MEPS 586:155-165 (2018)  -  DOI: https://doi.org/10.3354/meps12397

ABSTRACT: The appropriate behavioural response to predation risk is critical to survival; however, behavioural responses can be subjected to trade-offs. For example, individuals may engage in riskier foraging behaviour to secure sufficient energy if resources are limited. Additionally, elevated CO₂ can influence foraging and antipredator behaviour of marine organisms. Yet, how the availability of energetic resources may influence antipredator behaviour in an elevated CO₂ environment is unknown. We tested the effects of food ration (low and high: 4 and 8% of body weight per day, respectively) on antipredator behaviour at ambient (489 µatm) and elevated (1022 µatm) CO₂ in juvenile Amphiprion percula at 50 d post-hatching. Juveniles were from parents held at either ambient or elevated CO₂, as parental exposure can influence phenotypic response in offspring. Antipredator behaviour was severely impaired by elevated CO₂, with juveniles reared at elevated CO₂ exhibiting no change in feeding rate in the presence of the predator cue compared with a >67% reduction in feeding rate in ambient CO₂ fish. By contrast, food ration had a minor effect on the change in feeding rate in response to the predator cue, with only a 2.3% difference between high and low food ration fish. The effect of elevated CO₂ on antipredator behaviour of juveniles was not influenced by food ration. Parental exposure to elevated CO₂ influenced the baseline feeding rate and exhibited a small carry-over effect in elevated CO₂ juveniles. These results suggest that reef fish could exhibit riskier behaviour at elevated CO₂ levels, regardless of the energetic resources available.

KEY WORDS: Ocean acidification · Energy budget · Predation · Trade-offs · Parental effects · Climate change