Photo: UGA ecologist James Porter is a principal project investigator in the coral reef monitoring program. Photo by Rick O'Quinn. 
By Phil Williams
Photo: UGA ecologist James Porter is a principal project investigator in the coral reef monitoring program. Photo by Rick O'Quinn.
New information gathered last summer shows that diseases on Florida's coral reefs have dramatically increased, with potential long-term consequences for the coral-reef ecosystem.
The study, part of the Environmental Protection Agency's Coral Reef Monitoring Program, found that the incidence of disease has increased by 276 percent from 1996 to 1997. Perhaps even more ominous, the number of coral species with diseases has increased 211 percent in the same time period.
New diseases discovered
"In the late 1980s, we were following five or six diseases on Florida's coral reefs, but we now know of 13, some of which are entirely new to science," says James W. Porter, the UGA ecologist who is a principal investigator for the project. "We are really stunned at what we found. There is no precedent for what has happened in the past year."
Porter reported the team's findings last week at the Smithsonian Institution in Washington, D.C. The presentation was sponsored by the Ecological Society of America, the National Oceanic and Atmospheric Administration, the Smithsonian and the EPA. Other members of the team investigating the coral reefs are Phil Dustan of the College of Charleston and Walt Jaap of the Florida Marine Research Institute in St. Petersburg, Fla.
Final data 'shocking'
The new information comes from 160 monitoring stations that range from Key West to Key Largo. Porter says that the widespread and increasing damage to the reefs was obvious to the naked eye but that final data shocked even the scientists. In 1996, 25 monitoring stations showed signs of disease, while in 1997 the number rose to 94 stations. In addition, nine of 44 species showed disease in 1996, but a startling 28 species showed diseases a year later.
Disease evolution not recent
Porter does not believe the newly discovered coral diseases have recently evolved. Instead, they may have existed in the oceans for some time, but the coral may not have been susceptible to them. While there is no evidence coral have anything analogous to a mammalian immune system, some change in the coral ecosystem has apparently made them susceptible to a wide range of diseases.
"On one reef near Key West, some 80 percent of the Elkhorn coral were killed between 1994 and 1997," says Porter. "This is of great concern, since Elkhorn coral is the primary frame builder of the reef."
The problem extends far beyond the damage to the coral itself. While coral is an animal related to the sea anemone, it carries in its tissues a symbiotic algae that allows the corals to produce more oxygen than they consume.
This productivity is crucial to the overall health of the coral reefs, which support fishes and sea life on which the area's economic stability depends.
While widespread damage is obvious, the scientists are stymied in understanding much about the 13 diseases, having discovered the origins of only three of those coral diseases. Early in the study, they considered that human interference such as chemical dumping might have caused the problems, but that theory has largely been discredited. In fact, the team has shown that the diseases can be transmitted from coral to coral simply by touching an uninfected coral with a diseased one.
"We are beginning to identify the disease species, but most of them are without proper scientific names," says Porter.
Instead, the team has casually divided the diseases into "stompers" and "jumpers." Porter says "stompers" are diseases that infect fewer reefs but cause extremely high mortality. "Jumpers" are diseases that cause low-level infections but which move from area to area very rapidly.
New concern: diseased fish
The researchers also discovered last summer a disturbing new concern--diseased fishes swimming on the reefs. Porter, who has been diving in the Florida reefs and studying them for many years, says that the etiology of these diseases in the area is unknown. Some fish are showing red spots on their undersides that could be related to fish-disease outbreaks seen earlier in North Carolina estuaries.
Many reasons are offered for the sudden decline in the coral reefs, but none has yet been proved. One idea proposed by Drew Harwell of Cornell University is that the fungus Aspergillus is being transferred by runoff from the land into Florida Bay. This is a method of direct infection; others suggest more indirect methods of infection. By these theories, poor water quality may be influencing the resistance of the corals to disease.
No one knows if lower invertebrates even have an immune system, much less how certain infections affect them.
"The entire situation is puzzling and alarming," says Porter. "If these diseases increase in the next two years as fast they have in the past year, coral mortality rates could begin to threaten the entire reef ecosystem."
