Pavel R. Makarevich

This study builds on our prior research to refine the methodology for estimating marine primary production (PP) in the Barents Sea. It examines how abiotic factors—vertical mixing and horizontal advection—affect nutrient concentrations in the euphotic zone and subsequently influence PP. The analysis utilized salinity and nutrient data from the World Ocean Atlas (NCEI WOA). The δ¹⁸O parameter, used in conjunction with salinity, helped quantify the proportion of water from different origins. The results revealed a spatial heterogeneity in nutrient transport, identifying zones of both synchronous and asynchronous nutrient flows. Asynchronous flow was characterized by the removal of phosphorus and silicon alongside the influx of nitrogen. A significant correlation between these physical fluxes and PP was observed in the eastern part of the sea, where asynchronous flow prevails. Our calculations indicate that nitrogen influx increases PP by an average of 38% as high as 68%. The simultaneous fluxes of silicon and phosphorus showed no statistically significant effect. The study concludes that nitrogen is the primary limiting factor for PP in this region.

The results of studies of the biotopic diversity of diatom communities in pelagic, bottom and ice communities of the southeastern part of the Barents Sea are presented.

During expeditionary work on the research vessel Dalniye Zelentsy in 2024, multidisciplinary oceanographic studies of the Arctic nature were carried out in the waters of the Barents, Kara, and Greenland seas and the Arctic Ocean. Work was carried out to assess the current state and analyze changes occurring in the structure of pelagic, benthic, and ichthyofauna communities under the influence of climatic and anthropogenic factors. Qualitatively new information was obtained on the functioning of marine Arctic ecosystems in polar night conditions.

In the course of conducted studies the influence of climatic fluctuations on the structural and production characteristics of the pelagic zone was determined using both long-term data series on the chl-а content in situ and direct taxonomic study of the pelagic phytocenosis in local areas of the Barents Sea during spring activation. The timing of the onset, dynamics of development and structural organization of spring phytoplankton bloom were determined. A technique was developed for using δ18O isotope ratios to assess individual stoichiometric ratios and primary production of water areas. New information was obtained on the spring pelagic complex of zooplankton in the areas of the Arctic archipelago of Novaya Zemlya. The first unique studies of bacterio- and virioplankton were conducted in previously unstudied coastal areas of the Novaya Zemlya archipelago. Seasonal hydrochemical parameters of the water masses of the Kola Bay are given.

The results of multidisciplinary marine scientific expeditionary work on studying the nature of the Arctic seas by the Murmansk Marine Biological Institute of the Russian Academy of Sciences in the period 2020–2024 are presented. As a result of the research work, a large amount of original information on the current state of marine Arctic ecosystems was obtained. The collected material will supplement the basic foundation of all theoretical and practical developments carried out at the institute.

During a marine expedition of the R/V Dalniye Zelentsy in summer 2024, the current state of the fishing communities of the eastern Barents Sea and western Kara Sea was analyzed. In the northeast Kara Sea, a unique ichthyological survey was carried out using a coordinate grid replicating research in 1930–1935. Ichthyological trawling was also carried out in the Barents and Kara seas along of the Novaya Zemlya archipelago. As a result, new data have been obtained on the species composition, abundance, biomass, distribution, and condition of ichthyofauna in these areas.

In 2025, the Murmansk Marine Biological Institute of the Russian Academy of Sciences, the northernmost academic institution in Russia, celebrated its 90th anniversary. The article briefly describes the history of the institute and its main scientific achievements in such areas as marine biology, oceanography, marine geology and ecology.

In November–December 2023, an expedition of the Murmansk Marine Biological Institute of the Russian Academy of Sciences, on board the R/V Dalnie Zelentsy conducted hydrological, hydrochemical, hydrobiological, and radioecological research in the area west of the Spitsbergen archipelago and on the century-old Kola Meridian transect in the Barents Sea. New data on thermohaline conditions, plankton, and radionuclides during the polar night were obtained at 54 oceanographic and hydrobiological stations. Positive water temperature anomalies show continuation of the warm climate cycle in the Barents Sea. The revealed activation of florogenesis in the western Barents Sea is probably caused by advection of Atlantic waters. Based on an analysis of the population structure of Calanus finmarchicus and C. glacialis in the waters of Spitsbergen, a specific feature of seasonal size variability of species in summer and winter was determined.

Integrated marine studies were carried out by researchers at the Murmansk Marine Biological Institute, Russian Academy of Sciences, during an August 2023 cruise on the R/V Dalnie Zelentsy within the national project “Science and Universities.” The studies included CTD sampling; hydrological, hydrochemical, hydrobiological, ichthyological, and radioecologic studies; and observations of marine birds and mammals. The outcome of the cruise was new data on the reference state of the eastern Barents Sea ecosystem.

This study provides a rather new approach to research on a portion of general biological production of marine ecosystems, namely on primary production. The methodology presented consists of two blocks of techniques. The hydrological block provides for an estimate of the amounts of basic water masses, the estimate being based on the salinity and δ¹⁸O stable isotope value. The techniques of the ecosystem block provide for a calculation of primary production based on the water mass composition, nutrients concentrations in the cores of the water masses, and changes in nutrients reserves. The rate of the nutrients reserve change is corrected by the non-productive component caused by the inflow or outflow of the nutrient as a result of advection or exchange with underlying layers. Another correction is related to nutrient regeneration going in parallel to photosynthesis. The technique was tested and verified in the waters around the Svalbard archipelago. By using a combination of δ¹⁸О isotope parameter (with an intention to add δ²H in the future), salinity, and nutrients composition, the present methodology allows to consider the domain of the marine ecosystem comprising its hydrological, hydrochemical, and hydrobiological (phytoplankton) processes as a single system of their relationships. Barents Sea, nutrients, phytoplankton, primary production, new production, photosynthesis