Intra-Field Variation of Prokaryotic Communities On and Below the Seafloor in the Back-Arc Hydrothermal System of the Southern Mariana Trough

Abstract

Deep-sea hydrothermal vents harbor diverse prokaryotes. There are a variety of habitat types in a deep-sea hydrothermal field, e.g., active and inactive chimneys, iron-rich mats, venting fluid and hydrothermal plume. Numerous studies have shown the diversity and composition of prokaryotic communities in individual habitats. However, it is still unclear whether and how the characteristics of prokaryotic communities in their respective habitats are different. Previously, we reported 16S rRNA genes in a variety of habitats, i.e., hydrothermally active and inactive chimneys, iron-rich mats, a vent fluid, crustal fluids from boreholes, as well as ambient seawater in a back-arc basin hydrothermal field of the Southern Mariana Trough. Here we summarize the prokaryotic communities in the collected samples at higher taxonomic resolution (up to family level) using the detected 16S rRNA gene sequences and compare them using recently developed bioinformatics tools. The comparative analysis clearly highlights differences in prokaryotic communities among the habitat types on and below the seafloor in the Southern Mariana Trough. Furthermore, descriptions of cultured species and environmental clones close to the detected sequences provide valuable information for understanding of their distribution and potential of ecological roles in deep-sea hydrothermal fields.