A CORAL growing on the Great Barrier Reef has been found to self-regulate itself against one of the more harmful effects of climate change.

Australian researchers have detailed, for the first time, how a species of coral has developed a high degree of resilience to ocean acidification.

The team, from the University of Western Australia, the University of Queensland, and the ARC Centre of Excellence for Coral Reef Studies, conducted experiments on the branching coral Porites cylindrica, at Heron Island.

They found the species has a reservoir of calcifying fluid which maintains a constant pH (acidity) level, regardless of the pH level in the surrounding waters.

Over a six-month period from mid-winter to early summer, the coral maintained its pH at near-constant elevated levels, independent of changes in the environment, such as temperature.

Lead author of the study, University of WA researcher Lucy Georgiou, said the research suggested corals were tougher than originally thought, when it came to withstanding ocean acidification.

Ocean acidification is caused by rising carbon dioxide and is one of the greatest long-term challenges facing the survival of reefs and coral.

“We know corals have an internal ability to regulate their internal pH relative to that of the seawater they’re living in, but we didn’t know they were able to do it at this level,’’ Ms Georgiou said.

“It seems regardless of whether the pH is relatively low or high, they can still maintain their own pH at a level which they are comfortable with, to keep calcifying and grow, and keep doing what they need to do.”

The researchers studied the colony in its natural environment using an innovative free ocean carbon enrichment technique to simulate the impact of ocean acidification.

While the findings are positive, it is not yet known if the adaptation is species-specific and limited to colonies where there is a high fluctuation of ocean pH levels.

“We think it is most likely only typical to coral from reefs such as Heron Island Lagoon where temperature and pH fluctuations vary greatly,” Ms Georgiou said.