NURP Research Provides Insight into White Plague
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.
Name: John Marr
Tel: (561) 741-0192