Imposex in the commercial snail Bolinus brandaris in the northwestern Mediterranean

A survey of the degree of imposex in populations of the commercial muricid Bolinus brandaris (L.) was carried out at six locations along the Catalan Coast (NW Mediterranean). Imposex was found to be a widespread phenomenon; the occurrence of a penis was observed in all females studied with the exception of those from St. Carles (South of Catalunya) where only 37% were affected. Other indices such as Relative Penis Length (RPL) and Vas Deferens Sequence (VDS) were applied; RPL varied from 4.5% in St. Carles--the least affected area--to 29.8% in the vicinity of Barcelona; similar results were obtained for VDS. Tissue organotin residues ranged from 6 to 140 ng g(-1) w.w. as Sn. Despite legislation restricting the use of tributyltin (TBT) in antifouling paints, this paper evidences the occurrence of organotin pollution far from the source, with levels of both TBT and triphenyltin (TPhT) high enough to cause environmental concern.