Scientists are warning that a “lot of coral will be lost” as the infamous crown of thorns starfish swarm over the world heritage treasure.

Alerts that the starfish are targeting parts of Australia’s 1,400-mile long natural wonder come in the wake of a shock scientific warning that the planet’s corals are under increasing attack from “bleaching” events.

The once 25-year cycle when warming waters left the stone-hard living creatures turning to white skeletons are now occurring every six years because of climate change.

In 2016, an environmentalist penned an “obituary” for the Great Barrier Reef, warning that two successive bleachings had brought about its death at the age of 25 million years.

After hopes for the reef were boosted recently with the discovery a hundred areas which had escaped the catastrophic damage, comes a New Year warning that its coral structures are now facing another deadly foe.

The predatory crown of thorn starfish that use digestive enzymes to liquefy coral tissue have been found in “plague proportions” amid the Swains Reefs sector, about 120 miles offshore and 300 miles north of the Queensland state capital of Brisbane.

Hugh Sweatman, a senior research scientist at the Australian Institute of Marine Science, said: “Each starfish eats about its body diameter a night, and so over time that mounts up very significantly – a lot of coral will be lost,” warned.”

There have been four major crown of thorn outbreaks since the 1960s along the Great Barrier Reef and only last month its park officials were in action killing starfish in the Swains Reefs area.

Yet wiping out the foot-wide creatures covered in venomous spines is a challenge.

Fred Nucifora, a director Great Barrier Reef Marine Park Authority, told Australian Broadcasting Corporation: “The complexity with the Swains Reef location is... they are logistically difficult to access and it is actually quite a hostile environment to work in.”

The cause of the latest starfish eruption is not known but their numbers are believed to increase when nutrient levels rise in seawater.

As the starfish attack from one direction, coral reefs around the globe are facing an even greater threat: high tropical water temperatures speeding up bleaching cycles.

Coral bleaching, put simply, happens when environmental stress impacts on the “symbiotic” relationship between the rock-like living creatures that form the reefs and microscopic algae that give them their incredible colours.

When stressful factors, particularly the warming up of ocean waters because of climate change, take effect, the corals expel the algae, leaving them to become transparent skeletons. Without the algae, the coral then starves.

New research from an Australian-led team of experts published in the journal Science warns bleaching events experienced at the rate every 25-30 years in the 1980s have now shortened to six-yearly intervals.

The team said: “Tropical reef systems are transitioning to a new era in which the interval between recurrent bouts of coral bleaching is too short for a full recovery.”

The Great Barrier Reef was not the only casualty during the worst ever bleaching event in 2015-16 when record ocean temperatures impacted on 75 per cent of a 100 global reefs studied in a global survey.

Last July one of the planet’s leading marine experts warned that all 29 World Heritage List coral reefs could vanish by the end of the century. 

Besides the Great Barrier Reef, Dr Fanny Douvere, coordinator of the Marine Programme at UNESCO’s World Heritage Centre, explained how the iconic Galapagos Islands and Komodo National Park corals were at risk within the next five years.

Lead author of this week’s study, Professor Terry Hughes, director of the ARC Centre of Excellence for Coral Reef Studies in Australia, is calling for more action to limit greenhouse gas emissions under the global 2015 Paris climate agreement.

He says the main problem for protecting reefs was “weak commitments for reductions in emissions from individual countries like Australia and the United States”.