Tag Archives: salt marsh

Saving the Salt Marsh with Mussels?

Along the southern shore of the Merrimack River near Joppa Flats Education Center, over a mile stretch of salt marsh is struggling. While it’s uncertain exactly why this salt marsh is degrading, excessive nutrients from the Merrimack River and upstream wastewater treatment plants might be to blame.

The salt marsh behind Joppa Flats

When salt marsh cordgrass, Spartina alterniflora, is overloaded with nutrients, it develops more above-ground biomass and less below-ground biomass, leaving it unstable. Top-heavy and poorly rooted cordgrass can slump over when hit by waves, leading to bank collapse and erosion. This, combined with sea-level rise and increased storm activity, could speed up degradation and eventually lead to total habitat loss.

Protecting salt marshes in this area is vital as they absorb wave energy and reduce storm surges. This stretch of salt marsh is also a valuable habitat that houses more than 220 species of birds, including six rare species and three species with state wildlife action plans (SWAP).

Restoring with Ribbed Mussels

Ribbed Mussels

The ribbed mussel, Geukensia demissa, is the East Coast’s most common salt marsh bivalve and has been used in restoration projects for its ability to filter water, remove phytoplankton, transform nitrogen, and stabilize sediments with its byssal threads. However, surveys have not found any ribbed mussels in the salt marshes on the southern shore of the Merrimack River estuary. This might be from a lack of suitable substrate, poor water quality conditions, or ice scouring.

In October 2022, Mass Audubon relocated mussels from a nearby marsh to the salt marsh at Joppa Flats Education Center on the southern shore of the Merrimack River to test the feasibility of ribbed mussel restoration. Mussel survival and water quality will be monitored through the winter and spring of 2023. If they survive, Mass Audubon will start testing possible materials to grow mussels on and assess different ways to introduce them into the Merrimack River Estuary salt marsh.

Mass Audubon has received funding from the Palmer Foundation to collect data to evaluate the marsh and support the design of a salt marsh restoration approach. Results from the ongoing pilot study and future mussel experiments will be incorporated into the salt marsh restoration design process.

Moving the Action Agenda Forward

We are committed to fostering resilient landscapes across Massachusetts, as outlined in our Action Agenda. Learn more about how we are doing this on the coast via our Coastal Resilience Program and how you can support this important work.

Climate Action through Salt Marsh Restoration

 DNRT’s and Mass Audubon’s TerraCorps members, staff, and volunteers hard at work.

When we look to nature, we can find many ways to adapt to and mitigate climate change. Restoring nature so it can perform these services is, in part, how Mass Audubon acts on climate. Wetland restoration work being done on the South Coast is a prime example.  

On February 15, Dartmouth Natural Resources Trust (DNRT) and Mass Audubon’s TerraCorps members, staff, and volunteers spent the day achieving this goal by removing invasive plant species on DNRT’s Ocean View Farm Reserve (neighboring Mass Audubon’s Allens Pond Wildlife Sanctuary). This effort is under the recently awarded Southeast New England Program (SNEP) Watershed Grant. SNEP Watershed Grants are funded by the U.S. Environmental Protection Agency (EPA) through a collaboration with Restore America’s Estuaries (RAE). 

The Big Deal about Invasive Species 

Invasive species are known for their ability to easily spread past their native habitats — either by accident, opportunity, or purposeful introduction — and establish themselves into new habitats. Upon their arrival, these species tend to out-compete native flora or fauna for resources. This can cascade into a variety of consequences such as already vulnerable wildlife losing critical food sources or homes. 

Why Wetlands? 

Wetlands are our first line of defense when it comes to withstanding climate impacts like flooding, which we are now seeing more of due to sea level rise and an increase in the frequency of extreme weather events. Not to mention, healthy wetlands (like a salt marsh) store more carbon per unit area than some of Massachusetts’ forests, helping us mitigate climate change at the same time. 

But wetlands also need to be able to adapt to climate change’s impacts. As tides creep further up our shores, flood and salt intolerant wildlife move upland as a response. An abundance of invasive species inhibits how well native plants (and their accompanying animals) can migrate landward. 

Staff and Volunteers at Work 

Following COVID-19 public health guidelines and armed with loppers, handsaws, and chainsaws, staff and volunteers worked together to remove invasive species such as Autumn Olive, Multiflora Rose, and Bush Honeysuckle.   

The invasive brush must be cut from the ground to enhance Ocean View Farm Reserve’s ability to act as a wetland buffer, or an area with plants that helps protect the wetland and all its climate services. Volunteers stacked the cut brush on tarps and pulled the brush over 100 yards to a suitable area for disposal.   

The job doesn’t end with invasive species removal, however. Staff and volunteers then began planting native grasses and flowers that are both salt and flood tolerant. As sea levels rise, these actions will help facilitate wildlife and habitat movement landward as a response.  

The Bigger Picture 

The work is tedious and grueling, and relies on the dedication of staff and volunteers to restoring nature and protecting our world from climate change. Invasive species removal is just one component of the grant, which funds a variety of other science and restoration activities at Mass Audubon Great Neck and Allens Pond Wildlife Sanctuaries.

All these initiatives are designed to better understand how sea level rise impacts our coastal wetlands, how to protect these habitats from climate change (and therefore the wildlife and human communities surrounding them), and how to model broader climate resilience efforts in the region. 

Thank you to our partners DNRT and TerraCorps for their collaboration on this project, Home Depot for donating tarps for our staff and volunteers to use during removals, and all the Mass Audubon and DNRT volunteers who lent their time and efforts to the project.