Ocean acidification does not impair the behaviour of coral reef fishes

Abstract: The partial pressure of CO₂ in the oceans has increased rapidly over the past century, driving ocean acidification (OA) and sparking concern for the stability of marine ecosystems. Coral reef fishes are predicted to be especially susceptible to end-of-century OA, based on several high-profile papers reporting profound behavioural and sensory impairments (e.g., complete attraction to the chemical cues of predators under OA). In contrast, here we comprehensively and transparently show that end-of-century OA has negligible impacts on critical behaviours of coral reef fishes (i.e., avoidance of predator chemical cues, activity levels, and behavioural lateralisation). Using data simulations, we show that the large effect sizes and small within-group variance reported in several previous studies are highly improbable. Together, our findings indicate that reported effects of OA on coral reef fish behaviour are not reproducible, suggesting that behavioural perturbations will not be a major consequence for coral reef fishes in high CO₂ oceans.