Year: 2022, Number: 2, Pages: 20-27
The paper presents first data on the species composition and structure of plankton communities based on phytoplankton and zooplankton research conducted in Lake Arey in 2019–2020. The lake is a functioning natural monument of regional significance in the Trans-Baikal territory. The research revealed 102 algae taxa and 50 zooplankton species. The species composition of planktonic flora and fauna consisted of cosmopolitan, eurybiontic and freshwater species. The total abundance and biomass of the planktonic community changed widely during the entire research period. The density of phytoplankton was the highest in September and July (due to Cyanobacteria and Bacillariophyta), the lowest in March, whereas the zooplankton peak was in September (due to rotifers) with a decline in July. The dominant complexes were represented by ten phytoplankton taxa (Aphanizomenon flos-aquae, Coelomoron pusillum, Limnothrix planctonica, Aphanothece sp., Microcystis pulverea, Cyclotella meneghiniana, Asterionella formosa, Ulnaria ulna, Aulacoseira granulata, Fragilaria radians) and eleven invertebrate species (Keratella cochlearis, Keratella quadrata, Kellicottia longispina, Synchaeta kitina, S. pectinata, Polyarthra dolichoptera, Filinia longiseta, Asplanchna priodonta, Neutrodiaptomus incongruens, Cyclops vicinus, Mesocyclops leuckarti). The lake is oligo-mesotrophic, according to the diversity index values.