White Pox

It's a two-way street


Most divers know coral are threatened worldwide. In 1996, a new threat was identified in the Florida Keys: white pox. This disease, which can kill four inches of coral every day, is caused by Serratia marcescens, a species of bacteria that causes meningitis and pneumonia in humans. Although this bacterium is known to inhabit sewage, the origin of the bacterial populations responsible for the coral death was unclear at first. Some argued it had been introduced to the affected areas by wild mammals or birds, but research soon confirmed it came from human sources.

It is the first known case of a human disease infecting a marine invertebrate. James Porter of the University of Georgia has referred to this as a "rare and unusual evolutionary triple jump." To infect coral, the bacteria had to move from humans to lower invertebrates, from the terrestrial environment to the marine environment and from the anaerobic conditions of human stomachs to the completely oxygenated conditions on the reef. How the bacteria underwent this evolution is not completely understood, but fortunately, conserving the coral does not depend on such understanding. Better wastewater management is the key to protecting coral from white pox.

Recently, citizens of the Florida Keys voted to invest tax dollars in improved wastewater treatment infrastructure. While white pox was unknown at the time the Keys transitioned from septic tanks to sewers, residents knew their coral reefs were an asset they had to preserve. Health warnings due to pollution are now extremely rare, due to the improvements in wastewater management. Thanks to these efforts, elkhorn coral, which are key components of local reef structures, have stopped dying off in areas where the improvements have been made, and, in fact, are making a comeback.

In other coastal areas with fewer resources, such contamination of the marine environment may go unchecked. As the populations of island nations and coastal regions grow, input of human contaminants may become increasingly problematic. Widespread lack of wastewater treatment throughout the Caribbean is a potential hazard to reefs and their inhabitants.
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