The Protective Role of Coastal Marshes: A Systematic Review and Meta-analysis

By C. Shepard, Caitlin MULLAN CRAIN, M. Beck. PLoS ONE, 2011

643 citations recorded by the source corpus.

Background Salt marshes lie between many human communities and the coast and have been presumed to protect these communities from coastal hazards by providing important ecosystem services. However, previous characterizations of these ecosystem services have typically been based on a small number of historical studies, and the consistency and extent to which marshes provide these services has not been investigated. Here, we review the current evidence for the specific processes of wave attenuation, shoreline stabilization and floodwater attenuation to determine if and under what conditions salt marshes offer these coastal protection services. Methodology/Principal Findings We conducted a thorough search and synthesis of the literature with reference to these processes. Seventy-five publications met our selection criteria, and we conducted meta-analyses for publications with sufficient data available for quantitative analysis. We found that combined across all studies (n = 7), salt marsh vegetation had a significant positive effect on wave attenuation as measured by reductions in wave height per unit distance across marsh vegetation. Salt marsh vegetation also had a significant positive effect on shoreline stabilization as measured by accretion, lateral erosion reduction, and marsh surface elevation change (n = 30). Salt marsh characteristics that were positively correlated to both wave attenuation and shoreline stabilization were vegetation density, biomass production, and marsh size. Although we could not find studies quantitatively evaluating floodwater attenuation within salt marshes, there are several studies noting the negative effects of wetland alteration on water quantity regulation within coastal areas. Conclusions/Significance Our results show that salt marshes have value for coastal hazard mitigation and climate change adaptation. Because we do not yet fully understand the magnitude of this value, we propose that decision makers employ natural systems to maximize the benefits and ecosystem services provided by salt marshes and exercise caution when making decisions that erode these services.

Subfields: Earth-Surface Processes, Ecology, Oceanography

View Paper: https://www.semanticscholar.org/paper/843e6c3af367bfb19d70975e9aeae224fb3d02f9

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Citations in the corpus

Climate change's impact on key ecosystem services and the human well‐being they support in the US (2013, background): “Habitats along the US shoreline (eg marshes, coastal forests, and reefs) provide protection from erosion and storms by attenuating waves and stabilizing shorelines (Shepard et al. 2011).”
Valuing Ecosystem Services for Coastal Wetland Protection and Restor ation : Progress and Challenges (2013, background): “Field studies indicate that coastal marsh vegetation significantly impacts wave attenuation, as measured by reductions in wave height per unit distance across a wetland [10,29,30].”
A global predictive model of carbon in mangrove soils (2014, background): “…including serving as primary nursery habitat for many species of fish, crustaceans, birds, and marine mammals, and protecting coastal communities from coastal erosion and damage from storms and other natural hazards (Mumby et al 2004, Spalding et al 2010, Twilley et al 1996, Shepard et al 2011).”
Humans and Nature: How Knowing and Experiencing Nature Affect Well-Being (2013, background): “For example, it has been shown that in coastal systems, nearshore habitats, such as reefs, marshes, and dunes, can significantly reduce the damage caused by sea-level rise and storms (112, 113), but we found no studies examining how this protective role changes people’s perceptions of safety.”