Coral Reef Rescue Underway
Researchers and rangers have deployed the first batch of aquaculture-reared young corals on to the Great Barrier Reef. It took 130 people to collect an estimated 14.6 million coral eggs during spawning to get the project started. Then in February this year, they deployed 44,608 seeding devices, each containing around 10 young corals, from 13 vessels.Now they watch and wait.Their aim: to help the Great Barrier Reef survive global warming in the decades ahead.Researchers from the Australian Institute of Marine Science (AIMS) and partners have established an interlinked network of weather stations, moorings, buoys and other sensor-loaded devices to collect data on tropical marine ecosystems and assembled a team of oceanographers to coordinate efforts and analyze the information.Weather station at Davies Reef (Image courtesy of Marie Roman / AIMS)“The instruments we use operate in difficult environments and can get damaged. A tenacious barnacle can ruin months of data,” said AIMS Oceanography and Shelf Processes Team Lead Simon Spagnol, who oversees a network of buoys and moorings as part of AIMS’ work with IMOS (Integrated Marine Observing System).“You might put down a wire as thick as your thumb but when you pull it out it might have quadrupled in diameter due to barnacles and other sea creatures becoming attached. This can mess with sensors and prevent you from collecting important data.“There are some easy fixes, like applying zinc cream or copper tape to prevent encrustations. It is important to be in problem solving mode to ensure you can collect the best data for as long as possible from these instruments.”Other impediments to data collection include severe weather events, such as cyclones which have been known to wipe out infrastructure and sensors for long periods.There are approximately 300 temperature loggers helping gather data on sea temperatures on Australia’s reefs. They are exchanged annually or more frequently if there is a coral bleaching event. A collaborative effort across universities and government agencies also monitors conditions at key times and locations using IMOS Event Based Sampling's autonomous ocean gliders.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.Coral infected with black-band disease (Image courtesy of Maria Byrne / University of Sydney)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.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.”Researchers from James Cook University (JCU) have found that coral bleaching on the Great Barrier Reef is influenced not only by extreme summer heat, but also by winter conditions months earlier.“Most bleaching prediction tools focus on summer heat and assume that corals start each summer in the same condition,” said JCU student Valerie Cornet, who led the study. The team analyzed in-water and aerial bleaching observations alongside sea surface temperatures across the central Great Barrier Reef from Townsville to Port Douglas, focusing on the 2016/17 bleaching seasons.“2016 and 2017 were the first consecutive years of severe bleaching,” said JCU Professor Scott Heron, who supervised the study. “The scale and severity of these mass bleaching events were unprecedented, affecting vast areas of the reef. This gave us a rare opportunity to study how repeated heat stress and recovery periods interacted, including effects before summer conditions set in.”Their results showed that sustained high winter temperatures worsen bleaching the following summer. In contrast, moderate winter heat may reduce bleaching impacts because it stimulates corals to produce heat-shock proteins, boosting cellular repair and metabolic activity. It can also shift their symbiotic algae to more heat-tolerant types.These results could improve early-warning systems and predictive models.The most sophisticated modelling to date forecasts that under the current global emissions pathway the Great Barrier Reef could lose most of its coral by the end of the century, but curbing climate change and strategic management will help coral resilience.A research team led by the University of Queensland (UQ) simulated different future climate scenarios driven by a range of plausible global emissions trajectories.A research team led by the University of Queensland simulated different future climate scenarios driven by a range of plausible global emissions trajectories. (Image courtesy of University of Queensland)Dr. Yves-Marie Bozec from UQ’s School of the Environment said the comprehensive modelling of individual corals included their ability to adapt to warmer water, large-scale reef dynamics and their interconnections on ocean currents.“We ran all of those factors with the most up to date climate projections – and the news was not good,” Bozec said. “We forecast a rapid coral decline before the middle of this century regardless of the emissions scenario. Corals may partially recover after 2050, but only if ocean warming is sufficiently slow to allow natural adaptation to keep pace with temperature changes.”The ecosystem model, ReefMod-GBR, simulated the lifecycles of multiple coral species on 3,806 individual reefs. Each modelled reef had tailored environmental settings including water quality, larval connectivity with neighboring reefs, outbreaks of the coral-eating Crown of Thorns starfish and the risk of cyclones and coral bleaching until 2100.The study has a glimmer of hope, even on the current emissions trajectory. Reefs in areas where the water doesn’t heat up as dramatically because it is well mixed, fared better than others. And the better-connected reefs with good access to larval replenishment from other nearby reefs were healthier.Therefore, management efforts to safeguard strategic parts of the coral reef network can have a beneficial impact.“The window for meaningful action is closing rapidly but it hasn’t shut,” Bozec said.Baby coral being deployed overboard (Image courtesy of Marie Roman / AIMS)