Long-term seed storage and viability of Zostera marina

•Seed viability is reduced with storage, 1 year old @ 78%, to 4 year old @ 32%.•Only 5% of seeds develop foliage leaves.•Fractures in the seed coat increase with age.

Successful establishment of seedlings in populations of Zostera marina (eelgrass), especially for restoration efforts using stored seeds, depends in part on viability and germination of seeds. Seeds of Z. marina were collected from plants and stored in seawater at 5 °C for up to several years. Seed viability, assessed with the viability stain, tetrazolium chloride, decreased steadily over a four-year period. There was a strong correlation between age and viability; viability of fresh seeds was approximately 77% whereas for four-year old seeds was 32%. However, only 51 of 975 of fresh seeds that germinated (∼5%) developed leaves. The physical structure of the seed was evaluated to understand the effects of aging. It was determined that as seeds age there is an increase in the number of fractures on the seed coat. These data combined with the recent awareness that global seagrass populations are declining present valuable information to help maintain viable seed repositories which may contribute to the conservation and restoration of these wild plants.