Size dependence of growth and photosynthesis in diatoms: a synthesis

Abstract

The dependence of growth and photosythesis on cell size in diatoms is evaluated in terms of an energy-balance model of microalgal physiology. Based on a review of available observations it appears that cell size can account for much of the interspecific variability in maximum growth rate (p,) and in optical absorption cross-section (ach,)B. oth CL, and a,,, decrease with increases in cell size. Cell size does not appear to influence the chlorophyll a:carbon ratio, the quantum efficiency of photosynthesis nor the photon flux density (PFD) at which growth rate is llght-saturated. Available observations do not allow an evaluation of the size dependence of maintenance metabolic rates or the PFD at which light compensation of growth occurs. This analysis confirms the competitive advantage of small cell size of microalgae under nutrient-sufficient conditions at both light-saturating and light-limiting growth rates to the extent that small-celled diatoms have enhanced catalytic efficiencies of growth and light absorption.