Designing restored oyster reefs to enhance coastal protection benefits

Highlights

• Retreat rates of nearby reef-lined and un-lined marshes were measured in-situ with erosion pins.
• Oyster reefs only reduced wave energy in shallow water on gently sloped shorelines.
• Oyster substrates can be used separately or together to accommodate shoreline geomorphology.
• Oyster Catcher™ fostered greater oyster growth than Oyster Castles.
• Oyster reefs facilitate marsh growth by allowing a steep edge to become more gradually sloped.

Abstract

As sea levels rise and storms become more intense, many coastal communities that rely on the natural buffering capacity of marshes from winds and waves are becoming more vulnerable. There is considerable interest in using “living shorelines” as nature-based solutions for coastal protection that stabilize shorelines and enhance ecological communities. This study evaluated restored oyster reefs as a nature-based solution for attenuating waves and stabilizing marsh edges in coastal Virginia, USA. Oyster Castles and Oyster Catcher™, a new biodegradable reef substrate, were placed adjacent to an actively eroding marsh island. Field measurements were collected before and after reef construction to quantify changes to the wave, morphologic and ecologic environments related to reef presence. Oyster reefs successfully dissipated wind-wave energy, but only when water depths were near or below reef crest heights on the more gently sloping section of the shoreline. In situ measurements of reef-lined and un-lined marshes showed reefs reduced rates of marsh edge erosion, but only the portion of the shoreline lacking a significant edge scarp. However, fringing reefs did slow erosion of the marsh toe for both the more gently sloped and steeper sections of the shoreline. Oyster Castles and Oyster Catcher™ substrate both fostered oyster growth with greater densities recorded on Oyster Catcher™. This study demonstrates that a combination of marsh morphology and fringing oyster reef presence determines the degree to which wave energy causing marsh edge retreat is reduced. To enhance coastal protection and ecological benefits, marsh edge morphology, reef elevation and substrate type should be considered when designing oyster reef restoration projects.

Citation

Elizabeth R. Bieri, Patricia L. Wiberg, Bowdoin W. Lusk, Matthew A. Reidenbach, Designing restored oyster reefs to enhance coastal protection benefits, Estuarine, Coastal and Shelf Science, Volume 341, 2026, 110156, ISSN 0272-7714, https://doi.org/10.1016/j.ecss.2026.110156.