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Impacts of gravel jetting on the composition of fish spawning substrates: Implications for river restoration and fisheries management

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posted on 04.08.2017, 10:04 by Tea Basic, J. Robert Britton, Stephen RiceStephen Rice, Andrew Pledger
Fine sediments can impact river biota, with egg and larval stages of lithophilic fish particularly sensitive to deposition of sand- to clay-sized particles (‘fines’) in spawning gravels. Mitigation and restoration methods include jetting to cleanse gravels of fines. Despite wide application, impacts of jetting on gravel composition and quality have rarely been quantified. Here, gravel jetting impacts on sediment composition in the River Great Ouse (UK), were tested during an in-situ experiment completed at riffle (55.6 ± 13.4 m 2 ) and patch (0.3 m 2 ) scales to determine its magnitude and persistence on surface and subsurface substrate conditions. Before-after (riffle) and control-impact (patch) designs were used, with bedload sediment traps installed downstream of experimental patches to investigate the sediments mobilised during jetting. At the riffle scale, surface grain size was significantly altered; fines were removed resulting in coarser and better-sorted sediments. Similar patterns were detected at the patch scale, although sediment sorting was not significantly altered. Despite reduced fine sediment content of subsurface gravels at the riffle scale, the overall grain size composition was not significantly altered. At the patch scale, no subsurface improvements were detected. Temporally, at the riffle scale, no changes in surface or subsurface sediments lasted more than 12 months; patch scale changes generally persisted for less than 3 months. Thus, whilst gravel jetting could improve spawning gravel quality for surface spawning fishes, including European barbel Barbus barbus, its effects are short-lived. Because subsurface sediments are not affected by gravel jetting, the benefits are limited for redd-building fishes, such as salmonids. Consequently, reducing fine sediment delivery to rivers, such as by changes in agricultural practices, is more sustainable for managing excessive river sedimentation.

Funding

This work was supported by a studentship funded by the Environment Agency and Barbel Society, UK.

History

School

  • Social Sciences

Department

  • Geography and Environment

Published in

Ecological Engineering

Volume

107

Pages

71 - 81

Citation

BASIC, T. ... et al, 2017. Impacts of gravel jetting on the composition of fish spawning substrates: Implications for river restoration and fisheries management. Ecological Engineering, 107, pp. 71-81.

Publisher

© Elsevier

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2017

Notes

This paper was published in the journal Ecological Engineering and the definitive published version is available at http://dx.doi.org/10.1016/j.ecoleng.2017.06.057.

ISSN

0925-8574

Language

en