Game of Thorns could wreak reef havoc


Australian Broadcasting Corporation

Broadcast: 06/11/2013

Reporter: Peter McCutcheon

Scientists fear the Great Barrier Reef is about to be hit by the most damaging outbreak of Crown of Thorns starfish on record.


LEIGH SALES, PRESENTER: It's decades since Australians first learned that a pestilent starfish was attacking the Great Barrier Reef.

And even though since then experts have warned of many, many other threats to the Reef ranging from dredging to climate change, it seems the dreaded crown-of-thorns starfish is still the thing most likely to devastate the Heritage-listed area.

Here's Peter McCutcheon.

MORGAN PRATCHETT, CENTRE FOR CORAL REEF STUDIES: Crown-of-thorns starfish are very unusual. I wouldn't say I love them. I take great pleasure in killing them. But at the same time, you can't help but be in awe of the fact that they've so well-adapted to coral reef ecosystem.

PETER MCCUTCHEON, REPORTER: Professor Morgan Pratchett is trying to solve one of the biggest mysteries of the Great Barrier Reef. Why does the coral-eating crown-of-thorns starfish routinely invade in plague proportions? It's a question that's being asked not only out of scientific curiosity, but also because Australia's most famous environmental wonder is in the midst of yet another starfish attack.

MORGAN PRATCHETT: I wouldn't say it's peaked. We're certainly getting numbers far above what have been recorded before within the region from Cooktown to Cairns, but I think in the coming years that they're going to spread southwards.

NICK HEATH, WORLD WILDLIFE FUND: It's bad and it's going to get a lot worse. We're really worried because the coral cover on the reef is as low as it's been on any initiation of an outbreak for decades.

REPORTER (archive footage, ABC News, 1969): This ugly-looking creature has a great liking for live coral and has been eating away at the reef at a fast rate.

PETER MCCUTCHEON: The large-scale destruction caused by crown-of-thorns was first described in the 1960s and since then we've had three more outbreaks. And over that time, scientists have gained a much greater understanding of this bizarre creature.

It appears all the outbreaks begin in the same place, near Lizard Island off the coast of Cooktown, possibly because its sheltered position allows starfish numbers to reach a critical mass.

PETER DOHERTY, AUST. INSTITUTE FOR MARINE STUDIES: The crown-of-thorns is a native species. Look, it is virtually a pile of skin and spines overlying gonads that are very well-equipped to find and feed on coral. And so it is a species that sooner or later is prone to outbreak in very large numbers.

PETER MCCUTCHEON: Although this may be a natural phenomenon, coral scientist Professor Peter Doherty says there's little doubt the severity and arguably the frequency of these outbreaks has been caused by human activity. The most widely accepted theory is that the plagues are being fuelled by run-off from fertilisers.

PETER DOHERTY: Flood plumes during the cyclone season come laden with additional nutrients and sediments. They promote intense plankton blooms that increase the size of the plant cells and provide perfect feeding conditions for the starfish and the combination of that is suddenly an explosive increase in the numbers of starfish.

PETER MCCUTCHEON: Professor Pratchett believes the causes may also involve climate change and overfishing and other factors we've yet to discover. But coral scientists agree on one vital fact. This current outbreak is occurring at a time the reef is already in a poor condition.

MORGAN PRATCHETT: This is a very bad time to have a major outbreak of crown-of-thorns starfish because we've had a whole series of very severe cyclones which have already depressed coral cover and these crown-of-thorns outbreaks on top of that will really destroy what coral cover is left.

PETER MCCUTCHEON: A recent Federal Government report says crown-of-thorns continues to be one of the biggest threats to the Reef. Over 40 per cent of the coral loss over the past three decades is due to the starfish.

These are the latest pictures of the current outbreak. At least a million of these starfish cover reefs stretching hundreds of kilometres and they're slowly moving south with the ocean current.

COL MCKENZIE, MARINE PARK TOURISM OPERATORS: At the moment the crown-of-thorns are still ramping up in numbers. The - I would expect it's another 12 months before we see a full-on outbreak off Cairns.

PETER MCCUTCHEON: Col McKenzie represents Reef Tour operators and also heads a Queensland and Federal Government-funded crown-of-thorns eradication program. He's had success keeping the starfish away from reefs visited by tourists and this year the eradication team was given a new weapon: a single-shot poison that provides a quantum leap in killing efficiency.

COL MCKENZIE: It's probably the most exciting innovation in crown-of-thorns control anywhere in the world. The reality is that before the single shot injection, it was taking us on average six minutes per crown-of-thorns 'cause we had to inject the bell of the crown-of-thorns five times and every single arm. Now we just need one injection in the arm and so we're doing that in 10, 20 seconds.

PETER MCCUTCHEON: But although eradication programs are important to the $5 billion tourism industry, they're fundamentally cosmetic.

NICK HEATH: The one shot will not prevent or stop an active outbreak of crown-of-thorns starfish. It's just too big. It is a tsunami. And no amount of human endeavour could prevent a crown-of-thorns outbreak.

PETER MCCUTCHEON: The long-term solution is improving water quality. And over the past decade, fertiliser run-off has actually decreased, but the results won't be immediately obvious. The critical question is whether the Reef has been given enough time to recover.

LEIGH SALES: Peter McCutcheon reporting.