Reef Scientists Warn of Unprecedented Destruction

WASHINGTON, DC, August 15, 2003 (ENS) - "In the next 50 years, coral reef ecosystems will experience environmental changes greater than any they have faced in the past half million years," says evolutionary ecologist Rick Grosberg at the University of California at Davis. His conclusions and those of 16 other reef scientists published in today's issue of the journal "Science" show the downward spiral started when people first began killing off large reef fish, turtles, seals and other top predators - thousands of years ago in some parts of the world and just 100 years ago in others.

"The link between increased greenhouse gases, climate change and regional scale bleaching of corals, considered dubious by many reef researchers only 10 to 20 years ago, is now incontrovertible," the report says.

The experts, led by James Cook University's Professor Terry Hughes, conclude that the coral reef management strategies of today must change if they are to make a real difference. "Existing approaches to protecting reefs must undergo a radical change in emphasis and a substantial expansion in scope if they are to make a real difference," Hughes said.

Professor Terry Hughes examines coral structures in his lab at James Cook University. (Photo courtesy Centre for Coral Reef Biodiversity)

Greenhouse gas emissions must be reduced, they insist, or else global warming will "undoubtedly" change the nature of reef ecosystems. Scientists are already recording the effects of warmer conditions, such as widespread coral bleaching.

And the authors advise that coral reef management must be coordinated across international and local agencies.

The report, which synthesizes decades of coral reef research, is authored by 17 international researchers from Australia, Europe, and the United States, with an unprecedented breadth of expertise in environmental management, ecology, geology, palaeontology, climatology and economics.

"Coral reefs provide critically important ecosystem goods and services, and, in a human-dominated world, the economic importance of these goods and services will increase. Management of this valuable resource is crucial," Hughes said.

Their findings grew out of an October 2002 forum, "Managing Coral Reefs in the Face of Global Change." Organized by the Centre for Coral Reef Biodiversity at James Cook University in Townsville, Australia, the forum was the first of its kind. The participants produced a road map for reef rescue called The Townsville Declaration.

Corals need clean, clear waters to survive. When stressed by heat, they can lose their symbiotic colored algae, a process called bleaching. (Photo courtesy NASA)

Grosberg says, "Complicating their existing health problems will be the impacts of climate change, such as warmer water, more frequent and more intense hurricanes, and changes in seawater chemistry." The increase of carbon dioxide in the air is changing ocean chemistry, which may cause reefs' limestone skeletons to fracture or dissolve.

"For virtually all species of corals and coral reef fishes, we have no idea what the precise genetic heritage is. We don't know how genetically variable they are or how capable they are of responding to environmental change," Grosberg said. "One thing we can be sure of is that, as we reduce population size and increase the distance between reefs, their ability to respond to change will be diminished."

The scientists examined historical and archaeological records surrounding major reef systems in 14 regions in the Atlantic and Pacific oceans and the Red Sea, including the reefs of the Caribbean and the Great Barrier Reef.

Each scientist handled a different region, with Bjorndal tackling the Bahamas and the Cayman Islands. She said her research led her to more than 400 references for the Bahamas alone, including papers on archaeological findings and colonial fishing catch records.

Dr. Karen Bjorndal focuses her research on the biology of sea turtles. (Photo courtesy University of Florida)

The researchers discovered that all the reefs experienced declines as a result of human activity, although the declines occurred over different periods of time and were more advanced in some places than others.

Regardless of geography, the researchers learned, the declines follow the same pattern. First, people deplete large predators such as sharks and large herbivores, which tend to be both easy to kill or capture and slow to rebuild their populations. Next to go are smaller animals, such as small fishes, followed last by sea grasses, corals and other so-called architectural parts of the coral reefs.

By 1900, decades before the first scuba divers descended to investigate the reefs, decline had already started in more than 80 percent of the reefs worldwide, the scientists found.

Today, in the regions where the process is most advanced, such as Jamaica, the corals are either dead or dying, the fish are tiny, few other organisms such as shellfish exist, and the formerly vibrant reef structure is dull and coated with algae.

The Great Barrier Reef sometimes is said to be largely pristine, but it is actually as much as a third of the way toward ecological extinction, Bjorndal said.

"Reefs won't disappear entirely, but they will change," said Grosberg. "To keep those changing reefs diverse and resilient, we are calling for vigorous international action to manage reefs better and to reduce the rate of global warming."

Dr. Sean Connolly of James Cook University, a co-author of the study, said, "Wealthy countries have an obligation to take the lead in increasing the proportion of reefs that are no-take areas, while simultaneously controlling greenhouse gas emissions."

"Even in affluent countries like the USA and Australia, less than five percent of reefs today are no-take areas, said ecologist and geologist co-author, Professor Jeremy Jackson from the Scripps Institution of Oceanography in the United States, who believes that overfishing and pollution need to be addressed as global issues.

For the first time, Bjorndal said, their research will give reef managers and governments of coral reef countries a benchmark they can use to determine how far their particular reef system has progressed along the ecological "extinction continuum."

Bjorndal observed that, with the exception of the extinct Caribbean monk seal and a handful of other top predators, most reef organisms have been depleted but are not yet extinct, offering some hope for the future.

"If we could step back in with strong management decisions we could restore the ecosystem," she said, "but that's a matter of political will and funding and a lot of other influences that are difficult to predict."