title: Ocean chemistry. Dilution limits dissolved organic carbon utilization in the deep ocean.
abstract: Oceanic dissolved organic carbon (DOC) is the second largest reservoir of organic carbon in the biosphere. About 72% of the global DOC inventory is stored in deep oceanic layers for years to centuries, supporting the current view that it consists of materials resistant to microbial degradation. An alternative hypothesis is that deep-water DOC consists of many different, intrinsically labile compounds at concentrations too low to compensate for the metabolic costs associated to their utilization. Here, we present experimental evidence showing that low concentrations rather than recalcitrance preclude consumption of a substantial fraction of DOC, leading to slow microbial growth in the deep ocean. These findings demonstrate an alternative mechanism for the long-term storage of labile DOC in the deep ocean, which has been hitherto largely ignored.
authors.affiliation: Department of Global Change Research, Institut Mediterrani d'Estudis Avançats (IMEDEA), Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de las Islas Baleares (UIB), 07190 Esporles, Spain. Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia. txetxu@mail.com.
authors.forename: Jesús M
authors.initials: JM
authors.lastname: Arrieta
authors.affiliation: Department of Global Change Research, Institut Mediterrani d'Estudis Avançats (IMEDEA), Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de las Islas Baleares (UIB), 07190 Esporles, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Mayol
authors.affiliation: Department of Limnology and Bio-Oceanography, Division Bio-Oceanography, University of Vienna, Althanstr. 14, 1090 Vienna, Austria.
authors.forename: Roberta L
authors.initials: RL
authors.lastname: Hansman
authors.affiliation: Department of Limnology and Bio-Oceanography, Division Bio-Oceanography, University of Vienna, Althanstr. 14, 1090 Vienna, Austria. Department of Biological Oceanography, Royal Netherlands Institute for Sea Research (NIOZ), 1790AB Den Burg, Netherlands.
authors.forename: Gerhard J
authors.initials: GJ
authors.lastname: Herndl
authors.affiliation: Research Group for Marine Geochemistry (ICBM-MPI Bridging Group), Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl von Ossietzky University Oldenburg, and Max Planck Institute for Marine Microbiology (MPI), Bremen, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Dittmar
authors.affiliation: Department of Global Change Research, Institut Mediterrani d'Estudis Avançats (IMEDEA), Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de las Islas Baleares (UIB), 07190 Esporles, Spain. Red Sea Research Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia. The UWA Oceans Institute, University of Western Australia (UWA), Crawley, WA, Australia.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Duarte
mesh_terms: D002244:Carbon / Q000032:analysis; D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000737:chemistry*; D009792:Oceans and Seas; D012623:Seawater / Q000737:chemistry* / Q000382:microbiology*
chemical_list: D002245:Carbon Dioxide; D002244:Carbon