“Coral gardening” aims to help the Great Barrier Reef fight climate change

Underwater gardens, where coral chips are grown, are among efforts to help protect coral reefs from climate change

A school of fish swims through a breach in the coral along Australia's Great Barrier Reef.  Bleaching events caused by warming seas have caused significant damage to coral reefs.  (Photo by Michael Robinson Chavez/The Washington Post)
A school of fish swims through a breach in the coral along Australia’s Great Barrier Reef. Bleaching events caused by warming seas have caused significant damage to coral reefs. (Michael Robinson Chávez/The Washington Post)


The world off the northeastern coast of Australia is magical yet beleaguered, a place of stunning colors in good times but ghostly white in bad. The bad news has occurred repeatedly in recent years as climate change-related warming of the seas has bleached the vast underlying coral ecosystem.

But through a symbiotic collaboration between five tour companies and marine scientists from the Sydney University of Technology, “coral gardening” in underwater nurseries is seeking to help preserve the country’s famed Great Barrier Reef.

Company divers – all very familiar with the reef and, like so many companies, addicted to its vitality – scour the seabed. There they collect broken pieces of coral and attach them to submerged structures on which the fragments can recover and grow. Eco-minded tourists pay to see the unusual attraction.

It’s a strategy that reef guide Russell Hosp says aims to give “Mother Nature a little boost.” About 30 gardens are currently being grown and the healthy coral segments that thrive on their man-made underwater structures are then transplanted into the damaged areas of the reef.

“Coral gardening” in underwater nurseries is trying to help preserve Australia’s famous Great Barrier Reef. (Video: Michael Robinson Chávez)

The Coral Nurture Program is just one of several projects along the Queensland coast, including one, run by the Reef Restoration Foundation, which has just seen planted coral spawn for the first time. Together, these efforts aim to transform the reef into a more resilient one.

This month’s COP27 conference in Egypt discussed adaptation solutions for coral nations. Peter Thomson, the UN secretary-general’s special envoy for the oceans, told a panel he was converted to the effectiveness of programs such as coral hatcheries after seeing the results in his native Fiji.

The Great Barrier Reef has the most coral in decades. Global warming could reverse that.

“Don’t accept the idea that coral reefs will become extinct,” he said. “We will reject that future.”

However, none of the progress can overcome runaway global warming. “A 1.5-degree world is truly a death knell for coral reefs,” warned Carol Phua, who leads the World Wildlife Federation’s Global Coral Reef Initiative.

The loss would be tragic. Corals are undoubtedly the strangest of the many puzzling life forms that can be found in the world’s oceans, simultaneously animal, vegetable and mineral.

The animal is the octopus, a transparent and tentacular creature related to the anemone and the jellyfish. Coral polyps have soft bodies but have evolved the miraculous ability to secrete calcium carbonate, the same material as limestone, for protection. These calcium carbonate barricades form the visible architecture of a coral reef.

Inside the tissue of the polyp are living algae called zooxanthellae. It is these single-celled organisms that give coral reefs their famous rainbows of color. And most importantly for the octopus, the algae provide food for their hosts, transforming sunlight into proteins, fats and carbohydrates through photosynthesis.

Coral polyps have soft bodies but have evolved the miraculous ability to secrete calcium carbonate, which forms the visible architecture of a coral reef. (Video: Michael Robinson Chávez)

There are billions of coral polyps, containing tens of billions of zooxanthellae, hidden within the tough structure of the Great Barrier Reef. Each newborn octopus absorbs algae and secretes rock, infinitely adding to an ecosystem that has been growing for 20,000 years.

One man’s lonely quest to save the world’s corals attracts a sequel

The problem, said Emma Camp, co-founder of the Coral Nurture Program and academic marine biologist, is that “corals have a narrow environmental niche, or range, in which they typically like to survive.”

Coralline algae can only survive in warmer waters. But when the temperature gets too hot, the algae begin to emit a toxic substance instead of food, which the octopus instinctively and protectively expels into the ocean.

The result is coral bleaching and sharp pictures of the reefs after an event show what the corals look like with no algae inside. Unless the water temperature drops and the algae can return safely, the polyp starves and the reef remains colorless.

The Great Barrier Reef has experienced four bleaching events in various sections since 2016. Even when a coral colony survives, the stress takes its toll. Coral needs time to recover, and more bleaching in a short period is more likely to be fatal. Some species tolerate heat better than others, but when the most vulnerable species die, the diversity of the reef suffers.

The would-be “coral factory” restoring coral reefs destroyed by climate change

Coral Nurture participants planted nearly 77,000 corals over the four years of the program. Camp acknowledged that compared to the barrier reef’s sheer size — Florida’s equivalent length to Maine — the number is small. “Where we are with most of the current restoration efforts is that they’re local,” she said.

This attention is something Alan Wallish appreciates. He’s a tour operator in Cairns who has spent several decades on the reef, and his business, Passions of Paradise, is among five lead companies partnering with scientists from the university. The idea, he said, is to “take care of your own little plot.”

The other initiatives underway to feed the reef run the gamut. Eye on the Reef, led by the Great Barrier Reef Marine Park Authority, enlists the masses of divers who visit underwater to gather data while they’re there. A “Coral IVF” project, led by Southern Cross University, collects coral sperm and eggs and fertilizes them in an ocean pool, depositing the larvae in degraded regions.

Indigenous rangers of the Mandubarra people are also involved, working with recreational fishing group OzFish and researchers at James Cook University to plant kelp beds. In a lab near Townsville, specialists at the Australian Institute of Marine Science are experimenting with a molecule-thick biodegradable film that can block heat from entering the ocean.

The race to save Florida’s diseased corals

Climate change remains the big warning for all of these initiatives. Human intervention projects “will be essential” in the coming decades, said Scott Heron, an environmental physicist at the ARC Center for Excellence for Coral Reef Studies. But they will only be more effective if they go hand in hand with a rapid decline in greenhouse gas emissions.

“We need to address climate change and the causes of climate change in a policy-consistent way so that we don’t set a blowtorch as well as a hose on the fire,” Heron said.

Despite the odds, Hosp is actually quite optimistic as he guides visitors on the Great Barrier Reef. “The work we’re doing on the reef is concurrent with work being done in Antarctica, and in Africa, around the world,” he said. “There’s this concerted effort to try and fix the problem any way we can.”

“Honestly,” he added, “I think it’s a bit early to tick the box and say that the coral reef, or any other ecosystem, is a lost cause. Because it absolutely isn’t.”

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