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Publications (116)
Tidal marshes in the Chesapeake Bay are vulnerable to the accelerating rate of sea-level rise (SLR) and subsidence. Restored and created marshes face the same risks as natural marshes, and their resilience to SLR may depend upon appropriate design and implementation. Here, the Coastal Wetland Equilibrium Model (CWEM) was used to assess the resilien...
Marsh accretion models predict the resiliency of coastal wetlands and their ability to store carbon in the face of accelerating sea level rise. Most existing marsh accretion models are derived from two parent models: the Marsh Equilibrium Model, which formalizes the biophysical relationships between sea level rise, dominant macrophyte growth, and e...
Tidal marshes provide numerous ecosystem services, but are threatened by recent increases in global sea level rise (SLR). Marsh restoration and creation are important strategies for mitigating marsh loss, restoring ecosystem services, increasing coastal community resilience, and providing much needed habitat for threatened species. Dredged material...
Quantifying carbon fluxes into and out of coastal soils is critical to meeting greenhouse gas reduction and coastal resiliency goals. Numerous ‘blue carbon’ studies have generated, or benefitted from, synthetic datasets. However, the community those efforts inspired does not have a centralized, standardized database of disaggregated data used to es...
Rice cultivation is popular in low-lying areas such as deltas, but climate change threatens the viability of the crop. In recent decades, the resilience of deltas to sea level rise (SLR) has been influenced by the reduction of sediment load from rivers due to the construction of dams, disrupting natural deposition in deltaic plains. Sediment and or...
The long‐term stability of coastal wetlands is determined by interactions among sea level, plant primary production, sediment supply, and wetland vertical accretion. Human activities in watersheds have significantly altered sediment delivery from the landscape to the coastal ocean, with declines along much of the U.S. East Coast. Tidal wetlands in...
Quantitative, broadly applicable metrics of resilience are needed to effectively manage tidal marshes into the future. Here we quantified three metrics of temporal marsh resilience: time to marsh drowning, time to marsh tipping point, and the probability of a regime shift, defined as the conditional probability of a transition to an alternative sup...
Around the world, wetland vulnerability to sea‐level rise (SLR) depends on different factors including tidal regimes, topography, creeks and estuary geometry, sediment availability, vegetation type, etc. The Plum Island estuary (PIE) is a mesotidal wetland system on the east coast of the United States. This research applied a newly updated Hydro‐ME...
Coastal ecosystems play a disproportionately large role in society, and climate change is altering their ecological structure and function, as well as their highly valued goods and services. In the present article, we review the results from decade-scale research on coastal ecosystems shaped by foundation species (e.g., coral reefs, kelp forests, c...
Sea-level rise (SLR) and obstructions to sediment delivery pose challenges to the persistence of estuarine habitats and the ecosystem services they provide. Restoration actions and sediment management strategies may help mitigate such challenges by encouraging the vertical accretion of sediment in and horizontal migration of tidal forests and marsh...
This review evaluates the importance of plants and associated biological processes in determining the vulnerability of coastal wetlands to sea-level rise. Coastal wetlands occur across a broad sedimentary continuum from minerogenic to biogenic, providing an opportunity to examine the relative importance of biological processes in wetland resilience...
The analysis presented here was motivated by an objective of describing the interactions between the physical and biological processes governing the responses of tidal wetlands to rising sea level and the ensuing equilibrium elevation. We define equilibrium here as meaning that the elevation of the vegetated surface relative to mean sea level (MSL)...
Plain Language Summary
The rapid, climate‐driven acceleration of global sea level threatens salt marshes and mangroves along low‐elevation shorelines. These coastal wetlands provide protection from storms along with other ecosystem services to vulnerable coastal communities, including several megacities. The question of how coastal wetlands will co...
The coupling of geomorphological and ecological processes is critical for the maintenance or disappearance of salt marshes. Emergent macrophytes dampen wave- and tide-generated shear stresses promoting sediment deposition and marsh formation. The complex interactions among marsh primary productivity, sea level, and sedimentation determine the equil...
A forecast of nuisance flooding of Charleston peninsula is presented, based on an analysis of tide records from Charleston Harbor, SC. The forecast was based on past trends in local sea level and tidal harmonics, including the 18.6-yr lunar nodal and annual cycles. The data document an exponential rise in mean sea level. Extrapolating to year 2060...
The responses of marsh elevation in four National Parks affected by Hurricane Sandy were examined using empirical data from surface elevation tables (SET) and modeling. The parks examined were Fire Island National Seashore and Gateway National Recreational Area in New York; Cape Cod National Seashore, Massachusetts; and Assateague Island National S...
Schuerch et al. (2018) [1] deserve credit for compiling a wide range of disparate, global datasets that will be instrumental in predicting future coastal wetland change. However, we challenge their projections that range from modest losses to substantial gains worldwide by the end of this century. Their modeling does not adequately capture the role...
The margins of the sea are encroaching landward throughout most of the world. This is happening not simply because of sea level rise but also because the solid material- sand, mud, gravel-composing the shore and the subaerial and subaqueous lands immediately adjacent to it is being displaced. In addition to physical erosion by wave, thermal erosion...
Coastal climate adaptation strategies are needed to build salt marsh resiliency and maintain critical ecosystem services in response to impacts caused by climate change. Although resident microbial communities perform crucial biogeochemical cycles for salt marsh functioning, their response to restoration practices is still understudied. One promisi...
Summary of above and belowground plant biomass, carbon dioxide flux, and chemical composition of pore water at 21 cm depth.
(PDF)
Description of the samples and alpha-diversity measures.
(PDF)
Summary of permutational analysis of variance (PERMANOVA with 999 permutations) testing the difference in bacterial community structure according to sediment source (on all samples together) and elevation and depth (separately for natural and sand-amended sediments).
(PDF)
Natural and sand-amended mesocosms with inserts and lysimeters, and elevation levels labelled.
(TIF)
Phylum-level taxonomic distribution of all sequences retrieved during this study (singleton-free, n = 68,123).
"Others" comprises phyla accounting less than 1%.
(PNG)
Coastal wetlands store carbon dioxide (CO2) and emit CO2 and methane (CH4) making them an important part of greenhouse gas (GHG) inventorying. In the contiguous United States (CONUS), a coastal wetland inventory was recently calculated by combining maps of wetland type and change with soil, biomass, and CH4 flux data from a literature review. We as...
Two distinct microtidal estuarine systems were assessed to advance the understanding of the coastal dynamics of sea level rise in salt marshes. A coupled hydrodynamic-marsh model (Hydro-MEM) was applied to both a marine-dominated (Grand Bay, Mississippi) and a mixed fluvial/marine (Weeks Bay, Alabama) system to compute marsh productivity, marsh mig...
A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.
Spartina alterniflora, marsh grass, is a vegetative apomicticly-reproducing halophyte native to marshes along the east coast of the United States and invasive across the world. S. alterniflora provides many ecosystem services including, but not limited to, water filtration, habitats for invertebrates, and sediment retention. Widespread diebacks of...
Methylation values from North Inlet S. alterniflora samples.
(XLSX)
Tidal wetlands produce long-term soil organic carbon (C) stocks. Thus for carbon accounting purposes, we need accurate and precise information on the magnitude and spatial distribution of those stocks. We assembled and analyzed an unprecedented soil core dataset, and tested three strategies for mapping carbon stocks: applying the average value from...
With sea level rise accelerating and sediment inputs to the coast declining worldwide, there is concern that tidal wetlands will drown. To better understand this concern, sources of sediment contributing to marsh elevation gain were computed for Plum Island Sound estuary, MA, USA. We quantified input of sediment from rivers and erosion of marsh edg...
The sediments of coastal wetlands contain large stores of carbon which are vulnerable to oxidation once disturbed, resulting in high levels of CO2 emissions that may be avoided if coastal ecosystems are conserved or restored. We used a simple model to estimate CO2 emissions from mangrove forests, seagrass beds, and tidal marshes based on known deco...
The 18.6-year lunar-nodal cycle drives changes in tidal amplitude globally, affecting coastal habitat formation, species and communities inhabiting rocky shores, and salt marsh vegetation. However, the cycle's influence on salt marsh fauna lacked sufficient long-term data for testing its effect. We circumvented this problem by using salt marsh mosq...
Coastal regions are vulnerable to flood risk due to climate change, sea level rise, and wetland losses. The Northern Gulf of Mexico (NGOM) is a region in which extreme events are projected to be more intense under climate change and sea level rise scenarios [Wang et al., 2013; Bilskie et al., 2014]. Considering increased frequency and intensity of...
Studies show that coastal estuaries and marsh systems are at the risk of losing their productivity under increasing rates of sea level rise (SLR). A rise in relative sea level may increase flooding across the marsh surface and thereby increase the hydroperiod and re-establish the elevation of the marsh relative to the new mean sea level (Morris, 20...
Coastal wetlands are likely to lose productivity under increasing rates of sea-level rise. This study assessed a fluvial estuarine salt marsh system using the Hydro-MEM under four sea-level rise scenarios. The Hydro-MEM was developed to apply the dynamics of sea-level rise as well as capture the effects associated with the rate of sea-level rise in...
The Long-Term Ecological Research (LTER) Program is, in a sense, an experiment to transform the nature of science, and represents one of the most effective mechanisms for catalyzing comprehensive site-based research that is collaborative, multidisciplinary, and long-term in nature. The scientific contributions of the Program are prodigious, but the...
Supporting Information S1
A mixing model derived from first principles describes the bulk density (BD) of intertidal wetland sediments as a function of loss on ignition (LOI). The model assumes the bulk volume of sediment equates to the sum of self-packing volumes of organic and mineral components or BD = 1/[LOI/k1 + (1-LOI)/k2], where k1 and k2 are the self-packing densiti...
The Grand Bay estuary, situated along the border of Alabama and Mississippi, is a marine dominant estuary. Juncus roemerianus and Spartina alterniflora cover approximately 49% of the estuary (
Eleuterius and Criss, 1991); However, this marsh system is prone to erosion more than other marsh systems in the state (Mississippi Department of Marine Reso...
Decaying mats of Ulva can be washed into salt marshes by the tides as large wrack deposits, especially in eutrophic estuaries, where they can negatively impact marsh vegetation. Using field and laboratory experiments, we examined the effects of decomposing Ulva on Spartina alterniflora growth, soil biogeochemistry and nitrogen dynamics. High levels...
Many global change drivers chronically alter resource availability in terrestrial ecosystems. Such resource alterations are known to affect aboveground net primary production (ANPP) in the short term; however, it is unknown if patterns of response change through time. We examined the magnitude, direction, and pattern of ANPP responses to a wide ran...
Soil organic matter, roots, rhizomes, and carbon dioxide (CO2) emission rates were examined in minerogenic marshes of the North Inlet Estuary, a system dominated by sediment depositional processes and typical of the Southeast USA. Three marsh sites were sampled: a long-term nutrient enrichment experiment at Goat Island; the high marsh, low marsh, a...
Coastal wetlands are at the risk of losing their productivity under increasing rates of sea level rise (SLR). Studies show that under extreme enough stressors, salt marshes will not have time to establish an equilibrium and may migrate landward (Donnelly and Bertness 2001; Warren and Niering 1993) or become open water.
In order to investigate salt...
40 3 general ConsIderatIons Once the details of the project and sampling requirements have been determined, field sampling of the ecosystem carbon pools can begin. Field techniques for measuring the aboveground and belowground living biomass in different ecosystems vary between mangroves, tidal salt marshes, and seagrass meadows and are described i...
An assessment of the sea level rise (SLR) impact on coastal salt marsh biomass productivity for a marine dominated estuary in Grand Bay, MS is presented. The projection of salt marsh productivity is conducted using an integrated hydro-marsh model, which is comprised of a hydrodynamic and a parametric marsh model. The results include the dynamic eff...
An assessment of the effects of sea level rise on salt marsh grass biomass productivity for a fluvial dominated estuary in Apalachicola, FL and a marine dominated estuary in Grand Bay, MS is presented. The Apalachicola River, located in the Florida panhandle, is formed by the confluence of the Chattahoochee and Flint Rivers, and has the largest dis...
Tidal marshes maintain elevation relative to sea level through accumulation of mineral and organic matter, yet this dynamic accumulation feedback mechanism has not been modeled widely in the context of accelerated sea-level rise. Uncertainties exist about tidal marsh resiliency to accelerated sea-level rise, reduced sediment supply, reduced plant p...
In this study, an integrated model to assess the effect of sea level rise on salt marsh systems is presented. It is based on a coupled two-dimensional hydrodynamic model and a parametric marsh model. The model shows marsh productivity as a function of mean high water (MHW), mean low water (MLW), and the elevation of the marsh platform. MHW and MLW...
The Marsh Equilibrium Model (MEM) was calibrated to a marsh in Apalachicola Bay, Florida, and used to forecast the effect of sea-level rise on carbon sequestration. At the current rate of sea-level rise (0.24 cm/yr) this wetland sequesters between 2-2.5 tons C ha^-1 yr^-1. The sediment can be characterized as a peat with sediment organic matter (SO...
Feedbacks between flooding and plant growth that help to stabilize marshes against rising sea level are being investigated in estuaries at Plum Island, Massachusetts, and North Inlet, South Carolina. Net annual primary production of the marsh grass Spartina alterniflora has been quite variable through the years, and correlates positively with sea l...
The impact of sea-level rise on salt marsh sustainability is examined for the lower St. Johns River and associated salt marsh (Spartina alterniflora) system. A two-dimensional hydrodynamic model, forced by tides and sea-level rise, is coupled with a zero-dimensional marsh model to estimate the level of biomass productivity of S. alterniflora across...
In situ persistence of coastal marsh habitat as sea level rises depends on whether macrophytes induce compensatory accretion of the marsh surface. Experimental planters in two North Carolina marshes served to expose two dominant macrophyte species to six different elevations spanning 0.75 m (inundation durations 0.4–99 %). Spartina alterniflora and...
Data from salt marshes in the U.S. Southeast show that long-term variations in mean water level (MWL) correlate strongly with
salt marsh productivity and porewater salinity. Here we used numerical models of tidally-driven groundwater flow to assess
the effect of variations in tidal amplitude and MWL on porewater exchange between salt marshes and ti...
This paper describes model (Marsh Equilibrium Model) simulations of the unit area carbon sequestration potential of contemporary coastal wetlands before and following a projected 1 m rise in sea level over the next century. Unit rates ranged typically from 0.2 to 0.3 Mg C ha−1 year−1 depending primarily on the rate of sea-level rise, tidal amplitud...
Computed tomography (CT) imaging has been used to describe and quantify subtidal, benthic animals such as polychaetes, amphipods, and shrimp. Here, for the first time, CT imaging is used to quantify wet mass of coarse roots, rhizomes, and peat in cores collected from organic-rich (Jamaica Bay, New York) and mineral (North Inlet, South Carolina) Spa...
From the fecundity and temperature-dependent development times of the life stages of Microarthridion littorale and long-term measurements of the densities of copepodites and female and male adults in subtidal sediments at North Inlet, South Carolina, we calculated maximum and minimum productivity limits of this meiobenthic copepod. The potential pr...
Climate impacts on coastal and estuarine systems take many forms and are dependent on the local conditions, including those
set by humans. We use a biocomplexity framework to provide a perspective of the consequences of climate change for coastal
wetland ecogeomorphology. We concentrate on three dimensions of climate change affects on ecogeomorphol...
An integrated monitoring system is proposed for India that will monitor terrestrial, coastal, and oceanic environments.
Vertical elevation relative to mean sea level is a critical variable for the productivity and stability of salt marshes. This research classified a high spatial resolution Airborne Data Acquisition and Registration (ADAR) digital camera image of a salt marsh landscape at North Inlet, South Carolina, USA using an artificial neural network. The remot...
Acid phosphatase activity (APA) was measured in intertidal marsh sediments located along the Cooper River estuary, South Carolina, at North Inlet, SC, and in a marsh on the Rowley River, MA. We found that APA increased from 4.3 +/- 2.3 to 29.3 +/- 18.8 pmol p-nitrophenol released g(-1) h(-1) with decreasing sediment salinity from 22 g l(-1) to 0.1...
Estuaries integrate atmospheric, watershed, oceanic, and human influences over space and time. Therefore, spatial and temporal patterns in estuarine water-column properties are useful as metrics to evaluate external factors related to internal processes. The National Estuarine Research Reserve monitoring program, including the North Inlet–Winyah Ba...
Dimethylsulphoniopropionate (DMSP) is produced in high concentrations in many marine algae, but in higher plants only in a
few salt marsh grasses of the genus Spartina, in sugar canes (Saccharum spp.), and in the Pacific strand plant Wollastonia biflora (L.) DC. The high concentrations found in higher plants (up to 250 μmol g−1 dry weight) suggest...
Sediment transport by rainfall-runoff processes is well documented for terrestrial land scapes but few studies have focused on rainfall-runoff effects in intertidal areas. Here we present geochemical analyses performed on sediment samples collected during low tide irrigation experiments, and tidal channel turbidity measurements taken during natural...
Phosphatase activity was measured in sediments from tidal freshwater habitats adjacent to the Cooper River in South Carolina
representing different stages of ecological succession. It was found that sediment (0–5 cm) acid phosphatase activity, alkaline
phosphatase activity and phosphodiesterase activity increased with increasing successional stage...
Phytoplankton community pigment composition and water quality were measured seasonally along salinity gradients in two minimally urbanized salt marsh estuaries in South Carolina in order to examine their spatial and temporal distributions. The North Inlet estuary has a relatively small watershed with minimal fresh water input, while the Ashepoo, Co...
1 Canopy-level CO2 exchange and biomass were measured monthly for 9 consecutive months during 1990 on grazed and non-grazed portions of a Danish salt marsh dominated by Spartina anglica. The empirical measurements were used to calibrate a model of canopy photosynthesis and soil respiration that was subsequently integrated to provide estimates of an...
Primary production in coastal wetlands is conventionally thought to be limited by nitrogen. Although the plant community in
a pristine salt marsh was found to be limited primarily by nitrogen availability, the bacterial community in the soil was
limited by phosphorus. Hence, in coastal wetlands, and possibly in many ecosystems, individual trophic g...
The intertidal salt marshes of the Atlantic and Gulf coasts of the United States are dominated by the perennial grass, Spartina alterniflora Loisel. The ecology of salt marshes in which this species dominates has been extensively investigated because of the documented
biogeochemical functions that these ecosystems perform and the resulting societal...
Loading of bioavailable phosphorus, traditionally measured as soluble reactive phosphorus (SRP), contributes to the eutrophication of aquatic ecosystems. However, polyphosphates are also bioavailable but escape detection by the standard method used for measuring SRP. 31p nuclear magnetic resonance spectrometric analysis of sediment extracts and enz...
We use 228Ra and 226Ra to determine the mass
balance of dissolved inorganic nitrogen (DIN) and dissolved reactive
phosphorus (DRP) in the North Inlet salt marsh-estuarine system. While
this system has only minor freshwater inputs of nutrients or radium, it
is an extremely productive ecosystem. In addition, there are significant
exports of these dis...
The phosphate sorption capacity of intertidal vegetated marsh sediments was measured along a salinity gradient in the Cooper River estuary, South Carolina. The phosphate sorption capacity of the surface sediments (0-10 cm) of a freshwater marsh was higher than the sorption capacity of sediments from brackish and saline marshes, and surface sediment...
We examined forms of solid phosphorus fractions in intertidal marsh sediments along a salinity (0–22%.) gradient in a river-dominated estuary and in a marine-dominated salt marsh with insignificant freshwater input. Freshwater marsh sediments had the highest ratio of organic N:P of between 28:1 and 47:1 mol:mol, compared to 211 to 311 molmol in the...
Results of a 12-yr study in an oligotrophic South Carolina salt marsh demonstrate that soil respiration increased by 795 g C m-2 yr-1 and that carbon inventories decreased in sediments fertilized with nitrogen and phosphorus. Fertilized plots became net sources of carbon to the atmosphere, and sediment respiration continues in these plots at an acc...
In North Inlet, a tidally dominated salt-marsh estuary near Georgetown, South Carolina, the summer chlorophyll maximum correlates with an annual peak in ambient NH4+ concentration. This relationship suggests that phytoplankton population growth during the summer bloom is limited by factors other than nutrient supply, because NH4+ is the major inorg...
Dimethylsulphoniopropionate (DMSP) in saltmarsh grasses of the genus Spartina has been suggested to act as a compatible osmolyte or as an intermediary product of a sulphide detoxification mechanism. Investigations of Spartina alterniflora Loisel. plants collected from salinity and sulphide gradients along a South Carolina river showed that DMSP con...
Nitrogen was withheld from the salt marsh grass Spartina alterniflora Loisel., in order to determine the effect of salinity (sea salts) on critical tissue nitrogen concentrations (defined here as the minimum tissue concentration required to sustain biomass accumulation). The critical nitrogen concentration per kilogram dry weight of above-ground ti...
We combined field, laboratory, and modeling efforts to construct a process-oriented N budget for a tidal freshwater wetland in eastern Massachusetts. The emergent marsh contained most of the total N in the wetland because of its large area and high N mass per unit area. Total N stored in live marsh plants, dead litter, and inorganic interstitial wa...
The effects of short- and long-term exposure to a range in concentration of sea salts on the kinetics of NH
inf4sup+uptake by Spartina alterniflora were examined in a laboratory culture experiment. Long-term exposure to increasing salinity up to 50 g/L resulted in a progressive increase in the apparent Km but did not significantly affect Vmax (mean...
