Global warming will have far-reaching consequences for marine species over coming decades, yet the magnitude of these effects may depend on the rate of warming across generations. Recent experiments show coral reef fishes can compensate the metabolic challenges of elevated temperature when warm conditions are maintained across generations. However, the effects of a gradual temperature increase across generations remain unknown. In the present study, we analyzed metabolic and molecular traits in the damselfish Acanthochromis polyacanthus that were exposed to +1.5°C in the first generation and +3.0°C in the second (Step +3.0°C). This treatment of step-wise warming was compared to fish reared at current-day temperatures (Control), second-generation fish of control parents reared at +3.0°C (Developmental +3.0°C), and fish exposed to elevated temperatures for two generations (Transgenerational +1.5°C and Transgenerational +3.0°C). Hepatosomatic index, oxygen consumption and liver gene expression were compared in second-generation fish of the multiple treatments. Hepatosomatic index increased in fish that developed at +3.0°C, regardless of the parental temperature. Routine oxygen consumption of Step +3.0°C fish was significantly higher than Control, however their aerobic scope recovered to the same level as Control fish. Step +3.0°C fish exhibited significant upregulation of genes related to mitochondrial activity and energy production, which could be associated to their increased metabolic rates. These results indicate that restoration of aerobic scope is possible when fish experience gradual thermal increase across multiple generations, but the metabolic and molecular responses are different from fish reared at the same elevated thermal conditions in successive generations. This article is protected by copyright. All rights reserved.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): OCRF-2014-CRG3-62140408
Acknowledgements: Funding for this project was provided by the Competitive Research Funds OCRF-2014-CRG3-62140408 from the King Abdullah University of Science and Technology (T. Ravasi and T. Ryu), and the Australian Research Council (ARC) and the ARC Centre of Excellence for Coral Reef Studies (P.L. Munday). Research was conducted under JCU Ethics approval A1233, A1415 and A1547. We would like to acknowledge the staff of the Marine Aquaculture Research Facility of JCU for their help with maintaining the experimental systems. Thanks to scientific illustrator Ivan Gromicho of the Research Publication Services at KAUST for crating Figures 1-5 of this manuscript. Thanks to the staff of Macrogen for their help with the library preparation and sequencing of RNA-Seq libraries. Special thanks to members of the Ravasi lab and Giverny Rodgers for their input on this manuscript.