The past 27 years has seen a shocking reduction in the amount of coral cover in Australia's Great Barrier Reef — according to a new study, it's down to half the size it was in 1985.

This rather depressing analysis shows a drop of 50.7%, thanks to data gathered from more than 2,000 surveys of 214 reefs. They were even able to break down the cause of this decline into three sections: storm damage (48%), bleaching (10%), and a full 42% can be attributed to the crown of thorns starfish.

In a press release John Gunn, CEO of Australian Institute of Marine Science (AIMS) said:

"We can't stop the storms, and ocean warming (the primary cause of coral bleaching) is one of the critical impacts of the global climate change. However, we can act to reduce the impact of crown of thorns."

The crown of thorns is an interesting creature. It's widely spread throughout the Pacific, and feeds specifically on the coral polyps. Its numbers have dramatically increased in the last few decades — possibly through the decline of predation — and because of that, it's causing significant damage.


Right now, the coral cover is declining at rate of 3.38% per year — and if all three causes were prevented, it would be growing at 2.85%, but if just the starfish could be contained, the coral cover would increase at 0.89% per year. It's not a lot, and it's not fast, but it would be enough to offset the other damages.

Images via Paul Toogood/Flickr.