Study Details Atlantic Ocean 'Dead Zones'

In a newly published study, researchers from Germany and Canada describe a number of dead zones recently identified in the tropical North Atlantic

Dead zones are large expanses of oxygen deprived water where little to no life can survive. In a newly published study, researchers from Germany and Canada describe a number of dead zones recently identified in the tropical North Atlantic.

As detailed in the new paper -- published this weekin Biogeosciences, the open access journal of the European Geosciences Union -- the concentrations of oxygen-deficient water develop in eddies. The swirling dead zones accumulate more lifeless water as they churn slowly westward across the open ocean. Their structure is similar to that of a hurricane.

"The fast rotation of the eddies makes it very difficult to exchange oxygen across the boundary between the rotating current and the surrounding ocean," Johannes Karstensen, a researcher at the Helmholtz Centre for Ocean Research Kiel, in Germany,explained in a press release. "Moreover, the circulation creates a very shallow layer -- of a few tens of meters -- on top of the swirling water that supports intense plant growth."

The researchers also discovered that zooplankton, the tiny marine organisms that anchor large ocean-based food chains, congregate on the surface of these drifting dead zones.

Most dead zones are found near the coast, where rivers deltas deliver large concentrations of fertilizers used on inland farms upstream. Fed by the excess phosphorous, the growth of summertime algae blooms accelerate -- sucking the oxygen from large swaths of ocean water. This lifeless water can be swept out to sea, but until now, dead zones have never found in the open ocean.

Source: UPI

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