Extending the life history of a clonal aquatic plant: Dispersal potential of sexual and asexual propagules of Zostera noltii

• We study dispersal potential of Zostera noltii propagules.
• Z. noltii fragments show higher dispersal potential than detached individual seeds.
• After floating for 55 days 15% of fragments were still viable and growing.
• Spathe release occurs exclusively after the seeds ripe.
• Detached Z. noltii seeds show small dispersal capacity of <30 cm.

The dispersal potential of sexual and asexual propagules of Zostera noltii was experimentally quantified in still water and under different currents in microcosm and mesocosm facilities. We estimated sinking rates of seeds and changes over time in shoot buoyancy, shoot viability, fragment breakage, shoot growth rate and spathe release rate of floating fragments. The fast sinking rates of detached Z. noltii seeds suggest a small spatial scale of dispersal insufficient to connect fragmented populations, whereas the traits of floating fragments, particularly shoot buoyancy and shoot survival (>55 d), suggest a potential for long distance dispersal (>2300 km) that could connect distant patches and allow colonization of new areas. We showed that the Z. noltii vegetative and reproductive fragments have the potential to extend the dispersal achieved by detached seeds alone.