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PeerJ. 2018 Feb 23;6:e4275. doi: 10.7717/peerj.4275. eCollection 2018.

Quantifying the effectiveness of shoreline armoring removal on coastal biota of Puget Sound.

Author information

Department of Biology, East Carolina University, Greenville, NC, USA.
School of Marine and Environmental Affairs, University of Washington, Seattle, WA, USA.
School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, USA.
Department of Biology, Friday Harbor Laboratories, University of Washington, Friday Harbor, WA, USA.
Washington Sea Grant, College of the Environment, University of Washington, Seattle, WA, USA.


Shoreline armoring is prevalent around the world with unprecedented human population growth and urbanization along coastal habitats. Armoring structures, such as riprap and bulkheads, that are built to prevent beach erosion and protect coastal infrastructure from storms and flooding can cause deterioration of habitats for migratory fish species, disrupt aquatic-terrestrial connectivity, and reduce overall coastal ecosystem health. Relative to armored shorelines, natural shorelines retain valuable habitats for macroinvertebrates and other coastal biota. One question is whether the impacts of armoring are reversible, allowing restoration via armoring removal and related actions of sediment nourishment and replanting of native riparian vegetation. Armoring removal is targeted as a viable option for restoring some habitat functions, but few assessments of coastal biota response exist. Here, we use opportunistic sampling of pre- and post-restoration data for five biotic measures (wrack % cover, saltmarsh % cover, number of logs, and macroinvertebrate abundance and richness) from a set of six restored sites in Puget Sound, WA, USA. This broad suite of ecosystem metrics responded strongly and positively to armor removal, and these results were evident after less than one year. Restoration responses remained positive and statistically significant across different shoreline elevations and temporal trajectories. This analysis shows that removing shoreline armoring is effective for restoration projects aimed at improving the health and productivity of coastal ecosystems, and these results may be widely applicable.


Armoring; Biota; Coastlines; Cohen’s D; Effect size; Macroinvertebrates; Response; Restoration; Restoration trajectory; Shoreline

Conflict of interest statement

The authors declare that they have no competing interests.

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