1In 2016, collaboration with an Australian team prompted IRD researchers working in New Caledonia to inventory all corals located near mangroves. In Bouraké, they found a surprising coral reef which thrived under extreme temperature, pH and oxygenation conditions. These environmental conditions seemed similar to those expected by the end of the century which, based on experiments conducted in aquariums, could spell doom for corals. Consequently, these projections are moderated by the discovery of the New Caledonian site.

Studying coral bleaching, New Caledonia.

••• Some corals can survive under totally unexpected physical-chemical conditions •••

2Researchers have been examining this unique site since 2016, considered to be a natural laboratory for studying the ability of coral reefs to adapt to environmental changes. They discovered that 50-odd coral species have adapted to this more acidic, warmer and oxygen-poor environment. Surprisingly, elsewhere in the world these very species are the first to die from severe heat.

Coral bleaching, New Caledonia.

3During the 2016 heatwave, only 20% of corals from the “laboratory site” in Bouraké suffered from bleaching, compared with 100% for the rest of New Caledonia. This unexpected resilience may be due to symbiosis with a specific, heat-resistant single-celled alga, but also to factors which remain to be discovered but are probably linked to the proximity to mangroves. To find out more, researchers monitored the environment, attempted various experiments and analysed the genetic material of the algae.

4The presence of corals living in these environmental conditions, similar to and even worse than those expected by 2100, sparks hope that some corals might survive global warming, and even that some of the damaged areas might be salvaged or repopulated.

“The coral reef ecosystem forms a fundamental and vital part of New Caledonia’s natural and cultural heritage; it nurtures people in every sense of the word, while actively participating in the construction of codes of conduct for society and building its identity.” 
Didier Poidyaliwane, government official in charge of customary matters, ecology, sustainable development, relations with the Customary Senate, customary councils and customary lands, New Caledonia