associated with motion through fluidized substrate—characterized by a depth-independent density and viscosity—scales linearly with depth. In contrast, moving through static soil requires energy that scales with depth squared. For E. directus, this translates to a 10X reduction in the energy required to reach observed burrow depths. For engineers, localized fluidization offers a mechanically simple and purely kinematic method to dramatically reduce energy costs associated with digging. This concept is demonstrated with RoboClam, an E. directus-inspired robot. Using a genetic algorithm to find optimal digging kinematics, RoboClam has achieved localized fluidization burrowing performance comparable to that of the animal, with a linear energy-depth relationship, in both idealized granular glass beads and E. directus' native cohesive mudflat habitat. (paper)

  4. Polymorphisms at three introns in the Manila clam (Ruditapes philippinarum) and the grooved carpet-shell clam (R. decussatus)

    OpenAIRE

    Cordero, David; Peña, Juan B.; Saavedra, Carlos J.

    2008-01-01

    We have designed a set of exon-primed intron-crossing (EPIC) PCR primers to amplify introns at the genes TBP and SRP54 in the Manila clam (Ruditapes philippinarum) and the grooved carpet-shell clam (R. decussatus), and also one intron at a histone 3 homologous gene in the Manila clam. The primers were developed by using >universal> EPIC primers available in the literature and by searching for intron locations in cDNA sequences taken from public databases. The identity of the amplified product...

  5. Bioeconomic modelling of hard clam growout in Florida: the replacement decision

    OpenAIRE

    Holiman, Stephen G.; Weldon, Richard N.; Thunberg, Eric M.; Adams, Charles B.; Thomas H. Spreen

    1995-01-01

    A decision to undertake hard clam growout aquaculture in Florida, therefore, requires knowledge of appropriate production systems, sources of operation risk, the effects of risk on operation design and replacement scheduling, and estimates of the costs and returns of hard clam growout under risk. The specific objectives of this research project were: 1. Develop a bioeconomic model of Florida hard clam growout. 2. Generate cost and return estimates of hard clam growout under dif...

  6. Toxicity of a traditional molluscicide to asian clam veligers

    Science.gov (United States)

    Layhee, Megan J.; Miho Yoshioka; Miho Yoshioka; Bahram Farokhkish; Bahram Farokhkish; Gross, Jackson A.; Sepulveda, Adam J.

    2014-01-01

    Aquaculture and hatchery industries are in need of effective control methods to reduce the risk of spreading aquatic invasive species, such as the Asian clam Corbicula fluminea, through aquaculture and hatchery activities. The planktonic nature of Asian clam veligers enables this life stage to enter water-based infrastructure undetected, including hatchery trucks used to stock fish. Once in hatchery trucks, veligers can disperse overland and establish in previously uninvaded habitats. As a result, there is a need to develop techniques that result in veliger mortality but do not harm fish. In September 2012, we conducted laboratory trials to determine if a molluscicide (750 mg/L potassium chloride and 25 mg/L formalin) commonly used to kill zebra mussel (Dreissena polymorpha) veligers in hatchery trucks can also effectively kill Asian clam veligers. We exposed Asian clam veligers to this molluscicide for 1, 3, and 5 h in each of two water types: deionized water and filtered lake water. We found ,20% mortality at the 1-h exposure period and 100% mortality at both the 3-h and 5-h exposure periods, regardless of water type. This laboratory study represents an important step toward reducing the spread of Asian clams by aquaculture facilities.

  7. An efficient method of noroviruses recovery from oysters and clams

    Science.gov (United States)

    Zhou, Deqing; Ma, Liping; Zhao, Feng; Yao, Lin; Su, Laijin; Li, Xinguang

    2013-03-01

    Noroviruses (NoVs) are widespread causes of nonbacterial gastroenteritis. Outbreaks of NoVs caused diseases are commonly ascribed to the consumption of contaminated shellfish. The concentration and RNA extraction of NoVs are crucial steps of detecting NoVs in shellfish. This study aimed to select a simple, rapid and highly efficient recovery method of NoVs detection with real-time RT-PCR. Four methods of recovering GI.3 and GII.4 NoVs from spiked digestive tissues of oysters and clams, respectively, were compared, of them, the method involving proteinase K and PEG 8000 was found the most efficient. With this method, 9.3% and 13.1% of GI.3 and GII.4 NoVs were recovered from oysters and 9.6% and 12.3% of GI.3 and GII.4 NoVs were recovered from clams, respectively. This method was further used to detect NoVs in 84 oysters ( Crassostrea gigas) and 86 clams ( Ruditapes philippinarum) collected from 10 coastal cities in China from Jan. 2011 to Feb. 2012. The NoVs isolation rates were 10.47% of clams (9/86) and 7.14% of oysters (6/84). All the detected NoVs belonged to genotype GII. The NoVs recovery method selected is efficient for NoVs detection in oysters and clams.

  8. Investigation of radiocesium biokinetics in Manila clam (Ruditapes philippinarum)

    International Nuclear Information System (INIS)

    This study was carried out to better understand the biokinetics of radiocesium in clams living in sediment. The accumulation and depuration kinetics of 134Cs were investigated in the Manila clam (Ruditapes philippinarum) under controlled laboratory conditions. The concentration factor was found to be 3.0 for 134Cs in the whole body; however, the concentration factor in the soft part of the clams (12) was significantly higher than those in the whole body and shell (0.80). The depuration kinetics of the radionuclide were described by a two-component exponential model for the whole body. The biological half-lives in the fast and slow components were found to be 0.63 and 22.1 days, respectively. The depuration kinetics for 134Cs in the soft parts were described by a single-component exponential model with a resultant the biological half-life of 18.0 days. (author)

  9. Performance Characteristics of AOAC Method 2005.06 for the Determination of Paralytic Shellfish Toxins in Manila Clams, European Otter Clams, Grooved Carpet Shell Clams, Surf Clams, and Processed King Scallops.

    Science.gov (United States)

    O'Neill, Alison; Turner, Andrew D

    2015-01-01

    An approach was developed for the verification of method performance of the AOAC 2005.06 LC-fluorescence detector (FLD) method for determination of paralytic shellfish poisoning (PSP) toxins in bivalve shellfish. This was developed following advice published by the Analytical Laboratory Accreditation Criteria Committee and applied to shellfish species that had not been previously subjected to a full single-laboratory validation scheme. The refined approach was developed following the need to assess performance in a number of shellfish species infrequently monitored through the UK statutory monitoring program, while reducing the impact and cost of the studies, most notably in terms of the use of valuable reference standards. The species assessed were manila clams (Ruditapes philippinarum), European otter clams (Lutraria lutraria), grooved carpet shell clams (R. decussatus), surf clams (Spisula solida), and king scallops (Pecten maximus) presented as adductor only or adductor plus roe. The method was assessed for sensitivity in terms of LOD and LOQ, toxin recovery, and method precision in each species. It incorporated the PSP toxins deemed toxic and/or prevalent in UK samples and commercially available as certified reference standards. The toxins studied included GTX1-5, dcSTX, STX, C1&2, and NEO. The toxins dcGTX2&3 were included for surf clams due to the prevalence of these toxins in this species as a result of toxin decarbamoylation. Method performance targets were met for each of the characteristics investigated. Consequently, the method was deemed fit for purpose for the screening and quantification of these clam and scallop species for PSP toxins by AOAC Method 2005.06 LC-FLD. PMID:26024751

  10. Effect of Surface Preparation on CLAM/CLAM Hot Isostatic Pressing diffusion bonding joints

    International Nuclear Information System (INIS)

    Surface preparation is essential for the Hot Isostatic Pressing (HIP) diffusion bonding of RAFM steels. Hot Isostatic Pressing (HIP) diffusion bonding experiments on China Low Activation Martensitic (CLAM) steel was performed to study the effect of surface preparation. A few approaches such as hand lapping, dry-milling and grinding etc., were used to prepare the faying surfaces of the HIP joints. Different sealing techniques were used as well. The HIP parameters were 150 MPa/3 h/1150 deg. C. After post HIP heat treatment (PHHT), the tensile and Charpy impact tests were carried out. The results showed that hand lapping was not suitable to prepare the faying surfaces of HIP diffusion bonding specimens although the surface roughness by hand lapping was very low.

  11. Development status of CLAM steel for fusion application

    Science.gov (United States)

    Huang, Qunying

    2014-12-01

    The China low activation martensitic (CLAM) steel is being developed at the Institute of Nuclear Energy Safety Technology (INEST) under wide collaboration within China. Significant R&D work on CLAM steel was carried out to help make it suitable for industrial applications. The effect of refining processes and thermal aging on composition, microstructures and mechanical properties were investigated. Material properties before irradiation including impact, fracture toughness, thermal aging, creep and fatigue properties etc. were assessed. A series of irradiation tests in the fission reactor HFETR in Chengdu up to 2 dpa and in the spallation neutron source SINQ in Paul Scherrer Institute up to 20 dpa were performed. PbLi corrosion tests for more than 10,000 h were done in the DRAGON-I and PICOLO loops. Fabrication techniques for a test blanket module (TBM) are being developed and a 1/3 scale TBM prototype is being fabricated with CLAM steel. Recent progresses on the development status of this steel are presented here. The code qualification of CLAM steel is under plan for its final application in ITER-TBM and DEMO in the future.

  12. Fabrication techniques development of test blanket module based on CLAM

    International Nuclear Information System (INIS)

    The Reduced Activation Ferritic/Martensitic steels (RAFMs) are considered as the primary candidate structural material for the DEMO fusion reactor and the first fusion power plant. China Low Activation Martensitic (CLAM) steel, a version of RAFMs, is being developed in ASIPP (Institute of Plasma Physics, Chinese Academy of Sciences), under wide collaboration with many institutes and universities in China and overseas. The designs of FDS (Fusion Design Study) series liquid LiPb blankets for fusion reactors and corresponding Dual Functional Lithium Lead (DFLL) Test Blanket Module (TBM) in International Thermonuclear Experimental Reactor (ITER) are being carried out in ASIPP. And CLAM steel is chosen as the primary candidate structural material in these designs. So the fabrication techniques for DFLL TBM with CLAM are or urgently needed to be studied in detail. The fabrication of DFLL TBM mainly includes the manufacturing of the First Wall (FW), the Cooling Plates (CP) and the joining of the FW and CPs. Currently, solid Hot Isostatic Pressing (HIP) bonding and uniaxial diffusion bonding method are the most promising candidate fabrication method for the FW and CP. Experiments of HIP and unixial diffusion bonding of CLAM/CLAM were carried out and good joints were obtained. As for the joining technique of FW and CPs, the fusion welding techniques such as Tungsten Inert Gas welding, Laser welding and Electron Beam welding are candidates. Preliminary experiments on these welding techniques were performed. The simulation of thermal process by Gleeble 2000 was also carried out. Results of these experiments are summarized and further R and D plan on blanket fabrication techniques is also stated. (authors)

  13. Effect of surface preparation on Clam/Clam HIP Diffusion Bonding joints

    International Nuclear Information System (INIS)

    Full text of publication follows: China Low Activation Martensitic (CLAM) steel has been being developed in ASIPP (Institute of Plasma Physics, Chinese Academy of Sciences) since five years ago. The primary properties of CLAM before neutron irradiation are roughly the same as those of Eurofer97 and F82H etc.. The hot isostatic pressing (HIP) bonding technique is one of the main candidate bonding techniques for manufacturing of the first wall of a fusion reactor. There are many influencing factors on properties of HIP joints and surface preparation is one of the major factors. Dry-milling, grinding and hand lapping were used to prepare the sample surfaces in the performed experiments and then the samples are treated as the following steps: 1) Degreasing with a mixture of alcohol and acetone in an ultrasonic bath; 2) Outgassing in high vacuum furnace; 3) The samples by dry-milling were seal-welded by EBW (electron beam welding) at a circular bonding zone prior to HIP. Others were canned in 304ss capsules which were seal-welded after degassing for tens of hours. The HIP parameters were 150 MPa/1150 deg. C/3 hrs. Then post HIP heat treatment was 930 deg. C/60 min/air and 745 deg. C/150 min/air. Tests of tensile strength and impact toughness for HIP joints had been performed under Room Temperature (RT) using standard samples. The tensile strength and elongation of the samples were identical to those of the base metal. However, the impact absorbed energy (IAE) of the joints using standard U-shape notched impact specimen were of great difference compared with the base material. That of samples by grinding and dry-milling was about 90 J and that of the other two joints by hand lapping was 10.3 J and 34.4 J respectively. This indicated that properties of HIP joints didn't increase with the surface roughness. HIP joint line is the weakest part of the material and just like a long grain boundary through the sample. That of the samples with very smooth surface is quite

  14. Endogenous circatidal rhythm in the Manila clam Ruditapes philippinarum (Bivalvia: Veneridae)

    OpenAIRE

    Kim, W S; Huh, H.T.; Lee, J.-H.; Rumohr, Heye; Koh, C.H.

    1999-01-01

    Manila clams, Ruditapes philippinarum, removed from their natural environment and maintained for 9 weeks in continuously immersed conditions exhibited a clear endogenous circatidal rhythm in oxygen consumption. The clams exhibited a semidiurnal rhythmicity in oxygen consumption after showing a diurnal pattern in the first few days (5 to 7 d) of the experiment. The results of the present study indicate that activity rhythms of clams are controlled not only by exogenous factors, but also by an ...

  15. Hsp 70 in the soft shell clam (Mya arenaria): Potential as a biomarker of field contamination

    International Nuclear Information System (INIS)

    Soft shell clams (Mya arenaria) were collected from 2 contaminated and 2 control sites in Massachusetts at 4 time periods, extending over a 30 degree C temperature range. Populations at New Bedford Harbor were exposed to PCBs, PAHs, and heavy metals and populations at the Cotuit Bay Shores Beach Club were exposed to an unknown quantity and composition of petroleum hydrocarbons. Heat shock protein (hsp) 70 was measured in the gill of 20 clams per site by ELISA, using a commercially available monoclonal antibody. Expression of hsp 70 was variable between individual clams collected from the same site. Significance of the variables site and month was tested by one-way and two-way ANOVA; site, month, and site by month interaction were all significant. The significant interaction term meant that it was necessary to hold the month variable constant in order to test the hypothesis that clams from the contaminated sites contained more heat shock proteins than clams from the corresponding control sites. In general, the contaminated clams contained a higher concentration of hsp 70 than clams from the control sites, with New Bedford Harbor exhibiting the highest levels. Seasonal differences which could be responsible for the month effect include heat shock, food availability, and reproductive condition. In order to use heat shock protein expression as a biomarker of exposure to contaminants in the field, it is necessary to compare clams from contaminated sites to clams from control sites sampled at the same time

  16. Depuration of shellfish by irradiation: Final technical report, October 1, 1987--March 31, 1989

    International Nuclear Information System (INIS)

    Studies by the University of Lowell Radiation Laboratory and the US National Marine Fisheries Service N.E. Laboratory in Gloucester, MA on softshelled clams (Mya arenaria) demonstrated the effectiveness of low to medium doses of Cobalt 60 source gamma irradiation in the inactivation of Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Streptococcus faecalis. Post-irradiation survival and organoleptic studies when extended to hardshelled clams (Mercinaria mercenaria) and American oysters (Crassostrea virginica) showed no significant decline in consumer qualities or 6 day post irradiation survival in oysters at doses of up to 3.0 kGy. The capacities of the American oyster to sustain relatively high doses of gamma irradiation were demonstrated by 6 day post-exposure survivorship values of greater than 90% for samples receiving 3.0, 5.0 and 7.0 kGy. Initial studies of inactivation of Polio I virus and a simian rotavirus (SA-11) was conducted in both hardshelled clams and oysters. Of greatest interest was the behavior of Hepatitis A virus (HAV), in live, irradiated shellfish. The average log decrement value for HAV in oysters was calculated at 2.0 kGy. From these data it appears that doses of up to 2 kGy can be applied to: reduce or eliminate bacterial pathogens, reduce the infectivity of human viral pathogens by one or more orders of magnitude, and preserve market qualities of longevity, appearance, odor, taste and texture. 23 refs., 11 figs., 3 tabs

  17. Depuration of shellfish by irradiation: Final technical report, October 1, 1987--March 31, 1989

    Energy Technology Data Exchange (ETDEWEB)

    Beghian, L.E.; Mallett, J.C.

    1989-01-01

    Studies by the University of Lowell Radiation Laboratory and the US National Marine Fisheries Service N.E. Laboratory in Gloucester, MA on softshelled clams (Mya arenaria) demonstrated the effectiveness of low to medium doses of Cobalt 60 source gamma irradiation in the inactivation of Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Streptococcus faecalis. Post-irradiation survival and organoleptic studies when extended to hardshelled clams (Mercinaria mercenaria) and American oysters (Crassostrea virginica) showed no significant decline in consumer qualities or 6 day post irradiation survival in oysters at doses of up to 3.0 kGy. The capacities of the American oyster to sustain relatively high doses of gamma irradiation were demonstrated by 6 day post-exposure survivorship values of greater than 90% for samples receiving 3.0, 5.0 and 7.0 kGy. Initial studies of inactivation of Polio I virus and a simian rotavirus (SA-11) was conducted in both hardshelled clams and oysters. Of greatest interest was the behavior of Hepatitis A virus (HAV), in live, irradiated shellfish. The average log decrement value for HAV in oysters was calculated at 2.0 kGy. From these data it appears that doses of up to 2 kGy can be applied to: reduce or eliminate bacterial pathogens, reduce the infectivity of human viral pathogens by one or more orders of magnitude, and preserve market qualities of longevity, appearance, odor, taste and texture. 23 refs., 11 figs., 3 tabs.

  18. Corbicula fluminea (Mollusca, Bivalvia) - the new freshwater clam for Slovakia

    International Nuclear Information System (INIS)

    Specimens of the expansive Asian freshwater clam Corbicula fluminea O. F. Mueller, 1774 (Mollusca: Bivalvia, Corbiculidae) were found on the following three localities of Danube river of Slovakia: Radvan nad Dunajom env. (DFS - 8276a), Komarno env. (DFS - 8274b), Gabcikovo env. (DFS - 8171a). The basic information about this species, key for determination and a photo of an adult individual are presented on the poster. (authors)

  19. Evaluation of 4-nonylphenol toxicity in the clam Tapes philippinarum

    International Nuclear Information System (INIS)

    Lethal and sub lethal effects of 4-nonylphenol (NP) were investigated in the clam Tapes philippinarum from the Lagoon of Venice. In a 96-h lethality test, bivalves were exposed to the following NP concentrations: 0, 0+acetone, .19, 0.38, 0.75, 1.5, and 3.0 mg NP/L. The 96-h LC50 value was 1.12 mg P/L. No mortality was observed at 0.19 mg NP/L, whereas at 1.5 and 3.0 mg P/L both siphons and foot of clams were often cut-off, the animals being unable to withdraw them before shell closure, suggesting the possible narcotic effect of NP. Lower concentrations (0, 0+acetone, 0.025, 0.05, 0.1, nd 0.2 mg NP/L) were then used to evaluate sub lethal NP effects on clearance rate (CR), respiration rate (RR), scope for growth (SFG), and survival in ir. Following a 7-day exposure, decreased RRs were found at all NP concentrations tested. Significant decreases in the CR and SFG were only observed at the two highest NP concentrations (0.1 and 0.2 mg/L), with SFG reductions reaching 54% and 71%, respectively. Last, the highest concentrations tested significantly decreased the resistance of clams to exposure to air and enhanced the mortality rate. As the lowest effective NP concentrations are similar to environmentally realistic levels, a condition of potential risk for the well-being of clam populations in estuarine areas is highlighted

  20. A large metabolic carbon contribution to the δ 13C record in marine aragonitic bivalve shells

    Science.gov (United States)

    Gillikin, David P.; Lorrain, Anne; Meng, Li; Dehairs, Frank

    2007-06-01

    It is well known that the incorporation of isotopically light metabolic carbon (C M) significantly affects the stable carbon isotope (δ 13C) signal recorded in biogenic carbonates. This can obscure the record of δ 13C of seawater dissolved inorganic carbon (δ 13C DIC) potentially archived in the shell carbonate. To assess the C M contribution to Mercenaria mercenaria shells collected in North Carolina, USA, we sampled seawater δ 13C DIC, tissue, hemolymph and shell δ 13C. All shells showed an ontogenic decrease in shell δ 13C, with as much as a 4‰ decrease over the lifespan of the clam. There was no apparent ontogenic change in food source indicated by soft tissue δ 13C values, therefore a change in the respired δ 13C value cannot be the cause of this decrease. Hemolymph δ 13C, on the other hand, did exhibit a negative relationship with shell height indicating that respired CO 2 does influence the δ 13C value of internal fluids and that the amount of respired CO 2 is related to the size or age of the bivalve. The percent metabolic C incorporated into the shell (%C M) was significantly higher (up to 37%, with a range from 5% to 37%) than has been found in other bivalve shells, which usually contain less than 10%C M. Interestingly, the hemolymph did contain less than 10%C M, suggesting that complex fractionation might occur between hemolymph and calcifying fluids. Simple shell biometrics explained nearly 60% of the observed variability in %C M, however, this is not robust enough to predict %C M for fossil shells. Thus, the metabolic effect on shell δ 13C cannot easily be accounted for to allow reliable δ 13C DIC reconstructions. However, there does seem to be a common effect of size, as all sites had indistinguishable slopes between the %C M and shell height (+0.19% per mm of shell height).

  1. Clamming up: environmental forces diminish the perceptive ability of bivalve prey.

    Science.gov (United States)

    Smee, Delbert L; Weissburg, Marc J

    2006-06-01

    The lethal and nonlethal impacts of predators in marine systems are often mediated via reciprocal detection of waterborne chemical signals between consumers and prey. Local flow environments can enhance or impair the chemoreception ability of consumers, but the effect of hydrodynamics on detection of predation risk by prey has not been investigated. Using clams as our model organism, we investigated two specific questions: (1) Can clams decrease their mortality by responding to predators? (2) Do fluid forces affect the ability of clams to detect approaching predators? Previous research has documented a decrease in clam feeding (pumping) in response to a neighboring predator. We determined the benefits of this behavior to survivorship by placing clams in the field with knobbed whelk or blue crab predators caged nearby and compared mortality between these clams and clams near a cage-only control. Significantly more clams survived in areas containing a caged predator, suggesting that predator-induced alterations in feeding reduce clam mortality in the field. We ascertained the effect of fluid forces on clam perception of predators in a laboratory flume by comparing the feeding (pumping) behavior of clams in response to crabs and whelks in flows of 3 and 11 cm/s. Clams pumped significantly less in the presence of predators, but their reaction to blue crabs diminished in the higher velocity flow, while their response to whelks remained constant in both flows. Thus, clam reactive distance to blue crabs was affected by fluid forces, but hydrodynamic effects on clam perceptive distance was predator specific. After predators were removed, clams exposed to whelks took significantly longer to resume feeding than those exposed to blue crabs. Our results suggest that prey perception of predators can be altered by physical forces. Prey detection of predators is the underlying mechanism for trait-mediated indirect interactions (TMIIs), and recent research has documented the

  2. Environmental context and trophic trait plasticity in a key species, the tellinid clam Macoma balthica L

    DEFF Research Database (Denmark)

    Törnroos, Anna; Nordström, M. C.; Aarnio, K.;

    2015-01-01

    for understanding the role of individual species for ecosystem functioning. The tellinid clam Macoma balthica can vary its feeding behaviour, shifting between deposit- and suspension-feeding. In order to study the context-dependency of this trophic plasticity in adult clams, we conducted an experiment assessing......Species show varying levels of plasticity regarding morphology, physiology and behaviour in relation to their immediate environment, and several trait characteristics are habitat-dependent. Determining when and how the environmental context changes trait expression is of key importance...... showing differing isotopic signatures from clams at their original habitat, over time mirroring the changes in clams in the site to which they were transferred. The shift in carbon and nitrogen stable isotopes of the clams provides insights into the context-dependent intraspecific feeding plasticity...

  3. Assessment of clam ruditapes philippinarum as Heavy metal bioindicators using NMR-based metabolomics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaoli; Zhang, Linbao; You, Liping [Key Laboratory of Coastal Zone Environment Processes, CAS, Shandong Provincial Key Laboratory of Coastal Zone Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai (China); The Graduate School of Chinese Academy of Sciences, Beijing (China); Yu, Junbao; Cong, Ming; Wang, Qing; Li, Fei; Li, Lianzhen; Zhao, Jianmin; Li, Chenghua; Wu, Huifeng [Key Laboratory of Coastal Zone Environment Processes, CAS, Shandong Provincial Key Laboratory of Coastal Zone Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai (China)

    2011-08-15

    There are mainly distributed three pedigrees (White, Liangdao Red, and Zebra) of Manila clam Ruditapes philippinarum in Yantai population along the Bohai marine and coast. However, the biological differences to environmental stressors have been ignored in toxicology studies, which could lead to the distortion of biological interpretations of toxicological effects induced by environmental contaminants. In this study, we applied a system biology approach, metabolomics to compare the metabolic profiles in digestive gland from three pedigrees of clam and characterize and compare the metabolic responses induced by mercury in clam digestive gland tissues to determine a sensitive pedigree of clam as a preferable bioindicator for metal pollution monitoring and toxicology research. The most abundant metabolites, respectively, included branched-chain amino acids, alanine, and arginine in White samples, glutamate, dimethylglycine, and glycine in Zebra clams and acetylcholine, betaine, glucose, and glycogen in Liangdao Red clams. After 48 h exposure of 20 {mu}g L{sup -1} Hg{sup 2+}, the metabolic profiles from the three pedigrees of clams showed differentially significant changes in alanine, glutamate, succinate, taurine, hypotaurine, glycine, arginine, glucose, etc. Our findings indicate the toxicological effects of mercury exposure in Manila clams including the neurotoxicity, disturbances in energetic metabolisms and osmoregulation in the digestive glands and suggest that Liangdao Red pedigree of clam could be a preferable bioindicator for the metal pollution monitoring based on the more sensitive classes of metabolic changes from digestive glands compared with other two (White and Zebra) pedigrees of clams. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Infestation of the clam Chione fluctifraga by the burrowing worm Polydora sp. nov. in laboratory conditions.

    Science.gov (United States)

    Tinoco-Orta, Gissel Dalila; Cáceres-Martínez, Jorge

    2003-07-01

    Burrowing worms that belong to Polydora spp. infest marine mollusks cultured worldwide, causing problems for production and marketing. The clam Chione fluctifraga is semi-cultured in Bahía Falsa, Baja California, NW Mexico, and some clams harbor burrowing worms. The present study was carried out to determine the identity of the worm species infesting the clam, the infesting process by cohabitation of infested and non-infested clams in aquaria with a variety of substrates (fine sand, gross sand, plastic bag used for clam culture, and aquarium without substrate) and turbulence conditions, and the occurrence of architomy phenomena in connection with infestation of the clam. The burrowing worm was considered as a nova species due to its singular limbate neurosetae and notosetae in the setiger 5, hooks in the setiger 6, eyes not present, and general pigmentation, among other characteristics. Infestation was similar in all substrates and turbulence conditions, but it was more abundant on clams previously infested than on those free of worms, showing a preferential settlement of worm infesting stages on pre-infested clams. Regeneration was observed in all segments of the worm: anterior (metastomium), medium, and posterior (prostomium); the complete regeneration time occurred in 40 days. This is the first record of architomy in a species of Polydora and this phenomenon could account for the increase of infestation intensity in pre-infested clams at the end of the study period. Infestation of clams by settling polichaete in the conditions studied, and the architomy process in this worm species, shows its great infesting capacity. PMID:12877826

  5. Bioaccumulation of gasoline in brackish green algae and popular clams

    Directory of Open Access Journals (Sweden)

    Gihan A. El-Shoubaky

    2016-03-01

    Full Text Available The green algae (Ulva lactuca and Enteromorpha clathrata and the clams (Tapes decussates and Venerupis aurea grow together in Timsah Lake, Suez Canal, Egypt. Our ultimate goal is to validate the bioaccumulation of gasoline in the marine organisms and their behavior after exposure to the pollutant, experimentally. These species were treated with a serial treatment of gasoline (1000, 4000, 16,000 and 64,000 μl in aquaria with brackish sea-water for 72 h. The tested green algae and clams were taken for an analysis of total hydrocarbon accumulation daily. The statistical analysis showed significant differences between the four species and also between the duration of exposure. The accumulation of gasoline in U. lactuca and E. clathrata reached their maximum after 48 h at 1000 and 4000 μl. The highest absorption was registered after 24 h only at 16,000 and at 64,000 μl. U. lactuca recorded complete mortality in 64,000 μl at 72 h whereas E. clathrata registered death at 48 h and 72 h in the same treatment. V. aurea was more sensitive than T. decussates. The accumulation of gasoline reached its maximum in V. aurea after only 24 h in the first treatment while it retarded to 48 h in T. decussates with a lesser accumulation. However, both clam species accumulated the highest amount of petroleum hydrocarbons during the first hour of exposure at the first treatment. In the third and fourth treatments, clams did not accumulate gasoline but began to dispose it from their tissues till it became less than that in the control. Mortality gradually increased with time in each treatment except the last one (64,000 μl in which 100% death of the specimens was observed. In general, the bioaccumulation of gasoline level was in a descending order as follows: U. lactuca > E. clathrata > V. aurea > T. decussates. Their behavior changed from accumulation to detoxification with time and with the increase in pollutant concentration. Generally, these

  6. PCDD/F and dioxin-like PCB bioaccumulation by Manila clam from polluted areas of Venice lagoon (Italy)

    International Nuclear Information System (INIS)

    POP bioaccumulation pathways in the clam Tapes philippinarum were examined for two years from juveniles to adult size. Two polluted sites, one with sandy sediment, the other muddy were compared with a reference site characterized by low contamination levels. Juvenile clams coming from a hatchery were reared both on the sediment and in nets suspended at 30 cm from the bottom. POP changes in clam tissue were related to the concentrations recorded in sediments and in the particulate matter during the entire fattening period. Results provided interesting data on the relationships between environmental contamination and bioaccumulation. Contrary to studies on the decontamination times of the clams collected in polluted areas, this work investigates the preferential clam bioaccumulation pathways during growth under different environmental conditions. In general POP bioaccumulation resulted to be correlated to concentrations in SPM rather than in sediments and was higher in S-clams rather than in B-clams. -- Highlights: • PCDD/Fs and dioxin-like PCB accumulation in clam tissues during growth. • Muddy and sandy polluted areas. • How sediment and suspended matter contamination affect clam toxicity. • Clam toxicity and law limits. -- Clam bioaccumulation pathways in polluted areas

  7. Predicting coexistence and predominance patterns between the introduced Manila clam (Ruditapes philippinarum) and the European native clam (Ruditapes decussatus)

    Science.gov (United States)

    Bidegain, Gorka; Bárcena, Javier Francisco; García, Andrés; Juanes, José Antonio

    2015-01-01

    In several European estuaries, the introduced Manila clam (Ruditapes philippinarum) has become a widespread and predominating species supplanting the native carpet shell clam (Ruditapes decussatus) whereas in other estuaries such as the Bay of Santander (Gulf of Biscay) this pattern has not been detected. Using this estuary as a case study, the potential coexistence/predominance patterns between these two species were explored with the objective of providing insight into the capacity of expansion of R. philippinarum. Firstly, the Ecological Niche Factor Analysis (ENFA) was applied to determine the niches of both species, using seven contemporary environmental variables, i.e. salinity, water depth, current velocity, and sediment sand, gravel, silt and organic matter content. Secondly, ENFA-derived habitat-suitability (HS) maps were simultaneously treated, using geospatial techniques and following HS index-based criteria, to determine the potential distribution patterns. Both species models performed well according to the cross-validation evaluation method. The environmental variables that most determined the presence of both clams were depth, current velocity and salinity. ENFA factors showed that R. philippinarum habitat differs more from the mean environmental conditions over the estuary (i.e. higher marginality) and has less narrow requirements (i.e. lower specialization). R. philippinarum dominated areas, determined by relatively lower current velocities and percentages of sand, higher organic matter contents and slightly shallower depths, were very reduced (i.e. 2.0% of the bay surface) compared to coexistence (47%) and R. decussatus predominance areas (7.4%). These results suggest that HS may regulate the expansion of R. philippinarum. ENFA, together with geospatial analysis of HS index, seems to be a valuable approach to explore the expansion potential of estuarine invasive or introduced species and thus support conservation decisions regarding native species.

  8. Mechanical properties and microstructure evolution of CLAM Steel in tube fabrication and test blanket module assembly

    International Nuclear Information System (INIS)

    The first wall of the China dual functional lithium lead–test blanket module (DFLL–TBM) will be assembled with China low activation martensitic (CLAM) steel rectangular tubes and plates by hot isostatic pressing (HIP) – diffusion welding. The objective of this study is to evaluate CLAM rectangular tubes and investigate mechanical property and microstructure evolution of CLAM steel in tube fabrication and TBM assembly. In this work, CLAM rectangular tubes with lengths of 1500 mm were fabricated, and the dimensional accuracy met the requirement for HIP joining. In the tube fabrication process, the CLAM steel was annealed to improve its ductility. In addition, the anisotropy in mechanical properties and microstructure introduced by tube rolling was eliminated according to the simulation of HIP heat treatment in TBM preparation. The tensile strength of the CLAM tubes with final heat treatment was slightly higher than that of CLAM steel with the published standard heat treatment, while the total elongation was reduced. This revealed that a post-HIP heat treatment was required before the final heat treatment

  9. The antioxidant potential of the New Zealand surf clams.

    Science.gov (United States)

    Odeleye, Tinu; Li, Yan; White, William Lindsey; Nie, Shaoping; Chen, Shuping; Wang, Junqiao; Lu, Jun

    2016-08-01

    The antioxidant action of three New Zealand surf clams was evaluated for the first time. Aqueous (cd) and ethanolic extracts from Diamond shell - Crassula aequilatera, Storm shell - Mactra murchisoni, and Tua tua - Paphies donacina were studied for their antioxidant potentials using two in vitro assays. The ethanolic extracts were further fractioned into four parts; petroleum ether (pe), ethyl acetate (ea), n-butanol (nb), and the final aqueous fraction (w). Comparing among all fractions tested, the ea fraction of P. donacina showed the strongest free radical scavenging power, with a radical scavenging activity of 76.14% at 20μg/mL. The ea fraction of C. aequilatera had the highest copper reducing activity with an absorbance of 1.596 at 20μg/mL. Results from this study suggest that some bioactive compounds with significant antioxidant effects may exist in the New Zealand surf clams, and could potentially reduce oxidative stress to deliver health benefits or to produce functional foods. PMID:26988487

  10. Addressing Sustainability of Clam Farming in the Venice Lagoon

    Directory of Open Access Journals (Sweden)

    Lara Pizzo

    2011-09-01

    Full Text Available The clam fishing and aquaculture system in the Venice Lagoon still appears insufficiently resilient to buffer external and internal perturbations, such as productivity fluctuations, unregulated fishing, and market related dynamics, despite the efforts of regional and local authorities to achieve the sustainable development. According to the System Approach Framework (SAF, based on previous studies and stakeholder interactions, we developed a model integrating ecological, social, and economic (ESE aspects. We chose the aspects necessary to represent the essential dynamics of major ecological, social, and economic clam farming system components to project the consequences of implementing alternative management policies and to address the ecological and social carrying capacity. Results of the simulations suggest that a properly managed farming system can sustain an acceptable income and support the local community, while reducing negative environmental impacts, social conflicts, and consumer health risks and improving system resilience. The results highlight the importance of an interdisciplinary, participatory, and adaptive approach in planning the management of this important renewable resource.

  11. Recolonization of reactor cooling water system by the Asiatic clam Corbicula fluminea

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, R.S.

    1978-01-01

    Recolonization rates for the Asiatic clam Corbicula fluminea ranged from 3.0 to 5.6 metric tons per year in cooling water basins for a nuclear production reactor at the Savannah River Plant. However, a 10-month cleaning cycle for each basin (flow area, 6100 m/sup 2/) keeps the depth of the silt/clam layer low. With this cleaning frequency, Corbicula are not reaching heat exchangers at sufficient size or in sufficient numbers to restrict flow. Data are presented on the size/age distribution for clams recolonizing cooling water basins between cleanings.

  12. Assessment of immune parameters of manila clam Ruditapes philippinarum in different physiological conditions using flow cytometry

    Science.gov (United States)

    Park, Kyung-Il; Donaghy, Ludovic; Kang, Hyun-Sil; Hong, Hyun-Ki; Kim, Young-Ok; Choi, Kwang-Sik

    2012-03-01

    Cellular and humoral immune parameters are often used as biomarkers to trace environmental and physiological stresses in marine bivalves. In this study, we compared various immune parameters of Manila clams ( Ruditapes philippinarum) under normal conditions and under a high level of desiccation, using flow cytometry. The immune parameters analyzed included, total hemocyte count, hemocyte mortality, hemocyte DNA damage, reactive oxygen species (ROS) production, and phagocytosis activity. Total hemocyte count, hemocyte DNA damage, and hemocyte mortality were significantly elevated among clams under high desiccation stress, while phagocytosis activity and spontaneous ROS production were significantly lower compared to those parameters of the control clams ( pclams.

  13. Field and laboratory transmission studies of haemic neoplasia in the soft-shell clam, Mya arenaria, from Atlantic Canada.

    Science.gov (United States)

    Mateo, D R; MacCallum, G S; Davidson, J

    2016-08-01

    A two-year laboratory and field study was initiated in 2001 in response to mass mortalities associated with haemic neoplasia (HN) in 1999 in Prince Edward Island (PEI) soft-shell clams, Mya arenaria. A laboratory proximity experiment (cohabitation) and an inoculation challenge were conducted with clams and mussels (Mytilus edulis). Three field exposure experiments were also conducted, in which naive clams were held in sediment (in trays) or out of sediment (in mesh bags) at three high HN prevalence sites on PEI. There was a conversion to HN positive in clams in the proximity experiment and in clams injected with whole blood and cell-free homogenate, but not at statistically significant levels. No mussels or control clams became HN positive. There was a significant conversion to HN positive in as little as 24 and 58 days after transfer with clams held out of sediment and in sediment, respectively. The laboratory and field experiments' results suggest that HN-infected clams are spreading the disease through water from infected clams to naïve individuals and via transplantation from affected to unaffected sites. Some environmental conditions (e.g. abnormally high water temperature and hypoxia-induced sea lettuce [Ulva lacteus] invasion) may make clams susceptible to infections or exacerbate the proliferation of HN. PMID:26687447

  14. Geographic distribution of mercury in asiatic clams, Corbicuia plumihea, from the North Fork Holston River, Virginia

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — A study was conducted quantifying mercury concentrations in the Asiatic clam, Corbicula fluminea, from the North Fork Holston River, Virginia. The purpose of this...

  15. Contaminant assessment of fish, rangia clams, and sediments in the Lower Pamlico River, North Carolina

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Samples of sediment, rangia clams Rangia cuneata, gizzard shad Dorosoma cepedianum, and longnose gar Lepisosteus osseus were collected from five sites in the lower...

  16. Population Dynamics of the Giant Clam, Tridacna maxima, at Rose Atoll

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — There is a paucity of knowledge on the population dynamics of the giant clams of the family Tridacnidae. Such information on population dynamics is necessary for...

  17. A theoretical individual-based model of Brown Ring Disease in Manila clams, Venerupis philippinarum

    Science.gov (United States)

    Paillard, Christine; Jean, Fred; Ford, Susan E.; Powell, Eric N.; Klinck, John M.; Hofmann, Eileen E.; Flye-Sainte-Marie, Jonathan

    2014-08-01

    An individual-based mathematical model was developed to investigate the biological and environmental interactions that influence the prevalence and intensity of Brown Ring Disease (BRD), a disease, caused by the bacterial pathogen, Vibrio tapetis, in the Manila clam (Venerupis (= Tapes, = Ruditapes) philippinarum). V. tapetis acts as an external microparasite, adhering at the surface of the mantle edge and its secretion, the periostracal lamina, causing the symptomatic brown deposit. Brown Ring Disease is atypical in that it leaves a shell scar that provides a unique tool for diagnosis of either live or dead clams. The model was formulated using laboratory and field measurements of BRD development in Manila clams, physiological responses of the clam to the pathogen, and the physiology of V. tapetis, as well as theoretical understanding of bacterial disease progression in marine shellfish. The simulation results obtained for an individual Manila clam were expanded to cohorts and populations using a probability distribution that prescribed a range of variability for parameters in a three dimensional framework; assimilation rate, clam hemocyte activity rate (the number of bacteria ingested per hemocyte per day), and clam calcification rate (a measure of the ability to recover by covering over the symptomatic brown ring deposit), which sensitivity studies indicated to be processes important in determining BRD prevalence and intensity. This approach allows concurrent simulation of individuals with a variety of different physiological capabilities (phenotypes) and hence by implication differing genotypic composition. Different combinations of the three variables provide robust estimates for the fate of individuals with particular characteristics in a population that consists of mixtures of all possible combinations. The BRD model was implemented using environmental observations from sites in Brittany, France, where Manila clams routinely exhibit BRD signs. The simulated

  18. Welding techniques development of CLAM steel for Test Blanket Module

    International Nuclear Information System (INIS)

    Fabrication techniques for Test Blanket Module (TBM) with CLAM are being under development. Effect of surface preparation on the HIP diffusion bonding joints was studied and good joints with Charpy impact absorbed energy close to that of base metal have been obtained. The mechanical properties test showed that effect of HIP process on the mechanical properties of base metal was little. Uniaxial diffusion bonding experiments were carried out to study the effect of temperature on microstructure and mechanical properties. And preliminary experiments on Electron Beam Welding (EBW), Tungsten Inert Gas (TIG) Welding and Laser Beam Welding (LBW) were performed to find proper welding techniques to assemble the TBM. In addition, the thermal processes assessed with a Gleeble thermal-mechanical machine were carried out as well to assist the fusion welding research.

  19. Early development, survival and growth rates of the giant clam Tridacna crocea (Bivalvia: Tridacnidae)

    OpenAIRE

    Miguel Mies; Felipe Braga; Marcello Santos Scozzafave; Daniel Eduardo Lavanholi de Lemos; Paulo Yukio Gomes Sumida

    2012-01-01

    Tridacnid clams are conspicuous inhabitants of Indo-Pacific coral reefs and are traded and cultivated for the aquarium and food industries. In the present study, daily growth rates of larvae of the giant clam Tridacna crocea were determined in the laboratory during the first week of life. Adults were induced to spawn via intra-gonadal serotonin injection through the byssal orifice. After spawning oocytes were collected, fertilized and kept in 3 L glass beakers and raceways treated with antibi...

  20. Protective role of edible clam Paphia malabarica (Chemnitz) against lipid peroxidation and free radicals

    Digital Repository Service at National Institute of Oceanography (India)

    Pawar, R.T.; Nagvenkar, S.S.; Jagtap, T.G.

    Introduction Clams, mussels, and oysters are dominant components of bivalve fishery [1] and forms important source of nutrition in coastal states [2, 3]. Paphia malabarica (Chemnitz) (a clam), is a commonly consumed as seafood in its cooked form.... malabarica has great market demand in Japan and other European countries. Moreover, this species has high nutritional value and percentage edibility [5] yet they are to be explored for its nutritional and antioxidative properties. In a living organism...

  1. Ionic and Amino Acid Regulation in Hard Clam (Meretrix lusoria) in Response to Salinity Challenges.

    Science.gov (United States)

    Lin, Chia-Hao; Yeh, Po-Ling; Lee, Tsung-Han

    2016-01-01

    Most marine mollusks are osmoconformers, in that, their body fluid osmolality changes in the direction of the change in environmental salinity. Marine mollusks exhibit a number of osmoregulatory mechanisms to cope with either hypo- or hyperosmotic stress. The effects of changes in salinity on the osmoregulatory mechanisms of the hard clam (Meretrix lusoria, an economically important species of marine bivalve for Taiwan) have not been determined. In this study, we examined the effect of exposure to hypo (10‰)- and hyper (35‰)-osmotic salinity on hard clams raised at their natural salinity (20‰). The osmolality, [Na(+)], and [Cl(-)] of the hard clam hemolymph were changed in the same direction as the surrounding salinity. Further, the contents of total free amino acids including taurine in the gills and mantles were significantly upregulated in hard clam with increasing salinity. The gill Na(+), K(+)-ATPase (NKA) activity, the important enzyme regulating cellular inorganic ions, was not affected by the changed salinity. Mantle NKA activity, however, was stimulated in the 35‰ SW treatment. The taurine transporter (TAUT) is related to the regulation of intracellular contents of taurine, the dominant osmolyte. Herein, a TAUT gene of hard clam was cloned and a TAUT antibody was derived for the immunoblotting. The TAUT mRNA expression of the mantle in hard clam was significantly stimulated in 35‰ SW, but protein expression was not modulated by the changed salinity. In gills of the hard clam with 10‰ SW, both TAUT mRNA and protein expressions were significantly stimulated, and it may reflect a feedback regulation from the decreased gills taurine content under long-term hypoosmotic acclimation. These findings suggest that TAUT expression is regulated differently in gills and mantles following exposure to alterations in environmental salinity. Taken together, this study used the physiological, biochemical and molecular approaches to simultaneously explore the

  2. Immune- and Pollution-mediated DNA Damage in Two Wild Mya arenaria Clam Populations

    OpenAIRE

    François Gagné; M. Laura Martín-Díaz; Christian Blaise

    2009-01-01

    In aquatic environments, genotoxicity results from the effects of pollution combined with the inflammatory response triggered by the immune system. Indeed, the production of nitrosylated DNA and proteins are though to arise from the production of peroxinitrite during phagocytosis and inflammation. The purpose of this study was to examine new DNA biomarkers that differentiate between immune- and pollution-mediated genotoxicity in wild clam populations. Intertidal clam populations were sampled ...

  3. Growth performance of the clam, Meretrix meretrix, breeding-selection populations cultured in different conditions

    Institute of Scientific and Technical Information of China (English)

    WANG Chao; CHAI Xueliang; WANG Hongxia; TANG Baojun; LIU Baozhong

    2013-01-01

    A breeding-selection program for the clam, Meretrix meretrix, was conducted since 2004. Two of the selec-tion populations were generated with the shell color pattern as an additional selection criterion and named as SP (purple stripes) population and SB (black dots) population. The third-generation SP and SB popula-tions (08G3SP and 08G3SB, respectively) were cultured at two commercial clam farms and a nursery pond and their shell lengths were compared. 08G3SB clams had significantly larger sizes than 08G3SP clams at commercial clam farms (p<0.05), yet 08G3SB individuals were significantly smaller than 08G3SP individ-uals at the nursery pond (p <0.05). Then, we examined the growth of the fourth-generation SP and SB populations (10G4SP and 10G4SB, respectively) at a commercial farm, and found that the shell lengths of the 10G4SB clams increased at a significantly higher growth rate than the 10G4SP clams (p <0.05) from May to September, when the water temperature was between 24.2-27.5◦C, while 10G4SB lost the growth advantage in the other months. These results indicated that SP and SB populations responded differently to environmental factors, so it is beneficial for the clam farmers to select a suitable population according to the culture environment. Furthermore, a diallel mating of the SB and SP populations was designed to investigate whether their hybrid population would show heterosis. However, the heterosis was not shown in this study, which might result from the slight genetic divergence between SB and SP populations.

  4. Growth estimats of the Argentinean surf clam Donax hanleyanus (Bivalvia: Donacidae) derived from fluorescent marking

    OpenAIRE

    Herrmann, Marko; Laudien, Jürgen; Arntz, Wolf; Penchaszadeh, P. E.

    2007-01-01

    RESUMENMicro-growth increments of the Argentinean surf clam Donax hanleyanus were measured at the exposed sandy beach Mar Azul. After marking the shells with the fluorescence marker Calcein, animals were allowed to grow in situ for 36 days. The majority of the marked specimens showed a distinct fluorescent band reflecting the calcein staining time and allowing for growth estimates.Palabras llaves: growth rate, fluorescent marking, Calcein, surf clam, Donax hanleyanusINTRODUCCIÓNGrowth rate is...

  5. Detection of hepatitis A virus genotype IB variants in clams from Maputo Bay, Mozambique.

    Science.gov (United States)

    Nenonen, Nancy P; Hernroth, Bodil; Chauque, Arlindo A; Hannoun, Charles; Bergström, Tomas

    2006-07-01

    Clams provide an important source of food and income for the population of Maputo, Mozambique, where conditions of poor water supply and inadequate sanitation favor endemic infection with hepatitis A virus (HAV). To determine the role of bivalves in an endemic area, clams gathered from Maputo Bay were bought from market and examined for HAV. Four batches, total 150 clams, were sampled over the year. RNA extracted from individual digestive glands was assayed by nested RT-PCR and sequencing of HAV 5' noncoding region (5' NCR). Specific HAV signals were detected in one batch, 23 of 34 clams (67%) testing positive. Phylogenetic analyses of VP3/VP1, VP1/P2A, and 5' NCR determined clustering of clam strains as genotype I, subtype B. In addition to identifying HAV IB strains with predicted conserved amino acid sequence, IB variants exhibiting novel amino acid substitutions at the VP1/P2A junction were detected. HAV strains from clams showed 93%-99% homology with wild-type IB strains from South African outbreaks and from a panel of HAV IgM positive Swedish patients. DNA from enteric human adenovirus 40/41 was found in a limited number of clams from two batches, 6/34 (17%) and 4/35 (11%). Detection of HAV subgenotype IB in bivalves provided indirect evidence of the strains circulating in a densely populated coastal region where HAV is presumed to be hyperendemic. The results suggest that clams may be an important source of HAV in Maputo region, and indicate the need for further molecular study of strains circulating in the indigenous population. PMID:16721847

  6. Influence of non-metal inclusions on mechanical properties of Clam steel

    International Nuclear Information System (INIS)

    Full text of publication follows: With good irradiation swelling resistance, thermo-physical and thermo-mechanical properties, the RAFMs (Reduced Activation Ferritic / Martensitic steels) have been considered as the primary candidate structural materials for application in fusion systems in the near future. The China Low Activation Martensitic steel (CLAM) based on the nominal compositions of 9Cr1.5WVTa is being developed in Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) under wide collaboration with many other institutes and universities in domestic and overseas. The heat treatment of CLAM is quenching at 980 deg. C for 30 minutes and then cooled by air or water and tempering at 760 deg. C for 90 minutes and then cooled by air. Mechanical properties of CLAM were strongly affected by the size and distribution of non-metal inclusions as most steels, and its effects on mechanical properties of CLAM steel has been investigated. The evaluation of the non-metallic inclusions in CLAM has been done by optical microscopy observation, electron microscopy observation and Energy Dispersive X-ray Spectroscopy (EDS) analysis. The results showed that most of the non-metal inclusions in CLAM were brittle alumina phase with large size and non-uniform distribution and those were no good to the mechanical properties of CLAM. So electroslag remelting process was chosen to remelt the ingot which was smelted previously by vacuum induction furnace. Inclusion detection by optical microscopy showed that both of the dimensions and quantity of the inclusions decreased and their distributions became more uniform compared with the case before. And the tensile tests and Charpy V-notch impact tests indicated that electroslag remelting improved the tensile properties and impact toughness of CLAM steel. (authors)

  7. Dimethylsulfoniopropionate in six species of giant clams and the evolution of dimethylsulfide after death

    Energy Technology Data Exchange (ETDEWEB)

    Hill, R.W.; Hill, S.D. [Michigan State Univ., East Lansing, MI (United States). Dept. of Zoology; Dacey, J.W.H. [Woods Hole Oceanographic Inst., Woods Hole, MA (United States). Dept. of Biology; Edward, A. [Micronesia College, Pohnpei (Micronesia, Federated States); Hicks, W.A. [Michigan State Univ., East Lansing, MI (United States). Dept. of Bioichemistry and Molecular Biology

    2004-05-01

    Dimethylsulfoniopropionate (DMSP) could accumulate in large concentrations in animals living symbiotically with algae. The giant clam family Tridacnidae accumulates DMSP because they have a symbiotic relationship with dinoflagellates (or zooxanthellae). In this study, well preserved clam tissues from the western Pacific Islands were analyzed to provide definitive evidence of DMSP in the tissues. Six of the common species in the Tridacnidae family were examined. The objective was to test the hypothesis that dimethyl sulfide (DMS) is released from clam tissues soon after death due to the breakdown of DMSP tissue. In particular, it determined if DMS is responsible for the problem of potent odours and off-taste that have hindered the commercial success of giant clams mariculture. Gas chromatography and mass spectrometry was used in this study to measure DMSP concentrations in siphonal mantle, byssal mantle, adductor muscle and gill tissues. The formation of DMS by tissues after death was documented. It was suggested that since giant clams associate with dinoflagellates, they could accumulate DMSP to high concentrations which could affect multiple properties and functions. It was concluded that the perishability of giant clam tissues is most likely due to the high concentrations of DMS produced one day post mortem. 15 refs., 2 tabs., 4 figs.

  8. A radiotracer study on the chronic effects and subcellular partitioning of metals in the Manila clam Ruditapes Philippinarum

    International Nuclear Information System (INIS)

    A laboratory microcosm study was employed to evaluate chronic physiological and histopathological effects of wate-rborne Ag to the Manila clam Ruditapes philippinarum. Additionally, radiotracers of gamma emitting isotopes of 109Cd, 51Cr, and 65Zn were used to study the metal bioaccumulation mechanisms and subcellular partitioning in the clam Ruditapes philippinarum. Bioaccumulation of Ag in the clam increased linearly with Ag concentration in seawater and exposure time. All the physiological parameters (e.g., filtration rate, scope for growth) and histopathological data had negative relationships with tissue Agconcentrations in the clams. The uptake rate of 3 metals increased in the order of Zn > Cd > Cr and had inverse relationship with salinity and with individual clam size (dry weight). The result suggest that subcellular partitioning of metals in the clams into different binding pools could be important factors determining Biologically Detoxified Metal (BDM), Trophically Available Metal (TAM) and Trophically Available Metal (TAM)

  9. Empirical Analysis of the Typical Breeding Pattern of Clam in Hongdao Town and the Preliminary Estimates of Costs and Benefits

    OpenAIRE

    YANG, Xijuan; Zhang, Shijun

    2014-01-01

    Based on the survey data about clam breeding farmers in Hongdao Town in August 2011, this paper analyzes the production and operation of typical clam breeding pattern, and estimates the costs and benefits. Through the analysis of operation conditions and economic conditions of Hongdao clam breeding, this paper aims to explore a more reasonable and effective breeding pattern so as to reduce breeding costs and market risks, and increase breeding farmers' income.

  10. Empirical Analysis of the Typical Breeding Pattern of Clam in Hongdao Town and the Preliminary Estimates of Costs and Benefits

    Institute of Scientific and Technical Information of China (English)

    Xijuan; YANG; Shijun; ZHANG

    2014-01-01

    Based on the survey data about clam breeding farmers in Hongdao Town in August 2011,this paper analyzes the production and operation of typical clam breeding pattern,and estimates the costs and benefits. Through the analysis of operation conditions and economic conditions of Hongdao clam breeding,this paper aims to explore a more reasonable and effective breeding pattern so as to reduce breeding costs and market risks,and increase breeding farmers’ income.

  11. Temperature- and parasite-induced changes in toxicity and lethal body burdens of pentachlorophenol in the freshwater clam Pisidium amnicum.

    Science.gov (United States)

    Heinonen, J; Kukkonen, J V; Holopainen, I J

    2001-12-01

    Seasonal variation in abiotic and biotic environments may modify the toxicity of organic chemicals for aquatic organisms. In present study, survival of the freshwater clam Pisidium amnicum was studied in laboratory exposures to pentachlorophenol (PCP) in April (at 5 degress C) and July (at 19 degress C). Behavioral responses, mean survival times (MSTs), and the lethal body burdens (LBBs) of PCP for uninfected clams and for clams infected by digenean trematodes were determined separately in two PCP concentrations, 100 and 300 microgram/L. Analysis of data revealed reduced behavioral activity of the clams in the PCP exposure compared to that in the control. The time needed for toxic responses was greatly affected by temperature; MSTs were 5 to 15 times longer in winter than at summer temperatures. Unexpectedly, the infected clams in summer were more tolerant to PCP than the uninfected clams. Despite the differences in survival times, the LBBs between the seasons were constant. However, in summer, the infected clams had significantly higher LBBs than the uninfected clams. The differences in survival and LBBs between the infected and uninfected clams are suggested to be caused by the high lipid contents found in parasites, which may change the internal distribution of PCP. PMID:11764161

  12. A spatially resolved model of seasonal variations in phytoplankton and clam ( Tapes philippinarum) biomass in Barbamarco Lagoon, Italy

    Science.gov (United States)

    Spillman, C. M.; Hamilton, D. P.; Hipsey, M. R.; Imberger, J.

    2008-08-01

    Barbamarco Lagoon (area = 7 km 2) is in the Po River Delta, adjoining the Northern Adriatic Sea, and supports a commercially valuable clam ( Tapes philippinarum) fishery. This study investigated interactions of the lagoon with adjacent coastal waters and inland riverine inputs by modelling both the lagoon and the Northern Adriatic Sea, using a coupled three-dimensional (3D) hydrodynamic-ecological model (ELCOM-CAEDYM) adapted to include the clam population. The clam model accounted for carbon (C), nitrogen (N) and phosphorus (P) biomass in the benthos through parameterisations for filtration, excretion, egestion, respiration, mortality, and harvesting. Multiple clam size classes were included in a new population dynamics sub-model. Output from the coupled model was validated against hydrodynamic and water quality data from intensive field sampling and routine monitoring. Time scales of tidal flushing, primary production and clam grazing were investigated with the model to demonstrate that food supply to clam populations is dominated by phytoplankton inputs from the Northern Adriatic Sea. Effects of clam cultivation on nutrient concentrations and phytoplankton biomass in Barbamarco Lagoon were primarily localised, with strong tidal flushing minimising impacts of clam filtration on lagoon-wide nutrient concentrations at current clam stocking levels. Clam populations were found to alter the cycling of nutrients in the system, causing the lagoon to become a net sink for particulate organic matter and to export dissolved organic matter to the adjacent sea via tidal flushing. Ecosystem health and sensitivity of nutrient cycles to clam cultivation are important considerations for the long term sustainable management and potential expansion of the fishery.

  13. Transcriptomic responses to low temperature stress in the Manila clam, Ruditapes philippinarum.

    Science.gov (United States)

    Nie, Hongtao; Jiang, Liwen; Huo, Zhongming; Liu, Lianhui; Yang, Feng; Yan, Xiwu

    2016-08-01

    The Manila clam, Ruditapes philippinarum, is an economically important shellfish in marine aquaculture, with a broad thermal tolerance. The ability to cope with cold stress is quite important for the survival of aquatic species under natural conditions. A cold-tolerant clam that can survive the winter at temperatures below 0 °C might extend our understanding of the mechanisms underlying the response to cold stress. In this study, the transcriptional response of the Manila clam to cold stress (-1 °C) was characterized using RNA sequencing. The transcriptomes of a cold-treatment (O) group of clams, which survived under cold stress, and the control group (OC2), which was not subjected to cold stress, were sequenced with the Illumina HiSeq platform. In all, 148,593 unigenes were generated. Compared with the unigene expression profile of the control group, 1760 unigenes were up regulated and 2147 unigenes were down regulated in the O group. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that signal transduction, mitochondrial metabolism, cellular component organization or biogenesis, and energy production processes were the most highly enriched pathways among the genes that were differentially expressed under cold stress. All these pathways could be assigned to the following biological functions in the cold-tolerant Manila clam: signal response to cold stress, antioxidant response, cell proliferation, and energy production. PMID:27288255

  14. Infection by gymnophallid metacercariae enhances predation mortality of SW Atlantic stout razor clam Tagelus plebeius

    Science.gov (United States)

    Addino, Mariana; Lomovasky, Betina J.; Cremonte, Florencia; Iribarne, Oscar

    2010-02-01

    Parasite life cycles are frequently completed in different hosts, thus the parasites have its life cycle overlapped to natural trophic webs. The family Gymnophallidae (Class: Trematoda; Subclass: Digenea) includes digenetic parasites whose larval stages occur on bivalves and may affect bivalve predation by the final host of these parasites. In this work we evaluated: (a) if individuals of the razor clam Tagelus plebeius with higher parasite intensity suffer higher predation by the oystercatcher Haematopus palliatus and, (b) if there is any effect of parasite intensity on burrowing and escape behaviours of these razor clams which may enhance exposure to predators. Field experiments (oystercatcher exclusion vs. open access) showed that clams with higher parasite intensity support higher predation by oystercatchers, which suggests a higher consumption of more parasitized clams and thus, a more successful reproduction of parasites linked to the intensity of infection. However, clam burrowing and escape behaviours did not show differences related to different parasite intensity, suggesting that the commonly believed mechanisms are not responsible in this case.

  15. Assessment of thermo-mechanical behavior in CLAM steel first wall structures

    Energy Technology Data Exchange (ETDEWEB)

    Liu Fubin, E-mail: liufubin_1216@126.com [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, Liaoning (China); Yao Man, E-mail: yaoman@dlut.edu.cn [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, Liaoning (China)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer China Low Activation Martensitic steel (CLAM) as FW the structural material. Black-Right-Pointing-Pointer The thermo-mechanical behavior of the FW was analyzed under the condition of normal ITER operation combined effect of plasma heat flux and neutron heating. Black-Right-Pointing-Pointer The temperature dependence of the material physical properties of CLAM is summarized. - Abstract: The temperature and strain distributions of the mockup with distinct structural material (SS316L or China Low Activation Martensitic steel (CLAM)) in two-dimensional model were calculated and analyzed, based on a high heat flux (HHF) test recently reported with heat flux of 3.2 MW/m{sup 2}. The calculated temperature and strain results in the first wall (FW), in which SS316L is as the structural material, showed good agreement with HHF test. By substituting CLAM steel for SS316L the contrast analysis indicates that the thermo-mechanical property for CLAM steel is better than that of SS316 at the same condition. Furthermore, the thermo-mechanical behavior of the FW was analyzed under the condition of normal ITER operation combined effect of plasma heat flux and neutron heating.

  16. Impediment to symbiosis establishment between giant clams and Symbiodinium algae due to sterilization of seawater.

    Directory of Open Access Journals (Sweden)

    Takeo Kurihara

    Full Text Available To survive the juvenile stage, giant clam juveniles need to establish a symbiotic relationship with the microalgae Symbiodinium occurring in the environment. The percentage of giant clam juveniles succeeding in symbiosis establishment ("symbiosis rate" is often low, which is problematic for seed producers. We investigated how and why symbiosis rates vary, depending on whether giant clam seeds are continuously reared in UV treated or non treated seawater. Results repeatedly demonstrated that symbiosis rates were lower for UV treated seawater than for non treated seawater. Symbiosis rates were also lower for autoclaved seawater and 0.2-µm filtered seawater than for non treated seawater. The decreased symbiosis rates in various sterilized seawater suggest the possibility that some factors helping symbiosis establishment in natural seawater are weakened owing to sterilization. The possible factors include vitality of giant clam seeds, since additional experiments revealed that survival rates of seeds reared alone without Symbiodinium were lower in sterilized seawater than in non treated seawater. In conclusion, UV treatment of seawater was found to lead to decreased symbiosis rates, which is due possibly to some adverse effects common to the various sterilization techniques and relates to the vitality of the giant clam seeds.

  17. Change in metallothionein phosphorylation state in Mya arenaria clams: implication in metal metabolism and oxidative stress

    Directory of Open Access Journals (Sweden)

    F Gagné

    2010-01-01

    Full Text Available The contamination of the benthic environment poses a threat to long-lived sessile organisms such as clams. The purpose of this study was to investigate metal contamination in tissues and changes in metallothioneins (MT in respect to its redox status in Mya arenaria clams collected at three polluted sites. The phosphorylation state of MT was also investigated to determine whether this state is changed in clams collected at heavy-metal contaminated site and its involvement in cytoprotective signaling during stress contamination. The results show that clams collected at least one of the three polluted sites presented significantly higher concentrations of silver (Ag, arsenic (As, cobalt (Co, copper (Cu, mercury (Hg, nickel (Ni, tin (Sn and lead (Pb in tissues. In the visceral tissue, total MT levels and the reduced, metal-binding form of the protein were significantly induced at the sites. The phosphorylation of MT and mitochondrial activity, as determined by electron transport and cytochrome c oxidase activities, were also significantly reduced at the contaminated sites. Reduced phosphate levels in MT were negatively correlated with total MT levels, suggesting that decreased phosphorylation was involved in kinase-mediated signaling during cellular stress and could possibly alter the protein’s affinity to confer cytoprotection against heavy metal contamination. These preliminary investigations revealed that the phosphorylation state could change in polluted environment and provide some clues on the modulation of binding affinities during heavy-metal and oxidative stress in clams.

  18. Comparative genomics of vesicomyid clam (Bivalvia: Mollusca chemosynthetic symbionts

    Directory of Open Access Journals (Sweden)

    Girguis Peter R

    2008-12-01

    Full Text Available Abstract Background The Vesicomyidae (Bivalvia: Mollusca are a family of clams that form symbioses with chemosynthetic gamma-proteobacteria. They exist in environments such as hydrothermal vents and cold seeps and have a reduced gut and feeding groove, indicating a large dependence on their endosymbionts for nutrition. Recently, two vesicomyid symbiont genomes were sequenced, illuminating the possible nutritional contributions of the symbiont to the host and making genome-wide evolutionary analyses possible. Results To examine the genomic evolution of the vesicomyid symbionts, a comparative genomics framework, including the existing genomic data combined with heterologous microarray hybridization results, was used to analyze conserved gene content in four vesicomyid symbiont genomes. These four symbionts were chosen to include a broad phylogenetic sampling of the vesicomyid symbionts and represent distinct chemosynthetic environments: cold seeps and hydrothermal vents. Conclusion The results of this comparative genomics analysis emphasize the importance of the symbionts' chemoautotrophic metabolism within their hosts. The fact that these symbionts appear to be metabolically capable autotrophs underscores the extent to which the host depends on them for nutrition and reveals the key to invertebrate colonization of these challenging environments.

  19. Toxicological evaluation of two pedigrees of clam Ruditapes philippinarum as bioindicators of heavy metal contaminants using metabolomics.

    Science.gov (United States)

    Ji, Chenglong; Cao, Lulu; Li, Fei

    2015-03-01

    Heavy metal pollution has been of great concern in the Bohai marine environment. Manila clam Ruditapes philippinarum has been used as a bioindicator in marine toxicology. In this study, NMR-based metabolomics was used to ascertain whether there were significant biological differences between two dominant pedigrees (White and Zebra) of clam and evaluate the suitability of two pedigrees for marine environmental toxicology, together with antioxidant enzymatic analysis. Our results indicated that there were significant biological differences between White and Zebra clams based on the metabolic profiles and antioxidant enzyme activities. In details, the metabolic profiles showed higher levels of amino acids and succinate in Zebra clam digestive glands and higher levels of ATP in White clam digestive glands, respectively. The superoxide dismutase activities in control White and Zebra clam samples were significantly different. Additionally, White clam was more sensitive to Cd based on the significant accumulation of Cd, antioxidant enzymatic alterations and sensitive metabolic changes. Overall, we concluded that White clam could be a preferable bioindicator for marine environmental toxicology. PMID:25681705

  20. Clam Ruditapes philippinarum recovery from short-term exposure to the combined effect of salinity shifts and Arsenic contamination.

    Science.gov (United States)

    Velez, Catia; Teixeira, Miguel; Wrona, Frederick J; Soares, Amadeu M V M; Figueira, Etelvina; Freitas, Rosa

    2016-04-01

    The current study assessed the biochemical alterations induced in the clam species Ruditapes philippinarum after exposure to salinity shifts (14, 28 and 42) and arsenic (As) contamination (0 and 2mg/L). The capacity of this species to recover (96h and 28 days) after exposure (96h) to both stressors, acting alone and in combination, was also evaluated. After exposure, regardless of the salinity tested, clams contaminated with As showed higher concentrations than non-contaminated specimens. After recovery, As concentration in clams decreased, with contaminated and non-contaminated specimens presenting similar values. The results obtained further demonstrated that exposure to As (2mg/L) at different salinities (salinities 14, 28 and 42) and salinity 42 (As 0mg/L) lead to an increase of lipid peroxidation and detoxification mechanisms in clams, compared with non-contaminated clams at salinities of 14 and 28. After recovery, at salinities 14 and 28, clams previously exposed to As were capable to decrease their oxidative stress to levels found in non-contaminated clams. Nevertheless, at salinity 42 both contaminated and non-contaminated clams did not survive. Overall results of measured energy-related parameters, indicators of oxidative stress, antioxidant and biotransformation enzymes indicated that As exposure and salinity shifts caused biochemical alterations in R. philippinarum, with stronger impacts when both stressors were acting in combination. PMID:26889773

  1. Permanent genetic resources added to molecular ecology resources database 1 august 2011-30 september 2011

    OpenAIRE

    A'Hara, S.W.; Amouroux, P.; Argo, Emily.E.; Avand-Faghih, A.; Barat, Ashoktaru; Barbieri, Luiz; Bert, Theresa M.; Blatrix, R.; Blin, Aurelie; Bouktila, D.; Broome, A.; Burban, Christian; Capdevielle-Dulac, C.; Casse, N.; Chandra, Suresh

    2012-01-01

    This article documents the addition of 299 microsatellite marker loci and nine pairs of single-nucleotide polymorphism (SNP) EPIC primers to the Molecular Ecology Resources (MER) Database. Loci were developed for the following species: Alosa pseudoharengus, Alosa aestivalis, Aphis spiraecola, Argopecten purpuratus, Coreoleuciscus splendidus, Garra gotyla, Hippodamia convergens, Linnaea borealis, Menippe mercenaria, Menippe adina, Parus major, Pinus densiflora, Portunus trituberculatus, Procon...

  2. Review on the Risk Assessment of Heavy Metals in Malaysian Clams.

    Science.gov (United States)

    Hossen, Md Faruk; Hamdan, Sinin; Rahman, Md Rezaur

    2015-01-01

    The current review discusses the levels of six heavy metals in different clam species from 34 sites of Malaysian coasts. The concentrations (µg/g dry weight) of these heavy metals ranged around 0.18-8.51, 0.13-17.20, 2.17-7.80, 0.84-36.00, 24.13-368.00, and 177.82-1912.00 for Cd, Pb, Ni, Cu, Zn, and Fe, respectively. It was observed that the concentrations of metals slightly depend on different clam species but mostly depend on site locations. According to Malaysian Food Regulation (1985), about 30% and more than 50% sites are safe from Cd and Pb contamination, respectively, and also the clam species from the other populations studied were safe for consumption. PMID:26060840

  3. Review on the Risk Assessment of Heavy Metals in Malaysian Clams

    Directory of Open Access Journals (Sweden)

    Md. Faruk Hossen

    2015-01-01

    Full Text Available The current review discusses the levels of six heavy metals in different clam species from 34 sites of Malaysian coasts. The concentrations (µg/g dry weight of these heavy metals ranged around 0.18–8.51, 0.13–17.20, 2.17–7.80, 0.84–36.00, 24.13–368.00, and 177.82–1912.00 for Cd, Pb, Ni, Cu, Zn, and Fe, respectively. It was observed that the concentrations of metals slightly depend on different clam species but mostly depend on site locations. According to Malaysian Food Regulation (1985, about 30% and more than 50% sites are safe from Cd and Pb contamination, respectively, and also the clam species from the other populations studied were safe for consumption.

  4. Progress in development of CLAM steel and fabrication of small TBM in China

    International Nuclear Information System (INIS)

    China Low Activation Martensitic (CLAM) steel is being developed at the Institute of Plasma Physics, Chinese Academy of Sciences under collaboration with many institutes and universities. This steel has been chosen as the primary candidate structural material for the LiPb blanket and DFLL-TBM developed in China. The development and testing strategy for DFLL-TBM includes three stages: out-of-pile tests, tests in EAST, and tests in ITER. The joining of CLAM by Hot Isostatic Pressing Diffusion Welding and Electron Beam Welding is being studied in detail, and small scale panels of the TBM first wall and cover plate with flow channels are being fabricated. Properties of CLAM including fatigue crack growth, creep properties and compatibility with liquid LiPb are also being studied. Recent progress in these R and D activities is summarized.

  5. Numerical simulation and experimental study of cold forming for CLAM steel reducer

    International Nuclear Information System (INIS)

    The research on the formability of CLAM steel pipe fittings with high quality is important for the fabrication of pipe line system in nuclear fusion project. The cold forming process to manufacture CLAM shape tube was evaluated via numerical simulation in this work. The variation of velocity vector in the cold forming process was studied, and the effective stress. strain distribution and push force prediction of cold forming were presented. Subsequently, the tube blank was coated by the lubricating coating with lower friction coefficient. Then practical forming was carried out according to the simulation results. The simulation results agreed well with the experimental ones in the geometry size and thickness distribution. This indicates that the numerical simulation predicted the practical forming effects of CLAM reducer effectively. (authors)

  6. Finite element simulation and experimental study of push-bending processes for CLAM steel elbow

    International Nuclear Information System (INIS)

    The early application of CLAM steel in nuclear fusion project need to solve the difficult of fabrication of tube blank by cold forming processing. The push-bending processes for CLAM steel elbow at room temperature was simulated in this work by means of the numerical simulation software Dynaform. The optimization of process parameters and the prediction of cold forming effect were then studied,and the optimized process parameters were determined. Subsequently, the tube blank was coated by the lubricating agent with friction factor of 0.07. Then practical forming was carried out according to the optimal process parameters. The investigation obviously indicated that simulation results agreed well with the experiment in thickness distribution and surface quality. Therefore, it can be concluded through the very good results of the experiments that the optimization calculation of FE simulation can guide the practical forming of CLAM steel tube blank used in nuclear fusion project in the future. (authors)

  7. Effect of coastal eutrophication on heavy metal bioaccumulation and oral bioavailability in the razor clam, Sinonovacula constricta

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Tengxiu [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Li, Shunxing, E-mail: lishunxing@mnnu.edu.cn [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology (China); Chen, Lihui [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Zheng, Fengying; Huang, Xu-Guang [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology (China)

    2014-10-15

    Graphical abstract: - Highlights: • Razor clams are often exposed to coastal eutrophication. • The bioaccumulation of Fe, Ni, V, and As was promoted by eutrophication. • Bionic gastrointestinal tract was used for metal oral bioavailability assessment. • Eutrophication decreased oral bioavailability of Fe and Pb but enhanced for V. • The daily maximum allowable intakes are controlled by eutrophication levels. - Abstract: As traditional seafoods, the razor clams are widely distributed from tropical to temperate areas. Coastal razor clams are often exposed to eutrophication. Heavy metal contamination is critical for seafood safety. However, how eutrophication affects bioaccumulation and oral bioavailability of heavy metals in the razor clams is unknown. After a four-month field experimental cultivation, heavy metals (Fe, Cu, Ni, V, As, and Pb) could be bioaccumulated by the razor clams (Sinonovacula constricta) through exposure to metals present in water and sediments or in the food chain, and then transferred to human via consumption of razor clams. Bionic gastrointestinal digestion and monolayer liposome extraction are used for metal oral bioavailability (OBA) assessment. The influence of eutrophication on OBA is decreased for Fe and Pb and increased for V. A significant positive linear correlation was observed between the bioaccumulation factors of Fe, Ni, V, and As in razor clams and the coastal eutrophication. These results may be due to the effect of eutrophication on metal species transformation in coastal seawater and subcellular distribution in razor clams. The maximum allowable daily intakes of razor clams are controlled by eutrophication status and the concentration of affinity-liposome As in razor clams.

  8. Effect of coastal eutrophication on heavy metal bioaccumulation and oral bioavailability in the razor clam, Sinonovacula constricta

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Razor clams are often exposed to coastal eutrophication. • The bioaccumulation of Fe, Ni, V, and As was promoted by eutrophication. • Bionic gastrointestinal tract was used for metal oral bioavailability assessment. • Eutrophication decreased oral bioavailability of Fe and Pb but enhanced for V. • The daily maximum allowable intakes are controlled by eutrophication levels. - Abstract: As traditional seafoods, the razor clams are widely distributed from tropical to temperate areas. Coastal razor clams are often exposed to eutrophication. Heavy metal contamination is critical for seafood safety. However, how eutrophication affects bioaccumulation and oral bioavailability of heavy metals in the razor clams is unknown. After a four-month field experimental cultivation, heavy metals (Fe, Cu, Ni, V, As, and Pb) could be bioaccumulated by the razor clams (Sinonovacula constricta) through exposure to metals present in water and sediments or in the food chain, and then transferred to human via consumption of razor clams. Bionic gastrointestinal digestion and monolayer liposome extraction are used for metal oral bioavailability (OBA) assessment. The influence of eutrophication on OBA is decreased for Fe and Pb and increased for V. A significant positive linear correlation was observed between the bioaccumulation factors of Fe, Ni, V, and As in razor clams and the coastal eutrophication. These results may be due to the effect of eutrophication on metal species transformation in coastal seawater and subcellular distribution in razor clams. The maximum allowable daily intakes of razor clams are controlled by eutrophication status and the concentration of affinity-liposome As in razor clams

  9. Responses of Manila clam growth and its food sources to global warming in a subarctic lagoon in Japan

    Science.gov (United States)

    Yoon, Seokjin; Abe, Hiroya; Kishi, Michio J.

    2013-12-01

    Akkeshi Lake is a subarctic shallow brackish lagoon located in Hokkaido, Japan. The Manila clam, Ruditapes philippinarum, is cultured in sandy sediments at the shallow, intertidal flat near the mouth of the lake. To quantitatively evaluate the effects of environmental factors such as water temperature and food availability on the growth of the Manila clam and to estimate the responses of Manila clam growth and food availability to global warming in Akkeshi Lake, we developed a numerical model by coupling a three-dimensional ecosystem model with a bioenergetics model for the growth of the Manila clam. We ran the model under two different conditions: the present condition and the global warming condition. For the global warming condition, water temperature was increased by 2 °C at the open boundary for the entire computational period. The growth of the Manila clam was limited by water temperature and food availability. The Manila clam grew up to 1.33 g dry weight ind.-1 at the lake mouth (station A) for 5 years, whereas it grew up to 1.00 g dry weight ind.-1 at the lake center (station B). The difference in the biomass of the Manila clam between two stations was due to the difference in food availability. Under the global warming condition, the water temperature limitation for the Manila clam was relaxed with a water temperature increase. The Manila clam grew up to 1.55 g dry weight ind.-1 at station A and 1.10 g dry weight ind.-1 at station B. While the growth of the Manila clam was improved in the lake under the global warming condition, its food sources, especially phytoplankton, decreased because of ingestion increases of grazers.

  10. An overview of the welding technologies of CLAM steels for fusion application

    International Nuclear Information System (INIS)

    Highlights: ► Welding technologies of China Low Activation Martensitic steel is overviewed. ► Most welding technologies in use are discussed and suggestions are given. ► Proper welding technologies could ensure weld properties but more detailed work are necessary. - Abstract: China Low Activation Martensitic steel (CLAMs), a kind of RAFM steel with Chinese intellectual property rights, is considered as the primary structural material for the China-designed ITER test blanket module (TBM). As one of the key issues in the fabrication of the fusion reactor, the welding technologies of CLAMs are reviewed. Emphasis is placed on the weldability of CLAMs by different welding methods, and on the properties of as-welded and post-weld heat-treated joints. Recent highlights in research and development for the welding of CLAMs show that proper welding procedure could provide welds with adequate tensile strength but the welds exhibit lower impact toughness compared with the base metal. Post-weld heat treatment (PWHT) and the application of ultrasonic energy during TIG welding could dramatically improve impact toughness. Research also shows that welds in CLAMs have sufficient resistance to swelling under irradiation as well as suitable compatibility with liquid LiPb. The microstructure, mechanical and other physical properties of welds are significantly different from those of the base metal due to the complicated welding thermal cycle. The weld joint is the area most likely to fail one or more of the design requirements within the fusion reactor. Therefore significant additional research is necessary to ensure safe application of welded CLAM steel for fusion reactor construction.

  11. Microstructure and nanoindentation of the CLAM steel with nanocrystalline grains under Xe irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yongqin, E-mail: chang@ustb.edu.cn; Zhang, Jing; Li, Xiaolin; Guo, Qiang; Wan, Farong; Long, Yi

    2014-12-15

    This work presents an early look at irradiation effects on China low activation martensitic (CLAM) steel with nanocrystalline grains (NC-CLAM steels) under 500 keV Xe-ion bombardment at room temperature to doses up to 5.3 displacements per atom (dpa). The microstructure in the topmost region of the steel is composed of nanocrystalline grains with an average diameter of 13 nm. As the samples were implanted at low dose, the nanocrystalline grains had martensite lath structure, and many dislocations and high density bubbles were introduced into the NC-CLAM steels. As the irradiation dose up to 5.3 dpa, a tangled dislocation network exists in the lath region, and the size of the bubbles increases. X-ray diffraction results show that the crystal quality decreases after irradiation, although the nanocrystals obviously coarsen. Grain growth under irradiation may be ascribed to the direct impact of the thermal spike on grain boundaries in the NC-CLAM steels. In irradiated samples, a compressive stress exists in the surface layer because of grain growth and irradiation-introduced defects, while the irradiation introduced grain-size coarsening and defects gradients from the surface to matrix result in a tensile stress in the irradiated NC-CLAM steels. Nanoindentation was used to estimate changes in mechanical properties during irradiation, and the results show that the hardness of the NC-CLAM steels increases with increasing irradiation dose, which was ascribed to the competition between the grain boundaries and the irradiation-introduced defects.

  12. Microstructure and nanoindentation of the CLAM steel with nanocrystalline grains under Xe irradiation

    International Nuclear Information System (INIS)

    This work presents an early look at irradiation effects on China low activation martensitic (CLAM) steel with nanocrystalline grains (NC-CLAM steels) under 500 keV Xe-ion bombardment at room temperature to doses up to 5.3 displacements per atom (dpa). The microstructure in the topmost region of the steel is composed of nanocrystalline grains with an average diameter of 13 nm. As the samples were implanted at low dose, the nanocrystalline grains had martensite lath structure, and many dislocations and high density bubbles were introduced into the NC-CLAM steels. As the irradiation dose up to 5.3 dpa, a tangled dislocation network exists in the lath region, and the size of the bubbles increases. X-ray diffraction results show that the crystal quality decreases after irradiation, although the nanocrystals obviously coarsen. Grain growth under irradiation may be ascribed to the direct impact of the thermal spike on grain boundaries in the NC-CLAM steels. In irradiated samples, a compressive stress exists in the surface layer because of grain growth and irradiation-introduced defects, while the irradiation introduced grain-size coarsening and defects gradients from the surface to matrix result in a tensile stress in the irradiated NC-CLAM steels. Nanoindentation was used to estimate changes in mechanical properties during irradiation, and the results show that the hardness of the NC-CLAM steels increases with increasing irradiation dose, which was ascribed to the competition between the grain boundaries and the irradiation-introduced defects

  13. Microstructure and nanoindentation of the CLAM steel with nanocrystalline grains under Xe irradiation

    Science.gov (United States)

    Chang, Yongqin; Zhang, Jing; Li, Xiaolin; Guo, Qiang; Wan, Farong; Long, Yi

    2014-12-01

    This work presents an early look at irradiation effects on China low activation martensitic (CLAM) steel with nanocrystalline grains (NC-CLAM steels) under 500 keV Xe-ion bombardment at room temperature to doses up to 5.3 displacements per atom (dpa). The microstructure in the topmost region of the steel is composed of nanocrystalline grains with an average diameter of 13 nm. As the samples were implanted at low dose, the nanocrystalline grains had martensite lath structure, and many dislocations and high density bubbles were introduced into the NC-CLAM steels. As the irradiation dose up to 5.3 dpa, a tangled dislocation network exists in the lath region, and the size of the bubbles increases. X-ray diffraction results show that the crystal quality decreases after irradiation, although the nanocrystals obviously coarsen. Grain growth under irradiation may be ascribed to the direct impact of the thermal spike on grain boundaries in the NC-CLAM steels. In irradiated samples, a compressive stress exists in the surface layer because of grain growth and irradiation-introduced defects, while the irradiation introduced grain-size coarsening and defects gradients from the surface to matrix result in a tensile stress in the irradiated NC-CLAM steels. Nanoindentation was used to estimate changes in mechanical properties during irradiation, and the results show that the hardness of the NC-CLAM steels increases with increasing irradiation dose, which was ascribed to the competition between the grain boundaries and the irradiation-introduced defects.

  14. Code aus einem Forschungskontext mit CLAM in einen Web-Service verwandeln

    OpenAIRE

    Matteo Romanello

    2016-01-01

    Poster bei dem von CLARIN-D veranstaltetem CA3 Forum im Hamburg. Der Computational Linguistics Application Mediator (CLAM) ist ein im Rahmen von CLARIN-NL entwickeltes Python Tool, das darauf abzielt, die Transformation von Code aus einem Forschungskontext in einen Web-Service zu vereinfachen (van Gompel & Reynaert 2014). Während der HandsOn Session wird die CLAM Anwendung am Beispiel des für meine Promotion entwickelte Programms vorge...

  15. Review on the Risk Assessment of Heavy Metals in Malaysian Clams

    OpenAIRE

    Md. Faruk Hossen; Sinin Hamdan; Md. Rezaur Rahman

    2015-01-01

    The current review discusses the levels of six heavy metals in different clam species from 34 sites of Malaysian coasts. The concentrations (µg/g dry weight) of these heavy metals ranged around 0.18–8.51, 0.13–17.20, 2.17–7.80, 0.84–36.00, 24.13–368.00, and 177.82–1912.00 for Cd, Pb, Ni, Cu, Zn, and Fe, respectively. It was observed that the concentrations of metals slightly depend on different clam species but mostly depend on site locations. According to Malaysian Food Regulation (1985), ab...

  16. Male claspers in clam shrimps (Crustacea, Branchiopoda) in the light of evolution

    DEFF Research Database (Denmark)

    Kaji, Tomonari; Fritsch, Martin; Schwentner, Martin; Olesen, Jørgen; Richter, Stefan

    2014-01-01

    Male "clam shrimps" possess highly modified first (and second) trunk limbs for clasping the carapace of females during copulation. Claspers are present in all three clam shrimp taxa (Laevicaudata, Spinicaudata, and Cyclestherida) but despite striking similarities in their morphology and function......, the matter of their homology is controversial. In this study, we address the question of the homology and evolution of these structures by comparing the developmental transformation of an unspecialized trunk limb into a clasper. In addition, we study the musculature and the nervous system in trunk...

  17. Diarrhetic shellfish poisoning toxin esters in Danish blue mussels and surf clams

    DEFF Research Database (Denmark)

    Jørgensen, Kevin; Scanlon, Sine Hedegaard; Jensen, L.B.

    2005-01-01

    . Samples of Danish surf clams ( Spisola spp.) and blue mussels ( Mytilus edulis) from 1999 - 2004 were analysed by liquid chromatography coupled with tandem mass spectrometry ( LC/ MS/ MS) for the presence of DSP toxin esters. The samples contained only okadaic acid and esters of okadaic acid. The level of...... total okadaic acid equivalents ranged from 224 to 2516 mu g kg (-1) in surf clams. The percentage of okadaic acid esters of the total okadaic acid equivalents ranged from 83 to 98%, mean 95%. The level of total okadaic acid equivalents ranged from 43 to 1631 mu g kg (-1) in blue mussels. The percentage...

  18. Metabolomic analysis revealed the differential responses in two pedigrees of clam Ruditapes philippinarum towards Vibrio harveyi challenge.

    Science.gov (United States)

    Liu, Xiaoli; Zhao, Jianmin; Wu, Huifeng; Wang, Qing

    2013-12-01

    Manila clam Ruditapes philippinarum is an important marine aquaculture shellfish. This species has several pedigrees including White, Zebra, Liangdao Red and Marine Red distributing in the coastal areas in North China. In this work, we studied the metabolic differences induced by Vibrio harveyi in hepatopancreas from White and Zebra clams using NMR-based metabolomics. Metabolic responses (e.g., amino acids, glucose, glycogen, ATP and succinate) and altered mRNA expression levels of related genes (ATP synthase, heat shock protein 90, defensin and lysozyme) suggested that V. harveyi induced clear disruption in energy metabolism and immune stresses in both White and Zebra clam hepatopancreas. However, V. harveyi caused obvious osmotic stress in Zebra clam hepatopancreas, which was not observed in V. harveyi-challenged White clams samples. In addition, V. harveyi challenge induced more severe disruption in energy metabolism and immune stress in White clams than in Zebra clams. Overall, our results indicated that the biological differences between different pedigrees of R. philippinarum should be considered in immunity studies. PMID:24161758

  19. Direct contribution of clams (Ruditapes philippinarum) to benthic fluxes, nitrification, denitrification and nitrous oxide emission in a farmed sediment

    Science.gov (United States)

    Welsh, David T.; Nizzoli, Daniele; Fano, Elisa A.; Viaroli, Pierluigi

    2015-03-01

    The influence of the manila clam (Ruditapes philippinarum) on N-cycle processes, and oxygen and nutrient fluxes in a farmed sediment was investigated using a multiple core incubation approach and parallel incubations of individual clams. Clam population/biomass density varied ∼8-fold between cores and all sediment-water column solute (O2. N2, N2O, NH4+, NOX and DIN) fluxes and benthic process (N-regeneration, nitrification and denitrification) rates were strongly and significantly correlated with clam density/biomass. Isolated clams exhibited high rates of respiration, N-excretion, nitrification and denitrification of 2050 ± 70, 395 ± 49, 201 ± 42 and 235 ± 40 nmol individual-1 h-1, respectively. The direct contribution of the clams and their associated microbiota to benthic processes was estimated by multiplying the per individual rates by the number of clams in each incubated core. The clams on average directly accounted for 64-133% of total rates of sediment oxygen demand, N-regeneration, nitrification and denitrification, indicating that they regulated processes primarily through their own metabolic activity and that of bacteria that colonise them. Clams and the farmed sediments were significant sources of the greenhouse gas N2O, but this was primarily due to their high nitrification and denitrification rates, rather than high specific N2O yields, as N2O emissions represented environmental cost of increased N-regeneration and N2O emission rates. The measured N2O emissions indicate that bivalve aquaculture may be a significant source of N2O. It is therefore recommended that N2O emissions should be included in the impact assessments of current and future bivalve-farming projects.

  20. Microstructures and Mechanical Properties of Laser Welding Joint of a CLAM Steel with Revised Chemical Compositions

    Science.gov (United States)

    Chen, Shuhai; Huang, Jihua; Lu, Qi; Zhao, Xingke

    2016-05-01

    To suppress the tendency to form delta ferrite in weld metal (WM) of China low activation martensitic (CLAM) steel joint, a CLAM steel with revised chemical compositions was designed. Laser welding of the CLAM steel was investigated. The microstructures of the WM and heat-affected zone were analyzed. The impact toughness of the WM was evaluated by a Charpy impact test method with three V notches. The influence of temper temperature on mechanical properties was analyzed. It was found that the delta ferrite was eliminated almost completely in laser WM of CLAM steel with revised chemical compositions which has lower tendency to form delta ferrite than original chemical compositions. The joint has higher tensile strength than the parent metal. With increasing the heat input, the impact toughness of the joint is approximatively equal with that of parent metal first and then decreases obviously. Temper treatment could effectively improve mechanical property of the joint. When the temper temperature exceeds 600 °C, the impact toughness of the joint is higher than that of the parent metal.

  1. Microstructures and Mechanical Properties of Laser Welding Joint of a CLAM Steel with Revised Chemical Compositions

    Science.gov (United States)

    Chen, Shuhai; Huang, Jihua; Lu, Qi; Zhao, Xingke

    2016-03-01

    To suppress the tendency to form delta ferrite in weld metal (WM) of China low activation martensitic (CLAM) steel joint, a CLAM steel with revised chemical compositions was designed. Laser welding of the CLAM steel was investigated. The microstructures of the WM and heat-affected zone were analyzed. The impact toughness of the WM was evaluated by a Charpy impact test method with three V notches. The influence of temper temperature on mechanical properties was analyzed. It was found that the delta ferrite was eliminated almost completely in laser WM of CLAM steel with revised chemical compositions which has lower tendency to form delta ferrite than original chemical compositions. The joint has higher tensile strength than the parent metal. With increasing the heat input, the impact toughness of the joint is approximatively equal with that of parent metal first and then decreases obviously. Temper treatment could effectively improve mechanical property of the joint. When the temper temperature exceeds 600 °C, the impact toughness of the joint is higher than that of the parent metal.

  2. Multidrug-resistant and epidemic clones of Escherichia coli from natural beds of Venus clam.

    Science.gov (United States)

    Vignaroli, C; Di Sante, L; Leoni, F; Chierichetti, S; Ottaviani, D; Citterio, B; Biavasco, F

    2016-10-01

    Epidemic Escherichia coli clones have been recovered in marine sediment along the coast of Marche, an Adriatic region in central Italy. In the present study, E. coli strains from the clam Chamelea gallina, sampled from seven natural beds in the same area, were detected. Selected E. coli isolates from all sampling sites were screened for antimicrobial susceptibility, genetic diversity and correlation. The majority (60%) belonged to phylogroups A or B1, 31% to the other groups (B2, C, D, E, F), 8% to cryptic clades, and 1% were untypable. Moreover, 33.3% of isolates were resistant to at least one drug and 11% were multidrug resistant (MDR). The most common resistance was to tetracycline, ampicillin, and streptomycin. No clonality was detected, but the strains' high genetic heterogeneity pointed at multiple sources of microbiological contamination. MLST analysis found potentially pathogenic and even epidemic MDR strains in clams collected in class A (ST746 and ST46) and class B (ST393, ST58 and ST131) areas, indicating that strains of clinical origin are detectable in clams. These data highlight that eating raw or lightly cooked clams may pose a health risk if purification is not performed or is ineffective. PMID:27375238

  3. Fisheries ecology: hunger for shark fin soup drives clam chowder off the menu.

    Science.gov (United States)

    Brierley, Andrew S

    2007-07-17

    Removal by fishing of large sharks has reduced predation-pressure on shark prey and, via a trophic cascade, caused clam populations to crash. This indirect response illustrates why fisheries should be managed in a whole-ecosystem context. PMID:17637357

  4. Use of minimum legal size in managing black clam (Villorita cyprinoides fishery in India

    Directory of Open Access Journals (Sweden)

    Nagampoozhi Suja

    2014-01-01

    Full Text Available Using size at first maturity (SFM as a biological reference point, the minimum legal size (MLS for the black clam, Villorita cyprinoides was fixed at 20 mm. Corresponding minimum legal weight was calculated as 3.4 g. The reproductive load and mean generation time were determined as 0.35 and 0.72, respectively. Of the total quantity of clams exploited during 1996-97, 50% were juveniles. The percentage was reduced to 7.9% during 2009-10. The loss in harvest weights due to exploitation of juvenile clam was 50%, 23% and 37% and the economic loss caused was US$ 4.6 million, US$ 1.5 million and US$ 1.1 million for the periods 1996-97, 2000-01 and 2002-03, respectively. If the undersized clams were permitted to grow up to MLS, the harvest weights could have improved by up to 24% and hence the economic gain is to the tune of US$ 1.40 million during 2009-10. The difference between the present Lmean in the fishery and the Lopt is 4 mm.

  5. Uptake of trace metals by the clam Macoma inquinata from clean and oil-contaminated detritus

    International Nuclear Information System (INIS)

    In recent years there has been increasing concern about the entry of petroleum hydrocarbon (PHC) into the marine environment and the effects of such entry on the composition and functioning of the marine ecosystem. Few reports have been published on the possible effect of oil on the uptake of metals from water or sediments by animals. The possibility of such effects is indicated by the work of Fletcher et al. (1979), who showed that crude oil causes a reduction in blood plasma copper concentrations in fish, and Payne et al. (1978) who reported that petroleum affected chloride regulation in fish. Luoma and Jenne (1977) have shown that the availability of sediment-bound metals to a deposit-feeding clam depended on the metal-sediment associated and sediment-to-water desorption rate. We exposed a detritivorous clam, Macoma inquinata, to clean and oil-contaminated detritus to determine the effects of the oil on metal accumulation. To measure the uptake of metals, clams were exposed to neutron activated detritus and the uptake of several isotopes (51Cr, 60Co, 152Eu, 59Fe, 46Sc, and 65Zn) measured in the clams

  6. 50 CFR 17.45 - Special rules-snails and clams. [Reserved

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 2 2010-10-01 2010-10-01 false Special rules-snails and clams. 17.45 Section 17.45 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR (CONTINUED) TAKING, POSSESSION, TRANSPORTATION, SALE, PURCHASE, BARTER, EXPORTATION, AND IMPORTATION OF WILDLIFE AND PLANTS (CONTINUED)...

  7. First molluscan antimicrobial peptide hydramacin in Manila clam:molecular characterization and expression analysis

    Institute of Scientific and Technical Information of China (English)

    Youngdeuk Lee; Saranya Revathy K; Sukkyoung Lee; Ilson Whang; Chulhong Oh; Do-Hyung Kang; Gee-Wook Shin; Jehee Lee; Mahanama De Zoysa

    2014-01-01

    Objective:To investigate molecular characterization and the immune responses of Manila clam hydramacin (Rp-hdmc). Methods:cDNA sequence of hydramacin was isolated from Manila clam transcriptome database. Molecular characterization of hydramacin cDNA was performed by BLAST and SWISS-MODEL bioinformatics programs. Tissue-specific expression and transcriptional regulation after Vibrio tapetis challenge was done by quantitative real time PCR. Results:Rp-hdmc has 291 bp open reading frame (ORF), encoding 97 amino acids with a mature hydramacin consisting of 77 amino acid residues. In un-challenged clam, Rp-hdmc was constitutively expressed in all tested tissues and the highest expression level was detected in gill. After pathogenic bacteria Vibrio tapetis challenge, Rp-hdmc mRNA was up-regulated in gill and hemocytes. Conclusions: We identified hydramacin cDNA (Rp-hdmc) from mollusk Manila clam that shows the characteristic features of hydramacin sequence. It has eight cysteine residues with four disulfide linkages, three helices and twoβ-strands in secondary structure. Expression results after V. tapetis challenges suggest that Rp-hdmc is involved in immune response against pathogenic bacteria.

  8. Native and introduced clams biochemical responses to salinity and pH changes.

    Science.gov (United States)

    Velez, Catia; Figueira, Etelvina; Soares, Amadeu M V M; Freitas, Rosa

    2016-10-01

    By the end of year 2100 physiological and biochemical performance of aquatic organisms are expected to become strongly affected by salinity and pH shifts, which in turn may favor the conditions for introduced species to invade new ecosystem areas. Given this, we evaluated the effects of salinity and pH changes in native Ruditapes decussatus and introduced Ruditapes philippinarum clams, by measuring different biomarkers related to oxidative stress, metabolic activity and osmoregulation capacity. Results showed that extreme salinities induced mortality in both species, while all clams survived under low pH (7.3). Both species mobilized glycogen as a source of energy towards cells protection mechanisms under extreme salinities. The native species presented higher lipid peroxidation levels while the introduced species was able to prevent oxidative damages through the induction of antioxidant enzymes at most extreme salinities. R. philippinarum also induced CA activity to balance the ion homeostasis at extreme salinities. In contrast, low pH induced oxidative damages, an increase of antioxidant (catalase), detoxification (glutathione S-transferases) and osmoregulation (carbonic anhydrase) mechanisms in R. philippinarum compared to the native clams. Overall, salinity and pH changes can alter physiological and biochemical status of native and introduced clam species. PMID:27220103

  9. The clam (Chamelea gallina: evaluation of the effects of solids suspended in seawater on bivalve molluscs

    Directory of Open Access Journals (Sweden)

    Salvatora Angela Angioni

    2010-03-01

    Full Text Available The study was designed to evaluate the effects of solids in suspension in seawater on clams (Chamelea gallina. The aim was to investigate the possible correlation between the widespread deaths of clams in the coastal waters of the central and northern Adriatic in the last five years and increased concentrations of solids in suspension. The research involved conducting 96-hour tests on clams farmed in aquariums containing filtered seawater. The tests were preceded by a 7-day adaptation stage to allow the molluscs to acclimatise. During this period, the clams were fed on unicellular seaweed (Dunaliella tertiolecta. The molluscs were exposed to particles of solids in suspension consisting of pools of silica gel (SiO2 granules of various sizes, similar to those constituting silt, whose presence and suspension in the sea considerably increase after heavy rain and heavy seas. The study established that the number of deaths caused by solids suspended in seawater at the concentrations used in the tests was not statistically significant.

  10. Habitat Descriptionof the Threatened Freshwater Clam, Galatea paradoxa (Born 1778 at the Volta Estuary, Ghana

    Directory of Open Access Journals (Sweden)

    K.A. Obirikorang

    2013-12-01

    Full Text Available This research was conducted to at two of the few remaining habitats of the threatened freshwater clam (Galatea paradoxa at the Volta Estuary in Ghana to describe the current state of the clam habitat with respect to the physicochemical water parameters and the characterize the bottom sediment on which they thrive. The research was carried out over an 18-month period with the aim of facilitating the transplanting of juvenile clams from their natural habitats to portions of the estuarine environments with similar physicochemical and characteristics which will consequently lead to the conservation of the clampopulation and expansion of the clam habitat. The measured physicochemical water parameters were fairly similar at the two locations and exhibited temporal fluctuations which could be attributed to seasonal changes as well as anthropogenic activities within the catchment of the sampling locations.The results of the grain size analyses revealed very low sedimentological diversity and it was observed that the estuarine sediments fall under the sandy textural group (>95% which characterized both sampling locations in the Estuary.

  11. CLAM - CoLlAborative eMbedded networks for submarine surveillance: An overview

    NARCIS (Netherlands)

    Meratnia, Nirvana; Havinga, Paul J.M.; Casari, Paolo; Petrioli, Chiara; Grythe, Knut; Husoy, Thor; Zorzi, Michele

    2011-01-01

    This paper provides an overview of the CLAM project, which aims at developing a collaborative embedded monitoring and control platform for submarine surveillance by combining cutting edge acoustic vector sensor technology and 1D, 2D, 3D sensor arrays, underwater wireless sensor networks protocol des

  12. Metabolic responses of clam Ruditapes philippinarum exposed to its pathogen Vibrio tapetis in relation to diet.

    Science.gov (United States)

    Richard, Gaëlle; Guérard, Fabienne; Corporeau, Charlotte; Lambert, Christophe; Paillard, Christine; Pernet, Fabrice

    2016-07-01

    We investigated the effect of brown ring disease (BRD) development and algal diet on energy reserves and activity of enzymes related to energy metabolism, antioxidant system and immunity in Manila clam, Ruditapes philippinarum. We found that algal diet did not impact the metabolic response of clams exposed to Vibrio tapetis. At two days post-injection (dpi), activities of superoxide dismutase and glutathione peroxidase (GPx) decreased whereas activities of nitric oxide synthase (iNOS) and catalase increased in infected clams, although no clinical signs were visible (BRD-). At 7 dpi, activities of several antioxidant and immune-related enzymes were markedly increased in BRD-likely indicating an efficient reactive oxygen species (ROS) scavenging compared to animals which developed clinical signs of BRD (BRD+). Therefore, resistance to BRD clinical signs appearance was associated with higher detoxification of ROS and enhancement of immune response. This study provides new biochemical indicators of disease resistance and a more comprehensive view of the global antioxidant response of clam to BRD development. PMID:26921670

  13. Accumulation and tissue distribution of radioiodine (131I) from algal phytoplankton by the freshwater clam Corbicula manilensis

    International Nuclear Information System (INIS)

    Radioactive wastes discharged from establishments involved in the use of radioisotopes such as nuclear-powered industries, tracer research and nuclear medicine are a potential public health hazard. Such wastes contain radionuclides, particularly Iodine-131 (131I), produced in fission with a yield of about 3%. Radionuclides in waste waters are known to be taken up by molluscs such as mussels, oysters, and clams. This study aims to determine the uptake of 131I from algal phytoplankton (Chroococcus dispersus) fed to the freshwater clam Corbicula manilensis as well as the organ/tissue distribution. The results will be compared with a previous study on 131I uptake from water by the same clams

  14. Artificial radioactivity in edible parts of giant clam mollusc from Mururoa atoll from 1967 to 1990. Health physics aspect

    International Nuclear Information System (INIS)

    Radionuclides concentration by giant clams is associated with feeding habit. It's also a main food for polynesian atolls inhabitants, elsewhere than Mururoa island because this mollusc is not consumed like all the other fishery products from this atoll lagoon. Nevertheless measurements of ten artificial radionuclides are performed in edible parts of giant clams fished from Mururoa lagoon since the beginning of nuclear tests. The decay of radionuclides concentration is described versus time. To go further on we have computed the dose-equivalent for internal exposure of an eventual giant clams eater. It is estimated that the resulting risk of malignancy is below than 1 per 10 000

  15. Transcriptome sequencing and microarray development for the Manila clam, Ruditapes philippinarum: genomic tools for environmental monitoring

    Directory of Open Access Journals (Sweden)

    Patarnello Tomaso

    2011-05-01

    Full Text Available Abstract Background The Manila clam, Ruditapes philippinarum, is one of the major aquaculture species in the world and a potential sentinel organism for monitoring the status of marine ecosystems. However, genomic resources for R. philippinarum are still extremely limited. Global analysis of gene expression profiles is increasingly used to evaluate the biological effects of various environmental stressors on aquatic animals under either artificial conditions or in the wild. Here, we report on the development of a transcriptomic platform for global gene expression profiling in the Manila clam. Results A normalized cDNA library representing a mixture of adult tissues was sequenced using a ultra high-throughput sequencing technology (Roche 454. A database consisting of 32,606 unique transcripts was constructed, 9,747 (30% of which could be annotated by similarity. An oligo-DNA microarray platform was designed and applied to profile gene expression of digestive gland and gills. Functional annotation of differentially expressed genes between different tissues was performed by enrichment analysis. Expression of Natural Antisense Transcripts (NAT analysis was also performed and bi-directional transcription appears a common phenomenon in the R. philippinarum transcriptome. A preliminary study on clam samples collected in a highly polluted area of the Venice Lagoon demonstrated the applicability of genomic tools to environmental monitoring. Conclusions The transcriptomic platform developed for the Manila clam confirmed the high level of reproducibility of current microarray technology. Next-generation sequencing provided a good representation of the clam transcriptome. Despite the known limitations in transcript annotation and sequence coverage for non model species, sufficient information was obtained to identify a large set of genes potentially involved in cellular response to environmental stress.

  16. Accumulation of petroleum hydrocarbons and heavy metals in clams (Ruditapes philippinarum) in Jiaozhou Bay, China

    Institute of Scientific and Technical Information of China (English)

    MA Haiqing; SONG Qian; WANG Xuchen

    2009-01-01

    Accumulation and distributions of aliphatic and polyaromatic hydrocarbons (PAHs) and heavy metals were measured in tissues of the clam Ruditapes philippinarum collected from 5 sites in Jiaozhou Bay, Qingdao, China. The concentrations of total aliphatic hydrocarbon and PAHs ranged from 570 to 2 574 ng/gdw (gram dry weight) and from 276 to 939 ng/gdw, in the most and least polluted sites, respectively. The bio-accumulation of hydrocarbons and PAHs in the clams appeared to be selective. Aliphatic hydrocarbons were predominantly represented by short chain (clams was probably related to the physiological and bio-kinetic processes that were energetically favorable for uptake of compounds with fewer rings. Accumulation of the metals Cd, Cu, Zn, Pb, Cr, Hg, and As in the clam tissues also showed high variability, ranging from 0.043 to 87μg/gdw. Among the 7 detected metals, Zn, Cd, Cu, and As had a particularly high potential of accumulation in R. philippinarum. In general, a positive correlation was found between the tissue concentrations and sediment concentrations of hydrocarbons and of some metals. Our study suggests that moderate contamination with polyaromatic hydrocarbons, and low to moderate contamination with metals, currently exists for clam R. philippinarum in Jiaozhou Bay, in comparison with other regional studies. A long-term monitoring program is certainly needed for assessment of the potential ecological influence and toxicity of these contaminants of R. philippinarum in Jiaozhou Bay.

  17. Gene transcription and biomarker responses in the clam Ruditapes philippinarum after exposure to ibuprofen

    Energy Technology Data Exchange (ETDEWEB)

    Milan, Massimo; Pauletto, Marianna; Patarnello, Tomaso; Bargelloni, Luca [Department of Comparative Biomedicine and Food Science, University of Padova, Viale dell' Universita 16, Legnaro (Padova) (Italy); Marin, Maria Gabriella [Department of Biology, University of Padova, Via Ugo Bassi 58/B, 35131 Padova (Italy); Matozzo, Valerio, E-mail: matozzo@bio.unipd.it [Department of Biology, University of Padova, Via Ugo Bassi 58/B, 35131 Padova (Italy)

    2013-01-15

    Pharmaceuticals are a class of emerging environmental contaminants that continuously enter aquatic environments. Presently, little information is available about the effects of these substances on non-target organisms, such as bivalves. We investigated the effects of ibuprofen (IBU) on the clam Ruditapes philippinarum. Clams were exposed for 1, 3, 5 and 7 days to 0, 100 and 1000 {mu}g IBU/L, and established biomarker responses (haemolymph lysozyme, gill acetylcholinesterase and digestive gland superoxide dismutase activities) as well as digestive gland transcriptome were evaluated. A two-way ANOVA revealed significant effects of both 'IBU concentration' and 'exposure duration' on biomarker responses. Overall, the enzyme activities were generally lower in IBU-exposed clams than in controls. Although limited knowledge of the mollusc transcriptome makes it difficult to interpret the effects of IBU on clams, the gene transcription analysis using DNA microarrays enabled the identification of the putative molecular mode of action of the IBU. The functional analysis of differentially transcribed genes suggests that IBU can interfere with various signalling pathways in clams, such as arachidonic acid metabolism, apoptosis, peroxisomal proliferator-activated receptors, and nuclear factor-kappa B. In addition, several genes involved in the metabolism of xenobiotics (e.g., glutathione S-transferase, sulfotransferase, cytochrome P450) were also found to be significantly affected by IBU exposure. In summary, the integrated approach of gene transcription analysis and biomarker responses facilitated the elucidation of the putative mechanisms of action of IBU in non-target species.

  18. Preliminary Study on Hot Isostatic Pressing Diffusion Bonding for CLAM Steel

    International Nuclear Information System (INIS)

    China Low Activation Martensitic (CLAM) steel is being developed in ASIPP (Institute of Plasma Physics, Chinese Academy of Sciences) since three years ago. CLAM is selected as the major candidate structure materials for the FDS series design of fusion reactors and for China liquid metal LiPb Test Blanket Module (TBM) for ITER i.e. DFLL-TBM, which are being carried out in ASIPP. Since the hot isostatic pressing (HIP) bonding technique is one of the main candidate bonding techniques for manufacturing of the first wall of a fusion reactor, research of the HIP technique on CLAM/CLAM is greatly needed. Preliminary HIP diffusion bonding experiments on CLAM steel have been performed. A few machining approaches such as dry-milling, turnery and grounding etc. were used to prepare the sample surfaces and then they were degreased with a mixture of alcohol, ether and acetone in an ultrasonic bath. The samples were joined by HIP diffusion bonding with the compression pressure of 150 MPa and the holding time of 2 ∼ 3 hours under different temperatures between 950 deg. and 1100 deg.. Different seal techniques of the capsules were studied as well. Then appropriate post heat treatment was done. Tests on mechanical properties of the joints such as tensile strength and impact toughness have been performed. The preliminary results show that the tensile properties are roughly the same as those of the base material. The absorbed energy of the joints at present is a little low and further research is needed to increase it. Microstructure of the joints was studied by optical microscope, SEM and TEM. Compositions of the defects on the joining line were analyzed by EDS. Through analysis of the results, optimized parameters for HIP are given. (author)

  19. Concentration of heavy metals in clam Ruditapes decussatus (L) in laguna environment: Mellah Lake (El Kala), Algeria

    International Nuclear Information System (INIS)

    Concentrations of Hg, Pb, Cd, Cu and Zn have been measured in clam samples collected in eastern Algerian coast (El-Kala). Total of 280 samples have been collected between March 1993 and March 1994 at two stations

  20. Intersex in the clam Scrobicularia plana (Da Costa): Widespread occurrence in English Channel estuaries and surrounding areas.

    Science.gov (United States)

    Pope, N D; Childs, K; Dang, C; Davey, M S; O'Hara, S C M; Langston, K; Minier, C; Pascoe, P L; Shortridge, E; Langston, W J

    2015-06-30

    Estuarine clams Scrobicularia plana were sampled from 108 intertidal locations around the English Channel and adjacent areas. Although S. plana is believed to be a strict gonochorist, 58% of the populations sampled included intersexed individuals (described as male clams exhibiting ovotestis). Over the entire region, on average, 8.6% of male clams exhibited intersex, although proportions of affected males ranged from 0% to 53% depending on location. The severity of intersex was assessed using a simple classification scale, with the majority of individuals showing low levels of impact. Sex ratios were significantly skewed at some sites. There were no significant relationships between incidence or severity of intersex; or with size or parasitism of individual clams. Intersex in S. plana is a useful tool to assess endocrine disruptive effects in estuaries, although mechanisms of impact and causative agents remain uncertain. PMID:25837773

  1. Cohort life tables for a population of the soft-shell clam, Mya arenaria L., in the White Sea

    Science.gov (United States)

    Gerasimova, Alexandra V.; Maximovich, Nikolay V.; Filippova, Nadezhda A.

    2015-06-01

    The Mya arenaria generation in the White Sea was observed for almost the whole life cycle (around 25 years). Using the data on this generation dynamics, the cohort life table was built. The main purpose of the research is analysis of age-specific mortality in this soft-shell clam population. The mortality rate was found to change more than tenfold throughout the study period. No regular changes in its value were observed. Periods of low mortality alternated with periods of much higher mortality. Several reasons for the increase in M. arenaria mortality rate during its life cycle are proposed: (a) living in the surface sediment layer at early stages of life cycle (unstable environment, high mortality of non-viable clams, predator impact); (b) intense intraspecific relationships in dense aggregations of young clams; (c) increased intraspecific competition during periods of the rapid individual growth; (d) ageing (clam mortality increases with older age—achievement of an average and a maximum lifespan).

  2. Annual variations of biogenic element contents of manila clam ( Ruditapes philippinarum) bottom-cultivated in Jiaozhou Bay, China

    Science.gov (United States)

    Zan, Xiaoxiao; Xu, Binduo; Zhang, Chongliang; Ren, Yiping

    2014-08-01

    Manila clam ( Ruditapes philippinarum) was monthly sampled from its benthic aquaculture area in Jiaozhou Bay from May 2009 to June 2010. The annual variations of major elemental composition, organic content, fatness and element ratio of Manila clam were examined. The element removal effect of clam farming in Jiaozhou Bay was analyzed based on natural mortality and clam harvest. The results indicated that the variation trend of carbon content in shell ( C shell) was similar to that in clam ( C clam). Such a variation was higher in summer and autumn than in other seasons, which ranged from 9.10 ± 0.13 to 10.38 ± 0.09 mmol g-1 and from 11.28 ± 0.29 to 12.36 ± 0.06 mmol g-1, respectively. Carbon content of flesh ( C flesh) showed an opposite variation trend to that of shell in most months, varying from 29.42 ± 0.05 to 33.64 ± 0.62 mmol g-1. Nitrogen content of shell ( N shell) and flesh ( N flesh) changed seasonally, which was relatively low in spring and summer. N shell and N flesh varied from 0.07 ± 0.009 to 0.14 ± 0.009 mmol g-1 and from 5.46 ± 0.12 to 7.39 ± 0.43 mmol g-1, respectively. Total nitrogen content of clam ranged from 0.50 ± 0.003 to 0.76 ± 0.10 mmol g-1 with a falling tend except for a high value in March 2010. Phosphorus content of clam ( N clam) fluctuated largely, while phosphorus content of shell ( P shell) was less varied than that of flesh ( P flesh). P shell varied from 0.006 ± 0.001 to 0.016 ± 0.001 mmol g-1; while P flesh fluctuated between 0.058 ± 0.017 and 0.293 ± 0.029 mmol g-1. P clam ranged from 0.015 ± 0.002 to 0.041 ± 0.006 mmol g-1. Carbon and nitrogen content were slightly affected by shell length, width or height. Elemental contents were closely related to the reproduction cycle. The removal amounts of carbon, nitrogen and phosphorus from clam harvest and natural death in Jiaozhou Bay were 2.92×104t, 1420 t and 145 t, respectively. The nutrient removal may aid to reduce the concentrations of nitrogen and phosphorus

  3. Giant clams and rising CO2: light may ameliorate effects of ocean acidification on a solar-powered animal

    OpenAIRE

    Sue-Ann Watson

    2015-01-01

    Global climate change and ocean acidification pose a serious threat to marine life. Marine invertebrates are particularly susceptible to ocean acidification, especially highly calcareous taxa such as molluscs, echinoderms and corals. The largest of all bivalve molluscs, giant clams, are already threatened by a variety of local pressures, including overharvesting, and are in decline worldwide. Several giant clam species are listed as 'Vulnerable' on the IUCN Red List of Threatened Species and ...

  4. Frequency, Magnitude, and Possible Causes of Stranding and Mass-Mortality Events of the Beach Clam Tivela mactroides (Bivalvia: Veneridae)

    OpenAIRE

    Alexander Turra; Maíra Pombo; Marcelo Petracco; Eduardo Siegle; Mariana Fonseca; Denadai, Márcia R.

    2016-01-01

    Stranding combined with mass-mortality events of sandy-beach organisms is a frequent but little-understood phenomenon, which is generally studied based on discrete episodes. The frequency, magnitude, and possible causes of stranding and mass-mortality events of the trigonal clam Tivela mactroides were assessed based on censuses of stranded individuals, every four days from September 2007 through December 2008, in Caraguatatuba Bay, southeastern Brazil. Stranded clams were classified as dying ...

  5. Soft-shell clam (Mya arenaria) p53: A structural and functional comparison to human p53

    OpenAIRE

    Holbrook, Lauren A.C.; Butler, Rondi A.; Cashon, Robert E.; Van Beneden, Rebecca J.

    2008-01-01

    The tumor suppressor p53 regulates genes involved in progression through the cell cycle, DNA repair, senescence or apoptosis in response to cell stress. Dysregulation of p53 can result in uncontrolled cellular proliferation. Invertebrate homologues to human p53 (Hsp53) have been identified, including a putative p53 gene (Map53) from the soft-shell clam (Mya arenaria). Predicted sequences for human and clam p53 proteins exhibit conservation in key domains. In light of this similarity, and the ...

  6. One Perkinsus species may hide another: characterization of Perkinsus species present in clam production areas of France

    OpenAIRE

    ARZUL, Isabelle; Chollet, Bruno; Michel, J.; Robert Mill, Hugh; Garcia, Celine; Joly, Jean-pierre; Francois, Cyrille; Miossec, Laurence

    2012-01-01

    Although clam populations in France are known to be infected with protozoans of the genus Perkinsus, no molecular characterization was previously performed on these parasites. Considering that several members of this genus have been associated with mortalities of molluscs worldwide, a study was undertaken in order to characterize these parasites in France. For that purpose, clams, Ruditapes philippinarum and R. decussatus, collected from different production areas and found to be infected wit...

  7. Study on contamination and depuration of clam Scapharca subcrenata in the sea area of Qidong County in Jiangsu Province, China

    OpenAIRE

    Wu, X; Ju, S.

    1992-01-01

    A serious bio-pollution of virus in clam (Arca) broke out in Jiangsu coast water in 1988 winter season. About 400 thousand people were spreaded in Shangai, Jiangsu and Jiangjang provinces. The results of investigation and research showed that this serious event was caused by virus of hepatitis due to eating raw clam (Arca). The ecological and physical and chemistry oceanography investigation in water, intertide zone, sediment were carried out. The virus of hepatitis A was isolated and biossay...

  8. Occurrence and Seasonal Variations of Lipophilic Marine Toxins in Commercial Clam Species along the Coast of Jiangsu, China

    Directory of Open Access Journals (Sweden)

    Xin-Zhi Wang

    2015-12-01

    Full Text Available Recent studies have examined lipophilic marine toxins (LMTs in shellfish and toxic algae worldwide, but the occurrence and seasonal variations of LMTs in commercial clams (including Mactra veneriformis, Ruditapes philippinarum, Meretrix meretrix, and Cyclina sinensis at their major culturing area in Jiangsu, China, remain largely unexplored. In this study, a new solid phase extraction (SPE in combination with an ultra-fast liquid chromatography and triple-quadrupole linear ion trap mass spectrometry (UFLC-TQ-MS method was developed to determine the presence of 10 typical LMTs (okadaic acid (OA, yessotoxins (YTXs, azaspiracids (AZA1-3, pectenotoxins (PTX2, gymnodimine (GYM, dinophysistoxins (DTX1&2, and spirolides (SPX1 in the aforementioned four clam matrices. After confirmation of its sensitivity and precision, this method was used to evaluate the amounts of LMTs in clam samples harvested in five aquaculture zones of the Jiangsu coastal area. Monthly variations of GYM, PTX2, OA, and DTX1&2 in 400 clam samples from the sample areas were determined from January 2014 through August 2015. Peak values were observed during May and August. This is the first systematic report of LMTs detected in clam samples harvested in Jiangsu. Follow-up research and the implementation of protective measures are needed to ensure the safety of clams harvested in this area.

  9. Occurrence and Seasonal Variations of Lipophilic Marine Toxins in Commercial Clam Species along the Coast of Jiangsu, China.

    Science.gov (United States)

    Wang, Xin-Zhi; Cheng, Ying; Li, Na; Wen, Hong-Mei; Liu, Rui; Shan, Chen-Xiao; Chai, Chuan; Wu, Hao

    2016-01-01

    Recent studies have examined lipophilic marine toxins (LMTs) in shellfish and toxic algae worldwide, but the occurrence and seasonal variations of LMTs in commercial clams (including Mactra veneriformis, Ruditapes philippinarum, Meretrix meretrix, and Cyclina sinensis) at their major culturing area in Jiangsu, China, remain largely unexplored. In this study, a new solid phase extraction (SPE) in combination with an ultra-fast liquid chromatography and triple-quadrupole linear ion trap mass spectrometry (UFLC-TQ-MS) method was developed to determine the presence of 10 typical LMTs (okadaic acid (OA), yessotoxins (YTXs), azaspiracids (AZA1-3), pectenotoxins (PTX2), gymnodimine (GYM), dinophysistoxins (DTX1&2), and spirolides (SPX1)) in the aforementioned four clam matrices. After confirmation of its sensitivity and precision, this method was used to evaluate the amounts of LMTs in clam samples harvested in five aquaculture zones of the Jiangsu coastal area. Monthly variations of GYM, PTX2, OA, and DTX1&2 in 400 clam samples from the sample areas were determined from January 2014 through August 2015. Peak values were observed during May and August. This is the first systematic report of LMTs detected in clam samples harvested in Jiangsu. Follow-up research and the implementation of protective measures are needed to ensure the safety of clams harvested in this area. PMID:26712791

  10. Influence of environmental variables on the abundance of estuarine clam Meretrix casta (Chemnitz, 1782 in Trang Province, Southern Thailand

    Directory of Open Access Journals (Sweden)

    Prasert Tongnunui

    2011-02-01

    Full Text Available The estuarine clam Meretrix casta (Chemnitz, 1782 is an edible bivalve that burrows into bottom sediment to protectitself from environmental fluctuations and predation. This study examined the relationship between clam populations andabiotic environmental conditions in order to develop an understanding of the biological and ecological processes that couldbe used to improve their management and exploitation. The study site was located in the estuary of the Palian River, KantangDistrict, Trang Province, on the Andaman coast of Thailand. Six zones were established along the estuary. Data werecollected from January 2008 to December 2008. The results showed that salinity (Sal and concentrations of total suspendedsolids (TSS were the water quality parameters most closely related to population densities of estuarine clams. The combinationof those variables gave the strongest correlation to clam densities (Spearman rank correlation, pw = 0.504. Among bottomsediment parameters, pH and ferrous and ferric iron concentrations gave the strongest correlations to clam densities(Spearman rank correlation, pw = 0.716. The result revealed that the water quality (Sal and TSS and the bottom sediment(pH, ferrous and ferric iron were the main significant parameters influencing the abundance of estuarine clam M. casta.

  11. Size-related and seasonal diet of the manila clam (Ruditapes philippinarum), as determined using dual stable isotopes

    Science.gov (United States)

    Suh, Yeon Jee; Shin, Kyung-Hoon

    2013-12-01

    Stable isotope ratios of lab-cultured Manila clams (Ruditapes philippinarum) and those from natural tidal flats of Seonjae Island in Korea were investigated in terms of their dietary uptake patterns in relation to body size and season. The smallest size group of wild Manila clams revealed significantly depleted δ15N based on the results of a one-way ANOVA. There was significant seasonal change in the proportional contribution of food sources, especially in winter, from benthic particulate organic matter (BPOM) to pelagic particulate organic matter (POM). Laboratory-cultured Manila clams showed growth rates of 6.02-37.75 mm/yr, and smaller-sized clams did not fully utilise the microalgal diets that were provided constantly. Instead, they derived most of their energy from detritus or dead microalgae that had settled on the bottom. Bigger clams, however, exhibited well-balanced source contributions, converting the microalgal diets into biomass. This demonstrates intra-specific differences in the growth rates and preferred diet uptakes of Manila clams, even under similar environmental conditions.

  12. Optimization of hard clams, polychaetes, physical disturbance and denitrifying bacteria of removing nutrients in marine sediment.

    Science.gov (United States)

    Shen, Hui; Thrush, Simon F; Wan, Xihe; Li, Hui; Qiao, Yi; Jiang, Ge; Sun, Ruijian; Wang, LiBao; He, Peimin

    2016-09-15

    Marine organisms are known to play important roles in transforming nutrients in sediments, however, guidelines to optimize sediment restoration are not available. We conducted a laboratory mesocosm experiment to investigate the role of hard clams, polychaetes, the degree of physical disturbance and denitrifying bacterial concentrations in removing total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) in marine sediments. Response surface methodology was employed to analyze the results of initial experiments and in a subsequent experiment identified optimal combinations of parameters. Balancing the TN, TP, TOC removal efficiency, our model predicted 39% TN removal, 33% TP removal, and 42% TOC removal for a 14-day laboratory bioremediation trial using hard clams biomass of 1.2kgm(-2), physical disturbance depth of 16.4cm, bacterial density of 0.18Lm(-2), and polychaetes biomass of 0.16kgm(-2), respectively. These results emphasize the value of combining different species in field-based bioremediation. PMID:27371956

  13. Creep deformation and rupture behavior of CLAM steel at 823 K and 873 K

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Boyu [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Huang, Bo, E-mail: bo.huang@fds.org.cn [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Li, Chunjing; Liu, Shaojun; Xu, Gang [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Zhao, Yanyun; Huang, Qunying [Key Laboratory of Neutronics and Radiation Safety, Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); University of Science and Technology of China, Hefei, Anhui 230027 (China)

    2014-12-15

    China Low Activation Martensitic (CLAM) steel is selected as the candidate structural material in Fusion Design Study (FDS) series fusion reactor conceptual designs. The creep property of CLAM steel has been studied in this paper. Creep tests have been carried out at 823 K and 873 K over a stress range of 150–230 MPa. The creep curves showed three creep regimes, primary creep, steady-state creep and tertiary creep. The relationship between minimum creep rate (ε-dot{sub min}) and the applied stress (σ) could be described by Norton power law, and the stress exponent n was decreased with the increase of the creep temperature. The creep mechanism was analyzed with the fractographes of the rupture specimens which were examined by scanning electron microscopy (SEM). The coarsening of precipitates observed with transmission electron microscope (TEM) indicated the microstructural degradation after creep test.

  14. Creep deformation and rupture behavior of CLAM steel at 823 K and 873 K

    International Nuclear Information System (INIS)

    China Low Activation Martensitic (CLAM) steel is selected as the candidate structural material in Fusion Design Study (FDS) series fusion reactor conceptual designs. The creep property of CLAM steel has been studied in this paper. Creep tests have been carried out at 823 K and 873 K over a stress range of 150–230 MPa. The creep curves showed three creep regimes, primary creep, steady-state creep and tertiary creep. The relationship between minimum creep rate (ε-dotmin) and the applied stress (σ) could be described by Norton power law, and the stress exponent n was decreased with the increase of the creep temperature. The creep mechanism was analyzed with the fractographes of the rupture specimens which were examined by scanning electron microscopy (SEM). The coarsening of precipitates observed with transmission electron microscope (TEM) indicated the microstructural degradation after creep test

  15. Intersex related gene expression profiles in clams Scrobicularia plana: Molecular markers and environmental application.

    Science.gov (United States)

    Ciocan, Corina M; Cubero-Leon, Elena; Langston, William J; Pope, Nick; Cornelius, Keith; Hill, E M; Alvarez-Munoz, Diana; Indiveri, Paolo; Lerebours, Adelaide; Minier, Christophe; Rotchell, Jeanette M

    2015-06-30

    Intersex, the appearance of female characteristics in male gonads, has been identified in several aquatic species. It is a widespread phenomenon in populations of the bivalve, Scrobicularia plana, from the southwest coast of the U.K. Genes previously identified as differentially expressed (ferritin, testicular haploid expressed gene, THEG, proliferating cell nuclear antigen, PCNA; receptor activated protein kinase C, RACK; cytochrome B, CYB; and cytochrome c oxidase 1, COX1) in intersex clams relative to normal male clams, were selected for characterisation and an environmental survey of the Channel region. Transcripts were significantly differentially expressed at sites with varying intersex incidence and contaminant burdens. Significant correlations between specific gene expressions, key contaminants and sampling locations have been identified, though no single gene was associated with intersex incidence. The results highlight the difficulty in understanding the intersex phenomenon in molluscs where there is still a lack of knowledge on the control of normal reproduction. PMID:25746199

  16. Nitrogen stable isotope ratio in the manila clam, Ruditapes philippinarum, reflects eutrophication levels in tidal flats

    International Nuclear Information System (INIS)

    Understanding the effects of anthropogenic eutrophication on coastal fisheries may help in the enhancement of fishery production by effective utilization of sewage effluents, as well as in the consequent reduction of eutrophication. In this study, it was revealed that the nitrogen stable isotope ratio (δ15N) in the soft tissues of the manila clam, Ruditapes philippinarum, can be used as an indicator of anthropogenic eutrophication levels in tidal flat environments by investigation of δ15N in dissolved inorganic nitrogen (DIN), particulate organic matter (POM), sedimentary organic matter (SOM) and soft tissues of the clam in five tidal flats in Japan with different levels of DIN concentration. In addition, it was found that the acid insoluble fraction of the shell organic matrix, conchiolin, can be used as a proxy for the soft tissues in δ15N analyses. This will contribute in easier storage handling and the expansion of chances for sample acquisition.

  17. Nitrogen stable isotope ratio in the manila clam, Ruditapes philippinarum, reflects eutrophication levels in tidal flats.

    Science.gov (United States)

    Watanabe, Satoshi; Kodama, Masashi; Fukuda, Masaaki

    2009-10-01

    Understanding the effects of anthropogenic eutrophication on coastal fisheries may help in the enhancement of fishery production by effective utilization of sewage effluents, as well as in the consequent reduction of eutrophication. In this study, it was revealed that the nitrogen stable isotope ratio (delta(15)N) in the soft tissues of the manila clam, Ruditapes philippinarum, can be used as an indicator of anthropogenic eutrophication levels in tidal flat environments by investigation of delta(15)N in dissolved inorganic nitrogen (DIN), particulate organic matter (POM), sedimentary organic matter (SOM) and soft tissues of the clam in five tidal flats in Japan with different levels of DIN concentration. In addition, it was found that the acid insoluble fraction of the shell organic matrix, conchiolin, can be used as a proxy for the soft tissues in delta(15)N analyses. This will contribute in easier storage handling and the expansion of chances for sample acquisition. PMID:19647270

  18. Heavy metal concentrations in the razor clams (Solen spp.) from Muara Tebas, Sarawak

    International Nuclear Information System (INIS)

    The razor clams (Solen spp) or locally known as ambal in Sarawak collected from Muara Tebas were studied for their heavy metals contents in tissues and shells. Sediment samples were also tested for their metal contents. Concentrations of Pb, Fe, Zn, Cu, Cd and Mn were determined by using Flame Atomic Absorption Spectrophotometer (FAAS). Tissues of razor clams showed highest concentrations of Fe and Zn, while shells accumulated highest concentrations of Pb and Mn. The lowest metal concentrations found were Cu and Cd. In general, the levels of metals in ambal were within the permissible limit recommended by international standard, the Food and Agricultural Organization (FAO). However, the study revealed that the sediments at Muara Tebas fall under the category of slightly polluted (for Pb) when compared to the guidelines suggested by United States Environment Protection Agency (USEPA). (author)

  19. Creep deformation and rupture behavior of CLAM steel at 823 K and 873 K

    Science.gov (United States)

    Zhong, Boyu; Huang, Bo; Li, Chunjing; Liu, Shaojun; Xu, Gang; Zhao, Yanyun; Huang, Qunying

    2014-12-01

    China Low Activation Martensitic (CLAM) steel is selected as the candidate structural material in Fusion Design Study (FDS) series fusion reactor conceptual designs. The creep property of CLAM steel has been studied in this paper. Creep tests have been carried out at 823 K and 873 K over a stress range of 150-230 MPa. The creep curves showed three creep regimes, primary creep, steady-state creep and tertiary creep. The relationship between minimum creep rate (ε˙min) and the applied stress (σ) could be described by Norton power law, and the stress exponent n was decreased with the increase of the creep temperature. The creep mechanism was analyzed with the fractographes of the rupture specimens which were examined by scanning electron microscopy (SEM). The coarsening of precipitates observed with transmission electron microscope (TEM) indicated the microstructural degradation after creep test.

  20. He and H irradiation effects on the nanoindentation hardness of CLAM steel

    International Nuclear Information System (INIS)

    In this study, He and H ion irradiation induced hardening behavior of China Low Activation Martensitic (CLAM) steel was investigated, and the influence of Si on irradiation hardening was also examined. CLAM steel with different Si contents, Heat 0912 and Heat 0408D, were irradiated with single He (He concentration range from 0 to 2150 appm) ion beam and He/H dual ion beams. Then nanoindentation tests were applied to evaluate the ion irradiation induced hardening effect. The result of Heat 0912 showed hardening effect would be more serious with higher He concentration, and the trend saturated when He concentration reach 1000 appm. Comparing the result of Heat 0912 and Heat 0408D, higher Si content might improve the resistance to hardening

  1. He and H irradiation effects on the nanoindentation hardness of CLAM steel

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Siben [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Peng, Lei, E-mail: penglei@ustc.edu.cn [University of Science and Technology of China, Hefei, Anhui 230027 (China); Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Ge, Hongen [University of Science and Technology of China, Hefei, Anhui 230027 (China); Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Huang, Qunying; Xin, Jingping [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Zhao, Ziqiang [State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871 (China)

    2014-12-15

    In this study, He and H ion irradiation induced hardening behavior of China Low Activation Martensitic (CLAM) steel was investigated, and the influence of Si on irradiation hardening was also examined. CLAM steel with different Si contents, Heat 0912 and Heat 0408D, were irradiated with single He (He concentration range from 0 to 2150 appm) ion beam and He/H dual ion beams. Then nanoindentation tests were applied to evaluate the ion irradiation induced hardening effect. The result of Heat 0912 showed hardening effect would be more serious with higher He concentration, and the trend saturated when He concentration reach 1000 appm. Comparing the result of Heat 0912 and Heat 0408D, higher Si content might improve the resistance to hardening.

  2. He and H irradiation effects on the nanoindentation hardness of CLAM steel

    Science.gov (United States)

    Jiang, Siben; Peng, Lei; Ge, Hongen; Huang, Qunying; Xin, Jingping; Zhao, Ziqiang

    2014-12-01

    In this study, He and H ion irradiation induced hardening behavior of China Low Activation Martensitic (CLAM) steel was investigated, and the influence of Si on irradiation hardening was also examined. CLAM steel with different Si contents, Heat 0912 and Heat 0408D, were irradiated with single He (He concentration range from 0 to 2150 appm) ion beam and He/H dual ion beams. Then nanoindentation tests were applied to evaluate the ion irradiation induced hardening effect. The result of Heat 0912 showed hardening effect would be more serious with higher He concentration, and the trend saturated when He concentration reach 1000 appm. Comparing the result of Heat 0912 and Heat 0408D, higher Si content might improve the resistance to hardening.

  3. In vivo exposure of the marine clam Ruditapes philippinarum to zinc oxide nanoparticles: responses in gills, digestive gland and haemolymph.

    Science.gov (United States)

    Marisa, Ilaria; Matozzo, Valerio; Munari, Marco; Binelli, Andrea; Parolini, Marco; Martucci, Alessandro; Franceschinis, Erica; Brianese, Nicola; Marin, Maria Gabriella

    2016-08-01

    Potential nanoparticle (NP) toxicity poses a growing concern in marine coastal environments. Among NPs, zinc oxide nanoparticles (nZnO) are widely used in many common products that ultimately become deposited in coastal habitats from multiple non-point sources. In this study, we evaluated the in vivo effects of nZnO in the clam Ruditapes philippinarum. Animals were exposed to nZnO (1 and 10 μg/L) and ZnCl2 (10 μg/L) for 7 days. ZnCl2 was used to compare the effects of the NPs to those of Zn(2+) and to ascertain whether nZnO toxicity is attributable to the release of ions into the aquatic medium. At differing time intervals during the exposure, several biochemical and cellular responses were evaluated in the clam gills, digestive gland, and haemolymph. The results showed that nZnO, at concentrations close to the predicted environmental levels, significantly affected various parameters in clam tissues. Significant increases in catalase and superoxide dismutase activities and a decreasing trend of glutathione S-transferase activity indicated the involvement of oxidative stress in nZnO toxicity. In clams exposed to ZnCl2, slight variations in antioxidant enzyme activities were detected with respect to nZnO-treated clams. However, no damage to lipids, proteins or DNA was revealed in all exposure conditions, suggesting a protection of antioxidant enzymes in the tissues. Of the various haemolymph parameters measured, haemocyte proliferation increased significantly, in ZnCl2-treated clams in particular. Under nZnO (10 μg/L) and ZnCl2 exposure, DNA damage in haemocytes was also revealed, but it was lower in clams exposed to ZnCl2. A decreasing trend in gill AChE activity of treated clams proposed a possible role of zinc ions in nZnO toxicity. However, the dissimilar modulation of the responses in the nZnO- and ZnCl2-exposed clams suggested different mechanisms of action, with nZnO toxicity possibly depending not only on the release of zinc ions but also on NP

  4. Multi-species generalist predation on the stochastic harvested clam Tivela mactroides (Mollusca, Bivalvia)

    Science.gov (United States)

    Turra, Alexander; Fernandez, Wellington S.; Bessa, Eduardo; Santos, Flavia B.; Denadai, Márcia R.

    2015-12-01

    Top-down control is an important force modulating the abundance of prey and structuring marine communities. The harvested trigonal clam Tivela mactroides is hypothesized to be part of the diet of a variety of marine organisms, with its stock influencing predator abundance and being influenced by them. Here we analyzed the diet of potential predators of T. mactroides in Caraguatatuba Bay, northern coast of São Paulo State, Brazil, to identify the main consumers of this marine resource, and also to address the importance of this clam in the diet of each predator. Samples were taken year-round by trawls; all specimens collected were identified and measured and the food items identified and quantified. Twenty-one species consumed T. mactroides, whose importance in the diet varied greatly in both the volume ingested and the frequency of occurrence (pompano Trachinotus carolinus > blue crab Callinectes danae > starfish Astropecten marginatus). Top-down influence on T. mactroides was also dependent on the abundance of consumers (yellow catfish Cathorops spixii > rake stardrum Stellifer rastrifer > barred grunt Conodon nobilis > A. marginatus). Considering the mean volume ingested, the frequency of occurrence of T. mactroides in the diet, and the relative abundance of consumers, the predators that most influenced T. mactroides were T. carolinus, A. marginatus, and C. danae, in decreasing order. Large numbers of small-sized individuals of T. mactroides (<10 mm) were generally preyed upon by A. marginatus, which may have a stronger effect on clam abundance in comparison to C. danae and T. carolinus, which preyed upon larger clams. In conclusion, the results of this study indicate that predators' consumption of T. mactroides in Caraguatatuba Bay can influence its stocks, mainly due to the type and/or abundance of predator species, the volume and number of individuals of T. mactroides preyed upon, and the temporal variations in the abundance of predators.

  5. Reproductive Cycle of Hard Clam, Meretrix lyrata Sowerby, 1851 (Bivalvia: Veneridae) from Sarawak, Malaysia

    OpenAIRE

    Hamli, Hadi; Idris, Mohd Hanafi; Rajaee, Amy Halimah; Kamal, Abu Hena Mustafa

    2015-01-01

    A study of the reproductive cycle of the hard clam, Meretrix lyrata, was documented based on histological observation and Gonad Index (GI). Samples were taken from estuarine waters of the Buntal River in Sarawak, Malaysia. The gonad of M. lyrata started to develop in September 2013. Gametogenesis continued to develop until the maturation and spawning stage from February to April 2014. The GI pattern for a one-year cycle showed a significant correlation with chlorophyll a. The corresponding GI...

  6. Acute and chronic exposure in mussel (aulacomya ater) and clam (semelle solida) with Cs137

    International Nuclear Information System (INIS)

    Two of the most common Peruvian benthonic molluscs, have been shown to be effective concentrators of Cesium-137 and have also proven useful as indicators of that radionuclide in their natural environment, according with results in this paper. However the clam is a better indicator, when determining environmental acute release of Cesium-137 due to reactor accidents, nuclear tests, accidents in nuclear ships, submarines and radioactive material transport, and the mussel for a continuous monitoring of environmental radio contaminant levels. (author). 11 refs

  7. Interaction of CLAM Steel with Plasma in HT-7 Tokamak During High Parameter Operation

    Institute of Scientific and Technical Information of China (English)

    LI Chunjing; HUANG Qunying; FENG Yan; LI Jiangang; KONG Mingguang

    2007-01-01

    A Plasma Surface Interaction(PSI)experiment on China Low Activation Martensitic(CLAM)steel was done to check if CLAM steel could be used as a Plasma Facing Material (PFM).A specimen with a diameter of 45 mm was exposed to 897 shots of deuterium plasmas with a total duration of 712 sec at a minor radius of 30 cm in HT-7 tokamak.During the exposure experiment,no observable influence Was found on plasma performance.After exposure,the surface of the specimen seemed as smooth as before but with some colour change at the margin of the specimen.Even though some micro-damage,such as dense blisters,melting,splashing,depositions,and dust,Was found on local surfaces with Scanning Electron Microscopic(SEM)observation.The reflectivity of the specimen decreased only slightly.All of these shows CLAM steel has good stability and irradiation resistance.With further optimization,it could possibly be used as the first mirror material for plasma diagnostics in tokamaks.

  8. Di-(2-ethylhexyl phthalate mediates glycolysis and the TCA cycle in clam Venerupis philippinarum

    Directory of Open Access Journals (Sweden)

    C Li

    2014-06-01

    Full Text Available Di-(2-ethylhexyl phthalate (DEHP has many adverse effects on immunity and metabolic states. However, scarce information is available on its connection with toxicologically relevant proteomics response in marine invertebrates. In this study, GS-MS was employed to determine the bio-accumulated levels of DEHP in clam Venerupis philippinarum. After exposure to 0.4 mg L-1 and 4mg L-1 DEHP, the bio-accumulated DEHP in the clam foot was significantly increased in the first 24 h, and then sharply decreased from 0.203 ± 0.022 μg g-1 to 0.104 ± 0.011 μg g-1 , and from 1.689 ± 0.018 μg g-1 to 1.172 ± 0.012 μg g-1, respectively. Comparative proteomic was conducted to investigate the global protein expression changes towards this contaminant exposure. Twenty-eight proteins with significant differences in abundance were identified and characterized, among them six enzymes related to the glycolysis pathway were suppressed, and two members of TCA cycle were induced. The activity and mRNA expression level of malate dehydrogenase (MDH were further assessed using qPCR and an enzymatic assay. The MDH activity and mRNA transcript levels were both elevated compared to those in the ethanol control group. Our findings indicated that a DEHP-treated clam modulated host toxicological effect through depressing glycogen synthesis and activating TCA cycle.

  9. Intersex related gene expression profiles in clams Scrobicularia plana: Molecular markers and environmental application

    International Nuclear Information System (INIS)

    Highlights: • Expression of intersex-related genes was analysed in clam gonads sampled from the Channel. • Genes were differentially expressed at sites with varying levels of intersex and contaminants. • Correlations between gene expressions, key contaminants and sampling sites were identified. • No single gene expression studied correlated with intersex incidence. - Abstract: Intersex, the appearance of female characteristics in male gonads, has been identified in several aquatic species. It is a widespread phenomenon in populations of the bivalve, Scrobicularia plana, from the southwest coast of the U.K. Genes previously identified as differentially expressed (ferritin, testicular haploid expressed gene, THEG, proliferating cell nuclear antigen, PCNA; receptor activated protein kinase C, RACK; cytochrome B, CYB; and cytochrome c oxidase 1, COX1) in intersex clams relative to normal male clams, were selected for characterisation and an environmental survey of the Channel region. Transcripts were significantly differentially expressed at sites with varying intersex incidence and contaminant burdens. Significant correlations between specific gene expressions, key contaminants and sampling locations have been identified, though no single gene was associated with intersex incidence. The results highlight the difficulty in understanding the intersex phenomenon in molluscs where there is still a lack of knowledge on the control of normal reproduction

  10. Irradiation control of pathogenic bacteria and their growth during storage in short neckde clam

    International Nuclear Information System (INIS)

    The growth of pathogenic bacteria during storage and their D10 values by irradiation in short necked clam were evaluated. The results showed that the D10 values of the total bacteria count, E. coli, Vibrio parahaemolyticus in short necked clam at 0 degree C ∼ 4 degree C condition were 0.70, 0.56, 0.20kGy, respectively. The results showed that total bacteria count in vacuum packaged short necked clam sample was 4.46 log (CFU/g) after 3kGy 60Co γ-irradiation and 28 days stored under 0 degree C ∼ 4 degree C, which could meet the requirement of related aquatic product standards, the E. coli and Vibrio parahaemolyticus would not detected after 0.4kGy irradiation and 7 days storage at 0 degree C ∼ 4 degree C. Therefore, micro-organisms could be controled effectively by 3 kGy irradiation and its shelf-life could extend to 28 days. (authors)

  11. Larval and juvenile growth performance of Manila clam hybrids of two full-sib families

    Science.gov (United States)

    Huo, Zhongming; Yan, Xiwu; Zhao, Liqiang; Liang, Jian; Yang, Feng; Zhang, Guofan

    2015-06-01

    In order to determine whether growth performance could be improved by hybridizing full-sib families of Manila clam ( Ruditapes philippinarum), crosses between two full-sib families including self and reciprocal crosses were carried out. The effects of heterosis, combining ability and interaction on the growth of shell length were estimated. The results showed that the growth of hybrid larvae was intermediate between parents on days 6 and 9. Heterosis on shell length was observed, which varied at juvenile stage. The cross of ♂A × ♀B ( Hp varied between 10.41% and 68.27%) displayed larger heterosis than ♂B × ♀A ( Hp varied between 1.89% and 32.33%) did, suggesting that ♂A × ♀B was an ideal hatchery method of improving the growth performance of Manila clam. The variances of general combining ability (GCA), special combining ability (SCA) and interaction (I) were significant in shell length (P Manila clam seeds could be improved by hybridizing selected parents from large numbers of full-sib families.

  12. Giant Clams and Rising CO2: Light May Ameliorate Effects of Ocean Acidification on a Solar-Powered Animal.

    Science.gov (United States)

    Watson, Sue-Ann

    2015-01-01

    Global climate change and ocean acidification pose a serious threat to marine life. Marine invertebrates are particularly susceptible to ocean acidification, especially highly calcareous taxa such as molluscs, echinoderms and corals. The largest of all bivalve molluscs, giant clams, are already threatened by a variety of local pressures, including overharvesting, and are in decline worldwide. Several giant clam species are listed as 'Vulnerable' on the IUCN Red List of Threatened Species and now climate change and ocean acidification pose an additional threat to their conservation. Unlike most other molluscs, giant clams are 'solar-powered' animals containing photosynthetic algal symbionts suggesting that light could influence the effects of ocean acidification on these vulnerable animals. In this study, juvenile fluted giant clams Tridacna squamosa were exposed to three levels of carbon dioxide (CO2) (control ~400, mid ~650 and high ~950 μatm) and light (photosynthetically active radiation 35, 65 and 304 μmol photons m-2 s-1). Elevated CO2 projected for the end of this century (~650 and ~950 μatm) reduced giant clam survival and growth at mid-light levels. However, effects of CO2 on survival were absent at high-light, with 100% survival across all CO2 levels. Effects of CO2 on growth of surviving clams were lessened, but not removed, at high-light levels. Shell growth and total animal mass gain were still reduced at high-CO2. This study demonstrates the potential for light to alleviate effects of ocean acidification on survival and growth in a threatened calcareous marine invertebrate. Managing water quality (e.g. turbidity and sedimentation) in coastal areas to maintain water clarity may help ameliorate some negative effects of ocean acidification on giant clams and potentially other solar-powered calcifiers, such as hard corals. PMID:26083404

  13. Giant Clams and Rising CO2: Light May Ameliorate Effects of Ocean Acidification on a Solar-Powered Animal.

    Directory of Open Access Journals (Sweden)

    Sue-Ann Watson

    Full Text Available Global climate change and ocean acidification pose a serious threat to marine life. Marine invertebrates are particularly susceptible to ocean acidification, especially highly calcareous taxa such as molluscs, echinoderms and corals. The largest of all bivalve molluscs, giant clams, are already threatened by a variety of local pressures, including overharvesting, and are in decline worldwide. Several giant clam species are listed as 'Vulnerable' on the IUCN Red List of Threatened Species and now climate change and ocean acidification pose an additional threat to their conservation. Unlike most other molluscs, giant clams are 'solar-powered' animals containing photosynthetic algal symbionts suggesting that light could influence the effects of ocean acidification on these vulnerable animals. In this study, juvenile fluted giant clams Tridacna squamosa were exposed to three levels of carbon dioxide (CO2 (control ~400, mid ~650 and high ~950 μatm and light (photosynthetically active radiation 35, 65 and 304 μmol photons m-2 s-1. Elevated CO2 projected for the end of this century (~650 and ~950 μatm reduced giant clam survival and growth at mid-light levels. However, effects of CO2 on survival were absent at high-light, with 100% survival across all CO2 levels. Effects of CO2 on growth of surviving clams were lessened, but not removed, at high-light levels. Shell growth and total animal mass gain were still reduced at high-CO2. This study demonstrates the potential for light to alleviate effects of ocean acidification on survival and growth in a threatened calcareous marine invertebrate. Managing water quality (e.g. turbidity and sedimentation in coastal areas to maintain water clarity may help ameliorate some negative effects of ocean acidification on giant clams and potentially other solar-powered calcifiers, such as hard corals.

  14. Recorders of reef environment histories: stable isotopes in corals, giant clams, and calcareous algae

    Science.gov (United States)

    Aharon, Paul

    1991-06-01

    Time-series δ18O and δ13C records from cohabiting massive coral Porites australiensis and giant clam Tridacna gigas from the Great Barrier Reed of Australia, and from calcareous green algae in a core through modern Halimeda bioherm accreting in the eastern Java Sea, provide insights into the complex links between environmental factors and stable isotopes imprinted in these reef skeletal materials. The aragonitic coral and giant clam offer 20 years and 15 years of growth history, respectively. The giant clam yields mean δ18O and δ13C values of-0.5±0.5‰ and 2.2±0.2‰ ( n=67), which agree well with the predicted equilibrium values. The coral yields mean δ18O and δ13C values of-5.6±0.5‰ and-1.8±0.7‰ ( n=84), offering a striking example of kinetic and metabolic fractionation effects. Although both the coral and giant clam harbor symbionts and were exposed to a uniform ambient environment during their growth histories, their distinct isotopic compositions demonstrate dissimilar calcification pathways. The δ18O records contain periodicities corresponding to the alternating annual density bands revealed by X-radiography and optical transmitted light. Attenuation of the δ18O seasonal amplitudes occurring in the giant clam record 8 years after skeletal growth commenced is attributed to a changeover from fast to slow growth rates. Extreme seasonal δ18O amplitudes of up to 2.2‰ discerned in both the coral and giant clam records exceed the equivalent seasonal temperature contrast in the reef environment, and are caused by the combined effect of rainfall and evaporation during the monsoon and dry seasons, respectively. Thus in addition of being useful temperature recorders, reef skeletal material of sufficient longevity, such as Porites and Tridacna, may also indicate rainfall variations. Changing growth rates, determined from the annual growth bands, may exert a primary control on the coral δ13C record which shows a remarkable negative shift of 1.7

  15. Bioaccumulation of polychlorinated biphenyls and metals from contaminated sediment by freshwater prawns, Macrobrachium rosenbergii and clams, Corbicula fluminea

    Energy Technology Data Exchange (ETDEWEB)

    Tatem, H.E.

    1986-02-01

    Freshwater prawns, Macrobrachium rosenbergii, and clams, Corbicula Fluminea, were exposed for 48 or 50 days to three concentrations of a river sediment that contained environmental contaminants such as polychlorinated biphenyls (PCBs) and metals. The PCB sediment bioaccumulation factors (BAF) for prawns ranged from 0.11 to 0.90 for 1242 and 0.20 to 2.40 for 1254, and were highest for animals exposed to 10% sediment. Exposed clams also accumulated PCBs (1242 + 1254) from the sediment. Sediment BAFs for clams were 0.54 to 12.52 and were highest for animals exposed to 10% sediment. Analyses of clams for metals showed lead (Pb) in exposed animals at higher concentrations compared with controls. Bioaccumulation of Pb differed from PCB in that the Pb concentrations did not increase over time and concentrations were higher among animals exposed to 10% sediment compared to animals exposed to 100% sediment. Sediment 11-80 contained 99 mg/kg of Pb while exposed animals, at 48 days, contained approximately 2.2 mg/kg Pb. Analysis of clams for cadmium (Cd) showed exposed animals contained less Cd than controls.

  16. In situ studies with Asian clams (Carbacula fluminea) detect acid mine drainage and nutrient inputs in low-order streams

    International Nuclear Information System (INIS)

    This study evaluates the correlation between transplanted Asiatic clam and indigenous community responses to acid mine drainage and nutrient loading in first-to-third-order streams, by comparing the toxicological endpoints of clam survival and growth with benthic macro-invertebrate community indices as community responses to both acid mine drainage and nutrient loading. Clam survival was found to be positively correlated with water column pH and negatively correlated with conductivity and metal concentrations. There was also a positive correlation with the relative abundance of the macro-invertebrate Ephemeroptera, the most sensitive taxonomic group, to acid mine drainage in this watershed. No correlation was found between clam growth and acid mine drainage inputs, but there was evidence of positive correlation with nitrate concentrations and the relative abundance of collector-filterer functional feeding groups. These results suggest that clam growth is related to nutrient levels and accurately reflect benthic macro-invertebrate responses to nutrient loading. 28 refs., 5 tabs., 1 fig

  17. Purification and Characterization of Hemagglutinating Proteins from Poker-Chip Venus (Meretrix lusoria and Corbicula Clam (Corbicula fluminea

    Directory of Open Access Journals (Sweden)

    Chin-Fu Cheng

    2012-01-01

    Full Text Available Hemagglutinating proteins (HAPs were purified from Poker-chip Venus (Meretrix lusoria and Corbicula clam (Corbicula fluminea using gel-filtration chromatography on a Sephacryl S-300 column. The molecular weights of the HAPs obtained from Poker-chip Venus and Corbicula clam were 358 kDa and 380 kDa, respectively. Purified HAP from Poker-chip Venus yielded two subunits with molecular weights of 26 kDa and 29 kDa. However, only one HAP subunit was purified from Corbicula clam, and its molecular weight was 32 kDa. The two Poker-chip Venus HAPs possessed hemagglutinating ability (HAA for erythrocytes of some vertebrate animal species, especially tilapia. Moreover, HAA of the HAP purified from Poker-chip Venus was higher than that of the HAP of Corbicula clam. Furthermore, Poker-chip Venus HAPs possessed better HAA at a pH higher than 7.0. When the temperature was at 4°C–10°C or the salinity was less than 0.5‰, the two Poker-chip Venus HAPs possessed better HAA compared with that of Corbicula clam.

  18. Filtration and respiration rates of the short-necked clam Paphia undulata (Born, 1778 (Mollusca, Pelecypoda: Veneridae under laboratory conditions

    Directory of Open Access Journals (Sweden)

    Laureen Morillo Manalo

    2010-12-01

    Full Text Available The filtration and respiration rates of various size classes (35-39.99, 40-44.99,45-49.99, 50-54.99 and 55-59.99 mm of the short-necked clam Paphia undulata were measured in the laboratory. The effects of three light regimes (0 lux, 172.22 lux and 645.83 lux, three microalgal species (Isochrysis galbana, Tetraselmis tetrahele and Chaetoceros calcitrans and four microalgal concentrations (10, 25, 50 and 100 x 104 cells ml-1 on filtration rates were investigated. Mean filtration rate was highest (0.57 ± 0.04 Lh-1ind.-1 under total darkness. This can be attributed to the natural environment of this species which is characterized by silty substrate and low visibility. Filtration was also highest in the microalga Isochrysis galbana (0.67 ± 0.05. Rates initially increased from low to moderate microalgal concentrations (25 x 104 cells ml-1 and decreased at higher concentrations. Filtration generally decreased with increase in clam size. Light intensity, microalgal species and microalgal concentration showed significant effects on filtration. Respiration of fed clams was higher (0.138 ± 0.026 ml O2h-1ind.-1 than unfed clams (0.053± 0.025 ml O2h-1 nd.-1 and increased with clam size.

  19. Norovirus recognizes histo-blood group antigens on the gastrointestinal cells of clams, mussels and oysters: a possible mechanism of bio-accumulation

    Science.gov (United States)

    In this study, a set of HBGA-specific monoclonal antibodies (MAbs) was used to detect the expression of HBGA in three oyster species consumed commonly (pacific, virginica, and kumamato), and manila clams, and blue mussels. rNVLPs were applied to plate coated with oyster, mussel or clam GI homogena...

  20. NMR-Based Metabolomic Investigations on the Differential Responses in Adductor Muscles from Two Pedigrees of Manila Clam Ruditapes philippinarum to Cadmium and Zinc

    Directory of Open Access Journals (Sweden)

    Junbao Yu

    2011-09-01

    Full Text Available Manila clam Ruditapes philippinarum is one of the most important economic species in shellfishery in China due to its wide geographic distribution and high tolerance to environmental changes (e.g., salinity, temperature. In addition, Manila clam is a good biomonitor/bioindicator in “Mussel Watch Programs” and marine environmental toxicology. However, there are several pedigrees of R. philippinarum distributed in the marine environment in China. No attention has been paid to the biological differences between various pedigrees of Manila clams, which may introduce undesirable biological variation in toxicology studies. In this study, we applied NMR-based metabolomics to detect the biological differences in two main pedigrees (White and Zebra of R. philippinarum and their differential responses to heavy metal exposures (Cadmium and Zinc using adductor muscle as a target tissue to define one sensitive pedigree of R. philippinarum as biomonitor for heavy metals. Our results indicated that there were significant metabolic differences in adductor muscle tissues between White and Zebra clams, including higher levels of alanine, glutamine, hypotaurine, phosphocholine and homarine in White clam muscles and higher levels of branched chain amino acids (valine, leucine and isoleucine, succinate and 4-aminobutyrate in Zebra clam muscles, respectively. Differential metabolic responses to heavy metals between White and Zebra clams were also found. Overall, we concluded that White pedigree of clam could be a preferable bioindicator/biomonitor in marine toxicology studies and for marine heavy metals based on the relatively high sensitivity to heavy metals.

  1. Evaluation of Using Caged Clams to Monitor Contaminated Groundwater Exposure in the Near-Shore Environment of the Hanford Site 300 Area

    Energy Technology Data Exchange (ETDEWEB)

    Larson, Kyle B.; Poston, Ted M.; Tiller, Brett L.

    2008-01-31

    The Asiatic clam (Corbicula fluminea) has been identified as an indicator species for locating and monitoring contaminated groundwater in the Columbia River. Pacific Northwest National Laboratory conducted a field study to explore the use of caged Asiatic clams to monitor contaminated groundwater upwelling in the 300 Area near-shore environment and assess seasonal differences in uranium uptake in relation to seasonal flow regimes of the Columbia River. Additional objectives included examining the potential effects of uranium accumulation on growth, survival, and tissue condition of the clams. This report documents the field conditions and procedures, laboratory procedures, and statistical analyses used in collecting samples and processing the data. Detailed results are presented and illustrated, followed by a discussion comparing uranium concentrations in Asiatic clams collected at the 300 Area and describing the relationship between river discharge, groundwater indicators, and uranium in clams. Growth and survival, histology, and other sources of environmental variation also are discussed.

  2. Verification of the effect of surface preparation on Hot Isostatic Pressing diffusion bonding joints of CLAM steel

    International Nuclear Information System (INIS)

    Hot Isostatic Pressing (HIP) diffusion bonding with CLAM steel is the primary candidate fabrication technique for the first wall (FW) of DFLL-TBM. Surface state is one of the key factors for the joints quality. The effect of surface state prepared with grinder and miller on HIP diffusion bonding joints of CLAM steel was investigated. HIP diffusion bonding was performed at 140 MPa and 1373 K within 3 h. The mechanical properties of the joints were investigated with instrumented Charpy V-notch impact tests and the microstructures of the joints were analyzed with scanning electron microscopy (SEM). The results showed that the milled samples with fine surface roughness were more suitable for CLAM steel HIP diffusion bonding

  3. Frequency, Magnitude, and Possible Causes of Stranding and Mass-Mortality Events of the Beach Clam Tivela mactroides (Bivalvia: Veneridae).

    Science.gov (United States)

    Turra, Alexander; Pombo, Maíra; Petracco, Marcelo; Siegle, Eduardo; Fonseca, Mariana; Denadai, Márcia R

    2016-01-01

    Stranding combined with mass-mortality events of sandy-beach organisms is a frequent but little-understood phenomenon, which is generally studied based on discrete episodes. The frequency, magnitude, and possible causes of stranding and mass-mortality events of the trigonal clam Tivela mactroides were assessed based on censuses of stranded individuals, every four days from September 2007 through December 2008, in Caraguatatuba Bay, southeastern Brazil. Stranded clams were classified as dying (closed valves did not open when forced) or dead (closed valves were easily opened). Information on wave parameters and the living intertidal clam population was used to assess possible causes of stranding. This fine-scale monitoring showed that stranding occurred widely along the shore and year-round, with peaks interspersed with periods of low or no mortality. Dead clams showed higher mean density than dying individuals, but a lower mean shell length, attributed to a higher tolerance to desiccation of larger individuals. Wave height had a significant negative relationship to the density of dying individuals, presumed to be due to the accretive nature of low-energy waves: when digging out, clams would be more prone to be carried upward and unable to return; while larger waves, breaking farther from the beach and with a stronger backwash, would prevent stranding in the uppermost areas. This ecological finding highlights the need for refined temporal studies on mortality events, in order to understand them more clearly. Last, the similar size structure of stranded clams and the living population indicated that the stranded individuals are from the intertidal or shallow subtidal zone, and reinforces the ecological and behavioral components of this process, which have important ecological and socioeconomic implications for the management of this population. PMID:26745804

  4. Frequency, Magnitude, and Possible Causes of Stranding and Mass-Mortality Events of the Beach Clam Tivela mactroides (Bivalvia: Veneridae.

    Directory of Open Access Journals (Sweden)

    Alexander Turra

    Full Text Available Stranding combined with mass-mortality events of sandy-beach organisms is a frequent but little-understood phenomenon, which is generally studied based on discrete episodes. The frequency, magnitude, and possible causes of stranding and mass-mortality events of the trigonal clam Tivela mactroides were assessed based on censuses of stranded individuals, every four days from September 2007 through December 2008, in Caraguatatuba Bay, southeastern Brazil. Stranded clams were classified as dying (closed valves did not open when forced or dead (closed valves were easily opened. Information on wave parameters and the living intertidal clam population was used to assess possible causes of stranding. This fine-scale monitoring showed that stranding occurred widely along the shore and year-round, with peaks interspersed with periods of low or no mortality. Dead clams showed higher mean density than dying individuals, but a lower mean shell length, attributed to a higher tolerance to desiccation of larger individuals. Wave height had a significant negative relationship to the density of dying individuals, presumed to be due to the accretive nature of low-energy waves: when digging out, clams would be more prone to be carried upward and unable to return; while larger waves, breaking farther from the beach and with a stronger backwash, would prevent stranding in the uppermost areas. This ecological finding highlights the need for refined temporal studies on mortality events, in order to understand them more clearly. Last, the similar size structure of stranded clams and the living population indicated that the stranded individuals are from the intertidal or shallow subtidal zone, and reinforces the ecological and behavioral components of this process, which have important ecological and socioeconomic implications for the management of this population.

  5. The endocrine-disrupting effect and other physiological responses of municipal effluent on the clam Ruditapes decussatus.

    Science.gov (United States)

    Mezghani-Chaari, Sawssan; Machreki-Ajmi, Monia; Tremolet, Gauthier; Kellner, Kristell; Geffard, Alain; Minier, Christophe; Hamza-Chaffai, Amel

    2015-12-01

    In order to document the potential endocrine disrupting and toxic effect of the municipal wastewater effluents discharged into the Sfax coastal area (South of Tunisia), specimens of clam R. decussatus were collected from a reference site and were in vivo exposed to treated sewage effluent for 30 days. To this end, estrogenic and androgenic activities were measured in the gills to assess potential accumulation and regulation of active compounds. After effluent exposure androgenic activity in organic extracts increased up to fivefold compared to controls and remained elevated, while estrogenic activity was not significantly affected by exposure. As a consequence, remarkable disruptions in the gametogenesis activity, glycogen content, and Vitellogenin-like protein levels in male clams were observed. A parallel analysis of heavy metals in clam tissues was determined. A significant uptake of Ni, Zn, and Pb in soft tissues of exposed clams was observed. The significant increase of malondialdehyde (MDA) concentrations as a function of exposure time implies that clams have been exposed to an oxidative stress probably due to the presence of high metal concentrations in sewage effluent. Correlation analysis has revealed a statistically significant and positive relationship between MDA levels and metal concentrations in clams' tissues. The acetylcholinesterase activity was not significantly affected by exposure. Altogether, these results showed that a short-term exposure to a mixture of chemical compounds released by the Sfax wastewater treatment plant induce adverse physiological and reproductive effects in R. decussatus. Further studies are underway in order to evaluate its long-term impacts on aquatic wildlife in the gulf of Gabes area. PMID:26278908

  6. Size-dependent effects of low level cadmium and zinc exposure on the metabolome of the Asian clam, Corbicula fluminea

    Energy Technology Data Exchange (ETDEWEB)

    Spann, Nicole, E-mail: nicole.spann@web.de [Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ (United Kingdom); Aldridge, David C., E-mail: da113@cam.ac.uk [Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ (United Kingdom); Griffin, Julian L., E-mail: jlg40@mole.bio.cam.ac.uk [Sanger Building, Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA (United Kingdom); Jones, Oliver A.H., E-mail: o.jones@gmail.com [Sanger Building, Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA (United Kingdom)

    2011-10-15

    Highlights: Small and large Corbicula fluminea were exposed to cadmium and zinc spiked sediment. Metabolomic changes in the freshwater clams were determined by NMR and GC-MS. Metabolic perturbations were related to amino acid and energy related metabolism. Small and large clams were differentiated by their metabolic composition. Size classes showed opposite responses to metal stress. - Abstract: The toxic effects of low level metal contamination in sediments are currently poorly understood. We exposed different sized Asian clams, Corbicula fluminea, to sediment spiked with environmentally relevant concentrations of either zinc, cadmium or a zinc-cadmium mixture for one week. This freshwater bivalve is well suited for sediment toxicity tests as it lives partly buried in the sediment and utilises sediment particles as a food resource. After one week, the whole tissue composition of low molecular weight metabolites was analysed by nuclear magnetic resonance spectroscopy (NMR) and gas chromatography-mass spectrometry (GC-MS). The condition index (ratio of tissue dry weight to volume inside the shell valves) was also measured. Small and large clams were clearly differentiated by their metabolic composition and the two size classes showed opposite responses to the mixture spiked sediment. No effects of zinc alone on the metabolome were found and cadmium only influenced the smaller size class. The main perturbations were seen in amino acid and energy metabolism, with small clams using amino acids as an energy resource and larger clams primarily drawing on their larger storage reserves of carbohydrates. Our study demonstrates that metabolomics is a useful technique to test for low level toxicity which does not manifest in mortality or condition index changes. The differing effects between the two size classes stress that it is important to consider age/size when conducting metabolomic and ecotoxicology assessments, since testing for the effects on only one size class makes

  7. Impact of cadmium contamination and oxygenation levels on biochemical responses in the Asiatic clam Corbicula fluminea

    International Nuclear Information System (INIS)

    The aim of this work was to evaluate the potential utility of several biochemical parameters as indicators of the toxic effects of cadmium in the freshwater clam Corbicula fluminea under two levels of oxygenation (normoxia 21 kPa and hypoxia 4 kPa). These variations in oxygenation are representative of the natural environments of bivalves living at the bottom of the water column, where hypoxic episodes may occur regularly. Cadmium accumulation, metallothionein synthesis, MXR protein induction, lipoperoxidation and antioxidant enzyme activities (catalase, glutathione reductase and total and selenium-dependent glutathione peroxidases) were assessed in the gills of C. fluminea in four experimental conditions: normoxia, hypoxia, normoxia with cadmium and hypoxia with cadmium ([Cd] = 30 μg l-1) over a 14-day period. Behavioural reactions were also followed for the duration of the experiment by monitoring clam activity and valve movements. This study is a first report on biochemical responses under cadmium contamination and hypoxia and will enable us to determine better biomarkers for C. fluminea as they were measured simultaneously. In metal-exposed animals, we found an increasing accumulation of cadmium in the gills with time, and this was more severe in hypoxic conditions. Metallothionein synthesis occurred in contaminated clams and was precocious in hypoxic conditions. MXR protein induction appeared promising due to its quick and significant response to metal with a strong impact from hypoxic contamination. On the other hand, in our experimental conditions, antioxidant parameters did not show decisive responses to contamination and hypoxia, except glutathione peroxidases which decreased systematically with time in a cadmium-independent manner. Lipid peroxidation, expressed as malondialdehyde content, was not stimulated by normoxic contamination, as has been shown in other studies, but was stimulated under hypoxic cadmium contamination. Our study confirms the

  8. Parasites as possible cause of mass mortalities of the critically endangered clam Mesodesma mactroides on the Atlantic coast of Argentina

    OpenAIRE

    Cremonte, Florencia; Figueras, Antonio

    2004-01-01

    A survey of the health status of the yellow clam Mesodesma mactroides was performed to contribute to establish the causes of mass mortality episodes. A sample of 32 clams was collected from Isla del Jabalí (40°32’S- 62°21’W, Buenos Aires province, Argentina), a relict population by 1999, that two years later suffered a mass mortality. Microscopical examination of the histological sections revealed the presence of four parasitic or commensal taxa: Trichodina sp. ciliates, coccidian...

  9. Effects of burial by the disposal of dredged materials from the Columbia River on Pacific razor clams (Siliqua patula)

    Energy Technology Data Exchange (ETDEWEB)

    Vavrinec, John; Kohn, Nancy P.; Hall, Kathleen D.; Romano, Brett A.

    2007-05-07

    Annual maintenance of the Columbia River navigation channel requires the U.S. Army Corps of Engineers (Corps) to dredge sediment from the river and dispose of the sediment in coastal areas at the mouth of the Columbia River. Some of these disposal areas can be as shallow as 12 m deep in waters off the coastal beaches, and dredged material disposal activities have therefore raised concerns of impacts to local razor clam (Siliqua patula) populations that are prevalent in the area. The Corps’ Portland District requested that the Marine Sciences Laboratory of the U.S. Department of Energy’s Pacific Northwest National Laboratory conduct laboratory experiments to evaluate the potential impacts of burial by dredged material to razor clams during disposal. Prior modeling of disposal events indicates three stresses that could have an impact on benthic invertebrates: convective descent and bottom encounter (compression forces due to bottom impact), dynamic collapse and spreading (surge as material washes over the bottom), and mounding (burial by material). Because the razor clam is infaunal, the effects of the first two components should be minimal, because the clams should be protected by substrate that is not eroded in the event and by the clams’ rapid digging capabilities. The mound resulting from the disposal, however, would bury any clams remaining in the footprint under as much as 12 cm of new sediment according to modeling, and the clams’ reaction to such an event and to burial is not known. Although the literature suggests that razor clams may be negatively affected by siltation and therefore perhaps by dredging and disposal activity, as well, impacts of this type have not been demonstrated. The primary purpose of this study was to evaluate the potential impacts of dredge material disposal on adult subtidal razor clam populations at the mouth of the Columbia River. Using the parameters defined in a previous model, a laboratory study was created in which a

  10. Manila clams from Hg polluted sediments of Marano and Grado lagoons (Italy) harbor detoxifying Hg resistant bacteria in soft tissues

    International Nuclear Information System (INIS)

    A mechanism of mercury detoxification has been suggested by a previous study on Hg bioaccumulation in Manila clams (Ruditapes philippinarum) in the polluted Marano and Grado lagoons and in this study we demonstrate that this event could be partly related to the detoxifying activities of Hg-resistant bacteria (MRB) harbored in clam soft tissues. Therefore, natural clams were collected in six stations during two different periods (winter and spring) from Marano and Grado Lagoons. Siphons, gills and hepatopancreas from acclimatized clams were sterile dissected to isolate MRB. These anatomical parts were glass homogenized or used for whole, and they were lying on a solid medium containing 5 mg l−1 HgCl2 and incubated at 30 °C. A total of fourteen bacterial strains were isolated and were identified by 16S rDNA sequencing and analysis, revealing that strains were representative of eight bacterial genera, four of which were Gram-positive (Enterococcus, Bacillus, Jeotgalicoccus and Staphylococcus) and other four were Gram-negative (Stenotrophomonas, Vibrio, Raoultella and Enterobacter). Plasmids and merA genes were found and their sequences determined. Fluorescence in situ hybridization (FISH) technique shows the presence of Firmicutes, Actinobacteria and Gammaproteobacteria by using different molecular probes in siphon and gills. Bacterial clumps inside clam flesh were observed and even a Gram-negative endosymbiont was disclosed by transmission electronic microscope inside clam cells. Bacteria harbored in cavities of soft tissue have mercury detoxifying activity. This feature was confirmed by the determination of mercuric reductase in glass-homogenized siphons and gills. -- Highlights: ► We isolated Gram-positive and Gram-negative Hg resistant strains from soft tissues of Ruditapes philippinarum. ► We identify 14 mercury resistant strains by 16S rRNA gene sequences. ► Bacteria in siphon and gill tissues of clams were observed by TEM and identified with different

  11. Oxidative DNA damage levels and catalase activity in the clam Ruditapes decussatus as pollution biomarkers of Tunisian marine environment.

    Science.gov (United States)

    Jebali, Jamel; Banni, Mohamed; de Almeida, Eduardo Alves; Boussetta, Hamadi

    2007-01-01

    Levels of the oxidative DNA damage 7, 8-dihydro-8-oxo-2'-deoxyguanosine (8-oxodG) and catalase (CAT) activity were measured in the digestive gland and gills of clams Ruditapes decussatus, related to the presence of pollutants along Tunisian marine environment. Increased levels of CAT were observed in tissues of clams from all the sites studied, compared to control values, and elevated 8-oxodG levels were observed at specific sites. Results obtained in this work indicate that the measurement of 8-oxodG levels and CAT activity in tissues of R. decussatus is promising in pollution monitoring studies of the Tunisian marine environment. PMID:16897518

  12. Manila clams from Hg polluted sediments of Marano and Grado lagoons (Italy) harbor detoxifying Hg resistant bacteria in soft tissues

    Energy Technology Data Exchange (ETDEWEB)

    Baldi, Franco, E-mail: baldi@unive.it [Dipartimento di Scienze Molecolari e Nanosistemi, Cà Foscari University of Venice, Dorsoduro 2137, 30123 Venice (Italy); Gallo, Michele; Marchetto, Davide [Dipartimento di Scienze Molecolari e Nanosistemi, Cà Foscari University of Venice, Dorsoduro 2137, 30123 Venice (Italy); Faleri, Claudia [Department of Environmental Science ‘G. Sarfatti’, University of Siena, 53100 Siena (Italy); Maida, Isabel; Fani, Renato [Dipartimento di Biologia Evoluzionistica, Via Romana, 17, University of Florence, 50125 Florence (Italy)

    2013-08-15

    A mechanism of mercury detoxification has been suggested by a previous study on Hg bioaccumulation in Manila clams (Ruditapes philippinarum) in the polluted Marano and Grado lagoons and in this study we demonstrate that this event could be partly related to the detoxifying activities of Hg-resistant bacteria (MRB) harbored in clam soft tissues. Therefore, natural clams were collected in six stations during two different periods (winter and spring) from Marano and Grado Lagoons. Siphons, gills and hepatopancreas from acclimatized clams were sterile dissected to isolate MRB. These anatomical parts were glass homogenized or used for whole, and they were lying on a solid medium containing 5 mg l{sup −1} HgCl{sub 2} and incubated at 30 °C. A total of fourteen bacterial strains were isolated and were identified by 16S rDNA sequencing and analysis, revealing that strains were representative of eight bacterial genera, four of which were Gram-positive (Enterococcus, Bacillus, Jeotgalicoccus and Staphylococcus) and other four were Gram-negative (Stenotrophomonas, Vibrio, Raoultella and Enterobacter). Plasmids and merA genes were found and their sequences determined. Fluorescence in situ hybridization (FISH) technique shows the presence of Firmicutes, Actinobacteria and Gammaproteobacteria by using different molecular probes in siphon and gills. Bacterial clumps inside clam flesh were observed and even a Gram-negative endosymbiont was disclosed by transmission electronic microscope inside clam cells. Bacteria harbored in cavities of soft tissue have mercury detoxifying activity. This feature was confirmed by the determination of mercuric reductase in glass-homogenized siphons and gills. -- Highlights: ► We isolated Gram-positive and Gram-negative Hg resistant strains from soft tissues of Ruditapes philippinarum. ► We identify 14 mercury resistant strains by 16S rRNA gene sequences. ► Bacteria in siphon and gill tissues of clams were observed by TEM and identified

  13. Development and application of a new material for control of asiatic clams

    Energy Technology Data Exchange (ETDEWEB)

    Lyons, L.A.; Austin, D.M.; Post, R.M.; McClellan, E.

    1988-01-01

    Asiatic-clam-related macrofouling has been estimated to cost US industry more than $1 billion annually. These costs are related flow restrictions, reduced cooling efficiency, maintenance expenses, replacement of damaged equipment, and forced outages. The vulnerability of fire protection systems and safety-related systems in nuclear-fueled generating stations has aroused special concerns. In the spring of 1987, Philadelphia Electric was approached by Betz Laboratories to consider an application of their recently developed molluscicide at the Peach Bottom Atomic Station. The molluscicide was first applied in December 1987 to the high-pressure service water systems. Results are summarized.

  14. Development and application of a new material for control of asiatic clams

    International Nuclear Information System (INIS)

    Asiatic-clam-related macrofouling has been estimated to cost US industry more than $1 billion annually. These costs are related flow restrictions, reduced cooling efficiency, maintenance expenses, replacement of damaged equipment, and forced outages. The vulnerability of fire protection systems and safety-related systems in nuclear-fueled generating stations has aroused special concerns. In the spring of 1987, Philadelphia Electric was approached by Betz Laboratories to consider an application of their recently developed molluscicide at the Peach Bottom Atomic Station. The molluscicide was first applied in December 1987 to the high-pressure service water systems. Results are summarized

  15. Expression of cyp1a protein in the freshwater clam Corbicula fluminea (Müller

    Directory of Open Access Journals (Sweden)

    Vranković Jelena

    2011-01-01

    Full Text Available We investigated the expression of CYP1A in the foot, gill and visceral mass of the freshwater clam Corbicula fluminea in relation to polychlorinated biphenyls (PCBs exposure. Different PCBs congeners were found in the foot and visceral mass, while the expression of CYP1A was observed only in the visceral mass. However the level of CYP1A expression in the visceral mass was not related to the level of PCBs present in the tissue. Our results indicate a higher rate of biotransformation and lower threshold of CYP1A induction in the visceral mass compared with other tissues.

  16. ALAM/CLAM and some applications of computer algebra systems to problems in general relativity

    International Nuclear Information System (INIS)

    This paper is divided into three parts. Part A presents a historical survey of the development of the system, a brief description of its features and, finally, a critical assessment. ALAM and CLAM have been used in many problems in General Relativity; the vast majority of these belong to a set of standard calculations termed ''metric applications''. However, four large non-standard applications have been attempted successfully and these are described in Part B. CAMAL is the only other system which has been used extensively for work in relativity. CAMAL has played an important role in two research projects and details of these are given in Part C

  17. Contaminant assessment of fish, rangia clams, and sediments in the lower Pamlico River, North Carolina

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-10-01

    Samples of sediment, rangia clams (Rangia cuneata), gizzard shad (Dorosoma cepedianum), and longnose gar (Lepisosteus osseus) were collected from five sites in the lower Pamlico River and analyzed for elemental contaminants, organochlorines, aliphatic hydrocarbons, and polynuclear aromatic hydrocarbons. Most sample concentrations were either beneath the detection limit or too low to be associated with biological impacts. However, sediment sample concentrations of cadmium and fluoride were observed at levels that could be associated with biological impacts at one of the sites which was located near the discharge from a large phosphate mining operation.

  18. Determination of multiple toxins in whelk and clam samples collected from the Chukchi and Bering seas.

    Science.gov (United States)

    Li, Aifeng; Chen, Huidan; Qiu, Jiangbing; Lin, Heshan; Gu, Haifeng

    2016-01-01

    Buccinidae whelk Neptunea varicifera (Dall), Cardiidae clam Serripes laperousii (Deshayes), and two unknown species of whelk and clam were collected from the Arctic Chukchi Sea and sub-Arctic Bering Sea in July 2014. In this study, the mollusk samples were analyzed by different liquid chromatography-tandem quadrupole mass spectrometry (LC-MS/MS) methods for multiple shellfish toxins, including okadaic acid (OA), pectenotoxin (PTX), yessotoxin (YTX), azaspiracid (AZA), cyclic imines (CI), and saxitoxin (STX) groups. PTX2 (≈2.0 μg kg(-1) whole tissues) was detected exclusively in the clam S. laperousii collected from the Chukchi Sea. OA and dinophysistoxin-1 (DTX1) were restricted to mollusk samples collected from the Bering Sea, and OA was the dominant component of the whelk N. varicifera (63 μg kg(-1) digestive gland) and an unknown species of whelk (6.8 μg kg(-1) digestive gland). Spirolide-1 (SPX1) was confirmed in most samples except for the whelk N. varicifera collected from the Bering Sea. The highest content of SPX1 (≈18.5 μg kg(-1) digestive gland) occurred in the whelk N. varicifera collected from the Chukchi Sea, along with the suspected presence of SPX-C, SPX-D and didesMe-SPX-C. YTX, as well as its derivatives 45-OH-YTX and 45,46,47-Trinor-YTX, were found in all samples, with the highest YTX content (66 μg kg(-1) digestive gland) present in the whelk N. varicifera collected from the Chukchi Sea. Interestingly, STX and dcSTX were measured only in the whelk N. varicifera and unknown species of clam collected from the Chukchi Sea. No AZA-group toxins, gymnodimine (GYM), or pinnatoxin G were found in any samples analyzed. Results demonstrated that the mollusk samples were contaminated by multiple shellfish toxins in the Chukchi and Bering seas. This study highlights the need to monitor potentially toxic microalgae in the Arctic and sub-Arctic regions, as well as species of mollusk that may be included in future commercial or

  19. Characterisation of the mantle transcriptome and biomineralisation genes in the blunt-gaper clam, Mya truncata.

    Science.gov (United States)

    Sleight, Victoria A; Thorne, Michael A S; Peck, Lloyd S; Arivalagan, Jaison; Berland, Sophie; Marie, Arul; Clark, Melody S

    2016-06-01

    Members of the Myidae family are ecologically and economically important, but there is currently very little molecular data on these species. The present study sequenced and assembled the mantle transcriptome of Mya truncata from the North West coast of Scotland and identified candidate biomineralisation genes. RNA-Seq reads were assembled to create 20,106 contigs in a de novo transciptome, 18.81% of which were assigned putative functions using BLAST sequence similarity searching (cuttoff E-value 1E-10). The most highly expressed genes were compared to the Antarctic clam (Laternula elliptica) and showed that many of the dominant biological functions (muscle contraction, energy production, biomineralisation) in the mantle were conserved. There were however, differences in the constitutive expression of heat shock proteins, which were possibly due to the M. truncata sampling location being at a relatively low latitude, and hence relatively warm, in terms of the global distribution of the species. Phylogenetic analyses of the Tyrosinase proteins from M. truncata showed a gene expansion which was absent in L. elliptica. The tissue distribution expression patterns of putative biomineralisation genes were investigated using quantitative PCR, all genes showed a mantle specific expression pattern supporting their hypothesised role in shell secretion. The present study provides some preliminary insights into how clams from different environments - temperate versus polar - build their shells. In addition, the transcriptome data provides a valuable resource for future comparative studies investigating biomineralisation. PMID:26777791

  20. Tensile properties and fracturing behavior of weld joints in the CLAM at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Yucheng [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Xiao, Chengwen, E-mail: emoryxiao@163.com [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Wang, Xu; Yue, Jiajia; Zhu, Qiang [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-06-15

    Highlights: • We use the stress triaxiality theory to explain the plastic deformation and facture behavior of the joints during the short term tensile tests at high temperature. • The tensile strength of CLAM welded joint at high temperature is lower compared with that at room temperature. • We explained the formation of crack and the reason of fracture. - Abstract: The tensile properties and fracturing behavior of weld joints in the Chinese low activation martensitic steel (CLAM) at high temperatures were studied. The result revealed that the cracks of weld joints in the base metal would appear in the heat-affected zone, after post-weld heat treatment for the high-temperature tensile test. The microstructure in the fractured frontier had different deformation and directions, and the fractured surface had different angles, a result associating with the normal faulting and shear fracturing. The tri-axial theory of stress can well explain the deformation and fracturing behavior of weld joints in the high-temperature tensile.

  1. Tensile properties and fracturing behavior of weld joints in the CLAM at high temperatures

    International Nuclear Information System (INIS)

    Highlights: • We use the stress triaxiality theory to explain the plastic deformation and facture behavior of the joints during the short term tensile tests at high temperature. • The tensile strength of CLAM welded joint at high temperature is lower compared with that at room temperature. • We explained the formation of crack and the reason of fracture. - Abstract: The tensile properties and fracturing behavior of weld joints in the Chinese low activation martensitic steel (CLAM) at high temperatures were studied. The result revealed that the cracks of weld joints in the base metal would appear in the heat-affected zone, after post-weld heat treatment for the high-temperature tensile test. The microstructure in the fractured frontier had different deformation and directions, and the fractured surface had different angles, a result associating with the normal faulting and shear fracturing. The tri-axial theory of stress can well explain the deformation and fracturing behavior of weld joints in the high-temperature tensile

  2. Population dynamics of the freshwater clam Galatea paradoxa from the Volta River, Ghana

    Directory of Open Access Journals (Sweden)

    Adjei-Boateng D.

    2012-07-01

    Full Text Available Population parameters such as asymptotic (L∞, growth coefficient (K, mortality rates (Z,F and M, exploitation level (E and recruitment pattern of the freshwater clam Galatea paradoxa were estimated using length-frequency data from the Volta River estuary, Ghana. The L∞ for G. paradoxa at the Volta estuary was 105.7 mm, the growth coefficient (K and the growth performance index (Ǿ ranged between 0.14–0.18 year-1 and 3.108–3.192, respectively. Total mortality (Z was 0.65–0.82 year-1, while natural mortality (M and fishing mortality (F were 0.35–0.44 year-1 and 0.21–0.47 year-1, respectively, with an exploitation level of 0.32–0.57. The recruitment pattern suggested that G. paradoxa has year-round recruitment with a single pulse over an extended period (October–March in the Volta River. The Volta River stock of G. paradoxa is overfished and requires immediate action to conserve it. This can be achieved by implementing a minimum landing size restriction and intensifying the culture of smaller clams which is a traditional activity at the estuary.

  3. Fishery of the short-necked clam Paphia undulata in Southern Negros Occidental, Central Philippines

    Directory of Open Access Journals (Sweden)

    Karen A. Villarta

    2010-06-01

    Full Text Available This study documents the fishery of the short-necked clam Paphia undulata in coastal waters of southern Negros Occidental. Catch and effort estimates were determined based on daily records of compressor divers gathered between February-July 2008 in Himamaylan City and July 2008-May 2009 in the town of Hinigaran. Fishing and marketing practices in both areas were also documented and population biology information noted.Compared to earlier conditions, present fishing patterns show a worsened stage of overexploitation primarily characterized by collection of predominantly small and immature (mostly <45 mm shell lengths sizes. Intensity/duration and location of fishing also varied due to both abundance and demand factors.The difference in sizes of clams and the varying fishing durations in each area suggest a non-uniform pattern of settlement resulting most likely from differential larval recruitment, the likely factors causing the local boom and bust fishery. The larger and long term extent of the effect of these factors can only be further investigated by parallel 2-3 year fishery-dependent and -independent surveys

  4. Zoosporulation of a new Perkinsus species isolated from the gills of the softshell clam Mya arenaria

    Directory of Open Access Journals (Sweden)

    Mclaughlin S.M.

    2000-06-01

    Full Text Available A gill-associated Perkinsus sp. isolated from the softshell clam (Mya arenaria is described as a new species, P. chesapeaki sp. nov. Examination of the parasite in seawater cultures revealed life cycle stages and zoosporulation processes similar to those described for other species of the genus Perkinsus. Prezoosporangia developed thickened cell walls upon contraction of the cytoplasm and development of a distinctive clear area between the cell wall and the protoplast. Successive bipartition of the protoplast led to the formation of hundred's of zoospores within mature sporangia. Zoospores were released into seawater through one or more discharge tubes. Ultrastructural studies revealed an oblong zoospore possessing two flagella that arose from a concave side located in the upper third of the zoospore body. The anterior flagellum possessed a unilateral array of hair-like structures. A large anterior vacuole and basolateral nucleus dominated the cytoplasm of the zoospore body. The presence of a rudimentary apical complex including on open-sided conoid, rhoptries, micronemes, and subpellicular microtubules were also discerned. Differences in zoospore morphology, and sequence analyses of two genes previously reported, support the designation of the gill-associated Perkinsus from the softshell clam as a new species

  5. Online detection of waterborne bioavailable copper by valve daily rhythms in freshwater clam Corbicula fluminea.

    Science.gov (United States)

    Jou, L J; Chen, W Y; Liao, C M

    2009-08-01

    Freshwater clam Corbicula fluminea, a surrogate species in metal toxicity testing, is a promising bioindicator of impairment in aquatic ecosystems. Little is known, however, about the relationship between clam valve daily rhythmic response and metal bioavailability related to a metal biological early warning system (BEWS) design. The purpose of this study was to link biotic ligand model (BLM)-based bioavailability and valve daily rhythm in C. fluminea to design a biomonitoring system for online in situ detection of waterborne copper (Cu). We integrated the Hill-based dose-time-response function and the fitted daily rhythm function of valve closure into a constructed programmatic mechanism. The functional presentation of the present dynamic system was completely demonstrated by employing a LabVIEW graphic control program in a personal computer. We used site-specific effect concentration causing 10% of total valve closure response (EC10) as the detection threshold to implement the proposed C. fluminea-based Cu BEWS. Here our results show that the proposed C. fluminea-based BEWS could be deliberately synthesized to online in situ transmit rapidly the information on waterborne bioavailable Cu levels under various aquatic environmental conditions through monitoring the valve daily rhythmic changes. We suggested that the developed C. fluminea-based dynamic biomonitoring system could assist in developing technically defensible site-specific water quality criteria to promote more efficient uses in water resources for protection of species health in aquatic environments. PMID:18607762

  6. Real-Time Mesoscale Forecast Support During the CLAMS Field Campaign

    Institute of Scientific and Technical Information of China (English)

    WANG Donghai; P. MINNIS; T. P. CHARLOCK; D. K. ZHOU; F. G. ROSE; W. L. SMITH; W. L. SMITH Jr.; L. NGUYEN

    2007-01-01

    This paper reports the use of a specialized, mesoscale, numerical weather prediction (NWP) system and a satellite imaging and prediction system that were set up to support the CLAMS (Chesapeake Lighthouse and Aircraft Measurements for Satellites) field campaign during the summer of 2001. The primary objective of CLAMS was to validate satellite-based retrievals of aerosol properties and vertical profiles of the radiative flux, temperature and water vapor. Six research aircraft were deployed to make detailed coincident measurements of the atmosphere and ocean surface with the research satellites that orbited overhead. The mesoscale weather modeling system runs in real-time to provide high spatial and temporal resolution for forecasts that are delivered via the World Wide Web along with a variety of satellite imagery and satellite location predictions. This system is a multi-purpose modeling system capable of both data analysis/assimilation and multi-scale NWP ranging from cloud-scale to larger than regional scale. This is a three-dimensional, nonhydrostatic compressible model in a terrain-following coordinate. The model employs advanced numerical techniques and contains detailed interactive physical processes. The utility of the forecasting system is illustrated throughout the discussion on the impact of the surface-wind forecast on BRDF (Bidirectional Reflectance Distribution Function) and the description of the cloud/moisture forecast versus the aircraft measurement.

  7. Development of molecular resources for an intertidal clam, Sinonovacula constricta, using 454 transcriptome sequencing.

    Directory of Open Access Journals (Sweden)

    Donghong Niu

    Full Text Available BACKGROUND: The razor clam Sinonovacula constricta is a benthic intertidal bivalve species with important commercial value. Despite its economic importance, knowledge of its transcriptome is scarce. Next generation sequencing technologies offer rapid and efficient tools for generating large numbers of sequences, which can be used to characterize the transcriptome, to develop effective molecular markers and to identify genes associated with growth, a key breeding trait. RESULTS: Total RNA was isolated from the mantle, gill, liver, siphon, gonad and muscular foot tissues. High-throughput deep sequencing of S. constricta using 454 pyrosequencing technology yielded 859,313 high-quality reads with an average read length of 489 bp. Clustering and assembly of these reads produced 16,323 contigs and 131,346 singletons with average lengths of 1,376 bp and 458 bp, respectively. Based on transcriptome sequencing, 14,615 sequences had significant matches with known genes encoding 147,669 predicted proteins. Subsequently, previously unknown growth-related genes were identified. A total of 13,563 microsatellites (SSRs and 13,634 high-confidence single nucleotide polymorphism loci (SNPs were discovered, of which almost half were validated. CONCLUSION: De novo sequencing of the razor clam S. constricta transcriptome on the 454 GS FLX platform generated a large number of ESTs. Candidate growth factors and a large number of SSRs and SNPs were identified. These results will impact genetic studies of S. constricta.

  8. THE ACCUMULATION AND DEPURATION OF NO. 2 FUEL OIL BY THE SOFT SHELL CLAM, 'MYA ARENARIA L.'

    Science.gov (United States)

    Young soft shell clams, Mya arenaria, were exposed to subacute concentrations of No. 2 fuel oil-in-water emulsions under simulated winter (4 C) spill conditions. A pattern of accumulation and discharge of petroleum constituents, an experimental depuration time (biological half li...

  9. Radio-resistance of some bacterial pathogens in soft-shell clams (Mya arenaria) and mussels (Mytilus edulis)

    International Nuclear Information System (INIS)

    Gamma-irradiation decimal reduction doses were determined for E. coli, Salmonella typhimurium, Shigella flexneri, Strept. faecalis, Staph, aureus, and the Total Plate Count in a soft-shell clam or mussel substrate. Factors to be considered for designing and irradiation bacterial-decontamination process for shellfish are discussed

  10. Induction of a multixenobiotic resistance protein (MXR) in the Asiatic clam Corbicula fluminea after heavy metals exposure.

    Science.gov (United States)

    Achard, M; Baudrimont, M; Boudou, A; Bourdineaud, J P

    2004-05-12

    Multixenobiotic resistance mechanisms (MXR) related to the mammalian P-glycoprotein multidrug transporter protein (P-gp) are known to occur in several marine invertebrates. In the present work, we report on the induction of an MXR protein by various heavy metals in the gills of the freshwater clam Corbicula fluminea. The evaluation of the MXR protein level was assessed by Western blot using a specific monoclonal antibody raised against the human P-gp (C219). A field transplantation experiment, where clams were caged in a gradient relative to an industrial site, demonstrated a positive relationship between MXR levels and (a) metal pollution (Cd and Zn) in the environment and (b) metal bioaccumulation in the gills. To establish this correlative relationship, clams were exposed to different levels of cadmium (15-60 microg l(-1)) for up to 15 days in a controlled laboratory experiment. MXR protein levels increased in time for all treatments (including the control). However, the highest levels of MXR protein titer were expressed in clams that had been exposed to the lowest dose of cadmium. The causes for this observed inverse relationship between the exposure dose and the MXR induction is discussed. MXR protein titer was also shown to be induced by other heavy metals (zinc, inorganic mercury, and copper). PMID:15084411

  11. Effect of strain rate on the mechanical properties of CLAM steel in liquid PbLi eutectic

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jing; Huang, Qunying [University of Science and Technology of China, Hefei, Anhui 230031 (China); Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Jiang, Zhizhong, E-mail: zhizhong.jiang@fds.org.cn [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China); Zhu, Zhiqiang; Li, Mingyang [Institute of Nuclear Energy Safety Technology, Chinese Academy of Sciences, Hefei, Anhui 230031 (China)

    2013-10-15

    Highlights: • The mechanical properties of CLAM steel in liquid PbLi eutectic were studied firstly. • Tensile tests of RAFMs in liquid PbLi were conducted at a higher temperature of 480 °C. • No obvious liquid metal embrittlement (LME) was found in the given test conditions. -- Abstract: The liquid PbLi blanket is one of the most promising designs for fusion reactors and under extensive research in the world. China Low Activation Martensitic (CLAM) steel has been chosen as the primary candidate structural material for PbLi blanket in China. The effect of strain rate on mechanical properties of CLAM steel with and without liquid PbLi under Ar atmosphere has been investigated with slow strain rate tensile (SSRT) test at 480 °C. SEM observation showed the specimens tested in both environments exhibited ductility fracture with dimpled behavior. The primary tensile results tested with and without PbLi indicated that the uniform elongation of CLAM specimens was independent of strain rate, whereas the total elongation decreased with increasing strain rate. The strength properties tested with liquid PbLi under Ar increased with strain rate from 8.33 × 10{sup −6} s{sup −1} to 4.17 × 10{sup −4} s{sup −1}, but which decreased at 8.33 × 10{sup −4} s{sup −1}.

  12. De novo assembly of Manila clam (Ruditapes philippinarum and protozoan parasite (Perkinsus olseni transcriptome from RNA-Seq data

    Directory of Open Access Journals (Sweden)

    Abul Farah Md. Hasanuzzaman

    2014-06-01

    Full Text Available Manila clam (Ruditapes philippinarum with its high commercial value has become a major contributor to the world´s clam production from both bivalve fishery and aquaculture ventures. But, the production of manila clam is at greater risk from diseases, especially caused by Perkinsus olseni. Considering the limited genomic resources of R. philippinarum and P. olseni as well as the increasing interest in immune-genes response in the host, the present work was conducted to analyze the transcriptome profile of R. philippinarum and of P. olseni using RNA-Seq technology. Data obtained will be used to construct transcriptome databases and to design oligo-microarrays both in the host and the parasite for understanding their transcriptional expressions through host-pathogen interactions. cDNA libraries were synthesized using RNA aliquots of clam haemocytes and perkinsus trophozoites collected from different experimental conditions (in vitro, in vivo and natural environment for further sequencing carried out on Illumina HiSeq 2000 (Oxford Genomics Center, UK. A total of 131,037,742 pair-end reads for R. philippinarum and 67,840,472 for P. olseni were produced. De novo assembly was evaluated using different parameters of Trinity and Abyss assembler programs. De novo transcriptome of clam was further undergone through filtering steps by expression (> 5 FPKM, and length (500 bp for improving transcriptome quality. CAP3 software was executed to cluster final de novo transcriptomes. Trinity+CAP3 assembly was the best approach after manual evaluation of 30 annotated contigs randomly sampled from each strategy and was chosen finally to assemble transcriptomes. 33,182 unique transcripts (3,031 contigs and 30,151 singletons from de novo clam transcriptome, and 47,590 unique transcripts (7,251 contigs and 40,339 singletons from perkinsus transcriptome were obtained. Among them; 3,031 (9.13% unigenes of R. philippinarum, and 7,251 (15.24% of P. olseni were annotated

  13. Rangia and Marsh Clams, Rangia cuneata, R. flexuosa, and Polymesoda caroliniana, in Eastern México: Distribution, Biology and Ecology, and Historical Fisheries

    OpenAIRE

    Armando T. Wakida-Kusunoki; MacKenzie, Jr., Clyde L.

    2004-01-01

    Rangia and marsh clams, Rangia cuneata, R. flexuosa, and Polymesoda caroliniana, occur in brackish waters along México’s eastern coast from the northern State of Tamaulipas to the southern State of Campeche. The clams were important to the prehispanic people in the southern part of the State of Veracruz, where they were used as food and as construction material. In modern times, they are harvested for food. The fishermen wade in shallow water and harvest the clams in soft sediments by hand...

  14. Technical Note: Towards resolving in situ, centimeter-scale location and timing of biomineralization in calcareous meiobenthos - the calcein-osmotic pump method

    Science.gov (United States)

    Bernhard, J. M.; Phalen, W. G.; McIntyre-Wressnig, A.; Mezzo, F.; Wit, J. C.; Jeglinski, M.; Filipsson, H. L.

    2015-09-01

    Insights into oceanographic environmental conditions such as paleoproductivity, deep-water temperatures, salinity, ice volumes, and nutrient cycling have all been obtained from geochemical analyses of biomineralized carbonate of marine organisms. However, we cannot fully understand geochemical proxy incorporation and the fidelity of such in species until we better understand fundamental aspects of their ecology such as where and when these (micro)organisms calcify. Here, we present an innovative method using osmotic pumps and the fluorescent marker calcein to help identify where and when calcareous meiofauna calcify in situ. Method development initially involved juvenile quahogs (Mercenaria mercenaria); subsequent method refinement involved a neritic benthic foraminiferal community. Future applications of this method will allow determining the in situ growth rate in calcareous organisms and provide insights about microhabitats where paleoceanographically relevant benthic foraminifera actually calcify.

  15. Wavelength-specific forward scattering of light by Bragg-reflective iridocytes in giant clams.

    Science.gov (United States)

    Ghoshal, Amitabh; Eck, Elizabeth; Gordon, Michael; Morse, Daniel E

    2016-07-01

    A surprising recent discovery revealed that the brightly reflective cells ('iridocytes') in the epithelia of giant clams actually send the majority of incident photons 'forward' into the tissue. While the intracellular Bragg reflectors in these cells are responsible for their colourful back reflection, Mie scattering produces the forward scattering, thus illuminating a dense population of endosymbiotic, photosynthetic microalgae. We now present a detailed micro-spectrophotometric characterization of the Bragg stacks in the iridocytes in live tissue to obtain the refractive index of the high-index layers (1.39 to 1.58, average 1.44 ± 0.04), the thicknesses of the high- and low-index layers (50-150 nm), and the numbers of pairs of layers (2-11) that participate in the observed spectral reflection. Based on these measurements, we performed electromagnetic simulations to better understand the optical behaviour of the iridocytes. The results open a deeper understanding of the optical behaviour of these cells, with the counterintuitive discovery that specific combinations of iridocyte diameter and Bragg-lamellar spacing can produce back reflection of the same colour that is also scattered forward, in preference to other wavelengths that are scattered at higher angles. We find for all values of size and wavelength investigated that more than 90% of the incident energy is carried by the photons that are scattered in the forward direction; while this forward scattering from each iridocyte shows very narrow angular dispersion (ca ±6°), the multiplicative scattering from a layer of ca 20 iridocytes broadens this dispersion to a cone of approximately ±90°. This understanding of the complex biophotonic dynamics enhances our comprehension of the physiologically, ecologically and evolutionarily significant light environment inside the giant clam, which is diffuse and nearly white at small tissue depths and downwelling, relatively monochromatic, and can be the same colour as

  16. Spatio-temporal variations in biochemical composition, condition index and percentage edibility of the clam, Paphia malabarica (Chemnitz) from estuarine regions of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Nagvenkar, S.S.; Jagtap, T.G.

    Biochemical compositions, condition index (CI) and percentage edibility (PE) of an estuarine clam, Paphia malabarica, were studied from two estuarine regions of Goa during March 2009 to March 2010. Relationships between nutritive components...

  17. Nutrients and clam contamination by Escherichia coli in a meso-tidal coastal lagoon: Seasonal variation in counter cycle to external sources.

    Science.gov (United States)

    Botelho, Maria João; Soares, Florbela; Matias, Domitília; Vale, Carlos

    2015-07-15

    The clam Ruditapes decussatus was transplanted from a natural recruitment area of Ria Formosa to three sites, surveyed for nutrients in water and sediments. Specimens were sampled monthly for determination of Escherichia coli, condition index and gonadal index. Higher nutrient values in low tide reflect drainage, anthropogenic sources or sediment regeneration, emphasising the importance of water mixing in the entire lagoon driven by the tide. Despite the increase of effluent discharges in summer due to tourism, nutrient concentrations and E. coli in clams were lower in warmer periods. The bactericide effect of temperature and solar radiation was better defined in clams from the inlet channel site than from sites closer to urban effluents. High temperature in summer and torrential freshwater inputs to Ria Formosa may anticipate climate change scenarios for south Europe. Seasonal variation of nutrients and clam contamination may thus point to possible alterations in coastal lagoons and their ecosystem services. PMID:26003385

  18. Fluctuations of sulfate, S-bearing amino acids and magnesium in a giant clam shell

    Directory of Open Access Journals (Sweden)

    T. Yoshimura

    2014-01-01

    Full Text Available We used micro-X-ray fluorescence combined with X-ray photoabsorption spectroscopy to investigate speciation-specific sulfur profiles in the inner shell layer of a giant clam (Hippopus hippopus. The sulfate, S-bearing amino acids, and total sulfur profiles indicated that inorganic sulfate was the dominant component in the shell of this bivalve. Sulfur profiles in the inner shell layer showed clear annual fluctuations that varied by more than one order of magnitude, from K-edge XANES and comparison of Mg and S-bearing amino acids profiles indicated that a pronounced effect of the organic fraction or disordered phases were observed in aragonitic shell of H. hippopus rather than regulated substitution into the aragonite crystal lattice.

  19. Comparative Study of the Accumulation of Ni in Different Tissues of Mussels and Soft Clams

    Directory of Open Access Journals (Sweden)

    Chalkiadakis O.

    2013-04-01

    Full Text Available Two bivalves, the mussel Mytilus galloprovincialis, and the soft clam Callista chione were exposed to various Ni concentrations for a total period of 20 days, and then a depuration period of 10 days followed. Nickel accumulation in gills, mantle and the remaining body of the animals was measured after 5, 10, 15 and 20 days of exposure to Ni-contaminated seawater. The two organisms showed different behavior regarding Ni accumulation in all three tissues examined. In all concentrations, Ni accumulation increased with time in all three tissues of Mytilus galloprovincialis with gills being the most effective accumulator per dry mass. On the other hand, Callista chione showed an initial response to Ni contamination the first 5 days, followed by stabilization or even a slight decrease of Ni accumulation.

  20. POSSIBILITIES OF CULTIVATION OF CHAMELEA GALLINA (LINNAEUS, 1758 CLAM ALONG EASTERN ADRIATIC COAST

    Directory of Open Access Journals (Sweden)

    Iris Dupčić

    2004-09-01

    Full Text Available Chamelea gallina clam is among 16 shellfish species commonly present on Croatian fish markets. In the year 2000, European fishermen collected 39,819 tons of this species. The most abundant settlements of Chamelea gallina are situated along western Adriatic coast, however, there are settlements along eastern Adriatic coast especially in the estuaries of Neretva and Cetina, Nin and Novigradsko more areas, as well as along the coasts of islands; Brač, Rab and Susak. Ecological parameters affect growth rates, reproduction and mortality. Due to great temperature oscillations insufficient spat recruitment occurs on occasion. Temperature values determine the time and the intensity of spawning. Hatcheries insure constant and secure spat resource. Adults from brood stock mature during conditioning process, after which they are transferred into spawning tanks for fertilization. Brood stock, larvae, and spat are fed by cultured phytoplankton species.

  1. Use of antioxidant enzymes of clam Ruditapes philippinarum as biomarker to polycyclic aromatic hydrocarbon pollution

    Science.gov (United States)

    Zhu, Lin; Tang, Xuexi; Wang, Ying; Sui, Yadong; Xiao, Hui

    2016-03-01

    The typical organic pollutant polycyclic aromatic hydrocarbon (PAH) anthracene was selected as a contaminant to investigate its effects on the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in the clam Ruditapes philippinarum. The results show that SOD, CAT and GSH-Px had diff erent induction and inhibition reactions to anthracene stress, and that three diff erent organs in R. philippinarum (visceral mass, muscle tissue and mantle) had diff erent sensitivities to anthracene stress. This study suggest that SOD activities of the visceral mass, CAT activitities of the mantle and the visceral mass, and GSH-Px activity of the muscle tissue could be used as sensitive indicators of anthracene stress in R. philippinarum.

  2. Effects of Fishing and Fishing Closures on Beach Clams: Experimental Evaluation across Commercially Fished and Non-Fished Beaches before and during Harvesting.

    Science.gov (United States)

    Gray, Charles A

    2016-01-01

    Management responses to reconcile declining fisheries typically include closed areas and times to fishing. This study evaluated this strategy for a beach clam fishery by testing the hypothesis that changes in the densities and size compositions of clams from before to during harvesting would differ between commercially fished and non-fished beaches. Sampling was spatially stratified across the swash and dry sand habitats on each of two commercially fished and two non-fished beaches, and temporally stratified across three six-week blocks: before, early and late harvesting. Small-scale spatio-temporal variability in the densities and sizes of clams was prevalent across both habitats and the components of variation were generally greatest at the lowest levels examined. Despite this, differences in the densities and sizes of clams among individual beaches were evident, but there were few significant differences across the commercially fished versus non-fished beaches from before to during harvesting. There was no evidence of reduced densities or truncated size compositions of clams on fished compared to non-fished beaches, contrasting reports of some other organisms in protected areas. This was probably due to a combination of factors, including the current levels of commercial harvests, the movements and other local-scale responses of clams to ecological processes acting independently across individual beaches. The results identify the difficulties in detecting fishing-related impacts against inherent levels of variability in clam populations. Nevertheless, continued experimental studies that test alternate management arrangements may help refine and determine the most suitable strategies for the sustainable harvesting of beach clams, ultimately enhancing the management of sandy beaches. PMID:26731102

  3. Effects of Freshwater Clam Extract Supplementation on Time to Exhaustion, Muscle Damage, Pro/Anti-Inflammatory Cytokines, and Liver Injury in Rats after Exhaustive Exercise

    OpenAIRE

    Kuang-Wen Liao; Ru-Ping Lee; Bang-Gee Hsu; Yi-Han Chiu; Tai-Chu Peng; Fwu-Lin Yang; Wen-Tien Wu; Kuo-Chin Huang

    2013-01-01

    The potent anti-inflammatory activities and tissue-protective effects of freshwater clams (Corbicula fluminea) have been well reported. The aim of this study was to determine the effects of freshwater clam extract (FCE) supplementation on time to exhaustion, muscle damage, pro- and anti-inflammatory cytokines, and liver injury in rats after exhaustive exercise. Thirty-two rats were divided into four groups: sedentary control (SC); SC group with FCE supplementation (SC+FCE); exhaustive exercis...

  4. Clam dredging effects and subsequent recovery of benthic communities at different depth ranges.

    Science.gov (United States)

    Constantino, R; Gaspar, M B; Tata-Regala, J; Carvalho, S; Cúrdia, J; Drago, T; Taborda, R; Monteiro, C C

    2009-03-01

    This study aimed to assess the potential effects of clam dredging and the subsequent recovery of the benthic environment. Two experimental areas located at 6 and 18m depth were established in order to analyse whether impacts and recovery of benthic environment are depth-related. Study areas were located within an area closed to dredging and two different plots were established at both depths. One of the plots was subjected to intense clam dredge-fishing, while the other was undisturbed and therefore used as control. Sampling followed a BACI design, with samples for macrobenthic, meiobenthic and sediment particle size analysis being taken by SCUBA divers from both areas before and after fishing stress. For both depths, impacts on the benthic environment were very low resulting in high recovery rates. Nevertheless, at shallower depths communities demonstrated a faster recovery. It was shown that depending on the faunal component used as a bioindicator, different results can be observed. Generally deposit-feeding organisms with scales or chitinous plates and vermiform shape (mainly crustaceans, polychaetes and ophiuroids), without external protection, were the most affected by dredging, while some polychaetes without external protection and with a carnivorous feeding mode seemed to be enhanced by fishing. The low level of perturbations induced by the dredging activities was comparable to the impact of surface waves on the bottom, as experiments were undertaken in wave-dominated environments. The coexistence of storm events during the study period proved to have similar or even more deleterious effects on the benthic environment. It appears that communities from hydrodynamic fishing grounds that are well adapted to natural physical stress are not highly affected by dredging. PMID:19131099

  5. Can 4-nonylphenol induce vitellogenin-like proteins in the clam Tapes philippinarum?

    International Nuclear Information System (INIS)

    Vitellogenins (Vg) are precursors of egg-yolk proteins (vitellins) constituting energy reserves for embryos. In oviparous females, Vg are produced in the liver (or equivalent organs) under the control of endogenous estrogens, released into the bloodstream (plasma or hemolymph), and stored in developing oocytes. Although Vg levels are generally undetectable in male plasma, they may significantly increase in (xeno-)estrogen-exposed males. The aim of the present study was to evaluate estrogenic effects of 4-nonylphenol (NP) in sexually differentiated males and females of the Manila clam Tapes philippinarum. Clams were exposed for 7 days to various sublethal NP concentrations (0, 0+acetone, 0.025, 0.05, 0.1, and 0.2 mg NP/L) and Vg-like protein levels were evaluated in both hemolymph and digestive glands of mollusks by the alkali-labile phosphate assay. This method, based on the determination of phosphates released by Vg, has previously been used to detect Vg concentrations in both fish plasma and bivalve hemolymph. Although Vg levels were generally higher in both hemolymph and digestive gland of T. philippinarum females, males appeared to be more sensitive than females to the estrogenic effects of NP. In males exposed to 0.1 and 0.2 mg NP/L, Vg levels increased significantly in both hemolymph (P<0.05 and P<0.01, respectively) and digestive gland (P<0.05), whereas no changes were observed in those of females. Although the mechanisms by which NP exerts its in vivo endocrine-modulating effects in bivalve mollusks remain unclear, the results of this study demonstrate that NP may induce Vg-like proteins in T. philippinarum, particularly males

  6. Influence of the invasive Asian clam Corbicula fluminea (Bivalvia: Corbiculidae) on estuarine epibenthic assemblages

    Science.gov (United States)

    Ilarri, M. I.; Souza, A. T.; Antunes, C.; Guilhermino, L.; Sousa, R.

    2014-04-01

    One of the most widespread invasive alien species (IAS) in aquatic ecosystems is the Asian clam Corbicula fluminea. Several studies have shown that C. fluminea can cause large-scale changes in macrozoobenthic assemblages; however, very few attempted to investigate the effects of this IAS on mobile epibenthic species, such as fishes and crustaceans. In this context, the influence of C. fluminea on epibenthic species was investigated during one year by comparing the associated epibenthic fauna in three nearby sites of the Minho estuary (NW of the Iberian Peninsula), wherein the abiotic conditions are similar but the density of the Asian clam is highly different. From a total of 13 species, six were significantly influenced by C. fluminea; five responded positively, namely the brown shrimp Crangon crangon, the European eel Anguilla anguilla, the common goby Pomatoschistus microps, the brown trout Salmo trutta fario and the great pipefish Syngnathus acus, whereas the shore crab Carcinus maenas was negatively influenced. However, stomach contents analysis revealed that fish and crustacean species do not feed on C. fluminea, suggesting that this IAS is still not a large component of the diet of higher trophic levels in this estuarine ecosystem. Our results suggest that the structure provided by C. fluminea shells is likely to be one of the main factors responsible for the differences observed. C. fluminea physical structure seems to influence the epibenthic associated fauna, when found in densities higher than 1000 ind./m2, with sedentary small-bodied crustaceans and fishes being mainly attracted by the increasing in habitat complexity and consequent enhancement of heterogeneity and shelter availability.

  7. Effects of elevated carbon dioxide concentrations on survivorship in zebra mussels (Dreissena polymorpha) and Asian clams (Corbicula fluminea)

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, R.F.; Matthews, M.A.; Shaffer, L.R.; Johnson, P.D. [Univ. of Texas, Arlington, TX (United States)

    1995-06-01

    In order to determine their tolerance to elevated concentrations of carbon dioxide, Asian clams and zebra mussels were collected. Subsamples of both species were acclimated to 25{degrees}C>14 days and then exposed in water at 25{degrees}C to various concentrations of CO{sub 2} and survivorship recorded. Zebra mussels were allowed to byssally attach prior to testing. Media CO{sub 2} concentrations were maintained by continuous bubbling with appropriate gas mixtures. Gas treatment included: (1) anoxia; (2) hypercapnic anoxia; and (3) hypercapnic normoxia. Deaths were recorded in subsamples of both species every 12-24 h until 100% mortality was achieved. No significant mortality occurred among specimens of either species in air bubbled control media in any experiment. Mortality time of zebra mussels exposed to anoxia under 100% N{sub 2} was 103.7 h and of Asian clams, 349.7 h. Mortality was more rapid among samples of both species exposed to anoxia under 100% CO{sub 2}, mean time to death being 43.6 h for zebra mussels and 46.3 h for Asian clams. There was no difference in the survivorship of samples of either species under atmospheres of either 5% CO{sub 2} and 95% N{sub 2} or 100% N{sub 2}, however, Asian clams survived anoxia under either atmosphere 4 to 5 times longer than did zebra mussels. There was no significant mortality among Asian clam or zebra mussel samples after a 39 day exposure to hypercapnic normoxia. While exposure to hypercapnic normoxia under an atmosphere of 5% CO{sub 2}:19% O{sub 2}:76% N{sub 2} did not induce mortality in zebra mussel samples, it completely suppressed all byssal thread production after 7 days of exposure and induced all sampled individuals to release from their byssal attachments within 10 days of exposure. These results indicate that CO{sub 2} injection may be an easily applied, cost-effective, environmentally acceptable molluscicide for mitigation and control of raw water system macrofouling by Asian clams and zebra mussels.

  8. The MIRACLE Project: An integrated approach to understanding biogeochemical cycling of mercury and its relationship with lagoon clam farming

    Science.gov (United States)

    Covelli, Stefano

    2012-11-01

    The "MIRACLE" Project was aimed at two specific issues: understanding Hg biogeochemical cycling in the Marano and Grado Lagoon and testing the coexistence of clam farming with Hg contamination in the sediments. Mercury contamination was measured in several matrices (water, sediment, biota) and its mobility was tested along with its speciation in relation to biogeochemical processes occurring in the lagoon environment, where bacterial communities have a primary role in converting Hg to its more toxic form, methylmercury (MeHg). Bioaccumulation of the Hg species was investigated on natural and seeded clams (Ruditapes philippinarum), the most important commercial bivalves in the Lagoon. The Editorial summarizes the main results obtained from this multidisciplinary study and reported in the Special Issue.

  9. Developmental Transcriptome Analysis and Identification of Genes Involved in Larval Metamorphosis of the Razor Clam, Sinonovacula constricta.

    Science.gov (United States)

    Niu, Donghong; Wang, Fei; Xie, Shumei; Sun, Fanyue; Wang, Ze; Peng, Maoxiao; Li, Jiale

    2016-04-01

    The razor clam Sinonovacula constricta is an important commercial species. The deficiency of developmental transcriptomic data is becoming the bottleneck of further researches on the mechanisms underlying settlement and metamorphosis in early development. In this study, de novo transcriptome sequencing was performed for S. constricta at different early developmental stages by using Illumina HiSeq 2000 paired-end (PE) sequencing technology. A total of 112,209,077 PE clean reads were generated. De novo assembly generated 249,795 contigs with an average length of 585 bp. Gene annotation resulted in the identification of 22,870 unigene hits against the NCBI database. Eight unique sequences related to metamorphosis were identified and analyzed using real-time PCR. The razor clam reference transcriptome would provide useful information on early developmental and metamorphosis mechanisms and could be used in the genetic breeding of shellfish. PMID:26921240

  10. Identification, expression, and innate immune responses of two insulin-like peptide genes in the razor clam Sinonovacula constricta.

    Science.gov (United States)

    Niu, Donghong; Wang, Fei; Zhao, Honggang; Wang, Ze; Xie, Shumei; Li, Jiale

    2016-04-01

    Insulin-like peptide (ILP) has emerged as a cell regulatory factor with multiple functions in vertebrates and invertebrates. In the present study, we identified and characterized two ILP genes, ILP1 and ILP2, in the razor clam Sinonovacula constricta. Both ILPs have a signal peptide and a mature domain consisting of six strictly conserved cysteines. The tertiary structure is divided into three main α-helices with a C-domain loop that separates helix 1 from helix 2. Both of ILPs were found to be regulated according to tissue type and developmental stage. After challenge with Vibrio anguillarum, Vibrio parahaemolyticus and Micrococcus lysodeikticus, the expression of two ILP genes was significantly up-regulated in the liver, hemocytes and mantle tissues, suggesting that the ILPs may play roles in the innate immunity in the razor clam Sinonovacula constricta. PMID:26980611

  11. Systems-level modeling the effects of arsenic exposure with sequential pulsed and fluctuating patterns for tilapia and freshwater clam

    International Nuclear Information System (INIS)

    The purpose of this paper was to use quantitative systems-level approach employing biotic ligand model based threshold damage model to examine physiological responses of tilapia and freshwater clam to sequential pulsed and fluctuating arsenic concentrations. We tested present model and triggering mechanisms by carrying out a series of modeling experiments where we used periodic pulses and sine-wave as featured exposures. Our results indicate that changes in the dominant frequencies and pulse timing can shift the safe rate distributions for tilapia, but not for that of freshwater clam. We found that tilapia increase bioenergetic costs to maintain the acclimation during pulsed and sine-wave exposures. Our ability to predict the consequences of physiological variation under time-varying exposure patterns has also implications for optimizing species growing, cultivation strategies, and risk assessment in realistic situations. - Systems-level modeling the pulsed and fluctuating arsenic exposures.

  12. Perkinsosis in the clams Ruditapes decussatus and R. philippinarum in the Northeastern Atlantic and Mediterranean Sea: A review.

    Science.gov (United States)

    Ruano, Francisco; Batista, Frederico M; Arcangeli, Giuseppe

    2015-10-01

    Perkinsosis is a disease of gastropod and bivalve molluscs caused by protozoan parasites of the Perkinsus genus. These parasites have been responsible for mass mortalities worldwide, with a significant impact in both fisheries and aquaculture, and resulting in severe economic losses. This review focuses mainly on current knowledge of diagnostic methods and on the distribution of Perkinsus spp. in the Northeastern Atlantic and Mediterranean Sea, which infect the grooved carpet shell clam Ruditapes decussatus and the Japanese carpet shell clam Ruditapes philippinarum. The association between perkinsosis and high mortality rates of R. decussatus and R. philippinarum in southern European countries such as Portugal and Italy is discussed as is the role of environmental factors in those mortality outbreaks. The putative introduction of Perkinsus olseni into the Northeastern Atlantic and Mediterranean Sea is also discussed, as are management strategies that could be used to mitigate the impact of perkinsosis in production of R. decussatus and R. philippinarum. PMID:26239015

  13. Systems-level modeling the effects of arsenic exposure with sequential pulsed and fluctuating patterns for tilapia and freshwater clam

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W.-Y. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Tsai, J.-W. [Institute of Ecology and Evolutionary Ecology, China Medical University, Taichung 40402, Taiwan (China); Ju, Y.-R. [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Liao, C.-M., E-mail: cmliao@ntu.edu.t [Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2010-05-15

    The purpose of this paper was to use quantitative systems-level approach employing biotic ligand model based threshold damage model to examine physiological responses of tilapia and freshwater clam to sequential pulsed and fluctuating arsenic concentrations. We tested present model and triggering mechanisms by carrying out a series of modeling experiments where we used periodic pulses and sine-wave as featured exposures. Our results indicate that changes in the dominant frequencies and pulse timing can shift the safe rate distributions for tilapia, but not for that of freshwater clam. We found that tilapia increase bioenergetic costs to maintain the acclimation during pulsed and sine-wave exposures. Our ability to predict the consequences of physiological variation under time-varying exposure patterns has also implications for optimizing species growing, cultivation strategies, and risk assessment in realistic situations. - Systems-level modeling the pulsed and fluctuating arsenic exposures.

  14. Combined Effects of Temperature and Seston Concentration on the Physiological Energetics of the Manila Clam Ruditapes philippinarum.

    Science.gov (United States)

    Kang, Hee Yoon; Lee, Young-Jae; Choi, Kwang-Sik; Park, Hyun Je; Yun, Sung-Gyu; Kang, Chang-Keun

    2016-01-01

    The suspension-feeding Manila clam Ruditapes philippinarum is a native species of the western Pacific that is now widely distributed around the globe because of its commercial importance. To determine the adaptive physiological responses to changing thermal and nutritional conditions, clearance, filtration, feces production, ammonium excretion, respiration rates, and scope for growth (SFG) were measured in adult clams. The clams were exposed to 24 treatments involving the combination of four water temperatures (8, 13, 18, and 23°C) and six concentrations of suspended particulate matter (SPM: 9.5 to 350.5 mg L-1). Physiological rates were standardized by using the mean (480 mg) of tissue dry weights of experimental clams using allometric equations between physiological variables and tissue dry weight. Higher clearance rates were recorded at higher temperatures and lower SPM concentrations, and these rates decreased with increasing SPM concentration at individual temperatures. Consumed energy increased with increasing temperature and SPM concentration, peaking at around 100-200 mg L-1 at 18-23°C. Whereas fecal energy was largely determined by SPM concentration, ammonia excretion was mainly governed by temperature. Respiration rate studies revealed a predominant quadratic effect of temperature on the metabolism, indicating a lack of acclimatory adjustment of metabolic rate to rising temperature. SFG values were positive under almost all the treatment conditions and were much higher at higher SPM concentrations (> 45 mg L-1), with the highest level being recorded at 18°C and 100-200 mg L-1 SPM. Increased filtration rate offset the increased metabolic cost at warm temperatures. Our holistic findings suggest that a high degree of physiological plasticity allows R. philippinarum to tolerate the wide range of temperatures and SPM concentrations that are found in tidal flats, accounting in part for the successful distribution of this species over a wide variety of

  15. Identification of Angiotensin I-Converting Enzyme Inhibitory Peptides Derived from Enzymatic Hydrolysates of Razor Clam Sinonovacula constricta

    OpenAIRE

    Yun Li; Sadiq, Faizan A.; Li Fu; Hui Zhu; Minghua Zhong; Muhammad Sohail

    2016-01-01

    Angiotensin I-converting enzyme (ACE) inhibitory activity of razor clam hydrolysates produced using five proteases, namely, pepsin, trypsin, alcalase, flavourzyme and proteases from Actinomucor elegans T3 was investigated. Flavourzyme hydrolysate showed the highest level of degree of hydrolysis (DH) (45.87%) followed by A. elegans T3 proteases hydrolysate (37.84%) and alcalase (30.55%). The A. elegans T3 proteases was observed to be more effective in generating small peptides with ACE-inhibit...

  16. Accumulation and sub-cellular partitioning of metals and As in the clam Venerupis corrugata: Different strategies towards different elements.

    Science.gov (United States)

    Velez, Cátia; Figueira, Etelvina; Soares, Amadeu M V M; Freitas, Rosa

    2016-08-01

    The main goal of the present study was to assess accumulation, tolerance and sub-cellular partitioning of As, Hg, Cd and Pb in Venerupis corrugata. Results showed an increase of elements accumulation in V. corrugata with the increase of exposure. However, organisms presented higher capacity to accumulate Hg, Cd and Pb (BCF ≥ 12.8) than As (BCF ≤ 2.1) and higher accumulation rate for Cd and Pb than for Hg and As. With the increase of Hg exposure concentrations clams tended to increase the amount of metal bound to metal-sensitive fractions, which may explain the mortality recorded at the highest exposure concentration. Cd sub-cellular partitioning showed that with the increase of exposure concentrations V. corrugata increased the amount of metal in the cellular debris fraction, probably bound to the cellular membranes which explain the mortality recorded at the highest concentration. Results on As partitioning demonstrated that most of the metalloid was associated with fractions in the biologically detoxified metal compartment (BDM). Since high mortality was observed in clams exposed to As our results may indicate that this strategy was not enough to prevent clams from toxic effects and mortality occurred. When exposed to Pb most of the metal was in the BDM compartment, but in this case the metal was mostly in the metal-rich granules fraction which seemed to be efficient in preventing clams from toxicity, and no mortality was recorded. Our study further revealed that As and Hg were the most available elements to be biomagnified through the food chain. PMID:27174825

  17. Reproductive Biology of the Short-Necked Clam, Paphia undulata (Born 1778 from Southern Negros Occidental, Central Philippines

    Directory of Open Access Journals (Sweden)

    Fenelyn M. Nabuab

    2010-12-01

    Full Text Available The short-necked clam, Paphia undulata, occurs in coastal muddy bottoms of Hinigaran, Binalbagan, and Himamaylan, Negros Occidental where it has an important contribution to fisheries. However, stocks in these areas are dwindling and in order to formulate sound management strategies, information on the reproductive biology of this species is a prerequisite. Also, knowledge on the reproduction of this species is a prelude to its laboratory breeding and rearing. Reproductive biology of the short-necked clam from the three areas was studied over an annual cycle. Short-necked clams were collected monthly from catches of compressor divers. Five gonad stages were described based on histological examinations: developing, mature, partially spawned, redeveloping, and spent. Immature or indeterminate gonads were also noted. Although occasional presence of hermaphrodite gonads was observed this species is still functionally dioecious with 1.00M: 1.02F sex ratio. Sexual maturity is attained at 42.6 mm for males and 44.8 mm for females. Short-necked clams have continuous breeding season. However, peak of spawning activities is on the months of August to November which coincide with the monsoon transition months probably due to the decrease in salinity and nutrient influx during these months. Organisms smaller than 45mm must not be collected and collection must be regulated during peaks of spawning activities to leave a portion of reproductively mature individuals to ensure sustainability of fisheries. However, in terms of laboratory breeding and rearing of this species, it is fundamental to consider the spawning peaks and size at sexual maturity to ensure successful spawning in the laboratory. Hence, broodstock to be used in the experiments must be sexually mature (>45mm and collected during peaks of spawning activities.

  18. Biota: sediment partitioning of aluminium smelter related PAHs and pulp mill related diterpenes by intertidal clams at Kitimat, British Columbia.

    Science.gov (United States)

    Yunker, Mark B; Lachmuth, Cara L; Cretney, Walter J; Fowler, Brian R; Dangerfield, Neil; White, Linda; Ross, Peter S

    2011-09-01

    The question of polycyclic aromatic hydrocarbon (PAH) bioavailability and its relationship to specific PAH sources with different PAH binding characteristics is an important one, because bioavailability drives PAH accumulation in biota and ultimately the biochemical responses to the PAH contaminants. The industrial harbour at Kitimat (British Columbia, Canada) provides an ideal location to study the bioavailability and bioaccumulation of sediment hydrocarbons to low trophic level biota. Samples of soft shell clams (Mya arenaria) and intertidal sediment collected from multiple sites over six years at various distances from an aluminium smelter and a pulp and paper mill were analysed for 106 PAHs, plant diterpenes and other aromatic fraction hydrocarbons. Interpretation using PAH source ratios and multivariate data analysis reveals six principal hydrocarbon sources: PAHs in coke, pitch and emissions from anode combustion from the aluminium smelter, vascular plant terpenes and aromatised terpenes from the pulp and paper mill, petroleum PAHs from shipping and other anthropogenic activities and PAHs from natural plant detritus. Harbour sediments predominantly contain either pitch or pyrogenic PAHs from the smelter, while clams predominantly contain plant derived PAHs and diterpenes from the adjacent pulp mill. PAHs from the smelter have low bioavailability to clams (Biota-Sediment Accumulation Factors; BSAFs petroleum PAHs and compound specific metabolism, with the importance of petroleum PAHs decreasing with increasing molecular weight. Plant derived compounds exhibit little natural bioaccumulation at reference sites, but unsaturated and aromatised diterpenes released from resins by industrial pulping processes are readily accumulated by the clams (BSAFs >500). Thus while most of the smelter associated PAHs in sediments may not be bioavailable to benthic organisms, the plant terpenes (including retene, totarol, ferruginol, manool, dehydroabietane and other plant

  19. Combined Effects of Temperature and Seston Concentration on the Physiological Energetics of the Manila Clam Ruditapes philippinarum

    Science.gov (United States)

    Kang, Hee Yoon; Lee, Young-Jae; Choi, Kwang-Sik; Park, Hyun Je; Yun, Sung-Gyu; Kang, Chang-Keun

    2016-01-01

    The suspension-feeding Manila clam Ruditapes philippinarum is a native species of the western Pacific that is now widely distributed around the globe because of its commercial importance. To determine the adaptive physiological responses to changing thermal and nutritional conditions, clearance, filtration, feces production, ammonium excretion, respiration rates, and scope for growth (SFG) were measured in adult clams. The clams were exposed to 24 treatments involving the combination of four water temperatures (8, 13, 18, and 23°C) and six concentrations of suspended particulate matter (SPM: 9.5 to 350.5 mg L–1). Physiological rates were standardized by using the mean (480 mg) of tissue dry weights of experimental clams using allometric equations between physiological variables and tissue dry weight. Higher clearance rates were recorded at higher temperatures and lower SPM concentrations, and these rates decreased with increasing SPM concentration at individual temperatures. Consumed energy increased with increasing temperature and SPM concentration, peaking at around 100–200 mg L–1 at 18–23°C. Whereas fecal energy was largely determined by SPM concentration, ammonia excretion was mainly governed by temperature. Respiration rate studies revealed a predominant quadratic effect of temperature on the metabolism, indicating a lack of acclimatory adjustment of metabolic rate to rising temperature. SFG values were positive under almost all the treatment conditions and were much higher at higher SPM concentrations (> 45 mg L–1), with the highest level being recorded at 18°C and 100–200 mg L–1 SPM. Increased filtration rate offset the increased metabolic cost at warm temperatures. Our holistic findings suggest that a high degree of physiological plasticity allows R. philippinarum to tolerate the wide range of temperatures and SPM concentrations that are found in tidal flats, accounting in part for the successful distribution of this species over a wide

  20. Assessment of wet weather impact on clam (Chamelea gallina faecal contamination in the district of San Benedetto del Tronto (Italy

    Directory of Open Access Journals (Sweden)

    Piero Capocasa

    2013-02-01

    Full Text Available Since 1998 clams (Chamelea gallina from the production areas of the district of San Benedetto del Tronto (South Marche - Italy have been periodically monitored to check the microbiological quality by the detection of the faecal indicator E. coli (MPN method. Results have been inconstant. They were not directly related to contamination sources identified by means of a Sanitary Survey. This one included a desk-based study of the physical, geographic, demographic and urban features of the district above and a shoreline survey to confirm or update previously identified sources. With regard to this, several authors found out that meteoric events, in particular rainfalls, increase faecal loading in marine coastal water. This study investigated the impact of rainfalls on E. coli values in clams from the district of San Benedetto del Tronto according to the sampling plan from 2002 to 2011. The study focused on rainfalls occurred until 4 days before mollusc sampling and set up E. coli values into satisfactory and unsatisfactory levels compared to the food safety limit of 230 MPN/100 g. Data were processed by a statistical tool, the Fisher’s exact test. Results revealed the association between precipitations and exceeding values of E. coli in clams collected from coastal waters of most populous areas to be statistically significant.

  1. A preliminary assessment of oxygen isotope fractionation and growth increment periodicity in the estuarine clam Rangia cuneata

    Science.gov (United States)

    Andrus, C. Fred T.; Rich, Kelley Whatley

    2008-10-01

    Rangia cuneata is an upper estuarine clam common in the coastal regions of the Gulf of Mexico. Limited data exist regarding oxygen isotope fractionation and microstructural increment periodicity in this species. As these clams were recently identified as an invasive species in other regions, such data may be useful for environmental management purposes. Additionally, the shell of this clam is common in archeological middens, and thus may serve as a paleoenvironmental proxy. In order to assess these aspects of the species' natural history, samples were collected from the upper Mobile Bay, Alabama, USA. A stable oxygen isotope profile was generated from one of these valves, and compared to growth increments seen in thin section. Time-series water temperature data from near the collection site were used to construct idealized models of oxygen isotope variation, assuming equilibrium fractionation, constant shell growth, and stable water δ18O values. Comparison of the modeled and measured data suggest the shell was precipitated in, or near oxygen isotope equilibrium with ambient water, and that the microstructural increments in the shell were precipitated in response to tidal cycles.

  2. Surface and internal microstructure damage of He-ion-irradiated CLAM steel studied by cross-sectional transmission electron microscopy

    International Nuclear Information System (INIS)

    Good understanding of blistering and embrittlement mechanism depends on good investigation of surface and internal microstructure damage of gas-ion-irradiated materials. Internal and surface microstructure of He+ ion irradiated CLAM steel were examined by cross-sectional transmission electron microscopy combining focused ion beam. Variation of helium bubble density and size distribution versus depth in CLAM steel after high dose helium irradiation at room temperature was investigated. The average size of helium bubble increased within 100–400 nm but decreased near the non-irradiated matrix with the increase of depth, while the density followed a reverse trend. The formation and growth mechanism of helium bubble is different at different irradiation depth. The formation of a zone of large bubbles under the surface is the main reason of surface blistering and flaking. Helium induced irradiation swelling and surface blistering at low temperature were also discussed. - Highlights: • Microstructure of helium irradiated CLAM steel was investigated by FIB and TEM. • The nucleation of helium bubble was controlled by both different mechanisms. • The substructure of surface blisters has been analyzed in detail by XTEM. • Helium induced surface blistering and irradiation swelling have been discussed

  3. Toxicological effects induced by cadmium in gills of Manila clam ruditapes philippinarum using NMR-based metabolomics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Linbao; Liu, Xiaoli; You, Liping; Zhou, Di [Key Laboratory of Coastal Zone Environment Processes, CAS, Shandong Provincial Key Laboratory of Coastal Zone Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai (China); The Graduate School of Chinese Academy of Sciences, Beijing (China); Yu, Junbao; Zhao, Jianmin; Wu, Huifeng [Key Laboratory of Coastal Zone Environment Processes, CAS, Shandong Provincial Key Laboratory of Coastal Zone Environment Processes, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai (China); Feng, Jianghua [Department of Electronic Science, Fujian Key Laboratory of Plasma and Magnetic Resonance, State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen (China)

    2011-11-15

    Cadmium (Cd) has become an important heavy metal contaminant in the sediment and seawater along the Bohai Sea and been of great ecological risk due to its toxic effects to marine organisms. In this work, the toxicological effects caused by environmentally relevant concentrations (10 and 40 {mu}g L{sup -1}) of Cd were studied in the gill tissues of Manila clam Ruditapes philippinarum after exposure for 24, 48, and 96 h. Both low (10 {mu}g L{sup -1}) and high (40 {mu}g L{sup -1}) doses of Cd caused the disturbances in energy metabolism and osmotic regulation and neurotoxicity based on the metabolic biomarkers such as succinate, alanine, branched chain amino acids, betaine, hypotaurine, and glutamate in clam gills after 24 h of exposure. However, the recovery of toxicological effects of Cd after exposure for 96 h was obviously observed in clam to Cd exposures. Overall, these results indicated that NMR-based metabolomics was applicable to elucidate the toxicological effects of heavy metal contaminants in the marine bioindicator. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Study of the toxic effects of flame retardant PBDE-47 on the clam Chamelea gallina (Linnaeus, 1758

    Directory of Open Access Journals (Sweden)

    Salvatora Angela Angioni

    2013-03-01

    Full Text Available The purpose of the study is to evaluate the effects of 2,2',4,4'-tetrabromodiphenylether (PBDE-47 on the Chamelea gallina clam (according to current commercial regulations: Venus gallina. PBDEs, which are used as flame retardants in various industrial products, are classed as hazardous substances by Directive 2011/65/EU. They are bioaccumulative compounds, considered to be endocrine disruptors, genotoxic, neurotoxic and practically ubiquitous, and their concentration in the environment has considerably increased in recent years. The aim of this study is to establish the effects of PBDE-47 on Chamelea gallina: toxic power and any harmful effects on the gonads, bioaccumulation capacity in the tissues, and possible entry into the food chain. The research used 96-hour and 21-day experimental tests on clams housed in filtered seawater. The tests were preceded by a period of acclimatisation of the molluscs lasting five to seven days. The clams were fed on seaweed (Dunaliella tertiolecta. The choice of the toxic compound PBDE-47 was based on the high concentration, among the congeners of PBDE, found in some aquatic species. The study demonstrated that the concentration of the contaminant used did not alter the vital functions, cause significant levels of mortality or lead to evident alteration in the gonads of Chamelea gallina. However, the research demonstrated the bioaccumulation capacity of the bivalve mollusc, allowing PBDE-47 to enter the food chain.

  5. Effect of cage design on growth of transplanted Asian clams: implications for assessing bivalve responses in streams.

    Science.gov (United States)

    Hull, Matthew S; Cherry, Donald S; Merricks, Timothy C

    2004-01-01

    This study was designed to determine whether survivorship and growth of Asian clams (Corbicula fluminea [Müller]) differed significantly between two types of field enclosures. Enclosures were either flexible mesh bags or rigid cages (hereto after referred as bioboxes) designed to homogenize substrate among study sites and accommodate Asian clam feeding mechanisms. For 96d, cages remained at 12 Clinch River (CR), Hurricane Fork (HF), and Dump's Creek (DC) sites upstream and downstream of a coal-fired power plant discharge, coal mining effluent, and coal combustion-related disposal facilities in Carbo, Virginia. Although survivorship was not significantly different between cage types, mean growth of clams in bioboxes was significantly greater overall (p = 0.0157). Despite the difference in growth between the two cage types, both confirmed significant reductions of survivorship and growth directly below the power plant discharge. Additionally, coefficient of variance values for biobox growth data were reduced at most study sites (averages of 16% for bioboxes versus 19% for mesh bags). Our results have implications toward strengthening weight-of-evidence approaches used to link impairment of transplanted bivalves to environmental contaminants. More importantly, these results suggest that ecotoxicological impairment of bivalves transplanted downstream of the coal-fired power plant discharge functioned independently of site-specific substrate provisions. PMID:15327146

  6. Surface and internal microstructure damage of He-ion-irradiated CLAM steel studied by cross-sectional transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, P.P. [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhan, Q., E-mail: qzhan@mater.ustb.edu.cn [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Fu, Z.Y.; Wei, Y.P. [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Y.M. [Faculty of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Wang, F.M. [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Ohnuki, S. [Faculty of Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Wan, F.R. [School of Material Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2015-11-15

    Good understanding of blistering and embrittlement mechanism depends on good investigation of surface and internal microstructure damage of gas-ion-irradiated materials. Internal and surface microstructure of He{sup +} ion irradiated CLAM steel were examined by cross-sectional transmission electron microscopy combining focused ion beam. Variation of helium bubble density and size distribution versus depth in CLAM steel after high dose helium irradiation at room temperature was investigated. The average size of helium bubble increased within 100–400 nm but decreased near the non-irradiated matrix with the increase of depth, while the density followed a reverse trend. The formation and growth mechanism of helium bubble is different at different irradiation depth. The formation of a zone of large bubbles under the surface is the main reason of surface blistering and flaking. Helium induced irradiation swelling and surface blistering at low temperature were also discussed. - Highlights: • Microstructure of helium irradiated CLAM steel was investigated by FIB and TEM. • The nucleation of helium bubble was controlled by both different mechanisms. • The substructure of surface blisters has been analyzed in detail by XTEM. • Helium induced surface blistering and irradiation swelling have been discussed.

  7. Accumulation and depuration profiles of PSP toxins in the short-necked clam Tapes japonica fed with the toxic dinoflagellate Alexandrium catenella.

    Science.gov (United States)

    Samsur, Mohamad; Yamaguchi, Yasunaga; Sagara, Takefumi; Takatani, Tomohiro; Arakawa, Osamu; Noguchi, Tamao

    2006-09-01

    A toxic dinoflagellate responsible for paralytic shellfish poisoning (PSP), Alexandrium catenella (Ac) was fed to the short-necked clam Tapes japonica, and the accumulation and depuration profiles of PSP toxins were investigated by means of high-performance liquid chromatography with postcolumn fluorescence derivatization (HPLC-FLD). The short-necked clams ingested more than 99% of the Ac cells (4 x 10(7)cells) supplied once at the beginning of experiment, and accumulated a maximal amount of toxin (185 nmol/10 clams) after 12h. The rate of toxin accumulation at that time was 23%, which rapidly decreased thereafter. Composition of the PSP toxin accumulated in the clams obviously different from that of Ac even 0.5h after the cell supply, the proportion of C1+2 being much higher than in Ac, although the reason remains to be elucidated. In contrast, a higher ratio of gonyautoxin (GTX)1+4 than in Ac was detected in the toxin profiles of clam excrements. The variation in toxin composition derived presumably from the transformation of toxin analogues in clams was observed from 0.5h, such as reversal of the ratio of C1 to C2, and appearance of carbamate (saxitoxin (STX), neoSTX and GTX2, 3) and decarbamoyl (dc) derivatives (dcSTX and dcGTX2, 3), which were undetectable in Ac cells. The total amount of toxin distributed over Ac cells, clams and their excrements gradually declined, and only 1% of supplied toxin was detected at the end of experiment. PMID:16887162

  8. Implication of site quality on mitochondrial electron transport activity and its interaction with temperature in feral Mya arenaria clams from the Saguenay Fjord

    International Nuclear Information System (INIS)

    The advent of global warming has given rise to questions about the impact of temperature/pollution interactions on the integrity of certain benthic organisms like bivalves. This interaction was examined in intertidal Mya arenaria clams from the Saguenay Fjord using the concepts of cellular energy allocation and temperature-dependent mitochondrial electron transport (METT) activity. Clams were collected at low tide from six sites (two clean, four polluted) for determinations of condition factor (weight/shell length), growth index (age-to-length ratio), gonadal lipids and maturation index, gonad MET at various habitat temperatures, METT, gill xanthine oxidase and gill DNA damage. Condition factor was generally lower at the four polluted sites, with growth index being severely affected at two of them. Gonadal maturation was also significantly dampened at two of the four pollution-impacted sites. Gill xanthine oxidase (purine bases salvage pathway) and DNA strand breaks were significantly increased at most of the polluted sites, confirming pollution-mediated damage in clams. Moreover, MET at 20 deg. C, METT and gonad lipids were significantly induced at the polluted sites. Clam condition factor was negatively correlated with most of the biomarkers for cellular energy allocation (gonadal lipids, MET and METT), but not with gonadal maturation. DNA damage and xanthine oxidase were positively correlated with MET at 20 deg. C and METT. This is the first report of electron transport in mitochondria being more sensitive to incremental temperature increases in clams under pollution stress. The gradual warming of clam habitats would likely worsen the impacts of pollution in feral clam populations

  9. A coupled lake-atmosphere model (CLAM) and its application to Lake Kinneret

    Science.gov (United States)

    Pan, Hai

    1999-08-01

    Kinneret is a 166-km2 lake located in Northern Israel, in the central part of the Jordan Valley, a corridor running from north to south, between the Galilee hills in the west and the Golan Heights in the east. Both the Galilee hills and the Golan Heights reach an elevation of about 400 m above mean sea level (MSL), and the lake is about -210 m (MSL). North of the lake is the mountainous area of the Hermon, culminating at about 2800 m (MSL). About 120 km south of it is the Dead Sea, which is about -410 m (MSL), and about 45 km west of it is the Mediterranean Sea. The complexity of the terrain, combined with relatively arid soil and various ground covers surrounding the lake, results in a very complicated system of atmospheric and lake processes. To understand this system, especially the processes affecting the atmosphere and lake dynamics and thermodynamics, and their effects on Lake Kinneret evaporation, a coupled lake-atmosphere model (CLAM) was developed and applied to the lake region. The CLAM is based on the Regional Atmospheric Modeling System (RAMS) and the oceanic S-coordinate Rutgers University Model (SCRUM). Energy, mass, and momentum are conserved at the interface between the atmosphere and the lake, and appropriate balance equations are applied there. In the atmospheric module, two nested grids are employed to simulate Northern Israel at a resolution of 4 x 4 km2, and the near-lake region at a resolution of 1 x 1 km 2. Synoptic conditions obtained from the National Meteorological Center (NMC) reanalysis are assimilated by the model. Soil moisture, which appears to have a significant impact on atmospheric circulation in this region, was transformed from the normalized difference vegetation index (NDVI). Observations collected during two summers above and inside the lake emphasize the good capability of CLAM to simulate surface fluxes and other microclimatic conditions, as well as lake temperature and currents. Although the lake is small (about 12-km wide

  10. A study of Al2O3 films on CLAM substrate

    International Nuclear Information System (INIS)

    Full text of publication follows: The Dual-Functional Lithium-Lead Blanket Module (DFLL-TBM) system is designed to demonstrate and validate the technologies of both the helium-cooled blanket and the helium/lithium-lead dual-cooled blanket, and there will be several relevant concept designs in China. Considering the fugacity of the tritium and its very low solubility in liquid LiPb, tritium is very easy to permeate out of the blanket, and this will result in the losing of nuclear fuel and the potential radioactive hazard to the circumstance. Additional liquid LiPb flowing in the blanket will produce serious MHD effects and corrupt the structural material. After many years of research in this field, it's considered possible to produce a coating on the structural materials which have advantages such as anti-irradiation-swelling, low thermal expansion coefficient and higher thermal conductance, to reduce tritium permeation, mitigate MHD effects and corrosion by the liquid LiPb. Chinese Low Activation Martensitic (CLAM) Steel was designed to be used as the structural material in the DFLL-TBM and the future DEMO reactor because of its high quality. It is recognized that large quantities of ceramics will be needed in the future for the fabrication of ITER test blanket modules and the ITER driver blanket. Aluminum oxide (Al2O3) ceramic has long been recognized as a promising tritium-breeding material for fusion reactor blankets. Al2O3 films were prepared on CLAM Substrate with the ratio of O2/Ar from 0.1 to 1.2 by RF Magnetron Sputtering method, and the base and the sputtering pressure are 2 x 10-4 Pa and 1 Pa respectively. The existence of nano-scale Al2O3 grains was observed by the Scanning Electronic Microscope(SEM); the structure of the films was investigated by means of X-Ray Diffraction (XRD); the samples were submitted to hydrogen permeation; the resistivity was calculated according to the resistance and the thickness which was measured by interferometer. In this

  11. Challenges to the Application of δ15N measurements of the organic fraction of archaeological and fossil mollusk shells to assess paleoenvironmental change.

    Science.gov (United States)

    Andrus, C. F. T.

    2015-12-01

    Nitrogen isotope analysis of the organic fraction of mollusk shells is beginning to be applied to questions of past anthropogenic and natural environmental variation using samples from archaeological and fossil deposits. Fairly extensive proxy validation research has been conducted in the past decade, documenting the relationship between the δ15N of ambient particulate organic matter, mollusk soft tissues, and shell organic matrix. However, comparatively little research has addressed the potential effects of taphonomy and diagenesis on these proxy records. Assessing archaeological samples are especially complex in that humans may have transported and/or cooked shell prior to deposition. Shell δ15N data will be presented from modern and archaeological oyster (Crassostrea virginica) and clam shell (Mercenaria spp.) of various late Holocene ages and late Cretaceous Crassatellites vadosus shells. Archaeological shells show some loss of organic matter over time, yet some Cretaceous shells retain enough matrix to permit δ15N analysis. The Cretaceous samples required concentration of the remaining organic matrix by removing carbonate via acid pretreatment prior to EA-IRMS analysis, but modern and archaeological shells had sufficient organic matrix to permit analysis without acid pretreatment. The δ15N data from the archaeological shells do not display obvious alteration from the loss of organic matrix. The results of cooking experiments performed on modern oyster shells also indicate little alteration of δ15N values, unless the shell was heated to the point of disintegration. While these experiments indicate promise for the application of δ15N analysis of shell organic matter, the results are incomplete and lack ideal control over initial δ15N values in ancient samples used for comparisons. Future research, perhaps focused on compound-specific δ15N analysis and additional controlled experiments on moderns shells, may improve this assessment.

  12. Intra-specific diet shift in manila clams (Ruditapes philippinarum) as revealed by carbon and nitrogen stable isotopes and fatty acid biomarker

    Science.gov (United States)

    Suh, Y.; Shin, K.

    2011-12-01

    Manila clams sampled in Seonjae Island, Korea with shell lengths (SL) below 19.76 mm in average showed a significantly depleted carbon and nitrogen isotope values (Pdiscrimination factors. In order to examine size-related diet shift in manila clams, R. philippinarum with different sizes that were constantly fed on known mixed microalgae for several months were sampled from Incheon Fisheries Hacheries Research Institute (IFRI). These manila clams have shown a high intra-species variation in growth rate with a maximum difference of more or less 2.30 cm. The smallest size groups (3.68±0.17 mm and 6.88±0.21 mm) obtained their nutrition from both P. tricornutum and aggregated organic matter that consists of dead or decomposed microalgae or other detritus. Bigger size groups (10.92±0.34 mm and 14.81±0.25 mm) obtained most of their energy from P.tricorutum and also from other phytoplankton unlike the biggest size group (21.15±1.02 mm) that feeds mainly on fresh microalgae of all diets fed. This variation in diet reveals that smaller clams mostly inhale dead or decomposed microalgae that sinks on the bottom while the bigger clams uptake more fresh ones that are still alive. This variation in feeding behavior could have been caused by morphological constraints such as limited siphon length. The results suggest that manila clams greater than and below 19.76 mm in average have different feeding behavior and P. tricornutum and I. galbana were the two most preferred diets for manila clams cultured in IFHRI. The result of fatty acid composition of manila clams in relation to size or growth rate suggests that fast growing clams would have rapid metabolism of fatty acids not required by the animals and an accumulation of the essential fatty acids (PUFA). In addition, their higher energy requirement and more active state of development would further diminish lipid reserve of the species.

  13. Analysis of trace elements in the shells of short-necked clam Ruditapes philippinarum (Mollusca: Bivalvia) with respect to reconstruction of individual life history

    International Nuclear Information System (INIS)

    Strontium (Sr) concentration in the shells of short-necked clams collected at different locations (Shirahama, warm area and Maizuru, cold area, Japan) was analyzed by two methods, PIXE and EPMA. The Sr concentration of external surface of shell umbo, which was made during short term at early benthic phase, was analyzed by PIXE, and was ranged from 1000 to 3500 ppm for individuals. The Sr concentration of clams collected at Shirahama showed positive correlation with shell length (SL) in individuals with SL < 31 mm, whereas clams collected at Maizuru did not show significant correlation. This result may be caused from the difference of the spawning seasons between two areas. The Sr concentration of cross section of shell umbo, which develops thicker continuously during their life to form faint stratum structure, was analyzed by EPMA along the line across the stratum structure. Some surges and long term waving patterns of the Sr concentration were observed. These results suggest that the life histories of individual clams could be recorded in the shell umbo cross sections as variations of trace elements and analyses of trace elements could clarify the histories of individual clams. (author)

  14. Some aspects of the reproduction in the elongate sunset clam, Gari (Gabraeus elongata (Lamarck 1818 from Banate Bay Area, West Central Philippines

    Directory of Open Access Journals (Sweden)

    Fenelyn Nabuab

    2006-12-01

    Full Text Available The elongate sunset clam, Gari (Gabraeus elongata (Lamarck 1818 is one of the commercially important invertebrates in Panay Island. The reproductive biology of this species from the Banate Bay Area, Panay Island, West Central Philippines was studied over one annual cycle. Elongate sunset clams were gathered monthly every last quarter of the lunar phase from September 2004 to August 2005.The shell length at first maturation, the sex ratio and the spawning periodicity were determined. The different stages of the reproductive cycle were characterized by histological examination. Seven distinguishable gonad stages were determined in both male and female clams namely, immature, early and late developing, mature, partially spawned, redeveloping and spent. Indeterminate gonads were also noted. Gari elongata is a dioecious species but in a few specimens hermaphroditism was observed. It exhibits no sexual dimorphism. The male to female ratio is 1:1.04. Sexual maturity is attained at 45.40 mm SL in the male and 44.80 mm SL in the female. It is therefore recommended that clams smaller than these sizes should not be collected to allow recruitment and proper sustainability of the resource. Based on the GSI and Index of Sexual Maturity elongate sunset clams have a protracted or continuous breeding period. Sexual activity is highest during the wet season while gamete development occurred during the preceding dry season. The latter is supported by higher phytoplankton densities.

  15. Accumulation and elimination profiles of paralytic shellfish poison in the short-necked clam Tapes japonica fed with the toxic dinoflagellate Gymnodinium catenatum.

    Science.gov (United States)

    Samsur, Mohamad; Takatani, Tomohiro; Yamaguchi, Yasunaga; Sagara, Takefumi; Noguchi, Tamao; Arakawa, Osamu

    2007-02-01

    The paralytic shellfish poison (PSP)-producing dinoflagellate Gymnodinium catenatum (Gc) was fed to the short-necked clam Tapes japonica, and the accumulation, transformation and elimination profiles of PSP were investigated by means of high-performance liquid chromatography with postcolumn fluorescence derivatization (HPLC-FLD). The short-necked clams ingested most of the Gc cells (4 x 10(6) cells) supplied as a bolus at the beginning of the experiment, and accumulated a maximal amount of toxin (181 nmol/10 clams) after 12 hr. The rate of toxin accumulation at that time was 16%, which rapidly decreased thereafter. During the rearing period, a variation in toxin composition, derived presumably from the transformation of toxin analogues in the clams, was observed, including a reversal of the ratio of C2 to C1, and the appearance of carbamate (gonyautoxin (GTX) 2, 3) and decarbamoyl (dc) derivatives (decarbamoylsaxitoxin (dcSTX) and dcGTX2, 3), which were undetectable in Gc cells. The total amount of toxin contained in clams and residue (remaining Gc cells and/or excrement in the rearing tank) gradually declined, and only about 1% of the supplied toxin was detected at the end of the experiment. PMID:17370612

  16. Toxicity and the fractional distribution of trace metals accumulated from contaminated sediments by the clam Scrobicularia plana exposed in the laboratory and the field

    Energy Technology Data Exchange (ETDEWEB)

    Kalman, J., E-mail: judit.kalman@uca.es [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom); Bonnail-Miguel, E. [Department of Physical-Chemistry, University of Cadiz, Poligono Industrial Rio San Pedro s/n, 11,510 Puerto Real, Cadiz (Spain); Smith, B.D. [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom); Bury, N.R. [Division of Diabetes and Nutritional Science, King' s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH (United Kingdom); Rainbow, P.S. [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom)

    2015-02-15

    The relationship between the subcellular distribution of accumulated toxic metals into five operational fractions (subsequently combined into presumed detoxified and non-detoxified components) and toxicity in the clam Scrobicularia plana was investigated under different laboratory exposures. Clams were exposed to metal contaminated media (water and diet) and analysed for the partitioning of accumulated As, Cu and Zn into subcellular fractions. In general, metallothionein-like proteins, metal-rich granules and cellular debris in different proportions acted as main storage sites of accumulated metals in the clam soft tissues for these three metals. No significant differences were noted in the accumulation rates of As, Cu and Zn of groups of individuals with or without apparent signs of toxicity after up to 30 days of exposure to naturally contaminated sediment mixtures. There was, however, an increased proportional accumulation of Cu in the non-detoxified fraction with increased Cu accumulation rate in the clams, suggesting that the Cu uptake rate from contaminated sediments exceeded the combined rates of elimination and detoxification of Cu, with the subsequent likelihood for toxic effects in the clams. - Highlights: • Scrobicularia plana accumulated As, Cu and Zn from naturally toxic sediments. • Toxic metals were accumulated in detoxified and non-detoxified components. • Cu accumulation in the non-detoxified pool increased with increased Cu uptake rate. • Cu uptake rate exceeded combined loss and detoxification rates to cause toxicity.

  17. Toxicity and the fractional distribution of trace metals accumulated from contaminated sediments by the clam Scrobicularia plana exposed in the laboratory and the field

    International Nuclear Information System (INIS)

    The relationship between the subcellular distribution of accumulated toxic metals into five operational fractions (subsequently combined into presumed detoxified and non-detoxified components) and toxicity in the clam Scrobicularia plana was investigated under different laboratory exposures. Clams were exposed to metal contaminated media (water and diet) and analysed for the partitioning of accumulated As, Cu and Zn into subcellular fractions. In general, metallothionein-like proteins, metal-rich granules and cellular debris in different proportions acted as main storage sites of accumulated metals in the clam soft tissues for these three metals. No significant differences were noted in the accumulation rates of As, Cu and Zn of groups of individuals with or without apparent signs of toxicity after up to 30 days of exposure to naturally contaminated sediment mixtures. There was, however, an increased proportional accumulation of Cu in the non-detoxified fraction with increased Cu accumulation rate in the clams, suggesting that the Cu uptake rate from contaminated sediments exceeded the combined rates of elimination and detoxification of Cu, with the subsequent likelihood for toxic effects in the clams. - Highlights: • Scrobicularia plana accumulated As, Cu and Zn from naturally toxic sediments. • Toxic metals were accumulated in detoxified and non-detoxified components. • Cu accumulation in the non-detoxified pool increased with increased Cu uptake rate. • Cu uptake rate exceeded combined loss and detoxification rates to cause toxicity

  18. Nutrients and clam contamination by Escherichia coli in a meso-tidal coastal lagoon: Seasonal variation in counter cycle to external sources

    International Nuclear Information System (INIS)

    Highlights: • Sources of nutrients and E. coli in Ria Formosa linked to tourism in summer. • Lower nutrient values and clam contamination by E. coli in summer. • Bactericide effect of temperature and solar radiation causes lower E. coli. • Higher biological consumption of nutrients in warmer periods. • Results mirror possible effects of climate changes on coastal lagoons. - Abstract: The clam Ruditapes decussatus was transplanted from a natural recruitment area of Ria Formosa to three sites, surveyed for nutrients in water and sediments. Specimens were sampled monthly for determination of Escherichia coli, condition index and gonadal index. Higher nutrient values in low tide reflect drainage, anthropogenic sources or sediment regeneration, emphasising the importance of water mixing in the entire lagoon driven by the tide. Despite the increase of effluent discharges in summer due to tourism, nutrient concentrations and E. coli in clams were lower in warmer periods. The bactericide effect of temperature and solar radiation was better defined in clams from the inlet channel site than from sites closer to urban effluents. High temperature in summer and torrential freshwater inputs to Ria Formosa may anticipate climate change scenarios for south Europe. Seasonal variation of nutrients and clam contamination may thus point to possible alterations in coastal lagoons and their ecosystem services

  19. Complement C3 gene: Expression characterization and innate immune response in razor clam Sinonovacula constricta.

    Science.gov (United States)

    Peng, Maoxiao; Niu, Donghong; Wang, Fei; Chen, Zhiyi; Li, Jiale

    2016-08-01

    Complement component 3 (C3) is central to the complement system, playing an important role in immune defense, immune regulation and immune pathology. Several C3 genes have been characterized in invertebrates but very few in shellfish. The C3 gene was identified from the razor clam Sinonovacula constricta, referred to here as Sc-C3. It was found to be highly homologous with the C3 gene of Ruditapes decussatus. All eight model motifs of the C3 gene were found to be included in the thiolester bond and the C345C region. Sc-C3 was widely expressed in all healthy tissues with expression being highest in hemolymph. A significant difference in expression was revealed at the umbo larvae development stage. The expression of Sc-C3 was highly regulated in the hemolymph and liver, with a distinct response pattern being noted after a challenge with Micrococcus lysodeikticus and Vibrio parahemolyticus. It is therefore suggested that a complicated and unique response pathway may be present in S. constricta. Further, serum of S. constricta containing Sc-C3 was extracted. This was activated by LPS or bacterium for verification for function. The more obvious immune function of Sc-C3 was described as an effective membrane rupture in hemocyte cells of rabbit, V. parahemolyticus and Vibrio anguillarum. Thus, Sc-C3 plays an essential role in the immune defense of S. constricta. PMID:27231190

  20. Molecular phylogenetics and historical biogeography amid shifting continents in the cockles and giant clams (Bivalvia: Cardiidae).

    Science.gov (United States)

    Herrera, Nathanael D; Ter Poorten, Jan Johan; Bieler, Rüdiger; Mikkelsen, Paula M; Strong, Ellen E; Jablonski, David; Steppan, Scott J

    2015-12-01

    Reconstructing historical biogeography of the marine realm is complicated by indistinct barriers and, over deeper time scales, a dynamic landscape shaped by plate tectonics. Here we present the most extensive examination of model-based historical biogeography among marine invertebrates to date. We conducted the largest phylogenetic and molecular clock analyses to date for the bivalve family Cardiidae (cockles and giant clams) with three unlinked loci for 110 species representing 37 of the 50 genera. Ancestral ranges were reconstructed using the dispersal-extinction-cladogenesis (DEC) method with a time-stratified paleogeographic model wherein dispersal rates varied with shifting tectonics. Results were compared to previous classifications and the extensive paleontological record. Six of the eight prior subfamily groupings were found to be para- or polyphyletic. Cardiidae originated and subsequently diversified in the tropical Indo-Pacific starting in the Late Triassic. Eastern Atlantic species were mainly derived from the tropical Indo-Mediterranean region via the Tethys Sea. In contrast, the western Atlantic fauna was derived from Indo-Pacific clades. Our phylogenetic results demonstrated greater concordance with geography than did previous phylogenies based on morphology. Time-stratifying the DEC reconstruction improved the fit and was highly consistent with paleo-ocean currents and paleogeography. Lastly, combining molecular phylogenetics with a rich and well-documented fossil record allowed us to test the accuracy and precision of biogeographic range reconstructions. PMID:26234273

  1. Determination of microcystin-LR in clams (Tapes decussatus) of two Sardinian coastal ponds (Italy).

    Science.gov (United States)

    Sedda, Tiziana; Baralla, Elena; Varoni, Maria Vittoria; Pasciu, Valeria; Lorenzoni, Giuseppa; Demontis, Maria Piera

    2016-07-15

    The presence of microcystin-LR (MC-LR) was monitored in Tapes decussatus harvested in two Sardinian ponds (Cabras and Tortolì, Italy) in spring and summer. After solid phase extraction, samples were analyzed using a screening enzyme-linked immunosorbent assay (ELISA) followed by a liquid chromatographic coupled to tandem mass spectrometer (LC-MS/MS) analysis. Results obtained through the ELISA test showed the presence of microcystins with a maximum concentration in August for Cabras pond (0.55ng/g) and in September for Tortolì pond (0.85ng/g). The LC-MS/MS analysis did not confirm the presence of MC-LR suggesting that results obtained with the ELISA technique could be due to the presence of other microcystins. According to the tolerable daily intake suggested by the World Health Organization, these results hint that clams harvested in these ponds are safe for human health. These data can contribute to enrich the knowledge about the healthiness of Sardinian ponds and of their products. PMID:27103424

  2. Shell matrix proteins of the clam, Mya truncata: Roles beyond shell formation through proteomic study.

    Science.gov (United States)

    Arivalagan, Jaison; Marie, Benjamin; Sleight, Victoria A; Clark, Melody S; Berland, Sophie; Marie, Arul

    2016-06-01

    Mya truncata, a soft shell clam, is presented as a new model to study biomineralization through a proteomics approach. In this study, the shell and mantle tissue were analysed in order to retrieve knowledge about the secretion of shell matrix proteins (SMPs). Out of 67 and 127 shell and mantle proteins respectively, 16 were found in both shell and mantle. Bioinformatic analysis of SMP sequences for domain prediction revealed the presence of several new domains such as fucolectin tachylectin-4 pentraxin-1 (FTP), scavenger receptor, alpha-2-macroglobulin (α2 M), lipocalin and myosin tail along with previously reported SMP domains such as chitinase, carbonic anhydrase, tyrosinase, sushi, and chitin binding. Interestingly, these newly predicted domains are attributed with molecular functions other than biomineralization. These findings suggest that shells may not only act as protective armour from predatory action, but could also actively be related to other functions such as immunity. In this context, the roles of SMPs in biomineralization need to be looked in a new perspective. PMID:27068305

  3. REPRODUCTIVE BIOLOGY OF THE HEART CLAM TRACHYCARDIUM PROCERUM (SOWERBY, 1833 (CARDIIDAE, PELECYPODA FROM CHIMBOTE, PERU

    Directory of Open Access Journals (Sweden)

    Ortiz-Galarza, Karen

    2011-01-01

    Full Text Available The aim of this study was to establish the gametogenesis and histological gonadal maturity scale, the reproductive cycle and size at first gonadal maturity of the heart clam Trachycardium procerum (Sowerby, 1833. The samples were collected from Chimbote, on the beach El Dorado, Samanco Bay, Peru. T. procerum is a benthic species with functional sexual hermaphroditism, with greater reproductive activity in males than in females. The ovary has three types of oocytes: immature (OI, at maturity (OEM and mature (OM in females. Males have spermatogonium (SG, spermatocytes (SC and sperm (SP. The gonads, according to the oocyte and spermatogonial development are grouped into six stages of maturity (virgin = 0; rest = I, maturing = II, mature = III; spawning/eject = IV and recovery = V. Reproduction in T. procerum is partially asynchronous; trabeculae with eggs and sperm at different stages of gonadal development grow in length and diameter as they are filled with mature gametes and are stored until the time of spawning. Reproduction was more intense during the summer (Feb and Mar and spring months (Oct and Nov. The condition factor (CF is related directly to the breeding season. The size at first gonadal maturity for females is 41 mm. The reproductive biology of this important benthic resource provides tools for optimal fisheries management for the conservation of this species.

  4. Seasonal dynamics of biomarkers in infaunal clam Macoma balthica from the Gulf of Riga (Baltic Sea)

    Science.gov (United States)

    Barda, Ieva; Purina, Ingrida; Rimsa, Elina; Balode, Maija

    2014-01-01

    Biomarkers are often regarded as “early warning” signals of environmental pollution; however seasonal changes are mentioned as one of the most important factor that influences the activity of biomarkers. The aim of our study was to assess the importance of seasonal variation of selected contaminant biomarkers in Macoma balthica to provide background information for further environmental surveys in the Gulf of Riga. Seasonal variation of biomarkers (acetylcholinesterase (AChE), catalase (CAT), glutathione reductase (GR) and glutathione-S-transferase (GST)) was measured in infaunal clam M. balthica from the southern part of the Gulf of Riga. The majority of biomarkers (GST, CAT and GR) showed strong seasonal variability; however only CAT and GR were found to be significantly related to environmental factors (near-bottom oxygen, salinity and temperature). Integrated biomarker response (IBR) index indicated that the most stressed condition of M. balthica is during August and May. The highest values of IBR were found near the mouth of the River Daugava, suggesting the impact of environmental pollution on the benthic animals.

  5. Commercial catch rates of the clam Spisula solida reflect local environmental coastal conditions

    Science.gov (United States)

    Baptista, V.; Leitão, F.

    2014-02-01

    The effect of environmental variables and fishing pressure (explanatory variables were lagged 1 year) on commercial catch rates of the clam Spisula solida was studied on an annual basis over a 21 year period in three areas off the Portuguese coast (the Northwest, the Southwest and the South) between 1989 and 2009. Each area showed distinct environmental (oceanographic and hydrological) characteristics. Different sensitivities of S. solida fishing grounds to environmental variables were found among the study areas. On the Northwest coast, the combined effect of NAO indices and sea surface temperature had a positive effect on S. solida fisheries, particularly during the spawning season. On the Southwest coast, the variation of S. solida catches was negatively associated with wind magnitude and positively related with South-Southeast winds. Winter river discharges and summer sea surface temperature negatively affected S. solida catches on the South coast. Fishing effort also affected S. solida catch rates in the South. However, “extreme” changes in environmental conditions were the main drivers of short-term variations in catch rates. These results indicate that variations of S. solida catches strongly reflect a regional signature of local climatic features off the coast. Information on local environmental conditions should therefore be used for the purpose of identifying management actions to ensure long-term sustainability of S. solida fisheries.

  6. Effect of cadmium in the clam Ruditapes decussatus assessed by proteomic analysis

    International Nuclear Information System (INIS)

    Cadmium, an environmental stressor due to its toxicity, persistence and accumulation in biota, is widespread in the aquatic environment. Cadmium accumulation kinetics have revealed that Ruditapes decussatus has a high affinity to this metal. Proteomics is an effective tool to evaluate the toxic effects of contaminants. The aim of this study was to investigate the Cd effects in the gill and digestive gland of the sentinel species R. decussatus. Protein expression profiles (PEPs) in the clam tissues exposed to Cd (40 μg l-1, 21 days) were compared to unexposed ones. Cd induces major changes in tissue-specific protein expression profiles in gill and digestive gland. This tissue dependent response results mainly from differences in Cd accumulation, protein inhibition and/or autophagy. An overall decrease of protein spots was detected in both treated tissues, being higher in gill. Some of the spots more drastically altered after pollutants exposure were excised and nine were identified by micro liquid chromatography tandem mass spectrometry (LC-MS/MS). Proteins identified by homology search in databases included: three proteins (8-fold) up-regulated, one down-regulated, four suppressed and one induced. Cd induces major changes in proteins involved in cytoskeletal structure maintenance (muscle-type actin, adductor muscle actin and β-tubulin), cell maintenance (Rab GDP) and metabolism (ALDH and MCAD, both identified by de novo sequencing) suggesting potential energetic change. They provide a valuable knowledge of Cd effects at biochemical and molecular levels in the gill and digestive gland of R. decussatus.

  7. Capillary crystallization and molecular-replacement solution of haemoglobin II from the clam Lucina pectinata

    International Nuclear Information System (INIS)

    The haemoglobin II from the clam L. pectinata has been crystallized using counter-diffusion in single capillary in the presence of agarose to improve crystal quality. Initial phases have been obtained by molecular replacement. Haemoglobin II is one of three haemoglobins present in the cytoplasm of the Lucina pectinata mollusc that inhabits the Caribbean coast. Using HBII purified from its natural source, crystallization screening was performed using the counter-diffusion method with capillaries of 0.2 mm inner diameter. Crystals of HbII suitable for data collection and structure determination were grown in the presence of agarose at 0.1%(w/v) in order to improve their quality. The crystals belong to the tetragonal space group P42212, with unit-cell parameters a = b = 73.92, c = 152.35 Å, and diffracted X-rays to a resolution of better than 2.0 Å. The asymmetric unit is a homodimer with a corresponding Matthews coefficient (VM) of 3.15 Å3 Da−1 and a solvent content of 61% by volume

  8. Preliminary study of HDA coating on CLAM steel followed by high temperature oxidation

    International Nuclear Information System (INIS)

    A hot-dip aluminizing process is expected to produce aluminide coatings on structural materials to resist tritium permeation, corrosion, and magnetohydrodynamic (MHD) effects in the fusion reactor blanket. China Low Activation Martensitic (CLAM) steel, which is the candidate structural material for the LiPb blanket system in China, was coated with pure aluminum and with an Al–Si alloy. Factors affecting the thickness and morphology of the aluminide coatings were studied. After the hot-dipping treatment, FeAl3 and Fe2Al5 were observed at the Al/steel interface. The existence of silicon in the molten aluminum suppressed the growth of Fe2Al5, built up the thickness of FeAl3 slightly, and contributed to reducing the thickness of the intermetallic layer. The brittle phase of Fe2Al5 had completely transformed to ductile phases of FeAl2, FeAl and α-Fe(Al) after high temperature heat-treatment in air. Kirkendall voids were found in the diffusion layer, due to the rapid interdiffusion of iron and aluminum during oxidation. Cracks and pores were observed on the coating surface and at the interlayer. Grazing incidence X-ray diffraction indicates the presence of α-Al2O3 in the oxide layer

  9. Overfishing population characteristics of razor clam, Ensis macha, from Independencia Bay, Peru, in 2004 year

    Directory of Open Access Journals (Sweden)

    Juan Tarazona

    2011-05-01

    Full Text Available Quantitative monthly samplings, in 2004, were carried out to estimate the density and biomass of Ensis macha (Molina 1782, from Morro Quemado area, Bay Independence, Pisco. The present study analyzes biometric relationships, growth parameters and somatic production using the ELEFAN I routine and the Crisp’s method. During the year 2004 the rate of exploitation (E= 0.69 y-1 was significantly bigger than the values of 2003 and the monthly landings (maximum of 335 t and fishing effort (maximum of 848 trips were twice increased. These changes induced in the same year a significant decrease of population mean density (D= 54.13 ind. m-2 and the halfway reduction of somatic production (P= 81.99 gAFDW m-2 y-1 and P/B rate (0.38 y-1 values, regarding the values of the previous year. Also, a significant increment of total mortality rate (2.84 y-1 and the fishing mortality rate (1.97 y-1 were twice increased, regarding the previous year. It is assumed that the population of razor clams already was a overfishing commercial resource in the 2003 and that the increment of fishing pressure in the 2004, particularly during the second semester, intensified its overfishing resource condition.

  10. Physical proximity may promote lateral acquisition of bacterial symbionts in vesicomyid clams.

    Directory of Open Access Journals (Sweden)

    Carole Decker

    Full Text Available Vesicomyid clams harbor intracellular sulfur-oxidizing bacteria that are predominantly maternally inherited and co-speciate with their hosts. Genome recombination and the occurrence of non-parental strains were recently demonstrated in symbionts. However, mechanisms favoring such events remain to be identified. In this study, we investigated symbionts in two phylogenetically distant vesicomyid species, Christineconcha regab and Laubiericoncha chuni, which sometimes co-occur at a cold-seep site in the Gulf of Guinea. We showed that each of the two species harbored a single dominant bacterial symbiont strain. However, for both vesicomyid species, the symbiont from the other species was occasionally detected in the gills using fluorescence in situ hybridization and gene sequences analyses based on six symbiont marker genes. Symbiont strains co-occurred within a single host only at sites where both host species were found; whereas one single symbiont strain was detected in C. regab specimens from a site where no L. chuni individuals had been observed. These results suggest that physical proximity favored the acquisition of non-parental symbiont strains in Vesicomyidae. Over evolutionary time, this could potentially lead to genetic exchanges among symbiont species and eventually symbiont displacement. Symbiont densities estimated using 3D fluorescence in situ hybridization varied among host species and sites, suggesting flexibility in the association despite the fact that a similar type of metabolism is expected in all symbionts.

  11. Food sources of the Manila clam Ruditapes philippinarum in intertidal areas: evidence from stable isotope analysis

    Science.gov (United States)

    Zhao, Liqiang; Yan, Xiwu; Yang, Feng

    2013-07-01

    Based on stable isotope analysis, we characterized the dietary regime of the Manila clam Ruditapes philippinarum inhabiting intertidal areas along the Liaodong Peninsula, Northern China. Samples, including particulate organic matter (POM; n =30), benthic microalgae (BMI; n =30) and R. philippinarum ( n =60), were collected from six sampling sites displaying the same ecological conditions. Of the two primary food sources, POM was more depleted in δ 13C (-20.61‰ to -22.89‰) than BMI was (-13.90‰ to -16.66‰). With respect to 15N, BMI was more enriched (2.90‰ to 4.07‰) than POM was (4.13‰ to 5.12‰). The δ 13C values of R. philippinarum ranged from -18.78‰ to -19.35‰ and the δ 15N values from 7.96‰ to 8.63‰, which were intermediate between the POM and BMI values. In a two-source isotope mixing model, we estimated the relative contributions of POM and BMI to the diet of R. philippinarum to be 74.2% and 25.8%, respectively. We conclude that R. philippinarum feeds mainly on POM, and BMI is also an important supplemental food source in intertidal areas.

  12. Seasonal Changes in Glycogen Contents in Various Tissues of the Edible Bivalves, Pen Shell Atrina lischkeana, Ark Shell Scapharca kagoshimensis, and Manila Clam Ruditapes philippinarum in West Japan

    Directory of Open Access Journals (Sweden)

    Tatsuya Yurimoto

    2015-01-01

    Full Text Available The types of tissues accumulating glycogen and seasonal changes in glycogen content were investigated in the following shell species: pen shell Atrina lischkeana, ark shell Scapharca kagoshimensis, and Manila clam Ruditapes philippinarum. Comparison of the results showed that the adductor muscle or foot was the main glycogen reservoir and the levels varied seasonally. The adductor muscle in the pen shell showed higher glycogen content during spring and lower content during autumn. The ark shell, on the other hand, showed higher content during winter and spring and lower content during summer and autumn, while the Manila clam showed higher glycogen content during spring and summer and lower content during autumn and winter. These results revealed that the adductor muscle in pen shells and the foot in ark shells and Manila clams act as the main storage tissues for glycogen in the three species studied and that these tissues are suitable to analyze glycogen prevalence to estimate individual physiological condition.

  13. Insights into the establishment of the Manila clam on a tidal flat at the southern end of an introduced range in Southern California, USA.

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    Drew M Talley

    Full Text Available Coastal ecosystem modifications have contributed to the spread of introduced species through alterations of historic disturbance regimes and resource availability, and increased propagule pressure. Frequency of occurrence of the Manila clam (Venerupis phillipinarum, Veneridae in Southern California estuaries has increased from absent or sparse to common since the mid-1990s. Potential invasion vectors include seafood sales and aquaculture, and spread from established northern populations over decades. The clam's post-settlement habitat preferences are, however, uncertain in this region. Our project aimed to identify factors associated with established patches of the clam within a bay toward the southern end of this introduced range. During summer 2013, we sampled 10 tidal flat sites in Mission Bay, San Diego; each containing an area with and without hard structure (e.g., riprap, boulders. We measured likely environmental influences (e.g., sediment variables, distance to ocean. Manila clam densities across the bay were most strongly associated with site, where highest densities were located in the northern and/or back halves of the bay; and weakly correlated with lower porewater salinities. Within sites, Manila clam density was enhanced in the presence of hard structure in most sites. Prevailing currents and salinity regimes likely contribute to bay wide distributions, while hard structures may provide suitable microhabitats (refuge from predators and physical stress and larval entrapment within sites. Results provide insights into decisions about future shoreline management efforts. Finally, we identify directions for future study to better understand and therefore predict patterns of establishment of the Manila clam in the southern portion of its introduced range.

  14. Can ecological history influence response to pollutants? Transcriptomic analysis of Manila clam collected in different Venice lagoon areas and exposed to heavy metal.

    Science.gov (United States)

    Milan, Massimo; Matozzo, Valerio; Pauletto, Marianna; Di Camillo, Barbara; Giacomazzo, Matteo; Boffo, Luciano; Binato, Giovanni; Marin, Maria Gabriella; Patarnello, Tomaso; Bargelloni, Luca

    2016-05-01

    Chronic exposure to environmental pollutants can exert strong selective pressures on natural populations, favoring the transmission over generations of traits that enable individuals to survive and thrive in highly impacted environments. The lagoon of Venice is an ecosystem subject to heavy anthropogenic impact, mainly due to the industrial activities of Porto Marghera (PM), which led to a severe chemical contamination of soil, groundwater, and sediments. Gene expression analysis on wild Manila clams collected in different Venice lagoon areas enabled to identify differences in gene expression profiles between clams collected in PM and those sampled in clean areas, and the definition of molecular signatures of chemical stress. However, it remains largely unexplored to which extent modifications of gene expression patterns persists after removing the source of contamination. It is also relatively unknown whether chronic exposure to xenobiotics affects the response to other chemical pollutants. To start exploring such issues, in the present study a common-garden experiment was coupled with transcriptomic analysis, to compare gene expression profiles of PM clams with those of clams collected in the less impacted area of Chioggia (CH) during a period under the same control conditions. Part of the two experimental groups were also exposed to copper for seven days to assess whether different "ecological history" does influence response to such pollutant. The results obtained suggest that the chronic exposure to chemical pollution generated a response at the transcriptional level that persists after removal for the contaminated site. These transcriptional changes are centered on key biological processes, such as defense against either oxidative stress or tissue/protein damage, and detoxification, suggesting an adaptive strategy for surviving in the deeply impacted environment of Porto Marghera. On the other hand, CH clams appeared to respond more effectively to copper

  15. De novo transcriptome assembly of Perkinsus olseni trophozoite stimulated in vitro with Manila clam (Ruditapes philippinarum) plasma.

    Science.gov (United States)

    Hasanuzzaman, Abul Farah Md; Robledo, Diego; Gómez-Tato, Antonio; Alvarez-Dios, Jose A; Harrison, Peter W; Cao, Asunción; Fernández-Boo, Sergio; Villalba, Antonio; Pardo, Belén G; Martínez, Paulino

    2016-03-01

    The protistan parasite Perkinsus olseni is a deadly causative agent of perkinsosis, a molluscan disease affecting Manila clam (Ruditapes philippinarum), having a significant impact on world mollusc production. Deciphering the underlying molecular mechanisms in R. philippinarum-P. olseni interaction is crucial for controlling this parasitosis. The present study investigated the transcriptional expression in the parasite trophozoite using RNA-seq. Control and treatment (in vitro challenged with Manila clam-plasma) P. olseni trophozoite RNA were extracted and sequenced on the Illumina HiSeq 2000 instrument using a 100-bp paired-end sequencing strategy. Paired reads (64.7 million) were de novo assembled using Trinity, and the resultant transcripts were further clustered using CAP3. The re-constructed P. olseni transcriptome contains 47,590 unique transcripts of which 23,505 were annotated to 9764 unique proteins. A large number of genes were associated with Gene Ontology terms such as stress and immune-response, cell homeostasis, antioxidation, cell communication, signal transduction, signalling and proteolysis. Among annotated transcripts, a preliminary gene expression analysis detected 679 up-regulated and 478 down-regulated genes, linked to virulence factors, anti-oxidants, adhesion and immune-response molecules. Genes of several metabolic pathways such as DOXP/MEP, FAS II or folate biosynthesis, which are potential therapeutic targets, were identified. This study is the first description of the P. olseni transcriptome, and provides a substantial genomic resource for studying the molecular mechanisms of the host-parasite interaction in perkinsosis. In this sense, it is also the first evaluation of the parasite gene expression after challenge with clam extracellular products. PMID:26820448

  16. Coping with seawater acidification and the emerging contaminant diclofenac at the larval stage: A tale from the clam Ruditapes philippinarum.

    Science.gov (United States)

    Munari, Marco; Chemello, Giulia; Finos, Livio; Ingrosso, Gianmarco; Giani, Michele; Marin, Maria G

    2016-10-01

    Seawater acidification could alter the susceptibility of marine organisms to emerging contaminants, such as pharmaceuticals. In this study, the combined effects of seawater acidification and the non-steroidal anti-inflammatory drug diclofenac on survival, growth and oxidative stress-related parameters (catalase activity and lipid peroxidation) in the larvae of the Manila clam Ruditapes philippinarum were investigated for the first time. An experimental flow-through system was set up to carry out a 96-h exposure of clam larvae. Two pH levels (pH 8.0, the control, and pH 7.8, the predicted pH by the end of this century) were tested with and without diclofenac (0.5 μg/L). After 4 days, mortality was dramatically higher under reduced pH, particularly in the presence of diclofenac (62% of the larvae dead). Shell morphology was negatively affected by both acidification and diclofenac from the first day of exposure. The percentage of abnormal larvae was always higher at pH 7.8 than in controls, peaking at 98% in the presence of diclofenac after 96 h. Instead, shell length, shell height or the ratio of these values were only negatively influenced by reduced pH throughout the whole experiment. After 96 h, catalase activity was significantly increased in all larvae kept at pH 7.8, whereas no significant difference in lipid peroxidation was found among the treatments. This study demonstrates a high susceptibility of R. philippinarum larvae to a slight reduction in seawater pH. Furthermore, the results obtained highlight that acidification enhances the sensitivity of clam larvae to environmentally relevant concentrations of diclofenac. PMID:27391052

  17. Repeated sampling of individual bivalve mollusks I: intraindividual variability and consequences for haemolymph constituents of the Manila clam, Ruditapes philippinarum.

    Science.gov (United States)

    Ford, Susan E; Paillard, Christine

    2007-08-01

    Components of the haemolymph are understood to constitute the internal defense system of bivalve mollusks and their levels are often considered to be indicators of "health"; however, relatively little proof exists of the role that these elements play in the success or failure of defense against a pathogen. A change associated with infection may be the consequence of disease rather than a measure of the capacity to respond effectively to a pathogen. One way to assess whether haemocyte or serum-component concentrations are related to resistance to microbial infection is to sample individuals over time, both before and after they are experimentally or naturally infected. But sampling itself may alter the parameter being assessed. In addition, interindividual variation is large and the degree of intraindividual variation over time is largely unknown. To evaluate intra- vs interindividual variability measured over time and to assess the effects of repeated sampling, we subjected Manila clams, Ruditapes philippinarum, to multiple haemolymph samplings during both field and laboratory experiments, and measured four parameters: haemocyte density, protein concentration, and the activities of leucine amino peptidase and DOPA-oxidase. A repeated-measures ANOVA indicated that individuals with high or low levels at one sampling, tended to have high or low levels, respectively, at the other sampling times. Furthermore, the index of individuality, which is the ratio of intra- to interindividual variability, for these four parameters was comparable to that for human serum components. Repeated sampling had no measured effect on field-deployed clams, which were sampled at intervals of 1-3 months, but significantly depressed values in laboratory-held clams sampled at 1-month intervals. Results demonstrated relative intraindividual constancy in the measured variables and suggested that minimizing sample frequency and volume, and maintaining animals in a comparatively natural

  18. Best management strategies for sustainable giant clam fishery in French Polynesia islands: answers from a spatial modeling approach.

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    Simon Van Wynsberge

    Full Text Available The giant clam Tridacna maxima has been largely overexploited in many tropical regions over the past decades, and was therefore listed in appendix II of the Convention of International Trade in Endangered Species (CITES in 1985. In French Polynesia, several atolls and islands harbor the world's highest stocks of giant clams in very shallow and accessible areas, which are therefore highly vulnerable to fishing pressure. The local fishery authority (i.e., Direction des Resources Marines or "DRM" implemented several management schemes in 2002 to control and regulate fishing pressure. However, for further decisions DRM was missing a sensitivity analysis on the effectiveness of the possible management actions. Here, we report on the use of a deterministic Viable Population Analysis (VPA and spatially-explicit age-based population model that simulated the 30-year trajectory of a Tridacna maxima stock under different management approaches. Specifically, given various scenarios of intra-island larval dispersal, we tested which of No-take-Areas (NTAs, rotational closures, size limits, quotas, and restocking schemes would lead to the highest future stocks in Tubuai and Raivavae, two exploited islands of the Austral archipelago. For both islands, stock abundances were estimated in 2004/2010 and 2005/2010 respectively, and natural mortalities were assessed previously only in Tubuai. When compared to field data, the model successfully predicted the 2010 stocks for Tubuai, but proved to be less reliable for Raivavae, where natural mortality rates may well be different from those on Tubuai. For Tubuai, the spatial model suggested that reducing fishing effort (through fixed quotas and banning fishing below the 12 cm size limit (as currently implemented were the most effective management actions to sustain T. maxima populations into the future. Implementing NTAs was of poor effectiveness. NTAs increased giant clam stock inside the protected area, but also

  19. Variation in heavy metals concentration in the edible oyster Crassostrea madrasensis, clam Polymesoda erosa and grey mullet Liza aurata from coastline of India

    Digital Repository Service at National Institute of Oceanography (India)

    Gawade, L.; Chari, N.V.H.; Sarma, V.V.; Ingole, B

    . Variation in heavy metals concentration in the edible oyster Crassostrea madrasensis, clam Polymesoda erosa and grey mullet Liza aurata from coastline of India, Indian Journal of Science, 2013, 2(4), 59-63, www.discovery.org.in http://www.discovery.org.in... RESEARCH Gawade Lata et al. Variation in heavy metals concentration in the edible oyster Crassostrea madrasensis, clam Polymesoda erosa and grey mullet Liza aurata from coastline of India, Indian Journal of Science, 2013, 2(4), 59-63, www.discovery.org.in...

  20. Marine pollution as indicated by oil accumulated on clams collected from the western coasts of the Red Sea, Egypt

    International Nuclear Information System (INIS)

    In order to save the environment from pollution, many techniques are used for identifying oil accumulated on clams along the western coast of the Red Sea. Gas chromatography (GC), infrared (IR), and ultraviolet (UV) absorption spectrophotometry are three different techniques used to analyze the collected samples, GC chromatograms for oil extracted from these animals indicate that the source of pollution is petroleum, and a few peaks reveal a mixture of biogenic and petrogenic hydrocarbons. These results are confirmed by the characteristic IR spectra profiles, high concentrations of the aromatic compounds, and the UV absorption spectra of these samples

  1. Haemocytic leukemia in Prince Edward Island (PEI) soft shell clam (Mya arenaria): Spatial distribution in agriculturally impacted estuaries

    Energy Technology Data Exchange (ETDEWEB)

    Muttray, Annette, E-mail: amuttray@rescan.com [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada); Reinisch, Carol, E-mail: creinisch@mbl.edu [Visiting Scientist Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada); Miller, Jason, E-mail: j.miller@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada); Ernst, William, E-mail: bill.ernst@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 45 Alderney Drive, Dartmouth, NS, Canada B2Y 2N6 (Canada); Gillis, Patricia, E-mail: patty.gillis@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada); Losier, Melanie, E-mail: melanie.losier@ec.gc.ca [Environment Canada, Atlantic Laboratory for Environmental Testing, Environmental Science Centre, P.O. Box 23005 Moncton, NB, Canada E1A 6S8 (Canada); Sherry, James, E-mail: jim.sherry@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada)

    2012-05-01

    Intensive farming of potatoes in Prince Edward Island (PEI) relies on the repeated and widespread application of fertilizers and pesticides. In PEI the main potato farming areas are in close proximity and drain directly to estuaries. Runoff from high agricultural activity watersheds could impact benthic organism health in the depositional zone of downstream estuaries. The estuarine filter feeder Mya arenaria (soft-shell clam) could be particularly vulnerable to both particle-adsorbed and water soluble contaminants. M. arenaria is susceptible to haemocytic leukemia. In May 2009, we established that heavily proliferated leukemia (HPL) prevalence was generally higher in PEI estuaries located downstream of high intensity potato farming (Dunk and Wilmot estuaries) watersheds than in estuaries downstream of lower intensity areas. Using Mab-1E10 based immunocytochemistry we observed that leukemic haemocytes from the Dunk and Wilmot estuaries were 1E10 negative whereas those from the Ox/Sheep estuary (low potato farming intensity) were 1E10 positive. The expression of genes in the p53 tumour suppressor pathway enabled us to differentiate groups of leukemic and normal M. arenaria, validating our diagnoses. In October 2009, we confirmed that HPL prevalence was elevated in the Dunk and Wilmot estuaries compared to reference (Souris River). Moreover, leukemia prevalence declined with distance from the river mouths along transects through the Dunk and Wilmot estuaries. The pesticides ss-endosulfan and {alpha}-endosulfan were detected in surface sediments from the Dunk and Wilmot estuaries, but not in sediments from either the Souris River or several other lower intensity potato farming watersheds. Our study provides evidence of an association between intensity of potato farming and prevalence of clam leukemia at downstream estuaries in PEI. - Highlights: Black-Right-Pointing-Pointer We examined leukemia prevalence in PEI clams Mya arenaria. Black

  2. First study of Vibrios in larval cultures of pullet carpet shell clam (Venerupis corrugata in hatchery

    Directory of Open Access Journals (Sweden)

    Javier Dubert Pérez

    2014-07-01

    Full Text Available Protocol for hatchery culture of the pullet carpet shell clam Venerupis corrugata spat is currently under development, as the only reliable means of providing spat to replenish natural beds or to support aquaculture activities. Among other variables, the microbiota has been demonstrated to be critical for successful bivalve culture. Shellfish hatcheries are hindered by fatal outbreaks of disease, regardless the bivalve species. These mass mortalities are mainly caused by opportunistic bacteria belonging to genus Vibrio and constitute one bottleneck for this economic activity. Different species, as V. tubiashii, V. pectenicida, V. splendidus, V. neptunius, V. ostreicida and V. bivalvicida, have been identified as responsible of mortalities in hatchery-reared larvae, affecting a wide range of bivalves. This is the first report of the microbiota associated with larval cultures of the pullet carpet shell clam. We present the results of the microbiological analyses of two larval cultures of pullet carpet shell reared in the Centro de Investigacións Mariñas (CIMA, Xunta de Galicia de Ribadeo (Galicia, NW Spain following the procedures developed in the institution. Each batch, A and B, was obtained from broodstocks collected in natural environment but in different geographical locations, the stock A (SW Galicia and the stock B (NW Galicia. Previous records of mortalities led us to divide each batch in two. One sub-batch (A1 and B1 was cultured following the routine procedures. Antibiotic was experimentally added to the other sub-batch (A2 and B2 with the aim of evaluating the effects on the culturable bacterial population (total marine bacteria and presumptive vibrios and on larval survival. Chloramphenicol, formerly the most commonly used antibiotic in bivalve hatcheries, was supplied with each change of seawater during larval development. Microbiological samples of broodstock, larvae and seawater in culture tanks were taken and processed

  3. Early development, survival and growth rates of the giant clam Tridacna crocea (Bivalvia: Tridacnidae

    Directory of Open Access Journals (Sweden)

    Miguel Mies

    2012-06-01

    Full Text Available Tridacnid clams are conspicuous inhabitants of Indo-Pacific coral reefs and are traded and cultivated for the aquarium and food industries. In the present study, daily growth rates of larvae of the giant clam Tridacna crocea were determined in the laboratory during the first week of life. Adults were induced to spawn via intra-gonadal serotonin injection through the byssal orifice. After spawning oocytes were collected, fertilized and kept in 3 L glass beakers and raceways treated with antibiotics to avoid culture contamination. Larvae were fed twice with the microalga Isochrysis galbana and zooxanthellae were also offered twice during the veliger stage (days 4 and 6. Larval length was measured using a digitizing tablet coupled to a microcomputer. Larval mortality was exponential during the first 48 hours of life declining significantly afterwards. Mean growth rate was 11.3 μm day-1, increasing after addition of symbionts to 18.0 μm day-1. Survival increased to ca. 75% after the addition of zooxanthellae. The results describe the growth curve for T. crocea larvae and suggest that the acquisition of symbionts by larvae may be useful for larval growth and survival even before larvae have attained metamorphosis.Bivalves tridacnídeos são habitantes conspícuos dos recifes da região do Indo-Pacífico e são cultivados e comercializados para os mercados alimentício e aquarista. No estudo apresentado foram determinadas as taxas de crescimento diário durante a primeira semana de vida da larva do bivalve ornamental Tridacna crocea. As matrizes foram induzidas à desova por meio de uma injeção intragonadal de serotonina realizada através do orifício bissal. Após desova, ovócitos foram coletados, fertilizados e mantidos em béqueres de vidro e tanques de fluxo contínuo tratados com antibióticos para evitar contaminação. Larvas foram alimentadas em duas ocasiões com a microalga Isochrysis galbana e zooxantelas foram oferecidas também por

  4. Role of hemoglobin from blood clam Scapharca kagoshimensis beyond oxygen transport.

    Science.gov (United States)

    Xu, Bin; Zhao, Jun; Jing, Zhao; Zhang, Yanan; Shi, Ying; Fan, Tingjun

    2015-05-01

    The evolutionary race between hosts and pathogens has led to a variety of adaptations. Little is known about the immunological role of hemoglobin (Hb) in antimicrobial immune responses. Results showed that a 31.2 kDa monodimer Hb (skHbI) and a 57.8 kDa heterotetramer Hb (skHbII) from the blood clam, Scapharca kagoshimensis, had phenoloxidase (PO)-like activities and antimicrobial activities. Both were found capable of oxidizing l-DOPA, catechol and hydroquinone. Their PO-like activities were visibly greatly inhibited by oxidase inhibitors, EDTA, and divalent metal ions, and greatly enhanced by isopropanol and Fe(2+), indicating that they have the properties of a metalloenzyme and a catecholase-type PO as well. They also showed obvious anti-bacterial activities against gram-positive bacteria but not against either gram-negative bacteria nor fungi. The anti-bacterial activities levels were a result of the generation of reactive oxygen species (ROS) of superoxide anions. These results indicate that skHbI and skHbII, not only function as iron-containing oxygen carriers, but also exert anti-bacterial activities and catecholase-type oxidizing activities. The fact that skHbII exerts high level of PO-like activity indicates different roles in the innate immunodefense system. These results may improve understanding of the multiple functions of invertebrate Hbs beyond serving as oxygen carriers and may provide insight into how the fundamental and universal mode of the innate immune system has persisted in respiratory proteins throughout the course of evolution. PMID:25700784

  5. Temporal dynamics of amino and fatty acid composition in the razor clam Ensis siliqua (Mollusca: Bivalvia)

    Science.gov (United States)

    Baptista, Miguel; Repolho, Tiago; Maulvault, Ana Luísa; Lopes, Vanessa M.; Narciso, Luis; Marques, António; Bandarra, Narcisa; Rosa, Rui

    2014-12-01

    Few studies have been conducted on the temporal dynamics of both amino acid (AA) and fatty acid (FA) profiles in marine bivalves. We investigated the seasonal variation of these compounds in the pod razor clam Ensis siliqua in relation to food availability, salinity, water temperature and reproductive cycle. AA content varied between 46.94 and 54.67 % dry weight (DW), and the AAs found in greater quantity were glutamic acid, glycine and aspartic acid. FA content varied between 34.02 and 87.94 mg g-1 DW and the FAs found in greater quantity were 16:0 and 22:6 n-3. Seasonal trends were observed for AAs and FAs. FAs increased with gametogenesis and decreased with spawning while AA content increased throughout spawning. The effect of increasing temperature and high food availability during the spawning season masked the loss of AAs resulting from gamete release. Still, a comparatively greater increase in the contents of glutamic acid and leucine with spawning indicate their possible involvement in a post-spawning gonad recovery mechanism. A post-spawning decrease in 14:0, 16:0, 16:1 n-7, 18:1 n-7 and 18:1 n-9 is indicative of the importance of these FAs in bivalve eggs. An increase in 18:3 n-3, 18:4 n-3, 20:1 n-9 and 20:2 n-6 during gametogenesis suggests their involvement in oocyte maturation. The FA 22:4 n-6, while increasing with spawning, appears to play a role in post-spawning gonad recovery. Salinity did not have an effect on the AA composition. None of the environmental parameters measured had an effect on FA composition.

  6. Effect of cadmium in the clam Ruditapes decussatus assessed by proteomic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chora, Suze [University of Algarve, CIMA, Faculty of Marine and Environmental Sciences, Campus de Gambelas, 8000-139 Faro (Portugal); University of Nice-Sophia Antipolis EA 4228 ECOMERS ' Ecosystemes Cotiers Marins et Reponses aux stress' Parc Valrose, BP 71, 06108 Nice cedex 2 (France); Starita-Geribaldi, Mireille [University of Nice-Sophia Antipolis, Laboratory of Oral Microbiology, URE 01., Faculty of Odontology, Pole Universitaire Saint-Jean d' Angely, 24 avenue des Diables Bleus 06357 Nice cedex 4 (France); Guigonis, Jean-Marie [University of Nice-Sophia Antipolis, Plateforme Bernard Rossi - Proteome Metabolome IFR50, Nice, F-06107 (France); Samson, Michel [University of Nice-Sophia Antipolis, Plateforme Bernard Rossi - Proteome Metabolome IFR50, Nice, F-06107 (France); INSERM, Unite 638, Nice, F-06107 (France); Romeo, Michele [University of Nice-Sophia Antipolis EA 4228 ECOMERS ' Ecosystemes Cotiers Marins et Reponses aux stress' Parc Valrose, BP 71, 06108 Nice cedex 2 (France); Bebianno, Maria Joao, E-mail: mbebian@ualg.pt [University of Algarve, CIMA, Faculty of Marine and Environmental Sciences, Campus de Gambelas, 8000-139 Faro (Portugal)

    2009-10-04

    Cadmium, an environmental stressor due to its toxicity, persistence and accumulation in biota, is widespread in the aquatic environment. Cadmium accumulation kinetics have revealed that Ruditapes decussatus has a high affinity to this metal. Proteomics is an effective tool to evaluate the toxic effects of contaminants. The aim of this study was to investigate the Cd effects in the gill and digestive gland of the sentinel species R. decussatus. Protein expression profiles (PEPs) in the clam tissues exposed to Cd (40 {mu}g l{sup -1}, 21 days) were compared to unexposed ones. Cd induces major changes in tissue-specific protein expression profiles in gill and digestive gland. This tissue dependent response results mainly from differences in Cd accumulation, protein inhibition and/or autophagy. An overall decrease of protein spots was detected in both treated tissues, being higher in gill. Some of the spots more drastically altered after pollutants exposure were excised and nine were identified by micro liquid chromatography tandem mass spectrometry (LC-MS/MS). Proteins identified by homology search in databases included: three proteins (8-fold) up-regulated, one down-regulated, four suppressed and one induced. Cd induces major changes in proteins involved in cytoskeletal structure maintenance (muscle-type actin, adductor muscle actin and {beta}-tubulin), cell maintenance (Rab GDP) and metabolism (ALDH and MCAD, both identified by de novo sequencing) suggesting potential energetic change. They provide a valuable knowledge of Cd effects at biochemical and molecular levels in the gill and digestive gland of R. decussatus.

  7. Histopathological survey of the mussel Mytilus chilensis (Mytilidae and the clam Gari solida (Psammobiidae from southern Chile

    Directory of Open Access Journals (Sweden)

    Florencia Cremonte

    2015-03-01

    Full Text Available A total of 175 specimens of mussels, Mytilus chilensis (Mytilidae, and 56 specimens of clams, Gari solida (Psammobiidae, were collected in natural beds and culture sites of southern Chile. Juvenile mussel specimens (3 cm of maximum length were free of parasites and diseases, whilst the commercial sized populations was parasitized by intracellular inclusions of bacteria-like organisms in the digestive gland epithelium and in the gills, by ciliates in the gills, turbellarians similar to Paravortex (Rhabocoela in the intestine lumen and copepods attached to the gills. In addition, the disseminated neoplasia disease was also present although in low prevalences. In the clam, G. solida, prokariotic inclusions were found in the digestive gland epithelium and bacteria-like organisms in the gills, often encapsulated by haemocytes; oocysts containing up to 8 sporozoites similar to Nematopsis (Apicomplexa in the connective tissue, causing haemocytic infiltration when the intensity of infection was high; ciliates belonging to two different species (one of them similar to Trichodina inhabiting the gills; and a turbellarian similar to Paravortex in the lumen of digestive system without apparent host reaction. The populations of the bivalve species here studied were devoid of serious pathogens.

  8. Assessment of parental contribution and effective population size from a 3×3 diallel cross of clam Meretrix meretrix

    Science.gov (United States)

    Dai, Ping; Wang, Hongxia; Liu, Baozhong

    2014-03-01

    Unbalanced parental contribution and small effective population size ( N e) are common issues during the artificial breeding of marine bivalves. The impact of hatchery-spawning practices on parental contribution, effective population size, the N e/ N ratio, and genetic diversity are largely unknown. To address this, we conducted a parentage analysis on a complete 3×3 diallel cross of clam M eretrix meretrix using eight microsatellite markers. The genetic diversity of the parents was higher than that of their respective offspring in most crosses (8/9). Sires or dams from the same family contributed unequally to the pool of offspring from a particular cross, and the same parent clam exhibited large variation in parental contribution among different crosses. The variance in male contribution was higher than that of the female contribution in most crosses, suggesting that male contribution was more skewed than for females. The N e/ N ratio for nine crosses ranged from 0.58 to 0.86. There was no linear relationship between the sex ratio and the N e/ N ratio ( P > 0.05). Moreover, a sex ratio closer to one-to-one does not necessarily mean a larger effective population size. A solution to small effective population size in commercial breeding programs is increasing broodstock numbers and attempting to maintain a balanced sex ratio.

  9. The influence of salinity on toxicological effects of arsenic in digestive gland of clam Ruditapes philippinarum using metabolomics

    Institute of Scientific and Technical Information of China (English)

    JI Chenglong; WU Huifeng; LIU Xiaoli; ZHAO Jianmin; YU Junbao; YIN Xiuli

    2013-01-01

    Ruditapes philippinarum,a clam that thrives in intertidal zones of various salinities,is a useful biomonitor to marine contaminants.We investigated the influence of dilution to 75% and 50% of normal seawater salinity (31.1) on the responses of the digestive gland of R.philippinarum to arsenic exposure (20 μg/L),using nuclear magnetic resonance (NMR)-based metabolomics.After acute arsenic exposure for 48 h,salinity-dependent differential metabolic responses were detected.In normal seawater,arsenic exposure increased the concentrations of branched-chain amino acids,and of threonine,proline,phosphocholine and adenosine,and it decreased the levels of alanine,hypotaurine,glucose,glycogen and ATP in the digestive glands.Differential changes in metabolic biomarkers observed at lower salinity (~23.3)included elevation of succinate,taurine and ATP,and depletion of branched-chain amino acids,threonine and glutamine.Unique effects of arsenic at the lowest salinity (~15.6) included down-regulation of glutamate,succinate and ADP,and up-regulation of phosphocholine.We conclude that salinity influences the metabolic responses of this clam to arsenic.

  10. Identification of Angiotensin I-Converting Enzyme Inhibitory Peptides Derived from Enzymatic Hydrolysates of Razor Clam Sinonovacula constricta.

    Science.gov (United States)

    Li, Yun; Sadiq, Faizan A; Fu, Li; Zhu, Hui; Zhong, Minghua; Sohail, Muhammad

    2016-01-01

    Angiotensin I-converting enzyme (ACE) inhibitory activity of razor clam hydrolysates produced using five proteases, namely, pepsin, trypsin, alcalase, flavourzyme and proteases from Actinomucor elegans T3 was investigated. Flavourzyme hydrolysate showed the highest level of degree of hydrolysis (DH) (45.87%) followed by A. elegans T3 proteases hydrolysate (37.84%) and alcalase (30.55%). The A. elegans T3 proteases was observed to be more effective in generating small peptides with ACE-inhibitory activity. The 3 kDa membrane permeate of A. elegans T3 proteases hydrolysate showed the highest ACE-inhibitory activity with an IC50 of 0.79 mg/mL. After chromatographic separation by Sephadex G-15 gel filtration and reverse phase-high performance liquid chromatography, the potent fraction was subjected to MALDI/TOF-TOF MS/MS for identification. A novel ACE-inhibitory peptide (VQY) was identified exhibiting an IC50 of 9.8 μM. The inhibitory kinetics investigation by Lineweaver-Burk plots demonstrated that the peptide acts as a competitive ACE inhibitor. The razor clam hydrolysate obtained by A. elegans T3 proteases could serve as a source of functional peptides with ACE-inhibitory activity for physiological benefits. PMID:27271639

  11. The uptake and loss of zinc-65 by the prawn Palaemon elegans and the clam Tapes decussatus in the Mediterranean

    International Nuclear Information System (INIS)

    In order to evaluate the uptake, accumulation and loss of 65Zn by organisms inhabiting the continental shelf of the Mediterranean sea, the uptake, accumulation and loss of 65Zn by the prawn, Palaemon elegans Rathke and the clam, Tapes decussatus both considered to be the indicator organisms in the coastal waters for measuring radioactive pollution were studied. Sea water solutions used in the experiments were filtered through a millipore filter of 0.45 μ to remove microorganisms and suspended particles. Specimens collected for experiments were placed for acclimatization in pure sea water for several days and 65Zn in chloride form (in 0.1 N HCl) was added to sea water. 65Zn accumulation in the organisms and the change in radioactivity in the water were measured with NaI (Tl) crystal detector. Uptake of 65Zn in the tissues of the prawn was fast, most of the radioactivity being incorporated in the tissues within 75-100 h exposure. The uptake varied directly with the environmental temperature. Uptake of 65Zn by the clam is a relatively rapid process, but the equilibrium is not reached within a period of days. (M.G.B.)

  12. Invasive zebra mussels (Driessena polymorpha) and Asian clams (Corbicula fluminea) survive gut passage of migratory fish species: implications for dispersal

    Science.gov (United States)

    Gatlin, Michael R.; Shoup, Daniel E.; Long, James M.

    2013-01-01

    The introduction and spread of invasive species is of great concern to natural resource managers in the United States. To effectively control the spread of these species, managers must be aware of the multitude of dispersal methods used by the organisms. We investigated the potential for survival through the gut of a migrating fish (blue catfish, Ictalurus furcatus) as a dispersal mechanism for two invasive bivalves: zebra mussel (Driessena polymorpha) and Asian clam (Corbicula fluminea). Blue catfish (N = 62) were sampled over several months from Sooner Lake, Oklahoma, transported to a laboratory and held in individual tanks for 48 h. All fecal material was collected and inspected for live mussels. Survival was significantly related to water temperature in the lake at the time of collection, with no mussels surviving above 21.1 C°, whereas 12 % of zebra mussels (N = 939) and 39 % of Asian clams (N = 408) consumed in cooler water survived gut passage. This research demonstrates the potential for blue catfish to serve as a dispersal vector for invasive bivalves at low water temperatures.

  13. Identification of Angiotensin I-Converting Enzyme Inhibitory Peptides Derived from Enzymatic Hydrolysates of Razor Clam Sinonovacula constricta

    Directory of Open Access Journals (Sweden)

    Yun Li

    2016-06-01

    Full Text Available Angiotensin I-converting enzyme (ACE inhibitory activity of razor clam hydrolysates produced using five proteases, namely, pepsin, trypsin, alcalase, flavourzyme and proteases from Actinomucor elegans T3 was investigated. Flavourzyme hydrolysate showed the highest level of degree of hydrolysis (DH (45.87% followed by A. elegans T3 proteases hydrolysate (37.84% and alcalase (30.55%. The A. elegans T3 proteases was observed to be more effective in generating small peptides with ACE-inhibitory activity. The 3 kDa membrane permeate of A. elegans T3 proteases hydrolysate showed the highest ACE-inhibitory activity with an IC50 of 0.79 mg/mL. After chromatographic separation by Sephadex G-15 gel filtration and reverse phase-high performance liquid chromatography, the potent fraction was subjected to MALDI/TOF-TOF MS/MS for identification. A novel ACE-inhibitory peptide (VQY was identified exhibiting an IC50 of 9.8 μM. The inhibitory kinetics investigation by Lineweaver-Burk plots demonstrated that the peptide acts as a competitive ACE inhibitor. The razor clam hydrolysate obtained by A. elegans T3 proteases could serve as a source of functional peptides with ACE-inhibitory activity for physiological benefits.

  14. Effects of LSP on micro-structures and residual stresses in a 4 mm CLAM steel weld joints

    International Nuclear Information System (INIS)

    The effects of laser shock processing (LSP) on the distribution of residual stress and micro-structure of China Low Activation Martensitic (CLAM) steel weldment were investigated via neutron diffraction and optical microscope (OM). A pair of 4 mm CLAM steel plates joined by GTA welding. Special attention is paid to the generation of high level compressive residual stresses introduced by LSP. Residual stress in longitudinal, normal and transversal direction at weldment surface and longitudinal stress through thickness are evaluated via neutron diffraction. Compressive residual stress after LSP occurred at more than 90% areas within the weld joint, it is almost double the areas of compressive stress compare to weldment surface before LSP. The maximum compressive normal residual stress becomes to −183 MPa after LSP from −63 MPa before LSP. The Modification of surface micro-structures including weld zone (WZ), heat affected zone (HAZ) and base metal (BM) are also discussed. Results to date demonstrate that laser shock processing has been a great potential method for the improvement of mechanical performance of components

  15. Seasonal changes in physiological responses and evaluation of "well-being" in the Venus clam Chamelea gallina from the Northern Adriatic Sea.

    Science.gov (United States)

    Moschino, Vanessa; Marin, Maria Gabriella

    2006-12-01

    Chamelea gallina is an infaunal bivalve, widespread in sandy bottoms along Mediterranean coasts. It is an important economic resource for fisheries in the Adriatic, although in recent years over-fishing, and other concurrent factors, have dramatically decreased clam harvesting. In this context, it is of great interest to gain information on seasonal variations in the physiological performance of clams, for an overall evaluation of their well-being. In this study, laboratory experiments were performed to define allometric relationships and effects of temperature on clearance and respiration rates of C. gallina. The mean values of b coefficients were calculated and used to correlate physiological measurements to 'standard' body mass, when seasonally collected clams were analysed. The highest clearance rate (0.42 L h(-1)) was measured in clams collected in July 2000; the highest respiration rate (12.22 micromol O2 h(-1)) was observed in July 2001, leading to a negative scope for growth (-2.8 J h(-1)). The influence of environmental and endogenous factors, mostly reproduction, was discussed. Survival in air and condition indices, showing higher stress conditions in December 2000 and July 2001, were in good agreement with the other physiological measurements. The physiological responses examined in this study appear to be suitable for providing detailed indications on the well-being of C. gallina and may be useful for future studies aimed at eco-sustainable management of the resource. PMID:16959514

  16. Tropomyosin and Actin Identified as Major Allergens of the Carpet Clam (Paphia textile and the Effect of Cooking on Their Allergenicity

    Directory of Open Access Journals (Sweden)

    Zailatul Hani Mohamad Yadzir

    2015-01-01

    Full Text Available Objectives. To identify the major allergenic proteins of clam (Paphia textile and to investigate the effect of different cooking methods on the allergenicity of these identified proteins. Methods. Clam protein extracts were separated by denaturing polyacrylamide gel electrophoresis. IgE reactive proteins were then analyzed by immunoblotting with sera from patients with positive skin prick tests (SPT to the raw clam extract. Mass spectrometry was used to identify the major allergenic proteins of this clam. Results. Raw extract showed 12 protein bands (18–150 kDa. In contrast, fewer protein bands were seen in the boiled extract; those ranging from 40 to 150 kDa were denatured. The protein profiles were similarly altered by frying or roasting. The immunoblots of raw and boiled extracts yielded 10 and 2 IgE-binding proteins, respectively. The fried and roasted extracts showed only a single IgE-binding protein at 37 kDa. Mass spectrometry analysis of the 37 and 42 kDa major allergens indicated that these spots were tropomyosin and actin, respectively. Conclusion. The two major allergens of Paphia textile were identified as the thermostable tropomyosin and a new thermolabile allergen actin.

  17. Population density, biomass, and age-class structure of the invasive clam Corbicula fluminea in rivers of the lower San Joaquin River watershed, California

    Science.gov (United States)

    Brown, L.R.; Thompson, J.K.; Higgins, K.; Lucas, L.V.

    2007-01-01

    Corbicula fluminea is well known as an invasive filter-feeding freshwater bivalve with a variety of effects on ecosystem processes. However. C. fluminea has been relatively unstudied in the rivers of the western United States. In June 2003, we sampled C. fluminea at 16 sites in the San Joaquin River watershed of California, which was invaded by C. fluminea in the 1940s. Corbicula fluminea was common in 2 tributaries to the San Joaquin River, reaching densities of 200 clams??m-2, but was rare in the San Joaquin River. Biomass followed a similar pattern. Clams of the same age were shorter in the San Joaquin River than in the tributaries. Distribution of clams was different in the 2 tributaries, but the causes of the difference are unknown. The low density and biomass of clams in the San Joaquin River was likely due to stressful habitat or to water quality, because food was abundant. The success of C. fluminea invasions and subsequent effects on trophic processes likely depends on multiple factors. As C. fluminea continues to expand its range around the world, questions regarding invasion success and effects on ecosystems will become important in a wide array of environmental settings.

  18. Comparative genomic analysis of mitochondrial protein-coding genes in Veneroida clams: Analysis of superfamily-specific genomic and evolutionary features.

    Science.gov (United States)

    Hwang, Jae Yeon; Lee, Chang-Kyu; Kim, Heebal; Nam, Bo-Hye; An, Cheul Min; Park, Jung Youn; Park, Kyu-Hyun; Huh, Chul-Sung; Kim, Eun Bae

    2015-12-01

    Veneroida is the largest order of bivalves, and these clams are commercially important in Asian countries. Although numerous studies have focused on the genomic characters of individual species or genera in Veneroida, superfamily-specific genomic characters have not been determined. In this study, we performed a comparative genomic analysis of 12 mitochondrial protein coding genes (PCGs) from 25 clams in six Veneroida superfamilies to determine genomic and evolutionary features of each superfamily. Length and distribution of nucleotides encoding the PCGs were too variable to define superfamily-specific genomic characters. Phylogenetic analysis revealed that PCGs are suitable for classification of species in three superfamilies: Cardioidea, Mactroidea, and Veneroidea. However, one species classified in Tellinoidea, Sinonovacula constricta, was evolutionarily closer to Solenoidea clams than Tellinoidea clams. dN/dS analysis showed that positively selected sites in NADH dehydrogenase subunit, nd4 and subunit of ATP synthase, atp6 were present in Mactroidea. Differences in selected sites in the nd4 and atp6 could be caused by superfamily-level differences in sodium transport or ATP synthesis functions, respectively. These differences in selected sites in NADH may have conferred these animals, which have low motility and do not generally move, with increased flexibility to maintain homeostasis in the face of osmotic pressure. Our study provides insight into evolutionary traits as well as facilitates identification of veneroids. PMID:26343338

  19. How life history influences the responses of the clam Scrobicularia plana to the combined impacts of carbamazepine and pH decrease

    International Nuclear Information System (INIS)

    In the present study, the bivalve Scrobicularia plana, collected from two contrasting areas (pristine location and mercury contaminated area), was selected to assess the biochemical alterations imposed by pH decrease, carbamazepine (an antiepileptic) and the combined effect of both stressors. The effects on oxidative stress related biomarkers after 96 h exposure revealed that pH decrease and carbamazepine induced alterations on clams, with greater impacts on individuals from the contaminated area which presented higher mortality, higher lipid peroxidation and higher glutathione S-transferase activity. These results emphasize the risk of extrapolating results from one area to another, since the same species inhabiting different areas may be affected differently when exposed to the same stressors. Furthermore, the results obtained showed that, when combined, the impact of pH decrease and carbamazepine was lower than each stressor acting alone, which could be related to the defence mechanism of valves closure when bivalves are under higher stressful conditions. - Highlights: • Environmentally relevant concentrations of CBZ and pH 7.1 impacted the performance of Scrobicularia plana. • The combination of CBZ and pH 7.1 did not induce higher impacts compared with stressors acting alone. • Clams from a polluted area showed greater alterations than clams collected from an unpolluted area. - pH decrease and carbamazepine induced biochemical alterations on clams (Scrobicularia plana), with greater impacts on individuals from the contaminated area

  20. Certification of Trace Elements and Methyl Mercury Mass Fractions in IAEA-461 Clam (Gafrarium tumidum) Sample

    International Nuclear Information System (INIS)

    The primary goal of the IAEA Environment Laboratories is to assist Member States in the use of both stable and radioisotope analytical techniques to understand, monitor and protect the environment. In this context, the major impact exerted by large coastal cities on marine ecosystems is an issue of primary concern for the IAEA and the IAEA Environment Laboratories. The marine pollution assessments required to understand such impacts depend on accurate knowledge of contaminant concentrations in various environmental compartments. The IAEA Environment Laboratories has been assisting national laboratories and regional laboratory networks since the early 1970s through the provision of reference material programme for the analysis of radionuclides, trace elements and organic compounds in marine samples. Quality assurance, quality control and associated good laboratory practice are essential components of all marine environmental monitoring studies. Quality control procedures are commonly based on the analysis of certified reference materials and reference samples in order to validate analytical methods used in monitoring studies and to assess the reliability and comparability of measurement data. Data that are not based on adequate quality assurance and quality control can be erroneous, and their misuse can lead to poor environmental management decisions. This publication describes the production of the IAEA-461 certified reference material, which was produced following ISO Guide 34:2009, General Requirements for the Competence of Reference Material Producers. A sample of approximately 60 kg of clams (Gafrarium tumidum) was collected in Noumea, New Caledonia, and processed at the IAEA Environment Laboratories to produce a certified reference material of marine biota. The sample contained certified mass fractions for arsenic, cadmium, calcium, chromium, cobalt, copper, iron, lead, mercury, methyl mercury, manganese, nickel, selenium, vanadium and zinc. The produced vials

  1. Long-term Cultivation of the Deep-Sea Clam Calyptogena okutanii: Changes in the Abundance of Chemoautotrophic Symbiont, Elemental Sulfur, and Mucus.

    Science.gov (United States)

    Ohishi, Kazue; Yamamoto, Masahiro; Tame, Akihiro; Kusaka, Chiho; Nagai, Yukiko; Sugimura, Makoto; Inoue, Koji; Uematsu, Katsuyuki; Yoshida, Takao; Ikuta, Tetsuro; Toyofuku, Takashi; Maruyama, Tadashi

    2016-06-01

    Survival of deep-sea Calyptogena clams depends on organic carbon produced by symbiotic, sulfur-oxidizing, autotrophic bacteria present in the epithelial cells of the gill. To understand the mechanism underlying this symbiosis, the development of a long-term cultivation system is essential. We cultivated specimens of Calyptogena okutanii in an artificial chemosynthetic aquarium with a hydrogen sulfide (H2S) supply system provided by the sulfate reduction of dog food buried in the sediment. We studied morphological and histochemical changes in the clams' gills by immunohistochemical and energy-dispersive X-ray analyses. The freshly collected clams contained a high amount of elemental sulfur in the gill epithelial cells, as well as densely packed symbiotic bacteria. Neither elemental sulfur nor symbiotic bacteria was detected in any other organs except the ovaries, where symbiotic bacteria, but not sulfur, was detected. The longest survival of an individual clam in this aquarium was 151 days. In the 3 clams dissected on Days 57 and 91 of the experiment, no elemental sulfur was detected in the gills. The symbiotic bacteria content had significantly decreased by Day 57, and was absent by Day 91. For comparison, we also studied the deep-sea mussel Bathymodiolus septemdierum, which harbors a phylogenetically close, sulfur-oxidizing, symbiotic bacterium with similar sulfur oxidation pathways. Sulfur particles were not detected, even in the gills of the freshly collected mussels. We discuss the importance of the proportion of available H2S and oxygen to the bivalves for elemental sulfur accumulation. Storage of nontoxic elemental sulfur, an energy source, seems to be an adaptive strategy of C. okutanii. PMID:27365420

  2. Contrasting Physiological Responses of Two Populations of the Razor Clam Tagelus dombeii with Different Histories of Exposure to Paralytic Shellfish Poisoning (PSP)

    Science.gov (United States)

    Navarro, Jorge M.; González, Katerina; Cisternas, Barbara; López, Jorge A.; Chaparro, Oscar R.; Segura, Cristian J.; Córdova, Marco; Suárez-Isla, Benjamín; Fernandez-Reiriz, María J.; Labarta, Uxio

    2014-01-01

    This study describes the physiological performance of two populations of the razor clam Tagelus dombeii from two geographic areas with different histories of exposure to paralytic shellfish poisoning (PSP) linked to the toxic dinoflagellate Alexandrium catenella. Clams from Melinka-Aysén, which are frequently exposed to PSP, were not affected by the presence of toxins in the diet. However, clams from Corral-Valdivia, which have never been exposed to PSP, exhibited significantly reduced filtration activity and absorption, affecting the energy allocated to scope for growth (SFG). Ammonia excretion and oxygen uptake were not affected significantly by the presence of A. catenella in the diet. Measurements of energy acquisition and expenditure were performed during a 12-day intoxication period. According to three-way repeated measure ANOVAs, the origin of the clams had a highly significant effect on all physiological variables, and the interaction between diet and origin was significant for the clearance and absorption rates and for the scope for growth. The scope for growth index showed similar positive values for both the toxic and non-toxic individuals from the Melinka-Aysén population. However, it was significantly reduced in individuals from Corral-Valdivia when exposed to the diet containing A. catenella. The absence of differences between the physiological response of the toxic and non-toxic clams from Melinka-Aysén may be related to the frequent presence of A. catenella in the environment, indicating that this bivalve does not suffer negative consequences from PSP. By contrast, A. catenella has a negative effect on the physiological performance, primarily on the energy gained from the environment, on T. dombeii from Corral-Valdivia. This study supports the hypothesis that the history of PSP exposure plays an important role in the physiological performance and fitness of filter feeding bivalves. PMID:25153329

  3. Contrasting physiological responses of two populations of the razor clam Tagelus dombeii with different histories of exposure to paralytic shellfish poisoning (PSP.

    Directory of Open Access Journals (Sweden)

    Jorge M Navarro

    Full Text Available This study describes the physiological performance of two populations of the razor clam Tagelus dombeii from two geographic areas with different histories of exposure to paralytic shellfish poisoning (PSP linked to the toxic dinoflagellate Alexandrium catenella. Clams from Melinka-Aysén, which are frequently exposed to PSP, were not affected by the presence of toxins in the diet. However, clams from Corral-Valdivia, which have never been exposed to PSP, exhibited significantly reduced filtration activity and absorption, affecting the energy allocated to scope for growth (SFG. Ammonia excretion and oxygen uptake were not affected significantly by the presence of A. catenella in the diet. Measurements of energy acquisition and expenditure were performed during a 12-day intoxication period. According to three-way repeated measure ANOVAs, the origin of the clams had a highly significant effect on all physiological variables, and the interaction between diet and origin was significant for the clearance and absorption rates and for the scope for growth. The scope for growth index showed similar positive values for both the toxic and non-toxic individuals from the Melinka-Aysén population. However, it was significantly reduced in individuals from Corral-Valdivia when exposed to the diet containing A. catenella. The absence of differences between the physiological response of the toxic and non-toxic clams from Melinka-Aysén may be related to the frequent presence of A. catenella in the environment, indicating that this bivalve does not suffer negative consequences from PSP. By contrast, A. catenella has a negative effect on the physiological performance, primarily on the energy gained from the environment, on T. dombeii from Corral-Valdivia. This study supports the hypothesis that the history of PSP exposure plays an important role in the physiological performance and fitness of filter feeding bivalves.

  4. Recruitment of mud clam Polymesoda erosa (Solander, 1876 in a mangrove habitat of Chorao island, Goa

    Directory of Open Access Journals (Sweden)

    Sandhya Clemente

    2011-06-01

    Full Text Available Habitat-specific settlement success results either from active habitat selection or differential mortality after non-selective settlement. The mud clam Polymesoda erosa (Solander, 1876 is an ecologically and economically important benthic invertebrate with high abundance in the mangrove forests of Chorao Island, Goa, India. A one-year study (Jul 2004-Jul 2005 was conducted to characterize the patterns of post-larval settlement and survival of P. erosa in the mangrove habitat. The mean density of settling post-larvae was 28 no.m-2 with a majority of settlers during Sept 04. The density of adult clams in the landward zone ranged from 7-12 no.m-2 (mean: 9 ± 6 sd; n=122. In the seaward region, adults were completely absent at the low tide level. Higher densities of juveniles observed at the low- and mid-tide levels were assumed to be due to frequent inundation which allowed the young individuals to feed adequately and attain the critical sizes at which vulnerability to physical and biological constraints is substantially reduced, whereas, at high-tide level, increased desiccation may account for the mortality of settlers. It is speculated that initially the settlers settle according to the hydrodynamic conditions for sedimentation; however, adult survival is affected by their recruitment in a suitable habitat (e.g. substrates near Avicennia sp.. Thus, habitat dependent viability during the post-settlement phase could be the best explanation for the non-random, patchy distribution of P. erosa observed in the Chorao mangrove swamp.Um assentamento larval bem sucedido resulta da seleção ativa do habitat pelas larvas ou da mortalidade diferencial destas após o assentamento não seletivo. Nos manguezais da ilha Chorao, Goa, India, a ostra do lodo Polymesoda erosa (Solander, 1876 é um invertebrado muito abundante e de importância econômica. O presente trabalho, realizado durante um ano (julho de 2004 a julho de 2005, visou caracterizar os padr

  5. Effect of acidic electrolyzed water-induced bacterial inhibition and injury in live clam (Venerupis philippinarum) and mussel (Mytilus edulis).

    Science.gov (United States)

    Al-Qadiri, Hamzah M; Al-Holy, Murad A; Shiroodi, Setareh Ghorban; Ovissipour, Mahmoudreza; Govindan, Byju N; Al-Alami, Nivin; Sablani, Shyam S; Rasco, Barbara

    2016-08-16

    The effect of acidic electrolyzed water (AEW) on inactivating Escherichia coli O104:H4, Listeria monocytogenes, Aeromonas hydrophila, Vibrio parahaemolyticus and Campylobacter jejuni in laboratory contaminated live clam (Venerupis philippinarum) and mussel (Mytilus edulis) was investigated. The initial levels of bacterial contamination were: in clam 4.9 to 5.7log10CFU/g, and in mussel 5.1 to 5.5log10CFU/g. Two types of AEW were used for treatment time intervals of 1 and 2h: strong (SAEW) with an available chlorine concentration (ACC) of 20mg/L, pH=3.1, and an oxidation-reduction potential (ORP) of 1150mV, and weak (WAEW) at ACC of 10mg/L, pH=3.55 and ORP of 950mV. SAEW and WAEW exhibited significant inhibitory activity against inoculated bacteria in both shellfish species with significant differences compared to saline solutions treatments (1-2% NaCl) and untreated controls (0h). SAEW showed the largest inhibitory activity, the extent of reduction (log10CFU/g) ranged from 1.4-1.7 for E. coli O104:H4; 1.0-1.6 for L. monocytogenes; 1.3-1.6 for A. hydrophila; 1.0-1.5 for V. parahaemolyticus; and 1.5-2.2 for C. jejuni in both types of shellfish. In comparison, significantly (Pmonocytogenes; 0.6-1.3 for A. hydrophila; 0.7-1.3 for V. parahaemolyticus; and 0.8-1.9 for C. jejuni in both types of shellfish. Among all bacterial strains examined in this study, AEW induced less bacterial injury (~0.1-1.0log10CFU/g) and more inactivation effect. This study revealed that AEW (10-20mg/L ACC) could be used to reduce bacterial contamination in live clam and mussel, which may help control possible unhygienic practices during production and processing of shellfish without apparent changes in the quality of the shellfish. PMID:27208583

  6. 蛤蜊中微量元素含量的测定%Determination of trace elements in Clams

    Institute of Scientific and Technical Information of China (English)

    姜凤

    2014-01-01

    用高压罐硝化样品,以正交试验原理,借助方差分析,利用ICP-AES法测定蛤蜊中Co、Mg、Zn、Fe、Ca、Sr等15种微量元素的含量,方法回收率在96.50%~102.50%之间,相对标准偏差小于2.57%。ICP-AES法具有灵敏度高、简单,快捷等优点,且多元素同时测定,更适合蛤蜊中金属与非金属元素的分析测定。通过实验:蛤蜊中含有丰富的Mg、Zn、Fe、Ca、K、P,还含有Se、Ge、Sr、Mn等微量元素对人体健康极其有益,是营养价值很高的海产品。但近些年,海水被环境造成一定程度的污染,食用时应加以注意。%Samples were digested by high pressure nitrifying pot.Orthogonal test and analysis of variance were applied to the determination of content of 15 kinds of trace elements in clam such as Co,Mg,Zn,Fe,Ca,Sr etc by ICP-AES .The recovery rate of the method is in the range of 96.50%-102.50%. Relative standard deviations is less than 2.57%. ICP-AES method is high sensitivity,convenient, rapid and simultaneous determination of many elements, more suitable for the analysis of clam in metallic and nonmetallic elements determination. Experimental results show that clams are rich in Mg, Zn, Fe, Ca, K, P, also contains Se, Ge, Sr, Mn and other trace elements beneficial to human body extremely. Seafood is high nutritional value, but the current environment seawater caused a certain degree of pollution.Consumption should be noted.

  7. Describing morphological and enzyme polymorphism in the Ribbed Venus Clam Gafrarium tumidum from five marine coastal locations in Mindanao, Philippines

    Directory of Open Access Journals (Sweden)

    Reynaldo A. Leong

    2013-05-01

    Full Text Available This study was conducted to describe morphological variations and enzyme polymorphism inthe Ribbed Venus Clam Gafrarium tumidum from five marine coastal locations in Mindanao, Philippines.Thirteen morphological characters and two enzymes were evaluated following standard methods ofmorphological measurements and enzyme pattern analysis. Results show variations in selectedmorphological characters and in the two enzyme loci among the populations examined. Enzymepolymorphism and the high heterozygosity in the populations examined can be attributed to theexternal fertilization and extended dispersal of planktonic larvae of this bivalve species. Factors such asheterozygote advantage during larval life, and the minimal effects if any of human exploitation canalso be considered to explain the high heterozygote frequencies. Since only a few loci wereinvestigated, it was postulated that the results may be different if a higher number of loci would beincluded in the evaluation of genetic variation in this species.

  8. Baseline of organotin pollution in fishes, clams, shrimps, squids and crabs collected from the west coast of India.

    Science.gov (United States)

    Jadhav, Sangeeta; Bhosale, Darshana; Bhosle, Narayan

    2011-10-01

    Organotins, especially tributyltins (TBT) are highly toxic to many marine organisms. These compounds are introduced in marine waters by ship trafficking, ship scrapping activities, as antifouling compounds and sewage disposal. Marine fishes, crustaceans and molluscans are easily prone to organotins contamination. In view of this, a baseline monitoring study was conducted in order to establish the levels of organotins in edible marine fishes, bivalves, shrimps, squids and crabs collected from Mumbai, Goa and Karwar on the west coast of India. At these locations average organotin concentration found in fishes, clams, shrimps, squids and crabs was 108, 852, 179, 70 and 89 ng Sn g(-1)dw, respectively. In all the samples butyltins dominated over phenyltins. The levels of organotins suggest that all the organisms were contaminated with organotins and their consumption may pose health problems to humans. PMID:21820681

  9. Transcriptomics of in vitro immune-stimulated hemocytes from the Manila clam Ruditapes philippinarum using high-throughput sequencing.

    Directory of Open Access Journals (Sweden)

    Rebeca Moreira

    Full Text Available BACKGROUND: The Manila clam (Ruditapes philippinarum is a worldwide cultured bivalve species with important commercial value. Diseases affecting this species can result in large economic losses. Because knowledge of the molecular mechanisms of the immune response in bivalves, especially clams, is scarce and fragmentary, we sequenced RNA from immune-stimulated R. philippinarum hemocytes by 454-pyrosequencing to identify genes involved in their immune defense against infectious diseases. METHODOLOGY AND PRINCIPAL FINDINGS: High-throughput deep sequencing of R. philippinarum using 454 pyrosequencing technology yielded 974,976 high-quality reads with an average read length of 250 bp. The reads were assembled into 51,265 contigs and the 44.7% of the translated nucleotide sequences into protein were annotated successfully. The 35 most frequently found contigs included a large number of immune-related genes, and a more detailed analysis showed the presence of putative members of several immune pathways and processes like the apoptosis, the toll like signaling pathway and the complement cascade. We have found sequences from molecules never described in bivalves before, especially in the complement pathway where almost all the components are present. CONCLUSIONS: This study represents the first transcriptome analysis using 454-pyrosequencing conducted on R. philippinarum focused on its immune system. Our results will provide a rich source of data to discover and identify new genes, which will serve as a basis for microarray construction and the study of gene expression as well as for the identification of genetic markers. The discovery of new immune sequences was very productive and resulted in a large variety of contigs that may play a role in the defense mechanisms of Ruditapes philippinarum.

  10. Northern Marshall Islands radiological survey: radionuclide concentrations in fish and clams and estimated doses via the marine pathway

    International Nuclear Information System (INIS)

    The survey consisted, in part, of an aerial radiological reconnaissance to map the external gamma-ray exposure rates. As a secondary phase, terrestrial and marine samples were collected to assess the radiological dose from pertinent food chains to atoll inhabitants. The marine sample collection, processing, and dose assessment methodology are presented as well as the concentration data for 90Sr, 137Cs, 238Pu, 239+240Pu, 241Am, and any of the other gamma emitters in fish and clam muscle tissue from the different species collected. Doses are calculated from the average radionuclide concentrations in fish and clam muscle tissue assuming an average daily intake of 200 and 10 g, respectivelty. The 90Sr concentration in muscle tissue is very low and there is little difference in the average concentrations from the different fish from different atolls or islands. The 239+240Pu concentration in the muscle tissue of all reef species, however, is higher than that in pelagic lagoon fish. In contrast, 137Cs concentrations are lowest in the muscle tissue of the bottom-feeding reef species and highest in pelagic logoon fish. Recent measurements of radionuclide concentrations in fish muscle tissue and other marine dietary items from international sources show that the average concentrations in species from the Marshall Islands are comparable to those in fish typically consumed as food in the United States and are generally lower than those in most international marine dietary items. The whole-body dose rates based on continuous consumption of 200 g/d of fish range from 0.028 to 0.1 mrem/y; the bone-marrow dose rates range from 0.029 to 0.12 mrem/y. The dose commitment, or 30-y integral doses, range from 0.00063 to 0.0022 rem for the whole body and from 0.00065 to 0.0032 rem for the bone marrow

  11. Metals bioaccumulation and biomarkers responses in the Neotropical freshwater clam Anodontites trapesialis: Implications for monitoring coal mining areas.

    Science.gov (United States)

    Oliveira, Luciana Fernandes de; Cabral, Millena Terezinha; Vieira, Carlos Eduardo Delfino; Antoniazzi, Matheus Henrique; Risso, Wagner Ezequiel; Martinez, Claudia Bueno Dos Reis

    2016-11-15

    As one of the most impactful industries, coal mining can promote several alterations at surrounding environment. In surface water, elevated concentrations of metals like Mn, Zn, Fe and Al are often observed. Thus, the aim of this study was to investigate the bioaccumulation and the sub-lethal effects of these metals on various organs of the Neotropical bivalve Anodontites trapesialis confined along a stream located near a coal mine, in order to assess a set of biomarkers that could be used for effectively monitoring coal mining areas. Clams were caged, for 96h, at two sites located upstream (Up1 and Up2) and two sites downstream (Dw1 and Dw2) from the mine. Metals bioaccumulation was determined in gills, mantle, digestive gland, muscle and hemolymph and the following biomarkers were measured in A. trapesialis tissues: total antioxidant capacity against peroxyl radicals, metallothionein content, lipid peroxidation (LPO), proteins carbonylation, glutathione S-transferase activity, superoxide dismutase activity and acetylcholinesterase (AChE) activity. The results showed that Al and Fe bioaccumulation in the gills and hemolymph, Al bioaccumulation in the mantle and muscle, increased LPO in the gills (Dw1 and Dw2) and mantle (Dw1), as well as reduced AChE activity in the muscle (Dw1 and Dw2) should be considered effective biomarkers for monitoring coal mining areas. A. trapesialis proved to be an efficient biological model, considering that biomarkers responses were observed in the clams after only 96h of confinement at Dw sites, accordingly this species could be a good candidate for monitoring Neotropical freshwaters. PMID:27453135

  12. Exclusive localization of carbonic anhydrase in bacteriocytes of the deep-sea clam Calyptogena okutanii with thioautotrophic symbiotic bacteria.

    Science.gov (United States)

    Hongo, Yuki; Nakamura, Yoshimitsu; Shimamura, Shigeru; Takaki, Yoshihiro; Uematsu, Katsuyuki; Toyofuku, Takashi; Hirayama, Hisako; Takai, Ken; Nakazawa, Masatoshi; Maruyama, Tadashi; Yoshida, Takao

    2013-12-01

    Deep-sea Calyptogena clams harbor thioautotrophic intracellular symbiotic bacteria in their gill epithelial cells. The symbiont fixes CO2 to synthesize organic compounds. Carbonic anhydrase (CA) from the host catalyzes the reaction CO2 + H2O ↔ HCO3(-) + H(+), and is assumed to facilitate inorganic carbon (Ci) uptake and transport to the symbiont. However, the localization of CA in gill tissue remains unknown. We therefore analyzed mRNA sequences, proteins and CA activity in Calyptogena okutanii using expression sequence tag, SDS-PAGE and LC-MS/MS. We found that acetazolamide-sensitive soluble CA was abundantly expressed in the gill tissue of C. okutanii, and the enzyme was purified by affinity chromatography. Mouse monoclonal antibodies against the CA of C. okutanii were used in western blot analysis and immunofluorescence staining of the gill tissues of C. okutanii, which showed that CA was exclusively localized in the symbiont-harboring cells (bacteriocytes) in gill epithelial cells. Western blot analysis and measurement of activity showed that CA was abundantly (26-72% of total soluble protein) detected in the gill tissues of not only Calyptogena clams but also deep-sea Bathymodiolus mussels that harbor thioautotrophic or methanotrophic symbiotic bacteria, but was not detected in a non-symbiotic mussel, Mytilus sp. The present study showed that CA is abundant in the gill tissues of deep-sea symbiotic bivalves and specifically localizes in the cytoplasm of bacteriocytes of C. okutanii. This indicates that the Ci supply process to symbionts in the vacuole (symbiosome) in bacteriocytes is essential for symbiosis. PMID:24031050

  13. Toxicological responses of the hard clam Meretrix meretrix exposed to excess dissolved iron or challenged by Vibrio parahaemolyticus

    International Nuclear Information System (INIS)

    Highlights: • Fe accumulated in hepatopancreas tissues after iron-enriched exposure. • Ferritin expression was positively correlated with iron concentration in seawater. • Ferritin appears to be involved in iron homeostasis and immune defense mechanism of M. meretrix. • mRNAs of cytokine genes responded faster than antioxidant enzyme genes in immune defense mechanism. • The study gives a new potential biomarker for monitoring iron levels in seawater. - Abstract: The responses of genes encoding defense components such as ferritin, the lipopolysaccharide-induced tumor necrosis factor-alpha factor (LITAF), the inhibitor of nuclear factor-κB (IκB), metallothionein, and glutathione peroxidase were assessed at the transcriptional level in order to investigate the toxicological and immune mechanism of the hard clam Meretrix meretrix (HCMM) following challenge with iron or a bacterium (Vibrio parahaemolyticus). Fe dissolved in natural seawater led to an increase of Fe content in both the hepatopancreas and gill tissue of HCMM between 4 and 15 days of exposure. The ferritin gene responded both transcriptionally as indicated by real-time quantitative PCR and translationally as shown by western blotting results to iron exposure and both transcriptional and translational ferritin expression in the hepatopancreas had a positive correlation with the concentration of dissolved iron in seawater. Both iron and V. parahaemolyticus exposure triggered immune responses with similar trends in clam tissues. There was a significant post-challenge mRNA expression of LITAF and IκB at 3 h, ferritin at 24 h, and metallothionein and glutathione peroxidase at 48 h. This behavior might be linked to their specific functions in physiological processes. These results suggested that similar signaling pathways were triggered during both iron and V. parahaemolyticus challenges. Here, we indicated that the ferritin of Meretrix meretrix was an intermediate in the pathway of iron homeostasis

  14. Toxicological responses of the hard clam Meretrix meretrix exposed to excess dissolved iron or challenged by Vibrio parahaemolyticus

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Qing [State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen 361102 (China); State Key Laboratory of Marine Environmental Science, School of Ocean and Earth Science, Xiamen University, Xiamen 361102 (China); Zhang, Yong [Department of Chemistry, College of Chemistry and Chemical Engineering, and the Key Laboratory of Chemical Biology of Fujian Province, Xiamen University, Xiamen 361102 (China); Peng, Hui-Fang [State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen 361102 (China); Ke, Cai-Huan, E-mail: chke@xmu.edu.cn [State Key Laboratory of Marine Environmental Science, School of Ocean and Earth Science, Xiamen University, Xiamen 361102 (China); Huang, He-Qing, E-mail: hqhuang@xmu.edu.cn [State Key Laboratory of Stress Cell Biology, School of Life Science, Xiamen University, Xiamen 361102 (China); State Key Laboratory of Marine Environmental Science, School of Ocean and Earth Science, Xiamen University, Xiamen 361102 (China); Department of Chemistry, College of Chemistry and Chemical Engineering, and the Key Laboratory of Chemical Biology of Fujian Province, Xiamen University, Xiamen 361102 (China)

    2014-11-15

    Highlights: • Fe accumulated in hepatopancreas tissues after iron-enriched exposure. • Ferritin expression was positively correlated with iron concentration in seawater. • Ferritin appears to be involved in iron homeostasis and immune defense mechanism of M. meretrix. • mRNAs of cytokine genes responded faster than antioxidant enzyme genes in immune defense mechanism. • The study gives a new potential biomarker for monitoring iron levels in seawater. - Abstract: The responses of genes encoding defense components such as ferritin, the lipopolysaccharide-induced tumor necrosis factor-alpha factor (LITAF), the inhibitor of nuclear factor-κB (IκB), metallothionein, and glutathione peroxidase were assessed at the transcriptional level in order to investigate the toxicological and immune mechanism of the hard clam Meretrix meretrix (HCMM) following challenge with iron or a bacterium (Vibrio parahaemolyticus). Fe dissolved in natural seawater led to an increase of Fe content in both the hepatopancreas and gill tissue of HCMM between 4 and 15 days of exposure. The ferritin gene responded both transcriptionally as indicated by real-time quantitative PCR and translationally as shown by western blotting results to iron exposure and both transcriptional and translational ferritin expression in the hepatopancreas had a positive correlation with the concentration of dissolved iron in seawater. Both iron and V. parahaemolyticus exposure triggered immune responses with similar trends in clam tissues. There was a significant post-challenge mRNA expression of LITAF and IκB at 3 h, ferritin at 24 h, and metallothionein and glutathione peroxidase at 48 h. This behavior might be linked to their specific functions in physiological processes. These results suggested that similar signaling pathways were triggered during both iron and V. parahaemolyticus challenges. Here, we indicated that the ferritin of Meretrix meretrix was an intermediate in the pathway of iron homeostasis

  15. Persistent organic pollutants (POPs) in populations of the clam Chione californiensis in coastal lagoons of the Gulf of California.

    Science.gov (United States)

    Vargas-González, Héctor H; Méndez-Rodríguez, Lía C; García-Hernández, Jaqueline; Mendoza-Salgado, Renato A; Zenteno-Savín, Tania; Arreola-Lizárraga, José A

    2016-07-01

    This study examines the potential public health risk due to the massive use of organochlorine pesticides (OCs) in agriculture in the Gulf of California. Specimens of the clam Chione californiensis were collected from three coastal lagoons (Yavaros, Altata and Reforma). Sites were classified as polluted/nonpolluted based on the presence/absence of OCs as an indicator of the persistence of these pollutants; in polluted sites, the time elapsed since pesticide application (past or recent) was estimated. Screening values (SV) for protecting human health as per the U.S. Environmental Protection Agency (EPA) were used for risk assessment. OCs detected were ranked according to frequency of occurrence as follows: γ-chlordane (75%) > endrin (54%) > aldrin (48%) > heptachlor, and dichlorodiphenyl-trichloroethane (DDE) (37%) > β-heptachlor epoxide (30%) > lindane (α-BHC, δ-BHC) and endosulphan I (≤ 6%). Specifically, OCs detected at the highest concentration were heptachlor in Yavaros (0.0168 µgg(-1)) and Altata (0.0046 µgg(-1)), and aldrin in Reforma (0.0019 µgg(-1)). β-Heptachlor epoxide in Altata and Reforma was the only OC with a concentration exceeding the EPA Screening Value. From our results and based on the monthly consumption limit set forth by EPA, the maximum safe consumption of clams to avoid a carcinogenic risk derived from β-heptachlor epoxide in the fishing villages of Yavaros and Altata is 4 servings per month (1 serving = 0.227 kg) by a 70-kg person. These findings suggest that concentrations of OCs and their isomers in C. californiensis populations reflect environmental persistence as well as recent inputs of OCs into coastal lagoons in the Gulf of California. PMID:27050678

  16. Inactivation of Vibrio cholerae O1 El Tor inoculated into Peruvian ''choro'' mussels (Aulacomya ater) and two species of clams (Argopecten purpuratus and Gari solida) using medium-dose irradiation

    International Nuclear Information System (INIS)

    The radiation decimal reduction dose (D10) for Vibrio cholerae O1 biotype El Tor inoculated through the natural feeding system into three species of bivalve mollusks from the Peruvian Pacific coast: ''choro'' mussels (Aulacome ater), ''abanico'' clams (Argopecten purpuratus), and common clams (Gari solida), was determined in vivo. The D10 value obtained in vivo was 0.14 kGy in all mollusks tested. Concurrent studies conducted to determine the potential use of irradiation to extend the microbiological shelf-life of the mollusks during post-irradiation storage at 0-1 deg. C indicated that a dose of 1.0 kGy was optimal for choro mussels and abanico clams, whereas 2.0 kGy produced the best results when treating common clams. Shelf-life extension thus achieved was 31 days for choro mussels, 16 days for abanico clams, and 21 days for common clams. Non-irradiated control samples of all mollusks spoiled after 17 days of refrigerated storage. There were no significant (p<.05) adverse effects from the application of the optimal radiation treatments on the sensory characteristics (i.e. appearance, odor, flavor, and texture) of the mollusks. Total volatile basic nitrogen (VBN) and pH values were examined for use as indexes of seafood freshness. (author)

  17. Seasonal Changes in Glycogen Contents in Various Tissues of the Edible Bivalves, Pen Shell Atrina lischkeana, Ark Shell Scapharca kagoshimensis, and Manila Clam Ruditapes philippinarum in West Japan

    OpenAIRE

    Tatsuya Yurimoto

    2015-01-01

    The types of tissues accumulating glycogen and seasonal changes in glycogen content were investigated in the following shell species: pen shell Atrina lischkeana, ark shell Scapharca kagoshimensis, and Manila clam Ruditapes philippinarum. Comparison of the results showed that the adductor muscle or foot was the main glycogen reservoir and the levels varied seasonally. The adductor muscle in the pen shell showed higher glycogen content during spring and lower content during autumn. The ark she...

  18. Exposure to2,2',4,4'-tetrabromodiphenyl ether (BDE-47) alters thyroid hormone levels and thyroid hormone-regulated gene transcription in manila clam Ruditapes philippinarum.

    Science.gov (United States)

    Song, Ying; Miao, Jingjing; Pan, Luqing; Wang, Xin

    2016-06-01

    Polybrominated diphenyl ethers (PBDEs) have the potential to disturb the thyroid endocrine system in vertebrates, but little is known about the disruptive effects of PBDEs on marine bivalves. In this study, we first examined the effects of BDE-47 exposure on growth of juvenile manila clams Ruditapes philippinarum. The result showed that 1.0 and 10 μg L(-1) BDE-47 had adverse effects on 14-d shell-length growth of juvenile clams. Then, one-year-old adult clams were exposed to 0, 0.1 and 1 μg L(-1) BDE-47 for 15 d. BDE-47 (1 μg L(-1)) exposure caused significant decreases of total T4 (thyroxine) by 40% and T3 (3,5,3'-triiodothyronine) by 75% concentrations in haemolymph of the clams. Transcription of genes involved in thyroid hormone synthesis and metabolism were also studied by quantitative RT-PCR. Gene expression levels of sodium iodide symporter (rp-NIS), iodothyronine deiodinase (rp-Deio) and thyroid peroxidase (rp-TPO) were increased in a dose-dependent manner at day 5 and day 10, while monocarboxylate transporter 8 (rp-Mct8) was downregulated at day 5, day 10 and day 15. The effect and preliminary mechanism observed in the present study were consistent with the results from previous studies on rodent and fish, implying that exposure to BDE-47 may pose threat to thyroid hormone homeostasis in bivalves through thyroid synthesis and metabolism pathways. This study may provide a first step towards understanding of the thyroid function disruptive effects of PBDEs on marine bivalves and the underlying mechanism across taxonomic groups and phyla. PMID:26943874

  19. Phytoplankton growth balanced by clam and zooplankton grazing and net transport into the low-salinity zone of the San Francisco Estuary

    Science.gov (United States)

    Kimmerer, Wim J.; Thompson, Janet K.

    2014-01-01

    We estimated the influence of planktonic and benthic grazing on phytoplankton in the strongly tidal, river-dominated northern San Francisco Estuary using data from an intensive study of the low salinity foodweb in 2006–2008 supplemented with long-term monitoring data. A drop in chlorophyll concentration in 1987 had previously been linked to grazing by the introduced clam Potamocorbula amurensis, but numerous changes in the estuary may be linked to the continued low chlorophyll. We asked whether phytoplankton continued to be suppressed by grazing and what proportion of the grazing was by benthic bivalves. A mass balance of phytoplankton biomass included estimates of primary production and grazing by microzooplankton, mesozooplankton, and clams. Grazing persistently exceeded net phytoplankton growth especially for larger cells, and grazing by microzooplankton often exceeded that by clams. A subsidy of phytoplankton from other regions roughly balanced the excess of grazing over growth. Thus, the influence of bivalve grazing on phytoplankton biomass can be understood only in the context of limits on phytoplankton growth, total grazing, and transport.

  20. Single-laboratory validation of a refined AOAC HPLC method 2005.06 for oysters, cockles, and clams in U.K. shellfish.

    Science.gov (United States)

    Turner, Andrew D; Hatfield, Robert G; Rapkova-Dhanji, Monika; Norton, Deirdre M; Algoet, Myriam; Lees, David N

    2010-01-01

    In 2009, a refined HPLC method based on AOAC Official Method 2005.06 was developed and validated for the determination of paralytic shellfish poisoning (PSP) in mussels. A single-laboratory validation study of this method was undertaken here for the analysis of PSP toxins in oysters, cockles, clams, and razor clams. The method was characterized for selectivity, sensitivity, linearity, precision, repeatability, recovery, ruggedness, and uncertainty of measurement. Validation data were utilized to determine method performance characteristics for non-mussel bivalves for all commercially available certified reference toxins, extending the method to dcNEO and dcGTX2,3, where available. A period of parallel testing of oysters, cockles, and clams enabled a comparison of sample toxicities obtained using mouse bioassay (MBA) and HPLC methodologies, although only a very low number of PSP-positive samples were obtained through the United Kingdom official control monitoring program. Results from the MBA and HPLC methods were well-correlated for PSP-negative samples, but the low number of naturally contaminated PSP-positive samples has prevented any comparative statistical assessment of method performance for non-mussels between the two official methods. However, some evidence for potentially significant differences in total saxitoxin equivalents obtained by the two methods in some species has highlighted the need for further comparative testing in non-mussel samples to be conducted prior to implementation of the HPLC method in routine official control monitoring programs. PMID:21140661

  1. Vacancy-type defects and hardness of helium implanted CLAM steel studied by positron-annihilation spectroscopy and nano-indentation technique

    International Nuclear Information System (INIS)

    Highlights: ► Helium implantation is performed to CLAM steel at different temperatures. ► Positron annihilation is used to investigate vacancy-type defects. ► Nano-hardness is investigated to study irradiation induced hardening. ► Vacancy–helium complexes are main defects after implantation. ► Both helium–vacancy clusters and helium bubbles contribute to hardening. - Abstract: China Low Activation Martensitic (CLAM) steel was implanted with helium up to 1e + 16/cm2 at 300–873 K using 140 keV helium ions. Vacancy-type defects induced by implantation were investigated with positron beam Doppler broadening technique, and then nano-hardness measurements were performed to investigate helium-induced hardening effect. He implantation produced a large number of vacancy-type defects in CLAM steel, and the concentration of vacancy-type defects decreased with increasing temperature. Vacancy–helium complexes were main defects at different temperatures. Irradiation induced hardening was observed at all irradiation temperatures, and the peak value of hardness was at 473 K. The result suggested that both vacancy–helium complexes and helium bubbles had contribution to irradiation induced hardening. The decomposition and annihilation of irradiation-induced defects became more and more significant with increasing temperature, which induced the increment of hardness became more and more small.

  2. Dicty_cDB: Contig-U03036-1 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available .. 36 0.81 6 ( CP000485 ) Bacillus thuringiensis str. Al Hakam, complete ge... 38 0.82 17 ( CU407224 ) Pig D...kfg*eqc*lv *rvvqifvihliyvymvstfyf*iellisvksirkl*slqfhsvvvvvevivvvverkss fneslsasqasdlssnssvstnsnelqsfkkkalill...DLMGFDDNFINLKESIINDAS DISEINELIKKKEQQQPPPQQPPPPPSSP*iiilnlrvlkiqqdviikllkfg*eqc*lv *rvvqifvihliyvymvstfyf*iell...Lat... 52 0.044 1 ( EY342734 ) CAWZ12083.rev CAWZ Helobdella robusta Primary Lat... 52 0.044 1 ( CP000942 ) Ureapl...a mercenaria microsatellite Mme277 seque... 50 0.17 1 ( AC149937 ) Strongylocentrotus purpur

  3. Effect of post-weld heat treatment on the mechanical properties of electron beam welded joints for CLAM steel

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qingsheng, E-mail: chunjing.li@fds.org.cn; Zheng, Shuhui; Liu, Shaojun; Li, Chunjing; Huang, Qunying

    2013-11-15

    In this paper the microstructure and mechanical properties of electron beam weld (EBW) joints for China low activation martensitic (CLAM) steel, which underwent a series of different post weld heat treatments (PWHTs) were studied. The aim of the study was to identify suitable PWHTs that give a good balance between strength and toughness of the EBW joints. The microstructural analyses were performed by means of optical microscope (OM) and scanning electron microscope (SEM). The mechanical properties were determined via tensile tests and Charpy impact tests. The results showed that the tensile strength of the as-weld joint (i.e. without any PWHT) were close to that of the base metal, but the impact toughness was only 13% of that of the base metal due to the existence of a delta-ferrite microstructure. To achieve a significant improvement in toughness a PWHT needs to be performed. If a one-step PWHT is applied tempering at 760 °C for 2 h gives EBW joints with high strength at a still acceptable toughness level. If a two-step PWHT is applied, a process involving quenching at 980 °C for 0.5 h followed by tempering at 740 °C or 760 °C for 2 h gives EBW joints with high strength and toughness properties. Whenever possible a two-step PWHT should be applied in favor of a one-step process, because of higher resulting strength and toughness properties.

  4. Effect of post-weld heat treatment on the mechanical properties of electron beam welded joints for CLAM steel

    Science.gov (United States)

    Wu, Qingsheng; Zheng, Shuhui; Liu, Shaojun; Li, Chunjing; Huang, Qunying

    2013-11-01

    In this paper the microstructure and mechanical properties of electron beam weld (EBW) joints for China low activation martensitic (CLAM) steel, which underwent a series of different post weld heat treatments (PWHTs) were studied. The aim of the study was to identify suitable PWHTs that give a good balance between strength and toughness of the EBW joints. The microstructural analyses were performed by means of optical microscope (OM) and scanning electron microscope (SEM). The mechanical properties were determined via tensile tests and Charpy impact tests. The results showed that the tensile strength of the as-weld joint (i.e. without any PWHT) were close to that of the base metal, but the impact toughness was only 13% of that of the base metal due to the existence of a delta-ferrite microstructure. To achieve a significant improvement in toughness a PWHT needs to be performed. If a one-step PWHT is applied tempering at 760 °C for 2 h gives EBW joints with high strength at a still acceptable toughness level. If a two-step PWHT is applied, a process involving quenching at 980 °C for 0.5 h followed by tempering at 740 °C or 760 °C for 2 h gives EBW joints with high strength and toughness properties. Whenever possible a two-step PWHT should be applied in favor of a one-step process, because of higher resulting strength and toughness properties.

  5. Genetic variation and differentiation in wide ranging populations of razor clam ( Sinonovacula constricta) inferred from AFLP markers

    Science.gov (United States)

    Wang, Jingbo; Li, Qi; Kong, Lingfeng

    2010-09-01

    The genetic variation and differentiation of the razor clam Sinonovacula constricta distributed along the coast of China were studied through amplified fragment length polymorphism (AFLP) analysis. Six primer combinations generated 193 fragments. The H e values varied from 0.322 to 0.463 and the percentage of polymorphic loci ranged from 74.1% to 98.4%, which indicates a high level of genetic diversity. Cluster analysis by Nei’s pairwise distance grouped all specimens by geographical origins. AMOVA consistently showed that genetic variation among populations was 8.71%, and most of the variation came from the genetic variation within populations (91.29%). Genetic differentiation among the six populations was moderate; pairwise F ST ranged from 0.0282 to 0.1480, which indicated that S. constricta populations along the coast of China are genetically connected. Among all the six populations, the Beihai population is the mostly differentiated from the others, suggesting that Hainan Island and Leizhou Peninsula act as barriers to gene flow. All populations abide isolation by distance model as indicated by Mantel test, except for ZS (Zhoushan) and YQ (Yueqing) populations. Information obtained in this study will provide guidelines for conservation and fishery management of this species in the future.

  6. Impact of hypoxia on hemolymph contamination by uranium in an aquatic animal, the freshwater clam Corbicula fluminea

    Energy Technology Data Exchange (ETDEWEB)

    Tran, Damien [Universite Bordeaux 1, CNRS, UMR 5805 EPOC, Place du Dr Peyneau, 33120 Arcachon (France)], E-mail: d.tran@epoc.u-bordeaux1.fr; Massabuau, Jean-Charles [Universite Bordeaux 1, CNRS, UMR 5805 EPOC, Place du Dr Peyneau, 33120 Arcachon (France)], E-mail: jc.massabuau@epoc.u-bordeaux1.fr; Garnier-Laplace, Jacqueline [Laboratoire de Radioecologie et Ecotoxicologie, Institut de Radioprotection et de Surete Nucleaire, Cadarache, Bat. 186, BP3, 13115 Saint Paul-Lez-Durance, Cedex (France)], E-mail: Jacqueline.Garnier-Laplace@irsn.fr

    2008-12-15

    Multi-stress situations are a major question and low-oxygenated waters (hypoxia) are a growing problem. Importantly, hypoxia stimulates the ventilatory flow rate in aquatic animals and this increases gill exposure to contaminants. Surprisingly, in the freshwater clam Corbicula fluminea, this is associated with increased bioaccumulation of uranium in gills but not in deep tissues. We searched for an explanation by analyzing hemolymph U-transport in Corbicula exposed to 0.36 {mu}M dissolved uranium at various O{sub 2}-levels for 10 days. In hypoxia, one observed an increased U concentration in the arterial hemolymph flowing from gills to tissues but this was not associated with an increased U concentration in the venous hemolymph nor in the other tissues. We conclude that the cardiac flow rate must have decreased to explain this absence of over-accumulation. In addition to its already known deleterious effects, uranium can thus deeply impair cardiac flow rate in exposed aquatic animals during multi-stress exposures. - Uranium contamination enhanced by hypoxia can deeply impair circulatory hemolymph flow in aquatic animals.

  7. Combining ability and heterosis analysis over two environments in a diallel cross of three families of the clam Meretrix meretrix

    Institute of Scientific and Technical Information of China (English)

    DAI Ping; WANG Hongxia; XIAO Guoqiang; LIU Baozhong

    2014-01-01

    A 3×3 complete diallel cross comprising three families of the clam Meretrix meretrix (P1, P2 and P3) was used to determine the combining ability of parental families and heterosis of F1 under indoor and open-air environments for growth traits. Analysis of variance for shell length and whole body weight indicated highly significant cross effects, environment effects and the interaction of cross by environment. General combining ability (GCA) and specific combing ability exhibited great variation among crosses and between two environments. Pooled over environments, P2 was the top combiner among the three parental families for both traits studied. The cross of P1 and P3 had the highest SCA. Additionally, significant reciprocal effects were observed. For individual environment, about half of the crossbred combinations showed favorable Mid-parent heterosis (MPH) (>1%) for the shell length and whole body weight. Our data has shown that non-additive genetic and reciprocal effects constituted the major sources of genetic variation for both shell length and whole body weight, which indicates that crossbreeding among selective families could further explore the heterotic effects.

  8. Impact of hypoxia on hemolymph contamination by uranium in an aquatic animal, the freshwater clam Corbicula fluminea

    International Nuclear Information System (INIS)

    Multi-stress situations are a major question and low-oxygenated waters (hypoxia) are a growing problem. Importantly, hypoxia stimulates the ventilatory flow rate in aquatic animals and this increases gill exposure to contaminants. Surprisingly, in the freshwater clam Corbicula fluminea, this is associated with increased bioaccumulation of uranium in gills but not in deep tissues. We searched for an explanation by analyzing hemolymph U-transport in Corbicula exposed to 0.36 μM dissolved uranium at various O2-levels for 10 days. In hypoxia, one observed an increased U concentration in the arterial hemolymph flowing from gills to tissues but this was not associated with an increased U concentration in the venous hemolymph nor in the other tissues. We conclude that the cardiac flow rate must have decreased to explain this absence of over-accumulation. In addition to its already known deleterious effects, uranium can thus deeply impair cardiac flow rate in exposed aquatic animals during multi-stress exposures. - Uranium contamination enhanced by hypoxia can deeply impair circulatory hemolymph flow in aquatic animals

  9. Fine-scale spatial distribution of the common lugworm Arenicola marina, and effects of intertidal clam fishing

    Science.gov (United States)

    Boldina, Inna; Beninger, Peter G.

    2014-04-01

    Despite its ubiquity and its role as an ecosystem engineer on temperate intertidal mudflats, little is known of the spatial ecology of the lugworm Arenicola marina. We estimated lugworm densities and analyzed the spatial distribution of A. marina on a French Atlantic mudflat subjected to long-term clam digging activities, and compared these to a nearby pristine reference mudflat, using a combination of geostatistical techniques: point-pattern analysis, autocorrelation, and wavelet analysis. Lugworm densities were an order of magnitude greater at the reference site. Although A. marina showed an aggregative spatial distribution at both sites, the characteristics and intensity of aggregation differed markedly between sites. The reference site showed an inhibition process (regular distribution) at distances fishing-impacted vs. the non-impacted site reflect similar findings for other components of these two mudflat ecosystems, suggesting common community-level responses to prolonged mechanical perturbation: a decrease in naturally-occurring aggregation. This change may have consequences for basic biological characteristics such as reproduction, recruitment, growth, and feeding.

  10. [Somatic condition of the clam Polymesoda solida (Veneroidea: Corbiculidae) in the rainy season of the Salamanca Island Natural Park, Colombian Caribbean].

    Science.gov (United States)

    De La Hoz Aristizábal, María Virginia

    2010-03-01

    The estuarine clam Polymesoda solida is the main fishery resource in the Salamanca Island Natural Park. I sampled the clam in three interconnected lagoons (Poza Verde, El Torno and Atascosa) during the rainy period (April to November 2004). Sixty individuals were monthly collected by hand on each lagoon; 30 to analyze two condition indexes (relationship between body and shell weight and between soft dry and wet weight), yield (meat percentage) and length-weight relationships. Maturity of female gonad smears was assessed on the remaining individuals. Measures of salinity, temperature, pH, dissolved oxygen, transparency and depth, were also taken at the collection places. Increases of the condition indexes occurred when the Magdalena River showed some decreases in its level, especially at Poza Verde and El Torno. The condition indexes were higher at 27-33 mm, (range where maturity size was reached). Clams from Poza Verde, the lagoon nearest to the Magdalena River, had the highest values in condition indexes, yield, fresh weight and maturity frequency. Yield was directly correlated to the condition indexes and sexual maturity. The condition index (body weight/shell weight) showed a highest multiple regression coefficient with salinity, pH and transparency (R2=74%), indicating the relevance of the hydrological regime in the regulation of the condition of the organisms. P. solida seems to be more adapted to the lowest salinities of the system (0.0-0.4), corresponding to Poza Verde, where the influence of the Magdalena river is more direct and steady. Additionally, differences found between sites in the assessed variables, emphasize the importance of considering spatial heterogeneity of this kind of lagoon estuaries, and should be taken into account for future fisheries management in the rainy period and conservation of P. solida populations. PMID:20411712

  11. Effects of ocean acidification driven by elevated CO2 on larval shell growth and abnormal rates of the venerid clam, Mactra veneriformis

    Science.gov (United States)

    Kim, Jee-Hoon; Yu, Ok Hwan; Yang, Eun Jin; Kang, Sung-Ho; Kim, Won; Choy, Eun Jung

    2016-03-01

    The venerid clam (Mactra veneriformis Reeve 1854) is one of the main cultured bivalve species in intertidal and shallow subtidal ecosystems along the west coast of Korea. To understand the effects of ocean acidification on the early life stages of Korean clams, we investigated shell growth and abnormality rates and types in the D-shaped, umbonate veliger, and pediveliger stages of the venerid clam M. veneriformis during exposure to elevated seawater pCO2. In particular, we examined abnormal types of larval shell morphology categorized as shell deformations, shell distortions, and shell fissures. Specimens were incubated in seawater equilibrated with bubbled CO2-enriched air at (400±25)×10-6 (ambient control), (800±25)×10-6 (high pCO2), or (1 200±28)×10-6 (extremely high pCO2), the atmospheric CO2 concentrations predicted for the years 2014, 2084, and 2154 (70-year intervals; two human generations), respectively, in the Representative Concentration Pathway (RCP) 8.5 scenario. The mean shell lengths of larvae were significantly decreased in the high and extremely high pCO2 groups compared with the ambient control groups. Furthermore, under high and extremely high pCO2 conditions, the cultures exhibited significantly increased abundances of abnormal larvae and increased severity of abnormalities compared with the ambient control. In the umbonate veliger stage of the experimental larvae, the most common abnormalities were shell deformations, distortions, and fissures; on the other hand, convex hinges and mantle protuberances were absent. These results suggest that elevated CO2 exerts an additional burden on the health of M. veneriformis larvae by impairing early development.

  12. Impact assessment of agricultural inputs into a Mediterranean coastal lagoon (Mar Menor, SE Spain) on transplanted clams (Ruditapes decussatus) by biochemical and physiological responses.

    Science.gov (United States)

    Campillo, Juan A; Albentosa, Marina; Valdés, N Juliana; Moreno-González, Rubén; León, Víctor M

    2013-10-15

    The Mar Menor is a coastal lagoon threatened by the development of intensive agriculture in the surrounding areas. Large amounts of pesticides from these areas are discharged into El Albujón, a permanent watercourse flowing into the lagoon. We have used a multi-biomarker approach to assess the biological effects of agricultural pollution on a bivalve species. Biomarkers indicative of neurotoxicity (acetylcholinesterase, AChE), oxidative stress (catalase, CAT; glutathione reductase, GR and lipid peroxidation, LPO), phase II biotransformation of xenobiotics (glutathione S-transferase, GST) and physiological stress (scope for growth, SFG) were measured in clams transplanted to four sites of the lagoon (two reference sites and two sites affected by the dispersion of the effluent of the El Albujón), for exposure periods of 7 and 22 days. The hazards of this effluent were also examined by simultaneously measuring up to 83 contaminants (pesticides, PCBs, PAHs and others) in samples of fresh water from the watercourse mouth and seawater from the deployed sites, as well as the bioaccumulation of organochlorinated compounds and PAHs in the transplanted animals. Biomarker responses showed marked differences between reference and affected sites after 7 and 22 days. However it was only after 22 days that principal component analysis (PCA) of the biomarker responses distinguished between clams deployed in sites affected by the dispersion of the effluent of the watercourse and those from the reference sites. The chemical analysis of water showed high concentrations of pesticides close to El Albujón watercourse mouth, with the greatest input flux corresponding to the organophosphate chlorpyrifos, followed by pendimethalin and naphthalene, and at lower levels acenaphthene, terbuthylazine-desethyl and chlorpyrifos-methyl. In this regard, PCA analysis showed that the biological effects of the mixture of pesticides in caged clams after 22 days were reduced levels of AchE and SFG

  13. A microarray-based analysis of gametogenesis in two Portuguese populations of the European clam Ruditapes decussatus.

    Directory of Open Access Journals (Sweden)

    Joana Teixeira de Sousa

    Full Text Available The European clam, Ruditapes decussatus is a species with a high commercial importance in Portugal and other Southern European countries. Its production is almost exclusively based on natural recruitment, which is subject to high annual fluctuations. Increased knowledge of the natural reproductive cycle of R. decussatus and its molecular mechanisms would be particularly important in providing new highly valuable genomic information for better understanding the regulation of reproduction in this economically important aquaculture species. In this study, the transcriptomic bases of R. decussatus reproduction have been analysed using a custom oligonucleotide microarray representing 51,678 assembled contigs. Microarray analyses were performed in four gonadal maturation stages from two different Portuguese wild populations, characterized by different responses to spawning induction when used as progenitors in hatchery. A comparison between the two populations elucidated a specific pathway involved in the recognition signals and binding between the oocyte and components of the sperm plasma membrane. We suggest that this pathway can explain part of the differences in terms of spawning induction success between the two populations. In addition, sexes and reproductive stages were compared and a correlation between mRNA levels and gonadal area was investigated. The lists of differentially expressed genes revealed that sex explains most of the variance in gonadal gene expression. Additionally, genes like Foxl2, vitellogenin, condensing 2, mitotic apparatus protein p62, Cep57, sperm associated antigens 6, 16 and 17, motile sperm domain containing protein 2, sperm surface protein Sp17, sperm flagellar proteins 1 and 2 and dpy-30, were identified as being correlated with the gonad area and therefore supposedly with the number and/or the size of the gametes produced.

  14. From water to land: How an invasive clam may function as a resource pulse to terrestrial invertebrates.

    Science.gov (United States)

    Novais, Adriana; Souza, Allan T; Ilarri, Martina; Pascoal, Cláudia; Sousa, Ronaldo

    2015-12-15

    Resource pulses are episodes of low frequency, large magnitude and short duration that result in increased resource availability in space and time, with consequences for food web dynamics. Studies assessing the importance of resource pulses by invasive alien species in the interface between terrestrial and aquatic ecosystems are rare, especially those in the direction from water to land. This study assessed the importance of massive die-offs of the Asian clam Corbicula fluminea (Müller, 1774) as a resource pulse to the terrestrial invertebrate community after an extreme climatic event using a manipulative experiment. We used 5 levels of C. fluminea density (0, 100, 500, 1000 and 2000ind·m(-2)), with terrestrial invertebrates being censused 7, 30 and 90days after C. fluminea addition. We also assessed the possible effect of plots position, where plots that delimited the experiment were assigned as edge plots and the remaining as core plots. Clear differences were detected in abundance, biomass, richness and diversity of terrestrial invertebrates depending on the C. fluminea density, time and position. Interestingly, the highest abundance of adult Diptera was observed 7days after C. fluminea addition, whereas that of the other terrestrial invertebrates was on day 30, both with C. fluminea densities higher than 500ind·m(-2) located on the edge of the experimental design. This study highlights the importance of major resource pulses after massive die-offs of invasive bivalves, contributing with remarkable amounts of carrion for adjacent terrestrial systems. Part of this carrion can be consumed directly by a great number of invertebrate species while the remainder can enter the detrital food web. Given the high density and biomass attained by several invasive bivalves worldwide and the predicted increase in the number, intensity and magnitude of extreme climatic events, the ecological importance of this phenomenon should be further investigated. PMID:26327634

  15. In-situ observation of the effect of the precipitate/matrix interface on the evolution of dislocation structures in CLAM steel during irradiation

    International Nuclear Information System (INIS)

    Highlights: • Structure evolution of ion and electron irradiated CLAM steels was in-situ studied. • High-density fine MC precipitate may inhibit the fast growth of dislocation loops. • Interface of precipitate/matrix acts as a sink trapping radiation-induced defects. • The stability of precipitates under high-dose irradiation should be considered. - Abstract: The key factor that affects the irradiation resistance of a material is its structure such as grain size and precipitates. Two types of China Low Activation Martensitic (CLAM) steels with a different number density of MC phase were pre-ion implanted and subsequently irradiated by electrons using ultra-high voltage electron microscope (HVEM). The effect of MC phase on the growth behavior of dislocation loops and the stability of pre-existing precipitates were investigated in situ and this may give some hints on the way to increase the ability against irradiation damage. The results show that a high number density of the fine MC phase improves the strength of the material and also helps to inhibit the fast growth of dislocation loops. The interface between the precipitate and the matrix acts as an effective sink to trap radiation induced point defects, which can possibly result in an improvement of irradiation resistance to some extent. However, the coarsening of precipitates because of radiation enhanced diffusion is another issue that needs to be seriously considered when developing a nuclear material

  16. Seasonal variation of biochemical components in clam ( Saxidomus purpuratus Sowerby 1852) in relation to its reproductive cycle and the environmental condition of Sanggou Bay, China

    Science.gov (United States)

    Bi, Jinhong; Li, Qi; Zhang, Xinjun; Zhang, Zhixin; Tian, Jinling; Xu, Yushan; Liu, Wenguang

    2016-04-01

    Seasonal variation of biochemical components in clam ( Saxidomus purpuratus Sowerby 1852) was investigated from March 2012 to February 2013 in relation to environmental condition of Sanggou Bay and the reproductive cycle of clam. According to the histological analysis, the reproductive cycle of S. purpuratus includes two distinctive phases: a total spent and inactive stage from November to January, and a gametogenesis stage, including ripeness and spawning, during the rest of the year. Gametes were generated at a low temperature (2.1°C) in February. Spawning took place once a year from June to October. The massive spawning occurred in August when the highest water temperature and chlorophyll a level could be observed. The key biochemical components (glycogen, protein and lipid) in five tissues (gonad, foot, mantle, siphon and adductor muscle) were analyzed. The glycogen content was high before gametogenesis, and decreased significantly during the gonad development in the gonad, mantle and foot of both females and males, suggesting that glycogen was an important energy source for gonad development. The protein and lipid contents increased in the ovary during the gonad development, demonstrating that they are the major organic components of oocytes. The lipid and protein contents decreased in the testis, implying that they can provide energy and material for spermatogenesis. The results also showed that protein stored in the mantle and foot could support the reproduction after the glycogen was depleted.

  17. Effects of freshwater clam extract supplementation on time to exhaustion, muscle damage, pro/anti-inflammatory cytokines, and liver injury in rats after exhaustive exercise.

    Science.gov (United States)

    Huang, Kuo-Chin; Wu, Wen-Tien; Yang, Fwu-Lin; Chiu, Yi-Han; Peng, Tai-Chu; Hsu, Bang-Gee; Liao, Kuang-Wen; Lee, Ru-Ping

    2013-01-01

    The potent anti-inflammatory activities and tissue-protective effects of freshwater clams (Corbicula fluminea) have been well reported. The aim of this study was to determine the effects of freshwater clam extract (FCE) supplementation on time to exhaustion, muscle damage, pro- and anti-inflammatory cytokines, and liver injury in rats after exhaustive exercise. Thirty-two rats were divided into four groups: sedentary control (SC); SC group with FCE supplementation (SC+FCE); exhaustive exercise (E); and E group with FCE supplementation (E+FCE). The SC+FCE and E+FCE groups were treated with gavage administration of 20 mg/kg for seven consecutive days. Blood samples were collected for the evaluation of biochemical parameters. The cytokine levels of TNF-α and IL-10 were also examined. Twenty-four hours after exhaustive exercise, the rat livers were removed for H & E staining. The FCE supplementation could extend the time to exhaustion in exercised rats. The levels of CPK, LDH, AST, ALT, lactate, TNF-α and H & E stains of the liver injury were significantly decreased in the E+FCE group, but the blood glucose and IL-10 were significantly higher in comparison with the E group. This study suggests that FCE supplementation may improve endurance performance and reduce exercise-induced muscle damage, inflammatory stress and liver injury. PMID:23531600

  18. Effects of Freshwater Clam Extract Supplementation on Time to Exhaustion, Muscle Damage, Pro/Anti-Inflammatory Cytokines, and Liver Injury in Rats after Exhaustive Exercise

    Directory of Open Access Journals (Sweden)

    Kuang-Wen Liao

    2013-03-01

    Full Text Available The potent anti-inflammatory activities and tissue-protective effects of freshwater clams (Corbicula fluminea have been well reported. The aim of this study was to determine the effects of freshwater clam extract (FCE supplementation on time to exhaustion, muscle damage, pro- and anti-inflammatory cytokines, and liver injury in rats after exhaustive exercise. Thirty-two rats were divided into four groups: sedentary control (SC; SC group with FCE supplementation (SC+FCE; exhaustive exercise (E; and E group with FCE supplementation (E+FCE. The SC+FCE and E+FCE groups were treated with gavage administration of 20 mg/kg for seven consecutive days. Blood samples were collected for the evaluation of biochemical parameters. The cytokine levels of TNF-α and IL-10 were also examined. Twenty-four hours after exhaustive exercise, the rat livers were removed for H & E staining. The FCE supplementation could extend the time to exhaustion in exercised rats. The levels of CPK, LDH, AST, ALT, lactate, TNF-α and H & E stains of the liver injury were significantly decreased in the E+FCE group, but the blood glucose and IL-10 were significantly higher in comparison with the E group. This study suggests that FCE supplementation may improve endurance performance and reduce exercise-induced muscle damage, inflammatory stress and liver injury.

  19. High resolution oxygen isotope and grayscale records of a medieval fossil giant clam(Tridacna gigas) in the South China Sea:physiological and paleoclimatic implications

    Institute of Scientific and Technical Information of China (English)

    YAN Hong; WANG Yuhong; SUN Liguang

    2014-01-01

    Mollusks are well known for their detailed recording of paleoenvironmental and paleoclimatic changes in their carbonate shells. In this study, we constructed 18-year blue color intensity and oxygen isotope profiles of a14C dated (AD 990±40) fossil giant clam,Tridacna gigas, from Shidao Island, South China Sea. Theδ18O profile of theT. gigas specimen displayed regular annual cycles and was probably controlled by seasonal variations of the climatic parameters. The blue color intensity profile showed good agreement with theδ18O series, and both had 18 clear annual cycles in accordance with the 18 visually identified annual growth bands. The annual shell growth rate determined from the blue color intensity and oxygen isotope profiles indicated that the annual shell increment of theTridacna specimen was stable after the onset of sexual ma-turity. Spectral analysis of theδ18O and blue color intensity time series suggested that the El Niño-Southern Oscillation (ENSO) period observed in the instrumental temperature and precipitation records of the South China Sea during the past 50 years also existed in medieval times. Our results showed that fossil giant clams could provide a good archive of historical intra-seasonal to decadal climate variations.

  20. Mg-isotopic fractionation in the manila clam (Ruditapes philippinarum): New insights into Mg incorporation pathway and calcification process of bivalves

    Science.gov (United States)

    Planchon, Frédéric; Poulain, Céline; Langlet, Denis; Paulet, Yves-Marie; André, Luc

    2013-11-01

    We estimate the magnesium stable isotopic composition (δ26Mg) of the major compartments involved in the biomineralisation process of euryhaline bivalve, the manila clam Ruditapes philippinarum. Our aim is to identify the fractionation processes associated with Mg uptake and its cycling/transport in the bivalve organism, in order to better assess the controlling factors of the Mg isotopic records in bivalve shells. δ26Mg were determined in seawater, in hemolymph, extrapallial fluid (EPF), soft tissues and aragonitic shell of adult clams collected along the Auray River estuary (Gulf of Morbihan, France) at two sites showing contrasted salinity regimes. The large overall δ26Mg variations (4.16‰) demonstrate that significant mass-dependent Mg isotopic fractionations occur during Mg transfer from seawater to the aragonitic shell. Soft tissues span a range of fractionation factors relative to seawater (Δ26Mgsoft tissue-seawater) of 0.42 ± 0.12‰ to 0.76 ± 0.12‰, and show evidence for biological isotopic fractionation of Mg. Hemolymph and EPF are on average isotopically close to seawater (Δ26Mghemolymph-seawater = -0.20 ± 0.27‰; 2 sd; n = 5 and Δ26MgEPF-seawater = -0.23 ± 0.25‰; 2 sd; n = 5) indicating (1) a predominant seawater origin for Mg in the intercellular medium and (2) a relatively passive transfer route through the bivalve organism into the calcifying fluid. The lightest isotopic composition is found in shell, with δ26Mg ranging from -1.89 ± 0.07‰ to -4.22 ± 0.06‰. This range is the largest in the dataset and is proposed to result from a combination of abiotic and biologically-driven fractionation processes. Abiotic control includes fractionation during precipitation of aragonite and accounts for Δ26Mgaragonite-seawater ≈ 1000 ln αaragonite-seawater = -1.13 ± 0.28‰ at 20 °C based on literature data. Deviations from inorganic precipitate (expressed as Δ26MgPhysiol) appear particularly variable in the clam shell, ranging from 0

  1. A Comparative Study of Clam and Squid. Biting Flies of the Coastal Region. Diatoms: Nature's Aquatic Gems. Learning Experiences for Coastal and Oceanic Awareness Studies, Nos. 227, 231, 232. [Project COAST].

    Science.gov (United States)

    Delaware Univ., Newark. Coll. of Education.

    Included are three units related to coastal and oceanic awareness. The units are: (1) A Comparative Study of Clam and Squid; (2) Biting Flies of the Coastal Region; and (3) Diatoms: Nature's Aquatic Gems. All three units were designed for secondary school students. Each unit contains teacher background materials, student activity materials,…

  2. Long-term toxicity of hexabromocyclododecane (HBCDD) to the benthic clam Macoma balthica (L.) from the Baltic Sea

    Energy Technology Data Exchange (ETDEWEB)

    Smolarz, Katarzyna, E-mail: oceksm@univ.gda.pl [University of Gdansk, Institute of Oceanography, Laboratory of Ecosystem Functioning, al Pilsudskiego 46, 81-378 Gdynia (Poland); Soedertoern University College, School of Life Sciences, Alfred Nobels alle 7, 141 89 Huddinge (Sweden); Berger, Agata [University of Gdansk, Institute of Oceanography, Laboratory of Ecosystem Functioning, al Pilsudskiego 46, 81-378 Gdynia (Poland)

    2009-11-27

    The world's largest brackish water sea area, the Baltic Sea, is considered to be one of the most polluted seas of the world. Many new pollutants are constantly entering the environment, such as brominated flame-retardants (BFRs). BFRs represent a group of compounds that structurally resemble hydrophobic organic contaminants, but only scarce data about their toxicity to marine organism exist. Thus, the purpose of this study was to analyze long-term in vivo cytotoxicity and genotoxicity of hexabromocyclodododecane (HBCDD) to exposed marine invertebrates using a suite of cytogenetic biomarkers. This included a set of nuclear and nucleolar characteristics and the micronucleus test. The use of those parameters reflects different mechanisms of nuclear activity regulation in cells (as a parameter of cytotoxicity) and measures subcellular processes. The induction of nuclear abnormalities (like the formation of micronuclei) was also employed here as a parameter of genotoxicity. In order to reflect the proliferative and metabolic activity of the cells the number of argylophillic nucleolar organiser regions (NORs) in interphase cells was scored. Over a period of 50 days an in vivo exposure experiment with a clam Macoma balthica and different concentrations of HBCDD (nominal concentrations of 0, 100 and 250 {mu}g/l) with three replicates each was performed. Gill cells were used as 'sentinel systems' considering specificity in metabolism, repair mechanisms, adaptative response and cell proliferation. A significant increase in nuclear and nucleolar abnormalities and in the frequency of dead cells was observed during the duration of the experiment with the highest peak occurring 10 days after exposure for nuclear abnormalities and 20-30 days after exposure for malfunction of ribosomal genes (NORs) (GLM analyses and Spearman correlation, p < 0.05). Thus, the induction of micronuclei and other nuclear abnormalities reflected the toxic potential of HBCDD to marine

  3. Subcellular partitioning profiles and metallothionein levels in indigenous clams Moerella iridescens from a metal-impacted coastal bay.

    Science.gov (United States)

    Wang, Zaosheng; Feng, Chenglian; Ye, Chun; Wang, Youshao; Yan, Changzhou; Li, Rui; Yan, Yijun; Chi, Qiaoqiao

    2016-07-01

    In this study, the effect of environmental metal exposure on the accumulation and subcellular distribution of metals in the digestive gland of clams with special emphasis on metallothioneins (MTs) was investigated. Specimens of indigenous Moerella iridescens were collected from different natural habitats in Maluan Bay (China), characterized by varying levels of metal contamination. The digestive glands were excised, homogenized and six subcellular fractions were separated by differential centrifugation procedures and analyzed for their Cu, Zn, Cd and Pb contents. MTs were quantified independently by spectrophotometric measurements of thiols. Site-specific differences were observed in total metal concentrations in the tissues, correlating well with variable environmental metal concentrations and reflecting the gradient trends in metal contamination. Concentrations of the non-essential Cd and Pb were more responsive to environmental exposure gradients than were tissue concentrations of the essential metals, Cu and Zn. Subcellular partitioning profiles for Cu, Zn and Cd were relatively similar, with the heat-stable protein (HSP) fraction as the dominant metal-binding compartment, whereas for Pb this fraction was much less important. The variations in proportions and concentrations of metals in this fraction along with the metal bioaccumulation gradients suggested that the induced MTs play an important role in metal homeostasis and detoxification for M. iridescens in the metal-contaminated bay. Nevertheless, progressive accumulation of non-essential metals (Cd, and especially Pb) resulting from "spillover" was observed in putative metal- sensitive (e.g., mitochondria and heat-denaturable protein (HDP)) or lysosome/microsome fractions, demonstrating that metal detoxification was incomplete and increased the toxicological risk to M. iridescens inhabiting the metal-impacted environments. Through multiple stepwise regression analysis, the induction of MTs was statistically

  4. Some pharmacological properties of brain ganglioside

    Science.gov (United States)

    Bogoch, S.; Paasonen, M. K.; Trendelenburg, U.

    1962-01-01

    The effects of a preparation of purified brain ganglioside and of neuraminic acid have been studied on various pharmacological test preparations. In concentrations of 10 μg/ml. or more, ganglioside stimulates the isolated guinea-pig ileum; graded responses are usually obtained. Various substances, known to antagonize the actions of other stimulant substances, fail to affect the response to ganglioside. Ganglioside and neuraminic acid neither stimulate the superior cervical ganglion of the cat nor do they affect ganglionic transmission. Ganglioside and neuraminic acid did not change the response of the frog rectus abdominis muscle to acetylcholine, nor did they affect the blood pressure of the cat. Ganglioside (2 μg/ml. or more) stimulates the isolated heart of Venus mercenaria, but the response, which develops slowly, decreases with repeated administration of ganglioside. The response is not blocked by 2-bromo-lysergic acid diethylamide and there is no indication that it is due to the liberation of endogenous 5-hydroxytryptamine or related indole compounds. For both the heart of Venus mercenaria and guinea-pig ileum, the activity demonstrated by brain ganglioside is specifically a property of the whole molecule, since neither neuraminic acid itself nor a preparation of brain ganglioside from which only two-thirds of its neuraminic acid had been removed are active. PMID:13870595

  5. Response of detoxification gene mRNA expression and selection of molecular biomarkers in the clam Ruditapes philippinarum exposed to benzo[a]pyrene

    International Nuclear Information System (INIS)

    Benzo[a]pyrene (B[a]P) has a high carcinogenic potential. B[a]P concentrations and molecular biomarkers (mRNA expressions of Pgp, AhR, CYP4, CYP414A1, GST-pi, GST-S2, Cu/Zn-SOD and Mn-SOD) were assayed in gills and digestive glands of the clam Ruditapes philippinarum exposed to 0.03, 0.3 and 3 μg/L B[a]P for 21 days and then exposed to natural seawater for 15 days. Results showed that B[a]P was rapidly accumulated in and then eliminated from tissues of the clams. All gene mRNA expressions in the treated groups were induced significantly with the exception of CYP414A1 and Cu/Zn-SOD in the 0.03 μg/L B[a]P group. According to correlation analysis, mRNA expressions of AhR, GST-pi and Mn-SOD in gills and GST-pi in digestive glands had good correlations with B[a]P concentrations and could be used as molecular biomarkers of B[a]P exposure. This study investigated the molecular response of the genes mentioned above and selected useful molecular biomarkers for B[a]P pollution monitoring. - Highlights: • We measured B[a]P contents and mRNA expressions of eight different kinds of genes. • More B[a]P accumulated in digestive glands than in gills. • Most gene mRNA expressions in the treated groups were induced significantly. • AhR, GST-pi and Mn-SOD mRNA expressions in gills could be used as useful biomarkers. • GST-pi mRNA expression in digestive glands could be used as a useful biomarker. - mRNA expressions of AhR, GST-pi and Mn-SOD in gills and GST-pi in digestive glands of the clams are useful molecular biomarkers of B[a]P exposure

  6. A Study of the Soft Clam (Mya arenaria) Population on Some of the Mud Flats Within the Boundaries of the Parker River National Wildlife Refuge, Essex County, Massachusetts, with respect to the possible changes brought about by the influx of Black duck

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Several investigators working on the food habits of the black duck (Anas rubripes), have reported the presence of soft clams (Mya arenaria), in their stomachs and...

  7. Expression of genes involved in the uptake of inorganic carbon in the gill of a deep-sea vesicomyid clam harboring intracellular thioautotrophic bacteria.

    Science.gov (United States)

    Hongo, Yuki; Ikuta, Tetsuro; Takaki, Yoshihiro; Shimamura, Shigeru; Shigenobu, Shuji; Maruyama, Tadashi; Yoshida, Takao

    2016-07-10

    Deep-sea vesicomyid clams, including the genus Phreagena (formerly Calyptogena), harbor thioautotrophic bacterial symbionts in the host symbiosome, which consists of cytoplasmic vacuoles in gill epithelial cells called bacteriocytes. The symbiont requires inorganic carbon (Ci), such as CO2, HCO3(-), and CO3(2-), to synthesize organic compounds, which are utilized by the host clam. The dominant Ci in seawater is HCO3(-), which is impermeable to cell membranes. Within the bacteriocyte, cytoplasmic carbonic anhydrase (CA) from the host, which catalyzes the inter-conversion between CO2 and HCO3(-), has been shown to be abundant and is thought to supply intracellular CO2 to symbionts in the symbiosome. However, the mechanism of Ci uptake by the host gill from seawater is poorly understood. To elucidate the influx pathway of Ci into the bacteriocyte, we isolated the genes related to Ci uptake via the pyrosequencing of cDNA from the gill of Phreagena okutanii, and investigated their expression patterns. Using phylogenetic and amino acid sequence analyses, three solute carrier family 4 (SLC4) bicarbonate transporters (slc4co1, slc4co2, and slc4co4) and two membrane-associated CAs (mcaco1 and mcaco2) were identified as candidate genes for Ci uptake. In an in situ hybridization analysis of gill sections, the expression of mcaco1 and mcaco2 was detected in the bacteriocytes and asymbiotic non-ciliated cells, respectively, and the expression of slc4co1 and slc4co2 was detected in the asymbiotic cells, including the intermediate cells of the inner area and the non-ciliated cells of the external area. Although subcellular localizations of the products of these genes have not been fully elucidated, they may play an important role in the uptake of Ci into the bacteriocytes. These findings will improve our understanding of the Ci transport system in the symbiotic relationships of chemosynthetic bivalves. PMID:27016297

  8. First genotoxicity study of Paraná river water from Argentina using cells from the clam Corbicula fluminea (Veneroida Corbiculidae) and Chinese hamster (Cricetulus griseus Rodentia, Cricetidae) K1 cells in the comet assay

    OpenAIRE

    Jacqueline D. Caffetti; Mário S. Mantovani; María C. Pastori; Alberto S. Fenocchio

    2008-01-01

    High concentrations of xenobiotics from urban and industrial wastes have contributed to the contamination of many aquatic environments. We used the comet assay to evaluate the genotoxic potential of water collected from the River Paraná, which receives a great deal of waste, at three points (Puerto Piray, Eldorado and Montecarlo) in the Misiones Province of Argentina. The in vivo comet assay used 40 freshwater clams (Corbicula fluminea) while the in vitro comet assay used Chinese hamster (Cri...

  9. Residues in fish, wildlife, and estuaries. Indicator species near top of food chain chosen for assessment of pesticide base levels in fish and wildlife--clams, oysters, and sediment in estuarine environment

    Science.gov (United States)

    Johnson, R.E.; Carver, T.C.; Dustman, E.H.

    1967-01-01

    Federal efforts to determine pesticide levels in fish and wildlife are being carried out by the Bureau of Sport Fisheries and Wildlife, U. S. Department of the Interior. Monitoring estuarine pesticide levels in clams, oysters, and sediments is a joint endeavor of the Bureau of Commercial Fisheries, U. S. Department of the Interior, and the Water Supply and Sea Resources Program of the National Center for Urban and Industrial Health, Public Health Service, U. S. Department of Health, Education, and Welfare.

  10. South West Pacific climate at c. 6600-6000 BP inferred from giant clam Tridacna maxima and massive coral Porites sp. records

    Science.gov (United States)

    Duprey, N.; Pujol, N.; Lazareth, C. E.; Cabioch, G.; Correge, T.; Le Cornec, F.; Maes, C.; Galipaud, J.; Caquineau, S.; Madeng-Yogo, M.

    2011-12-01

    In the last three decades, the El Niño Southern Oscillation (ENSO) has been characterized by more frequent and stronger El Niño events. Recent paleo-climate studies demonstrated that ENSO periodicity was lower during the Mid-Holocene and that it increased towards present-day. While a better knowledge on such past changes is necessary to reliably predict future climate, the origin of the Mid-Holocene ENSO regime shift remains controversial. The present study is focused on the climate in the Southwest Pacific c. 6 600-6 000 BP. This period precedes the Mid-Holocene ENSO-shift, and is essential to understand the ENSO evolution. The Vanuatu archipelago (South West Pacific; 15° 40'S; 167°00' E) is characteristic of an open ocean context and climatic conditions are strongly linked to the ENSO variability in relation with the position of the South Pacific Convergence Zone (SPCZ). The Sea Surface Salinity (SSS) and Sea Surface Temperature (SST) are highly correlated to the Southern Oscillation Index (SOI) and the Niño 3.4 index. Consequently, high-resolution SSS and SST records from massive corals and giant clams provide reliable tools to track ENSO variability back in time in this region. Two massive Porites sp. coral colonies, dated at 6758 - 6544 14C cal. BP, and one giant Tridacna maxima clam dated at 6257-6056 14C cal. BP, were collected on Espiritu Santo Island. These archives were sampled at monthly resolution and analyzed for Sr/Ca ratio and δ18O. SST was reconstructed from corals Sr/Ca and the giant clam δ18O. The δ18O composition of seawater (δw), calculated from the coral δ18O record, was used as a proxy for evaporation/precipitation (E/P) budget. Compared to present-day conditions, reconstructed SST are 2.5°C lower at ~6600 BP and 1°C lower at ~6100 BP, and both archives present a slightly higher (+0.5°C) seasonal amplitude. Fossil Porites sp. from Vanuatu showed that the E/P budget was positively correlated to the SST c. 6600BP whereas the inverse

  11. Tropical troposphere to stratosphere transport of carbon monoxide and long-lived trace species in the Chemical Lagrangian Model of the Stratosphere (CLaMS

    Directory of Open Access Journals (Sweden)

    R. Pommrich

    2014-08-01

    Full Text Available Variations in the mixing ratio of trace gases of tropospheric origin entering the stratosphere in the tropics are of interest for assessing both troposphere to stratosphere transport fluxes in the tropics and the impact of these transport fluxes on the composition of the tropical lower stratosphere. Anomaly patterns of carbon monoxide (CO and long-lived tracers in the lower tropical stratosphere allow conclusions about the rate and the variability of tropical upwelling to be drawn. Here, we present a simplified chemistry scheme for the Chemical Lagrangian Model of the Stratosphere (CLaMS for the simulation, at comparatively low numerical cost, of CO, ozone, and long-lived trace substances (CH4, N2O, CCl3F (CFC-11, CCl2F2 (CFC-12, and CO2 in the lower tropical stratosphere. For the long-lived trace substances, the boundary conditions at the surface are prescribed based on ground-based measurements in the lowest model level. The boundary condition for CO in the free troposphere is deduced from MOPITT measurements (at ≈ 700–200 hPa. Due to the lack of a specific representation of mixing and convective uplift in the troposphere in this model version, enhanced CO values, in particular those resulting from convective outflow are underestimated. However, in the tropical tropopause layer and the lower tropical stratosphere, there is relatively good agreement of simulated CO with in-situ measurements (with the exception of the TROCCINOX campaign, where CO in the simulation is biased low ≈ 10–20 ppbv. Further, the model results are of sufficient quality to describe large scale anomaly patterns of CO in the lower stratosphere. In particular, the zonally averaged tropical CO anomaly patterns (the so called "tape recorder" patterns simulated by this model version of CLaMS are in good agreement with observations. The simulations show a too rapid upwelling compared to observations as a consequence of the overestimated vertical velocities in

  12. Dynamics and chemistry of vortex remnants in late Arctic spring 1997 and 2000: Simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS

    Directory of Open Access Journals (Sweden)

    P. Konopka

    2003-01-01

    Full Text Available High-resolution simulations of the chemical composition of the Arctic stratosphere during late spring 1997 and 2000 were performed with the Chemical Lagrangian Model of the Stratosphere (CLaMS. The simulations were performed for the entire northern hemisphere on two isentropic levels 450 K (~18 km and 585 K (~24 km. The spatial distribution and the lifetime of the vortex remnants formed after the vortex breakup in May 1997 display different behavior above and below 20 km. Above 20 km, vortex remnants propagate southward (up to 40°N and are "frozen in'' in the summer circulation without significant mixing. Below 20 km the southward propagation of the remnants is bounded by the subtropical jet. Their lifetime is shorter by a factor of 2 than that above 20 km, owing to significant stirring below this altitude. The behavior of vortex remnants formed in March 2000 is similar but, due to an earlier vortex breakup, dominated during the first 6 weeks after the vortex breakup by westerly winds, even above 20 km. Vortex remnants formed in May 1997 are characterized by large mixing ratios of HCl indicating negligible, halogen-induced ozone loss. In contrast, mid-latitude ozone loss in late boreal spring 2000 is dominated, until mid-April, by halogen-induced ozone destruction within the vortex remnants, and subsequent transport of the ozone-depleted polar air masses (dilution into the mid-latitudes. By varying the intensity of mixing in CLaMS, the impact of mixing on the formation of ClONO2 and ozone depletion is investigated. We find that the photochemical decomposition of HNO3 and not mixing with NOx-rich mid-latitude air is the main source of NOx within the vortex remnants in March and April 2000. Ozone depletion in the remnants is driven by ClOx photolytically formed from ClONO2. At the end of May 1997, the halogen-induced ozone deficit at 450 K poleward of 30°N amounts to ~12% with ~10% in the polar vortex and ~2% in well-isolated vortex remnants

  13. Fate of isotopically labeled zinc oxide nanoparticles in sediment and effects on two endobenthic species, the clam Scrobicularia plana and the ragworm Hediste diversicolor.

    Science.gov (United States)

    Buffet, Pierre-Emmanuel; Amiard-Triquet, Claude; Dybowska, Agnieszka; Risso-de Faverney, Christine; Guibbolini, Marielle; Valsami-Jones, Eugénia; Mouneyrac, Catherine

    2012-10-01

    Although it is reported that metal and metal oxide nanoparticles, which are among the most rapidly commercialized materials, can cause toxicity to organisms, their fate in the environment and toxicity to marine organisms are not well understood. In this study, we used a stable isotope labelling approach to trace the fate of nanoparticles (NPs) in sediments and also investigated bio-uptake in two estuarine intra-sedimentary invertebrates Scrobicularia plana and Nereis diversicolor. We selected exposure to 3 mg kg(-1) sediment ZnO NPs since this level is a realistic prediction of the environmental concentration in sediments. 67ZnO NPs (DLS: 21-34 nm, positively charged: 31.3 mV) suspensions were synthesised in diethylene glycol (DEG). We explored the fate of 67ZnO NPs in sediment, 67Zn bioaccumulation and the biochemical (biomarkers of defence and damage) and behavioural (burrowing kinetics and feeding rates) biomarkers in both species to 67ZnO NPs and DEG on its own during a 16 d laboratory exposure. After exposure, 67Zn concentrations in sediment showed higher levels in the upper section (1cm: 2.59 mg kg(-1)) decreasing progressively (2 cm: 1.63 mg kg(-1), 3 cm: 0.90 mg kg(-1), 4 cm: 0.67 mg kg(-1)) to a minimum value at the bottom (5 cm: 0.31 mg kg(-1)). 67Zn bioaccumulation was observed in both organisms exposed to 67ZnO NPs in DEG but no major inter-species differences were found. At the biochemical level, 67ZnO NPs exposure significantly induced increased glutathione-S-transferase activity in worms and catalase activity in clams whereas superoxide dismutase activity and thiobarbituric acid reactive substance levels were not affected in any species. Exposure to DEG on its own leads to a significant increase of metallothionein-like protein levels in clams compared with those exposed to 67ZnO NPs or controls. Burrowing behaviour as well as feeding rate were significantly impaired in both species exposed to 67ZnO NPs. Concerning exposure to DEG on its own

  14. Gene cloning and catalytic characterization of cold-adapted lipase of Photobacterium sp. MA1-3 isolated from blood clam.

    Science.gov (United States)

    Kim, Young Ok; Khosasih, Vivia; Nam, Bo-Hye; Lee, Sang-Jun; Suwanto, Antonius; Kim, Hyung Kwoun

    2012-12-01

    A lipase-producing Photobacterium strain (MA1-3) was isolated from the intestine of a blood clam caught at Namhae, Korea. The lipase gene was cloned by shotgun cloning and encoded 340 amino acids with a molecular mass of 38,015 Da. It had a very low sequence identity with other bacterial lipases, with the exception of that of Photobacterium lipolyticum M37 (83.2%). The MA1-3 lipase was produced in soluble form when Escherichia coli cells harboring the gene were cultured at 18°C. Its optimum temperature and pH were 45°C and pH 8.5, respectively. Its activation energy was calculated to be 2.69 kcal/mol, suggesting it to be a cold-adapted lipase. Its optimum temperature, temperature stability, and substrate specificity were quite different from those of M37 lipase, despite the considerable sequence similarities. Meanwhile, MA1-3 lipase performed a transesterification reaction using olive oil and various alcohols including methanol, ethanol, 1-propanol, and 1-butanol. In the presence of t-butanol as a co-solvent, this lipase produced biodiesel using methanol and plant or waste oils. The highest biodiesel conversion yield (73%) was achieved using waste soybean oil and methanol at a molar ratio of 1:5 after 12 h using 5 units of lipase. PMID:22841866

  15. Application of electron-beam irradiation on the production of salted and seasoned short-necked clam, Tapes Pilippinarum, for safe distribution

    Energy Technology Data Exchange (ETDEWEB)

    Kim, B.; Song, H.P.; Choe, J.H.; Jung, S. [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Jang, A. [Quality Control and Utilization of Animal Products, National Institute of Animal Science, Suwon 441-706 (Korea, Republic of); Kim, Y.J. [Food Safety Research Division, Korea Food Research Institute, Seongnam 463-746 (Korea, Republic of); Jo, C. [Department of Animal Science and Biotechnology, Chungnam National University, Daejeon 305-764 (Korea, Republic of)], E-mail: cheorun@cnu.ac.kr

    2009-07-15

    Salted and seasoned short-necked clam (Tapes Philippinarum; SNC) and its major ingredients, red hot pepper powder, ginger, garlic and onion were irradiated at 0.5, 1, 2 and 5 kGy, respectively, and the microbiological and sensory quality were evaluated. The water activities of SNC and red pepper powder were 0.91 and 0.56, respectively, and others were higher than 0.97. The initial microbial populations of SNC were approximately 3.99, 4.38 and 2.22 log CFU/g for total aerobic bacteria, yeast and mold, and coliform bacteria. The highest contamination of total aerobic bacteria was detected from ground ginger among ingredients at 5.51 log CFU/g. Electron-beam irradiation (0, 0.5, 1, 2 and 5 kGy) significantly reduced the initial microbial level of SNC and its ingredients not only immediately after irradiation, but also during storage at 10 {sup o}C for 4 weeks (p<0.05). There was no adverse change of sensory score except for the color of onion irradiated at 5 kGy, which results in a lower score than control. From the results electron-beam irradiation is a useful tool to enhance the storage stability and safe distribution of SNC.

  16. Modelling 2,4-dichlorophenol bioavailability and bioaccumulation by the freshwater fingernail clam Sphaerium corneum using artificial particles and humic acids

    International Nuclear Information System (INIS)

    The complex and variable composition of natural sediments makes it very difficult to predict the bioavailability and bioaccumulation of sediment-bound contaminants. Several approaches have been proposed to overcome this problem, including an experimental model using artificial particles with or without humic acids as a source of organic matter. For this work, we have applied this experimental model, and also a sample of a natural sediment, to investigate the uptake and bioaccumulation of 2,4-dichlorophenol (2,4-DCP) by Sphaerium corneum. Additionally, the particle-water partition coefficients (K d) were calculated. The results showed that the bioaccumulation of 2,4-DCP by clams did not depend solely on the levels of chemical dissolved, but also on the amount sorbed onto the particles and the characteristics and the strength of that binding. This study confirms the value of using artificial particles as a suitable experimental model for assessing the fate of sediment-bound contaminants. - An experimental model is proposed to better understand the bioavailability and bioaccumulation of sediment-bound 2,4-dichlorophenol

  17. Population subdivision of the surf clam Mactra chinensis in the East China Sea: Changjiang River outflow is not the sole driver

    Science.gov (United States)

    Ni, Gang; Ni, Lehai; Kong, Lingfeng; Yu, Hong

    2015-01-01

    The northwestern Pacific, characterized by unique tectonic and hydrological settings, has greatly intrigued marine phylogeographers. However, current studies mostly focus on the influence of Pleistocene isolation of sea basins in population structure of species in the region, leaving the contribution of other factors (such as freshwater outflow and environmental gradients) largely unexploited. Here we shed light on the question by investigating phylogeography of the surf clam Mactra chinensis in the East China Sea (ECS). Genetic information was acquired from 501 specimens collected from its main distribution in the region, represented by mitochondrial cytochrome oxidase I (COI) and nine polymorphic microsatellite loci. A shallow and star-like phylogeny was revealed for all COI haplotypes, indicating the origin of populations from a single refugium. Although no divergent lineages existed, population subdivision was detected in both data sets. The most striking pattern was the significant differentiation between populations north and south of a biogeographic boundary—the Changjiang Estuary, suggesting a barrier effect of the freshwater outflow to gene flow. For the northern group, substructure was revealed by COI result as one southernmost population was significant different from other ones. Clear latitude gradations in allele frequencies were revealed by microsatellite analyses, likely influenced by environmental gradient factors such as temperature. Our results demonstrate that genetic subdivision can arise for populations within the ECS despite they have a single origin, and multiple mechanisms including Changjiang River outflow, environmental gradient factors and life-history traits may act in combination in the process. PMID:26468432

  18. Does the antibiotic amoxicillin affect haemocyte parameters in non-target aquatic invertebrates? The clam Ruditapes philippinarum and the mussel Mytilus galloprovincialis as model organisms.

    Science.gov (United States)

    Matozzo, Valerio; Bertin, Valeria; Battistara, Margherita; Guidolin, Angelica; Masiero, Luciano; Marisa, Ilaria; Orsetti, Alessandro

    2016-08-01

    Amoxicillin (AMX) is one of the most widely used antibiotics worldwide, and its levels in aquatic ecosystems are expected to be detectable. At present, information concerning the toxic effects of AMX on non-target aquatic organisms, such as bivalves, is scarce. Consequently, in this study, we investigated for the first time the effects of AMX on the haemocyte parameters of two bivalve species, the clam Ruditapes philippinarum and the mussel Mytilus galloprovincialis, which share the same habitat in the Lagoon of Venice, in order to compare the relative sensitivity of the two species. The bivalves were exposed to 100, 200 and 400 μg AMX/L for 1, 3 and 7 days, and the effects on the total haemocyte count (THC), the diameter and volume of the haemocytes, haemocyte proliferation, lactate dehydrogenase (LDH) activity in cell-free haemolymph, the haemolymph pH, and the formation of micronuclei were evaluated. The actual concentrations of AMX in the seawater samples from the experimental tanks were also measured. Overall, the obtained results demonstrated that AMX affected slightly the haemocyte parameters of bivalves. In addition, no clear differences in terms of sensitivity to AMX exposure were recorded between the two bivalve species. PMID:27219711

  19. Ocean acidification weakens the immune response of blood clam through hampering the NF-kappa β and toll-like receptor pathways.

    Science.gov (United States)

    Liu, Saixi; Shi, Wei; Guo, Cheng; Zhao, Xinguo; Han, Yu; Peng, Chao; Chai, Xueliang; Liu, Guangxu

    2016-07-01

    The impact of pCO2 driven ocean acidification on marine bivalve immunity remains poorly understood. To date, this impact has only been investigated in a few bivalve species and the underlying molecular mechanism remains unknown. In the present study, the effects of the realistic future ocean pCO2 levels (pH at 8.1, 7.8, and 7.4) on the total number of haemocyte cells (THC), phagocytosis status, blood cell types composition, and expression levels of twelve genes from the NF-kappa β signaling and toll-like receptor pathways of a typical bottom burrowing bivalve, blood clam (Tegillarca granosa), were investigated. The results obtained showed that while both THC number and phagocytosis frequency were significantly reduced, the percentage of red and basophil granulocytes were significantly decreased and increased, respectively, upon exposure to elevated pCO2. In addition, exposure to pCO2 acidified seawater generally led to a significant down-regulation in the inducer and key response genes of NF-kappa β signaling and toll-like receptor pathways. The results of the present study revealed that ocean acidification may hamper immune responses of the bivalve T. granosa which subsequently render individuals more susceptible to pathogens attacks such as those from virus and bacteria. PMID:27109580

  20. A novel widespread cryptic species and phylogeographic patterns within several giant clam species (Cardiidae: Tridacna from the Indo-Pacific Ocean.

    Directory of Open Access Journals (Sweden)

    Thomas Huelsken

    Full Text Available Giant clams (genus Tridacna are iconic coral reef animals of the Indian and Pacific Oceans, easily recognizable by their massive shells and vibrantly colored mantle tissue. Most Tridacna species are listed by CITES and the IUCN Redlist, as their populations have been extensively harvested and depleted in many regions. Here, we survey Tridacna crocea and Tridacna maxima from the eastern Indian and western Pacific Oceans for mitochondrial (COI and 16S and nuclear (ITS sequence variation and consolidate these data with previous published results using phylogenetic analyses. We find deep intraspecific differentiation within both T. crocea and T. maxima. In T. crocea we describe a previously undocumented phylogeographic division to the east of Cenderawasih Bay (northwest New Guinea, whereas for T. maxima the previously described, distinctive lineage of Cenderawasih Bay can be seen to also typify western Pacific populations. Furthermore, we find an undescribed, monophyletic group that is evolutionarily distinct from named Tridacna species at both mitochondrial and nuclear loci. This cryptic taxon is geographically widespread with a range extent that minimally includes much of the central Indo-Pacific region. Our results reinforce the emerging paradigm that cryptic species are common among marine invertebrates, even for conspicuous and culturally significant taxa. Additionally, our results add to identified locations of genetic differentiation across the central Indo-Pacific and highlight how phylogeographic patterns may differ even between closely related and co-distributed species.

  1. RISK CHARACTERIZATION OF A COASTAL ENVIRONMENT FACING A MINING AND INDUSTRIAL AREA IN SARDINIA (SULCIS-IGLESIENTE BY MEANS OF CLUSTER SAMPLING AND CONTAMINANTS RESEARCH ON EDIBLE FISH AND CLAMS

    Directory of Open Access Journals (Sweden)

    P.L. Piras

    2011-01-01

    Full Text Available On the basis of the results obtained from the analysis carried out on various environmental substrates (sediments, sea water and bio-indicators, it can be assumed that there has been a transfer of contaminants from sediments to edible “biota” in the Boi Cerbus lagoon (Sulcis-Iglesiente. It has also been verified that the benthic clams, in particular the Cerastoderma glaucum, is the species mainly affected by heavy metals contamination, in particular Lead, even if the role of Cadmium in the lagoon would need further investigation.

  2. Light induces changes in activities of Na+/K+-ATPase, H+/K+-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam, Tridacna squamosa

    OpenAIRE

    Ip, Yuen K.; Ching, Biyun; Kum C Hiong; Choo, Celine Y. L.; Boo, Mel V.; Wong, Wai P.; Chew, Shit F.

    2015-01-01

    The objective of this study was to determine the effects of 12 h of exposure to light, as compared with 12 h of exposure to darkness (control), on enzymatic activities of transporters involved in the transport of NH+ 4 or H+, and activities of enzymes involved in converting NH+ 4 to glutamate/glutamine in inner mantle, outer mantle, and ctenidia of the giant clam, Tridacna squamosa. Exposure to light resulted in a significant increase in the effectiveness of NH+ 4 in substitution for K+ to ac...

  3. Light induces changes in activities of Na+/K+(NH4+)-ATPase, H+/K+(NH4+)-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam Tridacna squamosa

    OpenAIRE

    Alex Y K Ip; Biyun eChing; Kum C Hiong; Yen Ling eChoo; Mel Veen Boo; WaiP eWong; S F Chew

    2015-01-01

    The objective of this study was to determine the effects of 12 h of exposure to light, as compared with 12 h of exposure to darkness (control), on enzymatic activities of transporters involved in the transport of NH4+ or H+, and activities of enzymes involved in converting NH4+ to glutamate/glutamine in inner mantle, outer mantle and ctenidia of the giant clam, Tridacna squamosa. Exposure to light resulted in a significant increase in the effectiveness of NH4+ in substitution for K+ to activa...

  4. Molecular characterization of two kazal-type serine proteinase inhibitor genes in the surf clam Mesodesma donacium exposed to Vibrio anguillarum.

    Science.gov (United States)

    Maldonado-Aguayo, Waleska; Núñez-Acuña, Gustavo; Valenzuela-Muñoz, Valentina; Chávez-Mardones, Jacqueline; Gallardo-Escárate, Cristian

    2013-06-01

    This study reports two kazal-type serine protease inhibitors (KPI) identified in a cDNA library from the surf clam Mesodesma donacium, and characterized through Rapid Amplification of cDNA Ends (RACE). The KPIs, denoted as MdSPI-1 and MdSPI-2, presented full sequences of 1139 bp and 781 bp respectively. MdSPI-1 had a 5'untranslated region (UTR) of 175 bp, a 3'UTR of 283 bp and an open reading frame (ORF) of 681 pb that encodes for 227 amino acids. MdSPI-2 showed a 5'UTR of 70 bp, a 3'UTR of 279 bp and an ORF of 432 bp that encodes for 144 amino acids. Both sequences presented two kazal-type tandem domains. Phylogenetic analysis of MdSPI-1 and MdSPI-2 shows a main clade composed by other bivalve species and closely related crustaceans. Real time PCR analysis showed that MdSPI-1 is mainly up-regulated in mantle, foot, gills and muscle tissues, while MdSPI-2 is expressed principally in foot tissue. Moreover, to evaluate the immune response of MdSPI-1 and MdSPI-2, infections with Vibrio anguillarum were performed. Herein, MdSPI-1 and MdSPI-2 transcription expression were significantly up-regulated at 2 and 8 h post-challenge. Our results suggest that MdSPI-1 and MdSPI-2 are important humoral factors of innate immunity in M. donacium. PMID:23528874

  5. Effect of permethrin, anthracene and mixture exposure on shell components, enzymatic activities and proteins status in the Mediterranean clam Venerupis decussata

    International Nuclear Information System (INIS)

    Highlights: • We assessed toxicity of anthracene, permethrin and their mixture on clams. • Tissue and stressor-dependent changes were observed in biochemical responses. • Permethrin induces phase transition from aragonite to calcite in shell structure. • Interactive effects were observed on digestive gland and gill biomarkers. • Both approaches give new vision to risk assessment of organic pollution. - Abstract: Anthracene (ANT) and permethrin (PER) are two of the more toxic compounds reaching the marine environment. This study aimed to determine the impact of these molecules on Venerupis decussata, an economically important species cultured on the Tunisian coast. Shell structure and its possible transformation upon exposure to the two contaminants were studied by X-ray diffraction and gravimetric analyses. Results revealed a phase transition in shell composition from aragonite to calcite after PER exposure, to a mixture of PER and ANT (Mix) but not for ANT alone. Catalase (CAT), superoxide dismutase (SOD) and glutathione transferase (GST) activities were determined in digestive gland and gills after exposure to ANT, PER and Mix to assess the impact of the contamination on the oxidative status of V. decussata. Enzyme activities increased in the digestive gland after PER treatment and in the gills after ANT treatment. PER exposure significantly reduced the levels of free thiols and increased levels of carbonylated proteins in the digestive gland, as compared to controls. In contrast, ANT exposure significantly reduced free thiols and increased the number of carbonylated proteins in the gills. Mix induced additive effects as measured by both enzymatic and proteomic approaches. The present study suggests that PER has a strong effect on shell structure; that PER and ANT exposure generate compound-dependent oxidative stress in the tissues of V. decussata and that a mixture of the two compounds has synergistic effects on biochemical response

  6. Biodynamic modelling of the bioaccumulation of trace metals (Ag, As and Zn) by an infaunal estuarine invertebrate, the clam Scrobicularia plana

    International Nuclear Information System (INIS)

    Highlights: • Biodynamic modelling is used to predict accumulation of Ag, As and Zn in S. plana. • Dissolved and sediment-associated metals contribute to total metal bioaccumulation. • Relative importance varies with water and sediment concentrations and geochemistries. - Abstract: Biodynamic modelling was used to investigate the uptake and accumulation of three trace metals (Ag, As, Zn) by the deposit feeding estuarine bivalve mollusc Scrobicularia plana. Radioactive labelling techniques were used to quantify the rates of trace metal uptake (and subsequent elimination) from water and sediment diet. The uptake rate constant from solution (±SE) was greatest for Ag (3.954 ± 0.375 l g−1 d−1) followed by As (0.807 ± 0.129 l g−1 d−1) and Zn (0.103 ± 0.016 l g−1 d−1). Assimilation efficiencies from ingested sediment were 40.2 ± 1.3% (Ag), 31.7 ± 1.0% (Zn) and 25.3 ± 0.9% (As). Efflux rate constants after exposure to metals in the solution or sediment fell in the range of 0.014–0.060 d−1. By incorporating these physiological parameters into biodynamic models, our results showed that dissolved metal is the predominant source of accumulated Ag, As and Zn in S. plana, accounting for 66–99%, 50–97% and 52–98% of total accumulation of Ag, As and Zn, respectively, under different field exposure conditions. In general, model-predicted steady state concentrations of Ag, As and Zn matched well with those observed in clams collected in SW England estuaries. Our findings highlight the potential of biodynamic modelling to predict Ag, As and Zn accumulation in S. plana, taking into account specific dissolved and sediment concentrations of the metals at a particular field site, together with local water and sediment geochemistries

  7. Effect of permethrin, anthracene and mixture exposure on shell components, enzymatic activities and proteins status in the Mediterranean clam Venerupis decussata

    Energy Technology Data Exchange (ETDEWEB)

    Sellami, Badreddine, E-mail: sellamibadreddine@gmail.com [Laboratory of Environment Biomonitoring, Coastal Ecology Unit, Faculty of Sciences of Bizerta, University of Carthage, 7021 Zarzouna (Tunisia); Khazri, Abdelhafidh [Laboratory of Environment Biomonitoring, Coastal Ecology Unit, Faculty of Sciences of Bizerta, University of Carthage, 7021 Zarzouna (Tunisia); Mezni, Amine [Unit of Research 99/UR12-30, Department of Chemistry, Faculty of Sciences of Bizerte, 7021 Jarzouna (Tunisia); Louati, Héla; Dellali, Mohamed; Aissa, Patricia; Mahmoudi, Ezzeddine; Beyrem, Hamouda [Laboratory of Environment Biomonitoring, Coastal Ecology Unit, Faculty of Sciences of Bizerta, University of Carthage, 7021 Zarzouna (Tunisia); Sheehan, David, E-mail: d.sheehan@ucc.ie [Environmental Research Institute and Department of Biochemistry, University College Cork, Western Gateway Building, Western Road, Cork (Ireland)

    2015-01-15

    Highlights: • We assessed toxicity of anthracene, permethrin and their mixture on clams. • Tissue and stressor-dependent changes were observed in biochemical responses. • Permethrin induces phase transition from aragonite to calcite in shell structure. • Interactive effects were observed on digestive gland and gill biomarkers. • Both approaches give new vision to risk assessment of organic pollution. - Abstract: Anthracene (ANT) and permethrin (PER) are two of the more toxic compounds reaching the marine environment. This study aimed to determine the impact of these molecules on Venerupis decussata, an economically important species cultured on the Tunisian coast. Shell structure and its possible transformation upon exposure to the two contaminants were studied by X-ray diffraction and gravimetric analyses. Results revealed a phase transition in shell composition from aragonite to calcite after PER exposure, to a mixture of PER and ANT (Mix) but not for ANT alone. Catalase (CAT), superoxide dismutase (SOD) and glutathione transferase (GST) activities were determined in digestive gland and gills after exposure to ANT, PER and Mix to assess the impact of the contamination on the oxidative status of V. decussata. Enzyme activities increased in the digestive gland after PER treatment and in the gills after ANT treatment. PER exposure significantly reduced the levels of free thiols and increased levels of carbonylated proteins in the digestive gland, as compared to controls. In contrast, ANT exposure significantly reduced free thiols and increased the number of carbonylated proteins in the gills. Mix induced additive effects as measured by both enzymatic and proteomic approaches. The present study suggests that PER has a strong effect on shell structure; that PER and ANT exposure generate compound-dependent oxidative stress in the tissues of V. decussata and that a mixture of the two compounds has synergistic effects on biochemical response.

  8. An assessment on the influence of salinity in the growth of black clam (Villorita cyprinoides in cage in Cochin Estuary with a special emphasis on the impact of Thanneermukkom salinity barrier

    Directory of Open Access Journals (Sweden)

    Aloorkalarickal U. Arun

    2009-06-01

    Full Text Available Regular tidal flow, estuarine circulation and other allied hydrographical parameters in the Cochin Estuary has changed due to regular closure and opening of Thanneermukkom bund and entry of saline water in to the estuary. Temperature, salinity and bottom sediment texture are found to be the important factors significant for the growth and survival of bivalves. The environmental condition on different parts of the estuary especially at station II (south of bund, station IV (north of bund and station V (near to bar mouth showed a clear and distinct variation in all the hydrographical parameters due to the existence of Thanneermukkom bund and bar mouth. At stations II the frequency of temperature fluctuation was high and the dominant environment was freshwater when compared with station IV. Sediment texture at station II was sandy silt and at station IV was silty sand. At station V the dominant condition was saline and sediment texture was clayey in nature. A higher salinity was noted throughout the study period at station V. At station II the annual average growth was 8.48 mm; at station IV it was 15.15 mm and at station V it was 9.64 mm. Moderate level of salinity is found to be a favourable factor for the growth of Villorita cyprinoides. Growth rates of smaller clams were found to be higher than larger clams.

  9. Biodynamic modelling of the bioaccumulation of trace metals (Ag, As and Zn) by an infaunal estuarine invertebrate, the clam Scrobicularia plana

    Energy Technology Data Exchange (ETDEWEB)

    Kalman, J., E-mail: judit.kalman@uca.es [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom); Smith, B.D. [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom); Bury, N.R. [Division of Diabetes and Nutritional Science, King' s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH (United Kingdom); Rainbow, P.S. [Department of Life Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD (United Kingdom)

    2014-09-15

    Highlights: • Biodynamic modelling is used to predict accumulation of Ag, As and Zn in S. plana. • Dissolved and sediment-associated metals contribute to total metal bioaccumulation. • Relative importance varies with water and sediment concentrations and geochemistries. - Abstract: Biodynamic modelling was used to investigate the uptake and accumulation of three trace metals (Ag, As, Zn) by the deposit feeding estuarine bivalve mollusc Scrobicularia plana. Radioactive labelling techniques were used to quantify the rates of trace metal uptake (and subsequent elimination) from water and sediment diet. The uptake rate constant from solution (±SE) was greatest for Ag (3.954 ± 0.375 l g{sup −1} d{sup −1}) followed by As (0.807 ± 0.129 l g{sup −1} d{sup −1}) and Zn (0.103 ± 0.016 l g{sup −1} d{sup −1}). Assimilation efficiencies from ingested sediment were 40.2 ± 1.3% (Ag), 31.7 ± 1.0% (Zn) and 25.3 ± 0.9% (As). Efflux rate constants after exposure to metals in the solution or sediment fell in the range of 0.014–0.060 d{sup −1}. By incorporating these physiological parameters into biodynamic models, our results showed that dissolved metal is the predominant source of accumulated Ag, As and Zn in S. plana, accounting for 66–99%, 50–97% and 52–98% of total accumulation of Ag, As and Zn, respectively, under different field exposure conditions. In general, model-predicted steady state concentrations of Ag, As and Zn matched well with those observed in clams collected in SW England estuaries. Our findings highlight the potential of biodynamic modelling to predict Ag, As and Zn accumulation in S. plana, taking into account specific dissolved and sediment concentrations of the metals at a particular field site, together with local water and sediment geochemistries.

  10. de Granada (España

    Directory of Open Access Journals (Sweden)

    Francisco Jiménez Bautista

    2008-01-01

    Full Text Available Esta investigación pretende estudiar, analizar y diagnosticar el fenómeno de la prostitución en la ciudad de Granada, como un conflicto que configura unas nuevas formas de esclavitud en la realidad del siglo XXI. La prostitución es un tema que ha cobrado, a nivel institucional, una especial relevancia en los últimos años, especialmente desde la conferencia de Beijing y que plantea las principales dificultades que presentan estas mujeres dentro del mundo de la prostitución. La hipótesis que defendemos, en este artículo, es que la mujer que entra en el mundo de la prostitución, en un primer momento, lo hace por necesidad y posteriormente se vuelve adicta al dinero. Esa adicción hace que muchas mujeres no puedan salir de este mundo y terminan convirtiéndose en unas mercenarias del amor.

  11. Short- and long-term consequences of larval stage exposure to constantly and ephemerally elevated carbon dioxide for marine bivalve populations

    Directory of Open Access Journals (Sweden)

    C. J. Gobler

    2013-04-01

    Full Text Available While larval bivalves are highly sensitive to ocean acidification, the basis for this sensitivity and the longer-term implications of this sensitivity are unclear. Experiments were performed to assess the short-term (days and long-term (months consequences of larval stage exposure to varying CO2 concentrations for calcifying bivalves. Higher CO2 concentrations depressed both calcification rates assessed using 45Ca uptake and RNA : DNA ratios in Mercenaria mercenaria and Argopecten irradians larvae with RNA : DNA ratios being highly correlated with larval growth rates (r2>0.9. These findings suggested that high CO2 has a cascading negative physiological impact on bivalve larvae stemming in part from lower calcification rates. Exposure to elevated CO2 during the first four days of larval development significantly depressed A. irradians larval survival rates, while a 10-day exposure later in larval development did not, demonstrating the extreme CO2 sensitivity of bivalve larvae during first days of development. Short- (weeks and long-term (10 month experiments revealed that individuals surviving exposure to high CO2 during larval development grew faster when exposed to normal CO2 as juveniles compared to individuals reared under ambient CO2 as larvae. These increased growth rates could not, however, overcome size differences established during larval development, as size deficits of individuals exposed to even moderate levels of CO2 as larvae were evident even after 10 months of growth under normal CO2 concentrations. This "legacy effect" emphasizes the central role larval stage CO2 exposure can play in shaping the success of modern-day bivalve populations.

  12. Short and long term consequences of larval stage exposure to constantly and ephemerally elevated carbon dioxide for marine bivalve populations

    Directory of Open Access Journals (Sweden)

    C. J. Gobler

    2012-11-01

    Full Text Available While larval bivalves are highly sensitive to ocean acidification, the basis for this sensitivity and the longer term implications of this sensitivity are unclear. Experiments were performed to assess the short term (days and long term (months consequences of larval stage exposure to varying CO2 concentrations for calcifying bivalves. Higher CO2 concentrations depressed both calcification rates assessed using 45Ca uptake and RNA:DNA ratios in Mercenaria mercenaria and Argopecten irradians larvae with RNA:DNA ratios being highly correlated with larval growth rates r2 > 0.9. These findings suggested that high CO2 has a cascading negative physiological impact on bivalve larvae stemming in part from lower calcification rates. Exposure to elevated CO2 during the first four days of larval development significantly depressed A. irradians larval survival rates, while a 10 day exposure later in larval development did not, demonstrating the extreme CO2-sensitivity of bivalve larvae during first days of development. Short- (weeks and long-term (10 month experiments revealed that individuals surviving exposure to high CO2 during larval development grew faster when exposed to normal CO2 as juveniles compared to individuals reared under ambient CO2 as larvae. These increased growth rates could not, however, overcome size differences established during larval development, as size deficits of individuals exposed to even moderate levels of CO2 as larvae were evident even after 10 months of growth under normal CO2 concentrations. This `legacy effect' emphasizes the central role larval stage CO2 exposure can play in shaping the success of modern day bivalve populations.

  13. Accumulation and detoxification of paralytic shellfish poison (PSP) in hard clam Meretrix meretrix%麻痹性贝毒在文蛤体内的累积及净化技术研究

    Institute of Scientific and Technical Information of China (English)

    沈和定; 付金花; 冉福

    2011-01-01

    There were two stages in the experiment, accumulation and detoxification. Accumulation PSP by hard clam Meretrix meretrix achieved by feeding clams certain amount paralytic shellfish poison (PSP) every day and detecting PSP periodically. The detoxification was determined by method of"inner discharge and out purification". We found that the clam had a low ability to accumulate PSP. It reached to 884μg/100g after exposed to toxic A. tamarense for 15 d and the toxins in the viscera were higher than in other muscles, accounting to 77.4% - 89.1%. The amounts of PSP decreased in three groups with the elimination rates of the control group 30.1%, ozone purified group 32.8%, group of inner discharge and out purification 47.2% during detoxification. This research showed that "inner discharge and out purification" could accelerate PSP detoxification.%试验研究分毒素累积和解毒两个阶段,丈蛤(Meretrix meretrix)对麻痹性贝毒(Paralytic Shellfish Poisoning,PSP)的累积能力试验中每天投喂一定量塔玛亚历山大藻(Alexandrium tamarense),定期测定丈蛤体内的毒素含量;解毒试验通过投喂饵料和水体消毒的“内排外解”法进行。结果表明:文蛤对麻痹性贝毒的累积能力较弱,累积试验末期(15d)的内脏毒素累积量仅为884μg/100g,内脏中毒素累积量高于肌肉,占全贝的77.4%~89.1%。15d的解毒试验

  14. First genotoxicity study of Paraná river water from Argentina using cells from the clam Corbicula fluminea (Veneroida Corbiculidae and Chinese hamster (Cricetulus griseus Rodentia, Cricetidae K1 cells in the comet assay

    Directory of Open Access Journals (Sweden)

    Jacqueline D. Caffetti

    2008-01-01

    Full Text Available High concentrations of xenobiotics from urban and industrial wastes have contributed to the contamination of many aquatic environments. We used the comet assay to evaluate the genotoxic potential of water collected from the River Paraná, which receives a great deal of waste, at three points (Puerto Piray, Eldorado and Montecarlo in the Misiones Province of Argentina. The in vivo comet assay used 40 freshwater clams (Corbicula fluminea while the in vitro comet assay used Chinese hamster (Cricetulus griseus K1 cell (CHO-K1 cultures with the mutagen ethyl methanesulfonate (EMS as the positive control and phosphate buffered saline (PBS as the negative control. Both assays showed statistically significant differences between the three sampling sites in relation to the negative control, the results of this preliminary study indicating that at these three sites water from the Paraná River presents genotoxic potential.

  15. An innovative method based on quick, easy, cheap, effective, rugged, and safe extraction coupled to desorption electrospray ionization-high resolution mass spectrometry for screening the presence of paralytic shellfish toxins in clams.

    Science.gov (United States)

    Mattarozzi, Monica; Bianchi, Federica; Milioli, Marco; Cavazza, Antonella; Careri, Maria

    2016-01-15

    The capabilities of desorption electrospray ionization-high resolution mass spectrometry (DESI-HRMS) were tested for screening the presence of some paralytic shellfish toxins in clams. A quick, easy, cheap, effective, rugged, and safe (QuEChERS) approach is proposed for sample clean-up. QuEChERS extraction was optimized by using a full factorial design followed by the multicriteria method of the desirability functions. Quantitation limits in the microgram per kilogram range proved reliability of the method for the detection of the investigated toxins in accordance to the rules laid down by European legislation. The optimized QuEChERS-DESI-HRMS based-method allowed for a rapid reliable screening of the investigated compounds at levels of interest, thus being useful for high-throughput analyses. PMID:26592627

  16. Allozymic variation in the clam genus Eurhomalea (Bivalvia: Veneriidae) along southern South American coast Variación alozímica en el género de almejas Eurhomalea (Bivalvia: Veneriidae) a lo largo de la costa sur de Sudamérica

    OpenAIRE

    M.H GALLARDO; González, C; Mena, C; Lomovasky, B.; Morriconi, E.; E CLASING

    2003-01-01

    The correspondence between allozymic variation and specific differentiation was studied in four populations corresponding to the three nominal, allopatric species of clam genus Eurhomalea (E. rufa, E. lenticularis, E. exalbida) described for southern South America. Allozyme variation scored in 12 loci was high as indicated by heterozygosity levels (15.8-20.7 %) and by the presence of only three monomorphic loci (Hk-2, Icd-2, and Xdh-1). These high estimates of allelic variability were influen...

  17. Corrosion resistance for ODS-CLAM steel in a static Pb-Bi environment%ODS-CLAM钢抗静态Pb-Bi腐蚀性能的初步研究

    Institute of Scientific and Technical Information of China (English)

    刘玉贞; 孙钦星

    2014-01-01

    含碳量不同(0.1%、0.2%质量分数)氧化物弥散强化铁素体/马氏体钢(ODS-CLAM)在100 h、500℃饱和氧含量条件下进行静态Pb-Bi腐蚀实验.采用SEM、EDS、电子万能试验机表征样品腐蚀实验前后的变化.结果表明:腐蚀实验过后,两种样品表面均形成厚度10 μm的氧化层,其主要成分为Fe-Cr-O,含碳量0.2%样品内部出现Fe-C-O的颗粒.腐蚀试验后两种样品的力学性能均降低,主要表现为均匀延伸率的下降,而抗拉强度降低较少,对低碳含量的样品而言其屈服强度降低更明显,拉伸断口形貌在腐蚀试验前后没有出现明显的变化.

  18. Effects of water salinity on the antioxidant enzyme activities and growth of clam Cyclina sinensis%盐度对青蛤抗氧化酶活性及生长的影响

    Institute of Scientific and Technical Information of China (English)

    李子牛; 林听听; 么宗利; 来琦芳; 陆建学; 王慧; 周凯

    2012-01-01

    为了弄清盐度对青蛤(Cyclina sinensis)生长及免疫相关酶的影响,以期探讨其在不同盐度环境下养殖的可能性,本文研究了青蛤在盐度10、15、25(对照)和35下,0、3、6、12、24、48、96 h内鳃、外套膜和肝胰腺中抗氧化酶(超氧化物歧化酶(SOD)和过氧化氢酶(CAT))的活性变化;同时研究了不同盐度下青蛤养殖2个月的月增长率和增重率变化.结果表明:青蛤不同组织中SOD和CAT活性以肝胰腺最高,外套膜次之,鳃最低.盐度10时,鳃中的SOD活性于3h显著高于对照盐度(P<0.05);外套膜中的SOD活性于3、6、12、24 h,CAT活性于6、12 h与对照有显著差异(P<0.05);肝胰腺中的SOD活性于3、6、12、24h,CAT活性于3、6h显著高于对照(P<0.05).盐度15时,仅肝胰腺中的SOD和CAT活性于3h显著高于对照(P<0.05).而盐度35时,鳃中的SOD活性于3、6h,CAT活性于3h显著高于对照(P<0.05);外套膜中的SOD和CAT活性于3、6、12、24 h与对照有显著差异(P<0.05);肝胰腺中的SOD和CAT活性几乎整个时间段均与对照有显著差异(P<0.05).此外,盐度35时的SOD和CAT活性波动幅度显著高于盐度10(P<0.05).月增长率和增重率方面:盐度15较快,与对照无显著差异(P>0.05),各月间也无显著差异(P>0.05);盐度10则显著低于盐度15和对照,并且盐度10第2月份显著高于第1月份(P<0.05);而盐度35则极缓慢,各月间也无显著差异(P>0.05).研究表明,青蛤受盐度胁迫时其抗氧化酶的波动基本于胁迫后的前24 h内完成,青蛤对低盐的耐受性强于高盐,盐度高于35时青蛤抗氧化酶波动剧烈,且生长极慢.%In order to clarify the effects of water salinity on the growth and immune enzymes of clam Cyclina sinensis , and accordingly, to explore the possibility of breeding C. sinensis in different salinity environment, the individuals of the clam were undergone different salinity stress (10, 15, 25 (control

  19. Use of Population Parameters in Examining Changes in the Status of the Short-Necked Clam Paphia undulata Born, 1778 (Mollusca, Pelecypoda: Veneridae in Coastal Waters of Southern Negros Occidental

    Directory of Open Access Journals (Sweden)

    Anabelle del Norte Campos

    2010-06-01

    Full Text Available Growth, recruitment, mortality and exploitation rate of the short-necked clam Paphia undulata (Born, 1778 were studied in southern Negros Occidental waters between August 2007 and July 2008 from length-frequency data derived from catches of divers, to be able to compare with earlier data derived and analyzed 13 years ago by Agasen et al. (1998. Both sets of data were analyzed using the FiSAT software (Gayanilo & Pauly, 1997. The asymptotic shell length (S¥ = 79 mm derived from the present data proved to be smaller compared to the earlier data (SL¥ = 81.5 mm due to the lack of bigger sizes in the present samples. The growth constant (K = 1.0 yr-1 was however comparable indicating it to be a more species-characteristic parameter. Two recruitment pulses for each study were derived and were found to be correlated with the spawning pattern in the species. The value of natural mortality (M = 1.57 yr-1 derived from bivalve literature, is deemed more appropriate compared to the earlier estimate (M = 2.89 yr-1 based on Pauly’s (1980 empirical equation developed for fish. Total mortality (Z values for both studies were comparable, but a higher level of fishing mortality (F = 4.61 yr-1 was estimated for the present data set, thus resulting likewise in a higher exploitation rate (E = 0.75. These, together with fishery information from an accompanying paper (Villarta & del Norte-Campos, 2010, not only validate the earlier findings of overexploitation due to lack of management, but reveal a worsening condition of the stock, most likely as a result of growth overfishing. Overexploitation can only be mitigated by imposing stringent restrictions in terms of the minimum size for exploitation (45 mm shell length and closed seasons during the spawning peak (August-November.

  20. Molecular characteristics and expression analysis of ScHsc70 cDNA in agamaki clam (Sinonovacula constricta)%缢蛏ScHsc70cDNA的分子特性和表达分析

    Institute of Scientific and Technical Information of China (English)

    冯冰冰; 牛东红; 钟玉民; 陈慧; 林国文; 李家乐

    2012-01-01

    Heat shock proteins consist of several families of highly conserved proteins that play an essential role in a number of cellular processes. Among the 70 kD family of heat shock proteins, heat shock cognate protein 70 kD (Hsc70) and inducible heat shock protein 70 kD (Hsp70) have been extensively studied in vertebrates and invertebrates. Several cDNAs encoding HSP70 have been described in molluscs, including the oyster (Crassostrea gigas), bay scallop (Argopecten irradians), Zhikong scallop (Chlamys farreri), mussel (Mytilus galloprovincialis), and Asiatic hard clam (Meretrix meretrix). Recent studies examining HSP70 expression in different species of mollusc have recognized the physiological and ecological importance of heat-shock gene expression in response to changing environments. We isolated an EST sequence with high homology with heat shock protein 70 gene from the cDNA library of Sinonovacula constricta. Then, the complete express sequence of this gene was obtained using PCR and 5'RACE. The cDNA of this gene was 2 335 bp, and consisted of a 76 bp 5' untranslated region (UTR), a 1 950 bp open reading frame (ORF) and a 309 bp 3' UTR. The translated protein consisted of 649 amino acids (70.89 kD)and its calculated isoelectric point was 5.28. Sequence analysis of the protein revealed that this gene contained three signature sequences of the heat shock protein 70 family (HSP70 family), two glycosylation sites and one ATP-GTP binding site. Four terapeptides of GGXP and a cytoplasm characteristic motif of EEVD were detected in the carboxyl terminal region of the deduced amino acid sequence. This HSP70 is a member of the HSC70 (constitutive genes) subfamily in the HSP70 family, and is designated as ScHsc70. Phylogenetic analysis suggested that the protein was most similar to those of 5. Constricta, Laternula elliptica, and M. Meretrix. Quantitative reverse transcriptase (qRT-PCR) analyses revealed that ScHsc70 mRNA was expressed constitutively in all the tissues

  1. Light induces changes in activities of Na(+)/K(+)-ATPase, H(+)/K(+)-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam, Tridacna squamosa.

    Science.gov (United States)

    Ip, Yuen K; Ching, Biyun; Hiong, Kum C; Choo, Celine Y L; Boo, Mel V; Wong, Wai P; Chew, Shit F

    2015-01-01

    The objective of this study was to determine the effects of 12 h of exposure to light, as compared with 12 h of exposure to darkness (control), on enzymatic activities of transporters involved in the transport of NH(+) 4 or H(+), and activities of enzymes involved in converting NH(+) 4 to glutamate/glutamine in inner mantle, outer mantle, and ctenidia of the giant clam, Tridacna squamosa. Exposure to light resulted in a significant increase in the effectiveness of NH(+) 4 in substitution for K(+) to activate Na(+)/K(+)-ATPase (NKA), manifested as a significant increase in the Na(+)/NH(+) 4-activated-NKA activity in the inner mantle. However, similar phenomena were not observed in the extensible outer mantle, which contained abundant symbiotic zooxanthellae. Hence, during light-enhanced calcification, H(+) released from CaCO3 deposition could react with NH3 to form NH(+) 4 in the extrapallial fluid, and NH(+) 4 could probably be transported into the shell-facing inner mantle epithelium through NKA. Light also induced an increase in the activity of glutamine synthetase, which converts NH(+) 4 and glutamate to glutamine, in the inner mantle. Taken together, these results explained observations reported elsewhere that light induced a significant increase in pH and a significant decrease in ammonia concentration in the extrapallial fluid, as well as a significant increase in the glutamine concentration in the inner mantle, of T. squamosa. Exposure of T. squamosa to light also led to a significant decrease in the N-ethylmaleimide (NEM)-sensitive-V-H(+)-ATPase (VATPase) in the inner mantle, and significant increases in the Na(+)/K(+)-activated-NKA, H(+)/NH(+) 4-activated-H(+)/K(+)-ATPase, and NEM-sensitive-VATPase activities in ctenidia, indicating that light-enhanced calcification might perturb Na(+) homeostasis and acid/base balance in the hemolymph, and might involve the active uptake of NH(+) 4 from the environment. This is the first report on light having direct

  2. Light induces changes in activities of Na+/K+(NH4+-ATPase, H+/K+(NH4+-ATPase and glutamine synthetase in tissues involved directly or indirectly in light-enhanced calcification in the giant clam Tridacna squamosa

    Directory of Open Access Journals (Sweden)

    Alex Y K Ip

    2015-03-01

    Full Text Available The objective of this study was to determine the effects of 12 h of exposure to light, as compared with 12 h of exposure to darkness (control, on enzymatic activities of transporters involved in the transport of NH4+ or H+, and activities of enzymes involved in converting NH4+ to glutamate/glutamine in inner mantle, outer mantle and ctenidia of the giant clam, Tridacna squamosa. Exposure to light resulted in a significant increase in the effectiveness of NH4+ in substitution for K+ to activate Na+/K+-ATPase (NKA, manifested as a significant increase in the Na+/NH4+-activated-NKA activity in the inner mantle. However, similar phenomena were not observed in the extensible outer mantle, which contained abundant symbiotic zooxanthellae. Hence, during light-enhanced calcification, H+ released from CaCO3 deposition could react with NH3 to form NH4+ in the extrapallial fluid, and NH4+ could probably be transported into the shell-facing inner mantle epithelium through NKA. Light also induced an increase in the activity of glutamine synthetase, which converts NH4+ and glutamate to glutamine, in the inner mantle. Taken together, these results explained observations reported elsewhere that light induced a significant increase in pH and a significant decrease in ammonia concentration in the extrapallial fluid, as well as a significant increase in the glutamine concentration in the inner mantle, of T. squamosa. Exposure of T. squamosa to light also led to a significant decrease in the N-ethylmaleimide (NEM-sensitive-V-H+-ATPase (VATPase in the inner mantle, and significant increases in the Na+/K+-activated-NKA, H+/NH4+-activated-H+/K+-ATPase and NEM-sensitive-VATPase activities in ctenidia, indicating that light-enhanced calcification might perturb Na+ homeostasis and acid/base balance in the hemolymph, and might involve the active uptake of NH4+ from the environment. This is the first report on light having direct enhancing effects on activities of certain

  3. A Large Metabolic Carbon Ccontribution to the δ13C Record in Marine Aragonitic Bivalve Shells

    Science.gov (United States)

    Gillikin, D. P.; Lorrain, A.; Dehairs, F.

    2006-12-01

    The stable carbon isotopic signature archived in bivalve shells was originally thought to record the δ13C of seawater dissolved inorganic carbon (δ13C-DIC). However, more recent studies have shown that the incorporation of isotopically light metabolic carbon (M) significantly affects the δ13C signal recorded in biogenic carbonates. To assess the M contribution to Mercenaria mercenaria shells collected in North Carolina, USA, we sampled seawater δ13C-DIC, tissue, hemolymph and shell δ13C. We found up to a 4‰ decrease through ontogeny in shell δ13C in a 23 year old individual. There was no correlation between shell height or age and tissue δ13C. Thus, the ontogenic decrease observed in the shell δ13C could not be attributed to changes in food sources as the animal ages leading to more negative metabolic CO2, since this would require a negative relationship between tissue δ13C and shell height. Hemolymph δ13C, on the other hand, did exhibit a negative relationship with height, but the δ13C values were more positive than expected, indicating that hemolymph may not be a good proxy of extrapallial fluid δ13C. Nevertheless, the hemolymph data indicate that respired CO2 does influence the δ13C of internal fluids and that the amount of respired CO2 is related to the age of the bivalve. The percent metabolic C incorporated into the shell (%M) was significantly higher (up to 37%) than has been found in other bivalve shells, which usually contain less than 10 %M. Attempts to use shell biometrics to predict %M could not explain more than ~60% of the observed variability. Moreover, there were large differences in the %M between different sites. Thus, the metabolic effect on shell δ13C cannot easily be accounted for to allow reliable δ13C-DIC reconstructions. However, there does seem to be a common effect of size, as all sites had indistinguishable slopes between the %M and shell height (+0.19% per mm of shell height).

  4. Utilização do farelo de conchas de vôngole na adsorção de fósforo e como corretivo da acidez do solo Utilization of ground clam shells in the adsorption of phosphorus and for correction of soil acidity

    Directory of Open Access Journals (Sweden)

    Paola A. V. Lo Monaco

    2012-10-01

    Full Text Available Teve-se o objetivo de, com a realização deste trabalho, obter a curva de neutralização do pH de amostras dos horizontes A e B de um Latossolo Vermelho-Amarelo distrófico, utilizando-se de farelo de conchas de vôngole (Anomalocardia brasiliana; além disso, avaliar a capacidade de adsorção de fósforo, obtendo-se a isoterma de adsorção de melhor ajuste aos dados obtidos. Verificou-se que o farelo de concha de vôngole apresenta potencial para uso como corretivo de acidez do solo e que a dose recomendada para correção do pH do horizonte A do Latossolo Vermelho Amarelo distrófico estudado foi de 2,92 t ha-1, enquanto, para correção do horizonte B, foi de 3,35 t ha-1. O farelo de conchas de vôngole também apresentou alta capacidade de adsorção de fósforo, o que indica possibilidades de sua utilização em sistemas que visem à remoção deste elemento químico de águas residuárias. Os modelos de Langmuir e Freundlich ajustaram-se bem aos dados e podem ser utilizados para representar a isoterma de adsorção de fósforo.The objective of this study was to obtain the curve of pH neutralization for samples of the horizons A and B of a dystrophic Rhodic Haplustox soil using ground clam shells (Anomalocardia brasiliana, as well as assess the capacity of phosphorus adsorption to obtain the adsorption isotherm that best fit to the data obtained. It was found that the ground clam shells present potential to be used in soil acidity correction and that the recommended dose for pH correction of horizon A of the dystrophic Rhodic Haplustox studied was 2.92 t ha-1, while for correction of horizon B was 3.35 t ha-1. The ground clam shells also showed high adsorption capacity for phosphorus, which indicates possibilities of its use in systems targeting the removal of this chemical from wastewater. The Langmuir and Freundlich models fit well to the data and may be used to represent the adsorption isotherm.

  5. 菲律宾蛤仔(Ruditapes philippinarum)漆酶型酚氧化酶的纯化及特性分析%PURIFICATION AND CHARACTERIZATION OF LACCASE-TYPE PHENOLOXIDASE FROM THE CLAM RUDITAPES PHILIPPINARUM

    Institute of Scientific and Technical Information of China (English)

    蒋经伟; 邢婧; 战文斌

    2012-01-01

    采用非变性电泳结合特异性底物发色方法从菲律宾蛤仔血细胞中分离出一种酚氧化酶,研究了该酶的酶促反应动力学参数,金属离子、抑制剂对酶活的影响。结果表明,分离获得的酚氧化酶分子量约为563kDa;对底物邻苯二酚、左旋多巴(L—DOPA)、多巴胺、对苯二酚的米氏常数如分别为0.42、1.60、1.79和1.76mmol/L;酶的活性在Mg2+、Zn2+、Mn2十、Fe2+、Cu2中和ca斗浓度为5、10、20、30mmol/L时受到抑制;酶的活性可被抑制剂抗坏血酸、二乙基二硫代氨基甲酸钠(DETC)、半胱氨酸、亚硫酸钠、柠檬酸、乙二胺四乙酸二钠(EDTA)、叠氮钠和硫代尿素等抑制。根据底物特异性、抑制剂等结果,所分离获得的酚氧化酶属于漆酶型的含铜酚氧化酶。%In this paper, a phenoloxidase (PO) of clam Ruditapes philippinarum was purified from hemocytes using linear-gradient native-PAGE combined with catechol staining. The results showed that this PO had a molecular mass of 563kDa in native-PAGE. Kinetics determination indicated that the K,, values of PO for catechol, L-DOPA, dopamine and hydroquinone were 0.42, 1.60, 1.79 and 1.76mmol/L, respectively. The PO activity was inhibited by Mg2+,Zn2+,Mn2+,Fe2+,Cu2+,and Ca2+ at concentrations of 5, 10, 20, 30mmol/L, and also inhibited by inhibitors including ascorbic acid, sodium diethyldithiocarbamate (DETC), cysteine, sodium sulfite, citric acid, ethylenediaminetetraacetic acid disodium (EDTA), sodium azide and thiourea. Based on the substrate specificity and the results of inhibition, it could be concluded that this PO was a laccase-type copper-containing phenoloxidase.

  6. The Tridacna Clams of Rose Atoll

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Report to American Samoa Department of Marine and Wildlife Resources on surveys conducted 1013 November 1980 to assess distribution, abundance, density, and...

  7. La globalización y la violencia.

    Directory of Open Access Journals (Sweden)

    Amelia Imbriano.

    2004-03-01

    Full Text Available “Tal como están ahora las cosas…el más imperioso de todos los problemas que la civilización debe enfrentar …es este: Hay algún camino para evitar a la humanidad los estragos de la guerra?. El logro de una seguridad internacional implica la renuncia incondicional de todas las naciones a su libertad de acción, vale decir, a su soberanía…El hambre de poder político guiado por aspiraciones puramente mercenarias, indiferentes a las consideraciones y moderaciones sociales, ven en la guerra, en la fabricación y venta de armamentos, nada más que una ocasión para favorecer sus intereses particulares y extender su autoridad…Cómo es que estos procedimientos logran despertar en los hombres tan salvaje entusiasmo hasta llevarlos a sacrificar su vida?... Cómo es posible que esta pequeña caramilla someta al servicio de sus ambiciones la voluntad de la mayoría, para la cual el estado de guerra representa pérdidas y sufrimientos?...Todo intento de darle solución ha terminado en un lamentable fracaso”. Albert Einstein, 30 de julio de 1932(1

  8. De dragones, cascos y soldados de fortuna en el Occidente Antiguo. acerca de dos obras recientes sobre el mercenariado galo e hispano

    Directory of Open Access Journals (Sweden)

    García Jiménez, Gustavo

    2015-12-01

    Full Text Available Research on ancient mercenaries is fraught with problems, being the match between the scarce and partial data provided by the literary sources and the archaeological record a tricky and difficult matter. The recent publication of two books dealing with Iberian and Celtic mercenaries, by Raimon Graells and Luc Baray respectively, offers us an opportunity to dwell on a pervading discussion when studying cultural and military dynamics, and long distance relationships in Ancient Western Europe.La actividad mercenaria en la Antigüedad es uno de los campos de estudio más complejos de la investigación histórica, en buena medida debido a la difícil combinación que existe entre los siempre parciales datos de las fuentes literarias y la arqueología. La reciente publicación de dos monografías dedicadas al mercenario ibérico y celta, a cargo respectivamente de Raimon Graells y Luc Baray, nos brinda una magnífica oportunidad para retomar una vieja discusión siempre latente en el estudio de las dinámicas bélicas y culturales, y que nos permite ahondar en las intrincadas relaciones a larga distancia en el Occidente europeo antiguo.

  9. Permanent genetic resources added to Molecular Ecology Resources Database 1 August 2011-30 September 2011.

    Science.gov (United States)

    A'Hara, S W; Amouroux, P; Argo, Emily E; Avand-Faghih, A; Barat, Ashoktaru; Barbieri, Luiz; Bert, Theresa M; Blatrix, R; Blin, Aurélie; Bouktila, D; Broome, A; Burban, C; Capdevielle-Dulac, C; Casse, N; Chandra, Suresh; Cho, Kyung Jin; Cottrell, J E; Crawford, Charles R; Davis, Michelle C; Delatte, H; Desneux, Nicolas; Djieto-Lordon, C; Dubois, M P; El-Mergawy, R A A M; Gallardo-Escárate, C; Garcia, M; Gardiner, Mary M; Guillemaud, Thomas; Haye, P A; Hellemans, B; Hinrichsen, P; Jeon, Ji Hyun; Kerdelhué, C; Kharrat, I; Kim, Ki Hwan; Kim, Yong Yul; Kwan, Ye-Seul; Labbe, Ellen M; LaHood, Eric; Lee, Kyung Mi; Lee, Wan-Ok; Lee, Yat-Hung; Legoff, Isabelle; Li, H; Lin, Chung-Ping; Liu, S S; Liu, Y G; Long, D; Maes, G E; Magnoux, E; Mahanta, Prabin Chandra; Makni, H; Makni, M; Malausa, Thibaut; Matura, Rakesh; McKey, D; McMillen-Jackson, Anne L; Méndez, M A; Mezghani-Khemakhem, M; Michel, Andy P; Paul, Moran; Muriel-Cunha, Janice; Nibouche, S; Normand, F; Palkovacs, Eric P; Pande, Veena; Parmentier, K; Peccoud, J; Piatscheck, F; Puchulutegui, Cecilia; Ramos, R; Ravest, G; Richner, Heinz; Robbens, J; Rochat, D; Rousselet, J; Saladin, Verena; Sauve, M; Schlei, Ora; Schultz, Thomas F; Scobie, A R; Segovia, N I; Seyoum, Seifu; Silvain, J-F; Tabone, Elisabeth; Van Houdt, J K J; Vandamme, S G; Volckaert, F A M; Wenburg, John; Willis, Theodore V; Won, Yong-Jin; Ye, N H; Zhang, W; Zhang, Y X

    2012-01-01

    This article documents the addition of 299 microsatellite marker loci and nine pairs of single-nucleotide polymorphism (SNP) EPIC primers to the Molecular Ecology Resources (MER) Database. Loci were developed for the following species: Alosa pseudoharengus, Alosa aestivalis, Aphis spiraecola, Argopecten purpuratus, Coreoleuciscus splendidus, Garra gotyla, Hippodamia convergens, Linnaea borealis, Menippe mercenaria, Menippe adina, Parus major, Pinus densiflora, Portunus trituberculatus, Procontarinia mangiferae, Rhynchophorus ferrugineus, Schizothorax richardsonii, Scophthalmus rhombus, Tetraponera aethiops, Thaumetopoea pityocampa, Tuta absoluta and Ugni molinae. These loci were cross-tested on the following species: Barilius bendelisis, Chiromantes haematocheir, Eriocheir sinensis, Eucalyptus camaldulensis, Eucalyptus cladocalix, Eucalyptus globulus, Garra litaninsis vishwanath, Garra para lissorhynchus, Guindilla trinervis, Hemigrapsus sanguineus, Luma chequen. Guayaba, Myrceugenia colchagüensis, Myrceugenia correifolia, Myrceugenia exsucca, Parasesarma plicatum, Parus major, Portunus pelagicus, Psidium guayaba, Schizothorax richardsonii, Scophthalmus maximus, Tetraponera latifrons, Thaumetopoea bonjeani, Thaumetopoea ispartensis, Thaumetopoea libanotica, Thaumetopoea pinivora, Thaumetopoea pityocampa ena clade, Thaumetopoea solitaria, Thaumetopoea wilkinsoni and Tor putitora. This article also documents the addition of nine EPIC primer pairs for Euphaea decorata, Euphaea formosa, Euphaea ornata and Euphaea yayeyamana. PMID:22136175

  10. Damages of coral reef ecosystem by the giant clam excavation--- a case study on North Reef of Xisha Islands%砗磲采挖对珊瑚礁生态系统的破坏--以西沙北礁为例

    Institute of Scientific and Technical Information of China (English)

    李元超; 韩有定; 陈石泉; 谢海群; 陈孝; 周治东

    2015-01-01

    The variations of coral reefs was compared before and after the excavation of giant clams on North Reef of Xisha Islands to illustrate the destructions on the coral reef ecosystem.The results showed that 29 coral species dis-appeared on the reef flat of North Reef in 2014 compared to that in 2012.Dominant species evolved from previous Acropora sp.to Montipora digitata.The diversity index of corals became low in the reef flat.Although North Reef maintained 52.83% of mean coral coverage,around 10% reduction in coral coverage was found in 2014 compared with that in 2012.Particularly,the coral coverage was reduced as much as 20% with bleaching corals at station 2. The findings suggest that North Reef,especially the reef flat,has suffered severe damages.As results,the numbers of coral species were deceased and the community structure altered besides the deceased of species diversity and coral coverage and increased of coral mortality.It is considered that the coral reef degradation on North Reef is re-sulted from the illegal excavation of giant clams,which is an important factor destroyed and threatened the health of coral reef ecosystem in the flat.%以西沙群岛北礁为例,通过对比采挖砗磲前后的数据,来说明该活动对珊瑚礁生态系统的破坏.2012~2014年间北礁礁坪上的造礁石珊瑚种类数量变动较大,减少了29种;优势种由之前的鹿角珊瑚(Acropora sp.)变为现在的指状蔷薇珊瑚(Montipora digitata);礁坪的物种多样性指数也处于较低的水平.虽然当前北礁的珊瑚覆盖率为52.83%,但是相比2012年降低了大约10%,尤其是2号站位,珊瑚覆盖率降低了约20%.同时2号站位出现了珊瑚白化死亡的现象.调查结果表明,北礁的珊瑚礁生态系统,尤其是礁坪上的珊瑚礁生态系统已经受到严重的破坏,珊瑚种类减少、群落结构改变、物种多样性降低、覆盖率下降、死亡率提高.通过分析

  11. Grown-out of seeds of the taquilla clam Mulinia edulis (King & Broderip, 1832 in the subtidal zone in northern Chile and in the intertidal zone in southern Chile Engorda de semillas de la almeja taquilla Mulinia edulis (King & Broderip, 1832 en la zona submareal en el norte y en la zona intermareal en el sur de Chile

    Directory of Open Access Journals (Sweden)

    Alejandro Abarca

    2012-09-01

    Full Text Available Seeds of the clam Mulinia edulis produced in a hatchery were grown in bottom cages in the subtidal zone of Tongoy Bay (northern Chile and in the intertidal zone of Chullec (Chiloé Island, southern Chile, to compare the growth and survival of small and large seeds of the same production in different environments and latitudes. Seeds were shipped twice to Chullec, once in summer and once in winter. Previous experiments with seed transportation (14.2 ± 2.4 mm showed that they are able to survive more than 24 h out of water. The growth rate of both large and small seeds was greater in Tongoy than in Chullec, reaching maxima of 1.24 mm month-1 in the small seeds of Tongoy and 1.06 mm month-1 in the same group in Chullec. The growth rates obtained for M. edulis were similar to those described for other cultured clams. Seeds grown in Chullec presented a significantly greater weight by size than the seeds grown in Tongoy. Survival after 12 months was 38% and 88% in Tongoy and 19.4% and 37.3% in Chullec for small and large seeds, respectively. Seeds produced in hatcheries are able to withstand long travel (1,360 km and grow in the intertidal zone of southern Chile, where the operation of the culture is simple and cheap. The growth curve presents an inflection point around 20 mm length, probably related to the age at sexual maturity. Growing out seeds in the intertidal zone in southern Chile is seen as a new activity for artisanal fishermen.Semillas de la almeja Mulinia edulis producidas en el Hatchery de Pesquera San José (Tongoy fueron engordadas en sistemas de fondo en la zona submareal de bahía Tongoy e intermareal en Chullec (Chiloé, para comparar el crecimiento y la supervivencia de semillas pequenas y grandes de una misma producción en diferentes ambientes y latitudes. Se realizaron dos envíos de semillas a Chullec, uno en verano y otro en invierno. Experimentos de simulación del transporte de semillas (14,2 ± 2,4 mm muestran que

  12. Allozymic variation in the clam genus Eurhomalea (Bivalvia: Veneriidae along southern South American coast Variación alozímica en el género de almejas Eurhomalea (Bivalvia: Veneriidae a lo largo de la costa sur de Sudamérica

    Directory of Open Access Journals (Sweden)

    M.H GALLARDO

    2003-09-01

    Full Text Available The correspondence between allozymic variation and specific differentiation was studied in four populations corresponding to the three nominal, allopatric species of clam genus Eurhomalea (E. rufa, E. lenticularis, E. exalbida described for southern South America. Allozyme variation scored in 12 loci was high as indicated by heterozygosity levels (15.8-20.7 % and by the presence of only three monomorphic loci (Hk-2, Icd-2, and Xdh-1. These high estimates of allelic variability were influenced by the low levels of interspecific genetic similarity (I = 0.64 and for the high conspecific values of genetic identity observed. The high estimates of substructuring found at the species level (F ST = 0.39 contrasted with the low differentiation (F ST = 0.027 and high migration rate (Nm = 9 existing among conspecific samples. Diagnostic allele fixation coinciding with specific recognition was recorded at locus Hk-1 whereas nearly-fixed differences at loci (Adh, alpha-Gpd, Icd-1, Ldh, Odh, Pgm-3 differed sharply in frequency among species. The Wagner procedure and the neighbor-joining algorithm produced a similar tree topology highly related to the geographic distance and to their taxonomic recognition. The lack of coincidence between patterns of allozymic variation and the two distinctive shell morphs (flat and globoid occurring in E. exalbida from Ushuaia bay do not support their taxonomic recognition.Se estudió la correspondencia entre la variación bioquímica y la diferenciación específica en cuatro poblaciones correspondientes a las tres especies nominales y alopátricas en las almejas del género Eurhomalea (E. rufa, E. lenticularis, E. exalbida descritas para la zona sur de Sudamérica. La variación alozímica registrada en 12 loci fue alta como lo indican los altos niveles de heterocigosidad (15,8-20,7 % y por la presencia de solo tres loci monomórficos (Hk-2, Icd-2 y Xdh-1. Esta alta estimación de variabilidad alélica influyó en los bajos

  13. 36Cl-AMS measurements with 3-MV tandem accelerator

    International Nuclear Information System (INIS)

    36C- is one of the most interesting nuclides in accelerator mass spectrometry (AMS) measurements. The application of 36Cl has been widely applied in various fields. All most all of 36Cl AMS measurements at natural isotopic concentrations have yet been performed at tandem accelerator with 5 MV or higher terminal voltage. The measure improvement of 36Cl and other medium heavy isotopes performed at 3 MV in AMS facilities is one of the hottest topics in AMS measurements. In order to increase the suppression factor of 36S, the energy loss straggling and angular straggling of 36Cl and 36S ions in various counter gases (P10, isobutane and propane) were investigated. Some groundwater samples were measured with energy of 32 MeV, and the results were in good agreement with the result obtained with ion energy of 72 MeV. The results indicate that the approximate detection limit of 36Cl in 3 MV AMS facility is 36Cl/Cl=1 × 10-14, and the uncertainty is 30% when the sample with isotopic ration 36Cl/Cl≈10-13. (authors)

  14. Viewpoint – Happy Like a Clam in French Water

    Directory of Open Access Journals (Sweden)

    Pierre-Frédéric Ténière-Buchot

    2013-06-01

    Full Text Available After a few lines about his personal history, the author presents the legal context for water in France in the last century, and describes the hesitant first steps of the French Agences de l’Eau during the 1970s. While the financial system of French water policy is presented in detail, the role of economic transfers between various categories of water users is underlined. Then, the general socio-political aspects of French water governance are explained. A diagram illustrating the financial decision-making procedure for water (the 'water wheel' is given. Simple advice is drawn from the experience of a CEO of a water agency: the most useful skill for a water professional is to know how to swim…

  15. Assessment of the toxicity of sediment and seawater polluted by the Prestige fuel spill using bioassays with clams (Venerupis pullastra, Tappes decussatus and Venerupis rhomboideus) and the microalga Skeletonema costatum; Evaluacion de la toxicidad de sedimento y agua de mar contaminados por el vertido de fuel del Prestige, mediante el uso de bioensayos con las almejas Venerupis pullastra, Tappes decussatus y Venerupis rhomboideus y la microalga Skeletonema costatum

    Energy Technology Data Exchange (ETDEWEB)

    Marino-Balsa, J.C.; Perez, P.; Estevez-Blanco, P.; Saco-Alvarez, L.; Fernandez, E.; Beiras, R. [Laboratorio de Ecologia Marina LEM, Facultad de Ciencias, Universidad de Vigo, Galicia (Spain)

    2003-03-15

    In this study we present the early monitoring of the pollution caused by the accident of the Prestige tanker off the Galician coast. To evaluate the toxicity of sediment and water exposed to fuel, three kinds of bioassays were carried out using juvenile clams, clam embryos and microalgae. Firstly, the burrowing behavior of Venerupis pullastra and Tappes decussatus in the sediment collected from two beaches of similar characteristics but different pollution conditions, was studied over 24 h. No significant differences were observed between the two sediments. Secondly, embryogenesis success of Venerupis rhomboideus was recorded after incubation in seawater and elutriates obtained from affected areas. In this case, fuel-polluted seawater showed a marked inhibition of embryogenesis, while sediment elutriates showed moderate toxicity. Parallel bioassays with the diatom Skeletonema costatum were carried out using sediment elutriates and filtered seawater from the sampling sites. The response variable measured was the maximum quantum yield of photosynthesis ({phi}{sub p}o) using a Fast Repetition Rate Fluorometer (FRRF). In the first sampling, significant differences were found in the response of S. costatum cultured in the elutriates as compared to the control after 5 h exposure. The results corresponding to the second sampling showed statistically significant lower values of {phi}{sub p}o in the culture incubated in M2 water as compared with the control, indicating that the water-accommodated fraction of fuel at this site was the most toxic. [Spanish] En este estudio presentamos los primeros resultados obtenidos del control de la contaminacion producida por el accidente del petrolero Prestige en la costa de Galicia. Para evaluar la toxicidad del agua y el sedimento expuestos al fuel, se realizaron tres tipos de bioensayos: usando almejas juveniles, embriones de almeja y una microalga. En los primeros, se evaluo el comportamiento de enterramiento de Venerupis pullastra y

  16. Presiones Antropogenicas y su relación con la Calidad Ambiental de la Ecoregion del Golfo de Batabanó. Impactos Y Respuestas.

    Directory of Open Access Journals (Sweden)

    Eusebio Perigó Arnaud

    2005-01-01

    Full Text Available El Golfo de Batabanó se encuentra situado en la porción SW de la plataforma insular cubana. Su área es de 20850 km2 con una profundidad media de 6m. Esta plataforma tiene el mayor peso económico en la industria pesquera de Cuba, aportando más de la mitad de la producción de la langosta espinosa (Panulirus argus y volúmenes considerables de peces y otras especies marinas de alto valor comercial como son el camarón blanco (Litopenaeus schmitti, el camarón rosado (Litopenaeus notialis, cangrejo moro (Menippe mercenaria, la biajaiba (Lutjanus sinagris y el caballerote (Lutjanus griseus. Además, posee un elevado potencial como zona de cría natural de camarón en la Ensenada de la Broa, el cual disminuyó sus poblaciones en forma drástica debido a su sobre explotación en 1950, y por la misma causa en la década de los años 80. En los últimos años se ha comenzado a desarrollar el turismo con la explotación de algunos sitios como María La Gorda, Cayo Largo del Sur y Punta Francés. La ecorregión del Golfo ha experimentado afectaciones en su calidad ambiental debido a presiones antropogénicas derivadas de las actividades industriales, agropecuarias y domésticas, y en los últimos tiempos las actividades turísticas. En este trabajo se presentan los balances de las cargas de las principales fuentes de contaminación y otras acciones antropogénicas como la tala de vegetación circundante, construcción de un dique costero, represamientos excesivos de ríos, dragado e inadecuado manejo de los recursos pesqueros. También se dan las concentraciones medias de las principales variables de estado químicas indicadoras de contaminación orgánica y del estado trófico a partir de 1973 hasta el 2003. Al mismo tiempo se indican los principales impactos ambientales y propuestas de medidas para el desarrollo sustentable de la ecorregión.

  17. Gametogenic development and spawning of the mud clam, Polymesoda erosa (Solander, 1876) at Chorao Island, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Clemente, S.; Ingole, B.S.

    The reproductive cycle of Polymesoda erosa was studied over a 12 - month period from July 2004 to July 2005 at Chorao Island, Goa, India. Macroscopic observation revealed that Polymesoda erosa is dioecious and gametogenic development was synchronous...

  18. Do Management Systems Foster Social Capital? Empirical Evidence from Japanese Surf Clam Fisheries

    OpenAIRE

    Tegawa, Mihoko; Uchida, Hirotsugu

    2015-01-01

    We empirically examine the social effect of management systems. We focus on a particular management practice employed in self-governed coastal fisheries in Japan—revenue sharing arrangement. We hypothesize that management systems affect cooperative relationships and information network in a community; broadly termed as social capital. We quantified social capital using controlled economic experiments with fisherman subjects as well as surveys. Using wild cluster bootstrap for small sample inf...

  19. Inactivation of human norovirus in contaminated oysters and clams by high-hydrostatic pressure

    Science.gov (United States)

    Human norovirus (NoV) is the most frequent causative agent of foodborne disease associated with shellfish consumption. In this study, the effect of high-hydrostatic pressure (HHP) on inactivation of NoV was determined. Genogroup I.1 (GI.1) or Genogroup II.4 (GII.4) NoV were inoculated into oyster ho...

  20. Direct evidence for maternal inheritance of bacterial symbionts in small deep-sea clams (Bivalvia: Vesicomyidae)

    Science.gov (United States)

    Szafranski, Kamil M.; Gaudron, Sylvie M.; Duperron, Sébastien

    2014-05-01

    Bacterial symbiont transmission is a key step in the renewal of the symbiotic interaction at each host generation, and different modes of transmission can be distinguished. Vesicomyidae are chemosynthetic bivalves from reducing habitats that rely on symbiosis with sulfur-oxidizing bacteria, in which two studies suggesting vertical transmission of symbionts have been published, both limited by the imaging techniques used. Using fluorescence in situ hybridization and transmission electron microscopy, we demonstrate that bacterial symbionts of Isorropodon bigoti, a gonochoristic Vesicomyidae from the Guiness cold seep site, occur intracellularly within female gametes at all stages of gametogenesis from germ cells to mature oocytes and in early postlarval stage. Symbionts are completely absent from the male gonad and gametes. This study confirms the transovarial transmission of symbionts in Vesicomyidae and extends it to the smaller species for which no data were previously available.

  1. Uranium in the Near-shore Aquatic Food Chain: Studies on Periphyton and Asian Clams

    Energy Technology Data Exchange (ETDEWEB)

    Bunn, Amoret L.; Miley, Terri B.; Eslinger, Paul W.; Brandt, Charles A.; Napier, Bruce A.

    2007-12-31

    The benthic aquatic organisms in the near-shore environment of the Columbia River are the first biological receptors that can be exposed to groundwater contaminants coming from the U.S. Department of Energy's Hanford Site. The primary contaminant of concern in the former nuclear fuels processing area at the Site, known as the 300 Area, is uranium. Currently, there are no national clean up criteria for uranium and ecological receptors. This report summarizes efforts to characterize biological uptake of uranium in the food chain of the benthic aquatic organisms and provide information to be used in future assessments of uranium and the ecosystem.

  2. Sulfide oxidizing activity as a survival strategy in mangrove clam Polymesoda erosa (Solander, 1786)

    Digital Repository Service at National Institute of Oceanography (India)

    Clemente, S.; Ingole, B.S.; Sumati, M.; Goltekar, R.

    strategies of sulfide detoxification appear to be common in animals in normoxia. First, sulfide can be bound to blood proteins (Bagarinao and Vetter 1992). Second, sulfide is frequently oxidized to less toxic or nontoxic sulfur compounds, either... with the help of bacterial symbionts (Wilmot and Vetter 1990) or in the animal tissue (Vetter et al. 1987). As a group, thiotrophic (sulfide-utilizing) bacteria employ various enzymatic pathways for conversion of sulfide into energy, including the oxidation...

  3. Recruitment of mud clam Polymesoda erosa (Solander, 1876) in a mangrove habitat of Chorao Island, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Clemente, S.; Ingole, B.S.

    and biological constraints is substantially reduced, whereas, at high-tide level, increased desiccation may account for the mortality of settlers. It is speculated that initially the settlers settle according to the hydrodynamic conditions for sedimentation...

  4. Population characteristics of the mangrove clam Polymesoda (geloina) erosa (solander, 1786) in the Chorao mangrove, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Naik, S.; Furtado, R.; Ansari, Z.A.; Chatterji, A.

    Mangroves are the tropical and sub tropical coastal and/or estuarine intertidal or island plant communities. Since the early history of mankind, mangrove ecosystems have played important role in the socio-economic development of coastal people...

  5. Uranium in the Near-shore Aquatic Food Chain: Studies on Periphyton and Asian Clams

    International Nuclear Information System (INIS)

    The benthic aquatic organisms in the near-shore environment of the Columbia River are the first biological receptors that can be exposed to groundwater contaminants coming from the U.S. Department of Energy's Hanford Site. The primary contaminant of concern in the former nuclear fuels processing area at the Site, known as the 300 Area, is uranium. Currently, there are no national clean up criteria for uranium and ecological receptors. This report summarizes efforts to characterize biological uptake of uranium in the food chain of the benthic aquatic organisms and provide information to be used in future assessments of uranium and the ecosystem.

  6. Depuration and anatomical distribution of domoic acid in the surf clam Mesodesma donacium.

    Science.gov (United States)

    Álvarez, Gonzalo; Uribe, Eduardo; Regueiro, Jorge; Martin, Helena; Gajardo, Teresa; Jara, Lorena; Blanco, Juan

    2015-08-01

    In northern Chile, domoic acid (DA) has been detected in several bivalve species. In Mesodesma donacium, one of the most important commercial species for local fishermen, no information is available on depuration, or on the anatomical distribution of this toxin and its potential use as a palliative measure to minimize the consequences of ASP outbreaks. Deputation of DA is very fast in M. donacium, and can be adequately described by means of a two-compartment model. The estimated rates for the first and second compartments were 1.27 d(-1) and 0.24 d(-1), respectively, with a transfer rate between compartments of 0.75. Having high depuration rates protects this species from being affected by Pseudo-nitzschia blooms for an extended period of time. Taking this into account, the time in which the bivalves are unsafe for consumers is very short, and therefore the economic losses that could result by the DA outbreaks in local fisheries should be moderate. In relation to anatomical distribution, at least during the uptake phase, the toxin was evenly distributed within the soft tissues, with a total toxin burden corresponding to 27%, 32% and 41% for Digestive Gland (DG), Foot (FT) and Other Body Fractions (OBF), respectively. Since the contribution of each organ to the toxin concentration is a function of both weight contribution and toxin burden, the pattern of toxin distribution showed the following trend: "all other body fractions" (OBF) > Foot (FT) > Digestive Gland (DG). Thus, the highest concentration of DA, with a contribution close to 72%, corresponds to the edible tissues (OBF + FT), while the DG (non-edible tissue) only contributes the remaining 28%. Consequently, in view of the anatomical distribution of domoic acid in M. donacium, the elimination of the digestive gland does not substantially reduce the toxicity of the final product and therefore selective evisceration would not improve their quality for human consumption. PMID:26003793

  7. Overfishing population characteristics of razor clam, Ensis macha, from Independencia Bay, Peru, in 2004 year

    OpenAIRE

    Juan Tarazona; Jürgen Laudien

    2011-01-01

    Quantitative monthly samplings, in 2004, were carried out to estimate the density and biomass of Ensis macha (Molina 1782), from Morro Quemado area, Bay Independence, Pisco. The present study analyzes biometric relationships, growth parameters and somatic production using the ELEFAN I routine and the Crisp’s method. During the year 2004 the rate of exploitation (E= 0.69 y-1) was significantly bigger than the values of 2003 and the monthly landings (maximum of 335 t) and fishing effort (maximu...

  8. Infection of clams by Perkinsus olseni as an example of the new French Surveillance Programme

    OpenAIRE

    Miossec, Laurence; Garcia, Celine; ARZUL, Isabelle; Francois, Cyrille; Joly, Jean-pierre; Chollet, Bruno; Robert, Maeva; De Blas, Isabelle

    2006-01-01

    The French network for the surveillance and monitoring of mollusc health (REPAMO) was officially set up in 1992 to control the shellfish status along the French coasts according to the European directives 91/67/EEC and 95/70/EC. The objectives are 1) the surveillance of notifiable diseases present in France (Bonamiosis and Marteiliosis of flat oysters Ostrea edulis), 2) the surveillance of health status of cultured and wild populations of molluscs, 3) the study of abnormal mortality and 4) th...

  9. Coase and the Clams: Constructing Markets for Property Rights in Fisheries

    OpenAIRE

    Brandt, Sylvia J

    2001-01-01

    This dissertation addresses the impact of environmental regulation on resource-based industries by analyzing firms' responses to current environmental policies and to predicted changes in the regulatory regime. This research presents a theoretical motivation for and empirical estimates of changes in productivity, industrial organization, and strategic behavior due to the transition from firm-level regulation of inputs and outputs ("command and control") to tradable property rights (or "indivi...

  10. Diarrhetic shellfish poisoning toxin esters in Danish blue mussels and surf clams

    DEFF Research Database (Denmark)

    Jørgensen, Kevin; Scanlon, Sine Hedegaard; Jensen, L.B.

    2005-01-01

    Until recently, little focus was given to the presence of diarrhetic shellfish poisoning ( DSP) toxin esters in seafood products. However, during the last few years, the occurrence of a high percentage of esters of the total amount of DSP toxins present in some seafood products has been observed...

  11. Sandeels and clams (Spisula sp.) in the wind turbine park at Horns Reef. Preliminary report

    International Nuclear Information System (INIS)

    Sandeels were found in the sediment at all of the sample locations in the area of the wind turbine park and in the control area. The mean density of sandeels in the sediment was 0.0102 m-2 (10,200 km-2) in the control area and 0.0096 m-2 (9,600 km-2) in the impact area. The most abundant species of sandeel in both the impact and the control area was H. lanceolatus followed by A. marinus and A. tobianus. No G. semisquamatus was caught during the surveys. The construction of the wind turbine park is not supposed to effect the sandeel population in the Horns Reef area because the impact area seems to constitute a small fraction of a larger area with sandeel habitat. However, within the area of the wind turbine park sandeel abundance might be affected if the surface sediment changes due to the construction of the wind turbine park or if the abundance of sandeel predators increases in the impact area after the wind turbine park has been build (the so called artificial reef effect). To investigate if these effects will occur the field programmethat was carried out in February/march 2002 (the subject of this report) will have to be repeated after the wind turbine park has been constructed. (au)

  12. First pioneering laboratory experiments on filtration, respiration and growth of the razor clam (Ensis directus, Conrad)

    NARCIS (Netherlands)

    Kamermans, P.; Brummelhuis, E.B.M.; Wijsman, J.W.M.

    2011-01-01

    In Dutch marine circumstances, sand extraction releases silt into the water column. The extra silt can reduce light penetration into the water and consequently algal growth. To predict potential effects of an expansion of sand extraction activities it is necessary to know possible impacts on the env

  13. Of "Chicharrones" and Clam Chowder: Gender and Consumption in Jorge Ulica's Cronicas Diabolicas

    Science.gov (United States)

    Barrera, Magdalena

    2009-01-01

    This essay examines the working-class Mexican experience as represented in Jorge Ulica's "Cronicas Diabolicas," which he published between 1916 and 1926. What unites the wide-ranging subject matter of the chronicles is the author's resolute interest in maintaining his working-class compatriots' cultural and ideological ties to Mexico. Ulica…

  14. Sandeels and clams (Spisula sp.) in the wind turbine park at Horns Reef. Preliminary report

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Henrik; Sand Kristensen, P.; Hoffmann, E.

    2003-04-15

    Sandeels were found in the sediment at all of the sample locations in the area of the wind turbine park and in the control area. The mean density of sandeels in the sediment was 0.0102 m{sup -2} (10,200 km{sup -2}) in the control area and 0.0096 m{sup -2} (9,600 km{sup -2}) in the impact area. The most abundant species of sandeel in both the impact and the control area was H. lanceolatus followed by A. marinus and A. tobianus. No G. semisquamatus was caught during the surveys. The construction of the wind turbine park is not supposed to effect the sandeel population in the Horns Reef area because the impact area seems to constitute a small fraction of a larger area with sandeel habitat. However, within the area of the wind turbine park sandeel abundance might be affected if the surface sediment changes due to the construction of the wind turbine park or if the abundance of sandeel predators increases in the impact area after the wind turbine park has been build (the so called artificial reef effect). To investigate if these effects will occur the field programmethat was carried out in February/march 2002 (the subject of this report) will have to be repeated after the wind turbine park has been constructed. (au)

  15. Effects of Upper-Limit Water Temperatures on the Dispersal of the Asian Clam Corbicula fluminea

    OpenAIRE

    Inês Correia Rosa; Joana Luísa Pereira; Raquel Costa; Fernando Gonçalves; Robert Prezant

    2012-01-01

    Temperature is a determinant environmental variable in metabolic rates of organisms ultimately influencing important physiological and behavioural features. Stressful conditions such as increasing temperature, particularly within high ranges occurring in the summer, have been suggested to induce flotation behaviour in Corbicula fluminea which may be important in dispersal of this invasive species. However, there has been no experimental evidence supporting this hypothesis. It was already prov...

  16. Biochemical changes during larval development in the short neck clam, Paphia malabarica Chemnitz

    Digital Repository Service at National Institute of Oceanography (India)

    Gireesh, R.; Biju, A.; Muthiah, P.

    with seawater to remove excess salt and frozen at C020 1C until analysed for bio- chemical composition. Each sample for chemical analysis contains 10^15 C2 10 4 eggs or 15^20 C2 10 3 D-shaped larvae. Pre-metamorphic larvae (shell length 171.0 C6 0.2 mm) from... the pedivelgers under a microscope. Samples of pediveliger and juveniles were washed with 1% ammonium formate solution, quanti¢ed and frozen at C020 1C until analysed. Each sample for chemical analysis contains 3^5 C2 10 3 pre-meta- morphic larvae or 1^2 C2 10 3...

  17. The relationship between shellbed type and sequence architecture: examples from Japan and New Zealand

    Science.gov (United States)

    Kondo, Yasuo; Abbott, Stephen T.; Kitamura, Akihisa; Kamp, Peter J. J.; Naish, Tim R.; Kamataki, Takanobu; Saul, Gordon S.

    1998-12-01

    Examples of lithology, fossil content and taphonomic features of shellbeds and intervening less fossiliferous intervals are presented from four Plio-Pleistocene successions (Shimosa Group, Boso Peninsula, Omma Formation, Hokuriku area, Japan, and Okehu, Kai-iwi, and Shakespeare groups in Wanganui, and the Rangitikei Group along the Rangitikei River in New Zealand). As for pre-Pliocene 3rd- and 4th-order depositional sequences, Plio-Pleistocene 5th- to 7th-order depositional sequences contain a variety of shellbeds which are often associated with surfaces or intervals that are characterized by sedimentary condensation, omission or erosion (e.g. sequence boundaries, ravinement surfaces, downlap surfaces and condensed sections). Stratigraphic patterns of shellbed type tend to be similar and repetitive within a basin and a locality. This demonstrates that a specific palaeogeography played an important role in determining the nature of shellbeds. For example, shellbeds formed in the context of toplap are common only in the Shimosa Group, which was deposited in a moderately sheltered sea, the palaeo-Tokyo Bay. Toplap shellbeds are rare in other sequences formed in more open conditions. Despite the variability resulting from such basin characteristics, common styles of shellbeds can be recognized that formed under conditions of marine onlap, backlap, downlap and toplap. Each type of shellbed has a characteristic fossil composition and taphonomy. Onlap and toplap shellbeds contain low-diversity macrobenthic associations including Glycymeris, Mercenaria, Paphies or other bivalves having robust shells, which are often abraded or fragmented. Backlap shellbeds, which are equivalent to the condensed section formed at the maximum transgression, are characterized by dominance of epifaunal macrobenthos such as bryozoa, brachiopoda, pectinid and ostreid bivalves, preserved in a slightly cemented, glauconitic muddy matrix. In contrast to fossils in such condensed sections, the shell

  18. Laboratory experiment, the number of clams consumed by the fish of FLORIDA POMPANO in experimental tanks feeding on coquina clams individually and in groups from 2013-11-26 to 2013-12-03 (NCEI Accession 0127553)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset includes the results from a laboratory experiment assessing whether juvenile Florida Pompano (Trachinotus carolinus) foraging success is greater when...

  19. Ultrastructural description of the spore maturation stages of the clam parasite Minchinia tapetis (Vilela, 1951) (Haplosporida: Haplosporidiidae).

    Science.gov (United States)

    Azevedo, C

    2001-07-01

    The fine structure of maturing spores of a haplosporidian parasite found in the gill, mantle and foot tissues of Ruditapes decussatus L. (Mollusca, Bivalvia), a species of commercial importance in Portugal, is described. When observed free in suspension, immature spores exhibit one or two epispore cytoplasmic extensions (ECE) which constitute a projection of a portion of the exosporoplasm, sometimes without ultrastructural organisation, surrounded by the plasmalemma. Free spores observed by light microscopy (LM) after 3-5 days of incubation in filtered sea-water exhibit no ECE attached to the spore wall. The mature spore is ovoid to ellipsoid, operculate, uninucleate and measures c. 4.8 microm long and c. 3.9 microm wide. The spore shape and size and the identity of the host living in the same geographical region suggest that this species is the same as previously described using LM observations as Haplosporidium tapetis Vilela, 1951 and later transferred to Minchinia Labbé, 1896. PMID:11466479

  20. Bio-accumulation of some trace metals in the short-neck clam Paphia malabarica from Mandovi estuary, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    KrishnaKumari, L.; Kaisary, S.; Rodrigues, V.

    . Concentration factor was determined as a ratio of mean metal content (dissolved) in water (Ag/l) and that in the soft tissue (Ag/kg wet weight). All the analyses were carried out in duplicate, and the average values are reported in this paper. 3. Results... to 10 ml with acidified double-distilled water and later analysed by flame atomic absorption spectrophotometry (AAS). Mean ratio (wet to dry weight) was used for converting metal content to ppm wet weight. Samples prepared for metal analyses included...

  1. Effects of anthracene on filtration rates, antioxidant defense system, and redox proteomics in the Mediterranean clam Ruditapes decussatus (Mollusca: Bivalvia).

    Science.gov (United States)

    Sellami, Badreddine; Khazri, Abdelhafidh; Louati, Héla; Dellali, Mohamed; Driss, Mouhamed Ridha; Aïssa, Patricia; Mahmoudi, Ezzeddine; Hamouda, Beyrem; Coelho, Ana Varela; Sheehan, David

    2015-07-01

    This study aimed at analyzing the impact of a toxic polyaromatic hydrocarbon (PAH), anthracene (ANT), on Ruditapes decussatus collected from a Tunisian coastal lagoon (Bizerte Lagoon). Filtration rates, several antioxidant enzymes--superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione transferase (GST)--as well as indices of protein oxidation status were determined in various tissues of this bivalve. Specimens were exposed to 100 μg/L of ANT for 2 days. ANT levels were evaluated using HPLC and were detected in the gill and digestive gland at different amounts. ANT exposure altered the behavior of bivalves by changing the siphon movement and decreasing filtration rate significantly. The enzymatic results indicated that ANT exposure affected the oxidative stress status of the gills of R. decussatus. In addition, modification of proteins was detected in the gills using redox proteomics after ANT treatment. Three protein spots were successfully identified by matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF-MS). These proteins can be roughly related to muscle contraction function. In contrast, no significant modification of enzymatic and protein responses was detected in the digestive gland after ANT treatment. These data demonstrate that combined behavioral and biochemical analyses are a powerful tool to provide valuable insights into possible mechanisms of toxicity of anthracene in R. decussatus. Additionally, the results highlight the potential of the gill as a valuable candidate for investigating PAH toxicity. PMID:25779113

  2. THE PHYLOGENETIC RELATIONSHIPS OF WHALE-FALL VESICOMYID CLAMS BASED ON MITOCHONDRIAL COI DNA SEQUENCES. (U915626)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  3. Use of centrifuged and preserved microalgae for feeding juvenile Manila clam (Tapes philippinarum): effects on growth and fatty acid composition

    OpenAIRE

    Pier Paolo Gatta; Attilio Luigi Mordenti; Giovanni Corso; Silvia Testi; Anna Badiani; Alessio Bonaldo

    2010-01-01

    The objective of the present study was to assess the nutritional value of three diets containing commercial preserved  microalgae pastes and the relationship of their biochemical composition to the growth rate and fatty acids profile of juve-  nile Tapes philippinarum.  The feeding period was 6 weeks. At a daily ratio of 1% dry weight live weight of the clams–1, the trispecific diet with 40%  of I. galbana, 20% of T. suecicaand 40% of C. muelleri supported greater gr...

  4. Assimilation of terrigenous organic matter via bacterial biomass as a food source for a brackish clam, Corbicula japonica (Mollusca: Bivalva)

    Science.gov (United States)

    Yamanaka, Toshiro; Mizota, Chitoshi; Maki, Yonosuke; Matsumasa, Masatoshi

    2013-07-01

    Corbicula japonica collected from the Kitakami River estuary, northeastern Japan, showed lower δ34S values in soft-body parts (+1.7 to +11.0‰) than the ambient seawater sulfate sulfur (+21‰), and this value gradually decreased at successive sites up to 15.8 km upstream from the river mouth. Previous study using carbon and nitrogen isotopes suggests that the bivalve nonselectively assimilates particulate organic matter of marine and terrestrial origin by filter feeding. This pattern in δ34S values may indicate a considerable contribution of a food source derived from terrigenous organic matter, which has low δ34S values close to 0‰, and the bivalve has been reported to have cellulase and hemicellulase activities. Unique fatty acids (iso 17:0 and anteiso 17:0 acids), both characteristic of sulfate-reducing bacteria, were observed in the salt-free, soft-body parts of the bivalve. The concentration of monounsaturated fatty acids, possibly derived from bacteria, was also high. Trace amounts of a polyunsaturated fatty acid (20:5ω3) specific to dinoflagellates were detected. In Corbicula habitats, reductive sandy layers with ample sulfides that were sporadically intercalated into the oxidative sandy sediment were often observed. The stable isotopic signatures of sediment sulfides (acid-volatile sulfide) and associated pore-water sulfates were -8.9 to +8.6‰ and +22.4 to +26.3‰, respectively, indicating the existence of bacterial sulfate-reducing activity and thiobios biomass. These isotopic signatures of the sediment, with the fatty acid composition of the bivalve, confirm the importance of a food source derived from bacteria belonging to the thiobios in the substrate sediments via pedal feeding, rather than direct digestion of terrigenous organic matter, in this estuarine ecosystem.

  5. Interannual climate variability in the Miocene: high resolution trace element and stable isotope ratios in giant clams

    NARCIS (Netherlands)

    Batenburg, S.J.; Reichart, G.-J.; Jilbert, T.; Janse, Max; Wesselingh, F.P.; Renema, Willem

    2011-01-01

    High resolution stable isotope and trace elemental ratios of a recent Tridacna squamosa from Vietnam and a Middle to Late Miocene (10–13 Ma) Tridacna gigas from Indonesia are presented. The seasonal pattern of modern sea surface temperature (SST) variability offshore Vietnam is faithfully recorded i

  6. Free amino acids in the clam Macoma balthica (L.) (Bivalvia, Mollusca) from brackish waters of southern Baltic Sea

    NARCIS (Netherlands)

    Sokolowski, A.; Wolowicz, M.; Hummel, H.

    2003-01-01

    Fourteen acidic and neutral free amino acids (FAA) were investigated in soft tissue of Macoma balthica from different depth zones of the Gulf of Gdansk (Baltic Sea) over a full seasonal cycle. The dry weight of the bivalves and physico-chemical parameters of overlying bottom water and surface sedime

  7. Butyltin accumulation in the marine clam Mya arenaria: an evaluation of its suitability for monitoring butyltin pollution.

    Science.gov (United States)

    Yang, Rui-qiang; Zhou, Qun-fang; Jiang, Gui-bin

    2006-03-01

    The use of Mya arenaria as a new sensitive biomonitor of butyltins pollution in the oceanic system was investigated. Field survey indicated that much higher levels of butyltin compounds were found in M. arenaria compared with the other species investigated. Using Mytilus edulis as a control organism, a 28 days exposure of tributyltin chloride (TBT) to M. arenaria for accumulation and subsequent 28 days breeding in clean seawater for elimination were conducted under laboratory conditions in order to confirm its high accumulation ability and characterize its kinetic behavior to TBT. Bioconcentration factor (BCF) of M. arenaria ranged from 15,538 to 91,800 after 28 days exposure. The rapid uptake and low rate to eliminate TBT of M. arenaria displayed first-order kinetics. M. arenaria shows potential as a new bioindicator to monitor TBT pollution in marine environment. PMID:16188291

  8. A real-time biomonitoring system to detect arsenic toxicity by valve movement in freshwater clam Corbicula fluminea.

    Science.gov (United States)

    Chen, Wei-Yu; Jou, Li-John; Chen, Suz-Hsin; Liao, Chung-Min

    2012-05-01

    Arsenic (As) is the element of greatest ecotoxicological concern in aquatic environments. Effective monitoring and diagnosis of As pollution via a biological early warning system is a great challenge for As-affected regions. The purpose of this study was to synthesize water chemistry-based bioavailability and valve daily rhythm in Corbicula fluminea to design a biomonitoring system for detecting waterborne As. We integrated valve daily rhythm dynamic patterns and water chemistry-based Hill dose-response model to build into a programmatic mechanism of inductance-based valvometry technique for providing a rapid and cost-effective dynamic detection system. A LabVIEW graphic control program in a personal computer was employed to demonstrate completely the functional presentation of the present dynamic system. We verified the simulated dissolved As concentrations based on the valve daily rhythm behavior with published experimental data. Generally, the performance of this proposed biomonitoring system demonstrates fairly good applicability to detect waterborne As concentrations when the field As concentrations are less than 1 mg L(-1). We also revealed that the detection times were dependent on As exposure concentrations. This biomonitoring system could particularly provide real-time transmitted information on the waterborne As activity under various aquatic environments. This parsimonious C. fluminea valve rhythm behavior-based real-time biomonitoring system presents a valuable effort to promote the automated biomonitoring and offers early warnings on potential ecotoxicological risks in regions with elevated As exposure concentrations. PMID:22359017

  9. Vanishing clams on an Iberian beach: local consequences and global implications of accelerating loss of shells to tourism.

    Science.gov (United States)

    Kowalewski, Michał; Domènech, Rosa; Martinell, Jordi

    2014-01-01

    Multi-decadal increase in shell removal by tourists, a process that may accelerate degradation of natural habitats, was quantified via two series of monthly surveys, conducted thirty years apart (1978-1981 and 2008-2010) in one small embayment on the Mediterranean coast of the Iberian Peninsula. Over the last three decades, the local tourist arrivals have increased almost three-fold (2.74), while the area has remained unaffected by urban encroachment and commercial fisheries. During the same time interval the abundance of mollusk shells along the shoreline decreased by a comparable factor (2.62) and was significantly and negatively correlated with tourist arrivals (r = -0.52). The strength of the correlation increased when data were restricted to months with high tourist arrivals (r = -0.72). In contrast, the maximum monthly wave energy (an indirect proxy for changes in rate of onshore shell transport) was not significantly correlated with shell abundance (r = 0.10). Similarly, rank dominance of common species, drilling predation intensity, and body size-frequency distribution patterns have all remained stable over recent decades. A four-fold increase in global tourist arrivals over the last 30 years may have induced a comparable worldwide acceleration in shell removal from marine shorelines, resulting in multiple, currently unquantifiable, habitat changes such as increased beach erosion, changes in calcium carbonate recycling, and declines in diversity and abundance of organisms, which are dependent on shell availability. PMID:24421895

  10. Aquaculture as a use of the Coastal Zone: Environmental and Economic Aspects, Giant Clam Farming as a Development

    OpenAIRE

    Tisdell, Clem

    1989-01-01

    There is increasing competition for the use of the coastal zone as economic development proceeds. This has resulted in the recent release of a Green Paper by the Queensland Premier's Department on coastal zone management. Economic development and conservation appear rarely, if ever, to be completely compatible, and the use of the coastal area for the development of aquaculture can have some adverse environmental effects. In Australia, aquaculture is relatively underdeveloped and the McKinnon ...

  11. The potential impact of sea otters (Enhydra lutris) on the British Columbia geoduck clam (Panopea abrupta) fishery

    OpenAIRE

    Reidy, Rhonda Darlene

    2011-01-01

    I used fishery-independent survey data and catch curve analysis to assess the potential predation effects of sea otters on the British Columbia geoduck fishery on the west coast of Vancouver Island, by estimating geoduck total mortality rates across a gradient of sea otter abundance. Linear regression provided strong evidence of a fishing effort effect on geoduck total mortality while the main effect of otters was not significant. Harvesters, however, have increasingly reported seeing sea ott...

  12. Baseline of organotin pollution in fishes, clams, shrimps, squids and crabs collected from the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Jadhav, S.; Bhosale, D.; Bhosle, N.B.

    , crustaceans and molluscans are easily prone to organotins contamination. In view of this, a baseline monitoring study was conducted in order to establish the levels of organotins in edible marine fishes, bivalves, shrimps, squids and crabs collected from...

  13. Vanishing clams on an Iberian beach: local consequences and global implications of accelerating loss of shells to tourism.

    Directory of Open Access Journals (Sweden)

    Michał Kowalewski

    Full Text Available Multi-decadal increase in shell removal by tourists, a process that may accelerate degradation of natural habitats, was quantified via two series of monthly surveys, conducted thirty years apart (1978-1981 and 2008-2010 in one small embayment on the Mediterranean coast of the Iberian Peninsula. Over the last three decades, the local tourist arrivals have increased almost three-fold (2.74, while the area has remained unaffected by urban encroachment and commercial fisheries. During the same time interval the abundance of mollusk shells along the shoreline decreased by a comparable factor (2.62 and was significantly and negatively correlated with tourist arrivals (r = -0.52. The strength of the correlation increased when data were restricted to months with high tourist arrivals (r = -0.72. In contrast, the maximum monthly wave energy (an indirect proxy for changes in rate of onshore shell transport was not significantly correlated with shell abundance (r = 0.10. Similarly, rank dominance of common species, drilling predation intensity, and body size-frequency distribution patterns have all remained stable over recent decades. A four-fold increase in global tourist arrivals over the last 30 years may have induced a comparable worldwide acceleration in shell removal from marine shorelines, resulting in multiple, currently unquantifiable, habitat changes such as increased beach erosion, changes in calcium carbonate recycling, and declines in diversity and abundance of organisms, which are dependent on shell availability.

  14. Vanishing Clams on an Iberian Beach: Local Consequences and Global Implications of Accelerating Loss of Shells to Tourism

    Science.gov (United States)

    Kowalewski, Michał; Domènech, Rosa; Martinell, Jordi

    2014-01-01

    Multi-decadal increase in shell removal by tourists, a process that may accelerate degradation of natural habitats, was quantified via two series of monthly surveys, conducted thirty years apart (1978–1981 and 2008–2010) in one small embayment on the Mediterranean coast of the Iberian Peninsula. Over the last three decades, the local tourist arrivals have increased almost three-fold (2.74), while the area has remained unaffected by urban encroachment and commercial fisheries. During the same time interval the abundance of mollusk shells along the shoreline decreased by a comparable factor (2.62) and was significantly and negatively correlated with tourist arrivals (r = −0.52). The strength of the correlation increased when data were restricted to months with high tourist arrivals (r = −0.72). In contrast, the maximum monthly wave energy (an indirect proxy for changes in rate of onshore shell transport) was not significantly correlated with shell abundance (r = 0.10). Similarly, rank dominance of common species, drilling predation intensity, and body size-frequency distribution patterns have all remained stable over recent decades. A four-fold increase in global tourist arrivals over the last 30 years may have induced a comparable worldwide acceleration in shell removal from marine shorelines, resulting in multiple, currently unquantifiable, habitat changes such as increased beach erosion, changes in calcium carbonate recycling, and declines in diversity and abundance of organisms, which are dependent on shell availability. PMID:24421895

  15. Developing simple tools for transferring the biology to the management in small scale fisheries: the case of a sword razor clam fishery in Galicia

    Directory of Open Access Journals (Sweden)

    Alba Hernández Otero

    2014-06-01

    Fig. 2. Management procedure proposed. Dark grey polygons indicate the stakeholders involved in shellfishing. Light grey polygons and white boxes show the recommended management actions. Fig. 3 von Bertalanffy growth curves fitted for E. magnus using growth marks revealed in the acetate peels.

  16. Distribution of butyltins (TBT, DBT, MBT) in sediments of Gulf of Cadiz (Spain) and its bioaccumulation in the clam Ruditapes philippinarum

    Digital Repository Service at National Institute of Oceanography (India)

    Garg, A.; Anton-Martin, R.; Garcia-Luque, E.; Riba, I.; DelValls, T.A.

    in the environment. It is well known that sediments can adsorb persistent and toxic chemicals at concentrations much higher than in the water column. Butyltin compounds belong to the group of organotins, which are compounds containing at least one bond between tin... malformation at very low concentrations (Lee et al. 2006; Blanca 2008). There are no detailed studies on the effects of TBT on humans as yet (Bortoli et al. 2003) though TBT has been detected in human blood (Kannan et al. 1995) and marine food has been...

  17. Effect of permethrin, anthracene and mixture exposure on shell components, enzymatic activities and proteins status in the Mediterranean clam Venerupis decussata.

    Science.gov (United States)

    Sellami, Badreddine; Khazri, Abdelhafidh; Mezni, Amine; Louati, Héla; Dellali, Mohamed; Aissa, Patricia; Mahmoudi, Ezzeddine; Beyrem, Hamouda; Sheehan, David

    2015-01-01

    Anthracene (ANT) and permethrin (PER) are two of the more toxic compounds reaching the marine environment. This study aimed to determine the impact of these molecules on Venerupis decussata, an economically important species cultured on the Tunisian coast. Shell structure and its possible transformation upon exposure to the two contaminants were studied by X-ray diffraction and gravimetric analyses. Results revealed a phase transition in shell composition from aragonite to calcite after PER exposure, to a mixture of PER and ANT (Mix) but not for ANT alone. Catalase (CAT), superoxide dismutase (SOD) and glutathione transferase (GST) activities were determined in digestive gland and gills after exposure to ANT, PER and Mix to assess the impact of the contamination on the oxidative status of V. decussata. Enzyme activities increased in the digestive gland after PER treatment and in the gills after ANT treatment. PER exposure significantly reduced the levels of free thiols and increased levels of carbonylated proteins in the digestive gland, as compared to controls. In contrast, ANT exposure significantly reduced free thiols and increased the number of carbonylated proteins in the gills. Mix induced additive effects as measured by both enzymatic and proteomic approaches. The present study suggests that PER has a strong effect on shell structure; that PER and ANT exposure generate compound-dependent oxidative stress in the tissues of V. decussata and that a mixture of the two compounds has synergistic effects on biochemical response. PMID:25461742

  18. 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.

  19. First European record of the invasive brackish water clam Rangia cuneata (G.B. Sowerby I, 1831) (Mollusca: Bivalvia)

    OpenAIRE

    Verween, A; Kerckhof, F; Vincx, M.; Degraer, S.

    2006-01-01

    A population of Rangia cuneata (G.B. Sowerby I, 1831), an estuarine bivalve, has been recorded in the harbour of Antwerp, Belgium. This species is new to the European brackish water fauna. After initially finding only a few small individuals in August 2005, R. cuneata was encountered frequently in the pipes of the cooling water system of an industrial plant from February 2006 onwards. Before this present record, R. cuneata was only known from the Gulf of Mexico and the Atlantic coast of North...

  20. Recent trends in the prevalence of neoplasia in the Baltic clam Macoma balthica (L. from the Gulf of Gdañsk (Baltic Sea

    Directory of Open Access Journals (Sweden)

    Catherine Thiriot-Quiévreux

    2005-03-01

    Full Text Available This study discusses the occurrence of neoplasia in the Balticclam Macoma balthica from the Gulf of Gdańsk in recent yearsand investigates potential relationships between toxic compoundsin the environment and the presence of the cancer. The diseasewas identified at four sampling stations during 1999-2002. Comparison withprevious results highlighted the substantialprevalence of the tumour between 1998 and 2002. The prevalenceof the cancer was strongly dependent on the sampling location(p > 0.001: it was highest at sampling point H45 (the deepestpart of the gulf and lowest at station PB30 (central part ofthe gulf. Monthly studies showed a trend towards an increasingprevalence of neoplasia during the warm months. However, overseveral sampling months no strong statistical correlation betweenthe prevalence of the disease and the sampling time was found.The results of the study suggest that several environmental factorsmay promote the progress of the cancer in M. balthica from the Gulf of Gdańsk: it is most probably an indirecteffect of pollution, although causality cannot be proven at thisstage. Seriously polluted and exhibiting a considerable asymmetryof contamination, the ecosystem of the gulf provides an idealenvironment for testing potential cause-effect relationshipsbetween pollutants and their biological effects.

  1. Influence of rainfall on E. coli concentrations in clams: results of collaboration between competent health authority and producers’ association in the province of Fermo (Italy

    Directory of Open Access Journals (Sweden)

    Valentina Gentili

    2014-02-01

    Full Text Available The Area Vasta di Fermo (the competent health authority of the Marche Region, in collaboration with the local producers’ Association conducted a series of studies on the presence of E. coli as an indicator of faecal contamination in the environment, in shellfish and in fishery waters, and on the factors that can affect their presence. These studies, carried out from 2008 to 2011, included an assessment of the currents along the coast, of the precipitations, and data from the monitoring of E. coli on shellfish harvested in the collection areas were examined. The results showed that in most cases, small concentrations of microorganisms in shellfish corresponded to little or no precipitations, while an increase in the levels of E. coli was preceded by more or less abundant rainfalls. The conclusions suggest that it is advisable to carry out a more detailed risk analysis which should take into account the above-mentioned factors. Furthermore, monitoring alone based on the determination of indicator organisms, especially when carried out as a single analysis or with a small number of E. coli determinations, does not provide a satisfactory indication of safety. The regional surveillance plans should be applied timely and rigorously, together with onsite investigations aimed at identifying changes that can affect the presence of E. coli in shellfish. Food business operators themselves could implement good manufacturing practices to verify whether the microbiological parameters are within the prescribed limits after rainfalls, especially if heavy.

  2. EXPOSURE ASSESSMENT TO FOOD CONTAMINANTS ON EDIBLE FISH, CLAMS AND CRUSTACEANS IN A COASTAL ENVIRONMENT FACING A MINING AND INDUSTRIAL AREA IN SARDINIA (SULCIS-IGLESIENTE

    Directory of Open Access Journals (Sweden)

    P.L. Piras

    2011-08-01

    Full Text Available The risk assessment following exposure of the local population to the consumption of fishery products caught in the Boi Cerbus lagoon, located in country of Portoscuso (Sardinia, followed the phase of sampling, analysis and data-collection “site-specific”. Overall, the fishery products samples are part of the following zoological groups: fish (grey mullets, soles and gobies, bivalve (cockles and crustaceans (crabs. It was also agreed that further investigation were implemented in a targeted way, directing attention to critical issues that emerged from the first phase, represented by heavy metals such as Cadmium, Lead, Mercury and the (metalloid Arsenic that, for the purposes of food safety, are still contaminants with high concern for the potential impact on human health. For the risk analysis through food intake, three different procedures for exposure assessment were considered: the regulation by law, the assessment according to US-EPA approach and the assessment according to EU harmonized method. For a wider opportunity for exposure assessment through ingestion of food from contaminated areas, also for their risk management, a single approach to the risk analysis is not be considered sufficient.

  3. Pinnatoxin G is responsible for atypical toxicity in mussels (Mytilus galloprovincialis) and clams (Venerupis decussata) from Ingril, a French Mediterranean lagoon

    OpenAIRE

    Hess, Philipp; Abadie, Eric; Hervé, Fabienne; Berteaux, Tom; Séchet, Véronique; Aráoz, Romulo; Molgó, Jordi; Zakarian, Armen; Sibat, Manoëlla; Rundberget, Thomas; Miles, Christopher O.; Amzil, Zouher

    2013-01-01

    Following a review of official control data on shellfish in France, Ingril Lagoon had been identified as a site where positive mouse bioassays for lipophilic toxins had been repeatedly observed. These unexplained mouse bioassays, also called atypical toxicity, coincided with an absence of regulated toxins and rapid death times in mice observed in the assay. The present study describes pinnatoxin G as the main compound responsible for the toxicity observed using the mouse bioassay for lipo...

  4. Worldwide and Regional Laboratory Comparison on the Determination of Organochlorine Compounds, Polybrominated Diphenyl Ethers and Petroleum Hydrocarbons in IAEA-457 Clam (Gafrarium tumidum) Sample

    International Nuclear Information System (INIS)

    For nearly thirty years, the Marine Environmental Studies Laboratory (MESL) of the IAEA Environment Laboratories has conducted worldwide laboratory performance studies, also known as interlaboratory comparisons (ILCs). The results have been used to evaluate the participating laboratories' performance with respect to a wide range of organic and inorganic pollutants. This work has been conducted in collaboration with the Regional Seas Programme of the United Nations Environment Programme. The goal of the performance studies is to demonstrate the measurement capabilities of laboratories participating in ILCs and proficiency tests (PTs). The results of ILCs or PTs are of crucial interest to laboratories, as they provide clear information about the laboratories' measurement capabilities. Participation is voluntary or is undertaken to fulfil external requirements (e.g. legal, accreditation, control bodies). The ILC and PT schemes involve the comparison of participant results with an assigned value, usually delivered as a consensus value from the overall population of test results. These exercises are designed to monitor and demonstrate the performance and analytical capabilities of the participating laboratories, and to identify gaps and problem areas where further development is needed. Regular participation has benefits with regard to training and educational opportunities, enhanced mutual trust in results and methodology, and objective evidence for accreditation purposes. The present interlaboratory study was designed to evaluate the measurement performance of the participating laboratories on the analysis of organic contaminants in biota samples. The data reported by the laboratories, together with the technical and statistical evaluations of the results for each element, are included in this report

  5. Influence of mesh size and tooth spacing on the proportion of damaged organisms in the catches of the Portuguese clam dredge fishery

    OpenAIRE

    Gaspar, M. B.; Leitao, F.; Santos, M. N.; Sobral, M.; Chícharo, Luís; Chícharo, Alexandra; Monteiro, C. C.

    2002-01-01

    Experiments to assess the effect of mesh size and tooth spacing on the catch of Spisula solida were undertaken with the aim of determining an optimal combination of these two characteristics to minimize the dredging impact on by-catch species. However, our data showed that tooth spacing, mesh size and the interactions between these two factors did not affect the number of damaged macrofaunal individual’s caught. This may be because infauna entered the dredge without passing through the spa...

  6. Bio-accumulation of copper, zinc, iron and manganese in oyster Saccostrea cucullata, Snail Cerithium rubus and Clam Tellina angulata from the Bombay coast

    Digital Repository Service at National Institute of Oceanography (India)

    Krishnakumari, L.; Nair, V.R.; Moraes, C.

    accumulation was high in S. cucullata, manganese in C. rubus and iron in T. angulata. Similarly, copper and zinc in S. cucullata and copper in C. rubus were found occasionally higher than accepted health standards...

  7. = Study of the effects of contaminants in a sentinel species, the clam Ruditapes decussatus, through protein expression analysis: application to marine environment monitoring

    OpenAIRE

    Chora, Suze Chainho

    2009-01-01

    As regiões costeiras, que englobam alguns dos ecossistemas mais produtivos do meio marinho e que são vitais à manutenção do equilíbrio da região litoral, são também lugares preferenciais para a instalação de várias estruturas humanas, tais como portos, centros urbanos, indústrias e actividades agrícolas. Como consequência, numerosos e variados poluentes são libertados nestas áreas, infligindo vários impactos negativos. Estes poluentes, que podem existir em solução ou em suspensão na água ou a...

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

    International Nuclear Information System (INIS)

    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

  9. Progress Report No 1 to ACIAR Project No. 8823

    OpenAIRE

    Tisdell, Clem

    1990-01-01

    The main objectives of ACIAR Project No. 8823 are to provide information about (i) market prospects for giant clams, (ii) the production economics and supply factors involved in giant clam mariculture, (iii) marine property rights as these affect the economics of giant clam mariculture and (iv) the possible value of giant clam mariculture in development in less developed countries of the Indo-Pacific region especially South Pacific countries.

  10. 车螺肉酶解液中提取分离天然牛磺酸工艺%Extraction and Separation of Natural Taurine from Enzymatic Hydrolysis Water of Marine Clam Meat

    Institute of Scientific and Technical Information of China (English)

    粟桂娇; 阎欲晓; 覃洁; 黄艳萍; 聂桂锋

    2005-01-01

    以新鲜车螺肉为原料,采用酸性蛋白酶先酶解再水煮工艺提取天然牛磺酸.在料:水=1:3(W/V),酶解温度35℃,酶解pH2.5前提下,酸性蛋白酶最适的提取条件为加酶量E/S=2000U/g,酶解时间4h,水煮时间0.5h.用H+型强酸性阳离子交换树脂从酶解提取液中分离提纯牛磺酸,结果表明该工艺能有效地将牛磺酸与甘氨酸、赖氨酸等其他氨基酸分离.在25×400(mm)离子交换柱湿装柱量为120ml,洗脱速度1.5BV/h条件下,最适上柱量0.5mg氨基氮/ml湿树脂,在pH0.9~3.3范围内的洗脱液是牛磺酸流出的高流分部分.

  11. The impact of ocean acidification on the early life stages of surf clams and the interactive effects of feeding and temperature from laboratory experiment studies from 2011-07-12 to 2012-06-17 (NODC Accession 0123314)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains laboratory experiment data that were collected to examine the effects of ocean acidification on the Atlantic surfclam, Spisula...

  12. 水环境中 Cd和 Cu污染对监测生物河蚬积累效应的影响%Accumulation Effects of Biomonitoring Indicator Asian Clam (Corbicula fluminea) Under Different Cd and Cu Pollution Conditions

    Institute of Scientific and Technical Information of China (English)

    曾丽璇; 陈桂珠; 余日清; 卢杰

    2004-01-01

    以河蚬作为指示生物,采用室内培养方法,研究了不同浓度的 Cd和 Cu的单独及联合作用的毒性效应.结果显示,在水体中浓度为 10、 20、 30、 40、 50 μ g· L-1的 Cd与 Cu单独作用下,河蚬体内 Cd与 Cu的含量分别与其在该环境中的暴露时间和浓度呈显著正相关.在同样浓度的 Cd与 Cu共同存在的环境中,河蚬体内的 Cd与 Cu的含量仍与环境中该物质的浓度呈显著正相关,且随着暴露时间的延长均表现出对污染物质积累的增加.初步建议:河蚬可作为淡水中重金属污染的监测指示生物.

  13. Investigation on the Environment of Clam Breeding Area in Yunlong, Fuzhou%福州琅岐云龙贝类养殖区的环境现状调查

    Institute of Scientific and Technical Information of China (English)

    翁新

    2006-01-01

    2006年5~6月对福州市琅岐云龙贝类养殖区的环境现状进行调查,调查内容包括水质、沉积物、海洋浮游生物和养殖贝类,结果表明琅岐云龙贝类养殖区环境现状基本良好,部分水质轻度污染.

  14. 乐清湾泥蚶、缢蛏体内及养殖水环境细菌菌群的初步调查%Preliminary Investigation on Bacteria Colonies in Clams and Their Living Environment in Leging Bay

    Institute of Scientific and Technical Information of China (English)

    杨星星; 管嘉兴; 房文红; 郑国兴; 于业绍

    2003-01-01

    本文对浙江省乐清湾滩涂和池塘养殖的泥蚶和缢蛏体内及养殖环境细菌菌群组成进行了初步调查.2000年7月~2001年7月间分四个季度进行采样分析.细菌总数分析表明,蒲歧和翁样海水中细菌总数在103~105个/mL之间,蒲歧和翁样两地每次海水样品都是池塘细菌总数高于滩涂;无论哪个季节和采样点,在一年内泥蚶和缢蛏体内的细菌总数均高于水中的细菌总数,且缢蛏体内细菌总数高于泥蚶,翁样贝体内细菌总数几乎均高于蒲歧贝体内细菌总数.对贝体内细菌属组成分析表明,在不同季节,同一滩涂或池塘中泥蚶和缢蛏体内菌群的组成及优势菌属比较相近,蒲歧滩涂和池塘、翁样滩涂和池塘贝体内菌群的组成及优势菌属具有一定的相似性;贝体内细菌优势菌属具有明显的季节性变化,在夏季(2001年7月31 日),以弧菌属和气单胞菌属占优势,而在冬季则以莫拉氏菌属占优势.

  15. Toxicity Effects of Cd and Cu on the Respiration and Excretion Metabolism of Asian Clam%重金属镉和铜对河蚬呼吸和排泄的毒性研究

    Institute of Scientific and Technical Information of China (English)

    曾丽璇; 陈桂珠; 吴宏海

    2007-01-01

    采用代谢瓶人工培养方法,初步研究了未受污染情况下河蚬的呼吸和排泄过程中的重要指标耗氧率和排氨率.与受100、200、400 μg·L-1的重金属镉和铜的单独和联合污染情况下河蚬耗氧率和排氨率进行对照,结果显示随着3种不同处理方式重金属浓度的增大,河蚬的耗氧率、排氨率均有明显的下降.3种处理浓度中,除100 μg·L-1处理组外,200、400 μg·L-1的不同重金属处理方式均对河蚬的耗氧率、排氨率产生抑制.结果显示河蚬的呼吸和排泄过程中耗氧率和排氨率的变化可以作为河蚬重金属镉、铜污染的指示指标.

  16. Moluscos bivalvos y gasteropodos

    OpenAIRE

    Lasta, M.L.; Ciocco, N.F.; Bremec, C.; Roux, A.

    1998-01-01

    The main life history characteristics, ecology and fishing interest of bivalve and gastropod species from the Argentine Sea are described. Exploited bivalve species are: mussel Mytilus edulis platensis, cholga Aulacomya ater, tehuelche scallop Aequipecten tehuelchus, Patagonian scallop Zygochlamys patagonica. Bivalve species irregularly exploited are: yellow clam Mesodesma mactroides, purple clam Amiantis purpurata, hard shell clam Ameghinomya antiqua and wedge shell Donax hanleyanus. It is a...

  17. Retained non-adaptive plasticity : gene flow or small inherent costs of plasticity?

    NARCIS (Netherlands)

    Edelaar, P; Piersma, T

    2005-01-01

    Question: Do clams from populations not exposed to a predator retain the ability to respond to that predator?? Motivation: If maintaining the potential for phenotypic plasticity involves a significant cost. plasticity should be selected against in constant environments. Background: Clams of the spec

  18. Anoxic survival of Macoma balthica: the effect of antibiotics, molybdate and sulphide

    NARCIS (Netherlands)

    De Zwaan, A.; Schaub, B.; Babarro, J.M.F.

    2001-01-01

    In anoxic semi-closed systems, the survival time of the clam Macoma balthica was compared to clams which were incubated in the presence of several antibiotics (chloramphenicol, 5- oxytetracycline hydrochloride, penicillin, streptomycin. a mix of penicillin and streptomycin and a mix of chloramphenic

  19. 50 CFR 648.74 - Shucking at sea.

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Shucking at sea. 648.74 Section 648.74... Clam and Ocean Quahog Fisheries § 648.74 Shucking at sea. (a) Observers. (1) The Regional Administrator may allow the shucking of surf clams or ocean quahogs at sea if he/she determines that an...

  20. 50 CFR 100.28 - Subsistence taking of shellfish.

    Science.gov (United States)

    2010-10-01

    ...; (iv) A handline; (v) A hydraulic clam digger; (vi) A mechanical clam digger; (vii) A pot; (viii) A... specified for each particular area and fishery; (7) If the return of catch information necessary for... subsistence shellfish fishery when that vessel is being chartered. (k) Subsistence shellfish areas...

  1. 50 CFR 648.76 - Maine mahogany quahog zone.

    Science.gov (United States)

    2010-10-01

    ... 648.76 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL OCEANIC AND ATMOSPHERIC... Atlantic Surf Clam and Ocean Quahog Fisheries § 648.76 Maine mahogany quahog zone. (a) Landing requirements... Advisory Panel shall make recommendations, through the Surf Clam and Ocean Quahog Committee of the...

  2. 50 CFR 648.77 - Framework adjustments to management measures.

    Science.gov (United States)

    2010-10-01

    ... measures. 648.77 Section 648.77 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... Management Measures for the Atlantic Surf Clam and Ocean Quahog Fisheries § 648.77 Framework adjustments to... add or adjust management measures within the Atlantic Surf Clam and Ocean Quahog FMP if it finds...

  3. 50 CFR 600.725 - General prohibitions.

    Science.gov (United States)

    2010-10-01

    .... Rod and reel, handline, pot, spear. 11. Surf Clam and Ocean Quahog Fishery (FMP managed by the MAFMC... fishery I. Rod and reel, handline, pot, spear. 4. Surf Clam and Ocean Quahog Fishery (FMP): A. Commercial... Note: For Federal Register citations affecting § 600.725, see the List of CFR Sections Affected,...

  4. Estimation of ingestion rate as nitrogen and factors creating its seasonal changes in Ruditapes philippinarum population in Banzu Tidal Flat, Tokyo Bay; Tokyowan Banzu higata no asari ni yoru chisso sesshuryo no suitei to sono kisetsu hendo ni kakawaru yoin

    Energy Technology Data Exchange (ETDEWEB)

    Isono, R. [Marine Ecology Research Institute, Chiba (Japan)

    1998-11-10

    The above-named clam is evaluated for water purifying capability. Experiments are conducted, and relations between the clam shell length and filtered water amount and the need of correction of the amount for temperature and salinity are clarified. Using existing materials, data are put in order about temperature, salinity, concentration levels of suspended nitrogen and chlorophyl, and changes in clam density. Findings are outlined below. The amounts of nitrogen that the clam group ingests per 1m{sup 2} of the tidal flat in August, when the group is the largest, and February, when the group is the smallest, are 300 and 19 mg-N/m{sup -2}h{sup -1}, respectively. Without pseudofeces production, the amount of food filtered by the clam is equal to the amount of food ingested. The filtered amount is estimated to be equivalent to 9-94% of the molluscan portion, but the figures may result from overestimation. The amount to be ingested is subject to seasonal changes, greatly dependent on temperature and suspended nitrogen concentration, but a little on salinity. A precisely planned temperature measurement will be required since the temperature change in the actual habitat of the clam is different from that in the tidal flat. Temperature is lower under the silt surface than on the silt surface. Troubles due to the exposure of the clam to high temperature on the ebb tide will be alleviated if the clam is deeper in the sand. 24 refs., 6 figs., 3 tabs.

  5. Filter-feeding, food utilization, and nutrient remineralization by Corbicula fluminea (bivalvia) and its contribution to nutrient cycling in a North Carolina River

    International Nuclear Information System (INIS)

    The introduced Asiatic clam Corbicula fluminea is quite prolific, and since it is a filter-feeder, it can be expected to influence the cycling of nutrients within its habitat as a result of its feeding and excretory activities. Factors affecting filtration rates, food utilization, and excretion of metabolic wastes (ammonia and phosphate) were determined by laboratory experiments, and these physiological processes were then extrapolated to field estimates of Corbicula found in the upper Chowan River, N.C., to obtain an estimate of the potential impact the clams can have on nutrient cycling in the river. Clam filtration rates of four different 14C-labeled algae species (two greens, a blue-green, and a diatom) were similar, although partitioning of the ingested isotope showed significant differences between the algal foods. The diatom species was the most efficiently utilized by the clams, with more than 80% of the isotope ingested recovered in clam tissues. Corbicula freshly collected from the Chowan River excreted substantially more ammonia than phosphate, and rates of excretion of both nutrients were highest in summer. Clam excretion rates were much higher than sediment fluxes, and as a source of recycled nutrients, these clams could provide about one third of the nitrogen and phosphate requirements of the phytoplankton in the upper Chowan

  6. Depuration Times of Donax trunculus and Tapes decussatus

    OpenAIRE

    Fatma Arik Çolakolu; Mine Çardak; Serhat Çolakoglu; Ibrahim Ender Künili

    2014-01-01

    The present study was performed to determine the depuration time and ability of Donax trunculus (Wedge Clam) and Tapes decussatus (Carpet Shell) contaminated with Escherichia coli, Salmonella enterica subsp. enterica serovar Typhimurium and Vibrio parahaemolyticus. Clams were contaminated with each bacterium at the level of 7.0 - 8.0 Log10 cfu/g. After contamination, clams were analyzed every 3 h in the first 24 h time period and every 6 h until the 72nd hour. During the depuration process of...

  7. Annual harvests of Corbicula populations prevent clogging of nuclear reactor heat exchangers

    International Nuclear Information System (INIS)

    An annual program for removal of millions of Corbicula from upstream cooling water basins has prevented reclogging of nuclear reactor heat exchanger distributor plates at the Savannah River Plant during the past seven years. There are nine 32-megaliter basins in the three operating reactor areas where some settling of particulates occurs before cooling water is passed through screens in route to heat exchangers. Annual cleanings keep silt/clam substrate levels low and clam sizes small. Data are presented on the size/age distribution for clams recolonizing basins between cleanings

  8. Environmental contaminants in fish and wildlife of Havasu National Wildlife Refuge, Arizona

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Sediment, vegetation, clams, fish, waterbirds and waterbird eggs were collected at Havasu National Wildlife Refuge (NWR) during April-August 1993 for organochlorine...

  9. Sensitivity of Coastal Environments and Wildlife to Spilled Oil: Puget Sound and Strait of Juan de Fuca, Washington: INVERT (Invertebrate Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for clams, oysters, crabs, and other invertebrate species in Puget Sound and Strait of Juan de Fuca,...

  10. Evidence of paleo-cold seep activity from the Bay of Bengal, offshore India

    Digital Repository Service at National Institute of Oceanography (India)

    Mazumdar, A.; Dewangan, P.; Joao, H.M.; Peketi, A.; Khosla, V.R.; Kocherla, M.; Badesab, F.K.; Joshi, R.K.; Roxanne, P.; Ramamurty, P.B.; Karisiddaiah, S.M.; Patil, D.J.; Dayal, A.M.; Ramprasad, T.; Hawkesworth, C.J.; Avanzinelli, R.

    Evidence of paleo–cold seep associated activities, preserved in methane-derived carbonates in association with chemosynthetic clams (Calyptogena sp.) from a sediment core in the Krishna-Godavari basin, Bay of Bengal is reported. Visual observations...

  11. Maine belowground marsh destruction from the European green crab documented by computer-aided tomography

    Science.gov (United States)

    Invasive European green crab (Carcinus maenus) populations have exploded with devastating losses to Maine’s intertidal resources including soft-shell clams, eelgrass beds, and salt marshes. This project quantified the green crab abundance in three different marsh locations ...

  12. PECONIC ESTUARY: AN ASSESSMENT OF SHELLFISH RESOURCES IN THE TRIBUTARIES AND EMBAYMENTS OF THE PECONIC ESTUARY

    Science.gov (United States)

    Executive Summary Historically, the Peconic Estuary's shellfish resources have supported significant fisheries for a number of species including hard clams, oysters and bay scallops. However, distribution and abundance data for the tributaries and embayments within the Peconic Es...

  13. Corbiculae fluminea as a bioindicator on the Lower Colorado River

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Tissue samples from Asiatic clam (Corbimla fluminea) from the lower Colorado River were analyzed for trace element concentrations. Selenium and arsenic were...

  14. SC/OQ Vessel Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data tables holding information for the Surf Clam/Ocean Quahog vessel and dealer/processor logbooks (negative and positive), as well as individual tag information...

  15. ACCUMULATION OF POLYCHLORINATED ORGANIC CONTAMINANTS FROM SEDIMENT BY THREE BENTHIC MARINE SPECIES

    Science.gov (United States)

    A laboratory experiment was conducted to measure the accumulation of selected polychlorinated compounds by marine benthos exposed to environmentally contaminated sediment. andworms (Nereis virens), clams (Macoma nasuta), and grass shrimp (Palaemonetes pugio) were exposed to sedim...

  16. Retained non-adaptive plasticity: gene flow or small inherent costs of plasticity?

    OpenAIRE

    Edelaar, P.; Piersma, T

    2005-01-01

    Question: Do clams from populations not exposed to a predator retain the ability to respond to that predator?? Motivation: If maintaining the potential for phenotypic plasticity involves a significant cost. plasticity should be selected against in constant environments. Background: Clams of the species Macoma balthica (a burrowing bivalve) respond to shore crabs by burrowing deeper in the sediment. Norwegian M. balthica are not exposed to crabs naturally whereas Dutch M. balthica are naturall...

  17. A comparative study of the effect of starvation regimes on the foraging behavior of Portunus trituberculatus and Charybdis japonica.

    Science.gov (United States)

    Sun, Yunfei; Wang, Fang; Dong, Shuanglin

    2015-11-01

    Predation of manila clams (Ruditapes philippinarum) by swimming crabs (Portunus trituberculatus) and Japanese stone crabs (Charybdis japonica) was compared in the laboratory under different starvation regimes by a video recording analysis system, and the mechanism of foraging behavior differences between them combined with ethograms and morphology characteristics was discussed. The main results were as follows: (1) Starvation had a significant effect on P. trituberculatus and C. japonica predation rates. With the increase of the starvation regime, predation rate tended to increase at first and then decrease. Under starvation for 6 days, their predation rates were 4.5 clams day(-1) and 5.5 clams day(-1), respectively. (2) Their foraging time budgets were significantly affected by starvation. The handling time per clam of P. trituberculatus (10.9 ± 4.7 min) was higher than C. japonica (5.3 ± 3.0 min), but the difference was not significant. (3) Encounter rate and the probability of capture upon encounter between P. trituberculatus and clams were significantly affected by starvation. The probability of capture upon encounter of P. trituberculatus was approximately 10 times the probability of consumption upon capture. Encounter rate and the probability of consumption were important components in the swimming crab-clam system. The probability of consumption upon capture between C. japonica and clams was significantly affected by starvation. The probability of consumption upon capture was an important component in the Japanese stone crab-clam system. (4) Relative frequencies of transition from stationary to moving and from searching to handling of P. trituberculatus were significantly affected by starvation. As for C. japonica, the relative frequency of transition from searching to handling was significantly affected by starvation. It revealed that the component regulating predation rate variation under starvation between swimming crabs and Japanese stone crabs was

  18. Corbicula fluminea (Bivalvia: Corbiculidae): a possible second molluscan intermediate host of Echinostoma cinetorchis (Trematoda: Echinostomatidae) in Korea

    OpenAIRE

    Chung, Pyung-Rim; Jung, Younghun; Park, Yun-Kyu; Hwang, Myung-Gi; Soh, Chin-Thack

    2001-01-01

    More than 1,500 clams of Corbicula fluminea, the most favorable food source of freshwater bivalves in Korea, were collected from 5 localities to examine cercarial and metacercarial infection with Echinostoma cinetorchis. Although 3 clams infected with suspicious E. cinetorchis metacercariae out of 200 specimens collected at Kangjin, Chollanam-do were detected, no cercarial and metacercarial infections with E. cinetorchis were observed in field-collected Corbicula specimens. In the susceptibil...

  19. Fishery management priorities vary with self-recruitment in sedentary marine populations

    OpenAIRE

    Yau, Annie J; Lenihan, Hunter S.; Kendall, Bruce E.

    2014-01-01

    Fisheries science often uses population models that assume no external recruitment, but nearshore marine populations harvested on small scales of 0.775 (equivalent to 52.85% self-recruitment under present conditions). Elasticity analysis of demographic parameters indicated that future abundance can most effectively be influenced by increasing survival of mid-sized clams (∼80–120 mm) if the population is self-sustaining, and by increasing survival of juvenile clams (∼40–70 mm) if the populatio...

  20. STUDI KANDUNGAN KITOSAN CANGKANG KAPAH (Meretrix sp.) DI PANTAI AMAL LAMA

    OpenAIRE

    Edy Prayogo;  Dori Rachmawani

    2013-01-01

    Chitosan is a polysaccharide that obtained by deacetylation of chitin. In this present day, chitosan been widely applicated and exploited in many sector of human life. Oriental hard clam was which one of fisheries commodity of Tarakan city, however it shells not yet been optimally exploited. The purpose of this research was to know the content of chitosan in oriental hard clam shell at Amal Lama beach. Sample determined by purposive sampling method. Meanwhile the isolation chitosan are using ...

  1. Handling enhances the development of brown ring disease signs in Ruditapes philippinarum

    OpenAIRE

    Jean, Fred; Flye-Sainte-Marie, Jonathan; Oudard, Clémence; Paillard, Christine

    2011-01-01

    Brown ring disease (BRD) in the Manila clam is characterized by the formation of a brown deposit of conchiolin on the inner surface of the shell that gives the disease its name. The development of the signs of BRD may be favored by the entry of bacteria in the extrapallial compartments via mechanical disruptions of the periostracal lamina and/or chipping of the shell margin. In order to test this hypothesis, we conducted an experiment simulating clam handling under aquaculture conditions and ...

  2. Biomonitoring and assessment of monomethylmercury exposure in aqueous systems using the DGT technique

    Energy Technology Data Exchange (ETDEWEB)

    Clarisse, O., E-mail: olivier.clarisse@umoncton.ca [Trent University, Chemistry Department, 1600 West Bank Drive, Peterborough, ON K9J 7B8 (Canada); Universite de Moncton, Departement de Chimie et de Biochimie, Moncton, New Brunswick E1A 3E9 (Canada); Lotufo, G.R. [Environmental Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS 39180-6199 (United States); Hintelmann, H. [Trent University, Chemistry Department, 1600 West Bank Drive, Peterborough, ON K9J 7B8 (Canada); Best, E.P.H. [Environmental Laboratory, U.S. Army Engineer Research and Development Center, Vicksburg, MS 39180-6199 (United States); U.S. Environmental Protection Agency, National Risk Management Research Laboratory, 26 West Martin Luther King Boulevard, Cincinnati, OH 45268 (United States)

    2012-02-01

    A series of laboratory experiments was conducted under realistic environmental conditions to test the ability of the Diffusive Gradient in Thin film (DGT) technique to mimic monomethylmercury (MMHg) bioaccumulation by a clam (Macoma balthica, Baltic clam). Using isotope enriched MMHg as tracers, bioavailability was determined by comparing the rate of MMHg uptake by novel DGT devices and sentinel organism over time. Experiments were conducted under varying conditions of salinity and MMHg speciation. Depending on MMHg level and speciation in the dissolved phase, MMHg uptake rates by the sentinel organism varied greatly from 0.4 to 2.4 L g{sup -1} d{sup -1}. Reproducibilities of MMHg uptakes by DGT and clams were estimated at 7 and 38%, respectively. A significant linear relationship (log basis) between MMHg accumulation by DGT and clams was observed (r{sup 2} = 0.89). The study demonstrates that DGT results reasonably predict MMHg uptake by clams from the aqueous phase and provide the basis for application of the DGT device as a surrogate for sentinel organism for monitoring bioavailable MMHg. - Highlights: Black-Right-Pointing-Pointer We investigate the potential of DGT devices to act as surrogates for sentinel organism. Black-Right-Pointing-Pointer We compare monomethylmercury accumulation in DGT devices and in clams from the dissolved phase. Black-Right-Pointing-Pointer We examine the effects of salinity and MMHg speciation on MMHg accumulation by DGT and clams. Black-Right-Pointing-Pointer For all laboratory experiments, a strong overall correlation between MMHg accumulations in clams and DGTs is observed.

  3. Pesquerías de bivalvos: mejillón, vieiras (tehuelche y patagónica) y otras especies

    OpenAIRE

    Ciocco, N.F.; Lasta, M.L.; Bremec, C.

    1998-01-01

    Fisheries of the mussel Mytilus edulis platensis, the tehuelche scallop Aequipecten tehuelchus and Patagonian scallop Zygochlamys patagonica are described. Information about catches of purple clam Amiantis purpurata in San Matias Gulf, mussel Aulacomya ater ater and hard shell clam Ameghinomya antiqua in San José Gulf is also presented. Regarding mytilus fishery, it is observed that the main catches were situated in Faro Querandí and Quequén beds (Buenos Aires Province, Argentina), where high...

  4. Careful Planning: The Fundraising Edge [and] A Twelve-Step Program for Stronger Grant Proposals [and] Business-School Partnerships: Future Media Center Funding Sources [and] Rakin' in the Clams... Or, How to Make Lots of Cash from Renting Best-Sellers [and] The Book Business: The Bookstore as an Alternative Funding Source for the Public Library [and] Friends of the Library Book Sales.

    Science.gov (United States)

    Sumerford, Steve; And Others

    1995-01-01

    Presents six articles addressing various methods and concerns for raising funds for public, academic, and school libraries, including raising money from corporations, foundations, and individuals; the process of writing grant proposals; local business/school partnerships; rental programs for bestsellers; bookstores/giftshops; and friends of the…

  5. Utilização do farelo de conchas de vôngole na adsorção de fósforo e como corretivo da acidez do solo Utilization of ground clam shells in the adsorption of phosphorus and for correction of soil acidity

    OpenAIRE

    Paola A. V. Lo Monaco; Antonio T. de Matos; Valdeir Eustáquio Júnior; Ivan C. A. Ribeiro; Denis L. Teixeira

    2012-01-01

    Teve-se o objetivo de, com a realização deste trabalho, obter a curva de neutralização do pH de amostras dos horizontes A e B de um Latossolo Vermelho-Amarelo distrófico, utilizando-se de farelo de conchas de vôngole (Anomalocardia brasiliana); além disso, avaliar a capacidade de adsorção de fósforo, obtendo-se a isoterma de adsorção de melhor ajuste aos dados obtidos. Verificou-se que o farelo de concha de vôngole apresenta potencial para uso como corretivo de acidez do solo e que a dose rec...

  6. Concentration distribution and potential health risk of heavy metals in Mactra veneriformis from Bohai Bay, China

    International Nuclear Information System (INIS)

    Highlights: • Mn was dominant in the heavy metals, followed by Zn, and Pb was the lowest. • THQs of Co were the highest at three sections and the others were less than 1. • Heavy metal concentration in clam was affected by pollution sources, and itself. • Consumer should be aware of their health risks associated with the consuming clam. - Abstract: To investigate the pollution level and evaluate the potential health risks of heavy metals, the concentrations of chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), molybdenum (Mo), cadmium (Cd), antimony (Sb), and lead (Pb) were determined by inductively coupled plasma-mass spectrometry (ICP-MS) in 198 clams (Mactra veneriformis) collected from 11 sites of the Bohai Bay. The results showed that heavy metal concentrations in the clams were different at different sites (p < 0.05). Mn was dominant with a percentage of 22.08–77.03% in heavy metals, followed by Zn with 12.66–57.11%, and the concentration of Pb was the lowest with 0.45–1.04%. The potential health risk to consumers was evaluated by the target hazard quotient (THQ) and the maximum daily consumption rate (CRmax). The results indicated that the THQs of Co were the highest with the values of 1.125, 1.665, and 1.144 at three sections; the values of other individual metals were <1, which indicated that consumption of clams from the study areas caused health risks due to Co. Moreover, the CRmax values also indicated the potential health risk caused by Co in clams consumed in this area. Pearson correlation analysis and principal component analysis (PCA) indicated that there were significantly positive or negative correlations between the heavy metals (p < 0.05), and the studied metals were divided into four groups. The results indicated that the concentrations of heavy metals in clams were affected not only by pollution sources but also by the characteristics of clams that could absorb

  7. Relationships between the stable isotopic signatures of living and fossil foraminifera in Monterey Bay, California

    Science.gov (United States)

    Martin, Jonathan B.; Day, Shelley A.; Rathburn, Anthony E.; Perez, M. Elena; Mahn, Chris; Gieskes, Joris

    2004-04-01

    Fossil foraminifera are critical to paleoceanographic reconstructions including estimates of past episodes of methane venting. These reconstructions rely on benthic foraminifera incorporating and retaining unaltered the ambient isotopic compositions of pore fluids and bottom waters. Comparisons are made here of isotopic compositions of abundant live and fossil foraminifera (Uvigerina peregrina, Epistominella pacifica, Bulimina mexicana, and Globobulimina pacifica) collected in Monterey Bay, CA from two cold seeps (Clam Flats and Extrovert Cliffs) and from sediments ˜5 m outside of the Clam Flats seep. Clam Flats has steep δ13CDIC gradients (to Extrovert Cliffs is less enriched in 12C (to approximately -22‰). Oxygen isotope values of fossil foraminifera at Clam Flats are ˜1.5‰ enriched in 18O over the living foraminifera, as well as those of both live and fossil foraminifera at Extrovert Cliffs, suggesting they may have lived during the last glacial maximum. Statistical comparisons (Student's t and Kolmogorov-Smirnov tests) of δ13C and δ18O values indicate that live and fossil foraminifera come from different populations at both Clam Flats and Extrovert Cliffs. At Clam Flats, the difference appears to result from alteration enriching some fossil foraminifera in 12C over live foraminifera. At Extrovert Cliffs, the fossil foraminifera are enriched in 13C over the live foraminifera, suggesting they lived prior to the onset of venting and thus that venting began recently. The short time of venting at Extrovert Cliffs may be responsible for the less alteration there compared with Clam Flats. These results indicate that preservation of foraminifera is likely to be poor within long-lived cold seeps, but that foraminifera living in the surrounding sediment may incorporate and preserve broad basin-wide changes in isotopic compositions of the ambient water.

  8. Nutritional value of winter foods for whooping cranes

    Science.gov (United States)

    Nelson, J.T.; Slack, R.D.; Gee, G.F.

    1996-01-01

    We measured metabolizable energy and digestibility of Whooping Crane (Grus americana) winter foods (blue crab [Callinectes sapidus]), common Rangia clam (Rangia cuneata), wolfberry fruit (Lycium carolinianurn [wolfberry]), and live oak acorn (Ouercus virginiana [acorn])] with feeding trials to captive-reared Whooping Cranes. Apparent metabolizable energy coefficients (expressed as %) were for crab (34.1), Rangia clam (75.0), wolfberry (44.8), and acorn (43.2). Digestion coefficients for protein were lower for plant foods (48.9 and 53.4) than for animal foods (69.4 and 75.2). Digestion coefficients for total lipid differed among foods: highest and lowest lipid digestibility was for acorn (87.2) and wolfberry (60.0), respectively. We also determined total energy and percent protein and lipid of the four foods and stout razor clam (Tagelus plebeius); gross energy was 2-5x higher for acorn and wolfberry on a dry-weight basis than for blue crab and stout razor clam. Crude protein was 2-3x higher for blue crab than for wolfberry and stout razor clam. Wolfberry ranked the highest of five foods for metabolic energy and total lipid nutrient availability per kg of food ingested, and blue crab ranked highest for crude protein availability.

  9. AcEST: DK951022 [AcEST

    Lifescience Database Archive (English)

    Full Text Available (release 39.9) Link to BlastX Result : TrEMBL tr_hit_id A5CUP1 Definition tr|A5CUP1|A5CUP1_CLAM3 Conserved h... OS=Claviba... 34 9.4 >tr|A5CUP1|A5CUP1_CLAM3 Conserved hypothetical protein OS=Clavibacter michiganensis subsp. michigane...9 Definition Adiantum capillus-veneris mRNA. clone: TST38A01NGRL0010_E13. 5' end sequence. Accession DK95102...nt alignments: (bits) Value tr|A5CUP1|A5CUP1_CLAM3 Conserved hypothetical protein...TST38A01NGRL0010_E13 669 Adiantum capillus-veneris mRNA. clone: TST38A01NGRL0010_E1

  10. AcEST: DK956676 [AcEST

    Lifescience Database Archive (English)

    Full Text Available ult : TrEMBL tr_hit_id A5CUP1 Definition tr|A5CUP1|A5CUP1_CLAM3 Conserved hypothetical protein OS=Clavibacter michigane...2 Definition Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0026_F20. 5' end sequence. Accession DK95667...lue tr|A5CUP1|A5CUP1_CLAM3 Conserved hypothetical protein OS=Claviba... 33 10.0 t...r|A4H6Q5|A4H6Q5_LEIBR Putative uncharacterized protein OS=Leish... 33 10.0 >tr|A5CUP1|A5CUP1_CLAM3 Conserved...TST39A01NGRL0026_F20 612 Adiantum capillus-veneris mRNA. clone: TST39A01NGRL0026_F2

  11. AcEST: BP920484 [AcEST

    Lifescience Database Archive (English)

    Full Text Available ease 39.9) Link to BlastX Result : TrEMBL tr_hit_id A5CUP1 Definition tr|A5CUP1|A5CUP1_CLAM3 Conserve...a... 33 7.3 >tr|A5CUP1|A5CUP1_CLAM3 Conserved hypothetical protein OS=Clavibacter michiganensis subsp. michigane...h programs, Nucleic Acids Res. 25:3389-3402. Query= BP920484|Adiantum capillus-veneris mRNA, clone: YMU001_000137_F04. (540 letter...oducing significant alignments: (bits) Value tr|A5CUP1|A5CUP1_CLAM3 Conserved hypothetical protein OS=Clavib...YMU001_000137_F04 540 Adiantum capillus-veneris mRNA. clone: YMU001_000137_F04. BP9

  12. A study on some trace elements in Chilean seafood

    International Nuclear Information System (INIS)

    Levels of essential and toxic trace elements in six marine species greatly in demand in the international market (canned pink clams, razor clams, clams, king crab, sardines, and frozen albacore tuna fish) were studied. A special laboratory adequately equipped for handling and preparing biological materials, is described. The elements As, Br, Na, Se, Hg, Cr, Fe, Zn and Rb were determined by INAA, while copper and cadmium content were determined using RNAA. Significant differences were found on comparing the contents of some toxic elements in mollusk and other samples of marine food. Various certified reference materials (CRMs) of the IAEA, NIST and NIES were analyzed for quality assurance purposes. (author) 11 refs.; 1 fig.; 1 tab

  13. Carotenoids in Marine Invertebrates Living along the Kuroshio Current Coast

    Directory of Open Access Journals (Sweden)

    Yoshikazu Sakagami

    2011-08-01

    Full Text Available Carotenoids of the corals Acropora japonica, A. secale, and A. hyacinthus, the tridacnid clam Tridacna squamosa, the crown-of-thorns starfish Acanthaster planci, and the small sea snail Drupella fragum were investigated. The corals and the tridacnid clam are filter feeders and are associated with symbiotic zooxanthellae. Peridinin and pyrrhoxanthin, which originated from symbiotic zooxanthellae, were found to be major carotenoids in corals and the tridacnid clam. The crown-of-thorns starfish and the sea snail D. fragum are carnivorous and mainly feed on corals. Peridinin-3-acyl esters were major carotenoids in the sea snail D. fragum. On the other hand, ketocarotenoids such as 7,8-didehydroastaxanthin and astaxanthin were major carotenoids in the crown-of-thorns starfish. Carotenoids found in these marine animals closely reflected not only their metabolism but also their food chains.

  14. Latest progress on R and D of ITER DFLL-TBM in China

    International Nuclear Information System (INIS)

    The China Low Activation Martensitic (CLAM) steel is being developed in ASIPP (Institute of Plasma Physics, Chinese Academy of Sciences) under wide collaboration with many institutes and universities. A heat of 1.2 tons was fabricated and tested. The tested main compositions are eligible and without segregation. The tensile, Charpy impact and fracture toughness tests showed that its mechanical properties were similar to those of small ingots of CLAM steel. Also, joining techniques such as Electron Beam Welding (EBW), Hot Isostatic Pressing-Diffusion Welding (HIP-DW) and fabrication techniques of rectangular tube with CLAM steel were studied in details. And a 1/3 scaled mockup of Test Blanket Module (TBM) by P91 are being fabricated to explore TBM fabrication technology.

  15. Location is everything: evaluating the effects of terrestrial and marine resource subsidies on an estuarine bivalve.

    Science.gov (United States)

    Harding, Joel M S; Segal, Michelle R; Reynolds, John D

    2015-01-01

    Estuaries are amongst the world's most productive ecosystems, lying at the intersection between terrestrial and marine environments. They receive substantial inputs from adjacent landscapes but the importance of resource subsidies is not well understood. Here, we test hypotheses for the effects of both terrestrial- and salmon-derived resource subsidies on the diet (inferred from stable isotopes of muscle tissue), size and percent nitrogen of the soft-shell clam (Mya arenaria), a sedentary estuarine consumer. We examine how these relationships shift across natural gradients among 14 estuaries that vary in upstream watershed size and salmon density on the central coast of British Columbia, Canada. We also test how assimilation and response to subsidies vary at smaller spatial scales within estuaries. The depletion and enrichment of stable isotope ratios in soft-shell clam muscle tissue correlated with increasing upstream watershed size and salmon density, respectively. The effects of terrestrial- and salmon-derived subsidies were also strongest at locations near stream outlets. When we controlled for age of individual clams, there were larger individuals with higher percent nitrogen content in estuaries below larger watersheds, though this effect was limited to the depositional zones below river mouths. Pink salmon exhibited a stronger effect on isotope ratios of clams than chum salmon, which could reflect increased habitat overlap as spawning pink salmon concentrate in lower stream reaches, closer to intertidal clam beds. However, there were smaller clams in estuaries that had higher upstream pink salmon densities, possibly due to differences in habitat requirements. Our study highlights the importance of upstream resource subsidies to this bivalve species, but that individual responses to subsidies can vary at smaller scales within estuaries. PMID:25993002

  16. Location is everything: evaluating the effects of terrestrial and marine resource subsidies on an estuarine bivalve.

    Directory of Open Access Journals (Sweden)

    Joel M S Harding

    Full Text Available Estuaries are amongst the world's most productive ecosystems, lying at the intersection between terrestrial and marine environments. They receive substantial inputs from adjacent landscapes but the importance of resource subsidies is not well understood. Here, we test hypotheses for the effects of both terrestrial- and salmon-derived resource subsidies on the diet (inferred from stable isotopes of muscle tissue, size and percent nitrogen of the soft-shell clam (Mya arenaria, a sedentary estuarine consumer. We examine how these relationships shift across natural gradients among 14 estuaries that vary in upstream watershed size and salmon density on the central coast of British Columbia, Canada. We also test how assimilation and response to subsidies vary at smaller spatial scales within estuaries. The depletion and enrichment of stable isotope ratios in soft-shell clam muscle tissue correlated with increasing upstream watershed size and salmon density, respectively. The effects of terrestrial- and salmon-derived subsidies were also strongest at locations near stream outlets. When we controlled for age of individual clams, there were larger individuals with higher percent nitrogen content in estuaries below larger watersheds, though this effect was limited to the depositional zones below river mouths. Pink salmon exhibited a stronger effect on isotope ratios of clams than chum salmon, which could reflect increased habitat overlap as spawning pink salmon concentrate in lower stream reaches, closer to intertidal clam beds. However, there were smaller clams in estuaries that had higher upstream pink salmon densities, possibly due to differences in habitat requirements. Our study highlights the importance of upstream resource subsidies to this bivalve species, but that individual responses to subsidies can vary at smaller scales within estuaries.

  17. Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California; 2015

    Science.gov (United States)

    Cain, Daniel J.; Thompson, Janet K.; Crauder, Jeffrey; Parchaso, Francis; Stewart, Robin; Turner, Matthew; Hornberger, Michelle I.; Luoma, Samuel N.

    2016-01-01

    Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in South San Francisco Bay, California. This report includes data collected by U.S. Geological Survey (USGS) scientists for the period from January 2015 to December 2015. These data are appended to long-term datasets extending back to 1974, and serve as the basis for the City of Palo Alto’s Near-Field Receiving Water Monitoring Program, initiated in 1994.

  18. Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in South San Francisco Bay, California-2010

    Science.gov (United States)

    Dyke, Jessica; Parcheso, Francis; Thompson, Janet K.; Cain, Daniel J.; Luoma, Samuel N.; Hornberger, Michelle I.

    2011-01-01

    Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in South San Francisco Bay, Calif. This report includes the data collected for the period January 2010 to December 2010 and extends a critical long-term biogeochemical record that dates back to 1974. These data serve as the basis for the City of Palo Alto's Near-Field Receiving Water Monitoring Program initiated in 1994.

  19. Diversification de la production : culture de palourdes sur estran, premiers résultats 1984 semis expérimentaux 1985

    OpenAIRE

    Goulletquer, Philippe

    1985-01-01

    The study of foreshore clam culture with three immersion levels (40, 50, 70) has demonstrated a backlog in clam growth on the highest level, as well as a reproduction backlog and a weakened physical state during winter for populations unimmersed with a tide coefficient of 40-50. But the available areas for these cultures (areas that have not been allocated to oyster or mussel culture) are those unimmersed with those tide coefficients. Thus, it is not advised to extend the surfaces granted in ...

  20. Mirror alignment control for COMPASS RICH-1 detector

    Energy Technology Data Exchange (ETDEWEB)

    Alexeev, M. [INFN, Sezione di Torino and University of East Piemonte, Alessandria (Italy); Birsa, R. [INFN, Sezione di Trieste, Trieste (Italy); Bradamante, F.; Bressan, A. [INFN, Sezione di Trieste and University of Trieste, Trieste (Italy); Chiosso, M. [INFN, Sezione di Torino and University of Torino, Torino (Italy); Ciliberti, P. [INFN, Sezione di Trieste and University of Trieste, Trieste (Italy); Dalla Torre, S. [INFN, Sezione di Trieste, Trieste (Italy); Denisov, O. [INFN, Sezione di Torino, Torino (Italy); Duic, V. [INFN, Sezione di Trieste and University of Trieste, Trieste (Italy); Ferrero, A. [INFN, Sezione di Torino and University of Torino, Torino (Italy); Finger, M.; Finger, M. [Charles University, Praga (Czech Republic); JINR, Dubna (Russian Federation); Giorgi, M. [INFN, Sezione di Trieste and University of Trieste, Trieste (Italy); Gobbo, B. [INFN, Sezione di Trieste, Trieste (Italy); Levorato, S. [INFN, Sezione di Trieste and University of Trieste, Trieste (Italy); Maggiora, A. [INFN, Sezione di Torino, Torino (Italy); Martin, A. [INFN, Sezione di Trieste and University of Trieste, Trieste (Italy); Menon, G. [INFN, Sezione di Trieste, Trieste (Italy); Panzieri, D. [INFN, Sezione di Torino and University of East Piemonte, Alessandria (Italy); Pesaro, G. [INFN, Sezione di Trieste and University of Trieste, Trieste (Italy)

    2011-05-21

    The focusing system of the COMPASS RICH-1 detector consists of two segmented spherical mirror surfaces, formed by 68 hexagonal and 48 pentagonal individual elements. All individual mirrors have two degrees of freedom to adjust the angular alignment in order to obtain a continuous spherical surface. Relative angular misalignments can be monitored on-line by the CLAM method, based on the optical reconstruction of line images. Complementing the CLAM measurements with photogrammetry, the absolute mirror orientation and position in space can be determined too. The method is described, as well as the algorithms used to access the relative and absolute mirror alignment.