Imposex and tributyltin contamination as a consequence of the establishment of a marina, and increasing yachting activities at Phuket Island, Thailand

The objective was to investigate how tributyltin (TBT) contamination resulting from the establishment of a new marina and increasing yachting activities at Phuket Island, Thailand affects the area. A minimum of 30 specimen of the mangrove dwelling muricid Chicoreus capucinus were collected at five stations 2 months before and 5, 9, 18 and 33 months after Yacht Haven Marina was constructed. Imposex measured as RPLI and VDSI were significantly correlated to duration of time after construction and distance from the marina. All females developed imposex close to the marina after 18 months, whereas no significant increase occurred at stations more than 2 km from the marina. To evaluate the range of effects of the increasing yachting activities the muricid Thais distinguenda was used as an indicator of imposex at two popular mooring sites for yachts at Phi Phi and Raja Island in Phangna Bay, Thailand. The incidence of imposex was 100% at stations close to the mooring sites. A significant correlation existed between the distance from the sites and the incidence of imposex. The increasing incidence of imposex suggest that TBT contamination is worsening, against global trends, because regulations prohibiting the use of TBT-based paints, do not exist in Thailand.