The fauna and benthic communities of invertebrates of watercourses of the Upper Vichera river basin

There are 176 species and forms in the zoobenthos of the Upper Vishera river basin. Larvae of chi-ronomids are the most diversely (80 species and forms). There are 25 species of caddisflies, 23 species of mayflies and 20 species of stoneflies. The basis of the fauna (61.7%) is species with broad areas. The western and the eastern Palaearctic species account for 25.7% and 11.3%. Two species (1.3%) are endemic. In the Upper Vishera and its tributaries - the Halsoria, the Lopya and the Big Moyva rivers - communities, where caddisflies Arctopsyche ladogensis and Apatania crymophila, stoneflies Arcynop-teryx compacta and mayflies Heptagenia sulphurea are dominated, are formed. Its number is varied between 1 150-8 180 ind/m2, the biomass - from 1 600 to 5 110 mg/m2. Communities, where caddisflies Rhyacophila nubila and A. crymophila, stoneflies A. compacta and mayflies H. sulphurea are dominated, are formed in the Niols river, the Small Moyva river and in the Small Listvennychnye stream. The number of zoobenthos is 800.8 010 ind/m2, the biomass - 3 980.5 600 mg/m2. Community, where larvae of chironomids are dominated, is formed in the Muravei river. The number and the biomass reach 34 010 ind/m2 and 30 070 mg/m2. Communities, where mayflies of Baetis genus, stoneflies Isoperla gram-matica, Amphinemura borealis and caddisflies A. crymophila and Potamophylax latipennis are dominated, are formed in small streams. The number of benthic fauna is 1 720 ind/itf and the biomass - 2 490 mg/m2.