Marine scientists fear confirmation of another La Niña weather event this year could lead to increased coral bleaching along the northwest coast of Western Australia over the summer.
- James Gilmour of the Australian Institute of Marine Science says mass bleaching occurs once temperatures reach two degrees above normal for several weeks
- Up to 30% of Turquoise Bay’s corals were bleached earlier this year
- Department of Biodiversity Conservation and Attractions, Salyann Gudge urges people to be careful when visiting the reef and not to damage the coral
Although there are signs of recovery, researchers have confirmed significant bleaching events along the World Heritage-listed Ningaloo Reef, including Turquoise Bay and Coral Bay.
Australian Institute of Marine Science researchers James Gilmour and Luke Thomas monitor sections of the marine park for coral bleaching.
“The common thread is climate change. The oceans are warming and no reef is truly safe,” said Dr Thomas.
Further south, scientists have detected between 20 and 30 percent coral bleaching in Turquoise Bay.
But there are signs of recovery from last summer’s marine heat wave.
Marine Park Coordinator Sallyann Gudge of the Department of Biodiversity Conservation and Attractions (DBCA) regularly monitors the area.
A double whammy for the reef
Warm ocean temperatures and light winds created a double impact on WA’s Ningaloo coast earlier this year.
A marine heatwave caused bleaching at Bundegi and Turquoise Bay, while an unrelated coral spawning event at the same time led to massive fish kills at Coral Bay in April.
“The eggs and reproductive cells of corals rise to the surface and cause a slick, which usually disperses into the ocean,” she said.
“But this year, given the weather, he actually just dragged him into Bill’s Bay, and he was there for a week.
“And those conditions caused oxygen depletion out of the water.
Not the first time
The DBCA says that since it began monitoring the area, Bill’s Bay has experienced fish kills and coral bleaching due to anoxic (lack of oxygen) events in 1978, 1989, 2002, 2005, 2008 , 2019 and 2022.
Although there are signs of recovery, scientists fear that this third consecutive La Niña weather event, confirmed by the Bureau of Meteorology, could again lead to higher ocean temperatures and light winds along the coast. northwest this summer.
Dr Gilmour said the mass bleaching happened once the temperature was two degrees above normal for several weeks.
However, he says, a bleached coral is not necessarily a dead coral.
“It can be any type of stress, but it’s usually warm water where the corals expel or spit out the tiny algae cells that live inside their tissues. And the cells algae really provide a food source for the corals,” he said.
“It’s called bleaching because you can see the white skeleton through the translucent fabric.
“But if high heat persists for several weeks, then the coral will most certainly die.”
Take care of our reef
As ocean temperatures continue to rise, Dr Thomas says they are using DNA technology to help find heat-tolerant corals on the Ningaloo Reef and learn from them.
“[We are] trying to focus on how temperature tolerance varies across the reef,” Dr Thomas said.
“What are the mechanisms driving this variation? Can we harness this natural variation?
“Can we find pockets of heat-tolerant corals?”
The coral is already renowned for its fragility, but with sections of the reef in recovery mode, the DBCA urges people to be careful when visiting the reef.
“Please don’t stand on the coral. Don’t touch the coral. And look and enjoy, but don’t take,” Ms Gudge said.
For now, the DBCA and researchers say they will continue to monitor Ningaloo Reef this summer.