Project title: Biological Enhancement of Estuarine Sediment Stability through Microbial Activity
Bed stability in estuarine hydrological systems is altered by the existence and activity of microorganisms such as microalgae (principally diatoms) and bacteria. Biological production of extracellular polymers results in a sediment matrix in which sediment particles are bound, elevating the critical erosion threshold, a process known as bio-stabilisation. The combination of this binding process together with the flow characteristics and river/estuarine morphology will control bed erosion and sediment mobility in estuaries.
This project will comprise laboratory and field investigations into the enhancement of sediment stability by microbial growth, in particular to understand how the presence of microbial exudates and subsequent biostabilisation affects the dynamics of sediment mobility, and in particular the threshold of motion of bed sediment. The field study site will be the Newport Wetland intertidal mudflats on the Welsh side of the Severn Estuary, where significant intertidal benthic microalgae are present. Current understanding of the threshold of motion has been developed from experimental studies using clean, non-cohesive sediments where the bed mobility is considered only in terms of the physical interaction between the flow properties and the bed particles. Important objectives include the determination of properties of sediment/microbial aggregates and the impact of spatially heterogeneous biostabilisation on flow processes and subsequent patterns of bed erosion. The project will investigate ex situ the biological processes and magnitude of stabilisation as well as use in situ measurements to determine the magnitude of this ecosystem service at the Newport wetlands intertidal, where currently extensive saltmarsh and mudflat erosion is occurring.
Start date: 1st October 2015 (flexible)
Number of Studentships: 1