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Aotearoa’s only species of seagrass, Nanzostera muelleri, is drawing new attention from scientists as efforts ramp up to understand and restore one of the country’s most important, and increasingly threatened, marine habitats.
Seagrass, a marine flowering plant with long green blades and underground rhizomes that hold it steady against tides and currents, grows in estuaries, harbours and sheltered coastal waters across the motu. While once considered relatively simple plants, recent research has shown that Aotearoa’s seagrass commonly flowers and produces seeds, an insight that could hold the key to rebuilding declining meadows.
These underwater meadows are ecological powerhouses. They filter and improve water quality, provide vital food and habitat for fisheries, enhance coastal resilience, support biodiversity, and store carbon – making them crucial allies in mitigating climate change. Despite their importance, seagrass habitats have been shrinking in many parts of Aotearoa and around the world, largely due to human impacts such as sedimentation, pollution and coastal development.
To help protect what remains, the Department of Conservation is encouraging New Zealanders to learn where seagrass grows through its Our Estuaries website, which maps key habitats nationwide.
Meanwhile, a major research initiative is underway to turn knowledge into action. Restore the Meadows, a programme led by the Cawthron Institute, is developing techniques to restore seagrass meadows across the country. A key part of this work is understanding when and where seagrass flowers, because flowers produce the seeds needed for successful restoration.
Researchers believe flowering typically occurs from spring to early summer, though timing may vary regionally. To track these patterns, the team has created the Aotearoa Seagrass Flower Survey Database, a national repository for observations from flower surveys.
By gathering data from across the country, scientists hope to pinpoint the best times to collect seeds, understand how flowering differs between regions, and determine how many flowers can be harvested without harming existing meadows.
The project’s leaders say this knowledge will form the foundation of large-scale restoration efforts, helping to secure the future of one of Aotearoa’s most valuable but vulnerable marine ecosystems.
