Storms on the Western Black Sea shore: an opportunity for long-distance dispersal of coastal dunes psammophytes?

Coastal areas are among the planet's most dynamic yet vulnerable environments, the shape of sand dunes being typically modeled by two sets of forces: the relatively constant action of wind and waves and the disturbances caused by infrequent but powerful storms. These meteorological events affect the plant communities, but can also play an important role in the long-distance dispersal of some psammophytes. Plants can be exposed, uprooted, broke apart and spread by wind and waves. Then, depending on the resilience of the plant to seawater temperature, the duration of immersion, the type of fragment transported and the suitability of the new habitat, new population can be established. This study aimed to assess the resilience to seawater immersion and the ability of long-distance dispersal of three psammophytes: Convolvulus persicus, Alyssum borzaeanum, and Silene thymifolia. The experiments tested the viability of vegetative fragments and the reproductive capacity of seeds under different exposure periods (5, 10, and 15 days) and temperature conditions: 4 °C (average surface seawater temperature during winter and early spring when storms on the Black Sea Coast occur), 13 °C (average surface seawater temperature), and 23 °C (average summer surface seawater temperature). The increase of both seawater temperature and the exposure time had a significant negative influence on the viability of the vegetative fragments and on germination capacity. After exposure to seawater, Convolvulus persicus, and Silene thymifolia are able to establish new populations through vegetative fragments or seeds, whilst in case of Alyssum borzaeanum, no vegetative regeneration was observed.