title: Global distribution of microbial abundance and biomass in subseafloor sediment.
abstract: The global geographic distribution of subseafloor sedimentary microbes and the cause(s) of that distribution are largely unexplored. Here, we show that total microbial cell abundance in subseafloor sediment varies between sites by ca. five orders of magnitude. This variation is strongly correlated with mean sedimentation rate and distance from land. Based on these correlations, we estimate global subseafloor sedimentary microbial abundance to be 2.9⋅10(29) cells [corresponding to 4.1 petagram (Pg) C and ∼0.6% of Earth's total living biomass]. This estimate of subseafloor sedimentary microbial abundance is roughly equal to previous estimates of total microbial abundance in seawater and total microbial abundance in soil. It is much lower than previous estimates of subseafloor sedimentary microbial abundance. In consequence, we estimate Earth's total number of microbes and total living biomass to be, respectively, 50-78% and 10-45% lower than previous estimates.
authors.affiliation: Institut für Erd- und Umweltwissenschaften, Universität Potsdam, 14476 Potsdam, Germany. kallm@gfz-potsdam.de
authors.forename: Jens
authors.initials: J
authors.lastname: Kallmeyer
authors.forename: Robert
authors.initials: R
authors.lastname: Pockalny
authors.forename: Rishi Ram
authors.initials: RR
authors.lastname: Adhikari
authors.forename: David C
authors.initials: DC
authors.lastname: Smith
authors.forename: Steven
authors.initials: S
authors.lastname: D'Hondt
mesh_terms: D018533:Biomass; D002452:Cell Count; D003710:Demography; D005843:Geography; D019015:Geologic Sediments / Q000382:microbiology*; D016013:Likelihood Functions; D008954:Models, Biological; D010140:Pacific Ocean; D011156:Population Density; D025341:Principal Component Analysis; D012044:Regression Analysis