During his PhD studies, Jonathan Christensen investigated how environmental conditions influence the energy use of Atlantic cod in the North Atlantic. Metabolism determines how much energy fish need to survive, grow and reproduce, and can therefore set limits on where species are able to live.

In his project, Christensen estimated the metabolic rate of wild Atlantic cod using chemical signals preserved in fish ear stones (otoliths). By combining these measurements with information about temperature and oceanographic conditions, he examined how metabolism varies across different parts of the cod’s distribution in Greenland and the North Sea.

The research provides new insight into how environmental conditions influence the physiological performance of marine fish and contributes to understanding how species may respond to climate change.

The PhD study was completed at the Department of Biology, Faculty of Natural Sciences, Aarhus University.

This summary was prepared by the PhD student.

Time: Tuesday, 26. May 2026 at 10:00
Place: Building 1531, room 113, Lecture Theatre D1, Department of Mathematics, Aarhus University, Ny Munkegade 116, 8000 Aarhus
Title of PhD thesis: A metabolic squeeze on marine fish: Does the field metabolic rate limit the geographic distribution of fish populations?
Contact information: Jonathan Christensen, e-mail: joch@bio.au.dk, tel.: +45 61289815
Members of the assessment committee:
Professor Christian Jørgensen, Department of Biological Sciences, University of Bergen, Norway
Senior researcher David J. McKenzie, Centre National de la Recherche Scientifique, Université de Montpellier, France
Associate Professor Brian Kieth Sorrell (chair), Department of Biology, Aarhus University, Denmark
Main supervisor: Professor Peter Grønkjær, Department of Biology, Aarhus University, Denmark
Language: The PhD dissertation will be defended in English

The defence is public.
The PhD thesis is available for reading at the Graduate School of Natural Sciences/GSNS, Ny Munkegade 120, building 1521, 8000 Aarhus C