Restoring sub-tidal seagrass at scale: A comparative analysis of seeding and transplantation technologies.

Seagrass restoration is increasingly gaining global attention, with large-scale restoration being the ultimate goal. Planting technologies play a critical role in large-scale restoration. Restoration performance comparison between planting technologies is currently limited. To facilitate comparison across seagrass species, this study proposes the following categorization for planting technologies: equipment-aided, passive dispersal, mechatronic-aided, and robotic. The respective technologies within each category are analyzed for their potential to restore large-scale areas in the sub-tidal zone. The criteria against which the technologies are being evaluated are operational feasibility, scalability, and restoration performance, each with subsequent sub-criteria. There is a distinct shortfall of shoot-based transplantation technologies, despite shoots being the preferred method for manual restoration. The comparison criteria indicate that only mechatronic-aided and robotic technologies are suitable for large-scale sub-tidal restoration. Recently, the availability of seed-based planting technologies has increased, and they have outperformed transplantation-based technologies according to the defined criteria. The trend of using seeds is expected to continue, with robotic technologies expected to provide an operational framework for large-scale restoration in the near future. Currently, mechatronic-aided technologies are better suited to large-scale restoration. However, it is predicted that, in the near future, robotic technologies will be able to collect their own donor material for seeds and perform planting themselves, thereby reducing the man-hours required for large-scale restoration.