ИСТИНА

Kislo-Sladkoye lake is a waterbody separated from the White sea. It is located 2 km away from the White Sea Biological Station on the Rugozerskaya bay in Kandalaksha bay. Lake dimensions are 196 x - 147 m, average depth is 1-1.5 m, maximum depth is 4.5 m. The main influx of fresh water comes with melted snow and rains. Salt water inflow takes place during the sizygy at high tides through the rapid between the lake and the White Sea. The main interest is in huge diversity of species of microorganisms inhabiting different depths. The most intriguing for the researchers is the red water layer at the depth from 2.2 to 2.4 m. Investigation was held during the summer student workshop in August 2014. Water samples were taken from the surface to maximum depth of 4.5 m with the 0.5 m step. In the range between 2 and 3 m step was 0.1 m. Fluorescence and absorption, H2S concentration were measured in vitro. Also all the samples were studied with the fluorescent microscopy. Microscopy studies showed a huge amount of cryptophytae algae (genus Rhodomonas). The layer distribution is: 0-1.9m – organisms are virtually absent, 2.0 m - appearance of cryptophytae algae (genus Rhodomonas) and green cocci, 2.1-2.5 m – huge amount of cryptophytae algae (genus Rhodomonas) and infusoria of different species, 2.6-3.5 m –decrease of cocci concentration. This stratification corresponds the hydrological structure of the Kislo-Sladkoye lake. The maximum of the Rhodomonas concentration is on the depth of about 2.2 m.