Crown-of-thorns creep into Reef
Parts of the Great Barrier Reef are in the grips of an outbreak of crown-of-thorns starfish.
The outbreak was discovered on the Swain Reefs off Yeppoon last year, but the remoteness and hostility of the area has made efforts to control the spread of the coral-killing marine animal difficult.
The Great Barrier Reef Marine Park Authority (GBRMPA) sasy it is working on strategies to respond.
Hugh Sweatman from the Australian Institute of Marine Sciences says “very, very high densities [are] being seen, as high as we've seen in the past”.
“As high as you'd expect to see and there'll certainly be a lot of coral lost as a result.”
Dr Sweatman said the starfish consume coral by engulfing them.
“The crown-of-thorns starfish has an extrudable stomach so it lies on top of the coral and it wraps its stomach around the coral,” he said.
“It doesn't actually break bits off the coral, it just digests the tissue off the of the skeleton … it's very effective at that."
The starfish is native to the reef, but put the system at risk when their numbers increase.
“Each starfish eats about its body diameter a night and so over time that mounts up very significantly,” Dr Sweatman said.
The cause of the outbreak has scientists stumped.
Typically, outbreaks of crown-of-thorns are linked to spikes in ocean nutrients, and so usually occur further north and closer to the coast.
The Swain Reefs are well offshore, so these factors are less likely to have caused the outbreak.