The remaining two-fifths, they say, was predation by the crown-of-thorns starfish.

ECONOMIST: The Great Barrier Reef: Dr De��ath v the killer starfish | The

The World Wildlife Fund offers a commercial tour in Palau, Micronesia on which snorkelers can help their guide remove the invasive crown-of-thorns starfish, which every day eat their weight in coral polyps from fragile reefs.

BBC: Hunting possums �C and ecological balance �C in New Zealand

John Gunn, head of AIMS, said it was difficult to stop the storms and bleaching but researchers could focus their short-term efforts on the crown-of-thorns starfish, which feasts on coral polyps and can devastate reef cover.

BBC: Half of Great Barrier Reef coral lost in last 27 years

Glen De'ath from the Australian Institute of Marine Science (AIMS) and colleagues determined that tropical cyclones - 34 in total since 1985 - were responsible for 48% of the damage, while outbreaks of the coral-feeding crown-of-thorns starfish accounted for 42%.

BBC: Half of Great Barrier Reef coral lost in last 27 years