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

— backwaters of third order: isolated systems that are only inundated during flood events. — flowing backwaters: small streams in the Traisen-area — artificial waterbodies: fish ponds. The backwaters were investigated with different methods during 1997 to obtain a complete set of fish and amphibian coenoses. Fish were mainly detected by electrofishing. Fish show characteristic galvanotaxis in an electric field (Cowx & Lamarque 1990), we used 1.5 or 2.5 KW aggregates (DC) with 300-600 voltage. Amphibian populations were either evaluated by counting spawning clutches (mainly Rana dalmatina) or by searching for larvae or metamorphosed juveniles (Pintar & Straka 1990). Larval occurrence was identified by standardised catches with a hoop net. Although we tried a similar and simultaneous field analysis of fish and amphibian coenoses, field survey of both groups was achived by different methods. Fish coenoses can be quantified by electrofishing, whereas amphibians were quantified only in the case of Rana dalmatina. Therefore, for data analysis a hierarchical cluster analysis was applied after Ward, we used single habitats as cases and binary species records of fish and amphibians as variables. To determine distance between cases, Squared Euclidean Danube / Traisen system 79.80.81.82.83.8 70. 77. 78. S48 Traisen Traisen system Z2.Z3 30.SM St. Pölten Fig.l. The investigation area: Numbers refer to backwater characterisation and are cited in the text