Chesapeake's tributaries also running low on oxygen


At least once a day, Eileen McLellan gets a phone call from a homeowner along the Chester River, wondering about the dead fish washing up under the dock or the funny color of the algae or just the strange smell of the water.

"They call me and ask if the river is dying," said McLellan, who is completing her first year as the Chester Riverkeeper, hired by the Chester River Association. "I tell them it's not dying, but it's very sick."

Around the Chesapeake Bay, zones of low dissolved oxygen are increasingly found far beyond the deep waters of the main channel. They're now reaching tributaries, where residents have rarely seen so much algae and so few crabs and fish.

"The dead zone problem we're seeing on the bay is equally bad in the Chesapeake Bay tributaries," said J. Charles Fox, a vice president for the Chesapeake Bay Foundation. "We don't have the same amount of data that we have in the main part of the bay, but the data we have are showing it's very bad."

The foundation -- which took reporters on a tour near Solomons last week to illustrate low dissolved oxygen in the bay -- followed up yesterday with a look at the bay's smaller tributaries, focusing on Weems Creek and the Severn River near Annapolis.

Scientists say dissolved oxygen is critical for survival of fish and crabs -- low levels can kill them or prompt them to flee to other areas.

Further illustrating this year's problems was a report yesterday by the Maryland Department of Natural Resources confirming the discovery of microcystin toxin in a blue-green algae bloom in the Sassafras River between Cecil and Kent counties.

The microcystin toxin irritates the skin of humans and can be fatal to animals if ingested. State officials said livestock and pets should be kept clear of the Sassafras and recommended that people who come into contact with river water wash off as soon as possible with fresh water.

It is the first discovery of the toxin in Maryland's bay tributaries since 2000. Tests of blue-green algae blooms in several other areas -- including the Bush River and Betterton Beach -- are still outstanding.

"In 2000, like this year, we had an abundance of rainfall, coupled with the nutrients that the rainfall brought into the river," said Peter Tango, a natural resource planner with DNR. He said toxin levels are "above the long-term chronic health and safety guidelines by the World Health Organization. It's not as high right now as it was in 2000, but it's not inconsequential, either."

In addition to producing the toxin, algae blooms help deplete dissolved oxygen by blocking sunlight, which kills underwater grasses that otherwise would produce oxygen. When the algae die, the bacteria that feed on them further deplete the oxygen supply.

Those algae feed on nutrient runoff (primarily nitrogen and phosphorus), which has increased as a result of this year's heavy rainfall after two years of drought. "It's like we're seeing three years of nutrients and sediments go right into the water," said Paula Jasinski, president of the South River Federation.

While oxygen levels typically decline each summer, recent surveys by the U.S. Environmental Protection Agency's Chesapeake Bay Program and the National Oceanic and Atmospheric Administration have found record areas of the bay almost devoid of oxygen and aquatic life.

State monitoring sites along rivers feeding the bay are also finding low oxygen levels. "What this essentially does is take 50 to 60 percent of the river away from fish and crabs," said John Page Williams, the bay foundation's senior naturalist.

While agriculture and wastewater treatment plants are the two largest sources baywide, most nutrients coming into waterways like Weems Creek can be traced to suburban development -- such as fertilizer from homeowners' lawns and sediment from commercial projects.

In Weems Creek yesterday, it wasn't hard to spot the green algae floating near the shore. A seine net used to capture fish and other life in a 10-foot swath off the creek's shoreline found almost nothing but tiny baitfish.

When Bart Jaeger of the bay foundation performed a "bottom grab" by dropping a metal scoop into 10 feet of water, he pulled up a black ooze that lacked any sign of life and was covered with freshly dead algae. The muck's noxious, sulfuric odor was further evidence of the lack of oxygen at the bottom, he said.

Instruments found 2.48 milligrams of oxygen per liter in the water along the bottom -- far below the 5 milligrams that the state recommends for fish and crabs to survive. "That's a pretty stressful environment for everything that's down there," Jaeger said.

In the Severn River, dissolved oxygen readings dropped to similar low levels at about 15 feet. But water moves in and out of the Severn more frequently than in smaller creeks, flushing out algae, nutrients and sediments.

So the bottom grab presented a far different picture -- no foul smell, a few broken clam shells and a lighter brown color without much algae.

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