In 2019, the composition and quantitative representation of the zoobenthos in Donuzlav Lake, in the area of fine sediment discharge after the sand mining, and in the adjacent water area were studied. The accounting of the macrozoobenthos at the species level and of the meiobenthos at the major taxa level indicates the presence of a typical Pontic bottom fauna in the Lake, which has developed over 58 years of it existence. The benthic macrofauna was represented by a biocoenosis of Chara algae with Mytilaster lineatus, existing in a two-tier biotope – of a soft-bottom and of a Chara algaes developing on it. The epiphyton macrofauna quantitatively dominated the benthic macroinfauna. A total of 102 species and 7 superspecies taxa of the macrozoobenthos were registered in the identified biocoenosis. That increases the overall level of the macrozoobenthos representation up to 171 species and 9 superspecies taxa in Donuzlav for the period since 1981. In meiobenthos 11 taxa in the rank of type were recorded. The abundance and biomass of the macrozoobenthos averaged 34.658±1.655 ind./m2 and 316±93 g/m2 respectively, that is comparable with the previous studies. The average abundance of meiobenthos in the bottom biotope reached 247.2×103 ind./m2. Nematodes were the dominant group in meiobenthos, followed by harpacticids, with a combined share of 81 % in total meiobenthos abundance. The local impact of the discharging finely dispersed soil fractions to the benthic fauna of the southern part of the Donuzlav Lake was revealed. There was a 12, 3.5 and 2-fold decrease in abundance, biomass and number of macrozoobenthos species respectively and a 3.2-fold decrease in meiobenthos abundance, in the discharging area compared to the neighboring water areas of the Lake.
Soft bottom macrofauna of an All Taxa Biodiversity Site: Hornsund (77○N, Svalbard)
