An effective seed protection method for planting Zostera marina (eelgrass) seeds: Implications for their large-scale restoration

•We develop an innovative method of planting Z. marina seeds with burlap bag.•Seedling establishment rate under 200–500seedsbag−1 ranged from 16% to 26%.•New patches from seed were fully developed and well maintained after 2–3years.•400seedsbag−1 may be the most suitable for the establishment of new patches.•The method should be considered for future large-scale Z. marina restoration. We describe an innovative method of planting Zostera marina (eelgrass) seeds in which hessian bags filled with high-silted sediments are used as a seed protecting device. Here, we evaluated the effectiveness of the method through a field seed-sowing experiment over a three year period. The suitable seed planting density required by the seeds of Z. marina in this method was also investigated. In the spring following seed distribution, seedling establishment rate of Z. marina subjected to different seed densities of 200–500seedsbag−1 ranged from 16% to 26%. New eelgrass patches from seed were fully developed and well maintained after 2–3years following distribution. The seed planting density of 400seedsbag−1 may be the most suitable for the establishment of new eelgrass patches. Our results demonstrate that seed-based restoration can be an effective restoration tool and the technique presented should be considered for future large-scale Z. marina restoration projects.