BREATHE
Bottom-sea ice Respiration and nutrient Exchanges Assessed for THE Arctic (BREATHE)
Polar amplification of global warming has transformed the Arctic marine system and its sea ice cover. Reductions of ice thickness, distribution and extent have substantially impacted sea ice habitats and the microorganisms living within them. Algae are important members of sea ice microbial communities; their spring bloom kick-starts annual primary production that contributes to trophic function and carbon cycling in the marine ecosystem. However, current estimates and modeled projections of sea ice algal productivity are compromised by incomplete characterization of two key processes, i) turbulence-driven nutrient supply and, ii) algal respiratory costs of living in a harsh ice environment. Furthermore, inherent methodological constraints of studying sea ice has meant an underrepresentation of in situ measurements that are unbiased by experimental artifacts and thus invaluable for our understanding sea ice habitats. The BREATHE project will combine in situ, experimental and model-based approaches to address knowledge gaps on turbulent nutrient supply and ice algal respiration, with results that improve the accuracy of current and projected ice algal production estimates. Towards this purpose the project will develop and apply state-of-the-art O2 methods for the study of sea ice biogeochemistry. It will complete fieldwork in contrasting regions of the Arctic to characterize productivity and turbulence-driven nutrient regimes of different sea ice habitats, which will inform innovative experiments that provide the first empirical description of ice algal respiration and its variability. Integrated modeling will provide the unique opportunity to implement and directly test parameterizations of respiratory and nutrient processes, before they are applied for prediction. Project outcomes will represent a paradigm shift in our understanding of sea ice primary production, with implications for the management of ecosystem services it supports like, greenhouse gas regulation.