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Penny Chisholm    

Award-Winning Oceanographer

Sallie W. (Penny) Chisholm is a U.S. biological oceanographer at the Massachusetts Institute of Technology. She is an expert in the ecology and evolution of ocean microbes.

Chisholm graduated from Marquette Senior High School in Marquette, MI in 1965. She attended Skidmore College and earned a Ph.D. from SUNY Albany in 1974.

Chisholm has been a faculty member at the Massachusetts Institute of Technology since 1976. Her research has focused on the ecology of marine phytoplankton.[2] Chisholm's 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 timescales. 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.

In recent years, Chisholm has played a visible role in opposing the use of iron fertilization as a technological fix for anthropogenic climate change.

Chisholm has been a member of the United States National Academy of Sciences (NAS) since 2003. Chisholm received the National Medal of Science from President Barack Obama on February 1, 2013.

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