Complex Circum-Baikal expedition on board the RV “Vereshchagin” from September 19 to October 02, 2022

The complex expeditionary works over the whole water area of Lake Baikal were carried out on board the RV “Vereshchagin” within the programmes “Study of seasonal and long-term transformations of the state of water bodies and watercourses in East Siberia in the context of climate change, geological environment and anthropogenic loads” (project № 0279-2021-0005) (directed by A. Fedotov), “Investigation of the advective and turbulent water exchange of Lake Baikal and its impact on the lake ecosystem, risks of catastrophic events” (project №0279-2021-0004) (directed by N. Granin), and «From cell to ecosystem: Research of the ultrastructure of hydrobionts and their communities in the evolutionary and ecological aspect by methods of cell biology and genomics», (project № 0279-2021-0008 ) (directed by Ye. Likhoshway).

The expedition is aimed to conduct a comprehensive monitoring of abiotic and biotic components of the Baikal ecosystem to identify patterns of their spatial and temporal dynamics, experimental study of mechanisms and processes affecting the distribution and cycling of the matter in the water column.

During the expedition, samples were taken at fixed depths from the surface to the bottom using the Carousel SBE-32 cassette-type sampler equipped with 25 bathometers of 5-liter volume each, according to the standard grid of stations of the longitudinal and transverse sections of the lake. Water samples were taken for chemical and metagenomic analysis as well as to study distribution and species composition of phytoplankton. Phyto- and zooplankton samples were collected with a Juday net. The works were carried out in three Baikal basins as well as in Barguzin Bay, Chivyrkuysky Bay and Maloye More Strait. Water samples were collected at 44 stations; using a Juday net – at 26 stations. Water samples for hydrochemical analysis were taken from six rivers: the Anga, the Sarma, the Barguzin, the Rel, the Tyya, and the Kichera. Hydrophysical measurements were conducted at 53 stations using a high-precision SBE-25 CTD-zond with additional sensors of dissolved oxygen and transparency.

With the main works along the course of the research vessel, the water surface temperature was recorded, and the gas bubble outlet was monitored using a hardware-software complex based on Furuno echo-sounder with recording the data of echograms.

The total number of samples:

• hydrochemical analysis – 253
• metagenomic analysis – 533
• phytoplankton – 32
• zooplankton – 65