Kleypas JA, Langdon C (2006) “Coral reefs and changing seawater chemistry”, Chapter 5 In: Phinney J, Hoegh-Guldberg O, Kleypas J, Skirving W, Strong AE (eds) Coral Reefs and Climate Change: Science and Management. AGU Monograph Series, Coastal and Estuarine Studies. Geophys. Union, Washington DC, pp 73-110.]]>
Is there in fact any evidence to support any independent link between calcification and acidity in the fairly narrow pH range in question?
Since corals make calcium carbonate from the bicarbonate ion, and bicarbonate concentrations are not much affected by pH in the pH range in question (8.0 to 8.5 approx), there is no obvious reason why acidity should be a significant factor in coral deposition of calcium carbonate.
Indeed increased ocean acidity caused by increased CO2 from the atmosphere will surely lead to higher levels of bicarbonate – which is known to be a coral ‘fertiliser’ which – other things being equal – results in a higher rate of calcification .
As for temperature, there is of course no dispute that corals are stressed by higher temperatures and that this would be expected to reduce calcification. But again, direct experimental evidence in support of this entirely believable hypothesis would be desirable.
Re the important question that temperature rise and acidification might act synergistically to reduce calcification, is there any evidence in support of this?
Another question that it would be intriguing to investigate further is whether raising bicarbonate concentrations would have any effect in reducing the adverse impact on coral of heat stress. If it does, then that would offer a possible route for protecting coral reefs against temperature increase.]]>
Here it is:
As far as I know, it’s still unpublished.]]>