The interaction between sea ice, ocean biogeochemistry and ecosystem function

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Many recent changes in the Arctic cryosphere have been dramatic and have exceeded even the most extreme projections of future change. Some of these cryosphere changes are expected to affect local, regional and even global climate through distant connections. However, climate feedbacks associated with the changing cryosphere are extremely complex, vary over space and time, and are still generally poorly understood. The long-term goal of my program is to understand how climate-induced changes in sea ice and freshwater dynamics transform the biogeochemical and ecological function of the marine Arctic. This will provide critical insight for defining the role of the polar oceans in buffering emissions of climate-active gasses. Special focus will be allocated to determine the role of ice algal communities in supporting feedback mechanisms with climate change. These unique microbial communities thrive within the extreme biome of the sea ice and contribute to the formation and cycling of organic material, nutrients and climate active gasses. However, very little is known about ice algal ecology and the potentially important role that they play in oceansea iceatmosphere exchange. I will explore and quantify the metabolic activity of ice-associated microbial communities. The short-term goal of my program is to determine the role of ice algal communities in supporting feedback mechanisms with climate change. To achieve this goal I will: 1. Resolve the complex 3-D structure of sea ice (ice, brine, gasses, biota) during ice freeze and thawing cycles; 2. Quantify how this affects light conditions for the autotrophic ice algal community and net community metabolism governing ice algae's role in organic matter release, thermal budget and CO2 exchange between the ocean and atmosphere. 3. Train 2 PhD, 2 MSc and 5 undergraduate students during this project. The project findings will be instrumental in improving current models of Arctic sea ice effects on the role of the Arctic as a CO2 sink and generator of radiative forcing, thereby improving regional and global climate models.