Fish ecological assessment of an Austrian impoundment (HEPP Freudenau, Vienna) with cluster and discriminant analysis implicating dominances after Tischler (1949)

Abstract

According to the demands of the European Union Water Framework Directive, natural structures and habitats were implemented during the construction of the hydropower plant Freudenau. Ecological data were processed and evaluated from the years 1999 to 2000 as well as from the years 2003 till 2004. The study area was divided into five parts, which were further divided into 19 habitats. The statistical software SPSS (© SPSS Inc. 2007) was used for statistical analysis. The dominances after Tischler were calculated and consulted for further analysis. In the context of this project an increase in the number of fish species from 1993 to 2004, showing a peak before and after the power station construction, was demonstrated. The CPUE values proved high magnitudes in the habitats B, D and I. The lowest number of individuals shows the Free Flowing Stretches. Both juvenile and adult fish could be proved in many habitats. A more exact analysis with the dominances after Tischler confirmed previous results. Nevertheless the change in the current spectrum of fish species points out interventions to the habitats. Anthropogenically created habitats are only substitutes for natural habitats.