In a first for Australia's Great Barrier Reef, coral babies from frozen sperm have been introduced onto the threatened underwater landscape.
Early reports from the pilot suggest offspring from the thawed coral sperm cells are not only surviving but thriving in what scientists are describing as a major milestone in reef restoration.
Reproductive biologist at Taronga Conservation Society Australia, Dr Justine O’Brien, has been working on coral cryopreservation for years as part of a broader suite of work aimed at protecting climate-vulnerable reefs.
"We know that a business-as-usual approach is not going to be enough in a warming future," she told AAP.
Coral reefs are in the firing line of global heating caused by excess greenhouse gas emissions in the atmosphere.
The Great Barrier Reef has been struck by five mass bleaching events in eight years and Australia's west coast, including the Ningaloo Reef famous for its whale sharks, is presently under pressure from a severe marine heatwave.
It's on this backdrop that the Reef Restoration and Adaptation Program began several years ago, with Taronga working alongside the Great Barrier Reef Foundation, the Australian Institute of Marine Science, Traditional Owners and many others to improve the resilience of reefs.
Taronga's involvement has focused on cryopreservation, with the organisation a world-leader in the technology.
It's still early days but the aim is to use cryo-born coral babies to help repopulate reefs after marine heatwaves and other damaging events.
Securing genetic diversity is another driver.
There are close to 400 species of coral on the Great Barrier Reef and so far there are more than 30 stored at the bio-banks at Taronga's zoos in Sydney and Dubbo.
Sperm cells are collected on the reef during spawning events and then placed into liquid nitrogen at very low temperatures, pausing metabolic processes until thawed.
With so many species to collect, Dr O'Brien said prioritisation was inevitable, with heat-tolerant and "reef building" structurally-supportive corals top-tier candidates.
"It's much like the trees in a rainforest; protect the trees and then you protect many many other species as well," she said.
Roughly a quarter of all marine life, including fish, rely on coral reefs at some stage in their life cycle.
Researchers have been working closely with Traditional Owners, Taronga conservation biologist Dr Jon Daly explained during a tour of the Sydney coral cryo-diversity bank facilities as part of Climate Action Week.
During a mass coral spawning collection project in 2022, scientists worked alongside First Nations people on Konomie, North Keppel Island, in Woppaburra sea Country in Central Queensland.
"That was a good opportunity to have a lot of informal conversations with Traditional Owners about what it meant to them for us to be collecting samples from their sea Country and then moving them down to here," he said.
This led to broader consultation and an eventual framework to ensure biobanking samples are being collected and managed in a culturally-safe way.
