G.P. Schmahl, of the Florida Keys National Marine Sanctuary, also was involved in the discovery. The disease has no known counterparts on coral reefs. Porter says it is closest to white band disease, although the two diseases show more differences than similarities. White band decimated coral reefs in St. Croix in the early 1990s. Like white band, the new disease prefers to attack a coral called Acropora, specifically Acropora palmata , and both diseases can result in partial or whole-colony mortality.
Diseased colonies appear white, as infected coral tissue dies over the underlying skeleton.
Still, these similarities are no more than superficial, says Porter, and considerable differences between white pox and white band have been seen. The size of the discolored areas ranges from a few centimeters in diameter to large patches some 20 centimeters in diameter. Diseased portions of the colonies are neither bands nor circles but instead irregular blotches distributed across the colony as well as on the blade tip. Initially, the destruction of coral by white pox looks like an attack by the coral-eating snail, Coralliophyla , a natural predator on elkhorn coral. However, says Porter, there are no snails in the vicinity of these diseased coral patches, and close examination reveals that the actual tissue manifestation of white pox differs from snail predation.