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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=713235
• 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.

我的研究项目的总体目标是开发、测试和应用新型稳定同位素技术来跟踪北冰洋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 万年来的首次。目前尚不清楚未来无冰北极的初级生产力是否会增加或减少。这对于预测渔业产量和通过将二氧化碳生物封存在深海来减少温室气体排放具有紧迫的全球重要性。冰盖的消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较长无冰生长季节所带来的生产力增长。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限制，因为除了夏季的短暂窗口外，很难进入偏远的北极环境，卫星遥感器无法看到水体深处超过 25 m 的深度，而且严重缺乏长期（数十年）的科学观察。我的研究计划通过两种关键方式直接解决科学进步面临的这些持续挑战。首先，我们利用深海珊瑚骨骼中包含的年度分辨率古记录，这些珊瑚以最近出口的初级生产力的下沉通量为食。通过将这些珊瑚记录与更传统的沉积物岩心的记录相结合，将产生北极水域前所未有的长度和分辨率的古记录。其次，我们利用对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。这种新颖的方法超越了传统的大量同位素方法，提供了一种独立跟踪海洋食物网基础的四个关键过程的方法：营养源、自养群落组成、生物体营养位置和微生物降解。以年度分辨率和数百年时间跨度重建这些变量将使我们能够检验有关海冰条件变化对养分可用性和初级生产力影响的假设。这项研究建立在创新和有影响力的古生态重建的可靠记录之上，这对于理解、减轻和适应气候变化至关重要。