High p CO 2 promotes coral primary production

• Published in: Biology Letters
• Main Authors: Biscéré, T, Zampighi, M, Lorrain, A, Jurriaans, S, Foggo, A, Houlbrèque, F, Rodolfo-Metalpa, R
• Format: Article in Journal/Newspaper
• Language: English
• Published: Royal Society, The 2019
• Subjects: ocean acidification; coral reefs; acclimatization; metabolic flexibility; CO2 seeps; Ocean acidification
• Online Access: http://hdl.handle.net/10026.1/14756; https://doi.org/10.1098/rsbl.2018.0777

<jats:p> While research on ocean acidification (OA) impacts on coral reefs has focused on calcification, relatively little is known about effects on coral photosynthesis and respiration, despite these being among the most plastic metabolic processes corals may use to acclimatize to adverse conditions. Here, we present data collected between 2016 and 2018 at three natural CO <jats:sub>2</jats:sub> seeps in Papua New Guinea where we measured the metabolic flexibility (i.e. <jats:italic>in hospite</jats:italic> photosynthesis and dark respiration) of 12 coral species. Despite some species-specific variability, metabolic rates as measured by net oxygen flux tended to be higher at high <jats:italic>p</jats:italic> CO <jats:sub>2</jats:sub> ( <jats:italic>ca</jats:italic> 1200 µatm), with increases in photosynthesis exceeding those of respiration, suggesting greater productivity of Symbiodiniaceae photosynthesis <jats:italic>in hospite</jats:italic> , and indicating the potential for metabolic flexibility that may enable these species to thrive in environments with high <jats:italic>p</jats:italic> CO <jats:sub>2</jats:sub> . However, laboratory and field observations of coral mortality under high CO <jats:sub>2</jats:sub> conditions associated with coral bleaching suggests that this metabolic subsidy does not result in coral higher resistance to extreme thermal stress. Therefore, the combined effects of OA and global warming may lead to a strong decrease in coral diversity despite the stimulating effect on coral productivity of OA alone. </jats:p>