{"id":13506,"date":"2019-03-15T13:49:00","date_gmt":"2019-03-15T20:49:00","guid":{"rendered":"https:\/\/www.darkenergybiosphere.org\/?post_type=publication&#038;p=13506"},"modified":"2019-04-01T13:31:55","modified_gmt":"2019-04-01T20:31:55","slug":"fluid-geochemistry-local-hydrology-and-metabolic-activity-define-methanogen-community-size-and-composition-in-deep-sea-hydrothermal-vents","status":"publish","type":"publication","link":"https:\/\/www.darkenergybiosphere.org\/publication\/fluid-geochemistry-local-hydrology-and-metabolic-activity-define-methanogen-community-size-and-composition-in-deep-sea-hydrothermal-vents\/","title":{"rendered":"Fluid geochemistry, local hydrology, and metabolic activity define methanogen community size and composition in deep-sea hydrothermal vents"},"content":{"rendered":"<p>The size and biogeochemical impact of the subseafloor biosphere in oceanic crust remain largely unknown due to sampling limitations. We used reactive transport modeling to estimate the size of the subseafloor methanogen population, volume of crust occupied, fluid residence time, and nature of the subsurface mixing zone for two low-temperature hydrothermal vents at Axial Seamount. Monod CH<sub>4<\/sub>\u00a0production kinetics based on chemostat H<sub>2<\/sub>\u00a0availability and batch-culture Arrhenius growth kinetics for the hyperthermophile\u00a0<i>Methanocaldococcus jannaschii<\/i>\u00a0and thermophile\u00a0<i>Methanothermococcus thermolithotrophicus<\/i>\u00a0were used to develop and parameterize a reactive transport model, which was constrained by field measurements of H<sub>2<\/sub>, CH<sub>4<\/sub>, and metagenome methanogen concentration estimates in 20\u201340\u2009\u00b0C hydrothermal fluids. Model results showed that hyperthermophilic methanogens dominate in systems where a narrow flow path geometry is maintained, while thermophilic methanogens dominate in systems where the flow geometry expands. At Axial Seamount, the residence time of fluid below the surface was 29\u201333\u2009h. Only 10<sup>11<\/sup>\u00a0methanogenic cells occupying 1.8\u201318\u2009m<sup>3<\/sup>\u00a0of ocean crust per\u2009m<sup>2<\/sup>\u00a0of vent seafloor area were needed to produce the observed CH<sub>4<\/sub>\u00a0anomalies. We show that variations in local geology at diffuse vents can create fluid flow paths that are stable over space and time, harboring persistent and distinct microbial communities.<\/p>\n","protected":false},"template":"","tags":[],"publication_type":[19],"_links":{"self":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/publication\/13506"}],"collection":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/publication"}],"about":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/types\/publication"}],"wp:attachment":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/media?parent=13506"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/tags?post=13506"},{"taxonomy":"publication_type","embeddable":true,"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/publication_type?post=13506"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}