Reef Reborn

Home to 25% of all marine life, tropical coral reefs are now being decimated by the effects of climate change: in 20 years, over 50% of the corals in Australia’s Great Barrier Reef have died, endangering local populations and economic players. Current initiatives to repopulate corals by taking cuttings from adult colonies have had limited success, and do not allow for genetic renewal (and hence long-term adaptation). Natural repopulation is limited by the low survival rate of larvae (less than 1%). Researchers working on the Reefs Reborn project have developed a unique cocktail of lipid nanoparticles; with their metabolism boosted by this “super-fat plankton”, 46% of larvae eventually settle into colonies. The project aims to optimize this cocktail, both for feeding larvae in nurseries prior to reintroduction, and directly on priority reef areas. Methodological guides and videos will be disseminated to promote reef restoration on a wider scale.

Tropical coral reefs are the ecosystems most threatened by climate change. Warming surface waters and increasing marine heatwaves are causing coral bleaching and the disappearance of reef-dwelling species, which account for around 1/4 of the world’s marine life. 98% of Australia’s Great Barrier Reef is affected, and more than half of all corals have died in the last 20 years. Almost all current reef repopulation initiatives involve the cutting of hardy adult corals, with the short-term aim of maintaining the ecosystem services they once provided (including fishing resources and tourist appeal). However, these colonies of the same genetic make-up (clones) are particularly sensitive to bacterial and viral infections, and offer no guarantee of resistance to further warming. Sexual reproduction in corals enables genetic innovation, and promotes long-term reef resilience, but less than 1% of larvae reach adulthood. Jennifer Matthews’ team has developed an energy mix in the form of lipid nanoparticles, enabling 46% of larvae to eventually form new colonies. The project aims to (1) adapt the quality and quantity of the cocktail to water temperature, and (2) develop a simple feeding strategy, to make it affordable and easily replicable by local players. It includes a double phase of ex-situ experimentation in laboratory nurseries prior to reintroduction, and in-situ experimentation at selected high-value sites on the Great Barrier Reef. The results will be shared in the form of methodological guides and demonstration videos to encourage their adoption on a wider scale, and thus hope to improve the resilience of warm-water coral reefs.