Dead Zones

Ocean Dead zones are spreading.

OSLO (Reuters) - The number of polluted "dead zones" in the world's oceans is rising fast and coastal fish stocks are more vulnerable to collapse than previously feared, scientists said on Monday.

The spread of "dead zones" -- areas of oxygen-starved water -- "is emerging as a major threat to coastal ecosystems globally," the scientists wrote in the journal Proceedings of the National Academy of Sciences.

Such zones are found from the Gulf of Mexico to the Baltic Sea in areas where algae bloom and suck oxygen from the water, feeding on fertilizers washed from fields, sewage, animal wastes and pollutants from the burning of fossil fuels.