Salt Marsh Monitoring Program

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Salt Marsh Program

What are Salt Marshes?

Salt marshes are coastal wetlands that form transition zones between land and sea. They provide habitat for wildlife, serve as nurseries for fish and shellfish, store floodwaters, and protect our shorelines against storm surge damage. Salt marshes also act as natural purifiers by filtering pollutants and sediment and by absorbing excess nutrients from streams, rivers, and surface runoff before they can reach coastal waters and drinking water supplies.

Subjected to the daily rise and fall of the sea, the salt marsh environment is constantly changing. Incoming freshwater from rivers, streams and groundwater mixes with tidal saltwater resulting in frequent and rapid changes in salinity, temperature and water depth within the salt marsh system. Salt marshes are characterized by plants and animals that tolerate changes in water temperature, depth, and salinity (ranging from 0-35 ppt).

Cape Cod salt marshes provide nesting, feeding and breeding habitat for a variety of animals. Among these are the rare and protected northern harrier, least tern, king rail, river herring, the Massachusetts-listed diamondback terrapin and eastern box turtle. (Click photos to enlarge)  

Northern Harrier Herring King Rail Least Tern Eastern Box Turtle Diamondback Terrapin lightbox visualby v5.7

What Happened to Our Salt Marshes?

Since colonial times, a significant portion of our nation’s salt marshes have been degraded or altered by agriculture, mosquito-ditching, channeling, urban development and other legacies of human activities. On Cape Cod 38% or about 7,000 acres of our historical salt marshes have been lost or severely degraded.

Roads and railroad tracks bisect and damage marshes by restricting the tidal flow that nourishes them. When tidal flow is restricted, these once-saline environments change to a brackish or freshwater condition in which native salt marsh vegetation suffers. Typically, these marshes become colonized by the invasive common reed (Phragmites australis), which forms dense stands 12 feet or higher. As invasive species take over, a major shift in wildlife occurs, and formerly diverse communities of salt marsh inhabitants are replaced by fewer species.

How Are We Helping?

In 2003 APCC launched its salt marsh monitoring program, in consultation with the Massachusetts Offices of Coastal Zone Management and Mass Bays Program to:

  • Increase awareness and stewardship of salt marshes through direct study of ecology and function;
  • Build and maintain a skilled base of volunteers;
  • Obtain scientifically useful and relevant information on key indicators of salt marsh health and
  • Document the need for and effectiveness of restoration.

How Can You Help?

It takes a team to monitor a salt marsh. APCC’s salt marsh program relies on the dedication and enthusiasm of its volunteers. In salt marshes across Cape Cod, numerous volunteers monitor critical indicators of salt marsh health. Through this experience volunteers become stewards of the salt marsh and gain appreciation for its wonders, functions and benefits. Without their involvement the program would not be possible.

To find out more about becoming a salt marsh monitor, please email Tara Nye at or call the APCC office at 508-362-4226.