1. Grossman and Dieckmann, 1994 Most of what we know regarding the biology of (Arctic) sea ice is biased toward summertime basal ice Most biomass Easiest access Microbial activity in sea ice occurs throughout the annual cycle (Junge et al. 2004) Bacterial are distributed throughout the ice column, concentrating at the top and bottom (Bowman and Deming, 2010) Sharp environmental gradients and other stressors at the top and bottom of the ice column may induce physiological responses of significance to chemistry and physics DMSP production and conversion to DMS (T, S, UV) Methylhalide formation, including iodomethane (S, UV, H 2 O 2 ) EPS production (S, T, UV) C export Calcium carbonate polymorph selection Brine channel blockage Enhanced connectivity

2. Community composition Physiological state Physical and chemical impact Krembs, Eicken, and Deming, 2011 Biologically active ice is more connective than sterile ice Implications for permeability of gas Implications for nutrient renewal Implications for ice strength Limitations of laboratory study EPS varies in concentration and composition At this time don’t know how changing EPS will impact the properties of sea ice in the future

3. Integrating into MOSAiC – Establishing a baseline for predictive (physio)biogeochemistry + + Krembs et al. 2002 Given a set of chemical and physical conditions who is present, how many are there, and what are they doing that feeds back to the initial conditions? Basic biology is lacking for the central Arctic, little effort or equipment is required for a long time series of basic parameters In addition at key time points detailed community composition* should be assessed in combination with rate measures and flux measures