THE USE OF MOLLUSCS TO MONITOR CADMIUM LEVELS IN ESTUARIES AND COASTAL MARINE ENVIRONMENTS

Abstract

Molluscs are known to accumulate cadmium, an element toxic to man, to levels in excess of those commonly found in marine waters. It is shown that molluscs can be used to monitor cadmium levels in estuarine and other marine environments. The reliability of this type of monitoring is compared with data obtained from standard sediment and water sampling surveys, using as an example studies in two estuaries in the United Kingdom. Cadmium concentrations in the Pacific oyster Crassostrea gigas from these estuaries are quoted, together with concentrations in molluscs from other polluted and unpolluted environments. Suggestions are made as to which of the variety of molluscs occurring around the South African coast might be most useful as monitoring organisms.