What Is SAV, and What Does It Do?
How Is the SAV in the Bay Doing?
How Is NOAA’s Chesapeake Bay Office Helping to Restore SAV?
How Can I Protect and Restore SAV?
Monitoring the Progress of SAV Recovery
Further Reading
Links to Regional Partners' Web Sites
Information on SAV in Other Places

Underwater grasses, or submerged aquatic vegetation (SAV), are plants that grow underwater in shallow areas of the Chesapeake Bay and its tributaries. Air-filled sacks called “aerenchyma” provide these plants with the buoyancy and support necessary for life in the water. Although they are vascular plants, their leaves and cuticles lack the waxy coating found on most land plants allowing them to exchange gases and nutrients with the surrounding water. About 20 different species of SAV live in and around the Bay.

SAV helps improve water clarity by absorbing nutrients, settling sediment suspended in the water, and stabilizing the bottom. It also absorbs some of the wave energy that can cause shoreline erosion.

Perhaps one of the most important services that SAV provides is habitat for Bay wildlife. SAV beds provide forage for waterfowl, and protection from predators for juvenile blue crabs and finfish species including menhaden, herring, shad, spot, croaker, weakfish, red drum, striped bass, and white perch. One study conducted by researchers at VIMS found that juvenile blue crabs were 30 times more abundant in SAV beds in Tangier Sound than they were in adjacent unvegetated areas.

The blue crab uses SAV for refuge from predation and as a place in which to feed on small forage fish and detritus. SAV is especially critical as a refuge for the blue crab to hide in during molts, when it sheds its old shell and begins to form a new one.

Because SAV responds directly to local water-quality conditions such as sediment and nutrients, its presence, abundance, and diversity are important indicators of the health of the Chesapeake Bay. Many of the nearshore areas of the Bay contain excess nutrients and sediment–mostly from fertilizer from agricultural operations and home use, outflow from sewage treatment facilities, and direct land runoff from impervious surfaces such as roads, parking lots and buildings.

Too much sediment can block the light needed by SAV to survive. Nutrients (principally nitrogen and phosphorus) are necessary for plants to survive and grow, but can stimulate excess algae production when present in high concentrations. An overabundance of algae in the water column can block light from reaching the submerged plants.

Estimates of historic SAV distribution in the Bay range from 400,000 to 600,000 acres. By 1978, the first year of "modern" Bay-wide surveys, SAV coverage in the Bay had dropped precipitously to only 41,000 acres—only 10% or less of estimated historic levels. SAV abundance and distribution have increased in most years since the mid-1980s, and are currently at almost half of the Bay-wide restoration goal of 185,000 acres set in 2003.

The Chesapeake Bay Program has adopted a goal to restore SAV in the Chesapeake Bay and its tidal tributaries to 185,000 acres by 2010. Achieving this goal depends on improving water quality to allow SAV to grow in more areas, protecting existing SAV, and restoring SAV to where it grew before. NOAA is working with the Chesapeake Bay Program and its other partners to achieve this goal through:

• Improving water quality by reducing the amount of nutrients and suspended sediments entering the Bay and its rivers.
• Protecting SAV through regulations that protect shallow water habitats during dredging and other activities.
• Restoring SAV by planting native species around the Chesapeake Bay.

NOAA’s Chesapeake Bay Office also awards grants to support SAV restoration. These funds have supported large-scale plantings of eelgrass in the Piankatank and Patuxent Rivers, developed better methods for collecting and planting seeds, set up facilities to increase seed availability, and initiated site assessments for additional planting projects. The NOAA Chesapeake Bay Office also provides technical assistance and support to nonprofit community environmental groups and other NOAA programs working on SAV restoration.

• Volunteer to plant SAV .
• Help with SAV surveys. Volunteers can confirm the presence of SAV, identify the species if possible, and locate beds of SAV too small to be seen from the air. Instructions are available, or contact NCBO staff for more information. The Chesapeake Bay Foundation has online SAV identification guides. Information about how to order a printed SAV field guide (published in 2006) is available from Maryland Sea Grant
• Avoid disturbing SAV beds when boating. Propellers and impellers may tear rooted vegetation out of bottom sediments.
• Always use pump-out stations to dispose of boat waste.
• Avoid vegetated shallows when planning dredging or pier construction.
• Use your car and other gasoline engines less. Their exhaust contains nitrous oxides that pollute Chesapeake Bay, and the pavement that cars need increases harmful runoff.
• Put less fertilizer and weed killer on your lawn, and apply them less often. Fall fertilizing is better for your lawn and less harmful to SAV than spring fertilizing.
• Practice Bayscaping , using native plants in your yard that require less maintenance and are better suited to native wildlife.
• Reduce shoreline erosion by planting emergent vegetation (beach grass), and using other "soft" stabilization methods whenever possible.

SAV beds in the Chesapeake Bay are mapped and measured annually by the Virginia Institute of Marine Science (VIMS) using aerial photography. The reports are available on the VIMS web site . SAV surveys are used to track the recovery of SAV in Chesapeake Bay, guide protection and restoration efforts, and identify SAV beds that need protection where dredging, pier construction, or other potentially damaging activities are planned.

Restoration of aquatic grass communities of Chesapeake Bay: How should we proceed?
Interactions among dark false mussels, water clarity, and Submerged Aquatic Vegetation(SAV) abundance in mesohaline regions of Chesapeake Bay in 2004-2005

Alliance for Chesapeake Bay
Chesapeake Bay Foundation
Chesapeake Bay Program
Maryland Department of Natural Resources
Virginia Institute of Marine Science

Florida Keys
NOAA Coastal Services Center
Long Island eelgrass restoration