Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

Summer 2026

Thesis Director

Robert E. Colombo

Thesis Committee Member

Eden L. Effert-Fanta

Thesis Committee Member

Scott J. Meiners

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Abstract

There is concern about declining biodiversity in the world today and an increasing need to monitor biodiversity through collecting data and gauging changes occurring in biodiversity over time. Large river fish communities are one area of particular interest due to their sensitivity to environmental changes. One program seeking to address this is the Long-Term Survey and Assessment of Large River Fishes, LTEF, which monitors fish populations in the large rivers of Illinois. In this study, I assessed changes in the fish community of the lower 322 km of the Wabash River from 2010-2025 using annual direct current boat electrofishing surveys from June 15th to October 31st. I identified and measured all fishes to their total length (mm) and weight (g). Functional changes in the fish community were described by functional guilds that were defined using the USGS Fish Traits Database. I found a significant decline in the relative abundance of the Wabash River fish community from 2010 to 2025. Declines were found in multiple functional guilds, with significant trends found in the benthic invertivore, omnivore, and planktivore trophic guilds; the benthic spawner, cavity nester, nest builder, and pelagophile reproductive guilds; and the fast generalist and pool cover habitat guilds. There were fourteen species found to show declines in abundance that were highly responsive to the compositional changes occurring in the fish community, including species such as the Channel Catfish (Ictalurus punctatus), Common Carp (Cyprinus carpio), Freshwater Drum (Aplodinotus grunniens), Gizzard Shad (Dorosoma cepedianum), Largemouth Bass (Micropterus nigricans), and White Bass (Morone chrysops).The only species I found with a highly responsive increase in abundance was the Longnose Gar (Lepisosteus osseus). Although the highly responsive decline of fourteen species was concerning, I found most of the species to have good to excellent body condition according to their relative weights and most showed no significant change in relative weight over time. These findings emphasize the sensitivity of large river fish communities by showing how the Wabash River fish community has experienced a compositional shift in response to invasive species, increased anthropogenic presence, and intensive agriculture, and they stress the importance of long-term monitoring in these systems.

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