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Brian H says:
IIRC, a paper recently established that lowered alkalinity increased the dissolution of “dead” coral and shells, but accelerated the uptake of CaCO3 into new growth. I.e., the whole cycle ran at greater speed. There would thus be a decrease in the speed with which limestone and chalk was laid down, and an increase in the quantity and number of “living corals”, etc.
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higley7 says:
First, I would love to know how they measured that the reef was dissolving at night. That’s going to be a marginal effect when you are dealing with a saturated or supersaturated calcium carbonate condition. Added CO2 cannot cause a pH change that dissolves calcium carbonate as it is part of an extended equilibrium from CO2 to carbonic acid to bicarbonate to carbonate to calcium carbonate. More CO2 means more calcium carbonate deposition.
Only an outside source of protons (acid), such as the digestive juices of a sea cucumber, can cause dissolution. No surprise here! And the expelled carbonate solution would simply go towards deposition the next day when photosynthesis, which is an alkalizing process, neutralizes the acid released by the sea cucumbers.
SO, there is nothing unusual here and all is normal, except for any reference to added CO2 having any deleterious effects. The fact is that reefs have been thriving over the last 50 years as CO2 has been rising.
“This is especially important because increased atmospheric carbon dioxide is predicted to decrease the amount of carbonate available due to acidification.”
This is their money phrase (more funding, please). The acidification they refer to is simply impossible; marine organisms thrive with more CO2, which goes well with the fact that CO2 has been much higher during the vast majority of the last 600 million years, during which coral evolved and thrived.