Australia's Great Barrier Reef hit by record bleaching: authorities

Australia's spectacular Great Barrier Reef is experiencing its worst bleaching event on record, the country's reef authority reported on Wednesday.

"The cumulative impacts experienced across the reef this summer have been higher than previous summers," the federally funded Marine Park Authority said in a statement.

Often dubbed the world's largest living structure, the Great Barrier Reef is a 2,300-kilometre (1,400-mile) long expanse, home to a stunning array of biodiversity including more than 600 types of coral and 1,625 fish species.

But aerial surveys conducted by the scientists show about 730 out of more than 1,000 reefs spanning the Great Barrier Reef have bleached, the authority said.

Coral bleaching occurs when coral expel microscopic algae, known as zooxanthellae, to survive. If high temperatures persist, the coral can eventually turn white and die.

This event is the fifth mass bleaching on the reef in the past eight years.