Following fish through a restored Poplar Island 

This Poplar Island marsh cell features a sunken barge. Credit: Chesapeake Bay Program.

An ongoing restoration project is bringing back a Chesapeake Bay island that provides important habitat for a variety of species both on land and in the water. ACT Network collaborators with the National Oceanic and Atmospheric Administration’s (NOAA) National Centers for Coastal Ocean Science (NCCOS) are using acoustic telemetry to understand how aquatic species use restored marsh on Poplar and how the island is connected to the greater mid-Atlantic region.

Poplar Island lies about 12 miles west of the town of Easton. Once home to a small community, Poplar’s human inhabitants abandoned it in the 1920s as it began to disappear. Thirty years ago, it was almost gone: the island had shrunk from approximately 1,100 acres when surveyed in 1847 to a mere four.

The reasons? Land around the bay once pushed upward due to the massive weight of inland ice sheets during the last glaciation is now subsiding. Sea level is rising due to thermal expansion and glacial melt. Natural erosion from wave action has worsened at Poplar since the island’s trees were cleared for local sawmills in the early 20th century. Despite these changes, Poplar remains important habitat for avian, terrestrial, and aquatic species.

The goal of the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island is to reverse some of that loss through the beneficial use of dredged material from nearby shipping channels, which must be removed regularly to ensure that the channels do not fill with sand and mud. Dredged material is sculpted into restored marsh habitat, which is divided into containment cells, each with a unique arrangement of landscape features, such as creeks and ponds.

Repurposing dredged material is nothing new. However, what makes restoration projects like the one on Poplar Island innovative is how engineers mimic naturally occurring features.

“This is a total paradigm shift. By managing the sediment in these ways, not only can the shipping channel be maintained, but something really beneficial can be done for the ecosystem of Chesapeake Bay,” says Dr. Matt Kendall, marine biologist with NOAA NCCOS. “The key question is, do the fish buy it?”

Working alongside Jessica Hill, quantitative ecologist under contract to NOAA NCCOS, Kendall is using acoustic telemetry to track aquatic animals in newly restored marshes and follow their movements from Poplar Island to other parts of the Chesapeake and Northwest Atlantic.

The team implanted acoustic tags in individuals from ecologically and economically important species, including white perch, gizzard shad, striped bass, red drum, spot croaker, American eel, channel catfish, and cownose ray.

They also deployed an array of acoustic receivers around Poplar Island, with stations at the entrance and interior channels of constructed marsh cells. The goal of the work is twofold: the scientists want to know if fish tagged at Poplar are returning to the restored habitat, and whether fish tagged elsewhere are visiting Poplar.

Based on preliminary analysis of tag detections at Poplar and other sites maintained by ACT Network researchers, Hill says that the answer to both questions is a resounding yes.

“Poplar is connected, not just to the Chesapeake Bay, but to the greater mid-Atlantic region,” says Hill.

The bottom line – Poplar is popular.

“Fish live there. They grow up. They reach maturity. They leave, they go spawn somewhere else. And then they come back to Poplar, to the same containment cell and marsh culvert where they lived before,” says Kendall. “The white perch is a perfect example of a species that leaves to spawn but ultimately returns to Poplar — this place is contributing to the population of a really popular sport fish.”

Both Hill and Kendall emphasize that this type of analysis is only possible with collaborative networks like the ACT Network.

“This type of work – examining what would be an isolated island and understanding how it connects to the greater ecosystem – wouldn’t be possible without collaboration,” says Hill.

In the next phase, the NOAA NCCOS team will analyze detections from receivers inside the restored marsh cells to understand which cells and landscape features the fish prefer. These data will help managers select landscape features to maximize habitat for certain species in future restoration projects.

This project comes out of a collaboration between NOAA’s NCCOS, the Army Corps of Engineers, Maryland Environmental Service, and Maryland Port Administration. The project leads acknowledge the following ACT Network collaborators who have agreed to share data: Kim Richie, Matthew Balazik, Wilmelie Cruz-Marrero, Keith Dunton, Sheila Eyler, Michael Frisk, Evan Kostelecky, Henry Legett, Benjamin Marsaly, Reid Nelson, Matthew Ogburn, Ian Park, Eric Reyier, Brendan Runde, Jennifer Wyffels.