Upolu, one of the nine islands of Samoa, in the Pacific Ocean. Well-known among fans of diving, this isolated coral reef promised to be a site of rich biodiversity for the scientists on the Tara Pacific expedition, principally from the CNRS, the CEA1 and the King Abdullah University of Science and Technology (KAUST) in Saudi Arabia. Although some signs of bleaching had been observed on their route, the reefs of Upolu proved to be in a far more degraded state: coral cover is below 10% in over 80% of the 124 sites considered. According to the scientists, this situation can be explained by a combination of global and local factors. Their study is published in the journal Marine Pollution Bulletin.