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

Abstract

Chromium uptake and loss by the bivalves Crassostrea virginica and Mytilus edulis were studied at naturally occuning seawater temperature and salinity to determine their potential as an indicator of chromium pollution. After 12 wk treatment wlth 5 and 10 ppb Cr seawater, mean tissue concentration in oysters, C. virginica, was 3.12 -+ .45 and 5.63 + 1.15 pg Cr g-' dry weight, respectively. Mean chromium concentration in mussels, M. edulis, treated with 5 and 10 ppb Cr seawater for 12 wk were 4.83 + 1.32 and 9.41 f 3.37 vg Cr g-' dry weight, respectively. Significant linear relationships exist between chromium uptake by oysters and mussels and seawater chromium concentrations over the range of concentrations used in this study. A significant inverse relationship exists between tissue chromium concentration and dry weight in both oysters and mussels. Chromium concentration in oysters continued to increase during spawning, whereas it decreased in mussels. After holding chromium treated mussels in ambient flowing seawater for 28 wk, a 61 and 70 % loss of chromium 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 chromium after 28 wk depuration. Evidence is presented which suggests that oysters would b e a better indicator of chromium pollution of the environment than mussels.