AAP – October 11, 2013
A WORLD-FIRST Australian study has shown tropical corals can fight back against acidifying oceans caused by carbon dioxide emissions.
Scientists say coral reefs are still under serious threat from coral bleaching due to higher sea-surface temperatures and direct human impacts.
But research by the ARC Centre of Excellence for Coral Reef Studies suggests many corals have the ability to largely offset the effects of increasingly acidic oceans.
University of Western Australia Professor Malcolm McCulloch’s team has shown many coral species are able to reduce the acidity, or pH level, of the seawater they take in.
By adapting the chemistry of the seawater, they can more efficiently extract what they need from it for the skeleton-building process.
“This process of buffering seawater – raising its pH – only takes up a relatively small amount of energy and provides significant benefits to the coral,” Prof McCulloch says.
But he warns corals still face serious risks from climate change.
“In terms of ocean acidification, our research model showed predictable but generally small effects on the future ability of tropical corals to build skeletons, something that is not only critical for their individual growth and survival but for the health of coral reefs in general,” he says.
“But the rapid and often abrupt increases in ocean temperatures that are expected over the next 100 to 200 years are also likely to cause serious episodes of coral bleaching and when this happens the bleached corals are unable to function properly.”
Corals in this state will probably not be able to modify the chemistry of seawater they take in.
Prof McCulloch says other skeleton-building marine species, such as some sponges and giant clams, cannot modify the acidity of the seawater they use to extract building material.
These species may be even more vulnerable to the effects of climate change, he says.
The research team is continuing to examine a wide range of marine species that build skeletons in order to better understand their ability to modify their internal seawater chemistry.