The highest density of macrofauna was recorded in a muddy habitat, and the highest biomass (d.w.) in a stony one. Only Naididae, Hydracarina, young larvae of Trichoptera, and large specimens of Gammarus spp. preferred a transitional habitat (mud-covered stones). Of the 25 identified species of Oligochaeta especially three dominant species (Nais bretscheri, N. pardalis, and N. communis) were most numerous in the transitional habitat. Downstream the species diversity of Oligochaeta increased and the composition of the community changed.