​

Importance of SAV​

Submerged aquatic vegetation plays a crucial role in the health of the Chesapeake Bay ecosystem by providing a wide range of ecosystem services.

​

Benefits of SAV in Chesapeake Bay

​

Habitat for Aquatic Life SAV beds are essential fish habitat that provide food, shelter, breeding grounds, and nursery grounds to ecologically, recreationally, and commercially important fisheries throughout the Bay.

• From waterfowl to the tiniest microbes, countless Bay species benefit from nourishment provided by our underwater grasses. Seeds and tubers are particularly rich in nutritional value and are consumed by resident and migrating waterfowl alike. The leafy vegetation is grazed on by a number of invertebrates, particularly animals called detritivores that consume decaying plant matter once it has fallen to the Bay bottom. Because SAV is constantly growing new leaves and shedding old ones, our detritivores have plenty to eat!
• The leaves and stems of bay grasses also provide excellent habitat, refugia, and nursery sites for species such as killifish, minnows, and mummichogs. Small prey fish hide in SAV beds and larger fish use them as hunting grounds. Blue crabs are known to spend a great deal of time in SAV beds too; the habitat is especially important when they’re molting and highly vulnerable to predation. SAV beds increase biodiversity in the Bay by supporting a wide variety of aquatic life.

​

Oxygen Production During the process of photosynthesis, plants convert water and carbon dioxide (CO2) from the atmosphere into glucose and oxygen using sunlight. Oxygen is released as a by-product and enters the water column, providing liveable and breathable habitat for underwater organisms.

Carbon Sequestration SAV is considered a form of “Blue Carbon” because it grows in underwater environments and takes in carbon through the process of photosynthesis. The carbon is incorporated into their biomass, locking it in place as long as the plant is alive. When underwater grasses shed their leaves for the winter, like many land plants, the leaves settle to the Bay bottom where they break down and get incorporated into the sediment. In this way, SAV beds act as efficient and important carbon sinks that bind carbon in place for years to decades or longer.

pH Buffer Bay grasses help keep our waters healthy by buffering pH - the measure of how acidic or basic liquids are. As the grasses grow, they take in carbon dioxide from the water column for photosynthesis. Removing carbon dioxide from the water column helps reduce the production of carbonic acid and the release of hydrogen ions, which is what can make our Bay waters more acidic. Fewer hydrogen ions means less acidic water! Although pH fluctuates naturally from day to night (since plants can’t photosynthesize in the dark!), the presence of large, dense SAV beds in the Bay, like the Susquehanna Flats, helps stabilize conditions regardless. This is important because more acidic water makes it harder for shell-building animals like oysters and clams to grow and maintain their shells. By helping keep the water chemistry balanced, SAV beds create better living conditions for these species and support the overall health of the Bay.

Shoreline Protection from Erosion SAV beds help slow erosion and can help buffer coastlines from rising sea levels and storm impacts by dampening wave energy and holding bottom sediments in place.

In healthy SAV grass beds, the leaves and stems of the plants reduce water currents and wave energy by providing a physical structure in the water column that absorbs and dissipates that energy. The plants' root systems simultaneously work to hold bottom sediments in place. They are not indestructible though; big storms can damage SAV beds! If prop scars are present - areas where boat propellers have created troughs through grass beds by slicing into the sediments and severing the plants' root and rhizome system - strong wave energy can catch the edge of the scar and uproot the plants. To help our SAV beds maintain their resilience to environmental stressors, it’s important to avoid creating prop scars while boating!

Improved Water Clarity SAV’s ability to slow wave action also allows suspended sediment to settle out of the water column and onto the Bay bottom, where it gets further consolidated by the plants’ root and rhizome system. These sediments would otherwise scatter and block sunlight and reduce their ability to photosynthesize, and create inhospitable conditions for other Bay creatures. As above though, they’re not impervious to excessive sediment loading, particularly loads from big storms and precipitation events. If enough sediment is washed downstream, our SAV beds can get buried by sediment from the watershed. To help our SAV beds maintain their resilience to environmental stressors, it’s important to contain unconsolidated sediments on land!

Excess Nutrient Absorption SAV absorbs nutrients, such as nitrogen and phosphorus, from the sediments and water column. These nutrients can lead to unwanted algal blooms if present in excess. SAV’s ability to take up and incorporate nutrients into their biomass helps to maintain balanced ecosystems.

Economic & Recreational Benefits Healthy SAV beds support valuable commercial and recreational fisheries while also enhancing opportunities for boating, fishing, birdwatching, and eco-tourism. They contribute to both the local economy and our quality of life.

Educational and Cultural Value SAV offers hands-on learning opportunities through fieldwork and community science. SAV also holds cultural significance for many communities that depend on a healthy Bay for sustenance, heritage, and recreation.

​ ​