Scientists are warning of devastating coral bleaching on the Great Barrier Reef, off the coast of Australia’s eastern state of Queensland.

According to the local non-governmental organisation, Climate Council, new underwater images show the full extent of the disaster.

An area 1,100 kilometres long from Lizard Island to the Keppel Islands has already been affected, the Australian news agency AAP reported on Tuesday.

According to experts, the trigger is a recent marine heatwave in the region.

A project manager for the environmental monitoring group CoralWatch, Diana Klein, has said she has been visiting the Heron Island research station in the southern part of the Barrier Reef for 25 years.

She added that this was the worst bleaching event she had seen.

“Heron Island has luckily escaped several bleaching events in the last couple of years but the way it is looking now is just devastating,’’ she told AAP.

The island lies around 460 kilometres north of Brisbane, in the area affected by the current bleaching event.

The Great Barrier Reef is increasingly under threat due to global warming.

In difficult conditions, the corals repel the algae responsible for their colouring, with which they normally live together in a symbiotic relationship.

Bleached corals, cnidaria, are extremely stressed, but they are still alive and can recover.

According to experts, however, the extremely warm seawater makes them susceptible to diseases that can kill them.

If the water does not cool down in the coming weeks, it is only a matter of time before the bleached cnidarians die off, said Ms Kleine.

With water temperatures of up to 30 degrees Celsius, up to 80 per cent of the coral is bleached in some places.

The Climate Council has warned that the authorities could soon declare another mass bleaching.

“As ocean temperatures continue to increase, our precious Great Barrier Reef is in grave danger,’’ Climate Council’s Prof. Lesley Hughes told AAP.

Another Climate Council chief executive, Amanda McKenzie, said, “Our focus must be on limiting further harm as much as possible.

“Relentless pollution from coal, oil and gas is Australia’s number one environmental problem and it’s literally cooking the reef. Our environmental protection laws are outdated and in desperate need of an overhaul to prevent new reef-destroying gas and coal projects,’’ she said. 

(dpa/NAN)