Characterising the sea ice environment using a newly developed sensor array mounted on an under-ice trawl

One of the most pronounced impacts of climate change is the changing sea ice cover, which has implications for sea ice-associated ecosystems that depend on carbon produced by ice-associated algae. In order to fully understand these ecosystems there is a need to understand both the physical and biological components. We present preliminary results from Polarstern cruises to the Eastern Central Arctic Ocean (summer 2012) and Weddell Sea (fall-winter 2013). Biological samples were acquired from the under-ice environment using the Surface and Under-Ice Trawl (SUIT) and from within the ice by extracting ice cores. Biophysical properties of sea ice and under-ice environments were characterized using a sensor array mounted on the SUIT that measured ice thickness, under-ice light spectra, water properties and chlorophyll a biomass (in- and under-ice). Modal ice thicknesses were between 0.45-1.38 m (Arctic) and 0.23-0.70 m (Weddell Sea). Sea ice properties were related to the distribution of some key under-ice species (e.g. Polar Cod and Antarctic Krill). Previous studies have used under-ice light spectra to derive ice-algal biomass but were limited to local-scale point measurements. We present a new method for calculating ice-algal biomass from under-ice spectra on local- to meso-scales and compare the results using both methods