Divers kill coral-eating crown-of-thorns starfish with vinegar

Crown of thorns starfish COTS

Vinegar, a common household ingredient, could curtail crown-of-thorns starfish that has been nibbling away at the Great Barrier Reef. Injecting vinegar into the coral-eating pests kills them just as effectively as the current expensive and scarce drug.

Researchers from James Cook University have reached a breakthrough in solving this problem by injecting vinegar to two separate groups of CoTS from Kimbe Bay, Papua New Guinea and Lizard Island in Great Barrier Reef, Australia.

JCU researcher Lisa Boström-Einarsson said the findings were exciting. She notes, "The ideal would be to stop the cots (crown-of-thorns starfish) outbreaks from occurring altogether, but we still know relatively little about what causes them".

"This system has been trained to recognise crown-of-thorns starfish from among a vast range of corals using thousands of still images of the reef and videos taken by COTS-eradicating divers", said Matthew Dunbabin to BBC.

The researchers, during their approach, used 20ml of vinegar, and had a 100% strike rate, with all starfish in the trial meeting their demise within 48 hours of being injected. Further, if the bile isn't mixed to the right concentration, the starfish won't die. "Vinegar can be bought at any supermarket and is roughly half the price".

"There's no reason to think it won't work or it'll be unsafe, but we have to be sure", Lisa said.

Diver injects crown-of-thorns starfish with vinegar in cull
Diver injects crown-of-thorns starfish with vinegar in cull

Researchers note that killing the starfish individually can't save the entire reef by itself but it's just one step toward reducing CoTS outbreaks along the reef. Sea trials of this new vinegar method are expected to begin at the end of the year.

About 4 to 12 million crown-of-thorn starfishes are reportedly lurking in the Great Barrier Reef.

The reef report card, released by the government in the past week, shows that the Great Barrier Reef is still in bad shape, and that the goals to reduce chemical runoff from agriculture are not being met and is worsening the situation.

She said the findings could have big implications for developing countries without the means to acquire and use the current drug. Scientists at the Australian Institute of Marine Science warned in 2011 that the crown-of-thorns starfish was responsible for about 40 per cent of coral loss since the 1980s.


Conservation teams have killed around 350,000 starfish in 2014, and Bostrom-Einarsson said that as insane efforts are needed to eliminate all the CoTS, sustained efforts can still "save individual reefs".