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Download fileSignal crayfish burrowing, bank retreat and sediment supply to rivers: a biophysical sediment budget
journal contribution
posted on 2021-02-08, 14:04 authored by Harry Sanders, Stephen RiceStephen Rice, Paul WoodPaul WoodBurrowing into riverbanks by animals transfers sediment directly into river channels
and has been hypothesised to accelerate bank erosion and promote mass failure. A
field monitoring study on two UK rivers invaded by signal crayfish (Pacifastacus
leniusculus) assessed the impact of burrowing on bank erosion processes. Erosion
pins were installed in 17 riverbanks across a gradient of crayfish burrow densities and
monitored for 22-months. Bank retreat increased significantly with crayfish burrow
density. At the bank scale (<6 m river length), high crayfish burrow densities were
associated with accelerated bank retreat of up to 253% and more than a doubling of
the area of bank collapse, compared to banks without burrows. Direct sediment supply
by burrowing activity contributed 0.2% and 0.6% of total sediment at the reach (1.1
km) and local bank (<6 m) scales. However, accelerated bank retreat caused by
burrows contributed 12.2% and 29.8% of the total sediment supply at the reach and
bank scales. Together, burrowing and the associated acceleration of retreat and
collapse supplied an additional 25.4 t km-1 a
-1 of floodplain sediments at one site,
demonstrating the substantial impact that signal crayfish can have on fine sediment
supply. For the first time, an empirical relation linking animal burrow characteristics to
riverbank retreat is presented. The study adds to a small number of sediment budget
studies that compare sediment fluxes driven by biotic and abiotic energy but is unique
in isolating and measuring the substantial interactive effect of the acceleration of
abiotic bank erosion facilitated by biotic activity. Biotic energy expended through
burrowing represents an energy surcharge to the river system that can augment
sediment erosion by geophysical mechanisms
History
School
- Social Sciences and Humanities
Department
- Geography and Environment
Published in
Earth Surface Processes and LandformsVolume
46Issue
4Pages
837 - 852Publisher
WileyVersion
- VoR (Version of Record)
Rights holder
© The authorsPublisher statement
This is an Open Access Article. It is published by wiley under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/Acceptance date
2021-01-06Publication date
2021-02-05Copyright date
2021ISSN
0197-9337eISSN
1096-9837Publisher version
Language
- en