Australian scientists managing the Great Barrier Reef have sounded the alarm that the World Heritage site is experiencing the worst coral bleaching in 15 years.
Coral reefs are colonies comprised of countless millions of genetically identical animals, known as polyps. Coral bleaching results when corals expel their colourful endosymbionts, the photosynthetic zooxanthellae, leaving the white coral skeleton behind. The coral colony, which is still alive (at least for awhile), is thus “bleached”.
The Great Barrier Reef Marine Park Authority said it was lifting its response to level three, authority chairman Dr Russell Reichelt said.
“A level-three response level means we’re stepping up surveys in response to the coral mortality to help us better understand the effects of various pressures on the reef and help guide management actions,” Reichelt said in a statement.
Professor Terry Hughes, a marine biologist at James Cook University, said the rising ocean temperatures associated with global warming in recent decades have taken corals “closer and closer” to bleaching tipping points.
“Without global warming we never used to have these mass bleaching events,” he said.
“The new stills are very concerning and show large sections of coral drained of all color and fighting for survival,” World Wildlife Fund spokesman Richard Leck said.
“This is the worst coral bleaching event ever to hit this most pristine part of the Great Barrier Reef.”
The Great Barrier Reef stretches 1,200 miles along Australia’s northeast coast and is the world’s largest living ecosystem.
On Monday WWF-Australia released these underwater images taken of bleached corals in the pristine northern stretches of the barrier reef north of Cooktown.