Corals attract helpful bacteria that help them to fight disease
▶ Discovery at NYUAD may be used to give early warning of reefs in bad health
Research at New York University Abu Dhabi found that corals produce chemicals to attract helpful bacteria – a discovery that could help efforts to protect them and recognise warning signs of disease.
The study comes at a time when corals around the world are facing increased threats from climate change, pollution and environmental damage.
Led by Dr Shady Amin, an assistant professor of biology at NYUAD, the Abu Dhabi-based fieldwork is thought to be the first study to show how corals create a favourable microbiome – a mini ecosystem of micro-organisms – around them.
Scientists already know that corals have a symbiotic relationship with algae. But how they surround themselves with a unique community of other micro-organisms, especially 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,” he said.
To test whether corals were producing chemicals to attract, or repel, particular bacteria, the researchers collected seawater samples 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 a 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 coral probably signal to certain bacteria that this is the place to be, to colonise the surface,” Dr Amin said.
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 showed there are particular molecules associated with disease and the hope is that these could be used as early indicators of illness in corals.
“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, Dr Amin said, 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 temperature,” he said.
The researchers are now analysing tissue samples to better understand the way corals may be producing chemicals.