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
- Why Are Coral Reefs Important?on January 26, 2021 at 7:17 am
Coral reefs are highly productive marine ecosystems that serve as a home to a great diversity of marine flora and fauna.
- Reef Safe Sunscreen Dispensers Installed at Kahalu‘u Beachon January 25, 2021 at 6:27 pm
As part of an ongoing initiative to support reef health and regrowth, two new reef-safe sunscreen dispensers have been installed at the pavilion in Kahalu‘u Beach Park. The program is made possible by ...
- Robot ‘jellyfish’ to protect coral reefson January 25, 2021 at 10:56 am
A robot inspired by the shape and delicate underwater movements of a jellyfish, allowing it to safely explore endangered coral reefs, was unveiled by British scientists.
- Deep-sea coral reefs found in Ireland at the edge of submarine canyonon January 24, 2021 at 3:32 pm
Marine scientists are interested in studying the Porcupine Bank Canyon, which is the largest submarine canyon at the edge of Ireland's continental shelf.
- UK students create 3D-printed coral structures that could rebuild world's damaged reefson January 23, 2021 at 6:29 pm
Scientists hope they can then attach live coral to 3D-printed backbones, before placing them in the ocean to grow new reefs.
- Scientists discover how the potentially oldest coral reefs in the Mediterranean developedon January 21, 2021 at 12:16 pm
A new study from the Institut de Ciències del Mar (ICM-CSIC, Spain) and the National Oceanography Centre brings unprecedented insights into the environmental constraints and climatic events that ...
- “Coral Hospital” Tool Could Help Safeguard Reefs Facing Climate Changeon January 20, 2021 at 6:16 pm
How to Identify Heat-Stressed Corals Researchers have found a novel way to identify heat-stressed corals, which could help scientists pinpoint the coral species that need protection from warming ocean ...
- Half of Taiwan’s Reefs Have Been Bleached and a Third Are Dying: Reporton January 19, 2021 at 5:28 pm
Half of all reefs off the coast of Taiwan have been bleached due to warming seas, with a third damaged so profoundly they cannot be saved, according to a new report. The report, published on Jan. 13 ...
- Robot 'jellyfish' to protect endangered coral reefson January 19, 2021 at 4:00 pm
A robot inspired by the shape and delicate underwater movements of a jellyfish, allowing it to safely explore endangered coral reefs, was unveiled by British scientists on Wednesday.
via Bing News