Florida Coral Reefs In Sharp Decline

The study, part of the Environmental Protection Agency's Coral Reef Monitoring Program, found that the incidence of the 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.

"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," said Dr. James W. Porter, an ecologist from the University of Georgia 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 does not believe that 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 that 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," said 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 crucial to the area's economic stability.

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," said Porter.

Instead, the team has casually divided the diseases into "stompers" and "jumpers." Porter said "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.

Reasons for the sudden decline in the coral reefs are many, but none has yet been proved. One idea proposed by Dr. 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, but there are also those who propose more indirect methods of infection. By these theories, poor water quality may be influencing the resistance of the corals to disease.

The problem is that no one knows if lower invertebrates even have an immune system, much less how certain infections affect them.

"The entire situation is really puzzling and alarming," said Porter. "If these diseases increase in the next two years as fast they have is the past year, coral mortality rates could begin to threaten the entire reef ecosystem."