Dead zones spread across world’s oceans

Critically low oxygen levels in global coastal waters pose as great a threat to life as overfishing and habitat loss, the Guardian reported experts as saying. Manmade pollution has created more than 400 oxygen-starved dead zones in the world's oceans, with disastrous consequences for marine life.
There were some 405 recorded in coastal waters worldwide in 2007, up from 305 in 1995 and 162 in the 1980s, the report said. The zones are caused when massive algal blooms feeding off pollutants such as fertiliser die and decay.
"Dead zones were once rare," the report quoted Robert Diaz, from the US Virginia Institute of Marine Science, as saying. "Now they’re commonplace. There are more of them in more places."

Writing in the journal Science, the researchers say the dead zones must be viewed as one of the "major global environmental problems".
They say: "There is no other variable of such ecological importance to coastal marine ecosystems that has changed so drastically over such a short time."

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