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Great Barrier Reef Coral Is Becoming More Resilient

New research shows unprecedented back-to-back bleaching events on the Great Barrier Reef has made tougher coral more resilient to stress.

It's being described as an example of "ecological memory", and a "silver lining" for the embattled ecosystem.

Corals on the Great Barrier Reef that survived the 2016 bleaching were found to be much more resistant to a second heatwave the following year, according to researchers from the James Cook University.

"The response of the reef to heat exposure in year two, depended in part on its experience one year earlier," said lead researcher Terry Hughes.

"We can no longer assume that future bleaching events, in say a decade or two, will have the same effect that they have now, because of these changes in physiology in the mix of species," he told the ABC.

The Great Barrier Reef IMAGE: Getty

Bleaching happens when coral effectively gets cooked in the warming water. The change in sea temperature causes the corals to expel tiny photosynthetic algae, draining them of colour.

The good news is, bleached reefs aren't dead reefs.

Corals can recover if water temperature drops and the algae are able to recolonise.

Magical hard coral reef showing signs of minor coral bleaching. IMAGE: Getty

According to the study, the northern part of the Great Barrier Reef was worst hit in 2016 but was bleached much less in 2017, despite similar levels of heat stress.

The central regions copped about the same level of bleaching in both years.

While the southern region, which was the least effected in 2016, showed absolutely no bleaching at all in the second year.

Hughes labelled the finding "surprising".

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While the study suggests coral has toughened up, it's far from immune to coral bleaching.

Scientists are now nervously waiting until next March, when another bleaching event could occur in response to peak summer temperatures.