'Average to Below Average' Dead Zone Predicted for 2016 in Chesa - WBOC-TV 16, Delmarvas News Leader, FOX 21 -

'Average to Below Average' Dead Zone Predicted for 2016 in Chesapeake Bay

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CAMBRIDGE, Md.- The Chesapeake Bay may look like one simple ecosystem, but there are actually a few layers at work.  In simple terms, there are surface fish like striped bass, and bottom fish like flounder and crabs.  The dead zone is in that lower layer.

"There are regions in the bay, mostly during the summer, where there is little dissolved oxygen in the water, and there are regions of the bay where there is no dissolved oxygen in the water," said Dr. Michael Kemp, a professor at the University of Maryland Center for Environmental Science.

These areas are aptly named dead zones, since very little can live there.  This year, the dead zone is estimated to be 2.3 million Olympic-sized swimming pools worth of water along the bottom of the bay, about average.  It's caused by nutrients like phosphorous and nitrogen running off the land and into the bay, feeding algae.

"Nutrients fertilize algae.  Algae block light to submerged plants, and they also sink to the bottom and decompose, and as they decompose, they consume oxygen," Kemp said.

In other words, a dead zone can grow itself larger.  But Kemp said it can also shrink itself.

"On the other side of the coin, when things are getting better and we are on the recovery trajectory, this feedback cycle is going to accelerate recovery.  The case can be made that is what's happening right now," he said.

Kemp said there has been a gradual reduction in the size of the dead zone in the past few years, fed partially by varying short term causes, but also long-term changes.

"That variation is also supported by a long term trend which we have just recently picked up on, which is a decline in nutrients,"  Kemp said.

With less nutrients, you get a smaller dead zone, and thus a healthier bay.

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