On the Great Barrier Reef up to 150,000 of the starfish can spread over just one square kilometre during an outbreak. It is not known exactly what causes a crown-of-thorns (COTS) outbreaks, however, scientists agree it could have something to do with increased levels of nutrients in the water due to agriculture runoff or warming oceans, leading to a plankton bloom which is a necessary food source for starfish larvae.
But the starfish has one feared predator, the Giant Trion Sea Snail.
Sea Snail Breeding
The Federal Government of Australia is funding a world-first research into breeding rare giant triton sea snails (Charonia tritonis), which eat the starfish. The sea snails, which can grow to half a meter, were almost hunted to extinction for their shells, and while they’ve been a protected species in Queensland since the 1960s, although they still remain rare.
The Government is spending $568,000 on the initial research and trial over the next two years, with more than 100,000 swimming snail larvae already hatched during the early stages of the project.
Federal Environment Minister Josh Frydenberg said if the research is successful, triton snails could be used to disperse the starfish — which appear to “flee” from the predator — and prevent them from breeding.
“This new project builds on the success of Australian Institute of Marine Science research that found crown-of-thorns starfish avoid areas where triton sea snails are present,” Mr Frydenberg said.
AIMS research manager Dr David Souter said the snails were so rare, almost nothing was known about them, including their reproductive biology or life cycle.
“We’re looking at how long they take to grow to maturity and the potential for a breeding program,” he said.
Dr Souter said any eventual release of more snails onto the Great Barrier Reef would be done under tightly controlled circumstances to avoid a cane-toad-type situation, in which the solution becomes worse than the original problem. [Courier Mail]