MEPS 501:99-111 (2014)  -  DOI: https://doi.org/10.3354/meps10690

ABSTRACT: To investigate the effect of diel variation in pCO₂ on coral calcification, branches of Acropora hyacinthus were collected in 2 habitats (upstream and downstream in a unidirectional flow) in a shallow back reef in Moorea, French Polynesia, where different diel amplitudes of pCO₂ oscillation were expected. Corals were maintained for 6 wk under different pCO₂ regimes (constant versus oscillatory), each delivered in 3 configurations: constant conditions of 400 µatm, 700 µatm, and 1000 µatm pCO₂, or oscillatory conditions varying daily from 280 to 550 µatm, 550 to 1000 µatm, or 400 to 2000 µatm, with minima and maxima during the day and night, respectively. Calcification rates in all treatments tended to increase over time, and the interaction between Time and pCO₂ regime (i.e. constant versus oscillating) was significant (or close to significant) for upstream corals due to higher calcification in oscillatory pCO₂. A significant pCO₂ regime effect was detected in the highest pCO₂ for downstream corals, with higher calcification in the 400 to 2000 µatm oscillatory pCO₂ treatment compared to the 1000 µatm constant pCO₂ treatment. After 6 wk, calcification of A. hyacinthus was affected significantly by habitat, the pCO₂ level, and the pCO₂ regime. Calcification generally was reduced by high pCO₂ and was ≥21% greater in 400 to 2000 µatm oscillatory pCO₂ versus 1000 µatm constant pCO₂ treatment. Increased calcification in the 400 to 2000 µatm oscillatory pCO₂ treatment suggests that natural diel oscillations in pCO₂ could play a role by reducing the locally negative effects of rising pCO₂ associated with ocean acidification on coral calcification.

KEY WORDS: Calcification · Corals · Acclimation

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Cite this article as: Comeau S, Edmunds PJ, Spindel NB, Carpenter RC (2014) Diel pCO2 oscillations modulate the response of the coral Acropora hyacinthus to ocean acidification. Mar Ecol Prog Ser 501:99-111. https://doi.org/10.3354/meps10690 Export citation Share:    Facebook - - linkedIn