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Browsing by Author "Belanger, Scott E."

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    Functional and pathological responses of selected aquatic organisms to chrysotile asbestos
    Belanger, Scott E. (Virginia Tech, 1985-09-01)
    Functional and pathological responses of larval, juvenile, and adult Asiatic clams (Corbicula sp.), juvenile and adult fathead minnows (Pimephales promelas), and egg, larval and juvenile Japanese Medaka (Oryzias latipes) to chrysotile asbestos were investigated in 96-hour to 91-day tests. Chrysotile significantly reduced siphoning activity and shell growth of adult clams and siphoning, shell growth, and weight gain of juveniles at 10⁵ fibers/liter during 30-day tests. Larval Corbicula suffered significantly greater mortality and lower release by brooding adults at 10²-10⁸ fibers/liter. Adult and juvenile Corbicula exposed to 10⁸ fibers/liter for 30 days exhibited deteriorated gill tissue and significantly greater tissue water content. Corbicula accumulated up to 1000 fibers/mg in visceral tissue at 10⁸ fibers/liter. Clams collected from the California Aqueduct System exposed to 10⁹ fibers/liter accumulated up to 10⁵ fibers/mg in viscera. Corbicula can be used as a monitor for chrysotile contamination due to its ability to concentrate fibers. Adult and juvenile fathead minnows did not suffer acute toxicity at 10¹² fibers/liter and differential mortality relative to controls up to 10⁸ fibers/liter for 30 days. At the conclusion of the 30-day tests the length, weight, and swimming performance of adult minnows exposed to asbestos were not significantly affected relative to controls. Juvenile minnows exposed to 10⁶-10⁸ fibers/liter had significantly lower weight. Fish exposed to 10⁸ fibers/liter for 30 days accumulated up to 390 fibers/mg in kidney tissue. Egg and larval Medaka were exposed to 0-10¹⁰ fibers/liter of chrysotile until hatching and for thirteen weeks, respectively. Eggs responded erratically to asbestos exposure and no conclusive trends could be drawn. Larval Medaka exposed to 10⁶-10¹⁰ fibers/liter had reduced growth by 14 days. Fish exposed to 10¹⁰ fibers/liter suffered 100% mortality by 60 days. Fish exposed to asbestos developed epidermal tumors, thickened epidermal tissue, increased mucous cell density in the intestinal tract, constricted kidney tubules, and abnormal levels of lipid and endoplasmic reticulum in the liver. Maximum asbestos uptake occurred in fish exposed to 10⁸ fibers/liter for 91 days (400 fibers/mg). The extent of damage to fish and clams at levels greater than 10⁴ fibers/liter in the laboratory suggests that aquatically transmitted asbestos is a potential hazard to these species in the field.
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    Toxicological, physiological, and behavioral responses of the Asiatic clam, Corbicula sp., to biocidal and copper perturbations
    Sappington, Keith Gordon (Virginia Tech, 1987-09-15)
    Experiments were conducted on the effectiveness of exposure to simultaneous temperature shock with chlorination, monochloramine, and ammonia as control agents of the Asiatic clam, Corbicula sp. Control procedures were evaluated based on lethal and sublethal responses (e.g., glycogen, tissue water, dry weight index, and siphoning activity) of clams during 30-day laboratory artificial stream studies. Studies also were conducted comparing sublethal responses (e.g., glycogen, tissue water, soluble protein, and siphoning activity) of clams to copper, a component of power plant effluents, during 30-day laboratory, site-specific, and in-situ copper exposures. This was done to evaluate the use of the Asiatic clam as a biomonitoring organism of copper contamination. Regarding temperature and chlorine interactions, it was demonstrated that an increase of 10° C was needed to increase significantly adult and juvenile mortality in the presence of chlorine (0.30 mg/l TRC) during winter and summer. Naturally high temperatures also increased adult mortality during in-plant chlorination procedures, with the highest mortality occurring during the spring. Significant decreases in the dry weight condition index were observed for adults chlorinated at 5° increases during winter and at 10° C increases for control (non-chlorinated) clams during both winter and summer. Similarly, glycogen content responded with a temperature-dependent decrease in both control and chlorinated clams during the summer. In addition, exposure to increased temperatures significantly increased the siphoning activity of control adults during summer and juveniles during winter. Chlorinated clams experienced near total inhibition of siphoning activity at all temperatures tested, except for adults exposed at 33° C. Increased dsiphoning activity, decreased glycogen content, and possibly ammonia accumulation in the mantle cavity were believed to be responsible for the increased mortality of clams chlorinated at higher temperatures. Total residual chlorine, with < 90% as monochloramine, was found to be equally toxic to adults and more toxic to juveniles compared to total residual chlorine containing higher amounts of free residual chlorine. Since free residual chlorine is considered to be more toxic than combined residual chlorine (e.g., monochloramine), questions were raised as to which form of chlorine was actually exposed to the tissues of adducted Asiatic clams. Ammonia was considerably less toxic to adults but more toxic to juveniles compared to chlorine. Both monochloramine and ammonia caused significant reductions in clam glycogen content and siphoning activity. The siphoning activity of clams exposed to ammonia, although significantly reduced, was considerably higher than siphoning activities observed for monochlorinated and chlorinated clams. Clam tissue water content decreased in the presence of ammonia but remained unaffected in the presence of monochloramine. Ammonia toxicity to adult clams was highly pH dependent but may be useful in controlling larval stages of Asiatic clams. More definitive research is needed to evaluate fully the potential of monochlorination as a biofouling control agent. Clams were more sensitive to copper exposures, with respect to glycogen content, in field-located (i.e. site-specific) artificial streams than in laboratory artificial streams. Specifically, the "no observable effect concentration" was between 5.5 and 8.4 μg Cu/1 during the 30-day site-specific studies compared to 17.2-32.1 μg Cu/1 in the laboratory. Copper significantly increased clam tissue water content during the Clinch River and June site-specific studies. However, clam soluble protein content demonstrated no consistent dose-dependent response during the laboratory or site-specific studies. Glycogen and tissue water content, although subject to some seasonal influences, are recommended for use in Corbicula for future site-specific and in-situ long-term toxicity experiments.