A new initiative to enhance the resilience of marine life to the effects of climate change and human impact has launched this week in Tauranga Harbour. Video / Deep Dive Division
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Tauranga Harbour’s biodiversity declined after Cyclone Gabrielle due to sediment build-ups covering reefs.
Deep Dive Division created artificial reefs to restore marine life, using mātauranga Māori and advanced technology.
The project, involving local iwi and universities, aims to support marine ecosystems and the “blue economy”.
An artificial reef programme aims to restore marine life in Tauranga Harbour.
Tauranga Harbour saw a massive decline in biodiversity after Cyclone Gabrielle, and a colossal build-up of sediment covered reef systems.
Deep Dive Division, led by Tua and Courtney Karalus, has created an underwater reefsystem to help the necessary larvae and algae find a new home.
The project, involving local iwi and universities, aims to support marine ecosystems and the “blue economy”.
Tua and Courtney Karalus, co-owners of Deep Dive Division.
“The rest is the circle of life,” Tua said.
Deep Dive Division is a Hamilton-based company specialising in commercial and scientific diving services across Aotearoa.
It is believed to be the only Māori and Pacific-owned dive company in New Zealand, combining Māori perspectives with environmental science and advanced technology.
The nine reefs, situated 13m deep in Tauranga Harbour, were collectively named Peara, meaning “pearl” in te reo Māori and symbolising the nucleus of change, growth and life, Tua said.
The team at Deep Dive Division get ready to send the artificial reef to the ocean floor.
The artificial reefs were also given another name, “social housing for crayfish”, and use natural fibres and marine-grade concrete along with proven techniques in how to deploy and rig them to the ocean floor.
The artificial reef systems have been deployed in the water to biomimic the habitats of our natural marine ecosystems and restore and protect biodiverse native marine life.
Six of the structures were manufactured at Hynds Pipe Systems Ltd under the leadership of Hynds Holdings director and R&D director Aaron Hynds.
The remaining three were constructed using a 3D concrete-printing technique.
The project was a collaboration between Deep Dive Division, the University of Waikato, local iwi, Hynds Pipe Systems Ltd and the Port of Tauranga.
The trial is scheduled to run for an initial period of 24 to 36 months.
The effects of the artificial reefs on marine life are plain to see and happen fast, Tua said.
Tua Karalus out on Tauranga Harbour.
Tua said when they started installing the second part of the reef, he saw that crayfish were already crawling on the first part.
“It went straight to the hole that was designed for it.”
Projects like Peara were a push into the “blue economy” and the beginning push into aquaculture, he said.
“We embrace this industry because there will be jobs for local people.”
It was a purpose-driven project, starting with surveying the water and marine life and understanding the situation in Tauranga Harbour in real time, Courntey Karalus said.
There was also a purposeful New Zealand-led and based approach to creating these artificial reefs, she said.
“Many reef systems going in New Zealand are being bought in from Australia.”
Deep Dive Division recognised the strong cultural identity New Zealand has regarding the ocean and freshwater, Courtney said.
“We’ve got a marine heritage that we need to acknowledge.”
Deep Dive was established in 2018 and was involved with urban ocean agriculture structures, with a more real-world approach to environmental science.
She said the idea for the artificial reef followed the initial meeting with their partners in Tauranga Harbour.
“We were sitting at our home office whiteboard and sketching something up.”
University of Waikato professor Chris Battershill and Professor David Schiel, from the University of Canterbury, have led Ministry of Business, Innovation and Employment-funded research to assess marine life loss in the Eastern Bay of Plenty.
Chris Battershill, Tua Karalus and Aaron Hynds.
Battershill has worked closely on the development of Peara, providing scientific guidance on the conditions needed for marine ecosystems to regenerate.
The Peara reefs were designed to support the growth of seaweed and shellfish, act as a wave break, and attract marine life.
Inbuilt harmonics also helped deter whales and reduce the risk of beaching.
By introducing hard substrates, such as natural marine rock or engineered structures like Peara, the reefs provided essential footholds for marine life to grow in sandy or silty environments that typically lacked structure.
Reef structures and their acoustic properties were designed using mātauranga Māori to support the colonisation of native marine species in harbours, Battershill said.
“These native colonisers help resist the spread of invasive species.”
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Native kelps such as Ecklonia and Carpophyllum forest species, along with mats of turfing red seaweeds, provided habitat for important taonga like crayfish, kina and other invertebrates that also served as food for fish, Battershill said.
“These reef outcrops offer refuge for marine biodiversity that is now rare or absent in the harbour.”
