Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

Summer 2022

Thesis Director

Eden L. Effert-Fanta

Thesis Committee Member

Joseph J. Parkos III

Thesis Committee Member

Robert E. Colombo

Abstract

Understanding environmental conditions that support bigheaded carp (Hypophthalmichthys sp.) reproduction in tributary rivers provides key predictions of their invasion throughout the United States. Past research, primarily in larger order rivers, identified factors such as discharge, temperature, and turbidity as main environmental drivers of bigheaded carp reproduction. I used the variable hydrologic conditions between the Illinois and Wabash Rivers to compare environmental conditions between tributaries of each basin, determine which conditions influence bigheaded carp reproduction in tributaries, and predict tributaries likely to support bigheaded carp reproduction. Three tributaries of the Illinois and Wabash Rivers were sampled for ichthyoplankton from March-September 2016-2020. I compared tributary conditions, such as discharge, water temperature, chlorophyll a, and total phosphorus between each basins. Between basins, I found Wabash tributaries had higher discharge, whereas Illinois tributaries had higher dissolved oxygen. The Sangamon and Little Wabash had the highest peak larval densities, with highest overall peak densities in the Illinois River basin. Bigheaded carp reproduction in Wabash tributaries was positively influenced by discharge, whereas reproduction in Illinois River tributaries was positively related to temperature and discharge. Additionally, I found that tributaries can support similar reproduction to mainstem rivers likely due to increased hydrologic variation. I used drainage area to predict tributaries susceptible to bigheaded carp reproduction, such as the Grand and St. Joseph Rivers, in the Lake Michigan basin. Expanded monitoring of these tributaries is needed as they can serve as sources of recruitment to basin-wide bigheaded carp populations and their size is comparable to Great Lakes tributaries.

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