Home – Home – Jornals – Contemporary Problems of Ecology 2021 number 4

The species composition and quantitative characteristics of the zoobenthos of Lake Pyasino and rivers flowing into it after the diesel spill have been analyzed. The production of zoobenthos and potential production of benthivorous fish in Lake Pyasino have been calculated. A small number of zoobenthos species, low values of abundance and biomass were revealed. In the Bezymyanny stream, the mouth of the Daldykan and Ambarnaya rivers, oligochaetes Limnodrilus hoffmeisteri Claparede and Tubifex tubifex (O. F. Muller) dominated in zoobenthos abundance and biomass. In Lake Pyasino and the Pyasina River outflow, larvae of caddis flies, chironomids, stoneflies, and amphipods prevailed. In the area of deep-water silted station of Lake Pyasino, oligochaetes L. hoffmeisteri developed, the proportion of which in the benthofauna at this station (40 and 79 % of the total biomass and abundance respectively) was maximal. Amphipod Monoporeia affinis (Lindstrцm) dominated in biomass at this station. A decrease in chironomid diversity, an increase in the proportion of polysaprobic oligochaetes, and lower values of the Shannon index in Lake Pyasino in 2020 compared to 1992 were noted. The low abundance (2181 ± 2048 ind./m²) and biomass (2.01 ± 1.85 g/m²) of zoobenthos in the lake resulted in low values of zoobenthos production and potential production of benthivores fish (3 kg/ha per season). Based on the state of zoobenthos, improvement of water quality has been observed from river sections exposed to the oil spill to the lake and the outflow of the River Pyasina.