A 28‐d partial life‐cycle test with the estuarine amphipod Leptocheirus plumulosus was developed in response to the need for an assay to mimic chronic exposure to sediment‐associated contaminants. To ensure that toxicity tests have environmental relevance, it is essential to evaluate the relationship between laboratory responses and field measures of contamination. Consequently, one objective of the study was to compare the results of the chronic sediment toxicity test with L. plumulosus to gradients of sediment contamination and the in situ benthic community in its native Chesapeake Bay. Chronic tests were conducted by two laboratories, the Army Corps of Engineers Waterways Experiment Station ([WES]; Vicksburg, MS, USA) and the University of Maryland ([UM] College Park, MD, USA) using different feeding regimes, providing the opportunity to evaluate the effect of this variable on response sensitivity. A second objective was to compare the relative sensitivity of acute and chronic tests with L. plumulosus with field‐collected sediments. Overall, there was good agreement between the toxicological response of acute and chronic tests with L. plumulosus and field measures of contamination. Survival in the acute test and chronic test conducted by WES was negatively correlated with concentrations of sediment‐associated contaminants. Survival in acute exposures was significantly reduced in sediments from 8 of 11 stations. Indigenous L. plumulosus were found only at two of the three stations that did not exhibit acute toxicity. An unexpected finding was the difference in responsiveness of the two chronic tests. Survival in tests conducted by UM and WES was significantly reduced in sediments from 4 and 6 of 11 stations, respectively. No additional sublethal toxicity was detected in the UM chronic test, but the WES test detected reproductive effects at two additional stations. We believe the observed differences were related to the test diet used. Partly as a result of our findings, the recommended diet for the L. plumulosus chronic test was changed in the final methods document.

Fathead minnows (Pimephales promelas) were exposed to the biocide chlorine dioxide (0.13 and 0.19 mg l-1) for up to 12 h and to its primary decomposition product, chlorite (177 and 304 mg l-1), for up to 96 h followed by recovery periods of up to 14 days. Chlorine dioxide exposure produced dose-dependent gill pathology including epithelial lifting, hypertrophy, hyperplasia, lamellar fusion, and necrosis. Complete recovery, even in fish with severe hypertrophy and lamellar fusion, was achieved within 4 days. Chlorite did not produce gill pathology even at a lethal exposure level (304 mg l-1 for 96 h) but did elicit a chronic inflammatory response with a marked increase in circulating and fixed phagocytes within hematopoietic and vascular tissues. This study indicates that chlorine dioxide is approximately 1000 times more toxic to fathead minnows than chlorite. Further, exposure of fathead minnows to these distinct but related compounds is consistently associated with very different pathologies.

Toxicity bioassays were conducted on embryos and early larvae of quagga mussels, Dreissena bugensis, using a filtered aqueous extract and a lyophilized butanol extract of the soap berry plant Phytolacca dodecandra. Developmental stages exposed to each extract were embryos to trochophores (ca 3 h-17 h), trochophores to D-hinge larvae (ca 17 h-40 h) and embryos to D-hinge (3 h-ca 40). Over the whole embryo to D-hinge exposure period, the aqueous extract resulted in a lowest observed effective concentration (LOEC) of 5 mg l(-1), although mortality did not exceed 50%. For the butanol extract, the LOEC was 2 mg l(-1) and the LC50 was 2.1 mg l(-1). For the aqueous extract, most of the ended toxicity was seen at the embryo stage, whereas for the butanol extract the toxicity was associated with the trochophore stage. Compared with other non-oxidizing commercial molluscicides, ended has only moderate toxicity to early dreissenid life stages.

Zebra (Dreissena polymorpha) and quagga mussel (D. bugensis) larvae were reared through and beyond metamorphosis in the laboratory on diets of the estuarine algae, Isochrysis galbana T-Iso and Pavlova (= Monochrysis) lutheri. Larvae were successfully spawned and raised in the laboratory for over 1 year with routine survival to settlement. Some adult males reared from an August 1994 spawn reached sexual maturity with active sperm by April 1995. Diets of dried Chlorella sp. and Synecococchus sp. were unable to support larvae. Settlement of pediveligers at 22°C occurred at ≈ 21 days for zebra mussel and 32 days for quagga mussels. Saturated fatty acids predominated in I. galbana and P. lutheri, whereas polyunsaturated fatty acids (PUFAs) predominated in Chlorella sp. The process to culture dreissenid larvae in the laboratory is very labor-intensive and requires continuous culture of live algae maintained in log growth phase. Larvae are fed every other day at a density of 2 × 105 cells mL−1 for the first week, and then daily densities of 3–5 × 105 cells mL−1 thereafter. Water quality is critical. Larvae and juveniles should be stocked at densities of ≈ l mL−1 and the water must be changed at least 3× wk−1 in static cultures. Water must be changed at least weekly in tanks holding adult brood stock. Methods of controlling protozoan and rotifer infestation of cultures are also important for successful culture.

In reviewing studies of trace metal uptake over the last 30 years, evidence is sought for specific mechanisms controlling transepithelial metal uptake or loss, and their possible relationship with pumps controlling the regulation of physiologically-important electroytes. There is evidence of zinc regulation in some crustaceans. However, the widespread occurrence of specific transepithelial regulatory mechanisms for trace metals is unlikely. Metal uptake and toxicity is often negatively associated with salinity. Although this phenomenon is probably related, in part, to trace metal speciation, an associated calcium effect is seen in some species. Several examples exist of interactions between calcium regulation and trace metals, suggesting there may be a number of shared pathways. Cadmium is particularly implicated in this regard. Inhibition of NaK ATPase by trace metals is seen in some fish, although there is no direct evidence of competitive inhibition of transepithelial sodium movement by trace metals.

Hemolymph sodium, potassium and calcium concentrations were determined in crayfish (Orconectes propinquus) exposed to 203HgCl2 mixed with food to a concentration of 1 μg Hg g−1. Dummy-fed animals were exposed to Hg-dosed food wrapped in dialysis tubing to control for mercury reaching the animals via leaching from food to water. Hemolymph analyses were made following 14-day Hg exposures and again after a further 21-day ‘depuration’ period during which all animals were fed Hg-free food. After 14 days, the mercury reached a concentration of 0·175 μg g−1 in the hepatopancreas and approximately half this level in the gills of Hg-fed animals. No depuration occurred from the hepatopancreas although the gills lost approximately two-thirds of their labelled mercury during the depuration period. Hemolymph sodium concentrations in Hg-exposed crayfish, both fed and dummy-fed, after 14 days were significantly lower than in Hg-free controls and remained low following the 21-day depuration period. Hemolymph calcium concentrations were lower in Hg-fed animals than in dummy-fed and control animals after 14 days although calcium levels rose in all treatments after 35 days. This may have been due to the incidence of pre-molt animals in all experimental groups, although the relationship between this and mercury exposure was not established unequivocally. Hemolymph potassium levels showed no differences between treatments.

Trace metal distribution in Chesapeake Bay is dominated by the input from the Susquehanna River, although other inputs include shore erosion, industry, atmospheric deposition (especially for lead and zinc), and municipal wastewater. By most recent estimates the largest point source of metals, Baltimore Harbor contributes little to the main bay and there is only minimal transport of metals out of the northern bay.

Concentrations of unsubstituted polynuclear aromatic hydrocarbons were measured in sediments, Macoma balthica and Nereis succinea at seven Chesapeake Bay habitats to determine animal-sediment bioaccumulation factors. Bioaccumulation factors for both species ranged between 0.2 and 4 for sediments with more than 0.5% organic carbon. Levels of unsubstituted polynuclear aromatic hydrocarbons in animal lipids were directly related to corresponding concentrations in sediment. Coarse grained sediments low in organic carbon content (<0.5%) provided animal-sediment bioaccumulation factors that were much larger than fine grained sediments, and greater than estimations obtained from a thermodynamic model. Bioaccumulation was not related to the hydrocarbon concentrations present in sandy bed sediments.

Copper and cadmium monitoring in Chesapeake Bay sediments indicates that metal contamination exists in nursery areas for striped bass (Moronesaxatilis), which has been in serious decline over the last 17 years. Whole water metal concentrations in one spawning river were within an order of magnitude of published acutely toxic concentrations. Larval striped bass were exposed in the laboratory to copper and cadmium concentrations which were acutely toxic over a 96h period (24 and 19 µg L−1, respectively), and to sub-lethal concentrations of these metals over a three week period. Larvae from acutely toxic metal treatments, sub-lethal metal concentrations and control tanks were analyzed for cadmium and copper and the frequency distribution of metal body burdens was compared with field data. The distribution of copper concentrations in laboratory-exposed larvae was completely within the range of field specimens, and there was considerable overlap in cadmium frequency distributions from laboratory and field larvae. These results together with other published data suggest that environmental metal concentrations in some spawning tributaries of the Chesapeake Bay may pose a threat to striped bass, and the suggestion is made that greater efforts should be made to link laboratory and field toxicological data.

Research Article| April 01 1986 Factors Affecting Trace Metal Accumulation by Chesapeake Bay (U.S.A.) Oysters Crassostrea virginica David A. Wright David A. Wright Search for other works by this author on: This Site PubMed Google Scholar Water Sci Technol (1986) 18 (4-5): 356. https://doi.org/10.2166/wst.1986.0264 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Twitter LinkedIn Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentAll JournalsThis Journal Search Advanced Search Citation David A. Wright; Factors Affecting Trace Metal Accumulation by Chesapeake Bay (U.S.A.) Oysters Crassostrea virginica. Water Sci Technol 1 April 1986; 18 (4-5): 356. doi: https://doi.org/10.2166/wst.1986.0264 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex This content is only available as a PDF. © IWA Publishing 1986 Article PDF first page preview Close Modal You do not currently have access to this content.

Previous studies have shown that metals from the Susquehanna River and the industrial complexes around Baltimore Harbor and Hampton Roads are bioaccumulated in the oysters of Chesapeake Bay. This paper reports two programs, one an intensive study of oysters from mid-bay sites, the other at Swan Point. Individual variability of metals in oyster tissue is reported and the implications of such variability in respect of sample size for monitoring programs discussed.

Hatchery spawned oysters approximately 1% yr old were subjected to starvation stress by exposing them to 1 wm filtered seawater over an 8 wk period.Control (fed) oysters were exposed to unfiltered flowing seawater.RNA:DNA ratios in mantle tissue from fed and starved oysters were monitored throughout, together with shell length, width, height, whole specimen displacement and shell displacement.Wet welght was estimated from whole weight determinations made before and at the end of the experiment.From Day -4 (before the start of the experiment) to Day 52, there was a 32 % increase in mean weight of fed animals and a 12.6 % loss in wet weight of starved animals.Rate of wet weight growth was significantly less in starved oysters than in fed oysters after Day 3. Shell height increased in fed oysters, but remained more constant in starved specimens.Shell lengths were significantly different from Day 42.Condition index, defined as ratio of wet tissue weight to cavity volume, decreased rapidly in starved oysters and became significantly less than in fed oysters.Two sample t-tests between treatments showed that there was a significant difference in RNA:DNA ratio between treatments on all sampling days except Day 0. By Day 55, starved oysters had 36.5 % lower ratios than fed oysters.Over the 55 day experimental period the RNA:DNA ratio correlated highly with cond~tion index, but was lower in response to starvation than in reported studies on vertebrates.

Copper, zinc, cadmium and silver analyses were made of groups of ca 34 individual oysters taken from 13 oyster bars in the mid-Chesapeake Bay region on the east coast of the United States.Data are described for the years 1978, 1979 and 1981.Sampling stations were chosen to represent high and low salinity regimes as well as sites of potentially differing metal input.Metal concentrations were determined on a wet-weight basis and were found to be largely negatively correlated with body weight and with salinity.Data were entered in a multiple regression program which included body weight and salinity as independent variables, and regression equations were used to normalize the metal concentrations.Data indicated localized copper concentration in oysters close to 2 electricity generating stations, although at 1 of these sites the high values could be explained in terms of the body weighWsa1init.ymodel.High metal concentrations were also indicated at an oyster bar having stunted animals.Results indicated that the use of oysters to map trace metal input to an estuary can be complicated by extraneous factors such as salinity, but that useful information may still be obtained after normalization to size and salinity.Year-to-year comparison between these data and earlier data indicate that correction for salinity may have to be reset from year to year.

1.1. Regulation of major ionic hemolymph components was studied in Uca pugilator, U. pugnax and U. minax. Both urine and hemolymph were analysed, although urine samples were not available from U. pugnax.2.2. In all three species hemolymph sodium and chloride were strongly hyperregulated below about 85 and 75% sea water respectively. At higher sea water concentrations these ions were hypoionically regulated, although sodium regulation in U. minax was not as strong as the other two species. Hemolymph osmotic pressures followed major ion concentrations.3.3. Hemolymph potassium levels in U. minax and U. pugilator were hyperregulated below 100% sea water, with a tendency for higher potassium levels in U. pugilator.4.4. Calcium levels were subject to greater variability than other ions although in all three species the hemolymph remained hyperionic to the external media over almost the entire experimental range. Only in U. pugnax did the hemolymph calcium concentration coincide with that of the external medium in concentrated sea water.5.5. Sulphate was hyporegulated by all species over an externally concentration range of 8–40 mmol SO4C−1 (ca 25–125% SW). Hemolymph sulphate levels were similar in the three species, reaching 45–65% of the external medium in concentrated sea water. High urine sulphate levels emphasized the importance of the antennary gland in regulating this ion in concentrated sea water.6.6. Magnesium was regulated in a similar manner to sulphate although U. minax was apparently more effective at hyporegulating this ion than the other two species. U. minax was also capable of hyper-regulating magnesium in very dilute media.7.7. No major differences in ionic regulation were found between the three species studied.

Thermal tolerance was tested in cleavage stages, trochophores and straight hinge larvae of the bay scallop Argopecten irradians.Experiments were des~gned to simulate larval entrainment in power plant coollng systems.An 11 (temperature) X 8 (time) matrix was used with temperatures ranging from 20.6 to 43.0 "C and exposure times from 1 min to 6 h.Pooled mortality data from triplicate experiments for each larval stage were subjected to stepwise regression analysis (darcsine 90 mortality on temperature and time).Equations derived from these analyses, comprising first, second and third order terms for temperature and time, were used to generate response surfaces relating mortality to temperature and exposure time.In general, higher mortalities were associated with higher temperatures and with longer time exposure at any one temperature.However, there was some evidence of cold shock in trochophore and straight hinge larvae, with elevated mortalities occurring at temperatures lower than the spawning temperature.There was a trend towards increased thermal tolerance in older larvae, although in general A. irradians showed the greatest sensitivity to thermal shock of the estuarine bivalves so far tested in our laboratory.

Inhibition of polyspermy is a critical response during fertilization which ensures that only one sperm nucleus will fuse with the female pronucleus to restore the diploid state. Oyster (Crassostrea virginica) eggs prevent polyspermy by a process occurring at the cell surface. However, 5 min after fertilization, there are still functional sperm receptor sites available for penetration by supernumerary sperm. Reinsemination experiments indicate that there is no decrease in the number of penetration sites during this interval. Yet, the number of sperm entering eggs is restricted to one per fertilized egg at a sperm:egg ratio of 1000:1. At a sperm:egg ratio of 10(5):1, an average of only six sperm were able to penetrate each egg. Gamete binding experiments indicate that there is a gradual decrease in the number of sperm bound to eggs starting at approximately 75 sec and continuing until all sperm are detached. Since eggs are fertilized within seconds of insemination and this process takes at least 12 min, it is considered an unlikely mechanism for the polyspermy block. There are no ultrastructural correlates to the polyspermy block nor to the unbinding of sperm, such as secretion of cortical granules or fertilization envelope formation. Based on reinsemination experiments, kinetic data, and ultrastructural observations, we suggest a physiological block to polyspermy which prevents fusion of gamete plasma membranes, and is mediated by an inhibitory effect directly upon the sperm.

Seasonal measurement of zinc levels in mussels (Mytilus edulis) from the Tyne estuary showed a small spring peak and an annual low in September. Zinc concentration was found to be significantly lower in gonadal tissue than in nongonadal tissue. Although gonadal dry weight was strongly negatively correlated with gonadal zinc concentration there was no significant relationship between gonadal dry weight and whole body zinc levels, indicating that gonadal state has little effect on zinc variability in these animals. However, a strong negative correlation was found between log gonadal zinc concentration and log nongonadal dry weight. Construction of a gonadal index (gonadal/nongonadal dry weight) shows that the seasonal peak zinc concentration in early May occurs before major spawning has taken place. It is concluded that the seasonal dynamics of zinc in this species can be explained in terms of growth of somatic rather than germinal tissue.