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Effects of hydropeaking on drift, stranding and community composition of macroinvertebrates: a field experimental approach in three regulated Swiss rivers
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  • Diego Tonolla,
  • Florian Dossi,
  • Olivier Kastenhofer,
  • Michael Doering,
  • Christoph Hauer,
  • Wolfram Graf,
  • Lisa Schülting
Diego Tonolla
Zurcher Hochschule fur Angewandte Wissenschaften

Corresponding Author:diego.tonolla@zhaw.ch

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Florian Dossi
Universitat fur Bodenkultur Wien
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Olivier Kastenhofer
Zurcher Hochschule fur Angewandte Wissenschaften
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Michael Doering
Zurcher Hochschule fur Angewandte Wissenschaften
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Christoph Hauer
Universitat fur Bodenkultur Wien
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Wolfram Graf
Universitat fur Bodenkultur Wien
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Lisa Schülting
Universitat fur Bodenkultur Wien
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Abstract

Hydropeaking operation leads to fluctuations in wetted area between base and peak flow and increases discharge-related hydraulic forces (e.g., flow velocity). These processes promote macroinvertebrate drift and stranding, often affecting benthic abundance and biomass. Our field experimental study – conducted in three hydropeaking-regulated Swiss rivers – aimed to quantify (i) the short-term effects of the combined increase in flow amplitude and up-ramping rate based on macroinvertebrate drift and stranding, as well as (ii) long-term effects based on the established community composition. Hydropeaking led to increased macroinvertebrate drift compared to base flow and to unaffected residual flow reaches. Moreover, stranding of macroinvertebrates was positively related to drift, especially during the up-ramping phase. Flow velocity and up-ramping rate were identified as major determinants for macroinvertebrate drift, while flow ratio and down-ramping rate for stranding. Particularly high sensitivity towards HP was found for Limnephilidae, whereas Heptageniidae seemed to be resistant in respect to short and long-term hydropeaking effects. In the long-term, hydropeaking did not considerably reduce benthic density of most taxa, especially of some highly resistant and resilient taxa such as Chironomidae and Baetidae, which dominated the community composition even though they showed comparably high drift and stranding responses. Therefore, we argue that high passive drift and/or stranding, especially of individual-rich taxa, does not necessarily indicate strong hydropeaking sensitivity. Finally, our results demonstrate the necessity to consider the differences in river-specific morphological complexity and hydropeaking intensity, since these factors strongly influence the community composition and short-term drift and stranding response of macroinvertebrates to hydropower pressure.
02 Dec 2021Submitted to River Research and Applications
05 Dec 2021Submission Checks Completed
05 Dec 2021Assigned to Editor
06 Dec 2021Review(s) Completed, Editorial Evaluation Pending
08 Dec 2021Reviewer(s) Assigned
26 Jan 2022Editorial Decision: Revise Major
06 Apr 20221st Revision Received
21 Apr 2022Submission Checks Completed
21 Apr 2022Assigned to Editor
21 Apr 2022Review(s) Completed, Editorial Evaluation Pending
21 Apr 2022Reviewer(s) Assigned
31 May 2022Editorial Decision: Revise Minor
01 Jun 20222nd Revision Received
02 Jun 2022Submission Checks Completed
02 Jun 2022Assigned to Editor
02 Jun 2022Review(s) Completed, Editorial Evaluation Pending
02 Jun 2022Reviewer(s) Assigned
02 Jun 2022Editorial Decision: Accept
21 Jun 2022Published in River Research and Applications. 10.1002/rra.4019