Imposex incidence in Hexaplex trunculus from Kastela Bay, Adriatic Sea

Imposex, a pseudo-hermaphroditic condition characterized by the development of male sexual characteristics in female prosobranch gastropods, is used as a bioindicator of pollution by tributyltin (TBT) -based antifoulants. The incidence and the intensity of imposex, evaluated from the vas deferens sequence index (VDSI) and the female penis length (FPL), were investigated in Hexaplex trunculus populations from seven locations in Kastela Bay (Adriatic Sea, Croatia). Analysis of 131 females revealed the absolute prevalence of imposex at all investigated locations. Furthermore, most of the females showed signs of advanced imposex development (VDSI=4.4 plus or minus 0.8, range=2-5). Female penis homologues were found to be well developed (max=20 mm) with mean values ranging from 5.2-12.6 mm. Significant differences were detected regarding both the VDSI (H=36.24, p