Read here. For the oceans to become sufficiently "acidified" to have any impact on coral larvae, it would require an atmospheric CO2 level that exceeds 2100 ppm. The likelihood that level of CO2 will be attained due human emissions is extremely low, and very far into the future if it were to happen. The possible impact would be a reduction in size of larvae but would also include a positive increase in survivorship.
"In discussing their findings, the seven scientists say they indicate that "the survival of coral larvae may not be strongly affected by pH change," or "in other words," as they continue, "coral larvae may be able to tolerate ambient pH decreases of at least 0.7 pH units," which, in fact, is something that will likely never occur, as it implies atmospheric CO2 concentrations in the range of 2115 to 3585 ppm. In addition, if such high concentrations ever were to occur, they would be a long, long time in coming, giving corals far more than sufficient time to acclimate -- and even evolve -- to adequately cope with the slowly developing situation."
