BLOOMS AND DEAD ZONES?One concern about iron-fertilized phytoplankton blooms is that they eventually could lead to waters devoid of life?a process that can also occur naturally. In coastal waters off southwest Africa, easterly winds push surface water away from the shore, allowing cold, deep, iron- and nutrient-rich waters to rise to the surface and stimulate blooms, such as this one (the blue-green patch captured by a NASA satellite image) that stretched for hundreds of kilometers off Namibia in November 2007. But when large amounts of marine plants die, bacteria decompose them, using up some of the oxygen available in the water and sometimes creating anoxic ?dead zones? where fish can?t survive. (The MODIS Rapid Response Team at NASA Goddard Space Flight Center)[back]
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