Collaborative Research: Meta-Ecosystems and the Upstream Legacy: Influence of Dissolved Organic Matter on the Structure and Function of Streambed Bacterial Communities

有机碳以溶解分子的形式在溪流中运输，被生活在河床上的微生物加工成能量。这一过程构成了全球碳循环的一个关键环节。大部分河流碳的来源是小流域内的上层土壤和生活在河流中的藻类。通过观察排水网络，研究人员将探索有机分子的质量如何随着下游距离的变化而变化，以及这些变化如何影响利用该食物资源的河床微生物群落的组成。为了描述溶解在溪流中的数千个单独的有机分子和生活在溪流中的微生物的巨大多样性，研究小组将开发新的方法，将分子微生物学和分析有机地球化学的新前沿联系起来。该提案将在温带和热带森林内的小溪流到小河流的大小不等的水域中进行。研究目标包括在排水网络中推进河流生态系统的知识，并在全球碳循环中建立一个广泛的河流生态系统模型。了解全球碳循环是社会的一项重要科学需求，最近的研究表明，淡水溪流和河流在其中发挥了重要作用。通过更好地理解溪流微生物与淡水溪流中有机碳之间的关系，这项研究将有助于我们对全球碳循环的一个关键组成部分的全面理解。因为微生物是肉眼看不见的，所以很难让学生对微生物和有机分子的多样性以及它们之间生态相互作用的复杂性感到兴奋。研究小组将开发教育材料，描述微生物学和有机地球化学的基本概念，重点是微生物在水生生态系统中发挥的重要作用。在每个研究集水区的设施里，调查人员和他们的教育工作者同事将举办为期两天的暑期教师讲习班，让中学教师接触溪流的微生物世界。讲习班的时间安排将使参与者能够反映科学家的实地和实验室活动。此外，项目期间还将培养1名研究生、1名博士后、7名本科生。

Organic carbon, in the form of dissolved molecules transported in stream water, is processed for energy by microorganisms that live on the streambed. That processing constitutes a critical link in the global carbon cycle. The sources of much of the stream carbon are the upper layer of soils within small watersheds and algae that live in streams. Looking out over a drainage network, the investigators will explore how the quality of the organic molecules changes with distance downstream and how those changes influence the composition of the communities of streambed microbes using that food resource. To characterize the thousands of individual organic molecules dissolved in stream water and the vast diversity of microorganisms living in streams, the research team will exploit novel methods that link the new frontiers in molecular microbiology and analytical organic geochemistry. This proposal will be carried out in waters that range in size from small streams to small rivers within temperate and tropical forests. The research goals include advancing knowledge of stream ecosystems across drainage networks and forging a broad model of stream ecosystems in the global carbon cycle.Understanding the global carbon cycle is a critical scientific need of society and recent studies suggest that freshwater streams and rivers play a significant role within it. By better understanding the relationships between stream microorganisms and the organic carbon in freshwater streams, this study will contribute to our overall understanding of a key component of the global carbon cycle. Because microorganisms are invisible to the naked eye, getting students excited about the diversity of microorganisms and organic molecules and the complexity of their ecological interactions is difficult. The research team will develop educational materials that depict the basic concepts in microbiology and organic geochemistry with an emphasis on the vital roles that microorganisms play in aquatic ecosystems. At facilities within each of the study catchments the investigators and their educator colleagues will hold two-day summer teacher workshops to expose secondary school teacher to the microbial world of streams. The workshops will be timed to allow participants to mirror the field and laboratory activities of the scientists. In addition, 1 graduate student, 1 post-doctoral scientist, and 7 undergraduates will receive training during the project.