Salt marshes adjustment to anthropogenic pressures and sea-level rise

2021 ◽  
Author(s):  
A. Rita Carrasco ◽  
Katerina Kombiadou ◽  
Miguel Amado
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Salt Marshes ◽  
Anthropogenic Pressures ◽  
The Past ◽  
Ria Formosa ◽  
Sediment Loads ◽  
Human Interventions ◽  
South Portugal ◽  
And Sea Level

<p>It is predictable that salt marshes in regions, where sediment loads are high, should be stable against a broader range of relative sea level scenarios than those in sediment-poor systems. Despite extensive theoretical and laboratory studies, additional syntheses of marsh ‘persistence’ indicators under human interventions and accelerated sea-level rise rates are still needed. This study investigates the recent lateral changes occurring in lagoon-type marshes of the Ria Formosa lagoon (south Portugal) in the presence of human interventions and sea-level rise, to identify the major drivers for past marsh evolution and to estimate potential future trends. The conducted analysis assessed the past geomorphological adjustment based on imagery analysis and assessed its potential future adjustment to sea-level rise (~100 years) based on modelled land cover changes (by employing the SLAMM model within two sea-level rise scenarios).</p><p>Salt marshes in the Ria Formosa showed slow lateral growth rates over the last 70 years (<1 mm∙yr<sup>-1</sup>), with localized erosion along the main navigable channels associated with dredging activities. Higher change rates were noted near the inlets, with stronger progradation near the natural inlets of the system, fed by sediment influx pulses. Any potential influence of sea-level increase to an intensification of marsh-edge erosion in the past, could not be distinguished from human-induced pressures in the area. No significant sediment was exchanged between the salt marshes and tidal flats, and no self-organization pattern between them was observed in past. The related analysis showed that landcover changes in the salt marsh areas are likely to be more prominent in the future. The obtained results showed evidence of non-linearity in marsh response to high sea-level rise rates, which could indicate to the presence of critical thresholds and potential negative feedbacks within the system, with significant implications to marsh resilience.</p>

scholarly journals Suspended sediment projections in Apalachicola Bay in response to altered river flow and sediment loads under climate change and sea level rise

2016 ◽  
Vol 4 (10) ◽  
pp. 428-439 ◽  
Author(s):  
Wenrui Huang ◽  
Scott C. Hagen ◽  
Dingbao Wang ◽  
Paige A. Hovenga ◽  
Fei Teng ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
Suspended Sediment ◽  
Sea Level ◽  
River Flow ◽  
Apalachicola Bay ◽  
Sediment Loads ◽  
And Sea Level

scholarly journals Differential Effects of Increasing Salinity on Germination and Seedling Growth of Native and Exotic Invasive Cordgrasses

Plants ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 372 ◽  
Author(s):  
Infante-Izquierdo ◽  
Castillo ◽  
Grewell ◽  
Nieva ◽  
Muñoz-Rodríguez
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Fresh Water ◽  
Seedling Growth ◽  
Salt Marshes ◽  
Germination Percentage ◽  
Tidal Elevation ◽  
Exotic Invasive ◽  
Specialist Species ◽  
And Sea Level

Soil salinity is a key environmental factor influencing germination and seedling establishment in salt marshes. Global warming and sea level rise are changing estuarine salinity, and may modify the colonization ability of halophytes. We evaluated the effects of increasing salinity on germination and seedling growth of native Spartina maritima and invasive S. densiflora from wetlands of the Odiel-Tinto Estuary. Responses were assessed following salinity exposure from fresh water to hypersaline conditions and germination recovery of non-germinated seeds when transferred to fresh water. The germination of both species was inhibited and delayed at high salinities, while pre-exposure to salinity accelerated the speed of germination in recovery assays compared to non-pre-exposed seeds. S. densiflora was more tolerant of salinity at germination than S. maritima. S. densiflora was able to germinate at hypersalinity and its germination percentage decreased at higher salinities compared to S. maritima. In contrast, S. maritima showed higher salinity tolerance in relation to seedling growth. Contrasting results were observed with differences in the tidal elevation of populations. Our results suggest S. maritima is a specialist species with respect to salinity, while S. densiflora is a generalist capable of germination of growth under suboptimal conditions. Invasive S. densiflora has greater capacity than native S. maritima to establish from seed with continued climate change and sea level rise.

Beach nourishment versus sea level rise on Florida’s coasts

Shore & Beach ◽  
2020 ◽  
pp. 3-13
Author(s):  
James Houston
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
East Coast ◽  
Beach Nourishment ◽  
Shoreline Change ◽  
Intergovernmental Panel ◽  
Shoreline Changes ◽  
The Past ◽  
Equilibrium Profile ◽  
And Sea Level

Beach nourishment and sea level rise will dominate future shoreline changes on Florida’s 665 miles of sandy coast. Shoreline changes from 2020-2100 are projected along this entire coast using equilibrium profile theory that accurately predicted shoreline changes on Florida’s east coast from 1970-2017 (Houston 2019). Projections for 2020- 2100 are made assuming past rates of beach nourishment for the 30-yr period from 1988-2017 will continue and sea level will rise according to recent projections of the Intergovernmental Panel on Climate Change (IPCC) that include the latest knowledge on ice melting in Antarctica (IPCC 2019). Using the beach nourishment and sea level rise data, equilibrium profile theory is then used to predict shoreline change from 2020-2100 for each IPCC sea level rise projection. Beach nourishment is shown to produce shoreline advance seaward on average for all IPCC scenarios for both the entire Florida coast and east coast and for all scenarios except the upper confidence level of the worst scenario for the southwest and Panhandle coasts. Some of the 30 counties on these coasts will require a greater rate of nourishment than in the past to offset sea level rise for some or all of the scenarios, whereas some will offset sea level rise for all scenarios with lower nourishment rates than in the past. The annual beach nourishment volume for which a county has a shortfall or surplus in offsetting sea level rise for each IPCC scenario can be calculated with the information provided and examples are presented. The approach can be used on coasts outside Florida if beach nourishment and sea level rise are expected to dominate future shoreline change.

Salt marsh resilience to sea-level rise and increased storm intensity

2021 ◽  
Author(s):  
Natascia Pannozzo ◽  
Nicoletta Leonardi ◽  
Iacopo Carnacina ◽  
Rachel Smedley
Keyword(s):  
Salt Marsh ◽  
Sea Level Rise ◽  
Sea Level ◽  
Storm Surge ◽  
Salt Marshes ◽  
Sediment Budget ◽  
Geophysical Research ◽  
Storm Intensity ◽  
Combined Impact ◽  
And Sea Level

<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>

Vegetation death and rapid loss of surface elevation in two contrasting Mississippi delta salt marshes: The role of sedimentation, autocompaction and sea-level rise

2011 ◽  
Vol 37 (2) ◽  
pp. 229-240 ◽  
Author(s):  
John W. Day ◽  
G. Paul Kemp ◽  
Denise J. Reed ◽  
Donald R. Cahoon ◽  
Roelof M. Boumans ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Salt Marshes ◽  
Mississippi Delta ◽  
Surface Elevation ◽  
Rapid Loss ◽  
And Sea Level
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