Great Barrier Reef case study
The serene beauty of the waters in the Great Barrier Reef between Lizard Island and Cairns belies the battle beneath the surface between teams of dedicated divers and the venomous, coral-destroying crown-of-thorns starfish.
Of the major threats to the reef, this is one we can do something about on the ground,’ said Steve Moon, Project Manager for the Association of Marine Park Tourism Operators, a key partner in the Australian Government’s crown-of-thorns starfish control programme.
Crown of Thorns Starfish near Lady Musgrave Island on the Great Barrier Reef (Photo: Reef HQ Aquarium)
All year round, regardless of the weather, we have two teams of 10 to 12 divers, rotating 10 days on and four days off, out in the water culling and removing the crown-of-thorns starfish.
'At times it feels like we are at war, but we are definitely winning; we are seeing coral regenerating, we can see the difference.’
Native to the Indo-Pacific region, the crown-of-thorns starfish plays a vital ecological role in maintaining the diversity and delicate balance of the reef, as it feeds on the fastest growing corals, allowing slower growing coral species to form colonies. But when the poisonous starfish’s population booms to plague proportions, it is a significant danger to coral.
The first documented crown-of-thorns outbreak on the reef was recorded in 1962, with major outbreaks in 1978 to 1991, 1993 to 2005 and the present outbreak, which began in 2010.
According to research by the Australian Institute of Marine Science, coral cover on surveyed reefs has declined by about 50 per cent over the past 30 years. Crown-of-thorns starfish were responsible for almost half of this decline. The research estimates that if crown-of-thorns starfish predation had not occurred over the past three decades, there would have been a net increase in average coral cover.
When events like floods release large amounts of nutrients from land into the reef, water quality declines dramatically and if this occurs during the starfish’s summer spawning season, conditions are right for the starfish to develop, grow and survive at a much higher rate.
To build the resilience of the reef against this and any future outbreaks, the Australian Government, the Great Barrier Reef Marine Park Authority, the Reef and Rainforest Research Centre, and the Association of Marine Park Tourism Operators came together under the Australian Government’s crown-of-thorns starfish control programme to protect corals on high value reefs. Declining water quality is also being addressed through projects such as Game Changer case study.
Since its inception in 2011, more than 80 reefs have been patrolled and over 300 000 of the deadly coral predators have been culled.
The Australian Government has provided more than $7 million for two, 20-metre control vessels, research and development and the training and operation of diving teams.
`Proper training and management of diver fatigue is vital, it’s dangerous work,’ Steve said.
`We have a protocol on the control vessels that once a diver has been spiked more than twice, they are unable to dive.’
A major breakthrough for the programme was the development by James Cook University of a single injection cull method. Now a small single injection that produces an allergic reaction in the starfish, causing it to break apart and die within 24 hours, is used to cull the creature.
Previously divers had to extract the starfish from its location and inject it more than 20 times to get the same effect.
`The starfish can’t cope with the toxin and now break up in the water, making it much faster and safer for the divers and the reef,’ Steve said.
It is estimated the new method has led to a two and a half fold increase in injection efficiency. The results have been outstanding; such as 27 000 starfish removed in just eight days at Arlington Reef and 9000 at Batt Reef, as well as 14 000 at Spitfire Reef near Cooktown.
This remarkable success of the crown-of-thorns starfish control programme is a key element of the overall strategic approach by the Australian Government to protect the World Heritage listed Great Barrier Reef.
For more information go to: www.gbrmpa.gov.au/about-the-reef/animals/crown-of-thorns-starfish