Hinia reticulata and Nucella lapillus. Comparison of two gastropod tributyltin bioindicators

Hinia reticulata and Nucella lapillus (collected from 1989 to 1991 at Pointe de Pléneuf and Méan Mélen, France, respectively) exhibit imposex in response to tributyltin (TBT) pollution leached from antifouling paints and proved to be good TBT bioindicators. H. reticulata was kept for 18 mo under TBT-free conditions in the laboratory, but no evidence for imposex remission was found. A second series of experiments showed that food chain uptake of TBT from a contaminated diet is an important mode of TBT exposure in H. reticulata. Comparative tank experiments with H. reticulata and N. lapillus demonstrated that the same type of TBT exposure resulted in comparable TBT body burdens, biological concentration factors, and imposex development in both species measured as increase of VDS (vas deferens sequence index), uncubed RPS (relative penis size index) and average female penis length]. Differences in imposex development of natural and laboratory populations are discussed against the background of different types of TBT contamination of their food. A statistical study, based on an analysis of natural populations of both prosobranch species, makes a comparison of the specific TBT sensitivity of the two bioindicators possible. As a consequence it is proposed that TBT biomonitoring programs in Europe should use both prosobranchs as indicator species.