Underwater Grasses

Underwater grasses, called “submerged aquatic vegetation” or SAV, usually grow entirely underwater and rely on buoyancy to support their stems and leaves. Because SAV requires light for photosynthesis, it thrives in shallow areas where sufficient sunlight can penetrate.

SAV enriches the shallow aquatic environment of the Chesapeake in several ways. Mazes of underwater grass beds provide shelter to spawning fish, shellfish, and their offspring, such as juvenile crabs. Resident waterfowl feed on all parts of the grasses throughout the year, while SAV seeds and tubers provide the primary food source for many migrating waterfowl that over-winter on the Chesapeake.

Underwater grasses also help to maintain water quality by trapping sediment and absorbing nutrients that can lead to algae overgrowth and low dissolved oxygen in the water. Additionally, beds of SAV slow water currents and reduce the force of waves, which protects against shoreline erosion.

The Chesapeake Bay has over a dozen native SAV species throughout its fresh, brackish, and saltwater areas, but these grasses have experienced serious declines since the 1960s.

Learn more about the loss of underwater grasses in the Bay and efforts to restore them.