Gulf mangrove dieback discovery

Breakthrough research by James Cook University scientists has solved the mystery of the catastrophic death of 40 million mangrove trees around the Gulf of Carpentaria in 2016 – and the discovery could help scientists predict, and possibly prevent, future events.

The latest research reveals that the devastating mass death of tidal mangrove forests was a result of an unusually low sea-level due to large-scale swings in El Nino – Southern Oscillation events.

Lead author Dr Norm Duke from JCU’s TropWATER Research Centre said the mangroves had not recovered seven years on, making the mangrove dieback event an ongoing coastal catastrophe.

“The key factor responsible for the mass dieback appears to have been the sudden 40-centimetre drop in sea level that lasted for about six months, coinciding with no rainfall, killing vast areas of mangroves,” he said.

“Essentially, the trees died of thirst.”

The study shows that strong El Niño events – often associated with coral bleaching on the Great Barrier Reef – are also a threat to vital mangrove ecosystems.

Nearly 40 million mangrove trees died along 2000 kilometres of coastline in northern Australia’s remote Gulf region, releasing nearly one million tonnes of carbon. More than 76 km2 of mangroves were lost, making this the worst incidence of climate-related mass tree dieback that has ever occurred globally.

“Recovery has been repeatedly stymied by other climate-driven events including severe cyclones and flooding,” Dr Duke said.

Author assisting with data analysis and JCU TropWATER Researcher Dr Adam Canning said the study’s evidence for sea-level drop being the cause was found in the discovery of an earlier mass dieback in 1982, observed in satellite imagery.

“The 1982 dieback also coincided with an unusually extreme drop in sea level during another very severe El Niño event. We know from satellite data that the mangroves took at least 15 years to recover from that dieback,” he said.

“Now they are caught in a vicious collapse and recovery cycle because of repeated pressure from climate change – the question remains when or if they will recover.”

Enhancing the resilience of these ecosystems is possible with targeted action.

Co-author and wetlands researcher at Earthwatch Australia, Jock Mackenzie, said “To help mangrove ecosystems respond to environmental impacts such as climate change, we must address the localised human impacts that degrade mangrove habitats including pollution, altered hydrology, feral animals, weeds, and improper fire management. These impacts impede the natural ability of mangroves to adapt to climate change.”

“We encourage community groups, Indigenous custodians and catchment management agencies to continue to monitor mangrove shorelines through a combination of satellite monitoring and the MangroveWatch citizen science program, to help identify and prioritise targeted local mangrove management and threat reduction.”

Satellite imagery could also be used to help monitor the recovery of mangroves in remote areas and identify key areas under pressure. It may even be possible to predict future events, which could help prepare for innovative rescue efforts that may include reducing water stress during El Niño events via targeted irrigation.

Dr Duke said mangroves are vital to the ecology and stability of tropical and sub-tropical coastlines and their protection is critical.

“They provide essential habitat for many species and can hold substantially more carbon than tropical forests within the same area,” he said.

“These extraordinary trees are normally environmentally resilient, being able to grow in seawater, intertidal zones and on coastal salt flats. They are also essential for preventing or reducing shoreline erosion and retreat.”

The dieback’s exact cause has been revealed after a four-year research partnership between James Cook University, Charles Darwin University, and Carpentaria Land Council Aboriginal Corporation Indigenous Rangers in the Gulf, funded by the Australian Government’s National Environmental Science Program and the Northern Territory Government.

The Gulf mangrove dieback research project and team was funded by the Australian Government’s National Environmental Science Program (NESP), through both its Tropical Water Quality Hub and Northern Australia Environmental Resources Hub.

Scholarship gives marine science students real world opportunity

Two outstanding James Cook University (JCU) marine science students have been awarded Bachelor of Science scholarships – equipping them with unique real-world experience on the Great Barrier Reef under the guidance of leading marine researchers.

Jordan Wells and Indus Fisher will receive financial support throughout each year of their degree, in addition to the chance to work alongside researchers and port industry managers, thanks to a partnership between JCU and North Queensland Bulk Ports Corporation (NQBP).

JCU’s Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) Principal Researcher Dr Nathan Waltham said the scholarship would be invaluable for the budding marine scientists.

“Every year Jordan and Indus will have financial support, plus get hands-on experience in understanding how environmental science can tackle real marine industry issues,” he said.

“Marine science can be a very competitive field and this scholarship gives these promising students valuable real-world experiences, beyond just the classroom.”

Indus Fisher, who relocated to Townsville from Mackay, said he had grown up in the heart of the Great Barrier Reef and loved the marine environment from a young age.

“With a hope to help protect this beautiful ecosystem, I couldn’t think of a better place to learn the knowledge and skills to do so than at the world’s leading university in marine science,” he said.

“Thanks to the generosity of North Queensland Bulk Ports and JCU TropWATER, this financial burden has been greatly reduced, allowing me to focus more fully on my studies and achieve the very best possible results I can.

“The real opportunity lies in the industry connections, placement possibilities, and real-world experience this fantastic partnership makes available to us.”

The two students will join last year’s scholarship recipient, Amy Cantrill, and intern students who will complete placement in the environmental team at NQBP. Together, the student programs are building the next generation of marine scientists to be job ready.

NQBP CEO Nicolas Fertin said the port authority is proud to provide university students real-world experience in port environmental management.

“With JCU, we have created one of Australia’s most comprehensive port marine ambient monitoring programs while training the next generation of industry and job-ready science graduates,” Mr Fertin said.

“The marine environment is central in our everyday planning and port operations. Informed environmental management ensures trade keeps flowing to service the Queensland economy.”

JCU offers the world’s best marine and freshwater biology degrees, and NQBP is the only port authority in the world with three priority ports, of Hay Point, Mackay and Abbot Point, located on the shores of a World Heritage Area.

The scholarship program is part of NQBP’s broader five-year partnership with JCU, where researchers monitor the local marine environment surrounding four ports.

Jordan Wells (left) and Indus Fisher (right) have been awarded Bachelor of Science scholarships for 2022, joining 2021 recipient Amy Cantrill (centre).

Identifying sediments in the Bowen, Broken and Bogie catchments

Graziers and scientists are working together to understand how, when and where sediment moves from the land into the Bowen, Broken and Bogie catchments – building a more accurate understanding of the local water quality.

Over the past four wet seasons, JCU TropWATER scientists Zoe Bainbridge and Steve Lewis have worked with local graziers and NQ Dry Tropics’ Landholders Driving Change project team to run the LDC Community Water Quality Monitoring Group, collecting and analysing water samples across nine river and creek sites during high rainfall events.

The program is helping improve scientists’ and landholders’ understanding of the loss of soil, and the nutrients attached to this soil, that travel from the land into waterways during high rainfall.

“The aim is to help identify the main source areas of sediment within the catchment, and work with landholders to prevent fine sediment flowing out to the Great Barrier Reef,” researcher Zoe Bainbridge said.

Latest results: The 2021-22 wet season

Despite limited rainfall in the Collinsville region this wet season, more than 50 water samples were collected by graziers during local streamflow events and delivered to TropWATER to be analysed for phosphorous, nitrogen and sediment content.

Early results show the Bowen River sub-catchment is an area highly susceptible to soil loss, most likely due to soil types prone to erosion.

The full report will be available later this year.

Big picture: how the data will be used

The water quality data collected from this project is paired with historical water quality and sediment source tracing data, giving an improved understanding of the sediment sources and transport processes within these catchments.

These valuable datasets are being used by the Paddock to Reef Program’s catchment modellers to improve the spatial model representation of water quality across the Bowen Broken and Bogie catchments, including how this relates to land management changes within the catchment.

LDC Community Water Quality Monitoring Project is a collaborative between NQ Dry Tropics’ Landholders Driving Change and JCU TropWATER Centre, funded by the partnership between the Australian Government’s Reef Trust and the Great Barrier Reef Foundation, and the Office of the Great Barrier Reef.

Scientists, Traditional Owners and conservationists come together in ‘The Reef Cooperative’

To mark World Oceans Day, Cotton On Foundation, the philanthropic arm of the Cotton On Group, has committed $2 million to co-launch a world-first conservation project, ‘The Reef Cooperative’.

The new initiative, coordinated by Citizens of the Great Barrier Reef, brings together Traditional Owners Yirrganydji Land and Sea Rangers, James Cook University reef scientists, reef restoration experts Mars Sustainable Solutions and leading tourism operator GBR Biology.

Through the collaborative partnership, conservation efforts will be scaled up on the Great Barrier Reef, with Hastings Reef on Yirrganydji Sea Country, near Cairns, chosen as the first restoration site.

Seed and grow – JCU leads coral larvae project

Under The Reef Cooperative, James Cook University TropWATER Centre will lead the Coral Larval delivery program to help degraded reefs recover and replenish by seeding and growing new corals.

The project will see the delivery of 30 million coral larvae over three years on Hastings Reef, and other reefs, during the annual Great Barrier Reef mass coral spawning event.

Project lead JCU TropWATER’s Dr Katie Chartrand said the project would help to spur coral growth and boost local reef recovery.

“Climate change has resulted in more frequent marine heatwaves and cyclone damage combined with other impacts like crown-of-thorns starfish outbreaks – these repeated events are making it harder for damaged reefs to recover,” she said.

“This coral larval project is all about giving struggling reefs a better chance at recovering by boosting the number of available coral larvae for natural settlement.”

The project involves collecting coral spawn during the Reef’s annual spawning event and relocating the larvae to damaged reefs.

“The Reef Cooperative is an example of science, traditional owners, and industry partners delivering ground-breaking programs that could make a big difference to the recovery and resilience at key sites on the Great Barrier Reef,” Dr Chartrand said.

“This conservational model is designed to build resilience to damaged areas using a scientific approach while enabling greater capacity for traditional owners and tourism partners to share their perspectives and knowledge.”

The Reef Cooperative – projects for the next three years 

The three-year funding commitment will see the launch of The Reef Cooperative to deliver a major conservation program at degraded reefs with multiple projects interwoven to have greater collective impact.

In addition to JCU’s coral larvae project, 700 MARRS reef stars will be installed to aid in reef recovery, starting with the 250 at Hastings Reef. These stars are a ground-breaking restoration technology that will provide a stable base for coral fragments to grow on damaged sections of the reef.

Hastings Reef and other subsequent sites chosen as part of The Reef Cooperative will be maintained by Yirrganydji Sea Rangers or other Traditional Owners of their Sea Country. The rangers and Traditional Owners will engage tourists in reef conservation and protection with weekly tourism visits through Dreamtime Dive & Snorkel.

The Great Reef Census – a Citizens of the Great Barrier Reef initiative – will also be scaled up to survey the far reaches of the 2,300km Great Barrier Reef, both in-water and recruiting citizen scientists worldwide to help analyse the tens of thousands of Census images.

Andy Ridley, CEO of Citizens of the Great Barrier Reef said the scale of the $2 million investment from Cotton on Foundation for The Reef Cooperative allows for a rapid delivery of tangible conservation actions.

“With collaboration at its heart, The Reef Cooperative is designed to deliver highly scalable practical conservation outcomes on reefs across the 2,300km Great Barrier Reef and beyond.”

Tim Diamond, GM of Cotton On Foundation said the commitment, supported by a unique fundraising model in partnership with customers, will support an incredible collective of minds and organisations working directly on the Great Barrier Reef to address the issue of coral reef loss in the face of climate change and severe weather events.

“The conservation model is unique and through its focus on community, innovation, and knowledge sharing it has proven to transform one of the great environmental challenges in our own backyard. At Cotton On Foundation, we are proud to support Citizens of the Great Barrier Reef and this game-changing initiative.”

New partnership unlocks largest blue carbon restoration project in Queensland’s Great Barrier Reef catchment

Coles and the Great Barrier Reef Foundation have announced a 10-year, $10 million partnership to help strengthen the regeneration and resilience of the Great Barrier Reef.

Under the new partnership, JCU TropWATER Centre is leading a major coastal habitat restoration project – and it will be the largest blue carbon project to date in Queensland’s Great Barrier Reef catchment.

Led by Dr Nathan Waltham, TropWATER’s Principal Research Scientist, the project will work with farmers to reinstate significant coastal wetlands in the Great Barrier Reef catchment, restoring coastal habitats and serving as highly effective carbon sinks.

“The funding provides us the first opportunity to undertake large scale restoration in the Great Barrier Reef catchments, delivering outcomes for the reef, climate, biodiversity and water quality,” he said.

“Wide-scale loss of coastal wetlands and changing climate conditions means that we need to roll out major projects like this, and this funding is a start in helping us deliver ecosystem service returns for landholders, Traditional Owners of Country, industry and government agencies.”

Through the partnership, Coles will dedicate funds towards a number of innovative projects based on ‘blue carbon’ – the process of capturing and storing carbon in oceanic or coastal ecosystems such as mangroves, tidal marshes and seagrasses.

Thinus Keeve, Coles Chief Sustainability, Property and Export Officer said: “Coles is already making great strides in our Together to Zero emissions ambition and our partnership with the Great Barrier Reef Foundation represents the latest phase in our commitment to show leadership on sustainability.”

“Our investment in the regeneration and revegetation of coastal ecosystems will help build the resilience of the Reef and deliver projects that can make a difference at a meaningful scale,” he said.

Chief Scientist of the Great Barrier Reef Foundation Professor Ove Hoegh-Guldberg said: “We need the best science to develop bold, innovative ideas to protect coral reef habitats and slow the impacts of climate change, which is the biggest threat to the survival of the Great Barrier Reef.

“In addition to tackling the root cause of climate change, we must make reefs more resilient to the impacts of climate change that are already locked into the system.

“Coles’ partnership in blue carbon projects with the Great Barrier Reef Foundation is a prime example of the way we all can be working together to help the Reef and all its living diversity now and into the future. It is terrific to see one of Australia’s corporate greats generously engaging to solve one of the greatest challenges facing Australia.”

Coles’ investment will commence with two pilot projects designed to unlock the Reef’s blue carbon potential, increase biodiversity, accelerate scientific research and support communities along the Reef.

In addition to Dr Waltham’s wetland restoration project, the partnership is also developing the first large-scale seagrass nursery in partnership with leading seagrass researchers and Traditional Owners of the Reef.

Rangers take the lead as ‘eyes and ears’ of the Northern Great Barrier Reef

Rangers take the lead as ‘eyes and ears’ of the Northern Great Barrier Reef

In the lead up to National Reconciliation Week (27 May – 3 June), James Cook University’s scientists are this week upskilling Torres Strait rangers to be the eyes and ears in protecting seagrass meadows in the northernmost part of the Great Barrier Reef.

In one of the country’s most comprehensive seagrass monitoring programs, Torres Strait Regional Authority (TSRA) and JCU TropWATER Centre are together training rangers from remote island communities to monitor seagrass meadows in the nation’s far north.

TSRA Acting Chairperson Horace Baira said Green Island off Cairns – home to vital dugong and turtle seagrass habitat – provided the perfect training ground.

“Combining ancient knowledge and modern science is critical for conservation as we face climate impacts across the Torres Strait,” Mr Baira said.

“The ocean is the lifeblood of the Torres Strait and bringing together all fields of expertise will help protect this precious natural resource for current and future generations.”

JCU’s TropWATER Centre seagrass scientist Dr Alex Carter said the rangers were critical in regional assessments of seagrass condition in Torres Strait.

“This training week builds on a 15-year partnership that goes from strength to strength as it continues to grow with new monitoring locations added to the network,” she said.

“Traditional Owners are the eyes and ears on the ground and this ranger-led program provides the first warnings of any declines or changes in seagrass health.

“This allows for quick management responses and targeted research projects to protect these important seagrass meadows.”

The four-day workshop, delivered by JCU scientists and TSRA, includes in-field training, species identification, and an opportunity to discuss results from recent research and monitoring projects to plan for future opportunities.

24-year-old Iama (Yam) Island Traditional Owner and TSRA Marine Biologist Madeina David said the training would support reef monitoring and results.

“Most people are unaware the Torres Strait is the most northern part of the Great Barrier Reef, home to the world’s largest dugong population and significant numbers of green turtles,” Ms David said.

“Working in partnership to value both traditional and western science gives our marine life and ocean ecosystems the best chance to survive and thrive.”

Meriam Traditional Owner and TSRA Senior Ranger Supervisor Aaron Bon said the training would build the capacity and knowledge of local Torres Strait Islander and Aboriginal rangers and boost conservation efforts across the Torres Strait.

“It will also assist Rangers and Traditional Owners to keep an eye on our reefs and seagrass meadows in the region and in doing so, we help protect some of the world’s most pristine and rich sea country,” Mr Bon said.

“Rangers will bring back skills, share learnings to support our important work on land and sea country in remote island communities and help us to make informed decisions around where we need to target our conservation efforts.”

TSRA employs up to 60 land and sea rangers across 14 Torres Strait communities to support employment opportunities for local people to combine traditional knowledge with conservation training to protect and manage land, sea and culture.

 

Turtles, dugongs in danger from seagrass loss

Large-scale monitoring of seagrass meadows across Hervey Bay and the Great Sandy Strait reveals there’s almost no seagrass remaining across most of previously mapped areas.

The surveys come after two significant flood events in early 2022, and scientists are concerned the seagrass loss could trigger an increase in dugong and green sea turtle strandings.

James Cook University TropWATER Centre is leading the monitoring of 2300km2 of seagrass meadows – one of the largest and most important areas of seagrass in eastern Australia – in partnership with the Department of Environment and Science (DES).

TropWATER Professor Michael Rasheed said there had been drastic reduction of seagrass when compared with previous extensive mapping.

“Our boat surveys show there’s almost no seagrass visible in the 2m to 17m depth range for much of the deeper meadows, and these sites have previously recorded extensive areas of seagrass,” he said.

“There were some areas of sub-tidal seagrass but these were confined to the deepest areas in the northern part of the bay.

“We also used helicopters to assess more than 1300 intertidal sites throughout the Great Sandy Straits and while some sites had seagrass the cover was typically less than one percent of the seafloor offering scant resources for dugong and turtle.”

Prof Rasheed said the last comprehensive mapping of the entire area was more than 20 years ago, and surveys now were critical to help understand what seagrass resource remains to support dugong and turtle feeding as well as assess the potential for recovery over the coming months.

“However, we are in the low season for seagrass growth and about to enter the recovery period for seagrasses, so we hope to return to these waters in September/October, the normal seasonal peak for seagrasses, to look at how much of the seagrass has recovered.

“The good news is that there is still some seagrass remaining and this can provide the source for recovery in the coming months if conditions are favourable.”

In 1991 the same region experienced back-to-back floods causing more than 1000 km2 of seagrass loss.

Sediment in the floodwaters is known to reduce light and smother seagrass meadows, potentially depleting the main food source for dugong and turtles in the area.

The following year saw the highest recorded mortality of dugong, including a 20 per cent decline in dugong calves.

Queensland Parks and Wildlife Service Senior Ranger Dan Clifton said rangers had seen an increase in marine strandings within the Great Sandy Marine Park over the past 12 months, with the recent floods contributing to the issue.

“Since July 2021 we have recorded more than 240 stranded marine turtles and 22 stranded dugongs in this area as a result of different factors including boat strike and poor health,” Senior Ranger Clifton said.

“These numbers are significantly greater than the long-term average in the area.

“We have also recently seen large, mature green turtles presenting with an ulcerative skin disease affecting the carapace and flippers. This is currently being investigated by leading authorities to determine causes so we can respond accordingly.

“The issues currently faced by marine wildlife in the Great Sandy Marine Park demonstrate the importance of ongoing research and surveys so that we can identify and respond to threats and how critical it is that we protect our precious ecosystems.”

Alongside the seagrass monitoring, TropWATER researcher and dugong expert Dr Chris Cleguer is trialling the use of drones to monitor the body condition of the dugongs in the area.

“Extensive seagrass loss can have dramatic impact on dugongs and sea turtles. Dugongs may stop breeding, some will move and some will die,” he said.

“Assessing changes in the body condition of dugongs can help us monitor the health of the animals following the flooding events in the Hervey Bay region.

“Drones are increasingly used as a low-cost, non-invasive approach to obtain morphometric measurements of marine mammal body size. It’s been done for whales and manatees, and now we’re starting to collect data to do the same for dugongs.”

The large-scale monitoring also includes the collection of sediment samples from the seafloor to better characterise the fine sediment that surrounds the seagrass meadows and the source of these sediments.

TropWATER researchers and rangers from Queensland Parks and Wildlife Services will today finish the 14-day assessment of deep-water and shallow-water habitats across Hervey Bay and the Great Sandy Strait, using aerial and boat surveys.

Final results from the survey will be available in the coming months.

Dramatic loss of globe’s wetlands

Researchers analysing more than one-million satellite images have discovered 4,000 square kilometres of tidal wetlands have been lost globally over twenty years – but ecosystem restoration and natural processes are playing a part in reducing total losses.

Dr Nicholas Murray, Senior Lecturer and head of James Cook University’s Global Ecology Lab, led the study. He said global change and human actions are driving rapid changes of tidal wetlands —tidal marshes, mangroves and tidal flats — worldwide.

“But efforts to estimate their current and future status at the global scale remain highly unclear due to uncertainty about how tidal wetlands respond to drivers of change.

“We wanted to address that, so we developed a machine-learning analysis of vast archives of historical satellite images to detect the extent, timing and type of change across the world’s tidal wetlands between 1999 and 2019,” said Dr Murray.

TropWATER’s Nathan Waltham, and co-author on the study, said wetland loss in the Great Barrier Reef was a major concern.

“Coastal wetlands provide many services such as habitat for fish, cultural values, carbon storage and water quality,”  said Dr Waltham.

“We are working closely with many partners including NRM groups, farmers, Land and Sea Ranger groups, government and industry to protect and restore coastal wetlands at home here – but it is a big job and much work is needed.”

Dr Murray said that globally, 13,700 square kilometres of tidal wetlands were lost, offset by gains of 9,700 square kilometres, leading to a net loss of 4000 square kilometres over the two-decade period.

“We found 27 per cent of losses and gains were associated with direct human activities, such as conversion to agriculture and restoration of lost wetlands. All other changes were attributed to indirect drivers such as human impacts to river catchments, extensive development in the coastal zone, coastal subsidence, natural coastal processes and climate change,” said Dr Murray.

He said about three-quarters of the net global tidal wetland decrease happened in Asia, with almost 70 per cent of that total concentrated in Indonesia, China and Myanmar.

“Asia is the global centre of tidal wetland loss from direct human activities. These activities had a lesser role in the losses of tidal wetlands in Europe, Africa, the Americas and Oceania, where coastal wetland dynamics were driven by indirect factors such as wetland migration, coastal modifications and catchment change,” said Dr Murray.

The scientists found that almost three-quarters of tidal wetland loss globally has been offset by establishing new tidal wetlands in areas where they formerly did not occur – with notable expansion in the Ganges and Amazon deltas.

“Most new areas of tidal wetlands were the result of indirect drivers, highlighting the prominent role that broad-scale coastal processes have in maintaining tidal wetland extent and facilitating natural regeneration. This result indicates that we need to allow for the movement and migration of coastal wetlands to account for rapid global change,” said Dr Murray.

He said over one billion people now live in low-elevation coastal areas globally.
“Tidal wetlands are of immense importance to humanity, providing benefits such as carbon storage and sequestration, coastal protection, and fisheries enhancement.
“Global-scale monitoring is now essential if we are going to manage changes in coastal environments effectively,” said Dr Murray.

Wuthathi Land and Sea Custodians partner with TropWATER scientists

Wuthathi Land and Sea Custodians will use drone, helicopter and drop camera surveys to map seagrass habitats on Wuthathi Sea Country in Northern Cape York, in partnership with TropWATER scientists.

Combining cutting-edge technology, science and Traditional Ecological knowledge, the data collected will give Land and Sea Custodians and Traditional Owners the tools to develop plans for future monitoring and management of seagrass on Wuthathi Sea Country.

TropWATER is working alongside Wuthathi Land and Sea Custodians to conduct these surveys, helping to develop capacity in drone flight path programming, image collection and recording of data on sea grass habitat.

The partnership will expand to helicopter and drop camera survey training later this year, where Wuthathi Land and Sea Custodians will be upskilled to undertake aerial and subtidal surveys to monitor inshore seagrass meadows.

The program is funded by the partnership between the Australian Government’s Reef Trust and the Great Barrier Reef Foundation.

 

 

 

 

 

 

 

 

 

 

Long lost ‘bum-breathing’ turtle makes its return

A revolutionary new DNA detection method has helped rediscover an iconic species of turtle last seen more than 25 years ago in a northern Queensland river.

Water samples taken from the lower Burdekin River by a James Cook University-led team of researchers and analysed for environmental DNA (eDNA) confirmed the presence of the Irwin’s turtle at many sites along the river, which has not been formally recorded in the area for more than 25 years.

The turtle, first discovered in the Burdekin catchment by the late Steve Irwin and his father Bob in the early 1990s, is among a number of freshwater species which uses its cloaca (equivalent to its bum) to breathe while underwater, thus able to stay submerged underwater for longer.

Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) Director Professor Damien Burrows and Research Officers Dr Cecilia Villacorta-Rath and Jason Schaffer teamed up with a State Government agency, a consultancy firm and Traditional Owners to survey the Burdekin, Bowen and Broken rivers for the elusive turtle.

“Until this rediscovery, we didn’t have any formal records to prove that the Irwin’s turtle was still living in the lower Burdekin River, and that river has changed a lot since the construction of the Burdekin Falls Dam,” Prof Burrows said.

“It’s reassuring to know they are still living there.”

The survey findings, co-authored by the JCU team and the Department of Regional Development, Manufacturing and Water’s Thomas Espinoza and Bernie Cockayne, were published this week in BMC Ecology and Evolution journal following two years of research comprising three separate survey periods over 2020 and 2021.

Funded by the National Environmental Science Program, 37 sites were investigated across the three river catchments, some of which involved the use of helicopters to get in and out.

Prof Burrows said eDNA technology was vital to the rediscovery of the turtle in the lower Burdekin River and had the potential to revolutionise how researchers tracked and located both aquatic and land-based animals.

“Previously, it’s been very difficult to sample for the Irwin’s turtle because they only live in places where there are crocodiles, or in upland tributaries which are very hard to access,” he said.

“They also don’t come into traps easily and the water they are living in in the Burdekin isn’t clear so you can’t put in underwater cameras to see them.

“But now with eDNA, all we had to do was take a water sample and analyse for their DNA.”

With the new process, DNA itself can be extracted and amplified directly from environmental samples such as soil, sediment and water without having to catch the target organism.

Dr Villacorta-Rath said while the eDNA samples taken by the team could not determine the age of the turtles found in the lower Burdekin and other rivers surveyed, the results were potentially game-changing.

“With the original site samples that we took in 2020, we had the beginnings of the story, but we needed to investigate further and go closer to the dam and see where was the uppermost distribution of the species,” she said.

“We don’t know anything about the demographics of this population, but the fact we have found their eDNA now, despite the dam being built in the 1980s, could point to adult Irwin’s turtles being able to survive in these more turbid water conditions.

“This rediscovery has now challenged the previous hypothesis that the species could not survive in these conditions.”

The information gathered will also help the State Government as it evaluates a proposal to build a dam in the upper reaches of Broken River at Urannah Station

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