Volunteers use buckets and barrows to remove caulerpa washed up at Northland's Ōmakiwi Cove. Photo: Supplied / Ngāti Kuta, Patukeha
Hapū volunteers are spending a second day removing hundreds of tonnes of a highly invasive seaweed pest washing up on a Bay of Islands beach as a result of Cyclone Tam.
Local kaitiaki [guardian] Arana Rewha estimated locals removed 300 tonnes of exotic caulerpa on Friday, first with buckets and barrows, and later with a digger.
Rewha said the cyclone's huge swells and powerful easterly winds left Ōmakiwi Cove, at Rāwhiti, east of Russell, carpeted in a thick layer of the fast-growing pest.
Ngāti Kuta kaitiaki Rana Rewha. Photo: RNZ / Peter de Graaf
The first reaction of local hapū, Ngāti Kuta and Patukeha, was one of dismay at the sheer scale of the problem, Rewha said.
However, a call for help on social media prompted about 20 volunteers to descend on the beach to help with the cleanup.
Rewha said they wanted to prevent the weed, now that it had broken free from the seabed, being washed out on the next tide and spreading to other parts of the Bay of Islands.
"We're just trying to minimise it getting back in the water and regrowing, or even moving around the point and getting into open channels," he said.
"That's our main goal, get it out of the water, get it dry and dying, then come back and clean it up later on."
Photo: RNZ / Peter de Graaf
For now the seaweed was being piled up on shore, above the high-tide mark.
He estimated volunteers had removed 10-20 tonnes of caulerpa by hand on Friday.
Each bucket-load weighed about 10kg, so that meant thousands of buckets filled with washed-up seaweed.
Later in the day a digger sped up the work significantly, allowing the entire beach to be cleared of an estimated 300 tonnes of seaweed.
A volunteer with large clumps of the invasive seaweed caulerpa at Northland's Ōmakiwi Cove. Photo: Supplied / Ngāti Kuta, Patukeha
However, Rewha said more had washed up overnight, and they had yet to start on other beaches in the area.
Efforts started again at 2pm on Saturday as the tide went out.
By 3pm about 25 volunteers were at work but he had been told another 50 were on their way.
That included a contingent from Ngatiwai, another iwi further down the coast in the Whangārei District, who had offered their help on Saturday and Sunday.
Representatives of the Conquer Caulerpa Trust were also assisting.
Rewha said it was continuing to rain intermittently at Ōmakiwi but the physical work was keeping the volunteers warm.
The mood had lifted since the shock of Friday's discovery, he said.
"Yesterday everybody was a bit down and out, even myself, I had a bit of a moment. But now everybody's just trying do as much as they can, and get it off the beach."
Rewha said locals' concerns about caulerpa were based on its potential threat to biodiversity, especially its ability to rapidly smother shellfish beds.
"It's a food source that's going to be taken away from hapū, iwi and community. That's why we're so passionate about it and trying to do the best we can."
Efforts would continue until nightfall.
Kaitiaki Arana Rewha removes caulerpa by hand at Ōmakiwi Cove. Photo: Supplied / Ngāti Kuta, Patukeha
There have also been reports of caulerpa washing up at Tapeka Point and Long Beach in Russell.
Ōmakiwi Cove is ground-zero for the caulerpa invasion in Northland, and is also the site of a multi-million-dollar suction dredging trial aiming to come up with a method for removing the weed mechanically and on a large scale.
It was first identified at Ōmakiwi by Arana Rewha in May 2023.
It was first discovered in New Zealand at Aotea Great Barrier Island in mid-2021. Huge quantities washed up on the island's Okupu/Blind Bay after Cyclone Gabrielle.
Sign up for Ngā Pitopito Kōrero, a daily newsletter curated by our editors and delivered straight to your inbox every weekday.
