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5D + E - Risk communication + From risk mgnt to sust. mgnt? (MOP/185) A biomarker-based index to communicate the ecotoxic potential of aquatic sites. Chèvre, Nathalie1, Gagné, François2, Blaise, Christian2, 1 EAWAG, Duebendorf, ZH, Switzerland2 Environment Canada, Montréal, Qc, Canada ABSTRACT- The use of biochemical or physiological measurements as indicators of ecotoxicity is under constant development and has the advantage of delineating effects before the appearance of disease. However, these biomarkers are often part of a test battery and it is difficult to integrate them together to gain an overall view of an organism′s health. The aim of this project was therefore to develop an index that could integrate the data derived from a battery of biomarkers for application to both spatial and temporal studies. This index should represent an easy way to communicate ecotoxic potential of aquatic sites. In this study, Mya arenaria clams were collected at different sites along the Saguenay Fjord (Quebec, Canada). Six biomarkers were measured: metallothioneins, DNA strand breakage, lipid peroxidation, vitellin-like proteins, phagocytosis, and non-specific esterase activity in hemocytes. A Biomarker Index was obtained by summing biomarker values expressed in term of classes. Classes were determined by a distribution-free approach derived from the theory of rough sets. The results of the spatial study show that the index values discriminate well between contaminated and uncontaminated sites. The highly polluted sites had the highest index values (18 compared to 14 for the reference value). In the temporal study, the index was also able to highlight possible contamination-induced alterations, even though the interpretation of temporal variation is complicated by natural variations occurring throughout the year. A control chart approach is proposed for determining contaminated sites in both the spatial and temporal surveys. Key words: ecotoxicity, aquatic sites, index, biomarkers |
