A collaborative project involving MacLab, Cawthron, Port Nelson and Moananui is seeing greenshell mussels (GSM) being grown off one of the port’s wharves to improve water quality in the wider Nelson haven.

Shannon Holroyd, Port Nelson’s Environment Manager, says the prompt was her CEO Hugh Morrison sending her an article about similar projects at the Ports of Auckland. These saw 38 seeded mussel lines attached to public space on an inner city wharf, as well as mussels being reseeded to improve water quality in the Hauraki Gulf.

Port Nelson, MacLab, and Cawthron are partners in the Moananui blue economy cluster. Moananui serves as the national centre for blue economy innovation and high-value creation, fostering collaboration, knowledge exchange, and access to innovation opportunities to accelerate responsible development within the maritime sector.

The entities developed a proposal for the Living Filters project, a first stage six-month trial to put GSMs into the port. It won some funding from the Sustainable Seas Fund. MacLab supplied nearly 29,000 juveniles for two frames, which were hung in sleeves off a port wharf in January.

Shannon says they’d grown between 8-11mm when first looked at 6 weeks later.
Cawthron has installed data loggers and samplers to monitor a range of factors including, water temperature and the presence of heavy metals and hydrocarbons.

Being sited on the estuary of the Maitai River brings heavy metals of rooves, hydrocarbons and other urban runoff. Boating activities such as painting and cleaning ships also contribute to the presence of heavy metals and hydrocarbons, which it’s hoped the mussels may reduce by filtration (also called ‘bioremediation’).

“Largely, however, we want to improve the clarity of the water,” says Shannon.

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