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Armored in concrete, hardened shorelines lose the soft protections of coastal wetlands

Hardening shorelines, polar lessons, and legal barriers to science-based conservation in the August 2015 issue of ESA's journal Frontiers in Ecology and the Environment

Ecological Society of America


IMAGE: Cover picture: Although climate change poses the largest anthropogenic threat to the Arctic and Antarctic, other impacts -- including pollution, fisheries overharvesting, and invasive species -- must not be overlooked.... view more

Credit: Ecological Society of America. Central photo: A Terauds. Background photo: D Bergstrom

As we expand our coastal cities and armor the coast against the ravages of the sea, we lose the resiliency of the coastlines' natural defenses. Rachel Gittman and colleagues at the University of North Carolina, NOAA, and the US Coast Guard report in the August issue of ESA Frontiers that sea walls, bulkheads, breakwaters, and the like put in place to protect coastal communities harden 14 percent (22,842 km) of the tidal shoreline of the United States. But this conservative 14 percent hides a concentration of coastal development along soft marshy estuaries, lagoons, and tidal rivers; remote rocky coasts are less likely to be bolstered with artificial structures.

Gittman and coauthors Danielle Keller and Joel Fodrie will present research related to this report on shoreline habitat, hardening, and the ecosystem services trade-offs of different shoreline conditions at the upcoming 100th Annual Meeting of the Ecological Society of America in Baltimore, Md. on August 9-14.

The ecological vibrancy of wetland habitats is valued by birders, hunters, recreational anglers, and commercial fisheries managers. Coastal wetlands succor birds, fish, and crustaceans, filter outflowing pollution, and naturally buffer the coast against storm surge and erosion. But natural dunes and salt marshes also absorb the energy of storms. Examples of natural dunes and salt marshes emerging from severe storms with little to no damage, while nearby bulkheads took a battering, suggest that storm surge protection and habitat protection need not be at odds.

Nearly a third of the shoreline in the contiguous United States could be hardened by the end of the twenty-first century if the rate of shoreline hardening observed over the last century continues. On sheltered coasts, fortification of shorelines correlates more strongly with high housing density and GDP than with wave height or frequent storms. The authors project that growing populations will direct most new hardening to the US' south Atlantic and Gulf coasts, which encompass greater that 50 percent of the remaining salt marshes and 100 percent of the mangrove forests in the US. The authors argue for the incorporation of green infrastructure into coastal protections as managers plan for the next century of growing cities and rising sea levels.

Also in the August issue of ESA Frontiers:

Cold lessons

Profoundly different in topography, ecology, and social history, the Arctic and Antarctic have very similar vulnerabilities to climate change. Climate change exacerbates problems of pollution, over-fishing, and invasive species at both poles. Joseph Bennett and colleagues describe this perfect storm of threats and lessons in cooperation from the polar regions.

Adaptive legalese

Environmental law has not kept up with the last 40 years of ecological discovery. The law struggles, in particular, to address dynamic ecosystems and adapt to the kind of global scale change ecologists expect in the coming century. The very different approaches to uncertainty and complexity in science and law bedevil the application of environmental research to environmental law. Lawyers and ecologists collaborate in this Concepts & Questions article by Olivia Odom Green and colleagues to recommend an adaptive governance approach to bridging the gap.


Browse the complete content of the August issue of Frontiers in Ecology and the Environment online.

The Ecological Society of America (ESA), founded in 1915, is the world's largest community of professional ecologists and a trusted source of ecological knowledge, committed to advancing the understanding of life on Earth. The 10,000 member Society publishes six journals and a membership bulletin and broadly shares ecological information through policy, media outreach, and education initiatives. The Society's Annual Meeting attracts 4,000 attendees and features the most recent advances in ecological science. Visit the ESA website at

Frontiers in Ecology and the Environment, issued 10 times per year, consists of peer-reviewed, synthetic review articles on all aspects of ecology, the environment, and related disciplines, as well as short, high-impact research communications of broad interdisciplinary appeal.

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