14 July 2007

Coral Controversy

In recent years, coral bleaching has been observed in many places of the world. Up to 90% of reefs in parts of the Indian Ocean have been permanently damaged. In 1998 and 2002, 5% of the Great Barrier Reef were severly damaged in mass bleaching events. One cause of this is warmer sea surface temperatures (SST). There are other factors as well, both anthropogenic and natural.

As a result of this sensitivity to warmer SST, one of the projected impacts of climate change has been the widespread destruction of coral reefs. However, recent research reported in The Australian newspaper suggests otherwise:

Researchers in north Queensland have found many corals contain microscopic algae that protect them from temperature fluctuations.

The study by the Australian Institute of Marine Science in Townsville, which clashes with the work of many coral experts who have long claimed the reef is doomed by climate change, used DNA analysis to show many corals stored several types of algae that kicked in to provide nutrients when temperatures increased.


"The potential for this hidden back-up algae to provide nutrition to coral during heat stress is far greater than previously thought," said the study's lead researcher, Madeleine van Oppen.

She acknowledged the work was viewed as controversial in coral reef sciences.

The research team believes bleaching, widely associated with the death of coral, is part of coral's natural cycle of life.

Obviously, more research needs to be done, but this provides a glimmer of hope. Still, the issue is controversial: Soft Corals "Melting" Due to Warming Seas, Expert Says -- National Geographic.

Soft coral communities in tropical waters may literally be melting away because of bleaching events, which have been dramatically accelerated by global warming, a leading expert says.
Maoz Fine, of the Interuniversity Institute for Marine Sciences at Eilat, Israel, said global warming will subject most reefs to deadly temperature increases by the year 2030.

Preparing reefs now for dramatic climate change should be the most important task, he said.

"If we want to see reefs in the near future, we must remove all other disturbances such as overfishing, increased pressure from tourists, sewage, and so on," he said.

"Many acute disturbances can be prevented, and this will definitely increase the resilience of reefs."

This story from ScienceDaily suggests that it takes a significant amount of time for the reef system to recover, and preservation may require even more extreme measures...
Overall, the time frame needed by surgeonfish and tangs, triggerfish, rabbitfish, and the coral-building algae to completely rebuild their populations to pre-fishing levels may exceed the length of the study."Decisions made by managers to close areas to fishing in an effort to save fish populations can be unpopular but necessary," added McClanahan. "What this study has shown us is that many fish populations take long periods of time to recover fully, and that permanent bans on fishing in some parks are necessary if we're to conserve healthy coral reef systems."
The possible impacts above don't even take the likely effects of ocean acidification into account (from National Geographic):

More troublesome to marine habitats, biologists say, may be the potential impact of rising ocean acidity from fossil fuel use.

Acting as a carbon sink, the ocean absorbs atmospheric carbon dioxide. One 2005 study estimated that half of Earth's airborne CO2 was ultimately trapped by the ocean.

Through a series of chemical reactions, this dissolved CO2 turns ocean water more acidic.

Corals build their skeletons from waterborne calcium carbonate, the same mineral that makes limestone.

Rising ocean acidity retards the speed at which calcification can occur and in some cases may cause corals to build weaker skeletons.

The organisms, in effect, suffer a sort of osteoperosis.

All in all, if one of your ambitions (and one I would personally recommend) in life is too see the wondrous beauty that is a coral reef (or if you want your kids to see one...), the time to do it is now rather than later.

See Also:

Great Barrier Reef Marine Park Authority

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