Coral breakthrough offers climate hope

CORAL reefs may be much better able to adapt to rising sea temperatures due to climate change than previously thought.

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CORAL reefs may be much better able to adapt to rising sea temperatures due to climate change than previously thought, according to a breakthrough Australian discovery revealed yesterday.

The research undertaken at the Australian Institute of Marine Science (AIMS) and published in the journal Nature Climate Change has overturned previously held assumptions about coral bleaching and which corals may survive in warmer waters.

According to PhD student Emily Howells, the findings demonstrate the potential for corals to adapt is more widespread than previously thought.

Further research is under way to establish the speed at which coral can adapt to rising water temperatures, and whether it will be fast enough to survive the impact of climate change.

"As with all scientific discovery it raises further questions," Ms Howells said. "We hope to have some early results from preliminary experiments later this year."

The latest discovery is considered important because it has radically increases the estimated scope of corals that may survive a changing environment.

Scientists had believed that warm water corals required different organisms -- called "zooxanthellae" -- than those corals found in colder waters.

Zooxanthellae are algal cells that live within the tissue of living coral and provide the coral host with energy; the relationship is crucial for the coral's survival.

Rising ocean temperatures can lead to the loss of zooxanthellae from the coral host, leading to coral bleaching and possibly death.

The former logic was that corals would need a mix of zooxanthellae to enable them to adapt to rising water temperatures. But it has now been demonstrated that a single type of zooxanthellae found across a big range of the Great Barrier Reef exists in both cooler and warmer waters.

"The algae we are working on occurs up and down the Great Barrier Reef and we are finding that even though it is the same type of algae, those in warm locations have adapted to warm water temperatures and those that are in cooler places, over many years, have adapted to cooler temperatures," Ms Howells said.

"We really don't know about their rate of adaptation to temperature change.

"But previously we didn't really know that different populations of the same type did have any different thermal tolerances, so that is a completely new finding."

Madeleine van Oppen, ARC Future Fellow at AIMS, said until now corals associating with the same type of zooxanthellae had been viewed as physiologically similar, irrespective of location.