Salt marshes, mangroves, tidal freshwater marshes, swamps, estuaries, flood protection, erosion control, fisheries, migratory birds, blue carbon, sediment, water quality, sea level rise, restoration, coastal watersheds, and resilience
Coastal wetlands
Coastal wetlands are wetland habitats in coastal watersheds, including salt marshes, mangroves, tidal marshes, and coastal swamps.
What coastal wetlands are
Coastal wetlands are wetlands located in coastal watersheds. They include salt marshes, mangrove swamps, tidal freshwater marshes, forested wetlands, bottomland hardwood swamps, and other wet habitats influenced by coastal water, tides, rivers, or groundwater.
Where they form
These wetlands form along estuaries, bays, river mouths, lagoons, deltas, barrier islands, and low coastal plains. Some are flooded daily by tides, while others sit farther inland but still drain toward coastal waters.
Flood and storm protection
Coastal wetlands can absorb and slow moving water during storms, high tides, and heavy rainfall. Their plants and shallow surfaces help reduce wave energy and provide a buffer between open water and upland communities.
Water quality
Wetlands trap sediment, cycle nutrients, and filter some pollutants before water reaches bays and estuaries. Healthy coastal wetlands can improve water clarity and reduce stress on seagrass, oyster reefs, and other nearshore habitats.
Wildlife and fisheries
Many fish and shellfish use coastal wetlands as nursery grounds. Migratory birds, wading birds, reptiles, mammals, insects, and amphibians use them for feeding, nesting, refuge, and seasonal stopovers.
Blue carbon
Some coastal wetlands store large amounts of carbon in waterlogged soils. Salt marshes, mangroves, and other tidal wetlands can build carbon-rich sediments when plant growth and sediment trapping outpace decomposition and erosion.
Threats and loss
Coastal wetlands are lost or degraded by development, drainage, dredging, pollution, shoreline hardening, invasive species, altered river flows, subsidence, erosion, storms, and sea level rise. Loss can also happen when wetlands cannot migrate inland.
Why it matters
Coastal wetlands connect land and sea. Protecting and restoring them supports cleaner water, fisheries, wildlife, flood resilience, shoreline stability, carbon storage, and the long-term health of coastal communities.