A naturally occurring predator to coral reefs in the Great Barrier Reef is the Crown of Thorns sea star (Acanthaster planci). Population outbreaks of the Crown of Thorns sea star are one of the major causes of coral decline across the Great Barrier Reef, as an adult crown-of-thorns starfish is capable of consuming up to 10 m2 of reef building coral a year. However, each species of coral is not equally impacted, as the sea star has been observed to favor branching species of coral, Acropora, followed by a sub branching species. This results in a sequential and ordered eradication of coral reef species. 
Crown of Thorns Sea Star outbreaks on the Great Barrier Reef have become more frequent in recent years, which scientists predict could be linked to human activities. Any increase in nutrients, possibly from river run-off, can positively affect starfish populations, leading to detrimental outbreaks. As pressures from climate change increase, the time between reef disturbances is becoming shorter, leaving less time for reef recovery.