Ecological characteristics of small river fish fauna: structure of fish communities

Abstract

The investigation of fish communities on certain sampling spots from two distanced sampling sites on the Vapa river, revealed the discrepancy between results of qualitative and quantitative analyses, thus suggesting the fine structuration within fish communities. It is due to specific affinities of particular species: the chub Leuciscus cephalus (L., 1758) to a deeper water, the brook barbel Barbus peloponnesius Velenciennes, 1844 to a shallow water, the stone loach Orthrias barbatulus (L. 1758) to a faster current, and the nase Chondrostoma nasus (L., 1758) to weedless parts. Some other fish species revealed the regular distribution, e.g. the bullhead Cottus gobio L., 1758, the gudgeon Gobio gobio L., 1758, the schneider Alburnoides bipunctatus (Bloch, 1782), thus suggesting the possibility of distinguishing the particular river regions. Habitats with a domination of the single species (usually the chub), e.g. whirlpools, had small diversity, while those with the even distribution of species, e.g. rapids and weeded marginal zones, had the greatest diversity. The different composition of communities in weeded marginal zones from the composition of nearby different habitats suggests they are unstable, and fluctuating. That, and small size-classes of fishes, suggest that these weeded habitats most likely serve as a refuge for fish.