Divers home in on thorny threat

Published: 17/09/2014

Trained divers tasked with the job of culling the coral-eating crown-of-thorns starfish on the Great Barrier Reef have begun targeting a series of individual reefs thought to be spreading the current outbreak.

The divers are culling the coral predator on six reefs off Cairns and Port Douglas in addition to popular tourism sites, after new scientific modelling showed the reefs, which experience periodic local outbreaks, may be seeding downstream areas with the starfish larvae.

The University of Queensland study, led by Dr Karlo Hock, also predicts which ‘transport routes’ starfish larvae are likely to take from these ‘super spreader reefs’, based on the ocean’s currents.

The Great Barrier Reef Marine Park Authority’s manager of ecosystem resilience Roger Beeden says the findings are influencing the operation of the Australian Government’s control program.

“The research would suggest there are hotspots on the Reef where starfish outbreaks spark a chain reaction that spreads the infestation to vast areas,” he said.

“This is because individual reefs are interconnected, allowing an exchange of coral and fish larvae and other marine creatures.

“It’s helped in large part by some big currents — similar to how the beloved clownfish in ‘Finding Nemo’ was able to travel large distances by riding the Eastern Australian Current.

“These connections are critical to keeping the Reef resilient and driving recovery. However, unfortunately, these same connections can fuel crown-of-thorns starfish outbreaks.”

Crown-of-thorns starfish program coordinator Jessica Hoey said that of the northern reefs thought to be spreading the infestation, six are being targeted: Undine, Rudder, Chinaman, Batt, Arlington and Elford reefs.

“The current control program has largely focused its efforts on reefs popular with tourists around Cairns, Port Douglas and the Whitsundays, but with this new information we’ve also turned our attention to include these high-risk reefs,” she said.

“Because the research also shows there are certain routes that the larvae are likely to take, it means we’re in a far better position to know which reefs are prone to receiving and then spreading the starfish.

“This is valuable information we can apply to our surveillance and management measures which includes using Marine Park rangers as ‘spotters’ for the starfish and a dive team run by the marine tourism industry to manually administer a lethal injection which is harmless to other marine life.”

At one of the six reefs, Arlington, divers culled more than 27,000 starfish in a 10-day period in 2013.

The Australian Government’s crown-of-thorns starfish control program has so far protected coral on more than 80 reefs and culled 288,000 of these coral predators.

The venomous invertebrate has been one of the main drivers of coral cover decline on the Reef over the past 30 years.

The crown-of-thorns starfish management program is being delivered in partnership with the Association of Marine Park Tourism Operators, the Queensland Parks and Wildlife Service, and the Reef and Rainforest Research Centre.

The research on connectivity networks was conducted in collaboration with Professor Peter Mumby from the University of Queensland’s School of Biological Sciences, Dr Scott Condie from CSIRO and Dr Ken Anthony from the Australian Institute of Marine Science.

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