SEXUAL-MATURATION AS A SOURCE OF VARIATION IN THE RELATIONSHIP BETWEEN CADMIUM CONCENTRATION AND BODY-WEIGHT OF MYTILUS-EDULIS-L

To refine the utilization of M. edulis as a pollution indicator species, the relationship between Cd concentration and mussel body wt was investigated at different sites in the Estuary and Gulf of the St. Lawrence [Canada]. The regression coefficients become considerably more variable when animals enter adulthood and the variations are probably related to biochemical changes occurring during the sexual cycle. A substantial improvement of the applicability of mussels for monitoring marine pollution can be achieved by using only immature animals. This should reduce the influence of metabolism on the metal content of mussels and give a more precise indication of ambient pollution levels.