Abstract
Abstract. Sea-level rise, saltwater intrusion, and wave erosion threaten coastal marshes, but the influence of salinity on marsh erodibility remains poorly understood. We measured the shear strength of marsh soils along a salinity and biodiversity gradient in the York River estuary in Virginia to assess the direct and indirect impacts of salinity on potential marsh erodibility. We found that soil shear strength was higher in monospecific salt marshes (5–36 kPa) than in biodiverse freshwater marshes (4–8 kPa), likely driven by differences in belowground biomass. However, we also found that shear strength at the marsh edge was controlled by sediment characteristics, rather than vegetation or salinity, suggesting that inherent relationships may be obscured in more dynamic environments. Our results indicate that York River freshwater marsh soils are weaker than salt marsh soils, and suggest that salinization of these freshwater marshes may lead to simultaneous losses in biodiversity and erodibility.
Highlights
Tidal marshes are rapidly evolving ecosystems that sit at the boundary between land and sea, and are influenced by a tight coupling between biological and geomorphic processes (Redfield, 1972)
Various wetland types exist along the York River within different salinity regimes: polyhaline salt marshes that have monocultures of Spartina alterniflora, mesohaline brackish marshes with an extensive array of halophytic grasses, and oligohaline freshwater marshes with the dominant plant species Peltandra virginica and Zizania aquatica (Perry and Atkinson, 2009)
There was a large increase in shear strength below 30 cm at the Goodwin Islands edge location (Fig. 2a), which we attribute to measurements that were within the antecedent lithology
Summary
Tidal marshes are rapidly evolving ecosystems that sit at the boundary between land and sea, and are influenced by a tight coupling between biological and geomorphic processes (Redfield, 1972). Relative sea-level rise potentially increases wave height, wave power, and edge erosion rates (Marani et al, 2011; Mariotti and Fagherazzi, 2010; McLoughlin et al, 2015) and leads to nonlinear changes in vegetation that could alter the strength of eroding soils (Feagin et al, 2009; Kirwan and Guntenspergen, 2012; Stagg et al, 2017; Wilson et al, 2012). Numerical models of marshes have shown that erosion rates and shoreline morphology depend on interactions between shear stress from waves and the shear strength of marsh soils (Bernik et al, 2018; Leonardi and Fagherazzi, 2014; Marani et al, 2011; Mariotti and Fagherazzi, 2010)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
