Two experiments : IronEx I & II

IronEx I: on addition of Fe there was a rapid increase in primary production - although only sustained for a few days - possibly due to the fact that Fe is rapidly converted into a form that is biologically unavailable. IronEx II - multiple additions of Fe, over several days, were used to simulate a natural Fe input event. A massive phytoplankton bloom was triggered which was not significantly checked by either grazing or secondary nutrient limitation. This bloom significantly reduced CO2 concentrations in the surface layer.