Climate extremes triggered rare coral disease and mass mortality on the Great Barrier Reef

Findings suggest climate change is happening too quickly for corals to adjust.

Peer-Reviewed Publication

University of Sydney

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Lead author Professor Maria Byrne from the University of Sydney on the Great Barrier Reef.

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Credit: The University of Sydney

University of Sydney marine biologists have identified a devastating combination of coral bleaching and a rare necrotic wasting disease that wiped out large, long-lived corals on the Great Barrier Reef during the record 2024 marine heatwave.

The study, led by Professor Maria Byrne and Sydney Horizon Fellow Dr Shawna Foo, found that bleaching triggered by extreme ocean temperatures was followed by an unprecedented outbreak of black band disease that killed massive Goniopora corals, also known as flowerpot or daisy coral, at One Tree Reef on the southern Great Barrier Reef.

“This research shows that the compounding impact of disease – which appeared after the onset of bleaching – is what killed the Goniopora. These are very long-lived corals that would normally survive bleaching,” said Professor Byrne, a professor of marine biology in the School of Life and Environmental Sciences.

Their study is published today in Proceedings of the Royal Society B.

Black band disease is a bacterial necrotic infection that invades living coral, forming a black band that crosses the infected coral, usually killing the colony. Common in Caribbean reefs, it is rare in Australian waters.

The 2024 El Niño brought the highest sea temperatures on record to the Great Barrier Reef, with marine heatwave conditions persisting for months. During this period, 75 percent of Goniopora colonies at One Tree Reef bleached. Initially only a few (4 percent) showed signs of black band disease. By April, however, the disease had spread aggressively, invading more than half the bleached colonies.

Tracking 112 tagged Goniopora colonies over a year, the team found that three-quarters had died by October 2024, while only one quarter showed partial recovery. Population surveys of more than 700 colonies revealed the same pattern: widespread bleaching, rapid disease progression and high mortality.

Black band disease has been known for decades in the Caribbean, often linked to pollution or nutrient runoff, but it is extremely rare on the Great Barrier Reef. Its sudden appearance in One Tree Reef’s pristine waters marks the first recorded epizootic (an animal epidemic) event of this kind on the Great Barrier Reef and demonstrates how heat stress can turn even resilient coral species into disease victims.

“Normally these massive corals withstand environmental stress, but the combination of record heat and infection was catastrophic,” said Dr Shawna Foo, an ARC DECRA Fellow in the School of Life and Environmental Sciences. “It’s a stark example of how multiple stressors can act together to undermine reef resilience.”

The findings highlight the importance of long-term in-water monitoring made possible by the University’s One Tree Island Research Station, which provides vital infrastructure for studying coral ecosystems under natural conditions.

At the global level, the research sends an urgent warning.

“The current trajectory of climate change is progressing too quickly for corals to adjust,” the authors write. “Coral reefs are in danger, with recurrent anomalous heatwaves and mass coral bleaching being the greatest threat to their survival.”

Professor Byrne said the loss of these large, structure-forming corals will have lasting effects on reef biodiversity, coastal protection and food security.

“Coral reefs support more than a billion people worldwide. What we’re witnessing is a collapse in the natural resilience of these ecosystems. Ambitious global action to reduce emissions is now the only path to their survival.”

Download photos and videos of affected corals and the research at this link.

Interviews

Professor Maria Byrne | maria.byrne@sydney.edu.au | +61 452 176 609

Dr Shawna Foo | shawna.foo@sydney.edu.au

Media enquiries

Marcus Strom | marcus.strom@sydney.edu.au | +61 474 269 459

Outside of work hours, please call +61 2 8627 0246 (directs to a mobile number) or email media.office@sydney.edu.au. 

Research

Byrne, M. et al ‘Marine heatwave-driven mortality of bleached colonies of the massive coral Goniopora is exacerbated by a black band disease epizootic’. (Proceedings of the Royal Society B: Biological Sciences 2025). DOI: 10.1098/rspb.2025.1912

Declaration

The authors declare no competing interests. Funding was received from the Australian Research Council

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Journal

Proceedings of the Royal Society B Biological Sciences

DOI

10.1098/rspb.2025.1912 

Method of Research

Observational study

Subject of Research

Animals

Article Title

Marine heatwave-driven mortality of bleached colonies of the massive coral Goniopora is exacerbated by a black band disease epizootic

Article Publication Date

10-Dec-2025

Affected Goniopora cluster in February on One Tree Island at the Great Barrier Reef. With swimmer for scale

Goniopora coral cluster infected with black band disease at One Tree Island on the Great Barrier Reef.

Coral infected with black band disease at One Tree Island on the Great Barrier Reef.

Credit

The University of Sydney

 

Ocean current and seabed shape influence warm water circulation under ice shelves

University of East Anglia

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Autonomous underwater vehicle Boaty McBoatface was used to gather data from underneath the Dotson Ice Shelf.

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Credit: Hannah Wyles

New research reveals how the speed of ocean currents and the shape of the seabed influence the amount of heat flowing underneath Antarctic ice shelves, contributing to melting.

Scientists at the University of East Anglia (UEA) used an autonomous underwater vehicle to survey beneath the Dotson Ice Shelf in the Amundsen Sea, an area of rapid glacial ice loss largely due to increasing ocean heat around and below ice shelves.

The circulation of warm water and the heat transport within ice shelf cavities - significant areas beneath ice shelves - remains mostly unknown. To address this the team collected data from over 100 kilometres of dive tracks the underwater robot made along the seabed in the Dotson cavity.

The findings are published today in the journal Ocean Sciences.

Lead author Dr Maren Richter, from UEA’s Centre for Ocean and Atmospheric Sciences, said: “Upward transport of deep warm water to the shallower ice-ocean boundary in ice shelf cavities is what drives melting at the underside of the ice shelf. This melting makes the ice shelf thinner, and therefore less strong.

“We found that while there is mixing of warm water with other, cooler, water, under the Dotson Ice Shelf most of the warm water is not mixed upward. Instead, it flows horizontally to the grounding line, the point where the glacier loses contact with the seabed and starts to float.

“This means that the water stays warm all the way to the grounding line, where it can melt the glacier directly. This can cause the glacier to retreat, speed up and lose more ice into the ocean. Together, the retreat, increased speed, and increased melt contribute to sea level rise globally.”

During the mission, the first of its kind under the Dotson Ice Shelf, the researchers found warm, salty water below colder, fresher water. It is already known that warm water is transported upward by mixing, however this study shows that the mixing and upward transport of warm water are strongest in the inflow areas to the east of the ice shelf, where the currents are faster and the seabed is steep, with the gradient of the bedrock being particularly significant.

Current speeds recorded in this area by the Autosub Long Range (ALR) autonomous underwater vehicle - named Boaty McBoatface and operated by the National Oceanography Centre - were around five centimetres per second up to 10 centimetres per second. The gradient was about 45 degrees in the steepest areas.

Dr Richter added: “We were expecting the influence of current speed on the mixing to be much higher than what we found. Instead, the shape of the seabed seems to be really important.

“We also found water in the deepest part of the cavity that was surprisingly warm, and we are now working to explain how and when it got there.” 

The data was collected over four missions in 2022 when Boaty, equipped with sensors to measure properties of the water including temperature, current, turbulence (mixing) and oxygen, travelled along the bottom of the ice shelf cavity, staying about 100 metres above the seabed. Boaty was in the cavity for approximately 74 hours.

Missions to send a robot into an ice shelf cavity and then get it back at the end are very difficult, and ones with an instrument that can measure mixing are especially rare.

“This mission was the first of its kind under the Dotson Ice Shelf,” said Dr Richter. “We gained very valuable baseline measurements which can now be compared to assumptions about mixing in regional and global models of ice shelf-ocean interactions, and to measurements under other ice shelf cavities, helping us understand how these cavities are similar or different from each other.”

Warm deep water that is mixed upward not only increases the temperature in the upper ocean, it can also transport nutrients and trace-metals upward, which is very important for local algae blooms and the creatures that depend on them for food.

While this study did not measure nutrient transports through mixing, the data can be used by other researchers who want to calculate the effects of mixing in the cavity. 

The work was carried out as part of a project for the International Thwaites Glacier Collaboration, a major five-year research programme aiming to understand what is causing ice loss and better predict how this could contribute to sea level rise. It was funded by the UK’s Natural Environment Research Council and the US National Science Foundation.

‘Observations of turbulent mixing in the Dotson Ice Shelf cavity’, Maren Richter, Karen Heywood, Rob Hall and Peter Davis, is published in Ocean Sciences on December 10.

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Method of Research

Data/statistical analysis

Subject of Research

Not applicable

Article Title

‘Observations of turbulent mixing in the Dotson Ice Shelf cavity

Article Publication Date

10-Dec-2025

 

Call to increase funding for ‘invisible’ Deaf victim-survivors of domestic abuse

Heriot-Watt University

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Professor Jemina Napier, Chair of Intercultural Communication at Heriot-Watt University.

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Credit: Heriot-Watt University

A new report warns Deaf women experiencing domestic abuse in Scotland remain “effectively invisible” due to the chronic absence of specialist services and a lack of coordinated national support. Researchers say this gap leaves deaf victim-survivors without meaningful access to safety and advocacy.

 

Led by Heriot-Watt University and the University of Edinburgh, the British Academy-funded Sign LOUD report highlights that Scotland currently has no national dedicated British Sign Language (BSL) support services for Deaf victim-survivors of domestic abuse, despite evidence that Deaf women are two to three times more likely to experience abuse than the general population.

 

The report recommends establishing a BSL Equally Safe Advisory Group, bringing together Deaf community organisations, domestic abuse organisations, and officials responsible for the Scottish Government’s Equally Safe strategy and BSL National Plan. This group would work on action to improve the response of all frontline services as well as dedicated specialist support.

 

Professor Jemina Napier, Chair of Intercultural Communication in Heriot-Watt’s School of Social Sciences is Principal Investigator for the research who said: “Deaf women have been overlooked for years, despite being at high risk and having distinct language access needs. Aside from a small, fixed-term pilot across Angus, Tayside and Perthshire led by the Dundee-based charity Deaf Links, there is no dedicated service in Scotland. This must change.”

 

While specialist services exist in England such as SignHealth and the Cambridgeshire Deaf Association, Scotland relies solely on the temporary initiative operated by Deaf Links in Tayside and Women’s Aid groups, which are limited to local regions.

 

Deaf mothers and signing practitioners included in the study stressed the urgent need for support for both deaf and hearing children affected by domestic abuse. Many reported situations where children were expected to interpret during safeguarding conversations, placing them in highly stressful and inappropriate roles.

 

Dr Claire Houghton, the Co-Investigator on the study and a Senior Lecturer in Social Policy and Qualitative Research at the University of Edinburgh, said: “We heard repeatedly about children being asked to interpret conversations between their deaf mothers and statutory service providers in domestic abuse situations. 

 

“This compromises safeguarding and emotional wellbeing for both deaf mothers and their children. National support must include provision for children.”

 

Among its other findings, the report calls for dedicated, long-term funding for domestic abuse services that are offered directly in BSL for Deaf women and families, echoing recommendations from the Scottish Government’s Independent Strategic Review of Funding and Commissioning of Services on Violence Against Women and Girls. It also highlights a need for improved access in BSL to mainstream (hearing) services through interpreters.

 

A parliamentary roundtable hosted by MSP Karen Adam was recently held in Holyrood to discuss the findings and explore how Scotland can deliver equitable support for Deaf women and children.

 

“Deaf women and children have been hidden in plain sight,” Professor Napier said. “If we want services to be truly equitable, we must recognise their needs and act.”

 

Karen Adam MSP for Banffshire & Buchan Coast said the report not only identified the problems but offered a way forward.

 

”Deaf women experiencing domestic abuse are too often hit by a double trauma of the abuse itself, and then the barriers they face in getting help in their own language,” she said.

 

“The Sign LOUD project has shone a light on that reality and made it impossible to ignore.

 

“I hosted the roundtable in Parliament because these findings now need to be turned into action, on BSL access, on specialist support, and on making sure Deaf women and their children are properly supported in the systems meant to protect them.

 

“I’m very pleased that the Deputy First Minister joined us in her capacity as Minister for Languages, because language policy and BSL provision are absolutely central to making sure that safety, support and justice are genuinely accessible to Deaf women and their children.”

 

The 32-page study gathered first-hand accounts from of six Deaf mothers who are victim-survivors and five signing practitioners who use BSL to support Deaf women.

 

Among the Sign LOUD team supporting this activity was Lucy Clark, a Deaf victim-survivor who is a researcher and advocate of domestic abuse in the deaf community.

 

“As a survivor, I see many gaps that continue to delay recovery for BSL users,” she said.

 

“We urgently need greater awareness of the importance of specialist support for Deaf women and children, including access to qualified BSL interpreters and services that demonstrate real Deaf Awareness.

 

“BSL resources must expand so we can reach more people, break down barriers, and ensure that BSL is properly recognised and valued.”

 

Adding their insight to the project was Tasnim Ahmed, Operations Manager of the Scottish Ethnic Minority Deaf Charity and a Deaf victim-survivor who was a participatory consultant for the report, who said: “Being involved in this research has shown me just how urgent the need is for specialist support for Deaf women, particularly those from ethnic minority communities. Accessible, culturally appropriate services in BSL could make a real difference - helping women and children access safety, support, and advocacy with dignity and equality."

 

The Sign LOUD report is being publicly launched on International Human Rights Day which is observed every year on December 10 to commemorate the United Nations’ adoption of the Universal Declaration of Human Rights in 1948. It serves as a global reminder of the fundamental rights and freedoms owed to every person, and a call to action to protect them.

Members of the Sign LOUD team at the Scottish Parliament including some of the research participants, pictured alongside Scotland’s Deputy First Minister, Kate Forbes MSP and Karen Adam MSP.

Credit

Heriot-Watt University