One decade of benthic macroinvertebrate biomonitoring in the River Meuse

Abstract

The benthic macroinvertebrate community of the River Meuse was studied at four locations in Belgium and The Netherlands from 1983–1993. Macroinvertebrates were collected from artificial substrates, placed near the river bottom from June–August. The results were analyzed using autecological information. At an upstream sampling site in the Belgian Ardennes (Hastiere) the most diverse fauna was found. One quarter of the taxa found at this site are known to be confined to running waters and none of the dominant or subdominant taxa could be characterized as a specialized riverine taxon. These findings indicate an impoverished riverine fauna. This was especially the case in years with low discharge, indicating a delicately balanced ecosystem, easily susceptible to disturbances in the environment. Further downstream, in the heavily industrialized region of Liege (Hermalle) and just across the Belgian-Dutch border (Borgharen) the macroinvertebrate fauna consisted of taxa tolerating severe organic pollution. The ecosystem at these sites is on the brink of collapse. Recent results indicate an improvement of this situation at Borgharen. The macroinvertebrate fauna in the lowland reach (Keizersveer) indicates ecological recovery. It is concluded that abatement of the severe pollution must be the first step for an ecological rehabilitation of the degraded ecosystem and for the safe drinking water supply for millions of people in Belgium and The Netherlands.