Alteration of the immune response of the common marine mussel Mytilus edulis resulting from exposure to cadmium

The common marine mussel A4yt~lus edulls was used in laboratory-controlled experiments to investigate the effects of exposure to cadmium on immune capability Haemolymph was extracted from mussels exposed for 7 d to 40 and 400 pg 1 ' of cadmium, and assays were carned out to investlgate the potent~al for immune response The assays included total and differential haemocyte counts, the release of lntracellular and extracellular reactive oxygen metabolites, phagocytosis, release of degradatlve enzymes and uptake of neutral red Cadmium at 400 pg 1 ' resulted In sign~ficantly e nhanced numbers of circulating haemocytes and increased uptake of neutral red No alteration was demonstrated in proportions of circulat~ng haemocyte types phagocytosls or product~on of reactive oxygen metabolites The release of degradative enzymes during phagocytosis was found to be signiflcantly suppressed at the 40 pg 1 ' cadmium concentration Assays to determine the immune funct~on may provide a sensitive measure of the health status of an individual or population under pollutant stress However the variabihty in effects produced in different aspects of llnmune function emphasises the need for a multi-assay approach to monitonng pollution The observed effects on immunocompetence, at environmentally realistic levels of contaminant, support the vlew that a relat~onship exlsts between pollution and ii~~munomodulation In aqudtic organisms