Expedition on the board R/V “Papanin” on July 01-10, 2023

On July 01-10, 2023 the field works on the board R/V “Papanin” were carried out within the State assignments “Comprehensive studies of the Lake Baikal coastal zone: long-term dynamics of communities under the influence of various environmental factors and biodiversity; causes and consequences of negative environmental processes” (0279-2021-0007) (led by O.A. Timoshkin), “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) (led by A.P. Fedotov) and “From the cell to the ecosystem: Investigation of the ultrastructure of hydrobionts and their communities in the evolutionary and ecological aspect by methods of cell biology and genomics” (0279-2021-0008) (led by Ye.V. Likhoshway). The staff of LIN SB RAS and IEC SB RAS participated in the expedition.

The aim of the work is: integral studies of gastropod mollusks and nematodes, dominant groups of benthos in different biotopes of Lake Baikal, as well as species composition of benthic diatom algae that locate on gastropod shell and form unique food “pastures” for various invertebrates; description of underwater landscapes, identification of habitat peculiarities of benthic animals.

Today, the northern basin of Lake Baikal is the most poorly researched among the studied benthos groups. The field works were carried out in 13 areas of the northern part of the lake (Shartlay Cape, Solontsovaya Bay, Bolshoy Solontsovy Cape, Sagan-Moryan Cape, Yuzhny Kedrovy Cape, Zasechnaya Bay, Malaya Kosa Cape, Goryachinskaya Bay, Ayaya Bay, Tukalaragda Bay, Kabaniy Cape, Sosnovskaya Banka, Khoboy Cape).

The main research was carried out using Rovbilder RB-300 (ROV) that able to record on video landscapes of bottom with animals present, take measurements of objects and capture samples of soil and invertebrates to a depth of 200 m. The robot is also equipped with an underwater hydroacoustic navigation system that receives an acoustic signal with geographic coordinates from sensors located on four buoys forming a navigation network. It enables to locate the vehicle underwater, and therefore record the ROV`s way track.

Benthos samples were collected by ROV and dredge. The collected material is currently being processed for further comprehensive ecological, morphological and molecular genetic analysis.

During the expedition, previously unknown shows of liquefied clay were found on the bottom surface like "mud volcanism" with traces of degassing. Ruptural deformations of the bottom with traces of liquefied sediments were found in Malaya Kosa Bay and Goryachinskaya Bay in the Northern Baikal depression at depths of 105-153 meters. Rocks exposed in high-dipping extended ledges and in extruded rock masses are mainly represented by “cavernous” clays. In some places there are brows of boulder-pebble deposits locating down the slope. Spreading zones of “mud volcanism” are confined to the zones of dynamic influence of known ruptures that indicate their activity in recent times. In addition to obvious effusions of liquefied clay at depths of 157-162 m in Goryachinskaya Bay, cone-shaped structures with a size of ~ 5×5 cm with a crater in the apical part that indicate degassing were found in the soft muds. Similar structures were also detected in Solontsovaya Bay along the right lined ruptures opposite the paleoseismic dislocation of the same name. Large light brown-colored planaria (flatworms) 10-20 cm long, amphipods (~ 5 cm), gastropods (~ 3-5 cm), and cottoid fish were observed in this zone. Nematodes (roundworms), oligochaetes, chironomids, cyclops and harpacticids were mainly found among small invertebrates. Richness of fauna that is not found on neighboring areas of the flat bottom, and the previously identified (Golubev, 2007) increased values of heat flux in Solontsovaya Bay suggest the presence of specific conditions that create a favorable environment for the life of organisms of a different trophic level.

The results obtained indicate that the use of ROV in the Lake Baikal research is a promising method that opens up new opportunities in studying bottom landscapes.