Parental effects improve escape performance of juvenile reef fish in a high-CO2 world

Abstract

Rising CO2 levels in the oceans are predicted to have serious consequences for many marine taxa. Recent studies suggest that non-genetic parental effects may reduce the impact of high CO2 on the growth, survival and routine metabolic rate of marine fishes, but whether the parental environment mitigates behavioural and sensory impairment associated with high CO2 remains unknown. Here, we tested the acute effects of elevated CO2 on the escape responses of juvenile fish and whether such effects were altered by exposure of parents to increased CO2 (transgenerational acclimation). Elevated CO2 negatively affected the reactivity and locomotor performance of juvenile fish, but parental exposure to high CO2 reduced the effects in some traits, indicating the potential for acclimation of behavioural impairment across generations. However, acclimation was not complete in some traits, and absent in others, suggesting that transgenerational acclimation does not completely compensate the effects of high CO2 on escape responses.

Keywords: acclimation predation; carbon dioxide; climate change; locomotion; ocean acidification; parental effects.

Figure 1.

The effect of elevated CO₂ on the escape performance of juvenile A. melanopus in three different parent–offspring CO₂ treatments (control–control, high–high and control–high). The comparison between control–control and control–high assesses acute effects of elevated CO₂ on juveniles, while the comparison of the high–high group with the other two groups assesses the effects of parental exposure to high CO₂ on juvenile performance. Variables displayed are: (a) response distance, (b) mean speed, (c) max. speed, (d) response duration, (e) proportion of non-reactors, (f) directionality and (g) response latency. Errors are standard errors. Letters above bars represent Tukey's HSD groupings of means. Asterisk above panel (f) represents the proportion of responses directed away (unfilled portion) and towards (filled portion) the stimulus that differed significantly from random. n = control–control 45, high–high 37, control–high 43 (a–e); n = control–control 46, high–high 34, control–high 34 (f,g).