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
- Microalgae help corals tolerate environmental stresson February 14, 2020 at 12:47 pm
While this can help corals weather a heat wave, it may have a price—lower nutrition given to the coral compared to heat-sensitive symbionts. Kāneʻohe Bay has experienced significant human impacts over ...
- Study Finds Humans Have Been Hurting Reefs for Centurieson February 14, 2020 at 11:11 am
(Dan Peled/AAP Image via AP) “Coral reef ecosystems now appear to be unraveling before our eyes, with intensifying outbreaks of coral disease and bleaching threatening the persistence of reef habitats ...
- Coral reefs: Centuries of human impacton February 14, 2020 at 10:56 am
"Coral reef ecosystems now appear to be unraveling before our eyes, with intensifying outbreaks of coral disease and bleaching threatening the persistence of reef habitats and the immense biodiversity ...
- Corals in murky waters less affected by temperature stresson February 14, 2020 at 9:39 am
The co-authors examined coral bleaching severity on a global scale and found that bleaching was indeed reduced during temperature stress events when turbidity was naturally elevated, although excess ...
- University of Guam secures grant for innovative coral restoration workon February 14, 2020 at 8:00 am
The project will involve Raymundo and her graduate students, led by Ph.D. student Whitney Hoot, propagating types of staghorn corals that survived the mass coral bleaching and mortality events in the ...
- Algae team rosters could help ID 'super corals'on February 12, 2020 at 2:24 pm
"Over the past two years, we've been involved in a sampling effort in Mo'orea, French Polynesia, where we've tagged individual coral colonies all around the island," she said. "When I was there last ...
- The Coral Ark That Hopes to Save Florida’s Ailing Reefson February 12, 2020 at 2:17 pm
The Coral Rescue Project’s ark, operated by Nova Southeastern University (NSU), is part of a much larger project to save Caribbean corals from a mysterious disease that turns lush reefs into ...
- Record fires and dead coral reefs aren’t dulling Australia’s lust for coal.on February 12, 2020 at 10:34 am
In 2016 and 2017, a series of scientific reports showed that bleaching across the 1,400-mile Great Barrier Reef system had been far more extensive in recent years than previously thought. Then, last ...
- Best Thalassotherapy with Extreme Plants, Best Outdoor Skin Care – iLabon February 11, 2020 at 7:21 pm
The ecological environment is undergoing dramatic changes. The most dangerous skin killer is outdoor environment. Traditional skin care products cannot cope with the ever-changing environment. iLab ...
- The high-tech portable lab helping coral fight climate changeon February 11, 2020 at 5:49 pm
The development of a ship-based mobile laboratory which mimics conditions in the ocean has been hailed as a massive breakthrough in the fight against coral bleaching. AIMS' high-tech portable aquarium ...
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