Editor’s Note: Call to Earth is a CNN edited series that promises to report on the environmental challenges the planet faces, along with solutions. Rolex’s Permanent Planet Initiative is partnering with CNN to promote awareness and education on key sustainability issues and encourage positive action.
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Australia’s iconic Great Barrier Reef is the largest living structure on the planet, with a vast variety of species. However, in recent years it has been hit by a series of devastating mass bleaching events, turning the vibrant colors of some of the reefs into bright whites.
Around the world, corals suffer similar fates, with over 80% of the oceanic coral reefs hit ongoing global bleaching events launched in 2023, with ocean temperatures recorded. Bleaching is fatal as corals live in them and algae that serve as food sources are depleted.
The effect can be devastating. Coral reefs make up only 0.01% of the seabed, but they support a quarter of all marine life, provide food and livelihoods for people, helping to reduce storm surges and protect against erosion.
At this month’s UN Marine Conference, 11 countries signed a pledge to protect climate-resistant coral reefs, and separately the government and partners pledged $25 million to the Coral Reef Global Fund.
Ultimately, if coral reefs are saved, efforts to curb ocean warming by reducing carbon emissions should be strengthened. However, scientists are also looking for other solutions to keep the reef alive in a warm world.
At Sydney Institute of Technology, future Leaf Team scientists are looking for “super corals.” This is a species that is naturally resilient to changes in the environment, such as high temperatures, acidity, and low oxygen levels. One of the goals of the program is to identify these corals, discover the methods they are using to survive, and use them as a blueprint to support other corals in the harsh environment of the future.
“We’re focused on trying to understand reef resilience in a changing environment,” says Dr. Emma Camp, a marine biologist and future leader of the Reef Team. “How do we build coral resilience to survive the stress they inevitably face?
Camp first discovered “Super Coral” species naturally grown in high temperature, acidic mangrove lagoons. Since then, she says the team has found up to 40 species of these hardy species growing in a variety of environments around the world. Now their focus is on finding them within the Great Barrier Reef.
“(We want to increase heat resistance and identify coral species, but it still maintains other properties that are really important. We hope they are fast growers, says Christine Roper, a postdoctoral researcher on the team.
During the expedition to the Great Barrier Reef, the team collects and analyzes specific coral species. They perform real-time heat tolerance tests on the samples using a special phenotypic device machine that helps to predict which corals are most likely to survive as water temperatures rise. It also allows coral fragments to be returned to the lab, DNA is extracted and tested for a wider range of purposes.
Once they identify stress-resistant species, the coral care programme – a project co-founded by a large-scale repotting camp in collaboration with local tourism operators and indigenous communities – It spreads to coral nursery schools established in various locations in the Great Barrier Reef. They then “off” them with coral reefs that help to recover areas affected by bleaching.
Since the programme began in 2018, over 125,000 corals have been planted throughout the Great Barrier Reef off Cairns, Port Douglas and Whitsunday, with a survival rate of 85%.
However, restoring the area of the Great Barrier Reef is not an easy task. There are almost 3,000 individual coral reefs, covering 344,400 square kilometers (133,000 square miles), and as of April 2024, 60% of the reefs have been exposed to recent invasions. The team hopes that the areas where outplants have been performed already show visible signs of recovery.
Other labs around the world are developing similar solutions, with promising results. The Australian Institute of Marine Science (AIMS) uses artificial selection and selective reproduction to raise heat-resistant corals, and reports that genetic interventions may work, but have had a variety of successes across species. Newcastle University in the UK selectively raises corals that say they have not yet conducted large-scale trials in the wild but can better survive the ocean heat wave.
Research shows that traditional coral recovery efforts could be cancelled within a few years if there is a bleaching event, but by planting heat-resistant corals, coral nurturing programs hope that the restoration can withstand future events. “By focusing our efforts on identifying and increasing the abundance of heat-resistant corals in our population, we optimize our efforts by increasing resilience for future heat stress events,” says Roper.
Whether naturally or selectively reared corals, the main challenge is how to expand the labour-intensive and costly planting process.
Therefore, the focus of the coral care programme was to attract tourism operators and the local community. “We can build scale by having a pocket of the community that takes on these actions,” Camp says.
Working with seven tourist operators on the Great Barrier Reef, including the wavelength reef cruise, tourist-paid snorkeling trips to the reefs are doubled as instilling expeditions. On these trips, members of the crew, all trained divers and marine biologists, tend to have plant corals nursed and conduct local surveys. The Wavelength team helped establish the program at CAMP, operated coral nursery along the reefs and collected data on coral health.
Still, there are limits to how much you can achieve just by planting strict coral species. Future Leaf Teams are also investigating other solutions, including whether corals may nourish different foods and vitamins.
Corals feed by reaching tentacles from their bodies to capture microscopic food particles. Previous studies have shown that feeding the zoo (a small animal floating near the surface) after a bleaching event can help increase resilience, allowing corals to grow on substrates injected with metal nutrients such as manganese and zinc. However, such methods have not yet been tried on a large scale.
“Even though I know a lot about corals, I know very little about the nutritional aspects of corals,” says Camp. “This is a field that, for me, really helps us to advance our recovery practices by understanding more about what research and science needs to fundamentally survive stress.”
Early on, the team returning to Sydney’s lab has been doing experiments to feed coral foods such as microscopic brine shrimp fed various types of algae, and add specific metals or vitamins to the water the coral absorbs.
The goal is to develop supplements that can provide extra nutrients when stressed by corals, helping them survive or recover from heavy bleaching events.
“It’s like we humans. When we’re running, we might take supplements to give us a boost. That’s the same as corals,” says Camp.
“What we have to explore is these types of new ideas, and if we do nothing, the end result is a loss of coral reefs around the world,” she says.
While we hope that scientific innovation and scalable solutions can provide some kind of stop for the reef, Camp warns that protecting them in the long term will result in tackling the causes of mass coral bleaching.
“There’s a lot you can do to buy reef time,” she says. “We need to tackle climate change because if temperatures continue to rise, many of the corals will ask them to survive in the environment they face.”
