Digital participation
Main research findings
Stress is a natural part of life. However, whilst organisms have evolved mechanisms over millions of years to cope with natural stressors in their environment, humans have, in the space of a few decades, created a multitude of new stressors that threaten our natural world.
This thesis assessed the effect of three stressors – chemical pollution, whale watching tourism, and nutritional stress – on an ecologically, economically and socially important species: the killer whale (Orcinus orca). We used a combination of field and laboratory studies, and developed new analytical techniques for multiple analyses in tiny tissue samples.
We first established baseline pollutant and exposure data for Norwegian killer whales. We found that whilst long-regulated “legacy” pollutants dominated the pollutant load, unregulated “emerging” contaminants were an increasing risk, and could also biomagnify and be passed from mother to offspring.
We then found potential effects of both pollutants and whale watching on hormone levels, and the expression of stress and immune-related genes. The effect of contaminants on cortisol was further amplified during high whale watching periods, with the strongest stress response in whales with better nutritional status.
This thesis presents an interdisciplinary framework for assessing the effect of multiple stressors in a wild population, and emphasises the importance of assessing the effect of stressors in combination.
Trial lecture
The candidate will first give a trial lecture on the following topic: 'Cumulative Impacts of Anthropogenic Stressors on Marine Sentinel Species: From biomarkers to population level effects'.
Please note that the trial lecture will take place the day before the disputation.
Adjudication committee
- Associate Professor Krishna Das, Department of Biology, Ecology and Evolution, University of Liège, Belgium
- Professor Bjørn Munroe Jenssen, Department of Biology, NTNU, Trondheim, Norway
- Professor Johan Øvrevik, Department of Biosciences, University of Oslo, Norway
Chair of the defense
- Professor Josefin Titelman, Department of Biosciences (IBV), University of Oslo, Norway
Supervisors
- Professor Katrine Borgå, Department of Biosciences, University of Oslo, Norway
- Professor Anders Ruus, Department of Biosciences, University of Oslo & Norwegian Institute of Water Research (NIVA), Norway
- Dr. Eve Jourdain, Department of Biosciences, University of Oslo & Norwegian Orca Survey, Norway
- Professor Jan Ludvig Lyche, Department of Paraclinical Sciences, Norwegian University of Life Sciences (NMBU), Norway