Imposex in Sublittoral and Littoral Gastropods from the Gulf of Thailand and Strait of Malacca in Relation to Shipping

Abstract

Abstract The study aimed to survey the presence and extent of imposex in sublittoral gastropods in relation to shipping traffic in the Gulf of Thailand and the Strait of Malacca. Females of several species of meso- and neogastropods showed a high incidence (up to 100%) of imposex at several sites. These females had a penis of variable size and a vas deferens (sperm duct), two typically male characteristics. Imposex has been found to be caused by TBT from antifouling paints. The occurrence of imposex was related to the distance to the main shipping routes, but not to water depth or diet of the investigated gastropods. TBT remains active far away from the target area and influences non-target animals. Some gastropods affected by imposex were found within shellfish culture plots and on the fish markets. Keywords: ImposexsublittoralSouth-East Asianeogastropodamesogastropoda