EAGER: Meta-gut Dynamics Influence Aquatic Ecosystem Processes

EAGER：元肠道动力学影响水生生态系统过程

• 批准号: 2103884
• 负责人: Amanda Subalusky
• 金额: $ 29.96万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2103884&HistoricalAwards=false
• 关键词: EAGER; Meta; gut; Dynamics; Influence

When animals defecate or die, they transfer a portion of their gut microbes to the environment, together with the organic matter, nutrients, and metabolic byproducts that comprise their feces or carcasses. Microbial decomposition of these inputs can change the characteristics of an ecosystem. In this EAGER project, the proposed research will test whether this coupled gut-environment system, the 'meta-gut', allows microbial communities from the gut of hippopotami to persist external to the animal and have a greater influence on ecosystem function. Hippos are the focus of this study by this team that specialized in the ecosystem ecology of the Mara River in Kenya, which has thousands of hippos and is the only permanent source of water for wildlife in the world-famous Serengeti National Park. Although environmental microbial communities are traditionally considered important drivers of ecosystem function, demonstration that animal gut microbes can significantly influence ecosystem function directly would represent a paradigm shift in our understanding of the influence of animals on ecosystem processes. This research will increase our understanding of the influence of organic matter loading in aquatic ecosystems, as well as microbial drivers of organic matter decomposition and nitrogen cycling under low oxygen conditions, which are increasingly common in some aquatic ecosystems. This project will train a postdoc and 2-3 undergraduate students in each year of the grant and seek to broaden the participation of underrepresented students in science. Products from this research will be used to develop a module for zoos that have hippo facilities to educate the general public about the important role these animals play in structuring river ecosystems.The proposed study will use an experimental approach based on observations from field research on hippos in the Mara River. Hippos aggregate in slow-moving pools along the river where they defecate large quantities of organic material that alter pool biogeochemistry. Previous research has shown that high subsidy pools, with large hippo inputs and low flushing rates, can become anoxic. As a result, these pools develop microbial communities that closely resemble the hippo gut, suggesting hippo gut microbes may persist in the external environment. Researchers will conduct an experiment in replicated stream mesocosms using coupled, high-frequency sampling of microbial communities and biogeochemical responses to test whether hippo gut microbes can persist and function in the external environment, and whether they influence carbon and nutrient cycling. Hippo feces from a captive animal facility will be added to recirculating streams across a gradient from fresh feces with active gut microbes to sterilized feces with no gut microbes. Presence and activity of microbes from the hippo gut will be measured using metagenomics, metatranscriptomics, and metabolomics, as the mesocosms transition from aerobic to anaerobic metabolism. These measurements will be coupled with detailed measurements on aquatic biogeochemistry, carbon cycling, and nitrogen metabolism. A stochastic population model will simulate how microbes from the hippo gut survive and influence key ecosystem processes in the pools. In addition to training the postdoc and undergraduate students, findings from this research will be shared with resource managers and stakeholders in Kenya, broadening the understanding of the ecological role of hippos and their influences on water resources in the region.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.

当动物排便或死亡时，它们会将肠道微生物的一部分转移到环境中，以及构成它们粪便或身体的有机物、营养物质和代谢副产品。这些输入的微生物分解可以改变生态系统的特征。在这个急切的项目中，拟议的研究将测试这种耦合的肠道-环境系统，即“元肠道”，是否允许河马肠道中的微生物群落在动物外部生存，并对生态系统功能产生更大的影响。河马是这个专门研究肯尼亚马拉河生态系统生态系统的团队的研究重点，马拉河有数千只河马，是世界著名的塞伦盖蒂国家公园野生动物唯一的永久水源。虽然环境微生物群落传统上被认为是生态系统功能的重要驱动力，但证明动物肠道微生物可以直接影响生态系统功能，将代表着我们对动物对生态系统过程的影响的理解的范式转变。这项研究将加深我们对有机物负荷在水生生态系统中的影响，以及在低氧条件下有机物分解和氮循环的微生物驱动因素的理解，这在一些水生生态系统中越来越常见。该项目将在每一年的助学金中培训一名博士后和2-3名本科生，并寻求扩大未被充分代表的学生在科学领域的参与。这项研究的成果将被用来为拥有河马设施的动物园开发一个模块，教育公众这些动物在构建河流生态系统中所起的重要作用。拟议的研究将使用基于对马拉河河马的实地研究的观察结果的实验方法。河马聚集在河边缓慢移动的池塘中，在那里它们排出大量改变池塘生物地球化学的有机物质。此前的研究表明，高补贴池中的河马投入量大，冲水率低，可能会导致缺氧。因此，这些池子形成了与河马肠道非常相似的微生物群落，这表明河马肠道微生物可能会持续存在于外部环境中。研究人员将利用微生物群落和生物地球化学反应的耦合高频采样，在复制的溪流中进行一项实验，以测试河马肠道微生物是否能够在外部环境中生存和发挥作用，以及它们是否影响碳和营养循环。来自圈养动物设施的河马粪便将被添加到再循环的溪流中，从含有活跃肠道微生物的新鲜粪便到没有肠道微生物的消毒粪便。河马肠道微生物的存在和活性将通过元基因组学、后转录组学和代谢组学来测量，因为河马肠道中的微生物从有氧代谢过渡到无氧代谢。这些测量将与水生生物地球化学、碳循环和氮代谢的详细测量相结合。随机种群模型将模拟河马肠道中的微生物如何生存并影响池塘中的关键生态系统过程。除了培训博士后和本科生，这项研究的结果将与肯尼亚的资源经理和利益相关者分享，扩大对河马的生态作用及其对该地区水资源的影响的理解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。