Frequently Asked Questions

https://doi.org/10.1080/08920753.2016.1160201

“Globally, shoreline protection approaches are evolving towards the incorporation of natural and nature-based features (living shorelines henceforth) as a preferred alternative to shoreline armoring. Emerging research suggests that living shorelines may be a viable approach to conserving coastal habitats (marshes, beaches, shallows, seagrasses) along eroding shorelines. Living shorelines typically involve the use of coastal habitats, such as wetlands, that have a natural capacity to stabilize the shore, restore or conserve habitat, and maintain coastal processes. They provide stability while still being dynamic components of the ecosystem, but due to their dynamic nature, careful designs and some maintenance will be required if habitat conservation is a goal. Living shorelines may represent a singular opportunity for habitat conservation in urban and developing estuaries because of their value to society as a shoreline protection approach and resilience to sea level rise. However, enhanced public acceptance and coordination among regulatory and advisory authorities will be essential to expand their use. To fully understand their significance as habitat conservation strategies, systematic and standardized monitoring at both regional and national scales is vital to evaluate the evolution, persistence, and maximum achievable functionality (e.g., ecosystem service provision) of living shoreline habitats.”

https://doi.org/10.3354/meps07279

“Coastal development affects estuarine resources by severing terrestrial–aquatic linkages, reducing shallow water habitats, and degrading ecosystem services, which is predicted to result in measurable declines in nekton community integrity. We assessed the effects of landscape features on nearshore habitats and biological communities, relating subtidal habitat, shoreline condition, upland land use and nearshore fish communities in a Chesapeake Bay tributary, the James River, Virginia. Both upland development and the placement of erosion control structures on the shoreline were associated with reduced fish community integrity, and shoreline alterations were linked with the amount of subtidal structural habitat in the nearshore. Ecological thresholds in nekton community integrity were evident at ≥23% developed land use within 200 and 1000 m buffer increments. Nekton assemblages at sites with low development (< 23%) and natural or riprap shorelines were different from all other combinations of altered conditions (low development with bulkhead, and high development with riprap or bulkhead). Species composition along natural or riprap revetment shorelines with low upland development tended to be diverse and inclusive of tidal marsh species, while highly developed sites or bulkhead shorelines were dominated by a few generalist species. The complex interaction between watershed (both nearshore and inland) and shoreline development presents a unique challenge for coastal planning. Alternate moderating approaches for coastal development may include preservation of riparian buffers, the placement of living shorelines for erosion control where appropriate, and development of targeting tools to identify landscapes near an ecological threshold.”

https://doi.org/10.1007/s11273-004-5543-z

“Seawalls are often built along naturally dynamic coastlines, including the upland edge of salt marshes, in order to prevent erosion or to extend properties seaward. The impacts of seawalls on fringing salt marshes were studied at five pairs of walled and natural marshes in the Great Bay Estuary of New Hampshire, USA. Marsh plant species and communities showed no difference in front of walls when compared with similar elevations at paired controls. However, seawalls eliminated the vegetative transition zone at the upper border. Not only did the plant community of the transition zone have high plant diversity relative to the low marsh, but it varied greatly from site to site in the estuary. The effects of seawall presence on other marsh processes, including sediment movement, wrack accumulation, groundwater flow, and vegetation distribution and growth, were examined. Although no statistically significant effects of seawalls were found, variation in the indicators of these processes were largely controlled by wave exposure, site-specific geomorphology and land use, and distance of the sampling station from the upland. Trends indicated there was more sediment movement close to seawalls at high energy sites and less fine grain sediment near seawalls. Both trends are consistent with an increase in energy from wave reflection. The distribution of seawalls bordering salt marshes was mapped for Great and Little Bays and their rivers. Throughout the study area, 3.54% of the marshes were bounded by shoreline armoring (5876 m of seawalls along 165.8 km of marsh shoreline). Localized areas with high population densities had up to 43% of marshes bounded by seawalls. Coastal managers should consider limiting seawall construction to preserve plant diversity at the upper borders of salt marshes and prevent marsh habitat loss due to transgression associated with sea level rise.”

https://doi.org/10.2112/jcoastres-d-24a-00015.1

“Coastal development and shoreline armoring have contributed to rapid declines of salt marsh ecosystems. This study investigates multidecadal effects of bulkheads, a common shoreline armoring technique, on marsh extent in microtidal salt marshes. Aerial imagery of Bogue and Back sounds and Newport and North rivers (North Carolina, U.S.A) from 1981, 1992, 2006, and 2013 was used to measure changes in marsh extent at 45 sites with bulkheads landward of marsh and 45 control sites without bulkheads. At each site, change in marsh shoreline position (i.e. erosion or accretion) as well as landward marsh migration were measured. Rates of shoreline change and net change, the sum of shoreline change and landward migration, were compared among bulkhead and control sites. Over a 32-year period, salt marshes with landward bulkheads experienced higher mean rates of shoreline erosion than marshes without bulkheads (–0.14 ± 0.01 m/y vs. –0.09 ± 0.01 m/y). Sites without bulkheads as a barrier were able to offset some shoreline erosion through landward migration (mean migration rate = 0.05 ± 0.01 m/y). All bulkhead sites experienced net marsh loss, whereas 36% of control sites experienced net marsh gain. Net marsh loss was nearly three times higher at sites with bulkheads over the study period (–0.14 ± 0.01 m/y vs. –0.05 ± 0.01 m/y). Our results suggest that bulkheads can have a significant negative effect on marsh extent through increased erosion of the waterward edge and prevention of landward migration with sea-level rise (i.e. coastal squeeze). Land-use planning and conservation efforts protecting marsh migration corridors, combined with living shoreline strategies to reduce shoreline erosion, will be critical in protecting productive salt marsh ecosystems and the vital ecosystem services they provide.”

“Rapid population growth and coastal development are primary drivers of marine habitat degradation. Although shoreline hardening or armoring (the addition of concrete structures such as seawalls, jetties, and groins), a byproduct of development, can accelerate erosion and loss of beaches and tidal wetlands, it is a common practice globally. Here, we provide the first estimate of shoreline hardening along US Pacific, Atlantic, and Gulf of Mexico coasts and predict where future armoring may result in tidal wetland loss if coastal management practices remain unchanged. Our analysis indicates that 22 842 km of continental US shoreline -approximately 14% of the total US coastline – has been armored. We also consider how socioeconomic and physical factors relate to the pervasiveness of shoreline armoring and show that housing density, gross domestic product, storms, and wave height are positively correlated with hardening. Over 50% of South Atlantic and Gulf of Mexico coasts are fringed with tidal wetlands that could be threatened by future hardening, based on projected population growth, storm frequency, and an absence of coastal development restrictions.”

https://doi.org/10.1890/14-0716

“Coastal ecosystems provide numerous services, such as nutrient cycling, climate change amelioration, and habitat provision for commercially valuable organisms. Ecosystem functions and processes are modified by human activities locally and globally, with degradation of coastal ecosystems by development and climate change occurring at unprecedented rates. The demand for coastal defense strategies against storms and sea-level rise has increased with human population growth and development along coastlines worldwide, even while that population growth has reduced natural buffering of shorelines. Shoreline hardening, a common coastal defense strategy that includes the use of seawalls and bulkheads (vertical walls constructed of concrete, wood, vinyl, or steel), is resulting in a “coastal squeeze” on estuarine habitats. In contrast to hardening, living shorelines, which range from vegetation plantings to a combination of hard structures and plantings, can be deployed to restore or enhance multiple ecosystem services normally delivered by naturally vegetated shores. Although hundreds of living shoreline projects have been implemented in the United States alone, few studies have evaluated their effectiveness in sustaining or enhancing ecosystem services relative to naturally vegetated shorelines and hardened shorelines. We quantified the effectiveness of (1) sills with landward marsh (a type of living shoreline that combines marsh plantings with an offshore low-profile breakwater), (2) natural salt marsh shorelines (control marshes), and (3) unvegetated bulkheaded shores in providing habitat for fish and crustaceans (nekton). Sills supported higher abundances and species diversity of fishes than unvegetated habitat adjacent to bulkheads, and even control marshes. Sills also supported higher cover of filter-feeding bivalves (a food resource and refuge habitat for nekton) than bulkheads or control marshes. These ecosystem-service enhancements were detected on shores with sills three or more years after construction, but not before. Sills provide added structure and may provide better refuges from predation and greater opportunity to use available food resources for nekton than unvegetated bulkheaded shores or control marshes. Our study shows that unlike shoreline hardening, living shorelines can enhance some ecosystem services provided by marshes, such as provision of nursery habitat.”

https://doi.org/10.1016/j.ocecoaman.2014.09.016

“Acting on the perception that they perform better for longer, most property owners in the United States choose hard engineered structures, such as bulkheads or riprap revetments, to protect estuarine shorelines from erosion. Less intrusive alternatives, specifically marsh plantings with and without sills, have the potential to better sustain marsh habitat and support its ecosystem services, yet their shoreline protection capabilities during storms have not been evaluated. In this study, the performances of alternative shoreline protection approaches during Hurricane Irene (Category 1 storm) were compared by 1) classifying resultant damage to shorelines with different types of shoreline protection in three NC coastal regions after Irene; and 2) quantifying shoreline erosion at marshes with and without sills in one NC region by using repeated measurements of marsh surface elevation and marsh vegetation stem density before and after Irene. In the central Outer Banks, NC, where the strongest sustained winds blew across the longest fetch; Irene damaged 76% of bulkheads surveyed, while no damage to other shoreline protection options was detected. Across marsh sites within 25 km of its landfall, Hurricane Irene had no effect on marsh surface elevations behind sills or along marsh shorelines without sills. Although Irene temporarily reduced marsh vegetation density at sites with and without sills, vegetation recovered to pre-hurricane levels within a year. Storm responses suggest that marshes with and without sills are more durable and may protect shorelines from erosion better than the bulkheads in a Category 1 storm. This study is the first to provide data on the shoreline protection capabilities of marshes with and without sills relative to bulkheads during a substantial storm event, and to articulate a research framework to assist in the development of comprehensive policies for climate change adaptation and sustainable management of estuarine shorelines and resources in U.S. and globally.”

https://doi.org/10.7717/peerj.11815

“Nature-based shoreline protection provides a welcome class of adaptations to promote ecological resilience in the face of climate change. Along coastlines, living shorelines are among the preferred adaptation strategies to both reduce erosion and provide ecological functions. As an alternative to shoreline armoring, living shorelines are viewed favorably among coastal managers and some private property owners, but they have yet to undergo a thorough examination of how their levels of ecosystem functions compare to their closest natural counterpart: fringing marshes. Here, we provide a synthesis of results from a multi-year, large-spatial-scale study in which we compared numerous ecological metrics (including habitat provision for fish, invertebrates, diamondback terrapin, and birds, nutrient and carbon storage, and plant productivity) measured in thirteen pairs of living shorelines and natural fringing marshes throughout coastal Virginia, USA. Living shorelines were composed of marshes created by bank grading, placement of sand fill for proper elevations, and planting of S. alterniflora and S. patens, as well as placement of a stone sill seaward and parallel to the marsh to serve as a wave break. Overall, we found that living shorelines were functionally equivalent to natural marshes in nearly all measured aspects, except for a lag in soil composition due to construction of living shoreline marshes with clean, low-organic sands. These data support the prioritization of living shorelines as a coastal adaptation strategy.”

https://doi.org/10.1111/1365-2664.13371

This study evaluates the considerations designers should take into account before implementing a living shoreline project in order maximize its resilience to climate change. Before beginning a project, landowners should select project sites that allow for “landward marsh retreat with rising sea levels”. Additionally, proper planting of healthy plants that are well suited for the site is essential in order to stabilize the living shoreline sediment. Design wise, sill structures should facilitate sedimentation while also allowing for animals to continue to utilize the target marsh. This may be achieved through the implementation of windows (gaps amongst the sills). Lastly, public education and outreach is essential in order to make the public aware of the ecosystem services and benefits living shorelines may provide.

https://doi.org/10.1016/j.ecoleng.2022.106798

This study identifies barriers to the widespread implementation of living shorelines, while also suggesting solutions to overcome these barriers. One of these barriers is the lack of awareness landowners may have about the effects of hardening structures and the benefits that living shorelines have over hardening structures. This barrier may be overcome by better understanding stakeholders wants, needs, and perceptions of shoreline protection in order to provide stakeholders with a solution that best fits their needs. Another barrier includes the limited spread of technical knowledge as engineering technical guidelines regarding living shorelines are not yet widely available. Cross sector collaboration may facilitate the development and dissemination of technical knowledge. Lastly, regulation regarding living shoreline projects can sometimes hinder the development of projects. The adoption of a standard permitting process for living shoreline projects will better facilitate the development of these projects.

https://doi.org/10.1016/j.ecoleng.2023.106944

“Shorelines in Chesapeake Bay, and many other estuaries and coastal embayments, are rapidly eroding, with even more rapid loss expected in the future from drivers like urbanization and accelerated relative sea-level rise (RSLR). Past efforts to stabilize shorelines using approaches like riprap or bulkheads generally have resulted in negative ecosystem impacts, resulting in a rise of ecosystem-based approaches using natural and nature-based features (NNBF) such as living shorelines, defined here as narrow marsh fringes with adjacent sills. Living shorelines provide similar ecosystem services as natural marshes but are threatened by the same stressors of environmental change, raising questions about their long-term resiliency and effectiveness in reducing shoreline erosion. Questions also remain about their potential impacts on benthic habitats in adjacent waters. These questions are especially relevant to the Chesapeake, where relatively rapid rates of RSLR and declining sediment supplies have led to widespread marsh loss, and submersed aquatic vegetation (SAV) is a critical indicator for water clarity. This study addresses these questions through field observations in ∼10-year-old living shorelines and SAV habitats adjacent to them, along with observations at nearby reference (unaltered) shorelines. In general, shoreline erosion continued at or above historical rates at reference shorelines, but living shoreline installation builds shorelines seaward and results in net shoreline accretion. While the sand and organic content of bottom sediments in adjacent waters changed at many sites after living shoreline installation, changes were site-specific and typically in the same direction at both living and reference shorelines. These changes did not appear to impact SAV distributions, which followed regional trends likely linked to water clarity. Sediment and nutrient burial in the coastal zone, which includes both intertidal marsh and subtidal SAV habitats, was highest for living shorelines due to the addition of marsh habitat. While this study did not consider direct replacement of SAV with living shorelines, these results suggest that discouraging living shoreline installation in areas with SAV may miss an opportunity to enhance nutrient burial in the coastal zone.”

https://doi.org/10.1007/s12237-018-0439-y

“Living shorelines are a shoreline stabilization strategy encompassing a range of vegetative to structural materials and serve as an alternative approach to the use of structures like bulkheads, which are known to aggravate erosion. Living shorelines are often installed with little to no long-term monitoring for effectiveness; specifically, there is a lack of quantitative data regarding their performance as a shoreline stabilization strategy. This study sought to assess the performance of living shorelines with sills, with respect to shoreline protection, by determining shoreline change rates (SCR) using geospatial analysis. Shoreline surveys were conducted using a real-time kinematic (RTK)-GPS unit at a total of 17 living shoreline projects and nine control segments at 12 sites along the coast of North Carolina. Current shoreline position was compared to historic (pre-installation) shoreline positions obtained from aerial imagery, dating to 1993. The average SCR among northern sites before installation was − 0.45 ± 0.49 m year−1, and in southern sites, it was − 0.21 ± 0.52 m year−1. After installation, average SCR was significantly less erosive at northern and southern sites with living shorelines, 0.17 ± 0.47 and − 0.01 ± 0.51 m year−1, respectively. Of the 17 living shoreline project segments, 12 exhibited a reduction in the rate of erosion; of those 12, six were observed to be accreting. This study supports the convention that living shorelines can reduce the rate of erosion and potentially restore lost shore zone habitat.”

https://doi.org/10.1002/ieam.4447

“A growing suite of research has demonstrated that nature-based shoreline stabilization methods can increase resilience of coastal ecosystems by improving their capacity to return to predisturbance states. Previous work suggests that during hurricanes, living shorelines promote vertical accretion and experience less damage than traditional shoreline stabilization alternatives. Nevertheless, there is limited research looking at the impacts of major storm events on living shorelines and most studies have investigated a small number of sites. This study used in situ real-time kinematic (RTK)-GPS surveys to quantify the resilience (via the lateral change in shore position) of 17 living shoreline sites before and after a Category 1 hurricane event (Hurricane Florence, 2018). By doing so, this study seeks to understand the capacity of living shorelines (marsh with seaward breakwater or sill) to provide storm protection as compared to unaltered natural fringing salt marshes. After Hurricane Florence, living shorelines on average experienced significantly less lateral erosion compared to unprotected control segments (shoreline change rates of 0.015 and −0.31 m year−1, respectively). This study also explores how environmental siting variables (i.e., scarp presence, fetch, and bottom sediment) and sill design variables (i.e., sill material, width, and height) influence short- and long-term erosion. living shorelines were found to reduce erosion of fringing marsh edge among projects with a range of installation ages, structural materials, sill widths, and sill heights, and they were able to provide protection from erosion across a range of fetch, scarp, and bottom sediment conditions. Living shoreline siting and sill design may be suitable for broader environmental conditions than previously known. This study shows that living shorelines can increase resilience by reducing erosion of fringing salt marshes, promoting lateral building up of shoreline zones during short-term disturbance events, and from their long-term presence.”

https://doi.org/10.1016/j.ocecoaman.2024.107150

“Recreational fishing is an important ecosystem service supported by coastal habitats. Information on habitat utilization and preferences by anglers is largely unavailable, however. In this study, data was collected on habitat use and associated preferences from ∼1500 licensed saltwater anglers in the Middle Peninsula region of Virginia, a rural area heavily reliant on coastal natural resources. A mixed logit model was used to estimate habitat preferences from responses to a discrete choice experiment where individuals were asked to choose preferred fishing trips to different shoreline habitat types. Coastal marshes and living shorelines (nature-based coastal protection) were found to generate considerable benefits to recreational anglers due to frequent use, low visitation costs, and high willingness-to-pay. Combining habitat-specific effort and valuation estimates suggests marshes and living shorelines in this region produce US $6.42M in annual benefits associated with recreational fishing, a value which is more than three times greater than that produced by hardened shorelines. Ecosystem service values estimated in this research can be used to increase efficiency of habitat restoration and shoreline management decisions and advance accounting of coastal natural capital assets.”

https://doi.org/10.1038/s41598-025-29349-9

“Coastal protection structures that incorporate reef-building organisms, such as oysters, are increasingly used to reduce wave energy, while also enhancing ecological function. However, it remains unclear how recruitment and growth of living organisms alters wave attenuation, and ultimately coastal protection, over time. Here, we present the first field-based quantification of changes in wave transformation over a living oyster breakwater following two seasons of recruitment. Using wave gauge deployments and oyster surveys at two sites, we observed a 10–15% increase in wave attenuation after oyster recruitment. The increase in wave attenuation was associated with oysterinduced increases in surface roughness and reductions in structural porosity. A standard breakwater transmission model was adapted using fitted ecological parameters, and oyster length emerged as an informative predictor of effective structural diameter. Our results highlight how ecological dynamics shape the evolving performance of nature-based coastal defenses and demonstrate a path toward adaptive, hybrid design frameworks.”