МACROZOOBENTHOS OF THE RIVER BOLSHAYA SARAPULKA IN THE UDMURT REPUBLIC
Bolshaya Sarapulka is a small river, the upper and middle reaches of which are characterized by low pollution, mainly by domestic and agricultural wastewaters. In the lower reach of the river, the anthropogenic load increases due to municipal and industrial sewage of the city of Sarapul. The purpose of this work is to study the species composition and quantitative development of the macrozoobenthos of the Bolshaya Sarapulka River, the right tributary of the Kama River. In the river's macrozoobenthos 126 species and taxa of a higher systematic rank are recorded. The leading group in the species composition is mollusks (27 species) and beetles (23 species). There were revealed 17 species of Diptera, 18 - Trichoptera, 11 - Annelida, 12 - Ephemeroptera, 7 - Odonata, 6 - Heteroptera, 1 - Crustacea. The maximum number of species was observed on sandy-silty soils (76 species). Species wealth gradually decreases from the headwater to the mouth of the river due to substitution of rheophilic communities with limnophilic ones and influence of urban environment. The highest density and biomass of macrozoobenthos was recorded on clayey silts and sandy-stony grounds, respectively.