Macrophytes, hydrology, and aquatic ecotones: a GIS-supported ecological survey

The detection of macrophyte-dependent ecotones, the characterization of different hydrological regimes and aspects of sports fishing activities were the main objectives studied in a backwater system of the River Danube in Austria. The macrophyte survey, a dynamic hydrological model and a socio-economic study were all part of the Austrian Ecotone Project. Conclusions were drawn from this database by GIS thematic map interpretation and overlay techniques. Significant transitions existed between stretches of macrophyte vegetation as far as species number and plant mass are concerned. These transitions can be attributed as macrophyte-dependent aquatic/aquatic ecotones. Some plant species and the structural diversity of the aquatic vegetation were found to be characteristic for backwater reaches with different hydrological regimes. In contrast to a hypothesis worked out earlier in the ecotone project the GIS overlays revealed spatial coincidence between the centres of sports fishing activities and survey stretches with high densities of macrophyte vegetation.