At just 16, Titouan Bernicot looked beneath the waves off his home island of Moorea and saw a reef in trouble. Instead of simply watching the corals disappear, the Polynesian surfer began gathering broken pieces, coaxing them back to life in underwater nurseries, and returning them to the sea. What started in 2017 as a small experiment in French Polynesia has since grown into an international effort that has planted more than 221,000 corals across French Polynesia, Fiji and Thailand.
Bernicot grew up on Moorea, where he witnessed the gradual decline of the coral reefs around the island. That early worry turned into action when, as a teenager, he founded an organisation called Coral Gardeners to restore Moorea's damaged reefs. His method draws on a restoration approach known as coral gardening. In this technique, fragments are taken from living coral colonies and grown in nurseries until they are large enough to be transplanted back onto damaged reef areas. Many reef-building corals can reproduce through fragmentation, meaning a broken piece can survive and grow into a new colony under the right conditions. Coral Gardeners began with small underwater nurseries in Mo'orea before expanding its work across the region.
But planting corals is only part of the story. A fragment that survives in a nursery must still cope with waves, predators, disease, warmer water and competition once it returns to the reef. That is why restoration efforts increasingly focus not just on producing more corals, but on identifying colonies that may be better able to withstand environmental stress. Coral Gardeners has incorporated this idea by collecting fragments from coral colonies that have survived difficult conditions and using those in its nurseries. The organisation has also adopted cameras and digital tools to track individual corals and document changes at restoration sites, reflecting a broader shift towards measuring how well restored corals persist over time.
Research backs up this careful approach. A global review published in PLOS One found that nursery-grown corals can survive and grow after transplantation, although results vary with coral species, nursery conditions, reef location and environmental pressures. A study in Restoration Ecology similarly found that the survival of transplanted staghorn corals depended on colony size, location, habitat and the year of transplantation. In other words, restoration outcomes depend on where and how corals are grown and planted, not simply on how many fragments are produced.
The biggest limitation of Bernicot's work is that coral restoration cannot remove the pressures driving coral decline. The growing threat is marine heatwaves, which cause corals to expel the microscopic algae that provide them with energy and colour — a process called coral bleaching that can be fatal. Eventually, even nursery-raised coral will face the same warming as wild colonies.
Yet the goal of coral gardening is more ambitious than simply placing coral on the seabed. For restoration to succeed, the final result should be coral colonies able to reproduce and rebuild the reef. For Bernicot and his team, the underwater nursery is a tool, not a goal. While the project cannot reverse ocean warming on its own, growing coral helps degraded reefs recover, and choosing colonies resilient to harsh conditions may help protect corals from extinction.