Aug 14

A global map of “dead zones”—where coastal waters contain too little oxygen to sustain life—shows (as black dots) a concentration in the Northern Hemisphere, where human activity has had the most effect.
As of August 2008, there were more than 400 known “dead zones,” scientists said, up from just over 300 in the 1990s. Image courtesy Science/AAAS

“Dead zones” are on the rise, says a new study that identified stark growth in the number of coastal areas where the water has too little oxygen to sustain marine life.

There are now more than 400 known dead zones in coastal waters worldwide, compared to 305 in the 1990s, according to study author Robert Diaz of the Virginia Institute of Marine Science.

Related article: Are the oceans giving up?

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Apr 06

Studies seem to indicate that oceans, which are major carbon sinks, may have had enough. If so, the consequences are BAD, writes Jayalakshmi K.

Ocean deserts, which are non-productive areas, have increased by 15 per cent in the period 1998-2007, according to a study done by the National Oceanic and Atmospheric Administration (NOAA) in the US and the University of Hawaii. This translates into a total of 6.6 million sq km. On the whole, there are 51 million sq km of such desert zones. The data was collected by Nasa’s orbiting SeaStar craft.

Attributed mostly to warming surface waters, which is happening at a rate of 1 per cent every year, this creates many layers in the ocean waters, preventing deep ocean nutrients from rising to the surface and feeding plant life.

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