Microbiological investigation of hydrothermal vent plumes in Australian-Antarctic Ridge, Southern Ocean

Abstract

The mid-ocean ridge (MOR) is the longest underwater mountain system where new ocean crust is continuously created. The intermediate spreading Australian-Antarctic Ridge (AAR) in the Southern Ocean is one of the largest unexplored regions of the global MOR system because of extreme conditions. During two RV Araon AAR expeditions in 2011, deep-sea hydrothermal vent signals were obviously detected by MAPR (Miniature Autonomous Plume Recorder) at a southmost site (62.2°S) in the MOR system. During the Araon cruise in 2013, samples of vent plumes were collected with Niskin bottles by CTD (conductivity, temperature and depth with potential reduction and turbidity sensors integrated) toyo-ing. In addition, some new benthic animals including crabs and starfish were collected during the cruise. To find microbiological signature of hydrothermal vent plume at the new vent site, bacterial community analysis was performed for the samples in 2011. In 2013, extensive data of microbial community structures using 16S rRNA genes were obtained for the samples of hydrothermal vent plumes and ambient seawaters. About one hundred of culturable bacterial strains were isolated from the vent plumes, revealing the presence of thermophlic bacteria. Community structures of symbiotic bacteria associated with vent crabs and potential functions are going to be analysed using metagenomic approaches. Overall, microbiological data along with the geochemical data in the study area strongly support the presence of new deep-sea hydrothermal vent environments in the Southern Ocean, which will offer prospects for biogeography and evolution of global vent communities.