Аннотация:In this study 21 strains of Acremonium fuci were studied. Isolates were yielded from brown seaweeds and littoral soils of White and Barents seas. This species is widely distributed in arctic environments, especially in algal mycobiota. Results of experiments with culture conditions demonstrated that strains of A. fuci readilly assimilate algal polysaccharides and succesfully grow at temperature close to 0°C. Optimal medium salinity for A. fuci is 3%; nevertheless, studied isolates grow well in media with salinity levels from 2 to 10 %, that proves their tolerance to oscillating conditions in arctic intertidal zone. According to morphological data, all studied strains were subdivided into two groups accordingn to: I) shape and size of conidia; II) ability of cell wall grow in a marine water to fluorescence in UV light. Data of phylogenetic analysis of ITS and beta-tubuline sequences also support the morphology-based grouping of investigated strains. A comparison with the first description of A.fuci strongly supports the existence of a least two species. At present authors perform the search of the entire A. fuci genome for phylogenetically important characters and traits of adaptation to marine conditions.