Doctoral Dissertation Research: Reconstruction of Alpine Aquatic Ecosystem Responses to Temperature Changes

地理学空间科学（GSS）项目本博士论文研究将调查高海拔水生生态系统在第四纪和更新世-全新世时期对放大的热条件的反应。 具体来说，研究将侧重于重建近期和长期的环境条件，在高山和亚高山湖泊在科罗拉多落基山脉的前线。 将提供新的见解，这些淡水系统的变化将如何影响食物网机制，捕食者/猎物的动态和入侵物种在这些关键的生态系统的扩张。 此外，这项研究将促进我们了解水生生态系统的结构、功能和组成的这种变化将如何影响淡水资源的获取和可供娱乐和经济用途。 这项研究的结果将为资源管理者提供新的信息，有助于管理持续环境变化对生态和经济的影响。 博士生将与政府机构合作，创造和传播材料，以进一步公众教育和宣传。 作为博士论文研究改进奖，该奖项将为有前途的学生提供支持，使其能够建立强大的独立研究事业。将来自加速冰川融化的寒冷，富含泥沙的水添加到高山水生生态系统中将影响这些系统的物理和地球化学条件。 了解以前的冰川到现在的间冰期条件的过渡特征的变化幅度和速度将建立一个基线比较水生生态系统的现代热放大的反应。 博士生将进行成对的冰川和非冰川湖泊的研究，以评估在最近的过去和更新世-全新世过渡期间，冰川融水输入对摇蚊群落的抑制作用，并记录高山和亚高山环境中水生生态系统对冰川退缩的反应。 摇蚊是苍蝇的一个家族，它们的幼虫和蛹是鳟鱼等鱼类的重要食物。 为了重建过去的环境条件，将收集湖泊沉积物岩心，并使用碳（C）和氮（N）同位素分析来分析摇蚊遗骸的丰度。 该研究将应用基于摇蚊的推理模型来描述水生生态系统生产力随时间的变化。 C的变化将被用来跟踪湖泊和流域内的植被变化，N的波动将被用来建立湖泊生产力的变化以及湖泊的营养状态。

NATIONAL SCIENCE FOUNDATIONGEOGRAPHY SPATIAL SCIENCES (GSS) PROGRAMABSTRACTThis doctoral dissertation research will investigate the responses of high elevation aquatic ecosystems to amplified thermal conditions during the Quaternary and the Pleistocene-Holocene periods. Specifically, the research will focus on reconstructing recent and long-term environmental conditions in the alpine and sub-alpine lakes in the Front Range of the Colorado Rockies. New insights will be provided on how the changes in these freshwater systems would affect food web mechanisms, predator/prey dynamics and the expansion of invasive species in these critical ecosystems. Furthermore, the research will advance our understanding of how such changes in the structure, function and composition of aquatic ecosystems would impact access and availability of freshwater resources for recreational and economic use. Findings from this research will provide resource managers with new information that will help in managing the ecological and economic impacts of ongoing environmental changes. The doctoral student will work with government agencies to create and disseminate materials to further public education and outreach. As a Doctoral Dissertation Research Improvement award, this award will provide support to enable a promising student to establish a strong independent research career.The addition of cold, silt-enriched water from accelerated glacial melt into alpine aquatic ecosystems will impact the physical and geochemical conditions of these systems. Understanding the magnitude and rate of change that characterized the transition from the previous glacial to the present interglacial conditions will establish a baseline for comparison of aquatic ecosystem responses to modern thermal amplifications. The doctoral student will conduct a paired study of glaciated and unglaciated lakes to assess the dampening effect of glacial meltwater input on chironomid communities during the recent past and during the Pleistocene-Holocene transition, and document the response of aquatic ecosystems in alpine and subalpine environments to glacial ice retreat. Chironomids are a family of flies and their larvae and pupae are important food items for fish such as trout. To reconstruct past environmental conditions, lake sediment cores will be collected and analyzed for abundance of chironomid remains using Carbon (C) and Nitrogen (N) isotope analyses. The research will apply a chironomid-based inference model to describe changes in the productivity of the aquatic ecosystems through time. Variations in C will be used to track vegetation change within the lake and catchment and fluctuations in N will be used to establish changes in lake productivity as well as the trophic status of the lakes.