'Dead Zone' Reappears Off Oregon Coast
US - For the fifth year in a row, unusual wind patterns off the coast of Oregon have produced a large “dead zone,” an area so low in oxygen that fish and crabs suffocate.This dead zone is unlike those in the Gulf of Mexico and elsewhere, which result from fertilizer, sewage or runoff from hog or poultry operations carried by rivers. The Oregon zone appears when the wind generates strong currents carrying nutrient-rich but oxygen-poor water from the deep sea to the surface near shore, a process called upwelling.
The nutrients encourage the growth of plankton, which eventually dies and falls to the ocean floor. Bacteria there consume the plankton, using up oxygen.
Jane Lubchenco, a marine biologist at Oregon State University, said the phenomenon did not appear to be linked to recurring El Niño or La Niña currents or to long-term cycles of ocean movements. That made Dr. Lubchenco wonder if climate change might be a factor, she said, adding, “There is no other cause, as far as we can determine.”
Source: Free Internet Press
8 August 2006
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