Assessment of the bioindicator capacity of aquatic macrophytes using multivariate-analysis

International audienceThe aquatic vegetation of twenty one streams, located at the head of watersheds and representative of the geological diversity of the Lorraine, was analysed with regard to its environmental descriptors (geology, morphometry and water chemistry). A Principal Components Analysis was carried out on the data (230 stations and 134 variables), using 40 active chemical and morphometrical variables. This procedure was followed by a Hierarchical Ascending Classification for grouping the variables into classes. The analysis of the mesological and chemical structures of the streams indicated the dominance of geochemical parameters compared to pollution parameters. The indicator capacity of several species was revealed, e.g. Scapania undulata for weakly mineralized, oligotrophic waters; Potamogeton pectinatus for eutrophicated waters and Ranunculus fluitans for high nitrate levels. Five species groups characterizing the geology and mineralization as well as the perturbations in the quality of the water or the environment were identified (e.g. pollution, eutrophication, reposition and reshaping)