Bacterial communities during the period of massive under-ice dinoflagellate development in Lake Baikal

Taxonomic diversity of Lake Baikal bacteria during the period of massive under-ice development of dinoflagellate Gymnodinium baicalense was studied. During the ice-covered period in 2013, both the abundance and biomass of G. baicalense were several orders of magnitude higher than the values for previous years, the maximum values were 8.9 × 10⁶ cells/L and 405 g/m³, respectively. The taxonomic structure of bacterial communities was determined using the data obtained by 454 pyrosequencing (Roche) with Mothur 1.19.0. Predominance of three phyla was revealed: Bacteroidetes, Proteobacteria, and Actinobacteria. Massive dinoflagellate development resulted in a considerable decrease in the richness and diversity of bacterial communities compared to the results of the earlier long-term studies.