PhD (Funded) - Using Integrative Physiology to Reassess Optimal Foraging Theory & Aquaculture Diets. Biosciences Ref: 2673

College of Life and Environmental Sciences

University of Exeter

Join a world-leading, cross-continental research team

The University of Exeter and the University of Queensland are seeking exceptional students to join a world-leading, cross-continental research team tackling major challenges facing the world’s population in global sustainability and wellbeing as part of the recently launched QUEX Institute. The joint PhD programme provides a fantastic opportunity for the most talented doctoral students to work closely with world class research groups and benefit from the combined expertise and facilities offered at the two institutions. This prestigious programme provides full tuition fees, stipend, travel funds and Research Training Support Grants to the successful applicants.

10 generous, fully-funded studentships are available for the best applicants, 5 offered by the University of Exeter and 5 by the University of Queensland. This select group will have the chance to study in the UK and Australia, and will graduate with a double degree from the University of Exeter and the University of Queensland.

Find out more about the PhD Studentships

Successful applicants will have a strong academic background and track record to undertake research projects based in one of the three themes of: Physical Activity and Nutrition; Healthy Ageing; and Environmental Sustainability.

Closing date for applications is 11 September 2017, with interviews on 26 September 2017. Start date in January 2018.

Please note that of the 11 Exeter led projects advertised, we expect that up to 5 posts will be filled.


Exeter Academic Lead: Prof. Rod W. Wilson
Queensland Academic Lead: Prof. Craig Franklin

Project description

Optimal foraging theory (food selection based on calorie/nutrient value) has not previously considered dietary acid-buffering capacity (which is not linked to calorific/nutrient content). Carnivorous fish commonly ingest whole prey, and hard skeletal parts (calcium phosphate in fish bone, calcium carbonate in invertebrate shells) are often entirely dissolved by gastric acid secretion. This process has an energetic cost, and in turn it induces an alkaline tide (rise in blood pH and bicarbonate during digestion) which we were the first to discover in teleost fish (Cooper & Wilson, 2008). Recovering post-feeding acid-base balance can take up to 3 days in fish, and has energetic costs (gill, intestinal and kidney ion transport), as well as physiological consequences for blood oxygen transport by haemoglobin.

Experiments at Exeter used rainbow trout fed on isocaloric pellet diets that differed only in the calcium salt added (calcium carbonate, calcium phosphate, or calcium chloride in equimolar quantities that mimic the skeletal calcium content of crustacean/mollusc or fish prey). These experiments demonstrated that acid-buffering minerals can have major energetic consequences during digestion. This raises hypotheses that dietary buffer capacity should influence: a) prey selection and hence optimal foraging theory in nature, and b) efficiency of growth in aquaculture.

Several species are amenable to test these hypotheses. For aquaculture this includes trout, salmon, sea bass and barramundi (providing both UK and Australian relevance). In nature, freshwater tench and sticklebacks consume whole snails (with calcium carbonate shells) as well as bony fish and soft-bodied invertebrates. A study of invasive lionfish (of marine conservation relevance) found they ate 78% teleosts and 14% crustaceans by volume (Morris and Akins, 2009).

This integrative ecophysiology project will apply automated respirometry to characterise energetic costs, and assess physiological consequences (ion/acid-base balance, blood oxygen transport) of consuming different artificial and natural diets across a realistic range of acid-buffering capacities. The supervisory team (Rod Wilson & Steve Simpson at Exeter, Craig Franklin at UQ, and Al Harborne at Florida) provides ideal physiological (RW/CF), behavioural (RW/SS/AH) and ecological/conservation expertise (CF/AH/SS), as well as current aquaculture collaborations within UK (RW) and Australia (CF). We can also use our existing collaborations with field stations (e.g. Lizard & Heron Island, Australia; CEI, Bahamas) to run mesocosm- and field-based studies of prey selection to further evaluate this novel idea regarding our understanding of optimal foraging theory.

Cooper CA, Wilson RW. 2008. Post-prandial alkaline tide in freshwater rainbow trout: effects of meal anticipation on recovery from acid-base and ion regulatory disturbances. Journal of Experimental Biology 211: 2542–2550

Morris JA, Akins JL. 2009. Feeding ecology of invasive lionfish (Pterois volitans) in the Bahamian archipelago. Environmental Biology of Fishes 86: 389–398

Academic Entry Requirements

Applicants should be highly motivated and have, or expect to obtain, either a first or upper-second class BSc (or equivalent) in a relevant discipline.

If English is not your first language you will need to meet the English language requirements and provide proof of proficiency. Click here for more information and a list of acceptable alternative tests.

Funding information

Funding applies to:
Open to applicants from a range of countries
Funding notes:

Full tuition fees, stipend of £15,000 p.a, travel funds of up to £15,000, and RTSG of £3,000 are available over the 3 year programme

Contacts and how to apply

Administrative contact and how to apply:

For further information and details of how to apply please see here.

Application deadline:

11 September 2017