Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Enhanced Southern Ocean marine productivity due to fertilization by giant icebergs

A Corrigendum to this article was published on 01 September 2016

This article has been updated

Abstract

Primary productivity is enhanced within a few kilometres of icebergs in the Weddell Sea1,2 owing to the input of terrigeneous nutrients and trace elements during iceberg melting. However, the influence of giant icebergs, over 18 km in length, on marine primary production in the Southern Ocean is less well studied1,3. Here we present an analysis of 175 satellite images of open ocean colour before and after the passage of 17 giant icebergs between 2003 and 2013. We detect substantially enhanced chlorophyll levels, typically over a radius of at least 4–10 times the iceberg’s length, that can persist for more than a month following passage of a giant iceberg. This area of influence is more than an order of magnitude larger than that found for sub-kilometre scale icebergs2 or in ship-based surveys of giant icebergs1. Assuming that carbon export increases by a factor of 5–10 over the area of influence, we estimate that up to a fifth of the Southern Ocean’s downward carbon flux originates with giant iceberg fertilization. We suggest that, if giant iceberg calving increases this century as expected4, this negative feedback on the carbon cycle may become more important.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: Chlorophyll-a concentration on 1 December 2013, from the MODIS Aqua satellite.
Figure 2: Mean chlorophyll level associated with the passage of a giant iceberg.
Figure 3: Chlorophyll concentration anomaly in the Pine Island Bay region of West Antarctica related to the passage of giant iceberg, B31.

Change history

  • 16 August 2016

    In the version of this Letter originally published, it was incorrectly stated in Figure 1 that Chlorophyll-α concentrations were recorded on 12 January 2013, when the date should have been 1 December 2013. This has been corrected in the online versions of the paper.

References

  1. Smith, K. L. Jr et al. Free-drifting icebergs: hot spots of chemical and biological enrichment in the Weddell Sea. Science 317, 478–482 (2007).

    Article  Google Scholar 

  2. Schwarz, J. N. & Schodlok, M. P. Impact of drifting icebergs on surface phytoplankton biomass in the Southern Ocean: ocean colour remote sensing and in situ iceberg tracking. Deep-Sea Res. I 56, 1727–1741 (2009).

    Article  Google Scholar 

  3. Helly, J. J., Kaufmann, R. S., Stephenson, G. R. & Vernet, M. Cooling, dilution and mixing of ocean water by free-drifting icebergs in the Weddell Sea. Deep-Sea Res. II 58, 1336–1345 (2011).

    Article  Google Scholar 

  4. Joughin, I., Smith, B. E. & Medley, B. Marine ice sheet collapse potentially under way for the Thwaites Glacier Basin, West Antarctica. Science 344, 735–738 (2014).

    Article  Google Scholar 

  5. Ciais, P. et al. in Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) 465–570 (IPCC, Cambridge Univ. Press, 2013).

    Google Scholar 

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

    Article  Google Scholar 

  7. Mahowald, N. M. et al. Atmospheric iron deposition: global distribution, variability and human perturbations. Ann. Rev. Mar. Sci. 1, 245–278 (2009).

    Article  Google Scholar 

  8. Blain, S. et al. A biogeochemical study of the island mass effect in the context of the iron hypothesis: Kerguelen Islands, Southern Ocean. Deep-Sea Res. I 48, 163–187 (2001).

    Article  Google Scholar 

  9. Lancelot, C. et al. Spatial distribution of the iron supply to phytoplankton in the Southern Ocean: a model study. Biogeosciences 6, 2861–2878 (2009).

    Article  Google Scholar 

  10. Hawkings, J. R. et al. Ice sheets as a significant source of highly reactive nanoparticulate iron to the oceans. Nature Commun. 5, 3929 (2014).

    Article  Google Scholar 

  11. Wadley, M. R., Jickells, T. D. & Heywood, K. J. The role of iron sources and transport for Southern Ocean productivity. Deep-Sea Res. I 87, 82–94 (2014).

    Article  Google Scholar 

  12. Death, R. et al. Antarctic ice sheet fertilises the Southern Ocean. Biogeosciences 11, 2635–2643 (2014).

    Article  Google Scholar 

  13. Raiswell, R., Benning, L. G., Tranter, M. & Tulaczyk, S. Bioavailable iron in the Southern Ocean: the significance of the iceberg conveyor belt. Geochem. Trans. 9 (2008).

  14. Wadham, J. L. et al. The potential role of the Antarctic Ice Sheet in global biogeochemical cycles. Earth Env. Sci. Trans. R. Soc. Edinburgh 104, 55–67 (2013).

    Article  Google Scholar 

  15. Silva, T. A. M., Bigg, G. R. & Nicholls, K. W. The contribution of giant icebergs to the Southern Ocean freshwater flux. J. Geophys. Res. Oceans 111, C03004 (2006).

    Google Scholar 

  16. Lannuzel, D. et al. Iron study during a time series in the western Weddell pack ice. Mar. Chem. 108, 85–95 (2008).

    Article  Google Scholar 

  17. Jansen, D., Schodlok, M. & Rack, W. Basal melting of A-38B: a physical model constrained by satellite observations. Remote Sens. Env. 111, 195–203 (2007).

    Article  Google Scholar 

  18. Smith, K. L. Jr et al. Carbon export associated with free-drifting icebergs in the Southern Ocean. Deep-Sea Res. II 58, 1485–1496 (2011).

    Article  Google Scholar 

  19. Shaw, T. J. et al. Input, composition and potential impact of terrigenous material from free-drifting icebergs. Deep-Sea Res. II 58, 1376–1383 (2011).

    Article  Google Scholar 

  20. Smith, K. L. Jr et al. Icebergs as unique Lagrangian ecosystems in polar seas. Ann. Rev. Mar. Sci. 5, 269–287 (2013).

    Article  Google Scholar 

  21. AGS Tectonic Map of Antarctica (Antarctic Map Folio Series, Folio 12-Geology, Amer. Geogr. Soc., 1970).

    Google Scholar 

  22. Rignot, E. et al. Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise. Geophys. Res. Lett. 38, L05503 (2011).

    Article  Google Scholar 

  23. Paolo, F. S., Fricker, H. A. & Padman, L. Volume loss from Antarctic ice shelves is accelerating. Science 348, 327–331 (2015).

    Article  Google Scholar 

  24. Staham, P. J., Skidmore, M. & Tranter, M. Inputs of glacially derived dissolved and colloidal iron to the coastal ocean and implications for primary productivity. Glob. Biogeochem. Cycles 22, GB3013 (2008).

    Google Scholar 

  25. Bigg, G. R., Marsh, R. A., Wilton, D. J. & Ivchenko, V. B31—a giant iceberg in the Southern Ocean. Ocean Challenge 20, 32–34 (2014).

    Google Scholar 

Download references

Acknowledgements

Much of this work followed from the MSc dissertation of L.P.A.M.D. We also acknowledge support for part of the work from the Natural Environment Research Council Urgency Grant NE/L010054/1, ‘Tracking and prediction of the giant Pine Island iceberg’, and SAR images from the German Aerospace Center Projects OCE2116 and 2184 and the European Space Agency project 16456. We wish to thank the Canadian Space Agency for providing the data from the latter ESA project. We also wish to thank E. Victor, who helped L.P.A.M.D. with some of the statistics, and J. Thompson, whose MSc research brought the comparisons shown in Fig. 3 to our attention.

Author information

Authors and Affiliations

Authors

Contributions

G.R.B. and L.P.A.M.D. conceived the project; L.P.A.M.D. carried out much of the analysis and assisted with writing; G.R.B. contributed to the analysis and was the principal writer of the final manuscript. D.J.W. carried out some of the tracking work shown in Fig. 3, and commented on the manuscript.

Corresponding author

Correspondence to Grant R. Bigg.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 425 kb)

Supplementary Information

Supplementary Information (XLSX 14 kb)

Supplementary Information

Supplementary Information (XLSX 14 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Duprat, L., Bigg, G. & Wilton, D. Enhanced Southern Ocean marine productivity due to fertilization by giant icebergs. Nature Geosci 9, 219–221 (2016). https://doi.org/10.1038/ngeo2633

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/ngeo2633

Further reading

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing