A diver swims past a healthy colony of Caribbean elkhorn coral.
Credits: REUTERS/James W. Porter
The scientists at Oregon State University say coral abundance has decreased about 80% in the Caribbean Sea in the past 30-40 years.
And they think viruses, in particular a strain of herpes that affects the marine animal colonies, could be to blame.
"We've identified 22 kinds of emerging disease that affect corals, but still don't know the pathogens that cause most of them," assistant professor Rebecca Vega-Thurber said, noting most researchers looked at bacteria, but haven't considered viruses.
"We were shocked to find that so many coral viruses were in the herpes family," Vega-Thurber said. "But corals are one of the oldest animal life forms, evolving around 500 million years ago, and herpes is a very old family of viruses that can infect almost every kind of animal. Herpes and coral may have evolved together."
The researchers said it's not certain if herpes or other viruses are causing the diseases.
"Just because you harbour a virus doesn't mean you are getting sick from it," Vega-Thurber said. "This is part of what we have to pin down with further research."