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 Niño – 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-centimeter 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 kilometers 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 localized 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 prioritize 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 subtropical 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 were funded by the Australian Government’s National Environmental Science Program (NESP), through both its Tropical Water Quality Hub and Northern Australia Environmental Resources Hub.

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 mean 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.

In the lead-up to National Reconciliation Week (27 May – 3 June), scientists from James Cook University are upskilling Torres Strait rangers this week 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, the 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 that 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.

Large-scale monitoring of seagrass meadows across Hervey Bay and the Great Sandy Strait reveals there is almost no seagrass remaining across most of the previously mapped areas. The surveys come after two significant flood events in early 2022, and scientists are concerned that the seagrass loss could trigger an increase in dugong and green sea turtle strandings. James Cook University TropWATER Centre is leading the monitoring of 2300 km2 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 a drastic reduction in seagrass when compared with previous extensive mapping. “Our boat surveys show there is 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 are critical to help understand what seagrass resource remains to support dugong and turtle feeding, as well as to 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 favorable.” 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 dugongs, including a 20 percent 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 trialing the use of drones to monitor the body condition of the dugongs in the area. “Extensive seagrass loss can have a 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 has been done for whales and manatees, and now we are 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 characterize 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 finish the 14-day assessment of deep-water and shallow-water habitats across Hervey Bay and the Great Sandy Strait today, using aerial and boat surveys. Final results from the survey will be available in the coming months.

Researchers analyzing more than one million satellite images have discovered 4,000 square kilometers 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 kilometers of tidal wetlands were lost, offset by gains of 9,700 square kilometers, leading to a net loss of 4,000 square kilometers over the two-decade period. “We found 27 percent 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 percent of that total concentrated in Indonesia, China, and Myanmar. “Asia is the global center 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 will use drones, helicopters, 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 seagrass 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.

Native freshwater turtles have been caught in the battle to keep feral pigs out of coastal wetlands, with many adult turtles becoming fatally trapped by fences. But now, scientists and Traditional Owners on Cape York Peninsula have found it’s possible to keep the destructive pests out and give turtles safe passage to move between water bodies during critical lifecycle periods. It’s called a ‘turtle gate’ and any freshwater floodplain fence can be modified to include it by removing a small section of wire, with little more than a pair of pliers. The research, led by James Cook University’s Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER), shows the modifications can be made to the most common exclusion fences used in Australia. TropWATER Principal Researcher Dr. Nathan Waltham said many inland wetlands tend to dry out entirely in the dry season, resulting in the migration of freshwater species. “These freshwater turtles need to make the very slow journey across land, from one wetland to another waterhole,” he said. “In cases where fences have been built around wetlands to protect them from feral animals, we found many turtles simply became stuck either inside or outside of the wetlands. “Without being able to move to another river or creek, turtles would often not survive either because of dehydration or from starvation.” The research showed any freshwater turtle with a shell width greater than the diagonal wire gap would likely become trapped, limiting their ability to access nesting sites, other waterholes, mates, and food. “These turtle gates are a fast and cost-effective solution, which could be included by landholders or local rangers,” Dr. Waltham said. The research was funded by the Australian Government’s National Environmental Science Program through the Northern Australia Environmental Resources Hub. North Australian Indigenous Land and Sea Management Alliance Research Manager Dr. Justin Perry said feral pigs were the worst invasive mammal in Australia and managing the feral animals was a “hard balance” to get right. “Pigs can contaminate water sources and quickly destroy a wetland in just a few days, decimating crucial habitats for native plants and animals,” he said. “Fences are a common management solution and our project partners on Cape York, Aak Puul Ngantam (APN), and Kalan Enterprises, have been using fences to protect wetlands for many years. “We know that well-maintained fences do a good job at keeping pigs out, but we need to take into account what these exclusion fences could be doing to native species. “These small modifications could save many turtles already caught in challenging floodplain environments.” The study Simple fence modification increases land movement prospects for freshwater turtles on floodplains was published in Wildlife Biology, authored by Nathan Waltham, Jason Schaffer, Sophie Walker, Justin Perry, and Eric Nordberg.

Genetic clues in the water could lead scientists to the last surviving populations of frogs on the brink of extinction – and it could be our last hope to find them. For decades, scientists have slowly scoured remote mountain ranges in search of rare frog species that have vanished from the wilderness, often to no avail. But in new research, scientists from James Cook University’s Centre for Tropical Water and Aquatic Ecosystem Research (TropWATER) have found it’s possible to find traces of a frog’s environmental DNA (eDNA) in catchments more than 20 kilometres downstream from their habitats. TropWATER geneticist and co-lead author Dr Cecilia Villacorta-Rath said the eDNA tool could revolutionise the search for some of Australia’s critically endangered frogs. “When frogs visit water streams they shed bits of their genetic material, such as skin, urine, saliva, faeces and blood into the water,” she said. “This eDNA travels kilometres downstream to feed into a bigger catchment – and this is where we could detect even small populations. “It’s a remarkable result. We could find where these missing frogs are hiding without even sighting them.” With potentially dozens of small streams leading into a bigger catchment, Dr Villacorta-Rath said the eDNA method captures multiple possible habitats. Australia’s frogs have been disappearing over the last four decades, with 26 species at the greatest risk of extinction. Invasive species, habitat loss and chytrid fungus disease are thought to have caused this dramatic decline. JCU biologist and co-lead author Dr Conrad Hoskin said knowing where the remaining populations were living was critical. “Using traditional visual surveys to find these elusive frogs can feel like trying to find a needle in a haystack,” he said. “I’ve spent many, many nights in the darkness at the top of some really remote mountains looking for these missing frogs – we’ve made some important finds but also failed to find some species. “This eDNA tool is an invaluable addition to narrowing down the search area by screening entire catchments.” The science team used the new eDNA tool on a known armoured mist frog population living in the mountains outside of Cairns. The team collected and preserved whole water samples to detect the small population, of about 1000 individuals, about 22 kilometres from their known habitat. Researchers caution that while finding threatened populations is an important first step in protecting frogs, issues such as invasive species, habitat impacts and climate change need to be managed to ensure conservation success. The study, Long distance (> 20 km) downstream detection of endangered stream frogs suggests an important role for eDNA in surveying for remnant amphibian populations was published in the journal PeerJ and authored by Cecilia Villacorta-Rath, Conrad Hoskin, Jan Strugnell and Damien Burrows. TropWATER has led research in eDNA technology for six years, revolutionising how scientists monitor and detect rare and endangered species and invasive aquatic species. The research was funded by the Australian Government’s National Environmental Science Program through the Northern Australia Environmental Resources Hub.