MACROINVERTEBRATE COMMUNITIES OF THE DOUBS RIVER PRIOR TO COMPLETION OF THE RHINE-RHONE CONNECTION

The Rhine-Rhone connection project concerns the part of the Doubs Rive r between Montbeliard and Dole (France), i.e. downstream from the conf luence of the Allan River. In order to update our knowledge of the ben thic macroinvertebrate communities of the Doubs River, three types of aquatic environments of this hydrosystem were sampled (main channel, b ackwaters and the Freycinet canal). Hydraulic characteristics are the most explanatory environment variables of lotic macroinvertebrate dist ribution of the Doubs hydrosystem. The aquatic fauna of the Doubs Rive r is varied due to the diversity of biotopes, microhabitats and curren t velocities. The lotic aspect is well defined. Rheophilic taxa are pr esent in the main stream in riffle areas or located downstream from we irs where the current velocity is rapid (> 75 cm s(-1) physics of flow ('stream hydraulics') create the richness of habitats and thereby the biological diversity. Backwaters have a relatively high richness, sim ilar to that of stations in the main stream located in the same sector . Conservation management must be oriented towards the present ecologi cal situation of the Doubs River, i.e. that of a lotic ecosystem with active connections with its backwaters. The primary goal from a conser vation perspective must be the maintenance and the improvement of area s highly sensitive to disturbances.