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Global Warming May Create Island Refuges for Corals

Upwelling to bring cold, nutrient rich waters to Gilbert Islands.

May 3, 2012

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bleached coral


Bleached corals results when corals lose symbioitic algae that lives in the coral tissues, which results in the death of the coral. (Photo by Jessie Kneeland, Woods Hole Oceanographic Institution)
coral study
Today: The Glibert Islands, a chain of 16 atolls and coral islands experience trade winds that blow east to west that creates a surface current along the equator. The Equatorial Undercurrent (EUC) flows at 100 to 200 meters depth in the opposite direction, west to east. When the current hits an island, the cooler water (shown as blue), which is higher in chlorophyll-containing marine phytoplankton, flows up toward the surface. (Illustration by Amy Caracappa-Qubeck, Woods Hole Oceanographic Institution).
coral study future
The Future: Scientists predict that ocean surface temperatures will rise more than 5 degree Fahrenheit (3 degrees Celsius) by the end of this century. According to the model produced by Karnauskas and Cohen, the equatorial trade winds will weaken, which in turn will cause a slowing or weakening of the surface current. This drag on the EUC will be reduced and then it will strengthen, bringing with it more nutrient rich waters to the surface around the Gilbert Islands. This, the scientists say will result in more robust marine life near the islands. The slower rate at which the water temperatures rise may give corals a chance to adapt to the temperatures and survive in warmer waters. (Illustration by Amy Caracappa-Qubeck, Woods Hole Oceanographic Institution

The warming of the world's oceans are expected to have adverse effects on corals, but certain areas may provide a safe haven to certain corals, according to a study published in the journal Nature Climate Change. The study was completed by climate scientist Kristopher Karnauskas from the Woods Hole Oceanographic Institution and coral scientist Anne Cohen. The scientists say that while the effects of global warming will be devastating to corals worldwide, a handful of islands in the equatorial Pacific will benefit from increased upwelling of cold water in the region. This upwelling, which the scientists predict will gain strength, will bring nutrient-rich waters to the corals that need it.

“Our model suggests that the amount of upwelling will actually increase by about 50 percent around these islands and reduce the rate of warming waters around them by about 0.7 degrees Celsius (1.25 degrees Fahrenheit) per century,” Karnauskas said in a press release put out by Woods Hole Oceanographic Institution.

The researchers believe that warming near the Gilbert Islands, a chain of 16 atolls and coral islands, won't be as fast as elsewhere in the ocean. This slower pace of warming may give the corals around the islands the capability to adapt to the new water temperatures. This slower rate of temperature change around the islands, they say, might also lead to a refuge for new corals and other species that could recolonize reefs damaged by the effects of climate change.

“While the mitigating effect of a strengthened equatorial undercurrent will not spare the corals from the perhaps inevitable warming expected for this region, the warming rate will be slower around these equatorial islands, which may allow corals and their symbiotic algae a better chance to adapt and survive,” Karnauskas said. If the model holds true, then even if neighboring reefs are hit hard, equatorial island coral reefs may well survive to produce larvae of corals and other reef species. Like a seed bank for the future, they might be a source of new corals and other species that could re-colonize damaged reefs."

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Global Warming May Create Island Refuges for Corals

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Reader Comments

Bill    Beckley,, WV

5/10/2012 10:49:41 AM

Global warming bites, but this is good to know.

Jillian    Calgary, AB

5/3/2012 4:31:34 PM

Very interesting article.

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