Dissertation Research: Environmental Controls on Stream Bacterial Community Structure & Metabolic Function

了解生物群落如何影响碳的命运是生态系统科学面临的最大挑战之一。淡水生态系统，包括溪流，现在被认为是大量有机物质的运输、加工和埋藏的场所。包括细菌在内的微生物群落在河流中有机物的处理中占绝大多数，但关于微生物群落如何影响河流中有机物的命运，还有很多未知之处。该项目将通过研究细菌群落多样性、溪流水化学和有机物组成如何影响有机物是否被溪流微生物消耗或向下游运输来解决这一知识缺口。将进行一个围隔实验，以测试pH值和有机物组成的变化将影响河流微生物群落及其处理有机物的能力的假设。遗传细菌群落指纹将用于量化细菌群落对实验处理的反应。 本研究将利用酵素分析及整体代谢率来测量细菌的代谢反应，有助了解淡水中微生物群落结构与代谢的关系。 由于人类活动改变了流域，水生生态系统的pH值和有机物投入也在发生变化。由于溪流可以被视为环境变化的哨兵，这项研究将产生深入了解淡水社区对全球变化的反应。本科研究人员将从事工作的各个方面，以进一步提高他们的科学认识。结果将在科学会议和期刊上公布。将为当地小学生编制教育材料，协助解释这项工作和更广泛的生态系统生态学概念。

Understanding how the fate of carbon is influenced by biological communities is one of the greatest challenges in ecosystem science. Freshwater ecosystems, including streams, are now recognized as sites for the transport, processing, and burial of substantial amounts of organic matter. Communities of microbes, including bacteria, account for a vast majority of the processing of organic matter in streams, but there is much that is not known about how microbial communities impact the fate of organic matter in streams. This project will address this knowledge gap by studying how bacterial community diversity, stream water chemistry, and organic matter composition influence whether organic matter is consumed by stream microbes or transported downstream. A mesocosm experiment will be conducted to test the hypothesis that changes in pH and organic matter composition will impact the stream microbial community and its ability to process organic matter. Genetic bacterial community fingerprints will be used to quantify how the bacterial community responds to the experimental treatments. Bacterial metabolic responses will be measured using enzyme assays and overall metabolic rates.This project will contribute to understanding of the relationship between microbial community structure and metabolism in freshwaters. As watersheds are altered by human activity, pH and organic matter inputs to aquatic ecosystems are also changing. Since streams may be viewed as sentinels for environmental change, this study will generate insight into the response of freshwater communities to global change. Undergraduate researchers will be engaged in all aspects of the work to further their scientific understanding. Results will be communicated at scientific meetings and in journals. Educational materials will be developed for local primary school students that assist in interpreting this work and broader concepts of ecosystem ecology.