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Biological cohesion as the architect of bed movement under wave action

Biological cohesion as the architect of bed movement under wave action
Biological cohesion as the architect of bed movement under wave action

Cohesive extracellular polymeric substances (EPS) generated by microorganisms abundant on Earth are regarded as bed “stabilizers” increasing the erosion threshold in sedimentary systems. However, most observations of this phenomenon have been taken under steady flow conditions. In contrast, we present how EPS affect the bed movement under wave action, showing a destabilization of the system. We demonstrate a complex behavior of the biosedimentary deposits, which encompasses liquefaction, mass motion, varying bed formations and erosion, depending on the amount of EPS present. Small quantities of EPS induce higher mobility of the sediments, liquefying an otherwise stable bed. Bed with larger quantities of EPS undergoes a synchronized mechanical oscillation. Our analysis clarifies how biological cohesion can potentially put coastal wetlands at risk by increasing their vulnerability to waves. These findings lead to a revised understanding of the different roles played by microbial life, and their importance as mediators of seabed mobility.

bed stability, biological cohesion, biostabilization, coastal safety, sediment erosion, wave action
0094-8276
Chen, Xindi
79f07552-4abc-407b-805e-0a16ee40a98c
Zhang, Changkuan
dfdb560e-6606-4ba2-86be-f7068ef48393
Townend, Ian
f72e5186-cae8-41fd-8712-d5746f78328e
Paterson, David M.
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Gong, Zheng
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Jiang, Qin
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Feng, Qian
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Yu, Xiping
a139885b-74cc-4427-94f5-fe7248d19b55
Chen, Xindi
79f07552-4abc-407b-805e-0a16ee40a98c
Zhang, Changkuan
dfdb560e-6606-4ba2-86be-f7068ef48393
Townend, Ian
f72e5186-cae8-41fd-8712-d5746f78328e
Paterson, David M.
cb3a1995-cd31-46b5-970c-71d0f571d63b
Gong, Zheng
8fec227f-4dcc-431e-85c3-13a520574886
Jiang, Qin
72a65269-6c74-4bcb-8293-1aa734b58fbb
Feng, Qian
e5bc45a3-f8ed-479f-bd3e-5e10a8bd7bf3
Yu, Xiping
a139885b-74cc-4427-94f5-fe7248d19b55

Chen, Xindi, Zhang, Changkuan, Townend, Ian, Paterson, David M., Gong, Zheng, Jiang, Qin, Feng, Qian and Yu, Xiping (2021) Biological cohesion as the architect of bed movement under wave action. Geophysical Research Letters, 48 (5), [e2020GL092137]. (doi:10.1029/2020GL092137).

Record type: Letter

Abstract

Cohesive extracellular polymeric substances (EPS) generated by microorganisms abundant on Earth are regarded as bed “stabilizers” increasing the erosion threshold in sedimentary systems. However, most observations of this phenomenon have been taken under steady flow conditions. In contrast, we present how EPS affect the bed movement under wave action, showing a destabilization of the system. We demonstrate a complex behavior of the biosedimentary deposits, which encompasses liquefaction, mass motion, varying bed formations and erosion, depending on the amount of EPS present. Small quantities of EPS induce higher mobility of the sediments, liquefying an otherwise stable bed. Bed with larger quantities of EPS undergoes a synchronized mechanical oscillation. Our analysis clarifies how biological cohesion can potentially put coastal wetlands at risk by increasing their vulnerability to waves. These findings lead to a revised understanding of the different roles played by microbial life, and their importance as mediators of seabed mobility.

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2020GL092137 - Version of Record
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Published date: 16 March 2021
Additional Information: Funding Information: Funding for this project was provided by the National Key Research and Development Project, MOST, China (2018YFC0407506), the National Natural Science Foundation of China (51620105005), and the China Postdoctoral Science Foundation (2020M680580). D. M. Paterson acknowledges NERC funding (N E/N016009/1). We appreciate the work of Dr. Naiyu Zhang for the nondestructive three dimensional imaging of the biofilm-sediments. We would like to thank Jun Zhang, Fei Gao, Guangwei Liu and Kaiyue Shan for the fruitful discussions. Our thanks also go to Jia Xu, Shibai Yu and all our laboratory assistants for their help with the flume setup. Publisher Copyright: © 2021. American Geophysical Union. All Rights Reserved.
Keywords: bed stability, biological cohesion, biostabilization, coastal safety, sediment erosion, wave action

Identifiers

Local EPrints ID: 447263
URI: http://eprints.soton.ac.uk/id/eprint/447263
ISSN: 0094-8276
PURE UUID: 6883d2b0-7097-44a5-9088-93c19b3c960b
ORCID for Ian Townend: ORCID iD orcid.org/0000-0003-2101-3858

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Date deposited: 05 Mar 2021 17:34
Last modified: 17 Mar 2024 06:22

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Contributors

Author: Xindi Chen
Author: Changkuan Zhang
Author: Ian Townend ORCID iD
Author: David M. Paterson
Author: Zheng Gong
Author: Qin Jiang
Author: Qian Feng
Author: Xiping Yu

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