New weapons, strategies in war against Crown of Thorns
New weapons, strategies in war against Crown of Thorns
Friday August 8 2014, 1:35pm
New efforts are underway to combat infestations of Crown of Thorns starfish on the Great Barrier Reef with the development of lethal bile injectors and integrated pest management plans.
Sudden population booms of the coral-eating Crown of Thorns have plagued the reef since the 1960s.
The starfish, which grow to the size of a dinner plate and are protected against predators by hundreds of toxic spines, swarm over reefs and extrude their stomachs onto the coral surface, digesting polyps and leaving only the white calcium carbonate skeleton behind.
Large outbreaks - believed to be fuelled by nutrient run-off from coastal farms - result in a nightmarish plague of millions of the creatures marching across the reef, consuming all the living coral in their path.
Crown of Thorns outbreaks occur from Lizard Island to reefs south of Townsville.
Recent sightings of the starfish at Low Isles have also caused concern in Port Douglas.
The impact of the starfish plagues is huge - a study by the Australian Institute of Marine Science (AIMS) estimates that the Great Barrier Reef has lost almost half of its living coral in the last 20 years, with Crown of Thorns outbreaks identified as one of the leading causes of coral death.
Organisations such as the Great Barrier Reef Marine Park Authority (GBRMPA), the Association of Marine Park Tourism Operators (AMPTO) and the Reef and Rainforest Research Centre (RRRC) are developing new strategies to control the starfish.
On the front line of the war against Crown of Thorns are trained divers like Doug Baird, environmental compliance manager for Quicksilver Port Douglas.
Doug has been diving to control Crown of Thorns outbreaks since the late 1990s, with his primary weapon against the starfish being an injector needle filled with poisonous sodium biosulfate.
This method, however, is laborious and time-consuming - divers must grab each spiky starfish, flip them over and inject them several times to ensure they are killed.
But after certification with GBMRPA, Doug is now equipped with a new ammunition in his battle against the starfish - a potent cocktail of thiosulfate-citrate-bile salts-sucrose (TCBS), produced using bile from the stomachs of sheep and oxen developed by James Cook University.
A single injection of TCBS, which entered use in 2013, causes the gruesome death of the starfish from toxic shock in 24 hours - the body of the creature disintegrates, sloughing off its skin to expose internal organs, which are fed upon by scavenging fish.
AMPTO and GBRMPA are training and equipping divers like Doug to better control Crown of Thorns outbreaks not just on popular dive reefs visited by tour boats like Quicksilver but also more remote ‘producer’ or ‘seed’ reefs, where large numbers of the starfish breed and develop to maturity.
AMPTO executive officer Col McKenzie told Newsport that after the introduction of TCBS injection, kill rates of the starfish had increased from 150,000 per year to up to 300,000 per year.
Doug Baird picked up his new TCBS injector from GBRMPA on Wednesday, and is looking forward to being able to use it on his next dive.
“I’m looking forward to giving it a test run on Monday, that’s for sure,” he said.
“I’m definitely expecting an increase in what we call catch per unit, which is how many starfish someone can cull in every dive.”
Even a hardened starfish hunter like Doug is feeling the stress of battling plagues of the creatures for so long.
“It does get a little creepy dealing with these things constantly, actually - they’ve even started showing up in my dreams,” he said.
Controlling Crown of Thorns isn’t just about culls, however.
The Reef and Rainforest Research Centre in Cairns is developing an integrated pest management scheme (IMP) for the starfish, which was recently approved by Federal environment minister Greg Hunt.
The IPM focuses on approaching the Crown of Thorns problem in the same way as land pests like mice or locusts, including identifying stages of the starfish’s life cycle that were most vulnerable.
RRRC managing director Sheriden Morris said all stakeholders in the Great Barrier Reef needed to cooperate for the IPM to work.
Ms Morris said like locusts, Crown of Thorns plagues were basically unstoppable once specimens grew to adult size so new ways have to be found to stop outbreaks before they happen.
To that end the RRRC plans a large-scale surveillance program as part of the IPM, which would need feedback from users of the reef.
“Crown of Thorns is not a little problem - it’s a very, very big problem for the reef,” Ms Morris said.
“If we’re going to stop them we need cooperation and information from everyone that uses the reef - divers, fishers, tour operators, anyone that works underwater on the reef.
“The reef is already at a critical stage of vulnerability and it cannot take another serious Crown of Thorns plague.”
