Physico-ecobiogeochemistry of East Antarctic pack ice during the winter-spring transition

Our study provides information on the relationships between physical, chemical, and biological properties of East Antarctic sea ice sampled as part of the Sea Ice Physics and Ecosystem eXperiment (SIPEX) during the winter-spring transition in 2007. The sampled sea ice showed a high contribution of granular ice, indicating the turbulent conditions during sea ice formation off East Antarctica. The sea ice was cold, with brine volumes often below or very close to the theoretical percolation threshold of sea ice. Dissolved inorganic nutrient concentrations showed both positive and negative deviations from theoretical dilution lines, indicating both nutrient uptake as well as nutrient remineralisation in sea ice brines. Cold temperatures, high brine salinities, and low brine volumes limited high ice algal biomass to the warmer and more porous sea ice layers at the ice–water interface. We hypothesise that East Antarctic sea ice shows generally low ice algal biomass accumulation due to a combination of relatively low snow–loading, relatively cold ice temperatures, and short persistence of sea ice into the warm forcing regime, all of which prevent the development of significant internal and surface communities.