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13 juillet 2023
Differences in carbonate chemistry up-regulation of long-lived reef-building corals

With climate projections threatening the future survival of stony corals and their dominance as tropical reef builders, it is critical to understand the adaptive capacity of corals to ongoing climate change. Biological mediation of the carbonate chemistry of the coral calcifying fluid is a fundamental component for assessing the response of corals to global threats. The Tara Pacific expedition (2016-2018) provided an opportunity to investigate calcification patterns in extant corals throughout the Pacific Ocean. Cores from colonies of the massive Porites and Diploastrea genera were collected from different environments to assess calcification parameters of long-lived reef-building corals.

Fig. 1. Coral skeletal composition. (A)  B/Ca and (B) δ11B values of Porites (n = 33, blue) & Diploastrea (n = 6, red) corals across the Pacific Ocean plotted against SST. (C-F) Carbonate chemistry variables of calcifying fluid calculated for each colony (DICcf, pHcf, [CO32-]cf, Ωcf, respectively) against SST. The filled blue and red dots represent the 6 sites where both Porites and Diploastrea were sampled

At the basin scale of the Pacific Ocean, we show that both genera systematically up-regulate their calcifying fluid pH and dissolved inorganic carbon to achieve efficient skeletal precipitation. However, while Porites corals increase the aragonite saturation state of the calcifying fluid (Ωcf) at higher temperatures to enhance its calcification capacity, Diploastrea shows a steady homeostatic Ωcf across the Pacific temperature gradient. Thus, the extent to which Diploastrea responds to ocean warming and/or acidification is unclear, and it deserves further attention whether this is beneficial or detrimental to future survival of this coral genus.

Fig. 2. Correlations between SST & calcifying fluid composition in co-occurring Porites (n = 6, blue dots) and Diploastrea (n = 6, red dots) specimens across the Pacific Ocean. Solid blue and red lines in the left panels indicate significant correlations.

Reference: Marine Canesi, E. Douville, P. Montagna, M. Taviani, J. Stolarski, L. Bordier, A. Dapoigny, G. E. H. Coulibaly, A.-C. Simon, M. Agelou, J. Fin, N. Metzl, G. Iwankow, D. Allemand, S. Planes, C. Moulin, F. Lombard, G. Bourdin, R. Troublé, S. Agostini, B. Banaigs, E. Boissin, E. Boss, C. Bowler, C. de Vargas, M. Flores, D. Forcioli, P. Furla, E. Gilson, P. E. Galand, S. Pesant, S. Sunagawa, O. Thomas, R. Vega Thurber, C. R. Voolstra, P. Wincker, D. Zoccola, S. Reynaud (2023). Differences in carbonate chemistry up-regulation of long-lived reef-building corals. Scientific Report, 41598. DOI : 10.1038/s41598-023-37598-9

#356 - Màj : 14/12/2023
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