"We were amazed that declines in corals were relatively uniform over large areas, despite different areas in the Indo-Pacific having wildly different management practices," co-author Selig said.
The widespread declines may be due to regional or global stressors such as increased sea temperatures, which trigger coral bleaching, she said. (Related: "Global Warming Has Devastating Effect on Coral Reefs, Study Shows" [May 16, 2006].)
"It is also possible that different, smaller-scale threats, [such as] destructive fishing and sedimentation, are causing equivalent declines across the whole region," Bruno added.
The study appeared in this week's online journal PLoS ONE.
Rain Forests of the Sea
Coral reefs are often considered to be the rain forests of the sea due to their high levels of biodiversity, and also because both ecosystems face severe threats from human activities.
"Not only are we losing coral reefs much faster than rain forests, but the [reefs] are already quite rare to begin with," Selig said.
A major obstacle to preventing ongoing reef loss is the difficulty in finding data.
The researchers found it very difficult to track down reef surveys from the 1970s and early 1980s, when scuba diving was still taking off.
"Compared to ecosystems on land, we have had a far shorter time studying coral reefs," Selig said.
The "Blue Water" Problem
Another problem is public perception of the oceans.
"Most people don't dive," Selig said, "and when they see beautiful blue tropical waters, they assume that everything is probably all right."
Selig refers to this as the problem of "blue water."
"It's so hard to persuade people to care when everything still looks so lovely from the surface."
Nancy Knowlton, a marine biology professor at the Scripps Institution of Oceanography in La Jolla, California, said research is a wake-up call.
It also shows that the situation for coral reefs is extremely serious in the Indo-Pacific, and not just the Caribbean, she said.
Scientists have extensively documented the destruction of reefs in the Caribbean, which have suffered heavily for decades from human impacts and devastating coral diseases.
"It was assumed that the Caribbean was the worst case scenario," said Knowlton, who was not involved in the study. "But ignorance is not bliss."
Room for Optimism?
Co-author Bruno thinks there is still room for optimism and that reefs have maintained some resilience to threats from humans.
"Despite the general trend of decline, it seems that some reefs can still recover," he said.
Richard Aronson, a senior marine scientist at the Dauphin Island Sea Lab in Alabama, said that saving coral reefs worldwide means addressing local problems and thinking big.
"As a society we absolutely must address regional and global issues," said Aronson, who is also president of the International Society for Reef Studies.
"Among the most urgent global problems are climate change and other effects of greenhouse-gas emissions, such as acidification of the oceans."
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