2003

Physico-chemical monitoring and mathematical modelling (made at IBP SB RAS and ICS SB RAS):

The scientists measured the physical and chemical characteristics of the water layer of lakes Shira and Shunet in all seasons: in winter under ice, in spring after ice melting, in summer during temperature stratification and in autumn before freeze-up. Physical characteristics included temperature, рН , redox potential, electrical conductivity, turbidity, luminance. Chemical characteristics were as follows: concentrations of oxygen, hydrogen sulphide, sulphur, sulphates, ammonium nitrogen and inorganic phosphorus. It was found out that in winter in Lake Shira the chemocline zone is located more deeply than in summer, which proves that the lake is characterized by the balanced productive-destructive processes in the cold time of year. The analysis of vertical distribution of hydrogen sulphide and temperature showed that in spring 2003 there was intermixing of water layer with some parts of the bottom layers. The researchers consider that the amount of hydrogen sulphide in the monimolimnion of Lake Shira tends to decrease during the last three years.

A one-dimensional mathematical model was built to determine the annual dynamics of the vertical distribution of temperature and salinity of lake water. For winter period, the convective mixing in the layer bordering the ice cover is calculated in a simplified statement. Trial calculations were made for Lake Shira.

Microbiological investigations (made at IBP SB RAS, IMB RAS and IBIW RAS):

Using original device for vertical thin-layer water sampling, the scientists studied microstratification of microbe populations in the chemocline zone. It was shown that in summer the large-scale growth of purple and green sulphur bacteria in Lake Shira occurs in layers about 5 cm thick, and the layer of purple bacteria forms exactly in the redox zone, while the layer of green bacteria is located right under the purple bacteria layer. In winter and spring the microstratification of both groups of bacteria wasn't found.

The scientists investigated the microstratification of phototrophic sulphur bacteria in the chemocline of Lake Shunet. It was discovered that in summer the redox zone forms a thin (about 5 cm) layer in which the quantity of purple bacteria is by two orders of magnitude larger than in the corresponding zone of Lake Shira. In winter the microstratification of purple and green bacteria wasn't revealed. The data obtained in 2003 allow to study Lake Shunet as a scaled-down model analogue of Lake Shira and to make comparative studies of the two lakes with the aim of revealing the mechanisms of matter cycle in aquatic ecosystems of this type.

The researchers studied the vertical distribution of the rates of sulphate reduction, oxygen and anoxic photosynthesis, methanogenesis and methane oxidation in lakes Shira and Shunet in winter time. They determined the thin-layer distribution of the rates of sulphate reduction, oxygen and anoxic photosynthesis in the chemocline of Lake Shunet in summer, resolution being 5 cm.

The heterotrophic bacteria selected from the stations of the littoral zone of Lake Shira having different degrees of man's impact in summer period were tested for sensitivity to antibiotics (ampicillin, kanamycin). It was shown that at the stations subject to an intense man's impact prevailed bacteria resistant to both classes of antibiotics (ampicillin and kanamycin). At the stations located at the distance of 2 km from the resort beach there was a larger number of bacteria resistant to one antibiotic (ampicillin). The littoral zone of Lake Shira which was less subject to man's impact revealed no bacteria resistant to antibiotics.

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

The scientists studied the dynamics of the vertical distribution of zooplankton in the meromectic Lake Shira and its connection with the stratification of the lake. It was shown that the peaks of reproduction of zooplankton species prevailing in Lake Shira are spaced apart in time, while the prevailing species themselves and various age-dimension groups of one kind are located in different places.