EAR-PF: Linking lakes to the landscape: mechanisms that control terrestrial subsidies to pelagic food webs

Steven Sadro博士被授予美国国家科学基金会地球科学博士后奖学金，在加州大学河滨分校实施一项研究和教育计划。他将采用比较和实验的方法来研究陆源输入湖泊的浓度和组成的变化对陆源碳向远洋食物网转移的影响程度。陆地生态系统向湖泊输出了相当数量的有机物质，但这些物质对远洋食物网的支持程度存在争议，人们对这种补贴的环境控制知之甚少。在这项研究中，碳（13C和14C）、氮（15N）和氢（2H）同位素的自然丰度将被用来确定陆地对水生食物网的贡献。将利用陆地输入的数量和质量的季节和空间驱动的变化以及实验操作来说明控制向远洋生物的碳转移的机制。这些研究将在高海拔湖泊中进行，这些湖泊在海拔和融雪动态驱动下具有一致的溶解有机质组成时空格局，使其成为碳流生态系统研究的理想天然实验室。湖泊是陆生有机物的天然储存库。这些物质在湖泊中分解、储存或生物循环的程度对能量流、食物网结构以及最终以二氧化碳的形式输出或释放回大气的碳量具有重要意义。然而，陆地碳被纳入水生食物网的证据仍然存在争议。通过描述控制水生食物网中陆地碳流动的机制，本研究将阐明生物之间的联系，并有助于完善水生系统的食物网模型。此外，高海拔生态系统对气候变暖的影响较为敏感；特别是，了解这些系统中的碳循环是预测土壤、植被和水文动态的持续变化如何影响水生生态系统的关键的第一步。Sadro博士将直接将本科生纳入本研究的实地和实验室方面。他将协助开发和领导一门大学水生生态系统科学课程，该课程在内华达山脉水生研究实验室设施教授，该实验室位于塞拉利昂东部的加州大学保护区。Sadro博士还将致力于开发一门分水岭教育课程，为加州维萨利亚附近的西内华达山脉伍德莱克联合高中中代表性不足的中学生提供服务。

Dr. Steven Sadro has been awarded an NSF Earth Sciences Postdoctoral Fellowship to implement a research and education program at the University of California, Riverside. He will use comparative and experimental approaches to investigate the extent to which variability in the concentration and composition of terrigenous inputs to lakes affects the transfer of terrestrial carbon into pelagic food webs. Terrestrial ecosystems export a considerable amount of organic matter into lakes, but the degree to which such material supports pelagic food webs is debated, and the environmental controls of such subsidies are poorly understood. In this study, the natural abundance of carbon (13C and ∆14C), nitrogen (15N), and hydrogen (2H) isotopes will be used to determine terrestrial contributions to aquatic food webs. Seasonal and spatial driven variation in the quantity and quality of terrestrial inputs will be used along with experimental manipulations to illustrate mechanisms of control on carbon transfers to pelagic organisms. These studies will be carried out in high-elevation lakes, which have consistent spatiotemporal patterns in dissolved organic matter composition driven by elevation and snowmelt dynamics, making them ideal natural laboratories for ecosystem studies of carbon flow. Lakes are natural repositories of terrestrial organic matter. The extent to which this material is decomposed, stored, or biologically cycled within lakes has important implications for energy flow, food web structure, and ultimately, the amount of carbon that is exported or released back into the atmosphere as carbon dioxide. However, evidence that terrestrial carbon is incorporated into aquatic food webs remains controversial. By characterizing the mechanisms that control the flow of terrestrial carbon in aquatic food webs, this research will illustrate linkages between organisms and help refine food web models for aquatic systems. Furthermore, high-elevation ecosystems are sensitive to the effects of climate warming; understanding carbon cycling in these systems, in particular, is a critical first step in predicting how ongoing changes in soil, vegetation, and hydrological dynamics will affect aquatic ecosystems. Dr. Sadro will directly incorporate undergraduates in both field and laboratory aspects of this research. He will assist in developing and leading a university field aquatic ecosystem science course taught at the Sierra Nevada Aquatic Research Laboratory facilities, a UC Reserve located in the eastern Sierra. Dr. Sadro will also contribute to the development of a watershed education curriculum serving under-represented secondary school students within the western Sierra Nevada Woodlake Union High School near Visalia, California.