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Seawalls: Ecological effects of coastal armoring in soft sediment environments

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July 24 2017 UC Santa Barbara read full ScienceDaily article here

For nearly a century, the O’Shaughnessy seawall has held back the sand and seas of San Francisco’s Ocean Beach. At work even longer: the Galveston seawall, built after America’s deadliest hurricane in 1900 killed thousands in Texas. These are just two examples of how America’s coasts — particularly those with large urban populations — have been armored with humanmade structures.

While the resulting ecological effects [of sea walls] have been studied more in recent years, the research largely has been conducted in specific settings, making it difficult to generalize these effects across ecosystems and structure types.

…”Our review not only revealed major gaps in knowledge but also highlighted the fact that existing information on ecological responses to armoring is unevenly distributed across soft sediment habitat types and does not necessarily cover the range of potential environmental and armoring contexts”

…”Understanding how these ecological responses vary with hydrodynamic energy and their effect on water flow could help people design and install armoring structures that could have less ecological impact,” Dugan said. “Then, the menu of options would contain not only the cost of the structure but also some idea of the ecological implications of each type of structure based on the environmental setting.

“This is one of the first attempts to assess how engineering structures on beaches and other sedimentary environments affect the biota that inhabits these locations,” said David Garrison, an LTER program director at the National Science Foundation, which supported the research. With some 40 percent of the nation’s human population living in coastal counties, Garrison noted that the study is certainly timely.

…”Our review not only revealed major gaps in knowledge but also highlighted the fact that existing information on ecological responses to armoring is unevenly distributed across soft sediment habitat types and does not necessarily cover the range of potential environmental and armoring contexts”

J. E. Dugan, K. A. Emery, M. Alber, C. R. Alexander, J. E. Byers, A. M. Gehman, N. McLenaghan, S. E. Sojka. Generalizing Ecological Effects of Shoreline Armoring Across Soft Sediment Environments. Estuaries and Coasts, 2017; DOI: 10.1007/s12237-017-0254-x

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