Mytilus edulis shell as a bioindicator of lead pollution considerations on bioavailability and variability

Abstract

he nacre of Mytilus edulis is introduced as an alternative to soft tissues for trace metal analyses in biological monitoring programs. The lnner nacreous shell and soft tissues of mussels collected near a Pb smelter were analyzed for Pb and compared with the total-Pb content in suspended particulate matter (SPM).The results indlcate that shells can provide an index of Pb bioavailability as the nacre-Pb levels were strongly correlated (p < 0.001) with the tissue-Pb concentrations. Although nacre sequesters ca one tenth of the Pb measured in the tissues, the statistical variability associated with nacre-Pb levels is half that calculated for the tissues. Consequently, nacre-Pb levels offer a compara- tively better relationshp with the SPM Pb-content and also prov~dea significantly better spatial resolution. How other biophysical parameters such as mussel age, size, and littoral zonation may affect mussel Pb concentrations are also discussed.