Recent studies have revealed how the freshwater biota of Lake Baikal responds to climate change and anthropogenic impacts. We studied phyto- and zooplankton, as well as phyto- and zoobenthos, in the open coastal waters of the southern basin of the lake and of Listvennichny Bay. A total of 180 aquatic organism taxa were recorded. The response of the Baikal ecosystem to climate change can be traced by changes in the species composition of planktonic communities of the lake’s open coasts in summer. The key species were thermophilic the Anabaena lemmermannii P. Richt. (F_ij = +0.7) blue-green algae, the Asplanchna priodonta Gosse (F_ij = +0.6) rotifers in 2016, the Rhodomonas pusilla (Bachm.) Javorn. (F_ij = +0.5) cold-loving algae, and the Cyclops kolensis Lilljeborg (F_ij = +0.9) copepods in the past century. The proportion of Chlorophyta decreased from 63% to 17%; the Cyanophyta increased from 3% to 11% in the total biomass of phytoplankton; and the proportion of Cladocera and Rotifera increased to 26% and 11% in the biomass of zooplankton, respectively. Human activity makes an additional contribution to the eutrophication of coastal waters. The Dinobryon species, the cosmopolitan Asterionella formosa Hass. and Fragilaria radians Kütz., dominated phytoplankton, and filamentous algae, Spirogyra, dominated at the bottom in the area with anthropogenic impact. The trophic level was higher than at the unaffected background site: the saprobity index varied from 1.45 to 2.17; the ratio of eutrophic species to oligotrophic species ranged from 1:2 to 3:1, and the ratio of mesosaprobiont biomass to endemics biomass ranged from 2:1 to 7:1. Currently, the boundaries of eutrophication zones of shallow waters in Lake Baikal are expanding, and its coastal zone has acquired features typical of freshwater bodies of the eutrophic type.

The spatial distribution of Elodea canadensis Mich. was studied in the southern and central basins of Lake Baikal in 2006–2009. E. canadensis has naturalized successfully in the lake ecosystem. It coexists here with the indigenous submerged macrophytes under its canopy or forms either rarefied undergrowth or separate monomorphic spots. The invasion of this species into the Lake Baikal ecosystems has led to the structure reorganization of indigenous phytocenoses in several bays of the Maloye More. Currently, E. canadensis dominates in phytocenoses of Khuzhir-Nugo Bay; and Myriophyllum spicatum L., in Kurkutskaya Bay. The trend of the population dynamics in these two species was observed, common to the Lake Baikal and other fresh-water ecosystems, where a decrease in E. canadensis abundance is followed by an increase in M. spicatum abundance. The abundance and distribution of the associated biota of submerged macrophytes was studied. It was found that the phytoepiphytone community of E. canadensis differed significantly compared to the indigenous submerged macrophytes inhabiting the same biotope. Low values of Shannon-Weaver index, high abundance of one species (Cocconeis placentula var. placentula), and low evenness are evidence of community vulnerability and unfavorable conditions of its habitat on E. canadensis. That is why, when E. canadensis forms thickets, a decrease in biodiversity of phytoepiphytone and dominance of Cocconeis species are usually observed. Structural changes of phytocenoses influence on the abundance of invertebrates. Epibiota of Elodea canadensis differs significantly from that on Myriophyllum spicatum and bottom fauna, which the results of principal component analysis and ANOVA confirm.

The taxonomic diversity of hydrobionts from Listvennichny Bay was studied by DNA metabarcoding. The sequencing of a gene fragment (313 bp) of mitochondrial DNA encoding the first subunit of cytochrome c oxidase (COI) was performed using an Illumina MiSeq after amplification from internal primers (mlCOIintF, jgHCO2198). Bioinformatic analysis of COI reads revealed 187 OTUs (operational taxonomic units), among which Arthropoda, Annelida, Mollusca, and Plathelminthes prevail, accounting for 52, 30, 10, and 4%, respectively. In general, the species diversity of the bay’s fauna by the Shannon index (3.2 bits) is comparable to other areas of Lake Baikal. The most diverse composition of taxa (22 OTUs) of the species rank falls on the larvae of chironomids, which confirms the effectiveness of the method for identifying juvenile stages of invertebrates. The research results are the first step toward improving the system of hydrobiological monitoring of Lake Baikal based on the synthesis of molecular genetic diagnostics of invertebrates and classical morphological taxonomy.

The diversity of macroinvertebrates, the structure of their communities in Bolshiye Koty Bay (Lake Baikal) was studied by a DNA metabarcoding approach using an Illumina MiSeq system. Internal primer mlCOIintF in combination with jgHCO2198 of the Folmer fragment of the COI gene were used for macroinvertebrate metabarcoding. A total of 118009 reads of the COI gene fragment (at least 313 bp in length) were obtained. The correlation of the Spearman coefficient (S = 0.6, p < 0.05) with the abundance of macroinvertebrates in the samples before DNA extraction showed that the number of reads can serve as an indirect characteristic of the abundance of a species (operational taxonomic unit, OTU). 115 OTUs belonging to the higher taxa of macroinvertebrates were identified: Porifera, 1; Platyhelminthes, 3; Annelida, 38; Arthropoda, 55; Mollusca, 18. At a high level of resolution (with homology with GenBank reference sequences ≥ 95 %, coverage ≥ 90 %), 46 taxa of macroinvertebrates comprising three communities were registered: one dominated by molluscs (Choanomphalus conf. maacki) and two dominated by chironomids (Orthocladius grega rius Linev., Sergentia baicalensis Tshern.). Communities are characterized by low species diversity according to Shannon (from 0.7 to 1.2 bits), high concentration of dominance according to Simpson (from 0.5 to 0.7) and low evenness according to Pielou (from 0.3 to 0.4). Dominants and subdominants in the communities account for 91 to 96 % of COI gene fragment reads. The spatial distribution of the dominant species identified in the communities is influenced by the geomorphological features of the bottom and the composition of sediments in the area studied. The approach proposed for studying the structure of macroinvertebrate communities based on DNA metabarcoding and next generation sequencing can be recommended for express assessment of the state of aquatic ecosystems in the monitoring.

The population structure of endemic species Sergentia baicalensis Tshern. (Diptera, Chironomidae) from Lake Baikal was studied using the first subunit of the cytochrome c oxidase mitochondrial gene (...

The evolutionary history of two species belonging to the genus Orthocladius van der Wulp, 1874 van der Wulp, F.M. (1874), ‘Dipterologische Aanteekneningen’, Tijdschrift voor Entomologie, 17, 109–148. [Google Scholar] (Diptera: Chironomidae) from Lake Baikal was investigated using the mitochondrial gene coding the first subunit of the cytochrome c oxidase (CO1 mtDNA). The phylogenetic analysis indicated that the Baikal Orthocladius species were divided into two well-defined clades where O. (Orthocladius) gregarius Linevitsh, 1970 was a sister species to Palaearctic O. (Orthocladius) nitidoscutellatus Lundstrom, 1915 and the O. (Eudactylocladius) sp. was a sister species to Nearctic O. (Eudactylocladius) subletteorum Cranston, 1998 Сranston, P.S. (1998), ‘Nearctic Orthocladius Subgenus Eudactylocladius Revised (Diptera: Chironomidae)’, Journal of the Kansas Entomological Society, 71(3), 272–295. [Web of Science ®] [Google Scholar] . Divergence time estimates indicated that these species had been evolving independently for about 18 Ma (Neogene, Early Miocene), while emergence of the most recent common ancestors of the modern O. (Orthocladius) gregarius and O. (Eudactylocladius) sp. was dated to about 3.5 Ma (Neogene, Pliocene). The evolution of Baikal orthoclads occurred from the rheophilic fauna under conditions of global climate change during the geological history of the Baikal Depression in the Tertiary Period.