Infantes E, Hoeks S, Adams MP, van der Heide T, van Katwijk MM, Bouma TJ

Seagrass roots strongly reduce cliff erosion rates in sandy sediments

The canopies of coastal vegetation such as mangroves, saltmarshes and seagrass beds are known to contribute to coastal defence by reducing wave energy. The ability of roots, however, to reduce coastal erosion remains less clear and likely depends on the sediment types they grow on. We investigated how root mats of seagrass mitigate wave-induced cliff erosion using seagrass in manipulative flume experiments. The seagrass Zostera marina was able to reduce up to 70% of cliff erosion rates in sandy sediment containing high root biomass, while erosion rates in muddy sediments were unaffected by the presence of roots. This highlights the important role of roots in erosion mitigation, which has been overlooked compared to the role of canopies which has received more attention. Therefore, we suggest establishing management strategies using seagrass to enhance sediment stabilization.

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