 A Product of the SEBS and NJAES Office of Public Outreach and Communication  Images of healthy (left) and SCTLD-diseased (right) Montastrea cavernosa corals in waters near the Dominican Republic. Images by divers at the Marine Innovation Center, Punta Cana. Photo credit: Debashish Bhattacharya
A mysterious disease has been quietly destroying coral reefs across the Caribbean for over a decade. Stony coral tissue loss disease, or SCTLD, causes coral tissue to simply fall away, killing entire colonies — and no one has been able to pinpoint exactly what causes it. Now, new research is offering some of the clearest clues yet.
Debashish Bhattacharya, Distinguished Professor in the Department of Biochemistry and Microbiology and affiliate of the Rutgers Climate and Energy Institute, supervised the work that was led by graduate student Shrinivas Nandi in his lab and published in ISME Communications. The research examined the microscopic communities — bacteria, viruses, and other microbes — living inside diseased and healthy corals collected from reefs in the Dominican Republic.
The authors found that when corals get SCTLD, the rich and diverse community of microbes that normally lives inside a healthy coral essentially collapses. In its place, harmful bacteria move in and take over. The study also found strong evidence that viruses may be setting this collapse in motion — disrupting the healthy microbiome and opening the door for dangerous bacteria to thrive. This phenomenon is referred to as dysbiosis.
Five specific viruses were found in significantly higher amounts in diseased corals. Strikingly, the same viruses turned up in SCTLD-affected corals from Florida — over 1,000 miles away — suggesting these viruses are consistently linked to the disease across the Caribbean.
Perhaps the most surprising finding was the discovery of two coral colonies that appeared healthy for at least nine months after sampling, yet contained the same viruses found in sick corals. These “asymptomatic” corals had a different bacterial community than diseased ones, hinting that the right mix of microbes or a resistant coral genotype might protect some colonies from getting sick — even when the virus is present.
“Finding corals that appear resistant to this disease is genuinely exciting. It opens the door to the possibility of identifying beneficial microbial communities (natural probiotics) or resistant genotypes that could be used for coral conservation. Given how rapidly SCTLD is spreading across the Caribbean, there is also a need for SCTLD diagnostic tools to screen wild and nursery populations for signs of the disease (virus DNA), an area we are actively working on with our partners in the region,” said Bhattacharya.
As climate change warms and stresses the ocean, coral diseases like SCTLD are expected to become more severe and widespread. These findings offer a potential path forward: by identifying the molecular “fingerprints” of disease — and resistance — scientists may be able to develop early warning tools to flag at-risk reefs and guide targeted conservation efforts before it’s too late.
You can read the full study here.
This article was written with assistance from Artificial Intelligence, was reviewed and edited by Oliver Stringham, and was reviewed and editted by Debashish Bhattacharya, senior author of the study.
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