Submerged aquatic vegetation (SAV), also known as seagrass, bay grass or underwater grasses, is critical to the health of aquatic ecosystems. It provides habitat, food and nursery grounds for commercially and recreationally important fish and shellfish and helps improve water quality by trapping sediments, absorbing excess nutrients and mitigating shoreline erosion.

The Watershed Assessment and Management Section, in the DNREC Division of Watershed Stewardship, leads efforts in monitoring, restoring and educating the public about submerged aquatic vegetation. The Submerged Aquatic Vegetation Program plays a vital role in restoring and monitoring SAV across Delaware’s marine and freshwater systems.

DNREC is part of the Delaware Statewide Submerged Aquatic Vegetation Workgroup, which brings together partners in state and federal government agencies, academia and environmental organizations to work on issues related to submerged aquatic vegetation.

What is Submerged Aquatic Vegetation?

Submerged aquatic vegetation consists of rooted, vascular, flowering plants that grow underwater in freshwater, estuarine or marine habitats.

Like terrestrial plants, SAV relies on sunlight for photosynthesis, reproduces through the pollination of flowers, produces seeds and uses a vascular system to transport nutrients between roots, leaves and sediment.

Despite similarities to land plants, SAV is often mistaken for seaweed or macroalgae.

Submerged Aquatic Vegetation in Delaware

One of the most iconic SAV species that historically was found in Delaware is eelgrass (Zostera marina), the only fully marine species that thrives in high-salinity environments in our region. While recent monitoring efforts have not found eelgrass in Delaware waters, other SAV species are thriving.

SAV grows in areas where the conditions are just right.

One key factor is sunlight. These plants need light to make food, so they grow in shallow, clear water where sunlight can reach the bottom. 

Salinity, or how salty the water is, also matters. Some plants prefer fresh water, while others thrive in salty or brackish water. 

Water movement is important too. While some plants can handle strong currents, others need calm waters to stay rooted. 

The bottom surface, or substrate, is another factor. These plants need soft sand, mud or other stable materials to anchor their roots. 

Finally, temperature plays a role. Each plant has a range of temperatures in which it grows best.

All these factors combine to determine where SAV can live and grow.

Related Topics:  assessment, habitat, monitoring, sav, seagrass, Submerged Aquatic Vegetation, water quality, watershed stewardship