The contribution of salt marshes to wave attenuation during extreme storms.

Salt marshes' vegetation reduces wave attenuation by up to 50% at low-energy coasts but limits attenuation to 10% at high-energy coasts during extreme storms.

• Why it matters: Understanding how extreme storms damage salt marshes is crucial for predicting their long-term coastal protection role under climate change, yet comprehensive data on wave-marsh interactions are lacking.
• What they did: A unique experiment transferred intact salt marshes to a large wave flume and exposed them to waves up to 2 meters high, assessing erosion and vegetation damage across increasing wave energies.
• The result: The marsh platform remained stable with negligible erosion, but vegetation damage reduced wave attenuation, indicating substantial protection at low-energy coasts and limited attenuation at high-energy coasts.