the CROZet natural iron bloom and EXport experiment (CROZEX)
In some parts of the ocean phytoplankton growth is limited by the availability of iron. The CROZEX project tested the hypothesis that iron occurring naturally in the sediments around the Crozet Isles in the Southern Ocean fuels the phytoplankton bloom observed in waters close to the islands. The project also explored the importance of the iron supply for carbon drawdown to the deep ocean.
did the natural iron fertilisation increase carbon export?
The project confirmed that bloom around the Crozet Isles was naturally fertilised by iron from the islands. The flux of sinking organic carbon was also higher beneath the bloom than in the iron-depleted regions nearby.
The synthesis paper, Pollard et al. 2009, published in Nature, triggered varied articles in the mainstream media that can still be found online.
how did the iron alter the biogeochemistry in the region?
Phytoplankton species responded differently during the iron-light incubation experiments. We used these observations to understand how the availability of iron and light is inter-related to concentrations of nitrate, phosphate and silicate in the region.