Funded PhD studentship: “Response of ringed seal populations to environmental change in the Canadian Arctic”
The Arctic Ocean is undergoing unprecedented rates of environmental change, warming twice as fast as the global average (Hoegh-Guldberg and Bruno, 2010). Arctic sea ice concentrations have decreased by 9% per decade since 1978. Extended periods of open water have increased primary production by 30%from 1998 to 2012 (Arrigo and van Dijken 2015), causing regional changes in phytoplankton community size structure and diversity at the base of the food web (Li et al., 2009, Leu et al., 2011). Northward expansion of the ranges of boreal fish species is introducing different food sources to the Arctic food web (Fossheim et al. 2015). Understanding how food webs are being reshaped in time and space in response to these environmental stressors is crucial in addressing the impacts of future change on biodiversity, conservation and ecosystem services in the Arctic (Post et al., 2009, Eamer et al., 2013).
Ringed seals (Pusa hispida) have a circumpolar distribution, and they provide an important link between lower and higher trophic levels (Smith 1987). Changes in the distribution of key prey species and the borealization of fish stocks in the Arctic are likely to have implications for the foraging strategy of ringed seals and ultimately their body condition. Their life history is also strongly shaped by sea ice dynamics as stable land-fast ice is their preferred breeding habitat over pack ice (Smith and Stirling, 1975). Therefore, ringed seals can be seen as an indicator species of ecological change in the Arctic (Laidre et al., 2008). Changing sea ice dynamics as a result of climate change is expected to impact upon ringed seal populations and this is of concern to both Arctic communities and marine managers.
The student will study the ringed seal populations of the Canadian sub- and high- Arctic using a combination of existing telemetry and body condition datasets in combination with a novel biomarker approach. This multi-faceted approach will allow the student to determine the sensitivity of ringed seal foraging behaviour and ecological niche to their changing environment and the impact this has on their body condition and vital rates. There are a number of ringed seal populations in the Canadian Arctic which are observed at specific locations (see Figure 1 from Yurkowski et al., 2015). Ringed seals display different movement strategies with latitude and as such are exposed to different environmental pressures and stressors. The student will use existing telemetry data to characterise the foraging and migratory pattern of ringed seals in the Arctic based on 2-d tracking. Dive data can also be collected by the tags which carry depth sensors, so that the 3-dimensional aspects of foraging can also be reconstructed. Environmental measurements such as salinity and temperature can be recorded as well, allowing the student to relate seal habitat choice and diving to environmental covariates. Modern statistical methods e.g. Hidden Markov models and continuous time state-space models will be used to help determine relationships between seal movement/foraging and environment to suggest how their foraging patterns shift, as the environment changes. The student will use biomarker analysis of food sources and seals to reconstruct food webs of ringed seal populations. Biomarkers can be used alongside body condition to provide insight into the health of the seals. The objective is to quantitatively assess if the ecological niche of ringed seal populations is sensitive to changing environmental stressors in the Canadian Arctic and how this is manifested in the overall health/body condition of the ringed seal population.
The student will become part of a large team of UK and international scientists within the ARISE project, which is funded by the NERC Changing Arctic Ocean Programme. The student spend time at the CASE Partner, the University of Manitoba, Canada, learning about ringed seal ecology and conducting fieldwork as appropriate. Manitoba is very experienced in the collection and analysis of seal movement data and CREEM (UNSTAN) is a world leader in movement modelling, so the student will receive a strong training in analysing or Argos tracking data. Training in compound specific stable isotope analysis (of lipids and amino acids) will be provided in the Liverpool Isotopes for Environmental Research (LIFER) analytical facility so no prior experience in stable isotope analysis is required.
Full funding (fees, stipend, research support budget) is provided by the University of Liverpool. Formal training is offered through partnership between the Universities of Liverpool and Manchester in both subject specific and transferable skills to the entire PhD cohort and at each University through local Faculty training programmes.
Deadline: 23 January 2019