Combined toxicity of mercury, copper and cadmium on embryogenesis and early larval stages of the Mytilus galloprovincialis.

The aim of this study was to investigate the individual and combined toxicity of dissolved copper-cadmium and mercury using the embriotoxicity test with Mytilus galloprovincialis. Adult stocks of Mytilus galloprovincialis were induced to spawn and early larvae were recorded after incubation of fertilized eggs in seawater. The 48h - EC50 for the single metals, ranged from 10 to 590 microg l(-1), with the following toxicity ranking: Hg > Cd > Cu. One-way ANOVA showed that the toxicity of mercury and copper had a significant effect on larval development beginning from the lowest concentration, but there is no significant difference in the mean responses among all concentrations. Cadmium had a significant effect (p < 0.05) already at the lowest concentrations. To identify the kind of interaction in binary mixtures among metals, the additive toxicity index (S) was calculated. All mixtures tested, after 48h, showed an antagonistic response.