Collaborative Resarch: Terrestrial Support of Lake Food Webs: A Multi-Isotope Approach

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。生态系统中对动物的支持最终来自两个来源：生态系统内的初级生产（例如新生长的植物材料）或从其他生态系统进口的初级生产（例如向水生系统输入的陆地材料）。在湖泊中，众所周知，与内部初级生产相比，外部投入很大，但这些物质如何支持湖泊食物网的记录较少。氘是氢的稳定同位素，陆地和水生初级生产者的氘含量有显著差异。碳和氮稳定同位素比率虽然对比不太好，但当与氘相结合时，也有助于区分消费者支持的来源。因此，对氢、碳和氮稳定同位素的综合分析可以区分湖泊动物和微生物对内部和外部初级生产的利用。在这项提议中，pi将使用稳定同位素碳、氮和氢的测量，以及一种新的建模方法来测试关于水生消费者陆地补贴变化的假设，以及这些变化在不同类型湖泊之间的差异。多同位素方法还将应用于整个湖泊的养分施肥试验，以测试底栖生物和远洋生物在外部有机质支持下的差异。这项研究将直接测量外部物质对消费者支持的变化，并有助于理解这些过程中生态系统之间变化的驱动因素。本项目将培养若干本科生和2名研究生，涉及生态系统生态学、湖沼学、模型学和稳定同位素方法学。这项研究的结果将直接用于pi教授的课程。本研究中使用的稳定同位素模型将是其他研究人员感兴趣的工具。在开放存取软件上运行的模型将通过我们的网站与文档、教程和测试数据一起提供。此外，原子能机构建议在一次关于同位素研究建模方法的全国会议上赞助一个半天的讲习班。为更大的研究界提供多同位素模型方法将是该项目更广泛影响的重要组成部分。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The support of animals in ecosystems ultimately comes from two sources: primary production within an ecosystem (e.g. newly grown plant material) or primary production imported from other ecosystems (e.g. inputs of terrestrial material to an aquatic system). In lakes, it is well known that external inputs are large compared to internal primary production, but how these materials support lake food webs is less well documented. Deuterium is a stable isotope of hydrogen and deuterium content of terrestrial and aquatic primary producers is significantly different. Carbon and nitrogen stable isotope ratios, while less well contrasted, are also helpful, when coupled with deuterium, in discriminating sources of consumer support. Thus, integrated analysis of hydrogen, carbon and nitrogen stable isotopes can distinguish the use of internal versus external primary production by lake animals and microbes. In this proposal the PIs will use measurements of the stable isotopes carbon, nitrogen, and hydrogen along with a new modeling approach to test hypotheses about variation in terrestrial subsidies of aquatic consumers and how these vary among different types of lakes. The multi-isotope approach will also be applied to a whole lake nutrient fertilization experiment to test differences in the support of benthic versus pelagic consumers by external organic matter. This research will directly measure variation in the support of consumers by external materials and contribute to understanding the drivers of variation among ecosystems in these processes. Several undergraduates and 2 graduate students will receive training through this research in ecosystem ecology, limnology, modeling, and stable isotope methodology. Results from this research will contribute directly to courses taught by the PIs. The stable isotope model to be utilized in this study is a tool that will be of interest to other researchers. The model which runs on open access software will be made available through our website along with documentation, tutorials, and test data. In addition, the PIs propose to sponsor a half-day workshop at a national meeting on modeling methods in isotopic studies. Providing a multi-isotope model approach to the larger research community will be a significant component of the Broader Impacts of this project.