Hundreds of trade vessels, cruise ships and recreational boats pass through Great Barrier Reef waters to get to the Port of Cairns each year. They can bring unwelcome passengers – from non-native mussels and oysters to worms, sea squirts and algae – which have the potential to disrupt local ecosystems and fisheries by spreading through ballast water, marine equipment and the biofouling on hulls.

Adam Fletcher, Environment Manager at Ports North, says eDNA, or Environmental DNA, is a new technology that is revolutionising biosecurity monitoring, particularly as new applications emerge.

“Environmental DNA detects traces of DNA that organisms naturally shed in the water,’’ he says.

“This helps us to identify species with much greater speed and accuracy. It means we can detect the presence of invasive species before they become a major problem and put response measures in places much more rapidly.”

The award-winning Q-SEAS Marine Pest Sampling program has been running since 2019 and is a joint effort by Ports North, the Queensland Ports Association, and Biosecurity Queensland.

As part of the program, Ports North collects bio-fouling – the layer of marine organisms, algae, slime and other debris that builds up on the underwater surfaces of a vessel – by placing plastic plates in the water for eight weeks twice a year. Plankton is also collected, along with water samples. The genetic materials of marine organisms are then sent to Curtin University, where they are analysed and compared to a library of over 100 marine pest DNA profiles.

Adam says no high priority or new invasive species have been detected in Cairns since the program began. However already established pest species have been detected.

“In the last two decades there have been a number of incursions of Asian green mussel and Asian bag mussel from physical samples but luckily they haven’t established themselves here. However, the black scar oyster, which was detected around five years ago, is now prevalent in Cairns and Port Douglas, competing with native oysters for habitat and resources.”

Australia has some of the strictest biosecurity laws in the world. Ships must regularly maintain their hulls with anti-fouling coatings to prevent marine organisms from attaching, and vessels arriving from high-risk international locations are inspected.

“This eDNA program provides another layer of defence in protecting our marine environment,” Adam says.

Help stop the spread of marine pests in Wet Tropics waterways 

• Keep your boat and fishing gear clean and dry and undertake regular maintenance to prevent biofouling.
• Comply with Australian Ballast Water Management requirements on your vessel.
• Put unwanted fishing gear in the bin, not the water.
• Dispose of aquarium contents responsibly i.e. not in our waterways.
• Only import permitted species for your aquarium.
• Learn more about risks, species and how you can help in the great resources provided by marine biosecurity agencies.