NASA-funded research using satellite data has shown large icebergs that have broken off from Antarctica's Ross Ice Shelf are dramatically affecting the growth of minute plant life in the ocean around the region -- plant life vital to the local food chain.
Scientists say the icebergs appear to have caused a 40 percent reduction in the size of the 2000-2001 plankton bloom in one of Antarctica's most biologically productive areas. The icebergs decrease the amount of open water that the plants need for reproduction.
After the calving, or "breaking off," of the B-15 iceberg in March of 2000, researchers used imagery from NASA's SeaWiFS (Sea-viewing Wide Field-of-view Sensor) satellite and data from the Defense Meteorological Satellite Program to see the effect that large icebergs have on phytoplankton (minute floating plants) blooms. The B-15 iceberg that broke off the Ross Ice Shelf and drifted into the southwestern Ross Sea was as large as the state of Connecticut (approximately 10,000 square kilometers or 3,900 square miles)
"This is the first time that satellite imagery has been used to document the potential for large icebergs to substantially alter the dynamics of a marine ecosystem," said Kevin Arrigo, a researcher at Stanford University, Stanford, Calif. Arrigo and his colleagues are publishing their results in a paper titled "Ecological Impact of a Large Antarctic Iceberg," in an upcoming issue of Geophysical Research Letters.
NASA's Thorsten Markus of the Goddard Space Flight Center,
Greenbelt, Md., a co-author on the paper, noted that SeaWiFS
satellite imagery enabled researchers to see that large
icebergs such as the B-15 restricted the normal drift of pack
ice. Normally, when the winds shift, ice is carried out into
the Ross Sea, creating open ocean space and a breeding ground
for phytoplankton. The icebergs, however, created a blockage
that resulted in heavier sprin
Contact: David E. Steitz
NASA/Goddard Space Flight Center