Biological impact of organotin compounds on mollusks in marine and freshwater ecosystems

Organotin compounds, like tributyltin (TBT) and triphenyltin (TPT), degrade only slowly in the environment. Today, TBT is known to evoke a variety of effects in animals, even at very low environmental concentrations. In terms of sensitivity, none rivals that of two virilisation phenomena-intersex and imposex-in prosobranch gastropods. The effects of TBT and TPT on various marine and freshwater snails were investigated in newly developed sediment biotests in the laboratory. Most tested species showed very low effect concentrations for both organotin compounds (e. g. the freshwater mudsnail Potamopyrgus antipodarum with an EC10 of 0.03 μg TPT as Sn/kg and 0.98μg TBT as Sn/kg for the reduction of fertility). In order to assess the actual TBT contamination of coastal sediments, extensive surveys were carried out in France and Ireland, indicating that there is still a continuing threat for sensitive marine organisms. To obtain information on the contamination of fluvial and estuarine sediments in Germany, an effect monitoring was conducted using the biotests with the netted whelk Nassarius reticulatus and P. antipodarum. From our investigations we may conclude that a variety of benthic mollusks is strongly affected by low concentrations of organotin compounds in aquatic ecosystems. Due to their persistence in the environment, a continuing impact on aquatic wildlife has to be expected