Hydrological and spectrophotometry research on Kislo-Sladkoye Lake

In this work, a description of the hydrological features of the lake Kislo-Sladkoye is given. The present work is a part of complex research on bottom topography, hydrological characteristics, water light absorption spectra at different depths, benthos communities, and ecological features of macrobenthic and terrestrial organisms. Vertical profiles of coloured layers, illumination, temperature, salinity, redox potential, acidity and oxygen content were analysed in August 2014 at different positions in the lake. According to the analysis of data, the water column is divided into strata: (a) zone of wind mixing (0 - 0.5 m); (b) halocline (0.5 - 1.5 m); (c) area with high oxygen concentration (1 - 1.5 m); (d) thermocline (1.5 - 3 m); (e) hydrosulfuric zone (2.5 m to the bottom).
Phytoplankton is dominated by cryptophyte flagellates Rhodomonas sp. and green-coloured cocci. In the coloured layers, the following pigments were detected by spectrophotometry: chlorophyll a, chlorophyll b, and bacteriochlorophyll, bacteriochlorophyll c or g, and phycoerythrin. Therefore, the presence of cryptophytae algae (genus Rhodomonas), unicellular phototrophic organisms contain-ing chlorophyll b, and green sulfur bacteria is shown. The distribution of the layers: 0 - 1.7 m: or-ganisms are virtually absent; 1.7- 2.2 m: cyanobacteria; 2.2 - 2.4 m: light absorption peaks corre-sponding to phycoerythrin and chlorophyll a and b appear, a large number of cryptophytae algae (genus Rhodomonas) and unicellular green algae. 2.4 - 2.7 m: concentration of pigments decline, a small amount of cells with chlorophyll b and cryptophytae algae; 2.7 - 4 m: green sulfur bacteria.
For the first time, a theoretical explanation of changes in the lake Kislo-Sladkoye following a spring tide is given. Densities of seawater and lake water were calculated and the results show that seawater penetrated the lake at a depth of 1.55 m during the spring tide.