Quantifying biostabilisation effects of biofilm-secreted and extracted extracellular polymeric substances (EPSs) on sandy substrate

Van De Lageweg, Wietse I.; McLelland, Stuart J.; Parsons, Daniel R.

Abstract

© Author(s) 2018. Microbial assemblages ( < q > biofilms < /q > ) preferentially develop at water-sediment interfaces and are known to have a considerable influence on sediment stability and erodibility. There is potential for significant impacts on sediment transport and morphodynamics, and hence on the longer-term evolution of coastal and fluvial environments. However, the biostabilisation effects remain poorly understood and quantified due to the inherent complexity of biofilms and the large spatial and temporal (i.e. seasonality) variations involved. Here, we use controlled laboratory tests to systematically quantify the effects of natural biofilm colonisation as well as extracted extracellular polymeric substances (EPSs) on sediment stability. Extracted EPSs may be useful to simulate biofilm-mediated biostabilisation and potentially provide a method of speeding up timescales of physical modelling experiments investigating biostabilisation effects. We find a mean biostabilisation effect due to natural biofilm colonisation and development of almost 4 times that of the uncolonised sand. The presented cumulative probability distribution of measured critical threshold for erosion of colonised sand reflects the large spatial and temporal variations generally seen in natural biostabilised environments. For identical sand, engineered sediment stability from the addition of extracted EPSs compares well across the measured range of the critical threshold for erosion and behaves in a linear and predictable fashion. Yet, the effectiveness of extracted EPSs to stabilise sediment is sensitive to the preparation procedure, time after application and environmental conditions such as salinity, pH and temperature. These findings are expected to improve biophysical experimental models in fluvial and coastal environments and provide much-needed quantification of biostabilisation to improve predictions of sediment dynamics in aquatic ecosystems.

Citation

Van De Lageweg, W. I., McLelland, S. J., & Parsons, D. R. (2018). Quantifying biostabilisation effects of biofilm-secreted and extracted extracellular polymeric substances (EPSs) on sandy substrate. Earth surface dynamics ESURF ; an interactive open access journal of the European Geosciences Union, 6(1), 203-215. https://doi.org/10.5194/esurf-6-203-2018

• Journal Article Type: Article
• Acceptance Date: Feb 18, 2018
• Online Publication Date: Mar 16, 2018
• Publication Date: Mar 16, 2018
• Deposit Date: Aug 26, 2018
• Publicly Available Date: Aug 28, 2018
• Journal: Earth Surface Dynamics
• Print ISSN: 2196-632X
• Publisher: European Geosciences Union
• Peer Reviewed: Peer Reviewed
• Volume: 6
• Issue: 1
• Pages: 203-215
• DOI: https://doi.org/10.5194/esurf-6-203-2018
• Keywords: Earth-Surface Processes; Geophysics
• Public URL: https://hull-repository.worktribe.com/output/755332
• Publisher URL: https://www.earth-surf-dynam.net/6/203/2018/
• Contract Date: Aug 28, 2018