Environmental Cues Driving Germination of Zostera muelleri : Critical Steps Towards Seed‐Based Seagrass Restoration in Aotearoa New Zealand

Seagrasses are globally important ecosystems that provide critical services, yet are rapidly declining, driving a need for restoration. While seed‐based restoration offers potential for large‐scale recovery, success is often limited at early recruitment stages. Germination cues are environmental signals that influence dormancy release and subsequent germination. They present a key bottleneck in seagrass restoration, where labour‐intensive, seed‐limited efforts make improving germination rates essential for restoration efficiency. In controlled laboratory conditions, we manipulated three germination cues previously identified for Zostera muelleri , Aotearoa New Zealand's only native seagrass species, temperature (18 or 13 °C), a weekly 24‐h freshwater pulse, 0 PSU (freshwater‐pulsed or non‐pulsed) and oxygen availability (oxic or anoxic). Freshwater pulses were the dominant driver of germination, with cumulative germination success of 15.5% in freshwater‐pulsed treatments, compared to non‐pulsed treatments with 0.25% success. Over 90% of germinations occurred within 24 h of a freshwater pulse, and germinations were observed across successive weeks, suggesting that repeated short duration freshwater exposure may progressively improve germination yields. Within freshwater‐pulsed treatments, warmer temperature (18 °C) combined with anoxia enhanced germination, resulting in the highest success (25%) and significantly increased weekly germination rates, highlighting that germination responses are shaped by multiple interacting cues and are likely context‐dependent. These findings provide insights into the environmental conditions required to stimulate germination, laying a foundation for seed‐based restoration and nursery development in Aotearoa New Zealand. More broadly, the role of freshwater pulse regimes in driving germination has wider relevance for seagrass restoration efforts globally.