Light Harvesting Among Photosynthetic Organisms

Examination of light absorption by photosynthetic tissues of 156 specimens from 128 species of chlorophyll a containing photosynthetic organisms, ranging from single-celled cyanobacteria to trees, confirmed the existence of a universal law involving the asymptotic increase in light absorption with increasing chlorophyll a density. The chlorophyll a concentration of photosynthetic tissues decreased as the tissues become thicker, thereby avoiding high areal chlorophyll a density and inefficient light absorption. Light absorption per unit photosynthetic tissue weight was strongly, linearly related to the chlorophyll a concentration, explaining the lower growth rates and higher light requirements of thick, compared to thin photosynthetic organisms and the dominance of thin photosynthetic organisms in shaded environments (...)