Biomonitoring of freshwater ecosystems by the use of biological traits

Benthic macroinvertebrates are of common use in bioindication. But global i ndices are not able to diagnose actual causes of damaging. The aim of this study is to integrate recent developments linking biological strategies of animals (reproduction, life duration, feeding habits, respiration) with env ironmental disturbance. This methodology has been applied to the Chalaronne river, a water body rec eiving effluents from a waste water treatment plant. Biocenotic analysis, b ased on abundances of taxa, allows discrimination of upstream from downstre am stations since 17.9 % of the variability is dedicated to it. Functional analysis, based on biological traits, gives a better discrimination of stat ions, since the value is equal to 23.1 %. This study shows that functional structure observed upstream is characteris tic of resilience. On the contrary, functional structure observed downstrea m is characteristic of resistance. A functional approach is interesting for two reasons : first as a mean to d iscriminate stations efficiently, and secondly it is promising in study of biological functionalities of ecosystems.