The spring phytoplankton in the pelagic zone of Lake Baikal during 2007‒2011

An assessment is made of the current status of the phytoplankton in the pelagic zone of Lake Baikal for 2007‒2011, as the continuation of previous long-term research. We investigated the species composition, population, biomass and spatial distribution of the phytoplankton in the pelagic zone of Baikal. Its quantitative indicators for 2007‒2011 have been compared with data of long-term investigations (1964‒1990). It is shown that the species composition of the phytoplankton remained stable at different periods. The values of population and biomass for 2007‒2011 fitted in the range of long-term fluctuations (1964‒1990), with the species assemblage characteristic for that period. As in the case with previous research, the main contribution to the biomass of the spring phytoplankton in the lake was made by the diatoms Aulacoseira baicalensis, Synedra acus subsp. radians, Aulacoseira islandica, and Stephanodiscus meyeri. Their maximum and minimum concentrations were observed in the southern and middle lake depressions, and in Northern Baikal, respectively. The study revealed a correlation of phytoplankton biomass with silicon concentration; no correlation with nitrates, phosphates and temperature was ascertained.