Factors affecting trace metal accumulation by estuarine oysters Crassostrea virginica

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Abstract
Cu, Zn, Cd and Ag analyses were made of groups of .apprx. 34 individual oysters taken from 13 oyster bars in the mid-Chesapeake Bay [Virginia and Maryland] region on the east coast of the USA. 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 Cu 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 weight/salinity model. 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.