From: David A Gabel, ENN
Published December 20, 2010 09:23 AM

Heading Towards a World without Corals

Every year brings new accounts of coral bleaching in the tropical oceans. Even the largest living structure on Earth, the Great Barrier Reef off the coast of Australia, is under threat. According to marine scientist, J.E.N.Veron, in a couple generations coral reefs will no longer exist, unless humans find a different way to live and allow this fragile ecosystem to recover.

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Vernon, a former chief scientist at the Australian Insitute of Marine Science is an expert on coral reefs. He has written a three-volume text book, Corals of the World, and has travelled to and observed all major coral reef regions in the world during his 66 expeditions. If any person is qualified to predict the future of coral reefs, it is him. His ominous warning may strike some as a shock, but using logic and his knowledge, he is convinced that it will be so.

It turns out that the symbiotic relationship with the algae, zooxanthellae, which sustains coral reefs is extremely fragile. Over-exposure to light plus above-average temperatures cause the algae to produce toxic levels of oxygen which cause bleaching and ultimately kill the coral.

Back in the 1980s, the first mass bleaching of coral occurred, causing a great deal of concern but no clear explanation. There is no sign that greenhouse gas increases are moderating, therefore, bleaching will continue to increase. Veron puts it this way: "on our present course, the worst bleaching year we have had to date will be an average year by 2030, and a good year by 2050." By 2050, the only corals left on Earth will be those hiding in refuges, not exposed to strong sunlight.

However, Veron points out another problem more dire than bleaching: ocean acidification. Oceans are the world's greatest absorbers of carbon dioxide. With greenhouse gas emissions, the oceans have difficulty in mixing in the CO2 between its different layers, causing it to build up near the surface where corals reside. The CO2 raises the pH level to make the ocean more acidic.

Corals which deposit calcium carbonate, need a certain water chemistry to function. As ocean alkalinity decreases, the deposition of calcium carbonate becomes more difficult and eventually impossible. The effect of acidification is catastrophic for coral reefs around the world.

In the end, coral reef collapse is inextricably linked to global climate change. They are another casualty to mankind's burning of fossil fuels. Only a radical shift in the way we live can save them.

For more information: http://e360.yale.edu/feature/is_the_end_in_sight_for_the_worlds_coral_reefs_/2347/

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