Kim Cobb, a marine scientist at the Georgia Institute of Technology, expected the coral to be damaged when she plunged into the deep blue waters off Kiritimati Island, a remote atoll near the center of the Pacific Ocean. Still, she was stunned by what she saw as she descended some 30 feet to the rim of a coral outcropping.
“The entire reef is covered with a red-brown fuzz,” Dr. Cobb said when she returned to the surface after her recent dive. “It is otherworldly. It is algae that has grown over dead coral. It was devastating.”
The damage off Kiritimati is part of a mass bleaching of coral reefs around the world, only the third on record and possibly the worst ever. Scientists believe that heat stress from multiple weather events including the latest severe El Niño, compounded by climate change, has threatened more than a third of Earth’s coral reefs. Many may not recover.
Coral reefs are the crucial incubators of the ocean’s ecosystem, providing food and shelter to a quarter of all marine species, and they support fish stocks that feed more than one billion people. They are made up of millions of tiny animals, called polyps, that form symbiotic relationships with algae, which in turn capture sunlight and carbon dioxide to make sugars that feed the polyps.
An estimated 30 million small-scale fishermen and women depend on reefs for their livelihoods, more than one million in the Philippines alone. In Indonesia, fish supported by the reefs provide the primary source of protein.
“This is a huge, looming planetary crisis, and we are sticking our heads in the sand about it,” said Justin Marshall, the director of CoralWatch at Australia’s University of Queensland.
Bleaching occurs when high heat and bright sunshine cause the metabolism of the algae — which give coral reefs their brilliant colors and energy — to speed out of control, and they start creating toxins. The polyps recoil. If temperatures drop, the corals can recover, but denuded ones remain vulnerable to disease. When heat stress continues, they starve to death.
Damaged or dying reefs have been found from Réunion, off the coast of Madagascar, to East Flores, Indonesia, and from Guam and Hawaii in the Pacific to the Florida Keys in the Atlantic.
The largest bleaching, at Australia’s Great Barrier Reef, was confirmed last month. In a survey of 520 individual reefs that make up the Great Barrier Reef’s northern section, scientists from Australia’s National Coral Bleaching Task Force found only four with no signs of bleaching. Some 620 miles of reef, much of it previously in pristine condition, had suffered significant bleaching.
In follow-up surveys, scientists diving on the reef said half the coral they had seen had died. Terry Hughes, the director of the Center of Excellence for Coral Reef Studies at James Cook University in Queensland, who took part in the survey, warned that even more would succumb if the water did not cool soon.
The Latest on: Coral bleaching
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The Latest on: Coral bleaching
- Reducing nutrient pollution helps corals resist bleachingon February 28, 2020 at 1:50 pm
Reducing nutrient pollution can help prevent coral reefs from bleaching during moderate heatwaves, according to a National Science Foundation-funded study by researchers at UC Santa Barbara. The ...
- Great Barrier Reef Bleaching Threats Loom over Australiaon February 27, 2020 at 1:32 pm
Researchers at Australia’s Great Barrier Reef Marine Park Authority (GBRMPA) are predicting a coral bleaching event during the southern hemisphere’s summer. Analysts say the event could be the most ...
- Great Barrier Reef: coral bleaching to worsen unless weather conditions changeon February 27, 2020 at 8:30 am
Cyclone is temporarily cooling distressed corals but experts say parts of reef that previously escaped bleaching are at risk ...
- All coral reefs could die by the end of the century, new research shows. Before-and-after photos show what that would look like.on February 26, 2020 at 5:41 am
Coral reefs cover less than 1% of Earth's surface, but provide a home to over 25% of all marine life. They could disappear within decades.
- Pollution cuts can prevent coral bleaching when things get hoton February 25, 2020 at 10:24 am
Reducing nutrient pollution can help prevent coral from bleaching during moderate heatwaves, researchers report. The results offer new strategies for managing these highly threatened yet important ...
- Curbing nutrient overload helps coral resist bleachingon February 25, 2020 at 9:46 am
According to a new study, published this week in the journal PNAS, reductions in nutrient pollution help corals avoid bleaching during moderate heatwaves.
- Reducing nutrient pollution helps coral resist bleachingon February 25, 2020 at 5:11 am
A study by researchers at UC Santa Barbara details how reducing nutrient pollution can help prevent coral from bleaching during moderate heatwaves. The results, which appear in the journal Proceedings ...
- Nearly All Coral Reefs Will Disappear Over The Next 20 Years, Scientists Sayon February 24, 2020 at 1:08 pm
Over the next 20 years, scientists estimate about 70 to 90% of all coral reefs will disappear primarily as a result of warming ocean waters, ocean acidity, and pollution. Expand that out to 2100 and ...
- Experts warn Great Barrier Reef could soon see third mass coral bleaching in five yearson February 23, 2020 at 6:10 pm
Feel free to republish and share widely. Australian scientists and conservationists warned in the Guardian Thursday that the Great Barrier Reef could soon endure a third major coral bleaching event in ...
- Great Barrier Reef could face 'most extensive coral bleaching ever', scientists sayon February 21, 2020 at 11:00 am
This year’s bleaching likely to be widespread although less intensive than previous outbreaks, National Oceanic and Atmospheric Administration says ...
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