Muddy intertidal sediments are intimately associated with animals and plants and are therefore biologically-mediated systems. This is a "two way street": the biota strongly influence the properties of and processes in the sediment; but changes to, or loss of sediments have important consequences for the associated fauna. Research tends to be polarised into biological or physical aspects, with only slow integration of findings from one to the other. This project draws these disciplines together in a multidisciplinary approach to improve our understanding of physical sedimentary processes such as erosion and deposition.

Erosion threshold responds to temporal and spatial variability in biota and the properties of sediment, often in an apparently idiosyncratic fashion. There is increasing recognition that this is caused by a complex interaction of direct and indirect processes, for example, biofilms can directly increase sediment stability via its effects on the inter-particle bonding of clay particles, and also indirectly mediate sediment stability by supporting faunal populations. Fauna often have antagonistic effects, both stabilising and destabilising sediment.Numerous other factors, such as weather, tides, salinity and water content affect the biotic/abiotic interaction. This project will experimentally manipulate selected biota, properties of sediment and environmental conditions in the field, to tease apart their contributions to sediment dynamics, such as erosion processes. This will improve our understanding of the biological/physical interactions that drive these processes.

Teasing apart such complex interactions is essential to advancing our knowledge of how biotic and abiotic components mediate sedimentary processes in coastal habitats and for understanding how intertidal habitats will respond in the future, for example due to climate change and resulting changes in weather patterns.

To date, most studies on the erosion of intertidal sediments have focussed on unidirectional or oscillatory flows in isolation. Recent advances in equipment made at UEA have resulted in the development of FloWave, a device that simulates combined unidirectional and oscillatory flows. This project will continue to calibrate and develop the FloWave device and will, for the first time, use it to investigate the abiotic and biotic properties and processes that mediate erosion by combined flows in the laboratory and field.

Work will be done in challenging muddy coastal environments, so the applicant should be able to demonstrate excellent field skills.

The student will join a growing group of sedimentary researchers in UEA and there will be opportunities for collaborative work with other UK research groups and possibly also overseas groups. The student will take part in the formal skills training offered to all PhD students in Environmental Sciences and in addition will be trained in experimental sedimentology/ecology and field observation as appropriate.
 

Black, K.S., Tolhurst, T.J., Hagerthey, S.E., and Paterson, D.M., (2002) Working with Natural Cohesive Sediments. Journal of Hydraulic Engineering, January, Vol. 128 (1), 2-8.

Tolhurst, T. J., Black, K. S., and Paterson, D. M. (2009) Muddy Sediment Erosion: Insights from Field Studies, Journal of Hydraulic Engineering-Asce, 135, 73-87