Committee Chair

Schorr, Mark

Committee Member

Barbosa, Jose; Carroll, Andy; Richards, Sean; Elwell, Jeffery; Walker, Randy


Dept. of Biological and Environmental Sciences


College of Arts and Sciences


University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)


The Redbreast Sunfish (Lepomis auritus) was introduced in the Tennessee River drainage (TRD) in the 1940s, and contemporary anecdotal evidence suggests that L. auritus is possibly displacing the native Longear Sunfish (Lepomis megalotis). This study aimed to characterize temporal patterns in regional abundances of L. auritus and L. megalotis populations in the TRD based on a multiyear analysis of historical and contemporary fish assemblage datasets (percent abundance, density, biomass). Results indicate that L. megalotis abundance declined in reservoirs where L. auritus was found in high or increasing abundances. Also, L. auritus surpassed L. megalotis in mean percent abundance in Nickajack-Chickamauga River section and has consequently shifted Lepomis species composition. Although it is difficult to isolate causal variables, the interaction of both biotic (i.e., L. auritus competition) and abiotic (i.e., geographic variables, land use, and water quality) factors likely explain the changes in L. megalotis abundance and variability within river sections.


First, I would like to express my gratitude to Dr. Mark S. Schorr for working as my thesis advisor and for giving me this opportunity. His continuous guidance and assistance throughout my time at the University of Tennessee at Chattanooga is greatly appreciated, and his mentorship has enhanced my growth as a researcher and biologist. I would also like to express gratitude to Andy Carroll for his guidance with GIS and development of range maps. Further, I wish to thank the remainder of my thesis committee, Dr. Jose Barbosa, Dr. Sean Richards, and Charles Saylor for their helpful comments and guidance. To the Biological and Environmental Science Department at the University of Tennessee at Chattanooga, thank you for making this project possible through research and teaching assistantships. To the Tennessee Valley Authority, thank you for providing fish assemblage data for analysis. Lastly, I would like to thank my family and friends for their constant support and encouragement throughout this process.


M. S.; A thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Master of Science.




Freshwater fishes -- Tennessee River Watershed; Sunfishes -- Tennessee River Watershed; Displacement activity (Animal behavior)


Species introductions; Fish distribution; Lepomis

Document Type

Masters theses




xvi, 261 leaves