WIDESPREAD NEOGASTROPOD IMPOSEX - A BIOLOGICAL INDICATOR OF GLOBAL TBT CONTAMINATION

Imposex (male genitalia imposed on females) in shoreline whelks and other Neogastropod molluscs is reported here from S.E. Asia (Singapore, Malyasia and Indonesia). In Singapore imposex occurred at all sites where females were available. In remote Ambon Bay, Indonesia, imposex also occurred widely, and was particularly severe in two harbours for high seas and inter-island vessels. There was a low incidence of imposex near Port Dickson, a small port in Malaysia. As whelk imposex occurs widely in North Atlantic and Pacific Oceans, we conclude that it is now global not just regionally localized. From the association of Neogastropod imposex with tributyltin (TBT) contamination derived from boat and ship anti-fouling paints, it follows that TBT contamination and its human consequences should be considered a contemporary global threat. We present here an imposex survey protocol for Neogastropod species in general. This should facilitate testing in new regions with new species, and indicate where chemical measures for TBT contamination are needed. © 1990.