1

People and ecosystems

Understanding of the links between coral reef ecosystems, the goods and services they provide to people, and the wellbeing of human societies.

2

Ecosystem dynamics: past, present and future

Examining the multi-scale dynamics of reefs, from population dynamics to macroevolution

3

Responding to a changing world

Advancing the fundamental understanding of the key processes underpinning reef resilience.

Coral Bleaching

Coral Bleaching

Coral Reef Studies

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

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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 Hoey of 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.

Citation: Hughes TP, Kerry JT, Connolly SR, Baird AH,  Eakin CM, Heron SF, Hoey AS, Hoogenboom MO, Jacobson M, Liu G, Pratchett MS, Skirving W & Torda G (2019). Ecological memory modifies the cumulative impact of recurrent climate extremes. Nature Climate Change Vol 9, pp 40–43

IMAGES
Link to video and images here.
Please credit as marked.

CONTACTS FOR INTERVIEWS

Prof Terry Hughes
Director, ARC Centre of Excellence for Coral Reef Studies
Phone: +61 (0) 400 720 164, +61 (0)7 4781 4000 (AEST/UTC +10)
Email: terry.hughes@jcu.edu.au

Dr Andrew Hoey
Coral CoE at James Cook University
Townsville, QLD AUSTRALIA
P: +61 7 4781 5979, +61 (0) 0458 174 583 (AEST/UTC +10)
E: andrew.hoey@jcu.edu.au

Dr Mark Eakin
U.S. National Oceanic & Atmospheric Administration
College Park, MD U.S.A.
P: +1 (301) 502 8608 (EST/UTC -5)
E: mark.eakin@noaa.gov

FOR FURTHER INFORMATION

Melissa Lyne, acting Communications Manager
ARC Centre of Excellence for Coral Reef Studies
P: +61 (0) 428 785 895 (AEDT/UTC +11)
E: melissa.lyne@gmail.com

A world-first study has revealed that “robust” reef-building corals are the only known organisms in the animal kingdom to make one of the “essential” amino acids, which may make them less susceptible than other corals to global warming.

Using advanced genomic techniques, a team of researchers led by Dr Hua (Emily) Ying of The Australian National University (ANU) and Prof David Miller of the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University (JCU), have found that the group of corals classified as “robust,” which includes a number of the brain corals and mushroom corals, have a key physiological advantage over “complex” corals, including common branching corals such as the staghorn coral.

In a new paper published today in the prestigious journal Genome Biology, the researchers report that “robust” corals possess a unique capacity to generate an “essential” amino acid.

“Amino acids are the building blocks of life,” said lead author Dr Emily Ying of the ANU Research School of Biology.

“They are crucial, for example, in repairing tissue or growing new tissue. But, generating amino acids is energetically costly for animals, so they usually only generate 11 of the 20 required for life.”

“The remaining nine amino acids are called the ‘essential’ amino acids because they must be supplied by the animal’s diet. For corals, this includes tiny drifting animals known as ‘zooplankton.’”

But this is not the only form of sustenance for corals. Through a mutually-beneficial relationship with microalgae known as Symbiodinium, corals are supplied the energy needed to build their hard skeletons.

Symbiodinium also supplies the coral with some of the ‘essential’ amino acids, making them less dependent on their diet than other animals,” said senior author Prof David Miller of Coral CoE at JCU.

For example, when global warming causes corals to bleach, they expel their resident Symbiodinium and are therefore suddenly fully dependent on their diet to meet this nutritional requirement.

“We now know that ‘robust’ corals can make at least one of the ‘essential’ amino acids without relying on Symbiodinium. This suggests that they may be more resilient, at least in the short term, to bleaching than the ‘complex’ corals such as the branching staghorns,” explained Prof Miller.

Until now, scientists had few clues about why some corals only host a specific Symbiodinium type and others are less particular.

“Our research also suggests that ‘robust’ corals are less choosey about which species of microalgae can take up residence in the coral’s tissue. The ability to host a broader range of Symbiodinium types could facilitate more rapid acclimation to higher temperatures,” said Prof Miller.

 

Note to editor:

• Since 1996, coral taxonomists have recognised the existence of two “superfamilies” of reef-building corals: “robust” and “complex.”

Symbiodinium is a photosynthetic micro-alga that has a mutually beneficial relationship with reef-building corals – in exchange for the stable environment inside the coral cells, it supplies most of the energy needs of the host animal.

• Coral bleaching is the loss of Symbiodinium by coral hosts when they are stressed –especially by high temperatures. Symbiodinium cells depart from stressed corals, which makes the corals pale.

Citation: Ying, H, Cooke, I, Sprungala, S, Wang, W, Hayward, DC, Tang, Y, Huttley, G, Ball, EE, Forêt, S, Miller, DJ (2018) Comparative genomics reveals the distinct evolutionary trajectories of the robust and complex coral lineages. Genome Biology 19:175 DOI: 10.1186/s13059-018-1552-8

Visuals available here

 

CONTACTS

Prof David Miller
Coral CoE at JCU
Townsville, Queensland
E: david.miller@jcu.edu.au

Dr Hua Ying
ANU Research School of Biology
Canberra, ACT
E: Hua.Ying@anu.edu.au

More information

Catherine Naum, Communications Mgr
Coral CoE
T: +61 (7) 4781 6067
M: +61 (0) 428 785 895
E: catherine.naum1@jcu.edu.au

 

Check out Prof. Miller’s related talk from the 2018 “Coral Reef Futures” Symposium:

Researchers have found that when water temperatures heat up for corals, fish ‘tempers’ cool down, providing the first clear evidence of coral bleaching serving as a trigger for rapid change in reef fish behaviour.

Publishing in Nature Climate Change this week, researchers from Lancaster University and collaborating institutes including the ARC Centre of Excellence for Coral Reef Studies (Coral CoE) at James Cook University show how the iconic butterflyfish, considered to be sensitive indicators of reef health, can offer an early warning sign that reef fish populations are in trouble.

The international team of researchers spent more than 600 hours underwater observing butterflyfish over a two-year period encompassing the unprecedented mass coral bleaching event of 2016.

Led by Dr. Sally Keith of Lancaster University, previously Center for Macroecology, Evolution and Climate, the team examined 17 reefs across the central Indo-Pacific in Japan, the Philippines, Indonesia and Christmas Island (Indian Ocean).

During the initial data collection, the researchers were unaware that the catastrophic bleaching event was on the horizon. Once underway, the researchers realised that this serendipitous ‘natural experiment’ placed them in a unique position to see how fish changed their behaviour in response to large-scale bleaching disturbance.

The team sprang into action to repeat their field observations, collecting a total of 5,259 encounters between individuals of 38 different butterflyfish species. Within a year after the bleaching event it was clear that, although the same number of butterflyfishes continued to reside on the reefs, they were behaving very differently.

“We observed that aggressive behaviour had decreased in butterflyfish by an average of two thirds, with the biggest drops observed on reefs where bleaching had killed off the most coral,” said Dr Keith. “We think this is because the most nutritious coral was also the most susceptible to bleaching, so the fish moved from a well-rounded diet to the equivalent of eating only lettuce leaves – it was only enough to survive rather than to thrive.”

Such changes in behaviour may well be the driver behind more obvious changes such as declining numbers of fish individuals and species. The finding has the potential to help explain the mechanism behind population declines in similarly disrupted ecosystems around the world.

Co-author Dr. Erika Woolsey of Stanford University said: “By monitoring behaviour, we might get an early warning sign of bigger things to come.”

“Our work highlights that animals can adjust to catastrophic events in the short term through flexible behaviour, but these changes may not be sustainable in the longer-term,” added co-author Prof Andrew Baird of Coral CoE at James Cook University.

The paper “Synchronous behavioural shifts  in reef fishes linked to mass coral bleaching” is available online here.

Citation: Keith, SA, Baird, AH, Hobbs, J-PA, Woolsey, ES, Hoey, AS, Fadli, N, Sanders, NJ (2018) Synchronous behavioural shifts in reef fishes linked to mass coral bleaching. Nature Climate Change 8:986-991

Visuals available here.

Video abstract here.

 

CONTACTS

Sally A. Keith, PhD (UNITED KINGDOM)
Lancaster University
E: sally.keith@lancaster.ac.uk
Twitter: @Sal_Keith

Beth Broomby, Head of Press Office
Lancaster University
O: +44 (0) 1524 593719
M: +44 (0) 7881813831

Prof Andrew Baird (AUSTRALIA) – available for comment from 29 October
ARC Centre of Excellence for Coral Reef Studies
James Cook University
E: andrew.baird@jcu.edu.au

Catherine Naum, Communications Manager
ARC Centre of Excellence for Coral Reef Studies
E: catherine.naum1@jcu.edu.au

 

A new study published online today in Nature shows that corals on the northern Great Barrier Reef experienced a catastrophic die-off following the extended marine heatwave of 2016.

“When corals bleach from a heatwave, they can either survive and regain their colour slowly as the temperature drops, or they can die. Averaged across the whole Great Barrier Reef, we lost 30 per cent of the corals in the nine month period between March and November 2016,” said Prof Terry Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies (Coral CoE).

The scientists mapped the geographical pattern of heat exposure from satellites, and measured coral survival along the 2,300-km length of the Great Barrier Reef following the extreme marine heatwave of 2016.

The amount of coral death they measured was closely linked to the amount of bleaching and level of heat exposure, with the northern third of the Great Barrier Reef being the most severely affected. The study found that 29 per cent of the 3,863 reefs comprising the world’s largest reef system lost two-thirds or more of their corals, transforming the ability of these reefs to sustain full ecological functioning.

“The coral die-off has caused radical changes in the mix of coral species on hundreds of individual reefs, where mature and diverse reef communities are being transformed into more degraded systems, with just a few tough species remaining,” said co-author Prof Andrew Baird of Coral CoE at James Cook University.

“As part of a global heat and coral bleaching event spanning 2014-2017, the Great Barrier Reef experienced severe heat stress and bleaching again in 2017, this time affecting the central region of the Great Barrier Reef,” said co-author Dr Mark Eakin of the U.S. National Oceanic and Atmospheric Administration.

“We’re now at a point where we’ve lost close to half of the corals in shallow-water habitats across the northern two-thirds of the Great Barrier Reef due to back-to-back bleaching over two consecutive years,” said Prof Sean Connolly of Coral CoE at James Cook University.

“But, that still leaves a billion or so corals alive, and on average, they are tougher than the ones that died. We need to focus urgently on protecting the glass that’s still half full, by helping these survivors to recover,” said Prof Hughes.

The scientists say these findings reinforce the need for assessing the risk of a wide-scale collapse of reef ecosystems, especially if global action on climate change fails to limit warming to 1.5‒2 °C above pre-industrial levels.

The study is unique because it tests the emerging framework for the International Union for Conservation of Nature (IUCN) Red List of Ecosystems, which seeks to classify vulnerable ecosystems as ‘safe,’ ‘threatened’ or ‘endangered.’

“The Great Barrier Reef is certainly threatened by climate change, but it is not doomed if we deal very quickly with greenhouse gas emissions. Our study shows that coral reefs are already shifting radically in response to unprecedented heatwaves,” said Prof Hughes.

The researchers warn that failure to curb climate change, causing global temperatures to rise far above 2 °C, will radically alter tropical reef ecosystems and undermine the benefits they provide to hundreds of millions of people, mostly in poor, rapidly-developing countries.”

 

Citation: Hughes, TP, Kerry, JT, Baird, AH,Connolly, SR, Dietzel, A, Eakin, CM, Heron, SF, Hoey, AS, Hoogenboom, MO, Liu, G, McWilliam, MJ, Pears, R., Pratchett, MS, Skirving, WJ, Stella, JS and Torda, G (2018). Global warming transforms coral reef assemblages. Nature  doi:10.1038/s41586-018-0041-2

 

IMAGES

Link to video and images here. Please credit as marked.

CONTACTS FOR INTERVIEWS

Prof Terry Hughes
Director, ARC Centre of Excellence for Coral Reef Studies
Phone: +61 (0) 400 720 164 (AEST/UTC +10)
E-mail: terry.hughes@jcu.edu.au

Prof Sean Connolly
ARC Centre of Excellence for Coral Reef Studies at James Cook University
Phone: +61 (0)7 4781 4242 (AEST/UTC +10)
Email: sean.connolly@jcu.edu.au

Prof Andrew Baird
ARC Centre of Excellence for Coral Reef Studies at James Cook University
Phone: +61 (0) 400 289 770 (AEST/UTC +10)
Email: andrew.baird@jcu.edu.au

C. Mark Eakin, Ph. D.
U.S. National Oceanic & Atmospheric Administration
College Park, MD U.S.A.
Phone: +1 (301) 502 8608 (EST/UTC -5)
Email: mark.eakin@noaa.gov

FOR FURTHER INFORMATION

Catherine Naum
Communications Manager
ARC Centre of Excellence for Coral Reef Studies at James Cook University
Phone: +61 (0)7 4781 6067, +61 (0) 428 785 895 (AEST/UTC +10)
Email: catherine.naum1@jcu.edu.au

The world’s reefs are under siege from global warming, according to a novel study published today in the prestigious journal Science.

For the first time, an international team of researchers has measured the escalating rate of coral bleaching at locations throughout the tropics over the past four decades. The study documents a dramatic shortening of the gap between pairs of bleaching events, threatening the future existence of these iconic ecosystems and the livelihoods of many millions of people.

“The time between bleaching events at each location has diminished five-fold in the past 3-4 decades, from once every 25-30 years in the early 1980s to an average of just once every six years since 2010,” says lead author Prof Terry Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies (Coral CoE).

“Before the 1980s, mass bleaching of corals was unheard of, even during strong El Niño conditions, but now repeated bouts of regional-scale bleaching and mass mortality of corals has become the new normal around the world as temperatures continue to rise.”

The study establishes a transition from a period before the 1980s when bleaching only occurred locally, to an intermediate stage in the 1980s and 1990s when mass bleaching was first recorded during warmer than average El Niño conditions, and finally to the current era when climate-driven bleaching is now occurring throughout ENSO  (El Niño-Southern Oscillation) cycles.

The researchers show that tropical sea temperatures are warmer today during cooler than average La Niña conditions than they were 40 years ago during El Niño periods.

“Coral bleaching is a stress response caused by exposure of coral reefs to elevated ocean temperatures. When bleaching is severe and prolonged, many of the corals die. It takes at least a decade to replace even the fastest-growing species,” explained co-author Prof Andrew Baird of Coral CoE.

“Reefs have entered a distinctive human-dominated era – the Anthropocene,” said co-author, Dr C. Mark Eakin of the National Oceanic & Atmospheric Administration, USA. “The climate has warmed rapidly in the past 50 years, first making El Niños dangerous for corals, and now we’re seeing the emergence of bleaching in every hot summer.”

“For example, the Great Barrier Reef has now bleached four times since 1998, including for the first time during back-to-back events in 2016 and 2017, causing unprecedented damage,” explained Prof Hughes. “Yet the Australian government continues to support fossil fuels.”

“We hope our stark results will help spur on the stronger action needed to reduce greenhouse gases in Australia, the United States and elsewhere,” says Prof Hughes.

The paper “Spatial and temporal patterns of mass bleaching of corals in the Anthropocene” is now available here.

IMAGES

Images must carry credits as listed in Dropbox folder:
https://www.dropbox.com/sh/81s55plybbqz04b/AACuFcDjnP_-Ywid9RXsVdEKa?dl=0

CONTACTS FOR INTERVIEWS

Prof Andrew Baird
ARC Centre of Excellence for Coral Reef Studies at James Cook University
Phone: +61 (0) 400 289 770 (currently in Sydney, AEDT/UTC +11)
Email: Andrew.Baird@jcu.edu.au

Associate Professor Julia Baum
University of Victoria, Department of Biology
Victoria, BC CANADA
Phone: 1-250-858-9349 (PST/UTC -8)
Email: baum@uvic.ca

Associate Professor Michael Berumen
King Abdullah University of Science and Technology, Red Sea Research Center
Thuwal, SAUDI ARABIA
Phone: +966 544 700 019 (available from 3-4 Jan, MSK/UTC + 3; 5-7 Jan, CET/UTC + 1)
Email: michael.berumen@kaust.edu.sa

C. Mark Eakin, Ph. D.
National Oceanic & Atmospheric Administration
Silver Spring, MD U.S.A.
Phone: 1-301-502-8608  (EST/UTC -5)
Email: mark.eakin@noaa.gov

Prof Nicholas Graham
Lancaster University, Lancaster Environment Centre
Lancaster, UNITED KINGDOM
Tel: +44 (0) 7479 438 914 (available from 4 Jan, GMT/UTC)
Email: nick.graham@lancaster.ac.uk

Prof Terry Hughes
Director, ARC Centre of Excellence for Coral Reef Studies
Townsville, QLD AUSTRALIA
Phone: +61 (0) 400 720 164 (NZDT/UTC +13)
Email: Terry.Hughes@jcu.edu.au

FOR MORE INFORMATION

Catherine Naum
Communications Manager
ARC Centre of Excellence for Coral Reef Studies at James Cook University
Townsville, QLD AUSTRALIA
Phone: +61 (0)7 4781 6067, +61 (0) 428 785 895 (AEST/UTC +10)
Email: Catherine.Naum1@jcu.edu.au

Researchers from The University of Western Australia (UWA), ARC Centre of Excellence for Coral Reef Studies (Coral CoE), and Western Australian Marine Science Institution have examined the impact of the 2016 mass bleaching event on reefs in Western Australia (WA). They found significant bleaching occurred in the inshore Kimberley region, despite Kimberley corals being known as exceptionally stress resistant. They also found mild bleaching at Rottnest Island and that the Ningaloo Reef escaped bleaching.

The 2016 mass bleaching event is the most severe global bleaching event to ever be recorded.

Coral bleaching occurs as the result of abnormal environmental conditions, such as heightened sea temperatures that cause corals to expel tiny photosynthetic algae, called ‘zooxanthellae.’ The loss of these colourful algae causes the corals to turn white, and ‘bleach’. Bleached corals can recover if the temperature drops and zooxanthellae are able to recolonise the coral, otherwise the coral may die.

The researchers, led by Coral CoE’s Dr Verena Schoepf and UWA Masters student Morane Le Nohaïc, conducted surveys on the health of coral reefs along the Western Australian coastline from tropical to temperate locations.

“We found a concerning 57 to 80 per cent of corals on inshore Kimberley reefs were bleached in April 2016 – this included Montgomery Reef, Australia’s largest inshore reef,” Dr Schoepf said.

“Our research also found that there was mild bleaching at Rottnest Island – 29 per cent of corals were moderately bleached.”

“Ningaloo Reef, a UNESCO World Heritage site, escaped bleaching, but had some temperature-unrelated coral mortality. Temperate corals at Bremer Bay (Southwest) experienced no bleaching.”

Dr Schoepf said bleaching patterns were consistent with patterns of heat stress across WA.

“This is the first documented regional-scale bleaching event in WA during an El Nino year and the first time we have been able to measure the percentage of impacted corals in 2016,” she said.

“Coral reefs in WA are now at risk of bleaching during both El Nino years, such as in 2016, and La Nina years, such as 2010/11. But the geographic footprint differs – the northwest is at risk during El Nino years, whereas Ningaloo Reef and reefs further south are at risk during the La Nina cycle.”

“As bleaching events become more common in the future, it is critical to monitor how bleaching events impact coral reef resilience, and how long it takes reefs to recover from such catastrophic events.”

The research paper “Marine heatwave causes unprecedented regional mass bleaching of thermally resistant corals in northwestern Australia” is published today in the journal Scientific Reports.

IMAGES
Images must carry credits as listed in Dropbox folder:
https://www.dropbox.com/sh/tb0j31f5c1drbuc/AADj548hmYArKk_8MzMPrYioa?dl=0

FOR INTERVIEWS, PLEASE CONTACT:

Dr Verena Schoepf
ARC Centre of Excellence for Coral Reef Studies at University of Western Australia
Phone: (+61 8) 6488 4596 / (+61 4) 16 540 415
Email: verena.schoepf@uwa.edu.au

Ms Catherine Naum
Communications Manager
ARC Centre of Excellence for Coral Reef Studies
Phone: (+61 7) 4781 6067 / (+61 4) 28 785 895
Email: catherine.naum1@jcu.edu.au

For the second time in just 12 months, scientists have recorded severe coral bleaching across huge tracts of the Great Barrier Reef after completing aerial surveys along its entire length. In 2016, bleaching was most severe in the northern third of the Reef, while one year on, the middle third has experienced the most intense coral bleaching.

“The combined impact of this back-to-back bleaching stretches for 1,500 km (900 miles), leaving only the southern third unscathed,” says Prof. Terry Hughes, Director of the ARC Centre of Excellence for Coral Reef Studies, who undertook the aerial surveys in both 2016 and 2017.

“The bleaching is caused by record-breaking temperatures driven by global warming. This year, 2017, we are seeing mass bleaching, even without the assistance of El Niño conditions.”

The aerial surveys in 2017 covered more than 8,000 km (5,000 miles) and scored nearly 800 individual coral reefs closely matching the aerial surveys in 2016 that were carried out by the same two observers.

Dr. James Kerry, who also undertook the aerial surveys, explains further, “this is the fourth time the Great Barrier Reef has bleached severely – in 1998, 2002, 2016, and now in 2017. Bleached corals are not necessarily dead corals, but in the severe central region we anticipate high levels of coral loss.”

“It takes at least a decade for a full recovery of even the fastest growing corals, so mass bleaching events 12 months apart offers zero prospect of recovery for reefs that were damaged in 2016.”

Coupled with the 2017 mass bleaching event, Tropical Cyclone Debbie struck a corridor of the Great Barrier Reef at the end of March. The intense, slow-moving system was likely to have caused varying levels of damage along a path up to 100 km in width. Any cooling effects related to the cyclone are likely to be negligible in relation to the damage it caused, which unfortunately struck a section of the reef that had largely escaped the worst of the bleaching.

“Clearly the reef is struggling with multiple impacts,” explains Prof. Hughes. “Without a doubt the most pressing of these is global warming. As temperatures continue to rise the corals will experience more and more of these events: 1°C of warming so far has already caused four events in the past 19 years.”

“Ultimately, we need to cut carbon emissions, and the window to do so is rapidly closing.”

MULTIMEDIA: A selection of photos and videos and key graphic (see below) *Images must carry credits as listed in Dropbox folder*

Key graphic 2016 -2017_GBRbleaching.jpg (high and low res versions available)

This composite map shows surveyed coral reefs in 2016 (left panel) and 2017 (right panel).

Not all data is shown, only reefs at either end of the bleaching spectrum: Red circles indicate reefs undergoing most severe bleaching (60% or more of visible corals bleaching) Green circles indicate reefs with no or only minimal bleaching (10% or less of corals bleaching).

 

CONTACTS:

Prof. Terry Hughes

Director, ARC Centre of Excellence for Coral Reef Studies

Phone: +61 (0)400 720 164, +61 (0)7 4781 4000

Email: Terry.Hughes@jcu.edu.au

Dr. James Kerry

Senior Research Officer, ARC Centre of Excellence for Coral Reef Studies

Phone: +61 (0)407 475 576, +61 (0)7 4781 4823

Email: james.kerry1@jcu.edu.au

Prof. Sean Connolly

Chief Investigator, ARC Centre of Excellence for Coral Reef Studies

Phone: +61 (0)7 4781 4242

Email: sean.connolly@jcu.edu.au

Melissa Lyne

Communications Manager, ARC Centre of Excellence for Coral Reef Studies

Phone: +61 (0)415 514 328

Email: Melissa.lyne@jcu.edu.au

 

Note for editors

The two observers: Prof Terry Hughes and Dr. James Kerry work at the ARC Centre of Excellence for Coral Reef Studies at James Cook University in Townsville, Australia. The Centre for World University Rankings recently ranked this institution number 1 globally for Marine and Freshwater biology research.

The aerial survey techniques used in this study were employed consistently in all four bleaching events on the Great Barrier Reef: 1998, 2002, 2016 and 2017. They were backed up by extensive in-water research during the 2016 event and published in the peer-reviewed journal, Nature. (Link to journal)

Coral bleaching occurs when abnormal environmental conditions, like heightened sea temperatures, cause corals to expel tiny photosynthetic algae, called ‘zooxanthellae’. The loss of these colorful algae causes the corals to turn white, and bleach͛. Bleached corals can recover if the temperature drops and zooxanthellae are able to recolonise them, otherwise the coral may die.

In the six months following the peak of bleaching in March 2016, scientists measured on average 67% loss of corals in the northern 700 km section of the Great Barrier Reef, which was the worst impacted section in that year. An interactive map of images and video of aerial survey footage from the 2016 event can be found here.

 

 

 

 

 

 

 

 

A study has found that coral with high levels of fat or other energy reserves can withstand the impact of annual coral bleaching events, compared to coral with lower levels of fat reserves.

Coral bleaching events occur when sea temperatures rise as the result of climate change. This results in the breakdown of the symbiosis between the coral and their zooxanthellae (which gives coral most of its colour) and threatens the survival of the coral.

The study was carried out by scientists from The University of Western Australia’s Oceans Institute and the ARC Centre of Excellence for Coral Reef Studies, The Ohio State University’s School of Earth Sciences and the University of Delaware’s School of Marine Science and Policy.

Lead author, Dr Verena Schoepf from the ARC Centre of Excellence for Coral Reef Studies at UWA and a Research Associate from the Oceans Institute, says tropical coral is extremely sensitive to heat stress.

“Three global bleaching events have already occurred since the 1980s and will likely occur annually later this century. Therefore, it has become more urgent than ever to know how tropical coral can survive annual bleaching – one of the major threats to coral reefs today,” she said.

“Already bleaching events have resulted in significant amounts of coral dying causing impact to ocean ecosystems, but up until now it was largely unknown whether coral could recover between annual bleaching events.”

Dr Schoepf says the research which simulated annual coral bleaching found some species of coral such as the mustard hill coral (Porites astreoides) were severely affected by repetitive bleaching events, but other coral such as the finger coral (Porites divaricata) and the mountainous star coral (Orbicella faveolata) could recover quickly.

“When coral is bleached, it no longer gets enough food energy and so it starts slowing down in growth and loses its fat and other energy reserves – just like humans do during times of hardship,” she says.

“The coral then becomes increasingly weak and susceptible to disease, and when bleaching is prolonged, it can die.”

Dr Andrea Grottoli from The Ohio State University’s School of Earth Sciences says over the next decades, coral bleaching events were likely to occur more and more frequently and increasingly impact coral reefs around the world, contributing to their worldwide decline.

“Bleaching will significantly change the future of coral reefs with heat sensitive coral unable to recover,” Dr Grottoli says.

“Our research will help with predicting the persistence of coral reefs because knowledge of their capacity to recover from annual bleaching is critical information for these models.”

The research, which was funded by the USA National Science Foundation to Drs. Grottoli and Warner, will be published in the international journal Proceedings of the Royal Society B: Biological Sciences here on Wednesday 18 November.

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Contacts:

Dr Verena Schoepf  –  (+61 8) 6488 3644

Jess Reid (UWA Media)    (+61 8) 6488 6876

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