IPS reports on a recent conference focusing on the state of coral reefs in the world, the 12th International Coral Reef Symposium held July 9-13, 2012, in Cairns, Australia. The Caribbean is especially endangered; according to oceanographer Jeremy Jackson, it once had 60 percent coral cover, which has now decreased to 10 percent. Indeed, “Corals are critical and endangered ecosystems.”
Most corals thrive only in shallow waters, where there is enough light for them to grow. But the rapid rise in sea level, due to the melting of polar ice, is making these conditions increasingly scarce. Measurements from tropical seas around the world reveal that the rise in sea level (3.3 mm/year) is happening at a faster rate than many corals have grown in the past 10,000 years, according to new research released at the 12th International Coral Reef Symposium (ICRS).
“The Caribbean once had 60 percent coral cover, and that has now collapsed to 10 percent,” said Jeremy Jackson, professor emeritus at the Scripps Institution of Oceanography in California, in a special address to the symposium,. “Corals are critical and endangered ecosystems.” Sea-level rise is just one threat to corals, which have been decimated by overfishing, pollution, and bleaching from warmer sea temperatures due to climate change, Jackson added.
A colorful piece of coral is made up of thousands of tiny animals called polyps, which create cup-like limestone skeletons around themselves using calcium from seawater. Coral gets its beautiful colors from microalgae that live symbiotically with it. Reefs form as generation after generation of coral polyps live, build and die, creating a habitat for themselves and about 30 percent of all the species living in the oceans. When corals are stressed by overly warm sea temperatures or pollution, they begin to look white or bleached due to the death of the algae. They become vulnerable to disease and die if the bleaching lasts long enough. Eventually, weakened or dead coral is broken into rubble by waves and storms.
Jamaica may be the Caribbean country where reefs have deteriorated most. While it once possessed a great abundance of living coral, only five to ten percent remains, because of pollution and overfishing. “That’s happened because the people are so poor,” said Jackson. Each island is different, however. Bonaire and Curaçao have 20 to 30 percent coral cover left, and that may be growing due to good reef management, which has created no-fishing zones, reduced sources of pollution from the land, and controlled tourist access, he said. [. . .] One study in Belize estimated that without reefs protecting the coastal communities, storms would cause 240 million dollars in damages.
[. . .] One apparently small but unexpected change is the fact that emissions of carbon dioxide are turning the oceans sour. The oceans have now absorbed about a third of all human emissions of this greenhouse gas. This has kept the global climate from warming faster, but the additional carbon dioxide is altering the oceans’ chemistry, making them 30 percent more acidic.
[. . .] The rates of changes in the oceans are far faster than species have ever had to adjust to, said more than 2,500 marine scientists in the Consensus Statement on Climate Change and Coral Reefs released at the symposium. But despite all the bad news about coral, there are “glimmers of hope” as shown in Bonaire, Curaçao, and other places where there is good reef management and the impacts and stresses on these ecosystems are low, said oceanographer Jackson. “Fortunately, taking actions that are good for human society (like reducing emissions) are also good for reefs,” he added.
[The photo above (Living Oceans Foundation/IPS) shows a Bonaire reef, where, the caption describes “the olive-green coral is alive, but the mottled-gray coral is dead.”]
For more information, see full article at http://www.ipsnews.net/2012/07/scientists-discover-new-threats-to-corals/