Physiological regulatory mechanisms of the marine phytoplankton community structure

Field studies, experiments, and mathematical modeling showed that seasonal cycle of the Black Sea phytoplankton is regulated by three major physiological mechanisms. The first mechanism is a high specific growth rate, high values of the uptake rate and the half-saturation constant of the uptake of the limiting nutrient. It operates in spring when small-cell diatoms Pseudo-nitzschia pseudodelicatissima and Chaetoceros curvisetus grow actively. The second mechanism is notable for relatively low rates of growth, the uptake rate, and half-saturation constant; it operates mainly at the end of spring and in the beginning of summer when coccolithophore Emiliania huxleyi is in abundance. The third mechanism prevails in summer and autumn when the mass of water is regularly agitated by wind and waves with domination of macrocellular diatoms Proboscia alata and Pseudosolenia calcar-avis. The cells of these algae can accumulate nutrient ensuring numerous divisions.