Bioaccumulation and toxicity of four dissolved metals in Paracentrotus lividus sea-urchin embryo

The bioaccumulation of four metals (Cd, Cu, Pb, Zn) dissolved in water was assessed measuring the concentrations recorded within sea-urchin larvae (Paracentrotus lividus, Lmk.) after a 48-h exposure period. Concurrently, the frequencies of abnormalities were evaluated at the 48-h pluteus stage to check the actual toxicity of such contaminants with regards to larval development. Maximum metal concentrations in the larvae reached 43.8 +/- 6.7 micrograms Cd g-1 dry weight (d.w.), 1269 +/- 392 micrograms Cu g-1 d.w., 3106 +/- 679 micrograms Pb g-1 d.w., 534 +/- 62 micrograms Zn g-1 d.w. Bioconcentration factors (BCFs) reached very high values for Pb (maximum value: 16,282 +/- 973) and indicated that the concentrations of Pb and Cd were directly related to the water concentration at least in the range of concentrations tested. Zn appeared to be partially regulated above a certain threshold concentration (between 5 and 25 micrograms l-1). Cu was accumulated with an active uptake at least below lethal threshold level (100 micrograms l-1). Nevertheless, above these thresholds, high mortality of embryos prevent any interpretation of Zn and Cu bioconcentration factors. Concurrent studies carried out on embryotoxicity confirmed the high toxicity of Cu towards sea-urchin pluteus larvae and highlighted the different behaviour of Cd. The internal Cd concentrations were directly related to the external ones, comparable to other non-essential metals, but Cd had little toxic effect on the initial larval development.