Winter bloom of the diatom Nitzschia delicatula in the open waters of the Black Sea

Abstract

Cell numbers were as high as 6×109 cells m-3 and biomass was as high as 2.7 g m-3. The frequency of dividing cells in the population varied from zero to 37%. On average, for phytoplankton communities predominantly made up of N. delicatula, estimated production was 2.3 times as high as primary production measured by the 14C technique. Vertical changes of chlorophyll cell content were used as an index of the mixing in phytoplankton assemblages. While phytoplankton biomass was inversely related to the mixed layer depth, population growth rate depended upon mixing activity in the upper water column. -from Author