Sallie W. (Penny) Chisholm is a biological oceanographer. She attended Skidmore College and received her Ph.D. from the SUNY Albany in 1974. Since 1976 she has been a member of the faculty at the Massachusetts Institute of Technology where she is the McAfee Professor of Engineering. Chisholm's research has focused on the ecology of marine phytoplankton. Her early work focused on the processes by which such plankton take up nutrients and the manner in which this affects their life cycle on diurnal time scales. This led her to begin using flow cytometry which can be used to measure the properties of individual cells. The application of flow cytometry to environmental samples led Chisholm and her collaborators (most notably R.J. Olson and H.M. Sosik) to the discovery that small plankton (in particular Prochlorococcus and Synechococcus) accounted for a much more substantial part of marine productivity than had previously been realized. Previously, biological oceanographers had focused on silicaceous diatoms as being the most important phytoplankton, accounting for 10-20 gigatons of carbon uptake each year. Chisholm's work showed that an even larger amount of carbon was cycled through these small algae, which may also play an important role in the global nitrogen cycle. Chisholm has been a member of the United States National Academy of Sciences since 2003. In recent years, she has played a visible role in opposing the use of iron fertilization as a technological fix for anthropogenic climate change.
References
Chisholm, S.W., P.G. Falkowski, and J.J. Cullen. Dis-Crediting Ocean Fertilization. Science 294:309-310, 2001. Chisholm, S.W., R.J. Olson, E.R. Zettler, R. Goericke, J. Waterbury, and N. Welschmeyer. A novel free-living prochlorophyte abundant in the oceanic euphotic zone. Nature, 334(6180):340-343, 1988. Olson, R.J., D. Vaulot and S.W. Chisholm. Marine phytoplankton distributions measured using shipboard flow cytometry. Deep-Sea Res., 10:1273-1280, 1985. Olson, R.J., S.L. Frankel, S.W. Chisholm and H.M. Shapiro. An inexpensive flow cytometer for the analysis of fluorescence signals in phytoplankton: Chlorophyll and DNA distributions. J. Exp. Mar. Biol. Ecol., 68:129-144, 1983.
