Caribbean coral reefs are healthier than expected, says study

MIAMI – Coral reefs in deeper waters of the Caribbean, although very damaged in some areas, are significantly healthier than previously thought, according to a new comprehensive study that inspected reefs about 35 feet
(10.5 meters) deep with scuba-diving teams.
The three-year survey of 20 reefs in the western Atlantic found that reefs in waters 20 feet to 65 feet (6 meters to 19.5 meters) deep had an average of 26 percent living coral cover.
Although the results cannot be directly compared, previous studies of Caribbean reefs in shallow and deep water have found as little as 15 percent coral cover, said Robert Ginsburg, a professor of marine geology and geophysics at the University of Miami.
The new, $500,000 study is the first regional survey that focused on reefs in deeper waters and used the same methodology for measuring the coral cover on each reef. International teams of five to 10 trained scuba-diving scientists measured the coral cover on each reef.
“There were no data done in the same way,” Ginsburg said of earlier looks at reefs. “That’s really our contribution, to have done all of the surveys in the same method.”
The results were published in the July edition of the Smithsonian journal Atoll Research Bulletin, which is just being distributed, Ginsburg said. The report includes the initial findings of scientists from the University of Miami’s Rosenstiel School of Marine and Atmospheric Science and The Ocean Research and Education Foundation, who are creating a database of Caribbean coral reefs.
Ginsburg said scientists have regularly measured the condition of some damaged reefs, which he compared to intensive care. But Ginsburg said his project is more like a physical examination, to establish the conditions of reefs.
The study found that the healthiest coral reefs were far from land or next to small populations. Among the healthiest reefs were those around the Flower Gardens near Texas, the Windward Netherlands Antilles east of Puerto Rico, and Bonaire and Los Roques islands just north of South America. He said the healthy reefs likely benefited from favorable water quality, isolation from land, and isolation from people.
But “the reefs that were not as healthy or not as vigorous as those are scattered all over the place,” Ginsburg said. The most damaged reefs included two near populated areas of the Bahamas – off Andros Island and a site near Hope Town, Abaco – and one remote from any populated area, a small reef off Costa Rica.
The damaged reefs suffered from a combination of problems, including disease, overfishing, and other human damage and weakening from the warmer waters of El Niño, he said.