2001

We assessed: а ) the effect of temporary currents (precipitation, snow melting) on the composition of water and bottom sediments of Lake Shira, b) the effect of eolation on the composition of water and bottom sediments of the lake, c) the composition of the technogenic grounds of the settlement zone of the resort "Lake Shira" and their possible effect on the composition of water and bottom sediments of the lake.

In general, the data collected in 2001 confirmed the earlier proposed mechanism of formation of profundal chlorophyll " а ", which is characterized by grazing of microalgae by zooplankton in surface layers and a favorable mineral nutrition conditions in deep layers, and allowed to work out in detail the formation scheme of profundal maximum.

A series of experiment was made to study the growth of freshwater shrimp juveniles Gammarus lacustris (Sars) of Lake Shira depending on different kinds of forage. Copepod Arctodiaptomus salinus (Daday) and submerged vegetation (pondweed) were used as forage.

We thoroughly studied the vertical structure (daytime and nighttime distribution) of the zooplankton of Lake Shira in summer period.

The experiments were aimed at studying of the effect of physico-chemical factor gradients (light, temperature, oxygen concentration, hydrogen sulphide concentration) on the vertical distribution of zooplankton.

It was shown that the bioluminescent bienzymatic system is sensitive to the changes in the environment redox state, and that the oxidized forms of compounds have a larger effect on the bioluminescence of the bienzymatic system, than the corresponding reduced forms.

The distribution of mesophilic and psychritolerant heterotrophic bacteria was studied in summer period. It was shown that it's mesophilic bacteria that predominate in the littoral zone and surface layers of the lake, their percentage varies from 40 to 100%. In the central part of the lake at a depth of 10, 20 m the majority of bacteria is represented by psychrotolerant heterotrophic bacteria - 65%.

On the basis of two-dimensional models in a vertical plane we studied the effect of density stratification, intensity of wind and reservoir geometry on the flow pattern. It was shown that even minor relative changes of density in depth, depending not only on the temperature, but also on salinity gradient, result in the change of the qualitative flow pattern.

In theory, we discriminated the connection between the allochtonous flow of organic matter and hydrogen sulphide flow from the bottom as factors controlling the hydrogen sulphide zone . The calculations showed that the calculated parameters of the hydrogen sulphide zone will correspond better to the field data if we introduce the allochtonous flow of organic matter to the flow models. We established the theoretical limit of the depth of hydrogen sulphide zone rising when loaded with the allochtonous flow of organic matter.