ABSTRACT: The common marine mussel Mytilus edulis 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 ug l^-1 of cadmium, and assays were carried out to investigate the potential for immune response. The assays included total and differential haemocyte counts, the release of intracellular and extracellular reactive oxygen metabolites, phagocytosis, release of degradative enzymes and uptake of neutral red. Cadmium at 400 ug l^-1 resulted in significantly enhanced numbers of circulating haemocytes and increased uptake of neutral red. No alteration was demonstrated in proportions of circulating haemocyte types, phagocytosis or production of reactive oxygen metabolites. The release of degradative enzymes during phagocytosis was found to be significantly suppressed at the 40 ug l^-1 cadmium concentration. Assays to determine the immune function may provide a sensitive measure of the health status of an individual or population under pollutant stress. However the variability in effects produced in different aspects of immune function emphasises the need for a multi-assay approach to monitoring pollution. The observed effects on immunocompetence, at environmentally realistic levels of contaminant, support the view that a relationship exists between pollution and immunomodulation in aquatic organisms.

KEY WORDS: Mussel . Immunocompetence . Haemolymph . Cadmium

Published in DAO Vol. 22, No. 1 (1995) on May 4
ISSN: 0177-5103. Copyright © Inter-Research, Oldendorf/Luhe, 1995