Imposex and accumulation of organotin compounds in populations of Hexaplex trunculus (Gastropoda, Muricidae) from the Lagoon of Venice (Italy) and Istrian Coast (Croatia)

Imposex, namely the superimposition of male characteristics, such as penis and vas deferens, on females of gonochoristic gastropods is one of the most harmful effects of TBT on marine organisms. The development of such malformations on marine organisms have led to limitations in the use of TBT in antifouling paints in several countries. Regulation 782/2003 by the EU prohibits the application of organotin compounds. However, in other non EU Mediterranean countries, such as Croatia, the IMO convention has failed to be transposed into domestic legislation and TBT-based antifouling paints are still used. Different restrictions to TBT use and, consequently, likely different levels of TBT contamination between Italy and Croatia gave the cue to this work, whose aims are: (a) monitoring organotin compound levels and imposex degree in Hexaplex trunculus, a common gastropod in the Mediterranean Sea, and an exhibitor of imposex; (b) assessing the level of organotin compounds build-up in the visceral coil and in the rest of the soft body (ROSB) of this organism, in order to try to understand how H. trunculus metabolizes these pollutants; (c) investigating the relationship between organotin compound concentrations in tissues of H. trunculus and the level of imposex development. The results indicate that the incidence of imposex is still high in Italy (Lagoon of Venice) after more than 10 years from the ban of TBT-based antifouling paints. The sampling in Croatian coasts indicates that the absence of restrictions on the use of TBT is likely to cause very high levels of OTC contamination.