Diatom ecophysiology in a changing Arctic: consequences on the marine primary productivity

北冰洋海冰的缩小开辟了新的生物地理和生态前沿，将必要的微型初级生产者，即硅藻微藻与人类经济和社会活动联系起来。在当前全球变暖的背景下，人们对北冰洋初级生产的未来趋势--海洋食物网的实质和对北方海洋资源的重要支持--知之甚少。这尤其取决于内在联系的悖论：1)虽然更长时间和更大面积的自由水域将为人类打开新的领土，但它们将被新的硅藻定居，从大西洋和太平洋迁徙，或者被用新的北方海上航线用商船的压舱物运输；2)虽然预计光照供应略有增加将增加泛北极的海洋生产，但过多的持续或时断时续的光照可能会降低硅藻的生产力，并改变它们的食物质量属性。这些相互交织的即将发生的事件将改变北冰洋初级生产的面貌，因此有必要了解硅藻在当前和未来光照条件下的生态生理光反应(生长、生产力和驯化)。北冰洋初级生产力与季节性硅藻光合作用生产力和物种演替密切相关。它综合了功能和生态多样性的生长和生命形式，细胞大小，深度适应。因此，有必要理解北极硅藻的功能和生态多样性对光响应如何解释北极海洋初级生产力的现在和未来趋势：这是我的发现计划提案的目标。它阐述了大约4个短期目标：O1)生长和生命形式的比较，O2和O3)细胞大小和深度适应的影响，以及O4)与未来潜在的温带入侵者的对抗。我的探索计划建议得到了i)北极硅藻多样性、生态和环境的精确知识；ii)获得一系列菌株的独特途径，以及在模拟北极的条件下生长它们的能力；iii)通过实验室实验和田间监测在物种和群落水平上调查光生理学的能力；iv)结合遗传学、生物化学和(生态)生理学的多学科方法。每个目标都由定义9个学生的研究项目的任务交互地提供服务：3个学士学位，3个硕士学位。和3名博士生。此外，我的探索计划提案的合作基础是来自加拿大和法国的国际公认的科学家，这将大大有助于培训下一代北极和藻类专家，以支持在全球变暖加速的背景下更好地预测北极海洋生态系统的可持续性。

Arctic sea-ice shrinking opens new biogeographical and ecological frontiers that relate essential microscopic primary producers, i.e. the diatom microalgae, to human economic and social activities. In the context of current global warming, future trend of Arctic Ocean primary production, the substance of marine food-webs and vital support to the Northerners marine resources, is poorly understood. It particularly depends on intrinsically related paradoxes: 1) While longer periods and larger areas of free waters will open new territories for humans, they will be colonized by new diatoms, migrating from the Atlantic and Pacific, or being transported in the ballasts of commercial vessels using the new Northern maritime routes, 2) While a mild increase in light availability is predicted to enhance pan-Arctic marine production, too much sustained or episodic light could reduce the productivity of diatoms together with modifying their food quality' properties. These interlaced forthcoming events will modify the face of Arctic Ocean primary production, making it essential to understand the ecophysiological light-response of diatoms (growth, productivity and acclimation) under current and future light conditions. Arctic Ocean primary production is closely related to the seasonal diatom photosynthetic productivity and species succession. It integrates the functional and ecological diversity of growth and life forms, cell size, depth-adaptation. Therefore there is a need to comprehend how the functional and ecological diversity of Arctic diatoms light-response explains the present and future trends of Arctic marine primary production: this is the objective of my Discovery program proposal. It articulates around 4 short-term objectives: O1) Comparison of the growth and life forms, O2 and O3) Influence of cell size and depth-adaptation, and O4) Confrontation with potential future temperate invaders. My Discovery program proposal is supported by i) the precise knowledge of the diversity, ecology and environment of Arctic diatoms; ii) the unique access to a collection of strains, and the ability to grow them in Arctic-simulated conditions; iii) the ability to investigate photophysiology at the species and community levels with lab experiments and field monitoring; iv) a multidisciplinary approach coupling genetics, biochemistry and (eco-)physiology. Each objectives is interactively served by Tasks defining the research projects of 9 students: 3 B.Sc., 3 M.Sc. and 3 Ph.D. students. Furthermore, the collaborative foundation of my Discovery program proposal built on internationally acknowledged scientists from Canada and France will greatly contribute to the training of the next generation of Arctic and algae experts to support the better predictive sustainability of Arctic marine ecosystems in the context of accelerating global warming.