AQUATIC MACROPHYTE COMMUNITIES AS BIOINDICATORS OF EUTROPHICATION IN CALCAREOUS OLIGOSAPROBE STREAM WATERS (UPPER RHINE PLAIN, ALSACE)

The results cover a statistical analysis of the correlations between aquatic macrophyte communities and chemical parameters (N-NH4, N-NO3, P-PO4, COD, Temperature, dissolved O2, Cl) in unpolluted hard waters (upper Rhine rift valley). This study was based on a table of phytosociological relevés for six plant communities, named A, B, C, CD, D and E. The ecological determinism of the communities were defined from: The study of the seven foregoing physico-chemical parameters for 29 groundwater streams on periodical samples of water. The study of the change with time in the aquatic vegetation after change of the trophic status, confirmed by analysis. The comparative study of the vegetation of the streams and parts of the streams with different trophic statuses but fed by the same groundwater table of the Wurmian Rhine gravels. Analysis of the main components showed the good correlation between the macrophyte communities and the trophy (N-NH4, P-PO4). These six communities were classified according to the trophic scale. Discriminant analysis was used to compare the classification of the phytosociological sequence with that based on the statistical analysis. The authors give a very precise bioindication scale (based on the macrophyte community) for the eutrophication degree in unpolluted hard waters. © 1990 Kluwer Academic Publishers.