Behavioral and physiological indicators of stress coping styles in larval zebrafish

Abstract

Different individuals cope with stressors in different ways. Stress coping styles are defined as a coherent set of individual behavioral and physiological differences in the response to a stressor which remain consistent across time and context. In the present study, we have investigated coping styles in larval zebrafish (Danio rerio) at 8 days post-fertilization. Larvae were separated into two groups, according to the emergence sequence from a darkened into a novel well-lit environment, early (EE) and late (LE) emergers. We used brief periods of netting as a stressor. Swimming behavior and kinematics before and after netting stress were analyzed, as were whole-body cortisol levels before and at 10, 30 and 60 min after the stress event. The results show that general swimming activity was different between EE and LE larvae, with lower baseline cumulative distance and more erratic swimming movements in EE than in LE larvae. EE larvae showed a faster recovery to baseline levels after stress than LE larvae. Cortisol baseline levels were not different between EE and LE larvae, but peak levels after stress were higher and the recovery towards basal levels was faster in EE than in LE larvae. This study shows that coping styles are manifest in zebrafish larvae, and that behavior and swimming kinematics are associated with different cortisol responses to stress. A better understanding of the expression of coping styles may be of great value for medical applications, animal welfare issues and conservation.

• Behavioral syndrome
• cortisol
• HPA axis
• kinematics
• personality
• physiology
• stress

Acknowledgements

We would like to acknowledge the technical support of Davy de Witt and the helpful discussions with Herman Spaink and Peter Steenbergen.

Declaration of interest

There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported. The authors alone are responsible for the content and writing of the paper.

CT was supported by an NWO-STW funded VENI-fellowship (#11731).