Spatiotemporal Changes in the Phytoplankton in Lake Baikal during Late Summer: I. Water Temperature and Phytoplankton Abundance

Results of a study of the water temperature and phytoplankton abundance in different regions of Lake Baikal according to 15 expeditions from 1994 to 2013 during late summer are present. The spatial distribution and interannual dynamics of phytoplankton are analyzed. The total abundance of phytoplankton in late summer is shown to be high. Its average long-term value for all of the open area of Lake Baikal is 532 ± 17 thousand cells/L. In Southern Baikal, the west coast is characterized by higher average phytoplankton abundance; in Middle and Northern Baikal, the east coast is rich. No significant differences were found between the hollows of the lake in terms of the development of late summer phytoplankton. The long-term average abundance of phytoplankton in the southern, middle, and northern hollows differs only by ≤1.2 times, but in the middle hollow it is significantly higher than in the northern. In the long-term dynamics, no significant increase in the abundance of late summer phytoplankton was recorded in any of the regions of the lake. The dependence of the total phytoplankton abundance on water temperature is weak; the correlation coefficients between the average annual values ​​of these indicators are ≤0.50.