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Interrelated influence of iron, light and cell size on marine phytoplankton growth


The sub-optimal growth of phytoplankton and the resulting persistence of unutilized plant nutrients (nitrate and phosphate) in the surface waters of certain ocean regions has been a long-standing puzzle1,2. Of these regions, the Southern Ocean seems to play the greatest role in the global carbon cycle3,4, but controversy exists as to the dominant controls on net algal production. Limitation by iron deficiency4,5, light availability1,6,7 and grazing by zooplankton2 have been proposed. Here we present the results from culture experiments showing that the amount of cellular iron needed to support growth is higher under lower light intensities, owing to a greater requirement for photosynthetic iron-based redox proteins by low-light acclimatized algae. Moreover, algal iron uptake varies with cell surface area, such that the growth of small cells is favoured under iron limitation, as predicted theoretically8. Phytoplankton growth can therefore be simultaneously limited by the availability of both iron and light. Such a co-limitation may be experienced by phytoplankton in iron-poor regions in which the surface mixed layer extends below the euphotic zone—as often occurs in the Southern Ocean6,7—or near the bottom of the euphotic zone in more stratified waters. By favouring the growth of smaller cells, iron/light co-limitation should increase grazing by microzooplankton, and thus minimize the loss of fixed carbon and nitrogen from surface waters in settling particles9,10.

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Figure 1: Relationships among specific growth rate, intracellular Fe : C (measured with radiotracers), Fe uptake rate (normalized to cell volume and equivalent spherical surface area), and [Fe′] for coastal eukaryotes of varying mean diameters grown at 500 µE m−2 s−1 (here µE indicates microeinstein).
Figure 2: Specific growth rate (a) and Chl a : C (b) as functions of intracellular Fe : C at high (500 µE m−2 s−1; open symbols) and low light (50, closed symbols).
Figure 3: Plot of μ/μmax against [Fe′] at growth-saturating and growth-limiting light intensities.
Figure 4

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  1. Hart, T. J. On the phytoplankton in the southwest Atlantic and Bellinghausen Sea, 1929–31. Discovery Rep. 8, 1–268 (1934).

    Google Scholar 

  2. Cullen, J. T. Hypotheses to explain high nutrient conditions in the open sea. Limnol. Oceanogr. 36, 1579–1599 (1991).

    Article  ADS  Google Scholar 

  3. Sarmiento, J. L. & Toggweiler, J. R. Anew model for the role of the oceans in determining atmospheric carbon dioxide levels. Nature 308, 621–624 (1984).

    Article  ADS  CAS  Google Scholar 

  4. Martin, J. H. Glacial–interglacial CO2change: The iron hypothesis. Palaeooceanography 5, 1–13 (1990).

    Article  ADS  Google Scholar 

  5. Martin, J. H., Fitzwater, S. E. & Gordon, R. M. Iron deficiency limits phytoplankton growth in Antarctic waters. Global Biogeochem. Cycles 4, 5–12 (1990).

    Article  ADS  CAS  Google Scholar 

  6. Nelson, D. M. & Smith, W. O. Sverdrup revisited: Critical depths, maximum chlorophyll levels, and the control of Southern Ocean productivity by the irradiance-mixing regime. Limnol. Oceanogr. 36, 1650–1661 (1991).

    Article  ADS  Google Scholar 

  7. Mitchell, B. G., Brody, E. A., Holm-Hansen, O., McCain, C. & Bishop, J. Light limitation of phytoplankton biomass and macronutrient utilization in the Southern Ocean. Limnol. Oceanogr. 36, 1662–1677 (1991).

    Article  ADS  Google Scholar 

  8. Hudson, R. J. M. & Morel, F. M. M. Iron transport in marine phytoplankton: kinetics of medium and cellular coordination reactions. Limnol. Oceanogr. 35, 1002–1020 (1990).

    Article  ADS  CAS  Google Scholar 

  9. Miller, C. B. et al . Ecological dynamics in the subarctic Pacific, a possibly iron-limited ecosystem. Limnol. Oceanogr. 36, 1600–1615 (1991).

    Article  ADS  CAS  Google Scholar 

  10. Price, N. M., Ahner, B. A. & Morel, F. M. M. The equatorial Pacific Ocean: Grazer controlled phytoplankton populations in an iron-limited ecosystem. Limnol. Oceanogr. 39, 520–534 (1994).

    Article  ADS  CAS  Google Scholar 

  11. Sunda, W. G. & Huntsman, S. A. Iron uptake and growth limitation in oceanic and coastal phytoplankton. Mar. Chem. 50, 189–206 (1995).

    Article  CAS  Google Scholar 

  12. Anderson, M. A. & Morel, F. M. M. The influence of aqueous iron chemistry on the uptake of iron by the coastal diatom Thalassiosira weissflogii . Limnol. Oceanogr. 27, 789–813 (1982).

    Article  ADS  CAS  Google Scholar 

  13. Rich, H. W. & Morel, F. M. M. The availability of well-defined iron colloids to the marine diatom Thalassiosira weissflogii . Limnol. Oceanogr. 35, 652–662 (1990).

    Article  ADS  CAS  Google Scholar 

  14. Raven, J. A. The iron and molybdenum use efficiencies of plant growth with different energy, carbon and nitrogen sources. New Phytol. 109, 279–287 (1988).

    Article  CAS  Google Scholar 

  15. Raven, J. A. Predictions of Mn and Fe use efficiencies of phototrophic growth as a function of light availability for growth and C assimilation pathway. New Phytol. 116, 1–18 (1990).

    Article  CAS  Google Scholar 

  16. Falkowski, P. G., Owens, T. G., Ley, A. C. & Mauzerall, D. C. Effects of growth irradiance levels on the ratio of reaction centers in two species of marine phytoplankton. Plant Physiol. 68, 969–973 (1981).

    Article  CAS  Google Scholar 

  17. Boyle, E. A., Edmond, J. M. & Sholkovitz, E. R. The mechanism of iron removal in estuaries. Geochim. Cosmochim. Acta 41, 1313–1324 (1977).

    Article  ADS  CAS  Google Scholar 

  18. Gledhill, M. & van den Berg, C. M. G. Determination of complexation of iron (iii) with natural organic complexing ligands in seawater using cathodic stripping voltametry. Mar. Chem. 47, 41–54 (1994).

    Article  CAS  Google Scholar 

  19. Wu, J. & Luther, G. W. Complexation of Fe(iii) by natural organic ligands in the Northwest Atlantic Ocean determined by a competitive equilibration method and kinetic approach. Mar. Chem. 50, 159–177 (1995).

    Article  CAS  Google Scholar 

  20. Rue, E. L. & 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 voltametric method. Mar. Chem. 50, 117–138 (1995).

    Article  CAS  Google Scholar 

  21. Martin, J. H. & Gordon, R. M. Northeast Pacific iron distributions in relation to phytoplankton productivity. Deep-Sea Res. 35, 177–196 (1988).

    Article  ADS  CAS  Google Scholar 

  22. Bruland, K. W., Orians, K. J. & Cowen, J. P. Reactive trace metals in the stratified central North Pacific. Geochim. Cosmochim. Acta 58, 3171–3182 (1994).

    Article  ADS  CAS  Google Scholar 

  23. Coale, K. H. et al . Amassive phytoplankton bloom induced by an ecosystem-scale iron fertilization experiment in the equatorial Pacific Ocean. Nature 383, 495–501 (1996).

    Article  ADS  CAS  Google Scholar 

  24. Behrenfeld, M. J., Bale, A. J., Kolber, Z. S., Aiken, J. & Falkowski, P. G. Confirmation of iron limitation of phytoplankton photosynthesis in the equatorial Pacific. Nature 383, 508–511 (1996).

    Article  ADS  CAS  Google Scholar 

  25. Shimada, A., Hasegawa, T., Umeda, Kadoy, N. & Maruyama, T. Spatial mesoscale patterns of West Pacific picoplankton as analyzed by flow cytometry: their contribution to subsurface chlorophyll maxima. Mar. Biol. 115, 209–215 (1993).

    Article  CAS  Google Scholar 

  26. Takahashi, M. & Hori, T. The abundance of picoplankton in the subsurface chlorophyll maximum layer in subtropical and tropical waters. Mar. Biol. 79, 177–186 (1984).

    Article  CAS  Google Scholar 

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This paper was supported by grants from the Office of Naval Research.

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Correspondence to William G. Sunda.

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Sunda, W., Huntsman, S. Interrelated influence of iron, light and cell size on marine phytoplankton growth. Nature 390, 389–392 (1997).

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