Corals grow their skeletons upward toward sunlight, thickening and reinforcing them. The new research, led by National Science Foundation (NSF)-funded scientists at the Woods Hole Oceanographic Institution (WHOI), shows that ocean acidification impedes the thickening process -- decreasing the skeletons' density and leaving them more vulnerable to breaking. The results were published this week in the journal Proceedings of the National Academy of Sciences.
The research team included Nathaniel Mollica (MIT-WHOI); Weifu Guo, Anne Cohen and Andrew Solow (WHOI); Kuo-Fang Huang (Academia Sinica in Taiwan); and Hannah Donald and Gavin Foster (University of Southampton in England).
The researchers examined the coral growth process and showed that the corals can't produce as much aragonite to thicken their skeletons. The corals continue to invest in upward growth, but thickening suffers. As a result, corals build thinner skeletons that are more susceptible to damage from pounding waves or attacks by eroding organisms. The results show that by the start of the next century, declines in coral skeletal density will occur on many coral reefs.
The impact will be especially strong in the Indo-Pacific region, with up to 20 percent reductions in the densities of coral skeletons in parts of the Coral Triangle -- the area bounded by the waters of Indonesia, Malaysia, the Philippines, Papua New Guinea, Timor-Leste and the Solomon Islands. Corals in the Caribbean, Hawaii and northern Red Sea may fare better, the scientists say.