Dependence of light‐saturated rates of algal photosynthesis on intracellular concentrations of phosphorus

Abstract

Specific rates of photosynthesis at saturating irradiances ( P opt ) by laboratory populations of Chlorella and Anabaena depend on intracellular phosphorus ( Q ). A hyperbolic model of the form P opt = P opt s (1− K Q / Q ) is used to describe this relationship for three measurements of biomass (cell number, cell volume, and chlorophyll a ). Chlorophyll a provides the most adequate fit to the model. When chlorophyll a is used as the measure of population size, both the maximal specific rate of photosynthesis ( P opt s ) and the subsistence cell quota ( K Q ) for Anabaena are much larger than for Chlorella . The model provides a conceptual basis for understanding the relationship between rates of photosynthesis and intracellular nutrients in populations of planktonic algae.