From minute to day: Ecophysiological response of phytoplankton to fluctuating light exposure during vertical mixing

Underwater light is a highly dynamic resource for phytoplankton. Fluctuating influences photosynthesis, respiration, biosynthesis, and growth at different timescales, but the interplay of these processes not well-understood. Subsamples phytoplankton community from turbid, well-mixed lake TaiHu (China) were either vertically moved through mixing depths or incubated fixed matching daily supply. Growth, photosynthetic electron transport rates, net oxygen production, night respiration measured 9 days. Production was investigated during cyclic mixing, throughout day, among days integral intensities. Electron rates higher vertical increased with depth, therefore better exploited short periods surface illumination. On other hand, light-stimulation consumption photoperiod shortening compensation intensities production growth. The communities kept sub-surface photoinhibited; their declined intensity in afternoon. There no sign afternoon depression which metabolized products periodic phases low deeper layers. Mixing produced more increasing respired decreasing intensities, day. This post-illumination enhancement seemed to be hardwired fluctuating light, regardless depth uncoupled rates. Photosynthesis tightly connected under than constant light.