L. Forró szerk.: Miscellanea Zoologica Hungarica 13. 2000 (Budapest, 2000)

Spolwind, R., Schludermann, C. , Schuster, A.; Waidbacher, H.: Comparison of fish and amphibian communities in a floodplain system of the rivers Traisen and Danube westwards of Vienna

species, or pooled taxa (Greenfrogs) in the Traisen and Danube-Traisen system. Compared to the results of the fish coenoses, amphibians show higher species numbers and abundances in the Danube-Traisen region, whereas Salamandra salamandra and Rana temporaria are restricted to a few spots in the Traisen areas. In the entire system 60 habitats were classified as amphibian spawning places. Fig. 6 shows the distribution of proven spawning records of amphibians in the two study areas. Habitats with only one species (mainly Rana dalmatina) were dominant in both subsystems, whereas higher species numbers were mainly restricted to the downstream region with its diverse backwater distribution. Areas characterised by higher species numbers are spatially unevenly distributed: they are mostly located in the Danube-Traisen area. Number of species at spawning place Fig. 6. Frequency of spawning places with different amphibian species records Cluster analysis of fish and amphibian data The next step in data investigation was the performance of a hierarchical cluster analysis (after Ward), we used binary data files to investigate fish and amphibian communities in separate ways: In the analysis of fish data only backwater systems with stable fish coenoses were considered, the cluster can be separated in 2 major groups, one group (cluster 1-3) consists of habitats with low species numbers, the second group (cluster 4) includes intact, mostly larger habitats with higher species numbers.