The Great Barrier Reef has faced massive environmental threats in recent years, including two bleaching events, several tropical cyclones, years of agricultural run-off and several horrific crown-of-thorns starfish outbreaks. While the locals sometimes feel helpless when it comes to battling climate change, reef warriors are prepared to get their fins wet to battle the crown-of-thorns starfish, also called the crown-of-thorns seastar (CoTS).
The CoTS is one of the biggest threats to the Great Barrier Reef. A venomous, multi-armed predator that eats and kills coral, this starfish has been responsible for 40 percent of reef coral loss between Cooktown and the Whitsundays over the past few decades.
Researchers think the CoTS first appeared on the reef thanks to the ballast water of passing cargo ships. With few predators in Australian waters, they have thrived. Approximately 11 other species are known to prey on the CoTS, including the Triton’s trumpet sea snail, although unfortunately none appear to prefer it as a food source.
What’s the problem?
Crown-of-thorns position themselves on healthy coral, extrude their stomach through their mouths, and then secrete digestive enzymes and absorb dissolved coral tissue. Each night, the nocturnal starfish can eat its own body area of living coral. On average, that adds up to 140 square feet (13 m2) of reef per starfish, per year.
What are the challenges?
CoTS spawn during the warmer months from October to February, and large females can produce up to 60 million eggs per year. Aside from the large spawning numbers, one of the biggest challenges facing the cull is first locating them. Sea stars are quite mobile and can move up to 130 feet (40 m) in just one day.
An army of Reef Warriors
Alongside the Reef’s official custodians, which include the Great Barrier Reef Marine Park Authority (GRMPA) and the Association of Marine Park Tourism Operators (AMPTO), countless Reef Warriors are working on conservation projects that include education programs, pollution control, coral nurseries, and turtle sanctuaries.
Col McKenzie is just one of these Reef Warriors. He’s been fighting for the reef for over 30 years and has built his own army of marine conservationists. Under his guidance, and armed with only wetsuits, scuba gear and syringes, an underwater army of newly-trained divers is taking on the CoTS, one shot at a time.
Col heads up AMPTO, the organization that manages the crown-of-thorns control program in Queensland. Year-round, the program sees teams of up to 12 men and women taking part in non-stop 10-day containment voyages off the coast of Cairns and Port Douglas in tropical north Queensland.
Taking out the crown-of-thorns
After 42 years of research, scientists have established that the fastest (and safest) way to kill this predator is with a single lethal injection of bile salts. One quick and simple injection euthanizes a starfish without harming the reef. This is a far cry from the previous method, in which divers had to inject the reef pests up to 30 times.
“It used to take around about six minutes to deal with a single crown-of-thorns starfish,” says Col. “These days we are able to deal with one every four or five seconds. We would be pretty happy in the past if we could take out 500 crown-of-thorns in a day using the old method. With the new method, the best we’ve done is 7,000.”
Since 2012, teams from AMPTO have destroyed more than 400,000 of the starfish. In a recent horrific outbreak on Swains Reef, far south of Cairns, a team of 25 divers killed as many as 47,000 CoTS in nine days.
Programs provide job training
The program is also providing valuable training and employment for young men and women in the local area.
“We’re actually running two programs here,” says Col. “One is the crown-of-thorns control program and the other is called skilling Queenslanders for work program.
“That second program takes unemployed youth and we teach them to be occupational divers using the crown-of-thorns as the catalyst. So, we’re getting an employment benefit as well as an ecological benefit. What we’re doing with our program is achieving good environmental outcomes for the reef and changing lives.”
It takes the young divers six months to gain their divemaster status. So far, 230 trainees have graduated from the CoTS program. They now have dive qualifications, with an 85 percent employment rate.
One of the first recruits, Mathew Trueman, joined the program in 2010. He’s now the dive supervisor onboard research vessel the MV Venus II.
“I was in the original unemployed youth program,” Matt says. “I worked hard as a CoTS diver and my efforts were soon rewarded with a promotion to team leader. Now nearly eight years later, I am the boss.”
“Anyone with divemaster certification can attend a 10-day training onboard one of our CoTS vessels. There are two spaces available on every voyage.”
Despite the many threats to the Great Barrier Reef, Col McKenzie firmly believes it’s not too late.
“Perhaps not all of it, but the vast majority of it will survive,” he says. “The more we can help to minimize stress factors, such as water quality and CoTS outbreaks, the greater chance coral has to adapt to its biggest threat: climate change.”
How to be a citizen reef warrior
You can contribute to several citizen-science projects by helping monitor the reef’s health. Sign up for ReefSearch and you’ll receive a field guide to show you how to contribute valuable data to scientists studying the reef’s health. You’ll learn how to spend 10 minutes of each dive, snorkel or reef walk looking for key species, checking coral condition, and making note of any trash you find.
Coral Watch, managed by the University of Queensland, focuses on bleaching events. Your Coral Watch kit comes with a color-coded slate that helps you identify and record coral colors. You can then upload them via an app to add to a global database.
The Great Barrier Reef Marine Park Authority (GRMPA) manages Eye on the Reef. Download the Eye on the Reef app or login online to report your sightings directly to them. A sighting can be anything you feel important enough to report. These include incidents like a bleaching event, crown-of-thorns starfish, stranded or sick wildlife and coral damage.
If you’re a certified divemaster from any agency, with a current commercial medical certificate, and you’d like to take part in the CoTS control program’s training course or are interested in full-time employment as a COTS diver, send your resume to the program’s operations manager, Steve Moon.
Deborah Dickson-Smith is one half of Diveplanit, a dive travel website she manages with her partner Simon Mallender, based in Australia.