Sexual maturation as a source of variation in the relationship between cadmium concentration and body weight of Mytilus edulis L.

In order to refine the utilization of Mytilus edulis as a pollution indicator species, the relationship between cadmium concentration and mussel body weight was investigated at different sites in the Estuary and Gulf of the St. Lawrence. Our data show that the regression coefficients become considerably more variable when animals enter adulthood and that 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 thereby give a more precise indication of ambiant pollution levels.