Underwater grasses in the Chesapeake Bay were more plentiful again last year, with the important habitat-providing plants now covering about double the acreage they did when the survey began in 1984.
ANNAPOLIS, Md. — Underwater grasses in the Chesapeake Bay were more plentiful again last year, with the important habitat-providing plants now covering about double the acreage they did when the survey began in 1984.
Acreage of the bay grasses, however, is still less than half what biologists say it should be.
The survey was released Thursday by the U.S. Environmental Protection Agency's Chesapeake Bay Program. It was the result of months of aerial photos taken when skies were clear and the tide was low, giving scientists their best look at plants living on the bottom. The 2,000 photos were then entered into a mapping program to create an estimate of total acreage.
The 2005 map shows that grasses covered 78,260 acres, up 7 percent from 2004. But the coverage is less than half of the goal of 185,000 acres by 2010.
Bob Orth, project leader of the survey, said vegetation is an important measure of the bay's water quality.
"Bay grasses are the canaries of water quality," said Orth, who works with the Virginia Institute of Marine Science at the College of William and Mary in Williamsburg.
Submerged grasses provide habitat for blue crabs, rockfish and other dominant species in the Chesapeake. They also filter harmful nitrogen out of the water. But too much nitrogen and cloudy water has led to a decline in the grasses from historical levels.
Orth said the 2006 survey may not look as good because warm waters caused an eelgrass kill-off in the lower bay. Bay pictures are taken May through October, then the map is graphed, so it takes almost a year to figure out grass trends baywide.
Despite the recent uptick in bay grasses, the goal of 185,000 acres is unlikely to be attained, said Mike Naylor, a biologist for the Maryland Department of Natural Resources who specializes in the vegetation.
Bill Goldsborough, a senior scientist from the private Chesapeake Bay Foundation, called the survey encouraging, saying it's proof that bay species can rebound when pollutants are reduced. But he said the prospect of full revival for the grasses will require more drastic changes from humans.
Air pollution, residential sewage and agricultural runoff all are sources of pollutants washing into the bay.
"The bay is very resilient," Goldsborough said. "The grasses could do it in a more permanent fashion if we redouble our efforts to reduce nitrogen coming in."
Source: Associated Press
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