Reef Reborn

While they host 25% of all marine life, tropical coral reefs are currently being decimated by the effects of climate change. Over the last 20 years, more than half the corals in the Great Barrier Reef have died, jeopardizing the livelihoods of local populations and economic actors. Current restoration initiatives based on cuttings from adult colonies show limited success and do not allow genetic renewal (thus long-term adaptation); and on the other hand, natural repopulation is limited by the low survival rate of larvae (less than 1%).

The Reefs Reborn team have developed a unique cocktail of lipid nanoparticles; with their metabolism boosted by this “super-fat plankton”, 46% of the larvae ultimately form new colonies. The project aims to optimize this cocktail, both in the pre-introduction stage of feeding larvae in nurseries, and directly on priority high-value reef areas. Methodological guides and videos will be disseminated to promote reef restoration on a larger scale.

Tropical coral reefs are the ecosystems most threatened by climate change. The warming of surface waters and increasing frequency of marine heat waves are causing coral bleaching and the disappearance of reef-dwelling species, which account for about 1/4 of the world’s marine life. 98% of the Australian Great Barrier Reef is affected, and more than half of the corals have died in the last 20 years. Almost all current reef replenishment initiatives consist of cuttings of then-resistant adult corals, with the short-term objective of maintaining the ecosystem services they used to provide (including fishing resources and tourist attraction). But these colonies of the same genetic heritage (clones) are particularly sensitive to bacterial and viral infections and offer no guarantee of resistance to further warming. Sexual reproduction of corals allows for genetic innovations, and favors long-term resilience of the reefs, but less than 1% of larvae reach adulthood. Jennifer Matthews’ team has developed an energy mix in the form of lipid nanoparticles, allowing 46% of larvae to eventually form new colonies. The project aims to (1) adapt the quality and quantity of the cocktail to the water temperature, and (2) develop a simple feeding strategy, both to make it affordable and easily replicable by local stakeholders. It includes a double phase of ex-situ experiments in laboratory nurseries before reintroduction, and in-situ experiments on some high value sites of the Great Barrier Reef. The results will be shared in the form of methodological guides and demonstration videos to encourage wider adoption, and thus hope to improve the resilience of warm-water coral reefs.