Vol 49, No 5 (2023)

Samples of macrophyte algae were collected from an ecotope of Kandalaksha Gulf, the White Sea. These algae were selected from substrates, storm wracks and after long-term storage in the soil, and they were assessed by indirect competitive enzyme immunoassay for the presence of low-molecular metabolites of micromycetes (mycotoxins). In Fucus distichus, F. serratus, F. vesiculosus, and Ascophyllum nodosum, the concentrations of all analyzed toxic substances from storm wracks were uniformly reduced compared to those in living thalli. For Laminaria digitata, Saccharina latissima and Ahnfeltia plicata, in living individuals of which mycotoxins were not found or were extremely rare, cases of contamination with citrinin, mycophenolic acid, emodin and sterigmatocystin were found in storm wracks. After 12 months of burial in soil F. distichus samples had only 9 components out of 16 analyzed. In F. serratus, F. vesiculosus, A. nodosum, and Pelvetia canaliculata, only emodin, mycophenolic acid, alternariol, and ergot alkaloids were determined.

The allelic diversity of the DQB gene of the major histocompatibility complex (MHC) in Atlantic walrus from the European part of the Arctic was analyzed for the first time. We studied animals from the haulouts located on the Franz Josef Land archipelago and near the northern tip of Novaya Zemlya. We demonstrated that there are significant differences for this locus between the two studied haulouts. Simultaneous analysis of microsatellite loci reveals a lower level of differentiation, and also suggest that animals from more than one spatial-geographical stock (population) gather at the summer haulout on Novaya Zemlya. It has been suggested that individuals with different MHC genotypes may prefer different feeding areas, regardless of the areas of residence during the breeding season.

The biological features of Atlantic cod in the coastal zones of the Murman for 1999–2006 were studied. The age composition, growth rate and maturation, feeding habits and structure of otoliths were analyzed. Histological and genetic studies were carried out. It was shown that young cod mainly lives and spawns in Western Murman bays. Older cod leaves the bays due to insufficient food supply. The growth rate of young coastal cod is comparable to that of cod in the open part of the Barents Sea. With age, the cod of open sea areas noticeably overtakes the cod that lives in the coastal zone in growth. It was noted that cod spawns in the bays with both coastal and Atlantic types of otoliths. Studies of genetic polymorphism indicate a high degree of genetic si-milarity between cod groups in the Norwegian and Barents Seas, which is evidenced under the influence of currents (branches of the Norwegian Atlantic Current, the Murmansk Coastal Current) and against the background of migrations at different stages of ontogeny of cod individuals from coastal and open water areas.

The influence of the average annual sea surface temperature (SST) on the development of horse mackerel Trachurus mediterraneus on the south-western Crimean shelf has been shown. The changes in the main indicators of the population and their relationship with the change in the average annual SST (0.055°C/year) in 2000–2020 have been identified. Against the background of the observed increase in SST in recent years, the state of the horse mackerel population has improved: there has been an increase in the average age and, accordingly, the proportion of larger, well-fed individuals, and, in general, the average size and weight of fish. It has been shown that according to the nature of the change in the average annual SST, three periods can be distinguished: 2000−2007, 2008−2013 and 2014−2020.

Five specimens of encysted trematode metacercariae of Pygidiopsis Looss, 1907, located outside the tissues of the host, in a free state, were found in the extrapaleal cavity of the gastropod mollusc Hydrobia acuta (Draparnaud, 1805) from Cossack Bay (Black Sea). A figure, an image, and measurements of excisted larvae were given.