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GROUNDWATER INFLUENCES ON THE DISTRIBUTION AND ABUNDANCE OF RIVERINE SMALLMOUTH BASS, MICROPTERUS DOLOMIEU, IN PASTURE LANDSCAPES OF THE MIDWESTERN USA

Authors

  • Shannon K. Brewer

    Corresponding author
    • US Geological Survey, Oklahoma Cooperative Fish and Wildlife Research Unit, Oklahoma State University, Stillwater, Oklahoma, USA
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  • This article is a US Government work and is in the public domain in the USA.

Correspondence to: S. K. Brewer, US Geological Survey, Oklahoma Cooperative Fish and Wildlife Research Unit, Oklahoma State University, 404 Life Sciences West, Stillwater, Oklahoma 74078, USA.

E-mail: shannon.brewer@okstate.edu

ABSTRACT

This study examined how spring-flow (SF) contributions to streams related to the distribution and abundance of smallmouth bass Micropterus dolomieu in a predominately pasture landscape in Missouri, USA. Stream segments (N = 13) with similar landscape characters were classified by SF volume into high SF (HSF) or low SF (LSF) groups. The densities of smallmouth bass, channel unit (CU) use and temperature-selection patterns were assessed for several life stages and frequency distributions for age 0 fish. More smallmouth bass were present in stream segments with HSF influence. Age 0 fish were twice as likely to be present in HSF stream segments. Older age classes were present in stream reaches independent of SF contribution. For all age classes, the use of particular CUs did not depend on SF influence. All age classes were more likely to be present in pools than other CUs. Microhabitat temperature selection differed among age classes. Age 0 fish selected warmer temperatures with a gradual shift towards cooler temperatures for older age classes. The length frequency of age 0 fish was skewed towards larger individuals in streams with limited SF influence, whereas the length frequency in HSF stream segments was skewed towards smaller individuals. The benefits of significant groundwater via SF influence seem to be related to increased hatch or survival of age 0 fish and the availability of optimal temperatures for adult smallmouth bass growth. Thermal refugia and stable flows provided by springs should be recognised for their biological potential to provide suitable habitat as climate change and other land-use alterations increase temperature regimes and alter flow patterns. Published in 2011 by John Wiley & Sons, Ltd.

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