Between land and sea lie the ecological guardians of the coast—salt marshes.
Their grassy and sinuous channels fill and drain with saltwater as the tides ebb and flow, providing food, shelter, and nursery grounds for birds, fish, and other wildlife, ranging from dolphins and otters to snails and turtles.
Healthy salt marshes cleanse the water by filtering runoff, and help other ecosystems, including oyster reefs and seagrass beds, thrive. And conserving salt marsh helps people, too. Marshes can reduce erosion, stabilize shorelines, protect against storm surge, and support species that are crucial to recreational and commercial fishing, hunting, birding, and other activities.
Here are 11 things to know about salt marshes, and why they should be protected:
- The U.S. has approximately 3.8 million acres of salt marshes. Three-quarters of them are in the Southeast, including a vast interconnected 1 million-acre stretch from North Carolina to Florida.
- Salt marshes, and the estuaries that support them, provide shelter, food, and nursery grounds for more than 75% of commercial and recreational fish species in the country, including white shrimp, blue crab, redfish, and flounder.
- The National Oceanic and Atmospheric Administration (NOAA) estimates that the U.S. loses 80,000 acres of coastal wetlands, including salt marshes, each year, mostly due to development and sea-level rise, which can drown the marshes in places where there isn’t adequate undeveloped adjacent land to allow them to migrate.
- On average, salt marshes provide $695,000 of value per square mile during storms by reducing the impacts of surge and flooding, according to a University of California, San Diego study.
- During storms, salt marshes absorb flood waters and wave energy, decreasing property damage in adjacent communities by up to 20%, according to NOAA.
- One acre of salt marsh can absorb up to 1.5 million gallons of floodwater, which is equivalent to more than 2.25 Olympic-size swimming pools.
- By filtering runoff and excess nutrients, salt marshes help maintain water quality in coastal bays, sounds, and estuaries.
- Salt marshes provide important habitat for a variety of birds, including popular waterfowl and imperiled species such as the Eastern black rail, wood stork, and saltmarsh sparrow.
- Salt marshes get their salt from the seawater that comes in with the tides. They are marshy because their ground is composed of fine, muddy sediment and decomposing plant matter known as peat.
- Salt marshes and coastal wetlands sequester and store carbon at a rate 10 times that of mature tropical forests, helping to moderate the effects of climate change.
- Also known as tidal wetlands, salt marshes are one part of a complex coastal ecosystem with interdependent habitats. For example, by filtering pollutants, marshes help oyster reefs and seagrass beds, which need clean water to survive. But as salt marshes degrade, the health of adjacent coastal habitats and marine life suffers.
Conserving salt marshes is important to maintaining shorelines, protecting communities, keeping marine ecosystems healthy, and helping coastal economies thrive. Communities can and should work together to develop plans that restore, protect, and allow these vital habitats to adapt to changing environmental conditions.
Holly Binns directs The Pew Charitable Trusts’ efforts to protect ocean life in the Gulf of Mexico and the U.S. Caribbean. Joseph Gordon directs the work along the U.S. East Coast.