Microbiology and geochemistry of the FEAMP20 expedition
Shallow-water hydrothermal vents (SWHV) are dynamic ecosystems that occur below 200 m in tectonically active regions of the planet. They have been found to host highly diverse microbial consortia, employing diverse metabolic strategies. However, the relationships between hydrothermal fluid chemistry, geological settings and microbial community structure in SWHV has not been explored in detail. A previous study in the SWHV of the Aeolian archipelago suggested that resident microbial communities shifted according to different geochemical regimes following large-scale trends, responding to changes in volcanic activity. Here we investigate if these trends are observed between the two volcanic regions present in the Gulf of Naples, Italy. By applying 16S rRNA amplicon sequencing coupled with geochemical measurements, and by contextualizing it with previous geochemical measurements done in the region, we found that hydrothermal fluid chemistry plays a key role in controlling the availability of ecological niches, and therefore, imposes strong selective pressures in the resident microbial communities. This, in turn, is influenced by the typology of the hydrothermal system, and the geological setting where the vents are hosted. Additionally, by describing two new SWHV sites, we contribute to the characterization of the hydrothermalism in the region, unveiling the biodiversity associated with shallow-water hydrothermalism.