[Image: FMT]
A new study has found that record ocean warming levels have taken a devastating toll on one of the world’s greatest natural wonders, Australia’s Great Barrier Reef.
According to the study, coral bleaching is reaching “catastrophic” levels, with more than 50% of the corals monitored in the reef’s south killed last year during the most “severe and widespread bleaching” to ever hit the area.
In 2024, the reef experienced its worst summer on record. Soaring ocean temperatures smashed records, causing the reef’s seventh mass bleaching event. Corals are bleached white when marine heat waves put corals under stress, causing them to expel algae from their tissue and drain their colour.
Coral damage was also accelerated last year by the El Niño weather pattern, which heats ocean temperatures in this part of the world.
Scientists from the University of Sydney tracked 462 coral colonies at the reef’s One Tree Island over the course of five months last year, beginning at the heat wave’s peak in early February.
By May, 370 of those colonies were bleached and, by July, 52% of the bleached corals were dead, according to the peer-reviewed study published in Limnology and Oceanography Letters.
Some coral species monitored had a mortality rate of 95%, with researchers observing the start of “colony collapse” where the dead skeleton detaches from the reef and turns to rubble.
Another species, the Goniopora, became infected by black band disease, which invades the coral’s tissue and can kill it.
“Our findings underscore the urgent need for action to protect coral reefs, which are not only biodiversity hotspots but also crucial for food security and coastal protection,” said lead author Maria Byrne, from the School of Life and Environmental Sciences at the university.
But the reef, “despite its protected status, was not immune to the extreme heat stress that triggered this catastrophic bleaching event,” she said.
The Great Barrier Reef, the world’s biggest coral reef, covers over 133,000 square miles (345,000 square kilometres) and is home to over 1,500 fish species and 411 hard corals. It brings billions of dollars into the Australian economy each year, primarily through tourism, and is aggressively advertised to international tourists as one of the country’s – and the world’s – greatest natural marvels.
Severe mass bleaching at the Great Barrier Reef had previously been observed in 1998, 2002, 2016, 2017, 2020 and 2022.
The authors said their research was a “wake-up call for policymakers and conservationists” because its implications extend beyond ecology and conservation to communities that depend on the reef for fishing, tourism, and coastal protection.
“The resilience of coral reefs is being tested like never before, and we must prioritise strategies that enhance their ability to withstand climate change,” said Ana Vila Concejo, co-author of the study from the university’s School of Geoscience.
[Source: Crossroads Today]
