CAREER: Experimentally Testing the Role of Sympagic Algae in Sea-ice Environments using a Laboratory Scale Ice-tank.

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Sea ice in Antarctic coastal waters shape ecosystems, both in the surface waters and at the bottom of the ocean, environments that depend on algae living in sea ice for their productivity. With high variability in sea ice formation and melt between years and as a response to climate change, it is of importance to obtain better understanding of the interaction of sea ice with algae, as well as provide better data for global climate models. This project will accomplish those goals by measuring phytoplankton growth and cellular properties in sea ice with experiments performed using an ice tank. Laboratory experiments will be based on previous observations in the Antarctic Peninsula coastal waters, providing realistic conditions to emulate. The scientific importance of the proposed work aligns with the National Science Foundation goals to understand the biological and chemical properties of sea ice bio-geo-chemistry and its feedbacks with seasonal sea ice dynamics and climate. The finding from this project will be of interest to a broad scientific community, including oceanographers, biologists, chemists, and ecosystem and ocean modelers. To address the scarcity of data on sea ice microbes that limits our ability to predict future Antarctic climate with accuracy, the principal investigator will develop an Antarctic Science Minor in order to train future scientists with an environmental perspective and prepare the future US workforce with a strong scientific background on Earth and Biological Sciences.There is a paucity of data to understand the processes underlying observed patters in sea ice quality and their interaction with the sea-ice microbial community. This project will provide a mechanistic understanding of primary production and physiology of sympagic algae over the seasonal cycle of formation and melt of Antarctic sea ice. Although sea ice is central to the Antarctic coastal ecosystems, little is known of how they affect, and are in turn affected, by sea-ice algae. This project concentrates on first-year sea ice, forming and melting each year, creating unique and very dynamic habitats. The study will be structured by 4 main objectives: 1) how different algal species adapt to the seasonal changes in sea ice conditions, 2) how different methods to measure primary production (carbon dioxide drawdown, oxygen production and variable fluorescence) relate in sea ice and differ from sea water measurements, 3) how sympagic algae influence the physical structure of sea ice, 4) how sympagic algae contribute to organic matter cycling during ice melt. Due to expected changes in sea ice due to climate change, this study is uniquely positioned to provide needed data on short-term and seasonal processes. Results from this study will be useful to refine models of algal production in Antarctic and Arctic ecosystems, data not available to date as sea ice and its biogeochemistry are often poorly represented in earth system models. This project will also provide education for graduate and undergraduate students as well as material to develop class curriculum for middle-school students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.