Photophysiological responses of sea ice algae to changes in salinity (PRS)

Sea ice in the Arctic Ocean is rapidly changing and its surface waters are expected to freshen due to climate warming. This is likely to affect the algal communities living within it, with uncertain consequences for the Arctic marine ecosystem its biogeochemistry. The PRS project will assess the ability of sea ice algae to temporarily change with shifting growth conditions, in particular to changes in salinity at the ocean-ice interface. This will be done by comparing sea ice algal photophysiology and primary production from two contrasting areas within Tempelfjorden of Svalbard, sampling on 12 instances over a one-month spring period. One sampling area will be of comparatively high salinity, close to the opening of the fjord where it is expected that there will be a strong influence of relatively saline coastal currents. The other sampling area will target surface waters of low salinity, as it will be located farther into the fjord and thus nearer to potential freshwater inflow. This study of the natural ice algal community over salinity gradient will be coupled to field experiments, where long-term (weeks) photophysiological response of relatively saline-acclimated algae to freshening will be monitored. Production and photophysiology will be assessed in this study using using 14C methodology, and coincident measurement of environmental parameters will be completed (e.g. in situ light, dissolved inorganic carbon and nutrients). This work will improve our understanding on how sea ice algae may respond to climate change. It will also provide important insights on how procedures of sea ice sample melt, which can vary drastically in salinity, may impact our estimates of sea ice algal production.