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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13891

Saltmarsh seeds in motion: the relative importance of dispersal units and abiotic conditions

Zhiyuan Zhao, Liquan Zhang, Lin Yuan*, Tjeerd J. Bouma

*Corresponding author:

ABSTRACT: Propagule dispersal is fundamental to the colonization of new habitats, metapopulation connectivity, and gene flow and thus enables saltmarsh species to cope with global change. In this study, mesocosm and flume experiments were used to quantify the effects of different dispersal units (i.e., seed, spikelet, inflorescence, and plant fragment-containing seeds) and abiotic conditions on the dispersal processes of four globally distributed saltmarsh species: Salicornia europaea, Scirpus maritimus, Spartina anglica, and Elymus athericus. The results show that (1) moving seawater has a species-specific effect on the buoyancy, leading to the prolonged floatability of high-tidal flat species E. athericus and reduced floatability of pioneer species; (2) tidal currents increase the dispersal speed, whereas wind can have additive or antagonistic effects on the current-dominated dispersal speed depending on its direction; (3) wave action reduces the dispersal speed, but this effect becomes smaller with increasing wave magnitudes and/or applied co-directional wind; (4) the dispersal speed may vary depending on the physical forcing and type and morphology of the dispersal units, but the largest species effect is related to the period in which units remain buoyant; and (5) the dispersal potential of saltmarsh species in wind wave-dominated coastal environments can be ordered as follows: E. athericus > S. maritimus > S. anglica > S. europaea. The present study provides valuable guidance for future numerical hydrodynamic models of the saltmarsh dispersal and establishment, allowing more accurate prediction of the distributional responses of saltmarsh species to climate change, thereby supporting appropriate management and restoration strategies.