Ocean warming and hypoxia are major consequences of climate change which are predicted to increase in severity and frequency in the near future. Previous studies have shown that both warming and hypoxia can alter the behaviour of fish exposed to these conditions, but the interactive effects of both stressors are poorly understood. This study tested the effects of increased water temperature and reduced dissolved oxygen as single and combined stressors on boldness and exploration behaviour of early life stages of white seabream, Diplodus sargus. Fish were kept in four treatments: either at ambient (20°C) or increased temperature (24°C), combined with either hypoxia or normoxia. Results suggest a significant effect of hypoxia on risk-taking related behaviours, especially when combined with high temperature. Individuals exposed to the combination of stressors were bolder and experienced differences in exploration behaviour than when exposed to hypoxia as a single stressor and in some cases also compared to normoxia conditions. Temperature, on the other hand, as an individual stressor, had no influence on white seabream behaviour. This study provides relevant knowledge on fishes’ key behavioural responses to the combined effects of co-concurrent stressors.
Managing Thesis and Internship Exchanges
