The Structure of Fungal Communities of the Kara Sea in Silty Sediments of Different Granulometric Composition

The structure of fungal assemblages has been studied in silty sediments of the southwestern Kara Sea at 11 stations in November 2023. Using cultivation method, 23 fungal species from six genera, five families, five orders, four classes, and two phyla (Ascomycota and Mucoromycota), as well as unidentified yeasts and sterile mycelium from three morphotypes, were isolated. In terms of species richness, representatives of the class Eurotiomycetes (12 species of Penicillium and 5 species of Aspergillus) were dominant. For the first time, the structure of fungal assemblages was analyzed depending on a combination of abiotic factors: sampling depth, average particle diameter, the percentage of sand, silt, and clay fractions, organic matter (OM), and organic carbon (Corg). Based on these abiotic parameters, two groups of stations were identified: group I (shallow water areas, depths of 21 and 26 m, silty-sand sediments) and group II (deep water areas, depth ≥122 m, silty-pelitic ooze). The abundance and morphotype diversity of filamentous fungi at shallow-water stations were 2.4–4-fold higher than at deep-water stations. The following factors were shown to influence the structure, clay fraction, OM, Corg, and mean particle diameter.