Jan. 18, 2004 White band disease, which killed about 90 percent of St. John's elkhorn coral colonies in the late 1970s and 1980s, is history, but the species faces a new threat, white pox disease.
However, unlike the white band disease that killed the coral, white pox disease isn't nearly as fatal. Indeed, studies on St. John show that the coral can recover.
"What causes it? That's a good question," marine ecologist Caroline Rogers said.
Rogers, who heads up the U.S. Geological Survey office on St. John, said that there is some evidence from Florida studies that bacteria found in human and animal waste may be the culprit. However, she said there isn't sufficient development at the Hawksnest Bay and Haulover study sites to cause the problem.
"There's no reason to think it's sewage," she said.
Rogers said elkhorn coral is important because it is the primary reef builder in the Caribbean. The reefs form breakwaters that reduce shoreline erosion.
"And elkhorn is an important shelter for fish, octopus and crabs," Rogers said.
Elkhorn coral is so important to the marine environment across the Caribbean that the National Oceanic and Atmospheric Administration is considering adding it to the threatened and endangered species list. Rogers said only one other marine invertebrate the white abalone found in California is on that list.
In addition to white pox disease, elkhorn coral as well as other varieties also fall victim to damage from boat anchors and from fishing line. Rogers said she's found numerous pieces of elkhorn coral tumbling around the ocean floor with fishing line wrapped around it. The fishing line snapped off the pieces.
Rafe Boulon, the V.I. National Park's head of environmental resources, said that the problem comes when people fish from the shore. He said it was inevitable that the coral would get caught in fishing line since the fish live in the reefs.
The Geologic Survey is in its second year of a three-year study of elkhorn coral. Rogers and her research assistant, Erinn Muller, have mapped colonies at 11 locations around St. John, but are focusing their study efforts on the two at Haulover and Hawksnest Bays. Muller said the colonies at Haulover are widely scattered, but those at Hawksnest are numerous and dense.
The study shows that during the late summer and fall, which are the warmest months in the Caribbean, the number of cases of white pox disease increases.
Muller said they evaluate the site monthly. She explained that the project uses a Global Positioning System (GPS) device to keep track of the coral.
Rogers said that when Hurricane Ivan passed to the south of the territory, the waves also caused damage to the elkhorn coral. She said scientists observed pieces snapped off at Yawzi Point and Saltpond, both on St. John's south side, and at Pelican Rock, located near Coral Harbor. Additionally, she said scientists saw a similar problem at Flat Cay, an island off the southwest side of St. Thomas.
She said the elkhorn coral is a good subject to study because it lives primarily in shallow water. This means volunteers can snorkel over the reefs to make evaluations rather than having to don scuba gear for a look at varieties that grow in deeper water.
Rogers said that the project was funded by the Disney Wildlife and Conservation Fund and the Friends of the V.I. National Park. Staff from the park and the University of the Virgin Islands Conservation Data Center assisted with the project.
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