Fish Habitat Associates in a Midwestern Prairie Stream; Evidence of Habitat Partitioning

	Texas Chapter of the American Fisheries Society

From the 2000 Joint Meeting of the Arkansas, Louisiana, and Texas Chapters of the American Fisheries Society held in Bossier City, Louisiana.

Fish Habitat Associates in a Midwestern Prairie Stream; Evidence of Habitat Partitioning
Bonner, T. H. and G. R. Wilde, Department of Range, Wildlife, and Fisheries Management, Texas Tech University, Lubbock,
Texas 79409, (806) 742-2841

General patterns in fish-habitat associations were found for the historically dominant minnows of the Canadian River, Texas and New Mexico. Upper reaches of prairie streams typically are characterized as unstable aquatic environments with large daily and seasonal variations in temperatures, flows, conductivity, and turbidity. Previous studies and ecological theory
suggest that in highly variable environments, abiotic factors play a greater role in species persistence and habitat selection than biotic factors; habitat selections are transitory, no single variable is important in habitat selection, and no stable patterns existed in habitat partitioning among species. However, we found stable patterns in habitat selection and partitioning along depth and current velocity gradients. Arkansas River shiners Notropis girardi and speckled chubs Macrhybopsis aestivalis
typically inhabited shallow depths, with the speckled chub selecting significantly swifter currents (P < 0.05) during the winter, spring, and summer. Plains minnows Hybognathus placitus and flathead chubs Platygobio gracilis typically inhabited significantly greater depths (P < 0.05), with the flathead chub selecting significantly swifter currents (P < 0.05) during the spring and summer. These distributional patterns were consistent with species morphology and feeding preferences, thus suggesting strong biotic influences on assemblage structure. Other abiotic factors such as temperature, conductivity, turbidity, and substrate were significantly correlated (P < 0.05) with flow (depth or current velocity), confounding the interpretation of preference or avoidance for a particular habitat variable. However, it is doubtful that any observed physical
or chemical parameter exceeded the physiological tolerances of these species. Understanding underlying structuring mechanisms of fish assemblages is critical to future conservation and restoration projects currently underway in prairie streams throughout the Midwest.

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