Restoration of the Seagrass Halodule uninervis: Harnessing the Strength of a Highly Tolerant Pioneer

Abstract Seagrass restoration is increasingly urgent as losses accelerate under pressures from development, declining water quality and climate change. However, scaling up seagrass restoration is challenging and costly. Here we review global restoration efforts with Halodule uninervis to date and explore the benefits of using this fast-growing pioneer species to increase the opportunity for restoration success. H. uninervis is a subtropical/tropical seagrass with a wide distribution across the Indo-Pacific region. Halodule spp. have life-history strategies characterised by fast growth, high disturbance tolerance, and rapid lateral expansion, making them resilient to multiple natural and anthropogenic disturbance regimes. Despite these advantageous opportunistic traits, only six studies/reports have attempted restoration of H. uninervis to date, highlighting a major gap between its ecological suitability and its use in practice. By synthesising available knowledge for this species and comparing it with its closely related and more widely restored congener Halodule wrightii , we show that both species share key traits that underpin high restoration success, including tolerance to temperature extremes, sediment instability, and transplantation stress. Drawing on evidence from Halodule restoration, emerging nursery-based work, and transplant trials on H. uninervis , we identify patterns indicating higher survival, expansion, and resilience when pioneer Halodule species are used as foundation taxa in restoration. By combining the existing knowledge of H. uninervis with nursery and field-based efforts with Halodule spp. and other seagrasses, we underscore the potential benefits and opportunities to improve and upscale seagrass restoration by harnessing the strength of this widespread pioneer species optimally adapted to a warming world.