'Zero recovery' for corals in back-to-back Australia bleaching

Sydney : Coral bleached for two consecutive years at Australia's Great Barrier Reef has "zero prospect" of recovery, scientists warned Monday, as they confirmed the site has again been hit by warming sea temperatures.

Researchers said last month they were detecting another round of mass bleaching this year after a severe event in 2016, and their fears were confirmed after aerial surveys of the entire 2,300-kilometre (1,400-mile) long bio-diverse reef.

Last year, the northern areas of the World Heritage-listed area were hardest hit, with the middle-third now experiencing the worst effects.

"Bleached corals are not necessarily dead corals, but in the severe central region we anticipate high levels of coral loss," said James Kerry, a marine biologist at James Cook University who led the aerial surveys.

"It takes at least a decade for a full recovery of even the fastest growing corals, so mass bleaching events 12 months apart offer zero prospect of recovery for reefs that were damaged in 2016."

It is the fourth time coral bleaching -- where stressed corals expel the algae that live in their tissue and provide them with food -- has hit the reef after previous events in 1998 and 2002.