GREEN

Great Barrier Reef Coral Types Found To Be Immune To Bleaching

The answer is in its genes.

16/05/2016 12:19 PM AEST | Updated 15/07/2016 12:52 PM AEST
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University of Melbourne
Some coral has been shown to be resistant to bleaching.

As the Great Barrier Reef begins the slow recovery process from the worst coral bleaching event in history, a new genetic discovery provides hope.

In a laboratory tank at the Australian Institute of Marine Science, a simulated coral bleaching event wiped out much of the coral samples that had been carefully selected from the reef, but some survived.

University of Melbourne professor Madeleine Van Oppen said these survivors had specific genes associated with a higher tolerance to environmental stress.

What is coral bleaching?

Coral hosts tiny algae in its tissues called zooxanthellae that produce its food as well as its colour.

When waters become too hot or cold or polluted, the coral becomes stressed and its metabolism and reproductive systems break down.

At this point, it cannot process the oxygen created by the zooxanthellae, so it expels them.

If the temperature/water quality returns to normal, these tiny creatures can re-enter the tissues, or if most but not all algae have been expelled, the remaining few can keep the coral alive.

If conditions remain extreme, the coral dies.

In other words, these genetic markers will point researchers that point towards creating coral immune to bleaching.

The research, published in journal Science Advances, also found one individual genetic marker that accounted for 30 percent of the variation observed in the colony's ability to deal with the dangerous free radicals produced by algae in stress.

Van Oppen said this resistant coral could be seeded throughout the Great Barrier Reef.

University of Melbourne
Coral at the Australian Institute of Marine Science that is resistant to bleaching.
"Absolutely we could find corals that have tolerant copies of the gene and we could boost their abundance by crossing parents that have those genetic characteristics then saddling offspring onto reefs."

Van Oppen said the need to find ways of protecting the reef was becoming more urgent, and genetics could be the place to look.

"Coral genomics is lagging behind other organisms," Van Oppen said.

"They're such non-standard organisms and a relatively small community works on them compared other areas like human genomes.

Reinhard Dirscherl
Bleached corals are slowly recovering in coral reefs around the Pacific.

"Our knowledge is rapidly increasing though, and these genomic tools are helping us understand how to build resilience in our reefs."

Van Oppen said the next step of the research was to survey the 7 percent of the Great Barrier Reef that wasn't bleached to determine whether they have the same tolerant genes.

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