Coastal Wetland Dynamics and Ecosystem Services

Coastal wetlands encompass salt marshes, mangroves, tidal flats and seagrass meadows that lie at the interface of land and sea. Their dynamics are governed by a balance of sediment supply, hydrodynamic energy, vegetation growth and relative sea-level changes. Vegetation traps mineral sediment and organic matter, enabling vertical accretion that can offset subsidence and sea-level rise. Conversely, reduced sediment delivery, land subsidence and accelerating sea-level rise can lead to wetland retreat or conversion to open water. Coastal wetlands deliver a suite of ecosystem services including carbon sequestration, shoreline stabilisation, flood attenuation, water filtration and habitat provision for fisheries and wildlife. These services deliver substantial economic and social benefits, underpinning climate-adaptation strategies worldwide. Restoration and conservation efforts increasingly employ nature-based defences to harness these functions, while monitoring of biogeochemical processes informs management under changing climatic and anthropogenic pressures.

Research from Nature Portfolio

Recent studies have revealed that the capacity of tidal marshes and mangroves to adjust to relative sea-level rise declines sharply beyond thresholds of 4–7 mm yr⁻¹, with higher warming scenarios doubling the area at risk of retreat by the end of this century. Analyses of palaeo-stratigraphic records aligned with in situ measurements demonstrate consistent probabilities of vertical adjustment under varying rates of sea-level rise. In parallel, high-resolution satellite observations along the US Atlantic coast show that local land subsidence exceeding 3 mm yr⁻¹ affects most coastal wetlands, with as much as 100 % of marshes losing elevation relative to rising seas. These findings refine vulnerability assessments by integrating sedimentation, subsidence and sea-level rise into a unified framework, highlighting hotspots of wetland loss and guiding targeted adaptation measures.

Coastal Wetland Dynamics and Ecosystem Services publication trend

The graph below shows the total number of articles in coastal wetland dynamics and ecosystem services across all publications each year (not limited to Nature Index journals).

Technical terms

Relative sea-level rise (RSLR): Combined effect of global sea-level rise and local land elevation change.

Vertical accretion: Build-up of sediment and organic matter that increases wetland surface elevation.

Subsidence: Low-lying land sinking due to natural compaction or anthropogenic extraction of groundwater or sediments.

Ecosystem services: Benefits provided by ecosystems to society, including climate regulation, flood protection and biodiversity support.

Biogenic feedbacks: Processes by which living organisms influence sediment deposition and hydrodynamics to stabilise or alter habitat form.

Nature-based defence: Use of natural or restored habitats to reduce coastal hazard exposure and erosion.

References

1. Widespread retreat of coastal habitat is likely at warming levels above 1.5 °C. Nature (2023).
2. Hidden vulnerability of US Atlantic coast to sea-level rise due to vertical land motion. Nature Communications (2023).
3. The Effectiveness, Costs and Coastal Protection Benefits of Natural and Nature-Based Defences. PLOS ONE (2016).
4. The Protective Role of Coastal Marshes: A Systematic Review and Meta-analysis. PLOS ONE (2011).
5. A global perspective on wetland salinization: ecological consequences of a growing threat to freshwater wetlands. Ecosphere (2015).
6. Updated estimates of carbon accumulation rates in coastal marsh sediments. Biogeosciences (2014).
7. Wetlands In a Changing Climate: Science, Policy and Management. Wetlands (2018).