2002

Mathematical modelling (made at ICS SB RAS):

The researchers built mathematical models of different levels of complexity to study wind-generated currents in stratificated reservoirs (by the example of Lake Shira) - one-dimensional, two-dimensional in the plan and in a vertical plane, three-dimensional, hydrostatical and non-hydrostatical approximating. Several computer programs were worked out with the aim of investigating of the two-dimensional, in vertical and horizontal planes, wind-generated currents in a stratificated reservoir, and calculations were made for various input data. The computer program for studying of three-dimensional flows in simple geometry reservoirs enjoyed final adjustment.

Microbiological investigations (made at IBP SB RAS):

The scientists analyzed the effect of temperature and sodium chloride on the vertical and horizontal distribution of heterotrophic bacteria, selected from Lake Shira in different seasons from 1999 to 2002. It was shown that the selected microorganisms tend to grow in moderate and low temperatures. In summer period it's mesophilic bacteria, found all across the lake, that prevail, while psychrotolerant microorganisms predominate in the central part of the ecosystem, in metalimnion and hypolimnion. In winter psychrophilic and thermoinducible bacteria were revealed in Lake Shira.

The growth efficiency of mesophilic, psychrotolerant and thermoinducible bacteria was studied in the presence of different concentrations of sodium. It was shown that it's mostly the mesophilic bacteria that belong to non-halophilic microflora, prevailing in the littoral zone of the lake, while the majority of psychrotolerant and thermoinducible bacteria are able to grow in a medium with 5-10% content of NaCl.

The scientists identified the heterotrophic bacteria selected from different parts of Lake Shira. On the basis of halotolerance criterion, growth efficiency at low temperatures and quantitative assessment of the taxonomic composition of heterotrophic microorganisms in the studied pars of the lake, the bacteria were preliminarily divided into autochtonous and allochtonous.

The heterotrophic bacteria of Lake Shira were investigated with a view to their resistance to antibiotics. It was shown that in winter it's the antibiotic-sensitive bacteria that prevail. In summer period there is a tendency of growing of mesophilic non-halophilic bacteria, showing multiple resistance to antibiotics in the resort zone of Lake. At the same time in the central part of the lake the percent of non-halophilic bacteria with these characteristics in the heterotrophic bacteria community tends to increase. Multiple resistance to antibiotics of the bacteria selected from the central part of Lake Shira in summer period is the evidence of the negative man's impact on the ecosystem.

Investigations of sulphur and carbon cycles interaction (made at IBP SB RAS, IBIW RAS, IMB RAS):

The researchers made quantitative assessment of the activity and quantity of microorganisms taking part in carbon and sulphur cycles in the water layer and benthic sediments of lakes Shira and Shunet:

The activities of the following major microbiological processes were determined by nuclear-radiation technique: photosynthesis production (with 14 С -bicarbonate); sulphate reduction rate (with 35S-sulphate); the rates of methane formation and oxidation (with 14 С -bicarbonate, 14 С -acetate and 14 С -methane).

The stable-isotopic composition of carbon and sulphur compounds was determined as the indicator of geochemical activity of various physiological groups of microorganisms.

The scientists obtained accumulative and one-species cultures of phototrophic, sulphate reducing, methanotrophic and methanogenic archaea.

The vertical distribution of the main groups of microorganisms was determined in the chemocline zone.

Investigations of phyto- and zooplankton (made at IBP SB RAS and KSU):

The researchers worked out and field-tested two-section extracted volumes - devices aimed at in situ investigation of vertical migrations of zooplankton.

A series of field experiments was made with the aim of studying of the interpopulation contacts Gammarus lacustris and Arctodiaptomus salinus , prevailing in the lake, during the formation of vertical distribution of zooplankton in the lake.

The fluorescence indices of phytoperiphyton were investigated at reconnaissance stations of Lake Shira. Samples were selected and prepared for determination of the structural characteristics of phytoperiphyton.