A new seagrass blueprint released by Cawthron Institute hopes to pave the way for large-scale restoration efforts of seagrass meadows across the country, helping to support biodiversity, improve water quality and sequester carbon.

‘Restore the Meadows’ is a multi-year research programme led by Cawthron that began in 2022. The programme aims to trial seed-based seagrass restoration methods using a Nelson Haven case study that could inform scalable seagrass restoration efforts.

Seagrass meadows are one of the world’s most valuable coastal ecosystems, offering an array of ecosystem services such as supporting biodiversity and food security, regulating water quality and mitigating climate change by sequestering carbon. But they are in decline globally, threatened by a range of human activities.

“Our aim was to develop an easy to use, step-by-step guide for groups and organisations with an interest in seagrass restoration,” said project co-leader Dr Anna Berthelsen.

“We’ve included simple methods wherever possible to help ensure as many people as possible can participate in seagrass restoration. Whilst specialist equipment is required for some activities, our goal is to continue to make this important restoration activity as easy as possible because we know that thriving seagrass meadows are vital for ecosystem health in coastal areas.”

Restoration projects around the world have achieved success by directly sowing seed into the wild. Until recently, seed-based restoration was not considered for Aotearoa New Zealand because seagrass flowering required for seed production was thought to be rare. However, Cawthron’s research has helped confirm that Aotearoa New Zealand’s only seagrass species, Zostera muelleri, flowers much more often than originally thought, and the team has successfully managed to germinate these seeds and develop seed-based restoration techniques.

“This shows the potential for using seeds to restore seagrass meadows across the country at scales required to achieve meaningful biodiversity, ecosystem health and carbon sequestration results, provided existing seagrass stressors are removed or reduced,” said Dr Berthelsen.

The seagrass blueprint covers how to plan and carry out seed-based seagrass restoration including collecting flowers; extracting, storing, germinating and sowing seeds; monitoring restoration success; and community engagement. It is specific to intertidal rather than subtidal seagrass and does not include guidance on how to remove existing seagrass stressors prior to restoration.

“We are thrilled that within a couple of years we have been able to develop this blueprint to guide seed-based seagrass restoration activities in Aotearoa New Zealand. We’d love to see this programme evolve to include seagrass nurseries that produce flowers and seeds. If we can optimise restoration techniques and if environmental conditions are suitable, there’s a real chance that our precious seagrass meadows can begin to recover,” said Dr Berthelsen.

However, there are still key knowledge gaps to explore, such as field conditions for seeds and seedlings, and the team is seeking ongoing funding support to continue this important research.

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