The Significance of Macroalgal Detritus for Marine Food Webs and Blue-Carbon Sequestration

巨藻碎屑对海洋食物网和蓝碳封存的意义

• 批准号: 2445859
• 金额: --
• 依托单位: University of Aberdeen
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2445859
• 关键词: Significance; Macroalgal; Detritus; Marine; Food

Marine plants draw down CO2, and in a world of rising atmospheric CO2 levels carbon sinks in vegetated coastal ecosystems can sequester CO2 on geological time scales and are now referred to as 'Blue Carbon'. Marine macroalgae (MA) are highly productive macrophytes that currently cover approximately 3.5 million km2 of sublittoral seabed and provide 1521 Tg C yr-1 of net primary production globally. Nevertheless, MA have largely been excluded from estimates of blue carbon sequestration because they predominantly grow on hard substrates, which prevent the accumulation of detritus-rich sediments. But while MA carbon (CMA) cannot accumulate within the source ecosystem, it has been estimated that up to 82% of CMA is exported from the source ecosystem to seabed habitats at greater depths, providing a significant carbon subsidy to marine seabed ecosystems beyond the coastal zone and/or contributing to long-term carbon burial in the ocean seabed.Shelf seas are known for their significant stocks of carbon, and marine fjords have recently been proposed as major C sinks of global significance, despite their low area coverage accounting for 11 % of global annual carbon sequestration. Per unit area, fjord organic carbon burial rates are one hundred times as large as the global ocean average, and fjord sediments contain twice as much organic carbon as biogeneous sediments underlying the upwelling regions of the ocean. Studies in Arctic fjords suggest that CMA contributes up to 60% to C sequestration which would render macroalgae a major contributor to blue carbon sequestration, and global biogeochemical cycles in general.Both remineralisation and sequestration of CMA are poorly constrained, however, and the actual importance of MA detritus, and hence carbon derived from macroalgae, as a major ecosystem service to deep allochthonous (sink) benthic biota and sediments still needs to be addressed in a quantitative, geographically well-constrained investigation.This project will quantify the contribution of MA carbon to C sequestration and as food subsidy to benthic fauna in Scottish fjords through a combination of camera surveys, sediment coring and analysis, stable isotope analysis and isotope tracing experiments. Following the methodology of Smeaton et al. (2017), the project will deliver a predictive (first-order) assessment of the MA carbon subsidy into sea loch sediments.Climate change is a global issue, and improved understanding and management of Blue Carbon ecosystems is important for climate mitigation action, and directly relevant to UN Sustainable Development Goals 3, 13 and 14. Close collaboration with the Scottish Blue Carbon Forum will facilitate quick translation into national climate mitigation and adaptation policy.In addition to SUPER specific training events, the candidate will be trained in a wide range of field and laboratory techniques, including the design and conduction of novel isotope tracing experiments, food web modelling and GIS. It is envisaged that the student will also spend some time in the laboratory of our external collaborator Dr. Inka Bartsch at AWI Bremerhaven.

海洋植物吸收二氧化碳，在大气二氧化碳水平上升的世界里，沿海植被生态系统中的碳汇可以在地质时间尺度上封存二氧化碳，现在被称为“蓝碳”。海洋大型藻类(MA)是高生产力的大型植物，目前覆盖约350万平方公里的滨下海床，提供全球1521TgCyr-1的净初级生产量。然而，MA在很大程度上被排除在蓝色碳固定的估计之外，因为它们主要生长在坚硬的基质上，这防止了富含碎屑的沉积物的积累。但是，尽管海洋生态系统中的海洋环境管理碳(CMA)不能在源生态系统内积累，但据估计，高达82%的CMA从源生态系统输出到更深的海底生境，为沿海地区以外的海洋海底生态系统提供了大量的碳补贴，和/或促进了海洋海底的长期碳埋藏。陆架海以其大量的碳储量而闻名，尽管海洋峡湾的面积较低，但它们占全球年度碳汇的11%，但最近被提议为具有全球意义的主要C汇。单位面积上，峡湾的有机碳埋藏率是全球海洋平均水平的一百倍，峡湾沉积物中的有机碳含量是海洋上升区下生物沉积物的两倍。北极峡湾的研究表明，CMA对碳的固存的贡献高达60%，这将使大型藻类成为蓝藻固碳和全球生物地球化学循环的主要贡献者。然而，CMA的再矿化和固存都受到很少的限制，MA碎屑的实际重要性，以及来自大型藻类的碳，作为深层异地(汇)底栖生物群和沉积物的主要生态系统服务，仍然需要在定量的、地理上受到很好限制的调查中得到解决。该项目将通过相机调查、沉积物采集和分析相结合的方式，量化MA碳对C固存和对苏格兰峡湾底栖动物的食物补贴的贡献。稳定同位素分析和同位素示踪实验。遵循Smeaton等人的方法。(2017)，该项目将对海洋湖泊沉积物中的MA碳补贴进行预测性(一阶)评估。气候变化是一个全球问题，改善对蓝色碳生态系统的了解和管理对气候缓解行动非常重要，与联合国可持续发展目标3、13和14直接相关。与苏格兰蓝色碳论坛的密切合作将有助于快速转化为国家气候缓解和适应政策。除了超级具体的培训活动外，候选人还将接受广泛的现场和实验室技术培训，包括设计和实施新的同位素追踪实验、食物网络建模和地理信息系统。据设想，学生还将在我们的外部合作者英卡·巴奇博士在AWI不来梅港的实验室呆一段时间。