Diversity of plankton communities of chloride lakes of Southeastern Transbaikalia

Abstract

Saline lakes as an extreme type of ecosystems are the object of intensive multidisciplinary research. The few chloride water bodies are unique in their own way and are of great interest to researchers. Their morphometric, hydrological, physical and hedrochemical characteristics are subject to significant changes, which are caused by cyclic climatic fluctuations. These lakes periodic fill and dry up. Most chloride lakes are localized on relatively level surfaces. The depth and area of the lakes vary depending on meteorological conditions. They are fed by surface runoff water and atmospheric precipitation. The surveyed water bodies are part of the Onon-Borzya group of lakes, located in the Onon River valley in the south-eastern Transbaikalia. The region is characterized by a cryoarid climate. Organisms adapted to living in mineral lakes combine wide physiological tolerance to changing salinity with rather strong dependence on other features of the habitat. We aim is to research the diversity of algae and plankton invertebrates in shallow chloride lakes (Gorbunka, Dabasa-Nur, Hilganta). This work presents the results of primary studies conducted in March and July 2021. Plankton samples were collected and processed according to methods generally accepted in hydrobiology. Taxonomic composition, abundance and biomass of planktonic organisms were revealed. The composition of algae and the ratio of the divisions in the plankton of the surveyed chloride water bodies are typical for water bodies with increased salinity, where cyanobacteria and green algae prevail. In zooplankton one species, rotifer Brachionus plicatilis, which is a cosmopolitan, halobiont and typical inhabitant of inland mineral lakes, was found. Quantitative indices varied within a wide range, which is probably connected with hydrochemical indices and different level of filling of lakes.