A glimmer of hope for corals as baby reef-builders cope with acidifying oceans

While the threat of coral bleaching as a result of climate change poses a serious risk to the future of coral reefs world wide, new research has found that some baby corals may be able to cope with the negative effects of ocean acidification.

Ocean acidification, which is a direct consequence of increased atmospheric carbon dioxide levels, is expected to have a deleterious effect on many marine species over the next century.

An international team examining the impact of ocean acidification on coral has found that a key reef-building coral can, over a relatively short period of time, acclimate to a doubling of atmospheric carbon dioxide levels.

“Our aim was to explore the effect of a more acidic ocean on every gene in the coral genome,” says study lead author Dr Aurelie Moya, a molecular ecologist with the ARC Centre of Excellence for Coral Reef Studies at James Cook University.

The researchers exposed baby corals from the Great Barrier Reef to acidified seawater for varying lengths of time and investigated how they responded at a molecular level.

“We found that, whereas 3 days of exposure to high CO₂ disrupts formation of the coral skeleton, within nine days the baby corals had re-adjusted their gene expression to pre-exposure levels. Longer exposure seems to be less detrimental to coral health than we had assumed based on shorter-term studies,” Dr Aurelie Moya says.

“These findings suggest that baby corals have the capacity to acclimate to elevated carbon dioxide.”

“We saw that within a few days juvenile coral adapted to CO₂levels double those experienced today with no obvious disruption to its life processes,” says study co-author, Professor David Miller, who leads the molecular biology group in the Coral CoE.

Professor Miller says the findings are particularly significant as they centred on staghorn coral.

“Staghorn corals are the key reef-building corals throughout the Pacific and Indian oceans. These are traditionally considered to have poor stress tolerance. So this work provides a glimmer of hope that coral reefs can attenuate the effects of ocean acidification.”

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