Seagrass productivity: the effect of light on carbon uptake

Abstract

Seagrass species are very similar. It is expected that these similarities extend to their productivity, especially their response of carbon uptake to light. Experiments quantifying the rate of productivity, estimated by ¹⁴C-carbon uptake as a function of light, measured as irradiance, yielded light-response curves for six North American species. High maximum rates, saturation irradiances, half-saturation irradiances, and the shapes of the curves were essentially the same, indicating that seagrass species share a specific type of production system. Therefore differences in their productivities are not caused by species-specific factors but environmental factors or artifacts of technique. Differences in maximum rates resulted most likely from differences in light quantity, physiological stress, or ecological roles in succession. Superimposed on the general pattern of seagrass productivity were modifications caused by environmental and ecological conditions of the habitats. Application of models based on the Michaelis-Menton and Steele’s equations yielded predictive understanding of primary production.