Accumulation and depuration of organic contaminants by the American oyster (Crassostrea virginica)

Oysters and other bivalves are widely used to assess the levels of environmental contamination; however, very little actual field calibration of bivalves has been done. The purpose of this research, therefore, has been to evaluate the uptake and depuration of selected PCBs and PAHs in transplanted American oysters, Crassostrea virginica, under field conditions in Galveston Bay, Texas. Transplanted oyster were found to bioaccumulate contaminants and reach concentrations nearly equal to those of indigenous oysters for PAHs and low molecular weight PCBs within 30–48 days. In contrast, high molecular weight PCBs did not reach equivalent concentrations. When returned to a clean environment, oysters significantly depurated PAHs and low molecular weight PCBs. There were, however, differences in depuration rates when newly contaminated oysters were compared to chronically contaminated oysters. Oysters are useful tools in biomonitoring studies but have their limitations. Transplant studies help to establish these limitations on the use of oysters as sentinel organisms to avoid misleading interpretation of the oyster contaminant concentrations.