Cold-Water Corals Trumping Ocean Acidification: How Is It Done?
McCullock, M., Trotter, J., Montagna, P., Falter, J., Dunbar, R., Freiwald, A., Forsterra, G., Correa, M.L., Maier, C., Ruggeberg, A. and Taviana, M. 2012. Resilience of cold-water scleractinian corals to ocean acidification: Boron isotopic systematics of pH and saturation state up-regulation. Geochimica et Cosmochimica Acta 87: 21-34.
To further explore this suspected phenomenon, McCullock et al. extended the novel approach taken by Trotter et al. (2011), based on boron isotopic systematics, to determine the relationship between seawater pH and the internal (extracellular) pHcf at the site of calcification for several azooxanthellate cold-water scleractinian corals, which were collected from a large range of depths and geographically disparate sites, including southeast Australia, Chile's Comau Fjord, the Marmara Sea, a number of sites in the Mediterranean Sea, the northeast Atlantic Ocean and the northwestern Hawaiian Islands.
This suite of "aragonitic cold-water coral species," as the eleven researchers describe them, "collectively show an overall trend of higher ΔpH [= pHcf - seawater pH] values that is anti-correlated with seawater pH, with systematics generally consistent with biologically controlled pH up-regulation." And this result indicates that, "like symbiont-bearing tropical corals (Trotter et al., 2011), they have the ability to ameliorate or buffer external changes in seawater pH by up-regulating their pHcf at the site of calcification."
In light of these several observations, McCullock et al. conclude that "cold-water corals are likely to be much more resilient to decreasing seawater pH from ocean acidification than previously realized," because, as they see it, "decreasing seawater pH alone will only marginally affect calcification rates since this process would be largely countered by pHcf up-regulation in cold-water corals, together with enhanced calcification rates from warming of the deep oceans."
Once again, therefore, life appears to be well prepared for another environmental contingency.
Trotter, J.A., Mpontagna, P., McCulloch, M.T., Silenzi, S., Reynaud, S., Mortimer, G., Martin, S., Ferrier-Pages, C., Gattuso, J.-P. and Rodolfo-Metalpa, R. 2011. Quantifying the pH 'vital effect' in the temperate zooxanthellate coral Cladocora caespitosa: validation of the boron seawater pH proxy. Earth and Planetary Science Letters 303: 163-173.