Hurricane's effects on bay studied

Early indications are that storm was not a disaster for the Chesapeake

November 14, 1999|By Jeff Long | Jeff Long,KNIGHT RIDDER/TRIBUNE

NEWPORT NEWS, Va. -- Scientists have been sampling the Chesapeake Bay and its tributaries to gauge the effects of Hurricane Floyd.

"There aren't massive signals screaming out: 'This was a catastrophic event,' " said Linda Schaffner, an associate professor in the department of biological sciences at the Virginia Institute of Marine Science. Schaffner and her colleagues are looking at levels of salt, mud and nutrients in the wake of the Sept. 16 storm.

Not enough or too much

Not enough of one or too much of the others can cause problems for bay and river creatures and for the watermen who depend on them for a living.

Oysters, for example, might be buried in their beds by mud sediment. Or, they might suffer from the freshwater that dilutes the saltwater that oysters need to survive.

Sea grass, which provides a habitat for young fish and crabs, could be harmed by the lack of light and oxygen caused by algae, which thrive and multiply on the nutrients carried from the land by floodwater.

The sea grass could also be smothered by sand, according to the institute's Robert Orth, a professor in the department of biological science.

Waiting for spring

Orth said Floyd's impact on sea grass won't be fully known until spring. Growth normally slows at this time of year, making the effect hard to see now. He expects the effect to be small, however.

Not everything about a storm such as Floyd is bad. Storms can wash algae out to sea.

And oysters do better in less salty water than the diseases that attack them, according to Roger Mann, a professor at the Virginia Institute of Marine Science. Readings so far seem to say that saltwater hasn't been diluted enough to harm oysters.

Although scientists will be studying the data for months, early signs suggest that the damage hasn't been disastrous. The bay has seen hurricanes before.

Remembering Agnes

Compare Floyd with Agnes, which swept farther inland during its 1972 rampage.

"That was a monster event and had very significant, baywide implications," said Ward Staubitz of the U.S. Geological Survey office in Richmond, Va.

Agnes brought more nutrients, pollutants, mud and freshwater to dilute saltwater than Floyd, and did more harm than Floyd.

There's a difference between modern hurricanes and those that buffeted the bay in the few thousand years before people began changing the landscape around it, Schaffner and others noted. The water that floods into the bay today carries things with it that it didn't before: nutrients from farmland, the fertilizer from your lawn or pollutants from your vehicle.

And the water makes its way into the bay more easily than before, since there are fewer wetlands to soak it up.

The Geological Survey, part of the Department of the Interior, studies how much water storms such as Floyd and Agnes dump into the bay.

Agnes moved farther inland than Floyd did, so its floodwaters traveled farther on their way to the bay, picking up more nutrients and pollutants along the way.

Staubitz and Schaffner say that with Floyd, the nutrient runoff seems to have been confined mainly to the Tidewater area.

Any influx of nutrients isn't good for the Chesapeake Bay, which already has too many nutrients, the scientists say, but Floyd's impact hasn't been as bad as it could have been. Staubitz and Schaffner said that's because the storm didn't travel so far through the lands that drain into the bay. (That area, or watershed, is huge. It stretches as far as New York and West Virginia.)

Robert Brumbaugh, a fisheries scientist with the Chesapeake Bay Foundation, said runoff from even a relatively small geographic area is growing worse because of the amount of wetlands that continue to be developed.

Wetlands act like a sponge, he explained. They once soaked up more of the nutrients that now are washed into the bay. As the number of wetland acres shrinks, so does the sponge.

So, more nutrients drain from smaller areas of land.

"Think of it as a dramatic over-fertilization of the bay," Brumbaugh said.

The foundation is an advocacy group working to improve the health of the bay. Preservation of those sponge-like wetlands is among the group's top priorities.

Meanwhile, the Virginia Health Department put a stop to the harvest of oysters, clams and mussels after Floyd because of polluted runoff such as the coliform bacteria that contaminate sewage.

But that runoff was expected to be flushed out to sea by now, according to John Alman, field director in the department's Division of Shellfish Sanitation.

Baltimore Sun Articles
|
|
|
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.