Date of Award
Fall 12-13-2025
Document Type
Thesis
Degree Name
Master of Science in Fisheries and Wildlife Science
Department
Biological Sciences
College
College of Science, Technology, Engineering, & Mathematics
Committee Chair
Dr. Kyler Hecke
Second Committee Member
Dr. Zachary Moran
Third Committee Member
Mr. Matthew Anderson
Program Director
Dr. Thomas Nupp
Dean of Graduate College
Dr. Michael Bradley
Abstract
Intermittent streams are increasingly recognized as vital components of river networks by supporting dynamic fish communities shaped by variable hydrology and habitat connectivity. They are becoming increasingly vulnerable to fragmentation by anthropogenic activities, namely road crossings, dams, and climate shifts that intensify seasonal drying. In response, I conducted two studies in the Illinois Bayou watershed in Arkansas to assess the effects of fragmentation on fish community dynamics and morphology in intermittent streams.
In the first study, I examined temporal fish community dynamics across two barriers: a natural waterfall in Dare Creek and a low-water crossing in Dry Creek. Simultaneously, I evaluated fish movement across the road crossing in Dry Creek. Monthly single-pass backpack electrofishing from October 2023 to December 2024 documented 29 species in Dare Creek and 24 in Dry Creek, with upstream reaches supporting fewer species in both streams. Beta diversity analyses revealed distinct patterns, with Dare Creek exhibiting similar contributions of turnover (species replacement) and nestedness (species loss or gain) while Dry Creek was dominated by turnover. Although community composition varied from month to month over the study, species richness and presence generally rebounded predictably following seasonal hydrologic changes. Mark–recapture modeling indicated low overall recapture probability and rare upstream movement, with body size, but not environmental variables, predicting recapture success. In the second study, I investigated morphological variation in four widespread stream fishes (Creek Chub, Highland Stoneroller, Redfin Darter, and Plains Orangethroat Darter) across upstream and downstream reaches of a waterfall in Dare Creek. Geometric morphometric analyses revealed significant shape differences in three species, with upstream populations generally exhibiting deeper bodies, while both darter species exhibited significantly larger centroid sizes upstream. My findings broaden our understanding on how ecology, evolution processes, and temporal and spatial fragmentation shape fish communities and morphology in two intermittent streams. Furthermore, this research provides a basis for their conservation and management under growing anthropogenic pressures.
Recommended Citation
McCollough, Risa, "Assessment of Fish Community Dynamics, Movement, and Morphology in Relation to Stream Barriers in the Upper Illinois Bayou Watershed" (2025). ATU Theses and Dissertations 2021 - Present. 87.
https://orc.library.atu.edu/etds_2021/87