Faunal and microbial biodiversity of the newly discovered Deyin-1 hydrothermal vent field at 15°S on the southern Mid-Atlantic Ridge

The southern Mid-Atlantic Ridge (SMAR) is a representative slow-spreading ocean ridge. However, when compared with the northern Mid-Atlantic Ridge (NMAR), the SMAR has not been extensively explored. In particular, there is little information on the vent ecology, with no comprehensive ecological surveys conducted along the SMAR south of 10 degrees S. In 2011, a new hydrothermal vent field, named Deyin-1, was discovered on the SMAR at 15.17 degrees S. In this study, we recorded hydrothermal vent fauna and microbial diversity in both the hydrothermal plumes and deposits of Deyin-1. The biodiversity and distribution of the vent inhabitants were surveyed by phylogenetic analysis, high-throughput pyrosequencing, and in situ observation using a remotely operated vehicle. Results showed that the predominant primary consumers were shrimp (Rimicaris exoculate), crabs (Segonzacia maatlantica), and Bathymodiolus-like mussels, in addition to the common vent predators Macrouridae fish (Cetonurus globiceps), eelpout-like fish, and suspected octopuses. Phylogenetic analysis based on the mitochondria' cytochrome c oxidase subunit I gene and nonmetric multidimensional scaling analysis based on the vent fauna occurrence data revealed that the Deyin-1 vent fauna was closely related to species found on the NMAR. Sulfur-oxidizing bacteria (SOB) of the SUP05 Glade and ammonia-oxidizing archaea belonging to the phylum Thaumarchaeota dominated the vent plume microbial community. Putative thermophilic hydrogenoxidizing chemo-lithoautotrophs, including those belonging to archaeal genera Archaeogiobus and Methanocaldococcus and bacterial genera Desulfurobacterium and Nautilia, dominated the active chimney community, as well as a putative hyperthermophilic sulfur-reducing chemo-organoheterotroph belonging to archaeal genus Thermococcus. While Sulfurovum SOB constituted the predominant episymbionts of the vent shrimp. Overall, our study provides a comprehensive survey of vent life within the southernmost vent field of the SMAR to be investigated to date. The results presented herein will aid in our understanding of the bio-connectivity of species along the MAR.