ZOOPLANKTON IN THE DEEP-SEA AREA NEAR THE WESTERN AND EASTERN COASTS OF SOUTHERN BAIKAL IN 2021

Abstract

Zooplankton in the deep-water zone of Lake Baikal features endemism, a specific trophic structure, intensive food relationships and pronounced interannual variability. In the late summer period, the dynamics of zooplankton at the deep-sea zone near the western (Point 1, village Bolshye Koty) and eastern (former BCBC area of wastewater discharge) coasts, taking into account natural conditions. The total number of zooplankton in the 0-100 m layer off the west coast was 2,493 thousand per/m2. Epischura baikalensis Sars 1900 prevails - more than 51 % (1260,76 thousand per/m2). The share of rotifers was 47 % (1138,0 thousand per/m2). The number of Cyclops kolensis Lilljeborg, 1901 was 13,7 thousand per/m2 and Bosmina longirostris Muller, 1785 - 15,98 thousand per/m2 which accounts for about 2 % of the total amount of zooplankton. The total number of zooplankton in the 0-100 m layer off the east coast was 2399,18 thousand per/m2. Epischura baikalensis dominates the zooplankton community - more than 57 % (1379,99 thousand per/m2). The share of rotifers was 40 % (965,1 thousand per/m2). The number of Cyclops kolensis was 49,62 thousand per/m2 and Bosmina longirostris - 4,51 thousand per/m2 which accounts for about 3% of the total amount of zooplankton. The average temperature values in the 0-100 m layer and water transparency at the western and eastern coasts differed slightly from the long-term average. At the western shore, the maximum surface concentration of chlorophyll «a» was 1,84 mg/m3 with an average value of 1,16± 0,27 mg/m3. At the eastern coast, the maximum concentration of chlorophyll «a» at a depth of 25 m was 2,41 mg/m3 with an average value of 1,39±0,31 mg/m3. No significant differences in the state of plankton were found at the western and eastern coasts of Southern Baikal.