Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

Spring 2018

Thesis Director

Robert E. Colombo

Thesis Committee Member

Anabela Maia

Thesis Committee Member

Eric K. Bollinger


Wastewater treatment effluent, agricultural runoff, and impoundments can alter the water quality and flow regime of rivers. Fishes around the world are increasingly exposed to estrogenic compounds due to the discharge of wastewater into rivers. Estrogenic compounds, such as those found in birth control pills and soybean byproducts, are endocrine disruptors in vertebrates. The Sanitary District of Decatur serves the municipal and industrial entities of Macon County, IL, and discharges its effluent into the Sangamon River, which includes byproducts of industrial soybean processing. I assessed impacts of treated wastewater on the health of fishes in the Sangamon River. Abnormal caudal fins have been observed in several Catostomid species in the study reach of the Sangamon River. I assessed sex ratios, plasma vitellogenin concentrations, and the occurrence of gonadal intersex in three Catostomid species (River Carpsucker Carpiodes carpio, Smallmouth Buffalo Ictiobus bubalus, and Shorthead Redhorse Moxostoma macrolepidotum). I also assessed condition and morphometrics of these species to determine if relative weight is affected by fin morphology. Data were collected in spring of 2016 in the Sangamon and Embarras Rivers. All sexually mature fishes were sexed and blood was drawn from all adults identified as male and analyzed with ELISA test kits to determine vitellogenin concentrations. Fish testes were dissected, weighed, preserved for histology, and analyzed for the presence of testicular oocytes. No testicular oocytes were found in any of the species. Shorthead Redhorse from the Embarras River had a higher gonadosomatic index compared to fish from the Sangamon River, but no differences were found for River Carpsucker and Smallmouth Buffalo. Due to vitellogenin detection in a high percentage of males, populations were intersexed and female biased in both rivers for all species. Using traditional and geometric morphometrics, I used standard and total lengths to determine if River Carpsucker and Smallmouth Buffalo from the Sangamon River have significantly longer total lengths compared to standard lengths. River Carpsucker and Smallmouth Buffalo have longer caudal fins in the Sangamon River than the Embarras River. Longer caudal fins cause lower relative weight due to relative weight calculation incorporating total length. Geometric morphometrics revealed Sangamon River River Carpsucker and Smallmouth Buffalo have significantly different body shapes due to fin morphology than fishes in the Embarras River. The occurrence of feminization in both rivers, as well as the difference in body shapes between rivers, demonstrates these populations, especially in the Sangamon River, may be at risk for deterioration of health and further reproductive disruption due to contaminant exposure.