Comparison of imposex response in three Prosobranch species

A comparison of the intersex responses of Nucella lapillus, Ocenebra erinacea and Hinia (Nassarius) reticulata L. showed that Nucella was the most sensitive to tributyltin (TBT) and Hinia the least sensitive. Two imposex indices were calculated: Relative Penis Size Index (RPSI) and Vas Deferens Sequence Index (VDSI). Of these only VDSI showed good interspecies correlations. Nucella and Ocenebra were useful test species at TBT concentrations below 2 ng tin per litre while Hinia was more appropriate for higher TBT levels. At higher levels of pollution, none of the species examined was appropriate since imposex reached its maximum. The 2 sterilized Hinia females indicated that there was a limit to the resistance of this species to TBT-induced sterilization. This sterilization did not seem to be due to proliferation of vas deferens tissue in the vaginal opening. Studies using Nucella showed that the use of narcotization in imposex analysis led to an underestimation of RPSI compared with non-narcotization methods.