Long-term dynamics of dominant diatom species abundance of spring phytoplankton in three basins of the pelagic zone of Lake Baikal in 1964-1984 and 2007-2016

Abstract

Analysis of long-term observations of dominant diatom species of spring phytoplankton of Lake Baikal Synedra acus subsp. radians, Aulacoseira baicalensis, Aulacoseira islandica, Stephanodiscus meyeri and Nitzschia graciliformis was demonstrated. It is shown, how the abundance of these species varied in Southern, Central and Northern Baikal in 2007-2016 compared to other observation periods in 1964-1968 and 1969-1984. It is found out that, species ratio changed in 2007-2016. The abundance of S. acus subsp. radians increased in Southern and Central Baikal, while for other species - A. baicalensis, A. islandica, N. graciliformis and S. meyeri, it significantly decreased. In Northern Baikal, the ratio of species in 2007-2016 was comparable to 1969-1984. Despite the change in the ratio of species over the past decade, the contribution of these five dominant species to the total abundance of spring phytoplankton of Lake Baikal has comparable values in all studied periods.