As global warming alters the chemical makeup of the world’s oceans with increased concentrations of carbon dioxide, the world’s corals suffer from acidification, according to a November 2011 paper published in the online journal Coral Reefs.
Scientists from the University of California, Santa Cruz have been studying submerged ocean springs that emit low pH waters near the Yucatan Peninsula in Mexico for the last three years and found that while several species of smaller corals near the springs are able to calcify and grow at low pH levels where these springs are located, they were not the corals that form the backbone of the Mesoamerican Barrier Reef that is in close proximity to the springs. Their study indicates that seawater acidification affects these types of corals. The Mesoamerican Barrier Reef is one of the largest reef systems in the Caribbean.
The submerged springs, known as “ojos” Spanish for “eyes,” can be found on the east coast of the Yucatan Peninsula. These springs are fed by limestone “karst” landforms on the coast that release brackish water that has lower pH levels than the adjacent seawaters that these springs drain into. When pH levels are lowered, the chemical makeup of the adjacent seawater is affected with regard to calcium carbonate, and the surrounding corals have a more difficult time in building and maintaining their calcium carbonate-based structures.
UC Santa Cruz research professor Adina Paytan and co-author of the study told the Summit County Voice that lower pH levels do not bode well for the structure building, larger corals. The researchers conducted surveys around 10 springs and found that the number of coral species as well as the size of the coral colonies declined closer to the center of the spring. There were a few species of hard corals that were seen living near the center of the spring but Paytan said that these corals were not contributors to the larger reef framework of adjacent Caribbean reefs, though she indicated more study needed to determine the capability of these corals to build structure. The areas in which these ojos are located represent what scientists predict will be prevalent throughout the world’s oceans by the year 2100 because of acidification.
An abstract of the study can be found here.