Date of Award

1-1-2011

Document Type

Campus Access Thesis

Department

Earth and Ocean Sciences

Sub-Department

Earth and Environmental Resources Management

First Advisor

John Kupfer

Abstract

A cyanobacterial epiphyte in the order of Stigonematales has affected waterfowl and their avian predators on Lake J. Strom Thurmond since 1998. Avian mortalities caused by Stigonematales occur on Lake Thurmond from October through March. The purpose of this study was to examine the factors that may influence Stigonematales abundance at 20 sites on Lake Thurmond. The factors examined in this study were: dissolved oxygen, temperature, turbidity, copper, zinc, fluoride, chloride, nitrate, sulfate, phosphate, hydrilla abundance and previous Stigonematales abundance. Measurements (dissolved oxygen, water temperature) or water samples (turbidity, nutrient content) were taken at three different depths: one surface reading (epilimnion), one reading at 1 meter (metalimnion), and one reading near the bottom (hypolimnion). Relationships between the abundance of Stigonematales and the independent environmental factors were analyzed using generalized linear modeling (GLM) with a cumulative logit link function. The significance of main variable effects associated with the abundance of Stigonematales was tested using both forward and backward stepwise variable entry. The statistical significance of individual ecological factors was tested with a Wald chi-square test and Bonferroni corrected follow-up test. Non-significant variables were then removed and the data were re-analyzed using the significant variable and two-way interaction terms effects among the variables. The results of this study would be useful in the development of a predictive model to help identify areas prone to high abundance of Stigonematales and enable managers to reduce the submersed aquatic vegetation hosting the Stigonematales, thereby reducing the Stigonematales availability to waterfowl.

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