Current El Niño conditions in the Pacific Ocean have created high water temperatures that are seriously damaging coral reefs, including those on Christmas Island, which may be the epicenter for what could become a global coral bleaching event.
Researchers from the Georgia Institute of Technology recently returned from the Island and are reporting that 50 to 90 percent of corals they saw were bleached and as many as 30 percent were already dead at some sites. The situation could worsen as water temperatures remain well above normal into the early months of 2016.
"This El Niño event is driving one of the three largest global scale bleaching events on record," said Kim Cobb, a professor in Georgia Tech's School of Earth and Atmospheric Sciences who has studied long-term El Niño conditions. "Ocean temperatures exceeded the threshold for healthy corals back in the summer, and are continuing to warm. Bleaching occurs when temperatures exceed a threshold that is function of the amount of warming, as well as the length of time at that temperature."
Bleaching is an outward sign of stress on the corals, which release the symbiotic algae that normally help provide them with energy to sustain their metabolism during prolonged episodes of warm ocean temperatures. The loss of these alga turns the coral colonies white, and opens them to disease and death. Bleached corals can recover if water temperatures return to normal, but continued stress could lead to widespread coral death, Cobb said.
"This El Niño event is driving one of the three largest global scale bleaching events on record," said Kim Cobb, a professor in Georgia Tech's School of Earth and Atmospheric Sciences who has studied long-term El Niño conditions. "Ocean temperatures exceeded the threshold for healthy corals back in the summer, and are continuing to warm. Bleaching occurs when temperatures exceed a threshold that is function of the amount of warming, as well as the length of time at that temperature."
Bleaching is an outward sign of stress on the corals, which release the symbiotic algae that normally help provide them with energy to sustain their metabolism during prolonged episodes of warm ocean temperatures. The loss of these alga turns the coral colonies white, and opens them to disease and death. Bleached corals can recover if water temperatures return to normal, but continued stress could lead to widespread coral death, Cobb said.
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