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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)


Natural Resource Management

First Advisor

Brlan D. S. Graeb


Ecological effects of an historic flood in the Missouri River in 2011 are largely unknown. In rapid response, we assessed walleye Sander vitreus environmental history in Missouri River reservoirs using otolith microchemistry and evaluated flood effects on the Lewis & Clark Delta fish community and aquatic habitats. Geologic heterogeneity drove spatial variability in water chemistry throughout impoundments. Otolith trace element concentrations of age-0 and adult walleyes varied spatially in accordance with water chemistry. Bivariate natal signatures of adults exhibited site-specific heterogeneity sufficient to accurately identify natal tributaries and mainstem/embayment sites. The Moreau and Cannonball rivers were particularly important natal sites in Lake Oahe, as were North Shore, West Bend, Platte Creek, and the Lewis & Clark Delta in southern reservoirs. Walleye movement within and among Missouri River reservoirs was dominated by downstream passage and site residency before, during, and after the flood; upstream movement was relatively uncommon. Entrainment was most extensive during the flood and increased progressively moving downstream. Otolith microchemistry indicates divergent entrainment among hydrologic regimes, connectivity of walleye populations among impoundments, and the importance of collaborative riverscape management across state boundaries for walleye management in Missouri River reservoirs. Fish community evenness (J’) in the Lewis and Clark Delta decreased from 0.882 to 0.725 before the flood but rose to 0.835 after the disturbance. Pre-flood species richness declined from 25 to 15, whereas post-flood richness stabilized above 20. Diversity (Fisher’s α) decreased from 4.56 to 3.48 before the flood and stabilized at 3.27 after the disturbance. A majority of species were more abundant after the flood, whereas juvenile freshwater drum Aplodinotus grunniens and white crappie Pomoxis annularis were less abundant and small-bodied native species remained stable. Channel and backwater frequency and main channel width in the Delta declined after the flood, whereas sandbars became more abundant. Habitat changes likely had minimal effects on the fish community due to persistence of shallow-water habitats important for spawning and rearing. Our results suggest the Delta serves as a refuge environment for juvenile and adult fishes during and immediately after catastrophic flooding.

Library of Congress Subject Headings

Reservoir ecology -- Missouri Rive
Floods -- Missouri River
Walleye (Fish) Effect of floods on Missouri River
Aquatic habitats -- Missouri River
Fish communities -- Missouri River


Includes bibliographical references



Number of Pages



South Dakota State University


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