By Stephen Leahy

FORT LAUDERDALE, U.S., July 12 2008 (IPS)

The rapid decline of coral reefs around the world offers a potent warning that entire ecosystems can collapse due to human activities, although there is hope for reefs if immediate action is taken, coral experts agreed at the conclusion of a five-day international meeting Friday.

“Reefs are in serious trouble, but don’t write them off,” Terry Hughes, a marine ecologist at Australia’s James Cook University told 3,000 scientists, conservationists and policy makers attending at the 11th International Coral Reef Symposium (ICRS) in Fort Lauderdale, Florida.

“We can save reefs if we take immediate action,” Hughes said.

More than 20 percent of the world’s reefs have died, and large areas are failing due to a combination of climate change, overfishing, pollution and sea level rise. Most of the fabulous corals that attract tourists to the Caribbean are gone and half of remaining reefs in the U.S. are in serious decline.

[Update 08/10 – Here’s a list of Stephen Leahy’s latest articles on corals Coral Reefs and Acid Oceans Series]

“We may be facing ocean deserts in the future,” said Guillermo Dias-Pulido of Australia’s University of Queensland.

In 1998, a massive coral bleaching due to warm ocean temperatures linked to global warming killed 95 percent of reefs in large parts of the Indian ocean, in 2002 60 percent of the Australia’s Great Barrier Reef bleached, in 2005 it was the Caribbean that suffered a 50 to 90 percent loss because water temperatures were too high for too long, reported David Souter, coordinator of the Global Coral Reef Monitoring Network located at the Australian Institute of Marine Science.

And those corals that don’t die outright are often afflicted by disease in the following years, Souter told the symposium.

“Corals in American Samoa are bleaching every summer and are very close to death,” says Douglas Fenner, a biologist at Marine and Wildlife Resources, American Samoa.

The reefs he is studying are in small isolated pools where the water warms 2 degrees C more than the average.

“This is our window into the future 30 to 100 years from now,” Fenner told IPS.

Climate change will warm the oceans by at least 1.5 degrees C and possibly far more in the coming decades and based on Fenner’s studies of these warm pools, corals will grow much more slowly, reproduce poorly and are unlikely to survive in the long term.

It gets worse when ocean acidification, another product of climate change, is factored in.

Lab experiments where seawater acidity is increased to the levels expected in 2020 and 2060 uniformly show several important species of algae that helps glue reefs together do not grow well and their death rate increased under those high acid scenarios, said Guillermo Dias- Pulido of Australia’s University of Queensland.

“We may be facing ocean deserts in the future,” Dias-Pulido said in an interview, adding that he has only studied a few species and there are at least 650 species on the Great Barrier Reef, and some may prove to be resilient.

Researchers have found another window into the perilous future in the form of an undersea vent that releases high levels of carbon dioxide in the Mediterranean Sea. Carbon dioxide makes seawater acidic in direct proportion — more CO2, the more acidic. Maoz Fine of Bar-Ilan University in Ramat-Gan, Israel said he could easily see the rapid decline and then complete absence of coral near the vent as the acidity levels increased, corroborating Dias-Pulido’s lab research.

Fine cautioned that the levels of acidity near the vent are higher than what is expected in the oceans, but the combination of higher water temperatures and acidity is likely to be lethal well before the end of this century, he told IPS.

Increasingly warm and sour seawater is now inevitable, but how warm and how sour the oceans become is up humanity, said Simon Donner, an ecologist and climatologist at University of British Columbia. If emissions of fossil fuels can slow and eventually reverse, there is hope for corals.

The world’s fossil fuel economy is like the Titanic — we know its going to hit an iceberg but it takes a very long time to stop a really big ship Donner told IPS. “If we can reduce other threats to reefs and keep them healthy, that’s like reducing the size of the iceberg,” he said.

Souter of the Global Coral Reef Monitoring Network says there is very good evidence to support Donner. Reefs that suffered bleaching but are remote and do not have other stress factors like pollution or overfishing show a good rate of recovery.

Two years ago, one-third of the 2,000-km Great Barrier Reef was closed to all fishing. In just that short time, a key species called coral trout has increased 30 to 75 percent, an example of reef’s ability to bounce back when properly protected, Souter said.

Astonishingly, fishing is allowed in almost all marine protected areas, parks and sanctuaries in the world. The opposite is true for parks on land, where hunting is rarely allowed.

Reefs around remote pacific atolls where there is no fishing are doing remarkably well despite warmer sea temperatures, said Nancy Knowlton of the Smithsonian Natural History Museum in Washington.

“There are lots of huge fish, lots of corals and little signs of disease,” Knowlton told IPS.

That abundance what once the normal state on all reefs, and it shows that healthy reefs can better withstand the impact of climate change. There are other places in the world where reefs are doing well, such as islands of Palau in the Pacific and Bonaire in the Caribbean, but that’s because local people take pride in their reefs and protect them, she said.

While the global threat of climate change to oceans appears overwhelming, reducing CO2 levels in the atmosphere will automatically reduce ocean acidity, said Joan Kleypas of the National Centre for Atmospheric Research in Boulder Colorado.

“It’s like a volume slider – dial down the CO2 level and the volume of ocean acidity follows,” Kleypas said in an interview.

Change is in the air and people, especially the younger generation, recognise the crisis we are facing and they are willing to step and do what it takes to solve these problems, she said.

That change will have to come quickly, over the next eight years, reckons Ove Hoegh-Guldberg, a scientist at the Centre for Marine Studies at the University of Queensland, Australia.

“We can’t exceed 450 ppm (parts per million) of atmospheric CO2,” Hoegh-Guldberg. Current CO2 levels are 384 ppm, compared to the pre- industrial norm of 280.

Reducing emissions to save corals will likely prevent the collapse of other important ecosystems which sustain life on the planet and pull humanity back from the brink, he said.

“The coral reef crisis is really a crisis of governance,” Hughes concluded.

“The planet will never be like it was in the year 2000, or 1900 for that matter,” he said. “We need to look forward and see where we want to go and start moving in that direction.”

First published on IPS as: Cutting CO2 Could Save Dying Corals