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1.
《Journal of Sea Research》1999,41(3):213-224
Field collections of the bivalve Macoma balthica in the Dutch Wadden Sea and three southeastern United States estuaries revealed morphological differences between populations of the two sides of the Atlantic Ocean. Individuals of the same age showed much larger shell lengths at the American stations. In addition, bivalves of the same body weight had higher siphon weights at the American stations than at the Dutch stations. This difference in siphon size was related to their burying depths. The American population, which invested more in heavier siphons, was able to burrow much deeper into the sediment (up to 30 cm). Deep burial may be an adaptation to avoid exposure to the high southern temperatures. Furthermore, it may serve as a refuge from blue crab predation. The results of our comparison between the southern American population and the European support the suggestion that populations of M. balthica living in these two regions should be considered separate and sibling species.  相似文献   

2.
《Journal of Sea Research》1999,41(3):203-212
Bivalve eggs generally contain large amounts of lipids which, in comparison with proteins and carbohydrates, have high energy contents and are thus costly in energetic terms. As lipid contents vary between species, comparisons of reproductive investments should not only include numbers and sizes of eggs, but also their energy content. We estimated the investment in egg material of mature females of the Baltic tellin Macoma balthica (L.) in terms of both mass and energy content. All mass below a minimum body mass (below which no eggs are produced) was defined as structural mass. This threshold amounts to a body mass index (BMI) of 5.6 (ash-free dry mass per cubic shell length in mg cm−3). More than half (55%) of the mass above the structural mass was invested in egg material and 45% in extra somatic tissue and tissue for production and storage of gametes. This means that the amount of eggs spawned ranged from 0 (at BMI = 5.6 mg cm−3) to 33% of the total ash-free dry mass (at a high BMI value of 14 mg cm−3). Eggs contained a relatively large amount of lipids, about 30% of their ash-free dry mass, whereas non-egg material contained only about 7% lipids. Eggs of two other bivalves in the Wadden Sea, the cockle Cerastoderma edule and the mussel Mytilus edulis, were smaller and contained only about 11% and 20% lipids, respectively. Energy content of M. balthica eggs amounted to ∼0.006 J, in the other two species to ∼0.002 J. The function of the more expensive eggs in M. balthica may be related to its early spawning in spring, causing slower larval development until first feeding.  相似文献   

3.
In 1995 the seasonal development of concentrations of both phytoplankton and larvae of the bivalve Macoma balthica was studied in the coastal zone behind the back-barrier island of Spiekeroog (German Wadden Sea). In July/August larvae reached maximum concentrations of about 1000 to 4200 ind. m−3 (depending on the sampling site and tidal period), probably in relation to a phytoplankton bloom in July. This observation of an unusually late maximum of Macoma larvae is discussed in detail in connection with the recent literature available about spawning of M. balthica in the Wadden Sea.  相似文献   

4.
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5.
《Journal of Sea Research》2003,49(3):171-185
Epibenthic biogenic structures such as polychaete tubes are conspicuous features of many marine soft-bottom habitats. This paper compares the benthic macrofauna in patches with high and low densities of the tube-dweller Pygospio elegans on intertidal sandflats in eastern Scotland (UK). The main aim of this study was to determine potential differences in the macrofaunal community structure, the size distribution of individual species and sediment properties.Multivariate data analyses revealed that the macrofaunal community composition (excluding P. elegans) within patches was always significantly different from outside patches, mainly due to variability in the abundances of Cerastoderma edule and Corophium volutator. In addition to P. elegans, 5 taxa were sufficiently abundant for univariate analyses, 4 of these (Capitella capitata, C. edule, Macoma balthica and C. volutator) being significantly more abundant within P. elegans patches than in surrounding, non-patch sediments. The size distribution of P. elegans was significantly different between patches (bimodal distribution) and non-patches (skewed distribution). Similarly, there was a greater proportion of larger C. capitata individuals within patches compared to non-patch sediments. Sediment organic content and silt/clay fraction were always significantly higher in patch sediments while redox profiles showed no differences except at the end of the study period when the top 2 cm within patches were more positive and more negative at 4 cm. These results imply that even relatively small (1–1.5 m2) P. elegans patches can have large effects on the spatial variability of macrofaunal community structure on intertidal sandflats.Towards the end of the study there were marked visual changes in the P. elegans patches, such as wave-ripple marks on the surface, which signified their demise. This coincided with dramatic changes in the invertebrate community structure within patches. Along with the decline in P. elegans numbers, dramatic increases in the densities of the 2 bivalve species C. edule and M. balthica occurred, while remaining comparatively stable outside patches. This suggested that the conditions within P. elegans patches were particularly favourable to successful bivalve spat settlement. We postulate that P. elegans patches have limited longevity and propose that enhanced bivalve competition within them leads to rapid decreases in P. elegans numbers.  相似文献   

6.
Oysters (Crassostrea virginica) and soft shell clams (Mya arenaria) were exposed to two different total copper concentrations (10 μg liter−1 and 30 μg liter−1) and two different cupric ion activities (10−10 m and 10−9 m) under high salinity and low salinity conditions. Cupric ion activities were adjusted by adding nitrilotriacetic acid (NTA) to the experimental media.Copper accumulation by both species was inversely related to salinity and positively associated with total copper and cupric ion activity. This salinity effect was proportionately greater for lower copper concentrations and activities and it was concluded that salinity would, therefore, be an important influence on metal accumulation in the natural environment. The salinity effect was still apparent when the cupric ion activity was held constant indicating that the effect is, at least in part, independent of the copper speciation in the medium.  相似文献   

7.
《Marine Chemistry》2001,74(1):65-85
Here it is demonstrated that both Porphyra spp. and Enteromorpha spp. of macro-algae display similar and very marked seasonal variations in their concentration factor (CF) of Cu, Pb, Cd and Hg in field conditions. The CF variations are specific for each metal and reproducible over several years. The way variations in the biological activity affect the equilibrium and kinetics of the interaction between trace metals and live algae was studied in vitro. Natural seawater was used as the culture medium. Voltammetry was used for the determination of natural organic ligands and trace metals except Hg, which was determined by mercury cold vapour after on-line pre-concentration. Titrations with the relevant metal demonstrated that the maximum binding capacity of the algae was not significantly dependent on the season for Pb (ca. 100 μmol gdry algae−1), Cd (ca. 50 μmol g−1) and Hg (80–100 μmol g−1). Marked seasonal variations were observed for Cu (ca. 40 μmol g−1 in January; 70 μmol g−1 in May; and 100 μmol g−1 in August). The conditional stability constants of metal–algae complexation sites were seasonally independent and similar for both algae: logKMS′=8.5±0.3 (Cu), 5.6±0.2 (Pb), 5.3±0.2 (Cd) and 18.0±0.3 (Hg). Exudates with a strong Cu complexing capacity (logK′CuL=12.47±0.06) were determined in cultures with added Cu, Pb or Cd concentrations, and identified by cathodic stripping voltammetry (CSV) as cysteine or glutathione. All the tested metals promoted the liberation of exudates, both cysteine- and glutathione-like ligands were exuded in the presence of Cu, only cysteine-like ligands in the presence of Pb, and only glutathione-like ligands in the presence of Cd, the rise depending of the season of the year, particularly for Cu. Highest levels were produced in the presence of added Pb. When exposed to either 1- or 100-μM total dissolved metal concentrations, the metal uptake, and its rate, varied with the season and the algae.  相似文献   

8.
Petroleum hydrocarbons were investigated in Mytilus edulis and Macoma balthica at six intertidal sites in Port Valdez, Alaska after three to five years of oil terminal operation. Information about the concentrations of total hydrocarbons, unresolved complex mixture, normal alkanes, isoprenoids, olefins, hopanes and polycyclic aromatic hyrocarbons shows that petroleum accumulation in these bivalve mollusks is greatest at the Valdez municipal boat harbor and a crude oil terminal which has been permitted to discharge 170 kg oil day−1. Accumulation two- to ten-fold less were observed at 3 km from the terminal and boat harbor. The temporal trends in petroleum hydrocarbon concentrations in M. edulis and M. balthica reflect the effects of selective retention and depuration of different hydrocarbon classes as well as variation in hydrocarbon sources. It is not clear whether the petroleum concentrations in Port Valdez bivalves had reached steady state by 1982, the final sampling time reported here.  相似文献   

9.
An investigation of the factors responsible for the distribution of Macoma balthica (L.) on a mudflat receiving sewage effluent was carried out in the Fraser River estuary, British Columbia. The factors examined included reduced salinity, low levels of dissolved oxygen, effluent toxicity, chlorination, substrate grain size and the effects of metal contaminated sediments. Results showed that salinity, dissolved oxygen and sediment grain size did not satisfactorily explain the distribution of M. balthica. Unchlorinated and chlorinated sewage effluent were shown to be non-toxic in laboratory tests, and these results were confirmed by 7-day in situ bioassays. The factor which appeared to determine the distribution of M. balthica was the degree of contamination of the substrate which affected the settling and survival of larval and juvenile clams. Heavy metals occurred in high concentrations in the contaminated sediments and were considered to be the most probable controlling factor.  相似文献   

10.
Laboratory experiments were designed to measure the uptake of Tc by clams from North-East Atlantic sediments which were contaminated with different oxidation states of 95mTc. Distribution coefficients between solid sediment and pore water were similar for Tc IV and VII and never exceeded 3·5 during the 36-day experiment. Furthermore, 95mTc was rapidly leached from the sediments with a half-time of about 4·5 days. Biological uptake was low, with transfer factors between clam tissues and sediment ranging between 0·04 and 0·6. Greater relative uptake was noted in the soft tissues than in shell, although the latter contained the largest fraction (70%) of the clam's whole body 95mTc content. Contaminated clams, transferred to uncontaminated sediments, displayed a very long biological half-life (～120 days) for 95mTc. This observation suggests that following acute contamination, clams living in an environment of this type would still retain Tc in their tissues long after the radionuclide had been leached from the sediments.  相似文献   

11.
In order to assess the adaptation to metals previously observed in the bioindicator organism, Macoma balthica, subjected to chronic contamination by silver and mercury in the French Loire estuary, the bioaccumulation potential of individual organisms originating from the contaminated Loire estuary and a relatively uncontaminated control estuary (Somme) was evaluated using both radiotracers and stable isotopes of Ag (80 μg Ag litre−1) and Hg (100 μg Hg litre−1). Clams from the contaminated estuary were more sensitive to Ag (LT50 = 9d) than those originating from the Somme estuary (LT50 > 15d), even though the former bioaccumulated Ag to a significantly lower degree. This is attributed to a consequence of the chronic stress induced by Ag while clams were living in their natural environment. Therefore, past history of trace metal contamination should be considered when evaluating the susceptibility of M. balthica to heavy metal exposure. Lower uptake rates obtained for Hg (during the initial uptake phase only) and for Ag in clams from the polluted estuary suggest the presence of an adaptive trait for survival in contaminated areas. However, the lower degree of bioconcentration observed for Ag was not sufficiently low to reduce the sensitivity of the organisms to Ag and allow them to resist the toxic stress. Clams that survived Ag or Hg exposure at LT50 did not protect themselves against metal toxicity by accumulating a significantly lesser amount of these metals than clams which did not survive metal stress. The results suggest that the bioaccumulation potential of each individual was not a factor which can explain the survival ability of M. balthica exposed to chronic Ag and Hg contamination in estuaries. In this case, cellular, biochemical and genetic levels of adaptation are presumed to be of greater importance.  相似文献   

12.
Pathologic condition of Manila clam, Ruditapes philippinarum collected from Haeju off the west coast of North Korea in February and March 2007 was investigated in this study. The diagnostics included a protozoan parasite, Perkinsus olseni, the brown ring disease (BRD) caused by bacteria Vibrio tapetis and metazoan parasites Trematod and Cestod. P. olseni infection was examined using histology and Ray’s fluid thioglycollate medium (RFTM) assay along with Choi’s NaOH digestion technique. Trematode and cestode infection was also examined from the histology. A total of 140 clams with 35–45 mm in shell length (2–3 years old) were analyzed. Condition factor (CF), a ratio of the wet tissue weight to the shell dry weight, ranged from 0.445±0.074 (February) to 0.544±0.132 (March). Total body burden of P. olseni (i.e. infection intensity) ranged from 18,644±37,755 (February) to 26,933±80,611 cells/g wet tissue (March) with the prevalence of 76.7–43.3% (March) respectively. Prevalence of trematode and cestode infection in February and March varied 22.5–25.0 and 15.0–22.5% respectively. Infection intensity of V. tapetis ranged 1–2 and the prevalence was 1.4 (February) and 5.7% (March). Prevalence and infection intensity of P. olseni in clams from Haeju was comparatively lower than those of clams reported on the west coast of Korea. BRD and the other metazoan parasite infection were also relatively lower or similar to the condition of the clams reported previously. CF of Haeju clams was also relatively higher than the clams in Gyeonggi Bay and Taean, suggesting that Haeju clams had relatively better pathologic and health condition.  相似文献   

13.
The effects of chronic hypoxia and low salinity on anti-predatory responses of the green-lipped mussel Perna viridis were investigated. Dissolved oxygen concentrations ranged from hypoxic to normoxic (1.5 ± 0.3 mg l−1, 3.0 ± 0.3 mg l−1 and 6.0 ± 0.3 mg l−1), and salinities were selected within the variation during the wet season in Hong Kong coastal waters (15‰, 20‰, 25‰ and 30‰). The dissolved oxygen and salinity significantly affected some anti-predatory responses of mussel, including byssus production, shell thickness and shell weight, and the adductor diameter was only significantly affected by salinity. Besides, interactive effects of dissolved oxygen and salinity on the byssus production and shell thickness were also observed. In hypoxic and low salinity conditions, P. viridis produced fewer byssal threads, thinner shell and adductor muscle, indicating that hypoxia and low salinity are severe environmental stressors for self-defence of mussel, and their interactive effects further increase the predation risk.  相似文献   

14.
缢蛏(Sinonovacula constricta)是我国重要的水产经济贝类,开展耐高盐新品种选育对平衡不同地区缢蛏良种养殖意义重大。本研究对不同家系缢蛏幼贝进行高盐胁迫,运用统计学方法和相关性分析探究了缢蛏耐高盐性能及其与生长性状的相关性。结果显示,缢蛏家系间壳长、壳高、壳宽和体质量表型值差异较大,体质量变异系数达15.53%。不同家系对高盐耐受性差异较大,家系间死亡率范围在0～100%。胁迫实验共持续9 d,各家系缢蛏首粒死亡时间在第1～9 d之间,而且死亡率较高的家系内缢蛏死亡时间离散程度较大,说明不同个体间高盐耐受性差异也较大。缢蛏开始出现大量死亡的时间主要在胁迫后第8 d,第9 d部分家系死亡率高于80%,说明缢蛏对高盐耐受存在一个阈值,超过该阈值会开始或大量死亡。皮尔逊和斯皮尔曼相关性分析显示,缢蛏存活时间和生长性状为正相关,其中存活时间与缢蛏壳长、体质量相关性均达到显著水平(P<0.05)。缢蛏存活率与体质量、生长速度均显著正相关(P<0.05)。整体而言,壳长较长和体质量较重的缢蛏个体耐高盐性能较强,在高盐环境中具有生长优势。本研究揭示了缢蛏的高盐耐受性及...  相似文献   

15.
The relationships between the linear dimensions and body weight and the ratio between the masses, growth, and production were studied for the bivalve Astarte borealis inhabiting the southeastern Baltic Sea. The maximal shell length was 21.09 mm, while the maximum age was 8+. The linear growth was described by the Bertalanffy equation L τ = (1 - e -0.0894(τ-(-0.7354))). The annual production was 7.60 kJ/m2 at a P s/B coefficient of 0.41. It was found that the A. borealis inhabiting the southeastern Baltic Sea was characterized by a lower linear growth rate compared to the mollusks of other parts of the geographical range due to the low salinity of the Baltic Sea.  相似文献   

16.
The major aim of this study was to evaluate the capacity of Salicornia ramosissima on Cadmium phytoremediation under distinct salinities and, consequently, the toxic effects on the plant's development. A greenhouse experiment was performed, using two Cd concentrations (50 and 100 μg l−1) in different salinities (0, 5 and 10). Mortality and weight variation, observed at the end of the experiment, showed significant differences between some treatments, meaning that these variables were affected by the salinity and Cd concentrations. The highest Cd accumulation was detected in the roots, and decreased with the increase of salinity and Cd concentration. S. ramosissima is a potential candidate for Cd phytoremediation at salinities close to 0 and its capabilities in Cd phytoaccumulation and phytoestabilization proved to be quite interesting. The optimization of phytoremediation processes by S. ramosissima could turn possible the use of this plant in the recovery of contaminated ecosystems.  相似文献   

17.
Bathymodiolus brevior [von Cosel, R., Métivier, B., Hashimoto, J., 1994. Three new species of Bathymodiolus (Bivalvia: Mytilidae) from hydrothermal vents in the Lau Basin and the North Fiji Basin, western Pacific, and the Snake Pit Area, mid-Atlantic ridge. Veliger 37, 374–392] a bivalve mollusk living at deep-sea hydrothermal vents, exhibits daily microgrowth structures in its shell. This interpretation is substantiated by various lines of evidence: (1) similar shell portions of contemporaneous specimens from the same locality contain almost the same number of microincrements; (2) the number of microincrements coincides with the expected number of days in which shell portions of Bathymodiolus spp. form; (3) the width of such microincrements compares well with daily growth rates estimated for the close relative B. thermophilus [Kenk, V.C., Wilson, B.R., 1985. A new mussel (Bivalvia, Mytilidae) from hydrothermal vents in the Galapagos rift-zone. Malacologia 26, 253–271]; (4) different specimens from the same site show similar microgrowth curves. In addition, we found support for tide-controlled shell growth. Daily shell growth rates fluctuate on a fortnightly basis. Some shell portions also revealed the typical tide-controlled microgrowth pattern commonly observed in intertidal bivalves. Based on the analyses of lunar daily growth increments, a growth curve for B. brevior was computed: Xt=14 cm−(14–0.04 cm) e−0.26t. This curve enables estimation of ontogenetic age from shell length. According to this equation, B. brevior reaches its maximum shell length of 14 cm at about age 18. Shell isotope analyses suggest that some major shell growth interruptions or retardations are related to extremely active hydrothermal venting activity. However, shell growth also stopped during periods of low venting implying physiological controls on shell formation. Results of the present study demonstrate that shells of B. brevior provide calendars and environmental data loggers that can complement or partly substitute for long-term observations of venting systems.  相似文献   

18.
Studies on the processes of Cd accumulation, turnover and storage in marine molluscs have revealed important qualitative and quantitative differences between species. In Littorina littorea collected from uncontaminated sites, Cd is predominantly bound to metallothionein (MT)-like proteins. Exposure to Cd, in the laboratory and field, results in an increase in Cd bound to these proteins, together with limited increases in Cd in the high molecular weight (HMW) pool (the latter partly a result of haemocyanin-mediated transport of Cd in the haemolymph). Polarographic determination of heat-stable MT-like compounds in L. littorea indicates there is little overall increase in the amount of protein produced in response to Cd exposure, suggesting that much of the newly incorporated metal may be bound to previously synthesised material. Relatively high levels of MT-like proteins, notably in the digestive gland (the major Cd-storage organ), appear to be an inherent feature of this species even in uncontaminated areas.MT-like proteins also sequester much of the Cd in exposed mussels Mytilus edulis, though, unlike Littorina, protein induction can be quantitatively related to exposure. In contrast, tellinid clams, Macoma balthica, fail to produce MT-like compounds, even in highly contaminated conditions, and Cd is mainly bound to HMW proteins.These variations in metal-binding behaviour probably explain the large interspecific differences in experimentally-determined Cd uptake rates and may account for differences in bioaccumulation potential observed in the field. Despite such variability, all three species studied appear to tolerate an influx of Cd provided the normal partitioning of metal is not irreversibly disturbed. Maintaining intracellular homeostasis, albeit at elevated Cd concentrations, probably compensates for the inability of these animals to regulate Cd uptake and for their extremely slow rates of Cd excretion.  相似文献   

19.
A laboratory experiment was performed with the clam Ruditapes decussatus, fed with the toxic dinoflagellate Gymnodinium catenatum and the non-toxic algae Isochrysis galbana (14 days) and subsequently only with I. galbana (15 days). Individual paralytic shellfish toxins were determined by LC-FLD in G. catenatum cells, whole clam tissues, and particulate organic matter (POM) produced by clams. The toxins dcSTX and dcGTX2 + 3 in the algae were less abundant than C1 + 2 and B1, but were predominant in clams during both the exposure and depuration phases. The toxin dcNEO was only detected in clams during a short period, indicating conversion from other compounds. The toxin composition of the POM indicated the export of dcSTX as faeces or pseudo-faeces along the entire experiment (2.5–14 nmol mg−1), B1 was present in a short period of the exposure and C1 + 2 and dcGTX2 + 3 absent. A mass balance calculation indicated that approximately 95% of C1 + 2 and 85% of B1 supplied to the clams were converted into other toxins or lost in solution. Conversely, the net gain of 512, 61 and 31 nmol for dcSTX, dcGTX2 + 3 and dcNEO, respectively, suggests the conversion from other assimilated compounds by clams during exposure and depuration phases.  相似文献   

20.
A breeding-selection program for the clam,Meretrix meretrix,was conducted since 2004.Two of the selection 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 populations(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 individuals 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.  相似文献   

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