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

北极和亚北极海洋变化中氮循环和初级生产力的生态驱动因素。

• 批准号: RGPIN-2016-05965
• 负责人: Tremblay, JeanEric
• 金额: $ 3.21万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=688776
• 关键词: Ecological; drivers; nitrogen; cycling; primary

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.**

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，包括维持物种和生境的多样性，支持食物网、文化、沿海生计、资源开采、碳储存和气候调节。这些服务受到的气候驱动压力在北冰洋最快和最深，那里的海洋以不同的方式受到变暖、酸化、海冰消亡以及随之而来的淡水负荷和上层海洋动态变化的影响。由于这些变化必然会影响初级生产力，这为海洋生产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，因此我的发现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异和变化的敏感性。*** 最近确定氮（N）的可用性，而不是光，是调节北方海年度PP大小的最关键因素，我将在下一个5年计划中重点对影响海洋库存和藻类可用性的N循环和微生物过程进行全面评估。 由于其地理位置，AO是一个行星管道，从亚北极太平洋排水，并将其穿过加拿大群岛进入巴芬湾，拉布拉多海，最终进入西北大西洋，那里有丰富的渔业。这种连通性是至关重要的：它使所有受影响的地区敏感的累积效应不平衡的N循环在上游地区。在三个拟议的任务之一，这些累积的影响将被诊断从空间格局中的相对浓度不同的营养物质和主要的N基板，它集成了占主导地位的N循环途径的原子结构。这项工作将连接点之间的综合调查网站，在那里一套完整的N循环率将使用孵化与稳定同位素示踪剂进行评估。这第二个任务的目的是更好地了解氮循环是如何影响的空间和季节性变化的环境条件（例如海冰覆盖，光照，温度，pH值）。这两项任务将得到第三项任务的补充，第三项任务采用实验方法，评估海洋酸化和变暖对氮动态和初级生产的短期影响。为了与最近的成就保持一致，拟议的计划将培养高素质的人才，并为他们提供在学术界，政府或私营部门从事科学事业所需的专业知识。除了对AO生态学领域的变革性影响外，这项工作还将有助于完善预测模型，告知公众，并协助决策者管理突变带来的风险和机遇。