New research on Clavelina oblonga

New research undertaken in the Northern Hemisphere is showing that Clavelina oblonga has the potential there to have more negative impacts on the marine ecosystems and industry, particularly aquaculture, than initially thought.

 This species of sea squirt or ascidian was first found in 2019 by Auckland Council’s Sam Happy during routine marine pest surveillance at Smokehouse Bay on Aotea/Great Barrier Island, but its reach is slowly spreading into the wider Port Fitzroy area and heading out the man-of-war passage around Motu Kaikoura.

 This genus is well known to dislodge easily. Like its close relative Clavelina lepadiformis (the lightbulb-ascidian), they will grow on a wide range of substrates, but fall off with the slightest water movement, including when a diver waves their hand at it or when a boat is being hauled out of the water. 

 “That is probably the saving grace of why it's not spread far from where we originally detected it at Smokehouse Bay, near the tidal grid and mooring field,” says Senior Marine Biosecurity Advisor Sam Happy of Auckland Council. 

“This area is a boating mecca, it's really popular and sees high use especially over summer. We need people to be really careful to check and clean gear when they enter the water and before they move.” 

The paper, titled Biological, Biochemical and Elemental Traits of Clavelina oblonga, an Invasive Tunicate in the Adriatic Sea notes, “observations indicate that C. oblonga has adapted to the colder temperatures of the northern Adriatic Sea and may continue to spread, potentially disrupting shellfish farming, reducing plankton populations, and altering marine ecosystems”.

Whilst this research is not set in the New Zealand environment, the advice is the same as for any other biofouling species: regularly check and pay attention to hull grooming by maintaining antifoul and cleaning your boat regularly.