A deadly new disease is threatening to infect and ruin the world's coral reefs, warns a new study.
Known as grey-patch disease, it alters the community of microbes found on the host coral by forming a film of bacteria which envelops the live coral.
Researchers from the University of Derby and the University of Guam surveyed reefs across the Indian and Pacific Oceans between 2011 and 2018 for signs of the new disease.
Although the scientists found that grey-patch is currently restricted to Micronesia, it was found across 18 different species of coral and nearly 22 per cent of surveyed colonies.
The disease is apparently slow to progress, meaning that some coral tissue was able to grow back over the biofilm.
Study lead author Dr Michael Sweet said: "Upon analysis of the coral samples, multiple microorganisms appeared to be involved in degrading the corals' defences causing the onset of the disease.
"This supports recent findings that suggest we should shift from the one-pathogen-one-disease model, to exploring the importance of multiple pathogens in any given disease."
Each coral's microbiome - the distinct community of microbes hosted by corals - was significantly affected by the infection.
However, when comparing microbiomes across different corals, those with the disease were found to be more similar with regard to their community profiles.
Dr Sweet added: "Our analysis highlighted the clustering of specific microbes. Identifying these clusters may be a useful tool for assessing coral health at any given time.
"We found that in healthy coral tissue, 'infection clusters' were seen in advance of physical signs of the disease. We were also able to identify 'survival clusters' in diseased tissue.
"These appeared to be essential to the health of the coral and these good bacteria appeared to compete against the disease-causing microbes, allowing certain corals to recover and survive.
"We are now interested in exploring if these microbes may be cultured and used as probiotics to assist corals in overcoming the impacts of climate change."
The findings were published in the journal Microbiome.
