25 Jan 2024

Restoring Wellington’s seaweed forests

From Our Changing World, 5:00 am on 25 January 2024

A large tank of clear water filled with rocks covered with brown fuzz.

Giant kelp attached to rocks in the aquaculture facility at NIWA. Photo: Claire Concannon / RNZ

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The aquarium room at NIWA is awash with sound. A pump system hums, clicks and splashes as it circulates water through large tanks like the Wellington bucket fountain.

Inside, tiny seaweed fronds tied onto rocks dance in the currents.

Growing kelp

These fronds might be small – a few centimetres at most – but they can grow into lush forests. Giant kelp (Macrocystis pyrifera) starts out in a lab as microscopic spores, before it is coaxed through each phase of its life cycle by staff from the Love Rimurimu project and phycologist Dr Roberta D’Archino.

After growing a few more centimetres, the kelp will be returned to the wild, part of an ambitious effort to restore the seaweed ecosystems of Wellington harbour.

A landscape shot of calm clear water with kelp visible and some rocks on the left. Two people wearing snorkels rest on the sea surface near a red floatation device with a white flag. There are hills and a cloudy sky in the distance.

The kelp restoration pilot site at Worser Bay in Wellington. Photo: Claire Concannon / RNZ

Love Rimurimu

Love Rimurimu began as an educational programme delivered by Mountains to Sea Wellington, says project lead Zoe Studd. Local rangatahi were encouraged to learn more about seaweed, to get into the ocean and have a look around, and to learn about why kelp was disappearing.

But when students from Kura Kaupapa Māori o Ngā Mokopuna suggested that they should be actively growing kelp to plant back out, Love Rimurimu took on a new direction.

Now, the project is piloting plant-outs to help regenerate the giant kelp forests that are so vital to a healthy underwater ecosystem, working with Taranaki Wānui ki Te Upoko o Te Ika, NIWA, Victoria University of Wellington, the kura, and the local community.

Six people stand in front of the ocean underneath a blue sky with the hills of Wellington in the background. The two people on the left are wearing wetsuits.

The Love Rimurimu team at Worser Bay: Rachel Parry, Jorge Jiminez, Lee Rauhina-August, Siddharth Ravishankar, Zoe Studd and Dr Christopher Cornwall. Photo: Claire Concannon / RNZ

Listen to the episode to learn about the stressors impacting kelp, to hear how giant kelp is grown in a lab, and to meet some of the Love Rimurimu team who have been planting out kelp in their blue backyard.

Learn more:

Zoe spoke to RNZ Summer Times in 2022 about the educational side of Love Rimurimu and to Jesse Mulligan on Afternoons in 2021 when the project was just getting underway.
Christopher spoke to Afternoons about kelp ecosystems in danger in 2023, and was interviewed in 2021 as the winner of the Prime Minister's Emerging Scientist award.
For more on seaweeds, listen to The red seaweed of Otago Harbour and Multi-talented macroalgae – recent episodes from Our Changing World's extensive catalogue.
The Love Rimurimu website features lots of information about the reforestation project and Wellington's seaweed species.