Living Shorelines: Coastal Resilience with a Blue Carbon Benefit

Abstract

Living shorelines are a type of estuarine shoreline erosion control that incorporates native vegetation and preserves native habitats. Because they provide the ecosystem services associated with natural coastal wetlands while also increasing shoreline resilience, living shorelines are part of the natural and hybrid infrastructure approach to coastal resiliency. Marshes created as living shorelines are typically narrow (< 30 m) fringing marshes with sandy substrates that are well flushed by tides. These characteristics distinguish living shorelines from the larger meadow marshes in which most of the current knowledge about created marshes was developed. The value of living shorelines for providing both erosion control and habitat for estuarine organisms has been documented but their capacity for carbon sequestration has not. We measured carbon sequestration rates in living shorelines and sandy transplanted Spartina alterniflora marshes in the Newport River Estuary, North Carolina. The marshes sampled here range in age from 12 to 38 years and represent a continuum of soil development. Carbon sequestration rates ranged from 58 to 283 g C m-2 yr-1 and decreased with marsh age. The pattern of lower sequestration rates in older marshes is hypothesized to be the result of a relative enrichment of labile organic matter in younger sites and illustrates the importance of choosing mature marshes for determination of long-term carbon sequestration potential. The data presented here are within the range of published carbon sequestration rates for S. alterniflora marshes and suggest that wide-scale use of the living shoreline approach to shoreline management may come with a substantial carbon benefit.

Living shorelines enhanced the resilience of saltmarshes to Hurricane Matthew (2016)

“…, Davis et al. , Gittman et al. ), but successful promotion of living shorelines as an alternative to hardened shorelines will likely rely on demonstrating their effectiveness and durability first, and then promoting their ecological advantages as co‐benefits (Scyphers et al.…”

“…Nature-based solutions, such as living shorelines (also known as hybrid infrastructure), combine some of the best characteristics of natural and engineered shorelines and they have the potential to improve coastal resilience while restoring critical ecosystems or maintaining ecosystems in areas where they might otherwise be lost (e.g., saltmarshes and oyster reefs; Sutton-Grier et al 2015). Living shorelines have been shown to enhance services like wave amelioration, carbon sequestration, and nursery provision for juvenile fish (Scyphers et al 2011, Davis et al 2015, Gittman et al 2016a), but successful promotion of living shorelines as an alternative to hardened shorelines will likely rely on demonstrating their effectiveness and durability first, and then promoting their ecological advantages as co-benefits (Scyphers et al 2015, Smith et al 2017). An impediment to this promotion is that data on living shoreline resilience to hurricane impacts (as directly compared to traditional hardened shorelines) are extremely limited (Sutton-Grier et al 2018, but see Gittman et al 2014.…”

From grey to green: Efficacy of eco‐engineering solutions for nature‐based coastal defence

“…Equally, an evaluation of additional ecosystem services potentially provided by artificial structures is largely unknown, beyond patterns of biodiversity between artificial structures and natural shorelines(Bulleri & Chapman, 2010).Artificial structures introduce a novel substratum into the marine environment, which can be colonized by organisms. data are not availableDavis, Currin, O'brien, Raffenburg, and Davis (2015),La Peyre, Gossman, and Nyman (2007),Sparks, Cebrian, Tobias, and May (2015) with greater numbers of nonindigenous species(Dafforn et al, 2009).…”

The Role of the Upper Tidal Estuary in Wetland Blue Carbon Storage and Flux

“…However, these rates were determined using C‐14 techniques, which average over many centuries to millennia and may inherently underestimate C B at decadal time scales from integration of deeper depths and processes (Breithaupt et al, ; Breithaupt et al, ); the majority of C B assessments make use of shorter‐term approaches such as Pb‐210 or space‐for‐time substitutions. From these, soil C B was 18–1,713 g C · m −2 · year −1 in natural saltmarshes (Chmura et al, ), 58–283 g C · m −2 year −1 in constructed Atlantic coastal Spartina alterniflora marshes (Davis et al, ), 45–190 g C · m −2 · year −1 for sea grasses (Mcleod et al, ), 163–226 g C · m −2 · year −1 in natural mangroves globally (Breithaupt et al, ; Mcleod et al, ), 218 g C · m −2 · year −1 for created mangroves in southern Florida (Osland et al, ), and 80–435 g C · m −2 · year −1 in tidal freshwater marshes in Georgia and South Carolina (Drexler et al, ; Loomis & Craft, ). Pb‐210 estimates were 21–65 g C · m −2 · year −1 among our Waccamaw sites (Noe et al, ), compared with 7–51 g C · m −2 · year −1 for C‐14, suggesting that C‐14 techniques are slightly misestimating century‐scale C burial (though not in a consistent direction) but are potentially representative enough for our purposes.…”