The First Record of Thalassiosira angulata (Bacillariophyceae) Bloom in the White Sea: Spatial Distribution and Associated Species

Abstract

Species composition and biomass of phytoplankton (B_sum), concentration of chlorophyll “a” and nutrients, and hydrophysical conditions were studied on July 5–12, 2011, at 29 stations in the White Sea. The chlorophyll “a” concentration and B_sum in the surface water layer corresponded to the level of phytoplankton bloom (>1 mg/m³ and >30 mg C/m³, respectively), except for two stations. For the first time, the dominance of diatom Thalassiosira angulata by biomass was recorded for a vast area of the White Sea; in the surface layer, the abundance and biomass of this species reached up to 24 × 10³ cells/L and 34.56 mg C/m³, respectively. Even higher values (179 × 10³ cells/L and 258 mg C/m³) were noted at one of the coastal stations at a 3-m depth. The stability of the water column (positive relation) and salinity (negative relation) were the main factors affecting the spatial variability of the T. angulata biomass.