Wave Attenuation by Oyster Reefs in Shallow Coastal Bays

• Published in: Estuaries and coasts Vol. 42; no. 2; pp. 331 - 347
• Main Authors: Wiberg, Patricia L., Taube, Sara R., Ferguson, Amy E., Kremer, Marnie R., Reidenbach, Matthew A.
• Format: Journal Article
• Language: English
• Published: New York Springer Science + Business Media 01-03-2019; Springer US; Springer Nature B.V
• Subjects: Bays; Brackishwater environment; Coastal Sciences; Coastal zone management; Coasts; Composition; Coral reefs; Earth and Environmental Science; Ecology; Environment; Environmental Management; Environmental restoration; Escarpments; Estuaries; Estuarine environments; Freshwater & Marine Ecology; Marine molluscs; Marshes; Mean sea level; ORIGINAL PAPERS; Oyster reefs; Protection; Reefs; Restoration; Sea level; Shore protection; Shoreline protection; Shorelines; Water and Health; Water depth; Wave attenuation; Wave energy; Wave height; Wave power; Waves; Salt marsh; Shallow coastal bays; Wave attenuation; Oyster reefs; Shoreline stabilization
• DOI: 10.1007/s12237-018-0463-y
• EISSN: 1559-2731
• ISSN: 1559-2723

Oyster reef restoration in shallow estuarine environments has been thought to have the potential to provide shoreline protection as well as oyster habitat. This study was designed to address the question of how effective oyster reefs are at attenuating wave energy in shallow coastal bays. Measurements were made of waves on both sides of four restored intertidal oyster reefs and at a control site with no reef; mean water depths ranged from 0.9 to 1.3 m. The reefs differed in composition and position relative to the shoreline, but all had reef crest elevations between 0.3 and 0.5 m below mean sea level. Differences in wave heights between the exposed/sheltered sides and upwind/downwind sides of the reefs were used to quantify the effects of the reefs on waves under varying tidal and wind conditions. All four reefs were able to reduce wave heights by an average of 30–50% for water depths of 0.5–1.0 m (bracketing the heights of reef crests) and 0–20% for water depths of 1.0–1.5 m (reef crests > 0.25 m below the water surface). For water depths greater than 1.5 m, there was < 10% change in wave heights. In contrast, there was no average decrease in wave height from the more seaward (exposed) to the more landward wave gauge at the control site regardless of water depth. Based on our results, we conclude that fringing oyster reefs can reduce the wave energy reaching the shoreline of marshes with edge elevations close to mean sea level. However, reefs like those in our study have little effect on waves during deeper water conditions, which allow for the largest waves, and are therefore less likely to offer protection to marshes characterized by high edge scarps and marsh surface elevations well above mean sea level.