Embryotoxicity of butyltin compounds to the sea urchin Paracentrotus lividus Lmk.

Tributyltin (TBT) has been widely employed in marine anti-fouling paints as a biocide, although it represents a serious risk, particularly in estuarine and coastal water/sediment ecosystems. In this study, the embryotoxic e€ects of TBT and its degradation products, dibutyltin (DBT) and monobutyltin (MBT), were analyzed during the development of the sea urchin Paracentrotus lividus from post-fertilization to the pluteus stage, to better clarify eco- toxicological impact. The embryotoxicity of butyltins is concentration-dependent and increa- ses proportionally with number of butyl groups. Signi®cant growth reduction was observed at TBT concentrations as low as 0.01 mg lÿ1; 1 mg lÿ1 was the maximum concentration allowing embryos to reach the pluteus stage at 48 h post-fertilization. Development was blocked at the morula or blastula stage with higher TBT concentrations. DBT and MBT are less toxic: slo- wed development and a decrease in pluteus size occurred at 10 mg lÿ1 DBT and 0.5 mg lÿ1 MBT. E€ects on both skeletal deposition and blocked embryonic development are suggested to be due to the interference of organotin compounds with intracellular calcium homeostasis.