No abstract

Molecular phylogeny inferred from rbcL nucleotide sequences obtained from the single sterile filaments of green algae collected around the perimeter of Lake Baikal indicates the polyphyletic origin of the representatives of genus Spirogyra Link., 1820 inhabiting the lake. The common ancestor of all Baikal Spirogyra dates back at least to 20 MYA. This roughly coincides with the age of continuously existing freshwater body in the confines of current Baikal. The descendants of this node include both Baikal and non-Baikal species and thus suggesting a complex history of multiple emigrations and immigrations. There is at least one major lineage of the Baikal Spirogyra in the phylogeny descending uninterruptedly from the common ancestor of all Spirogyra species found so far in the lake. The likely explanation is its permanent presence in the ecosystem. All this allows us to hypothesize that the current bloom is a spectacular but natural response of the Baikal ecosystem to the increased pollution.

We have studied the diversity and composition of communities of micro-eukaryotes from two localities: area under anthropogenic impact near the town of Baikalsk and reference area, Irinda Bay, based on high-throughput ITS2 rDNA region sequencing. High taxonomic diversity of micro-eukaryotes has been revealed in both localities studied. However, micro-eukaryotic community from the area under anthropogenic impact is depressed, compared to reference area. Analysis of taxonomic diversity has revealed that community from the area under anthropogenic impact has a trend towards a decrease in diversity. Among the detected taxa, Alveolata, Stramenopiles and Fungi prevailed. Sörensen index of OTUs was 65%, which indicates the similarity of communities studied by taxonomic composition. The spectrum of Alveolata and Stramenopiles taxa identified in the area under the anthropogenic impact and the reference area was similar. The main differences were revealed in spectrum of Fungi taxa.