Animal-mediated interactions for pollination in saltmarsh communities

Among the wide variety of biotic interactions, animal-mediated pollination plays a crucial role in the maintenance of the integrity of plant communities. Thus, there is increasing concern about the possible effects that the growing loss of pollinators (i.e., pollinator crisis phenomenon) might have on plant communities. Recent studies revealed that pollination interactions often occur at the landscape scale, with plant species of different communities interacting through pollinator sharing. Saltmarshes provide a suitable example of plant communities spatially co-occurring at the landscape scale, with the micro-topography determining a precise zonation of ecologically distinct halophytic communities. However, little is still known about pollination interactions in saltmarshes. The aim of the present study was to assess which halophytic community contribute best to pollinator species richness in saltmarshes and whether plant species of different halophytic communities interact through pollinator sharing. To this aim we placed 20 permanent plots per plant community and monitored pollination interactions between plants and pollinators once a month during the overall flowering season. Our results revealed that animal-mediated pollination occurred in only two halophytic communities, with three species depending on animals for their pollination. When comparing halophytic communities in terms of richness of pollinator species, the vegetation of sandbanks, mudflats and sandflats emerged as the richest one. Animal-pollinated species of saltmarshes only partially shared pollinator species, revealing an overall low exchange of pollinators between different halophytic communities. In conclusion, the high complementarity in the spectrum of pollinators showed by animal-pollinated species of different halophytic communities makes all halophytic communities hosting animal-pollinated species important for the conservation of pollinators.