Partitioning light spectra: Adaptive stratification of phytobenthic communities in Antarctic lakes

Competition for light has an important influence for phototrophic community structures, especially, along the perpendicular axis. Here we develop a mathematical model for perpendicular community buildup of phototrophic species that differ in light absorption spectra and compete for incident light. Details of photon capture efficiencies and the roles of photoinhibition were taken into consideration to define species' fitness. Our theory showed that, if there is strong light irradiation due, for example, to the high transparency of the water in freshwater lakes in Antarctica, protective absorption of light should occur near the surface and photosynthetic absorption should gradually increase with depth. These results were then validated in comparison with observed vertical distributions of pigments in phytobenthic-mat communities from Antarctic lakes.