New multi-million dollar removal technology projects underway
Contracts have been awarded for three projects to drive improvements in technology to control exotic caulerpa seaweed.
The three projects share the $10 million funding injection announced last year and focus on methods that have previously shown promise.
Northland Regional Council (NRC) has been awarded the largest contract, with just over $6 million to progress its large-scale mechanical suction dredging technique that was trialled in Omakiwi Cove last year.
The first phase of the work, funded under the accelerated programme, demonstrated that the method can remove exotic caulerpa from sandy areas of the seafloor, and now the plan is to increase its effectiveness.
The project team is developing a new tool called a ‘submersible dredge planer’ which will operate remotely on the seafloor, rather than from a barge, and aims to remove caulerpa in a single pass.
The new system will include a dredge head, pumping arrangement, GPS positioning system, dredge spoil processing plant, and disposal system.
Work is in the planning and development stage, with trials in the water expected to start later in the year.
The second project, receiving $2 million in funding, is developing an ultra-violet light (UV-C) irradiation tool to kill the pest seaweed.
This contract has been awarded to Advanced Aquarium Technologies Ltd who aim to create a cost-effective option to treat exotic invasive caulerpa without needing to deploy SCUBA divers.
It will require minimal labour, operate off a vessel, and be able to be used at any depth of water from intertidal zones to 40m depth which is important as exotic caulerpa can grow at this depth.
The team expects to trial the technology in Omakiwi Cove, Northland, in March.
The third project, with $1.9 million funding, is a special underwater treatment ‘chamber’ with a frame which covers the area of caulerpa being treated and has curtains to contain chlorine within the specific treatment area.
This chlorine treatment chamber, being developed by Commercial Dive Specialists, will be able to hover over the seabed and pass over rocks and other obstacles without getting stuck. Work on this project also starts within weeks at Omakiwi Cove.
Exotic caulerpa found in new locations
Exotic caulerpa has recently been detected at a handful of locations close to known affected areas in Northland, Auckland and Coromandel.
It has been confirmed present in three Bay of Islands sites outside of the main infested area at Omakiwi Cove - Paradise Bay on the western side of Urapukapuka Island, the southern end of Motukiekie Island, and at Army Bay on Motorua Island.
The three locations are close to, but outside of, the controlled area at Omakiwi Cove where legal restrictions on anchoring and fishing are in place.
Biosecurity New Zealand is working with Council and mana whenua to determine next steps which will include further surveillance to help understand the state of infestation at each site and whether control measures are feasible.
There have also been five further detections in the Auckland and Waikato regions since the last issue of this newsletter:
Repanga/Cuvier Island, between Aotea Great Barrier Island and Ahuahu Great Mercury Island, Waikato
Square Top Island, off the tip of the Coromandel Peninsula, Waikato
Hakaimango Point, Waiheke Island, Auckland
Kaiaraara Bay, Aotea Great Barrier Island, Auckland
Katherine Bay, Aotea Great Barrier Island, Auckland.
There will be further investigation at these sites and, where feasible, treatment will be carried out.
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