Expedition on board RV "G.Yu. Vereshchagin", July 12-22, 2018.

The expedition was carried out within the framework of the programs "Studies of the Effect of Mud Volcanoes and Methane Seeps on Biological Communities of the Abyssal Zone of Lake Baikal" and "Microorganisms of the Deep Biosphere of Lake Baikal and Their Role in Hydrocarbon Generation" on board RV "G.Yu. Vereshchagin", July 12-22, 2018 in the areas of Southern and Central Baikal.

The aim of the expedition was to study cycles of methane and other hydrocarbons in the zones of underwater discharge and their role in the formation of biological communities in the abyssal area of Lake Baikal.

Samples of water and bottom sediments were collected in the areas of Southern and Central Baikal for: 1) studies of the composition of major ions and gases in pore waters; 2) survey of the intensity of processes of primary production, heterotrophic assimilation of carbon dioxide, sulfate reduction, oxidation and formation of methane in the water column and bottom sediments; 3) studies of natural microbial community diversity using platforms of highly productive sequencing; 4) experimental studies of benthic microbial communities providing hydrocarbon cycles and anaerobic degradation of biopolymers, aerobic and anaerobic oxidation of methane and oil; 5) studies of density of benthic communities in these areas with identification of dominant groups of animals taking into consideration geological structure and discharging gas-bearing fluid; 6) identification of symbiotic microorganisms of benthic animals and their trophic status.

The researchers collected 109 water samples, 20 sediment cores and 16 grabs with bottom sediments at 18 sites, as well as benthic animals using a dredge.

To compare data on the effect of organic substance fluxes on the cycle of methane and microbial processes, the samples were collected in the areas of shallow gas discharges at the bottom of Lake Baikal and in the zones with increased anthropogenic impact.