Term of Award

Fall 2023

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Department of Biology

Committee Chair

James Roberts

Committee Member 1

J. Checo Colón-Gaud

Committee Member 2

Stephen Vives


The geographic complexity of the Southeastern United States, in particular Georgia, is evident in the diversity of stream habitats present throughout that host unique stream fish communities but is threatened by anthropogenic activity. This spatial complexity can be captured through the ecoregion framework, which delineates areas of distinct habitat. However, this differing habitat character between ecoregions leads to different environmental pressures that may promote species heterogeneity between communities, may create intraspecific niche diversity in widely distributed species, and may complicate the transferability of widely accepted theoretical models of fish ecology between them. I analyzed a long-term fish community dataset, examining abiotic, taxonomic, and functional variation between communities across Georgia to assess the roles of local and regional environmental variables in structuring community composition and the role of ecoregion in mediating these relationships. I found that taxonomic and functional community variation were more affected by region-scale processes than by local variation. Further, although I found that ecoregion was effective in capturing this heterogeneity, biogeographic effects through basin similarity also significantly affects community composition. I assessed individual ecological variation in response to changes in stream size, ecoregion, and season through variations in diet composition in Redbreast Sunfish (Lepomis auritus), a widely distributed generalist feeder. I found that stream size and ecoregion significantly affect prey richness and the relative contribution of terrestrial prey items to their diets. My findings highlight the importance of region-scale processes in shaping local stream fish ecology through the fitness of their individuals and the composition of their communities.

Research Data and Supplementary Material