Seasonal Dynamics of Epiphytic Microbial Communities on Marine Macrophyte Surfaces.

Surfaces of marine macrophytes are inhabited by diverse microbial communities. Most studies focusing on epiphytic communities of macrophytes did not take into account temporal changes or applied low sampling frequency approaches. The seasonal dynamics of epiphytic microbial communities was determined in a meadow of invaded by and in a monospecific settlement of at monthly intervals. For comparison the ambient prokaryotic picoplankton community was also characterized. At the OTU level, the microbial community composition differed between the ambient water and the epiphytic communities exhibiting host-specificity. Also, successional changes were observed connected to the macrophyte growth cycle. Taxonomic analysis, however, showed similar high rank taxa (phyla and classes) in the ambient water and the epiphytic communities, with the exception of , which were only found on . showed seasonal changes while other high rank taxa were present throughout the year. In months of high presence the majority of cyanobacterial sequences were classified as . Phylogenetic groups present throughout the year (e.g., , members without known relatives within , and members without known relatives within ) constituted most of the sequences, while less abundant taxa showed seasonal patterns connected to the macrophyte growth cycle. Taken together, epiphytic microbial communities of the seagrass and the macroalga appear to be host-specific and contain taxa that undergo successional changes.