Some Coral May Be Better Suited for a Warmer, More Acidic Ocean
Aside from acting as center of biodiversity in the oceans, coral reefs play important roles in costal ecosystems and protect shorelines during storms and rough seas. Unfortunately, with ocean temperatures forecast to increase between one and three degrees Celsius by the end of the century, the outlook for these vital habitats is not good. The problem, scientists have long known, is that as water temperatures and acidity levels increase, the algae that feeds them struggles to survive.
"Until recently, it was widely assumed that coral would bleach and die off worldwide as the oceans warm due to climate change," explained Jessica Carilli, a coral researcher at the Australian Nuclear Science and Technology Organisation, "this would have very serious consequences, as loss of live coral—already observed in parts of the world—directly reduces fish habitats and the shoreline protection reefs provide from storms."
Two recent studies, however, suggest that all of the world's coral is not equally vulnerable.
A team led by Carilli has found that reefs with a history of sustaining dramatic temperature shifts—like those within the path of El Nino currents—are better able to weather increasing ocean temperatures.
In a separate study, conducted at Australia’s ARC Centre of Excellence for Coral Reef Studies, researchers found that organisms that form calcium carbonate skeletons have a mechanism to cope with more acidic environments. "The good news," says Professor Malcolm McCulloch, who led the study, "is that most corals appear to have this internal ability to buffer rising acidity of seawater and still form good, solid skeletons.” Not all corals have this advantage, however. At least one variety—which plays a critical role in reef systems by acting as the "glue" that binds them together—known as coralline algae, lacks the resistance.
Overall, this research shows that the outlook for the world's coral reefs is more complicated than anyone thought. Though the general forecast is still dire, this new knowledge will better help conservationists plan, establish, and manage marine preserves to protect reefs for the future.