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Abu Dhabi, UAESunday 18 November 2018

NYUAD research could help safeguard climate change-damaged corals from disease 

Scientists found that corals produce chemicals to attract helpful bacteria - a discovery that could help researchers recognise the warning signs of disease

NYUAD researchers have discovered that corals use chemicals to attract and repel bacteria that are either helpful or harmful to them. Courtesy Dr Emily Howells 
NYUAD researchers have discovered that corals use chemicals to attract and repel bacteria that are either helpful or harmful to them. Courtesy Dr Emily Howells 

A research at New York University Abu Dhabi has found that corals produce chemicals to attract helpful bacteria — a discovery that could assist efforts to protect them and recognise warning signs of diseases.

The study comes at a time when corals around the world are facing increasing threats from climate change, pollution and environmental damage.

Led by Dr Shady Amin, an assistant professor of biology at NYUAD, the study is thought to be the first to demonstrate how corals create a favourable microbiome – a mini ecosystem of microorganisms - around themselves.

Scientists already know that corals have a symbiotic relationship with algae. But how they surround themselves with a unique community of other microorganisms, in particular beneficial bacteria that help them resist disease, is poorly understood.

“We thought there must be some cue that corals produce to attract these microbes and to maintain them,” Dr Amin said.

To test whether corals were producing chemicals to attract, or repel, particular bacteria, the researchers collected samples of seawater at various distances from 18 corals.

Their results were published this week in the journal Communications Biology. Their hypothesis is that corals produce attractants, which act as food source for beneficial bacteria and repellents that can be poisonous to other types of bacteria. They also generate signalling molecules.

“My idea is that probably coral signal to certain bacteria that this is the place to be, to colonise the surface,” said Dr Amin.

Some of the samples were collected from healthy coral, while others came from corals suffering from a condition called white syndrome, which kills the coral and leaves only the white skeleton behind.

The analysis indicated there are particular molecules associated with disease and the hope is that these could be used as early indicators of illness in corals.

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“If we see these biomarkers, we can say this coral colony is likely to get diseases. If that's the case, maybe we can come up with some way to mitigate that or monitor it more closely, or assess how widespread the disease would be,” he said.

Temperature is thought to be a factor in white syndrome, said Dr Amin, possibly because pathogens that contribute to the disease are more active in warmer water.

“And maybe the coral is also stressed because of the high heat,” he said.

The researchers are now analysing tissue samples to better understand the way corals may be producing chemicals.

They will also take water samples from corals outside the Arabian Gulf, possibly in the Great Barrier Reef near Australia next year, to see if the same pattern is seen.