DNA test to ID any sea squirt
From the June 2010 edition of Agriculture Today.
Time-consuming overseas testing won’t be needed if there’s a “next time” an outbreak of invasive colonial sea squirt is suspected.
A recent emergency response on the NSW Far South Coast again highlighted the ability of Industry and Investment NSW staff to gear up quickly against potential biosecurity threats.
Various strains of sea squirt (better known to ocean lovers as cunjevoi) are extremely difficult to identify as they are very similar in appearance.
Beef molecular geneticist, Brendon O’Rourke, from the State Veterinary Diagnostic Laboratory at Elizabeth Macarthur Agricultural Institute, worked with staff in the Fisheries and Ecosystems Research Unit at Port Stephens and Batemans Bay to identify the strain.
A routine annual inspection in March by divers had revealed a suspect Didemnum vexillum infestation on the multi-purpose wharf in Twofold Bay.
While awaiting identification from the overseas results – ultimately negative – Mr O’Rourke turned his skills to developing a rapid genetic test, now up and running, with the help of his Port Stephens colleagues.
“The suspected exotic pest has not been previously detected in Australian waters, so Australia had no capacity to identify Didemnum vexillum,” Mr O’Rourke.
“The point of developing the DNA test is to give Australia the capability to quickly identify the organism and it will now be available in further sea squirt surveillance operations,” Mr O’Rourke said.
“The test we developed confirmed the overseas result that the sea squirt in Twofold Bay was not invasive and no eradication was necessary.”
Didemnum vexillum attaches to infrastructure such as wharves, pilings and boat ramps, as well as ropes and boats, and spreads easily.
It is a marine pest of national concern with potential to devastate marine fish habitats and smother local mussel and oyster stocks.
Water users around the State who find what they believe may be an aquatic species not native to the area are asked take a photo if possible and report its location promptly to a local Fisheries office or email aquatic.pests@industry.nsw.gov.au
