Chromium uptake and loss in the bivalves Crassostrea virginica and Mytilus edulis

Abstract

Cr uptake and loss by the bivalves C. virginica and M. edulis were studied at naturally occurring seawater temperature and salinity to determine their potential as an indicator of Cr pollution. After 12 wk treatment with 5 and 100 ppb Cr seawater, mean tissue concentration in oysters, C. virginica, was 3.12 .+-. 0.45 and 5.63 .+-. 1.15 .mu.g Cr g-1 dry weight, respectively. Mean Cr concentration in mussels, M. edulis, treated with 5 and 10 ppb Cr seawater for 12 wk were 4.83 .+-. 1.32 and 9.41 .+-. 3.37 .mu.g Cr g-1 dry weight, respectively. Significant linear relationships exist between Cr uptake by oysters and mussels and seawater Cr concentrations over the range of concentrations used in this study. A significant inverse relationship exists between tissue Cr concentration and dry wt in both oysters and mussels. Cr concentration in oysters continued to increase during spawning, whereas it decreased in mussels. After holding Cr treated mussels in ambient flowing seawater for 28 wk, a 61 and 70% loss of Cr occurred in mussels treated with 5 and 10 ppb Cr, respectively. When treated similarly, oysters from both the 5 and 10 ppb Cr treatments lost 42% of their tissue Cr after 28 wk depuration. Evidence is presented which suggests that oysters would be a better indicator of Cr pollution of the environment than mussels.