Development of a river continuity concept using the example of the River Ruhr catchment, Germany

Migratory obstacles (about 12.500 in North Rhine Westphalia) and hydropower plants have a significant impact on aquatic ecosystems. They interrupt the linear continuity of river systems as well as the lateral connection of secondary and meadow waters for fish and aquatic invertebrates. This leads to affected biological communities and a more or less pronounced decline of fish populations as well as a shift in the species composition. Therefore the preservation and restoration of Europe's endangered migratory fish species and habitats are of high priority within the international river basin policy agenda.

Within the program "Future Water" an innovative approach for assessing the ecological continuity of a river catchment will be developed. As a first step, the habitat suitability for the River Ruhr catchment area for different fish species is modelled by using the SDM Software "MaxEnt". To ensure a transferability to other catchments, only public available hydromorphological variables (single and main parameters of the state-wide hydromorphological survey) are used. In the further course of this project the model “FIDIMO” will applied for the study area and optimized in the field of ecological continuity. By combining both habitat suitability and species dispersal maps existing barriers will be prioritized in terms of the achievement of habitats.