Wave Attenuation by Oyster Reefs in Shallow Coastal Bays
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.
KeywordsOyster reefs Salt marsh Wave attenuation Shoreline stabilization Shallow coastal bays
We thank the staff of the Anheuser-Busch Coastal Research Center and The Nature Conservancy for logistical support, particularly David Boyd (ABCRC) and Bo Lusk (TNC).
This research was supported by the National Science Foundation through the VCR LTER award 1237733 and by a grant from the National Fish and Wildlife Foundation to The Nature Conservancy (2300.14.042551).
- Day, J.W., Jr., F. Scarton, A. Rismondo, and D. Are. 1998. Rapid deterioration of a salt marsh in Venice lagoon, Italy. Journal of Coastal Research 14: 583–590.Google Scholar
- Drexler, M., M.L. Parker, S.P. Geiger, W.S. Arnold, and P. Hallock. 2014. Biological assessment of eastern oysters (Crassostrea virginica) inhabiting reef, mangrove, seawall, and restoration substrates. Estuaries and Coasts 37 (4): 962–972. https://doi.org/10.1007/s12237-013-9727-8.CrossRefGoogle Scholar
- Emery, K.A. 2015. Man and boy marsh shoreline change. Report for The Nature Conservancy.Google Scholar
- Ferguson, A.E. 2018. Evaluating nature-based solutions to storm wave impacts in the Virginia coast reserve. M.S. Thesis, University of Virginia, Charlottesville, VA, 188 pp.Google Scholar
- Malhotra, A., and M.S. Fonseca. 2007. WEMo (Wave Exposure Model): Formulation, Procedures and Validation.NOAA Technical Memorandum NOS NCCOS 65. NOAA/National Ocean Service/National Centers for Coastal Ocean Science, Beaufort, NC, 28 pp.Google Scholar
- Möller, I., M. Kudella, F. Rupprecht, T. Spencer, M. Paul, B.K. van Wesenbeeck, G. Wolters, K. Jensen, T.J. Bouma, M. Miranda-Lange, and S. Schimmels. 2014. Wave attenuation over coastal salt marshes under storm surge conditions. Nature Geoscience 7 (10): 727–731. https://doi.org/10.1038/ngeo2251.CrossRefGoogle Scholar
- Rodriguez, A.B., F.J. Fodrie, J.T. Ridge, N.L. Lindquist, E.J. Theuerkauf, S.E. Coleman, J.H. Grabowski, M.C. Brodeur, R.K. Gittman, D.A. Keller, and M.D. Kenworthy. 2014. Oyster reefs can outpace sea-level rise. Nature Climate Change 4 (6): 493–497. https://doi.org/10.1038/nclimate2216.CrossRefGoogle Scholar
- Schwimmer, R.A. 2001. Rates and processes of marsh shoreline erosion in Rehoboth Bay, Delaware, U.S.A. Journal of Coastal Research 17: 672–683.Google Scholar
- Stricklin, A.G., M.S. Peterson, J.D. Lopez, C.A. May, C.F. Mohrann, and M.S. Woodrey. 2009. Do small, patchy, constructed intertidal oyster reefs reduce salt marsh erosion as well as natural reefs? Gulf and Caribbean Research 22: 21–27.Google Scholar
- Taube, S.R. 2013. Impacts of fringing oyster reefs on wave attenuation and marsh erosion rates. M.S. thesis, University of Virginia, Charlottesville, VA, 157pp.Google Scholar
- Woodhouse, W.E., Jr., and P.L. Knutson. 1982. Atlantic coastal marshes. In Creation and restoration of coastal plant communities, ed. R.R. Lewis III. Boca Raton: CRC Press, Inc. 219 p.Google Scholar
- Wray, R.D., S.P. Leatherman, and R.J. Nicholls. 1995. Historic and future land loss for upland and marsh islands in the Chesapeake Bay, Maryland, U.S.A. Journal of Coastal Research 11: 1195–1203.Google Scholar