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NURP Research Provides Insight into White Plague Disease
This story entered on 7th Mar, 2005 05:51:50 AM PST

Diseases of corals have increased dramatically over the last decade, leading to unprecedented decreases in live coral cover. In the Caribbean, the disease known as white plague (WP) is known to affect 33 reef building species of coral, often at epidemic proportions. Affected species include the keeled star coral (M. faviolata) and the knobby star coral (M. annularis). WP is caused by the bacterial pathogen Aurantimonas coralicida. The disease is characterized by a sharp line between apparently healthy coral tissue and freshly exposed coral skeleton, where the pathogen has killed and possibly consumed the overlying coral tissue. In the Type II variant of WP, tissue loss progresses at up to 2 cm per day, killing small colonies of corals in 24 to 48 hours.

NURP is currently supporting research to understand WP in relation to the bacterial communities that occur naturally in healthy coral reef ecosystems. Researchers aim to characterize the bacteria associated with diseased versus healthy coral tissues. Recent findings indicate that bacterial community composition on healthy coral differs substantially from the composition of bacteria present at the disease margin. An understanding of WP at the microbial level is essential to combating this disease, which not only destroys isolated corals, but has the potential to impact the function and productivity of entire coral reef ecosystems.

Led by Robert B. Jonas of George Mason University, researchers collected coral samples from two distant reef sites, St Croix in the US Virgin Islands and Lee Stocking Island in The Bahamas. They obtained multiple cores of three types of coral tissue; 1) apparently healthy coral colonies; 2) areas on corals with plague; and 3) areas along the disease margin. Samples were analyzed with a molecular approach known as amplicon length heterogeneity, where portions of the coral DNA were duplicated in order to create DNA fingerprints. These fingerprints were then compared to determine the type and degree of bacteria in each of the tissue samples. Having established that bacterial community composition on healthy coral and diseased coral is very different, researchers are now investigating range of variability in microbial community composition within a single coral colony, among corals of the same species within a reef site and between two reefs located hundreds of miles apart.

NURP supported this research through the Caribbean Marine Research Center, NOAA's Undersea Research Center for the Caribbean.

Contact information
Name: John Marr
Tel: (561) 741-0192

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Updated: August 26, 2005