From The Vancouver Sun
By Will Dunham

“Dead zones” in coastal waters — regions of ocean floor so deprived of oxygen that most marine life cannot survive — are spreading worldwide at an alarming pace, scientists said on Thursday.

Driving the trend are nitrogen and phosphorous from chemical agricultural fertilizers that reach coastal waters after flowing off farm fields and into streams and rivers, according to the study published in the journal Science.

Nitrogen compounds from burning fossils fuels, particularly from power plants and cars, also are settling back to the ground and eventually wash into coastal waters, they said.

This decade alone, the number of coastal dead zones has risen by about a third to 405 worldwide, with clusters on the coasts of the United States and Europe. Combined, they take up an area of at least 250,000 square km.

The number of dead zones started to approximately double every 10 years starting in the 1960s, the researchers said. There were 301 such dead zones at the end of the 1990s, 132 at the end of the 1980s, 63 at the end of the 1970s and 39 at the end of the 1960s, Diaz said.

The researchers said dead zones must be considered an important source of stress on marine ecosystems, ranking alongside overfishing, habitat loss from human development and harmful algal blooms as global environmental problems.

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