Submerged Aquatic Vegetation Monitoring

Column Paragraph
Underwater grasses, also known as submerged aquatic vegetation (SAV), are a critical nursery habitat for many aquatic creatures and help to improve water quality. These underwater meadows are one of North Carolina's most valuable, and fragile, aquatic resources. Submerged aquatic vegetation plays a crucial role within our coastal ecosystems, with a single acre of grasses supporting as many as 40,000 fish and 50 million small invertebrates. In addition to providing habitat for creatures such as blue crabs, scallops, shrimp, and juvenile fish, underwater meadows improve water quality by absorbing excess nutrients and generating oxygen. Grasses decrease wave energy, helping to protect shorelines from erosion, while their roots increase water clarity by holding sediment in place. All these ecosystem services provided by seagrasses make them one of the most valuable habitats on the planet.

Because of how North Carolina’s barrier islands shelter our sounds from wind and waves, the Albemarle-Pamlico region has more than 136,000 acres of submerged aquatic vegetation – putting it in the top three states in the country for SAV abundance. This estuarine system also contains half of the juvenile fish habitat from Maine to Florida, making the state of its SAV an issue of regional importance. It’s this unique resource that scientists and managers, including those who are part of the Albemarle-Pamlico National Estuary Partnership’s (APNEP’s) multiagency Submerged Aquatic Vegetation Team, are working together to protect from water quality issues that threaten this habitat.

Partnerships to Protect SAV

Since 2001, an Albemarle-Pamlico SAV partnership has collaborated with the long-term goal of determining where the region’s underwater grasses are located and if their overall extent and density is changing over time. Monitoring SAV is important because it serves as an indicator of overall water quality - if SAV is flourishing, it means that the environment is as well. The partnership has already taken its first steps towards assessing the extent of underwater grasses in the region. In 2011, the SAV Team published a baseline map of submerged aquatic vegetation using data from aerial flights from 2006 through 2008, and in 2019 published a follow-up map based on data from 2012 through 2014. 

The monitoring of SAV by APNEP and our partners has resulted in the publication of two maps of SAV in the high-salinity portions of our estuary. Check out the map below to see the 2012-2014 and 2006-2008 SAV maps. The data and metadata for these maps are also available on the NC Department of Environmental Quality's ArcGIS Online portal.

Access the map data

These two maps, used together, will help the group to analyze how the extent and density of underwater grasses has changed over the past half-decade as well as determine if there are any areas where SAV is disappearing. APNEP and its partners will use this information to develop protection and restoration strategies for SAV and fish species in the region.

The aerial surveys that were used to produce these maps are an efficient means to monitor changes in SAV extent over large areas, but in some areas visibility is diminished by relatively turbid waters. Furthermore, aerial surveys can only be conducted relatively infrequently due to funding constraints.

To address challenges in tracking "hidden" SAV in turbid water, and to detect significant trends more quickly (including changes in species composition), APNEP began coordinating a SAV Sentinel Network in 2014. The sentinel network combines boat-based sonar and video technology with in-water observations to track SAV at stations dispersed throughout the sounds. The boat-based protocols were tested on Albemarle Sound in 2014 and the first installment of sentinel stations occurred there in 2015.

APNEP Comprehensive Conservation and Management Plan (CCMP) actions addressed:

  • A1.1: Facilitate the mapping of significant ecological, bathymetric, geologic, demographic, and cultural features.
  • B2.2: Develop and implement a submerged aquatic vegetation (SAV) protection strategy
  • C3.3: Develop and implement a submerged aquatic vegetation (SAV) restoration strategy
  • E1.1: Facilitate the development and implementation of an integrated monitoring network through the guidance of regional monitoring and assessment teams.