RAPID/Collaborative Research: Estuarine dam removal as an ecosystem disturbance: Examining the impacts of seawater intrusion on functional stability of benthic N cycle communities

快速/合作研究：河口大坝拆除作为一种生态系统干扰：研究海水入侵对底栖氮循环群落功能稳定性的影响

• 批准号: 2016250
• 负责人: Craig Tobias
• 金额: $ 4.99万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-06-15 至 2023-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2016250&HistoricalAwards=false
• 关键词: RAPID; Collaborative; Research; Estuarine; dam

Large dams ( 15m high) are a major man-made disturbance to watersheds altering the structure and function of river ecosystems. The Nakdong River is one of the watersheds heavily affected by the dam constructed at the mouth of the river to stop tidal seawater exchange. When it was built in 1987, the dam caused dramatic shifts in lower river ecosystems converting the area to a man-made freshwater reservoir. The alteration of river water flows resulted in seasonal harmful algal blooms and water quality degradation. Increasing concerns about these negative impacts along with associated social and economic demands have led to restoring the river ecosystem by removing the dam. The dam removal will be done in a controlled way through a series of events that open the dam's gates, thereby allowing seawater intrusion into upstream ecosystems. This provides a unique and immediate opportunity to study the impacts of seawater intrusion on a freshwater ecosystem. The series of planned dam openings can be effectively used as a large-scale, unprecedented, manipulative ecosystem experiment. This RAPID project takes advantage of this unique opportunity to study the sediment microbial communities responding to the programmed seawater intrusion in the river. The project will include training opportunities for undergraduate and graduate students, and results will disseminated via public lectures and a scientific network for river researchers. This project aims to study the functional stability of sediment nitrogen (N) cycling communities responding to the disturbance of seawater intrusion in the Nakdong River, where dam removal is in progress via a series openings of dam gates. Multi-omic approaches including metagenomic, metatranscriptomic and metaproteomic analyses will be conducted to evaluate both sensitivity and resilience of individual N metabolisms in a community, while the measurements of N cycling processes (fluxes and rates), including denitrification and dissimilatory nitrate reduction to ammonium, reveal a whole community metabolism responding to the seawater intrusion. This is a unique and transformative project to determine the functional stability of different metabolisms within the community exposed to a programmed seawater intrusion in a freshwater ecosystem. The combined multi-omics and biogeochemical measurements will provide novel knowledge of sensitivity and resilience in different systematic levels from genes to individual organisms to the community level. Dissimilatory N cycling metabolisms in sediment communities are selected as a model of microbial functions since benthic N cycling is critical to attenuate excess N loading, a cause of eutrophication. Given the importance of benthic N cycle, the impacts of seawater intrusion on sediment N cycling communities and their functions have been mainly examined with ex-situ experimental designs such as microcosms and mesocosms or field survey along salinity gradients of rivers and estuaries. This first project represents the first ecosystem-scale manipulation examining sediment N cycling communities responding to seawater intrusion. Two graduate students will be involved in the project and will be trained in multi-omic and biogeochemcial methods. The project will also include training activities for undergraduates at the two institutions, dissemination of results in public outreach lectures and via the Worldwide Hydrobiogeochemical Observatory Network for Dynamic River Systems (WHONDRS).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

大型水坝（15米高）是对流域的主要人为干扰，改变了河流生态系统的结构和功能。洛东江是受河口大坝影响严重的流域之一，大坝的目的是阻止潮汐海水交换。当它在1987年建成时，大坝引起了下游生态系统的巨大变化，将该地区转变为人造淡水水库。河水流量的改变导致季节性有害藻华和水质退化。对这些负面影响的日益关注沿着相关的社会和经济需求，导致通过拆除大坝来恢复河流生态系统。大坝拆除将通过一系列打开大坝闸门的事件以受控的方式进行，从而允许海水侵入上游生态系统。这为研究海水入侵对淡水生态系统的影响提供了一个独特而直接的机会。一系列计划中的大坝开闸可以有效地用作一个大规模的、前所未有的、可操纵的生态系统实验。这个RAPID项目利用这个独特的机会来研究沉积物微生物群落对河流中程序化海水入侵的反应。该项目将包括为本科生和研究生提供培训机会，并将通过公开讲座和河流研究人员科学网络传播成果。本项目旨在研究沉积物氮（N）循环群落的功能稳定性，响应于海水入侵的干扰，在洛东江，大坝拆除是通过一系列的大坝闸门的开口。多组学方法，包括宏基因组学，元转录组学和元蛋白质组学分析将进行评估的敏感性和弹性的个人N代谢在一个社区，而N循环过程（通量和速率）的测量，包括反硝化和异化硝酸盐还原为铵，揭示了整个社区的代谢响应海水入侵。这是一个独特的和变革性的项目，以确定在淡水生态系统中暴露于程序化海水入侵的社区内不同代谢的功能稳定性。多组学和生物地球化学测量相结合，将提供从基因到个体生物再到群落水平的不同系统水平的敏感性和恢复力的新知识。沉积物群落中的异化氮循环代谢被选为微生物功能的模型，因为底栖氮循环是至关重要的，以减轻过量的氮负荷，富营养化的原因。鉴于底栖生物氮循环的重要性，海水入侵对沉积物氮循环群落及其功能的影响主要是通过非原位实验设计，如微型生态系统和中型生态系统，或沿河流和河口沿着盐度梯度的实地调查来研究的。这第一个项目代表了第一个生态系统规模的操作检查沉积物N循环社区响应海水入侵。两名研究生将参与该项目，并将接受多组学和生物化学方法的培训。该项目还将包括为两个机构的本科生开展培训活动，通过公共宣传讲座和全球动态河流系统水文地球化学观测网络（WHONDRS）传播成果。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。