Oceanic phytoplankton produces half of Earth’s primary production, and as such is critical in the carbon cycle. In shallower seas, upwelling of deeper nutrient-rich water fuels growth, but in deeper waters their limiting nutrient is often iron. Deposition of iron-containing mineral dust can often be the main source of limited micronutrients. However, much of the iron in such dust is locked away as biounavailable Fe3+. Little is known of the mechanism of how phytoplankton reduces Fe3+ to Fe2+, or how it sequesters iron. This study aims to determine if this method involves a primary dust/protein complex; either secreted by the phytoplankton or contained on the cell membrane. Biomarker studies were conducted in which phytoplankton cultures were isolated from a mineral dust Fe source by a cellulose dialysis tube in iron-deficient environments. Colorimetric analyses of phytoplankton were conducted to quantify biomass in terms of the chlorophyll a concentration using the tri-chromatic method and UV-Vis spectroscopy. Growth rates were determined as a measure of colony efficacy. Preliminary results suggest that a primary protein iron complex is not necessary for the sequestration of iron from the separated iron containing dust. Siderophore action is suspected.

Exploring the mechanism for iron uptake by phytoplankton: A biomarker study

249th National Meeting (2015)

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