Immediate action is being taken by Ngāti Manuhiri Settlement Trust to stop one of the most invasive seaweeds spreading through Kawau Bay and smothering our native marine ecosystem.

Caulerpa brachypus is a seaweed that forms dense matts smothering the seafloor affecting shellfish beds, native seagrasses and minimising the diversity of precious marine fauna in the sea. A large infestation was first discovered at Blind Bay Aotea Great Barrier in 2021 and proved extremely difficult to eradicate.

Patches of Caulerpa of about 20 cm to 30 cm have been spotted in the North Channel, northwest of Kawau Island (Auckland region).

Ngāti Manuhiri Settlement Trust Chief Executive, Nicola MacDonald, says the threat of Caulerpa is incredibly serious.

“As kaitiaki of our whenua and moana, it is our duty to protect and preserve our marine ecosystem. We cannot afford to mess around” she says.

“Caulerpa is easy to spread and very hard to remove. Just a small piece of seaweed caught up in lobster traps, anchors, or diving equipment can be transferred to other areas and risk our ecosystem.”

Caulerpa is a persistent, rapidly growing plant that can survive out of water in moist conditions for up to 10 days. Everyone will need to do their part to ensure it doesn’t take hold MacDonald says.

“People must be careful about their equipment, keep it clean and not do anything that poses further risk to our waters.”

Ngāti Manuhiri Settlement Trust and the Ministry for Primary Industries (MPI), with NIWA, are working together to contain and remove the patches of Caulerpa.

The infestation will be surveyed, and a range of options considered for removal such as hand removal or chlorine treatments; Ngāti Manuhiri kaitiaki will be involved in the process to ensure māramatanga Māori is utilised and protected.

If necessary, a rāhui will be considered to allow the waters to restore what has been lost.

“A rāhui is not laid down to take anything away from people,” says MacDonald. “It is there to allow our delicate ecosystem to heal and ensure it will be there for all of us to use in the future.”

“It is important that mātauranga māori is respected, and we’ve made it clear to the officials that this approach must be prioritised as we work to clear Caulerpa from our waters.”

Eradication is a future goal but the immediate focus is on removal and containment. Examination of current resources, expertise, and funding available will be undertaken to ensure this can be done. MacDonald says that long term, consideration must also be given to the Crown’s responsibility for biosecurity and its investment in this kaupapa.

Ngāti Manuhiri Settlement Trust is calling upon all community members, stakeholders, and fellow iwi to join the cause. The public is urged to share information, report sightings, and actively participate in eradication efforts to protect the marine environment and pass on a thriving marine ecosystem to future generations.

Sightings can be reported through 0800 80 99 66 or by completing the online reporting form at report.mpi.govt.nz.

© Scoop Media