U.S. scientists say coral reef systems exposed to the open ocean are most vulnerable to warming ocean temperatures. In a new study, researchers at the University of North Carolina write that three distinct coral zones located within the Mesoamerican Barrier Reef System in Central America — including the foreef (closest to the ocean), the nearshore (closest to the shore), and the backreef (directly behind the reef crest) — saw an increase in average summer sea surface temperatures from 1982 to 2008. But while they observed a decline in skeletal growth in corals facing the ocean during that period, coral growth rates in the other two zones remained relatively stable. According to their findings, published in the journal Nature Climate Change, the ocean-facing corals were more vulnerable to warming conditions because historically they had experienced cooler and more stable seawater. “However, because backreef and nearshore coral colonies have historically been exposed to warmer and more variable seawater temperatures, they seem to be less affected,” said Karl Castillo, a postdoctoral researcher at UNC and lead author of the study.