Spring Blooms of Sea Ice Algae Along the Western Antarctic Peninsula: Effects of Warming and Freshening on Cell Physiology and Biogeochemical Cycles.

南半球春季期间海冰范围和厚度的快速变化使冰内或附着在冰上的微生物受到温度、盐度、光照和营养物质的巨大波动。该项目旨在确定南极半岛西部春季融化期间海冰藻类对温度上升和盐度下降的细胞反应，并确定细胞一级的相关变化如何潜在地影响生物驱动的动态过程。了解海冰藻类如何应对和适应它们的环境，不仅有助于预测极地生态系统可能会随着海冰的范围和厚度发生变化，而且还将更好地理解地球上光合作用生命的广泛成功。科学背景和由此产生的研究进展将通过外联活动向公众传播，其中包括与科学传播学者和在华盛顿州西雅图太平洋科学中心举行的受欢迎的极地科学周末的合作。该项目将为大学生提供学生培训，并为K-12学龄儿童提供教育体验。目前，人们对南极半岛西部地区迅速变化的环境与海冰藻类生产之间存在的反馈关系了解甚少。在春季融化期间，藻类经历的温度和盐度的巨大变化影响了关键的细胞过程，包括参与光合作用和呼吸作用的酶催化反应的速度，以及压力保护化合物的产生。细胞过程中的这些变化很少受到限制，但可能很大，可能会对当地生态系统生产力和生物地球化学循环产生影响。特别是，这项研究将集中在酶的热敏感性和用于晕和低温保护的相容溶质和外聚合物的循环，以及它们如何影响初级生产和碳和氮的生物地球化学循环。方法将包括在春季融化期间进行实地采样，在不同温度和盐度条件下进行自然海冰群落的孵化实验，以及在实验室养殖中对海冰藻类进行受控操作。应用一系列技术，从快速重复频率荧光测量、总和净光合作用测量到代谢组学和酶动力学，将梳理温度和盐度对细胞新陈代谢和初级生产的机械影响，目的是量化这些变化将如何影响南极半岛西部的生物地球化学过程。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Rapid changes in the extent and thickness of sea ice during the austral spring subject microorganisms within or attached to the ice to large fluctuations in temperature, salinity, light and nutrients. This project aims to identify cellular responses in sea-ice algae to increasing temperature and decreasing salinity during the spring melt along the western Antarctic Peninsula and to determine how associated changes at the cellular level can potentially affect dynamic, biologically driven processes. Understanding how sea-ice algae cope with, and are adapted to, their environment will not only help predict how polar ecosystems may change as the extent and thickness of sea ice change, but will also provide a better understanding of the widespread success of photosynthetic life on Earth. The scientific context and resulting advances from the research will be communicated to the general public through outreach activities that includes work with Science Communication Fellows and the popular Polar Science Weekend at the Pacific Science Center in Seattle, Washington. The project will provide student training to college students as well as provide for educational experiences for K-12 school children. There is currently a poor understanding of feedback relationships that exist between the rapidly changing environment in the western Antarctic Peninsula region and sea-ice algal production. The large shifts in temperature and salinity that algae experience during the spring melt affect critical cellular processes, including rates of enzyme-catalyzed reactions involved in photosynthesis and respiration, and the production of stress-protective compounds. These changes in cellular processes are poorly constrained but can be large and may have impacts on local ecosystem productivity and biogeochemical cycles. In particular, this study will focus on the thermal sensitivity of enzymes and the cycling of compatible solutes and exopolymers used for halo- and cryo-protection, and how they influence primary production and the biogeochemical cycling of carbon and nitrogen. Approaches will include field sampling during spring melt, incubation experiments of natural sea-ice communities under variable temperature and salinity conditions, and controlled manipulation of sea-ice algal species in laboratory culture. Employment of a range of techniques, from fast repetition rate fluorometry and gross and net photosynthetic measurements to metabolomics and enzyme kinetics, will tease apart the mechanistic effects of temperature and salinity on cell metabolism and primary production with the goal of quantifying how these changes will impact biogeochemical processes along the western Antarctic Peninsula.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.