Coastal Wetlands

Coastal wetlands represent ecosystems that are permanently or seasonally inundated with either fresh, brackish, or saline water that is usually less than 6 feet in depth at low tide. [^8] [^9] There are different types of coastal wetlands: salt marshes, fresh marshes, mangroves, and sea/eel grasses. In the United States, coastal wetlands cover about 40 million acres and makeup 38 percent of the total wetland acreage.[^1] The ecosystem services provided by coastal wetlands are essential to people and the environment. Services that are provided can include flood protection, erosion control, habitat and, fisheries preservation, water quality abatement, recreation, and carbon sequestration.[^2]

Types of coastal wetland

Tidal salt marshes are usually found in areas where the accumulation of sediment occurs at the same or higher rate than land subsidence. They are important for supporting the spawning and feeding of several marine organisms. Hence, they represent a critical interface between the land and sea.
Mangroves swamps are estimated to occupy between 16 and 18 million hectares of coastal areas globally. In tropical and subtropical areas, mangrove swamps replace salt marshes. In some instances, both mangrove swamps and salt marshes exist together.
Tidal freshwater marshes are located close to tidal zones, but out of the reach of oceanic salt water. They comprise several features including salt marshes and freshwater marshes. Tidal freshwater marshes possess similar structural and functional characteristics as salt marshes. However, tidal freshwater marshes are more diverse because of reduced salt stress.
Riparian wetlands are ecotones or interfaces that exist between aquatic and upland ecosystems. They possess distinctive vegetative and soil characteristics. Riparian wetlands are difficult to distinguish from surrounding landscapes therefore they are classified as mosaics of landforms and communities within a larger landscape. [^10]

✓ Benefits

Protect upland areas from sea level rise, and storm surges by buffering wave action.
Reduces the frequency and intensity of floods by buffering and storing a significant amount of floodwater.
Provides habitat for threatened and endangered species.
Serves as a water filter for chemicals and sediments before they enter coastal waters.
Sequesters carbon in salt marshes and mangroves. [^11]

✗ Challenges

Lack of integrated understanding of coastal ecosystems. Wetlands represent complex ecosystem interactions and understanding the interactions between these subsystems is still evolving.
Transference of knowledge to practice is stymied by conflicts between coastal interests. [^12]
Development pressures for residential and commercial space could lead to the loss of wetlands endangered species.
Habitat degradation from chemicals and sediments due to land-use change inland. [^13]