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

国家科学基础地理空间科学(GSS)进展这篇博士论文将研究高海拔水生生态系统在第四纪和更新世-全新世期间对放大的热条件的响应。具体地说，这项研究将侧重于重建科罗拉多州落基山脉前缘高山和亚高山湖泊的近期和长期环境状况。将就这些淡水系统的变化将如何影响食物网机制、捕食者/猎物动态以及这些关键生态系统中入侵物种的扩张提供新的见解。此外，这项研究将增进我们对水生生态系统结构、功能和组成的这种变化将如何影响用于娱乐和经济用途的淡水资源的获取和供应的理解。这项研究的结果将为资源管理者提供新的信息，有助于管理正在进行的环境变化对生态和经济的影响。博士生将与政府机构合作，创建和传播材料，以进一步开展公共教育和宣传。作为博士论文研究改进奖，该奖项将为有前途的学生建立强大的独立研究事业提供支持。冰川加速融化产生的富含泥沙的冷水加入高山水生生态系统将影响这些系统的物理和地球化学条件。了解从前一次冰川过渡到目前间冰期条件的变化幅度和速度，将为比较水生生态系统对现代热放大的反应奠定基线。这位博士生将对冰川湖泊和未冰川湖泊进行配对研究，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的水生生态系统对冰川冰消退的反应。摇蚊是苍蝇的一个家族，它们的幼虫和蛹是鲑鱼等鱼类的重要食物。为了重建过去的环境条件，将收集湖泊沉积岩心，并使用碳(C)和氮(N)同位素分析来分析摇蚊遗迹的丰度。这项研究将应用基于摇摆学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内的植被变化，集水和N的波动将被用来确定湖泊生产力以及湖泊的营养状态的变化。

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.