Great Barrier Reef’s worst bleaching leaves giant coral graveyard: ‘It looks as if it has been carpet bombed’

A snorkeller above bleached and dead staghorn coral off Heron Island in the Great Barrier Reef Photograph: Mike Bowers/The Guardian

Beneath the turquoise waters off Heron Island lies a huge, brain-shaped Porites coral that, in health, would be a rude shade of purplish-brown. Today that coral outcrop, or bommie, shines snow white.

Prof Terry Hughes, a coral bleaching expert at James Cook University, estimates this living boulder is at least 300 years old.