Ngāti Kuta volunteers cleared up hundreds of tonnes of the invasive seaweed caulerpa, after the ex-Tropical Cyclone Tam weather system roared through Northland. Photo: Supplied Ngāti Kuta, Patuketa
A hapū tackling the invasive seaweed caulerpa in the Bay of Islands warns it will spread to the rest of the country, devastating coastal environments and economies, unless more is invested in stopping it short where it is now.
When hundreds of tonnes of caulerpa washed ashore after the storms caused by ex-Tropical Cyclone Tam it was a shock to many, except Arana Rewha and Viki Heta.
Rewha is the chair of Ngāti Kuta hapū - and an award winning kaitiaki. He's also the first person to discover caulerpa up there after it was first found at Great Barrier in 2021.
After caulerpa broke free from the seabed in the storm two weeks ago, Rewha and fellow kaitiaki, Heta, quickly sprang into action, organising volunteers to remove it from Ōmakiwi Cove.
The 'sea pest' had plagued Ōmakiwi Cove since May 2023, they said, and was already having detrimental impacts on biodiversity, especially because of its ability to rapidly smother shellfish beds.
"It suffocates everything. It's just devastating it's an environmental disaster," Heta said.
If caulerpa continued to spread to nearby bays, people in coastal areas who depend on seafood would suffer, Rewha said.
"Right now in the Bay of Islands, you can't even anchor your boat, because of the risk of caulerpa spreading.
"If we were to lose our coastline to caulerpa, it will greatly affect our economy and everyday living."
More than $20m had been allocated towards caulerpa control, the Ministry for Primary Industries said, the biggest response to a marine species to date.
But Rewha and Heta said that was not enough, and there needed to be more investment into action, instead of just research.
Rewha speculated it could end up being a billion-dollar clean-up.
"It's a beast. It grows so fast and it's going to be so expensive to get rid of. But it's a threat to the whole country."
They warned that the longer the government held off on eliminating caulerpa, the more costly it would get.
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