PACIFIC – Small teams of volunteers around the Pacific Islands are fighting to save coral reefs from the dreaded crown-of-thorns starfish.

The coral-eating starfish are in plague proportions around the Pacific and are causing widespread damage to some of the most pristine ecosystems in the world.

Scientists have discovered that low doses of vinegar injected into the “arms” of the crown-of-thorns starfish can kill the individual animal.

On board the Taka, a dive vessel operating in the Solomon Islands, dive master Dave Moss, who is passionate about marine conservation, has the crown-of-thorns in his sights.

Moss worked with scientists at James Cook University and other researchers in Bali to do his bit to tackle the problem.

“What we are seeing is a lot of dead coral, a lot of white coral, which is not actually bleaching – bleaching is live coral, but predated coral is stripped of all tissue, back to the bare limestone skeleton,” he said. “It’s almost like a wall of them marching along the reef.”

A trial conducted by the Australian Institute of Marine Science in 2015 found that injecting the starfish with vinegar showed a 100 per cent mortality rate.

“We take down a pack of syringes full of vinegar, household vinegar, which is five per cent acetic acid and inject it into the polian vesicles across the starfish, which distributes the water through the hydro vascular system of the animal and kills it,” he said.

“Within about 24 to 48 hours the star should have died and it won’t have impacted the environment around it. Then fish can eat them.”

“So what we hope to do is remove as many of the crown-of-thorns as we can, but also by leaving them there, we are hoping other fish will see them as a food source, and we wont need to continue this action.”

Moss said they were seeing some positive results and he hoped over time the slow growing damaged corals would recover.

But he conceded, killing individual starfish was not going to save the coral reefs, especially as higher water temperatures associated with climate change.

A loss of crown-of-thorns predators due to overfishing, and poor water quality were resulting in increasing numbers of them.

Coral bleaching and crown-of-thorns starfish damage may look similar, but Moss said they were different.

“The crown-of-thorns is a natural predator of coral, and it also has natural predators, like Maori wrasse and the triton snail, but when these are overfished or scavenged the starfish numbers increase.

‘Historically there are a number of recorded crown-of-thorns starfish plagues and reefs have recovered – but the frequency is increasing and regeneration is slowing.”

Researcher Lisa Boström-Einarsson said vinegar had been tried unsuccessfully before, but the James Cook University scientists had refined the process which resulted in a 100 per cent kill rate.

“It has been estimated there are between four and 12 million of the starfish on the Great Barrier Reef alone and each female produce around 65 million eggs in a single breeding season.

“They managed to kill around 350,000 last year with two full-time boat crews. While it would take an insane effort to cull them all that way, we know that sustained efforts can save individual reefs,” Boström-Einarsson said.

She said other researchers were working on population-level controls of the animal, but killing the starfish one-by-one was the only method available at the moment. - ABC