Coral reefs are a food source for coastal populations and play a crucial role as a barrier against swells and tsunamis. These stunning, vast reefs are constructed by tiny animals: corals – they grow by cloning themselves and building colonies with a hard skeleton. Climate change threatens the very existence of these reefs as we know them: When the water gets above a certain temperature, corals “bleach” and essentially starve to death, threatening the entire reef. [Photo by Rachel Moore]

A race against the clock

Scientists are racing against the clock to study coral reef organisms. “There are still many things we do not know about corals: for instance, how and when certain species reproduce, what the best ways are to upscale coral restoration, and what future reefs will look like” explains marine biologist and AFR PhD researcher Camille Leonard. Coral restoration techniques have become more widespread and more efficient in recent years: Scientists have developed methods to breed and have corals spawn in captivity, and can freeze coral eggs for preservation. [Photo by Rachel Moore]

Additionally, researchers have found ways to seed millions of coral larvae on degraded reefs and rebuild destroyed reefs with artificial structures. To make the reefs more future-proof, the corals are pre-exposed to predicted ocean temperatures and acidity, with the aim to create more resistant coral hybrids – they can even change their symbionts to increase their heat resistance. [Photo by Jules Schligler]

Coral trees to grow new reef fragments

Camille Leonard is a marine biologist at EPHE in Paris and CRIOBE in French Polynesia. As part of her AFR PhD project, she is trying to understand how corals reproduce and how marine biologists can best use them in restoration techniques. “I am trying to see whether coral nurseries can be used to select and grow coral fragments that are potentially more resistant to heat waves. [Photo by Rachel Moore]

“We installed ‘coral trees’ in the shallow lagoon and on the deeper forereef in Mo’orea, in French Polynesia. When the fragments reach a certain size, they can be planted back onto the reef. I am comparing their growth and health in these different environments. “During spawning, we can study their reproduction and seed their larvae onto degraded areas. I am also collaborating with a company called SEABOOST to find the best materials and shapes for building artificial reefs.” [Photo by Mathieu Reynaud]