Forty eight per cent of the depletion is as a result of storm damage, while thorn starfish were responsible for much of the remaining destruction.
The decline has been more pronounced in the southern regions of the reef where storms have been more prevalent.
John Gunn, CEO of The Australian Institute of Marine Science, who carried out the research, said “We can’t stop the storms but, perhaps we can stop the starfish.
“If we can, then the Reef will have more opportunity to adapt to the challenges of rising sea temperatures and ocean acidification.”
The £30m, 25-year study, suggests that the reef could half again by by 2022 if action isn’t taken.