Species Composition and Abundance of Microalgae in Sea Ice of Amur Bay, Sea of Japan, in 2021

Research on the vertical distribution of microalgae in ice cores was conducted in Amur Bay (February 2021), an area where the sea ice biota has remained largely unstudied. A total of 51 taxa of microalgae from 6 classes were found, 42 of which were identified to the species level. An increase in the number of species is observed from the upper to the lower layers; diversity increased from the beginning to the end of the study period as well. The cell number varied from 20 to 17 000 cells/mL. The maximum concentrations were noted in the lower 5 cm of ice (interface layer). Diatoms dominated: Chaetoceros socialis f. radians (up to 15 000 cells/mL), Detonula confervacea (up to 12 900 cells/mL), Navicula granii (up to 2,800 cells/mL), N. septentrionalis (up to 600 cells/mL), Nitzschia frigida (up to 2400 cells/mL), and Nitzschia sp. (up to 2400 cells/mL). Statistical analysis of the species composition using Sorensen’s resemblance allowed us to identify two communities inhabiting the upper (0–20 cm) and lower (20–50 cm) ice layers.