Parts of Australia’s iconic Great Barrier Reef, famed for its stunning colors and biodiversity, suffered the biggest decline of coral on record last year after a marine heatwave bleached vast swathes of hard coral,

Parts of the Great Barrier Reef have suffered the steepest annual decline in live coral cover following the worst bleaching events in nearly four decades. The Australian Institute of Marine Science, or Aims, said that two of the three areas monitored by researchers since 1986 have suffered coral losses this year.

The Great Barrier Reef has experienced its greatest annual loss of live coral across most of its expanse in four decades of record-keeping, Australian authorities say.