HAMPTON, Va. — It’s rare good news for the Chesapeake Bay.
Scientists say the huge sediment plume that formed in the bay after Hurricane Irene and Tropical Storm Lee did not cause the widespread damage they had feared.
The plume stretched dozens of miles and was of particular concern to the Susquehanna Flats, the area where the Susquehanna River meets the bay. The Daily Press of Newport News, Va., reported that scientists feared the plume would destroy underwater grass beds that serve as a feeding and nesting place for blue crabs and other organisms.
“We were incredibly surprised at how much of the grass beds remained on the Flats,” Robert Orth, a Virginia Institute of Marine Science professor, said in a statement issued by the Chesapeake Bay Program.
Oysters, however, did not fare as well.
One Maryland scientist blamed the plume in part for nearly 80 percent of the bivalve deaths on the four northernmost oyster bars along the Eastern Shore. Low salinity rates during the spring and early summer also played a role, said Mike Naylor, Maryland Department of Natural Resources’ shellfish program director.
“This is a setback for the upper bay,” Naylor said.
Scientists expected the sediment to move down the bay — along the mouths of the Potomac, Rappahannock, York and James rivers — over the fall and winter. A planned oyster survey next year in Maryland and Virginia waters should give them a better idea how much the plume affected oysters.
When Irene and Lee swept through the region in late August and early September, their winds brought 32 inches of rain to the bay’s 64,000-acre watershed, according to the National Oceanic and Atmospheric Administration. The deluge led to the third-highest water flow ever recorded at Maryland‘s Conowingo Dam, north of Havre de Grace.
Rainfall helps carry sediment and other debris, fertilizer and sewage to the bay. Sediment is among the bay’s chief pollutants, along with excessive amounts of nitrogen and phosphorus.
Scientists feared the plume would prevent sunlight from reaching the grass beds, suffocating them. But aerial surveys in November indicate that didn’t happen to the levels they had expected. There was some decline along the edges of the beds, Orth said.
Ducks and geese that stopped by the Flats on their migration south supported the scientists’ findings.
“The fact that we’re now seeing overwintering waterfowl in our photographs is a good sign that lots of food is available there now,” Orth said.