Spatial-temporal analysis of temperature in Lake Shira based on long-term observations

Long-term in-situ measurements of temperature were conducted in lake Shira during 2013-2015. The principal component analysis of temperature time series allowed to identify period of generation and propagation of internal waves. The spectral analysis revealed the dominance of the oscillations with periods of 21.3, 10.6 and 5.3 h.

Measuring Alloxanthin as a Proxy Approach in a Study of Trophic Relationships between Zooplankton and Cryptophyte Algae in Lake Shira

Cryptophyte algae are an important trophic link in many aquatic ecosystems, but they remain insufficiently studied in terms of trophic interactions with other components of ecosystems. They are better quality food than most other algae and, therefore, can be subject to selective grazing by zooplankton; thus, direct measurements of the dynamics of their concentration in lakes may give very low productivity indicators. One way to assess the consumption of cryptophyte algae by zooplankton is to determine the content of alloxanthin, a carotenoid specific for cryptophyte algae, in zooplankton. The present study investigated the alloxanthin content of sedimentary silts, sedimentation traps, and zooplankton of Lake Shira using high performance liquid chromatography. A significant correlation was found between the abundance of some zooplankton species capable of consuming cryptophyte algae and the flux of precipitated alloxanthin recorded in sedimentation traps. Analysis of zooplankton samples (the largest contribution to the biomass of which was made by the copepod Arctodiaptomus salinus (Daday, 1885)) for the content of carotenoids during the spring-summer season showed the presence of alloxanthin amounts reaching 80 μg/g, which decreased by the end of the season, and that correlated with the biomass of cryptophyte algae in the lake. Carotenoids associated with other groups of algae were observed in considerably smaller amounts. Thus, the copepod A. salinus exhibits high selective consumption of cryptophyte algae, which may serve as a confirmation of a close trophic relationship between them

Green algae distribution in some salt lakes of the Republic of Khakassia

The publication presents the results of a floristic study of green algae of some salt lakes in the Republic of Khakassia: Shira, Tus, Ulugkol, Altaiskoe, conducted in the period from 2006 to 2019. The lakes are located in the steppe zone within the Chebakovo-Balakhtinsky and Minusinsky basins of the Nazarov-Minusinsky intermountain depression. The mineralization of water in the lakes for the study period was: 15,9–21,9 g/l (Lake Shira); 52,7–115,07 g/l (Lake Tus); 18,3–21,7 g/l (Lake Ulugkol); 42,7 g/l (Lake Altaiskoe). The values of pH of the water lakes are alkaline – 8,2–9,8. In plankton, benthos and periphyton of 4 lakes we found 30 species of green algae belonging to 5 classes, 10 orders, 17 families, 22 genera. Cladophora glomerata and Oocystis submarina species were discovered in all the lakes surveyed. In different algae communities, along with cyanoprokaryotes and diatoms from green algae, the following species dominated: Botryococcus braunii, Chlorella chlorelloides, Cladophora glomerata, Cladophora sp., Dunaliella salina, Hindakia tetrachotoma, Oocystis submarina, Rhizoclonium hieroglyphicum, R. riparium, Spermatozopsis exsultans, Sphaerocystis planctonica. Among them, highly active species with a relative frequency of occurrence of 74–50 % were: Dunaliella salina (in lakes Ulugkol and Altaiskoe), Sphaerocystis planctonica and Oocystis submarina (in lake Ulugkol). Rare species for the flora of the region are noted: Picocystis salinarum – in lake Altaiskoe, Percursaria percursa – in the lake Tus. In relation to water mineralization, the green algae of the studied lakes belonged to the groups of indifferents, halophiles, and polygalobes.

Emergence of Midges (Chironomidae, Diptera) from a Saline Lake as a Source of Organic Matter and Essential Biochemical Compounds for Arid Ecosystems in South Siberia

Midges (Chironomidae, Diptera) are dominant amphibiotic insects in zoobenthos of the large saline Lake Shira located in the arid landscape of South Siberia. During two vegetation seasons we measured the dynamics of chironomid emergence from littoral parts of four stations in the lake. During one of the vegetation seasons we also measured chironomid emergence from profundal parts (depth of 6 m) of the same stations using original floating traps. Both seasonal dynamics and daily means of emergence values significantly varied among the studied stations and depths and were related to the bottom sediment type. The annual export of wet biomass (calculated as the sum of daily values for a vegetation season) was equal to 0.61 g per square meter of water surface and included proportional contributions of the areas with various bottom sediment types. Based on the values of benthic secondary production, we estimated additional annual export of chironomid biomass from the profundal part of the lake of approximately 1 g of wet weight · m−2. Besides, the total export of polyunsaturated fatty acids (PUFA) calculated using the previous data on PUFA content in the studied chironomid taxa (~ 2 mg · m−2 year−1) appeared to be one of the lowest when compared to estimations for chironomids and some other amphibiotic taxa from similar steppe landscapes

Fatty acid composition of the strain Nitzschia sp. isolated from the meromictic Lake Shira

Algae that inhabit extreme environmental conditions are often capable of synthesizing and storing unique biochemical inclusions. The diatom alga Nitzschia sp., strain Z-6, isolated from the meromictic Lake Shira, under conditions of nitrogen starvation, is capable of accumulating rare PUFAs (polyunsaturated fatty acids) that may be useful for biotechnology.