Date of this Version
Magruder, Mitchell, "Sturgeon Chub Distributional Patterns and Habitat Use and Benthic Fish Assemblage Structure in Missouri River Tributaries of South Dakota" (2022). Dissertations & Theses in Natural Resources,University of Nebraska-Lincoln.
Native species of the Missouri River drainage inhabiting benthic habitats dominate state and federal lists of species at risk. Sicklefin Chub Macrhybopsis meeki and Sturgeon Chub Macrhybopsis gelida are two native Missouri River benthic minnows that are currently under review for federal listing under the Endangered Species Act (ESA) due to extensive population declines and local extirpations within their native range. Substantial alterations to the Missouri River threaten Macrhybopsis spp. and other benthic fishes; however, large, less impacted tributaries in South Dakota may act as refugia for native species. The extent of Sicklefin Chub and Sturgeon Chub populations is largely unknown in the state and recent assessments documenting Missouri River benthic fish assemblages are lacking. The goal of this project was to update the distribution and abundance of benthic fishes of the Missouri River and its major tributaries with an emphasis on Sicklefin Chub and Sturgeon Chub in South Dakota. Our objectives were to: 1) evaluate abiotic and biotic influences on distributional patterns of Sicklefin Chub and Sturgeon Chub and characterize their habitat use, and 2) describe and compare patterns of benthic fish assemblage structure within rivers and for the region. Information presented herein pertains to the tributaries, due to zero catch of Macrhybopsis spp. in the mainstem Missouri River. Sturgeon Chub were captured in the Cheyenne, White, and Little White rivers but were absent from the Little Missouri and Grand rivers. Relative abundances of both age-0 and age-1+ Sturgeon Chub were highest in the White River. Distributions of Sturgeon Chubs were limited to lower areas of all rivers where stream width, turbidity, discharge, and observed habitat complexity were highest and Flathead Chub Platygobio gracilis and Hybognathus spp. (Plains Minnow H. placitus and Western Silvery Minnow H. argyritis) were more abundant. Sturgeon Chub primarily used main or secondary flowing channels and were predominantly found in or near the thalweg. Velocity, depth, and percent gravel predicted Sturgeon Chub presence on smaller scales. Predominantly native fish assemblages were observed in all rivers. Total species richness was lowest in the White River, where extreme environmental conditions likely limit species diversity and nonnative species establishment. Longitudinal patterns of assemblage structure were observed in the White, Cheyenne, and Little White rivers due to natural and anthropogenic changes in habitat conditions. Species additions occurred as rivers gradually increased in size and habitat complexity, but native species were replaced in response to abrupt habitat changes, such as those created by impoundments. High abundances of native, benthic fishes in Missouri River tributaries of South Dakota that are experiencing overall population declines highlights the importance of large, relatively unaltered tributaries to the conservation of freshwater biodiversity in North America.
Advisor: Mark A. Pegg