Resilience of cold-water scleractinian corals to ocean acidification: Boron isotopic systematics of pH and saturation state up-regulation

Intra-skeletal calcite in a live-collected Porites sp.: Impact on environmental proxies and potential formation process

“…6) we calculated a valueof 17.05±0.85‰ for a virtual 100%-calcite end-memberwith a constant seawater δ 11 B value of 39.61‰ .This would correspond to a calculatedpH solution of about 7.87 ± 0.11. It can be noted that such low δ 11 B value was recently observed for calcite cold-water octocorals (Farmer et al, 2015;McCulloch et al, 2012) which calcifying fluid pH fallingwithin 7.6-8.0.Nevertheless, in a biologically-controlled biomineralization, aragonite and calcite precipitation strictly results from the control of the organic matrix compounds,in the scleractinian coral case synthesized by the calicoblastic epithelium (Falini et al, 1996;Falini et al, 2013;Mass et al, 2013;Puverel et al, 2005;Rahman et al, 2011;. To date, no coral specieshasbeen found to produce both CaCO 3 polymorphsin natural modern seawater conditions, even in the primary skeleton formed by coral post-larvae (Clode et al, 2011).…”

“…In this assumption, a α value of 1.027 is used instead of 1.020 to determine pH solution . Fortunately, such pH solution inferred from Porites would also depend on the seawater pH (pH sw ) following the Porites-specific formula: pH sw = (pH solution -5.954)/0.32 (D'Olivo et al, 2015;McCulloch et al, 2012). By applying this approach, our new resultingpH sw has low values (7.10-7.62), from 0.5 to 1 pH-unit lower than the mean regional seawater pH of 8.12 (Fig.…”

The influence of seawater pH on U / Ca ratios in the scleractinian cold-water coral <i>Lophelia pertusa</i>

“…Clearly more detailed CWC U / Ca and seawater pH measurements are required, especially from different ocean basins and cultivation experiments, but our unique field calibration data set suggests U / Ca in L. pertusa may complement δ 11 B measurements (Anagnostou et al, 2012;McCulloch et al, 2012) to reconstruct seawater pH.…”

“…However, some studies indicate scleractinian CWCs are resilient to ocean acidification in conditions with arag < 1 (e.g. Anagnostou et al, 2012;Form and Riebesell, 2012;Maier et al, 2009;McCulloch et al, 2012). This implies that they may have developed adaptive strategies to not only thrive in cool waters but also to survive under low carbonate saturations states.…”

“…Case et al, 2010;Cohen et al, 2006;Gagnon et al, 2007;Lutringer et al, 2005;Montagna et al, 2006;Raddatz et al, 2013;RollionBard et al, 2009;Rüggeberg et al, 2008;Smith et al, 2000). To date only a few studies have focused on the reconstruction of the carbonate system using CWC skeletons (Anagnostou et al, 2011(Anagnostou et al, , 2012Blamart et al, 2007;McCulloch et al, 2012;Rollion-Bard et al, 2011a, b;Thresher et al, 2011). Coral uranium to calcium (U / Ca) ratios are known to depend on the carbonate system parameters (Anagnostou et al, 2011;Inoue et al, 2011;Min et al, 1995;Shen and Dunbar, 1995;Swart and Hubbard, 1982).…”