Macrozoobenthos of large lakes of the Omsk region

Abstract

The results of hydrobiological studies during the growing season of 2020 are presented. Qualitative and quantitative indicators of macrozoobenthos as a food resource of lakes Ik and Saltaim-Tenis are studied. In the lake Ik 7 taxa of macrozoobenthos exclusively of the class insects (Insecta) were registered. In the zoobenthos of lake Saltaim-Tenis 9 taxa of three classes were noted: insects, oligochaetes (Oligochаeta), and roundworms (Nematoda). In a comparative analysis of the species similarity of the zoobenthos of the lake Ik from the lake Saltaim-Tenis, the Jaccard coefficient was 0,8, which indicates the complete correspondence of the species compositions of these lakes. Common to the lakes were species characteristic of mesoand eutrophic water bodies Ch. gr. plumosus, C. defectus, E. carbonaria, G.glaucus, P. choreus, P. ferrugineus, C. salinarius. The average seasonal number of zoobenthos of the lake Ik reached 747±47 ind./m2, Saltaim-Tenis was 67±4,6 ind./m2, which is 11 times less than in lake Ik. Biomass of zoobenthos of the lake Ik was characterized by high rates throughout the season and averaged 25,9±4,21 g/m2, Saltaim-Tenis averaged 2,62±0,2 g/m2, which is 9,8 times less than in lake Ik. The maximum abundance and biomass of zoobenthos in lake Ik, observed in spring. On the lake Saltaim-Tenis, the highest abundance was recorded in autumn, biomass — in summer. The minimum values of zoobenthos abundance on both lakes were noted in summer, biomass — in autumn. The ecological state of the lakes has been established. Trophic status of the lake Ik estimated from the summer biomass of zoobenthos corresponds to the β-eutrophic type, high productivity class, very high-feeding water body. The lake Saltaim-Tenis, according to the summer indicators of zoobenthos biomass, belongs to the medium-feeding water body. According to the trophic status, it belongs to the α-mesotrophic type of the moderate productivity class.