RELATIONSHIP BETWEEN THE NUMBER OF DIVIDING AND NONDIVIDING CELLS OF CYANOBACTERIA IN NORTH ATLANTIC PICOPLANKTON¹

Abstract

ABSTRACT In the North Atlantic over a wide geographic region that includes various oceanic regimes and a temperature range from 10 to 22° C, an increase in the number of nondividing Synechococcus cells (X) was generally accompanied by a greater‐than‐proportional increase in the number of dividing cells (Y). As a result, the fraction of dividing cells (FDC = Y · (Y + X) −1 ) was positively related to population size (Y + X). Recognizing that FDC is generally greater in a rapidly growing population than in a slowly growing one, our empirical finding implies a positive correlation between specific growth rate and standing stock for Synechococcus. One notable exception occurred during winter (T < 5°C) in a eutrophic coastal embayment when a decrease in cell abundance was not matched by a decrease in FDC.