Salt Marsh Ecosystem Services and Their Benefits

Salt marshes are coastal wetlands flooded and drained by salt water tides. As transitional areas between land and sea, they create a unique environment that supports a variety of life. The benefits humans receive from these natural environments are known as ecosystem services. Salt marshes provide numerous services that support coastal well-being and economic activities.

Coastal Protection

Salt marshes serve as a natural defense for coastlines by lessening the impacts of storms and coastal erosion. The dense stands of salt-tolerant plants, like cordgrass, act as a barrier that absorbs wave energy. During coastal storms and hurricanes, this vegetation reduces the height and force of the storm surge, protecting inland areas from flooding and damage. This natural buffer helps safeguard private property and coastal communities.

Below the surface, the network of plant roots and rhizomes binds sediment together. This root system creates a stable mat that holds the shoreline in place, resisting erosion from waves and currents. By preventing soil from washing away, salt marshes maintain the coastline’s integrity. This stabilization process helps counter the effects of sea-level rise and storms.

The structure of the marsh, with its vegetation and underlying peat, functions like a large sponge. It absorbs and holds large volumes of water, reducing the risk of flooding in adjacent upland areas. This capacity for water retention makes healthy salt marshes a form of natural infrastructure. Their presence along a coast can reduce the need for costly engineered structures like seawalls and bulkheads.

Water Filtration

Salt marshes help maintain the health of coastal waters by acting as natural filters. As water from tides and runoff flows through the marsh, its velocity slows. This allows suspended sediments and other particles to settle out of the water column and become trapped in the marsh soil, leading to clearer water in adjacent estuaries and bays.

The biological processes within the marsh also remove pollutants. Marsh plants, like Spartina, absorb excess nutrients such as nitrogen and phosphorus from the water. These nutrients, which come from agricultural and urban runoff, can cause harmful algal blooms that deplete oxygen and harm marine life. The marsh soil is also home to bacteria that break down various chemical pollutants.

By filtering out contaminants and trapping them in plant tissues and sediments, salt marshes prevent pollution from reaching sensitive marine ecosystems. This filtration supports the overall health of the coastal environment.

Habitat and Nursery Grounds

Salt marshes provide habitat that supports high biodiversity. These ecosystems offer food, refuge, and breeding grounds for many organisms, from microscopic invertebrates to large wading birds. The mix of saltwater and terrestrial influences creates a productive environment that sustains a complex food web.

Salt marshes act as nurseries for many commercially and recreationally important marine species. The protected, nutrient-rich waters are an ideal location for juvenile shrimp, crabs, and numerous fish to grow. The dense vegetation offers young animals cover from predators, increasing their chances of survival until they can move into open waters. The health of many fisheries is directly linked to the availability of healthy marsh habitat.

These ecosystems are also important for birdlife. Many resident and migratory birds depend on salt marshes for foraging and nesting. Wading birds stalk small fish and invertebrates in the shallow creeks, while other species build nests in the taller grasses. For migratory birds, salt marshes are stopover points where they can rest and feed during long journeys.

Climate Change Mitigation

Salt marshes help address climate change by capturing and storing atmospheric carbon dioxide, a process known as carbon sequestration. This makes them “blue carbon” sinks, which refers to carbon stored in coastal and marine ecosystems. Salt marshes are efficient at this process, capturing carbon at rates often higher than those of terrestrial forests.

Carbon is captured by marsh plants during photosynthesis and converted into organic matter. When these plants die, they decompose slowly in the waterlogged, low-oxygen soil, trapping the carbon in the sediment. This process allows large amounts of carbon to be locked away for long periods, sometimes for centuries or millennia, reducing greenhouse gases in the atmosphere.

The Southeast United States alone has over a million acres of salt marsh habitat contributing to the global carbon cycle. Sequestration occurs year-round, with carbon stored in living plants, dead plant material, and the mud itself. Conserving and restoring these ecosystems enhances their natural capacity to mitigate climate change impacts.