Increase in bay grasses in 2001defying the odds

February 24, 2003

by Dr. Roman Jesien, science coordinator, Maryland Coastal Bays Program

Results from the 2001 seagrass data released last week indicate the bay grasses in Maryland's coastal bays increased 18 percent from 2000 to 2001 to approximately 11,438 acres.

The 2001 acreage represents the highest yet documented in the coastal bays, and a 245 percent increase since annual data collection began in 1986. Bay grass acreage in the coastal bays has exhibited a steady increase since annual monitoring began, and has declined only three times in the 16 year history of the survey, the most recent being in 2000.

While forage fish and water quality have shown declines in the northern bays over the past decade, the grasses seem to be defying all odds with their continued success. The growth of the essential crab, fish, and shellfish nurseries is a welcome sign to biologists. The grasses can also help offset nutrient inputs by helping to oxygenate the water and they protect shorelines from erosion by reducing wave energy.

Increases in bay grass coverage from 2000 were recorded in three of the four major coastal bays. Grasses in Chincoteague Bay increased 23 percent to 8,927 acres, Isle of Wight Bay increased 17 percent to 307 acres, and Assawoman Bay increased 7 percent to 550 acres. The largest increases in coverage and density were observed in the area of Tingles Island, South Point, and Mills Island in Chincoteague Bay, and near the eastern end of the Route 90 Bridge in Assawoman Bay.

Bay grass coverage in Sinepuxent Bay decreased approximately 2 percent from 2000 to a total of 1,654 acres. Decreases in bay grass coverage and density were observed in the Swan Point area of Assawoman Bay, and in several small pockets along the eastern portion of Sinepuxent and Chincoteague bays. Still, almost 85 percent of all bay grasses occur along the Assateague Island shoreline. Impacts from development and human activity have taken their toll on the northern bays.

Loss of natural shoreline that acts to filter out fine sediments and nutrients from paved surfaces and farm fields is the major threat to the health of the grasses. Microscopic algae, which guzzle nutrients faster than bay grasses, can block sufficient sunlight from reaching the grass. Bay grasses in the coastal bays have also been damaged by blooms of macroalgae and other harmful algal species and are sometimes destroyed by recreational and commercial boating activity.

The Coastal Bays Program is working with local, state, and federal partners to implement the Maryland Coastal Bays Comprehensive Conservation Management Plan, which identifies a variety of actions designed to restore and protect the coastal bays, including bay grasses. The news is encouraging for those working to protect the grasses. With severe brown tide blooms and extended periods of turbidity in 2002, scientists fear the next set of results may show a net loss as in 2000.

Despite recent increases documented by the aerial survey, bay grass coverage is currently considerably less than in the early 1900s. Disease struck many bay grasses along the East Coast in the early 1930s and eliminated bay grasses from the coastal bays. The Coastal Bays Program and DNR are evaluating historic aerial photographs to determine the extent of bay grass coverage during the 1930s and 1960s.

Since 1986, the Virginia Institute of Marine Sciences, funded by the States of Maryland, Virginia, and the federal government, has been monitoring bay grasses annually through aerial surveys.

DNR, in partnership with the Assateague Island National Seashore and others, initiated an environmental monitoring program in 2001 which will allow identification of specific factors influencing bay grass coverage in different portions of the coastal bays and guide future restoration efforts.
To view the entire 2001 Bay Grass Survey Report and associated maps, you can visit the Virginia Institute of Marine Science website at
www.vims.edu/bio/sav/sav01/.

Part of the National Estuary Program, the Maryland Coastal Bays Program is a cooperative effort between Worcester County, Berlin, and Ocean City which have come together to produce the first ever management plan for their bays. Home    |    About Us    |    Contact Us    |    Site Directory Copyright 2003 - Maryland Coastal Bays Program Questions? Email: mcbp@mdcoastalbays.org