Creating Living Shorelines

They look like strange objects from another planet. But the dome-shaped structures that were placed in the muddy waters off the Stratford Point shoreline offer more than a surreal view. They are helping to dissipate the energy from tidal waves. This artificial reef is being tested to see if it help to prevent erosion along the shore and give newly planted salt marsh vegetation a chance to grow.

While made of concrete, these “reef balls” are unlike concrete barriers such as seawalls because they are placed further out from shore, spaced apart and have holes. They allow the tidewater to come in—enough to provide suitable habitat for the plants and animals who live in the intertidal zone.

The salt marsh restoration is part of a project to restore a 40-acre parcel of tidal marsh, coastal bluff, dune, and coastal grassland habitats that had been severely degraded in the 20th century because of its use as a gun club. The reef ball installation is also being used as a model to demonstrate  how “living shorelines projects” that provide erosion control, while restoring or enhancing natural shoreline habitats, can be used as an alternative to hard infrastructure projects in adapting to climate change.

The area where the salt marsh is being planted lost much of its sedimentation following a remediation project in 2001 to remove lead. Jennifer Mattei, a Sacred Heart University biologist and one of the managers of the Stratford Point project, said that her team tried the reef ball installation after earlier attempts to plant saltmarsh vegetation failed, and after Superstorm Sandy washed away a restored dune and 30,000 newly planted beach grass plants.

“Timing and the sequencing of habitat restoration is important for success,” said Mattei. “Having a reef in place first with the salt marsh behind it will dissipate wave energy and protect the dune. The reef will allow sediment to be deposited and build the shoreline.”

During storm events pressure sensors designed to measure wave energy were placed in front and behind the reef balls. The reef was found to have reduced wave energy by 30 percent, a significant help in not only preventing erosion, but in allowing for the accumulation of between one to six inches of sediment both behind and in front of the reef. For tidal areas, the ability to accumulate sedimentation is crucial in their ability to keep pace with sea level rise to prevent the salt marsh from becoming oversaturated and eroded.

If the restoration succeeds, the salt marsh will then not only provide critical wildlife habitat but will also play its role in reducing wave energy so that the project can move forward with dune and upper marsh restoration in areas that were damaged by Superstorm Sandy.

The Stratford Point site is owned by DuPont Corporation, which granted the Connecticut Department of Energy and Environmental Protection a conservation easement, which will prevent the site from ever being developed and to use the site for environmental education. Audubon Connecticut has been designated as the caretaker for the site, while Sacred Heart University has partnered with Audubon and DuPont to restore the area. Sacred Heart has received funding through the Long Island Sound Futures Fund for the salt marsh restoration project and in 2015 for upland coastal restoration including a two acre pollinator meadow and the installment of trees and shrubs important for migratory birds. SHU is helping to develop the overall management plan for the site with Audubon.

Watch a video of Sacred Heart University students planting salt marsh vegetation (Spartina alterniflora) at Stratford Point.

Jennifer Mattei, a professor of Ecology and Evolution at Sacred Heart University, is also founder of Project Limulus, a citizen science project that enlists volunteers to monitor for horsehoe crab populations in Long Island Sound.