Chesapeake Bay National Estuarine Research Reserve

Monitoring Underwater Grasses (Submerged Aquatic Vegetation–SAV)

​​Hydrilla bed at Otter Point Creek. Photo credit: P. Delgado

Sampling SAV using the oyster tong technique. Photo credit: P. DelgadoCBNERR-MD is monitoring underwater grasses (SAV) as part of an overall effort to learn more about the plants and animals living in the Reserve. SAV are rooted aquatic plants that provide food and a home for many animals including fish, crabs, snails, ducks, and geese. SAV also make the water clearer and cleaner by trapping and absorbing pollutants, such as sediments and excess nutrients.

SAV is currently being sampled at two of the CBNERR-MD components: Jug Bay, with six sites located within the Patuxent River; and Otter Point Creek, with five sites located within the Bush River. This effort started in 2007 and follows a modified oyster tong sampling technique, which is a suitable method for sampling large areas when diving techniques are not practical. The characteristic shallow areas and the constant turbid conditions within the Patuxent and Bush Rivers make the sampling of SAV by diving especially difficult. In addition to sampling SAV, water quality parameters (dissolved oxygen, temperature, conductivity, conductance, salinity, secchi depth) and total depth are also recorded. Sampling occurs three times a year during the growing season: June, August, and October.

The main objectives of this project are to:Sorting SAV species.  Photo credit: P. Delgado

  1. Better understand the impacts of human and natural stressors in SAV communities (i.e., development, water quality, invasive species, and climate changes).
  2. Promote the use of long-term monitoring data to manage and protect CBNERR-MD SAV communities.
  3. Promote the use of long-term monitoring data for education and stewardship purposes.

Previous surveys have shown a dominance of Hydrilla (an invasive species) in both of the CBNERR-MD components. However, other SAV species have also been recorded including: coontail, southern naiad, common waterweed or elodea, horned pondweed, wild celery, eurasian watermilfoil (non-native), and spiny naiad (non-native).

How to Get Involved:

If you are interested in helping with our SAV monitoring, please contact CBNERR-MD Research Assistant, Lindsay Carroll ( No experience is required. Sampling involves long hours on a boat, the use of modified oyster tongs, sorting of SAV species, the use of equipment to measure water quality parameters, and note-taking. In return, you would have the opportunity to enjoy the wonders of Jug Bay and Otter Point Creek.

Available Information:

Information collected includes: species presence, biomass (estimated through an indirect volume displaced technique), and water quality parameters. If you are interested in this data please contact Stewardship Coordinator, Chris Snow (


Sampling marsh vegetation at Jug Bay (Credit: L. Carroll)

Our Science

Explore and learn about the interesting research and long-term monitoring projects we are conducting at Otter Point Creek (Bush River), Jug Bay (Patuxent River), and Monie Bay (eastern shore). Our projects range from water quality monitoring to marsh plants to monitoring secretive marsh birds and fish.​​​​​


Links to Our Data

Our Data

We invite you to use our data to support research, modeling, management, and/or education goals. Our data could serve as baseline information to start a new research project, to look for interesting trends, to support modeling efforts, or to complement a project already in progress. We hope our data can help you to make a difference!