Species Composition Features of Zoopankton in Mineralized Water Bodies from Specially Protected Natural Territories in Ulug-Khem Basin (Republic of Tuva)

Abstract

The species composition of zooplankton in mineralized water bodies located in the Ulug-Khem basin (Republic of Tuva) was studied. These lakes have the status of natural monuments of regional significance. In total we recorded 53 species of microscopic Custaceans and Rotifers from 32 genera, 13 families, and 8 orders. Cladocera comprises 53% of the species. The dependence of the species diversity on the level of mineralization was revealed; 89% of the species were found in brackish water bodies. The zooplankton composition of the hyperhaline lakes Dus-Khol (Svatikovo) and Cheder has remained constant for many dozen years. The zooplankton includes some species known only from Republic of Tuva in Russia, namely, Microcyclops afganicus and Macrotrix tabrizensis. M. asiaticus and Alona irinae, rare for the fauna of Russia, live in the lake Haak-Hol. A decrease in the total numbers of zooplankton is observed in the lakes, namely: in the lake Dus-Khol, it has decreased by 4 times, in the lake Khadyn it has decreased by 10–19 times as compared to the middle of the last century. Despite the lack of intermediate information, we regard this as a consequence of anthropogenic impact. The emergence of an indicator of pollution (Brachionus nilsoni) in the lake Khadin confirms this version. At the same time, the stable finding of species rare for the fauna of Russia indicates the presence of favorable conditions for their development and life, which increases the value of the reservoirs themselves, which are already unique natural objects.

Pleuroxus pamirensis (Werestschagin, 1923) (Crustacea: Cladocera), first record for the fauna of Russian Federation

“…However, less attention is paid to Western Siberia and western portion of Eastern Siberia, a huge territory with millions of water bodies [Pirozhnikov, 1937;Korovchinsky, Dubovskaya, 2014;Kirova, 2021]. Southern Siberia is an especially interesting region: presumable refugia for freshwater fauna were located there during Pleistocene glaciations [Zuykova et al, 2019].…”