Lake Baikal is the world's deepest lake, the largest body of freshwater and the habitat of endemic (unique to this area) animal species. How they have managed to adapt to the specific environmental conditions (high pressure at depth, specific light regime, limited and heterogeneous food resources) remains a hard-to-solve puzzle for biologists.

In their new research, Karelian biochemists and their Siberian colleagues will study the evolutionary, molecular-genetic and biochemical aspects of adaptation in deep-water fish species. In July, scientists from the Ecological Biochemistry Laboratory of the Institute of Biology (IB) KarRC RAS Viktor Voronin and Ekaterina Tushina participated in a multidisciplinary expedition on Lake Baikal on board the research vessel Professor A. A. Treskov. The work included collecting biological samples of animals that live at depths of more than two hundred meters: big and little Baikal oilfishes, sculpins, and other fishes.

— We traveled the whole of Baikal from south to north in 10 days. During the expedition we passed through and stopped over for sampling in unique places of Lake Baikal: Maloye Morye Strait at the Island of Olkhon, Ushkan Islands — one of the main haul-outs of Baikal seals, Chivyrkuisky Gulf, Tompuda, Khakusy and Ayaya bays, and other regions of the lake. We managed to collect samples from most of these sites. The exceptions were sanctuary areas, — tells Ekaterina Tushina, Principal Chemist at the Ecological Biochemistry Laboratory IB KarRC RAS.

— Fish were caught in a variety of ways, including bottom trawling and setting fishing nets. We conducted multiple trawlings at different depths and found unique fishes and invertebrates that live only in Baikal. In total, we collected more than 300 tissue samples of fish caught at different depths and in different parts of the lake. Sometimes, strong winds, vessel rolling and storms complicated our work, but then we tried not to pause. Despite the tight schedule, we found time to admire the amazing views of Lake Baikal, — added Viktor Voronin, Junior Researcher at the Ecological Biochemistry Laboratory IB KarRC RAS.

Fish adaptations to living in deep-water habitats of northern seas have been in the focus of attention for scientists at the Ecological Biochemistry Laboratory for more than seven years. Not so long ago, specialists from the laboratory started research on adaptations of deep-water fishes of the Atlantic sector of the Antarctic. To wit, the results of a study on the biochemical adaptations and nutritional value of a well-known commercial fish – beaked redfish of the Irminger Sea, were published in the Biomolecules Journal and the Journal of Marine Science and Engineering.

— Research on the adaptations to living in extreme environments, the trophic links between deep-water species and their ecological roles can have applications in dealing with sustainable use of natural resources and water ecosystem monitoring. For marine ecosystems, this is especially relevant in the context of active fishing and in making long-term resource forecasts, — explained Svetlana Murzina, Head of Ecological Biochemistry Laboratory IB KarRC RAS.

Previously, Karelian biochemists have successfully implemented similar studies in the northern seas of the North Atlantic (Irminger Sea). The laboratory team studied adaptations at the lipid metabolism level in members of common and widespread families: Myctophidae, Stomiidae and others. Even being very abundant and widespread, most of these fish species classify as by-catch - accidentally caught in nets during commercial trawling; however, they can be potentially useful in various areas of human economic activity: from processing into technical-grade products to the extraction of individual components for the development of new medical and feed formulas.

— Within the current study, we hope to be able to find and compare both general and specific mechanisms of adaptation of aquatic organisms to pressure changes in the sea and in the freshwater ecosystem of Baikal. We have a mighty scientific team, including our experienced colleagues - ichthyologists from the Baikal Museum of the RAS Siberian Branch Anna Etingova and Sergey Didorenko, genetics team led by Nikolai Myuge from the Russian Federal Research Institute of Fisheries and Oceanography, and ourselves. We are happy to note that in this summer expedition our laboratory was represented by young and talented scientists and specialists. The expedition was preceded by extensive planning and discussion, since proper organization of complex trawl operations for studying the impact of pressure on animals in the daily, deep-water regime requires a clear understanding, skills and efforts on the spot, — added Svetlana Murzina.

The results of scientific exploration will contribute to the conservation of the unique ecosystem of Lake Baikal, its species diversity and richness.