06-05-2025
Reef-saving critter sparks hope for Great Barrier Reef
Tiny crabs are turning the tide on one of the Reef's deadliest threats — devouring baby crown-of-thorns starfish at a rate that has stunned scientists.
The crown-of-thorns starfish (COTS), infamous for its appetite for live coral, has long been blamed as a key culprit in the decline of Australia's iconic Great Barrier Reef, Queensland.
They are a 'major contributor' to coral loss as they extend and wrap their stomachs around the coral to digest their tissues.
Currently, management of COTS outbreaks relies on teams of divers to hand-pick starfish off the reef, which is time consuming and labour intensive.
But a surprising new ally for our reefs has emerged from the shadows of the seafloor: Tiny decapod crabs.
Researchers from the University of Queensland (UQ) and Australian Institute of Marine Science (AIMS) made the discovery through a controlled lab study.
'Our research detected over 30 new species that consume COTS during their vulnerable juvenile life stage,' said Dr Kennedy Wolfe, the study's lead author from the UQ.
'The decorator crab was a particularly voracious feeder, demonstrating the highest known rate of predation on COTS.'
These findings are consistent in the wild with detected starfish DNA inside the stomach of seven species of crabs collected from reefs.
Wolfe said that the results were promising and 'crucial to our ability to manage COTS outbreaks and their impacts to coral reefs.
'The smaller critters often do a lot more than we give them credit for, just like the bees and the earthworms on land.'
It's a numbers game
Researchers believe these tiny critters consume more than five baby starfish per day, which is a significantly higher rate than predators like the starry pufferfish and giant triton snails that only eat one adult starfish every few days or week.
'By better understanding these ecological connections, scientists are opening new possibilities for more natural, scalable approaches to reef conservation,' The Great Barrier Reef Foundation said.
'What we now need to determine is whether these crabs are depleted on some reefs, and why,' Wolfe added.
'If they are impacted and depleted, the causes would need to be managed to ensure these crabs have the best fighting chance to perform their role in consuming COTS.'
He said the crabs could potentially be used as a biocontrol option on reefs heavily affected by COTS, but emphasised that introducing populations would need careful research to prevent unintended ecological impacts.
