Seasonal dynamics of the Upper Ob zoobenthos

Abstract

results of studies of the seasonal dynamics of the Upper Ob zoobenthos in the city of Novosibirsk are presented. Zoobenthos rivers Ob the growing season of 2022, the Ob was represented by 6 systematic classes: bivalves (Bivalvia) and gastropods (Gastropoda), small-lobed worms (Oligochaeta),leeches (Hirudinea), multi-legged crayfish (Amphipoda), insects (Insecta), including from the orders of mayflies (Efemeroptera), brooks (Trichoptera) and diptera (Diptera) from the families of bell mosquitoes (Chironomidae) and woodlice (Ceratopogonidae). A total of 43 species of invertebrates have been found. The largest number of taxa was observed in summer — 27, the minimum in autumn — 16. During the entire growing season, chironomid larvae and gastropods were observed in the benthic fauna. In the spring, the maximum species diversity was noted in the family of bell mosquitoes (Chironomidae) — 18 out of 24 of the total composition. The larvae of chironomids played the main role in the number, in the biomass — an autoacclimatizant — a gastropod mollusk (Viviparus viviparus (L.), belonging to a benthic non-feed for fish. The specific weight of this species in the total biomass reached 92.7%. In summer, V. viviparus (L.) dominated both in abundance and in biomass. The zoobenthos of the autumn period was characterized by a decrease in species diversity and abundance compared to previous seasons: 16 species from 5 classes were oted in the species composition, the number decreased by almost 2 times. The gastropod mollusk V. viviparus (L.) dominated in all indicators, as in summer. The average number of zoobenthos during the growing season was 527 copies/m2, the average biomass was 532,388 g/m2, of which 222 copies/m2 and 531,463 g/m2 were autoacclimatizant gastropod mollusk V. viviparus (L.).