Oxygen-deprived `dead zone' spreads over 41% of the bay

August 25, 2005|By Tom Pelton | Tom Pelton,SUN STAFF

The low-oxygen "dead zone" in the Chesapeake Bay spread this month to cover 41 percent of the estuary, the second-worst reading for August in recorded history, according to scientific data released yesterday.

The dismal results followed a report in July from the federal- and state-funded Chesapeake Bay Program that 36 percent of the bay's main section had less than 5 milligrams per liter of dissolved oxygen, a level that ranked among the worst for that month in a quarter-century of monitoring.

"People ought to be outraged by the condition of the Chesapeake Bay," said Will Baker, president of the nonprofit Chesapeake Bay Foundation, an advocacy group. "Our elected officials have got to start making the difficult decisions to reduce pollution, or we are going to end up with a national treasure that doesn't just have dead zones, it's going to be dead, period."

Low-oxygen "dead zones" spread during hot weather, when runoff of farm fertilizer and other pollutants into the bay feed the multiplication of algae. These rot and are consumed by bacteria in a process that deprives the water of oxygen that marine life needs to live.

Rockfish, blue crabs and other species won't die instantly if exposed to slightly less than 5 milligrams per liter of dissolved oxygen, said David Jasinski, water quality data analyst for the University of Maryland Center for Environmental Science. But they don't reproduce as well and can become unhealthy, he said.

More troubling, Jasinski said, is that about 10 percent of the bay had almost zero oxygen during the latest monitoring from Aug. 8 to Aug. 11. These were mostly the deepest sections of the bay, where there was less than 0.2 milligrams per liter of dissolved oxygen, a level that would kill fish, the Chesapeake Bay Program said.

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