SILVER AND COPPER ACCUMULATION IN 2 ESTUARINE BIVALVES, THE EASTERN OYSTER (CRASSOSTREA-VIRGINICA) AND THE HOOKED MUSSEL (ISCHADIUM-RECURVUM) IN THE PATUXENT RIVER ESTUARY, MARYLAND

In order to assess the source of trace elements and to compare uptake between different bivalve species, oysters and mussels were transplant ed to five sites in the upper Patuxent River estuary during 1988. Tran splant sites were located above and below the discharge of Chalk Point Steam Electric Station (CPSES)-a historic point source for copper. Or ganisms were sampled approximately monthly for 1 yr and analyzed for c opper and silver. During spring and summer, concentrations of silver a nd copper increased in oysters at the upstream stations. There was ver y little change in silver and copper concentrations in the mussels wit h either time or among stations. Copper concentrations accumulated by oysters approached those found during previous periods when CPSES used Cu-Ni alloy condenser tubes (1966-1987), suggesting that corrosion fr om the Cu-Ni condenser tubes was only a minor contributor to the coppe r burdens of oysters in the river nearby. The lack of accumulation by mussels at the same sites suggests that part of the reason for the acc umulation by oysters may be a taxonomically specific physiological eff ect caused by the salinity regime in the upper Patuxent.