Relationships between ecosystem properties and sea-level rise vulnerability of tidal wetlands of the U.S. Mid-Atlantic

Elsey‐Quirk, Tracy; Watson, E. B.; Raper, Kirk; Kreeger, Danielle; Paudel, Bhanu; Haaf, LeeAnn; Maxwell-Doyle, Martha; Padeletti, Angela; Reilly, Erin; Velinsky, David J.

doi:10.1007/s10661-022-09949-y

Cited by 8 publications

(5 citation statements)

References 58 publications

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“…On the other hand, the bottom of ponded areas that are too low in elevation to support vegetation should not be expected to recolonize ( Besterman et al, 2022 ). The challenge is how to delineate what “too low” might mean in the US Northeast where tidal range can vary from a few cm to several meters and marsh elevations can vary by over a meter ( Elsey-Quirk et al, 2022 ). A simple and promising indicator may be if the ponded area is recently formed (assessed using historic imagery), shallow, or somewhat ephemeral and the marsh platform has not subsided.…”

Section: Discussionmentioning

confidence: 99%

“…While our groundwater table data were not collected consistently during the same months each year, nor do they have as rigorous an elevation control as NOAA tide stations, it does suggest that salt marsh groundwater tables may be rising at a rate that exceeds that of mean sea level, and more closely approximates MHW. Increases in MHW have been observed at rates approaching 1-cm yr −1 over the past 19 years across the US Northeast (Courtney et al, 2020;Haaf et al, 2022).…”

Section: Runnels As a Tool To Build Ecosystem Resiliencementioning

confidence: 99%

“…0.40 m, and the water table dropped 0.07-0.12 m based on runnel installation to 0.30 m depth. To operationalize the investigation of tidal range at a candidate site, VDATUM can be used to estimate tidal range in US Northeastern marshes (Haaf et al, 2022); although data is not always available or accurate for back-barrier marshes (Cole . In these cases, deployment of an in-channel water level logger for a short time period (e.g., 1-2 months) with data post-processed in R (R Core Team, 2018) using the package VulnToolkit (Hill and Anisfeld, 2021) could help establish tidal range, and can be adjusted using nearby NOAA tide gauge data (NOAA, 2003).…”

Section: Recommendations For Future Projectsmentioning

confidence: 99%

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Runnels mitigate marsh drowning in microtidal salt marshes

Watson

Ferguson

Champlin

et al. 2022

Front. Environ. Sci.

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As a symptom of accelerated sea level rise and historic impacts to tidal hydrology from agricultural and mosquito control activities, coastal marshes in the Northeastern U.S. are experiencing conversion to open water through edge loss, widening and headward erosion of tidal channels, and the formation and expansion of interior ponds. These interior ponds often form in high elevation marsh, confounding the notion applied in predictive modeling that salt marshes convert to open water when elevation falls below a critical surface inundation threshold. The installation of tidal channel extension features, or runnels, is a technique that has been implemented to reduce water levels and permit vegetation reestablishment in drowning coastal marshes, although there are limited data available to recommend its advisability. We report on 5 years of vegetation and hydrologic monitoring of two locations where a total of 600-m of shallow (0.15–0.30-m in diameter and depth) runnels were installed in 2015 and 2016 to enhance drainage, in the Pettaquamscutt River Estuary, in southern Rhode Island, United States. Results from this Before-After Control-Impact (BACI) designed study found that runnel installation successfully promoted plant recolonization, although runnels did not consistently promote increases in high marsh species presence or diversity. Runnels reduced the groundwater table (by 0.07–0.12 m), and at one location, the groundwater table experienced a 2-fold increase in the fraction of the in-channel tidal range that was observed in the marsh water table. We suggest that restoration of tidal hydrology through runnel installation holds promise as a tool to encourage revegetation and extend the lifespan of drowning coastal marshes where interior ponds are expanding. In addition, our study highlights the importance of considering the rising groundwater table as an important factor in marsh drowning due to expanding interior ponds found on the marsh platform.

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Section: Discussionmentioning

confidence: 99%

Section: Runnels As a Tool To Build Ecosystem Resiliencementioning

confidence: 99%

Section: Recommendations For Future Projectsmentioning

confidence: 99%

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Runnels mitigate marsh drowning in microtidal salt marshes

Watson

Ferguson

Champlin

et al. 2022

Front. Environ. Sci.

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“…Plants were exposed to simulated once‐daily tides (MacTavish & Cohen 2014) where plants were flooded to a depth of 5 cm for 4 hours, and the soil was drained to 16.5 cm below the sediment surface for 20 hours. For reference, this inundation time (17%) corresponds to that considered “regularly flooded” (Eleuterius & Eleuterius 1979), but is flooded less frequently than that observed for 9 of 10 Mid‐Atlantic marshes which were found to have an average inundation time of 31% (Elsey‐Quirk et al 2022). Inundation times for Cape Cod marshes were found to be 15% in healthy marshes versus 45% in fragmenting marshes (Smith et al 2012).…”

Section: Methodsmentioning

confidence: 85%

Promoting success in thin layer sediment placement: effects of sediment grain size and amendments on salt marsh plant growth and greenhouse gas exchange

Wilburn,

Raper,

Raposa

et al. 2024

Restoration Ecology

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Thin layer sediment placement (TLP) is used to build elevation in marshes, counteracting effects of subsidence and sea level rise. However, TLP success may vary due to plant stress associated with reductions in nutrient availability and hydrologic flushing or through the creation of acid sulfate soils. This study examined the influence of sediment grain size and soil amendments on plant growth, soil and porewater characteristics, and greenhouse gas exchange for three key U.S. salt marsh plants: Spartina alterniflora (synonym Sporobolus alterniflorus), Spartina patens (synonym Sporobolus pumilus), and Salicornia pacifica. We found that bioavailable nitrogen concentrations (measured as extractable NH4+‐N) and porewater pH and salinity were inversely related to grain size, while soil redox was more reducing in finer sediments. This suggests that utilizing finer sediments in TLP projects will result in a more reduced environment with higher nutrient availability, while larger grain sized sediments will be better flushed and oxygenated. We further found that grain size had a significant effect on vegetation biomass allocation and rates of gas exchange, although these effects were species‐specific. We found that soil amendments (biochar and compost) did not subsidize plant growth but were associated with increases in soil respiration and methane emissions. Biochar amendments were additionally ineffective in ameliorating acid sulfate conditions. This study uncovers complex interactions between sediment type and vegetation, emphasizing the limitations of soil amendments. The findings aid restoration project managers in making informed decisions regarding sediment type, target vegetation, and soil amendments for successful TLP projects.

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“…The capacity of coastal wetlands to sustain their position within the tidal envelope is key to resiliency under conditions of climate change [1,2]. As these environments provide substantial habitat value and ecosystem function [3][4][5], myriad investigations have been conducted over the years to quantify ongoing and future risks to their resiliency under conditions of a changing climate and, in particular, accelerating sea level rise. Initially, these investigations focused on observations of ecosystem migration [6,7] and vertical sediment accumulation [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Horizontal Rates of Wetland Migration Appear Unlikely to Keep Pace with Shoreline Transgression under Conditions of 21st Century Accelerating Sea Level Rise along the Mid-Atlantic and Southeastern USA

Parkinson

2024

Coasts

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This investigation evaluated two fundamental assumptions of wetland inundation models designed to emulate landscape evolution and resiliency under conditions of sea level rise: that they can (1) migrate landward at the same rate as the transgressing shoreline and (2) immediately replace the plant community into which they are onlapping. Rates of wetland (e.g., marsh, mangrove) migration were culled from 11 study areas located in five regions of focus: Delaware Bay, Chesapeake Bay, Pamlico Sound, South Florida, and Northwest Florida. The average rate of marsh migration (n = 14) was 3.7 m yr−1. The average rate of South Florida mangrove migration (n = 4) was 38.0 m yr−1. The average rate of upland forest retreat (n = 4) was 3.4 m yr−1. Theoretical rates of shoreline transgression were calculated using site-specific landscape slope and scenario-based NOAA sea level rise elevations in 2050. Rates of shoreline transgression over the marsh landscape averaged 94 m yr−1. The average rate of shoreline transgression in the mangrove-dominated areas of South Florida was 153.2 m yr−1. The calculated rates of shoreline transgression were much faster than the observed horizontal marsh migration, and by 2050, the offset or gap between them averaged 2700 m and ranged between 292 and 5531 m. In South Florida, the gap average was 3516 m and ranged between 2766 m and 4563 m. At sites where both horizontal marsh migration and forest retreat rates were available, the distance or gap between them in 2050 averaged 47 m. Therefore, the results of this study are inconsistent with the two fundamental assumptions of many wetland inundation models and suggest that they may overestimate their resilience under conditions of 21st century accelerating sea level rise.

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Relationships between ecosystem properties and sea-level rise vulnerability of tidal wetlands of the U.S. Mid-Atlantic

Cited by 8 publications

References 58 publications

Runnels mitigate marsh drowning in microtidal salt marshes

Runnels mitigate marsh drowning in microtidal salt marshes

Promoting success in thin layer sediment placement: effects of sediment grain size and amendments on salt marsh plant growth and greenhouse gas exchange

Horizontal Rates of Wetland Migration Appear Unlikely to Keep Pace with Shoreline Transgression under Conditions of 21st Century Accelerating Sea Level Rise along the Mid-Atlantic and Southeastern USA

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