Fish and macrozoobenthos in the Vlára stream drainage area (Bílé Karpaty Mountains)

Fish fauna and macrozoobenthos were surveyed at 51 and 32 sampling sites, respectively, in mountain and submountain streams of the Vlara stream drainage area in the Bílé Karpaty Mountains. The aim of the study was to bring wide knowledge of their aquatic communities with their indicative value of the ecological quality of particular sites. Fish were sampled by electrofishing and macrozoobenthos was collected by kick-sampling using a bottom net (mesh size 500 μm) at the majority of the respective sites. In total, 15 fish species were registered in all profiles. At four headwater sites no fish were recorded at all. Brown trout (Salmo trutta m. fario) and stone loach (Barbatula barbatula) were the most frequent species at the sites under study (73% and 67%, respectively). A similar frequency (41%) was documented for chub (Leuciscus cephalus), gudgeon (Gobio gobio) and minnow (Phoxinus phoxinus). The species richness increased downstream in the mainstream of the Vlára stream with the maximum of 10 species found at the lowest study site. Qualitative data on fish assemblages did not fully correspond with the environmental stress. On the other hand, macrozoobenthos indicated a minor decrease in water quality downstream of small villages and farms. Larvae of dipterans (Chironomidae and Simuliidae in particular) and mayflies (Ephemeroptera) dominated among the temporary water macroinvertebrates while numerous populations of Gammarus fossarum (Amphipoda) and in some cases also of Asellus aquaticus (Isopoda) were recorded as permanent inhabitants of clean and polluted stretches, respectively.