In depth article on coral reefs at Skeptical Science

Figure 6. Example of a French Polynesian reef devastated by a COTS outbreak. A, healthy reef with cover in excess of 40%; B, algae have colonized the reef after attack by COTS; C, weakened or dead coral are swept away by a cyclone leaving less than 5% living coral cover. From Kayal (2012). 

For article go to this link:  http://www.skepticalscience.com/Australias-Great-Barrier-Reef-Last-Chance-to-See.html