A recently published map gives scientists a better understanding of the density of submerged seagrass habitats along North Carolina's coast as well as a baseline for measuring changes in the ecosystem.
“We’re trying to figure out how this environment is doing in North Carolina,” said Bill Crowell, the director of the Albemarle Pamlico National Estuary Partnership (APNEP), a cooperative program hosted by the N.C. Department of Environmental Quality. “Seagrasses are an indicator species for us to tell us how the overall system is doing. If we have a lot of grass, we know that water quality is pretty good."
Submerged aquatic vegetation, or SAV, reduces shoreline erosion, improves water quality, and provides habitat for many fish and wildlife species, including spotted sea trout, red drum, blue crab and bay scallops. A single acre of seagrass can support more than 40,000 fish and 50 million small invertebrate species, according to the Smithsonian Institution.
The new map, which shows the location of seagrass beds along nearshore waters of the Outer Banks, Pamlico Sound, Albemarle Sound, and Bogue Sound, was compiled using aerial images and boat based surveys conducted from 2012 through 2014.
“A person goes through every single image and looks for what appears to be submerged aquatic vegetation, and they draw lines around the areas,” said Crowell. “That’s complimented with people going out in the field to make sure that what the person looking at the photograph is seeing really is seagrasses.”
Now that the updated map has been released, APNEP plans to compare the new data with images from 2006-2008 to determine how the density of submerged seagrass has changed.
“As our environment changes, we try to get an idea of what to expect, what it should be, and how the condition is. Looking at whether the seagrasses are growing or shrinking, the extent to which it’s increasing or decreasing is really important,” said Crowell.
The growing season for SAV is late spring to early fall. A number of other factors, including water clarity, cloud cover, and wind limit how often aerial surveys can take place. This summer, APNEP completed aerial photos and boat-based surveys to gather data for a third map. Additional flights and boat surveys are planned for spring 2020.
Funding for the project was provided to APNEP by the U.S. Environmental Protection Agency. The N.C. Division of Marine Fisheries, the National Oceanic and Atmospheric Administration Beaufort Laboratory, and numerous volunteers provided field and technical support for the project.