Seasonal changes of phyto-, bacterioplankton and autotrophic picoplankton in the photic layer of Lake Baikal

Abstract

Abstract. This research was investigated the seasonal changes in phytoplankton, bacterioplankton and autotrophic picoplankton as well as environmental parameters in the photic layer of Lake Baikal. Using microscopy methods, 43 species belonging to Bacillariophyta, Dinophyta, Chlorophyta, Chrysophyta, Cryptophyta, Haptophyta, Charophyta and Cyanoprokaryota have been identified. Bacillariophyta and Chlorophyta were dominating throughout the year. The Shannon, Simpson, InvSimpson diversity indices, and evenness index showed that microalgae communities varied seasonally. In late spring these indices were significantly lower than in the under-ice period, summer and autumn that is due to the fact of the dominance of one species Ulnaria acus (K tzing) Aboal in the community. The abundance and biomass of phytoplankton also varied significantly depending on the season. Five different periods of phytoplankton development were identified, which were regulated by physicochemical factors.