Posted by: reefrescue | April 2, 2012

Herpes virus may contribute to coral reef die-offs

After finding that bacteria from waste water effluent are a major factor in the elkhorn coral die-off in Florida’s coastal waters, researchers are focusing on other pathogens that may be affecting reefs, including viral disease.

“We have found that nutrient increases from pollution can cause increased levels of viral infection, as do warmer water and physical handling,” said Rebecca Vega-Thurber, an assistant professor of microbiology at Oregon State University. “Now we have to determine if those increases in infection cause actual diseases that are killing the coral.”

One of the surprises from recent research was the predominance in corals of herpes viruses – similar but not identical to the herpes virus that can infect humans. Herpes viruses appear to constitute a majority of the viruses found in corals, and one experiment showed that herpes-like viral sequences were produced in coral tissues after acute episodes of stress.

“Coral abundance in the Caribbean Sea has gone down about 80 percent in the past 30-40 years, and about one-third of the corals around the world are threatened with extinction,” Vega-Thurber said.

“We’ve identified 22 kinds of emerging disease that affect corals, but still don’t know the pathogens that cause most of them,” Vega-Thurber said. “Most researchers have looked only at bacteria. But we suspect viruses may play a role in this as well, and it’s important to learn more about what is causing this problem. Corals are the building blocks of the tropical seas.”

It’s not yet certain, researchers say, whether the viruses being found on corals are actually causing diseases.

“Just because you harbor 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.”

Some of the possible causes of coral decline that have been identified so far include global warming that causes coral bleaching, loss of symbiotic algae that help nourish corals, pollution such as sewage runoff, and human-coral interactions.

Read entire article: http://summitcountyvoice.com/2012/04/01/viral-disease-may-contribute-to-coral-reef-die-offs/

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