Environmental Science and Engineering Seminar

Global satellite observations document expansions of the low-chlorophyll central ocean gyres and an overall inverse relationship between anomalies in sea surface temperature and phytoplankton chlorophyll concentrations.  These findings can provide an invaluable glimpse into potential future ocean changes, but only if the story they tell is accurately interpreted.  Chlorophyll is not simply a measure of phytoplankton biomass, but also registers changes in intracellular pigmentation arising from light-driven (photoacclimation) and nutrient-driven physiological responses.  These physiological responses can be characterized globally using advanced in remote sensing capabilities and through informed interpretations of satellite products using field and laboratory data.  In this presentation, I will focus on developments regarding the characterization of photoacclimation in the surface ocean mixed layer and on the unique consequences of iron stress.  Results suggest that these two physiological responses can be dominant drivers of observed temporal anomalies in global chlorophyll data, with important implications on how chlorophyll changes relate to changes in phytoplankton biomass and net primary production.