Coral reefs, often referred to as the "rainforests" of the seas, are among the most diverse and productive ecosystems on the planet. Research, such as that of Andréfouët et al. (2008), estimates that coral reefs occupy approximately 57,557 km², an area twice the size of the land they surround. These underwater formations are home to one third of marine species, despite their increasing vulnerability to environmental pressures.
France, through its overseas territories, owns nearly 10% of the world's reefs and 20% of its atolls, making the country a key player in protecting these ecosystems. These reefs are mainly found in the Indian, Atlantic and Pacific Oceans, and contribute to the extent of the French Exclusive Economic Zone, one of the largest in the world at over 11 million km².
Coral reefs are not just beautiful limestone structures. They play a fundamental role in the ocean ecosystem. Reef-building corals, for example, build their limestone skeletons over centuries, providing shelter for a multitude of species. Fish, turtles, rays, and other marine creatures depend on these reefs to survive. Yet corals are fragile. Rising sea temperatures due to global warming are affecting their symbiosis with zooxanthellae, tiny algae that live in coral tissue and provide essential nutrients through photosynthesis. This breakdown of the symbiotic bond causes coral bleaching, a phenomenon observed with increasing frequency on reefs around the world.
French overseas territories, such as French Polynesia or Clipperton, are home to a diversity of reefs ranging from coral reefs to fringing reefs. These reefs are a testament to nature’s resilience, but also its great vulnerability. Each tiny but essential coral polyp captures solar energy and feeds on zooplankton to grow and form underwater cities that support thousands of other forms of life.
Despite their vital role in the ocean ecosystem, coral reefs are under immense pressure, exacerbated by human activities. Urgent action is needed to reduce the impacts of climate change, protect these ecosystems and ensure their survival for future generations.
Sources
Andréfouët, S., et al. (2008). "Reefscape diversity of French Polynesia and the island biogeography of its coral reefs." Coral Reefs , 27(4), 999-1005.
