example from NY Times

Over the last 27 years, the study found, coral cover across the 133,000-square mile stretch of the Great Barrier Reef has fallen to 13.8 percent over all, from 28 percent. The study broke down the causes of the decline, attributing 48 percent of coral loss to cyclones, 10 percent to coral bleachingand the remainder — 42 percent — to excessive spawning of destructivecrown of thorns starfish. The starfish, believed by researchers to prosper when artificial nutrients increase in oceans, consume and destroy more than their fair share of live coral cover.