Limnological expedition aboard the RV Papanin on July 15-18, 2026

On July 15-18, 2026, within the state assignment “The 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 environmental, biochemical and molecular genetic characteristics,” field works were carried out aboard the RV Papanin.

The purpose of the work was to study the current chemical composition of water, the abundance and species diversity of phyto- and bacterioplankton of small tributaries of Southern Baikal to assess long-term changes resulting from climatic and anthropogenic factors.

During the expedition, water samples were collected from the near-mouth areas of 60 tributaries. Water samples were collected for chemical analysis (pH, electrical conductivity, oxygen content, concentrations of major ions, biogenic elements, trace components, and organic matter) and microbiological analysis (abundance of organotrophic bacteria, total and thermotolerant coliform bacteria, E. coli, and enterococci), as well as for determining the abundance and species diversity of phytoplankton. The lake's small tributaries remain poorly studied. The most comprehensive data on the chemical composition of their waters were collected in the mid 20th century (Votintsev et al., 1963), and for most of these rivers, no information on bacterio and phytoplankton is available. The data obtained during the expedition will expand our knowledge of the chemical and biological composition of river waters flowing into the southern basin of Lake Baikal and will help identify possible changes that have occurred over the past 60–70 years under the influence of natural and anthropogenic factors.