ACCUMULATION OF ORGANOTIN COMPOUNDS IN THE COMMON WHELK BUCCINUM-UNDATUM AND THE RED-WHELK NEPTUNEA-ANTIQUA IN ASSOCIATION WITH IMPOSEX

Several species of the subclass Prosobranchia are considered to be sui table organisms for monitoring long-term effects of triorganotin (TOT) compounds. This study utilized Buccinum undatum and Neptunea antiqua from the North Sea and the Irish Sea. Morphological alterations in the genital system (imposer phenomena), the histological structure of the gut, and the gonads were studied. TOT concentrations in soft body tis sue and shells were determined. Females of both species displayed impo sex phenomena (pseudohermaphroditism). The percentage of altered femal es per station ranged from 0 to 90% in B. undatum and from 0 to 29% in N. antiqua. Imposer index values in B, undatum reached 1.09 near Helg oland and 0.86 in N, antiqua sampled at 25 nautical miles from the Sco ttish northeast coast. Organotin compounds were detected in the soft b odies of snails from all stations. A chi-square analysis revealed a si gnificant correlation between imposer stages and TOT concentrations in B, undatum but not in N. antiqua. Tributyltin (TBT) in B. undatum ran ged from 1.0 to 15.9 ng g(-1) wet weight (Irish east coast). TBT conce ntrations in N, antiqua were higher and ranged from 2.2 to 25.7 ng g(- 1). In both species, organotin compounds in the shells were below dete ction Limits. Despite high TBT concentrations in soft tissues and the occurrence of imposer (offshore and inshore), female gonads were in go od shape and no signs of limited reproductive capacity were found. His tological findings indicate that TBT does not contribute considerably to mortality in the common whelk.