Physical and biological controls of primary production in the ice-covered Canadian Arctic marine system

北极海冰覆盖的海洋环境正在经历前所未有的变化，近年来海冰覆盖加速减少，水体特征和分布发生变化。因此，了解被冰覆盖的初级生产的时间和控制是至关重要的，这是极地海洋生态系统的关键组成部分。例如，冰藻华的早期终止可能有利于从高能量的北极专业物种转向能量较低的南方通用物种，部分原因是冰藻产量较低，但也与较长的无冰期相关的浮游植物产量增加。我的研究计划的长期目标是全面了解在冰雪覆盖的生态系统中控制北极海洋初级生产的过程，以更好地预测该系统将如何应对不断变化的环境。未来5年我的具体研究目标是：(1)研究冰下透射辐照度对冰藻光生理、生物量和分类组成的光谱依赖性，以进一步发展冰下遥感技术；(2)研究控制冰藻产生、积累和损失时空变化的物理和生物过程；(3)确定融冰水藻类对高紫外线和可见光的光保护策略；(4)研究控制冰下浮游植物生产时间和数量的机制。这些目标将通过实地研究、实验和藻类生长模型的互动方法来实现。通过实现这些目标，我和我的团队（包括5个学士学位，2个硕士学位和3个博士学位的学生）将增加我们对冰雪覆盖生态系统初级生产的物理和生物控制的知识，开发新的观测技术，激发新的想法，填补知识空白，并提高我们模拟生态系统的能力。冰盖的减少，对航运流量增加的预期，以及要求增加对我们北方的了解的政治压力，都突出了上述工作的重要性。

The Arctic ice-covered marine environment is undergoing unprecedented changes with recent accelerated declines in sea ice cover and changes to water mass characteristics and distribution. Understanding the timing and controls of ice-covered primary production, a critical component of the polar marine ecosystem, is therefore critically important. For example, an earlier termination of the ice algal bloom could favor a switch from high-energy Arctic specialist species to less energy-rich generalists from the south, due, in part, to lower ice algal production, but also to enhanced phytoplankton production associated with a longer ice-free period. The long-term goal of my research program is to obtain a comprehensive understanding of processes controlling Arctic marine primary production in the ice-covered ecosystem to better predict how the system will respond to its changing environment. My specific research objectives over the next 5 years are to: (1) examine the spectral dependence of sub-ice transmitted irradiance on ice algal photophysiology, biomass, and taxonomic composition to further develop under-ice remote sensing techniques; (2) investigate physical and biological processes that control spatial and temporal variability of ice algal production, accumulation and loss; (3) determine photoprotective strategies of ice melt water algae to high ultraviolet (UV) and visible light levels; and (4) investigate the mechanisms that control the timing and magnitude of under-ice phytoplankton production. The objectives will be met through an interactive approach of field studies, experiments, and algal growth modeling. By meeting these objectives, my team and I (including 5 B.Sc., 2 M.Sc. and 3 Ph.D. students over the grant's tenure) will increase our knowledge on physical and biological controls of primary production in the ice-covered ecosystem, develop new observational techniques, fuel novel ideas, fill knowledge gaps, and improve our capability to model the ecosystem. A declining ice cover, expectation of increased shipping traffic, and political pressure for an increased understanding of our North highlight the importance of the work described above.