Salt Marshes

These wetlands, regularly flooded by tides, are found across the world, primarily along estuaries and coastal lagoons in Arctic, temperate, and subtropical regions. Their vegetation consists of salt-tolerant grasses, herbs, and shrubs that thrive in these dynamic, tidal environments. Despite their importance, salt marshes are under threat, with an estimated global loss rate of 1–2% per year. Comprehensive global mapping of salt marshes is still in its early stages, with data available for just 43 countries, covering only about 14% of the potential global area.

Key Benefits of Salt Marshes

Carbon Sequestration

Salt marshes are powerful carbon sinks, storing carbon at rates 55 times faster than tropical rainforests. The carbon stored in their soils and vegetation helps mitigate climate change.
Coastal Protection

Acting as natural buffers, salt marshes absorb storm surges and reduce the height and energy of waves before they reach the shore. Their dense root systems stabilize soil, protecting shorelines from erosion. They also grow vertically by trapping sediment, helping them keep pace with rising sea levels.
Improved Water Quality

Salt marshes filter runoff, reducing nitrogen pollution in estuaries and lessening the risk of harmful algal blooms and marine dead zones.
Biodiversity Hotspots

Salt marshes provide critical habitats for migratory birds, fish, shellfish, and other wildlife. They also provide refuge for juvenile species, protecting them from predators.
Supporting Fisheries

Many commercially valuable species, such as fish, crabs, and oysters, rely on salt marshes for breeding and feeding, which supports local fisheries and economies.
Recreation and Ecotourism

Salt marshes are popular destinations for birdwatching, kayaking, and recreational fishing, contributing to local tourism industries.

Pressures on Salt Marshes

Coastal Development
Urbanization and infrastructure projects often encroach on salt marsh areas, leading to habitat destruction and fragmentation.
Climate Change
Rising temperatures and extreme weather events can erode salt marshes and damage their plant life, while sea-level rise reduces the space available for marsh migration.
Water Pollution
Runoff containing pesticides, heavy metals, and excess nutrients harms water quality and marsh health, leading to algal blooms and oxygen depletion.
Hydrological Changes
Dams and water diversion projects disrupt the flow of freshwater and sediment that salt marshes need to thrive.
Recreational Damage
Boating, hiking, and other activities can physically damage sensitive areas, further degrading the habitat.
Invasive Species
Non-native plants, such as Phragmites australis, can outcompete native vegetation, while certain invasive animals can overgraze the marshes.
Diseases
Salt marshes are susceptible to pathogens, which can reduce biodiversity and undermine their vital functions.

Taking Action to Restore Salt Marshes

Protecting Existing Marshes
Restoring Hydrology
Managing Sediment
Addressing Pollution
Nature-Based Solutions

Climate Mitigation
Marine Spatial Planning
Community Engagement
Financial Incentives
Research and Monitoring
International Alignment

Credits

Carlos Duarte
Vanesa Chalastani
Letizia Valluzzi

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