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Rice etal Crayfish Bioturb JGR 2016.pdf (2.04 MB)

The importance of biotic entrainment for base flow fluvial sediment transport

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journal contribution
posted on 2016-04-22, 10:23 authored by Stephen Rice, Matthew F. Johnson, Kate Mathers, Jake Reeds, Chris A. Extence
Sediment transport is regarded as an abiotic process driven by geophysical energy, but zoogeomorphological activity indicates that biological energy can also fuel sediment movements. It is therefore prudent to measure the contribution that biota make to sediment transport, but comparisons of abiotic and biotic sediment flux are rare. For a stream in the UK, the contribution of crayfish bioturbation to suspended sediment flux was compared with the amount of sediment moved by hydraulic forcing. During baseflow periods, biotic fluxes can be isolated because nocturnal crayfish activity drives diel turbidity cycles, such that night-time increases above day-time lows are attributable to sediment suspension by crayfish. On average, crayfish bioturbation contributed at least 36% (430 kg) to monthly baseflow suspended sediment loads; this biotic surcharge added between 4.7 and 13.54 t (0.19 to 0.55 t km-2 yr-1) to the annual sediment yield. As anticipated, most sediment was moved by hydraulic forcing during floods and the biotic contribution from baseflow periods represented between 0.43 and 1.24% of the annual load, but this may be a conservative estimate because of unusually prolonged flooding during the measurement period. In addition, we measured direct entrainment of sediment by crayfish, not their potentially greater role in making mobile sediment available to floods via burrowing. These results suggest that in rivers, during baseflow periods, bioturbation can entrain significant quantities of fine sediment into suspension with implications for the aquatic ecosystem and baseflow sediment fluxes. Energy from life rather than from elevation can make significant contributions to sediment fluxes.

History

Department

  • Geography and Environment

Published in

Journal of Geophysical Research - Earth Surface

Volume

121

Issue

5

Pages

890-906

Citation

RICE, S. ... et al., 2016. The importance of biotic entrainment for base flow fluvial sediment transport. Journal of Geophysical Research: Earth Surface, 121, pp. 890–906.

Publisher

© American Geophysical Union

Version

  • VoR (Version of Record)

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/

Acceptance date

2016-03-26

Publication date

2016-05-07

Copyright date

2016

Notes

An edited version of this paper was published by AGU. Copyright (2016) American Geophysical Union.

ISSN

2169-9011

Language

  • en

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