ABSTRACT
A chemostat or a cyclostat culture is useful in phytoplankton ecology only to elucidate general physiological, biochemical, and genetic principles as related to ecology, rather than to reproduce the conditions existing in the natural environment. Rates of various differentiation processes leading to cell division are neither time independent nor steady state. Thus, in a cyclostat, the cell cycles of algae tend to be phased with the photocycle. Phytoplankton have evolved in and adapted to an environment in which light and dark alternate periodically, and various factors regulate their growth. Growth rates of phytoplankton are also directly related to cell quota or to the concentration of specific storage pools. The chapter shows that the integrated growth in phosphate-limited cyclostat cultures of Euglena gracilis follows the Droop growth model if cell quota is replaced by an average cell quota for the period. In large-scale outdoor continuous cultures of Chaetoceros sp., phased cell division was expressed only at high nutrient levels.
