Scientists find chinks in coral-eating starfish armour
Crown-of-thorns starfish suck the colour and life out of corals, a favourite food, but in a healthy ecosystem their numbers are held in check
The discovery that coral-eating starfish are late risers and feed mostly at night could help slow the decline of the Great Barrier Reef and other shallow-water corals already ravaged by global warming, scientists reported.
Crown-of-thorns starfish suck the colour and life out of corals, a favourite food, but in a healthy ecosystem their numbers are held in check. When marine heatwaves bleach large swathes of coral, however, bigger fish leave the area and the spiky multi-armed predators proliferate and zero in on what’s left.
Mass-bleaching, outbreaks of crown-of-thorns starfish, and a myriad of other disturbances and pressures are leading to widespread coral loss and degradation of reef ecosystems.
Efforts to manually remove the ravenous starfish have largely failed, in part because they are not always easy to find.
But a study has found a chink in their spiky armour which could help scientists buy time for the world’s embattled reefs. The starfish appear to sleep in, and will be harder to find on the reef before about midday, that means they would be most active and exposed after the Sun goes down.
In the study, researchers showed that the crown-of-thorns species — like sea urchins — forage for food and then find shelter before daybreak. If the feast is close to home, they don’t roam.
But if the pickings are slim, they will wander up to 20 metres and then find their way back, a pattern known as homing behaviour.
The UN’s climate science advisory panel, the IPCC, has found that 1.5 degrees Celsius of atmospheric warming above pre-industrial levels would doom 90 percent of the world’s shallow-water corals. A 2 degree Celsius rise would spell their near-complete demise. Loss of coral reefs around the world would double the damage from coastal flooding, and triple the destruction caused by storm surges.
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