Award: OCE-1535962

The goal of the overall proposal was to better understand the extent of the serpentinite subsurface at the Lost City Vent Field on the Atlantis Massif and, specifically, to address the hypotheses: (1) microbial diversity spans a wider range of temperature/pH conditions than currently recognized and (2) the scarcity of ΣCO2 is a key biological limitation to serpentinization-driven ecosystems that can be overcome by the metabolic activity of one or a few foundation species. The primary goal of the University of Washington portion of this project was to collect water samples in samplers capable of maintaining dissolved gases without loss, process and store the samples in glass ampoules at sea, and to measure the concentrations of hydrogen, methane, carbon dioxide, ethane and propane in a shore based laboratory at the University of Washington. The cruise for the project was carried out in September/October 2018 on board the RV Atlantis with the ROV Jason (both of Woods Hole Oceanographic Institution). We collected and processed twenty water samples which were subsequently analyzed for gas concentrations at UW. A primary finding of the project is that gas concentrations of samples taken during the 2018 cruise differed little from those taken at the same sites during the original Lost City cruise in 2003. This is important in that it implies that the rate of serpentinization (reaction of mantle rocks with seawater which produces hydrogen) has changed little druing the intervening 15 years. This has important implications for the overall flux of hydrogen from the system. Last Modified: 01/31/2020 Submitted by: Marvin D Lilley