Coral-eating crown-of-thorns starfish can be killed with household vinegar: scientists

James Cook University researchers have discovered that household vinegar has a 100% kill rate for starfish that prey on coral on the Great Barrier Reef

A plague of coral-eating starfish that have caused alarm over their seemingly unstoppable attack on the Great Barrier Reef can be killed off with a simple dose of household vinegar, scientists have discovered.

Crown-of-thorns starfish are considered to be one of the two leading causes, along with cyclones, of a dramatic loss in coral cover on the Great Barrier Reef over the past 30 years.

The starfish occur naturally upon the reef but can reach plague conditions when conditions are right, such as when phytoplankton, their food source, becomes more abundant from floods washing fertilisers and other pollution from land into the sea.

A recent outbreak of the starfish has caused large areas of the reef to be eaten through, forcing scientists to grapple with new ways to halt the epidemic.

Researchers at James Cook University have now discovered that a simple dose of vinegar has a 100% kill rate for the coral-hungry starfish.

Trials undertaken at the university found that all starfish given 20ml of vinegar died within 48 hours. The research will now move to sea-based trials.

Related: Robotic killer being trialled to rid Great Barrier Reef of crown-of-thorns starfish

Currently, divers have to inject 10 to 12ml of ox bile into each starfish in order to kill it. The ox bile is expensive, requires various permits and has to be mixed to the right concentration, unlike vinegar, which is readily available in the supermarket.

The breakthrough is not a vinegary silver bullet, however – there is still no other way of administering the vinegar other than injecting starfish one-by-one.

Lisa Bostrom-Einarsson, lead author of the JCU report, said further research had to be done to ensure the vinegar did not harm other sea life.

“There’s no reason to think it won’t work or it’ll be dangerous, but we have to be sure,” she said.

“It has been estimated there are between four and 12 million of the starfish on the Great Barrier Reef alone and each female produces about 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.”

Related: Great Barrier Reef pollution prevention too slow, says Queensland government

The federal government funds crown-of-thorns eradication programs, with 27 marine tourism operators and two community groups licensed to kill them.

However, the latest report card on the Great Barrier Reef’s health, released this week , shows that targets to reduce chemical runoff are not being met, making further outbreaks more likely.

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