For the past two years Australian scientists have been collecting and storing billions of reproductive cells from the Great Barrier Reef, hoping that this “spawn bank” will one day help rebuild and preserve the World Heritage site. The reef, a popular tourist site worth billions of dollars annually to the Australian economy, is threatened by dredging, sedimentation and disease. Global issues such as ocean acidification and warming due to climate change also affect the reef’s health. Coral spawning takes place when colonies and species of coral simultaneously release egg and sperm cells for external fertilisation. It occurs only once a year, in the spring and after a full moon, turning vast swathes of the ocean red with a slick of the cells. “We are able to collect many billions of cells each year and keep adding genetic diversity,” said Rebecca Spindler, from the Taronga Conservation Society Australia. The sperm and egg cells are collected and frozen separately, on site, then brought back to the Taronga Western Plains Zoo in the town of Dubbo, some 400km northwest of Sydney. If needed, the cells could be mixed and fertilised in laboratories, then grown and transplanted to damaged reefs, although the team has yet to do so. “Because of the success of fertilising in vitro and the lack of predation we have many more viable cells that could be grown into adult coral,” Spindler told Reuters. The techniques they use, dubbed the Reef Recovery Initiative, were originally developed by Smithsonian Institution researcher Mary Hagedorn and have been applied to reefs in Hawaii and the Caribbean. “In the long term, we should be able to re-seed large areas of the reef. By restoring these localized sections we add to the resilience in strength of the reef as a whole,” Spindler said. “This is the only area in the world that has established the bank with a consistent plan to restore into the future.” Heralded as one of the seven natural wonders of the world, the 2,000 km Great Barrier Reef is home to 400 types of coral, 240 species of birds and 1,500 species of fish. It is worth A$6 billion a year in tourism to the economy. The Australian government pledged to stop coal port or shipping developments that could cause damage to the reef earlier this month as it responded to a February deadline calling for signs of progress amid UN warnings that the reef’s conservation status could be downgraded.