Bay grasses, or submerged aquatic vegetation (SAV), are plants that grow underwater. They can be found in the shallow waters of the Chesapeake Bay and its tributaries, and are a critical part of the Bay ecosystem. They provide food and habitat for wildlife, and produce oxygen that underwater animals need to survive. Bay grasses also keep the water clear and healthy by absorbing nutrient pollution, trapping floating particles of sediment and reducing erosion.
Like plants on land, bay grasses use photosynthesis to turn sunlight into food. Sunlight, therefore, is the most important factor in determining bay grass survival. Water must be clear enough to allow sunlight to pass through and reach the grasses that grow on the bottom of rivers, streams and the Bay.
Bay grass growth can be hindered by pollutants that cloud the water. These pollutants include excess nutrients, which fuel the growth of dense algae blooms, and suspended particles of sand, silt and sediment. Healthy grass beds can trap and absorb some nutrient and sediment pollution, but too much pollution can block sunlight from reaching the plants.
Efforts are under way to slow the flow of nutrients and sediment into the Bay and its waterways. Upgrades to wastewater treatment plants and on-farm conservation practices, for example, are expected to improve water clarity.
While bay grasses are sensitive to pollution, they respond quickly to improvements in water quality. This means their abundance is a good indicator of restoration success.