Novel Insights on the Bacterial and Archaeal Diversity of the Panarea Shallow-Water Hydrothermal Vent Field

Current knowledge of the microbial diversity of shallow-water hydrothermal vents is still limited. Recent evidence suggests that these peculiar and heterogeneous systems might host highly diversified microbial assemblages with novel or poorly characterized lineages. In the present work, we used 16S rRNA gene metabarcoding to provide novel insights into the diversity of the bacterial and archaeal assemblages in seawater and sediments of three shallow-water hydrothermal systems of Panarea Island (Tyrrhenian Sea). The three areas were characterized by hot, cold, or intermediate temperatures and related venting activities. Microbial biodiversity in seawater largely differed from the benthic one, both in alpha-diversity (i.e., richness of amplicon sequence variants-ASVs) and in prokaryotic assemblage composition. Furthermore, at the class level, the pelagic prokaryotic assemblages were very similar among sites, whereas the benthic microbial assemblages differed markedly, reflecting the distinct features of the hydrothermal activities at the three sites we investigated. Our results show that ongoing high-temperature emissions can influence prokaryotic alpha-diversity at the seafloor, increasing turnover (beta-)diversity, and that the intermediate-temperature-venting spot that experienced a violent gas explosion 20 years ago now displays the highest benthic prokaryotic diversity. Overall, our results suggest that hydrothermal vent dynamics around Panarea Island can contribute to an increase in the local heterogeneity of physical-chemical conditions, especially at the seafloor, in turn boosting the overall microbial (gamma-)diversity of this peculiar hydrothermal system.

Automated summary

Current knowledge of the microbial diversity of shallow-water hydrothermal vents is limited. This study used 16S rRNA gene metabarcoding to investigate the bacteria and archaea in seawater and sediments of three shallow-water hydrothermal systems. The results showed significant differences in microbial diversity between seawater and sediments. Additionally, the benthic microbial assemblages differed markedly among the three areas, reflecting the different hydrothermal activities. Overall, this study suggests that hydrothermal vent dynamics contribute to an increase in microbial diversity in this unique system.