Ocean 'Dead Zones' Increasing Worldwide

A "dead zone" occurs in the Gulf of Mexico each summer as nutrient build-up leads to drastic reductions in oxygen in bottom waters. Fish and shrimp virtually disappear.

Maritime “dead zones” have expanded steadily over the past half-century, now creating environments where marine life cannot survive in 400 coastal areas of the world.

Writing in the journal Science, researchers from Virginia’s College of William and Mary and Gothenburg University in Sweden have found that the number of oxygen-depleted areas of the sea has doubled every 10 years since the 1960s.

“The formation of dead zones has been exacerbated by the increase in (pollution) ... fueled by riverine runoff of fertilizers and the burning of fossil fuels,” the study said.

Lead author Robert J. Diaz pointed out that dead zones have tended to occur in areas that were historically prime fishing grounds.

Lack of oxygen seasonally wipes out fish and crustaceans in parts of the Gulf of Mexico, Baltic Sea and Chesapeake Bay.

The phenomenon has recently developed off the coast of South China as well as the Pacific Northwest.

Image: NASA
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