Expedition on the R/V Titov from May 29 to June 10, 2026
From May 29 to June 10, 2026, complex field works on board R/V Titov were conducted within the State Assignments:
- № FWSR-2026-0015 “Influence of Abiotic Factors of Lake Baikal and Adjacent Territories of Eastern Siberia on the Adaptation and Biodiversity of Aquatic Organisms at the Level of Ecological, Biochemical and Molecular Genetic Characteristics” (led by Fedotov A.P.) to continue a series of works to monitor the disease state of the Baikal endemic sponges, to research the problem of mass morbidity and death of Baikal sponges in the shallow waters of Lake Baikal.
- № FWSR-2026-0004 “Complex study of viral and bacterial communities of Lake Baikal: structural-functional and genetic organization, dynamics and transformation of microbiocenoses under the influence of various environmental factors” (led by Belykh O.I.) to clarify the data on the species diversity and distribution of benthic cyanobacteria of Lake Baikal and obtain cyanobacteria cultures for further research.
During the expedition, underwater mapping was done (areal projective cover of the bottom with various types of sponges). Simultaneously, from the framework, quantitative collection of samples of Baikal endemic sponges was carried out for species diversity and infection with various diseases in zones predated transects and polygons: Varnachka, Cape Elokhin, Listvennichny Bay. A total of five transects were worked out, more than 380 samples of sponges were collected at depths of 2-35 m, sampling was carried out using light diving equipment. For each sample, photofixation was performed and samples were fixed for species identification by spicule and skeleton analysis. Underwater photography and video recording of reference sponges placed previously in 2015–2016 were carried out during the expedition to the Circum-Baikal Railway station Ulanovo, the source of the river Angara, and Cape Elokhin.
To obtain continuous year-round data on the temperature regime in the shallow zone of the lake in the bottom layer (year-round recording of temperatures at sections at stations in different areas of Lake Baikal, at depths of 6, 12, 15 and 30 m), information was taken, read, and new temperature loggers were installed.
We collected 52 samples of benthic biofilms from various substrates in three basins of the lake for further research to clarify the data on the species diversity and distribution of benthic cyanobacteria of Lake Baikal and to obtain cultures of cyanobacteria. We researched foulings developing on substrates of both biotic origin - diseased branched and suberose sponges, submerged macrophytes, and abiotic - silt, sand, stones, rock outcrops, wood, ropes, plastic. Cyanobacterial biofilms consisting mainly of Tychonema litorale, less often with an admixture of Limnofasciculus baicalensis, Oscillatoria sancta и Tolypothrix distorta. were observed on diseased sponges. Nine species of cyanobacteria have been previously identified in the foulings of rocky substrates. The dominant species forming foulings were Tolypothrix distorta, Oscillatoria sancta, Limnofasciculus baicalensis, Leptolyngbya sp., Phormidium sp., Tychonema litorale and Rivularia rufescence, all zones of the lake, colonies of Nostoc spp. were noted
On July 1-3, RV Titov was able to reach only Bolshaya Kosa in Northern Baikal due to the not typical ice situation for this season. RV Titov faced a continuous field ice, because of this, a transect on the east coast near Cape Turali was not worked out.
