Similarity patterns of macroinvertebrate communities in the Hungarian Danube and adjacent wetlands (Szigetköz and Gemenc)
Nosek, J.; Oertel, N.
On the basis of data series from a faunistic survey of 62 localities in the riparian zone of the main channel of the Hungarian Danube and the adjacent two wetlands (Szigetköz and Gemenc) in 1998-1999 an attempt was made to evaluate any differences among the separate water bodies (wetland areas, main channel and/or within the main channel) of the Hungarian Danube with regard to size and composition of macroinvertebrate communities. Representants of 19 higher taxonomic groups were present in the samples. Gastropoda, Chironomidae, Amphipoda, Hirudinea, Ephemeroptera and Trichoptera were present at 50 % of the sampling sites (Fig. 3). Platyhelminthes, Polychaeta and Decapoda occurred only at one site. In total, 233 taxa (183 species, 45 genera and 5 families/subfamilies) were found. There were only two species (Dikerogammarus villosus: 66 % and Lymnea peregra: 63 %) which were collected at 50 % of the sampling sites, and 173 taxa (74 %) occurred only at six or less sampling sites (Fig. 4). The number of taxa present at one but absent from the other water bodies was significant. The spatial dispersion of taxa proved to be contagious or aggregated, while the taxonomic groups were dispersed randomly over the whole area studied. The spatial pattern of the riparian macroinvertebrate communities is greatly influenced by the taxonomic level of identification. Differences which become clear on the basis of taxa composition remain hidden using higher taxonomic levels. Based on the riparian macroinvertebrate communities at the end of the nineties of the previous century, marked differences could be detected between the different parts of the Danube main channel and the water bodies of the two great wetlands (Szigetkæz and Gemenc). There were differences not only in the composition of the macroinvertebrate communities, but also in the community parameters.