The study took advantage of the unusual seawater chemistry found naturally at sites along the Caribbean coastline of Mexico's Yucatan Peninsula, where water discharging from submarine springs has lower pH than the surrounding seawater, with reduced availability of the carbonate ions corals need to build their calcium carbonate skeletons.
In a two-year field experiment, the international team of researchers transplanted genetically identical fragments of three species of corals to a site affected by the springs and to a nearby control site not influenced by the springs, and then monitored the survival, growth rates, and other physiological traits of the transplants. They reported their findings in a paper published June 26 in Proceedings of the Royal Society B.
News - Corals - Calcium - Carbonate - Density
"The good news is the corals can survive and deposit calcium carbonate, but the density of their skeletons is reduced, which means the framework of the reef would be less robust and might be more susceptible to storm damage and bioerosion," said Adina Paytan, a research professor at UCSC's Institute of Marine Sciences and corresponding author of the paper.
Of the three species tested, the one that performed best in the low-pH conditions was Siderastrea siderea, commonly known as massive starlet coral, a slow-growing species that forms large dome-shaped structures. Another slow-growing dome-shaped species, Porites astreoides (mustard hill coral), did almost as well, although its survival rate was 20 percent lower. Both of these species outperformed the fast-growing branching coral Porites porites (finger coral).
Coauthor - Donald - Potts - Professor - Ecology
Coauthor Donald Potts, professor of ecology and evolutionary biology at UC Santa Cruz, said the transplanted species are all widespread throughout the Caribbean. "The slow-growing, dome-shaped corals tend to be more tolerant of extreme conditions, and they are important in building up the permanent structure of the reef," he said. "We found that they have the potential for persistence in acidified conditions."
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