Reef Check Réunion Documents Most Severe Bleaching Ever

Submitted by Jean-Pascal Quod, Reef Check France

Reef Check Réunion, a chapter of Reef Check France in the south-west Indian Ocean, is very concerned by the most severe bleaching ever encountered in Réunion during the first months of 2025. The subsequent mortality was highly enhanced on some fringing reefs by the cyclone Garance that hit the island in late February.

Reef Check Réunion was initiated in 2003 and now comprises more than 35 sites monitored every year. All data are added to a global citizen database about coral reef health. This database is analyzed through an online dashboard; click here for a demonstration dashboard.

Additional activities of the Réunion team include creating awareness of marine pollution and impacts of sun creams as well as conducting field surveys on marine biodiversity to provide a diversity index for Reef Check sites. 

Figure 1 below reveals that, as for many other places on our blue planet, hard coral cover has been seriously declining for three decades, with a negative trend predicted for the coming years. Citizen Reef Check surveys in Réunion have proved to provide the same overall results as those obtained by scientists operating for the Marine Reserve (see Figure 1).