Mysterious Diseases Strike Reefs
WASHINGTON, D.C.--Corals in the Florida Keys and throughout the Caribbean are getting sick faster than ever, according to the latest field results from an extensive monitoring project. And several of the coral diseases have never before been seen by scientists, according to marine ecologist James Porter of the University of Georgia, Athens, who spoke today at the Smithsonian Institution's National Museum of American History. Porter warned that if corals continue to die, he sees "the possibility of disruption of ecosystem function"--with far-ranging effects on other organisms.
As part of the Coral Reef Monitoring Program sponsored by the Environmental Protection Agency, Porter and colleagues in 1995 staked out 160 monitoring stations, each 2 by 20 meters, extending from Key Largo in the north to Key West, 160 km to the south. When Porter returned to the sites last year, he found several diseases in a small area of the Keys, and a new affliction, "rapid wasting disease," in the lower Caribbean. Now, after a summer survey of the sites, it appears that there are more diseases than ever, and that they are widespread throughout the Keys.
Between 1996 and 1997, Porter says, the number of stations with sick corals rose from 25 to 94. Of 44 species being monitored, the number afflicted rose from nine to 28. Three of the 13 diseases are "entirely new to science," says Porter. One puffs up brain coral, while another, called "red stripe," mows tissue off the coral skeleton in a brilliant red line.
Some scientists speculate that sewage and pesticides as well as light deprivation from turbidity are stressing corals, making them more susceptible to existing pathogens. Furthermore, at least one nonmarine organism has already been implicated: aspergillus, a soil fungus that afflicts soft corals known as sea fans. Garriet Smith, a marine microbial ecologist at the University of South Carolina, Aiken, says he suspects that the aspergillus arrives as atmospheric fallout, from winds bearing sands of the Sahara.
Florida officials are concerned about the apparent increase in disease, says Lauri MacLaughlin, a resource management specialist at the Florida Keys National Marine Sanctuary. But because the evidence is only from the past couple of years, they are cautious about the implications--"We're so unsure right now what's going on. We're just trying to get a handle on it," she says.