Damselfish in Distress: an exploration of context-dependent stress responses of coral reef fish exposed to anthropogenic noise

Abstract

This research examines the stress response of two coral reef fish species subject to the prevalent stressor anthropogenic noise, and examines how that response may change in different contexts. Literature on anthropogenic impacts has focused almost exclusively on the response of organisms to single stressors, however modern marine organisms face multiple stressors simultaneously; this research advances our understanding of this multiple stressor interaction. These studies tested two primary hypotheses: 1, there will be a significant difference in the stress response of fish to anthropogenic noise between field and laboratory studies; 2, fish subjected to limited feeding will exhibit a heightened stress response in anthropogenic noise conditions but not in ambient conditions. Using two important coral reef fish species (Chromis viridis and Acanthrochromis polyacanthus), experiments were conducted in the field and the laboratory and employed multiple methods to test physiological functions indicative of a stress response to anthropogenic noise. The findings from the research show that, while qualitatively similar, the stress response can be overstated when considering results from laboratory trials, compared with field trials. This suggests that the impact of experimental situation on fish physiological stress responses is more complex than previously thought, and highlights the importance of accurate validation of results before extrapolation. This research also found fish subject to suboptimal dietary conditions are more likely to exhibit a heightened stress response when exposed to anthropogenic noise. A pronounced and/or prolonged stress response can be detrimental to organisms, both in terms of physiology and behaviour. This illustrates how vulnerable organisms in today’s oceans are even more at risk from impacts such as anthropogenic noise. Overall findings from this research offer insights into the multi-stressor environment marine life currently face, and provide solid evidence for the inclusion of anthropogenic noise – a comparatively easy stressor to regulate and mitigate – in environmental management plans.