EAGER: Discovering how geologic and fossil methane sources support a contemporary river ecosystem

碳是生命的基本组成部分。对于溪流和湖泊中的大多数动物（昆虫，鱼类，浮游生物）来说，碳最初是二氧化碳，然后被藻类和植物捕获。这些碳然后传递给浮游生物，昆虫和鱼类。最近的研究表明，河流中可能有其他碳源，如支持水生植物和藻类的甲烷。然而，人们对这种甲烷的来源以及它如何融入河流，溪流和湖泊中的生命知之甚少。在地质或地热活动频繁的地区，甲烷可能被释放到地下水和河流中。这项EAGER奖将进行第一项研究，探索地质和化石甲烷作为替代碳源在支持河流洪泛区生命中的作用。该奖项还将支持学生和博士生的研究培训，让鱼类孵化场管理人员参与公民科学研究，并向公众提供河流系统如何运作的知识。地球上大多数生态系统的基本假设是，现代二氧化碳的固定推动了生产力和生物多样性，而很少认识或研究其他潜在的碳途径（例如，甲烷）作为生产力和生物多样性的驱动力。尽管化石和地质甲烷可能对淡水系统有贡献，而且甲烷有可能在生态上转化为危害较小的形式，但对影响这种温室气体来源的淡水生物过程知之甚少。该EAGER奖将调查非生物，产热和化石产甲烷甲烷补贴在支持淡水洪泛区生态系统中的作用，为碳有限的浅层含水层食物网（深潜流区）提供碳源。该奖项的目的是量化各种甲烷来源对含水层食物网的碳贡献。创新的稳定同位素方法将用于评估碳源，并通过洪泛区食物网追踪它们，然后开发新的方法来发现甲烷源对淡水生态系统的贡献。这项研究可能会改变目前以二氧化碳为基础的驱动生产力和生物多样性的范式，证明河流洪泛平原以下的浅层含水层食物网是由地质和化石甲烷衍生的碳驱动的。因此，这些洪泛区含水层将是第一个在概念上和生态上与海洋热液喷口生态系统类似的范例。该奖项反映了NSF的法定使命，并被认为值得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来支持。

Carbon is a fundamental building block of life. For most animals (insects, fish, plankton) in streams and lakes the carbon starts out as carbon dioxide and then is captured by algae and plants. This carbon then passes on to plankton, insects, and fish. Recent studies suggest there might be other sources of carbon in rivers such as methane that are supporting aquatic plants and algae. However, little is known about the sources of this methane and how it gets incorporated into the life in rivers, streams, and lakes. Methane may be released to groundwater and streams in areas with high geologic or geothermal activity. This EAGER award will conduct the first study to explore the role of geologic and fossil methane as an alternative carbon source in supporting life in river floodplains. The award will also support research training of students and doctoral scholars, engage fish hatchery managers in citizen science research, and provide knowledge of how river systems function to the public. The underlying assumption for most ecosystems on Earth is that the fixation of modern carbon dioxide drives productivity and biodiversity, with little recognition or study of other potential carbon pathways (e.g., methane) as drivers of productivity and biodiversity. Despite the likely contribution of fossil and geologic methane to freshwater systems and the potential for methane to be transformed ecologically into less harmful forms, the freshwater biotic processes affecting this greenhouse gas source are poorly known. This EAGER award will investigate the role of abiotic, thermogenic, and fossil methanogenic methane subsidies in supporting freshwater floodplain ecosystems by providing a carbon source to the carbon-limited shallow aquifer food web (deep hyporheic zone). The objective of this award is to quantify contributions of carbon from various methane sources to the aquifer food web. Innovative stable isotope methods will be used to assess the carbon sources and trace them through the floodplain foodweb, then develop new approaches for discovering methane source contributions to freshwater ecosystems. This research could potentially shift the current carbon dioxide-based paradigm of driving productivity and biodiversity by demonstrating that shallow aquifer food webs below river floodplains are driven by geologic and fossil methane-derived carbon. Therefore, these floodplain aquifers would be the first to demonstrate a conceptually and ecologically analogous paradigm to oceanic hydrothermal vent ecosystems.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.