Mapping Antarctic phytoplankton physiology using autonomous gliders

The integration of a FIRe sensor into a glider allows us to map, with high temporal and spatial resolution, phytoplankton physiological responses to physical forcing. Different missions were designed to evaluate the temporal and spatial variability of phytoplankton physiology by using a drift and a station keeping mission, respectively. Diel cycles collected show a clear diurnal variations driven by incident radiation, with both maximal fluorescence and photosynthetic efficiency (in any light adapted phytoplankton) showing reduced values only in the upper 10-15 meters of the water column at the highest irradiances. Further analyses comparing different MLD regimes have shown different photoacclimation responses (light saturation parameter, Ek) resulting from differences in solar radiation exposure conditions (both time and intensity), reflected in the depth of the ML. Further analyses include determining a method to correct the FIRe glider fluorescence profiles in the upper ocean during daytime by comparing the maximum fluorescence during the highest irradiance (daytime) with the lowest irradiance (nighttime).