The presence of imposex (female snails with male accessory organs) was studied in Costa Rica in the snail Thais brevidentata. Imposex is induced by organotins found in anti-foulant paints, especially tributyltin (TBT). T. brevidentata is commonly found in high densities in the mid-littoral zone of rocky shores. Snails from three Pacific coast sites in Costa Rica were collected for analyses. Two of the sites were located in the same general area in one of the main ports in Costa Rica, Caldera Port. A third site in Culebra Bay is a pristine area in the northern part of Costa Rica with little shipping traffic, and served as the reference site. Imposex was found only in Caldera females (28-30 %), and no imposex was found in snails from Culebra Bay. This is the first report of imposex in Costa Rica, and the first report of imposex in T. brevidentata. Although 30 % imposex was found in the Port area, this is relatively low compared to some harbors in the United States of America and Europe, where 100 % imposex has been reported in other gastropod species. Rev. Biol. Trop. 54 (Suppl. 1): 21-26. Epub 2006 Sept. 30.
Keywords: imposex, organotins, bioindicator, TBT, coastal pollution, Gastropoda, Thais brevidentata, Costa Rica