Embryo-larval tolerance of Mytilus galloprovincialis, exposed to elevated seawater metal concentrations—II. Stage-specific fluctuations in sensitivity toward Zn and Cd and their bioaccumulation into veliger larvae

Abstract

Acute intoxication of selected embryo-larval stages of M. galloprovincialis within successive 8-hr exposure intervals by elevated zinc and cadmium seawater concentrations, indicated stage- and metal-specific variations appearing in different proportions in normally developed straight-hinge veliger larvae. Zinc was found to be markedly more toxic than cadmium, particularly within the period of early cleavage and blastula stages. Embryos undergoing tissue differentiation and formation of the trochophora stage were substantially more sensitive regarding both metals tested in comparison with later veliger stages. Combined cadmium-zinc toxicity within each exposure interval tested appears to be less than additive, possibly associated with a markedly higher level of induced MT. The ability of developing embryos to concentrate seawater zinc (CF65Zn = 399) was approximately 2.5 times higher than for cadmium (CF109Cd = 160), which may also contribute to the observed difference in their tolerance levels