Diversity of Planktonic Bacteria in Durgun and Taishir Reservoirs (Western Mongolia)

This is the first report on the application of high-throughput sequencing of the 16S rRNA gene fragments for investigation of bacterioplankton diversity in two largest and relatively young reservoirs of Mongolia-Taishir, formed on the Zavkhan River, and Durgun, formed on the Chono Harayh Channel. A total of 145 phylotypes (with a cluster distance of 0.03) belonging to 18 phyla were identified in the communities. The share of OTUs that were not identified at the phylum level varied in the range of 0.6-3.0%. According to the ACE and CHAO1 diversity indices, bacterioplankton species richness was highest in the hypertrophic section of the Chono Harayh channel below the dam of the Durgun Hydropower Station and lowest in the mesotrophic section of the Zavkhan River above the Taishir Reservoir. According to the Shannon and Simpson indices, the species abundance of different species in the community characterized the mesotrophic and eutrophic pelagic zones of the Taishir and Durgun reservoirs, respectively, as areas with the most equality. The reservoir systems differed significantly in taxonomic diversity, as evidenced by the ratio of common and unique OTUs, but their representation was not uniform along the rivers.