Seasonal Primary Productivity and Nitrogen Cycling in Photosynthetic Mats, Lake Fryxell, McMurdo Dry Valleys

麦克默多干谷光合垫的季节性初级生产力和氮循环

• 批准号: 1937748
• 负责人: Dawn Sumner
• 金额: $ 79.92万
• 依托单位: University of California-Davis
• 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: 2020-08-15 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1937748&HistoricalAwards=false
• 关键词: Seasonal; Primary; Productivity; Nitrogen; Cycling

Part I: Non-technical summary:This project focuses on understanding annual changes in microbial life that grows on the bottom of Lake Fryxell, Antarctica. Because of its polar latitude, photosynthesis can only occur during the summer months. During summer, photosynthetic bacteria supply communities with energy and oxygen. However, it is unknown how the microbes behave in the dark winter, when observations are not possible. This project will install environmental monitors and light-blocking shades over parts of these communities. The shades will extend winter conditions into the spring to allow researchers to characterize the winter behavior of the microbial communities. Researchers will measure changes in the water chemistry due to microbial activities when the shades are removed and the mats first receive light. Results are expected to provide insights into how organisms interact with and change their environments. The project includes training of graduate students and early career scientists in fieldwork, including scientific ice diving techniques. In addition, the members of the project team will develop a web-based “Guide to Thrive”, which will compile field tips ranging from basic gear use to advanced environmental protection techniques. This will be a valuable resource for group leaders ranging from undergraduate teaching assistants to Antarctic expedition leaders to lead well-planned and tailored field expeditions. Part II: Technical summary:The research team will measure seasonal metabolic and biogeochemical changes in benthic mats using differential gene expression and geochemical gradients. They will identify seasonal phenotypic differences in microbial communities and ecosystem effects induced by spring oxygen production. To do so, researchers will install environmental sensors and opaque shades over mats at three depths in the lake. The following spring, shaded and unshaded mats will be sampled. The shades will then be removed, and changes in pore water O2, H2S, pH, and redox will be measured using microelectrodes. Mats will also be sampled for transcriptomic gene expression analyses at intervals guided by geochemical changes. Pore water will be sampled for nutrient analyses. Field research will be supplemented with laboratory experiments to refine field techniques, gene expression data analysis, and integration of results into a seasonal model of productivity and nitrogen cycling in Lake Fryxell. Results will provide insights into several key priorities for NSF, including how biotic, abiotic and environmental components of the benthic mats interact to affect Antarctic lakes.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.

第一部分：非技术摘要：该项目重点了解生长在南极洲弗里克塞尔湖底部的微生物生命的年度变化，由于其极地纬度，光合作用只能发生在夏季，光合细菌供应。然而，在无法进行观测的黑暗冬季，微生物的行为尚不清楚。该项目将在这些群落的部分区域安装环境监测器和遮光帘。将冬季条件延长到春季，以便研究人员能够表征微生物群落的冬季行为。研究人员将测量当遮蔽物被移除且垫子首次接受光照时由于微生物活动而引起的水化学变化。该项目包括对研究生和早期职业科学家进行实地考察，包括科学的冰潜水技术。此外，项目团队的成员将开发基于网络的“繁荣指南”。这将编译从基本装备到范围的现场技巧这对于从本科生助教到南极探险队领导者等领导精心策划和定制的野外探险来说都是宝贵的资源。第二部分：技术摘要：研究小组将测量季节性代谢和生物地球化学。他们将利用差异基因表达和地球化学梯度来识别底栖垫的季节性表型差异以及春季氧气产生引起的生态系统影响，为此，研究人员将在三层的垫子上安装环境传感器和不透明的阴影。来年春天，将对遮蔽和未遮蔽的垫子进行采样，并使用微电极对孔隙水 O2、H2S、pH 和氧化还原进行采样，以进行转录组学分析。基因表达分析间隔将在地球化学变化的指导下进行采样，以进行营养分析。现场研究将得到实验室实验的补充，以完善现场技术、基因表达数据分析并将结果整合到季节性模型中。弗里克塞尔湖的生产力和氮循环的结果将为 NSF 的几个关键优先事项提供见解，包括底栖垫的生物、非生物和环境成分如何相互作用影响南极湖泊。该奖项反映了 NSF 的法定使命，并被认为值得支持。通过使用基金会的智力优点和更广泛的影响审查标准进行评估。