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Underwater Grasses Decline In Maryland’s Coastal Bays
ANNAPOLIS — Bay grass acreage in Maryland’s portion of the Coastal Bays suffered a setback in 2005 and 2006, primarily the result of an eelgrass die-back due to elevated water temperatures in the summer of 2005. Long-term monitoring data has also identified increasing nutrient and chlorophyll trends in this area, which can impact bay grasses as well. The losses were reported today by the Virginia Institute of Marine Sciences (VIMS), which has conducted an annual aerial survey of bay grasses in the Chesapeake and Coastal Bays since the mid 1980s.
Total acreage in Maryland declined nearly 4,000 acres. The combined total loss for Maryland and Virginia dropped nearly 6,500 acres in 2006 to 10,548 acres, a 38 percent reduction from 17,012 acres in 2004.
The annual VIMS survey of the Coastal Bays is funded by the states of Maryland and Virginia and the National Park Service. The survey was not conducted in the Coastal Bays in 2005 due to inclement weather or poor water clarity during specified sampling periods.
The vast eelgrass beds in this area have appeared sparse since the unusually warm summer in 2005, when elevated water temperatures were identified by both Maryland Department of Natural Resources (DNR) and National Park Service water quality monitoring programs.
“Although water temperature appears to have been a major contributor to the recent declines, the lack of any significant increase in bay grasses during the past five years — coupled with degrading water quality trends — is certainly cause for concern,” said DNR Secretary John R. Griffin. “The Coastal Bays Policy Committee will be reviewing draft actions in June aimed at reversing the trends in this area.”
“The majority of these losses occurred in Chincoteague Bay, the site of the Coastal Bays largest underwater grass beds,” said Dave Blazer, Director of the Maryland Coastal Bays Program.
“Eelgrass prefers cool waters, and the Coastal Bays are near the southern extent of its distribution. As a result, any increase in water temperatures can impact populations.”
Similar bay grass decreases observed in the Chesapeake Bay were also attributed to regional record high temperatures.
Since monitoring began in 1986, bay grass acreage has increased fairly steadily from approximately 5,500 acres to over 19,000 acres in 2001. While increased abundance may be related to historically improving water quality trends, acreage has leveled off or declined since 2001, coincident with degrading water quality trends in the southern bays. During this time, bay grass acreage in Sinepuxent, Assawoman and Isle of Wight Bays has held relatively steady. Below is a chart documenting changes from 1986 to 2006.
Bay grasses have been demonstrated to be very sensitive to water quality and, as a result, are a good indicator of the health of estuaries like the Coastal and Chesapeake Bays. Excess nutrients and sediment act through a variety of mechanisms to prevent sufficient light from reaching the grass beds.
To date the Maryland Coastal Bays Program has only achieved 48 percent of its 2014 bay grass goal.
“Monitoring results remind us that more needs to be done to reduce nutrient and sediment inputs into Chincoteague Bay,” said Dave Blazer. “We are hopeful that implementation of nutrient reduction strategies will help reverse this recent declining trend and accelerate progress towards our restoration goals.”
Bay grass, or submerged aquatic vegetation (SAV), is a critical resource providing food and habitat for a wide range of species, including crabs, fish and waterfowl. SAV also protects shorelines from erosion, removes nutrients from the water, and traps sediments that cloud bay waters.
Sources of excess nutrients include atmospheric deposition, sewage treatment plants, septic systems, industries, automobiles, shoreline erosion, and runoff from agriculture and urban areas. Sources of excess sediments include improper agriculture techniques, impervious surfaces and erosion. The State of Maryland along with federal and local partners are working to reduce excess nutrient and sediment inputs by passing the Maryland Clean Car Act and strengthening regulatory requirements to enforce stronger stormwater management.
For more information, visit www.dnr.state.md.us/coastalbays/.
May 3, 2007The Maryland Department of Natural Resources (DNR) is the state agency responsible for providing natural and living resource-related services to citizens and visitors. DNR manages more than 446,000 acres of public lands and 18,000 miles of waterways, along with Maryland's forests, fisheries and wildlife for maximum environmental, economic and quality of life benefits. A national leader in land conservation, DNR-managed parks and natural, historic and cultural resources attract 11 million visitors annually. DNR is the lead agency in Maryland's effort to restore the Chesapeake Bay, the state's number one environmental priority. Learn more at www.dnr.maryland.gov
