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. © 2015, American Association for the Advancement of Science. All rights reserved.
|Original language||English (US)|
|Number of pages||3|
|State||Published - Mar 19 2015|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This is a contribution to the Malaspina 2010 Expedition project, funded by the CONSOLIDER-Ingenio 2010 program of the from the Spanish Ministry of Economy and Competitiveness (Ref. CSD2008-00077). J. M. A. was supported by a "Ramon y Cajal" research fellowship from the Spanish Ministry of Economy and Competitiveness. E.M. was supported by a fellowship from the Junta para la Ampliacion de Estudios program of CSIC. G.J.H. and R.L.H. were supported by the Austrian Science Fund (FWF) projects I486-B09 and P23234-B11 and by the European Research Council (ERC) under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement 268595 (MEDEA project). We thank A. Dorsett for assistance with DOC analyses, participants in the Malaspina Expedition and the crews of the BIO Hesperides, and RV Pelagia and the personnel of the Marine Technology Unit of CSIC for their invaluable support. Original data sets are available online at http://digital.csic.es/handle/10261/111563. J. M. A. designed the experimental setup, carried out part of the experiments, measured prokaryotic abundance, analyzed the data, and wrote the manuscript. E.M. carried out part of the experiments and data analysis. C.M.D. designed the Malaspina 2010 Expedition, was responsible for DOC analyses, and together with G.J.H. contributed to the design of the experiments and discussion of results. R.L.H. and T.D. analyzed the FT-ICR-MS samples. All authors discussed the results and contributed to the manuscript.