PhD studentship: Developing novel proxies of historical fishing effort and climate change based on fish-derived carbonates

University of Exeter – College of Life and Environmental Science

Qualification type: PhD
Location: Exeter

Funding for: UK Students, EU Students
Funding amount: £14,296 per annum for 2016-2017

Closes: 6th January 2017
Reference: 2249

This project is one of a number that are in competition for funding from the NERC Great Western Four+ Doctoral Training Partnership (GW4+ DTP).

At least 4 fully-funded studentships that encompass the breadth of earth and environmental sciences are being offered to start in September 2017 at Exeter.

The studentships will provide funding for a stipend which is currently £14,296 per annum for 2016-2017, research costs and UK/EU tuition fees at Research Council UK rates for 42 months (3.5 years) for full-time students, pro rata for part-time students.

Main supervisor: Dr Rod W. Wilson (Biosciences, University of Exeter)

Marine carbonate sediments provide invaluable insights for interpreting changes in ocean chemistry, benthic and pelagic ecology, and climatic change in the past, as well as modelling predictions for the future. Calcium carbonate production is attributed primarily to marine plankton (mainly by coccolithophores and foraminifera). However, marine fish also produce calcium carbonate crystals in their guts which are excreted at very high rates. This process has significant implications for physiological functions in marine fish (including acid-base and ion regulation, respiratory gas exchange). The excreted carbonates have also recently been acknowledged as a major but previously unrecognised component of the global inorganic carbon cycle (Wilson et al., 2009 – Science). In addition, for tropical marine fish we have recently demonstrated that fish represent an entirely new (to science), direct and quantitatively significant source of fine-grained carbonate sediment within shallow tropical marine settings (Perry et al., 2011 – PNAS).

This state of the art PhD project adds a new twist to the use of sedimentary carbonates in environmental science. It aims to characterise how changes in sedimentary carbonates attributable to marine fish may indicate historical trends in fishing pressure, climate change, and extreme events (El Nino cycles, hurricanes etc.) by examining late Holocene cores. The interdisciplinary supervisory team from Exeter, Penryn, Bristol, Cefas and Texas provides excellent expertise in fish physiology, marine carbonate sedimentology, paleoclimate and diagenesis. Furthermore, can already access some of the most relevant core material from the Gulf of Mexico through collaboration with paleoclimate scientists in the USA. These sites are ideal for the following reasons: 1) high sedimentation rates, but low bioturbation to maximise preservation during the latest Holocene; 2) existing chronological timeframe (e.g. radiocarbon, Pb210 dating); 3) good porewater datasets to determine likely diagenetic trends; 4) reliable historical records of fishery activity (~200 years); 5) low latitude so calcium carbonate is close to saturation in surface waters. Comparison with records for Arabian Gulf (offshore Abu Dhabi) with higher bioturbation rates is also available via Bristol and Cefas collaborations.

Analytical techniques will include the use of SEM with EDS microanalytical facilities. Climate change is relevant to this time period and to making future predictions, so we aim to explore the impact of temperature and CO2 on gut carbonate production by fish under controlled lab conditions. This in vivo physiological component will help inform the analysis and interpretation of sediment cores.

See for full details and how to apply.

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