Great Barrier Reef - Catastrophe

Australian Institute of Marine Science senior scientist Hugh Sweatman says the reef's health has decreased dramatically.

Half the Great Barrier Reef's coral has disappeared in the past 27 years and less than a quarter could be left within a decade unless action is taken, a landmark study has found.

A long-term investigation of the reef by scientists at Townsville's Australian Institute of Marine Science found coral had been wiped out by intense tropical cyclones, a native species of starfish and coral bleaching.

Researchers warned that while the World Heritage listed reef was a dynamic system — with coral cover rising and falling over time — if the mass die-off continued less than 25 per cent would exist in 2022.

"The big concern going forward is that if nothing else changes than within 20 years the reef could be in a perilous state," said institute senior scientist Peter Doherty .

At 214 reef sites surveyed, the coral cover halved from 28 to 13.8 per cent between 1985 and 2012.

Two-thirds of the loss occurred since 1998. Only three of the 214 reef sites exhibited no impact.

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