Effect of High CO2 on Photosynthesis and Growth in Marine Phytoplankton Daniel Steurer Morel Lab, Summer 2011
Trichodesmium • Oceanic, non-heterocystous cyanobacteria • Varies from other diazotrophs • Major player in oceanic nitrogen fixation • Primarily located in tropical and sub-tropical oceans • Diurnal, following circadian rhythm in nitrogen fixation
The Issue Fe’ in YBC II = ~200nM Fe’ in GSW = ~1250pM
Conclusions • Varying EDTA levels has a large effect on growth rate of Trichodesmium in YBC II medium • EDTA chelates potentially toxic ions in the relatively ‘dirty’ medium – e.g. copper • YBC II obviously has some previously unnoticed detriments to growth • Other potential unknown effects of the medium could exist
Shown: higher pCO2 yields higher N2 fixation rate in both instances *Grown in YBC II Kranz, 2010
Shown: higher pCO2 yields lower N2 fixation rate in both instances *Grown in GSW Shi and Morel, in prep.
Results / Analysis YBC II, Fe’ = ~200nM Clearly, the iron imbalance outside of the cells is not mimicked within the cells. GSW, Fe’ = ~1250 pM
Thanks to… • Dalin Shi • Francois Morel and co. • Princeton Environmental Institute