Arrigo is an assistant professor of geophysics, and van Dijken is a science and engineering associate in the department. In a study published in the American Geophysical Union's Geophysical Research Letters, the authors described how C-19 drifted northward from May until November 2002, when it apparently ran aground. By January 2003, the iceberg had become trapped against a shallow bank, eventually forming a perpendicular barrier that prevented sea ice from moving out of the southwestern Ross Sea for the next three months -- a crucial time of year when tons of microscopic marine algae, called phytoplankton, normally bloom in open water.
Phytoplankton are a major food source for krill, which in turn are consumed by fish, seals, penguins and whales. Without massive amounts of phytoplankton, the entire food chain in the Ross Sea can collapse.
Like plants, phytoplankton grow through the process of photosynthesis, using chlorophyll to convert sunlight into food. But unusually high levels of sea ice will block sunshine, preventing phytoplankton from growing.
Green waters
To determine phytoplankton production levels in the Ross Sea, the researchers examined data from SeaWIFS -- the Sea-viewing Wide Field-of-view Sensor aboard NASA's SeaStar satellite.
"SeaWIFS measures the amount of light coming out of the ocean at different wavelengths," noted Arrig
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Contact: Mark Shwartz
mshwartz@stanford.edu
650-723-9296
Stanford University
3-Oct-2003