Fears of devastating outbreak after diver's rare find off Aussie tourist island
Marine scientist Paul Groves said it was 'very unusual' to see a 'venomous' crown-of-thorns starfish so close to shore.
A life-long diver’s “venomous” discovery in waters off a popular Aussie tourist island has highlighted once again the dire threat our coral reefs are facing.
Marine scientist Paul Groves has spent as much time as he can swimming in the picturesque bays of Queensland’s Magnetic Island since moving there in 2006. Despite the numerous years familiarising himself with local marine life and coral beds, when he and his friend Colleen Mandris entered the water last week in Nelly Bay they were “very surprised” by what they saw.
“This is the first time in 18 years that I’ve seen one,” Mr Groves told Yahoo News Australia on Thursday, adding that he had spoken to other local divers who were also flabbergasted by the discovery which was “about the size of a dinner plate”.
What the marine scientist and Colleen — who snapped a photo of it — had found was a crown-of-thorns starfish, a native predator that has up to 21 arms and hundreds of toxin-tipped thorns. It is one of the four main stresses on Australia’s coral reefs for its ability to decimate coral tissue faster than it can grow when populations reach outbreak status, measuring approximately 15 starfish per hectare.
Crown-of-thorns starfish sighting shocks locals
Since crown-of-thorns starfish tend to live on the “mid-to-outer shelf reefs”, Mr Groves told Yahoo it was “very unusual for them to be closer to shore”. Other local enthusiasts agreed, describing the discovery as “really, really cool” on a Facebook page dedicated to the island’s marine life.
“This is the first time I’ve ever heard of [them] around Maggie,” one person commented, while another said a friend who has been monitoring the island’s coral reefs for over 50 years “said he has never seen them before either”.
“I’m actually shocked! Have to keep our eyes a little more open for these little critters now,” someone else wrote. “Probably means the coral cover is getting gooooood,” a member theorised as another warned others to keep an eye on the starfish because “they move pretty fast”.
Coral-eating butterfly fish also seen for first time
Mr Groves said locals will be monitoring to see “if there are any more” in the area and claimed a “range of factors” could have contributed to the starfish ending up so close to shore.
“This last summer was a very mild summer — no cyclones and very mild coral bleaching — so the coral cover around the island has continued to expand,” he told Yahoo, adding that it could attract more to migrate.
The marine scientist said he had also recently seen coral-eating butterfly fish around Magnetic’s reefs for the first time. “There’s a few new butterfly fish species that would normally stay further off shore that have started to appear around the island,” he said. Mr Groves reported the crown-of-thorns sighting to authorities using the Eye on the Reef app, which is recommended.
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'Could be a sign of another outbreak'
In 2012, the Crown-of-thorns Starfish Control Program was established to try and control outbreaks, with skilled divers able to kill more than 100 an hour by manually injecting them with salt or vinegar, Evan Quartermain, Head of Programs at Humane Society International, told Yahoo.
However, this approach has its limitations, he added, explaining that warming sea temperatures due to climate change can enhance the starfish’s lava. “These mature crown-of-thorns can release 200 million eggs a year and be sexually mature within two years,” he said. “When the conditions are favouring them they can expand quite rapidly.”
In this instance, “if divers are seeing this and the conditions that are happening encourage this expansion, it makes a lot of sense and could be a sign of another outbreak in that area”, Mr Quartermain warned.
There have been four major crown-of-thorns outbreaks since the 1960s in the Great Barrier Reef, with the last beginning in 2009, AIMS Principal Research Scientist Dr Sven Uthicke told Yahoo. They can last 10 to 12 years.
“Outbreaking populations are still common at mid-shelf reefs south of Townsville,” he said. “There is an ongoing culling program, and AIMS is involved in monitoring and research into causes of these outbreaks.”
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