|Bay's 'dead zone' is back
Lack of oxygen kills animals in water
While it's not surprising, it's yet another bad sign for the bay.
"All living resources - crabs, fish, oysters, clams - they need oxygen to survive," said Bruce Michael of the Maryland Department of Natural Resources.
When there's not enough oxygen, crabs and fish scuttle and look for better places to live. They can become susceptible to illness.
And critters that live at the bottom and can't move, such as oysters, can die from lack of oxygen.
Bobbing on his Boston Whaler in the middle of the Severn River yesterday afternoon, John Page Williams of the Chesapeake Bay Foundation could see the effects of the dead zone clear as day on his fish finder.
From the surface down to 10 feet, there were plenty of little squiggles indicating fish.
Below that - almost no fish.
Mr. Williams then dropped a handheld meter in the water. At approximately 13 feet, the meter read an oxygen level of 3 mg/liter. While that's not great, that's enough oxygen for shellfish and some fish. Ideal readings are 5 mg/liter or greater.
Then at nearly 20 feet, the meter read 0.6 mg/liter - a level of oxygen so low that almost nothing can survive.
"That's bad," he said.
Mr. Williams said he thinks its a bit early in the year to get such readings. He thinks the oxygen-deprived zone is shallower than in years past, too.
The Severn Riverkeeper Program's water monitoring crew is seeing similar numbers.
Riverkeeper intern Annelies Jane de Groot said there are "disappointingly low" oxygen levels around the entire river.
"It seems that oxygen is not permeating the Severn below 4 meters in depth," she said. Four meters is roughly 13 feet.
It's a similar case on the South River, where riverkeeper Drew Koslow said that seven of his 14 monitoring sites had readings below 5 mg/liter. At this time last year, five of his sites were that low.
Further south, the readings aren't encouraging in the West and Rhode rivers either, according to riverkeeper Bob Gallagher.
While the open areas of the rivers are doing well, the oxygen levels in the creeks and near shore are poor.
"We're seeing readings that seem to be lower than recent years," he said. "It's a little surprising to see this early in the year."
A broader monitoring program is finding evidence of the dead zone out in the open bay as well. "This is the time of year we do experience low dissolved oxygen," said Mr. Michael of the DNR.
Two baywide monitoring cruises in May showed low oxygen areas starting around the Bay Bridge, Mr. Michael said.
As the summer goes on, it's likely to get worse, he said.
"If it stays hot and sunny, this sets up and stays anoxic during the summer," he said.
Later this month, officials will unveil a summer forecast for the bay that will call for an average dead zone. The forecast is put out annually by the federal-state Chesapeake Bay Program, the DNR and the University of Maryland.
While the dead zone might come out as average, that's not good enough for Mr. Williams and the Chesapeake Bay Foundation.
CBF wants more focus on reducing the harmful nutrients that flow into the bay and cause the algae blooms that suck oxygen from the water.
"Is it better or worse? I don't give a damn. It's just bad," Mr. Williams said as he turned the Whaler back toward shore.
"Even if it's average," he added, "average stinks."
(Revised June 2007)