ИСТИНА

Species composition and biomass of phytoplankton (Bsum), concentrations of chlorophyll “a” (Chl),and nutrients, and as well as hydrophysical conditions were studied from 5th to 12th of July, 5 to 12 July 2011 at 29 stations in the White Sea. With the exception of indicators for two stations in the surface layer of the water columnWith the exception of two stations in the surface layer, the values of chlorophyll “a”Chl and Bsum corresponded to the level of phytoplankton bloom (> 1 mg/m3 and > 30 mg C/m3, respectively). The biomass dominance of diatom Thalassiosira angulata was first noted in vast area of the White Sea, its abundance and biomass in the surface layer reached 24 ∙× 103 cells/l and 34.56 mg C/m3, respectively. Still higher values were noted at one of the coastal stations at a depth of 3 m (179∙ × 103 cells/l and 258 mg C/m3). The main factors responsible for the spatial variability of the T. angulata biomass were the stability of the water column (positive relation) and salinity (negative relation).