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

Corresponding to fish data we clustered amphibian species records with a hierarchical cluster analysis after Ward. The result is a diversion into 4 clusters, we used the backwater type and presence versus absence of fish communities as descriptive factors in Table 6. Clustering results seem to be explained best by backwater typology and influencing fish communities in different systems. Fish presence in unstructured systems can lead to the exclusion of heterogeneous amphibian communities; only well structured habitats (present in the Danube-Traisen system) allow real coexistence of diverse fish and amphibian communities. A synopsis of the results of fish and amphibian clusters shows the impact of backwater typology and biocoenotic influences on the distribution of the two vertebrate groups. Fish are significantly grouped in habitats of similar hydrology/typology, whereas the distribution of amphibians is strongly influenced by typology as well as habitat configuration and the presence/absence of fish. Sensitive species as H. arborea are only present in the Danube-Traisen region; habitats without fish or with extensive, shallow inundation areas are strongly preferred. The cluster with the highest case number is cluster 3 with dominance of brown frogs. Especially the common species, R. dalmatina, shows highly frequent occurrence in nearly all backwater types and is often found as the only remaining species. In combination with B. bufo habitats with high fish biomass are colonised. Table 6. Cluster analysis (Ward) of flowing backwater types with stable fish coenoses. Split numbers show mesohabitats within one backwater system. Cluster Backwater Characterising species Type Fish Comments 1.1 Z6, z7 Ha Temporary backwaters Absent Isolated pioneer habitats 1.2 30 Ss Flowing backwater Absent Heterogeneous flowing system 1.3 Z4, z5 Rr Temporary backwaters Absent Temporary inundation areas of the Traisen 2.1 78,97/1,5/1 Rd, Greenfrogs Warm, temporary backwaters Absent Shallow areas of backwaters 2.2 35, 7, 3/2 Greenfrogs Fish ponds, inundated areas Present Warm, nonstructured areas 2.32.5 3.1 92/1,98/1,% 70/3, 84 Highest species Rd, Bb Permanent systems numbers Backwaters 1/3. order Present/absent (3. order) Present Warm, well structured areas Large, deep systems 3.2 S48, zl,z2, 11, S34, S44, S26, S27, Sil, S14, 98, 98/2, 95, 97, 89, 92/2, 80, 81, 77, 79, 69, 76, 62a; 65, 67, 49, 61, 46, 47 23, 26, 15, 17 Rd Temporary systems, backwaters 3. order Present/absent Heterogeneous group of backwaters e.g. shadowed temporary systems, backwaters with high fish biomass 3.3 Z3 Rt Temporary backwaters Absent Small, warm backwater 4.1,4.2 28, 94, 5, 64 Rd, Rr, Tv, (Tc) Backwaters 2. / 3. order Present Warm backwaters, high macrophyte biomass 4.3 62, 86, 87 Rd, Tv, Tc, (Ha) Permanent backwaters 3. orders Absent/instable Small-medium sized backwaters 4.4 82, 90 Rd, Ha, Tv Permanent backwaters 3. order Present/absent backwaters Medium sized 4.5 18, 66, 19, 11 Rd, Tv Permanent backwaters 3. order Absent/instable backwaters Non structured, shadowed