BG Biogeosciences BG Biogeosciences 1726-4189 Copernicus Publications Göttingen, Germany 10.5194/bg-6-2281-2009 Bioavailability of organically bound Fe to model phytoplankton of the Southern Ocean Hassler C. S. 1 3 Schoemann V. 2 Centre for Australian Weather and Climate Research (CAWCR), a partnership between CSIRO and the Bureau of Meteorology, Castray Esplanade, Hobart, 7000, TAS, Australia Ecologie des Systèmes Aquatiques, Université Libre de Bruxelles, Campus de la Plaine, CP 221, Boulevard du Triomphe, 1050 Bruxelles, Belgium now at: Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, P.O. Box 123 Broadway, 2007, NSW, Australia 30 10 2009 6 10 2281 2296 Copyright: © 2009 C. S. Hassler 2009 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/6/2281/2009/bg-6-2281-2009.html The full text article is available as a PDF file from https://bg.copernicus.org/articles/6/2281/2009/bg-6-2281-2009.pdf

Iron (Fe) is known to be mostly bound to organic ligands and to limit primary productivity in the Southern Ocean. It is thus important to investigate the bioavailability of organically bound Fe. In this study, we used four phytoplankton species of the Southern Ocean (<i>Phaeocystis</i> sp., <i>Chaetoceros</i> sp., <i>Fragilariopsis kerguelensis</i> and <i>Thalassiosira antarctica Comber</i>) to measure the influence of various organic ligands on Fe solubility and bioavailability. Short-term uptake Fe:C ratios were inversely related to the surface area to volume ratios of the phytoplankton. The ratio of extracellular to intracellular Fe is used to discuss the relative importance of diffusive supply and uptake to control Fe bioavailability. The effect of excess organic ligands on Fe bioavailability cannot be solely explained by their effect on Fe solubility. For most strains studied, the bioavailability of Fe can be enhanced relative to inorganic Fe in the presence of porphyrin, catecholate siderophore and saccharides whereas it was decreased in presence of hydroxamate siderophore and organic amine. For <i>Thalassiosira</i>, iron bioavailability was not affected by the presence of porphyrin, catecholate siderophore and saccharides. The enhancement of Fe bioavailability in presence of saccharides is presented as the result from both the formation of bioavailable (or chemically labile) organic form of Fe and the stabilisation of Fe within the dissolved phase. Given the ubiquitous presence of saccharides in the ocean, these compounds might represent an important factor to control the basal level of soluble and bioavailable Fe. Results show that the use of model phytoplankton is promising to improve mechanistic understanding of Fe bioavailability and primary productivity in HNLC regions of the ocean.

 References % vor jede Referenz Abraham, E. R., Law, C. S., Boyd, P. W. Lavender, S. J., Maldonado, M. T., and Bowie, A. R.: Importance of stirring in the development of an iron-fertilised phytoplankton bloom, Nature, 407, 727–730, 2000. Armand, L. K., Cornet-Barthaux, V., Mosseri, J., and Quéguiner, B.: Late summer diatom biomass and community structure on and around the naturally iron-fertilised Kerguelen Plateau in the Southern Ocean, Deep-Sea Res. II, 55, 653–676, 2008. Barbeau, K., Moffett, J. W., Caron, D. A., Croot, P. L., and Erdner, D. L.: Role of protozoan grazing in relieving iron limitation of phytoplankton, Nature, 380, 61–64, 1996. Barbeau, K., Rue, E. L., Bruland , K. W., and Butler A.: Photochemical cycling of iron in the surface ocean mediated by microbial iron(III)-binding ligands, Nature, 413, 409–413, 2001. Becquevort, S., Lancelot, C., and Schoemann, V.: The role of iron in the bacterial degradation of organic matter derived from \textitPhaeocystis Antarctica, Biogeochemistry, 83, 119–135, https://doi.org/10.1007/s10533-007-9079-1, 2007. Borer, P. M., Sulzberger, B., Reichard, P., and Kraemer S. M.: Effect of siderophores on the light-induced dissolution of colloidal iron(III) (hydr)oxides, Mar. Chem, 93, 179–193, 2005. Boyé, M. and van den Berg, C. M. G.: Iron availability and the release of iron-complexing ligands by Emiliania huxleyi, Mar. Chem., 70, 277–287, 2000. Boyé, M., van den Berg, C. M. G., de Jong, J. T. M., Leach, H., Croot, P., and de Baar, H. J. W.: Organic complexation of iron in the Southern Ocean, Deep-Sea Res. I, 48, 1477–1497, 2001. Boyd, P., Watson, A. J., Law, C. S., et al.: A mesoscale phytoplankton bloom in the polar Southern Ocean stimulated by iron fertilization, Nature, 407, 695–702, 2000. Chen, M., Dei, R. C. H., Wang, W.-X., and Guo, L.: Marine diatom uptake of iron bound with natural colloids of different origins, Mar. Chem., 81, 177–189, 2003. Chen, M., Wang ,W.-X., and Guo, L.: Phase partitioning and solubility of iron in natural seawater controlled by dissolved organic matter, Global Biogeochem. Cy., 18, GB4013, https://doi.org/10.1029/2003GB002160, 2004. Croot, P. L. and Johansson, M.: Determination of iron speciation by cathodic stripping voltammetry in seawater using the competing ligand 2-(2-thiazolylazo)-p-cresol (TAC), Electroanalysis, 12, 565–576, 2000. Davis, T. A., Llanes, F., Volesky, B., and Mucci, A.: Metal selectivity of \textitSargassum spp. and their alginates in relation to their $\alpha $-L-Guluronic acid content and conformation, Environ. Sci. Technol., 37, 261–267, 2003. de Baar, H. J. W., Buma, A. G. J., Nolting, R. F., Cadée, G. C., Jacques, G., and Tréguer, P. J.: On iron limitation~ of the Southern Ocean: experimental observations in the Weddell and Scotia Seas, Mar. Ecol. Prog. Ser., 65, 105–122, 1990. de Baar, H. J. W., Van Leeuwe, M. A., Scharek, R., Goeyens, L., Bakker, K. M. J., and Fritsche, P.: Nutrient anomalies in \textitFragilariopsis kerguelensis blooms, iron deficiency and the nitrate/phosphate ratio (A. C. Redfield) of the Antarctic Ocean, Deep Sea Res. II, 44, 229–260, 1997. de Baar, H. J. W. and de Jong, J. T. M.: Distribution, sources and sinks of iron in seawater, in: The Biogeochemistry of Iron in Seawater, edited by: Turner, D. R. and Hunter, K. H., IUPAC Series on Analytical and Physical Chemistry of Environmental Systems, vol. 7, Wiley, New York, 123–153, 2001. de Baar, H. J. W., Boyd, P. W., Coale, K. H., Landry, M. R., Tsuda, A., Assmy, P., Bakker, D. C. E., Bozec, Y., Barber, R. T., Brzezinski, M. A., Buesseler, K. O., Boye, M., Croot, P. L., Gervais, F., Gorbunov, M. Y., Harrison, P. J., Hiscock, W. T., Laan, P., Lancelot, C., Law, C. S., Levasseur, M., Marchetti, A., Millero, F. J., Nishioka, J., Nojiri, Y., van Oijen, T., Riebesell, U., Rijkenberg, M. J. A., Saito, H., Takeda, S., Timmermans, K. R., Veldhuis, M. J. W., Waite, A. M., and Wong, C.-S.: Synthesis of iron fertilization experiments: From the iron age in the age of enlightenment, J. Geophys. Res., 110, C09S16/01–C09S16/24, https://doi.org/10.1029/2004JC002601, 2005. de Jong, J., Schoemann, V., Lannuzel, D., Tison, J.-L., and Mattielli, N.: High-accuracy determination of iron in seawater by isotope dilution multiple collector inductively coupled plasma mass spectrometry (ID-MC-ICP-MS) using nitrilotriacetic acid chelating resin for pre-concentration and matrix separation, Anal. Chim. Acta, 623, 126–139, https://doi.org/10.1016/j.aca.2008.06.013, 2008. Freire-Nordi, C. S., Vieira, A. A. H., Nakaie, C. R., and Nascimento, O. R.: The metal binding capacity of \textitAnabaena spiroides extracellular polysaccharides: an EPR study, Process Biogeochemistry, 40, 2215–2224, 2005. Gledhill, M., McCormack, P., Ussher, S., Achterberg, E. P., Mantoura, R. F. C., and Worsfold, P. J.: Production of siderophore type chelates by mixed bacterioplankton populations in nutrient enriched seawater incubations, Mar. Chem., 88, 75–83, 2004. Gledhill, M.: The determination of heme b in marine phyto- and bacterioplankton, Mar. Chem., 103, 393–403, 2007. Harrison, G. I. and Morel, F. M. M.: Response of the marine diatom \textitThalassiosira weissflogii to iron stress, Limnol. Oceanogr., 31, 989–997, 1986. Hassler, C. S. and Twiss, M. R.: Bioavailability of iron sensed by a phytoplanktonic Fe-bioreporter, Environ. Sci. Technol., 40, 2544–2551, 2006. Hassler, C. S. and Schoemann, V.: Discriminating between intra- and extracellular metals using chemical extraction- the case of iron, Limnol. Oceanogr. Methods, 7, 479–489, 2009. Hassler C., Petrou K., Clementson L., Blackburn S., and Butler E.: Iron limitation for Southern Ocean diatom (\textitChaetoceros sp.) and haptophyte (\textitPhaeocystis sp.): impact on physiology and iron bioavailability, in preparation, 2009a. Hassler, C. S., Alasonati, E., Mancuso Nichols C. A., and Slaveykova, V. I.: Exopolysaccharides produced by bacteria isolated from the pelagic Southern Ocean - role in iron binding, chemical reactivity and bioavailability, Mar. Chem., submitted, 2009b. Hillebrand, H., Dürselen, C. D., Kirschtel, D., Zohary, T., and Pollingher, U.: Biovolume calculation for pelagic and benthic microalgae, J. Phycol., 35, 403–424, 1999. Hoagland, K. D., Rosowski, J. R., Gretz, M. R., and Roemer, S. C.: Diatom extracellular polymeric substances: function, fine structure, chemistry, and physiology, J. Phycol., 29, 537–566, 1993. Hudson, R. J. M. and F. M. M. Morel, F. M. M.: Distinguishing between extra- and intracellular iron in marine phytoplankton, Limnol. Oceanogr., 34, 1113–1120, 1989. Hudson, R. J. M. and Morel, F. M. M.: Iron transport in marine phytoplankton: kinetics of cellular and medium coordination reactions, Limnol. Oceanogr., 35, 1002–1020, 1990. Hunter K. H. and Boyd, P. W.: Iron-binding ligands and their role in the ocean biogeochemistry of iron, Environ. Chem., 4, 221–232, 2007. Hutchins, D. A., Witter, A. E., Butler, A., and Luther III, G. W.: Competition among marine phytoplankton for different chelated iron species, Nature, 400, 858–861, 1999. Janse, I., van Rijssel, M., van Hall, P., Gerwing, G. J., Gottschal, J. C., and Prins, R. A.: The storage glucan of \textitPhaeocystis globosa (prymnesiophyceae) cells, J. Phycol., 32, 382–387, 1996. Kirchman, D. L., Meon, B., Cottrell, M. T., Hutchins, D. A., Weeks, D., and Bruland, K. W.: Carbon versus iron limitation of bacterial growth in the California upwelling regime, Limnol. Oceanogr., 45, 1681–1688, 2000. Kojima, M., Takahashi, K., and Nakamura, K.: Cationic dye-sensitized degradation of sodium hyaluronate through photon induced electron transfer in the upper excited state. Photochem. Photobiol., 74, 369–377, 2001. Kuma, K., Nakabayashi, S., and Matsunaga, K.: Photoreduction of Fe(III) by hydroxycarboxilic acids in seawater, Water Resour., 29, 1559–1569, 1995. Lam, P. J., Bishop, J. K. B., Henning, C. C., Marcus, M. A., Waychunas, G. A., and Fung, I. Y.: Wintertime phytoplankton bloom in the subarctic Pacific supported by continental margin iron, Global Biogeochem. Cy., 20, GB1006, https://doi.org/10.1029/2005GB002557, 2006. Lannuzel, D., Schoemann, V., de Jong, J., Chou, L., Delille, B., Becquevort, S., and Tison, J. L.: Iron study during a time series in the western Weddell pack ice, Mar. Chem., 108, 85–95, 2008. Lannuzel D., Remenyi, T., Lam, P., Townsend, A., Ibisanmi, E., Butler, E., Wagener, T., Schoemann, V., and Bowie, A. R.: Distributions of dissolved and particulate iron in the sub-Antarctic and Polar Frontal Southern Ocean (Australian sector), Deep Sea Res. II, accepted, 2009. Maldonado, M. T. and Price, N. M.: Influence of N substrate on Fe requirements of marine centric diatoms, Mar. Ecol. Prog. Ser., 141, 161–172, 1996. Maldonado, M. T., Strzepek, R. F., Sander, S., and Boyd, P. W.: Acquisition of iron bound to strong organic complexes, with different Fe binding groups and photochemical reactivities, by plankton communities in Fe-limited subantarctic waters, Global Biogeochem. Cy., 19, GB4S23, https://doi.org/10.1029/2005GB002481, 2005. Mancuso C. A. N., Lardière, S. G., Bowman, J. P., Nichols, P. D., Gibson, J. A. E., and Guézennec, J.: Chemical characterization of exopolysaccharides from Antarctic marine bacteria, Microbiol. Ecol., 49, 578–589, 2005. McCormack, P., Worsfold, P. J., and Gledhill, M.: Separation and detection of siderophores produced by marine bacterioplankton using high-performance liquid chromatography with electrospray ionization mass spectrometry, Anal. Chem., 75, 2647–2652, 2003. McKay, R. L. M., Wilhelm, S. W., Hall, J., Hutchins, D. A., Al-Rshaidat, M. M. D., Mioni, C. E., Pickmere, S., Porta, D., and Boyd, P. W.: Impact of phytoplankton on the biogeochemical cycling of iron in subantarctic waters southeast of new Zealand during FeCycle, Global Biogeochem. Cy., 19, GB4S24, https://doi.org/10.1029/2005GB002482, 2005. Morel, F. M. M. and Hering, J. G.: Principles and applications of aquatic chemistry, Wiley Interscience, New York, 1993. Morel, F. M. M., Kustka, A. B., and Shaked, Y.: The role of unchelated Fe in the iron nutrition of phytoplankton, Limnol. Oceanogr., 53, 400–404, 2008. Nodwell, L. M. and Price, N. M.: Direct use of inorganic colloidal iron by marine mixotrophic phytoplankton, Limnol. Oceanogr., 46, 765–777, 2001. Öztürk, M., Croot, P. L., Bertilsson, S., Abrahamsson, K., Karlson, B., David, R., Fransson, A., and Sakshaug, E.: Iron enrichment and photoreduction of iron under UV and PAR in the presence of hydroxycarboxylic acid: implications for phytoplankton growth in the Southern Ocean, Deep-Sea Res. II, 51, 2841–2856, 2004. Pahlow, M., Riebesell, U., and Wolf-Gladrow, D. A.: Impact of cell shape and chain formation on nutrient acquisition by marine diatoms, Limnol. Oceanogr., 42, 1660–1672, 1997. Panagiotopoulos, C. and Sempéré, R.: Analytical methods for the determination of sugars in marine samples: A historical perspective and future directions, Limnol. Oceanogr. Methods, 3, 419–454, 2005. Panagiotopoulos, C., Repeta, D. J., and Johnson, C. G.: Characterization of methyl sugars, 3-deoxysugars and methyl deoxysugars in marine high molecular weight dissolved organic matter, Org. Geochem., 38, 884–896, 2007. Poorvin, L., Rinta-Kanto, J. M., Hutchins, D. A., and Wilhelm, S. W.: Viral release of iron and its bioavailability to marine plankton, Limnol. Oceanogr., 49, 1734–1741, 2004. Porter, K. G. and Feig, Y. S.: The use of DAPI for identifying and counting aquatic microflora, Limnol. Oceanogr., 25, 943–948, 1980. Price, N. M. and Morel, F. M. M.: Biological cycling of iron in the ocean, Met. Ions Biol. Syst., 35, 1–36, 1998. Rich, H. W. and Morel, F. M. M.: Availability of well-defined iron colloids to the marine diatom \textitThalassiosira weissflogii, Limnol. Oceanogr., 35, 652–662, 1990. Rijkenberg, M. J. A., Gerringa, L. J. A., Timmermans, K. R., Fischer, A. C., Kroon, K. J., Buma, A. G. J., Wolterbeek, B. T., and de Baar, H. J. W.: Enhancement of the reactive iron pool by marine diatoms, Mar. Chem., 109, 29–44, 2008. Rue, E. L. and Bruland, K. W.: Complexation of iron(III) by natural organic ligands in the Central North Pacific as determined by a new competitive ligand equilibration/adsorptive cathodic stripping voltammetric method, Mar. Chem., 50, 117–138, 1995. Santschi, P. H., Hung, C.-C., Schultz, G., Alvarado-Quiroz, N., Guo, L., Pinckney, J., and Walsh, I.: Control of acid polysaccharide production and $^234$Th and POC export fluxes by marine organisms, Geophys. Res. Lett., 30, 1044, https://doi.org/10.1029/2002GL016046, 2003. Sarthou, G., Timmermans, K. R., Blain, S., and Treguer, P.: Growth physiology and fate of diatoms in the ocean: a review, J. Sea Res., 53, 25–42, 2005. Schoemann, V., Wollast, R., Chou, L., and Lancelot, C.: Effects of photosynthesis on the accumulation of Mn and Fe by \textitPhaeocystis colonies, Limnol. Oceanogr., 46, 1065–1076, 2001. Schoemann, V., Becquevort, S., Stefels, J., Rousseau, V., and Lancelot, C.: Phaeocystis blooms in the global ocean and their controlling mechanisms: a review, J. Sea Res., 53, 43–66, 2005. Schoemann, V., Hassler, C., Masson, F., Dumont, I., Lannuzel, D., Bowie, A., and Becquevort, S.: The effect of organic ligands on Fe bioavailability to natural plankton communities of the Southern Ocean, in preparation, 2009. Schmidt, M. A. and Hutchins, D. A.: Size-fractionated biological iron and carbon uptake along a coastal to offshore transect in the NE Pacific, Deep-Sea Res. II, 46, 2487–2503, 1999. Shaked, Y., Kustka, A. B., and Morel, F. M. M.: A general kinetic model for iron acquisition by eukaryotic phytoplankton, Limnol. Oceanogr., 50, 872–882, 2005. Strzepek, R. F. and Harrison P. J.: Photosynthetic architecture differs in coastal and oceanic diatoms, Nature, 431, 689–692, 2004. Strzepek, R. F., Maldonado, M. T., Higgins, J. L., Hall, J., Safi, K., Wilhelm, S. W., and Boyd, P. W.: Spinning the "Ferrous Wheel": The importance of the microbial community in an iron budget during the FeCycle experiment, Global Biogeochem. Cy., 19, GB4S26, https://doi.org/10.1029/2005GB002490, 2005. Sunda, W. G. and Huntsman, S. A.: Iron uptake and growth limitation in oceanic and coastal phytoplankton, Mar. Chem., 50, 189–206, 1995. Sunda, W. G. and Huntsman, S. A.: Interrelated influence of iron, light and cell size on marine phytoplankton growth, Nature, 390, 389–392, 1997. Tagliabue, A. and K. R.: Arrigo. Processes governing the supply of iron to phytoplankton in stratified seas, J. Geophys. Res., 111, C06019, https://doi.org/10.1029/2005JC003363, 2006. Tagliabue, A., Bopp, L., Aumont, O., and Arrigo, K. R.: The influence of light and temperature on the marine iron cycle: From theoretical to global modelling, Global Biogeochem. Cy., 23, GB2017, https://doi.org/10.1029/2008GB003214, 2009. Takeda, S.: Influence of iron availability on nutrient consumption ratio of diatoms in oceanic waters, Nature, 393, 774–777, 1998. Tang, D. and Morel, F. M. M.: Distinguishing between cellular and Fe-oxide-associated trace elements in phytoplankton, Mar. Chem., 98, 18–30, 2006. Tian, F., Frew, R. D., Sander, S., Hunter, K. A., and Ellwood, M. J.: Organic iron(III) speciation in surface transects across a frontal zone: the Chatham Rise, New Zealand, Mar. Freshwater Res., 57, 533–544, 2006. Timmermans, K. R., Davey, M. S., van der Wagt, B., Snoek, J., Geider, R. J., Veldhuis, M. J. W., Gerringa, L. J. A., and de Baar, H. J. W.: Co-limitation by iron and light of \textitChaetoceros brevis, \textitC. dichaeta and \textitC. calcitrans (Bacillariophyceae), Mar. Ecol. Prog. Ser., 217, 287–297 , 2001. Timmermans, K. R., van der Wagt, B., and de Baar, H. J. W.: Growth rates, half-saturation constants, and silicate, nitrate, and phosphate depletion in relation to iron availability of four large, open-ocean diatoms from the Southern Ocean, Limnol. Oceanogr., 49, 2141–2151, 2004. Timmermans, K. R., Veldhuis, M. J. W., Laan, P., and Brussaard, C. P. D.: Probing natural iron fertilization near the Kerguelen (Southern Ocean) using natural phytoplankton assemblages and diatom cultures, Deep-Sea Res. II, 55, 693–705, 2008. Tovar-Sanchez, A., Sanudo-Wilhelmy, S. A., Garcia-Vargas, M., Weaver, R. S., Popels, L. C., and Hutchins, D. A.: A trace metal clean reagent to remove surface-bound iron from marine phytoplankton, Mar. Chem, 82, 91–99, 2003. Trick, C. G., Andersen, R. J., Price, N. M., and Harrison, P. J.: Examination of hydroxamate-siderophore production by neritic eukaryotic marine phytoplankton, Mar. Biol., 75, 9–17, 1983. Twining, B. S., Baines, S. B., Fisher, N. S., and Landry, M. R.: Cellular iron contents of plankton during the Southern Ocean Iron Experiment (SOFeX), Deep-Sea Res. I, 51, 1827–1850, 2004. van Leeuwen, H. P.: Metal speciation dynamics and bioavailability: inert and labile complexes, Environ. Sci. Technol., 33, 3743–3748, 1999. van Oijen, T., Veldhuis, M. J. W., Gorbunov, M. Y., Nishioka, J., van Leeuwe, M. A., and de Baar, H. J. W.: Enhanced carbohydrate production by Southern Ocean phytoplankton in response to in situ iron fertilization, Mar. Chem., 93, 33–52, 2005. Völker, C. and Wolf-Gladrow, D. A.: Physical limits on iron uptake mediated by siderophores or surface reductases, Mar. Chem., 65, 227–244, 1999. Vong, L., La\"es, A. and Blain, S.: Determination of iron-porphyrin-like complexes at nanomolar levels in seawater, Anal. Chim. Acta, 588, 237–244, 2007. Wang, W. X. and Dei, R. C. H.: Bioavailability of iron complexed with organic colloids to the cyanobacteria \textitSynechococcus and \textitTrichodesmium, Aquat. Microb. Ecol., 33, 247–259, 2003. Wang, D., Henrichs, S. M., and Guo, L.: Distributions of nutrients, dissolved organic carbon and carbohydrates in the western Arctic Ocean, Cont. Shelf Res., 26, 1654–1667, 2006. Wilkinson, K. J. and Buffle, J.: Critical evaluation of physicochemical parameters and processes for modeling the biological uptake of trace metals in environmental (aquatic) systems, in: Physicochemical kinetics and transport at biointerfaces, edited by: van Leeuwen, H. P. and Köster, W., John Wiley & Sons, New-York, 445–533, 2004. Witter, A. E., Hutchins, D. A., Butler, A., and Luther III, G. W.: Determination of conditional stability constants and kinetic constants for strong model Fe-binding ligands in seawater, Mar. Chem., 69, 1–17, 2000. Worms, I., Simon, D. F., Hassler, C. S., and Wilkinson, K. J.: Bioavailability of trace metals to aquatic microorganisms: importance of chemical, biological and physical processes on \mboxbiouptake, Biochimie, 88, 1721–1731, 2006. Zhang, W. and Wang, W.-X.: Colloidal organic carbon and trace metal (Cd, Fe, and Zn) releases by diatom exudation and copepod grazing, J. Exp. Mar. Biol. Ecol., 307, 17–34, 2004.