Oyster reefs as natural breakwaters mitigate shoreline loss and facilitate fisheries

Published source details Scyphers S.B., Powers S.P., Heck Jr. K.L. & Bryron D. (2011) Oyster reefs as natural breakwaters mitigate shoreline loss and facilitate fisheries. PLoS ONE, 6, e22396.
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This study is summarised as evidence for the following.

	Action	Category
	Build barriers to protect littoral brackish/salt marshes from rising water levels and severe weather Action Link

Build barriers to protect littoral brackish/salt marshes from rising water levels and severe weather

A replicated, randomized, paired, controlled study in 2007–2009 of two salt marshes in Alabama, USA (Scyphers et al. 2011) found that installing offshore oyster shell reefs had no significant effect on the rate of shoreline retreat. Over approximately two years, the vegetated shoreline receded by a statistically similar amount whether it was behind an oyster shell reef (3.1–5.1 m retreat) or left unprotected (4.5–5.5 m retreat). Methods: The study used eight sites across two rapidly eroding shorelines. At four sites (two random sites/shoreline), oyster shell was deposited just offshore to form a breakwater (three 5 x 25 m sections; top exposed during low tides). The shell was placed on geotextile fabric and anchored in place with plastic mesh. It was colonized by oysters Crassostrea virginica. The other four sites were left unprotected. Stakes were inserted at the seaward limit of emergent vegetation when the reefs were constructed. Retreat relative to these stakes was measured over 24–27 months.

(Summarised by: Nigel Taylor)