The Chesapeake Bay's underwater grasses decreased by 5,740 acres, or 8%, Baywide in 1998, according to information released by the Chesapeake Bay Program. This decrease interrupts the improving trend observed between 1995 and 1997.

Experts are examining several factors, including high freshwater flow during the first half of last year and poor water clarity conditions in the mid- and lower Bay, as they try to determine the reason for the decrease in overall acreage in 1998. Experts point out that the Bay received higher-than-average freshwater flow during four of the last six years, including 1993, 1994, 1996 and 1998.

"The cumulative effect of several recent high flow years is considered a likely factor in slowing overall Bay grass recovery since the early 1990's," said Robert Magnien, the Maryland Department of Natural Resources' Director of Tidewater Assessment.

High flows affect water clarity by increasing runoff from the land which adds higher levels of nutrients and sediment to the water. Higher levels of nutrients fuel the algal blooms which reduce water clarity and block the sunlight underwater grasses need in order to grow. According to the U.S. Geological Survey, a Bay Program partner, the freshwater flow to the Bay averaged 63.1 billion gallons per day in 1998, making it a higher-than-average year for flow. Flow during the first six months of 1998 was the highest for any continuous six-month period since 1951. In July, flow was about average; however, from August through December, drought conditions prevailed across the watershed which lead to below average flow for the second half of 1998.

"The Chesapeake Bay is a very complex system. It's driven by weather and river flow interacting with human impacts," said Carlton Haywood, chairman of the Chesapeake Bay Program's Monitoring Subcommittee. "That's why it's important for us to track river flow, sediment levels and algal blooms during the year, especially during the critical growing period for the grasses."

Restoring underwater grasses is one of the top priorities of the Bay Program. In 1993, the Bay Program partners -- Maryland, Virginia, Pennsylvania, the District of Columbia, the Chesapeake Bay Commission and the U.S. Environmental Protection Agency -- agreed to restore grasses to 114,000 acres by the year 2005. The current total of 63,495 acres represents 56% of that goal.

The decrease in underwater grasses was not uniform for all areas of the Bay. In the three largest geographical zones the survey showed:

• Acreage in the upper Bay increased 3% to 11,260 acres
• Acreage in the mid-Bay area decreased 14% to 30,225 acres
• Acreage in the lower Bay decreased by 5% to 22,010.

"The new Bay grass numbers provide some mixed messages about how well the Bay restoration is proceeding -- we have good news and bad news. The good news is that the upper Bay and some lower Bay tributaries fared well last year. However, the bad news from Tangier Sound sends a very clear message that we must redouble our efforts to reduce pollution from agriculture and other sources on the Delmarva Penninsula," said W. Michael McCabe, Region III Administrator for the U.S. Environmental Protection Agency.

According to experts, 1998 marked the sixth straight year of decreases in the Tangier Sound area. The latest decrease marks a 30% decline in grasses in Tangier Sound since 1997 and a 63% decline since 1992. The continued decline in grasses there is an ongoing concern to the Bay Program because it is an important nursery for young blue crabs and many species of fish.

There also were a number of positive findings in the 1998 survey, including 20% or greater increases in grass acreage in the Magothy, Severn, South, Northeast, Elk and Bohemia rivers and in the upper and middle Potomac and in Mattawoman Creek in Maryland. In Virginia, 20% or greater increases were recorded in the parts of the Mattaponi, Pamunkey and Chickahominy rivers.

Underwater grasses are important to the Bay because they produce oxygen; provide a nursery, food and protection from predators for a variety of creatures, including crabs and fish; reduce wave action; reduce erosion; absorb the nutrient pollutants phosphorus and nitrogen; and trap sediments. In order for grasses to grow, sunlight must be able to penetrate the water to the bottom. Grasses increase in response to water quality improvements that occur when levels of sediments and nutrient pollution are reduced. Grasses also are a good measure of the Bay's health and water quality since they are not under harvest pressure like most of the Bay's other living resources, including fish and crabs. In 1998, grasses covered about 63,495 acres of Bay bottom. That acreage is about one-tenth of the nearly 600,000 acres that once were thought to have covered the Bay floor.

Fact Sheet

The all-important nursery grounds for the Chesapeake Bay's fish and crabs -- its beds of underwater Bay grasses -- declined in 1998 by 8% from 1997 levels. That 5,740-acre decrease brings the Baywide total to 63,495 acres, according to the latest Chesapeake Bay Program information. This decline interrupts an overall improving trend observed between 1995 and 1997.

Underwater grasses are important to the Bay because they produce oxygen; provide a nursery, food and protection from predators for a variety of creatures, including crabs and fish; reduce wave action; reduce erosion; absorb the nutrient pollutants phosphorus and nitrogen; and trap sediments. In order for grasses to grow, sunlight must be able to penetrate the water to near the bottom. Grasses respond to water quality improvements that occur when levels of sediments and nutrient pollution are reduced. Grasses also are a good measure of the Bay's health and water quality since they are not under harvest pressure like most of the Bay's other living resources, including fish, crabs and other critters.

Restoring the Bay's grasses is one of the top priorities of the Bay Program. In 1993, the Bay Program partners agreed to restore grasses to 114,000 acres by the year 2005. The current total of 63,495 acres represents 56% of that goal.

The 1998 Bay grass survey found mixed results in the three major geographic areas of the Bay -- upper, middle and lower:

• In the upper Bay, stretching from the Chester and Magothy rivers north, Bay grasses increased to 11,260 acres which was 3% more than in 1997.
• In the mid-Bay area, stretching from the upper Bay south to the Pocomoke and Rappahannock rivers, acreage was down to 30,225 acres which was 14% less than in 1997. This area includes the Potomac River.
• In the lower Bay, stretching from the Pocomoke-Rappahannock area south to the mouth of the Bay at Hampton Roads, Virginia, acreage decreased to 22,010 acres which was 5% less than in 1997.

Increases

Bay grasses increased in 27 of the 78 segments of the Bay and its tidal tributaries monitored in the aerial survey, with new grass beds being reported in the six segments that were surveyed for the first time in 1998. Sixteen of the segments increased by 20% and 10 acres or greater in 1998.

In the upper Bay, these areas included:

• The Northeast River
• The Elk River
• The Bohemia River
• The Gunpowder River
• The Magothy River

In the middle Bay, these areas included:

• The Severn River
• The South River
• The middle Potomac River
• The upper Potomac River
• Mattawoman Creek (a tributary to the Potomac)

In the lower Bay, these areas included six areas surveyed for the first time in 1998:

• The upper Rappahannock River
• The upper Mattaponi River
• The upper Pamunkey River
• The middle James River
• The Chickahominy River
• The upper James River

Decreases

Bay grasses decreased in 25 of the 78 segments -- twice as many as in 1997. Twelve of the segments decreased by 20% and 10 acres or greater in 1998.

In the upper Bay, these areas included:

• The Sassafrass River
• The Bush River
• The Middle River

In the middle Bay, these areas included:

• Middle-Central Chesapeake Bay
• Eastern Bay
• The Honga River
• Tangier Sound
• The Manokin River
• The Big Annemessex River

In the lower Bay, these areas included:

• The lower Rappahannock River
• The Piankatank River
• The mouth of the James River

In addition, the acres of Bay grasses in Tangier Sound and around nearby islands declined for the sixth year in a row. The declines in Tangier Sound are a cause for concern because they have continued for so long and because so many acres are involved. This area is also one of the most productive areas for blue crabs in the Bay. In 1992, Tangier Sound had 18,106 acres grass. By 1998, that dropped to 6,609 acres -- a loss of 11,497 acres or 63% of the 1992 area. Causes for this decline are unclear, although water quality trends show that the conditions in that area are worse than they have been in the past.

The annual survey of grass beds is funded by the Chesapeake Bay Program, Maryland's Department of Natural Resources, NOAA's Coastal Zone Management Program, the U.S. Fish & Wildlife Service, and the Virginia Institute of Marine Science. The annual Bay grass survey is coordinated by the Virginia Institute of Marine Science. The survey is based on more than 1,800 aerial photographs of shallow water areas of the Bay. The results of the aerial survey are photo-interpreted for the presence of Bay grasses. Then, the data is digitized and stored in a geographical information system.

The Chesapeake Bay Program is the partnership among Maryland, Virginia, Pennsylvania, the District of Columbia, the Chesapeake Bay Commission and the U.S. Environmental Protection Agency. It was established in 1983 under the historic Chesapeake Bay Agreement.

For more specific information on Bay grasses, contact: Kate Naughten, Chesapeake Bay Program - (410)267-5758