The numerous studies of marine fungi in Arctic ecosystems show that fungi can play a significant role in the organic cycle in both pelagic biotopes and in sea ice and bottom sediments.
As part of the environmental monitoring of the Northern Sea Route, we studied samples collected in the Kara, Laptev, East Siberian and Chukchi seas. One of the stations was in the estuarine zone of the Gulf of Ob. Surface and bottom water samples were analyzed at all stations. Metagenomic analysis of ITS1-ITS2 sequences amplified using specific fungal primers was performed.
A total of 248 OTUs belonging to the Fungi kingdom and 6 divisions were found. The largest number of identified species belonged to the Basidiomycota, slightly less to the Ascomycota. In terms of geographical distribution, the estuarine region has the maximum species richness, the Chukchi Sea is the least, despite the fact that species from the Pacific region are present there. In comparison of the species composition of surface and bottom waters, including estuarine area, the top taxa are the same. Unique taxa for bottom waters are 98, unique taxa for the surface water are 57, and there are 93 common species. In first place, both on the surface and in the bottom, is an unidentified OTU of Fungi, which requires further study. One of the most common species is Cladosporium cladosporioides, previously discovered in studies of fungi isolated on nutrient media (Bubnova, Konovalova, 2019). At the estuarine station, both in the bottom and on the surface, there is a large number of chytridiomycetes species of genus  Betamyces and the OTUs related to Rozellomycotina. The species composition of the bottom layer on the shelf of the Arctic seas are similar to each other, while the surface ones are affected by currents and differ. As a result of monitoring studies, a large number of different environmental parameters were analyzed, and patterns in the distribution of marine fungi communities in the Arctic seas were discovered.
 

Arctic, Kara Sea, pelagic fungi, environmental parameters