ANNAPOLIS, MD — Underwater bay grass acreage in Maryland’s portion of Chesapeake Bay suffered a setback in 2003 as a result of reduced water clarity resulting from the record levels of rainfall in many parts of the bay drainage, according to a recent aerial bay grass survey.
Bay grass acreage in Maryland dropped 41%, to 30,990 acres in 2003, the Maryland Department of Natural Resources (DNR) announced today. This is a reduction of nearly 22,500 acres from the record 52,546 acres in 2002. For Maryland and Virginia’s portion of the Bay combined, bay grass acreage in 2003 was 64,709 acres, a 30% decline from 2002. The record rainfall and resulting high river flows of 2003 sent larger than normal amounts of sediments and nutrients into the Bay, clouding the water and reducing the amount of light available for bay grasses.
“These latest results remind us that more needs to be done to reduce nutrient and sediment loadings in Chesapeake Bay,” said DNR Secretary C. Ronald Franks. “We are hopeful that the establishment of Chesapeake Bay Restoration Fund, implementation of the Tributary Strategies, and accelerated bay grass planting and seeding efforts will accelerate our progress toward our restoration goals and a healthier Bay overall.”
Water clarity, which is limiting to bay grasses in even the best of years, was greatly reduced baywide and continues to be the greatest impediment to bay grass recovery.
Bay grasses (also known as “submerged aquatic vegetation” or “SAV”) are a critical resource that provides food and habitat for a wide range of bay species, including crabs, fish, and waterfowl. Bay grasses also protect shorelines from erosion, remove nutrients from the water, produce oxygen, and trap sediments that cloud bay waters.
The bay grass totals are based on an aerial survey conducted annually since 1984 by the Virginia Institute of Marine Science and funded by the U.S. EPA, DNR, and others. Since the inception of the survey, the upper Chesapeake Bay from the Bay Bridge to the Susquehanna River has seen a steady, but slow increase in bay grasses, while the remainder of Maryland’s portion of the bay has not shown the same improvement. At the current levels of progress, Maryland will not meet its 2010 SAV restoration goal of 110,647 acres of bay grasses.
“Restoring bay grasses to historic levels is recognized to be one of the cornerstones of restoring the Chesapeake Bay, and the fact that bay grass levels in Maryland today are below the 1992 acreage is a striking example of how far we have to go to reach that goal,” said Mike Naylor, DNR Biologist and Chair of the Chesapeake Bay Program’s SAV Taskforce.
The vast majority of the losses occurred in the higher salinity areas of Eastern Bay, the lower Choptank and Choptank rivers, the Honga River, and the Tangier Sound. These high salinity areas accounted for nearly 67% of the Maryland declines. The bay grass decreases in the lower Eastern Shore from the Chester River to Tangier Sound appear to be the result of decreases in water clarity in these areas caused by elevated levels of nutrients and suspended solids. These same areas had recorded increases in bay grasses in 2001 and 2002- a result of two consecutive low-rainfall years.
Decreases in water clarity were identified by DNR’s Water and Habitat Quality Monitoring Program. For example, levels of suspended solids doubled, the nutrient nitrogen also showed a substantial increase, and water clarity decreased by nearly 50% in the lower Choptank River, an area that had large bay grass declines. Reduced light levels, resulting primarily from excessive nutrient and sediment inputs, are the single greatest threat to bay grasses in the Chesapeake Bay, and light levels measured throughout Maryland’s portion of the bay showed system wide declines from 2002 to 2003.
Despite the overall reduction in bay grass coverage, several areas recorded their highest levels since the survey began and include the Bohemia, and the middle and upper Patuxent Rivers, and upper Patuxent rivers. Analyses are underway to understand why bay grasses in these rivers increased, while grasses throughout most of the rest of the bay declined.
Nutrient contributions to the upper portion of the Patuxent River are dominated by wastewater treatment plants. Bay grasses in that area subsequently may be less subject to fluctuations in water quality due to rainfall than many other bay tributaries in which nutrients and sediments reach the river primarily via runoff. In a very encouraging development, the West River showed 23 acres of bay grasses in 2003, the first time bay grasses have been recorded on that river since 1994, and may be the result of seeds or propagules that fortuitously made their way into the river last year.
Additionally, the middle Potomac River continued a two year recovery from a record low year in 2001 in which that portion of the river experienced a large decline due to the severe drought of that year, resulting in significantly higher salinities that stressed or killed typically resident freshwater species of bay grasses that live there.
DNR will be greatly accelerating the pace of bay grass restoration in 2004 using a combination of new technologies and the innovative use of conventional equipment. These restoration activities will be focused on unvegetated areas with suitable habitat.
Posted May 18, 2004