A destructive starfish that literally eats the Great Barrier Reef just got scarier, with scientists discovering it has climate change super powers.
Experiments have shown young crown-of-thorns can withstand tremendous heatwaves, well above levels that kill coral.
Juvenile starfish, which typically eat algae, can also survive and wait for at least six years for coral to regrow.
When it does, they advance into maturity and switch from being vegetarians to carnivores that prey on the recovering reef.
The findings are more bad news for the World Heritage-listed reef, which is already under pressure from crown-of-thorns outbreaks and marine heatwaves driven by climate change.
"We found juvenile crown-of-thorns starfish can tolerate almost three times the heat intensity that causes coral bleaching," Maria Byrne, a professor of marine biology at the University of Sydney said.
She describes a sort of self-perpetuating cycle where coral dies from heat stress and is then covered by algae before the dead coral breaks down into rubble.
The algae covered rubble provides the perfect refuge for young starfish to bide their time.
When coral starts to return, the starfish become adults with each one capable of eating 15 to 30 square metres of coral a day.
Study co-author and PhD student Matt Clements says the heat resistance observed in juveniles may be allowing them to build up in coral rubble over years, and contribute to adult outbreaks when conditions are right.
"Loss of natural predators due to overfishing and the build-up of nutrients in the water have been suspected to contribute to outbreaks of crown-of-thorns starfish," he said.
"Now we have evidence that bleaching induced coral mortality could aid the seafloor-dwelling juveniles, leading to subsequent large waves of adults in reefs which exacerbate the ravages of climate change."
The researchers say their findings have important implications for understanding the impacts of climate change on marine ecosystems.
The study has been published in the peer-reviewed scientific journal Global Change Biology.
