Lidar in-situ study of sunlight regulation of phytoplankton photosynthetic activity and chlorophyll fluorescence

摘要

Mechanisms of solar illumination influence on phytoplankton chlorophyll-a fluorescence and photosynthetic activity were investigated in situ by means of lidar implementation of the pump-and-probe technique. It has been found that for subsurface phytoplankton the main mechanisms of sunlight regulation were photoinhibition of primary photosynthesis processes by excessive light, dominating at illuminations more than 40 klx, and `energy-dependent' fluorescence quenching, at illuminations 5 - 20 klx. The potential role of other regulating mechanisms (photophosphorylation of pigment-protein complexes, spillover, xanthophyll cycle, lipids, and pigments photodestruction) are discussed and analyzed.