Greenhouse gas flux with reflooding of a drained salt marsh soil

Salt marshes are highly effective carbon (C) sinks and bury more C per square meter annually than any other ecosystem. Reclamation and anthropogenic impacts, however, have resulted in extensive losses of salt marshes. Carbon credits can be generated and sold by restoring marshes, but only if C sequestration and net reductions in greenhouse gases (GHG) are reliably quantified. Restored marshes, however, may exhibit different patterns of GHG emissions than natural marshes and it is possible that they could temporarily become sources of N2O even in the usually N-limited estuarine environment. Research on short-term GHG flux following salt marsh restoration is limited to studies of two restored marshes which examined GHG flux more than six months after the return of tidal flooding. Here we report on a laboratory experiment in which soil cores collected from a drained agricultural marsh on the St. Lawrence Estuary were flooded with estuary water. Gas flux measurements immediately after flooding revealed small increases in N2O and CH4, but a large decline in CO2 yielding, from a climatic perspective, a net cooling effect over the observation period. In addition to restoring the land’s capacity to sequester C once a marsh develops, returning tidal flooding thus appears to have the added benefit of stemming large ongoing C losses. With more than 400 km2 of undeveloped dykeland, Eastern Canada is well positioned to restore large sections of marsh and contribute to reducing atmospheric CO2 concentrations.

Download Full-text

Salt marshes of Atlantic Canada: their ecology and distribution

Canadian Journal of Botany ◽

10.1139/b86-060 ◽

1986 ◽

Vol 64 (2) ◽

pp. 455-467 ◽

Cited By ~ 19

Author(s):

Bruce A. Roberts ◽

Alexander Robertson

Keyword(s):

Salt Marsh ◽

Salt Marshes ◽

Anthropogenic Influences ◽

Eastern Canada ◽

Environment Management ◽

Oil Development ◽

The Status ◽

Domestic Use ◽

High Degree ◽

Offshore Oil

This paper reviews the status of research on the Atlantic salt marshes of eastern Canada. The floristics, habitats, and biophysical aspects of the Atlantic salt marshes are described and aspects relating to anthropogenic influences on the Atlantic marshes are discussed in the context of contemporary rural settlement and vulnerability to offshore oil development. Guidelines for environment management, protection, and rehabilitation research are proposed. Such guidelines are deemed important since more than half the 33 000 ha of salt marshes in Nova Scotia have been dyked for agriculture. Most of the salt-marsh habitats in Newfoundland have a high degree of domestic grazing, even though the marshes are small in size and rare in occurrence. The least disturbed in terms of domestic use are the Labrador salt marshes which, although grazed by migratory ducks and geese, have not yet been influenced by man's activities. In addition, the Labrador salt marshes are discussed and compared with the northern marshes of arctic Canada in terms of their ecology and formation.

Download Full-text

Top-down and sideways: Herbivory and cross-ecosystem connectivity shape restoration success at the salt marsh-upland ecotone

PLoS ONE ◽

10.1371/journal.pone.0247374 ◽

2021 ◽

Vol 16 (2) ◽

pp. e0247374

Author(s):

Kerstin Wasson ◽

Karen E. Tanner ◽

Andrea Woofolk ◽

Sean McCain ◽

Justin P. Suraci

Keyword(s):

Salt Marsh ◽

Salt Marshes ◽

Camera Traps ◽

Physical Factors ◽

High Marsh ◽

Top Down ◽

Salt Marsh Restoration ◽

Marsh Restoration ◽

Restoration Site ◽

Restoration Success

Wetland restoration provides remarkable opportunities to understand vegetation dynamics and to inform success of future projects through rigorous restoration experiments. Salt marsh restoration typically focuses on physical factors such as sediment dynamics and elevation. Despite many demonstrations of strong top-down effects on salt marshes, the potential for consumers to affect salt marsh restoration projects has rarely been quantified. Recently, major restoration projects at the Elkhorn Slough National Estuarine Research Reserve in central California, USA provided an opportunity to examine how herbivory influences restoration success. We quantified the strength of consumer effects by comparing caged to uncaged plantings, and compared effects among plant species and sites. We used camera traps to detect which herbivores were most common and how their abundance varied spatially. Beyond characterizing consumer effects, we also tested management strategies for reducing negative effects of herbivory at the restoration sites, including caging, mowing, and acoustic playbacks of predator sounds. We found extremely strong consumer effects at sites with extensive stands of exotic forbs upland of the high marsh; uncaged restoration plants suffered heavy herbivory and high mortality, while most caged plants survived. Brush rabbits (Sylvilagus bachmani) were by far the most frequent consumers of these high marsh plants. Our work thus provides the first evidence of mammal consumers affecting salt marsh restoration success. Mowing of tall exotic forb cover adjacent to the marsh at one restoration site greatly reduced consumption, and nearly all monitored plantings survived at a second restoration site where construction had temporarily eliminated upland cover. Playbacks of predator sounds did not significantly affect restoration plantings, but restoration efforts in marsh communities vulnerable to terrestrial herbivory may benefit from concurrent restoration of predator communities in the upland habitats surrounding the marsh. A landscape approach is thus critical for recognizing linkages between terrestrial and marine vegetation.

Download Full-text

Hitchhiking Halophytes in Wrack and Sediment-Laden Ice Blocks Contribute To Tidal Marsh Development in The Upper Bay of Fundy.

10.21203/rs.3.rs-1021544/v1 ◽

2021 ◽

Author(s):

Jeremy Lundholm ◽

Tasha R.M. Rabinowitz ◽

Lyndsay Greene ◽

Alisha D. Glogowski ◽

Tony Bowron ◽

...

Keyword(s):

Salt Marsh ◽

Salt Marshes ◽

Coastal Wetland ◽

Marsh Surface ◽

Plant Colonization ◽

Bay Of Fundy ◽

Plant Debris ◽

Salt Marsh Restoration ◽

Potential Source ◽

Total Sediment

Abstract Salt marshes are a type of coastal wetland that are affected by dynamic coastal processes. Ice blocks and wrack (mats of plant debris) regularly float onto northern marshes and become stranded, affecting vegetation and soil accretion. There is little research regarding the capacity of ice and wrack to transport viable plant propagules onto marshes where they can colonize, which may be particularly important at barren new salt marsh restoration sites. Contributions of sediment by ice may also be important at restoration sites to raise the marsh platform to elevations appropriate for plant colonization. We collected ice (n = 27) and wrack (n = 18) samples at marshes in the Bay of Fundy, ran germination trials with the contents, and measured the quantity of sediment in the ice. We found viable propagules from halophytic and non-halophytic species in wrack, and viable propagules of Sporobolus pumilus in ice. Additionally, we found sediment densities between 0.01 and 4.75 g·cm−3 in ice blocks that translated to 26.61 – 21,483.59 kg of total sediment per block, representing a large source of sediment. We found that the number of germinating propagules could not be predicted by wrack size, and that pH, sediment density, sediment weight in ice blocks were variable across the marsh surface, while ice salinity was negatively correlated with elevation and distance from creek. Our results indicate that ice and wrack represent a potential source for vegetation colonization at salt marsh sites and highlights their contributions to facilitating vegetation colonization through building marsh soils.

Download Full-text

Controls on salt marsh accretion: A test in salt marshes of Eastern Canada

Estuaries ◽

10.1007/bf02803561 ◽

2004 ◽

Vol 27 (1) ◽

pp. 70-81 ◽

Cited By ~ 66

Author(s):

Gail L. Chmura ◽

Grace A. Hung

Keyword(s):

Salt Marsh ◽

Salt Marshes ◽

Eastern Canada ◽

Marsh Accretion

Download Full-text

Inoculating rhizome-propagated Sporobolus pumilus with a native mycorrhizal fungus increases salt marsh plant growth and survival

FACETS ◽

10.1139/facets-2020-0104 ◽

2021 ◽

Vol 6 ◽

pp. 1134-1145

Author(s):

Tyler W. d’Entremont ◽

Juan C. López-Gutiérrez ◽

Allison K. Walker

Keyword(s):

Salt Marsh ◽

Salt Marshes ◽

Large Scale ◽

Life Stage ◽

Mycorrhizal Fungus ◽

Arbuscular Mycorrhizal ◽

Nutrient Status ◽

Salt Marsh Restoration ◽

Growth And Survival ◽

Salt Marsh Plant

Salt marshes are ecosystems of significant ecological importance for coastal stability and fundamental roles in marine ecosystems. Salt marshes are declining due to anthropogenic and natural causes including sea level rise. Coastal restoration efforts have increased worldwide, but many fail in long-term coastal stability. We used a naturally occurring arbuscular mycorrhizal fungus (AMF) to test whether survival and early growth of the salt marsh grass Sporobolus pumilus (formerly Spartina patens) improved under simulated salt marsh conditions. Using a tidal mesocosm bench, we grew inoculated plants with varying AMF treatments under simulated tidal regimes to determine if AMF could aid in establishment of healthy Sporobolus communities. Rhizome-derived S. pumilus had greater survival and grew faster than seed-derived plants. Plants inoculated with propagated AMF consistently outperformed both sterile and native sediment controls in terms of plant survival and growth. Use of rhizome-derived Sporobolus inoculated with propagated Funneliformis geosporum showed the most promise in producing successful plant populations for salt marsh restoration. This may be due to plant life stage and improved plant nutrient status, allowing rhizome-derived plants to grow more quickly than seed-derived plants. Using these plants in future large-scale restoration may increase re-establishment of salt marsh ecosystems.

Download Full-text

Salt Marsh Restoration for the Provision of Multiple Ecosystem Services

Diversity ◽

10.3390/d13120680 ◽

2021 ◽

Vol 13 (12) ◽

pp. 680

Author(s):

Janine B. Adams ◽

Jacqueline L. Raw ◽

Taryn Riddin ◽

Johan Wasserman ◽

Lara Van Niekerk

Keyword(s):

Ecosystem Services ◽

Salt Marsh ◽

Salt Marshes ◽

Well Being ◽

Coastal Protection ◽

Degraded Land ◽

National Scale ◽

Salt Marsh Restoration ◽

Marsh Restoration ◽

Run Off

Restoration of salt marsh is urgent, as these ecosystems provide natural coastal protection from sea-level rise impacts, contribute towards climate change mitigation, and provide multiple ecosystem services including supporting livelihoods. This study identified potential restoration sites for intervention where agricultural and degraded land could be returned to salt marsh at a national scale in South African estuaries. Overall, successful restoration of salt marsh in some estuaries will require addressing additional pressures such as freshwater inflow reduction and deterioration of water quality. Here, we present, a socio-ecological systems framework for salt marsh restoration that links salt marsh state and the well-being of people to guide meaningful and implementable management and restoration interventions. The framework is applied to a case study at the Swartkops Estuary where the primary restoration intervention intends to route stormwater run-off to abandoned salt works to re-create aquatic habitat for waterbirds, enhance carbon storage, and provide nutrient filtration. As the framework is generalized, while still allowing for site-specific pressures to be captured, there is potential for it to be applied at the national scale, with the largest degraded salt marsh areas set as priorities for such an initiative. It is estimated that ~1970 ha of salt marsh can be restored in this way, and this represents a 14% increase in the habitat cover for the country. Innovative approaches to restoring and improving condition are necessary for conserving salt marshes and the benefits they provide to society.

Download Full-text

Uptake of arsenic by Aster tripolium in relation to rhizosphere oxidation

Canadian Journal of Botany ◽

10.1139/b91-335 ◽

1991 ◽

Vol 69 (12) ◽

pp. 2670-2677 ◽

Cited By ~ 90

Author(s):

M. L. Otte ◽

I. M. J. Dekkers ◽

J. Rozema ◽

R. A. Broekman

Keyword(s):

Salt Marsh ◽

Salt Marshes ◽

Bulk Soil ◽

Marsh Soil ◽

Salt Marsh Plants ◽

Aster Tripolium ◽

Detoxification Mechanism ◽

Key Factor ◽

Salt Marsh Soil ◽

Reduced State

Arsenic present in salt marsh soil is taken up by plants and subsequently transferred to other parts of the ecosystem. The reduced state of the bulk soil of salt marshes favours the mobility of arsenic. In the rhizosphere of plants however, arsenic may be immobilized owing to oxidation of arsenic (III) to less mobile arsenic (V) and adsorption to iron (hydr-)oxides. In a field survey iron concentrations in the vicinity of roots of Aster tripolium were higher than in the bulk soil. In a greenhouse experiment accumulation of arsenic and iron in the rhizosphere occurred, which could be due to the oxidizing activity of plant roots and (or) microorganisms. This process stimulates uptake of arsenic by salt marsh plants. The formation of an iron plaque seems to play an important role in the uptake of arsenic by salt marsh plants, as was indicated by an incubation experiment with root parts of A. tripolium. The results of the experiments indicate that iron plays a key factor in determining the mobility of arsenic in salt marsh soils and in the uptake and translocation processes in the plants. Although oxidation processes in the rhizosphere enhance uptake of arsenic, it may be an important detoxification mechanism for the plants. Key words: arsenic, Aster tripolium, iron, rhizosphere, salt marsh.

Download Full-text

Urbanization impacts on production and recruitment of Fundulus heteroclitus in salt marsh creeks

Marine Ecology Progress Series ◽

10.3354/meps13378 ◽

2020 ◽

Vol 645 ◽

pp. 187-204

Author(s):

PJ Rudershausen ◽

JA Buckel

Keyword(s):

Salt Marsh ◽

Salt Marshes ◽

Fundulus Heteroclitus ◽

Multiple Factor Analysis ◽

Southeastern Usa ◽

Density Dependent ◽

Dependent Relationship ◽

Juvenile Abundance ◽

The Relationship ◽

Throw Trap

It is unclear how urbanization affects secondary biological production in estuaries in the southeastern USA. We estimated production of larval/juvenile Fundulus heteroclitus in salt marsh areas of North Carolina tidal creeks and tested for factors influencing production. F. heteroclitus were collected with a throw trap in salt marshes of 5 creeks subjected to a range of urbanization intensities. Multiple factor analysis (MFA) was used to reduce dimensionality of habitat and urbanization effects in the creeks and their watersheds. Production was then related to the first 2 dimensions of the MFA, month, and year. Lastly, we determined the relationship between creek-wide larval/juvenile production and abundance from spring and abundance of adults from autumn of the same year. Production in marsh (g m-2 d-1) varied between years and was negatively related to the MFA dimension that indexed salt marsh; higher rates of production were related to creeks with higher percentages of marsh. An asymptotic relationship was found between abundance of adults and creek-wide production of larvae/juveniles and an even stronger density-dependent relationship was found between abundance of adults and creek-wide larval/juvenile abundance. Results demonstrate (1) the ability of F. heteroclitus to maintain production within salt marsh in creeks with a lesser percentage of marsh as long as this habitat is not removed altogether and (2) a density-dependent link between age-0 production/abundance and subsequent adult recruitment. Given the relationship between production and marsh area, natural resource agencies should consider impacts of development on production when permitting construction in the southeastern USA.

Download Full-text

Topological and Morphological Controls on Morphodynamics of Salt Marsh Interiors

Journal of Marine Science and Engineering ◽

10.3390/jmse9030311 ◽

2021 ◽

Vol 9 (3) ◽

pp. 311

Author(s):

Ben R. Evans ◽

Iris Möller ◽

Tom Spencer

Keyword(s):

Salt Marsh ◽

Salt Marshes ◽

East Coast ◽

Marsh Surface ◽

Coastal Environments ◽

Coastal System ◽

Morphological Segmentation ◽

The Usa ◽

The Uk ◽

Over Time

Salt marshes are important coastal environments and provide multiple benefits to society. They are considered to be declining in extent globally, including on the UK east coast. The dynamics and characteristics of interior parts of salt marsh systems are spatially variable and can fundamentally affect biotic distributions and the way in which the landscape delivers ecosystem services. It is therefore important to understand, and be able to predict, how these landscape configurations may evolve over time and where the greatest dynamism will occur. This study estimates morphodynamic changes in salt marsh areas for a regional domain over a multi-decadal timescale. We demonstrate at a landscape scale that relationships exist between the topology and morphology of a salt marsh and changes in its condition over time. We present an inherently scalable satellite-derived measure of change in marsh platform integrity that allows the monitoring of changes in marsh condition. We then demonstrate that easily derived geospatial and morphometric parameters can be used to determine the probability of marsh degradation. We draw comparisons with previous work conducted on the east coast of the USA, finding differences in marsh responses according to their position within the wider coastal system between the two regions, but relatively consistent in relation to the within-marsh situation. We describe the sub-pixel-scale marsh morphometry using a morphological segmentation algorithm applied to 25 cm-resolution maps of vegetated marsh surface. We also find strong relationships between morphometric indices and change in marsh platform integrity which allow for the inference of past dynamism but also suggest that current morphology may be predictive of future change. We thus provide insight into the factors governing marsh degradation that will assist the anticipation of adverse changes to the attributes and functions of these critical coastal environments and inform ongoing ecogeomorphic modelling developments.

Download Full-text

Machine-Learning Classification of Soil Bulk Density in Salt Marsh Environments

Sensors ◽

10.3390/s21134408 ◽

2021 ◽

Vol 21 (13) ◽

pp. 4408

Author(s):

Iman Salehi Hikouei ◽

S. Sonny Kim ◽

Deepak R. Mishra

Keyword(s):

Machine Learning ◽

Remote Sensing ◽

Salt Marsh ◽

Bulk Density ◽

Remote Sensing Data ◽

Soil Bulk Density ◽

Soil Samples ◽

Marsh Soil ◽

Landsat 7 ◽

Salt Marsh Soil

Remotely sensed data from both in situ and satellite platforms in visible, near-infrared, and shortwave infrared (VNIR–SWIR, 400–2500 nm) regions have been widely used to characterize and model soil properties in a direct, cost-effective, and rapid manner at different scales. In this study, we assess the performance of machine-learning algorithms including random forest (RF), extreme gradient boosting machines (XGBoost), and support vector machines (SVM) to model salt marsh soil bulk density using multispectral remote-sensing data from the Landsat-7 Enhanced Thematic Mapper Plus (ETM+) platform. To our knowledge, use of remote-sensing data for estimating salt marsh soil bulk density at the vegetation rooting zone has not been investigated before. Our study reveals that blue (band 1; 450–520 nm) and NIR (band 4; 770–900 nm) bands of Landsat-7 ETM+ ranked as the most important spectral features for bulk density prediction by XGBoost and RF, respectively. According to XGBoost, band 1 and band 4 had relative importance of around 41% and 39%, respectively. We tested two soil bulk density classes in order to differentiate salt marshes in terms of their capability to support vegetation that grows in either low (0.032 to 0.752 g/cm3) or high (0.752 g/cm3 to 1.893 g/cm3) bulk density areas. XGBoost produced a higher classification accuracy (88%) compared to RF (87%) and SVM (86%), although discrepancies in accuracy between these models were small (<2%). XGBoost correctly classified 178 out of 186 soil samples labeled as low bulk density and 37 out of 62 soil samples labeled as high bulk density. We conclude that remote-sensing-based machine-learning models can be a valuable tool for ecologists and engineers to map the soil bulk density in wetlands to select suitable sites for effective restoration and successful re-establishment practices.

Download Full-text