Lead Accumulation in Soft Tissues and Shells of Asiatic Clams (Corbicula fluminea)

Abstract

Bivalves bioaccumulate metals and are useful as sentinel organisms for assessing the bioavailability of metal contaminants in aquatic ecosystems. Frequently, tissue metal concentrations are used by environmental monitoring studies to evaluate potential exposure and effects scenarios. However, bivalves may accumulate certain metals, such as lead, to a significant extent in shells. The purpose of this study was to evaluate the uptake and distribution of lead in the Asiatic clam (Corbicula fluminea) to determine the utility of using shell lead concentrations in environmental monitoring studies. Clams were exposed to lead (5 and 10 mg/L) in a static-renewal system for three weeks. Tissue (adductor muscle and foot) and shell lead concentrations were quantified by atomic absorption spectroscopy after three weeks of exposure and one week post-exposure. Lead accumulation in shells and tissues increased with increasing exposure concentrations. Lead accumulation in shells was approximately 76 to 89% greater than accumulation in adductor muscle tissue and 48 to 70% greater than accumulation in foot tissue. Furthermore, shell lead concentrations were not altered in depurated clams. Together, these data indicate that shells represent a primary storage site for lead in Asiatic clams and suggest that shells may represent a valuable biological material to sample in environmental monitoring studies when lead is a contaminant of concern.