
An example of coral bleaching seen at the Great Barrier Reef. Image: University of Sydney
The vital natural resource is facing increasing threats due to the climate crisis.
Marine scientists from the University of Sydney yesterday have published the first peer-reviewed study documenting “catastrophic” coral bleaching events at the southern Great Barrier Reef in the 2023-2024 global marine heatwave.
Coral reefs provide essential services to human communities, including fisheries, tourism and coastal protection (a 2017 study found that the Great Barrier Reef was worth a total of A$56bn), in addition to numerous forms of marine life. However, the Great Barrier Reef is facing increasing threats from the climate crisis.
Led by Prof Maria Byrne, the research, which was published in Limnology and Oceanography Letters, highlights the alarming impact of unprecedented marine heatwaves on coral ecosystems, which resulted in bleaching and coral mortality.
The study raises pressing concerns for marine biodiversity and the communities that depend on these vital ecosystems. Its findings follow the publication of a survey last November by the Australian Institute of Marine Science which found “substantial losses” in parts of the Great Barrier Reef.
The research team tracked the health of 462 coral colonies at the University of Sydney’s Great Barrier Reef research station located on One Tree Island over the course of 161 days.
The team found that 66pc of the colonies were bleached by February 2024 and 80pc by April. And by July, 44pc of the bleached colonies had died, with some coral genera, such as Acropora, experiencing a massive 95pc mortality rate.
Pointing to the findings, the team has called for a “collaborative approach” to conservation, one which involves local communities, scientists and policymakers.
Byrne said that the team’s 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”.
“The southern Great Barrier Reef, despite its protected status, was not immune to the extreme heat stress that triggered this catastrophic bleaching event.”
Prof Ana Vila Concejo, a co-author of the study, added that the research should serve as “a wake-up call for policymakers and conservationists”.
Another co-author of the study, Dr Shawna Foo maintained that although the reef’s highly protected status may not have prevented the detrimental effects of the heatwave, “its role in facilitating recovery will be crucial to observe”.
Many solutions for preventing coral reef bleaching have been floated. In 2018, scientists from the Australian Institute of Marine Science developed and deployed a floating biodegradable film made from calcium carbonate. This film is 50,000 times thinner than a human hair, but has shown itself to be a great protector of coral, in essence acting as a ‘sun shield’.
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