Underwater invasion

Pest control hopes for a seaweed infestation in NZ's northern waters rest on AI surveillance.

- VERONIKA MEDUNA

Within the few years since its 2021 detection in Blind Bay on Aotea Great Barrier island, the exotic seaweed caulerpa has spread to cover 1500ha of seabed in the upper North Island. The most dramatic evidence of its invasive creep came after Cyclone Tam washed up tonnes of the tangled marine pest on a Bay of Islands beach in April.

Eradication is not impossible but it's impractical, not least because the cost would be mind-boggling, says Niwa marine ecologist Dr Leigh Tait, whose work focuses on biosecurity and ocean ecosystem monitoring. But there are methods of control, some of which show promise and deliver temporary relief in areas of heavy infestation. And remotely operated vehicles equipped with AI detection tools are set to help keep the weed out of places it hasn't yet reached.

Caulerpa moves fast and seems to thrive in most marine habitats. Soon after being identified in Blind Bay, it was also found in Aotea's harbours at Tryphena and Whangaparapara.