Underwater gardens growing coral fragments are part of efforts to protect reefs from climate change
November 22, 2022 at 12:30 p.m. EST
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The world off Australia’s north-east coast is magical yet besieged, a place of stunning color in good times but ghostly white in bad times. The bad has happened repeatedly in recent years, as warming oceans associated with climate change have bleached the vast coral ecosystem beneath.
But through a symbiotic collaboration between five tourism companies and marine scientists at the University of Technology Sydney, ‘coral gardening’ in underwater nurseries is trying to help preserve the country’s famed Great Barrier Reef.
Company divers – all intimately familiar with the reef and, like so many companies, dependent on its vitality – comb the seabed. There they collect coral fragments and attach them to submerged frames on which the fragments can recover and grow. Eco-conscious tourists pay to see the unusual attraction.
It’s a strategy aimed at giving “mother nature” a little boost, according to reef guide Russell Hosp. About 30 gardens are currently maintained and the healthy coral segments that thrive on their artificial underwater structures are then transplanted to damaged areas of the reef.
“Coral Gardening” in underwater nurseries attempts to preserve Australia’s famous Great Barrier Reef. (Video: Michael Robinson Chavez)
The Coral Nurture Program is just one of numerous projects along the Queensland coast, including one by the Reef Restoration Foundation, which has just seen its planted corals spawn for the first time. Together, these efforts aim to transform the reef by making it more resilient.
Adaptation solutions for coral nations were discussed at this month’s COP27 conference in Egypt. Peter Thomson, the UN Secretary-General’s special envoy for the oceans, told a panel he was a convert to the effectiveness of programs like coral nurseries after seeing the results in his native Fiji.
“Don’t accept the idea that coral reefs are going to die out,” he said. “We will reject this future.”
However, none of the advances can overcome unchecked global warming. “A 1.5 degree world is really a death knell for reefs,” warned Carol Phua, who leads the World Wildlife Federation’s Global Coral Reef Initiative.
The loss would be tragic. Corals are arguably the strangest of the many bewildering life forms found in the world’s oceans—animal, vegetable, and mineral all at once.
The animal is the polyp, a transparent, tentacled creature related to anemones and jellyfish. Coral polyps have squishy bodies but have evolved the wondrous ability to secrete calcium carbonate — the same material as limestone — for protection. These calcium carbonate barricades form the visible architecture of a reef.
Inside the polyp’s tissue are living algae called zooxanthellae. It is these single-celled organisms that give reefs their famous rainbow colors. And more importantly for the polyp, the algae provide food for their hosts by converting sunlight into proteins, fats and carbohydrates through photosynthesis.
Coral polyps have squishy bodies but have evolved the wondrous ability to secrete calcium carbonate, which makes up a reef’s visible architecture. (Video: Michael Robinson Chavez)
There are billions of coral polyps containing tens of billions of zooxanthellae hiding in the hard structure of the Great Barrier Reef. Each newborn polyp ingests algae and secretes rock, adding immeasurably to an ecosystem that has grown for 20,000 years.
The problem, said Emma Camp, co-founder of the Coral Nurture Program and marine biologist at the university, is that “corals have a narrow environmental niche or range that they’re typically happy to outlive.”
Coral algae can only survive in warmer waters. But when the temperature gets too high, instead of food, the algae begin to emit a toxic substance, which the polyp instinctively and protectively expels into the ocean.
The result is coral bleaching, and the strong images of reefs after an event show what corals look like with no algae inside. Unless the water temperature drops and the algae are allowed to return safely, the polyp will starve and the reef will remain colorless.
The Great Barrier Reef has experienced four bleaching events in different sections since 2016. Even if a coral colony survives, stress takes its toll. The coral takes time to recover and multiple bleachings in a short period of time are rather fatal. Some species cope better with heat than others, but when the most endangered species die, the reef’s diversity suffers.
Coral Nurture participants have planted nearly 77,000 corals over the four years of the program. Camp acknowledged that the numbers are small compared to the reef’s vastness — the length from Florida to Maine. “Where we’ve gotten with most current restoration efforts is that they’re local,” she said.
Alan Wallish appreciates this focus. He is a Cairns tourism company that has spent several decades on the reef and his company Passions of Paradise is one of the top five companies working with the University’s scientists. The idea, he said, is “to mind your own little patch.”
The other ongoing reef care initiatives run the gamut. Eye on the Reef, run by the Great Barrier Reef Marine Park Authority, is calling on crowds of divers sightseeing underwater to collect data while they’re there. A Southern Cross University-led Coral IVF project collects sperm and eggs from coral and fertilizes them in an ocean basin, depositing the larvae in degraded regions.
Mandubarra Indigenous rangers are also involved, working with recreational fishing group OzFish and researchers from James Cook University to establish seagrass beds. At a lab near Townsville, specialists from the Australian Institute of Marine Science are experimenting with a biodegradable, molecule-thick film that could block heat from entering the ocean.
Climate change remains the major caveat to all these initiatives. Human intervention projects “will be critical for decades to come,” said Scott Heron, an environmental physicist at the ARC Center for Excellence for Coral Reef Studies. But they will only be most effective if they advance in tandem with rapid reductions in greenhouse gas emissions.
“We need to address climate change and the causes of climate change in a coherent way so that we’re not putting both a blowtorch and a hose on the fire,” Heron said.
Against all odds, Hosp is actually quite optimistic when guiding visitors to the Great Barrier Reef. “The work we’re doing on the reef connects to work in Antarctica and Africa around the world,” he said. “There’s this concerted effort to solve the problem in as many ways as possible.”
“Honestly,” he added, “I think it’s a little early to tick the box and say that the reef, or any ecosystem, is a lost cause. Because it absolutely isn’t.”
