RESUMO

The effect of light intensity and light-dark cycles (12 : 12) on the percentage of cells with diploid DNA in mono-specific cultures of microalgae Phaeodactylum tricornutum Bohlin, Nitzschia sp. 3, Prorocentrum pusillum Dodge, P. cordatum Schiller, and Isochrysis galbana Schiller was studied by flow cytometry. It was shown that the proportion of cells in the G2 phase was significantly higher under high-intensity lighting. In all species a strong correlation (r² > 0.98) was revealed between the potential growth rate of algae determined by the mitotic index, and their specific production, as measured by the increase in number. Flow cytometry was use for cell cycle analysis and evaluation of potential growth rates of picophytoplankton and nanophytoplankton of the Black Sea. At three stations in Sevastopol and Quarantine bays potential growth rates of pico-and nanophytoplankton in the surface layer was 0.2−1.0 d⁻¹ (year-round sampling in 2010 at 3 stations, a total of 120 samples). Maximum values of this parameter corresponded to the number of annual peaks of the phytoplankton number.