Accumulation of cadmium by larvae and adults of an Hawaiian bivalve,Isognomon californicum,during chronic exposure

Larvae and adults of an Hawaiian bivalve, Isognomon californicum, were exposed to sublethal, environmentally realistic concentrations of cadmium (2 and 20 ppb) for 28 d, and the accumulation of cadmium was evaluated. The concentrations of cadmium were expressed in terms of total cadmium (tissue and shell concentrations combined) and tissue cadmium. The accumulation rates of larvae were one to two orders of magnitude greater than adult rates. This study suggests that the faster uptake rates of larvae may explain why larvae are more sensitive than adults. Furthermore, the magnitude of differences between larval and adult accumulation rates may be related to metabolic rate. When larvae and adults were exposed to cadmium for only 14 d, followed by a 14 d depuration period, a substantial loss of cadmium was observed during the depuration period. Possible accumulation mechanisms and their similarity between larvae and adults are discussed.