Supplementary material from "Diel CO₂ cycles and parental effects have similar benefits to growth of a coral reef fish under ocean acidification"

Parental effects have been shown to buffer the negative effects of within-generation exposure to ocean acidification (OA) conditions on the offspring of shallow water marine organisms. However, it remains unknown if parental effects will be impacted by the presence of diel CO₂ cycles that are prevalent in many shallow water marine habitats. Here, we examined the effects that parental exposure to stable elevated (1000 μatm) and diel-cycling elevated (1000 ± 300 μatm) CO₂ had on the survival and growth of juvenile coral reef anemonefish, Amphiprion melanopus. Juvenile survival was unaffected by within-generation exposure to both elevated CO₂ treatments but was significantly increased (8%) by parental exposure to diel-cycling elevated CO₂. Within-generation exposure to stable elevated CO₂ caused a significant reduction in juvenile growth (10.7–18.5%); however, there was no effect of elevated CO₂ on growth when diel CO₂ cycles were present. Parental exposure to stable elevated CO₂ also ameliorated the negative effects of elevated CO₂ on juvenile growth, and parental exposure to diel CO₂ cycles did not alter the effects of diel CO₂ in juveniles. Our results demonstrate that within-generation exposure to diel-cycling elevated CO₂ and parental exposure to stable elevated CO₂ had similar outcomes on juvenile condition. This study illustrates the importance of considering natural CO₂ cycles when predicting the long-term impacts of OA on marine ecosystems.