Sallie W. Chisholm
Encyclopedia
Sallie W. Chisholm is a U.S. biological oceanographer
Marine biology
Marine biology is the scientific study of organisms in the ocean or other marine or brackish bodies of water. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather...

. She attended Skidmore College
Skidmore College
Skidmore College is a private, independent, liberal arts college with an enrollment of approximately 2,500 students. The college is located in the town of Saratoga Springs, New York State....

 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
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...

, where she is the McAfee Professor of Engineering.

Chisholm's research has focused on the ecology of marine phytoplankton
Phytoplankton
Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...

. 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
Flow cytometry
Flow cytometry is a technique for counting and examining microscopic particles, such as cells and chromosomes, by suspending them in a stream of fluid and passing them by an electronic detection apparatus. It allows simultaneous multiparametric analysis of the physical and/or chemical...

 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
Prochlorococcus
Prochlorococcus is a genus of very small marine cyanobacteria with an unusual pigmentation . These bacteria belong to the photosynthetic picoplankton and are probably the most abundant photosynthetic organism on Earth....

and Synechococcus
Synechococcus
Synechococcus is a unicellular cyanobacterium that is very widespread in the marine environment. Its size varies from 0.8 µm to 1.5 µm...

) 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
Nitrogen cycle
The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out by both biological and non-biological processes. Important processes in the nitrogen cycle include fixation, mineralization, nitrification, and denitrification...

.

Chisholm has been a member of the United States National Academy of Sciences
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...

 (NAS) since 2003. In January 2010, she was awarded the Alexander Agassiz Medal
Alexander Agassiz Medal
The Alexander Agassiz Medal is awarded by the U.S. National Academy of Sciences for an original contribution in the science of oceanography. It was established by Sir John Murray in honor of his friend Alexander Agassiz.-Recipients:-References:NotesA...

, for "pioneering studies of the dominant photosynthetic organisms in the sea and for integrating her results into a new understanding of the global ocean." In recent years, she has played a visible role in opposing the use of iron fertilization
Iron fertilization
Iron fertilization is the intentional introduction of iron to the upper ocean to stimulate a phytoplankton bloom. This is intended to enhance biological productivity, which can benefit the marine food chain and remove carbon dioxide from the atmosphere. Iron is a trace element necessary for...

 as a technological fix
Technological fix
A technological fix or technical fix refers to an engineering or technical solution to a problem caused by human nature. Frequently the solution is an impractical and/or humorous proposal such as the Internet Protocol Evil bit or the "suitable application of high explosives" to interpersonal problems...

 for anthropogenic climate change.

See also

  • Prochlorococcus
    Prochlorococcus
    Prochlorococcus is a genus of very small marine cyanobacteria with an unusual pigmentation . These bacteria belong to the photosynthetic picoplankton and are probably the most abundant photosynthetic organism on Earth....

  • Synechococcus
    Synechococcus
    Synechococcus is a unicellular cyanobacterium that is very widespread in the marine environment. Its size varies from 0.8 µm to 1.5 µm...

  • Carbon cycle
    Carbon cycle
    The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth...

  • Global warming
    Global warming
    Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...


External links



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