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

北极海冰的萎缩开辟了新的生物地理和生态前沿，将基本的微观初级生产者，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，北冰洋初级生产的未来趋势，海洋食物网的物质和对北方海洋资源的重要支持，知之甚少。它特别依赖于内在相关的悖论：1)虽然更长的时间和更大的自由水域将为人类开辟新的领土，但它们将被新的硅藻殖民，从大西洋和太平洋迁移，或通过新的北方海上航线在商业船只的压载物中运输；2)虽然光的可用性预计会轻微增加，以提高泛北极海洋生产；过多的持续或间歇性光照会降低硅藻的生产力，并改变其食品质量特性。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，因此了解硅藻在当前和未来光照条件下的生态生理光响应（生长、生产力和适应）至关重要。北冰洋初级生产与硅藻的季节性光合生产力和物种演替密切相关。它整合了生长和生命形式、细胞大小、深度适应的功能和生态多样性。因此，有必要了解北极硅藻光响应的功能和生态多样性如何解释北极海洋初级生产的当前和未来趋势：这是我的探索计划提案的目标。它阐明了4个短期目标：1)生长和生命形式的比较，2和3)细胞大小和深度适应的影响，4)对抗未来潜在的温带入侵者。我的“发现”项目提案有以下支持：1)对北极硅藻多样性、生态和环境的精确了解；ii)获得一系列菌株的独特途径，以及在北极模拟条件下培养这些菌株的能力；Iii)通过实验室实验和实地监测，在物种和群落水平上调查光生理的能力；结合遗传学、生物化学和（生态）生理学的多学科方法。每个目标都通过定义9名学生（3名学士、3名硕士和3名博士）研究项目的任务来互动地实现。此外，我的探索计划提案的合作基础建立在加拿大和法国的国际知名科学家的基础上，这将极大地有助于培训下一代北极和藻类专家，以支持在加速全球变暖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.