NERC GW4+ DTP PhD studentship: Impacts of changing distribution, quality and quantity of fish on marine predators

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. Stephen Votier, College of Environmental and Life Sciences, University of Exeter

Intense warming and fisheries overexploitation have dramatically altered marine fish distribution and abundance, with profound implications for predator-prey interactions. The same drivers are also altering the energetic quality of fish, but the implications of these changes are severely understudied.

Globally, populations of marine predators (birds, mammals and predatory fish) have declined significantly in recent decades. These declines have been linked with dwindling fish stocks, as well as changes in the distribution and energetic content of fish on which they feed (Sydeman et al. 2015), but studies lack a mechanistic understanding of predator-prey interactions in marine predators.
The aim of the current studentship is to examine the effects of changes in pelagic fish abundance, distribution and quality upon seabirds, using a combination of tracking, dietary analysis, modelled fish distribution & abundance, in conjunction with individual-based models, to address fundamental and applied questions. The studentship will focus on northern gannets to address the following hypotheses:

1. Variation in foraging effort is linked with the energetic reward of prey.
We will test this by deploying bird-borne sensors to record prey species and size (video; Fig. 1) and measure energy expenditure (acceleration) to measure directly the net costs of feeding on different prey. Foraging observations will be verified with diet data based on stable isotopes, pellets and regurgitates.

Figure 1. Gannet-borne cameras accurately record foraging and prey capture: a) scavenging and b) hunting shoaling fish (Wells et al. 2015).

2. Inter- and intra-annual variation in seabird foraging distribution is linked with spatial variation in their prey.
We will use multi-annual precision GPS tracking (n=>300 individuals, 13 years) in combination with “ethoinformatics” to identify gannet foraging grounds and relate these to modelled data on pelagic fish distribution and abundance (Rutterford et al. 2015), controlling for the potentially confounding effects of fisheries activity.

3. Individual-Based Models (IBMs) will reveal the population-level consequences of variation in pelagic fish availability.
IBMs have been used widely to inform decision-making, by predicting how environmental changes affect demographics. Using parameters from objectives 1 and 2, the student will develop and test a model to predict the impact of changing forage fish distribution, quality and quantity on fitness.

See http://www.exeter.ac.uk/studying/funding/award/?id=2304 for full details and how to apply.