Restoring the “Natural Mosaic” of the Thompsons Beach Salt Marsh

by Lindsay McNamara, Communications Manager, Conserve Wildlife Foundation of New Jersey

To restore Thompsons Beach, along New Jersey's Delaware Bayshore, our team removed debris from the beach, removed rubble from the road leading to the beach, and placed over 40,000 cubic yards of sand (weighing over 9 million pounds) onto the beach. We were filled with pride when we saw sanderlings and ruddy turnstones feeding this August on horseshoe crab larvae on our newly restored beach. We were delighted to learn that this spring, Thompsons Beach had the highest abundance of horseshoe crab egg clusters out of all the beaches that our team monitors on Delaware Bay.

How do we keep the momentum going? How do we ensure our restoration work at Thompsons Beach yields long-term, sustainable results? The answer is clear: we protect the backbone that the beach sits on -- the salt marsh behind the beach.

Historically, the marsh was farmed and hayed for salt hay or Spartina patens. The salt hay farmers impounded the marsh and diked it for hundreds of years. The farming effort was abandoned mostly over the last 40 years, leaving behind a marsh about one and a half feet lower in elevation than unfarmed marsh. At a lower elevation with no natural tidal channels, the composition of certain areas changed from a lush, vegetated marsh to a mud flat. Besides being far less productive, mud flat contributes to the vulnerability of nearby houses upland in the event of a storm surge.

Over the last 20 years, PSEG chose the Thompsons Beach salt marsh as a mitigation site aimed to create more fish habitat by making natural tidal channels within the marsh. The elevation built up naturally to some degree and conditions today would be far worse without their effort.  

Conserve Wildlife Foundation of New Jersey and American Littoral Society are striving to leverage the existing work of PSEG to further restore the salt marsh. We will be building up the areas that didn’t recover from farming by bringing in sediment to add elevation. The materials will be coming from creeks dredged during PSEG’s previous restoration work on site. Over time, the creeks filled in again with mud. We will be using this mud to build up the marsh and open up the waterways for beach goers to launch their boats at different tide stages.

Before we begin our restoration work on the marsh, our ecologists are recording data points at over 400 locations in the salt marsh. Our goal is to plan for how much material we will need to add, and also, to document what we want to see changed ahead of time.

Joe Smith recording vegetation data at one of the points along the marsh.

Joe Smith, an ecologist with LJ Niles Associates, and his team are out in the field now measuring vegetation characteristics during peak growth time in the marsh. The team is collecting data on marsh cover and species composition, vegetation height, and vertical vegetation density.

Core samples will also be taken to see how root structure differs at varying elevation levels. The underground biomass in the root samples are a good indicator of marsh condition. This data will be combined with elevation levels from Stockton University’s Coastal Research Center. Then, the scientists will collaborate and look for patterns in the data to see what conditions they would like to try to replicate in the marsh.



Adding elevation to areas of the Thompsons Beach salt marsh is important now more than ever due to the threats of climate change and sea level rise. We are operating with a deficit to begin with and these new challenges only add to the need for strong science-based recommendations behind our restoration work. 

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An area in the marsh with higher elevation and lower grasses.

Ideally, the salt marsh would have areas of low and high elevation. Salt marsh sparrow, black rail and Northern harrier all thrive in marshes with higher elevation and shorter grasses. Seaside sparrow and clapper rail, however, prefer lower elevation and taller grasses. Right now, with its low elevation, the salt marsh has many areas of tall grasses. 

We can’t build the marsh up too high, as Phragmites love higher elevation. At a higher elevation, they are not as prone to the salty and wet conditions of the marsh. Joe Smith jokingly referred to our marsh restoration work as a “Goldilocks scenario.” We want to build the marsh back up high, but not too high as to provide Phragmites with their ideal habitat conditions. We are collecting baseline data from over 400 points to determine the ideal elevation for native plants, like Spartina patens and salt marsh flea bane, to grow.

Areas with elevation too high often become overrun with phragmites.

Our team is working tirelessly to restore what he calls the “natural mosaic of high and low” throughout the marsh.

Joe Atzert and Mark Caltagirone working in the marsh.

The stakes are high for the salt marsh at Thompsons Beach, as sea level rise and climate change threaten the ecosystems that keep our communities safe from harm and are home to so many flora and fauna. 

Joe Smith, who has worked as an ecologist on Delaware Bay for seven seasons, describes the marsh as vital for many seafood species. The marsh he says, is the “productive center of the marine ecosystem,” where many commercial fish, including blue crabs, spend the early stages of their life, taking advantage of the sheltered waters of the marsh. 

Follow along with us as we use science-based methods to elevate the marsh and restore the balance of Thompsons Beach’s backbone!