Important Chesapeake Bay Grasses

Underwater Grasses in Chesapeake Bay & Mid-Atlantic Coastal Waters: Guide to Identifying Submerged Aquatic Vegetation
Join the hunt and learn the splender of Bay grasses
Bay Naturalist / By Kathy Reshetiloff - Bay Journal

Each year, the U.S. Fish & Wildlife Service coordinates the SAV Hunt, a citizen effort to locate Chesapeake Bay grass beds. These grasses, known as submerged aquatic vegetation or SAV, are an important indicator of water quality and provide habitat for wildlife.

Underwater grass beds are a critical habitat for many of the Chesapeake's aquatic life. Barnacles and scallop larvae attach to the leaves and stems of eelgrass in the salty waters of the lower Bay. Fish, including bluegill and largemouth bass, live in the freshwater grasses of the upper Bay. Minnows, small anadromous fish, such as juvenile striped bass, and blue crabs seek shelter as well as food in grass beds.

Grasses are an important source of food for the Bay's diverse waterfowl, fish, shellfish, and invertebrates. In the fall and winter, migrating waterfowl search the sediment for nutritious seeds, roots and tubers. Resident waterfowl may feed on different species of SAV year-round. Redhead grass and widgeon grass are favored foods of ducks of the same name, as well as many other waterfowl. Microscopic zooplankton feed on the decaying underwater plants and, in turn, are food for larger Bay organisms, such as fish and clams. Thus, SAV is a key contributor to the energy cycle in the Bay.

Bay grasses also provide other valuable functions to aquatic ecosystems like the Chesapeake. Bay grasses, like all green plants, produce oxygen, a precious and sometimes decreasing commodity in the Bay. The plants also filter and trap sediment, which can cloud the water and bury bottom-dwelling organisms like oysters. SAV also absorbs nutrients such as nitrogen and phosphorus, which in excess can spur harmful algae blooms.

Those who wish to join the SAV Hunt will need access to the water during the summer. Because most SAV grows in water 3 to 6 feet deep, it is recommended that volunteers wade in or use a shallow draft boat. Volunteers will be provided with instructions, field guides, data sheets and a map of the area they wish to survey. Each map shows the locations of SAV beds found in previous years by the same volunteer citizen effort and by aerial photography. Volunteers verify if these SAV beds are still present and record changes in size or species composition. They also look for and record any new SAV beds.
Information gathered by volunteers supplements the Baywide aerial survey, and often provides data on small, sometimes missed SAV beds.

Researchers also use the information to help target SAV protection and restoration, and local planning agencies use the data when considering projects that may affect aquatic resources.

Those interested in volunteering for the SAV Hunt should send their name, address and telephone number to U.S. Fish & Wildlife Service, 177 Admiral Cochrane Drive, Annapolis MD 21401, Attention: SAV Hunt.

Important Chesapeake Bay Grasses

Eelgrass (Zostera marina)
Description: Linear, ribbonlike leaves that occur along joints of the stem. Tips of leaves are rounded.
Distribution: High salinity areas of the lower Bay.
Importance: Good source of food for waterfowl, including black ducks, American widgeon, Canada geese and redhead ducks. Also a source of food for green sea turtles that occasionally enter the Bay. Important habitat for both juvenile and adult blue crabs.

Wild Celery (Vallisneria americana)
Description: Long, flattened, ribbonlike leaves arising from clusters at the base of the plant. Edges of leaves are slightly serrated with a rounded tip. Tiny white flowers.
Distribution: Freshwater areas of the northern portion of the Bay known as the Susquehanna Flats and in the upper freshwater reaches of many rivers.
Importance: Valuable food for canvasbacks, redhead ducks, mallards, lesser scaup, widgeon and swans. Habitat for fish and numerous aquatic invertebrates

Widgeon Grass (Ruppiamaritima)
Description: Linear, threadlike leaves arranged alternately on the stem. Immature flowers are enclosed in a sheath at base of the leaves. Mature flowers are raised close to the water's surface on a flower stalk. Fertilized flowers produce oval-shaped fruits, each on its own stalk.
Distribution: Mildly brackish water of upper and middle Bay to saltier waters of the lower Bay.
Importance: One of the best foods for waterfowl, it is eaten by many species of ducks, geese, swans, marsh birds and shorebirds. Also provides nursery and spawning areas for fish and aquatic invertebrates.

Redhead Grass
(Potamogeton perfoliatus)
Description: Oval leaves, the base of which clasps the plant stem. Clusters of tiny flowers extend above the surface of the water.
Distribution: Fresh to moderately brackish waters of the upper to middle
Importance: Valuable source of food for redhead ducks, canvasbacks, mallards, black ducks, Canada geese and tundra swans. Provides habitat formany aquatic organisms.

Kathryn Reshetiloff is with the U.S. Fish and Wildlife Service’s Chesapeake Bay Field Office in Annapolis.

Join the hunt and learn the splender of Bay grasses
Bay Journal
June 1998

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