Underwater bay grasses had a banner year in the upper Chesapeake Bay in 2004, with the largest increases in and around the Susquehanna River.
The multistate Chesapeake Bay Program released results of its annual bay grass survey yesterday, and the findings confirmed what scientists have seen on boat trips along Cecil, Harford and Baltimore county rivers: Multiple species of dense grasses have returned to areas that had been barren for many years.
"The big story is what we've been seeing in the upper Chesapeake Bay, particularly the Susquehanna Flats. When we first started monitoring there, you could barely see a plant," said Robert J. Orth, a biology professor at the Virginia Institute of Marine Sciences who conducts the grass survey, which has been done annually since 1984.
Bay grasses are crucial habitat for crabs, fish and other living things. They function as the canary in the mineshaft - if they can't survive in a particular area of the bay, then other species aren't likely to either. The better the water clarity, the more likely that grasses and the species they attract will be abundant.
Grasses in the upper bay more than doubled since last year, from 10,416 acres in 2003 to 21,654 acres in 2004. To conduct the survey, researchers flew over the grass beds, photographed them, and entered the information into a computer program that generates maps and data charts.
Orth and the researchers attribute the upper bay's success to reductions in nutrient pollution from sewage treatment plants and drier conditions than 2003, when Tropical Storm Isabel dumped lots of sediment into the bay.
The success also is linked to efforts in Pennsylvania and Maryland to reduce runoff from agriculture.
A mysterious kind of algae also may have helped the upper bay's grasses. Though algae often block sunlight and are usually unwelcome, this particular plant covers the grasses like a shag carpet and appears to trap sediment.
In the areas south of the Bay Bridge, where the salinity levels are higher, grasses did not grow as well, according to the survey.
In the middle bay, which includes the Choptank, Nanticoke, Potomac and Patuxent rivers, grasses increased from 30,475 acres in 2003 to 33,719 in 2004.
But in Virginia's portion of the bay, grass acreage dipped from nearly 21,000 in 2003 to about 17,500 last year.
Researchers are beginning to conduct the 2005 bay grass survey. William C. Dennison, a professor at the University of Maryland Center for Environmental Sciences, said he expects to see continued grass growth in the upper bay's fresh waters but only a small recovery in the saltier lower bay.
