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bleaching of the GBR —2024.....

As the lead managers of the Great Barrier Reef, the Reef Authority keeps an eye on the Reef year-round — with efforts stepped up over summer, a typically high-risk period from extreme weather.

Over summer the Reef Authority releases weekly updates on how the Reef is faring with a focus on sea surface temperatures, rainfall and floods, cyclones, crown-of-thorns starfish outbreaks, and coral disease.

 

These updates are based on forecasts, water temperature heat mapping, in-water surveys, citizen science and aerial surveys. 

Reef health update – 08 March 2024

 

Aerial surveys conducted by the Reef Authority in collaboration with scientists from the Australian Institute of Marine Science spanning two-thirds of the Marine Park have now been completed.

These surveys confirm a widespread, often called mass, coral bleaching event is unfolding across the Great Barrier Reef.

Aerial surveys have been completed on over 300 inshore, midshelf and offshore reefs, from Cape Melville north of Cooktown to just north of Bundaberg (southern boundary of the Marine Park). Further surveys will be undertaken pending favourable weather conditions.

Aerial surveys of the Reef have revealed prevalent shallow water coral bleaching on most surveyed reefs and results are consistent with patterns of heat stress that has built up over summer.

Heat stress has not been even across the Reef, and coral bleaching observed is variable.

This unfolding coral bleaching event follows similar reports from reefs around the world during the past 12 months. These Northern Hemisphere reefs have suffered coral bleaching as a result of climate change-driven elevated ocean temperatures, amplified by El Niño conditions in the Pacific Ocean.

While aerial surveys show that this coral bleaching event is widespread, the severity and depth of coral bleaching can only be assessed through in-water surveys. We are continuing to conduct in-water observations with research partners and extended observer network.

This information is critical to informing Reef management, providing a greater understanding of what is happening so we can target management actions to protect the Reef and strengthen its resilience.

Importantly, the Reef has demonstrated its capacity to recover from previous coral bleaching events, severe tropical cyclones, and crown-of-thorns starfish outbreaks.

Bleaching of corals does not always result in coral mortality, with some corals being able to recover if conditions cool.
 

Reef management

Based on the data we’re receiving from a wide range of sources, the Reef Authority in collaboration with the Australian Institute of Marine Science, will be conducting broadscale aerial surveys in the coming weeks to understand the spatial extent of bleaching in all regions of the Marine Park.

The results of these surveys, along with other data from satellite observations and in-water surveys provided by our extended partner network, will help determine the prevalence and spatial extent of coral bleaching in these regions, and overall will provide a more comprehensive understanding of conditions across the Reef.

The Crown-of-thorns Starfish Control Program team has been undertaking control efforts and surveillance at numerous reefs during the past month.

Marine Park rangers from our Reef Joint Field Management Program are continuing to undertake in-water surveys and aerial surveillance throughout the Marine Park as part of routine observations.

On-water programs such as crown-of-thorns starfish control, Land and Sea Rangers, Eye on the Reef, Master Reef Guides, the Tourism Reef Protection Initiative, and our science partners, all play a role in improving our understanding of Reef health and undertaking activities to enhance resilience.

https://www2.gbrmpa.gov.au/learn/reef-health/reef-health-updates

 

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coral bleaching....

For the fifth time in just the past eight summers – 2016, 2017, 2020, 2022 and now 2024 - huge swathes of the Great Barrier Reef are experiencing extreme heat stress that has triggered yet another episode of mass coral bleaching. 

Including two earlier heating episodes – in 1998 (which was at the time the hottest year globally on record) and 2002 – this brings the tally to seven such extreme events in the past 26 years. 

The most conspicuous impact of unusually high temperatures on tropical and subtropical reefs is wide-scale coral bleaching and death. Sharp spikes in temperature can destroy coral tissue directly even before bleaching unfolds. Consequently, if temperatures exceed 2°C above the normal summer maximum, heat-sensitive corals die very quickly.

https://theconversation.com/the-great-barrier-reefs-latest-bout-of-bleaching-is-the-fifth-in-eight-summers-the-corals-now-have-almost-no-reprieve-225348#

 

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75 per cent....

 

‘Worst I have seen’: 75% of Great Barrier Reef suffers coral bleaching    By Brett Wilkins

 

“We are really running out of time. We need to reduce our emissions immediately,” one expert warned. “We cannot expect to save the Great Barrier Reef and be opening new fossil fuel developments.”

Marine conservationists warned Thursday that Australia’s Great Barrier Reef may be suffering its worst-ever coral bleaching event amid record ocean heat fuelled by the worsening climate emergency.

The Australian Marine Conservation Society (AMCS) said that bleached corals have been found at depths of up to nearly 60 feet, and “some corals are starting to die as they face record marine heatwaves.”

“Corals bleach when they are stressed by warmer waters for an extended period of time—during marine heatwaves, which are driven by climate change,” AMCS explained. “They expel the algae that inhabit them, which is their main energy source and they starve, sometimes to death.”

Data collected from aerial surveys shows that 75% of the Great Barrier Reef has bleached during the current event, which the U.S. National Oceanic and Atmospheric Administration warned last month is likely to be “the worst bleaching event” ever observed in the world.

“This new footage shows extensive coral bleaching in southern reefs, but there are images from the central and northern parts that show bleaching is extensive and severe in some of those areas too,” AMCS Great Barrier Reef campaign manager Lissa Schindler said in a statement.

“The Great Barrier Reef is experiencing an unprecedented fifth mass coral bleaching in eight years,” Schindler added. “This is worse than the past two mass bleaching events—in 2020 and 2022—and we may discover as bad as the worst bleaching on record in 2016.”

According to AMCS:

Some regions in the southern reef have experienced unprecedented marine heatwaves, with elevated water temperatures for a record 14.57 degree heating weeks (DHW)—a measure of excessive heat over time—breaking the previous record of 11.8 DWH set in April 2020, according to data from the U.S. government’s world-leading ocean agency, the National Oceanic and Atmospheric Administration.

“I feel devastated. This bleaching event is the worst I have seen. It’s a severe bleaching event,” said Selina Ward, a coral reef expert and the former academic director of the University of Queensland’s Heron Island Research Station.

Ward, who reported extensive bleaching at all 16 sites she just visited along the southern Great Barrier Reef, added: “I’ve been working on the reef since 1992 but this I’m really struggling with. The diversity of species involved has been hard to deal with. Look at bleached areas, there are many different species that are bleached—many of which are pretty resistant to bleaching.”

It’s not just Australia or even the Southern Hemisphere. Following the planet’s hottest summer on record last year, the Caribbean suffered its worst recorded bleaching event.

The last global bleaching occurred in 2014-17, when scientists say approximately 15% of all reefs experienced major coral deaths. Nearly a third of the Great Barrier Reef’s coral perished during that event—a die-off that could be eclipsed this time.

“This bleaching event again brings us to the question, what are we doing to stop the reef from being lost?” Ward asked. “I can’t help but wonder what it is going to take for the right decisions to be made.”

“We are really running out of time. We need to reduce our emissions immediately,” she added. “We cannot expect to save the Great Barrier Reef and be opening new fossil fuel developments. It’s time to act and there are no more excuses.”

Republished from Common Dreams on April 11, 2024.

https://johnmenadue.com/worst-i-have-seen-75-of-great-barrier-reef-suffers-coral-bleaching/

 

 

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