METHODS FOR BIOLOGICAL QUALITY ASSESSMENT OF THE RIVER RHINE

摘要

The River Rhine is one of the most anthropogenetically stressed ecosystems in Europe. Between 1817 and 1879 the watercourse was already heavily under construction to improve water discharge according to the plans of J. G. Tulla. In the following decades diverse additional engineering measures were performed, with the consequence of an increase of current velocity and intense bottom erosion along the free flowing stretches, and minimization of current in the backwaters of the several newly built dams. Targets were improvement of flood control, generation of hydroelectric power, and shipping traffic, on the price of almost complete lost of the ecological function of the floodplain area. Pollution with diverse inorganic and organic chemical compounds from urban and industrial discharge increased severely in the 50's and 60's of the past century. The ecological quality reached its lowest level in the 60's and 70's. Fish deaths were the order of way. On the experience of the deteriorated river channel (pollution, flooding, local groundwater lowering, ecological impoverishment) intense investments in purification plants on the Rhine and its catchment area were done and proved positive. Restoration aspects for the river and the floodplain were focussed since 1988. Quality and diversity of species of fish and macrozoobenthos has improved visibly. However, in November 1986 a heavy pollution wave, caused by the Sandoz accident, contaminated the Rhine water and riverbed with various insecticides. Particularly the macrozoobenthos was heavily influenced (BRAUKMANN et al. 1987). In consequence of the Sandoz accident biological monitoring of the River Rhine was improved: An international macrozoobenthos monitoring programme in the main stream was established by the International Commission for protecting the River Rhine with an interval of five years, starting in 1990. In addition, regular intensive biocoenotic monitoring of the aquatic community of the upper River Rhine was carried out after the Sandoz accident between 1987 and 1989 in Baden-Wuerttemberg and was continued within a trendbiomonitoring project in running waters starting in 1995 at 100 sampling sites of the main streams Danube, Neckar and Rhine and at the most important of their tributaries in the area of Baden-Wuerttemberg (MARTEN in press a, b). Meanwhile this conception is recommended for monitoring long-term effects of background pollution in aquatic environments in Germany by the 'Laender-arbeitsgemeinschaft Wasser' (LAWA 2000).