LONG-TERM DYNAMICS AND SPATIAL DISTRIBUTION OF MACROZOOBENTHOS IN THE PROFUNDALE OF THE WHITE LAKE (VOLOGDA REGION)

Beloe Lake is part of the Sheksninsky reservoir and is part of the Volga-Baltic Waterway. The lake has a saucer-shaped shape, about 90% of the lake bottom is covered with silt, the depth is 4–6 m. Studies of macrozoobenthos in the profundale of the White Lake were carried out in 2010–2020 in late September — early October and sporadically in other seasons. The communities of zoobenthos in profundalia are of the same type and are represented exclusively by small bivalves, oligochaetes and chironomids. Of the 107 species of zoobenthos recorded for the lake, only 10 are constantly found in the central part of the lake. The biomass of zoobenthos in the period 2010–2020 ranged from 2.8 to 19.3 g/m2. Compared with the studies of the second half of the 20th century, the biomass values in 2010–2020 fit into the range of biomass fluctuations. In 2010–2020, a restructuring of the dominant zoobenthos complex was observed: Tubifex newaensis was replaced by Limnodrilus hoffmeisteri. There is also an increase in the size of the autumn generation of Chironomus plumosus and loss of Stictochironomus.