The influence of current and ripple development on seagrass transplant survival

Abstract

Seagrass restorations have been conducted globally but with low overall survival rates. To investigate the role of hydrodynamic energy from tidal currents in the survival of newly transplanted seagrass, Zostera marina rhizome fragments with living shoots were transplanted into a sediment bed and exposed to unidirectional flow in a flume. In accordance with planting techniques reported to improve restoration performance, garden staples were utilized to anchor transplants to the bed. Three flow conditions of increasing velocity were applied for a duration of six hours each, and current ripples developed and persisted in all cases. The ripples were characterized and related to the dislodgement of transplants from the sediment. The use of staples decreased the number of transplants that were dislodged. At lower velocities, transplant survival was further improved when the anchoring staple was oriented parallel to the direction of flow. Most of the transplants that were secured with a staple survived all velocity cases, even with average ripple amplitudes reaching the range of depth at which the roots and rhizomes were planted. These results can inform effective site selection and transplanting techniques for more successful seagrass restorations.