Estuaries and Salt Marshes

Salt marsh in Hatches Harbor

Photo by Naomi Blinick

The Cape Cod landscape is one of many estuaries and salt marshes. These ecosystems can be found along both the bay and ocean shores in what is known as the intertidal zone; any area that is regularly inundated by the tide.

The term estuary is a broad one used to describe an area where fresh water meets the sea. As freshwater flows into a marine environment, it carries with it nutrients from terrestrial run-off. Thus, estuaries are almost always associated with high biological productivity making them important ecological and economic systems. For many marine fishes and invertebrates estuaries serve as habitat in which they can find shelter, breed, and forage. Estuaries also have tremendous recreational value as they offer an ideal setting for fishing, kayaking, and photography.

Salt marshes are also located in the intertidal zone. In New England, they are marked by communities of salt-tolerant vegetation often found among a mosaic of meandering tidal creeks. Most often, salt marshes occur in low-energy locations where the land is some-what sheltered from the direct flow of the tide. Salt marshes are among the most biologically productive ecosystems on earth and play an important role in filtering out nutrients. Salt marshes serve as critical habitat for a host of important animals species including fishes, shellfish, and birds.

Due to the critical nature of these systems, the Cape Cod National Seashore has undertaken an ambitious program of estuarine monitoring and salt marsh restoration. You can learn much more about these by visiting the links below:

 

CCNS staff and Mosquito Control restoring clogged mosquito ditches in Nauset Marsh

Photo by Madelyn Lewis

Salt Marsh Restoration at Cape Cod National Seashore

• Herring River (Wellfleet)
• East Harbor (Truro)
• Hatches Harbor (Provincetown)

Mosquito Drainage Ditches at Nauset Marsh

The National Park Service and Mosquito Control of Cape Cod are collaborating on a project to remove sediment and plant matter that has filled existing mosquito ditches in Nauset Marsh. The clogged ditches have resulted in flooded conditions in the marsh, in which vegetation can’t survive. Restoring the ditches will improve drainage, reducing mosquito breeding habitat and promoting regrowth of vegetation. Additionally, the restored connectivity in the marsh will improve access for predators of mosquitos.

The field work was conducted on March 9 and 10, 2026.

 

Aerial image of East Harbor and the adjacent Province Lands dunescape. Route 6 winds along the harbor on the right.

Adaptive Management in Tidal Restoration Projects

• East Harbor Water Level Manipulations

Salt Marsh Dieback

• Salt Marsh Vegetation Losses on Cape Cod
• Revegetation of Salt Marsh Dieback Areas