Could a Dusting of Dredge Help Marshes Survive?

Sep 20, 2018 | Healthy Habitats, North Carolina, North Carolina

Photo courtesy North Carolina Reserve

As sea levels rise, marshes have two ways to move if they are going to survive. They can keep up with rising water by accumulating enough sediment to raise the elevation of the marsh surface or by migrating inland to higher and drier land.

Our North Carolina Reserve is one of eight sites to test  a new technique to help marshes at risk keep pace with sea level rise—thin-layer sediment addition.The first-ever national marsh vulnerability assessment highlighted indicated marshes at the Reserve’s Masonboro Island Reserve are particularly vulnerable to sea-level rise.  The research team hopes that by adding a thin layer of sediment to the marsh surface it will be able keep up with sea-level rise.

“This project is moving us beyond the assessment phase to actively testing sediment addition as a strategy to reduce vulnerability of marshes to sea-level rise,” says Reserve Research Coordinator Dr. Brandon Puckett.

Researchers are testing two sediment thicknesses (7 and 14 centimeters) in the high and low marsh zones. After the sediment is added to the marsh surface, changes in elevation, vegetation, and soil properties will be tracked. The approach will be considered effective if it helps raise the marsh platform, while supporting a healthy marsh plant community.

Coastal managers have long needed a restoration strategy that helps marshes keep up with sea level rise.

“Reserve partners need better science and guidance for the use of sediment addition as a marsh restoration strategy,” says Puckett, “and Reserve staff are eager to test on-the-ground restoration to protect marshes from sea-level rise.”

Results from this project will not only be used by the Reserve, but also state and federal partners in North Carolina.

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