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

University Of Georgia Research Foundation Inc, Athens GA

Investigators

Abstract

NATIONAL SCIENCE FOUNDATION GEOGRAPHY SPATIAL SCIENCES (GSS) PROGRAM ABSTRACT This 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.