The main results of researches of laboratory of ichthyology of the MMBI RAS in the period from 2015 to 2019 are presented. Data on the ichthyofauna of bays and fjords of North-Eastern Greenland, spatial distribution of some species of the Cottidae, Liparidae and Zoarcidae families in the Arctic seas of Russia, as well as on the dynamics of fish diversity in the coastal and sub-coastal zones of Eastern Murmansk are provided. Quantitative data on Barents sea Polar cod productivity, bioenergetic and adaptations of boreal and Arctic fish species were obtained.Aspects of the morphology of the thymus of lumpfish larvae used in aquaculture to control parasitic crustaceans are considered.

This paper presents some research results of the plankton laboratory MMBI RAS over the past 5 years. One of the main directions was the study of the structure of zooplankton communities and an assessment of their productivity off the coast of the Kola Peninsula and in the coastal waters of the Svalbard archipelago.Analysis of the vast perennial material revealed the main features of the spatial distribution of phytoplankton in the water area of the Pechora Sea. In the ice edge zone for nano-, micro-and zooplankton, the presence of ice edge effect in different seasons of the year is shown. It has been shown that in the Barents Sea, the Polar Front is not the boundary between various pelagic phytocenoses. During the polar night, virio-, bacterio-, phyto-and zooplankton were studied. When studyingthe deep-sea Barents Sea shelf, an autochthonous community of microalgae was found, the lower distribution limit of which is 300 m isobath.

The results of algological researches of the Murmansk Marine Biological Institute for the period from 2015 till 2019 are presented with the following achievements. Analysis of the expeditionary samples revealed 79 species of algae macrophyte, rarely found at the Murman coast, among them 10 species were Chlorophyta, 33 –Phaeophyceae, 36 –Rhodophyta. A significant increase of the occurrence (presence) of Ulva lactuca L.at the Murmansk coast of the Barents Sea in 2009–2019 was noted, due to positive climatic anomalies caused by an increase of the influx of the Atlantic waters. It has been shown for the first time that the various morphological forms of the brown alga Fucus distichuslived on the littoral of the Murmansk coast of the Barents Sea are genetically homogeneous. The morphology of embryogenesis, early ontogenesis of F. distichusis described. It was determined that hydrostatic pressure (from 4 atm) negatively affects the development of spores of Alaria esculentaand Palmaria palmata, and can determine the lower boundary of algae growth. It was shown that a change in the activity of enzymes of the antioxidant system P. palmata: (catalase and superoxide dismutase) depending on the temperature of the environment) is one of the mechanisms of adaptation of algae to growth in the tidal zone and seasonal temperature fluctuations. There were revealed the negative effect of the red algae P. palmataon the growth of F. distichus, F. serratusand the positive effect of Fucus on the growth of P. palmata. A change in the seasonal concentration of 4 B vitamins was determined (riboflavin, pantothenic acid, nicotinic acid and pyridoxine) of P. palmata. Isolated vitamins take part in spore formation and can act as antioxidants. An electron microscopic analysis of the “young” multicellular sporophytes of Saccharina latissimarevealed the presence in cells of a developed photosynthetic reticulum, and a high partial mass of mitochondria, energy structures that apparently provide an intensive process of cell division at this stage of ontogenesis. The participation of florotannins in the regeneration of thallus of Fucus algae was demonstrated. The data on the quantitative and qualitative composition of cultivated and uncultivated epiphytic bacteria of Fucus algae from clean and oil polluted areas of coastal waters of the Barents Sea have been obtained.For the first time, the evidence base presents that morphologically and systematically various macrophyte algae, differing in structure and systematic affiliation, possess in their ability to form a symbiotic association with hydrocarbon-oxidizing bacteria, they show a pronounced ability to sorb and to destruct the oil products, which determines their significant role in bioremediation of coastal waters.

We examined the radioecological status of seawater from arctic seas currently used for coastal and offshore innovative industrial and socio-economic projects. We analyzed processes that affect the formation of the current radioecological background. We showed that the volumetric activity of man-made radionuclides in seawater has been steadily low over the past decade. We believe that this is caused by the general influence of global sources of radioactive contamination. Among them, atmospheric deposition and transoceanic transport are most significant. We determined a substantial difference between the concentration of 137Cs in seawater of the Barents and Kara seas and that in the Laptev and East Siberian seas. This difference is determined by the significant influence of polluted Atlantic water on the Barents and Kara seas and its far weaker impact on the Laptev and East Siberian seas. We found out regional and local patterns of the distribution of radionuclides in the environment of arctic seas, which are the most important for the study and development of the logistics network in the Russian Arctic in the light of the prospective development of the transport and resources of those seas.

The results of five-year studies (2015–2019) of the laboratory of zoobenthos MMBI RAS on the impact of environmental factors, climate change and pollution on the species diversity, structure and abundance of bottom fauna in the Barents Sea were considered. The abundance and diversity of bottom communities and taxocenoses were higher in the most warm Atlantic water masses. The warming of the Arctic contributes to increased diversity of the Barents Sea benthos, increased biological invasion in the northern seas, and maintenance of diversity in the polluted ecosystem of the Kola Bay. The technology of biomonitoring of climate change using littoral populations of invertebrates is proposed.

This paper presents the generalized results of experimental studies on the influence of electromagnetic fields and optical characteristics of the medium on the behavior of real seals conducted by the biotechnological systems laboratory of the MMBI RAS as part of the state task.

In 1960th, red king crab was intentionally introduced into the Barents Sea. This species has formed a new self-sustaining population. In Russian waters, the commercial fishery of red king crab was started in 2004. Non-indigenous status and high commercial value of the crab have led to growing interest in the study of its biology and ecology. Red king crab has been intensively studied by specialists of Murmansk Marine Biological Institute to evaluate the role of this crab in local benthic communities and provide a theoretic basis and important applications for fishery science. New data on the population dynamics, symbiotic relationships, feeding and reproduction of red king crab have been obtained from long-term studies in coastal waters of the Barents Sea. Significant results of these studies are presented in this review.

The most important results of research on seabirds parasitology conducted at the Murmansk Marine Biological Institute in 2015–2019 are presented. Causal relationships between the distribution of hosts and the spread of helminths are determined. Similarities and differences of parasitic systems in different geographical areas are established. A more complete understanding of the parasitic-host relationship between seabirds and their helminths is obtained. Direct and indirect impact of helminths on hosts at the physiological and biochemical levels are described.

In 2013–2019, observations on Arctic archipelagoes Novaya Zemlya and Franz-Josef Land were made. A series of multiannual monitoring of seabird colonies on the Murman coast (Kola Peninsula) were continued. The results show that large-scale negative effects on seabird populations mostly occur in areas of Atlantic water masses in the southwestern Barents Sea. On the coasts and islands ofMurman, considerable fluctuations of the number of kittiwakes and guillemots imposed on the general decreasing trend were noted. Within the Arctic water masses at Franz-Josef Land and Novaya Zemlya, the conditions of the colonies were more favorable. Geolocation data loggers helped to establish wintering and pre-breeding areas of kittiwakes and guillemots in the Barents Sea. Degradation of the seabird colonies is explained by oceanographic changes in the southern Barents Sea, along with the influence of integrative drivers such as food stock, i. e., presence and availability of capelin, and thermal conditions of the water masses determining its distribution in coastal waters.

The work reflects the results of many years of research on modern lithodynamics on the coasts of the Barents and White Seas,employees of the Murmansk Marine Biological Institute.