UVI researchers find viruses may be cause of coral disease

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ST. THOMAS - A team of scientists at the University of the Virgin Islands is getting attention for their research on the coral disease known as the "white plague."

On the surface, the white plague disease looks similar to bleached coral, but it is far worse.

When colorful, living, coral polyps become stressed by high water temperatures, they expel the symbiotic algae that live within them and provide needed food to the coral. Because the algae is the source of the coral's color, when it leaves, the coral becomes stark white or "bleached."

While coral can survive the bleaching, it becomes vulnerable to disease and predators.

In the summer of 2005, high water temperatures led to a massive coral die-off both in the Virgin Islands and around the world. The territory lost 60 percent of its coral colonies to bleaching and disease.

The disease scientists have found most prevalent after the 2005 bleaching event is a disease called white plague. At the time, very little was known about the disease, including what causes it.

A team led by Marilyn Brandt of UVI's Center for Marine and Environmental Studies, has identified viruses as potential coral pathogens.

"The research suggests that white plague disease is associated with and may be caused by viruses," Brandt said. "This is the first study of its kind that has identified viruses as a potential coral pathogen."

The research also showed the disease was triggered when sand and sediment - stirred up by Hurricane Earl in August 2010 - made contact with living coral tissue.

Tyler Smith of UVI, Rebecca Vega-Thurber of Oregon State University and Oregon State Ph.D. graduate student Nitzan Soffer collaborated on the study.

Brandt said her overall goal is to understand the disease so that it can be better managed, or even prevented.

She first saw coral damaged by white plague while diving in the Cayman Islands in 1999. It became the subject of her scientific research career.

"It's been a topic of my primary research since my undergrad days," she said. "It was devastating to watch your favorite dive site just being destroyed because of this disease that we didn't know anything about."

White plague disease is known to affect more than 30 species of coral. In the 1990s, the disease was originally thought to be associated with a bacterial pathogen, but Brandt said the issue may be more complicated.

"Conflicting results from more recent studies, like ours, suggest that the causal agent may be more complex than originally thought," Brandt said.

Her latest study looked at corals in Brewer's Bay affected by the disease. She found that the disease was capable of spreading among coral colonies.

"Understanding what is occurring on a small scale in a location like Brewer's Bay has high relevance for researchers throughout the Caribbean," Smith said.

In addition to his UVI research, he serves as research coordinator for the Territorial Coral Reef Monitoring Program, which was established by the Department of Planning and Natural Resources and funded by the National Oceanic and Atmospheric Administration's Coral Reef Conservation Program.

Coral reefs provide valuable and vital ecosystem services, serving as a source of food for millions, protecting coastlines from storms and erosion, providing habitat, spawning and nursery grounds for economically important fish species, and providing jobs and income to local economies from fishing to recreation and tourism, according to the NOAA Coral Reef Conservation Program.

All Virgin Islanders should be as concerned as she is about the plight of coral, Brandt said.

"Corals provide the habitat. They are the ecosystem engineers for all the coral reefs which produce the things we like - like fish and conch and lobster. If the corals die and crumble away you don't have that," she said. "Without the corals which are the fundamental builders of that system we would lose much." 

The local research project was supported by the National Science Foundation and the NSF-supported Virgin Islands Experimental Program to Stimulate Competitive Research, known as VI-EPSCoR.

Brandt and UVI were also awarded a grant from NOAA's Coral Reef Conservation Program to continue studies of white plague and other important coral diseases in the territory.

Brandt's research has been published in two scientific journals, PLOS ONE in February, and the International Society for Microbial Ecology Journal in September. It also drew attention from the NBC News-Science website in October.

- Contact reporter Aldeth Lewin at 714-9111 or email alewin@dailynews.vi.

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