title: The pervasive role of biological cohesion in bedform development.
abstract: Sediment fluxes in aquatic environments are crucially dependent on bedform dynamics. However, sediment-flux predictions rely almost completely on clean-sand studies, despite most environments being composed of mixtures of non-cohesive sands, physically cohesive muds and biologically cohesive extracellular polymeric substances (EPS) generated by microorganisms. EPS associated with surficial biofilms are known to stabilize sediment and increase erosion thresholds. Here we present experimental data showing that the pervasive distribution of low levels of EPS throughout the sediment, rather than the high surficial levels of EPS in biofilms, is the key control on bedform dynamics. The development time for bedforms increases by up to two orders of magnitude for extremely small quantities of pervasively distributed EPS. This effect is far stronger than for physical cohesion, because EPS inhibit sand grains from moving independently. The results highlight that present bedform predictors are overly simplistic, and the associated sediment transport processes require re-assessment for the influence of EPS.
authors: School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey LL59 5AB, UK.
authors: Jonathan
authors: J
authors: Malarkey
authors: School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey LL59 5AB, UK.
authors: Jaco H
authors: JH
authors: Baas
authors: Sediment Ecology Research Group, School of Biology, University of St Andrews, Fife KY16 8LB, UK.
authors: Julie A
authors: JA
authors: Hope
authors: Sediment Ecology Research Group, School of Biology, University of St Andrews, Fife KY16 8LB, UK.
authors: Rebecca J
authors: RJ
authors: Aspden
authors: Department of Geography, Environment and Earth Sciences, University of Hull, Hull HU6 7RX, UK.
authors: Daniel R
authors: DR
authors: Parsons
authors: School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.
authors: Jeff
authors: J
authors: Peakall
authors: Sediment Ecology Research Group, School of Biology, University of St Andrews, Fife KY16 8LB, UK.
authors: David M
authors: DM
authors: Paterson
authors: School of Marine Science and Engineering, Plymouth University, Drake Circus, Plymouth PL4 8AA, UK.
authors: Robert J
authors: RJ
authors: Schindler
authors: Department of Geography, Environment and Earth Sciences, University of Hull, Hull HU6 7RX, UK.
authors: Leiping
authors: L
authors: Ye
authors: 1] School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey LL59 5AB, UK [2] National Oceanography Centre, Joseph Proudman Building, 6 Brownlow Street, Liverpool L3 5DA, UK.
authors: Ian D
authors: ID
authors: Lichtman
authors: School of Marine Science and Engineering, Plymouth University, Drake Circus, Plymouth PL4 8AA, UK.
authors: Sarah J
authors: SJ
authors: Bass
authors: School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey LL59 5AB, UK.
authors: Alan G
authors: AG
authors: Davies
authors: 1] Department of Geography, Environment and Earth Sciences, University of Hull, Hull HU6 7RX, UK [2] School of Marine Science and Engineering, Plymouth University, Drake Circus, Plymouth PL4 8AA, UK [3] HR Wallingford, Wallingford OX10 8BA, UK.
authors: Andrew J
authors: AJ
authors: Manning
authors: National Oceanography Centre, Joseph Proudman Building, 6 Brownlow Street, Liverpool L3 5DA, UK.
authors: Peter D
authors: PD
authors: Thorne
mesh_terms: D001704:Biopolymers / Q000737:chemistry*; D005110:Extracellular Space / Q000737:chemistry; D019015:Geologic Sediments / Q000382:microbiology*; D009038:Motion; D013997:Time Factors
chemical_list: D001704:Biopolymers
references: Microb Ecol. 2009 Aug;58(2):334-49
references: 19242746