"'Dead Zones' Appear In Waters WorldwideNew Study Estimates More Than 400
By Joel AchenbachWashington Post Staff Writer Friday, August 15, 2008; Page A02
...the number of oxygen-starved 'dead zones' in coastal waters around the world has roughly doubled every decade since the 1960s, killing fish, crabs and massive amounts of marine life at the base of the food chain, according to a study released yesterday.
...Low oxygen, known as hypoxia, is in significant measure a downstream effect of chemical fertilizers used in agriculture. Air pollution, including smog from automobiles, is another factor. The nitrogen from the fertilizer and the pollution feeds the growth of algae in coastal waters, particularly during summer.
The result is feast-then-famine: The algae eventually die and sink to the bottom, where the organic matter decays in a process that robs the bottom waters of oxygen. The ensuing die-off of marine life cuts down on the productivity of commercial fisheries. The 'biomass' missing because of depleted oxygen in the Chesapeake Bay, Diaz estimated, is enough to feed half the number of crabs that are commercially harvested in a typical year.
Hypoxia has been seen for decades in such places as the Chesapeake, Lake Erie, the Gulf of Mexico and Long Island Sound...
...government reports has identified many new zones, including in the Florida Keys, Puget Sound and tidal creeks in the Carolinas.
...the chaos in the planet's nitrogen cycle is not only creating dead zones but also inciting the spread of toxic organisms, such as the pfiesteria that has appeared in recent years in the Chesapeake.
Earlier this week, the Proceedings of the National Academy of Sciences published online a study warning of 'mass extinction in the oceans with unknown ecological and evolutionary consequences.'
The author, Jeremy Jackson, a professor at the Scripps Institution of Oceanography, contends that global warming, overfishing, invasive species, habitat destruction and agricultural runoff are creating oceans crammed with algae and jellyfish -- a process he calls 'the rise of slime.'
http://www.washingtonpost.com/wp-dyn/content/article/2008/08/14/AR2008081401910.html
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