ANNAPOLIS (April 30, 2009) — Bay grasses, a favorite home to the blue crab, increased 20 percent in 2008 in Maryland’s portion of the Chesapeake Bay and its tributaries. The majority of the 7,221-acre increase resulted from a continued expansion on the Susquehanna Flats, home of the largest bay grass beds in the Chesapeake Bay. While the new number — 42,237 acres (up from 35,016 acres in 2007) — marks a significant increase, Maryland bay grass acreage remains far short of the 2010 restoration goal of 110,000 acres.
Bay grasses, or submerged aquatic vegetation (SAV) are critical to the Chesapeake by providing food and shelter for a wide range of fish, shellfish and waterfowl including largemouth bass, blue crabs and the canvasback duck. Healthy bay grass beds also protect shorelines from erosion, produce oxygen, remove excess nutrients from the water and trap sediment that would otherwise cloud the water.
“Because bay grasses are sensitive to even minor changes in water quality, they serve as a key indicator of the health of our waterways,” said Natural Resources Secretary John Griffin. “So, while these increases are good news for some portions of the Bay, there are still places where poor water quality continues to restrict recovery.
Maryland’s increase in bay grass acreage has been driven by the Susquehanna Flats beds, which now cover about 15,000 acres or about 23 square miles. The Flats, located at the top of the Chesapeake Bay, is actually a delta formed below the mouth of the Susquehanna River near Havre de Grace. These thriving beds are home to over 12 different types of bay grasses.
Increasing in size since 1991, these vast beds have also become more dense. Today they act like a giant water filter, often producing visibility up to eight feet, a level unrivaled in other areas of the Bay. These substantial increases have co-occurred with long-term reductions in nitrogen loads reaching the Bay at the Susquehanna River as confirmed by State monitoring.
In addition to the remarkable growth on the Susquehanna Flats, bay grasses in the Elk River increased nearly 20 percent to 2,347 acres meeting its acreage goal for the first time in 2008. Expansion of bay grass beds in the Northeast River continued a 3-year trend, increasing an additional 60 percent to 182 acres in 2008, far exceeding the 89-acre goal for the river.
Numerous other areas have also met bay grass restoration goals for several years now, including the Bohemia, Bush and upper Potomac Rivers, and Mattawoman Creek, though grass in the Bohemia and Bush have been declining in recent years. Also encouraging, bay grasses in the middle Patuxent and Middle Rivers, Piscataway Creek, and the upper Chesapeake Bay directly below the Susquehanna Flats are all approaching their restoration goals.
Grasses in the Potomac River — from near the Woodrow Wilson Bridge south to about Mattawoman Creek — have shown steady increases since 2000, and have exceeded the restoration goal by 47 percent. This is due in part to major upgrades in wastewater treatment at the Blue Plains Facility in Washington, DC. Long-term water quality monitoring has confirmed reduced levels of nitrogen in the Potomac River since the partial wastewater treatment plant upgrade in 1996 and the full upgrade was completed in 2000.
Increases in bay grass coverage on Maryland’s lower Eastern Shore were driven primarily by the recovery of eelgrass, a higher salinity-tolerant type of bay grass, after significant reductions in eelgrass populations resulting from a bay-wide dieback in 2005. Several regions, including Tangier and Pocomoke Sounds and the Manokin and Big Annemessex Rivers, have seen increases in eelgrass since 2006. In the Honga River, bay grass acreage nearly doubled in 2008 due to a resurgence of widgeon grass, another type of bay grass tolerant of saltier waters.
Despite this encouraging progress, other Bay areas are showing steady declines in bay grass acreage. Poor water quality continues to hamper bay grass recovery in the middle zone (Kent Island south to the Potomac and Pocomoke Rivers). Several regions, including the Choptank, Little Choptank and lower Potomac Rivers, continue to experience substantial declines in bay grass acreages.
Bay grasses acreage is estimated through an aerial survey, which is flown from late spring to early fall. Additional information about the aerial survey and survey results, is available at http://www.vims.edu/bio/sav/ .
Source: Maryland Dept. of Natural Resources (DNR)