Large rivers: the relevance of ecotonal structure and hydrological properties for the fish fauna
Schiemer, F.; Keckeis, H.; Winkler, G.; Flore, L.
Over the past ten years the limnology of large rivers has received considerable attention. Besides the development of concepts concerning the significance of flood pulses and the hydrological connectivity between the river and its flood plain (Junk et al. 1989; Sedell et al. 1989), the application of general ecological theories proves to be of mutual benefit both for the limnological understanding of large river systems and the advancement of the theoretical concepts (e. g. Townsend 1996). Interest in large rivers is not only theoretical but also applied. River regulation and damming have changed the structural properties and hydrologic dynamics of high order rivers strongly in many parts of the world. These impacts not only affected the characteristic biota negatively, but also degraded the potential use of flood plains with regard to various resource utilization, drinking water, forestry and fisheries (Welcomme 1985). The high biodiversity of flood plain ecosystems and their role as a biogeographic corridor and refugia within ecologically depauperated cultivated land makes the conservation of large rivers a burning issue (Angermeier & Schlosser 1995). At present, restoration schemes have been developed for many river systems in order to restore their ecological properties and functions. It is a paramount challenge for ecologists to develop appropriate management procedures based on an understanding of ecosystem processes, community organization, and population dynamics of characteristic species.