Athena Irvine searching for kakahi. PHOTOS/PETE MONK
Wairarapa’s ‘ecological engineers’ – freshwater mussels – will be part of a ground-breaking conservation effort next month, pulling their weight by keeping their new waterways clean at Zealandia. CAL ROBERTS spoke with the team behind the project.
Wairarapa’s pocket-sized engineers are on the move to provide a boost to Wellington waterways when they get there.
Kakahi are an at-risk freshwater mussel species that play a special role in water quality and health which will be introduced for the first time to Zealandia’s waters next month.
On Saturday, a team of about seven people from Zealandia, iwi and Greater Wellington Regional Council gathered at the Wairarapa Moana wetlands to prepare 50 kakahi for rehoming at Roto Mahanga, inside the ecosanctuary.
Freshwater ecologist Amber McEwen has developed a programme for relocating kakahi.
She led the project on Saturday, where gatherers braved cold waters, sifting in the shallows for Echyridella aucklandica – one of two kakahi species in the water.
“It was great fun – it was cold – but we got the job done.”
She said the mussels lived on the bottom of rivers and lakes “and quietly filter feed away”.
A single kakahi can filter up to a litre of water per hour.
“People call them ecological engineers for that reason – they have the ability to change the environment they are living in.”
McEwen said there were two species of kakahi in Lake Wairarapa, with numbers classed as “at risk” or “threatened nationally”.
“Comparably, worse than little spotted kiwi and North Island kokako, to name a few.”
She said kakahi could live longer than 50 years and typically travelled by attaching themselves to freshwater fish. This time, they were rinsed and placed in the back of a station wagon and driven to Wellington.
McEwen is conducting her PhD on kakahi at Victoria University of Wellington and will continue to study them as they establish themselves in a new environment for the first time in recent history.
A further 150 kakahi of a different species, Echyridella menziesii, were being sent to the sanctuary from the Parangarahu Lakes area, southeast of Wellington.
Zealandia was working with Taranaki Whanui, Rangitane o Wairarapa, and Ngati Kahungunu on the project.
McEwen said Wairarapa iwi played a big role on collection days preparing kite to collect the kakahi and joining the collection and biosecurity processes.
“They oversaw the whole thing in terms of the appropriate protocols and karakia.”
A karakia at the Wairarapa site was led by Terese Mcleod from Taranaki Whanui, who travelled from Wellington for the event.
Rangitane o Wairarapa’s Joseph Potangaroa said the mussel was considered as mahinga kai – a valued natural food resource.
“Not only the species itself was valued, but the area they’re found in.”
These days, he said it was reassuring to know that should something catastrophic happen to Wairarapa’s declining mussel population, they would continue to grow in a new habitat.
He found searching for the right species of mussel on Saturday to be a little tricky.
“For about every 30 that I found, one of them was the one we were looking for.”
Zealandia’s ambitious 500-year vision is to restore its 225ha ecosanctuary in Karori, including its waterways, to something resembling a pre-human state.
Zealandia’s lead conservation ranger Athena Irvine said kakahi were going to play a role its restoration long-term.
The sanctuary’s objective for translocating kakahi was multi-faceted.
The mussels were part of promoting a functioning lake ecosystem for its man-made lake, and the move would be a first step in broadening the species’ range.
She said the collection days in Wairarapa and Parangarahu Lakes area were interesting.
“Everybody was here for the kakahi, just this little freshwater mussel that most people know nothing about.”
She said the kakahi will be electronically tagged to monitor their time at Zealandia so McEwen, rangers and others can continue to learn about them.
The kakahi were being acclimatised to different kinds of water this week and in quarantine at Zealandia.
They will be released in the sanctuary from August 1.