Phytoplankton are the basis of nearly all the Ocean’s ecosystems, and require a wide range of inorganic nutrients in order to grow; notably Carbon, Nitrogen and Phosphorous. They take up these nutrient elements according to the Redfield Ratio of C : N : P = 106 : 16 : 1. But phytoplankton also require less obvious nutrients such as calcium, magnesium and potassium. These are often in plentiful supply in the worlds Oceans, and other factors such as the micronutrient Iron can be the limiting Phytoplankton growth factor. Iron is not required by Phytoplankton in large amounts, but the Oceans are deficient of this micronutrient, and without it Phytoplankton cannot grow and reproduce as readily. This is because Iron is required in the biosynthesis of the pigment chlorophyll, required by Phytoplankton in order to photosynthesise. With a deficiency in Iron, Phytoplankton can suffer from a lack of chlorophyll known as chlorosis. The protein ferredoxin contains Iron and is substituted for flavodoxin as an iron-stress response (when Iron levels are low). It can be shown that Phytoplankton are Iron deficient by measuring how much of this electron transfer protein flavodoxin is present.
Iron’s role in phytoplankton growth was first identified in the 1930’s by an English biologist named Joseph Hart. However it was not until 1988 when the Iron Fertilisation Hypothesis was suggested, in an article in the January edition of the scientific journal Nature. It was submitted by John Martin who