Compared sensitivity of species, genera and families of Molluscs to biodegradable pollution

A scale of sensitivity of mollusc species to biodegradable pollution was pr oposed in a previous paper (Mouthon 1996). Using these results as a basis, and introducing supplementary elements in a correspondence analysis, we hav e been able to formulate a scale of sensitivity of mollusc genera and famil ies. A quantification of information lost when using genus or family-level rather than species-level identification was carried out by calculating the Euclidean distances between each species and the gravity centre of the gen us and family to which it belongs. The results obtained showed that the gen us-level identification can constitute an acceptable compromise for using m olluscs as water quality indicators in biomonitoring.