BG Biogeosciences BG Biogeosciences 1726-4189 Copernicus Publications Göttingen, Germany 10.5194/bg-11-5285-2014 Mechanisms of microbial carbon sequestration in the ocean – future research directions Jiao N. 1 Robinson C. https://orcid.org/0000-0003-3033-4565 2 Azam F. 3 Thomas H. https://orcid.org/0000-0002-6720-8434 4 Baltar F. https://orcid.org/0000-0001-8907-1494 5 Dang H. 1 Hardman-Mountford N. J. 6 Johnson M. https://orcid.org/0000-0002-4706-8294 2 Kirchman D. L. 7 Koch B. P. https://orcid.org/0000-0002-8453-731X 8 Legendre L. https://orcid.org/0000-0002-2854-7003 10 9 Li C. 11 Liu J. 1 Luo T. 1 Luo Y.-W. https://orcid.org/0000-0001-6106-7901 1 Mitra A. 12 Romanou A. 13 Tang K. 1 Wang X. 14 Zhang C. 15 Zhang R. 1 State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, UK Scripps Institution of Oceanography, UCSD, La Jolla, CA 920193, USA Dalhousie University, Halifax, Nova Scotia, Canada Department of Marine Science, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand CSIRO Marine and Atmospheric Research, Floreat, WA 6014, Australia School of Marine Science and Policy, University of Delaware, DE 19958, USA Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, 27570 Bremerhaven, Germany Sorbonne Universités, UPMC Univ. Paris 06, UMR7093, Laboratoire d'Océanographie de Villefranche, 06230 Villefranche-sur-Mer, France CNRS, UMR7093, Laboratoire d'Océanographie de Villefranche, 06230 Villefranche-sur-Mer, France State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China Centre for Sustainable Aquatic Research, Swansea University, Swansea, UK Dept. of Applied Physics and Applied Math., Columbia University and NASA-Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, USA South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China Tongji University, Shanghai, China 01 10 2014 11 19 5285 5306 Copyright: © 2014 N. Jiao et al. 2014 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://bg.copernicus.org/articles/11/5285/2014/bg-11-5285-2014.html The full text article is available as a PDF file from https://bg.copernicus.org/articles/11/5285/2014/bg-11-5285-2014.pdf

This paper reviews progress on understanding biological carbon sequestration in the ocean with special reference to the microbial formation and transformation of recalcitrant dissolved organic carbon (RDOC), the microbial carbon pump (MCP). We propose that RDOC is a concept with a wide continuum of recalcitrance. Most RDOC compounds maintain their levels of recalcitrance only in a specific environmental context (RDOC<sub>t</sub>). The ocean RDOC pool also contains compounds that may be inaccessible to microbes due to their extremely low concentration (RDOC<sub>c</sub>). This differentiation allows us to appreciate the linkage between microbial source and RDOC composition on a range of temporal and spatial scales. <br><br> Analyses of biomarkers and isotopic records show intensive MCP processes in the Proterozoic oceans when the MCP could have played a significant role in regulating climate. Understanding the dynamics of the MCP in conjunction with the better constrained biological pump (BP) over geological timescales could help to predict future climate trends. Integration of the MCP and the BP will require new research approaches and opportunities. Major goals include understanding the interactions between particulate organic carbon (POC) and RDOC that contribute to sequestration efficiency, and the concurrent determination of the chemical composition of organic carbon, microbial community composition and enzymatic activity. Molecular biomarkers and isotopic tracers should be employed to link water column processes to sediment records, as well as to link present-day observations to paleo-evolution. Ecosystem models need to be developed based on empirical relationships derived from bioassay experiments and field investigations in order to predict the dynamics of carbon cycling along the stability continuum of POC and RDOC under potential global change scenarios. We propose that inorganic nutrient input to coastal waters may reduce the capacity for carbon sequestration as RDOC. The nutrient regime enabling maximum carbon storage from combined POC flux and RDOC formation should therefore be sought.

 References Allgaier, M., Riebesell, U., Vogt, M., Thyrhaug, R., and Grossart, H.-P.: Coupling of heterotrophic bacteria to phytoplankton bloom development at different <i>p</i>CO<sub>2</sub> levels: a mesocosm study, Biogeosciences, 5, 1007–1022, <a href="http://dx.doi.org/10.5194/bg-5-1007-2008">https://doi.org/10.5194/bg-5-1007-2008</a>, 2008. Alonso-González, I. J., Arístegui, J., Lee, C., and Calafat, A.: Regional and temporal variability of sinking organic matter in the subtropical northeast Atlantic Ocean: a biomarker diagnosis, Biogeosciences, 7, 2101–2115, <a href="http://dx.doi.org/10.5194/bg-7-2101-2010">https://doi.org/10.5194/bg-7-2101-2010</a>, 2010. Anderson, T. R. and Tang, K. W.: Carbon cycling and POC turnover in the mesopelagic zone of the ocean: Insights from a simple model, Deep-Sea Res. Pt. II., 57, 1581–1592, 2010. Arístegui, J. and Montero, M. F.: Temporal and spatial changes in plankton respiration and biomass in the Canary Islands region: the effect of mesoscale variability, J. Marine. Syst., 54, 65–82, 2005. Arístegui, J., Tett, P., Hernández-Guerra, A., Basterretxea, G., Montero, M. F., Wild, K., Sangrá, P., Hernández-León, S., Cantón, M., García-Braun, J. A., Pacheco, M., and Barton, E. D.: The influence of island-generated eddies on chlorophyll distribution: a study of mesoscale variation around Gran Canaria, Deep-Sea Res., 44, 71–96, 1997. Arístegui, J., Gasol, J. M., Duarte, C. M., and Herndl, G. J.: Microbial Oceanography of the dark ocean's pelagic realm, Limnol. Oceanogr., 54, 1501–1529, 2009. Arnosti, C.: Microbial Extracellular Enzymes and the Marine Carbon Cycle, Ann. Rev. Mar. Sci., 3, 401–425, 2011. Arnosti, C., Fuchs, B. M., Amann, R., and Passow, U.: Contrasting extracellular enzyme activities of particle-associated bacteria from distinct provinces of the North Atlantic Ocean, Front. Microbiol., 3, 425, <a href="http://dx.doi.org/10.3389/fmicb.2012.00425">https://doi.org/10.3389/fmicb.2012.00425</a>, 2012. Azam, F. and Malfatti, F.: Microbial structuring of marine ecosystems, Nat. Rev. Microbiol., 5, 782–791, 2007. Baldock, J. A., Masiello, C. A., Gelinas, Y., and Hedges, J. I.: Cycling and composition of organic matter in terrestrial and marine ecosystems, Mar. Chem., 92, 39–64, 2004. Baltar, F., Arístegui, J., Gasol, J. M., Hernández-León, S., and Herndl, G. J.: Strong coast – ocean and surface – depthgradients in prokaryotic assemblage structure and activity in a coastal transition zone region, Aquat. Microb. Ecol., 50, 63–74, 2007. Baltar, F., Arístegui, J., Gasol, J. M., Sintes, E., and Herndl, G. J.: Evidence of prokaryotic metabolism on suspended particulate organic matter in the dark waters of the subtropical North Atlantic, Limnol. Oceanogr., 54, 182–193, 2009. Baltar, F., Arístegui, J., Gasol, J. M., Lekunberri, I., and Herndl, G. J.: Mesoscale eddies: Hotspots of prokaryotic activity and differential community structure in the ocean, ISME J., 4, 975–988, 2010a. Baltar, F., Arístegui, J., Gasol, J. M., Sintes, E., van Aken, H. M., and Herndl, G. J.: High dissolved extracellular enzymatic activity in the deep central Atlantic Ocean, Aquat. Microb. Ecol., 58, 287–302, 2010b. Baltar, F., Palovaara, J., Vila-Costa, M., Calvo, E., Pelejero, C., Marrase, C., Salazar, G., Gasol, J. M., and Pinhassi, J.: Response of rare versus abundant bacterioplankton to disturbances in a Mediterranean coastal site, in 13th Symposium on Aquatic microbial Ecology, Stresa, Italy, 8–13 September 2013, 2013. Barber, R. T.: Dissolved organic carbon from deep waters resists microbial oxidation, Nature, 220, 274–275, 1968. Barker, S., Higgins, J. A., and Elderfield, H.: The future of the carbon cycle: review, calcification response, ballast and feedback on atmospheric CO<sub>2</sub>, Philos. Trans. A Math. Phys. Eng. Sci., 361, 1977–1999, 2003. Bauer, J. E., Williams, P. M., and Druffel, E. R. M.: <sup>14</sup>C activity of dissolved organic carbon fractions in the north-central Pacific and Sargasso Sea, Nature, 357, 667–670, 1992. Beauvais, S., Pedrotti, M. L., Egge, J., Iversen, K., and Marrasé, C.: Effects of turbulence on TEP dynamics under contrasting nutrient conditions: implications for aggregation and sedimentation processes, Mar. Ecol.-Prog. Ser., 323, 47–57, 2006. Béjà, O., Aravind, L., Koonin, E. V., Suzuki, M. T., Hadd, A., Nguyen, L. P., Jovanovich, S., Gates, C. M., Feldman, R. A., Spudich, J. L., Spudich, E. N., and DeLong, E. F.: Bacterial rhodopsin: Evidence for a new type of phototrophy in the sea, Science, 289, 1902–1906, 2000. Bhaskar, P. V. and Bhosle, N. B.: Microbial extracellular polymeric substances in marine biogeochemical processes, Curr. Sci. India, 88, 45–53, 2005. Bidigare, R. R., Chai, F., Landry, M. R., Lukas, R., Hannides, C. C. S., Christensen, S. J., Karl, D. M., Shi, L., and Chao, Y.: Subtropical ocean ecosystem structure changes forced by North Pacific climate variations, J. Plankton. Res., 31, 1131–1139, 2009. Blackford, J. C., Allen, J. I., and Gilbert, F. J.: Ecosystem dynamics at six contrasting sites: a generic modelling study, J. Marine. Syst., 52, 191–215, 2004. Bode, A., Barquero, S., Varela, M., Braun, J. A., and de Armas, D.: Pelagic bacteria and phytoplankton in oceanic waters near the Canary Islands in summer, Mar. Ecol.-Prog. Ser., 209, 1–17, 2001. Boyd, P. W. and Hutchins, D. A.: Understanding the responses of ocean biota to a complex matrix of cumulative anthropogenic change, Mar. Ecol.-Prog. Ser., 470, 125–135, 2012. Boyd, P. W., Jickells, T., Law, C. S., Blain, S., Boyle, E. A., Buesseler, K. O., Coale, K. H., Cullen, J. J., de Baar, H. J. W., Follows, M., Harvey, M., Lancelot, C., Levasseur, M., Owens, N. P. J., Pollard, R., Rivkin, R. B., Sarmiento, J., Schoemann, V., Smetacek, V., Takeda, S., Tsuda, A., Turner, S., and Watson, A. J.: Mesoscale iron enrichment experiments 1993–2005: Synthesis and future directions, Science, 315, 612–617, 2007. Breitburg, D. L., Baxter, J. W., Hatfield, C. A., Howarth, R. W., Jones, C. G., Lovett, G. M., and Wigand, C.: Understanding effects of multiple stressors: ideas and challenges, in: Successes, Limitations, and Frontiers in ecosystem science, edited by: Pace, M. L., and Groffman, P. M., Springer-Verlag New York, Inc., New York, 416–431, 1998. Brewin, R. J. W., Lavender, S. J., Hardman-Mountford, N. J., and Hirata, T.: A spectral response approach for detecting dominant phytoplankton size class from satellite remote sensing, Acta Oceanol. Sin., 29, 14–32, 2010a. Brewin, R. J. W., Sathyendranath, S., Hirata, T., Lavender, S. J., Barciela, R. M., and Hardman-Mountford, N. J.: A three-component model of phytoplankton size class for the Atlantic Ocean, Ecol. Model., 221, 1472–1483, 2010b. Brophy, J. E. and Carlson, D. J.: Production of biologically refractory dissolved organic carbon by natural seawater microbial populations, Deep-Sea. Res. Pt. I., 36, 497–507, 1989. Brussaard, C. P. D., Noordeloos, A. A. M., Witte, H., Collenteur, M. C. J., Schulz, K., Ludwig, A., and Riebesell, U.: Arctic microbial community dynamics influenced by elevated CO<sub>2</sub> levels, Biogeosciences, 10, 719–731, <a href="http://dx.doi.org/10.5194/bg-10-719-2013">https://doi.org/10.5194/bg-10-719-2013</a>, 2013. Calow, P.: Proximate and ultimate responses to stress in biological systems, Biol. J. Linn. Soc., 37, 173–181, 1989. Canfield, D. E. and Kump, L. R.: Geochemistry, Carbon cycle makeover, Science, 339, 533–534, 2013. Capotondi, A., Alexander, M. A., Bond, N. A., Curchitser, E. N., and Scott, J. D.: Enhanced upper ocean stratification with climate change in the CMIP3 models, J. Geophys. Res., 117, C04031, <a href="http://dx.doi.org/10.1029/2011jc007409">https://doi.org/10.1029/2011jc007409</a>, 2012. Carder, K. L., Steward, R. G., and Betzer, P. R.: In situ holographic measurements of the sizes and settling rates of oceanic particulates, J. Geophys. Res., 87, 5681–5685, 1982. Carlson, C. A., Giovannoni, S. J., Hansell, D. A., Goldberg, S. J., Parsons, R., Otero, M. P., Vergin, K., and Wheeler, B. R.: Effect of nutrient amendments on bacterioplankton production, community structure, and DOC utilization in the northwestern Sargasso Sea, Aquat. Microb. Ecol., 30, 19–36, 2002. Carlson, C. A., Giovannoni, S. J., Hansell, D. A., Goldberg, S. J., Parsons, R., and Vergin, K.: Interactions among dissolved organic carbon, microbial processes, and community structure in the mesopelagic zone of the northwestern Sargasso Sea, Limnol. Oceanogr., 49, 1073–1083, 2004. Carlson, C. A., Hansell, D. A., and Tamburini, C.: DOC Persistence and its Fate After Export Within the Ocean Interior, in: Microbial Carbon Pump in the Ocean, edited by: Jiao, N., Azam, F., and Sanders, S., Science/AAAS Business Office, Washington, DC, 57–59, 2011. Cheney, R. E. and Richardson, P. L.: Observed decay of a cyclonic Gulf Stream ring, Deep-Sea Res., 23, 143–155, 1976. Ciotti, A. M. and Bricaud, A.: Retrievals of a size parameter for phytoplankton and spectral light absorption by colored detrital matter from water-leaving radiances at SeaWiFS channels in a continental shelf region off Brazil, Limnol. Oceanogr.-Meth., 4, 237–253, 2006. Corzo, A., Morillo, J. A., and Rodríguez, S.: Production of transparent exopolymer particles (TEP) in cultures of Chaetoceros calcitrans under nitrogen limitation, Aquat. Microb. Ecol., 23, 63–72, 2000. Costerton, J. W., Lewandowski, Z., Caldwell, D. E., Korber, D. R., and Lappinscott, H. M.: Microbial Biofilms, Annu. Rev. Microbiol., 49, 711–745, 1995. Cottrell, M. T., Yu, L., and Kirchman, D. L.: Sequence and expression analyses of <i>Cytophaga</i>-like hydrolases in a western Arctic metagenomic library and the Sargasso Sea, Appl. Environ. Microbiol., 71, 8506–8513, 2005. Craig, S. E., Thomas, H., Jones, C. T., Li, W. K. W., Greenan, B. J. W., Shadwick, E. H., and Burt, W. J.: Temperature and phytoplankton cell size regulate carbon uptake and carbon overconsumption in the ocean, Biogeosciences Discuss., 10, 11255–11282, <a href="http://dx.doi.org/10.5194/bgd-10-11255-2013">https://doi.org/10.5194/bgd-10-11255-2013</a>, 2013. Dall'Olmo, G., Westberry, T. K., Behrenfeld, M. J., Boss, E., and Slade, W. H.: Significant contribution of large particles to optical backscattering in the open ocean, Biogeosciences, 6, 947–967, <a href="http://dx.doi.org/10.5194/bg-6-947-2009">https://doi.org/10.5194/bg-6-947-2009</a>, 2009. Dang, H. and Jiao, N.: Perspectives on the microbial carbon pump with special reference to microbial respiration and ecosystem efficiency in large estuarine systems, Biogeosciences, 11, 3887–3898, <a href="http://dx.doi.org/10.5194/bg-11-3887-2014">https://doi.org/10.5194/bg-11-3887-2014</a>, 2014. DeLong, E. F., Preston, C. M., Mincer, T., Rich, V., Hallam, S. J., Frigaard, N. U., Martinez, A., Sullivan, M. B., Edwards, R., Brito, B. R., Chisholm, S. W., and Karl, D. M.: Community genomics among stratified microbial assemblages in the ocean's interior, Science, 311, 496–503, 2006. Devred, E., Sathyendranath, S., Stuart, V., and Platt, T.: A three component classification of phytoplankton absorption spectra: Application to ocean-color data, Remote Sens. Environ., 115, 2255–2266, 2011. Doney, S. C.: Oceanography: Plankton in a warmer world, Nature, 444, 695–696, 2006. Doney, S. C., Fabry, V. J., Feely, R. A., and Kleypas, J. A.: Ocean acidification: the other CO<sub>2</sub> problem, Annu. Rev. Mar. Sci., 1, 169–192, 2009. Druffel, E. R. M. and Williams, P. M.: Identification of a deep marine source of particulate organic-carbon using bomb C-14, Nature, 347, 172–174, 1990. Egge, J. K., Thingstad, T. F., Larsen, A., Engel, A., Wohlers, J., Bellerby, R. G. J., and Riebesell, U.: Primary production during nutrient-induced blooms at elevated CO<sub>2</sub> concentrations, Biogeosciences, 6, 877–885, <a href="http://dx.doi.org/10.5194/bg-6-877-2009">https://doi.org/10.5194/bg-6-877-2009</a>, 2009. Emeis, K.-C., Beusekom, J. V., Callies, U., Ebinghaus, R., Kannen, A., Kraus, G., Kröncke, I., Lenhart, H., Lorkowski, I., Matthias, V., Möllmann, C., Pätsch, J., Scharfe, M., Thomas, H., Weisse, R., and Zorita, E.: The North Sea – a shelf sea in the anthropocene, J. Marine Syst., IMBIZO special issue, <a href="http://dx.doi.org/10.1016/j.jmarsys.2014.03.012">https://doi.org/10.1016/j.jmarsys.2014.03.012</a>, in press, 2014. Engel, A.: Direct relationship between CO<sub>2</sub> uptake and transparent exopolymer particles production in natural phytoplankton, J. Plankton. Res., 24, 49–53, 2002. Engel, A., Delille, B., Jacquet, S., Riebesell, U., Rochelle-Newall, E., Terbrüggen, A., and Zondervan, I.: Transparent exopolymer particles and dissolved organic carbon production by <i>Emiliania huxleyi</i> exposed to different CO<sub>2</sub> concentrations: a mesocosm experiment, Aquat. Microb. Ecol., 34, 93–104, 2004a. Engel, A., Thoms, S., Riebesell, U., Rochelle-Newall, E., and Zondervan, I.: Polysaccharide aggregation as a potential sink of marine dissolved organic carbon, Nature, 428, 929–932, 2004b. Falkowski, P. G., Ziemann, D. A., Kolber, D. A., and Bienfang, P. K.: Role of eddy pumping in enhancing primary production in the ocean, Nature, 352, 55–58, 1991. Fike, D. A., Grotzinger, J. P., Pratt, L. M., and Summons, R. E.: Oxidation of the Ediacaran ocean, Nature, 444, 744–747, 2006. Flerus, R., Lechtenfeld, O. J., Koch, B. P., McCallister, S. L., Schmitt-Kopplin, P., Benner, R., Kaiser, K., and Kattner, G.: A molecular perspective on the ageing of marine dissolved organic matter, Biogeosciences, 9, 1935–1955, <a href="http://dx.doi.org/10.5194/bg-9-1935-2012">https://doi.org/10.5194/bg-9-1935-2012</a>, 2012. Flynn, K. J.: Incorporating plankton respiration in models of aquatic ecosystem function, in: Respiration in Aquatic Ecosystems, edited by: Giorgio, P. A. D. and Williams, P. J. L. B., Oxford University Press, 2005. Flynn, K. J., Clark, D. R., and Xue, Y.: Modeling the release of dissolved organic matter by phytoplankton, J. Phycol., 44, 1171–1187, 2008. Friedrichs, M. A. M., Dusenberry, J. A., Anderson, L. A., Armstrong, R. A., Chai, F., Christian, J. R., Doney, S. C., Dunne, J., Fujii, M., Hood, R., McGillicuddy, D. J., Moore, J. K., Schartau, M., Spitz, Y. H., and Wiggert, J. D.: Assessment of skill and portability in regional marine biogeochemical models: Role of multiple planktonic groups, J. Geophys. Res., 112, C08001, <a href="http://dx.doi.org/10.1029/2006jc003852">https://doi.org/10.1029/2006jc003852</a>, 2007. Fu, F. X., Warner, M. E., Zhang, Y., Feng, Y., and Hutchins, D. A.: Effects of increased temperature and CO<sub>2</sub> on photosynthesis, growth, and elemental ratios in marine <i>Synechococcus</i> and <i>Prochlorococcus</i> (Cyanobacteria), J. Phycol., 43, 485–496, 2007. Fuhrman, J. A.: Close Coupling between Release and Uptake of Dissolved Free Amino-Acids in Seawater Studied by an Isotope-Dilution Approach, Mar. Ecol.-Prog. Ser., 37, 45–52, 1987. Gardner, W. D., Mishonov, A., and Richardson, M. J.: Global POC concentrations from in-situ and satellite data, Deep-Sea Res. Pt. II., 53, 718–740, 2006. Gasol, J. M., Vázquez-Domínguez, E., Vaqué, D., Agustí, S., and Duarte, C. M.: Bacterial activity and diffusive nutrient supply in the oligotrophic Central Atlantic Ocean, Aquat. Microb. Ecol., 56, 1–12, 2009. Gonsior, M., Peake, B. M., Cooper, W. T., Podgorski, D., D'Andrilli, J., and Cooper, W. J.: Photochemically Induced Changes in Dissolved Organic Matter Identified by Ultrahigh Resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry, Environ. Sci. Technol., 43, 698–703, 2009. Grimsditch, G., Alder, J., Nakamura, T., Kenchington, R., and Tamelander, J.: The blue carbon special edition – Introduction and overview, Ocean. Coast. Manage., 83, 1–4, 2013. Grossart, H. P., Allgaier, M., Passow, U., and Riebesell, U.: Testing the effect of CO<sub>2</sub> concentration on the dynamics of marine heterotrophic bacterioplankton, Limnol. Oceanogr., 51, 1–11, 2006. Grotzinger, J. P., Fike, D. A., and Fischer, W. W.: Enigmatic origin of the largest-known carbon isotope excursion in Earth's history, Nat. Geosci., 4, 285–292, 2011. Gruber, D. F., Simjouw, J. P., Seitzinger, S. P., and Taghon, G. L.: Dynamics and characterization of refractory dissolved organic matter produced by a pure bacterial culture in an experimental predator-prey system, Appl. Environ. Microb., 72, 4184–4191, 2006. Hansell, D. A.: Recalcitrant Dissolved Organic Carbon Fractions, Annu. Rev. Mar. Sci., 5, 421–445, 2013. Hansell, D. A., Carlson, C. A., Repeta, D. J., and Schlitzer, R.: Dissolved organic matter in the ocean – A controversy stimulates new insights, Oceanography, 22, 202–211, 2009. Hansell, D. A., Carlson, C. A., and Schlitzer, R.: Net removal of major marine dissolved organic carbon fractions in the subsurface ocean, Global. Biogeochem. Cy., 26, GB1016, <a href="http://dx.doi.org/10.1029/2011gb004069">https://doi.org/10.1029/2011gb004069</a>, 2012. Hansman, R. L., Griffin, S., Watson, J. T., Druffel, E. R. M., and Ingalls, A. E.: The radiocarbon signature of microorganisms in the mesopelagic ocean, P. Natl. Acad. Sci. USA, 106, 6513–6518, 2009. Harris, R. P., Boyd, P., Harbour, D. S., Head, R. N., Pingree, R. D., and Pomroy, A. J.: Physical, chemical and biological features of a cyclonic eddy in the region of 61° 10´N 19° 50´W in the North Atlantic., Deep-Sea Res. Pt. I, 11, 1815–1839, 1997. Hartmann, M., Grob, C., Tarran, G. A., Martin, A. P., Burkill, P. H., Scanlan, D. J., and Zubkov, M. V.: Mixotrophic basis of Atlantic oligotrophic ecosystems, P. Natl. Acad. Sci. USA, 109, 5756–5760, 2012. Hays, G. C., Richardson A. J., and Robinson C. Climate change and marine plankton, Trend. Ecol. Evol., 20, 337–244, 2005 Hedges, I. J. and Keil, R. G.: Sedimentary organic matter preservation: an assessment and speculative synthesis, Mar. Chem., 49, 81–115, 1995. Henson, S. A., Sanders, R., and Madsen, E.: Global patterns in efficiency of particulate organic carbon export and transfer to the deep ocean, Global. Biogeochem. Cy., 26, GB1028, <a href="http://dx.doi.org/10.1029/2011gb004099">https://doi.org/10.1029/2011gb004099</a>, 2012. Hertkorn, N., Benner, R., Frommberger, M., Schmitt-Kopplin, P., Witt, M., Kaiser, K., Kettrup, A., and Hedges, J. I.: Characterization of a major refractory component of marine dissolved organic matter, Geochim. Cosmochim. Ac., 70, 2990–3010, 2006. Hinder, S. L., Manning, J. E., Gravenor, M. B., Edwards, M., Walne, A. W., Burkill, P. H., and Hays, G. C.: Long-term changes in abundance and distribution of microzooplankton in the NE Atlantic and North Sea, J. Plankton. Res., 34, 83–91, 2012. Hirata, T., Aiken, J., Hardman-Mountford, N., Smyth, T. J., and Barlow, R. G.: An absorption model to determine phytoplankton size classes from satellite ocean colour, Remote Sens. Environ., 112, 3153–3159, 2008a. Hirata, T., Hardman-Mountford, N. J., Aiken, J., Martinez-Vicente, V., Fishwick, J., and Bernard, S.: Particle size distribution determined from ocean colour as a descriptor of nano/micro phytoplankton community in the oceans, in Proceedings of the Remote Sensing and Photogrammetry Society Conference 2008, University of Exeter, Falmouth, UK, 15–17 September 2008, 155–156, 2008b. Hirata, T., Hardman-Mountford, N. J., Brewin, R. J. W., Aiken, J., Barlow, R., Suzuki, K., Isada, T., Howell, E., Hashioka, T., Noguchi-Aita, M., and Yamanaka, Y.: Synoptic relationships between surface Chlorophyll-<i>a</i> and diagnostic pigments specific to phytoplankton functional types, Biogeosciences, 8, 311–327, <a href="http://dx.doi.org/10.5194/bg-8-311-2011">https://doi.org/10.5194/bg-8-311-2011</a>, 2011. Honjo, S., Manganini, S. J., Krishfield, R. A., and Francois, R.: Particulate organic carbon fluxes to the ocean interior and factors controlling the biological pump: A synthesis of global sediment trap programs since 1983, Prog. Oceanogr., 76, 217–285, 2008. Hoppe, H.-G., Breithaupt, P., Walther, K., Koppe, R., Bleck, S., Sommer, U., and Jürgens, K.: Climate warming in winter affects the coupling between phytoplankton and bacteria during the spring bloom: a mesocosm study, Aquat. Microb. Ecol., 51, 105–115, 2008. Hwang, J. and Druffel, E. R.: Lipid-like material as the source of the uncharacterized organic carbon in the ocean?, Science, 299, 881–884, 2003. Ingalls, A. E., Shah, S. R., Hansman, R. L., Aluwihare, L. I., Santos, G. M., Druffel, E. R. M., and Pearson, A.: Quantifying archaeal community autotrophy in the mesopelagic ocean using natural radiocarbon, P. Natl. Acad. Sci. USA, 103, 6442–6447, 2006. IPCC: Climate Change 2013: The Physical Science Basis. Working Group I Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Stocker, T. F., Qin, D., Plattner, G., Tignor, M., Allen, S. K., Boschung, J., Nauel, A., Xia, Y., Bex, V., and Midgley, P. M., Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp., 2013. Jannasch, H. W.: The Microbial Turnover of Carbon in the Deep-Sea Environment, in: Direct Ocean Disposal of Carbon Dioxide, edited by: Handa, N. and Ohsumi, T., Terra Scientific Publishing Company (TERRAPUB), Tokyo, 1–11, 1995. Jiang, H. B., Kong, R. Q., and Xu, X. D.: The N-Acetylmuramic Acid 6-Phosphate Etherase Gene Promotes Growth and Cell Differentiation of Cyanobacteria under Light-Limiting Conditions, J. Bacteriol., 192, 2239–2245, 2010. Jiao, N. and Zheng, Q.: The microbial carbon pump: from genes to ecosystems, Appl. Environ. Microbiol., 77, 7439–7444, 2011. Jiao, N., Herndl, G. J., Hansell, D. A., Benner, R., Kattner, G., Wilhelm, S. W., Kirchman, D. L., Weinbauer, M. G., Luo, T., Chen, F., and Azam, F.: Microbial production of recalcitrant dissolved organic matter: long-term carbon storage in the global ocean, Nat. Rev. Microbiol., 8, 593–599, 2010a. Jiao, N., Tang, K., Cai, H., and Mao, Y.: Increasing the microbial carbon sink in the sea by reducing chemical fertilization on the land, Nat. Rev. Microbiol., 9, 75–75, <a href="http://dx.doi.org/10.1038/nrmicro2386-c2">https://doi.org/10.1038/nrmicro2386-c2</a>, 2010b. Jiao, N., Herndl, G. J., Hansell, D. A., Benner, R., Kattner, G., Wilhelm, S. W., Kirchman, D. L., Weinbauer, M. G., Luo, T., Chen, F., and Azam, F.: The microbial carbon pump and the oceanic recalcitrant dissolved organic matter pool, Nat. Rev. Microbiol., 9, 555–555, <a href="http://dx.doi.org/10.1038/nrmicro2386-c5">https://doi.org/10.1038/nrmicro2386-c5</a>, 2011. Jiao, N., Luo, T., Zhang, R., Yan, W., Lin, Y., Johnson, Z. I., Tian, J., Yuan, D., Yang, Q., Zheng, Q., Sun, J., Hu, D., and Wang, P.: Presence of <i>Prochlorococcus</i> in the aphotic waters of the western Pacific Ocean, Biogeosciences, 11, 2391–2400, <a href="http://dx.doi.org/10.5194/bg-11-2391-2014">https://doi.org/10.5194/bg-11-2391-2014</a>, 2014. Johnson, K. S., Berelson, W. M., Boss, E. S., Chase, Z., Claustre, H., Emerson, S. R., Gruber, N., Kortzinger, A., Perry, M. J., and Riser, S. C.: Observing Biogeochemical Cycles at Global Scales with Profiling Floats and Gliders Prospects for a Global Array, Oceanography, 22, 216–225, 2009. Johnson, M. T., Greenwood, N., Sivyer, D. B., Thomson, M., Reeve, A., Weston, K., and Jickells, T. D.: Characterising the seasonal cycle of dissolved organic nitrogen using Cefas SmartBuoy high-resolution time-series samples from the southern North Sea, Biogeochemistry, 113, 23–36, 2013. Jørgensen, N. O. G. and Middelboe, M.: Occurrence and bacterial cycling of D amino acid isomers in an estuarine environment, Biogeochemistry, 81, 77–94, 2006. Kadouri, D., Jurkevitch, E., Okon, Y., and Castro-Sowinski, S.: Ecological and agricultural significance of bacterial polyhydroxyalkanoates, Crit. Rev. Microbiol., 31, 55–67, 2005. Kattner, G., Simon, M., and Koch, B.: Molecular characterization of dissolved organic matter and constraints for prokaryotic utilization, in: Microbial Carbon Pump in the Ocean, edited by: Jiao, N., Azam, F., and Sanders, S., Science/AAAS, Washington DC, 60–61, 2011. Kieber, R. J., Zhou, X. L., and Mopper, K.: Formation of Carbonyl-Compounds from UV-Induced Photodegradation of Humic Substances in Natural-Waters – Fate of Riverine Carbon in the Sea, Limnol. Oceanogr., 35, 1503–1515, 1990. Kim, J. M., Lee, K., Shin, K., Yang, E. J., Engel, A., Karl, D. M., and Kim, H. C.: Shifts in biogenic carbon flow from particulate to dissolved forms under high carbon dioxide and warm ocean conditions, Geophys. Res. Lett., 38, L08612, <a href="http://dx.doi.org/10.1029/2011gl047346">https://doi.org/10.1029/2011gl047346</a>, 2011. Kiorboe, T. and Jackson, G. A.: Marine snow, organic solute plumes, and optimal chemosensory behavior of bacteria, Limnol. Oceanogr., 46, 1309–1318, 2001. Kirchman, D. L.: Processes in Microbial Ecology, Oxford University Press, Oxford, 312 pp., 2012. Koch, B. P., Witt, M., Engbrodt, R., Dittmar, T., and Kattner, G.: Molecular formulae of marine and terrigenous dissolved organic matter detected by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, Geochim. Cosmochim. Ac., 69, 3299–3308, 2005. Koch, B. P., Kattner, G., Witt, M., and Passow, U.: Molecular insights into the microbial formation of marine dissolved organic matter: recalcitrant or labile?, Biogeosciences, 11, 4173–4190, <a href="http://dx.doi.org/10.5194/bg-11-4173-2014">https://doi.org/10.5194/bg-11-4173-2014</a>, 2014. Koonin, E. V. and Wolf, Y. I.: Genomics of bacteria and archaea: the emerging dynamic view of the prokaryotic world, Nucleic. Acids. Res., 36, 6688–6719, 2008. Kostadinov, T. S., Siegel, D. A., and Maritorena, S.: Retrieval of the particle size distribution from satellite ocean color observations, J. Geophys. Res., 114, C09015, <a href="http://dx.doi.org/10.1029/2009jc005303">https://doi.org/10.1029/2009jc005303</a>, 2009. Kostadinov, T. S., Siegel, D. A., and Maritorena, S.: Global variability of phytoplankton functional types from space: assessment via the particle size distribution, Biogeosciences, 7, 3239–3257, <a href="http://dx.doi.org/10.5194/bg-7-3239-2010">https://doi.org/10.5194/bg-7-3239-2010</a>, 2010. Kriest, I., Khatiwala, S., and Oschlies, A.: Towards an assessment of simple global marine biogeochemical models of different complexity, Prog. Oceanogr., 86, 337–360, 2010. Kujawinski, E. B.: The Impact of Microbial Metabolism on Marine Dissolved Organic Matter, Annu. Rev. Mar. Sci., 3, 567–599, 2011. Kujawinski, E. B., Del Vecchio, R., Blough, N. V., Klein, G. C., and Marshall, A. G.: Probing molecular-level transformations of dissolved organic matter: insights on photochemical degradation and protozoan modification of DOM from electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, Mar. Chem., 92, 23–37, 2004. Lampitt, R. S., Achterberg, E. P., Anderson, T. R., Hughes, J. A., Iglesias-Rodriguez, M. D., Kelly-Gerreyn, B. A., Lucas, M., Popova, E. E., Sanders, R., Shepherd, J. G., Smythe-Wright, D., and Yool, A.: Ocean fertilization: a potential means of geoengineering?, Philos. Trans. R. Soc. London A, 366, 3919–3945, 2008. Lauro, F. M., McDougald, D., Thomas, T., Williams, T. J., Egan, S., Rice, S., DeMaere, M. Z., Ting, L., Ertan, H., Johnson, J., Ferriera, S., Lapidus, A., Anderson, I., Kyrpides, N., Munk, A. C., Detter, C., Han, C. S., Brown, M. V., Robb, F. T., Kjelleberg, S., and Cavicchioli, R.: The genomic basis of trophic strategy in marine bacteria, P. Natl. Acad. Sci. USA, 106, 15527–15533, 2009. Le Quere, C., Harrison, S. P., Prentice, I. C., Buitenhuis, E. T., Aumont, O., Bopp, L., Claustre, H., Da Cunha, L. C., Geider, R., Giraud, X., Klaas, C., Kohfeld, K. E., Legendre, L., Manizza, M., Platt, T., Rivkin, R. B., Sathyendranath, S., Uitz, J., Watson, A. J., and Wolf-Gladrow, D.: Ecosystem dynamics based on plankton functional types for global ocean biogeochemistry models, Glob. Change. Biol., 11, 2016–2040, 2005. Lechtenfeld, O. J., Kattner, G., Flerus, R., McCallister, S. L., Schmitt-Kopplin, P., and Koch, B. P.: Molecular transformation and degradation of refractory dissolved organic matter in the Atlantic and Southern Ocean, Geochim. Cosmochim. Ac., 126, 321–337, 2014. Legendre, L. and Le Fèvre, J.: From individual plankton cells to pelagic marine ecosystems and to global biogeochemical cycles, in: Particle analysis in oceanography, edited by: Demers, S., Springer-Verlag, Berlin, 261–300, 1991. Legendre, L. and Le Fèvre, J.: Microbial Food Webs and the Export of Biogenic Carbon in Oceans, Aquat. Microb. Ecol., 9, 69–77, 1995. Legendre, L. and Rassoulzadegan, F.: Food-web mediated export of biogenic carbon in oceans: Hydrodynamic control, Mar. Ecol.-Prog. Ser., 145, 179–193, 1996. Li, C., Love, G. D., Lyons, T. W., Fike, D. A., Sessions, A. L., and Chu, X. L.: A Stratified Redox Model for the Ediacaran Ocean, Science, 328, 80–83, 2010. Lindh, M. V., Riemann, L., Baltar, F., Romero-Oliva, C., Salomon, P. S., Granéli, E., and Pinhassi, J.: Consequences of increased temperature and acidification on bacterioplankton community composition during a mesocosm spring bloom in the Baltic Sea, Environ. Microbiol. Rep., 5, 252–262, 2012. Lipp, J. S., Morono, Y., Inagaki, F., and Hinrichs, K. U.: Significant contribution of Archaea to extant biomass in marine subsurface sediments, Nature, 454, 991–994, 2008. Liu, J., Jiao, N., and Tang, K.: An experimental study on the effects of nutrient enrichment on organic carbon persistence in the western Pacific oligotrophic gyre, Biogeosciences, 11, 5115–5122, <a href="http://dx.doi.org/10.5194/bg-11-5115-2014">https://doi.org/10.5194/bg-11-5115-2014</a>, 2014. Liu, Y., Yao, T., Jiao, N., Tian, L., Hu, A., Yu, W., and Li, S.: Microbial diversity in the snow, a moraine lake and a stream in Himalayan glacier, Extremophiles, 15, 411–421, 2011. Logan, G. A., Hayes, J. M., Hieshima, G. B., and Summons, R. E.: Terminal Proterozoic Reorganization of Biogeochemical Cycles, Nature, 376, 53–56, 1995. Loisel, H., Nicolas, J. M., Deschamps, P. Y., and Frouin, R.: Seasonal and inter-annual variability of particulate organic matter in the global ocean, Geophys. Res. Lett., 29, 2196, <a href="http://dx.doi.org/10.1029/2002gl015948">https://doi.org/10.1029/2002gl015948</a>, 2002. Loucaides, S., Tyrrell, T., Achterberg, E. P., Torres, R., Nightingale, P. D., Kitidis, V., Serret, P., Woodward, M., and Robinson, C.: Biological and physical forcing of carbonate chemistry in an upwelling filament off northwest Africa: Results from a Lagrangian study, Global. Biogeochem. Cy., 26, GB3008, <a href="http://dx.doi.org/10.1029/2011gb004216">https://doi.org/10.1029/2011gb004216</a>, 2012. Luisetti, T., Turner, R. K., Bateman, I. J., Morse-Jones, S., Adams, C., and Fonseca, L.: Coastal and marine ecosystem services valuation for policy and management: Managed realignment case studies in England, Ocean. Coast. Manage., 54, 212–224, 2011. Luo, Y. W., Friedrichs, M. A. M., Doney, S. C., Church, M. J., and Ducklow, H. W.: Oceanic heterotrophic bacterial nutrition by semilabile DOM as revealed by data assimilative modeling, Aquat. Microb. Ecol., 60, 273–287, 2010. Maiti, K., Benitez-Nelson, C. R., Rii, Y., and Bidigare, R.: The influence of a mature cyclonic eddy on particle export in the lee of Hawaii, Deep-Sea Res. Pt II, 55, 1445–1460, 2008. Mannino, A., Russ, M. E., and Hooker, S. B.: Algorithm development and validation for satellite-derived distributions of DOC and CDOM in the US Middle Atlantic Bight, J. Geophys. Res., 113, C07051, <a href="http://dx.doi.org/10.1029/2007jc004493">https://doi.org/10.1029/2007jc004493</a>, 2008. Marchant, H. J. and Scott, F. J.: Uptake of sub-micrometre particles and dissolved organic material by Antarctic choanoflagellates, Mar. Ecol.-Prog. Ser., 92, 59–64, 1993. Mari, X.: Does ocean acidification induce an upward flux of marine aggregates?, Biogeosciences, 5, 1023–1031, <a href="http://dx.doi.org/10.5194/bg-5-1023-2008">https://doi.org/10.5194/bg-5-1023-2008</a>, 2008. Maritorena, S. and Siegel, D. A.: Consistent merging of satellite ocean color data sets using a bio-optical model, Remote Sens. Environ., 94, 429–440, 2005. McFadden, K. A., Huang, J., Chu, X., Jiang, G., Kaufman, A. J., Zhou, C., Yuan, X., and Xiao, S.: Pulsed oxidation and biological evolution in the Ediacaran Doushantuo Formation, P. Natl. Acad. Sci. USA, 105, 3197–3202, 2008. McGillicuddy Jr., D. J., Robinson, A. R., Siegel, D. A., Jannasch, H. W., Johnson, R., Dickey, T. D., McNeil, J., Michaels, A. F., and Knap, A. H.: Influence of mesoscale eddies on new production in the Sargasso Sea, Nature, 394, 263–266, 1998. McNichol, A. P. and Aluwihare, L. I.: The power of radiocarbon in biogeochemical studies of the marine carbon cycle: insights from studies of dissolved and particulate organic carbon (DOC and POC), Chem. Rev., 107, 443–466, 2007. Mitra, A., Flynn, K. J., Burkholder, J. M., Berge, T., Calbet, A., Raven, J. A., Granéli, E., Glibert, P. M., Hansen, P. J., Stoecker, D. K., Thingstad, F., Tillmann, U., Våge, S., Wilken, S., and Zubkov, M. V.: The role of mixotrophic protists in the biological carbon pump, Biogeosciences, 11, 995–1005, <a href="http://dx.doi.org/10.5194/bg-11-995-2014">https://doi.org/10.5194/bg-11-995-2014</a>, 2014. Moore, T. S., Mullaugh, K. M., Holyoke, R. R., Madison, A. S., Yucel, M., and Luther, G. W.: Marine Chemical Technology and Sensors for Marine Waters: Potentials and Limits, Annu. Rev. Mar. Sci., 1, 91–115, 2009. Moran, M. A.: Genomics and metagenomics of marine prokaryotes, in: Microbial Ecology of the Oceans, edited by: Kirchman, D. L., John Wiley and Sons, Inc., Hoboken, New Jersey, 91–129, 2008. Moran, X. A. G., Taupier-Letage, I., Vazquez-Dominguez, E., Ruiz, S., Arin, L., Raimbault, P., and Estrada, M.: Physical-biological coupling in the Algerian Basin (SW Mediterranean): Influence of mesoscale instabilities on the biomass and production of phytoplankton and bacterioplankton, Deep-Sea Res. Pt. I, 48, 405–437, 2001. Morel, A. and Gentili, B.: A simple band ration technique to quantify the colored dissolved and detrital organic material from ocean color remotely sensed data, Remote Sens. Environ., 113, 998–1011, 2009. Motegi, C., Tanaka, T., Piontek, J., Brussaard, C. P. D., Gattuso, J.-P., and Weinbauer, M. G.: Effect of CO<sub>2</sub> enrichment on bacterial metabolism in an Arctic fjord, Biogeosciences, 10, 3285–3296, <a href="http://dx.doi.org/10.5194/bg-10-3285-2013">https://doi.org/10.5194/bg-10-3285-2013</a>, 2013. Müren, U., Berglund, J., Samuelsson, K., and Andersson, A.: Potential effects of elevated sea-water temperature on pelagic food webs, Hydrobiologia, 545, 153–166, 2005. Newbold, L. K., Oliver, A. E., Booth, T., Tiwari, B., DeSantis, T., Maguire, M., Andersen, G., van der Gast, C. J., and Whiteley, A. S.: The response of marine picoplankton to ocean acidification, Environ. Microbiol., 14, 2293–2307, 2012. Ogawa, H., Amagai, Y., Koike, I., Kaiser, K., and Benner, R.: Production of refractory dissolved organic matter by bacteria, Science, 292, 917–920, 2001. Parekh, P., Dutkiewicz, S., Follows, M. J., and Ito, T.: Atmospheric carbon dioxide in a less dusty world, Geophys. Res. Lett., 33, L03610, <a href="http://dx.doi.org/10.1029/2005gl025098">https://doi.org/10.1029/2005gl025098</a>, 2006. Park, J. T. and Uehara, T.: How bacteria consume their own exoskeletons (Turnover and recycling of cell wall peptidoglycan), Microbiol. Mol. Biol. R, 72, 211–227, 2008. Passow, U.: Production of transparent exopolymer particles (TEP) by phyto-and bacterioplankton, Mar. Ecol.-Prog. Ser., 236, 1–12, 2002. Passow, U.: The abiotic formation of TEP under different ocean acidification scenarios, Mar. Chem., 128, 72–80, 2012. Passow, U. and Carlson, C. A.: The biological pump in a high CO<sub>2</sub> world, Mar. Ecol.-Prog. Ser., 470, 249–271, 2012. Paulino, A. I., Egge, J. K., and Larsen, A.: Effects of increased atmospheric CO<sub>2</sub> on small and intermediate sized osmotrophs during a nutrient induced phytoplankton bloom, Biogeosciences, 5, 739–748, <a href="http://dx.doi.org/10.5194/bg-5-739-2008">https://doi.org/10.5194/bg-5-739-2008</a>, 2008. Pedrotti, M. L., Fiorini, S., Kerros, M. E., Middelburg, J. J., and Gattuso, J. P.: Variable production of transparent exopolymeric particles by haploid and diploid life stages of coccolithophores grown under different CO<sub>2</sub> concentrations, J. Plankton. Res., 34, 388–398, 2012. Piontek, J., Lunau, M., Händel, N., Borchard, C., Wurst, M., and Engel, A.: Acidification increases microbial polysaccharide degradation in the ocean, Biogeosciences, 7, 1615–1624, <a href="http://dx.doi.org/10.5194/bg-7-1615-2010">https://doi.org/10.5194/bg-7-1615-2010</a>, 2010. Piontek, J., Borchard, C., Sperling, M., Schulz, K. G., Riebesell, U., and Engel, A.: Response of bacterioplankton activity in an Arctic fjord system to elevated <i>p</i>CO<sub>2</sub>: results from a mesocosm perturbation study, Biogeosciences, 10, 297–314, <a href="http://dx.doi.org/10.5194/bg-10-297-2013">https://doi.org/10.5194/bg-10-297-2013</a>, 2013. Polimene, L., Allen, J. I., and Zavatarelli, M.: Model of interactions between dissolved organic carbon and bacteria in marine systems, Aquat. Microb. Ecol., 43, 127–138, 2006. Poretsky, R. S., Sun, S., Mou, X., and Moran, M. A.: Transporter genes expressed by coastal bacterioplankton in response to dissolved organic carbon, Environ. Microbiol., 12, 616–627, 2010. Prentice, I. C., Farquhar, G. D., Fasham, M. J. R., Goulden, M. L., Heimann, M., Jaramillo, V. J., Kheshgi, H. S., LeQuéré, C., Scholes, R. J., and Wallace, D. W. R.: The Carbon Cycle and Atmospheric Carbon Dioxide, in: Climate Change 2001: the Scientific Basis. Contributions of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Houghton, J. T., Ding, Y., Griggs, D. J., Noguer, M., van der Linden, P. J., Dai, X., Maskell, K., and Johnson, C. A., Cambridge University Press, Cambridge, UK, 185–237, 2001. Prowe, A. E. F., Thomas, H., Patsch, J., Kuhn, W., Bozec, Y., Schiettecatte, L. S., Borges, A. V., and de Baar, H. J. W.: Mechanisms controlling the air-sea CO<sub>2</sub> flux in the North Sea, Cont. Shelf. Res., 29, 1801–1808, 2009. Riebesell, U. and Tortell, P. D.: Effects of ocean acidification on pelagic organisms and ecosystems, in: Ocean Acidification, edited by: Gattuso, J. and Hanson, L., Oxford University Press, Oxford, 99–121, 2011. Riebesell, U., Czerny, J., von Bröckel, K., Boxhammer, T., Büdenbender, J., Deckelnick, M., Fischer, M., Hoffmann, D., Krug, S. A., Lentz, U., Ludwig, A., Muche, R., and Schulz, K. G.: Technical Note: A mobile sea-going mesocosm system – new opportunities for ocean change research, Biogeosciences, 10, 1835–1847, <a href="http://dx.doi.org/10.5194/bg-10-1835-2013">https://doi.org/10.5194/bg-10-1835-2013</a>, 2013. Riemann, L. and Azam, F.: Widespread N-acetyl-D-glucosamine uptake among pelagic marine bacteria and its ecological implications, Appl. Environ. Microb., 68, 5554–5562, 2002. Robinson, C., Poulton, A. J., Holligan, P. M., Baker, A. R., Forster, G., Gist, N., Jickells, T. D., Malin, G., Upstill-Goddard, R., Williams, R. G., Woodward, E. M. S., and Zubkov, M. V.: The Atlantic Meridional Transect (AMT) Programme: A contextual view 1995–2005, Deep-Sea Res. Pt. II, 53, 1485–1515, 2006. Rochelle-Newall, E., Delille, B., Frankignoulle, M., Gattuso, J. P., Jacquet, S., Riebesell, U., Terbrüggen, A., and Zondervan, I.: Chromophoric dissolved organic matter in experimental mesocosms maintained under different <i>p</i>CO<sub>2</sub> levels, Mar. Ecol.-Prog. Ser., 272, 25–31, 2004. Roland, L. A., McCarthy, M. D., and Guilderson, T.: Sources of molecularly uncharacterized organic carbon in sinking particles from three ocean basins: A coupled Δ<sup>14</sup>C and δ<sup>13</sup>C approach, Mar. Chem., 111, 199–213, 2008. Romanou, A., Romanski, J., and Gregg, W. W.: Natural ocean carbon cycle sensitivity to parameterizations of the recycling in a climate model, Biogeosciences, 11, 1137–1154, <a href="http://dx.doi.org/10.5194/bg-11-1137-2014">https://doi.org/10.5194/bg-11-1137-2014</a>, 2014. Rothman, D. H., Hayes, J. M., and Summons, R. E.: Dynamics of the Neoproterozoic carbon cycle, P. Natl. Acad. Sci. USA, 100, 8124–8129, 2003. Sathyendranath, S., Stuart, V., Nair, A., Oka, K., Nakane, T., Bouman, H., Forget, M. H., Maass, H., and Platt, T.: Carbon-to-chlorophyll ratio and growth rate of phytoplankton in the sea, Mar. Ecol.-Prog. Ser., 383, 73–84, 2009. Schrag, D. P., Higgins, J. A., Macdonald, F. A., and Johnston, D. T.: Authigenic carbonate and the history of the global carbon cycle, Science, 339, 540–543, 2013. Schulz, K. G., Riebesell, U., Bellerby, R. G. J., Biswas, H., Meyerhöfer, M., Müller, M. N., Egge, J. K., Nejstgaard, J. C., Neill, C., Wohlers, J., and Zöllner, E.: Build-up and decline of organic matter during PeECE III, Biogeosciences, 5, 707–718, <a href="http://dx.doi.org/10.5194/bg-5-707-2008">https://doi.org/10.5194/bg-5-707-2008</a>, 2008. Sherr, E. B.: Direct Use of High Molecular-Weight Polysaccharide by Heterotrophic Flagellates, Nature, 335, 348–351, 1988. Siegel, D. A., Maritorena, S., Nelson, N. B., Hansell, D. A., and Lorenzi-Kayser, M.: Global distribution and dynamics of colored dissolved and detrital organic materials, J. Geophys. Res., 107, 3228, <a href="http://dx.doi.org/10.1029/2001jc000965">https://doi.org/10.1029/2001jc000965</a>, 2002. Siegel, D. A., Maritorena, S., Nelson, N. B., Behrenfeld, M. J., and McClain, C. R.: Colored dissolved organic matter and its influence on the satellite-based characterization of the ocean biosphere, Geophys. Res. Lett., 32, L20605, <a href="http://dx.doi.org/10.1029/2005gl024310">https://doi.org/10.1029/2005gl024310</a>, 2005. Staats, N., Stal, L. J., and Mur, L. R.: Exopolysaccharide production by the epipelic diatom <i>Cylindrotheca closterium</i>: effects of nutrient conditions, J. Exp. Mar. Biol. Ecol., 249, 13–27, 2000. Stocker, R.: Marine microbes see a sea of gradients, Science, 338, 628–633, 2012. Stramska, M.: Particulate organic carbon in the global ocean derived from SeaWiFS ocean color, Deep-Sea Res. Pt. I, 56, 1459–1470, 2009. Stramski, D., Reynolds, R. A., Kahru, M., and Mitchell, B. G.: Estimation of particulate organic carbon in the ocean from satellite remote sensing, Science, 285, 239–242, 1999. Stramski, D., Reynolds, R. A., Babin, M., Kaczmarek, S., Lewis, M. R., Röttgers, R., Sciandra, A., Stramska, M., Twardowski, M. S., Franz, B. A., and Claustre, H.: Relationships between the surface concentration of particulate organic carbon and optical properties in the eastern South Pacific and eastern Atlantic Oceans, Biogeosciences, 5, 171–201, <a href="http://dx.doi.org/10.5194/bg-5-171-2008">https://doi.org/10.5194/bg-5-171-2008</a>, 2008. Sturt, H. F., Summons, R. E., Smith, K., Elvert, M., and Hinrichs, K. U.: Intact polar membrane lipids in prokaryotes and sediments deciphered by high-performance liquid chromatography/electrospray ionization multistage mass spectrometry–new biomarkers for biogeochemistry and microbial ecology, Rapid Commun. Mass Sp., 18, 617–628, 2004. Suzumura, M.: Phospholipids in marine environments: a review, Talanta, 66, 422–434, 2005. Swan, B. K., Martinez-Garcia, M., Preston, C. M., Sczyrba, A., Woyke, T., Lamy, D., Reinthaler, T., Poulton, N. J., Masland, E. D. P., Gomez, M. L., Sieracki, M. E., DeLong, E. F., Herndl, G. J., and Stepanauskas, R.: Potential for Chemolithoautotrophy Among Ubiquitous Bacteria Lineages in the Dark Ocean, Science, 333, 1296–1300, 2011. Swanson-Hysell, N. L., Rose, C. V., Calmet, C. C., Halverson, G. P., Hurtgen, M. T., and Maloof, A. C.: Cryogenian glaciation and the onset of carbon-isotope decoupling, Science, 328, 608–611, 2010. Tang, K., Jiao, N., Liu, K., Zhang, Y., and Li, S.: Distribution and functions of TonB-dependent transporters in marine bacteria and environments: implications for dissolved organic matter utilization, Plos One, 7, e41204, <a href="http://dx.doi.org/10.1371/journal.pone.0041204">https://doi.org/10.1371/journal.pone.0041204</a>, 2012. Tarran, G. A., Zubkov, M. V., Sleigh, M. A., Burkill, P. H., and Yallop, M.: Microbial community structure and standing stocks in the NE Atlantic in June and July of 1996, Deep-Sea Res. Pt. II, 48, 963–985, 2001. Taylor, P. G. and Townsend, A. R.: Stoichiometric control of organic carbon-nitrate relationships from soils to the sea, Nature, 464, 1178–1181, 2010. Teira, E., Pazo, M. J., Serret, P., and Fernandez, E.: Dissolved organic carbon production by microbial populations in the Atlantic Ocean, Limnol. Oceanogr., 46, 1370–1377, 2001. Thomas, H., Ittekkot, V., Osterroht, C., and Schneider, B.: Preferential recycling of nutrients – the ocean's way to increase new production and to pass nutrient limitation?, Limnol. Oceanogr., 44, 1999–2004, 1999. Thomas, H., Bozec, Y., Elkalay, K., and de Baar, H. J. W.: Enhanced open ocean storage of CO<sub>2</sub> from shelf sea pumping, Science, 304, 1005–1008, 2004. Tortell, P. D., DiTullio, G. R., Sigman, D. M., and Morel, F. M. M.: CO<sub>2</sub> effects on taxonomic composition and nutrient utilization in an Equatorial Pacific phytoplankton assemblage, Mar. Ecol.-Prog. Ser., 236, 37–43, 2002. Tsunogai, S. and Noriki, S.: Particulate Fluxes of Carbonate and Organic-Carbon in the Ocean – Is the Marine Biological-Activity Working as a Sink of the Atmospheric Carbon, Tellus B, 43, 256–266, 1991. Uitz, J., Claustre, H., Gentili, B., and Stramski, D.: Phytoplankton class-specific primary production in the world's oceans: Seasonal and interannual variability from satellite observations, Global. Biogeochem. Cy., 24, GB3016, <a href="http://dx.doi.org/10.1029/2009gb003680">https://doi.org/10.1029/2009gb003680</a>, 2010. Ullman, R., Bilbao-Bastida, V., and Grimsditch, G.: Including Blue Carbon in climate market mechanisms, Ocean. Coast. Manage., 83, 15–18, 2013. van Haren, H., Millot, C., and Taupier-Letage, I.: Fast deep sinking in Mediterranean eddies, Geophys. Res. Lett., 33, L04606, <a href="http://dx.doi.org/10.1029/2005gl025367">https://doi.org/10.1029/2005gl025367</a>, 2006. Volk, T. and Hoffert, M. I.: Ocean carbon pumps: analysis of relative strength and efficiencies of in ocean-driven circulation atmospheric CO<sub>2</sub> changes, in: The carbon cycle and atmospheric CO<sub>2</sub>: Natural variation Archean to Present, edited by: Sundquist, E. T. and Broecker, W. S., AGU Monograph 32, American Geophysical Union, Washington, DC, 99–110, 1985. White, A. E., Watkins-Brandt, K. S., Engle, M. A., Burkhardt, B., and Paytan, A.: Characterization of the rate and temperature sensitivities of bacterial remineralization of dissolved organic phosphorus compounds by natural populations, Front Microbiol., 3, 276, <a href="http://dx.doi.org/10.3389/fmicb.2012.00276">https://doi.org/10.3389/fmicb.2012.00276</a>, 2012. White, D. C., Davis, W. M., Nickels, J. S., King, J. D., and Bobbie, R. J.: Determination of the sedimentary microbial biomass by extractible lipid phosphate, Oecologia, 40, 51–62, 1979. White, D. C., Flemming, C. A., Leung, K. T., and Macnaughton, S. J.: In situ microbial ecology for quantitative appraisal, monitoring, and risk assessment of pollution remediation in soils, the subsurface, the rhizosphere and in biofilms, J. Microbiol. Meth., 32, 93–105, 1998. Wieder, W. R., Bonan, G. B., and Allison, S. D.: Global soil carbon projections are improved by modelling microbial processes, Nat. Clim. Chang., 3, 909–912, 2013. Wohlers-Zöllner, J., Biermann, A., Engel, A., Dörge, P., Lewandowska, A. M., von Scheibner, M., and Riebesell, U.: Effects of rising temperature on pelagic biogeochemistry in mesocosm systems: a comparative analysis of the AQUASHIFT Kiel experiments, Mar. Biol., 159, 2503–2518, 2012. Zhang, C. L., Li, Y., Wall, J. D., Larsen, L., Sassen, R., Huang, Y., Wang, Y., Peacock, A., White, D. C., Horita, J., and Cole, D. R.: Lipid and carbon isotopic evidence of methane-oxidizing and sulfate-reducing bacteria in association with gas hydrates from the Gulf of Mexico, Geology, 30, 239–242, 2002. Zhang, R., Xia, X., Lau, S. C. K., Motegi, C., Weinbauer, M. G., and Jiao, N.: Response of bacterioplankton community structure to an artificial gradient of <i>p</i>CO<sub>2</sub> in the Arctic Ocean, Biogeosciences, 10, 3679–3689, <a href="http://dx.doi.org/10.5194/bg-10-3679-2013">https://doi.org/10.5194/bg-10-3679-2013</a>, 2013. Ziervogel, B., Dhaksnamoorthy, B., Blachowicz, L., and Roux, B.: Antibiotic Binding and Dynamics within the OmpF Channel Allow Transfer Across the Bacterial Outer Membrane, Biophys. J., 100, 244–244, 2011. Zubkov, M. V. and Tarran, G. A.: High bacterivory by the smallest phytoplankton in the North Atlantic Ocean, Nature, 455, 224–226, 2008.