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BIODIVERSITY: A Third of Corals Face Extinction

Stephen Leahy

FORT LAUDERDALE, U.S., Jul 10 2008 (IPS) - One third of reef-building corals already face extinction because of climate change, the first-ever global assessment has found.

Dead Acropora corals Credit: Keoki Stender,

Dead Acropora corals Credit: Keoki Stender,

Reefs are made up of hundreds of coral species, and a two-year study to determine the current status of corals has discovered that 231 of the 704 species assessed will be “red-listed” Thursday. This means these 231 species meet the International Union for Conservation of Nature (IUCN) Red List Criteria for species at risk of extinction in the near future.

Previously, only 10 species of corals had been red-listed, mainly because no proper assessment had been done before.

“We were not expecting the numbers to be that high,” said Suzanne Livingstone of the IUCN’s Global Marine Species Assessment (GMSA) in Norfolk, Virginia. The paper was published Thursday in Science.

If the same assessment of corals had been done 20 years ago, only 13 of the 704 species would have been red-listed, Livingstone told IPS at the 11th International Coral Reef Symposium (ICRS) in Fort Lauderdale, Florida. However, in that short time span, climate change has warmed the oceans and begun to make them more acidic and corals are suffering.

“It’s frightening when you think about it,” she said.

Coral reefs are often called the rainforests of the oceans for the richness of species they harbour, representing 25 to 30 percent of all marine species. Millions of people, including many in developing countries, derive their livelihoods from fishing, while around 2.6 billion people get their protein from seafood, according to studies done by the United Nations Environment Programme (UNEP).

Coral reefs also help mitigate beach erosion and have high recreation value for tourism. UNEP estimates that a typical coral reef can absorb up to 90 percent of the energy of wind-generated waves, thus protecting coastal areas from damage.

The economic value of reefs globally is estimated at 375 billion dollars, Brian Huse, executive director of the Coral Reef Alliance, a U.S.-based NGO dedicated to protecting the health of coral reefs, told IPS in a previous interview.

“When corals die off, so do the other plants and animals that depend on coral reefs for food and shelter, and this can lead to the collapse of entire ecosystems,” said Kent Carpenter, lead author of the Science article, GMSA Director, IUCN Species Programme.

The rate at which corals are approaching extinction is far faster than any previous extinction event in Earth’s history, Carpenter told IPS. “It’s the most alarming finding for biodiversity in the marine realm,” he said, adding that only amphibians are at greater risk, also due to climate change.

Staghorn corals face the highest risk of extinction, with 52 percent of species listed in a threatened category. The Caribbean region has the highest number of highly threatened corals (endangered and critically endangered), including the iconic elkhorn coral (Acropora palmata) which is listed as critically endangered. The high biodiversity “Coral Triangle” in the western Pacific’s Indo-Malay-Philippine Archipelago has the highest proportions of vulnerable and near-threatened species in the Indo-Pacific, largely resulting from the high concentration of people living in many parts of the region.

Not all of the world’s 845 reef-building corals could be assessed. Carpenter says there wasn’t enough data to evaluate how 141 species are doing.

While climate change is the primary global threat because it warms ocean temperatures beyond corals’ heat tolerance, pollution and overfishing are also major stressors that amplify and accelerate the impact. Another problem for corals is ocean acidification. However, since scientists only recently discovered that carbon emissions from burning of fossil fuels are turning the oceans more acidic, it hasn’t been fully assessed in this study, said Livingstone.

“Ultimately it is a combination of all these impacts on corals,” she said.

Red-listing does not mean a species will become extinct, but it does mean that if the conditions that are threatening corals continue or worsen, then they may very well become extinct. The IUCN Red List is the widely-accepted gold standard for determining which species are at risk. It has eight levels of risk ranging from no risk to critically endangered. The 231 coral species are in the “critically endangered”, “endangered” or “vulnerable” categories.

The results emphasise the widespread plight of coral reefs and the urgent need to enact conservation measures, said Julia Marton-Lefèvre, IUCN director general.

“We either reduce our CO2 emissions now or many corals will be lost forever,” Marton-Lefèvre said in a statement.

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