Trace metal concentrations in relation to season and gonadal maturation in the oyster Crassostrea iridescens

The gonadal development and the concentrations of six trace metals (Cd, Cu, Fe, Mn, Ni and Zn) associated with the gonadal and somatic (nogonadal) tissue throughout the reproductive cycle of the oyster Crassostrea iridescens (Hanley) have been studied. The metal concentration in this oyster in both tissues exhibited significant seasonal variations. The minimum Cd, Cu, Fe, Ni and Zn concentrations in the gonadal tissue are related to periods of maximum gonadic development. In contrast, Mn shows a maximum in the gonad and whole tissue that is correlated positively with the maturation of the organism. This last result suggests that Mn may perform some function during the gonadic maturation or prespawning. In addition, this element (in somatic and whole soft tissue) was correlated negatively with body size. A general conclusion is that the reproductive state and body size in C. iridescens exerts an important influence on the accumulation (and variability) of these trace metals, which may influence interpretations with respect to low chronic or short-term contamination.