Vegetation Cover and Elevation in Long-Term Experimental Nutrient-Enrichment Plots in Great Sippewissett Salt Marsh, Cape Cod, Massachusetts: Implications for Eutrophication and Sea Level rise

2012 ◽  
Vol 35 (2) ◽  
pp. 445-458 ◽  
Author(s):  
Liza Fox ◽  
Ivan Valiela ◽  
Erin L. Kinney
Author(s):  
Dirk Granse ◽  
Sigrid Suchrow ◽  
Kai Jensen

AbstractThe cordgrass Spartina anglica C.E. Hubbard (Poaceae) is an invasive transformer in many salt marsh ecosystems worldwide. Relatively little is known about the capacity of Spartina to accelerate salt marsh succession and to protect salt marshes against sea level rise. We analyzed long-term changes in vegetation and elevation in mainland salt marshes of the European Wadden Sea in Schleswig-Holstein, Germany, to estimate the impact of non-native Spartina on the geomorphological resistance of salt marshes to sea level rise and on changes in species diversity. From 1989 to 2019, the Spartina-zone shifted and expanded upwards to elevations of the high marsh zone and Spartina increased in frequency in several salt marsh vegetation communities. At sites where Spartina dominated the vegetation already three decades ago, elevation and species diversity increased with a higher rate compared to sites lacking Spartina. The median change rates reached for elevation MHT +8.6 versus +1.5 mm per year, for species richness +3 versus $$\pm$$ ± 0 species per three decades, and for evenness +0.04 versus −0.08 per three decades, regarding plots with versus without former Spartina dominance, respectively. Invasion of salt marshes by Spartina and its continued, long-term presence were associated with increased elevation and species diversity in the face of sea level rise.


2020 ◽  
Vol 65 (9) ◽  
pp. 2142-2157 ◽  
Author(s):  
Amy K. Langston ◽  
Orencio Durán Vinent ◽  
Ellen R. Herbert ◽  
Matthew L. Kirwan
Keyword(s):  

2021 ◽  
Author(s):  
Natascia Pannozzo ◽  
Nicoletta Leonardi ◽  
Iacopo Carnacina ◽  
Rachel Smedley

<p>Salt marshes are widely recognised as ecosystems with high economic and environmental value. However, it is still unclear how salt marshes will respond to the combined impact of future sea-level rise and possible increases in storm intensity (Schuerch et al. 2013). This study investigates marsh resilience under the combined impact of various storm surge and sea-level scenarios by using a sediment budget approach. The current paradigm is that a positive sediment budget supports the accretion of salt marshes and, therefore, its survival, while a negative sediment budget causes marsh degradation (Ganju et al. 2015). The Ribble Estuary, North-West England, was used as test case, and the hydrodynamic model Delft3D was used to simulate the response of the salt marsh system to the above scenarios. We conclude that the resilience of salt marshes and estuarine systems is enhanced under the effect of storm surges, as they promote flood dominance and trigger a net import of sediment.  Conversely, sea-level rise threatens marsh stability, by promoting ebb dominance and triggering a net export of sediment. Ultimately, when storm surge and sea-level scenarios are combined, results show that storms with the highest intensities have the potential to counteract the negative impact of sea-level rise by masking its effects on the sediment budget.</p><p><strong>Acknowledgements</strong></p><p>We acknowledge the support of the School of Environmental Sciences, University of Liverpool.</p><p><strong>References</strong></p><p>Ganju, N.K., Kirwan, M.L., Dickhudt, P.J., Guntenspergen, G.R., Cahoon, D.R. and Kroeger, K.D. 2015. “Sediment transport-based metrics of wetland stability”. Geophysical Research Letters, 42(19), 7992-8000.</p><p>Schuerch, M., Vafeidis, A., Slawig, T. and Temmerman, S. 2013. “Modeling the influence of changing storm patterns on the ability of a salt marsh to keep pace with sea level rise”. Journal of Geophysical Research-Earth Surface, 118(1),<strong> </strong>84-96.</p>


2020 ◽  
Vol 191 ◽  
pp. 103212 ◽  
Author(s):  
Bing Yuan ◽  
Jian Sun ◽  
Binliang Lin ◽  
Fanyi Zhang

Author(s):  
Alice F. Besterman ◽  
Rachel W. Jakuba ◽  
Wenley Ferguson ◽  
Diana Brennan ◽  
Joseph E. Costa ◽  
...  

AbstractA prominent form of salt marsh loss is interior conversion to open water, driven by sea level rise in interaction with human activity and other stressors. Persistent inundation drowns vegetation and contributes to open water conversion in salt marsh interiors. Runnels are shallow channels originally developed in Australia to control mosquitoes by draining standing water, but recently used to restore marsh vegetation in the USA. Documentation on runnel efficacy is not widely available; yet over the past 10 years dozens of coastal adaptation projects in the northeastern USA have incorporated runnels. To better understand the efficacy of runnels used for restoration, we organized a workshop of 70 experts and stakeholders in coastal resource management. Through the workshop we developed a collective understanding of how runnels might be used to slow or reverse open water conversion, and identified unresolved questions. In this paper we present a synthesis of workshop discussions and results from a promising case study in which vegetation was restored at a degraded marsh within a few years of runnel construction. Despite case study outcomes, key questions remain on long-term runnel efficacy in marshes differing in elevation, tidal range, and management history. Runnel construction is unlikely to improve long-term marsh resilience alone, as it cannot address underlying causes of open water conversion. As a part of holistic climate planning that includes other management interventions, runnels may “buy time” for salt marshes to respond to management action, or adapt to sea level rise.


2021 ◽  
Author(s):  
Bing Yuan ◽  
Jian Sun ◽  
Binliang Lin ◽  
Fanyi Zhang

<p>Globally the riverine sediment supply to estuaries is decreasing and the mean sea level is rising, while the effects of these changes on the long-term estuarine morphodynamics have not been fully investigated. An idealized numerical model was used to explore the long-term morphodynamics of a large estuary subject to these changes. In the model, a funnel-shaped channel with fixed banks, constant riverine water and sediment fluxes, a single grain size and a semi-diurnal tide were used. A range of values of changes in the sediment supply (50-90% reduction) and sea level (1-5~mm/yr increase) were considered. Starting from an equilibrium state for an initial sediment supply, the estuary shifts to a new equilibrium for the considered changes on a timescale of millennia. Half of the bed level change occurs within several hundreds of years. A larger decrease in the sediment supply leads to a stronger bed erosion, while the corresponding adjustment time has minor changes in its range for the considered settings. When combined with sea level rise, the erosion is weakened and the adjustment time is shortened. The equilibrium state under sea level rise is characterized by a bed level keeping pace with the sea level and a significant amount of sediment being trapped in the estuary. Additional numerical experiments that use more realistic geometry and forcing of the Yangtze Estuary show that overall erosion of the estuary is expected for centuries.</p>


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