Related Media Releases
Great Barrier Reef risks losing tolerance to bleaching events
ARC Centre of Excellence for Coral Reef Studies
James Cook University Townsville
Queensland 4811 Australia
Phone: 61 7 4781 4000
Email: info@coralcoe.org.au
A new study has found that Great Barrier Reef (GBR) corals were able to survive past bleaching events because they were exposed to a pattern of gradually warming waters in the lead up to each episode. However, this protective pattern is likely to be lost under near future climate change scenarios.
In a paper published in Science today, researchers from ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University (JCU) and the University of Queensland (UQ), as well as the U.S. National Oceanic and Atmospheric Administration USA (NOAA) investigated what this warming pattern means for GBR coral bleaching events into the future.
Lead author Dr. Tracy Ainsworth from Coral CoE explains that bleaching is like a marathon for corals: “When corals are exposed to a pre-stress period in the weeks before bleaching, as temperatures start to climb, this acts like a practice run and prepares the coral. Corals that are exposed to this pattern are then less stressed and more tolerant when bleaching does occur.”
The researchers found that this “practice run” induces heat shock responses in the coral that reduce their severity of bleaching and mortality. The protective “practice run” was observed in three-quarters of stress events that occurred on the GBR in the past three decades.
Early evidence suggests that the 2016 GBR bleaching event has also followed the same pattern. Some individual reefs not previously exposed to bleaching stress at all missed out on the “practice run” this time, suggesting that the damage to the corals on those reefs could be even greater.
The pre-stress conditions are expected to disappear when seawater temperatures rise by as little as 0.5 °C, such as predicted for the near future. Corals will then instead be directly exposed to stress events.
“When corals lose the practice run, there is no break, or “relaxing” for the corals as summer stress develops,” explains co-author Dr. Scott Heron, from Coral Reef Watch at NOAA. “In future summers, bleaching events will occur more often and, without the practice run, become even more severe—with a greater risk for coral mortality and a fast decline in coral cover across reefs.”
The study examined 27 years worth of satellite data for sea surface temperatures, previous coral bleaching events, and studied how corals responded to different seawater warming conditions.
Under future climate change predictions, different reefs on the GBR will lose their protective mechanism at different rates. The study recommends that reefs able to retain the “practice run” of protective conditions prior to bleaching be given high priority for conservation efforts.
“Our models suggest reefs that lose their thermal protection in the future will degrade faster and stay in a degraded state for a longer period, while reefs that maintain their protection have a better chance of maintaining coral cover—if carbon emissions are reduced in the near future,” says Dr. Juan Ortiz from UQ.
Associate Professor Bill Leggat, from Coral CoE adds, “Knowing which temperature patterns are present on different reefs, how these impact coral survival and their capacity to recover from bleaching, and how quickly changes in these patterns occur, will inform reef management. This knowledge will help managers increase the likelihood of coral surviving bleaching events in the future by reducing the impact of other stressors, such as pollution and over-use, at both local and regional scales.”
Professor Peter Mumby, also from Coral CoE concludes, “Our results underscore, once again, the importance of global action to reduce greenhouse gas emissions. We can still have a beautiful reef if people are willing to change behaviour.”
Tracy D. Ainsworth, Scott F. Heron, Juan Carlos Ortiz, Peter J. Mumby, Alana Grech, Daisie Ogawa, C. Mark Eakin, William Leggat (2016). Climate change disables coral bleaching protection on the Great Barrier Reef, Science. : 338-342.
A copy of the paper can be found online at the Science press package webpage. You will need your EurekAlert! user ID and password to access this information.
High resolution images and videos of the 2016 Great Barrier Reef coral bleaching aerial surveys are available for use: https://goo.gl/tqELGR. All photos and videos must be credited: ARC Centre of Excellence for Coral Reef Studies, unless specified otherwise.
Permission must be obtained from the ARC Centre of Excellence for Coral reef Studies to use/re-use all images and footage provided past the media release date.
Tracy Ainsworth, Coral CoE (JCU), (07) 4781 4442, tracy.ainsworth@jcu.edu.au
Bill Leggat, Coral CoE (JCU), 0415 253 820, bill.leggat@jcu.edu.au
Juan Carlos Ortiz, UQ, 0412 200 831, j.ortiz@uq.edu.au
Peter Mumby, Coral CoE (UQ), 0449 811 589, p.j.mumby@uq.edu.au
Scott Heron, NOAA, 0404 893 420, scott.heron@noaa.gov
Melissa Lyne, Coral CoE media liaison, 0415 514 328, Melissa.lyne@gmail.com
Scientists have discovered a never-before-seen biodiversity pattern of coral reef fishes that suggests some fishes might be exceptionally vulnerable to environmental change. A new study shows plank
Scientists say stable seafood consumption amongst the world’s poorer coastal communities is linked to how local habitat characteristics influence fishing at different times of the year. In the co
An international group of scientists is predicting markedly different outcomes for different species of coral reef fishes under climate change – and have made substantial progress on picking the ‘
New research has found as climate change causes the world’s oceans to warm, baby sharks are born smaller, exhausted, undernourished and into environments that are already difficult for them to survi
Abstract: The vast majority of reef fishes have a life history consisting of a pelagic larval phase of typically 20 to 60 days, followed by larval settlement where they remain through their juvenile a
Abstract: Social networks have been and remain important across the Pacific Islands, and beyond, for building and maintaining social-ecological resilience. However, there is little quantitative infor
Abstract: The global conservation community is comprised of a range of organisations, processes, and professionals. Given the diversity of these actors, and the complexity of the systems that conser
Abstract: Seasons create a rhythm in nature and, by extension, in the lives of people who depend directly on natural resources. However, our understanding of how seasons affect the ways that people
Abstract: Oceanic shark populations have declined 77% over the past 60 years as a result of overexploitation in fisheries. However, sustainable shark management is limited to a few developed nations
Abstract: Vertigo3 is a new class of small, fast and agile ‘true-flight’ underwater glider, purposely designed for robotic, artificial intelligence-assisted broadscale marine surveys, and capable
Abstract: Recurrent marine heat waves are leading to widespread coral bleaching, transforming the structure and function of tropical coral reefs. Past bleaching events have highlighted large variatio
Abstract: Shallow-water tropical seascapes typically include a range of habitat types such as coral reefs, mangroves, macroalgal and seagrass beds. These habitats can occur in close proximity and are
ARC Centre of Excellence for Coral Reef Studies
James Cook University Townsville
Queensland 4811 Australia
Phone: 61 7 4781 4000
Email: info@coralcoe.org.au