HEALTH

Irene, Lee dump mud into Chesapeake Bay

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CAPE ST. CLAIRE, Md. (AP) - Back-to-back storms have dumped mud, debris and pollutants into the Chesapeake from across the bay's six-state watershed, creating a brown plume that can be seen from space.

Scientists are now fanning out across the bay's 200 mile length to learn how Hurricane Irene and Tropical Storm Lee have affected the nation's largest estuary, where state and federal officials have struggled for decades to restore populations of crabs, oysters and striped bass.

A Maryland Department of Natural Resources crew aboard the research vessel R/V Kerhin finished two days of water quality sampling in the middle bay on Tuesday. The good news is the storms stirred bay waters, and they didn't find any dead zones where oxygen is too low to support aquatic life, said DNR biologist Laura Fabian. That's a common problem when summer heat fuels algae blooms that suck oxygen from the water once they die and decompose.

"The dead zone is gone," Fabian said.

"But the turbidity is much worse that it was before," said Bruce Michael, DNR's director of resource assessment, using the term scientists use to describe the cloudiness of water.

The acres of floating trash and tree trunks and limbs that had accumulated above the Bay Bridge a week earlier also were gone as Fabian and Michael completed their second day of water quality sampling of the middle bay, finishing just north of the bridge. The water remained cloudy, but the coarser sediments were starting to settle out, Michael said.

"The bay is starting to recover from Tropical Storm Lee and Hurricane Irene," Michael said.

It remains to be seen how long it will take before water clarity is back to levels normally seen in the bay, said Tom Parham, director of DNR's Tidewater Ecosystem Assessment unit.

In the days immediately following Lee, Parham said turbidity in the Susquehanna Flats area of the upper bay was as much as 90 times what biologists say is needed for grasses to survive. Those levels have dropped sharply since then, but are still five to 10 times above the limit.

"How long is it going to be before we get to more normal levels? We just don't know," Parham said.

That is what scientists up and down the bay are trying to determine, and how that will affect species such as oysters. The filter feeders help clean bay waters, but can't move from their reefs on the bay bottom to avoid the sediment working its way downstream.

In addition to Maryland's DNR, researchers from federal agencies such as the U.S. Geological Survey and the National Oceanic and Atmospheric Administration are also monitoring bay conditions.

The Chesapeake Bay Program, the regional federal state partnership that coordinates restoration efforts, said 2011 will most likely be one of the highest annual flow years on record from the Susquehanna River into Chesapeake Bay because of the storms and a wet spring across the watershed. The bay's watershed drains parts of Maryland, Virginia, West Virginia, Pennsylvania, Delaware and New York.

In Virginia, researchers at the Virginia Institute of Marine Sciences say they plan to monitor the plume of muddy water making its way south using a network of sensors that normally track oxygen levels to pick up low oxygen levels due to the plume's arrival.

They are also planning additional monitoring trips.

VIMS researchers are also tracking how the storm will affect bay grasses, which are a key habitat for a number of species and help improve water quality. Professor J.J. Orth said researchers are concerned about how long the sediment plume might last.

Parham said the storms have buried grasses in the northern bay as well as washing some downstream. While the storms have harmed the beds in the northern bay, they also could have a positive impact if seeds from those beds are spread to new areas.

"It could be a good thing," Parham said. "It hurts the beds, but it also could transport seeds to different areas."

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