Could this world-first coral research save the Great Barrier Reef?

Queensland scientists have been trying to combat coral bleaching of the Great Barrier Reef, something that is of grave concern to environmentalists and governments alike. In an exclusive interview with SBS Chinese, an aquaculturist explains how his research could save the reef, one coral species at a time.

Key Points

• Chinese-Australian scientist leads a team that succeeds in breeding species of coral in a lab, six of which are world firsts.
• Captive breeding of some coral species may help with Great Barrier Reef restoration.
• Lab-bred heat-resistant coral can be planted into reefs to slow down their bleaching.

Every year, several days after a full moon, Luchang Shao returns to a lab of aqua tubs wearing a red headlamp and waits.

That's because coral spawning season has arrived.

Under red light, replicating lighting conditions in the natural underwater environment, he waits for when coral starts to spawn “one by one like firecrackers,” describing the event as “pure excitement and joy”.

Coral spawning is a natural, yearly phenomenon where various coral species simultaneously release sperm and eggs for fertilisation after the full moon.

Each bundle must find another bundle from the same species to fertilise.

Coral spawning in action on the Flynn Reef near Cairns in 2021. Credit: AAP/Gabriel Guzman Calypso Productions

In the laboratory, scientists capture sperm and eggs after spawning and fertilise coral artificially.

The team Mr Shao leads at Bundaberg’s Inter-Fish, an aquaculture farm, have so far spawned nine coral species in captivity, six of them world-firsts.

They’ve been at it since 2019 in a bid to combat mass bleaching on the Great Barrier Reef.

Since the 1980s, mass bleaching events have hit the heritage-listed reef six times due to heat stress.

The latest event was in 2022, which affected 43 per cent of surveyed reefs, according to the Australian Institute of Marine Science.

The United Nations’ Intergovernmental Panel on Climate Change identified tropical coral reefs as one of the most climate-vulnerable ecosystems on Earth, warning they would almost entirely disappear if global warming climbed to 1.5 degrees Celsius.

Today, temperatures are already around 1.1 degrees Celsius above pre-industrial levels.

We wonder how long the Great Barrier Reef will exist if bleaching happens again in the next three to five years.

Luchang Shao

Luchang Shao, an aquaculturist based in Queensland, explains how his research could save the reef, one coral species at a time. Credit: Luchang Shao

He explained that coral reef restoration needed a mass amount of heat-resistant coral ‘babies’ to survive in the current environment where they faced ocean warming and acidification.

While the asexual reproduction of coral – through budding or fragmentation – can only reproduce 10 to 20 genetically identical individuals at one time, sexual propagation can produce over 10,000 heterogeneous offspring simultaneously, Mr Shao explained.

Last month, the team sexually propagated the goniopora coral, known for their daisy-like appearance, from the reef’s southern end, for the first time in the history of such breeding.

It is extremely fascinating to see the 'coral babies' gradually grow from six tentacles to 12 and 24.

Luchang Shao

Rising ocean temperature caused by climate change is the primary reason for coral bleaching where many species prematurely turn pale and face extinction risks.

Hence, breeding programs led by scientists such as Mr Shao, have stepped in to propagate heat-resistant coral that is raised in aquaculture to be eventually placed on natural reefs in large quantities.

Goniopora, often called the 'flowerpot coral'. Dr Shao says it is rare to witness its growth from six tentacles to 24. Credit: Inter-Fish Pty Ltd

Flynn Reef coral spawning

“It is always great news when a new species or a new group of species are spawned either in the lab, in captivity or in the wild,” Kate Quigley, senior research fellow in Marine and Aquaculture Sciences at James Cook University, told SBS Chinese.

She explained that fundamental knowledge of coral spawn is “very critical for understanding recovery … under pressure from climate change, especially with something as large and complex as the Great Barrier Reef."

“There are hundreds of species on the Great Barrier Reef and we’re still discovering new species all the time,” she added.

Mr Shao’s team was also able to successfully spawn the scolymia coral in captivity last year, which is an endangered species that exists only in Australia.

Bleached coral near the Keppel Islands on the Great Barrier Reef. Source: AP / Ove Hoegh-Guldberg

I hope for this species to be bred in large numbers this year and released back into the wild.

Luchang Shao

Ms Quigley added that coral were complex, important animals for building the foundation of a reef, and that “hundreds and hundreds of coral species make up the kind of diverse ecosystem that we call a coral reef”.

However, she said that how much coral diversity was needed was a complex question.

In order to preserve the ecosystem which contains different kinds of structures, organisms and functions provided by various species, Ms Quigley remarks that “the more species, the better” it is for marine biology.

Once the fimpbriaphyllia 'coral babies' spawned by Inter-Fish have passed their 'green colour phase', they gradually start showing their true colours. Credit: Inter-Fish Pty Ltd

“We slowly increase the water temperature during the aquaculture process, screen out a group of species that are tolerant to high temperatures, and then go on to breed the second generation,” Mr Shao said of lab-bred species that would have a higher survival rate in the wild.

He adds that, ideally, coral restoration should attempt to restore genetic diversity for the importance of preserving the genetic integrity of populations based on the studies of coral scientists.

But the one thing that we can do to really help the fate of the Great Barrier Reef and reefs around Australia is to have strong action on climate change.

Kate Quigley

"We know that corals live very close to their temperature tolerance. There are some good news stories about adaptation potentials, but the best thing we can do is to have strong action on climate change,” Ms Quigley told SBS Chinese.

The joys and difficulties of raising 'coral babies'

Mr Shao describes the captive-bred coral as his “second baby”.

I only have photos of my baby son and my 'coral babies' on my phone.

Luchang Shao

“Every day is fresh. Every day, I witness something happening as a first in the world,” he said, describing how his field of work was one of the most complicated in aquaculture science.

The coral tank at Inter-Fish for captive breeding. Credit: Inter-Fish Pty Ltd

Scientists have yet to identify what natural factors trigger coral spawning, an annual procreation event for this form of organism.

The small window of time to experiment with the specimens means failure was not unusual, Mr Shao said.

A spawning system needs to imitate the natural environmental changes of seasons, taking lunar tides, sunlight, water temperature and light intensity into consideration.

“Any lapse in these conditions means wasting a year’s effort,” said Mr Shao.

“Usually, spawning could happen any day during the week after the full moon and I will observe them in that period. But once, I went there two days late and observed nothing,” Mr Shao recalled after a time he missed the coral spawn.

Mr Shao said captive breeding of coral had not been widely developed in the world. Credit: Inter-Fish Pty Ltd

At Inter-Fish, after the breeding, the establishment of the 'coral babies' is another barrier.

'Coral babies' were resistant to being established on the settlement tiles made of specific materials with biofilm and artificial grooves, followed by battles for coexistence with various other organisms in the water, for example, algae.

“Algae grows faster than coral babies and the latter could die from lack of lighting and reef salt because of the former developing,” Mr Shao said.

The captive breeding technique of coral is not widely developed in the world, which makes the results produced by Mr Shao and his team more fascinating.

I invited a professor who studied coral for over 40 years at James Cook University (to visit our lab), and he said he had never seen some of the coral species we bred.

Luchang Shao

He said the result could also benefit other researchers in the same area.

Mr Shao added that the captive-bred coral could provide eggs for PhD candidates studying the coral larval life history which had never been recorded as it was almost impossible to measure in the natural marine environment.

This kind of study could also assist with assessing coral growth rates and restoration efforts on the Great Barrier Reef restoration, he added.

“I hope, in the future, we will have the chance to replant them on to the Great Barrier Reef and (assist) the reef adapt to the new environmental challenges,” he said.