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M J Baptist - One of the best experts on this subject based on the ideXlab platform.
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where does the Salt Marsh start field based evidence for the lack of a transitional area between a gradually sloping intertidal flat and Salt Marsh
Estuarine Coastal and Shelf Science, 2020Co-Authors: M Van Regteren, M J Baptist, A. V. Groot, D Amptmeijer, Kelly ElschotAbstract:Abstract Salt Marshes are vegetated ecosystems between land and sea, hosting unique plant and animal communities, contributing to crucial habitats for birds and providing numerous other ecosystem services. They form a sustainable nature-based coastal protection, and its protective value increases with the width of the system. Salt Marshes and their adjoining tidal flats are often studied separately. At present, there is a lack of studies that describe the features of these two systems in unison and in relation to each other. This study descriptively assesses an array of abiotic and biotic variables that potentially affect successful vegetation establishment. Unfavourable soil conditions may limit establishment as well as bioturbation of infauna. This is related to the Marsh expansion potential and could aid in Salt Marsh restoration and Marsh growth stimulation projects. In a naturally developing Salt Marsh, we sampled the elevation gradient from the tidal flat to the low Marsh for benthic species composition, plant seed availability and abiotic variables. The abundance of benthos was highest landwards of the transition zone, in the pioneer zone. Distinct meiobenthic groups occurred in the different zones along the tidal flat to low Marsh gradient, but macrobenthos was largely absent from the muddy soil. In the sparsely vegetated transition zone, the abundance of Salt-Marsh seeds was low, similar to the tidal flat. It suggests that, even though a seed source was in proximity, seed availability in spring was insufficient to achieve lateral Marsh expansion. Clustering and nMDS analyses showed that an identifiable transition zone was lacking. The transition zone resembled the bare tidal flat in terms of its abiotic and biotic conditions. This was mainly driven by significant changes in soil oxygenation and seed availability.
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Multiple Environmental Variables Affect Germination and Mortality of an Annual Salt Marsh Pioneer: Salicornia procumbens
Estuaries and Coasts, 2020Co-Authors: M. Regteren, M J Baptist, E. H. Meesters, A. V. Groot, T. J. Bouma, K. ElschotAbstract:Salt Marshes, providing numerous ecosystem services, are degrading worldwide. To effectively aid conservation and restoration efforts, increased knowledge on Marsh expansion processes and the initial establishment of pioneer vegetation is essential. In this study, we disentangle environmental drivers that affect the lifecycle of the annual pioneer Salicornia procumbens at the Salt Marsh edge . We studied the effect of various environmental variables on the start of germination, germination success and mortality before seed-set in a field experiment in the Dutch Wadden Sea at Westhoek. Our results indicate that temperature and sedimentation inhibited the initiation of germination. Once germination occurred, higher precipitation rates increased germination success. In contrast, sedimentation rates above 0.5 mm day^−1 halved germination success through burial of freshly sprouted seedlings. Unexpectedly, natural germination was low, indicating that seed availability may have been limited, despite a seed source nearby. Frequent inundation, extended periods without inundation (through desiccation of the soil) and a highly dynamic bed level increased mortality before seed-set. Consequently, bed-level dynamics (erosion, sedimentation and bed-level variation) impact seed production dually (decrease germination and increase mortality) and thus potentially reproduction success. A high seed reproduction is crucial for annuals, such as S. procumbens , to re-establish the following year. Next to advancing our general knowledge of natural Salt Marsh expansion, results in this study can also be used to assess the potential of a given site for Salt Marsh stimulation or restoration. Seed availability and local bed-level dynamics are key in the successful establishment of a Salt Marsh pioneer: Salicornia procumbens .
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beneficial use of dredged sediment to enhance Salt Marsh development by applying a mud motor
Ecological Engineering, 2019Co-Authors: M J Baptist, Theo Gerkema, B C Van Prooijen, D S Van Maren, M Van Regteren, K Schulz, I Colosimo, J Vroom, T Van Kessel, B T GrasmeijerAbstract:We test an innovative approach to beneficially re-use dredged sediment to enhance Salt Marsh development. A Mud Motor is a dredged sediment disposal in the form of a semi-continuous source of mud in a shallow tidal channel allowing natural processes to disperse the sediment to nearby mudflats and Salt Marshes. We describe the various steps in the design of a Mud Motor pilot: numerical simulations with a sediment transport model to explore suitable disposal locations, a tracer experiment to measure the transport fate of disposed mud, assessment of the legal requirements, and detailing the planning and technical feasibility. An extensive monitoring and research programme was designed to measure sediment transport rates and the response of intertidal mudflats and Salt Marshes to an increased sediment load. Measurements include the sediment transport in the tidal channel and on the shallow mudflats, the vertical accretion of intertidal mudflats and Salt Marsh, and the Salt Marsh vegetation cover and composition. In the Mud Motor pilot a total of 470,516 m3 of fine grained sediment (D50 of ∼10 μm) was disposed over two winter seasons, with an average of 22 sediment disposals per week of operation. Ship-based measurements revealed a periodic vertical salinity stratification that is inverted compared to a classical estuary and that is working against the asymmetric flood-dominated transport direction. Field measurements on the intertidal mudflats showed that the functioning of the Mud Motor, i.e. the successful increased mud transport toward the Salt Marsh, is significantly dependent on wind and wave forcing. Accretion measurements showed relatively large changes in surface elevation due to deposition and erosion of layers of watery mud with a thickness of up to 10 cm on a time scale of days. The measurements indicate notably higher sediment dynamics during periods of Mud Motor disposal. The Salt Marsh demonstrated significant vertical accretion though this has not yet led to horizontal expansion because there was more hydrodynamic stress than foreseen. In carrying out the pilot we learned that the feasibility of a Mud Motor depends on an assessment of additional travel time for the dredger, the effectiveness on Salt Marsh growth, reduced dredging volumes in a port, and many other practical issues. Our improved understanding on the transport processes in the channel and on the mudflats and Salt Marsh yields design lessons and guiding principles for future applications of sediment management in Salt Marsh development that include a Mud Motor approach.
Mark D Bertness - One of the best experts on this subject based on the ideXlab platform.
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Centuries of Human-Driven Change in Salt Marsh Ecosystems
Annual review of marine science, 2009Co-Authors: K. Bromberg Gedan, Brian R Silliman, Mark D BertnessAbstract:Salt Marshes are among the most abundant, fertile, and accessible coastal habitats on earth, and they provide more ecosystem services to coastal populations than any other environment. Since the Middle Ages, humans have manipulated Salt Marshes at a grand scale, altering species composition, distribution, and ecosystem function. Here, we review historic and contemporary human activities in Marsh ecosystems—exploitation of plant products; conversion to farmland, Salt works, and urban land; introduction of non-native species; alteration of coastal hydrology; and metal and nutrient pollution. Unexpectedly, diverse types of impacts can have a similar consequence, turning Salt Marsh food webs upside down, dramatically increasing top down control. Of the various impacts, invasive species, runaway consumer effects, and sea level rise represent the greatest threats to Salt Marsh ecosystems. We conclude that the best way to protect Salt Marshes and the services they provide is through the integrated approach of ecosystem-based management.
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reconstructing new england Salt Marsh losses using historical maps
Estuaries, 2005Co-Authors: Keryn D Bromberg, Mark D BertnessAbstract:Analyses of habitat loss are often restricted to the past 75 years by the relative youth of aerial photography and remote sensing technologies. Although photographic techniques are highly accurate, they are unable to provide measurements of habitat loss prior to the 1950s. In this study, historical maps from the late 1700s and early 1800s covering portions of Rhode Islan, Massachusetts, New Hampshire, and Maine were used to approximate naturally occurring Salt Marsh cover in New England. Historical data was compared to current Salt Marsh coverage available in public geographic information system (GIS) data sets. The average loss in New England is estimated at 37% using this technique. Rhode Island has lost the largest proportion of Salt Marshes by state, a staggering 53% loss since 1832. Massachusetts has also experience large losses, amounting to a 41% loss of Salt Marsh since 1777. The Boston area alone has lost 81% of its Salt Marshes. Salt Marsh loss was highly correlated with urban growth. Restoration and preservation efforts have resulted in the retention of Salt Marsh in less populated areas of New England. Although historical maps are difficult to verify, they represent an extremely valuable and underused data repository. Using historical maps to trace land use practices is an effective way to overcome the short-term nature of many ecological studies. This technique could be applied to other habitats and other regions, wherever accurate historical maps are available. Analysis of historic conditions of habitats can help conservation managers determine appropriate goals for restoration and management.
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Anthropogenic modification of New England Salt Marsh landscapes
Proceedings of the National Academy of Sciences, 2002Co-Authors: Mark D Bertness, Patrick J. Ewanchuk, Brian R SillimanAbstract:Salt Marshes play a critical role in the ecology and geology of wave-protected shorelines in the Western Atlantic, but as many as 80% of the Marshes that once occurred in New England have already been lost to human development. Here we present data that suggest that the remaining Salt Marshes in southern New England are being rapidly degraded by shoreline development and eutrophication. On the seaward border of these Marshes, nitrogen eutrophication stimulated by local shoreline development is shifting the competitive balance among Marsh plants by releasing plants from nutrient competition. This shift is leading to the displacement of natural high Marsh plants by low Marsh cordgrass. On the terrestrial border of these same Marshes, shoreline development is also precipitating the invasion of the common reed, Phragmites, by means of nitrogen eutrophication caused by the removal of the woody vegetation buffer between terrestrial and Salt Marsh communities. As a consequence of these human impacts, traditional Salt Marsh plant communities and the plants and animals that are dependent on these habitats are being displaced by monocultures of weedy species.
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nutrients competition and plant zonation in a new england Salt Marsh
Journal of Ecology, 1998Co-Authors: Jonathan M Levine, Stephen J Brewer, Mark D BertnessAbstract:1 We examined the effects of nutrient availability on the competitive interactions of the New England Salt Marsh perennials that occupy discrete vegetational zones parallel to the shoreline. 2 Fertilized and unfertilized plots of pair-wise mixtures and monocultures of Spartina alterniflora, S. patens and Juncus gerardi were compared in order to assess the effects of nutrient addition on the competitive dynamics of these species in the field. In addition, we examined competition between some of these species and Distichlis spicata, a species common to disturbed Marsh habitats. 3 After two growing seasons, changes in above-ground biomass of the species indicated that in fertilized plots, S. alterniflora outcompeted S. patens, S. patens outcompeted J. gerardi, and D. spicata outcompeted both J. gerardi and S. patens. This was the reverse of the interactions seen under ambient Marsh conditions, and suggested that, under conditions of nutrient limitation, competitive dominance may result from efficient competition for nutrients. 4 Using a conceptual model of Salt Marsh zonation as a function of competition, physical stress and nutrient limitation, we hypothesize that a nutrient-induced reversal in the competitive dynamics among Salt Marsh perennials may result in modification of the pattern of plant zonation in this and similar Marshes.
Sergio Fagherazzi - One of the best experts on this subject based on the ideXlab platform.
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classification mapping of Salt Marsh vegetation by flexible monthly ndvi time series using landsat imagery
Estuarine Coastal and Shelf Science, 2018Co-Authors: Sergio FagherazziAbstract:Abstract Salt Marshes are deemed as one of the most dynamic and valuable ecosystems on Earth. Recently, Salt Marsh deterioration and loss have become widespread because of anthropogenic stressors and sea level rise. Long-term acquisition of spatial information on Salt Marsh vegetation communities is thus critical to detect the general evolutionary trend of Marsh ecosystems before irreversible change occurs. Medium resolution imagery organized in inter-annual time series has been proven suitable for large-scale mapping of Salt Marsh vegetation. For long-term monitoring purpose, the challenge still lies in developing time series based on data with sparse and uneven temporal distribution. This paper proposes a flexible Monthly NDVI Time-Series (MNTS) approach to achieve multi-temporal classification maps of Salt Marsh vegetation communities in the Virginia Coast Reserve, USA, by utilizing all viable Landsat TM/ETM + images during the period 1984–2011. Salt Marsh vegetation communities are identified on a reference MNTS spanning 12 months with an overall accuracy of 0.898, approximately 0.107 higher than classifications using single images. Utilizing a flexible selection process based on the reference MNTS, a significant inverse hyperbolic relationship emerges between overall accuracy and average length of the time series. Based on these results, eight classification maps with average accuracy of 0.844 and time interval of 2–5 years are acquired. A spatio-temporal analysis of the maps indicates that the upper low Marsh vegetation community has diminished by 19.4% in the study period, with a recent acceleration of losses. The conversion of Marsh area to vegetation communities typical of low elevations (37.7 km2) is more than twice the conversion to vegetation communities typical of high elevations (18.3 km2), suggesting that Salt Marsh ecosystems at the Virginia Coast Reserve are affected by sea level rise.
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Salt Marsh loss affects tides and the sediment budget in shallow bays
Journal of Geophysical Research, 2018Co-Authors: Carmine Donatelli, Neil K Ganju, Xiaohe Zhang, Sergio Fagherazzi, Nicoletta LeonardiAbstract:The current paradigm is that Salt Marshes and their important ecosystem services are threatened by global climate change; indeed, large Marsh losses have been documented worldwide. Morphological changes associated with Salt Marsh erosion are expected to influence the hydrodynamics and sediment dynamics of coastal systems. Here the influence of Salt Marsh erosion on the tidal hydrodynamics and sediment storage capability of shallow bays is investigated. Hydrodynamics, sediment transport, and vegetation dynamics are simulated using the numerical framework Coupled Ocean‐Atmosphere‐Wave‐Sediment Transport in the Barnegat Bay‐Little Egg Harbor system, USA. We show that Salt Marsh erosion influences the propagation of tides into back‐barrier basins, reducing the periodic inundation and sediment delivery to Marsh platforms. As Salt Marshes erode, the sediment trapping potential of Marsh platforms decreases exponentially. In this test case, up to 50% of the sediment mass trapped by vegetation is lost once a quarter of the Marsh area is eroded. Similarly, without Salt Marshes the sediment budget of the entire bay significantly declines. Therefore, a positive feedback might be triggered such that as the Salt Marsh retreats the sediment storage capacity of the system declines, which could in turn further exacerbate Marsh degradation.
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a linear relationship between wave power and erosion determines Salt Marsh resilience to violent storms and hurricanes
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Nicoletta Leonardi, Neil K Ganju, Sergio FagherazziAbstract:Salt Marsh losses have been documented worldwide because of land use change, wave erosion, and sea-level rise. It is still unclear how resistant Salt Marshes are to extreme storms and whether they can survive multiple events without collapsing. Based on a large dataset of Salt Marsh lateral erosion rates collected around the world, here, we determine the general response of Salt Marsh boundaries to wave action under normal and extreme weather conditions. As wave energy increases, Salt Marsh response to wind waves remains linear, and there is not a critical threshold in wave energy above which Salt Marsh erosion drastically accelerates. We apply our general formulation for Salt Marsh erosion to historical wave climates at eight Salt Marsh locations affected by hurricanes in the United States. Based on the analysis of two decades of data, we find that violent storms and hurricanes contribute less than 1% to long-term Salt Marsh erosion rates. In contrast, moderate storms with a return period of 2.5 mo are those causing the most Salt Marsh deterioration. Therefore, Salt Marshes seem more susceptible to variations in mean wave energy rather than changes in the extremes. The intrinsic resistance of Salt Marshes to violent storms and their predictable erosion rates during moderate events should be taken into account by coastal managers in restoration projects and risk management plans.
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coastal eutrophication as a driver of Salt Marsh loss
Nature, 2012Co-Authors: Linda A Deegan, Sergio Fagherazzi, David Samuel Johnson, Scott R Warren, Bruce J Peterson, John W Fleeger, Wilfred M WollheimAbstract:A nine-year whole-ecosystem experiment demonstrates that nutrient enrichment, a global problem in coastal ecosystems, can be a driver of Salt-Marsh loss. Salt Marshes provide important ecosystem services such as storm protection for coastal cities, nutrient removal and carbon sequestration, but despite protective measures these ecosystems are in decline. Nine years of data from a whole-ecosystem nutrient-enrichment experiment now demonstrate that current levels of coastal nutrient loading can alter key Salt-Marsh-ecosystem properties, leading to the collapse of creek banks and, ultimately, the conversion of Salt Marsh into mudflat. The potential deterioration of coastal Marshes owing to eutrophication adds another dimension to the challenge of managing nitrogen while meeting food-production demands in the twenty-first century. Salt Marshes are highly productive coastal wetlands that provide important ecosystem services such as storm protection for coastal cities, nutrient removal and carbon sequestration. Despite protective measures, however, worldwide losses of these ecosystems have accelerated in recent decades1. Here we present data from a nine-year whole-ecosystem nutrient-enrichment experiment. Our study demonstrates that nutrient enrichment, a global problem for coastal ecosystems2,3,4, can be a driver of Salt Marsh loss. We show that nutrient levels commonly associated with coastal eutrophication increased above-ground leaf biomass, decreased the dense, below-ground biomass of bank-stabilizing roots, and increased microbial decomposition of organic matter. Alterations in these key ecosystem properties reduced geomorphic stability, resulting in creek-bank collapse with significant areas of creek-bank Marsh converted to unvegetated mud. This pattern of Marsh loss parallels observations for anthropogenically nutrient-enriched Marshes worldwide, with creek-edge and bay-edge Marsh evolving into mudflats and wider creeks5,6,7. Our work suggests that current nutrient loading rates to many coastal ecosystems have overwhelmed the capacity of Marshes to remove nitrogen without deleterious effects. Projected increases in nitrogen flux to the coast, related to increased fertilizer use required to feed an expanding human population, may rapidly result in a coastal landscape with less Marsh, which would reduce the capacity of coastal regions to provide important ecological and economic services.
B T Grasmeijer - One of the best experts on this subject based on the ideXlab platform.
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beneficial use of dredged sediment to enhance Salt Marsh development by applying a mud motor
Ecological Engineering, 2019Co-Authors: M J Baptist, Theo Gerkema, B C Van Prooijen, D S Van Maren, M Van Regteren, K Schulz, I Colosimo, J Vroom, T Van Kessel, B T GrasmeijerAbstract:We test an innovative approach to beneficially re-use dredged sediment to enhance Salt Marsh development. A Mud Motor is a dredged sediment disposal in the form of a semi-continuous source of mud in a shallow tidal channel allowing natural processes to disperse the sediment to nearby mudflats and Salt Marshes. We describe the various steps in the design of a Mud Motor pilot: numerical simulations with a sediment transport model to explore suitable disposal locations, a tracer experiment to measure the transport fate of disposed mud, assessment of the legal requirements, and detailing the planning and technical feasibility. An extensive monitoring and research programme was designed to measure sediment transport rates and the response of intertidal mudflats and Salt Marshes to an increased sediment load. Measurements include the sediment transport in the tidal channel and on the shallow mudflats, the vertical accretion of intertidal mudflats and Salt Marsh, and the Salt Marsh vegetation cover and composition. In the Mud Motor pilot a total of 470,516 m3 of fine grained sediment (D50 of ∼10 μm) was disposed over two winter seasons, with an average of 22 sediment disposals per week of operation. Ship-based measurements revealed a periodic vertical salinity stratification that is inverted compared to a classical estuary and that is working against the asymmetric flood-dominated transport direction. Field measurements on the intertidal mudflats showed that the functioning of the Mud Motor, i.e. the successful increased mud transport toward the Salt Marsh, is significantly dependent on wind and wave forcing. Accretion measurements showed relatively large changes in surface elevation due to deposition and erosion of layers of watery mud with a thickness of up to 10 cm on a time scale of days. The measurements indicate notably higher sediment dynamics during periods of Mud Motor disposal. The Salt Marsh demonstrated significant vertical accretion though this has not yet led to horizontal expansion because there was more hydrodynamic stress than foreseen. In carrying out the pilot we learned that the feasibility of a Mud Motor depends on an assessment of additional travel time for the dredger, the effectiveness on Salt Marsh growth, reduced dredging volumes in a port, and many other practical issues. Our improved understanding on the transport processes in the channel and on the mudflats and Salt Marsh yields design lessons and guiding principles for future applications of sediment management in Salt Marsh development that include a Mud Motor approach.
Jennifer L. Bowen - One of the best experts on this subject based on the ideXlab platform.
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Nutrient Enrichment Alters Salt Marsh Fungal Communities and Promotes Putative Fungal Denitrifiers
Microbial Ecology, 2019Co-Authors: Patrick J. Kearns, Ashley N. Bulseco-mckim, Helen Hoyt, John H. Angell, Jennifer L. BowenAbstract:Enrichment of ecosystems with excess nutrients is occurring at an alarming rate and has fundamentally altered ecosystems worldwide. Salt Marshes, which lie at the land-sea interface, are highly effective at removing anthropogenic nutrients through the action of macrophytes and through microbial processes in coastal sediments. The response of Salt Marsh bacteria to excess nitrogen has been documented; however, the role of fungi and their response to excess nitrogen in Salt Marsh sediments is not fully understood. Here, we document the response of Salt Marsh fungal communities to long-term excess nitrate in four distinct Marsh habitats within a northern temperate Marsh complex. We show that Salt Marsh fungal communities varied as a function of Salt Marsh habitat, with both fungal abundance and diversity increasing with carbon quantity. Nutrient enrichment altered fungal communities in all habitats through an increase in fungal abundance and the proliferation of putative fungal denitrifiers. Nutrient enrichment also altered Marsh carbon quality in low Marsh surface sediments where fungal response to nutrient enrichment was most dramatic, suggesting nutrient enrichment can alter organic matter quality in coastal sediments. Our results indicate that fungi, in addition to bacteria, likely play an important role in anaerobic decomposition of Salt Marsh sediment organic matter.
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long term fertilization alters the relative importance of nitrate reduction pathways in Salt Marsh sediments
Journal of Geophysical Research, 2016Co-Authors: Patrick J. Kearns, John H. Angell, Jennifer L. Bowen, Xuefeng Peng, Hannah J Yang, Bess B WardAbstract:Salt Marshes provide numerous valuable ecological services. In particular, nitrogen (N) removal in Salt Marsh sediments alleviates N loading to the coastal ocean. N removal reduces the threat of eutrophication caused by increased N inputs from anthropogenic sources. It is unclear, however, whether chronic nutrient over-enrichment alters the capacity of Salt Marshes to remove anthropogenic N. To assess the effect of nutrient enrichment on N cycling in Salt Marsh sediments, we examined important N cycle pathways in experimental fertilization plots in a New England Salt Marsh. We determined rates of nitrification, denitrification, and dissimilatory nitrate reduction to ammonium (DNRA) using sediment slurry incubations with 15 N labeled ammonium or nitrate tracers under oxic headspace (20% oxygen / 80% helium). Nitrification and denitrification rates were more than ten-fold higher in fertilized plots compared to control plots. By contrast, DNRA, which retains N in the system, was high in control plots but not detected in fertilized plots. The relative contribution of DNRA to total nitrate reduction largely depends on the carbon/nitrate ratio in the sediment. These results suggest that long-term fertilization shifts N cycling in Salt Marsh sediments from predominantly retention to removal. Long-term fertilization alters the relative importance of nitrate reduction pathways in Salt Marsh sediments: NO 3 - reduction in Salt Marsh sediments (PDF Download Available). Available from: https://www.researchgate.net/publication/305480944_Long-term_fertilization_alters_the_relative_importance_of_nitrate_reduction_pathways_in_Salt_Marsh_sediments_NO_3_-_reduction_in_Salt_Marsh_sediments [accessed Jun 6, 2017].
