This map shows locations of eelgrass beds in coastal waters from eastern Long Island Sound to Maine.

Data Considerations

Beds of eelgrass (Zostera marina) are critical components of shallow coastal ecosystems throughout the region. Eelgrass beds provide food and cover for a great variety of commercially and recreationally important fauna and their prey. Eelgrass and other seagrasses are often called submerged aquatic vegetation (SAV). This distinguishes them from seaweeds and other marine algae, which are not classified as plants by biologists (rather they are usually classified as protists). It also distinguishes them from non-submerged (or “emergent”) saltwater plants such as grasses found in salt marshes. In addition to the term SAV, some coastal managers use the term SRV, or submersed rooted vascular plants.

Northeast Ocean Data’s eelgrass dataset was created from five separate datasets for the states of Connecticut, Rhode Island, Massachusetts, New Hampshire, and Maine. Where possible, we used polygon datasets depicting the most recent eelgrass surveys. Attributes with common themes for each dataset were integrated in order to better represent eelgrass density and year sampled. Users are encouraged to read the metadata for each individual state’s data carefully, as geometry, attribute details, and timeliness are not necessarily consistent among datasets used to develop this layer. Details of each state’s data source are described in the data processing section of the metadata.

The absence of eelgrass in a particular place on the map does not necessarily mean that eelgrass does not live at that location, as the surveys of eelgrass did not encompass the entire coastline.


Regional eelgrass data are updated yearly. The next update is planned for summer 2015.