Divers may be loving Florida's coral reefs a little too much. A recent study reveals that coral reefs off the continental United States suffer from a "stress-related syndrome," and divers may share much of the blame.
"When you touch a coral, you remove the mucous coating which protects it from disease and infection," said Helen Talge, a graduate student at the University of South Florida who conducted the study. "We're afraid that diver contact could be killing them."
For years, marine biologists have known that the brittle, living colonies of coral polyps were easily damaged by anchors and boat groundings. But Talge's study is the first scientific attempt to link recreational divers to the reefs' decline.
"A simple touch or scratch can trigger what is called a "Shut Down Reaction' in corals that can kill a coral head in a matter of hours," Talge, 55, wrote in the report she presented this month to the American Academy of Underwater Sciences. "This reaction is very contagious and can pass to other corals, possibly killing an entire reef."
Talge's findings are based on a three-month study at several locations in the Florida Keys, primarily Looe Key National Marine Sanctuary, a popular 5-square mile reef system about three miles south of Big Pine Key.
More than 50,000 people visited the Sanctuary in 1989, a 300 percent increase over the previous five years.
Talge spent more than 60 hours underwater observing the diving habits of 206 scuba divers. Each time a diver grabbed or bumped the coral, she described the incident on a prepared slate. Additional information included the diver's experience, the duration of the dive and any briefings given by the captain or dive master.
The study found that scuba divers were more likely to damage the coral than snorkelers. Men were more likely to touch the reef than women. And divers with gloves had more contact than divers without.
From her observations and follow-up interviews, Talge compiled a profile of the "most abusive diver." He is an experienced diver, 25 to 35, and lives on the West Coast of Florida, she said.
The average diver touched the reef seven times per half-hour dive; the average snorkeler touched it once. But the snorkelers' contacts often were more serious because they had a tendency to stand on the corals.
Another problem cited in Talge's report is the effect divers have on water quality. On a given day, 300 divers may explore a small section of reef.
Because waters around reefs generally lack nutrients, "300 divers urinating in the water could increase nitrogen concentration of the water by 25 to 50 percent," hindering the reef's growth and stimulating harmful algae.
"This problem could be reduced by educating divers and concession operators that metabolic wastes should be disposed of in sewage treatment systems," the report stated.
Talge's study also found that divers often had a problem controlling buoyancy. Because they wore too much weight, they often banged into reefs.
"It's just a question of training," said Brian Grindey, a scuba instructor with Mac's Sports, a Clearwater dive shop. "If you give students enough time in the pool, that shouldn't happen."
Better diver education and training is the key to protecting the reefs, said Mark Robertson of the Nature Conservancy's Key West office, the organization that commissioned Talge's study.
"This is the first time we have had any quantitative information on the issue," he said. "We'll use the information to help educate visitors to the reef."
Harold Hudson, a reef biologist who works in both the Looe Key and Key Largo marine sanctuaries, thinks the problem could be worse than Talge documented.
"Her results are certainly real, but the data is probably conservative," Hudson said. "If these transgressions were occurring randomly, the system could stand it. But it is a chronic problem.
"Day after day, year after year, the coral can't handle this kind of stress," he said. "You might say we are loving it to death."