Clayton Ridenour (MS) crkb3@mizzou.edu

Use and Dynamics of Shallow Waters of Lower Missouri River Sandbars by Small-bodied Fishes

Advisor: Dr. David Galat

Prior to channel modification the Missouri River was characterized by a dynamic free-ranging, braided channel network with shifting sandbars and abundant shallow-water habitat. Channelization and flow manipulation now contribute to reduced availability of low velocity, shallow-water areas for small and juvenile fishes in the lower Missouri River. Existing and newly constructed sandbars along the navigation channel today represent an opportunity to provide shallow-water refugia and nursery for imperiled fishes. Our goal is to characterize the small-bodied fish community in shallow-waters adjacent to existing inside-bend and wingdike sandbars, and relate differences in species composition and abundance to selected physical habitat variables. Habitat use is studied within a nested hierarchical framework to provide more accurate assessment of the spatial scale most relevant to small-bodied lower Missouri River fishes. Fishes are collected with prepositioned areal electrofishing devices (PAEDs) in shallow-water (≤0.5m) around sandbars and microhabitat variables measured for the defined sample area. Microhabitat variables include: water temperature, depth, turbidity, and velocity, sandbar slope and shoreline sinuosity, and substrate composition. Determining what habitat characteristics of sandbars are most beneficial to fishes will allow us to make recommendations for the design of new sandbars and management of existing sandbars to maximize the ecological value from shallow-water habitat creation and rehabilitation efforts.