Ocean acidification mitigation strategies for the mussel industry

Green-lipped mussels. © Dave Allen, NIWA

We are testing techniques to raise the pH of coastal waters around mussel farms to improve shellfish growth. 

Project leader: Cliff Law, NIWA/University of Otago

Duration: February 2017 – September 2019 
Budget: $300,000 
Status: Ongoing 

Coastal waters are becoming more acidic due to increasing atmospheric carbon dioxide and local processes such as microbial respiration. This is a threat to Aotearoa New Zealand’s shellfish aquaculture industry, because mussels are less healthy and don’t grow as well at lower pH. 

We are testing two techniques to see how effective they are at alleviating acidification around mussel farms. The first involves using waste mussel shells, which could raise pH and dissolved carbonate as they break down. The second is strategic aeration of farm waters at night, when oxygen and pH are naturally lower. 

In May 2018, in collaboration with the New Zealand seafood company Sanford, we measured the impact of these techniques at one of their mussel farms. The results are being used in hydrodynamic models, to estimate the benefits for mussel farms at the top of the South Island. We will also test the impact of these techniques on the survival and condition of mussel spat and juveniles. 

In addition to assisting the shellfish aquaculture industry, this research may contribute to mitigation of acidification in natural coastal ecosystems.

Watch Mitigating ocean acidification to protect mussels (2:10 mins)

Journal articles

Meduna V (2017) Acid Seas. New Zealand Geographic, 147 (Sept-Oct)

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Media statement: Today's marine environment report from MfE and StatsNZ

Julie Hall, Director: "It is deeply concerning that the state of our marine environment has not improved in the last three years. Resilient coasts and oceans are essential to New Zealanders' health and wealth, so urgent action is needed to address the decline. There is a growing need for ecosystem-based management (EBM) to holistically manage risk and sustain Aotearoa's coasts and oceans. This is even more important given the ongoing impacts of climate change."

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