Coral is an indicator species and the state of the world's coral reefs provide insight into the health of "the system" (at the world-wide level). From the Caribbean to the Med to the Great Barrier Reef, it appears that living coral are disappearing and this survey will verify the "80% loss" estimates for the Caribbean. https://www.theguardian.com/environment/2013/aug/01/caribbean-coral-reef-loss