The assumptions and rationales of a computer model of phytoplankton population dynamics1

Abstract

Predictions of phytoplankton growth dynamics and nutrient assimilation by a computer simulation model are consistent with studies of field and laboratory populations. The model simulates population dynamics and gross physiology of phytoplankton species in the epilimnion of a lake where algal growth is subject to temperature, light, and nutrient constraints and includes luxury consumption, end‐product inhibition of both carbon fixation and nutrient uptake, and species‐specific differential efficiencies of nutrient assimilation. C: P, C: N, and N: P ratios of the algal cells respond to changes in external nutrient conditions, and nutrient storage by the cells permits biological effects of nutrient pulses to be evident long after assimilation of dissolved nutrients forces the pulses to decline. Species succession results when abundances of specific taxa decline due to such factors as sinking or grazing, which assume overriding importance when cell division rates are slowed by chemical or physical limitations. The physiological tenets and limiting assumptions of the model have been used to formulate patterns of competition among species for light and nutrients in natural systems and to predict temporal changes in plankton biomass and species composition.