The common mussel Mytilus edulis as an indicator of trace metals in Scandinavian waters. II. lead,iron and manganese

An investigation of the mechanisms of detoxication of copper and zinc by the oyster Ostrea edulis (L) has been carried out using naturally occurring green-sick (contaminated by copper) and unpolluted oysters. Electron microprobe X-ray analysis of tissues in the electron microscope gives direct evidence for the structural compartmentation of copper and zinc in separate, specific, granular amoebocytes. The metals are immobilized in membrane-limited vesicles as different chemical compounds, copper being associated with sulphur and zinc with phosphorus. Chemical analyses of serum and tissues of normal and green-sick oysters indicate that (a) Cu and Zn are accumulated independently, (b) the Cu and Zn in the serum, while higher than in the surrounding sea water, are maintained at a 10-fold smaller level than the tissues, (c) toxicity is reduced by active uptake from the serum into granular amoebocytes, where it is further reduced by compartmentation in membrane-limited vesicles. It is calculated that the individual cell types may contain as much as 13,000 ppm Cu and 25,000 ppm Zn.