Satellite-detected fluorescence reveals global physiology of ocean phytoplankton M. J. Behrenfeld1, T. K. Westberry1, E. S. Boss2, R. T. O'Malley1, D. A. Siegel3, J. D. Wiggert4, B. A. Franz5, C. R. McClain5, G. C. Feldman5, S. C. Doney6, J. K. Moore7, G. Dall'Olmo1, A. J. Milligan1, I. Lima6, and N. Mahowald8 1Dept. of Botany and Plant Pathology, Cordley Hall 2082, Oregon State University, Corvallis, OR 97331-2902, USA 2School of Marine Sciences, 5706 Aubert Hall, University of Maine, Orono, Maine 04469-5741, USA 3Institute for Computational Earth System Science and Department of Geography, University of California, Santa Barbara, CA 93106-3060, USA 4Dept. of Marine Sciences, University of Southern Mississippi, 1020 Balch Blvd., Stennis Space Center, MS 39529-9904, USA 5NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 6Dept. of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution Woods Hole, MA 02543-1543 7Dept. of Earth System Science, 3214 Croul Hall, University of California, Irvine, CA 92697-3100, USA 8Cornell University, 2140 Snee Hall, Ithaca, NY, USA, 14850, USA
Abstract. Phytoplankton photosynthesis links global ocean biology and climate-driven
fluctuations in the physical environment. These interactions are largely
expressed through changes in phytoplankton physiology, but physiological
status has proven extremely challenging to characterize globally.
Phytoplankton fluorescence does provide a rich source of physiological
information long exploited in laboratory and field studies, and is now
observed from space. Here we evaluate the physiological underpinnings of
global variations in satellite-based phytoplankton chlorophyll fluorescence.
The three dominant factors influencing fluorescence distributions are
chlorophyll concentration, pigment packaging effects on light absorption,
and light-dependent energy-quenching processes. After accounting for these
three factors, resultant global distributions of quenching-corrected
fluorescence quantum yields reveal a striking consistency with anticipated
patterns of iron availability. High fluorescence quantum yields are
typically found in low iron waters, while low quantum yields dominate
regions where other environmental factors are most limiting to phytoplankton
growth. Specific properties of photosynthetic membranes are discussed that
provide a mechanistic view linking iron stress to satellite-detected
fluorescence. Our results present satellite-based fluorescence as a valuable
tool for evaluating nutrient stress predictions in ocean ecosystem models
and give the first synoptic observational evidence that iron plays an
important role in seasonal phytoplankton dynamics of the Indian Ocean.
Satellite fluorescence may also provide a path for monitoring
climate-phytoplankton physiology interactions and improving descriptions of
phytoplankton light use efficiencies in ocean productivity models.
Citation: Behrenfeld, M. J., Westberry, T. K., Boss, E. S., O'Malley, R. T., Siegel, D. A., Wiggert, J. D., Franz, B. A., McClain, C. R., Feldman, G. C., Doney, S. C., Moore, J. K., Dall'Olmo, G., Milligan, A. J., Lima, I., and Mahowald, N.: Satellite-detected fluorescence reveals global physiology of ocean phytoplankton, Biogeosciences, 6, 779-794, doi:10.5194/bg-6-779-2009, 2009.