An analytical study of three characteristic forms of light-forced primary production in aquatic ecosystems.

Primary production in aquatic ecosystems is largely a function of irradiance, with photosynthetic response to light ranging from "light saturation" through "asymptotic inhibition" to "complete inhibition". Equations describing these three basic types of response have been solved to yield instantaneous integral photosynthesis as a function of irradiance, chlorophyll a concentration, light extinction coefficient, and photosynthetic capacity of the phytoplankton at optimum irradiance. These results were used to calculate diurnal trends of instantaneous integral photosynthesis for several different latitudes and seasons and finally day-rate integrals of photosynthesis as a function of time of year at several latitudes. The final results allow rapid evaluation of the entire northern hemisphere in terms of potential sites for controlled aqua-culture facilities, using basic phytoplankton and water properties and standardized weather data. Results for the "complete inhibition" case can be used to evaluate both net and gross photosynthesis.