Science Centres: Aquatic Biodiversity and Biosecurity

Diver examing pile during port survey.

Over the winter, NIWA conducted surveys for the invasive sea squirt Styela clava (clubbed tunicate) at five new sites for Biosecurity New Zealand.

Styela was not found at any of these sites, which included Timaru Port, Auckland’s Onehunga Port, and three marinas in greater Wellington.

In addition, we re-surveyed Opua Marina in Northland, where Styela was found on a boat in May, and Nelson Port, following the discovery of Styela on a fishing boat in July. No Styela was found at Opua. We found and removed two Styela specimens from a second vessel at Nelson Port, which is thought to be the source of the original infestation.

Because ports and marinas are difficult places to search, our field teams conducted experiments to test the sensitivity of their search methods. Preliminary results show that the probability of detecting Styela varies considerably with water clarity, and whether searches are made from above water or by diver.