Death by vinegar: new weapon against coral-eating starfish

By Joanna Khan 28 April 2017
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Outbreaks of crown-of-thorns starfish can be reduced using household vinegar, as the new control technique becomes available across the Great Barrier Reef.

New research has found that the use of vinegar injections to kill the coral-eating crown-of-thorns starfish (COTS, Acanthaster planci) is an effective way of reducing the damaging impact the starfish have on coral reefs in the Indo-Pacific.

The method has now been approved across the whole Indo-Pacific region after field trials on the Great Barrier Reef showed that vinegar does not affect other reef animals.

“This will lead more people to have their own small-scale control efforts on the reef,” said Dr Lisa Boström-Einarsson, a marine biologist at James Cook University and lead researcher on the project. After a single vinegar injection a starfish will die within 48 hours, and be completely gone from the reef within 72 hours.

“There are a lot of fish and invertebrates that feast on them and the reef clean-up crew are very effective at their job,” Lisa added.

crown of thorns vinegar
Dr Mary Bonin, Great Barrier Reef Marine Park Authority, inspects a Crown of Thorns starfish (Acanthaster planci) displaying physiological signs of distress approximately 1 hour post-injection. Image credit: Lisa Boström-Einarsson

COTS are endemic to Indo-Pacific coral reefs and play an important ecological role in healthy systems, balancing coral communities by feeding on the fastest growing species, and cleaning up dying and diseased corals. However, when there are COTS population outbreaks the impact they have on the reef is devastating, and they have been significant contributors to coral loss on the Great Barrier Reef since the most recent outbreak began in 2010.

COTS outbreaks also impact reef tourism, and this new control method makes it easier for small and remote operators to make a difference on their local reefs. “Vinegar is so much easier to access for communities in the Indo-Pacific, where access to ox bile (the previously used control method) was not feasible, for them vinegar is not an alternative, it’s the only option,” said Lisa.

While the vinegar injection method cannot control COTS on its own, it is a new weapon in the arsenal against the coral-eating starfish. “It would take a massive effort to try and cull them all individually, but we know that sustained efforts can save individual reefs,” said Lisa.

Another team of scientists is working on other elements of the arsenal. “There are three ways you can approach a problem like COTS,” said Dr Cherie Motti, a chemist working on COTS control methods at the Australian Institute of Marine Science. “You can develop a hammer to cull the animal straight away, and then you can develop other tools to support the hammer – I call them baits and barriers,” she said.

Cherie’s research group are working on ways they can alter the behaviour of COTS by targeting certain genes with chemical stimulation.  “It’s not the aim of our research to find a way to eradicate them, it’s more a way to control them and to get that balance back into the system,” said Cherie.