Faculty Profiles

Gregory Thiemann

Associate Professor
Undergraduate Program Director
Hons BSc - McMaster
MSc - Dalhousie
PhD - Dalhousie

Areas of Academic Interest

  • Arctic ecosystems

  • Food web ecology

  • Wildlife conservation

  • Resource management

  • Animal physiology

Biography

My research focuses on the foraging ecology and conservation of Arctic carnivores. By examining the trophic relationships between top predators and their prey, we can define the structure of food webs and monitor changes in ecosystems over time. By understanding where, when, and how predators hunt for food, we can better act to protect wildlife populations and entire ecosystems.

Much of my research has involved the use of fatty acid signature analysis to examine the diets of marine and terrestrial carnivores. This technique is based on the knowledge that ingested dietary fatty acids (such as “omega-3’s”) are predictably incorporated into a predator’s fat stores. Therefore, the fatty acid profile of an animal can be used to make inferences about its foraging habits.

Long-term climate warming is having rapid and widespread effects on northern ecosystems. This in turn is altering the relationships between northern aboriginal communities and the wildlife populations they utilize. Accurate information on the current structure and functioning of food webs will help us predict how wildlife populations will change in the future and how these changes will impact the lives of people in the North. FES is uniquely positioned to examine the complex ecological, social, and economic changes that will result from a warming Arctic environment.

Major research projects

  • Foraging Ecology and Habitat Use of Polar Bears in Southern Hudson Bay
  • Community-Based Monitoring of Ice-Breeding Seals and Polar Bear Feeding in the Gulf of Boothia
  • Predator-Prey Interactions in Dynamic Arctic Ecosystems
  • Nutritional Physiology of Bears
  • Fatty Acid Profiles of Marine Mammals in Nunavut

Selected Publications

Laforest, B.J., J. Hebert, M.E. Obbard, G.W. Thiemann. 2018. Traditional Ecological Knowledge of polar bears in the northern Eeyou Marine Region, Québec, Canada. Arctic 71: 40-58.

Brown, T.A., M.P. Galicia, G.W. Thiemann, S.T. Belt, D.J. Yurkowski, M.G. Dyck. 2018. High contributions of sea ice derived carbon in polar bear (Ursus maritimus) tissue. PLoS ONE 13(1): e0191631. doi: 10.1371/journal.pone.0191631.

Ferguson, S., X. Zhu, B. Young, D. Yurkowski, G.W. Thiemann, A. Fisk, D. Muir. 2018. Geographic variation in ringed seal growth rate and body size. Canadian Journal of Zoology: 96: 649–659. doi: 10.1139/cjz-2017-0213.

Tartu, S., R. Lille-Langøy, T.R. Størseth, S. Bourgeon, A. Brunsvik, J. Aars, A. Goksøyr, B.M. Jenssen, A. Polder, G.W. Thiemann, V. Torget and H. Routti. 2017. Multiple-stressor effects in an apex predator: combined influence of pollutants and sea ice decline on lipid metabolism in polar bears. Scientific Reports 7: 16487. doi:10.1038/s41598-017-16820-5.

Sciullo, L., G.W. Thiemann, N.J. Lunn, S.H. Ferguson. 2017. Intraspecific and temporal variability in the diet composition of female polar bears in a seasonal sea ice regime. Arctic Science 3: 672–688. doi: 10.1139/as-2017-0004.

Bromaghin, J.F., S.M. Budge, G.W. Thiemann and K.D. Rode. 2017. Simultaneous estimation of diet composition and calibration coefficients with fatty acid signature data. Ecology and Evolution 7: 6103-6113. doi: 10.1002/ece3.3179.

Pagano, A.M., K.D. Rode, A. Cutting, M.A. Owen, S. Jensen, J.V. Ware, C.T. Robbins, G.M. Durner, T.C. Atwood, M.E. Obbard, K.R. Middel, G.W. Thiemann, and T.M. Williams. 2017. Using tri-axial accelerometers to identify wild polar bear behaviors. Endangered Species Research 32: 19-33.

Bromaghin, J.F., S.M. Budge, G.W. Thiemann and K.D. Rode. 2016. Assessing the robustness of quantitative fatty acid signature analysis to assumption violations. Methods in Ecology and Evolution 7: 51-59. doi: 10.1111/2041-210X.12456.

Bromaghin, J.F., S.M. Budge, G.W. Thiemann. 2016. Should fatty acid signature proportions sum to 1 for diet estimation? Ecological Research 31: 597-606. doi: 10.1007/s11284-016-1357-8.

Regehr, E.V., K.L. Laidre, H. Resit Akçakaya, S.C. Amstrup, T.C. Atwood, N.J. Lunn, M. Obbard, H. Stern, G.W. Thiemann, and Ø. Wiig. 2016. Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines. Biology Letters 12: 20160556. doi: 10.1098/rsbl.2016.0556

Sciullo, L., G.W. Thiemann and N.J. Lunn. 2016. Comparative assessment of metrics for monitoring the body condition of polar bears in Western Hudson Bay. Journal of Zoology, London 300: 45-58. doi: 10.1111/jzo.12354.

Galicia, M.P., G.W. Thiemann, M.G. Dyck, S.H. Ferguson and J.W. Higdon. 2016. Dietary habits of polar bears in Foxe Basin, Canada: possible evidence of a trophic regime shift mediated by a new top predator. Ecology and Evolution 16: 6005-6018. doi:10.1002/ece3.2173.

Tartu, S., S. Bourgeon, J. Aars, M. Andersen, D. Ehrich, G.W. Thiemann, J.M. Welker, H. Routti. 2016. Geographical area and life history traits influence diet in an Arctic marine predator. PLoS ONE 11(5): e0155980. doi:10.1371/journal.pone.0155980.

Galicia, M.P., G.W. Thiemann, M.G. Dyck, and S.H. Ferguson. 2015. Characterization of polar bear (Ursus maritimus) diets in the Canadian High Arctic. Polar Biology 38: 1983-1992. doi: 10.1007/s00300-015-1757-1.

Marcoux, M., V. Lesage, G.W. Thiemann, S.J. Iverson and S.H. Ferguson. 2015. Age estimation of belugas Delphinapterus leucas using fatty acid composition: a promising method. Marine Mammal Science 31: 944-962

Bromaghin, J.F., K.D. Rode, S.M. Budge and G.W. Thiemann. 2015. Distance measures and optimization spaces in quantitative fatty acid signature analysis. Ecology and Evolution 5: 1249-1262.

Duerksen, S.W., G.W. Thiemann, S.M. Budge, M. Poulin, A. Niemi, C. Michel. 2014. Large, omega-3 rich, pelagic diatoms under Arctic sea ice: sources and implications for food webs. PLoS ONE 9(12): e114070.

Rode, K.D., E.V. Regehr, D. Douglas, G. Durner, A.E. Derocher, G.W. Thiemann, S. Budge. 2014. Variation in the response of an Arctic top predator experiencing habitat loss: nutritional and reproductive ecology of two polar bear populations. Global Change Biology 20: 76-88.