Australia’s spectacular Great Barrier Reef is experiencing its worst bleaching ever.

The Australian federal government-funded Great Barrier Reef Marine Park Authority (GBRMPA) said today that scientists conducted an aerial survey and found that about 730 of the more than 1,000 coral reefs on the Great Barrier Reef have bleached. “This summer’s cumulative impacts across the Great Barrier Reef are more severe than in previous summers,” the Great Barrier Reef Marine Park Authority said in a statement.

The United Nations Educational, Scientific and Cultural Organization (UNESCO) will review Australia’s efforts later this year to see if they are sufficient to maintain World Heritage status for the Great Barrier Reef.

Often called the world’s largest living structure, the Great Barrier Reef stretches 2,300 kilometers and is home to stunning biodiversity, including more than 600 species of coral and 1,625 species of fish. This is the fifth large-scale coral bleaching event in the past eight years.

Corals are extremely sensitive to their growth environment. Changes in environmental conditions will directly affect the symbiotic relationship between corals and zooxanthellae. When corals excrete zooxanthellae in order to survive, bleaching will occur. If high temperatures continue, corals will eventually turn white. And die.

Roger Beeden, chief scientist of the Great Barrier Reef Marine Park Authority, said climate change poses the greatest threat to coral reefs around the world. “The Great Barrier Reef is an incredible ecosystem, and while it has shown resilience time and time again, this summer has been particularly challenging.”

Lizard Island, located in the northeast corner of Australia, can be said to be a small tropical paradise with vibrant coral reefs, but now it looks like a watery grave.

Anne Hoggett, a marine biologist who has lived and worked on Lizard Island for 33 years, said that when she first came to Lizard Island, coral bleaching occurred about once every 10 years.

It happens every year now, Hoggart said, with about 80 percent of the fragile Acropora corals on Lizard Island Reef bleaching this summer.

“We don’t know yet whether the corals have suffered too much damage to recover,” Hoggart told the outlet.

Australia has invested approximately AUD 5 billion (approximately NT$ 104.3 billion) to improve water quality, reduce the impact of climate change, and protect threatened species.