Seasonal Patterns and Environmental Drivers of Seagrass ( Zostera muelleri ) Flowering in Aotearoa New Zealand: Implications for Seed‐Based Restoration

Seagrass flowering underpins seed‐based restoration and is governed by the interaction of multiple abiotic and biotic drivers operating across a range of temporal and spatial scales. In New Zealand/Aotearoa, flowering was historically considered rare, but emerging evidence indicates it is more widespread than previously recognised, creating new opportunities for restoration. We conducted a 4‐year study from 2022 to 2025 across three estuaries near Nelson, New Zealand, to investigate how seasonality, seagrass cover, tidal height and regional temperature anomalies influence Zostera muelleri flowering density and identify peak flowering periods within each intertidal system. Flowering occurred within a broadly predictable seasonal window, with mean peak inflorescence densities (11 ± 3.1 SE to 170  ± 53.2 m ⁻² , maximum 756 m ⁻² ) observed between November and January at the beginning of Austral summer. A generalised additive model showed that seagrass cover was the strongest and most consistent predictor of flower density, with denser meadows supporting significantly greater numbers of flowers. Tidal height and temperature anomalies further influenced flowering in some estuaries, with higher flowering density occurring higher on the shore and reduced flowering associated with both warmer‐ and cooler‐than‐average temperatures. Peak flowering densities recorded in high‐flowering years were comparable to those reported from some Australian meadows of the same species, where seed‐based restoration approaches are being trialled, suggesting that meadows in New Zealand can exhibit comparable reproductive capacity under favourable conditions. These results provide the first extensive assessment of seagrass flowering dynamics in New Zealand, offering fundamental ecological insights and practical guidance for optimising seed‐based restoration domestically and worldwide.