The future of the world’s coral reefs is uncertain, as the impact of global heating continues to escalate. However, according to a study published today in Nature Climate Change, the response of the Great Barrier Reef to extreme temperatures in 2017 was markedly different to one year earlier, following two back-to-back bouts of coral bleaching. Remarkably, corals that bleached and survived 2016 were more resistant in 2017 to a recurrence of hot conditions.
“Dead corals don’t bleach for a second time. The north lost millions of heat-sensitive corals in 2016, and most of the survivors were the tougher species. As a result of bleaching, the mix of species is changing very rapidly,” said lead author Prof Terry Hughes, Director of the Australian Research Council Centre of Excellence for Coral Reef Studies (Coral CoE), headquartered at James Cook University.
“We were astonished to find less bleaching in 2017, because the temperatures were even more extreme than the year before,” he said.
The new research highlights the extent of damage, or “geographic footprint” of multiple coral bleaching events across the 2,300 km length of the world-heritage listed area.
The back-to-back heatwaves bring the total number of mass bleaching events on the Great Barrier Reef to four over the past two decades (in 1998, 2002, 2016 and 2017). The scientists found that only 7% of the Great Barrier Reef escaped bleaching entirely since 1998, and after the 2017 event, 61% of reefs have now been severely bleached at least once.
“We found, using the National Oceanic and Atmospheric Administration’s (NOAA) satellite-based coral bleaching tools, that corals in the north of the Great Barrier Reef were exposed to the most heat stress in 2016. A year later, the central region saw the most prolonged heating,” said co-author Dr Mark Eakin, from NOAA’s Coral Reef Watch program, in Maryland, USA.
The southern third of the Great Barrier Reef was cooler in both years due to local weather conditions, and escaped with only minor bleaching.
“It’s only a matter of time before we see another mass-bleaching event, triggered by the next marine heatwave, driven by global heating,” said co-author Dr Andrew Hoeyof Coral CoE at James Cook University. “One of the worst possible scenarios is we’ll see these southern corals succumb to bleaching in the near future.”
“The outcome in 2017 depended on the conditions experienced by the corals one year earlier. We called that ‘ecological memory,’ and show that these repeating events are now acting together in ways that we didn’t expect,” said Prof Hughes.
“We’ve never seen back-to-back mass coral bleaching before on the Great Barrier Reef, in two consecutive summers. The combined footprint has killed close to half of the corals on two-thirds of the world’s largest reef system,” said Dr Hoey.
“We need urgent global action on greenhouse emissions to save the world’s coral reefs. Australia should be – but regrettably isn’t – at the forefront of tackling global heating,” said Prof Hughes.
Learn more: A glimmer of hope for the world’s coral reefs
The Latest on: Coral reefs
[google_news title=”” keyword=”coral reefs” num_posts=”10″ blurb_length=”0″ show_thumb=”left”]
via Google News
The Latest on: Coral reefs
- Technology and data initiatives aim to preserve the world’s declining coral reefson April 26, 2024 at 1:38 am
Coral reefs have been described as the “rainforests of the ocean”. Which is why these two initiatives to try and preserve them are so important.
- A coral-bleaching event is devastating reefs globally − threatening tiny creatures whose beauty and biology have shaped human cultures for centurieson April 25, 2024 at 10:02 am
Coral’s biological uniqueness and central role in sustaining other forms of life, including humans, are reasons enough to preserve it. And scientists are making extraordinary efforts, such as ...
- It’s One of the Last Pristine Coral Reefs on Earth. Should We Be Visiting It?on April 24, 2024 at 12:15 pm
The Raja Ampat archipelago of Indonesia looms large in the imaginations of underwater adventurers. But by visiting its relatively untouched reefs are we protecting them—or threatening them?
- Culling predatory starfish conserves coral on the Great Barrier Reefon April 24, 2024 at 11:00 am
Targeted culling of crown-of-thorns starfish has resulted in parts of the Great Barrier Reef maintaining and even increasing coral cover, leading researchers to call for the programme to be dramatical ...
- New algorithm solves century-old problem for coral reef scientistson April 23, 2024 at 7:21 am
An algorithm developed by a Florida Tech graduate student creates a new ecological survey method that allows scientists to unlock important historical data from a vast trove of coral-reef photographs ...
- More than coral: The unseen casualties of record-breaking heat on the Great Barrier Reefon April 22, 2024 at 8:38 am
In past bleaching events on the Great Barrier Reef, the southern region has sometimes been spared worst of the bleaching. Not this time. This year's intense underwater heat has triggered the most ...
- These coral reefs suffered major damage. Watch how restoration efforts helped bring them backon April 19, 2024 at 10:57 am
Coral reefs offer crucial habitat for marine creatures and protection for coastal communities, but face a long list of threats due to human activity. One restoration project in Indonesia demonstrates ...
- UN envoy says of the threat to coral reefs: 'Are we faced with a colossal ecosystem tragedy? Yes'on April 16, 2024 at 11:07 am
ATHENS, Greece -- The world is not doing enough to protect coral reefs, the United Nations’ special envoy for the ocean said Tuesday in defense of the marine ecosystems that protect biodiversity, ...
- Coral reefs suffer fourth global bleaching event, NOAA sayson April 16, 2024 at 9:24 am
Along coastlines from Australia to Kenya to Mexico, many of the world's colorful coral reefs have turned a ghostly white in what scientists said on Monday amounted to the fourth global bleaching event ...
via Bing News