Posted on 04/23/2002 11:36:10 PM PDT by Vigilant1
18:30 23 April 02
NewScientist.com news service
Colossal icebergs that fractured away from an Antarctic ice shelf in 2000 have dramatically reduced the growth of sea phytoplankton in a region of the Ross Sea. Scientists fear this could disrupt the food chain is this biologically rich area.
Satellite data shows the volume of phytoplankton in the southwestern Ross Sea fell by about 40 per cent between March 2000, when the icebergs broke away from the Ross Ice Shelf, and December 2001. A single iceberg measuring 10,000 square kilometers first sliced away from the shelf before breaking into smaller icebergs.
The icebergs became grounded on the sea floor about 100 kilometres from the ice shelf. This has blocked pack ice from flowing out into the sea. But plankton need open water and direct sunlight to survive.
"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," says Kevin Arrigo, of Stanford University.
Chain reaction
Phytoplankton forms the foundation of the local food chain and scientists fear the reduction could have an impact on populations of marine mammals and birds, including penguins.
"It is potentially going to have an effect on lower levels of the food change and you can imagine it will have an impact further up," says John Rodhouse, head of biological sciences at the British Antarctic Survey.
Thorsten Markus of NASA's Goddard Space Flight Center says that climate change could make this event happen more frequently. "Statistically these icebergs are breaking away more frequently," he says "Which may mean that this sort of scenario will happen more frequently."
He says that determining whether the icebergs causing the blockage might dislodge is very difficult.
Images illustrating the reduction in phytoplankton were captured using NASA's Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite and the US Defense Meteorological Satellite Program. Data from the satellites was used to measure chlorophyll - a key component of phytoplankton.
Details of the research will be published in the next issue of Geophysical Research Letters.
And just exactly how long have we been keeping accurate statistics on the number of icebergs breaking off of Antarctica?
There has been complete surveillance of the Antarctic and icebergs since we had geophysical satellites observing the Earth's surface, probably since about the mid-1960s. There is also data from scientific expeditions and iceberg patrols going back to at least the pre-WWII period.
Now the rats and rinos are out in full force as usual to confiscate from those who produce and grow more rats with the proceeds.
Egghead enviromentalists frequently make stupid pronoucements that frequently are wrong. This may mean that this sort of scenario will happen more frequently.
I think these people have way too much time on their hands!
In addition to squandering much in taxpayers dollars too!
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