High temperatures are killing Great Barrier Reef
Australia’s famed Great Barrier Reef is suffering one of the most severe coral bleaching events on record, leaving scientists fearful for its survival as the impact of climate change worsens.
For 33 years marine biologist Anne Hoggett has lived and worked on Lizard Island, a small slice of tropical paradise off Australia’s northeast tip.
She affectionally dubs it “Blizzard Island”. The only relief from the wind and teeming showers is in the powder blue waters, where sea turtles and tiger sharks rove.
As Hoggett snorkels, schools of fish swim gracefully, feeding on the coral or darting between it. Some are as small as her little finger, others the colour of fire.
But thanks to climate change, it is becoming a watery graveyard of bleached reef.
“We don’t know yet if they’ve already sustained too much damage to recover or not,” said Hoggett.
The world is experiencing its second major coral bleaching event in 10 years, the US National Oceanic and Atmospheric Administration announced on Monday.
Coral bleaching occurs when water temperatures rise more than one degree Celsius.
“As the world’s oceans continue to warm, coral bleaching is becoming more frequent and severe,” said the administration’s Derek Manzello.
In a bid to survive, the coral expels microscopic algae, known as zooxanthellae, which it needs to live. If high temperatures persist, the coral eventually evicts most of the zooxanthellae, turns white, and dies.
Since February, ocean temperatures around Lizard Island have been up to 2oC warmer than average, and Hoggett estimates about 80% of the coral is already dead.
Often dubbed the world’s largest living structure, the Great Barrier Reef is a 2 300 kilometre-long expanse housing a stunning array of biodiversity, including more than 600 types of coral and 1 625 fish species.
It is vital to the health of the ocean and Australia’s tourism industry, netting billions of dollars every year.
But repeated mass bleaching events have robbed the reef of its wonder, turning banks of once-vibrant corals to a sickly white.
In March, Australian reef authorities announced another mass bleaching event was underway, the fifth in eight years.
Through aerial monitoring, they found more than 600 reefs have experienced bleaching. Ten percent of the area is classed as suffering extreme bleaching, where more than 90% of corals are distressed and unlikely to survive.
Just nine weeks ago, the reef off Lizard Island was healthy and vibrant, Hoggett said. Now, she points to the fluorescent pink and blue coral.
Its beauty means the coral is highly stressed and expelling the healthy algae it needs to survive.
Elsewhere, white coral is covered in a fluffy, brown algae, a sign it is dead.
When Hoggett first arrived on the island, bleaching would occur every 10 years or so. Mass bleaching events along the reef occurred in 1998, 2002, 2016, 2017, 2020, 2022 and now 2024.
She is heartbroken.
“The only time we’ve seen bleaching this bad was in 2016, when just about everything died.
“It’s anybody’s guess as to how many of these corals that are still alive now will be able to survive and recover,” she said. –