FREEZING DRIVEN UPWELLING IN ANTARCTIC SEA ICE BIOLOGICAL SYSTEMS (17th Symposium on Polar Biology)

Within existing ice covers, we found fluid motion can also be driven by freezing-induced convection. Surface snow-slush and near-surface highly porous layers were found in the pack ice at Ice Station Weddell in the western Weddell Sea at end of summer and examined for physical and biological processes. Convective fluid motion, driven by brine rejection from the ice freezing from above as air temperatures dropped, replaced nutrient depleted waters in the layers with nutrient rich sea water from below. The upwelling nutrients fueled autumn blooms of algae in second-year ice in the near surface regions of the ice cover where sufficient light is also available. Both the timing and location of these blooms within the ice cover are unlike the bottom spring blooms of sea ice algae previously observed