Tracking Arctic marine productivity across the Holocene - Anthropocene transition using novel compound-specific stable isotope techniques

使用新型化合物特异性稳定同位素技术跟踪整个全新世-人类世转变的北极海洋生产力

• 批准号: RGPIN-2018-05590
• 负责人: Sherwood, Owen
• 金额: $ 2.99万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=751182
• 关键词: Tracking; Arctic; marine; productivity; across

The overall goal of my research program is to develop, test and apply novel stable isotopic techniques for tracking long-term changes in primary productivity in the Arctic and sub-Arctic Oceans. By the year 2040, Arctic summer sea ice is projected to disappear completely for the first time in perhaps the last 13 million years. It remains unclear if primary productivity will increase or decrease in a future ice-free Arctic. This has urgent global importance for predicting fisheries yields and for mitigation of greenhouse gas emissions via biological sequestration of CO2 to the deep ocean. Loss of ice cover should lead to increases in photosynthetic potential; however, nutrient limitation and loss of habitat for highly productive ice algae could negate any gains in productivity made from longer ice-free growing seasons. Our understanding of physical-biological processes and feedbacks controlling marine productivity are limited by difficulty accessing the remote Arctic environment in all but a narrow window of summer, satellite remote sensors that cannot see deeper than 25 m into the water column, and an acute lack of long-term (multi-decadal) scientific observations. My research program directly addresses these ongoing challenges to scientific progress in two key ways. First, we make use of annual resolution paleo-records contained in the skeletons of deep-sea corals that feed on the sinking flux of recently exported primary productivity. By combining these coral records with those from more traditional sediment cores, paleo-records of unprecedented length and resolution for Arctic waters will be generated. Second, we leverage the breakthrough interpretive potential of carbon and nitrogen stable isotopic analysis of amino acids preserved in corals and sediments. This novel methodology goes beyond traditional bulk isotope methods to provide a means for independently tracking four key processes at the base of marine foodwebs: nutrient source, autotroph community composition, organism trophic position, and microbial degradation. Reconstruction of these variables at annual resolution and over multi-centennial timespans will allow us to test hypotheses on the effect of changing sea ice conditions on nutrient availability and primary productivity. This research builds on a solid track record of innovative and impactful paleo-ecological reconstructions, which are essential for understanding, mitigating and adapting to climate change.

我的研究计划的总体目标是开发，测试和应用新的稳定同位素技术，用于跟踪北极和亚北冰洋初级生产力的长期变化。到2040年，北极夏季海冰预计将完全消失，这可能是过去1300万年来的第一次。目前还不清楚初级生产力在未来无冰的北极会增加还是减少。这对于预测渔业产量和通过生物固存二氧化碳到深海减少温室气体排放具有紧迫的全球重要性。冰盖的丧失会导致光合作用潜力的增加;然而，营养限制和高产冰藻栖息地的丧失可能会抵消无冰生长季节延长所带来的生产力提高。我们对控制海洋生产力的物理-生物过程和反馈的理解受到以下因素的限制：除了夏季的一个狭窄窗口外，很难进入遥远的北极环境，卫星遥感器无法看到水柱深度超过25米，以及严重缺乏长期（数十年）的科学观测。我的研究计划直接解决这些持续的挑战，以两个关键的方式科学进步。首先，我们利用年度分辨率的古记录包含在骨骼的深海珊瑚，饲料的下沉通量最近输出的初级生产力。通过将这些珊瑚记录与传统沉积物岩心的记录相结合，将产生北极沃茨前所未有的长度和分辨率的古记录。其次，我们利用珊瑚和沉积物中保存的氨基酸的碳和氮稳定同位素分析的突破性解释潜力。这种新的方法超越了传统的散装同位素方法，提供了一种手段，独立跟踪四个关键过程的基础上的海洋食物网：营养源，自养生物群落组成，有机体营养位置，和微生物降解。重建这些变量在年度分辨率和超过几百年的时间跨度将使我们能够测试假设的影响不断变化的海冰条件对养分的可用性和初级生产力。这项研究建立在创新和有影响力的古生态重建的坚实记录之上，这对于理解，减缓和适应气候变化至关重要。