Ecological drivers of nitrogen cycling and primary productivity in changing Arctic and sub-arctic seas.

与加拿大接壤的海洋生态系统提供了许多具有经济、社会和环境价值的好处，包括维持支持食物网、养殖、沿海生计、资源开采、碳储存和气候调节的物种和栖息地的多样性。气候对这些服务的压力在北冰洋(AO)是最快和最深的，那里的海洋受到气候变暖、酸化、海冰消失以及随后淡水负荷和上层海洋动态变化的不同同时影响。由于这些变化必然会影响初级生产力，这为海洋产生的可收获资源量及其对碳储存和气候调节的影响设定了上限，因此我的探索研究的长期目标是量化这种初级生物生产力及其对北极和亚北极海洋环境变化和变化的敏感性。*最近确定了氮(N)的有效性，而不是光，是控制北部海域年PP大小的最关键因素，我将把下一个五年计划的重点放在彻底评估N的循环和影响其海洋库存和藻类可获得性的微生物过程上。由于其地理位置，AO是一个行星管道，将水从亚北区太平洋排出，并穿过加拿大群岛进入巴芬湾、拉布拉多海，最终进入渔业丰富的西北大西洋。这种连通性是至关重要的：它使所有受影响的地区对上游地区不平衡的氮循环的累积效应非常敏感。在三项拟议任务中的一项中，这些累积影响将根据不同养分相对浓度的空间模式和主要N底物的原子结构进行诊断，其中主要N底物的原子结构整合了主要的N循环路径。这项工作将连接综合调查地点之间的点，在那里将使用稳定的同位素示踪剂孵化来评估全套N循环速率。第二项任务旨在更好地了解氮循环如何受到空间和季节性环境条件(如海冰覆盖、光照可获得性、温度、pH)的影响。这两项任务将得到第三项任务的补充，该计划采用实验方法评估海洋酸化和变暖对氮素动态和初级生产的短期影响。*根据最近的成就，拟议的计划将培训高素质的人员，并为他们提供在学术界、政府或私营部门从事科学职业所需的专业知识。除了对AO生态学领域已证实的变革性影响之外，这项工作还将有助于改进预测模型，告知公众，并协助决策者管理突然变化带来的风险和机会。**

The marine ecosystems bordering Canada provide numerous benefits of economic, societal and environmental value, including maintenance of the diversity of species and habitats that support food webs, culture, coastal livelihoods, resource extraction, carbon storage and climate regulation. Climate-driven pressures on those services are fastest and deepest in the Arctic Ocean (AO), where the ocean is impacted in different concurrent ways by warming, acidification, the demise of sea ice and ensuing changes in freshwater loading and upper ocean dynamics. Because these changes necessarily impact primary production, which sets an upper limit to the amount of harvestable resources produced by the sea and its impact on carbon storage and climate regulation, the long-term objective of my Discovery research is to quantify this primary biological productivity and its sensitivity to environmental variability and change in Arctic and sub-arctic seas. ***Having recently established that the availability of nitrogen (N), and not light, is the most critical factor regulating the magnitude of annual PP in northern seas, I will focus the next 5-year program on a thorough assessment of N cycling and the microbial processes that affect its oceanic inventory and availability to algae. Due to its geographical location, the AO is a planetary conduit that drains water from the Subarctic Pacific and channels it across the Canadian Archipelago into Baffin Bay, the Labrador Sea and ultimately the northwest Atlantic, where fisheries abound. This connectivity is crucial: it makes all affected regions sensitive to the cumulated effect of imbalanced N cycling in upstream areas. In one of three proposed tasks, these cumulated impacts will be diagnosed from spatial patterns in the relative concentrations of different nutrients and in the atomic structure of major N substrates, which integrates dominant N cycling pathways. This work will connect the dots between comprehensive survey sites, where a full suite of N cycling rates will be assessed using incubations with stable isotopic tracers. This second tasks aims to better understand how N cycling is affected by spatially and seasonally changing environmental conditions (e.g. sea-ice cover, light availability, temperature, pH). These two tasks will be complemented by a third, which takes an experimental approach to evaluating the short-term impacts of ocean acidification and warming on nitrogen dynamics and primary production.***In keeping with recent achievements, the proposed program will train highly qualified personnel and provide them with the expertise required to undertake scientific careers in academia, government or the private sector. Beyond its confirmed transformative impact on the field of AO ecology, this work will help to refine predictive models, inform the public and assist decision makers in managing the risks and opportunities that abrupt change brings.**