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The Expedition ANT-XXV/3

Weekly Reports

22 January 2009: The passage across the South Atlantic

3 February 2009: The search for a suitable eddy and start of the experiment

17 February 2009: Developments in our garden

26 February 2009: What might have, but did not happen

9 March 2009: Watching our garden being grazed

15 March 2009: Keeping up with the patch


Summary and itinerary

The third cruise leg of Antarctic expedition ANT XXV is dedicated to the Indo-German iron fertilization experiment LOHAFEX (LOHA is Hindi for iron, FEX stands for Fertilization EXperiment). The cruise will be jointly carried out by the National Institute of Oceanography (NIO) Goa of the Council of Scientific and Industrial Research, India, and the Alfred Wegener Institute for Polar and Marine Research, member of the Helmholtz Association of German Research Centres. The interdisciplinary team of 48 scientists from India (29), Germany (10), Italy (3), Spain (2), UK (2), France and Chile (1 each) on board “Polarstern” will closely collaborate in monitoring the algal bloom expected to grow in the fertilized patch of ocean and studying its effects on the chemistry and biology for at least 45 days.


In-situ iron fertilization experiments have emerged in the last 10 years as a reliable method for testing biogeochemical and ecological hypotheses not accessible by other means. The interdisciplinary experiment LOHAFEX will test a range of independent yet interconnected hypotheses of which some are mentioned here:


a) The iron hypothesis of John Martin with its geo-engineering corollary.


b) Plankton species composition in an experimental bloom induced in the more productive southwest Atlantic Sector will differ from the plankton in blooms stimulated by previous experiments carried out in low productivity waters. This will have a strong effect on sinking of the bloom and on the ratio of carbon: silica of the sinking flux.


c) Crustacean zooplankton, including krill, is food limited, with its perspectives for explaining the current decline in krill stocks.


d) Iron-fertilized blooms lead to production of noxious gases with harmful effects on the atmosphere.


These, and other hypotheses address fundamental questions of integrated earth system science and biodiversity that are relevant to our understanding of the role of the marine biosphere in past and ongoing climate change as well as of the functioning of marine ecosystems.



Cruise itinerary


• 7. January 2009: Depart from Cape Town, South Africa

• 17. March 2009: Arrive in Punta Arenas, Chile



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Chief Scientists
Victor Smetacek
Wajih Naqvi


Eberhard Fahrbach