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
via Google News
The Latest on: Coral reefs
- Bulk carrier leaking oil on Solomons Islands reef after running aground on February 19, 2019 at 6:41 pm
HONIARA, 20 FEBRUARY 2019 (THE GUARDIAN) – The Solomon Islands prime minister has asked Australia for emergency help cleaning up an environmental disaster after oil spilled from a bulk carrier that ra... […]
- New Research Suggests a Different Approach to Protecting Reef-Building Corals on February 19, 2019 at 1:27 pm
A new study from the University of North Carolina at Chapel Hill reports that protecting coral reefs from fishing and pollution does not help coral populations cope with climate change. A new study fr... […]
- New living reef exhibit features cutting-edge coral research by UH scientists on February 19, 2019 at 11:33 am
A new living reef exhibit at the University of Hawaiʻi Waikīkī Aquarium highlights cutting-edge coral research done by six researchers at the UH Mānoa. It features work on both soft and stony coral li... […]
- Coral grown on land is subject of presentation on February 19, 2019 at 9:27 am
A land-based coral nursery that quickly grows massive coral colonies for replenishing degraded reefs will be the topic of a free presentation in Maalaea on March 6. David Gulko, director of the Divisi... […]
- Great Barrier Reef coral at risk of bleaching from Queensland flood waters on February 17, 2019 at 8:10 pm
The Great Barrier Reef is in danger of further coral bleaching due to recent flooding in north Queensland. Photograph: Ed Roberts/ARC Centre of Excellence for Coral Reef Studies Freshwater bleaching o... […]
- Researchers show that tropical reefs can host coral or seaweed communities under the same conditions on February 12, 2019 at 4:48 am
Under certain conditions, a reef can support either a thriving coral community or a lush seaweed field, depending on what it started with. Credit: Kai Kopecky, Russ Schmitt Tropical reefs are ... […]
- The flip side of a reef: Coral, seaweed -- or both? on February 11, 2019 at 9:09 pm
Find related stories on NSF's Long-Term Ecological Research Program at this link. Tropical reefs can change their composition from vibrant corals to underwater fields of seaweed. Now, researchers have ... […]
- Key West, Florida, bans sale of sunscreens that harm coral reefs on February 7, 2019 at 8:06 am
KEY WEST, Fla. (AP) — City officials in Key West voted to ban sunscreens containing two ingredients that scientists have said are harmful to the coral reef ecosystem. In a 6-1 vote Tuesday, the Key We... […]
- Key West Bans Popular Sunscreen To Protect Coral Reef on February 7, 2019 at 5:42 am
City officials in Key West voted to ban sunscreens containing two ingredients that scientists have said are harmful to the coral reef ecosystem. In a 6-1 vote Tuesday, the Key West City Commission ban... […]
via Bing News