A PhD project focusing on tidal resuspension in shelf seas is offered under the supervision of Dr Laurent Amoudry (NOC), Prof. Alex Souza (NOC) and Prof. Andrew Plater (University of Liverpool). The deadline for applications is 09.00am 6th February 2015.
Our studentships are funded by NERC and are available to UK nationals and other EU nationals that have resided in the UK for three years prior to commencing the studentship. If you meet this criteria, funding will be provided for tuition fees and stipend. If you are a citizen of a EU member state you will eligible for a fees-only award.
Continental shelf sediments are responsible for the majority of benthic biogeochemical cycling of organic matter even though they constitute less than 9% of the global seafloor. In the energetic environments that are shelf seas, frequent resuspension and reworking of sediments are caused by natural events (such as tidal currents, waves, winds, storms, and biological activity) and by anthropogenic perturbations (e.g., trawling, dredging, etc). However, traditional techniques used to measure the exchange of nutrients and other bioactive solutes between benthic and pelagic zones only produce passive fluxes due to processes such as molecular diffusion. More complex processes, such as sediment resuspension and water advection, are often overlooked and are still poorly understood due to a lack of observational data. Quantifying the role of resuspension is thus crucial for assessing how shelf sea ecosystems function and predicting how they are likely to respond to future changes in climate and human use of marine ecosystems.
The project will focus on the combined physical and sedimentological controls on near-bed vertical fluxes of suspended particulate matter (SPM). In particular, we will address how sea bed properties (e.g. bed morphology, grain size, sediment composition, consolidation) control near-bed fluxes of SPM and how this relates to key near-bed biogeochemical indicators.
The project will use in situ measurements from a benthic lander deployed over a range of sediment types from cohesive to permeable in the Celtic Sea. Each deployment will last for at least two tidal cycles at each site and will be conducted during a series of cruises covering different seasons and years (March 2014, March 2015, May, 2015, August 2015).
The lander is equipped with a suite of state-of-the-art instruments, which will provide a unique and comprehensive series of data sets focusing on the benthic boundary layer in shelf seas. Near-bed hydrodynamics and turbulence will be measured from several acoustic profilers (ADCP, Nortek AquaDopp HR) and velocimetres (ADV). Near-bed SPM resuspension characteristics will be derived from ABS (Acoustic Backscatter System), LISST (Laser In Situ Scattering and Transmissometry), and LISST-Holo (Holographic Particle Imaging System). Bed properties will be measured via cores, sampling, and acoustic techniques, such as the 3D acoustic ripple profiler, which measures small-scale sea bed topography. A range of other key bio-geo-physical parameters will also be recorded (temperature, salinity, O2, nitrate).
This project will operate in close collaboration with the NERC Research Programme on Shelf Sea Biogeochemistry (www.uk-ssb.org
) as the research cruises are part of the programme. The focus on tidal resuspension will address a key link between pelagic and benthic components of the whole system, which is a critical knowledge gap in term of shelf seas biogeochemical modelling.
Formulation of key research questions based on critical review of literature, state-of-the-art knowledge, and available observational and modelling methods.
„h Research training: in particular, familiarisation with in-situ acoustic and optical observational techniques, as well as approaches for sea bed investigation.
Data analysis: processing of data from acoustic velocity profiler, 3D ripple profiler data, LISST and ABS. Gathering of other relevant biogeochemical data via collaboration within NOC-L and the SSB programme.
Data interpretation: correlate physical processes to sedimentological and biogeochemical variability towards assessing the impact of sea bed properties on near-bed fluxes.
Outputs and dissemination: presentations at national and international conferences, writing reports and papers, PhD thesis.
In addition to the DTP training, the student will receive training in processing data from a range of instruments used in near-bed oceanographic measurements, as well as in mathematical and physical analytical techniques.
Applicants must have, or be about to obtain, a first class or upper second degree. If you have a lower second degree, but have also obtained a masters qualification, you are also eligible. If you do not have these qualifications but you have substantial relevant post-graduate experience please contact the School holding the studentship to find out if your relevant experience is sufficient.
Other PhD studentships are being offered by the NOC and the University of Liverpool in coastal and shelf seas science as part of the Manchester and Liverpool Doctoral Training Programme https://www.liv.ac.uk/studentships-earth-atmosphere-ocean/.