An Examination of the Tolerance to Low Iron Conditions among Marine Diatoms (2014)

Undergraduate: Jamal Benjamin

Faculty Advisor: Adrian Marchetti
Department: Environmental Science

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Diatoms are single-celled phytoplanktons that produce approximately 40 of the oxygen in the atmosphere. As they photosynthesize, die, and fall to the bottom of the ocean they also provide a significant carbon sink, further establishing their ecological and biogeochemical importance. In many regions of the ocean, the trace element iron limits the growth of diatoms. In this study, we examined the tolerance to low iron conditions among several diatoms originally isolated from coastal and oceanic environments, including iron-limited regions. The growth rates and photosynthetic efficiencies of the diatoms were measured through an assessment of changes in chlorophyll a fluorescence over time and variable fluorescence kinetics using a Fluorescence Induction and Relaxation (FIRe) fluorometer. Our findings suggest oceanic diatoms are much more tolerant of low iron conditions than their coastal diatom counterparts. In addition, although the oceanic centric diatom Thalasiosira oceanic is often used as a model low-iron tolerant species in iron limitation experiments, our findings suggests the oceanic pinnate diatom Pseduo-nitzchia granii is able to grow as much lower iron concentrations, suggesting further adaptations to coping with iron stress.