Linking carbon to structure and function in aquatic ecosystems

淡水生态系统是生物地球化学热点，在全球碳循环中发挥重要作用，特别是与其相对较小的地理足迹有关。湖泊和河流呼吸碳的速率(“新陈代谢”)是这些生态系统的一个关键特征。淡水新陈代谢难题的一个核心部分是溶解有机物(DOM)，因为它非常普遍，而且在整个景观(从陆地到海洋)中都有很高的流动性。DOM作为微生物的底物，影响光环境，并控制淡水生态系统中不同的食物网和生态系统过程。虽然DOM的数量已被认为是许多湖泊和河流性质的核心决定因素，但越来越清楚的是，并非所有DOM在化学上都是相同的，其化学成分(其质量)在水生生态系统内和水生生态系统之间存在差异。在这个项目中，我将研究DOM的数量和质量如何受到营养物质的影响，以及DOM质量和营养物质如何反过来调节溪流、河流和湖泊的生态功能。通过一系列的实地调查和实验，我们将评估DOM的来源，确定DOM的移动和损失的途径，并了解DOM质量的模式，因为它们与淡水生态系统中的营养物质在时间和空间上有关。这些关于碳转化和通量的生物地理化学控制的信息对于理解全球变化和土地利用变化对不同景观的淡水生态系统的影响是不可或缺的。我的研究团队将包括至少15名非常不同的学生，我将指导他们完成多学科的研究论文，这些论文可以包括生态系统生态学、水化学、生物活性、水文运输和数学的原理。最后，他们的研究论文可以向管理机构提供关于DOM、其与营养物质的相互作用、其在水生系统中的保留及其对生态功能的影响的信息，对生态系统健康和生态系统服务(例如，娱乐、饮用水、富营养化)具有重大影响。

Freshwater ecosystems are biogeochemical hotspots that play an important role in the global carbon cycle especially in relation to their relatively small geographic footprint. The rates at which lakes and rivers respire carbon (“metabolism”) is a key characteristic of these ecosystems. A central piece of the freshwater metabolism puzzle is dissolved organic matter (DOM), due to its very high prevalence and mobility across the landscape (from land to sea). DOM serves as a substrate for microbes, affects the light environment, and controls diverse food web and ecosystem processes in freshwater ecosystems. While DOM quantity has been recognized to be a central determinant of many lake and river properties, it is becoming increasingly clear that not all DOM is chemically equivalent and that its chemical composition (its quality) varies within and among aquatic ecosystems. In this project, I will examine how DOM quantity and quality is affected by nutrients and how, in turn, DOM quality and nutrients regulate ecological function in streams, rivers and lakes. Through a series of field surveys and experiments we will assess sources of DOM, determine pathways of DOM movement and loss, and understand patterns of DOM quality as they relate to nutrients in freshwater ecosystems through time and space. This information on the biogeochemical controls of carbon transformations and fluxes is integral to understanding the effects of global change and land use change on freshwater ecosystems across landscapes. My research team will include at least 15 highly diverse students that I will mentor to complete multidisciplinary research theses that can include principles of ecosystem ecology, water chemistry, biological activity, hydrological transport and mathematics. Finally, their research theses can provide information to management agencies on DOM, its interaction with nutrients, its retention in aquatic systems and its effects on ecological function with significant implications for ecosystem health and ecosystem services (e.g., recreation, drinking water, eutrophication).