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LOW-HEAD DAM REMOVAL INCREASES FUNCTIONAL DIVERSITY OF STREAM FISH ASSEMBLAGES
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  • Adam Jones,
  • Scott Meiners,
  • EFFERT-FANTA EDEN,
  • Trent Thomas,
  • C.F. SHANNON SMITH,
  • Robert Colombo
Adam Jones
US Geological Survey Columbia Environmental Research Center

Corresponding Author:ajones1847@gmail.com

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Scott Meiners
Eastern Illinois University Department of Biological Sciences
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EFFERT-FANTA EDEN
Eastern Illinois University Department of Biological Sciences
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Trent Thomas
Illinois Department of Natural Resources
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C.F. SHANNON SMITH
William & Mary Virginia Institute of Marine Science
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Robert Colombo
Eastern Illinois University Department of Biological Sciences
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Abstract

Despite the growing number of dam removals, very few have been studied to understand their impacts on stream fish communities. An even smaller proportion of dam removal studies focus on the impacts of low-head dam removals, although they are the most common type of dam. Instead, the majority of removal studies focus on the impacts of larger dams. In this study, two previously impounded Illinois rivers were monitored to assess the impacts of low-head dam removal on the functional assemblage of stream fishes. Study sites were sampled each fall from 2012-2015 (pre-dam removal) and 2018-2020 (post-dam removal) in three habitat types: downstream of the dam, impounded areas, and runs of rivers. Fishes were aggregated into habitat and reproductive guilds, relating community changes to habitat, environmental metrics, and stream quality. Prior to removal, the slackwater guild was the most prevalent habitat guild throughout both rivers, while nest builders and benthic spawners were the most abundant reproductive guilds. During the two years following removal, habitat conditions and fish assemblages improved throughout both rivers, with improvements in QHEI, IBI, water temperature, and dissolved oxygen, as well as a shift to more evenly distributed representation of habitat and reproductive guilds. The improvements in environmental metrics and overall stream quality, particularly in the formerly impounded habitats, indicate diminished habitat homogeneity, and a shift towards natural habitat diversity. This habitat diversification likely led to the restoration of a range of potential niches, thereby increasing the array of guild types inhabiting these rivers, while simultaneously preventing single-guild dominance.
14 Jul 2022Submitted to River Research and Applications
14 Jul 2022Submission Checks Completed
14 Jul 2022Assigned to Editor
15 Jul 2022Review(s) Completed, Editorial Evaluation Pending
15 Jul 2022Reviewer(s) Assigned
16 Aug 2022Editorial Decision: Revise Minor
16 Sep 20221st Revision Received
16 Sep 2022Submission Checks Completed
16 Sep 2022Assigned to Editor
16 Sep 2022Review(s) Completed, Editorial Evaluation Pending
16 Sep 2022Editorial Decision: Accept
Jan 2023Published in River Research and Applications volume 39 issue 1 on pages 3-20. 10.1002/rra.4063