Science.gov

Sample records for salt marsh ecosystem

  1. Salt Marsh--Estuarine Ecosystem: A Liquid Asset

    ERIC Educational Resources Information Center

    Steever, E. Zell

    1977-01-01

    A comprehensive description of the salt marsh-estuarine ecosystem is provided. Topics discussed include: the general geologic history and formation of this ecosystem; physical and chemical parameters; variety; primary productivity; tidal zones; kind, sizes and abundance of vegetation; and the environmental factors influencing vegetation. (BT)

  2. Soil Carbon Stocks in a Shifting Ecosystem; Climate Induced Migration of Mangroves into Salt Marsh

    NASA Astrophysics Data System (ADS)

    Simpson, L.; Osborne, T.; Feller, I. C.

    2015-12-01

    Across the globe, coastal wetland vegetation distributions are changing in response to climate change. The increase in global average surface temperature has already caused shifts in the structure and distribution of many ecological communities. In parts of the southeastern United States, increased winter temperatures have resulted in the poleward range expansion of mangroves at the expense of salt marsh habitat. Our work aims to document carbon storage in the salt marsh - mangrove ecotone and any potential changes in this reservoir that may ensue due to the shifting range of this habitat. Differences in SOM and C stocks along a latitudinal gradient on the east coast of Florida will be presented. The gradient studied spans 342 km and includes pure mangrove habitat, the salt marsh - mangrove ecotone, and pure salt marsh habitat.This latitudinal gradient gives us an exceptional opportunity to document and investigate ecosystem soil C modifications as mangroves transgress into salt marsh habitat due to climatic change.

  3. How do salt-marsh ecosystems respond to changes in the environmental forcings?

    NASA Astrophysics Data System (ADS)

    D'Alpaos, A.; Mudd, S. M.; Carniello, L.

    2012-04-01

    How do salt-marsh ecosystems respond to changes in the environmental forcings? This is a question of paramount importance due to the critical role exerted by salt-marsh ecosystems within the tidal landscape. Salt marshes in fact buffer coastlines against, filter nutrients and pollutants from tidal waters, provide nursery areas for coastal biota, and serve as a sink for organic carbon. Observations of marsh degradation worldwide and the acceleration in the rate of global sea level rise highlight the importance of improving our understanding of the chief processes controlling salt-marsh response to current natural climate changes and to the effects of changes in sediment supply. To address this important issue, we have applied a analytical model of biomorphodynamic evolution of salt-marsh ecosystems in the vertical plane, accounting for two-way interactions between ecological and geomorphological processes. Our results show that marshes are more resilient to a step decrease in the rate of relative sea level rise (RRSLR) rather than to a step increase of the same magnitude. However, marshes respond more rapidly to an increase in sediment load or vegetation productivity, rather than to a decrease (of the same amount) in sediment load or vegetation productivity. We also observe that marsh stability is therefore positively correlated with tidal range: marshes with high tidal ranges respond more slowly to changes in the environmental forcings and therefore are less likely to be affected by perturbations. Finally, the model suggests that, in the case of a oscillating RRSLR, marsh stratigraphy will be unable to fully record short-term fluctuations in relative mean sea level, whereas it will be able to capture long-term fluctuations particularly in sediment rich, microtidal settings.

  4. Use of structured decision making to identify monitoring variables and management priorities for salt marsh ecosystems

    USGS Publications Warehouse

    Neckles, Hilary A.; Lyons, James E.; Guntenspergen, Glenn R.; Shriver, W. Gregory; Adamowicz, Susan C.

    2015-01-01

    Most salt marshes in the USA have been degraded by human activities, and coastal managers are faced with complex choices among possible actions to restore or enhance ecosystem integrity. We applied structured decision making (SDM) to guide selection of monitoring variables and management priorities for salt marshes within the National Wildlife Refuge System in the northeastern USA. In general, SDM is a systematic process for decomposing a decision into its essential elements. We first engaged stakeholders in clarifying regional salt marsh decision problems, defining objectives and attributes to evaluate whether objectives are achieved, and developing a pool of alternative management actions for achieving objectives. Through this process, we identified salt marsh attributes that were applicable to monitoring National Wildlife Refuges on a regional scale and that targeted management needs. We then analyzed management decisions within three salt marsh units at Prime Hook National Wildlife Refuge, coastal Delaware, as a case example of prioritizing management alternatives. Values for salt marsh attributes were estimated from 2 years of baseline monitoring data and expert opinion. We used linear value modeling to aggregate multiple attributes into a single performance score for each alternative, constrained optimization to identify alternatives that maximized total management benefits subject to refuge-wide cost constraints, and used graphical analysis to identify the optimal set of alternatives for the refuge. SDM offers an efficient, transparent approach for integrating monitoring into management practice and improving the quality of management decisions.

  5. A trophic cascade triggers collapse of a salt-marsh ecosystem with intensive recreational fishing.

    PubMed

    Altieri, Andrew H; Bertness, Mark D; Coverdale, Tyler C; Herrmann, Nicholas C; Angelini, Christine

    2012-06-01

    Overexploitation of predators has been linked to the collapse of a growing number of shallow-water marine ecosystems. However, salt-marsh ecosystems are often viewed and managed as systems controlled by physical processes, despite recent evidence for herbivore-driven die-off of marsh vegetation. Here we use field observations, experiments, and historical records at 14 sites to examine whether the recently reported die-off of northwestern Atlantic salt marshes is associated with the cascading effects of predator dynamics and intensive recreational fishing activity. We found that the localized depletion of top predators at sites accessible to recreational anglers has triggered the proliferation of herbivorous crabs, which in turn results in runaway consumption of marsh vegetation. This suggests that overfishing may be a general mechanism underlying the consumer-driven die-off of salt marshes spreading throughout the western Atlantic. Our findings support the emerging realization that consumers play a dominant role in regulating marine plant communities and can lead to ecosystem collapse when their impacts are amplified by human activities, including recreational fishing.

  6. An invasive species facilitates the recovery of salt marsh ecosystems on Cape Cod.

    PubMed

    Bertness, Mark D; Coverdale, Tyler C

    2013-09-01

    With global increases in human impacts, invasive species have become a major threat to ecosystems worldwide. While they have been traditionally viewed as harmful, invasive species may facilitate the restoration of degraded ecosystems outside their native ranges. In New England (USA) overfishing has depleted salt marsh predators, allowing the herbivorous crab Sesarma reticulatum to denude hundreds of hectares of low marsh. Here, using multiple site surveys and field caging experiments, we show that the subsequent invasion of green crabs, Carcinus maenas, into heavily burrowed marshes partially reverses decades of cordgrass die-off. By consuming Sesarma, eliciting a nonlethal escape response, and evicting Sesarma from burrows, Carcinus reduces Sesarma herbivory and promotes cordgrass recovery. These results suggest that invasive species can contribute to restoring degraded ecosystems and underscores the potential for invasive species to return ecological functions lost to human impacts. PMID:24279265

  7. An invasive species facilitates the recovery of salt marsh ecosystems on Cape Cod.

    PubMed

    Bertness, Mark D; Coverdale, Tyler C

    2013-09-01

    With global increases in human impacts, invasive species have become a major threat to ecosystems worldwide. While they have been traditionally viewed as harmful, invasive species may facilitate the restoration of degraded ecosystems outside their native ranges. In New England (USA) overfishing has depleted salt marsh predators, allowing the herbivorous crab Sesarma reticulatum to denude hundreds of hectares of low marsh. Here, using multiple site surveys and field caging experiments, we show that the subsequent invasion of green crabs, Carcinus maenas, into heavily burrowed marshes partially reverses decades of cordgrass die-off. By consuming Sesarma, eliciting a nonlethal escape response, and evicting Sesarma from burrows, Carcinus reduces Sesarma herbivory and promotes cordgrass recovery. These results suggest that invasive species can contribute to restoring degraded ecosystems and underscores the potential for invasive species to return ecological functions lost to human impacts.

  8. Whole ecosystem estimates of carbon exchange and storage in a New England salt marsh

    NASA Astrophysics Data System (ADS)

    Forbrich, I.; Giblin, A.

    2013-12-01

    Salt marshes are wetlands situated at the interface of land and ocean. They are among the most productive ecosystems worldwide and store substantial amounts of carbon as peat. Their long-term stability is dependent on sediment accretion and carbon accumulation to avoid submergence when sea level is rising. Currently, estimates of carbon storage in salt marshes are uncertain because our understanding of the coupling between marsh plant productivity and carbon release to the adjacent ocean is limited. To evaluate the capacity to store carbon as well as the resilience of the ecosystem, long-term studies of carbon cycling considering both vertical and lateral fluxes are necessary. To study the net exchange between marsh and atmosphere, we chose the non-intrusive eddy covariance which allows nearly continuous half hourly flux measurements of net ecosystem exchange (NEE) on the ecosystem scale. Since spring 2012, we have been investigating the marsh-atmosphere exchange of carbon dioxide (CO2) at a Spartina patens high marsh at the Plum Island Ecosystems Long-Term Ecological Research site. Seasonal dynamics of CO2 exchange during summer were controlled by the phenology of S. patens. Preliminary estimates for seasonal carbon storage range from 185 to 228 g C m-2 (5/1/2012 to 10/31/2012). During the winter months we observed small fluxes, but carbon uptake still occurred during the day. We attribute this to microalgae productivity. Winter carbon release is estimated to be approximately 130 g C m-2 (12/6/2012 to 4/30/2013), when uptake by microalgae is not taken into account. This emphasizes the relevance of transitional and cold season carbon cycling for the carbon storage capacity of northern salt marshes, since a large proportion of fixed carbon is released during these periods. Direct tidal effects on the marsh-atmosphere carbon exchange are visible especially during monthly spring tides, when both daytime carbon uptake and night time respiration were reduced during

  9. Patterns in salt-marsh ecosystems: the role of biotic and abiotic forcings

    NASA Astrophysics Data System (ADS)

    D'Alpaos, A.; Marani, M.

    2010-12-01

    The dynamics of salt-marsh ecosystems are governed by interacting physical and biological processes, whose intertwined feedbacks critically affect the evolution. Salt marshes are characterised by complex patterns, both in their geomorphic and biological features, arising through the elaboration of a network structure driven by the tidal forcing and through the interaction between hydrodynamical, geophysical, and biological components. The complexity observed in tidal geomorphological patterns is deemed to arise from the mutual influence of biotic and abiotic components. The results from a 2D numerical model, accounting for biotic and geomorphic processes, show that the average marsh elevation within the tidal frame decreases with increasing rates of sea-level rise, decreasing sediment availability, and decreasing vegetation productivity. The spatial variability in platform elevations and biomass distribution, increases with increasing rates of sea-level rise, increasing sediment availability, and decreasing vegetation productivity. Supply-limited settings tend to develop uniform marsh surface elevations and biomass distribution, whereas supply-rich settings tend to develop sedimentation patterns characterized by large heterogeneities. Our analyses also suggest that the fate of tidal landforms and their possible geomorphological restoration should be addressed through approaches which explicitly incorporate bio-morphodynamic processes.

  10. The mutual influence of biotic and abiotic components on the long-term ecomorphodynamic evolution of salt-marsh ecosystems

    NASA Astrophysics Data System (ADS)

    D'Alpaos, Andrea

    2011-03-01

    Salt marshes are coastal ecosystems characterized by high biodiversity and rates of primary productivity, providing fundamental ecosystem services. Salt-marsh ecosystems are important indicators of environmental change as the dynamics are governed by interacting physical and biological processes, whose intertwined feedbacks critically affect the evolution. Settling deposition of inorganic sediment allows the platform to reach a threshold elevation for vegetation encroachment; the presence of vegetation then intensifies rates of accretion, thus, enhancing the resilience of marshes to increasing rates of sea level rise (SLR). The results from a two-dimensional numerical model, accounting for biotic and geomorphic processes, show that different morphological evolutionary regimes are followed depending on marsh biological processes. The average marsh elevation within the tidal frame decreases with increasing rates of SLR, decreasing availability of sediment, and decreasing productivity of vegetation. The spatial variability in platform elevations increases with increasing rates of SLR, increasing availability of sediment, and decreasing productivity of vegetation. Supply-limited settings tend to develop uniform marsh surface elevations, whereas supply-rich settings tend to develop patterns of sedimentation where large heterogeneities in marsh surface elevations occur. The complexity observed in tidal geomorphological patterns is deemed to arise from the mutual influence of biotic and abiotic components. The fate of tidal landforms and their possible geomorphological restoration should, thus, be addressed through approaches which explicitly incorporate bio-morphodynamic processes.

  11. Reconstructing the Genetic Potential of the Microbially-Mediated Nitrogen Cycle in a Salt Marsh Ecosystem

    PubMed Central

    Dini-Andreote, Francisco; Brossi, Maria Julia de L.; van Elsas, Jan Dirk; Salles, Joana F.

    2016-01-01

    Coastal ecosystems are considered buffer zones for the discharge of land-derived nutrients without accounting for potential negative side effects. Hence, there is an urgent need to better understand the ecological assembly and dynamics of the microorganisms that are involved in nitrogen (N) cycling in such systems. Here, we employed two complementary methodological approaches (i.e., shotgun metagenomics and quantitative PCR) to examine the distribution and abundance of selected microbial genes involved in N transformations. We used soil samples collected along a well-established pristine salt marsh soil chronosequence that spans over a century of ecosystem development at the island of Schiermonnikoog, The Netherlands. Across the examined soil successional stages, the structure of the populations of genes involved in N cycling processes was strongly related to (shifts in the) soil nitrogen levels (i.e., NO3−, NH4+), salinity and pH (explaining 73.8% of the total variation, R2 = 0.71). Quantification of the genes used as proxies for N fixation, nitrification and denitrification revealed clear successional signatures that corroborated the taxonomic assignments obtained by metagenomics. Notably, we found strong evidence for niche partitioning, as revealed by the abundance and distribution of marker genes for nitrification (ammonia-oxidizing bacteria and archaea) and denitrification (nitrite reductase nirK, nirS and nitrous oxide reductase nosZ clades I and II). This was supported by a distinct correlation between these genes and soil physico-chemical properties, such as soil physical structure, pH, salinity, organic matter, total N, NO3−, NH4+ and SO42−, across four seasonal samplings. Overall, this study sheds light on the successional trajectories of microbial N cycle genes along a naturally developing salt marsh ecosystem. The data obtained serve as a foundation to guide the formulation of ecological models that aim to effectively monitor and manage pristine

  12. Reconstructing the Genetic Potential of the Microbially-Mediated Nitrogen Cycle in a Salt Marsh Ecosystem.

    PubMed

    Dini-Andreote, Francisco; Brossi, Maria Julia de L; van Elsas, Jan Dirk; Salles, Joana F

    2016-01-01

    Coastal ecosystems are considered buffer zones for the discharge of land-derived nutrients without accounting for potential negative side effects. Hence, there is an urgent need to better understand the ecological assembly and dynamics of the microorganisms that are involved in nitrogen (N) cycling in such systems. Here, we employed two complementary methodological approaches (i.e., shotgun metagenomics and quantitative PCR) to examine the distribution and abundance of selected microbial genes involved in N transformations. We used soil samples collected along a well-established pristine salt marsh soil chronosequence that spans over a century of ecosystem development at the island of Schiermonnikoog, The Netherlands. Across the examined soil successional stages, the structure of the populations of genes involved in N cycling processes was strongly related to (shifts in the) soil nitrogen levels (i.e., [Formula: see text], [Formula: see text]), salinity and pH (explaining 73.8% of the total variation, R (2) = 0.71). Quantification of the genes used as proxies for N fixation, nitrification and denitrification revealed clear successional signatures that corroborated the taxonomic assignments obtained by metagenomics. Notably, we found strong evidence for niche partitioning, as revealed by the abundance and distribution of marker genes for nitrification (ammonia-oxidizing bacteria and archaea) and denitrification (nitrite reductase nirK, nirS and nitrous oxide reductase nosZ clades I and II). This was supported by a distinct correlation between these genes and soil physico-chemical properties, such as soil physical structure, pH, salinity, organic matter, total N, [Formula: see text], [Formula: see text] and [Formula: see text], across four seasonal samplings. Overall, this study sheds light on the successional trajectories of microbial N cycle genes along a naturally developing salt marsh ecosystem. The data obtained serve as a foundation to guide the formulation of

  13. Reconstructing the Genetic Potential of the Microbially-Mediated Nitrogen Cycle in a Salt Marsh Ecosystem.

    PubMed

    Dini-Andreote, Francisco; Brossi, Maria Julia de L; van Elsas, Jan Dirk; Salles, Joana F

    2016-01-01

    Coastal ecosystems are considered buffer zones for the discharge of land-derived nutrients without accounting for potential negative side effects. Hence, there is an urgent need to better understand the ecological assembly and dynamics of the microorganisms that are involved in nitrogen (N) cycling in such systems. Here, we employed two complementary methodological approaches (i.e., shotgun metagenomics and quantitative PCR) to examine the distribution and abundance of selected microbial genes involved in N transformations. We used soil samples collected along a well-established pristine salt marsh soil chronosequence that spans over a century of ecosystem development at the island of Schiermonnikoog, The Netherlands. Across the examined soil successional stages, the structure of the populations of genes involved in N cycling processes was strongly related to (shifts in the) soil nitrogen levels (i.e., [Formula: see text], [Formula: see text]), salinity and pH (explaining 73.8% of the total variation, R (2) = 0.71). Quantification of the genes used as proxies for N fixation, nitrification and denitrification revealed clear successional signatures that corroborated the taxonomic assignments obtained by metagenomics. Notably, we found strong evidence for niche partitioning, as revealed by the abundance and distribution of marker genes for nitrification (ammonia-oxidizing bacteria and archaea) and denitrification (nitrite reductase nirK, nirS and nitrous oxide reductase nosZ clades I and II). This was supported by a distinct correlation between these genes and soil physico-chemical properties, such as soil physical structure, pH, salinity, organic matter, total N, [Formula: see text], [Formula: see text] and [Formula: see text], across four seasonal samplings. Overall, this study sheds light on the successional trajectories of microbial N cycle genes along a naturally developing salt marsh ecosystem. The data obtained serve as a foundation to guide the formulation of

  14. DEVELOPING INDICATORS OF SALT MARSH HEALTH

    EPA Science Inventory

    We relate plant zonation in salt marshes to key ecosystem services such as erosion control and wildlife habitat. Ten salt marshes in Narragansett Bay, with similar geological bedrock and sea exchange, were identified to examine plant zonation. Sub-watersheds adjacent to the salt ...

  15. Salt marsh ecosystem biogeochemical responses to nutrient enrichment: a paired 15N tracer study.

    PubMed

    Drake, D C; Peterson, Bruce J; Galván, Kari A; Deegan, Linda A; Hopkinson, Charles; Johnson, J Michael; Koop-Jakobsen, K; Lemay, Lynsey E; Picard, Christian

    2009-09-01

    We compared processing and fate of dissolved NO3- in two New England salt marsh ecosystems, one receiving natural flood tide concentrations of approximately 1-4 micromol NO3-/ L and the other receiving experimentally fertilized flood tides containing approximately 70-100 micromol NO3-/ L. We conducted simultaneous 15NO3- (isotope) tracer additions from 23 to 28 July 2005 in the reference (8.4 ha) and fertilized (12.4 ha) systems to compare N dynamics and fate. Two full tidal cycles were intensively studied during the paired tracer additions. Resulting mass balances showed that essentially 100% (0.48-0.61 mol NO3-N.ha(-1).h(-1)) of incoming NO3- was assimilated, dissimilated, sorbed, or sedimented (processed) within a few hours in the reference system when NO3- concentrations were 1.3-1.8 micromol/L. In contrast, only 50-60% of incoming NO3- was processed in the fertilized system when NO3- concentrations were 84-96 micromol/L; the remainder was exported in ebb tidewater. Gross NO3- processing was approximately 40 times higher in the fertilized system at 19.34-24.67 mol NO3-N.ha(-1).h(-1). Dissimilatory nitrate reduction to ammonium was evident in both systems during the first 48 h of the tracer additions but <1% of incoming 15NO3- was exported as 15NH4+. Nitrification rates calculated by 15NO3- dilution were 6.05 and 4.46 mol.ha(-1).h(-1) in the fertilized system but could not be accurately calculated in the reference system due to rapid (<4 h) NO3- turnover. Over the five-day paired tracer addition, sediments sequestered a small fraction of incoming NO3-, although the efficiency of sequestration was 3.8% in the reference system and 0.7% in the fertilized system. Gross sediment N sequestration rates were similar at 13.5 and 12.6 mol.ha(-1).d(-1), respectively. Macrophyte NO3- uptake efficiency, based on tracer incorporation in aboveground tissues, was considerably higher in the reference system (16.8%) than the fertilized system (2.6%), although bulk uptake of NO3

  16. Experimental restoration of a salt marsh with some comments on ecological restoration of coastal vegetated ecosystems in Korea

    NASA Astrophysics Data System (ADS)

    Koo, Bon Joo; Je, Jong Geel; Woo, Han Jun

    2011-03-01

    Since the 1980s, the coastal wetlands in Korea have been rapidly degraded and destroyed mainly due to reclamation and landfills for coastal development. In order to recover damaged coastal environments and to develop wetland restoration technologies, a 4-year study on ecological the restoration of coastal vegetated ecosystems was started in 1998. As one of a series of studies, a small-scale experiment on salt marsh restoration was carried out from April 2000 to August 2001. The experiment was designed to find effective means of ecological restoration through a comparison of the changes in environmental components and species structure between two different experimental plots created using sediment fences, one with and one without small canals. Temporal variation in surface elevation, sedimentary facies, and benthic species were measured seasonally in each plot and in the adjacent natural reference sites. Monthly exposure occurred from 330 cm to mean sea level, which represents the critical tidal level (CTL) at which salt marsh plants colonize. Vegetation, especially Suaeda japonica, colonized the site the following spring and recovered to a similar extent in the natural marshes 16 months later. The sedimentary results indicated that the sediment fences had effects on particle size and sediment accumulation, especially in the plot with small canals. This experiment also showed that tidal height, especially that exceeding the CTL, is an important factor in the recovery of the benthic fauna of salt marshes. From these results, we suggested that designs for the restoration of salt marsh ecosystems must consider the inclusion of a tidal height exceeding CTL, as this may allow reconstruction of the previous natural ecosystem without artificial transplanting.

  17. Hemigrapsus sanguineus in Long Island salt marshes: experimental evaluation of the interactions between an invasive crab and resident ecosystem engineers.

    PubMed

    Peterson, Bradley J; Fournier, Alexa M; Furman, Bradley T; Carroll, John M

    2014-01-01

    The invasive Asian shore crab, Hemigrapsus sanguineus, has recently been observed occupying salt marshes, a novel environment for this crab species. As it invades this new habitat, it is likely to interact with a number of important salt marsh species. To understand the potential effects of H. sanguineus on this ecosystem, interactions between this invasive crab and important salt marsh ecosystem engineers were examined. Laboratory experiments demonstrated competition for burrows between H. sanguineus and the native fiddler crab, Uca pugilator. Results indicate that H. sanguineus is able to displace an established fiddler crab from its burrow. Feeding experiments revealed that the presence of H. sanguineus has a significantly negative impact on the number as well as the biomass of ribbed mussels (Geukensia demissa) consumed by the green crab, Carcinus maenas, although this only occurred at high predator densities. In addition, when both crabs foraged together, there was a significant shift in the size of mussels consumed. These interactions suggests that H. sanguineus may have long-term impacts and wide-ranging negative effects on the saltmarsh ecosystem.

  18. Hemigrapsus sanguineus in Long Island salt marshes: experimental evaluation of the interactions between an invasive crab and resident ecosystem engineers

    PubMed Central

    Fournier, Alexa M.; Furman, Bradley T.; Carroll, John M.

    2014-01-01

    The invasive Asian shore crab, Hemigrapsus sanguineus, has recently been observed occupying salt marshes, a novel environment for this crab species. As it invades this new habitat, it is likely to interact with a number of important salt marsh species. To understand the potential effects of H. sanguineus on this ecosystem, interactions between this invasive crab and important salt marsh ecosystem engineers were examined. Laboratory experiments demonstrated competition for burrows between H. sanguineus and the native fiddler crab, Uca pugilator. Results indicate that H. sanguineus is able to displace an established fiddler crab from its burrow. Feeding experiments revealed that the presence of H. sanguineus has a significantly negative impact on the number as well as the biomass of ribbed mussels (Geukensia demissa) consumed by the green crab, Carcinus maenas, although this only occurred at high predator densities. In addition, when both crabs foraged together, there was a significant shift in the size of mussels consumed. These interactions suggests that H. sanguineus may have long-term impacts and wide-ranging negative effects on the saltmarsh ecosystem. PMID:25071995

  19. Hemigrapsus sanguineus in Long Island salt marshes: experimental evaluation of the interactions between an invasive crab and resident ecosystem engineers.

    PubMed

    Peterson, Bradley J; Fournier, Alexa M; Furman, Bradley T; Carroll, John M

    2014-01-01

    The invasive Asian shore crab, Hemigrapsus sanguineus, has recently been observed occupying salt marshes, a novel environment for this crab species. As it invades this new habitat, it is likely to interact with a number of important salt marsh species. To understand the potential effects of H. sanguineus on this ecosystem, interactions between this invasive crab and important salt marsh ecosystem engineers were examined. Laboratory experiments demonstrated competition for burrows between H. sanguineus and the native fiddler crab, Uca pugilator. Results indicate that H. sanguineus is able to displace an established fiddler crab from its burrow. Feeding experiments revealed that the presence of H. sanguineus has a significantly negative impact on the number as well as the biomass of ribbed mussels (Geukensia demissa) consumed by the green crab, Carcinus maenas, although this only occurred at high predator densities. In addition, when both crabs foraged together, there was a significant shift in the size of mussels consumed. These interactions suggests that H. sanguineus may have long-term impacts and wide-ranging negative effects on the saltmarsh ecosystem. PMID:25071995

  20. Flax pond ecosystem study: exchanges of CO/sub 2/ between a salt marsh and the atmosphere

    SciTech Connect

    Houghton, R.A.; Woodwell, G.M.

    1980-12-01

    Profiles of CO/sub 2/ concentration, windspeed, and temperature were used in the aerodynamic flux technique to calculate the CO/sub 2/ exchange between a Long Island salt marsh and the atmosphere. Uptake of CO/sub 2/ by the marsh during hours of sunlight and release during the night occurred during all times of the year. The rates of CO/sub 2/ exchange were highest during midsummer, 2.3 g CO/sub 2/.m/sup -2/.h/sup -1/ averaged over the daylight hours of July, and 1.3 g CO/sub 2/.m/sup -2/.h/sup -1/ for both uptake and release. The net 24-h exchange rates followed Spartina growth and senescence during the summer and fall, and photosynthesis of benthic algae during late winter and spring. There was a net uptake of Co/sub 2/ over 24 h by the marsh during all seasons except autumn. The net annual flow of carbon was from the atmosphere to Flax Pond (approx. = 300 g C.m/sup -2/.yr/sup -1/ averaged over the entire marsh ecosystem). This flux was larger than the net exchange of carbon between the marsh and either uplands, sediments, or coastal waters. The net uptake of CO/sub 2/ during summer was less than the net productivity of the vascular plants, indicating that some of the CO/sub 2/ assimilated by the plants came from heterotrophic respiration within the marsh. Nevertheless, respiration by the plants was by far the largest source of CO/sub 2/ from the marsh surface. Nighttime respiration of the ecosystem released a total of approx. = 510 g C.m/sup -2/.yr/sup -1/ to the atmosphere.

  1. TOWARDS DEVELOPING INDICATORS OF SALT MARSH CONDITION

    EPA Science Inventory

    Five ecosystem services: water quality maintenance, erosion and flood control, recreation and cultural use, wildlife habitat, and food production were identified from the literature as key services to characterize salt marshes of high integrity. We describe a systems approach to ...

  2. Oregon Salt Marshes: How Blue are They?

    EPA Science Inventory

    Two important ecosystem services of wetlands are carbon sequestration and filtration of nutrients and particulates. We quantified the carbon and nitrogen accumulation rates in salt marshes at 135 plots distributed across eight estuaries located in Oregon, USA. Net carbon and ...

  3. Tidal pumping as a driver of groundwater discharge to a back barrier salt marsh ecosystem

    NASA Astrophysics Data System (ADS)

    Carter, M. L.; Viso, R. F.; Peterson, R. N.; Hill, J. C.

    2013-12-01

    Submarine groundwater discharge (SGD) typically consists of both terrestrial groundwater and recirculated seawater and has been shown to be a significant pathway of dissolved substances to the coastal zone. The fresh and saline water mixture in the subsurface creates a salinity gradient that can impact biogeochemical processes. Located along the South Atlantic Bight, Georgia's coastline is an approximately 100-mile stretch of complex primary and secondary barrier islands resulting from geologic interactions driven by long-term sea level rise and retreat, accretion, seasonal tidal events, storm overwash, and wave driven erosion. Our study site is located in the Duplin River near Sapelo Island, GA and is part of the Georgia Coastal Ecosystems Long Term Ecosystem Research (GCE-LTER) program. This area is considered mesotidal (2-4m) and tidal pumping may be a dominating process in controlling SGD rates. The Duplin River is connected to the Atlantic Ocean through Doboy Sound to the south. To the north, the river terminates in extensive salt marsh and therefore has no overland freshwater input. Previous studies show a salinity gradient within the Duplin River indicating that SGD must be present as a source of brackish water. To place constraints on SGD processes, we employ a combination of geochemical and geophysical techniques to determine the magnitude of SGD in the Duplin River. Together these techniques permit a more complete understanding of the groundwater system. Three time series stations at the upper, mid and lower reaches of the Duplin River were deployed in June of 2013 to measure groundwater influences during daily and fortnightly tidal cycles. At each station, continuous radon-222 measurements were conducted at 30 minute intervals along with measurements of water level, temperature and conductivity using standard hydrological data loggers. During this period, eight time series resistivity profiles using a 56 electrode (110m long) cable were recorded to

  4. Responses of salt marsh ecosystems to mosquito control management practices along the Atlantic Coast (U.S.A.)

    USGS Publications Warehouse

    James-Pirri, Mary-Jane; Erwin, R. Michael; Prosser, Diann J.; Taylor, Janith D.

    2012-01-01

    Open marsh water management (OMWM) of salt marshes modifies grid-ditched marshes by creating permanent ponds and radial ditches in the high marsh that reduce mosquito production and enhance fish predation on mosquitoes. It is preferable to using pesticides to control salt marsh mosquito production and is commonly presented as a restoration or habitat enhancement tool for grid-ditched salt marshes. Monitoring of nekton, vegetation, groundwater level, soil salinity, and bird communities before and after OMWM at 11 (six treatment and five reference sites) Atlantic Coast (U.S.A.) salt marshes revealed high variability within and among differing OMWM techniques (ditch-plugging, reengineering of sill ditches, and the creation of ponds and radial ditches). At three marshes, the dominant nekton shifted from fish (primarily Fundulidae species) to shrimp (Palaemonidae species) after manipulations and shrimp density increased at other treatment sites. Vegetation changed at only two sites, one with construction equipment impacts (not desired) and one with a decrease in woody vegetation along existing ditches (desired). One marsh had lower groundwater level and soil salinity, and bird use, although variable, was often unrelated to OMWM manipulations. The potential effects of OMWM manipulations on non-target salt marsh resources need to be carefully considered by resource planners when managing marshes for mosquito control.

  5. Consumer control of salt marshes driven by human disturbance.

    PubMed

    Bertness, Mark D; Silliman, Brian R

    2008-06-01

    Salt marsh ecosystems are widely considered to be controlled exclusively by bottom-up forces, but there is mounting evidence that human disturbances are triggering consumer control in western Atlantic salt marshes, often with catastrophic consequences. In other marine ecosystems, human disturbances routinely dampen (e.g., coral reefs, sea grass beds) and strengthen (e.g., kelps) consumer control, but current marsh theory predicts little potential interaction between humans and marsh consumers. Thus, human modification of top-down control in salt marshes was not anticipated and was even discounted in current marsh theory, despite loud warnings about the potential for cascading human impacts from work in other marine ecosystems. In spite of recent experiments that have challenged established marsh dogma and demonstrated consumer-driven die-off of salt marsh ecosystems, government agencies and nongovernmental organizations continue to manage marsh die-offs under the old theoretical framework and only consider bottom-up forces as causal agents. This intellectual dependency of many coastal ecologists and managers on system-specific theory (i.e., marsh bottom-up theory) has the potential to have grave repercussions for coastal ecosystem management and conservation in the face of increasing human threats. We stress that marine vascular plant communities (salt marshes, sea grass beds, mangroves) are likely more vulnerable to runaway grazing and consumer-driven collapse than is currently recognized by theory, particularly in low-diversity ecosystems like Atlantic salt marshes. PMID:18577090

  6. Consumer control of salt marshes driven by human disturbance.

    PubMed

    Bertness, Mark D; Silliman, Brian R

    2008-06-01

    Salt marsh ecosystems are widely considered to be controlled exclusively by bottom-up forces, but there is mounting evidence that human disturbances are triggering consumer control in western Atlantic salt marshes, often with catastrophic consequences. In other marine ecosystems, human disturbances routinely dampen (e.g., coral reefs, sea grass beds) and strengthen (e.g., kelps) consumer control, but current marsh theory predicts little potential interaction between humans and marsh consumers. Thus, human modification of top-down control in salt marshes was not anticipated and was even discounted in current marsh theory, despite loud warnings about the potential for cascading human impacts from work in other marine ecosystems. In spite of recent experiments that have challenged established marsh dogma and demonstrated consumer-driven die-off of salt marsh ecosystems, government agencies and nongovernmental organizations continue to manage marsh die-offs under the old theoretical framework and only consider bottom-up forces as causal agents. This intellectual dependency of many coastal ecologists and managers on system-specific theory (i.e., marsh bottom-up theory) has the potential to have grave repercussions for coastal ecosystem management and conservation in the face of increasing human threats. We stress that marine vascular plant communities (salt marshes, sea grass beds, mangroves) are likely more vulnerable to runaway grazing and consumer-driven collapse than is currently recognized by theory, particularly in low-diversity ecosystems like Atlantic salt marshes.

  7. Interactions between plant traits and sediment characteristics influencing species establishment and scale-dependent feedbacks in salt marsh ecosystems

    NASA Astrophysics Data System (ADS)

    Schwarz, C.; Bouma, T. J.; Zhang, L. Q.; Temmerman, S.; Ysebaert, T.; Herman, P. M. J.

    2015-12-01

    The importance of ecosystem engineering and biogeomorphic processes in shaping many aquatic and semi-aquatic landscapes is increasingly acknowledged. Ecosystem engineering and biogeomorphic landscape formation involves two critical processes: (1) species establishment, and (2) scale-dependent feedbacks, meaning that organisms improve their living conditions on a local scale but at the same time worsen them at larger scales. However, the influence of organism traits in combination with physical factors (e.g. hydrodynamics, sediments) on early establishment and successive development due to scale-dependent feedbacks is still unclear. As a model system, this was tested for salt marsh pioneer plants by conducting flume experiments: i) on the influence of species-specific traits (such as stiffness) of two contrasting dominant pioneer species (Spartina alterniflora and Scirpus mariqueter) to withstand current-induced stress during establishment; and ii) to study the impact of species-specific traits (stiffness) and physical forcing (water level, current stress) on the large-scale negative feedback at established tussocks (induced scour at tussock edges) of the two model species. The results indicate that, not only do species-specific plant traits, such as stiffness, exert a major control on species establishment thresholds, but also potentially physiologically triggered plant properties, such as adapted root morphology due to sediment properties. Moreover, the results show a clear relation between species-specific plant traits, abiotics (i.e. sediment, currents) and the magnitude of the large-scale negative scale-dependent feedback. These findings suggest that the ecosystem engineering ability, resulting from physical plant properties can be disadvantageous for plant survival through promoted dislodgement (stem stiffness increases the amount of drag experienced at the root system), underlying the importance of scale-dependent feedbacks on landscape development.

  8. Exotic Spartina alterniflora invasion alters ecosystem-atmosphere exchange of CH4 and N2O and carbon sequestration in a coastal salt marsh in China.

    PubMed

    Yuan, Junji; Ding, Weixin; Liu, Deyan; Kang, Hojeong; Freeman, Chris; Xiang, Jian; Lin, Yongxin

    2015-04-01

    Coastal salt marshes are sensitive to global climate change and may play an important role in mitigating global warming. To evaluate the impacts of Spartina alterniflora invasion on global warming potential (GWP) in Chinese coastal areas, we measured CH4 and N2O fluxes and soil organic carbon sequestration rates along a transect of coastal wetlands in Jiangsu province, China, including open water; bare tidal flat; and invasive S. alterniflora, native Suaeda salsa, and Phragmites australis marshes. Annual CH4 emissions were estimated as 2.81, 4.16, 4.88, 10.79, and 16.98 kg CH4 ha(-1) for open water, bare tidal flat, and P. australis, S. salsa, and S. alterniflora marshes, respectively, indicating that S. alterniflora invasion increased CH4 emissions by 57-505%. In contrast, negative N2O fluxes were found to be significantly and negatively correlated (P < 0.001) with net ecosystem CO2 exchange during the growing season in S. alterniflora and P. australis marshes. Annual N2O emissions were 0.24, 0.38, and 0.56 kg N2O ha(-1) in open water, bare tidal flat and S. salsa marsh, respectively, compared with -0.51 kg N2O ha(-1) for S. alterniflora marsh and -0.25 kg N2O ha(-1) for P. australis marsh. The carbon sequestration rate of S. alterniflora marsh amounted to 3.16 Mg C ha(-1) yr(-1) in the top 100 cm soil profile, a value that was 2.63- to 8.78-fold higher than in native plant marshes. The estimated GWP was 1.78, -0.60, -4.09, and -1.14 Mg CO2 eq ha(-1) yr(-1) in open water, bare tidal flat, P. australis marsh and S. salsa marsh, respectively, but dropped to -11.30 Mg CO2 eq ha(-1) yr(-1) in S. alterniflora marsh. Our results indicate that although S. alterniflora invasion stimulates CH4 emissions, it can efficiently mitigate increases in atmospheric CO2 and N2O along the coast of China.

  9. Exotic Spartina alterniflora invasion alters ecosystem-atmosphere exchange of CH4 and N2O and carbon sequestration in a coastal salt marsh in China.

    PubMed

    Yuan, Junji; Ding, Weixin; Liu, Deyan; Kang, Hojeong; Freeman, Chris; Xiang, Jian; Lin, Yongxin

    2015-04-01

    Coastal salt marshes are sensitive to global climate change and may play an important role in mitigating global warming. To evaluate the impacts of Spartina alterniflora invasion on global warming potential (GWP) in Chinese coastal areas, we measured CH4 and N2O fluxes and soil organic carbon sequestration rates along a transect of coastal wetlands in Jiangsu province, China, including open water; bare tidal flat; and invasive S. alterniflora, native Suaeda salsa, and Phragmites australis marshes. Annual CH4 emissions were estimated as 2.81, 4.16, 4.88, 10.79, and 16.98 kg CH4 ha(-1) for open water, bare tidal flat, and P. australis, S. salsa, and S. alterniflora marshes, respectively, indicating that S. alterniflora invasion increased CH4 emissions by 57-505%. In contrast, negative N2O fluxes were found to be significantly and negatively correlated (P < 0.001) with net ecosystem CO2 exchange during the growing season in S. alterniflora and P. australis marshes. Annual N2O emissions were 0.24, 0.38, and 0.56 kg N2O ha(-1) in open water, bare tidal flat and S. salsa marsh, respectively, compared with -0.51 kg N2O ha(-1) for S. alterniflora marsh and -0.25 kg N2O ha(-1) for P. australis marsh. The carbon sequestration rate of S. alterniflora marsh amounted to 3.16 Mg C ha(-1) yr(-1) in the top 100 cm soil profile, a value that was 2.63- to 8.78-fold higher than in native plant marshes. The estimated GWP was 1.78, -0.60, -4.09, and -1.14 Mg CO2 eq ha(-1) yr(-1) in open water, bare tidal flat, P. australis marsh and S. salsa marsh, respectively, but dropped to -11.30 Mg CO2 eq ha(-1) yr(-1) in S. alterniflora marsh. Our results indicate that although S. alterniflora invasion stimulates CH4 emissions, it can efficiently mitigate increases in atmospheric CO2 and N2O along the coast of China. PMID:25367159

  10. Nonlinear responses in salt marsh functioning to increased nitrogen addition.

    PubMed

    Vivanco, Lucía; Irvine, Irina C; Martiny, Jennifer B H

    2015-04-01

    Salt marshes provide storm protection to shorelines, sequester carbon (C), and mitigate coastal eutrophication. These valuable coastal ecosystems are confronted with increasing nitrogen (N) inputs from anthropogenic sources, such as agricultural runoff, wastewater, and atmospheric deposition. To inform predictions of salt marsh functioning and sustainability in the future, we characterized the response of a variety of plant, microbial, and sediment responses to a seven-level gradient of N addition in three Californian salt marshes after 7 and 14 months of N addition. The marshes showed variable responses to the experimental N gradient that can be grouped as neutral (root biomass, sediment respiration, potential carbon mineralization, and potential net nitrification), linear (increasing methane flux, decreasing potential net N mineralization, and increasing sediment inorganic N), and nonlinear (saturating aboveground plant biomass and leaf N content, and exponentially increasing sediment inorganic and organic N). The three salt marshes showed quantitative differences in most ecosystem properties and processes rates; however, the form of the response curves to N addition were generally consistent across the three marshes, indicating that the responses observed may be applicable to other marshes in the region. Only for sediment properties (inorganic and organic N pool) did the shape of the response differ significantly between marshes. Overall, the study suggests salt marshes are limited in their ability to sequester C and N with future increases in N, even without further losses in marsh area. PMID:26230015

  11. Plant Zonation in a Salt Marsh.

    ERIC Educational Resources Information Center

    Etri, Lawrence R.

    1978-01-01

    The zonation of plants within a salt marsh environment is detailed via illustrations and scientific nomeclature for purposes of encouraging outdoor educators to use the salt marsh environment as a learning laboratory. (JC)

  12. Ecogeomorphic Heterogeneity Sculpts Salt Marshes

    NASA Astrophysics Data System (ADS)

    Leonardi, N.; Fagherazzi, S.

    2014-12-01

    state for marsh boundaries, which would make the prediction of failure events impossible. Internal physical processes allowing salt marshes to reach self-organized criticality are geotechnical, biological, and related to the non-homogeneity of salt marshes whose material discontinuities act as stress raisers.

  13. Coastal eutrophication as a driver of salt marsh loss.

    PubMed

    Deegan, Linda A; Johnson, David Samuel; Warren, R Scott; Peterson, Bruce J; Fleeger, John W; Fagherazzi, Sergio; Wollheim, Wilfred M

    2012-10-18

    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 decades. Here we present data from a nine-year whole-ecosystem nutrient-enrichment experiment. Our study demonstrates that nutrient enrichment, a global problem for coastal ecosystems, 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 creeks. 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. PMID:23075989

  14. NITRATE RELEASE BY SALT MARSH PLANTS: AN OVERLOOKED NUTRIENT FLUX MECHANISM

    EPA Science Inventory

    Salt marshes provide water purification as an important ecosystem service in part by storing, transforming and releasing nutrients. This service can be quantified by measuring nutrient fluxes between marshes and surface waters. Many processes drive these fluxes, including photosy...

  15. Experimental predator removal causes rapid salt marsh die-off.

    PubMed

    Bertness, Mark D; Brisson, Caitlin P; Coverdale, Tyler C; Bevil, Matt C; Crotty, Sinead M; Suglia, Elena R

    2014-07-01

    Salt marsh habitat loss to vegetation die-offs has accelerated throughout the western Atlantic in the last four decades. Recent studies have suggested that eutrophication, pollution and/or disease may contribute to the loss of marsh habitat. In light of recent evidence that predators are important determinants of marsh health in New England, we performed a total predator exclusion experiment. Here, we provide the first experimental evidence that predator depletion can cause salt marsh die-off by releasing the herbivorous crab Sesarma reticulatum from predator control. Excluding predators from a marsh ecosystem for a single growing season resulted in a >100% increase in herbivory and a >150% increase in unvegetated bare space compared to plots with predators. Our results confirm that marshes in this region face multiple, potentially synergistic threats.

  16. Carbon accumulation in Bay of Fundy salt marshes: Implications for restoration of reclaimed marshes

    NASA Astrophysics Data System (ADS)

    Connor, Richard F.; Chmura, Gail L.; Beecher, C. Beth

    2001-12-01

    Transformation of agricultural land to natural terrestrial vegetation has been suggested as a means to increase soil carbon storage. However, the capacity for carbon storage in terrestrial soils is limited as compared to soils of tidal salt marshes, the original vegetation of many coastal agricultural lands. In a number of countries, tidal salt marshes have been "reclaimed," that is drained and diked to prevent tidal flooding and create suitable conditions for dry land agriculture. In this study we examine spatial and temporal patterns of carbon accumulation in tidal salt marshes of the Bay of Fundy and estimate the carbon storage potential of the bay's extensive area of reclaimed marsh. Rates of carbon accumulation vary from the upper to the outer Bay, over which there is a gradient of decreasing tidal range and suspended sediment supply. In the outer bay, high-marsh densities are highest (0.042 ± 0.009 g C cm-3), but carbon accumulation rates over the past 30 years are lowest (76 g C m-2 yr-1). The reverse pattern occurs in the upper bay where carbon densities in the high-marsh environment are lowest (0.036 ± 0.002 g C cm-3), but carbon accumulation rates over the past 30 years may be as high (184 g C m-2 yr-1). Compared to other ecosystems, the rates of carbon accumulation presented in this study were similar over timescales of years to centuries. Increases in relative sea level (over time) and suspended sediment supply (across the bay) positively affect the marsh soil accumulation rate and the rate of carbon sequestration. Parameters such as %C are not useful predictors of a marsh's potential for carbon sequestration. Soil carbon densities of functioning marshes and reclaimed marsh soils are similar, but marsh soils have a storage capacity that increases with rising sea level, while agricultural soils, such as those in reclaimed marshes, have a fixed (or possibly decreasing in reclaimed marshes) volume over time.

  17. Persistence and movement of atrazine in a salt marsh sediment microecosystem

    SciTech Connect

    Isensee, A.R.

    1987-09-01

    Pesticides enter salt marshes in runoff from agricultural lands or through direct or near-by application. Concern has been raised that the tidal action in the salt marsh that functions to trap sediment and nutrients may also function to concentrate pesticides to harmful levels. Studies have been conducted to evaluate the effect of pesticides on representative species of salt marsh ecosystems. This paper describes the use of a modified salt marsh microecosystem to evaluate persistence and movement of atrazine in salt marsh sediment under simulated tidal flux and continuous flooding conditions. Atrazine persistence was also compared under normal field conditions.

  18. Synecology of a Virginia salt marsh

    USGS Publications Warehouse

    Kerwin, J.A.; Pedigo, R.

    1971-01-01

    In the spring and summer of 1964 a salt marsh in Gloucester County, Virginia, was analyzed using random quadrat sampling. Synthetic treatments were employed to evaluate data and were correlated with observed differences in elevation. Floristic data indicate the Virginia salt marshes show closer similarity to marshes north of Chesapeake Bay than those south of Chesapeake Bay. Correlation of floristic data with observed differences in elevation indicates that zonation in the marsh is dependent upon differences in elevation or some environmental factor correlated with elevation differences. Observations of sedimentation and erosion in localized areas indicate that the marsh is in a constant state of change, with extensive areas undergoing both succession and regression.

  19. Salt marsh vegetation promotes efficient tidal channel networks.

    PubMed

    Kearney, William S; Fagherazzi, Sergio

    2016-01-01

    Tidal channel networks mediate the exchange of water, nutrients and sediment between an estuary and marshes. Biology feeds back into channel morphodynamics through the influence of vegetation on both flow and the cohesive strength of channel banks. Determining how vegetation affects channel networks is essential in understanding the biological functioning of intertidal ecosystems and their ecosystem services. However, the processes that control the formation of an efficient tidal channel network remain unclear. Here we compare the channel networks of vegetated salt marshes in Massachusetts and the Venice Lagoon to unvegetated systems in the arid environments of the Gulf of California and Yemen. We find that the unvegetated systems are dissected by less efficient channel networks than the vegetated salt marshes. These differences in network geometry reflect differences in the branching and meandering of the channels in the network, characteristics that are related to the density of vegetation on the marsh. PMID:27430165

  20. Salt marsh vegetation promotes efficient tidal channel networks

    PubMed Central

    Kearney, William S.; Fagherazzi, Sergio

    2016-01-01

    Tidal channel networks mediate the exchange of water, nutrients and sediment between an estuary and marshes. Biology feeds back into channel morphodynamics through the influence of vegetation on both flow and the cohesive strength of channel banks. Determining how vegetation affects channel networks is essential in understanding the biological functioning of intertidal ecosystems and their ecosystem services. However, the processes that control the formation of an efficient tidal channel network remain unclear. Here we compare the channel networks of vegetated salt marshes in Massachusetts and the Venice Lagoon to unvegetated systems in the arid environments of the Gulf of California and Yemen. We find that the unvegetated systems are dissected by less efficient channel networks than the vegetated salt marshes. These differences in network geometry reflect differences in the branching and meandering of the channels in the network, characteristics that are related to the density of vegetation on the marsh. PMID:27430165

  1. Final report: Initial ecosystem response of salt marshes to ditch plugging and pool creation: Experiments at Rachel Carson National Wildlife Refuge (Maine)

    USGS Publications Warehouse

    Adamowicz, S.C.; Roman, C.T.

    2002-01-01

    This study evaluates the response of three salt marshes, associated with the Rachel Carson National Wildlife Refuge (Maine), to the practice of ditch plugging. Drainage ditches, originally dug to drain the marsh for mosquito control or to facilitate salt hay farming, are plugged with marsh peat in an effort to impound water upstream of the plug, raise water table levels in the marsh, and increase surface water habitat. At two study sites, Moody Marsh and Granite Point Road Marsh, ditch plugs were installed in spring 2000. Monitoring of hydrology, vegetation, nekton and bird utilization, and marsh development processes was conducted in 1999, before ditch plugging, and then in 2000 and 2001 (all parameters except nekton), after ditch plugging. Each study site had a control marsh that was monitored simultaneously with the plugged marsh, and thus, we employed a BACI study design (before, after, control, impact). A third site, Marshall Point Road Marsh, was plugged in 1998. Monitoring of the plugged and control sites was conducted in 1999 and 2000, with limited monitoring in 2001, thus there was no ?before? plug monitoring. With ditch plugging, water table levels increased toward the marsh surface and the areal extent of standing water increased. Responding to a wetter substrate, a vegetation change from high marsh species (e.g., Spartina patens) to those more tolerant of flooded conditions (e.g., Spartina alterniflora) was noted at two of the three ditch plugged sites. Initial response of the nekton community (fishes and decapod crustaceans) was evaluated by monitoring utilization of salt marsh pools using a 1m2 enclosure trap. In general, nekton species richness, density, and community structure remained unchanged following ditch plugging at the Moody and Granite Point sites. At Marshall Point, species richness and density (number of individuals per m2) were significantly greater in the experimental plugged marsh than the control marsh (<2% of the control marsh was

  2. Restoring Ecological Function to a Submerged Salt Marsh

    USGS Publications Warehouse

    Stagg, C.L.; Mendelssohn, I.A.

    2010-01-01

    Impacts of global climate change, such as sea level rise and severe drought, have altered the hydrology of coastal salt marshes resulting in submergence and subsequent degradation of ecosystem function. A potential method of rehabilitating these systems is the addition of sediment-slurries to increase marsh surface elevation, thus ameliorating effects of excessive inundation. Although this technique is growing in popularity, the restoration of ecological function after sediment addition has received little attention. To determine if sediment subsidized salt marshes are functionally equivalent to natural marshes, we examined above- and belowground primary production in replicated restored marshes receiving four levels of sediment addition (29-42 cm North American Vertical Datum of 1988 [NAVD 88]) and in degraded and natural ambient marshes (4-22 cm NAVD 88). Moderate intensities of sediment-slurry addition, resulting in elevations at the mid to high intertidal zone (29-36 cm NAVD 88), restored ecological function to degraded salt marshes. Sediment additions significantly decreased flood duration and frequency and increased bulk density, resulting in greater soil drainage and redox potential and significantly lower phytotoxic sulfide concentrations. However, ecological function in the restored salt marsh showed a sediment addition threshold that was characterized by a decline in primary productivity in areas of excessive sediment addition and high elevation (>36 cm NAVD 88). Hence, the addition of intermediate levels of sediment to submerging salt marshes increased marsh surface elevation, ameliorated impacts of prolonged inundation, and increased primary productivity. However, too much sediment resulted in diminished ecological function that was equivalent to the submerged or degraded system. ?? 2010 Society for Ecological Restoration International.

  3. Florida's salt-marsh management issues: 1991-98.

    PubMed

    Carlson, D B; O'Bryan, P D; Rey, J R

    1999-06-01

    During the 1990s, Florida has continued to make important strides in managing salt marshes for both mosquito control and natural resource enhancement. The political mechanism for this progress continues to be interagency cooperation through the Florida Coordinating Council on Mosquito Control and its Subcommittee on Managed Marshes (SOMM). Continuing management experience and research has helped refine the most environmentally acceptable source reduction methods, which typically are Rotational Impoundment Management or Open Marsh Water Management. The development of regional marsh management plans for salt marshes within the Indian River Lagoon by the SOMM has helped direct the implementation of the best management practices for these marshes. Controversy occasionally occurs concerning what management technique is most appropriate for individual marshes. The most common disagreement is over the benefits of maintaining an impoundment in an "open" vs. "closed" condition, with the "closed" condition, allowing for summer mosquito control flooding or winter waterfowl management. New federal initiatives influencing salt-marsh management have included the Indian River Lagoon-National Estuary Program and the Pesticide Environmental Stewardship Program. A new Florida initiative is the Florida Department of Environmental Protection's Eco-system Management Program with continuing involvement by the Surface Water Improvement and Management program. A developing mitigation banking program has the potential to benefit marsh management but mosquito control interests may suffer if not handled properly. Larvicides remain as an important salt-marsh integrated pest management tool with the greatest acreage being treated with temephos, followed by Bacillus thuringiensis israelensis and methoprene. However, over the past 14 years, use of biorational larvicides has increased greatly.

  4. Methylmercury production in a Chesapeake Bay salt marsh

    NASA Astrophysics Data System (ADS)

    Mitchell, Carl P. J.; Gilmour, Cynthia C.

    2008-06-01

    In a detailed study of the biogeochemical factors affecting the methylation of mercury in a Chesapeake Bay salt marsh, we examined relationships between mercury methylation and numerous variables, including sulfate reduction rates, organic carbon mineralization rates, iron and sulfur chemistry, and the character of dissolved organic matter (DOM). Our data show that salt marshes are important sites of de novo methylmercury (MeHg) production in coastal ecosystems. Some of the controls on MeHg production that have been well-described in other ecosystems also impacted MeHg production in this salt marsh, specifically the effect of sulfide accumulation on mercury bioavailability. We observed some novel biogeochemical relationships with Hg(II)-methylation and MeHg accumulation, particularly the positive association of Hg(II)-methylation with zones of microbial iron reduction. On the basis of this relationship, we suggest caution in wetland and groundwater remediation approaches involving iron additions. Aqueous phase Hg complexation appeared to be the dominant control on Hg bioavailability across the marsh sites examined, rather than Hg partitioning behavior. A detailed examination of DOM character in the marsh suggested a strong positive association between Hg(II)-methylation rate constants and increasing DOM molecular weight. Overall, our results indicate that net MeHg production is controlled by a balance between microbial activity and geochemical effects on mercury bioavailability, but that a significant zone of MeHg production can persist in near surface salt marsh soils. Production of MeHg in coastal marshes may negatively impact ecosystems via export to adjacent estuaries or through direct bioaccumulation in birds, fish and amphibians that feed in these highly productive ecosystems.

  5. Numerical models of salt marsh evolution: Ecological, geomorphic, and climatic factors

    USGS Publications Warehouse

    Fagherazzi, S.; Kirwan, M.L.; Mudd, S.M.; Guntenspergen, G.R.; Temmerman, S.; D'Alpaos, A.; Van De Koppel, J.; Rybczyk, J.M.; Reyes, E.; Craft, C.; Clough, J.

    2012-01-01

    Salt marshes are delicate landforms at the boundary between the sea and land. These ecosystems support a diverse biota that modifies the erosive characteristics of the substrate and mediates sediment transport processes. Here we present a broad overview of recent numerical models that quantify the formation and evolution of salt marshes under different physical and ecological drivers. In particular, we focus on the coupling between geomorphological and ecological processes and on how these feedbacks are included in predictive models of landform evolution. We describe in detail models that simulate fluxes of water, organic matter, and sediments in salt marshes. The interplay between biological and morphological processes often produces a distinct scarp between salt marshes and tidal flats. Numerical models can capture the dynamics of this boundary and the progradation or regression of the marsh in time. Tidal channels are also key features of the marsh landscape, flooding and draining the marsh platform and providing a source of sediments and nutrients to the marsh ecosystem. In recent years, several numerical models have been developed to describe the morphogenesis and long-term dynamics of salt marsh channels. Finally, salt marshes are highly sensitive to the effects of long-term climatic change. We therefore discuss in detail how numerical models have been used to determine salt marsh survival under different scenarios of sea level rise. Copyright 2012 by the American Geophysical Union.

  6. Numerical models of salt marsh evolution: ecological, geomorphic, and climatic factors

    USGS Publications Warehouse

    Fagherazzi, Sergio; Kirwan, Matthew L.; Mudd, Simon M.; Guntenspergen, Glenn R.; Temmerman, Stijn; D'Alpaos, Andrea; van de Koppel, Johan; Rybczyk, John; Reyes, Enrique; Craft, Chris; Clough, Jonathan

    2012-01-01

    Salt marshes are delicate landforms at the boundary between the sea and land. These ecosystems support a diverse biota that modifies the erosive characteristics of the substrate and mediates sediment transport processes. Here we present a broad overview of recent numerical models that quantify the formation and evolution of salt marshes under different physical and ecological drivers. In particular, we focus on the coupling between geomorphological and ecological processes and on how these feedbacks are included in predictive models of landform evolution. We describe in detail models that simulate fluxes of water, organic matter, and sediments in salt marshes. The interplay between biological and morphological processes often produces a distinct scarp between salt marshes and tidal flats. Numerical models can capture the dynamics of this boundary and the progradation or regression of the marsh in time. Tidal channels are also key features of the marsh landscape, flooding and draining the marsh platform and providing a source of sediments and nutrients to the marsh ecosystem. In recent years, several numerical models have been developed to describe the morphogenesis and long-term dynamics of salt marsh channels. Finally, salt marshes are highly sensitive to the effects of long-term climatic change. We therefore discuss in detail how numerical models have been used to determine salt marsh survival under different scenarios of sea level rise.

  7. What's the Use of a Salt Marsh?

    ERIC Educational Resources Information Center

    Van Raalte, Charlene

    1977-01-01

    Summarizes information about salt marshes, including descriptions of their development and structure, details of their values in terms of commercial fishing, stabilization of coastal zones, "reclamation" for grazing and cropfields, recreation and aesthetics. (CS)

  8. A Review of Tidal Salt Marsh Morphodynamics

    NASA Astrophysics Data System (ADS)

    Friedrichs, C. T.; Perry, J. E.

    2001-05-01

    We now understand that, morphologically, natural tidal marshes are generally near or progressing rapidly toward dynamic equilibrium with sediment supply, vegetative growth and relative sea level, rather than far out of equilibrium on a slow evolution toward geologic maturity. The last fifteen years have been marked by major advances in the observation of sedimentation and accretion patterns in tidal salt marshes which reinforce the above interpretation. This paper reviews and synthesizes advances since the late 1980s in our understanding of tidal salt marsh morphodynamics. Recent work has shown that allochthonous deposition patterns on the marsh are controlled primarily by source concentration, distance from that source, and duration of inundation (in turn determined by marsh elevation). Because deposition is proportional to inundation period, inorganic accretion tends to increase or decrease with accelerated or decelerated sea level rise, allowing the accretion rate to similarly fluctuate. Feedback between proximity to sediment source and duration of inundation causes relatively uniform accretion to be characterized by highest marsh elevations adjacent to tidal creeks. Since physical stress on vegetation increases with inundation, plant density and accretion of organic matter is reduced as inundation period increases, a pattern opposite to allochthonous deposition. Among systems dominated by allochthonous sediment, microtidal marshes are more reliant on storm and flood sedimentation and horizontally expand and retreat more quickly than macrotidal marshes, while the latter are more likely to persist during periods of accelerated sea level rise. The density, width and depth of salt marsh creeks all increase with increased tidal prism. Along barrier coastlines, greater tidal range is associated with more frequent inlet spacing, shallower channels, flood-dominance, and higher marsh elevation at equilibrium. Smaller tidal range results in greater inlet spacing, deeper

  9. Regional ontogeny of New England salt marsh die-off.

    PubMed

    Coverdale, Tyler C; Bertness, Mark D; Altieri, Andrew H

    2013-10-01

    Coastal areas are among the world's most productive and highly affected ecosystems. Centuries of human activity on coastlines have led to overexploitation of marine predators, which in turn has led to cascading ecosystem-level effects. Human effects and approaches to mediating them, however, differ regionally due to gradients in biotic and abiotic factors. Salt marsh die-off on Cape Cod, Massachusetts (U.S.A.), triggered by a recreational-fishing-induced trophic cascade that has released herbivorous crabs from predator control, has been ongoing since 1976. Similar salt marsh die-offs have been reported in Long Island Sound and Narragansett Bay (U.S.A.), but the driving mechanism of these die-offs has not been examined. We used field experiments to assess trophic interactions and historical reconstructions of 24 New England marshes to test the hypotheses that recreational fishing and predator depletion are a regional trigger of salt marsh die-off in New England and that die-offs in Long Island Sound and Narragansett Bay are more recent than those on Cape Cod. Predator depletion was the general trigger of marsh die-off and explained differences in herbivorous crab abundance and the severity of die-off across regions. Die-offs in Long Island Sound and Narragansett Bay are following a trajectory similar to die-off on Cape Cod, but are approximately 20 years behind those on Cape Cod. As a result, die-off currently affects 31.2% (SE 2.2) of low-marsh areas in Long Island Sound and Narragansett Bay, less than half the severity of die-off on Cape Cod. Our results contribute to the growing evidence that recreational fishing is an increasing threat to coastal ecosystems and that studying the effects of human activity at regional scales can provide insight into local effects and aid in early detection and potential remediation.

  10. Salt-Marsh Landscapes and the Signatures of Biogeomorphic Feedbacks

    NASA Astrophysics Data System (ADS)

    D'Alpaos, A.; Marani, M.

    2014-12-01

    Salt marshes are coastal ecosystems which play a large role in the bio-geomorphological evolution of intertidal areas. The dense stands of halophytic plants which populate salt-marsh systems largely contribute to govern their dynamics, influencing marsh hydrodynamics and sediment transport through enhanced flow resistance and settling, and direct particle capture by plant stems. In addition, plants are known to increase vertical accretion through direct organic accretion. Looking across the salt-marsh landscape can one see the signatures of feedbacks between landscape and biota? Field evidence and the results of biomorphodynamic models indeed show that the interplay between physical and biological processes generates some striking biological and morphological patterns at different scales. One such pattern, vegetation zonation, consists in a mosaic of vegetation patches, of approximately uniform composition, displaying sharp transitions in the presence of extremely small topographic gradients. Here we extend the model proposed by Marani et al. (2013) to a two-dimensional framework, furthermore including the effect of direct capture of sediment particles by plant stems. This allows us to account for the effect of the drainage density of tidal networks on the observed biogeomorphic patterns and to model the coupled evolution of marsh platforms and channel networks cutting through them. A number of different scenarios have been modelled to analyze the changes induced in bio-geomorphic patterns by plants with different characteristics, within marshes characterized by different drainage densities, or subjected to changing environmental forcing such as rates of relative sea level rise and sediment supply. Model results emphasize that zonation patterns are a signature of bio-geomorphic feedbacks with vegetation acting as a landscape constructor which feeds back on, directly alters, and contributes to shape tidal environments. In addition, model results show that

  11. Coastal Wetland Deterioration, Climate Change and Nutrient Inputs in California and Southern New England Salt Marsh

    EPA Science Inventory

    Coastal salt marshes provide a wide variety of ecosystem services, including habitat for protected vertebrates and ecologically valuable invertebrate fauna, flood protection, and improvements in water quality for adjacent marine and estuarine environments. Here, we consider the i...

  12. Carbon and Nitrogen Accumulation Rates in Salt Marshes in Oregon, USA

    EPA Science Inventory

    Two important ecosystem services of wetlands are carbon sequestration and filtration of nutrients and particulates. We quantified the carbon and nitrogen accumulation rates in salt marshes at 135 plots distributed across eight estuaries located in Oregon, USA. Net carbon and ...

  13. INDICATORS OF ANTHROPOGENIC DISTURBANCE IN STREAMS AND RECEIVING SALT MARSHES

    EPA Science Inventory

    Land use and anthropogenic activities in watersheds affect biological, chemical, and physical conditions in streams and receiving coastal salt marshes. Our objective was to compare indicators of stream and riparian condition with analogous indicators of the coastal salt marshes i...

  14. INDICATORS OF ANTHROPOGENIC DISTURBANCE IN STREAMS AND RECEINVING SALT MARSHES

    EPA Science Inventory

    Land use and anthropogenic activities in watersheds affect biological, chemical, and physical conditions in streams and receiving coastal salt marshes. Our objective was to compare indicators of stream and riparian condition with analogous indicators of the coastal salt marshes...

  15. INDICATORS OF ANTHROPOGENIC DISTURBANCES IN STREAMS AND RECEIVING SALT MARSHES

    EPA Science Inventory

    Land use and anthropogenic activities in watersheds affect biological, chemical, and physical conditions in streams and receiving coastal salt marshes. Our objective was to compare indicators of stream and riparian condition with analogous indicators of the coastal salt marshes i...

  16. A global analysis of the seaward salt marsh extent: The importance of tidal range

    NASA Astrophysics Data System (ADS)

    Balke, Thorsten; Stock, Martin; Jensen, Kai; Bouma, Tjeerd J.; Kleyer, Michael

    2016-05-01

    Despite the growing interest in ecosystem services provided by intertidal wetlands, we lack sufficient understanding of the processes that determine the seaward extent of salt marsh vegetation on tidal flats. With the present study, we aim to establish a globally valid demarcation between tidal flats and salt marsh vegetation in relation to tidal range. By comparing results from a regional GIS study with a global literature search on the salt marsh-tidal flat border, we are able to define the global critical elevation, above which salt marsh plants can grow in the intertidal zone. Moreover, we calculate inundation characteristics from global tide gauge records to determine inundation duration and frequency at this predicted salt marsh-tidal flat border depending on tidal range. Our study shows that the height difference between the lowest elevation of salt marsh pioneer vegetation and mean high water increases logarithmically with tidal range when including macrotidal salt marshes. Hence, the potentially vegetated section of the tidal frame below mean high water does not proportionally increase with tidal range. The data analysis suggests that inundation frequency rather than duration defines the global lower elevational limit of vascular salt marsh plants on tidal flats. This is critical information to better estimate sea level rise and coastal change effects on lateral marsh development.

  17. Signatures of Biogeomorphic Feedbacks in Salt-Marsh Systems

    NASA Astrophysics Data System (ADS)

    D'Alpaos, Andrea; Marani, Marco

    2015-04-01

    Salt-marsh ecosystems which play a large role in the bio-geomorphological evolution of intertidal areas. Dense stands of halophytic vegetations which populate salt marshes largely control the dynamics of these ecosystems influencing marsh hydrodynamics and sediment transport through enhanced flow resistance and settling, and direct particle capture by plant stems. Moreover, plants are also known to increase vertical accretion through direct organic accretion. Field evidence and the results of biomorphodynamic models indeed show that the interplay between physical and biological processes generates some striking biological and morphological patterns at different scales. One such pattern, vegetation zonation, consists in a mosaic of vegetation patches, of approximately uniform composition, displaying sharp transitions in the presence of extremely small topographic gradients. Here we develop a two-dimensional model which describes the mutual interaction and adjustment between tidal flows, sediment transport and morphology mediated by vegetation influence. The model allows us describe the coupled evolution of marsh platforms and channel networks cutting through them. A number of different scenarios were modelled to analyze the changes induced in bio-geomorphic patterns by plants with different characteristics, within marshes characterized by different drainage densities, or subjected to changing environmental forcing such as rates of relative sea level rise and sediment supply. Model results emphasize that zonation patterns are a signature of bio-geomorphic feedbacks with vegetation acting as a landscape constructor which feeds back on, directly alters, and contributes to shape tidal environments. In addition, model results show that biogeomorphic feedbacks critically affect the response and the resilience of salt-marsh landscapes to changes in the environmental forcing.

  18. Recent Trends in Bird Abundance on Rhode Island Salt Marshes

    EPA Science Inventory

    Salt marsh habitat is under pressure from development on the landward side, and sea level rise from the seaward side. The resulting loss of habitat is potentially disastrous for salt marsh dependent species. To assess the population status of three species of salt marsh dependent...

  19. Astronomical Forcing of Salt Marsh Biogeochemical Cascades

    NASA Astrophysics Data System (ADS)

    Morris, J. T.; Sundberg, K.

    2008-12-01

    Astronomically forced changes in the hydroperiod of a salt marsh affect the rate of marsh primary production leading to a biogeochemical cascade. For example, salt marsh primary production and biogeochemical cycles in coastal salt marshes are sensitive to the 18.6-year lunar nodal cycle, which alters the tidal amplitude by about 5 cm. For marshes that are perched high in the tidal frame, a relatively small increase in tidal amplitude and flooding lowers sediment salinity and stimulates primary production. Porewater sulfide concentrations are positively correlated with tidal amplitude and vary on the same cycle as primary production. Soluble reactive phosphate and ammonium concentrations in pore water also vary on this 18.6- year cycle. Phosphate likely responds to variation in the reaction of sulfide with iron-phosphate compounds, while the production of ammonium in sediments is coupled to the activity of diazotrophs that are carbon- limited and, therefore, are regulated by primary productivity. Ammonium also would accumulate when sulfides block nitrification. These dependencies work as a positive feedback between primary production and nutrient supply and are predictive of the near-term effects of sea-level rise.

  20. Geographic variation in salt marsh structure and function.

    PubMed

    McCall, Brittany D; Pennings, Steven C

    2012-11-01

    We examined geographic variation in the structure and function of salt marsh communities along the Atlantic and Gulf coasts of the United States. Focusing on the arthropod community in the dominant salt marsh plant Spartina alterniflora, we tested two hypotheses: first, that marsh community structure varies geographically, and second, that two aspects of marsh function (response to eutrophication and addition of dead plant material) also vary geographically. We worked at eleven sites on the Gulf Coast and eleven sites on the Atlantic Coast, dividing each coast up into two geographic areas. Abiotic conditions (tidal range, soil organic content, and water content, but not soil salinity), plant variables (Spartina nitrogen content, height, cover of dead plant material, but not live Spartina percent cover or light interception), and arthropod variables (proportional abundances of predators, sucking herbivores, stem-boring herbivores, parasitoids, and detritivores, but not total arthropod numbers) varied among the four geographic regions. Latitude and mean tidal range explained much of this geographic variation. Nutrient enrichment increased all arthropod functional groups in the community, consistent with previous experimental results, and had similar effects in all geographic regions, contrary to our hypothesis, suggesting widespread consistency in this aspect of ecosystem function. The addition of dead plant material had surprisingly little effect on the arthropod community. Our results caution against the uncritical extrapolation of work done in one geographic region to another, but indicate that some aspects of marsh function may operate in similar ways in different geographic regions, despite spatial variation in community structure. PMID:22614261

  1. Habitat Function of a Restored Salt Marsh: Post-Larval Gulf Killifish as a Sentinel

    EPA Science Inventory

    Successful marsh restoration requires recreating conditions to ensure proper ecosystem function. One approach to monitor restoration success is using a sentinel species as a proxy integrator of salt marsh function. The gulf killifish (Fundulus grandis, Baird and Girard) is a goo...

  2. Factors controlling dimethylsulfide emission from salt marshes

    NASA Technical Reports Server (NTRS)

    Dacey, John W. H.; Wakeham, S. G.; Howes, B. L.

    1985-01-01

    The factors that control the emission of methylated gases from salt marshes are being studied. Research focusses on dimethylsulfide (DMS) formation and the mechanism of DMS and CH4 emission to the atmosphere. The approach is to consider the plants as valves regulating the emission of methylated gases to the atmosphere with the goal of developing appropriate methods for emission measurement. In the case of CH4, the sediment is the source and transport to the atmosphere occurs primarily through the internal gas spaces in the plants. The source of DMS appears to be dimethyl sulfoniopropionate (DMSP) which may play a role in osmoregulation in plant tissues. Concentrations of DMSP in leaves are typically several-fold higher than in roots and rhizomes. Even so, the large below ground biomass of this plant means that 2/3 of the DMSP in the ecosystem is below ground on the aerial basis. Upon introduction to sediment water, DMSP rapidly decomposes to DMS and acrylic acid. The solubility of a gas (its equilibrium vapor pressure) is a fundamental aspect of gas exchange kinetics. The first comprehensive study was conducted of DMS solubility in freshwater and seawater. Data suggest that the Setchenow relation holds for H at intermediate salinities collected. These data support the concept that the concentration of DMS in the atmosphere is far from equilibrium with seawater.

  3. Long term (>100 years) Carbon Sequestration in California Coastal Salt Marshes

    NASA Astrophysics Data System (ADS)

    Brown, L. N.; MacDonald, G. M.; Holmquist, J. R.

    2014-12-01

    Coastal salt marsh ecosystems rank as one of the ecosystems which sequester the most carbon (C) in the world (Chmura, 2003; Mcleod et al., 2011). California hosts multiple small marsh ecosystems outside of the San Francisco Bay that are limited in geographic extent but still contribute significantly to global soil C. This study evaluates 11 marsh sites along the California coast for annual soil C sequestration rates using 14C, 137Cs, and 210Pb chronologies. Estimates of carbon sequestration for California over the past 100 years from this study average at 49 g C m-2 yr-1. Long term estimates of soil C generally are lower because of natural decomposition of organic C, but this study indicates a persistence of high C storage capacity for coastal marsh systems. These estimates provide valuable insight into the long term capacity for coastal salt marshes to mitigate climate change through sequestration of C.

  4. Methane flux from coastal salt marshes

    SciTech Connect

    Bartlett, K.B.; Harriss, R.C.; Sebacher, D.I.

    1985-06-20

    The seasonal flux of methane to the atmosphere from salt marsh soils was examined in three different vegetation zones within a single marsh near Yorktown, Virginia. A total of 100 measurements were made over a 2-year period, with maximum rates occurring during summer and fall. Spatial and temporal variability in fluxes was high; rates ranged from -2.4 to 21.3 x 10/sup -3/ g CH/sub 4//m/sup 2//d. Estimates of annual methane losses to the atmosphere were 0.43 g CH/sub 4//m/sup 2/ for a salt meadow zone, 1.3 g CH/sub 4//m/sup 2/ for short Spartina alterniflora, and 1.2 g CH/sub 4//m/sup 2/ for tall creek-bank S. alterniflora. A total of 63 flux measurements, made in a variety of other coastal salt marshes along the east coast of the US, suggest that the Virginia site may be fairly typical for this region. In addition to diffusional losses across the air-soil interface, methane can be lost from the marsh system to the atmosphere through the lateral movement of pore waters supersaturated with methane into tidal creeks, with subsequent degassing across the water-air interface. Estimates of the magnitude of methane input to the atmosphere by this mechanism indicate it may be as important as diffusional losses across the air-soil interface. These data suggest that salt marshes of this type make only a minor contribution to global atmospheric methane.

  5. Microbial Community Analysis of a Coastal Salt Marsh Affected by the Deepwater Horizon Oil Spill

    PubMed Central

    Beazley, Melanie J.; Martinez, Robert J.; Rajan, Suja; Powell, Jessica; Piceno, Yvette M.; Tom, Lauren M.; Andersen, Gary L.; Hazen, Terry C.; Van Nostrand, Joy D.; Zhou, Jizhong; Mortazavi, Behzad; Sobecky, Patricia A.

    2012-01-01

    Coastal salt marshes are highly sensitive wetland ecosystems that can sustain long-term impacts from anthropogenic events such as oil spills. In this study, we examined the microbial communities of a Gulf of Mexico coastal salt marsh during and after the influx of petroleum hydrocarbons following the Deepwater Horizon oil spill. Total hydrocarbon concentrations in salt marsh sediments were highest in June and July 2010 and decreased in September 2010. Coupled PhyloChip and GeoChip microarray analyses demonstrated that the microbial community structure and function of the extant salt marsh hydrocarbon-degrading microbial populations changed significantly during the study. The relative richness and abundance of phyla containing previously described hydrocarbon-degrading bacteria (Proteobacteria, Bacteroidetes, and Actinobacteria) increased in hydrocarbon-contaminated sediments and then decreased once hydrocarbons were below detection. Firmicutes, however, continued to increase in relative richness and abundance after hydrocarbon concentrations were below detection. Functional genes involved in hydrocarbon degradation were enriched in hydrocarbon-contaminated sediments then declined significantly (p<0.05) once hydrocarbon concentrations decreased. A greater decrease in hydrocarbon concentrations among marsh grass sediments compared to inlet sediments (lacking marsh grass) suggests that the marsh rhizosphere microbial communities could also be contributing to hydrocarbon degradation. The results of this study provide a comprehensive view of microbial community structural and functional dynamics within perturbed salt marsh ecosystems. PMID:22815990

  6. Early Salt-Marsh Development, an Example of a Turing Instability?

    NASA Astrophysics Data System (ADS)

    van de Koppel, J.

    2008-12-01

    In the past decades, regular spatial patterns have been described in a wide range of ecosystems, ranging from arid lands to boreal peat lands. Pattern formation mechanisms in many of these ecosystems are caused by scale-dependent interactions between organisms and geophysical processes, causing facilitation between organisms at small spatial scale, but inhibition at larger spatial scales. This conforms to the activation-inhibition principle laid out by Alan Turing in 1953. We present a combination of experimental and modeling studies on early salt-marsh development that indicate that similar scale-dependent interactions determine the establishment of salt-marsh vegetation and early geomorphological development of the marsh. Based on these studies, we argue that the early development of salt-marsh ecosystems is characterized by a Turing instability, placed into a complex landscape setting.

  7. VALUING AN INTERVENTION: MARSH MIGRATION AND ECOSYSTEM SERVICES

    EPA Science Inventory

    There is growing interest in valuing ecosystem services provided by marsh systems. Ecosystem services represent a flow of benefits to society from the existence or functioning of the marsh. Therefore, to “put a value on” the marsh itself, or estimate a value of the na...

  8. Carbon Sequestration in Tidal Salt Marshes of the Northeast United States.

    PubMed

    Drake, Katherine; Halifax, Holly; Adamowicz, Susan C; Craft, Christopher

    2015-10-01

    Tidal salt marshes provide important ecological services, habitat, disturbance regulation, water quality improvement, and biodiversity, as well as accumulation and sequestration of carbon dioxide (CO2) in vegetation and soil organic matter. Different management practices may alter their capacity to provide these ecosystem services. We examined soil properties (bulk density, percent organic C, percent N), C and N pools, C sequestration and N accumulation at four marshes managed with open marsh water management (OMWM) and four marshes that were not at U.S. Fish and Wildlife National Wildlife Refuges (NWRs) on the East Coast of the United States. Soil properties (bulk density, percent organic C, percent N) exhibited no consistent differences among managed and non-OMWM marshes. Soil organic carbon pools (0-60-cm depth) also did not differ. Managed marshes contained 15.9 kg C/m(2) compared to 16.2 kg C/m(2) in non-OMWM marshes. Proportionately, more C (per unit volume) was stored in surface than in subsurface soils. The rate of C sequestration, based on (137)Cs and (210)Pb dating of soil cores, ranged from 41 to 152 g/m(2)/year. Because of the low emissions of CH4 from salt marshes relative to freshwater wetlands and the ability to sequester C in soil, protection and restoration of salt marshes can be a vital tool for delivering key ecosystem services, while at the same time, reducing the C footprint associated with managing these wetlands.

  9. Carbon Sequestration in Tidal Salt Marshes of the Northeast United States.

    PubMed

    Drake, Katherine; Halifax, Holly; Adamowicz, Susan C; Craft, Christopher

    2015-10-01

    Tidal salt marshes provide important ecological services, habitat, disturbance regulation, water quality improvement, and biodiversity, as well as accumulation and sequestration of carbon dioxide (CO2) in vegetation and soil organic matter. Different management practices may alter their capacity to provide these ecosystem services. We examined soil properties (bulk density, percent organic C, percent N), C and N pools, C sequestration and N accumulation at four marshes managed with open marsh water management (OMWM) and four marshes that were not at U.S. Fish and Wildlife National Wildlife Refuges (NWRs) on the East Coast of the United States. Soil properties (bulk density, percent organic C, percent N) exhibited no consistent differences among managed and non-OMWM marshes. Soil organic carbon pools (0-60-cm depth) also did not differ. Managed marshes contained 15.9 kg C/m(2) compared to 16.2 kg C/m(2) in non-OMWM marshes. Proportionately, more C (per unit volume) was stored in surface than in subsurface soils. The rate of C sequestration, based on (137)Cs and (210)Pb dating of soil cores, ranged from 41 to 152 g/m(2)/year. Because of the low emissions of CH4 from salt marshes relative to freshwater wetlands and the ability to sequester C in soil, protection and restoration of salt marshes can be a vital tool for delivering key ecosystem services, while at the same time, reducing the C footprint associated with managing these wetlands. PMID:26108413

  10. Carbon Sequestration in Tidal Salt Marshes of the Northeast United States

    NASA Astrophysics Data System (ADS)

    Drake, Katherine; Halifax, Holly; Adamowicz, Susan C.; Craft, Christopher

    2015-10-01

    Tidal salt marshes provide important ecological services, habitat, disturbance regulation, water quality improvement, and biodiversity, as well as accumulation and sequestration of carbon dioxide (CO2) in vegetation and soil organic matter. Different management practices may alter their capacity to provide these ecosystem services. We examined soil properties (bulk density, percent organic C, percent N), C and N pools, C sequestration and N accumulation at four marshes managed with open marsh water management (OMWM) and four marshes that were not at U.S. Fish and Wildlife National Wildlife Refuges (NWRs) on the East Coast of the United States. Soil properties (bulk density, percent organic C, percent N) exhibited no consistent differences among managed and non-OMWM marshes. Soil organic carbon pools (0-60-cm depth) also did not differ. Managed marshes contained 15.9 kg C/m2 compared to 16.2 kg C/m2 in non-OMWM marshes. Proportionately, more C (per unit volume) was stored in surface than in subsurface soils. The rate of C sequestration, based on 137Cs and 210Pb dating of soil cores, ranged from 41 to 152 g/m2/year. Because of the low emissions of CH4 from salt marshes relative to freshwater wetlands and the ability to sequester C in soil, protection and restoration of salt marshes can be a vital tool for delivering key ecosystem services, while at the same time, reducing the C footprint associated with managing these wetlands.

  11. Geographic variation in plant community structure of salt marshes: species, functional and phylogenetic perspectives.

    PubMed

    Guo, Hongyu; Chamberlain, Scott A; Elhaik, Eran; Jalli, Inder; Lynes, Alana-Rose; Marczak, Laurie; Sabath, Niv; Vargas, Amy; Więski, Kazimierz; Zelig, Emily M; Pennings, Steven C

    2015-01-01

    In general, community similarity is thought to decay with distance; however, this view may be complicated by the relative roles of different ecological processes at different geographical scales, and by the compositional perspective (e.g. species, functional group and phylogenetic lineage) used. Coastal salt marshes are widely distributed worldwide, but no studies have explicitly examined variation in salt marsh plant community composition across geographical scales, and from species, functional and phylogenetic perspectives. Based on studies in other ecosystems, we hypothesized that, in coastal salt marshes, community turnover would be more rapid at local versus larger geographical scales; and that community turnover patterns would diverge among compositional perspectives, with a greater distance decay at the species level than at the functional or phylogenetic levels. We tested these hypotheses in salt marshes of two regions: The southern Atlantic and Gulf Coasts of the United States. We examined the characteristics of plant community composition at each salt marsh site, how community similarity decayed with distance within individual salt marshes versus among sites in each region, and how community similarity differed among regions, using species, functional and phylogenetic perspectives. We found that results from the three compositional perspectives generally showed similar patterns: there was strong variation in community composition within individual salt marsh sites across elevation; in contrast, community similarity decayed with distance four to five orders of magnitude more slowly across sites within each region. Overall, community dissimilarity of salt marshes was lowest on the southern Atlantic Coast, intermediate on the Gulf Coast, and highest between the two regions. Our results indicated that local gradients are relatively more important than regional processes in structuring coastal salt marsh communities. Our results also suggested that in

  12. Geographic Variation in Plant Community Structure of Salt Marshes: Species, Functional and Phylogenetic Perspectives

    PubMed Central

    Guo, Hongyu; Chamberlain, Scott A.; Elhaik, Eran; Jalli, Inder; Lynes, Alana-Rose; Marczak, Laurie; Sabath, Niv; Vargas, Amy; Więski, Kazimierz; Zelig, Emily M.; Pennings, Steven C.

    2015-01-01

    In general, community similarity is thought to decay with distance; however, this view may be complicated by the relative roles of different ecological processes at different geographical scales, and by the compositional perspective (e.g. species, functional group and phylogenetic lineage) used. Coastal salt marshes are widely distributed worldwide, but no studies have explicitly examined variation in salt marsh plant community composition across geographical scales, and from species, functional and phylogenetic perspectives. Based on studies in other ecosystems, we hypothesized that, in coastal salt marshes, community turnover would be more rapid at local versus larger geographical scales; and that community turnover patterns would diverge among compositional perspectives, with a greater distance decay at the species level than at the functional or phylogenetic levels. We tested these hypotheses in salt marshes of two regions: The southern Atlantic and Gulf Coasts of the United States. We examined the characteristics of plant community composition at each salt marsh site, how community similarity decayed with distance within individual salt marshes versus among sites in each region, and how community similarity differed among regions, using species, functional and phylogenetic perspectives. We found that results from the three compositional perspectives generally showed similar patterns: there was strong variation in community composition within individual salt marsh sites across elevation; in contrast, community similarity decayed with distance four to five orders of magnitude more slowly across sites within each region. Overall, community dissimilarity of salt marshes was lowest on the southern Atlantic Coast, intermediate on the Gulf Coast, and highest between the two regions. Our results indicated that local gradients are relatively more important than regional processes in structuring coastal salt marsh communities. Our results also suggested that in

  13. Salt marsh-mangrove ecotones: using structural gradients to investigate the effects of woody plant encroachment on plant-soil interactions and ecosystem carbon pools

    USGS Publications Warehouse

    Yando, Erik S.; Osland, Michael J.; Willis, Jonathan M; Day, Richard H.; Krauss, Ken W.; Hester, Mark W.

    2016-01-01

    Synthesis: Our results indicate that the ecological implications of woody plant encroachment in tidal saline wetlands are dependent upon precipitation controls of plant–soil interactions. Although the above-ground effects of mangrove expansion are consistently large, below-ground influences of mangrove expansion appear to be greatest along low-rainfall coasts where salinities are high and marshes being replaced are carbon poor and dominated by succulent plants. Collectively, these findings complement those from terrestrial ecosystems and reinforce the importance of considering rainfall and plant–soil interactions within predictions of the ecological effects of woody plant encroachment.

  14. Crenarchaeal heterotrophy in salt marsh sediments

    PubMed Central

    Seyler, Lauren M; McGuinness, Lora M; Kerkhof, Lee J

    2014-01-01

    Mesophilic Crenarchaeota (also known as Thaumarchaeota) are ubiquitous and abundant in marine habitats. However, very little is known about their metabolic function in situ. In this study, salt marsh sediments from New Jersey were screened via stable isotope probing (SIP) for heterotrophy by amending with a single 13C-labeled compound (acetate, glycine or urea) or a complex 13C-biopolymer (lipids, proteins or growth medium (ISOGRO)). SIP incubations were done at two substrate concentrations (30–150 μM; 2–10 mg ml−1), and 13C-labeled DNA was analyzed by terminal restriction fragment length polymorphism (TRFLP) analysis of 16S rRNA genes. To test for autotrophy, an amendment with 13C-bicarbonate was also performed. Our SIP analyses indicate salt marsh crenarchaea are heterotrophic, double within 2–3 days and often compete with heterotrophic bacteria for the same organic substrates. A clone library of 13C-amplicons was screened to find matches to the 13C-TRFLP peaks, with seven members of the Miscellaneous Crenarchaeal Group and seven members from the Marine Group 1.a Crenarchaeota being discerned. Some of these crenarchaea displayed a preference for particular carbon sources, whereas others incorporated nearly every 13C-substrate provided. The data suggest salt marshes may be an excellent model system for studying crenarchaeal metabolic capabilities and can provide information on the competition between crenarchaea and other microbial groups to improve our understanding of microbial ecology. PMID:24553469

  15. Crenarchaeal heterotrophy in salt marsh sediments.

    PubMed

    Seyler, Lauren M; McGuinness, Lora M; Kerkhof, Lee J

    2014-07-01

    Mesophilic Crenarchaeota (also known as Thaumarchaeota) are ubiquitous and abundant in marine habitats. However, very little is known about their metabolic function in situ. In this study, salt marsh sediments from New Jersey were screened via stable isotope probing (SIP) for heterotrophy by amending with a single (13)C-labeled compound (acetate, glycine or urea) or a complex (13)C-biopolymer (lipids, proteins or growth medium (ISOGRO)). SIP incubations were done at two substrate concentrations (30-150 μM; 2-10 mg ml(-1)), and (13)C-labeled DNA was analyzed by terminal restriction fragment length polymorphism (TRFLP) analysis of 16S rRNA genes. To test for autotrophy, an amendment with (13)C-bicarbonate was also performed. Our SIP analyses indicate salt marsh crenarchaea are heterotrophic, double within 2-3 days and often compete with heterotrophic bacteria for the same organic substrates. A clone library of (13)C-amplicons was screened to find matches to the (13)C-TRFLP peaks, with seven members of the Miscellaneous Crenarchaeal Group and seven members from the Marine Group 1.a Crenarchaeota being discerned. Some of these crenarchaea displayed a preference for particular carbon sources, whereas others incorporated nearly every (13)C-substrate provided. The data suggest salt marshes may be an excellent model system for studying crenarchaeal metabolic capabilities and can provide information on the competition between crenarchaea and other microbial groups to improve our understanding of microbial ecology.

  16. Plant invasion impacts on the gross and net primary production of the salt marsh on eastern coast of China: Insights from leaf to ecosystem

    NASA Astrophysics Data System (ADS)

    Ge, Zhen-Ming; Guo, Hai-Qiang; Zhao, Bin; Zhang, Li-Quan

    2015-01-01

    exotic Spartina alterniflora from North America has been rapidly invading the entire Chinese coast, while the impacts of plant invasion on the gross (GPP) and net primary production (NPP) of the coastal salt marshes were less known. In this study, we investigated the photosynthetic performance, leaf characteristics, and primary production of the exotic C4 grass and the dominant native C3 grass (Phragmites australis) in two marsh mixtures (equipped with eddy covariance systems) in the Yangtze Estuary. The light-saturated photosynthetic rate and annual peak leaf area index (LAI) of S. alterniflora was higher than that of P. australis throughout the growing season. The leaf nitrogen content of P. australis declined sharper during the latter growing season than that of S. alterniflora. The leaf-to-canopy production model with species-specific (C3 and C4 types) parameterizations could reasonably simulate the daily trends and annual GPP amount against the 3 year flux measurements from 2005 to 2007, and the modeled NPP agreed with biomass measurements from the two species during 2012. The percentage contributions of GPP between S. alterniflora and P. australis were on average 5.82:1 and 2.91:1 in the two mixtures, respectively. The annual NPP amounts from S. alterniflora were higher by approximately 1.6 times than that from P. australis. Our results suggested that higher photosynthesis efficiency, higher LAI, and longer growing season resulted in greater GPP and NPP in the exotic species relative to the native species. The rapid expansion rate of S. alterniflora further made it the leading contributor of primary production in the salt marsh.

  17. Metal speciation in salt marsh sediments: Influence of halophyte vegetation in salt marshes with different morphology

    NASA Astrophysics Data System (ADS)

    Pedro, Sílvia; Duarte, Bernardo; Raposo de Almeida, Pedro; Caçador, Isabel

    2015-12-01

    Salt marshes provide environmental conditions that are known to affect metal speciation in sediments. The elevational gradient along the marsh and consequent differential flooding are some of the major factors influencing halophytic species distribution and coverage due to their differential tolerance to salinity and submersion. Different species, in turn, also have distinct influences on the sediment's metal speciation, and its metal accumulation abilities. The present work aimed to evaluate how different halophyte species in two different salt marshes could influence metal partitioning in the sediment at root depth and how that could differ from bare sediments. Metal speciation in sediments around the roots (rhizosediments) of Halimione portulacoides, Sarcocornia fruticosa and Spartina maritima was determined by sequentially extracting operationally defined fractions with solutions of increasing strength and acidity. Rosário salt marsh generally showed higher concentrations of all metals in the rhizosediments. Metal partitioning was primarily related to the type of metal, with the elements' chemistry overriding the environment's influence on fractionation schemes. The most mobile elements were Cd and Zn, with greater availability being found in non-vegetated sediments. Immobilization in rhizosediments was predominantly influenced by the presence of Fe and Mn oxides, as well as organic complexes. In the more mature of both salt marshes, the differences between vegetated and non-vegetated sediments were more evident regarding S. fruticosa, while in the younger system all halophytes presented significantly different metal partitioning when compared to that of mudflats.

  18. Response of a salt marsh microbial community to metal contamination

    NASA Astrophysics Data System (ADS)

    Mucha, Ana P.; Teixeira, Catarina; Reis, Izabela; Magalhães, Catarina; Bordalo, Adriano A.; Almeida, C. Marisa R.

    2013-09-01

    Salt marshes are important sinks for contaminants, namely metals that tend to accumulate around plant roots and could eventually be taken up in a process known as phytoremediation. On the other hand, microbial communities display important roles in the salt marsh ecosystems, such as recycling of nutrients and/or degradation of organic contaminants. Thus, plants can benefit from the microbial activity in the phytoremediation process. Nevertheless, above certain levels, metals are known to be toxic to microorganisms, fact that can eventually compromise their ecological functions. In this vein, the aim of present study was to investigate, in the laboratory, the effect of selected metals (Cd, Cu and Pb) on the microbial communities associated to the roots of two salt marsh plants. Sediments colonized by Juncus maritimus and Phragmites australis were collected in the River Lima estuary (NW Portugal), and spiked with each of the metals at three different Effects Range-Median (ERM) concentrations (1, 10×, 50×), being ERM the sediment quality guideline that indicates the concentration above which adverse biological effects may frequently occur. Spiked sediments were incubated with a nutritive saline solution, being left in the dark under constant agitation for 7 days. The results showed that, despite the initial sediments colonized by J. maritimus and P. australis displayed significant (p < 0.05) differences in terms of microbial community structure (evaluated by ARISA), they presented similar microbial abundances (estimated by DAPI). Also, in terms of microbial abundance, both sediments showed a similar response to metal addition, with a decrease in number of cells only observed for the higher addition of Cu. Nevertheless, both Cu and Pb, at intermediate metals levels promote a shift in the microbial community structure, with possibly effect on the ecological function of these microbial communities in salt marshes. These changes may affect plants phytoremediation

  19. Marsh-atmosphere CO2 exchange in a New England salt marsh

    NASA Astrophysics Data System (ADS)

    Forbrich, Inke; Giblin, Anne E.

    2015-09-01

    We studied marsh-atmosphere exchange of carbon dioxide in a high marsh dominated salt marsh during the months of May to October in 2012-2014. Tidal inundation at the site occurred only during biweekly spring tides, during which we observed a reduction in fluxes during day and night. We estimated net ecosystem exchange (NEE), gross primary production (GPP), and ecosystem respiration (Reco) using a modified PLIRTLE model, which requires photosynthetically active radiation, temperature, and normalized difference vegetation index (NDVI) as control variables. NDVI decreased during inundation, when the marsh canopy was submerged. Two-time series of NDVI, including and excluding effects of tidal inundation, allowed us to quantify the flux reduction during inundation. The effect of the flux reduction was small (2-4%) at our site, but is likely higher for marshes at a lower elevation. From May to October, GPP averaged -863 g C m-2, Reco averaged 591 g C m-2, and NEE averaged -291 g C m-2. In 2012, which was an exceptionally warm year, we observed an early start of net carbon uptake but higher respiration than in 2013 and 2014 due to higher-air temperature in August. This resulted in the lowest NEE during the study period (-255.9±6.9 g C m-2). The highest seasonal net uptake (-336.5±6.3 g C m-2) was observed in 2013, which was linked to higher rainfall and temperature in July. Mean sea level was very similar during all 3 years which allowed us to isolate the importance of climatic factors.

  20. Salt marsh persistence is threatened by predicted sea-level rise

    NASA Astrophysics Data System (ADS)

    Crosby, Sarah C.; Sax, Dov F.; Palmer, Megan E.; Booth, Harriet S.; Deegan, Linda A.; Bertness, Mark D.; Leslie, Heather M.

    2016-11-01

    Salt marshes buffer coastlines and provide critical ecosystem services from storm protection to food provision. Worldwide, these ecosystems are in danger of disappearing if they cannot increase elevation at rates that match sea-level rise. However, the magnitude of loss to be expected is not known. A synthesis of existing records of salt marsh elevation change was conducted in order to consider the likelihood of their future persistence. This analysis indicates that many salt marshes did not keep pace with sea-level rise in the past century and kept pace even less well over the past two decades. Salt marshes experiencing higher local sea-level rise rates were less likely to be keeping pace. These results suggest that sea-level rise will overwhelm most salt marshes' capacity to maintain elevation. Under the most optimistic IPCC emissions pathway, 60% of the salt marshes studied will be gaining elevation at a rate insufficient to keep pace with sea-level rise by 2100. Without mitigation of greenhouse gas emissions this potential loss could exceed 90%, which will have substantial ecological, economic, and human health consequences.

  1. Remote sensing of wetland conditions in West Coast salt marshes

    NASA Astrophysics Data System (ADS)

    Ustin, Susan L.; Lay, Mui C.; Li, Lin

    2004-11-01

    The objective of the PEEIR (Pacific Estuarine Ecosystem Indicator Research Consortium) program is to develop new indicators for assessing wetland health or condition. As part of PEEIR program we are investigating the use of imaging spectrometry to map and characterize marsh vegetation of several estuarine systems in California. We obtained airborne Advanced Visible Infrared Imaging Spectrometer (AVIRIS) data, an instrument which measures a detailed reflectance spectrum (400-2500nm) for each pixel, over paired tidal marshes, having either a history of exposure to pollution or no known exposure. AVIRIS image data was analyzed based on comparison to field measurements and reflectance changes measured in hydroponic experiments. We report leaf and canopy reflectance measurements of several common plant species of Pacific coast salt marshes exposed to different concentrations of heavy metals (Cd, V) and crude oil contaminants. Species exhibited differential sensitivities to specific contaminants, however in general, Salicornia virginica, the most salt tolerant species and the dominant species in these wetlands (70-90% cover) was most sensitive to metal and petroleum contaminants. Field measurements of canopy reflectance, biomass and vegetation structure were acquired across GPS-located transects at each field site. The AVIRIS data were calibrated to surface reflectance using the FLAASH radiative transfer code and geometrically registered to coordinates using the 1m USGS digital orthophoto quads. AVIRIS results show spatial patterns of plant stress indicators (e.g., reduced chlorophyll and water contents) are consistent with known patterns of contamination in these tidal wetlands.

  2. The influence of Spartina maritima on carbon retention capacity in salt marshes from warm-temperate estuaries.

    PubMed

    Sousa, Ana I; Lillebø, Ana I; Pardal, Miguel A; Caçador, Isabel

    2010-01-01

    Salt marshes constitute highly productive systems playing an important role on ecosystem functions. The aim of this study is to compare the role of Spartina maritima salt marshes on carbon cycling. Thus, four salt marshes located in two mesotidal estuarine systems (Tagus and Mondego, two salt marshes per estuary) were studied. The S. maritima above- and belowground biomass, carbon production, decomposition rates (through a litterbag experiment) and carbon content in the sediment were estimated for a one year period in both systems and compared. In Corroios (located at the Tagus estuary) S. maritima salt marsh had the highest belowground production (1008 gC m(-2) y(-1)), slower decomposition rate (k=0.0024 d(-1)), and the highest carbon content in sediments (750 gC m(-2) y(-1)); and thus, the highest carbon retention capacity. The other three salt marshes had comparatively higher aboveground productions, higher decomposition rates and lower carbon retention capacity. Therefore, Corroios had the most important carbon cycling characteristics. As a whole, results show that differences in carbon cycling in salt marshes depend mostly on its own characteristics and maturity, rather than the system itself. The intrinsic characteristics of the salt marshes, namely the physicochemical conditions determined by the maturity of the system, are more important factors affecting the role of warm-temperate mesotidal salt marshes as carbon sinks. PMID:20304438

  3. The contribution of mangrove expansion to salt marsh loss on the Texas Gulf Coast.

    PubMed

    Armitage, Anna R; Highfield, Wesley E; Brody, Samuel D; Louchouarn, Patrick

    2015-01-01

    Landscape-level shifts in plant species distribution and abundance can fundamentally change the ecology of an ecosystem. Such shifts are occurring within mangrove-marsh ecotones, where over the last few decades, relatively mild winters have led to mangrove expansion into areas previously occupied by salt marsh plants. On the Texas (USA) coast of the western Gulf of Mexico, most cases of mangrove expansion have been documented within specific bays or watersheds. Based on this body of relatively small-scale work and broader global patterns of mangrove expansion, we hypothesized that there has been a recent regional-level displacement of salt marshes by mangroves. We classified Landsat-5 Thematic Mapper images using artificial neural networks to quantify black mangrove (Avicennia germinans) expansion and salt marsh (Spartina alterniflora and other grass and forb species) loss over 20 years across the entire Texas coast. Between 1990 and 2010, mangrove area grew by 16.1 km(2), a 74% increase. Concurrently, salt marsh area decreased by 77.8 km(2), a 24% net loss. Only 6% of that loss was attributable to mangrove expansion; most salt marsh was lost due to conversion to tidal flats or water, likely a result of relative sea level rise. Our research confirmed that mangroves are expanding and, in some instances, displacing salt marshes at certain locations. However, this shift is not widespread when analyzed at a larger, regional level. Rather, local, relative sea level rise was indirectly implicated as another important driver causing regional-level salt marsh loss. Climate change is expected to accelerate both sea level rise and mangrove expansion; these mechanisms are likely to interact synergistically and contribute to salt marsh loss. PMID:25946132

  4. The Contribution of Mangrove Expansion to Salt Marsh Loss on the Texas Gulf Coast

    PubMed Central

    Brody, Samuel D.; Louchouarn, Patrick

    2015-01-01

    Landscape-level shifts in plant species distribution and abundance can fundamentally change the ecology of an ecosystem. Such shifts are occurring within mangrove-marsh ecotones, where over the last few decades, relatively mild winters have led to mangrove expansion into areas previously occupied by salt marsh plants. On the Texas (USA) coast of the western Gulf of Mexico, most cases of mangrove expansion have been documented within specific bays or watersheds. Based on this body of relatively small-scale work and broader global patterns of mangrove expansion, we hypothesized that there has been a recent regional-level displacement of salt marshes by mangroves. We classified Landsat-5 Thematic Mapper images using artificial neural networks to quantify black mangrove (Avicennia germinans) expansion and salt marsh (Spartina alterniflora and other grass and forb species) loss over 20 years across the entire Texas coast. Between 1990 and 2010, mangrove area grew by 16.1 km2, a 74% increase. Concurrently, salt marsh area decreased by 77.8 km2, a 24% net loss. Only 6% of that loss was attributable to mangrove expansion; most salt marsh was lost due to conversion to tidal flats or water, likely a result of relative sea level rise. Our research confirmed that mangroves are expanding and, in some instances, displacing salt marshes at certain locations. However, this shift is not widespread when analyzed at a larger, regional level. Rather, local, relative sea level rise was indirectly implicated as another important driver causing regional-level salt marsh loss. Climate change is expected to accelerate both sea level rise and mangrove expansion; these mechanisms are likely to interact synergistically and contribute to salt marsh loss. PMID:25946132

  5. The contribution of mangrove expansion to salt marsh loss on the Texas Gulf Coast.

    PubMed

    Armitage, Anna R; Highfield, Wesley E; Brody, Samuel D; Louchouarn, Patrick

    2015-01-01

    Landscape-level shifts in plant species distribution and abundance can fundamentally change the ecology of an ecosystem. Such shifts are occurring within mangrove-marsh ecotones, where over the last few decades, relatively mild winters have led to mangrove expansion into areas previously occupied by salt marsh plants. On the Texas (USA) coast of the western Gulf of Mexico, most cases of mangrove expansion have been documented within specific bays or watersheds. Based on this body of relatively small-scale work and broader global patterns of mangrove expansion, we hypothesized that there has been a recent regional-level displacement of salt marshes by mangroves. We classified Landsat-5 Thematic Mapper images using artificial neural networks to quantify black mangrove (Avicennia germinans) expansion and salt marsh (Spartina alterniflora and other grass and forb species) loss over 20 years across the entire Texas coast. Between 1990 and 2010, mangrove area grew by 16.1 km(2), a 74% increase. Concurrently, salt marsh area decreased by 77.8 km(2), a 24% net loss. Only 6% of that loss was attributable to mangrove expansion; most salt marsh was lost due to conversion to tidal flats or water, likely a result of relative sea level rise. Our research confirmed that mangroves are expanding and, in some instances, displacing salt marshes at certain locations. However, this shift is not widespread when analyzed at a larger, regional level. Rather, local, relative sea level rise was indirectly implicated as another important driver causing regional-level salt marsh loss. Climate change is expected to accelerate both sea level rise and mangrove expansion; these mechanisms are likely to interact synergistically and contribute to salt marsh loss.

  6. Consequences of Climate Change, Eutrophication, and Other Anthropogenic Impacts to Coastal Salt Marshes: Multiple Stressors Reduce Resiliency and Sustainability

    EPA Science Inventory

    Coastal salt marshes provide a wide variety of ecosystem services, including habitat for protected vertebrates and ecologically valuable invertebrate fauna, flood protection, and improvements in water quality for adjacent marine and estuarine environments. Here, we consider the ...

  7. ANTHROPOGENIC INFLUENCES ON STREAMS AND THEIR RECEIVING SALT MARSHES

    EPA Science Inventory

    Land use and anthropogenic activities in watersheds affect biological, chemical, and physical conditions in streams and receiving coastal salt marshes. Our objective is to compare indicators of stream condition and riparian vegetation with analagous indicators of the coastal salt...

  8. Factors controlling emissions of dimethylsulphide from salt marshes

    NASA Technical Reports Server (NTRS)

    Dacey, John W. H.; Wakeham, Stuart G.; King, Gary M.

    1987-01-01

    Salt marshes are presently identified as systems exhibiting high area-specific sulfur emission in the form of dimethylsulfide (DMS) and H2S, with the former predominating in vegetated areas of the marshes. Attention is presently given to the distribution of DMS in salt marshes; it is found that this compound primarily arises from physiological processes in the leaves of higher plants, especially the grass species Spartina alterniflora. Uncertainties associated with DMS emission measurements are considered.

  9. Pettaquamscutt Cove Salt Marsh: Environmental Conditions and Historical Ecological Change

    EPA Science Inventory

    Using historic air photos and U.S. Coast Survey maps, historic vegetation changes were identified. Using surveys of vegetation and elevation, we measure elevation of Narrow River salt marshes, and compare it with other salt marshes in Rhode Island and neighboring states. Water ...

  10. Impacts of Multiple Stressors on Southern New England Salt Marshes

    EPA Science Inventory

    In the Northeastern U.S., salt marsh area is in decline. Low sediment supply combined with regionally high rates of sea level rise mean that future salt marsh survival depends primarily on biomass production and organic matter accumulation, which are impacted by high nutrient lo...

  11. Large methyl halide emissions from south Texas salt marshes

    NASA Astrophysics Data System (ADS)

    Rhew, R. C.; Whelan, M. E.; Min, D.-H.

    2014-06-01

    Coastal salt marshes are natural sources of methyl chloride (CH3Cl) and methyl bromide (CH3Br) to the atmosphere, but measured emission rates vary widely by geography. Here we report large methyl halide fluxes from subtropical salt marshes of south Texas. Sites with the halophytic plant, Batis maritima, emitted methyl halides at rates that are orders of magnitude greater than sites containing other vascular plants or macroalgae. B. maritima emissions were generally highest at midday; however, diurnal variability was more pronounced for CH3Br than CH3Cl, and surprisingly high nighttime CH3Cl fluxes were observed in July. Seasonal and intra-site variability were large, even taking into account biomass differences. Overall, these subtropical salt marsh sites show much higher emission rates than temperate salt marshes at similar times of the year, supporting the contention that low-latitude salt marshes are significant sources of CH3Cl and CH3Br.

  12. Large methyl halide emissions from south Texas salt marshes

    NASA Astrophysics Data System (ADS)

    Rhew, R. C.; Whelan, M. E.; Min, D.-H.

    2014-11-01

    Coastal salt marshes are natural sources of methyl chloride (CH3Cl) and methyl bromide (CH3Br) to the atmosphere, but measured emission rates vary widely by geography. Here we report large methyl halide fluxes from subtropical salt marshes of south Texas. Sites with the halophytic plant, Batis maritima, emitted methyl halides at rates that are orders of magnitude greater than sites containing other vascular plants or macroalgae. B. maritima emissions were generally highest at midday; however, diurnal variability was more pronounced for CH3Br than CH3Cl, and surprisingly high nighttime CH3Cl fluxes were observed in July. Seasonal and intra-site variability were large, even taking into account biomass differences. Overall, these subtropical salt marsh sites show much higher emission rates than temperate salt marshes at similar times of the year, supporting the contention that low-latitude salt marshes are significant sources of CH3Cl and CH3Br.

  13. Anthropogenic modification of New England salt marsh landscapes.

    PubMed

    Bertness, Mark D; Ewanchuk, Patrick J; Silliman, Brian Reed

    2002-02-01

    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.

  14. Gross nitrous oxide production drives net nitrous oxide fluxes across a salt marsh landscape.

    PubMed

    Yang, Wendy H; Silver, Whendee L

    2016-06-01

    Sea level rise will change inundation regimes in salt marshes, altering redox dynamics that control nitrification - a potential source of the potent greenhouse gas, nitrous oxide (N2 O) - and denitrification, a major nitrogen (N) loss pathway in coastal ecosystems and both a source and sink of N2 O. Measurements of net N2 O fluxes alone yield little insight into the different effects of redox conditions on N2 O production and consumption. We used in situ measurements of gross N2 O fluxes across a salt marsh elevation gradient to determine how soil N2 O emissions in coastal ecosystems may respond to future sea level rise. Soil redox declined as marsh elevation decreased, with lower soil nitrate and higher ferrous iron in the low marsh compared to the mid and high marshes (P < 0.001 for both). In addition, soil oxygen concentrations were lower in the low and mid-marshes relative to the high marsh (P < 0.001). Net N2 O fluxes differed significantly among marsh zones (P = 0.009), averaging 9.8 ± 5.4 μg N m(-2)  h(-1) , -2.2 ± 0.9 μg N m(-2)  h(-1) , and 0.67 ± 0.57 μg N m(-2)  h(-1) in the low, mid, and high marshes, respectively. Both net N2 O release and uptake were observed in the low and high marshes, but the mid-marsh was consistently a net N2 O sink. Gross N2 O production was highest in the low marsh and lowest in the mid-marsh (P = 0.02), whereas gross N2 O consumption did not differ among marsh zones. Thus, variability in gross N2 O production rates drove the differences in net N2 O flux among marsh zones. Our results suggest that future studies should focus on elucidating controls on the processes producing, rather than consuming, N2 O in salt marshes to improve our predictions of changes in net N2 O fluxes caused by future sea level rise.

  15. Gross nitrous oxide production drives net nitrous oxide fluxes across a salt marsh landscape.

    PubMed

    Yang, Wendy H; Silver, Whendee L

    2016-06-01

    Sea level rise will change inundation regimes in salt marshes, altering redox dynamics that control nitrification - a potential source of the potent greenhouse gas, nitrous oxide (N2 O) - and denitrification, a major nitrogen (N) loss pathway in coastal ecosystems and both a source and sink of N2 O. Measurements of net N2 O fluxes alone yield little insight into the different effects of redox conditions on N2 O production and consumption. We used in situ measurements of gross N2 O fluxes across a salt marsh elevation gradient to determine how soil N2 O emissions in coastal ecosystems may respond to future sea level rise. Soil redox declined as marsh elevation decreased, with lower soil nitrate and higher ferrous iron in the low marsh compared to the mid and high marshes (P < 0.001 for both). In addition, soil oxygen concentrations were lower in the low and mid-marshes relative to the high marsh (P < 0.001). Net N2 O fluxes differed significantly among marsh zones (P = 0.009), averaging 9.8 ± 5.4 μg N m(-2)  h(-1) , -2.2 ± 0.9 μg N m(-2)  h(-1) , and 0.67 ± 0.57 μg N m(-2)  h(-1) in the low, mid, and high marshes, respectively. Both net N2 O release and uptake were observed in the low and high marshes, but the mid-marsh was consistently a net N2 O sink. Gross N2 O production was highest in the low marsh and lowest in the mid-marsh (P = 0.02), whereas gross N2 O consumption did not differ among marsh zones. Thus, variability in gross N2 O production rates drove the differences in net N2 O flux among marsh zones. Our results suggest that future studies should focus on elucidating controls on the processes producing, rather than consuming, N2 O in salt marshes to improve our predictions of changes in net N2 O fluxes caused by future sea level rise. PMID:26718748

  16. Hydrologic modeling as a predictive basis for ecological restoration of salt marshes

    USGS Publications Warehouse

    Roman, C.T.; Garvine, R.W.; Portnoy, J.W.

    1995-01-01

    Roads, bridges, causeways, impoundments, and dikes in the coastal zone often restrict tidal flow to salt marsh ecosystems. A dike with tide control structures, located at the mouth of the Herring River salt marsh estuarine system (Wellfleet, Massachusetts) since 1908, has effectively restricted tidal exchange, causing changes in marsh vegetation composition, degraded water quality, and reduced abundance of fish and macroinvertebrate communities. Restoration of this estuary by reintroduction of tidal exchange is a feasible management alternative. However, restoration efforts must proceed with caution as residential dwellings and a golf course are located immediately adjacent to and in places within the tidal wetland. A numerical model was developed to predict tide height levels for numerous alternative openings through the Herring River dike. Given these model predictions and knowledge of elevations of flood-prone areas, it becomes possible to make responsible decisions regarding restoration. Moreover, tidal flooding elevations relative to the wetland surface must be known to predict optimum conditions for ecological recovery. The tide height model has a universal role, as demonstrated by successful application at a nearby salt marsh restoration site in Provincetown, Massachusetts. Salt marsh restoration is a valuable management tool toward maintaining and enhancing coastal zone habitat diversity. The tide height model presented in this paper will enable both scientists and resource professionals to assign a degree of predictability when designing salt marsh restoration programs.

  17. Threats to Marsh Resources and Mitigation

    EPA Science Inventory

    Salt marshes inhabit low-energy, intertidal shorelines worldwide and are among the most abundant and productive coastal ecosystems. Salt-marsh ecosystems provide a wide array of benefits to coastal populations, including shoreline protection, fishery support, water quality impr...

  18. Salt Marsh Sediment Biogeochemical Response to the BP Blowout.

    PubMed

    Mills, Calista G; McNeal, Karen S

    2014-09-01

    The impact of the blowout on salt marshes was investigated by observing the biogeochemistry in salt marsh sediments along the Gulf Coast. High sulfide levels due to hydrocarbon loading, increased microbial activity, and microbial community shifts can lead to plant browning and mortality. Sediment biogeochemical processes that degrade enriched carbon pools through sulfate reduction are primarily responsible for the biodegradation of spilled hydrocarbons. An assessment of the impact of contamination on salt marshes at Skiff Island, LA, and Cat Island, Marsh Point, and Saltpan Island, MS, was achieved through sediment electrode profiling, microbial community profiling, and quantification of hydrocarbon contamination, which captured the spatial sedimentary biogeochemical response that affects salt marsh productivity. At western locations (Skiff and Cat Islands), total petroleum hydrocarbons (TPHs) ranged from 2183 to 2996 mg kg, which was more than double the TPH concentration observed at eastern locales. At eastern study locations (e.g., Marsh Point), sedimentary pore-water HS concentrations were higher (maximum value = 231 mg L) and detected further up in the sediment column than at western locales (e.g., Skiff Island). Similarly, anaerobic and aerobic microbial activity, as measured by C substrate utilization profiles and well-color development, was as high or higher at eastern locations as compared with western locations. These results indicate that other factors besides location or degree of contamination, perhaps sedimentary dynamics and physical processes specific to each marsh, should be considered when determining salt marsh response to hydrocarbon contamination.

  19. Methane flux from coastal salt marshes

    NASA Astrophysics Data System (ADS)

    Bartlett, K. B.; Harriss, R. C.; Sebacher, D. I.

    1985-06-01

    It is thought that biological methanogenesis in natural and agricultural wetlands and enteric fermentation in animals are the dominant sources of global tropospheric methane. It is pointed out that the anaerobic soils and sediments, where methanogenesis occurs, predominate in coastal marine wetlands. Coastal marine wetlands are generally believed to be approximately equal in area to freshwater wetlands. For this reason, coastal marine wetlands may be a globally significant source of atmospheric methane. The present investigation is concerned with the results of a study of direct measurements of methane fluxes to the atmosphere from salt marsh soils and of indirect determinations of fluxes from tidal creek waters. In addition, measurements of methane distributions in coastal marine wetland sediments and water are presented. The results of the investigation suggest that marine wetlands provide only a minor contribution to atmospheric methane on a global scale.

  20. Methane flux from coastal salt marshes

    NASA Technical Reports Server (NTRS)

    Bartlett, K. B.; Harriss, R. C.; Sebacher, D. I.

    1985-01-01

    It is thought that biological methanogenesis in natural and agricultural wetlands and enteric fermentation in animals are the dominant sources of global tropospheric methane. It is pointed out that the anaerobic soils and sediments, where methanogenesis occurs, predominate in coastal marine wetlands. Coastal marine wetlands are generally believed to be approximately equal in area to freshwater wetlands. For this reason, coastal marine wetlands may be a globally significant source of atmospheric methane. The present investigation is concerned with the results of a study of direct measurements of methane fluxes to the atmosphere from salt marsh soils and of indirect determinations of fluxes from tidal creek waters. In addition, measurements of methane distributions in coastal marine wetland sediments and water are presented. The results of the investigation suggest that marine wetlands provide only a minor contribution to atmospheric methane on a global scale.

  1. TYPES OF SALT MARSH EDGE AND EXPORT OF TROPHIC ENERGY FROM MARSHES TO DEEPER HABITATS

    EPA Science Inventory

    We quantified nekton and estimated trophic export at salt marshes with both erosional and depositional edges at the Goodwin Islands (York River, Virginia, USA). At depositional-edge marshes, we examined trophic flows through quantitative sampling with 1.75 m2 drop rings, and thro...

  2. [Emissions of methyl halides from coastal salt marshes: A review].

    PubMed

    Xie, Wen-xia; Zhao, Quan-sheng; Cui, Yu-qian; Du, Hui-na; Ye, Si-yuan

    2015-11-01

    Methyl halides are the major carrier of halogens in the atmosphere, and they play an important role in tropospheric and stratospheric ozone depletion. Meanwhile, methyl halides can act as greenhouse gases in the atmosphere, and they are also environmentally significant because of their toxicity. Coastal salt marshes, the important intertidal ecosystems at the land-ocean interface, have been considered to be a large potential natural source of methyl halides. In this paper, the research status of the natural source or sink of methyl halides, the mechanisms of their emission from coastal salt marshes and affecting factors were summarized. In view of this, the following research fields need to be strengthened in the future: 1) Long time-scale and large region-range researches about the emission of methyl halides and the evaluation of their source and sink function, 2) Accurate quantification of contribution rates of different plant species and various biological types to fluxes of methyl halides, 3) Further researches on effects of the tidal fluctuation process and flooding duration on methyl halides emission, 4) Effects of the global change and human activities on methyl halides emission. PMID:26915215

  3. Indirect Human Impacts Reverse Centuries of Carbon Sequestration and Salt Marsh Accretion

    PubMed Central

    Coverdale, Tyler C.; Brisson, Caitlin P.; Young, Eric W.; Yin, Stephanie F.; Donnelly, Jeffrey P.; Bertness, Mark D.

    2014-01-01

    Direct and indirect human impacts on coastal ecosystems have increased over the last several centuries, leading to unprecedented degradation of coastal habitats and loss of ecological services. Here we document a two-century temporal disparity between salt marsh accretion and subsequent loss to indirect human impacts. Field surveys, manipulative experiments and GIS analyses reveal that crab burrowing weakens the marsh peat base and facilitates further burrowing, leading to bank calving, disruption of marsh accretion, and a loss of over two centuries of sequestered carbon from the marsh edge in only three decades. Analogous temporal disparities exist in other systems and are a largely unrecognized obstacle in attaining sustainable ecosystem services in an increasingly human impacted world. In light of the growing threat of indirect impacts worldwide and despite uncertainties in the fate of lost carbon, we suggest that estimates of carbon emissions based only on direct human impacts may significantly underestimate total anthropogenic carbon emissions. PMID:24675669

  4. A WATERSHED APPROACH TO UNDERSTANDING ANTHROPOGENIC INFLUENCES ON STREAMS AND THEIR RECEIVING SALT MARSHES

    EPA Science Inventory

    Fresh and saltwater ecosystems have customarily been assessed separately. By taking a watershed approach, we are exploring the linkages between stream conditions, the biotic integrity of coastal salt marshes, and land use. Watersheds provide a pathway for point and nonpoint pollu...

  5. A dynamic nitrogen budget model of a Pacific Northwest salt marsh

    EPA Science Inventory

    The role of salt marshes as either nitrogen sinks or sources in relation to their adjacent estuaries has been a focus of ecosystem service research for many decades. The complex hydrology of these systems is driven by tides, upland surface runoff, precipitation, evapotranspirati...

  6. Oregon Salt Marshes: How Blue are They? November 12, 2015

    EPA Science Inventory

    We quantified carbon and nitrogen accumulation rates in salt marshes at 135 plots distributed across eight estuaries in Oregon, USA. Net carbon and nitrogen accumulation rates were quantified by measuring the content of these constituents in sediment that accumulated in marsh ha...

  7. Tidal salt marshes of the southeast Atlantic Coast: A community profile

    SciTech Connect

    Wiegert, R.G.; Freeman, B.J.

    1990-09-01

    This report is part of a series of community profiles on the ecology of wetland and marine communities. This particular profile considers tidal marshes of the southeastern Atlantic coast, from North Carolina south to northern Florida. Alone among the earth's ecosystems, coastal communities are subjected to a bidirectional flooding sometimes occurring twice each day; this flooding affects successional development, species composition, stability, and productivity. In the tidally influenced salt marsh, salinity ranges from less than 1 ppt to that of seawater. Dominant plant species include cordgrasses (Spartina alterniflora and S. cynosuroides), black needlerush (Juncus romerianus), and salt marsh bulrush (Scirpus robustus). Both terrestrail and aquatic animals occur in salt marshes and include herons, egrets ospreys (Pandion haliaetus), bald eagles (Haliaeetus leucocephalus), alligators (Alligator Mississippiensis), manatees (Trichecus manatus), oysters, mussels, and fiddler crabs. Currently, the only significant direct commercial use of the tidal salt marshes is by crabbers seeking the blue crab Callinectes sapidus, but the marshes are quite important recreationally, aesthetically, and educationally. 151 refs., 45 figs., 6 tabs.

  8. Post-mortem ecosystem engineering by oysters creates habitat for a rare marsh plant.

    PubMed

    Guo, Hongyu; Pennings, Steven C

    2012-11-01

    Oysters are ecosystem engineers in marine ecosystems, but the functions of oyster shell deposits in intertidal salt marshes are not well understood. The annual plant Suaeda linearis is associated with oyster shell deposits in Georgia salt marshes. We hypothesized that oyster shell deposits promoted the distribution of Suaeda linearis by engineering soil conditions unfavorable to dominant salt marsh plants of the region (the shrub Borrichia frutescens, the rush Juncus roemerianus, and the grass Spartina alterniflora). We tested this hypothesis using common garden pot experiments and field transplant experiments. Suaeda linearis thrived in Borrichia frutescens stands in the absence of neighbors, but was suppressed by Borrichia frutescens in the with-neighbor treatment, suggesting that Suaeda linearis was excluded from Borrichia frutescens stands by interspecific competition. Suaeda linearis plants all died in Juncus roemerianus and Spartina alterniflora stands, regardless of neighbor treatments, indicating that Suaeda linearis is excluded from these habitats by physical stress (likely water-logging). In contrast, Borrichia frutescens, Juncus roemerianus, and Spartina alterniflora all performed poorly in Suaeda linearis stands regardless of neighbor treatments, probably due to physical stresses such as low soil water content and low organic matter content. Thus, oyster shell deposits play an important ecosystem engineering role in influencing salt marsh plant communities by providing a unique niche for Suaeda linearis, which otherwise would be rare or absent in salt marshes in the southeastern US. Since the success of Suaeda linearis is linked to the success of oysters, efforts to protect and restore oyster reefs may also benefit salt marsh plant communities.

  9. Specificity of Salt Marsh Diazotrophs for Vegetation Zones and Plant Hosts: Results from a North American marsh

    PubMed Central

    Lovell, Charles R.; Davis, Debra A.

    2012-01-01

    Salt marshes located on the east coast of temperate North America are highly productive, typically nitrogen-limited, and support diverse assemblages of free-living nitrogen fixing (diazotrophic) bacteria. This article reviews and analyzes data from North Inlet estuary (SC, USA), addressing diazotroph assemblage structure and the influence of plant host and environmental conditions on the assemblage. The North Inlet estuary is a salt marsh ecosystem in which anthropogenic influences are minimal and the distributions of diazotrophs are governed by the natural biota and dynamics of the system. Denaturing gradient gel electrophoresis fingerprinting and phylogenetic analyses of recovered sequences demonstrated that the distributions of some diazotrophs reflect plant host specificity and that diazotroph assemblages distributed across marsh gradients are also heavily influenced by edaphic conditions. Broadly distributed diazotrophs that are capable of maintaining populations under all environmental conditions spanning such gradients are also present in these assemblages. Statistical analyses indicate that the structures of diazotroph assemblages in different vegetation zones are significantly (p < 0.01) different. New data presented here demonstrate the heterogeneity of salt marsh rhizosphere microenvironments, and corroborate previous findings from different plant hosts growing at several locations within this estuary. The data from these collected works support the hypothesis that the biogeography of microorganisms is non-random and these biogeographic patterns are predictable. PMID:22438851

  10. On the Lateral Retreat of Salt Marshes: Field Monitoring in the Venice Lagoon (Italy)

    NASA Astrophysics Data System (ADS)

    Solari, L.

    2015-12-01

    Salt marshes are geomorphic structures located in ecotone environments such as lagoon and estuaries, providing lot of ecosystem services to local population. In the last decades they are disappearing due to several factors such as sea level rise, subsidence and edge erosion due to surface waves. The latter is likely the chief mechanism modeling marsh boundaries and leading to the loss of wide marsh areas. In the case of the Venice Lagoon, from the beginning of the last century, the whole salt marsh surface has more than halved and trends indicate that the salt marshes might completely disappear over the next 50 years. Here, we present a field monitoring activity on a retreating salt marsh located in the north part of the Lagoon of Venice (Italy). The marsh is subject to North-East (Bora) wind. Marsh area loss during the last decades has been documented through the comparison of georeferenced aerial photographs showing a retreat rate of the order of 1 m/year. Field measurements started by the end of November 2013 and consist of: salt marsh bank geometry at different cross-sections and wave climate in the lagoon about 30 m in front of the salt marsh. Erosion data are obtained by means of erosion pins located horizontally on the marsh scarp; at higher banks (about 0.9 m), two pins are located along the same vertical direction, for lower banks (about 0.4 m), only one pin is employed. Significant wave height has been measured during three storm surges by means of pressure transducers. The measured wave climate in front of the bank was then put into relationship with the offshore wave climate estimated using wind data (intensity and direction) and bathymetric data. Wind intensity and direction is measured hourly by several measurement stations located in the Lagoon of Venice. In this way, it is possible to extrapolate wave climate hourly at the monitored marsh and calculate the wave power that acted on the bank in a given time interval. Field survey revealed that the

  11. Winter climate change and coastal wetland foundation species: salt marshes vs. mangrove forests in the southeastern United States.

    PubMed

    Osland, Michael J; Enwright, Nicholas; Day, Richard H; Doyle, Thomas W

    2013-05-01

    We live in an era of unprecedented ecological change in which ecologists and natural resource managers are increasingly challenged to anticipate and prepare for the ecological effects of future global change. In this study, we investigated the potential effect of winter climate change upon salt marsh and mangrove forest foundation species in the southeastern United States. Our research addresses the following three questions: (1) What is the relationship between winter climate and the presence and abundance of mangrove forests relative to salt marshes; (2) How vulnerable are salt marshes to winter climate change-induced mangrove forest range expansion; and (3) What is the potential future distribution and relative abundance of mangrove forests under alternative winter climate change scenarios? We developed simple winter climate-based models to predict mangrove forest distribution and relative abundance using observed winter temperature data (1970-2000) and mangrove forest and salt marsh habitat data. Our results identify winter climate thresholds for salt marsh-mangrove forest interactions and highlight coastal areas in the southeastern United States (e.g., Texas, Louisiana, and parts of Florida) where relatively small changes in the intensity and frequency of extreme winter events could cause relatively dramatic landscape-scale ecosystem structural and functional change in the form of poleward mangrove forest migration and salt marsh displacement. The ecological implications of these marsh-to-mangrove forest conversions are poorly understood, but would likely include changes for associated fish and wildlife populations and for the supply of some ecosystem goods and services.

  12. Winter climate change and coastal wetland foundation species: salt marshes vs. mangrove forests in the southeastern United States.

    PubMed

    Osland, Michael J; Enwright, Nicholas; Day, Richard H; Doyle, Thomas W

    2013-05-01

    We live in an era of unprecedented ecological change in which ecologists and natural resource managers are increasingly challenged to anticipate and prepare for the ecological effects of future global change. In this study, we investigated the potential effect of winter climate change upon salt marsh and mangrove forest foundation species in the southeastern United States. Our research addresses the following three questions: (1) What is the relationship between winter climate and the presence and abundance of mangrove forests relative to salt marshes; (2) How vulnerable are salt marshes to winter climate change-induced mangrove forest range expansion; and (3) What is the potential future distribution and relative abundance of mangrove forests under alternative winter climate change scenarios? We developed simple winter climate-based models to predict mangrove forest distribution and relative abundance using observed winter temperature data (1970-2000) and mangrove forest and salt marsh habitat data. Our results identify winter climate thresholds for salt marsh-mangrove forest interactions and highlight coastal areas in the southeastern United States (e.g., Texas, Louisiana, and parts of Florida) where relatively small changes in the intensity and frequency of extreme winter events could cause relatively dramatic landscape-scale ecosystem structural and functional change in the form of poleward mangrove forest migration and salt marsh displacement. The ecological implications of these marsh-to-mangrove forest conversions are poorly understood, but would likely include changes for associated fish and wildlife populations and for the supply of some ecosystem goods and services. PMID:23504931

  13. Evaluation of salt marsh hydrology using radium as a tracer

    SciTech Connect

    Bollinger, M.S. ); Moore, W.S. )

    1993-05-01

    Radium isotopes provide unique and important information concerning water exchange in a salt marsh-tidal creek system. Seasonal radium data collected over five tidal cycles from a creek draining a South Carolina salt marsh, radium and thorium data from the adjacent marsh sediments, and interstitial water radium data from the drainage basin are modeled to yield residence times of water in the upper 10 cm of the marsh sediments ranging from less than one to twenty-six hours. Water residence times derived from chambers which directly measure the flux of Ra isotopes to the creek waters agree well with these calculated interstitial water turnover times. Dissolved radium activities in the tidal creek were greater during the summer than during other times of the year. The authors suspect that seasonal changes in the storage of organic carbon and rates of bioturbation lead to net reduction of radium carrier phases in the marsh sediments during the summer. 18 refs., 4 figs., 7 tabs.

  14. Mangrove expansion and salt marsh decline at mangrove poleward limits.

    PubMed

    Saintilan, Neil; Wilson, Nicholas C; Rogers, Kerrylee; Rajkaran, Anusha; Krauss, Ken W

    2014-01-01

    Mangroves are species of halophytic intertidal trees and shrubs derived from tropical genera and are likely delimited in latitudinal range by varying sensitivity to cold. There is now sufficient evidence that mangrove species have proliferated at or near their poleward limits on at least five continents over the past half century, at the expense of salt marsh. Avicennia is the most cold-tolerant genus worldwide, and is the subject of most of the observed changes. Avicennia germinans has extended in range along the USA Atlantic coast and expanded into salt marsh as a consequence of lower frost frequency and intensity in the southern USA. The genus has also expanded into salt marsh at its southern limit in Peru, and on the Pacific coast of Mexico. Mangroves of several species have expanded in extent and replaced salt marsh where protected within mangrove reserves in Guangdong Province, China. In south-eastern Australia, the expansion of Avicennia marina into salt marshes is now well documented, and Rhizophora stylosa has extended its range southward, while showing strong population growth within estuaries along its southern limits in northern New South Wales. Avicennia marina has extended its range southwards in South Africa. The changes are consistent with the poleward extension of temperature thresholds coincident with sea-level rise, although the specific mechanism of range extension might be complicated by limitations on dispersal or other factors. The shift from salt marsh to mangrove dominance on subtropical and temperate shorelines has important implications for ecological structure, function, and global change adaptation.

  15. Impacts of the Deepwater Horizon Oil Spill on Salt Marsh Periwinkles (Littoraria irrorata).

    PubMed

    Zengel, Scott; Montague, Clay L; Pennings, Steven C; Powers, Sean P; Steinhoff, Marla; Fricano, Gail; Schlemme, Claire; Zhang, Mengni; Oehrig, Jacob; Nixon, Zachary; Rouhani, Shahrokh; Michel, Jacqueline

    2016-01-19

    Deepwater Horizon was the largest marine oil spill in U.S. waters, oiling large expanses of coastal wetland shorelines. We compared marsh periwinkle (Littoraria irrorata) density and shell length at salt marsh sites with heavy oiling to reference conditions ∼16 months after oiling. We also compared periwinkle density and size among oiled sites with and without shoreline cleanup treatments. Densities of periwinkles were reduced by 80-90% at the oiled marsh edge and by 50% in the oiled marsh interior (∼9 m inland) compared to reference, with greatest numerical losses of periwinkles in the marsh interior, where densities were naturally higher. Shoreline cleanup further reduced adult snail density as well as snail size. Based on the size of adult periwinkles observed coupled with age and growth information, population recovery is projected to take several years once oiling and habitat conditions in affected areas are suitable to support normal periwinkle life-history functions. Where heavily oiled marshes have experienced accelerated erosion as a result of the spill, these habitat impacts would represent additional losses of periwinkles. Losses of marsh periwinkles would likely affect other ecosystem processes and attributes, including organic matter and nutrient cycling, marsh-estuarine food chains, and multiple species that prey on periwinkles.

  16. Impacts of the Deepwater Horizon Oil Spill on Salt Marsh Periwinkles (Littoraria irrorata).

    PubMed

    Zengel, Scott; Montague, Clay L; Pennings, Steven C; Powers, Sean P; Steinhoff, Marla; Fricano, Gail; Schlemme, Claire; Zhang, Mengni; Oehrig, Jacob; Nixon, Zachary; Rouhani, Shahrokh; Michel, Jacqueline

    2016-01-19

    Deepwater Horizon was the largest marine oil spill in U.S. waters, oiling large expanses of coastal wetland shorelines. We compared marsh periwinkle (Littoraria irrorata) density and shell length at salt marsh sites with heavy oiling to reference conditions ∼16 months after oiling. We also compared periwinkle density and size among oiled sites with and without shoreline cleanup treatments. Densities of periwinkles were reduced by 80-90% at the oiled marsh edge and by 50% in the oiled marsh interior (∼9 m inland) compared to reference, with greatest numerical losses of periwinkles in the marsh interior, where densities were naturally higher. Shoreline cleanup further reduced adult snail density as well as snail size. Based on the size of adult periwinkles observed coupled with age and growth information, population recovery is projected to take several years once oiling and habitat conditions in affected areas are suitable to support normal periwinkle life-history functions. Where heavily oiled marshes have experienced accelerated erosion as a result of the spill, these habitat impacts would represent additional losses of periwinkles. Losses of marsh periwinkles would likely affect other ecosystem processes and attributes, including organic matter and nutrient cycling, marsh-estuarine food chains, and multiple species that prey on periwinkles. PMID:26713547

  17. Degradation and resilience in Louisiana salt marshes after the BP–Deepwater Horizon oil spill

    PubMed Central

    Silliman, Brian R.; van de Koppel, Johan; McCoy, Michael W.; Diller, Jessica; Kasozi, Gabriel N.; Earl, Kamala; Adams, Peter N.; Zimmerman, Andrew R.

    2012-01-01

    More than 2 y have passed since the BP–Deepwater Horizon oil spill in the Gulf of Mexico, yet we still have little understanding of its ecological impacts. Examining effects of this oil spill will generate much-needed insight into how shoreline habitats and the valuable ecological services they provide (e.g., shoreline protection) are affected by and recover from large-scale disturbance. Here we report on not only rapid salt-marsh recovery (high resilience) but also permanent marsh area loss after the BP–Deepwater Horizon oil spill. Field observations, experimental manipulations, and wave-propagation modeling reveal that (i) oil coverage was primarily concentrated on the seaward edge of marshes; (ii) there were thresholds of oil coverage that were associated with severity of salt-marsh damage, with heavy oiling leading to plant mortality; (iii) oil-driven plant death on the edges of these marshes more than doubled rates of shoreline erosion, further driving marsh platform loss that is likely to be permanent; and (iv) after 18 mo, marsh grasses have largely recovered into previously oiled, noneroded areas, and the elevated shoreline retreat rates observed at oiled sites have decreased to levels at reference marsh sites. This paper highlights that heavy oil coverage on the shorelines of Louisiana marshes, already experiencing elevated retreat because of intense human activities, induced a geomorphic feedback that amplified this erosion and thereby set limits to the recovery of otherwise resilient vegetation. It thus warns of the enhanced vulnerability of already degraded marshes to heavy oil coverage and provides a clear example of how multiple human-induced stressors can interact to hasten ecosystem decline. PMID:22733752

  18. Degradation and resilience in Louisiana salt marshes after the BP-Deepwater Horizon oil spill.

    PubMed

    Silliman, Brian R; van de Koppel, Johan; McCoy, Michael W; Diller, Jessica; Kasozi, Gabriel N; Earl, Kamala; Adams, Peter N; Zimmerman, Andrew R

    2012-07-10

    More than 2 y have passed since the BP-Deepwater Horizon oil spill in the Gulf of Mexico, yet we still have little understanding of its ecological impacts. Examining effects of this oil spill will generate much-needed insight into how shoreline habitats and the valuable ecological services they provide (e.g., shoreline protection) are affected by and recover from large-scale disturbance. Here we report on not only rapid salt-marsh recovery (high resilience) but also permanent marsh area loss after the BP-Deepwater Horizon oil spill. Field observations, experimental manipulations, and wave-propagation modeling reveal that (i) oil coverage was primarily concentrated on the seaward edge of marshes; (ii) there were thresholds of oil coverage that were associated with severity of salt-marsh damage, with heavy oiling leading to plant mortality; (iii) oil-driven plant death on the edges of these marshes more than doubled rates of shoreline erosion, further driving marsh platform loss that is likely to be permanent; and (iv) after 18 mo, marsh grasses have largely recovered into previously oiled, noneroded areas, and the elevated shoreline retreat rates observed at oiled sites have decreased to levels at reference marsh sites. This paper highlights that heavy oil coverage on the shorelines of Louisiana marshes, already experiencing elevated retreat because of intense human activities, induced a geomorphic feedback that amplified this erosion and thereby set limits to the recovery of otherwise resilient vegetation. It thus warns of the enhanced vulnerability of already degraded marshes to heavy oil coverage and provides a clear example of how multiple human-induced stressors can interact to hasten ecosystem decline. PMID:22733752

  19. Degradation and resilience in Louisiana salt marshes after the BP-Deepwater Horizon oil spill.

    PubMed

    Silliman, Brian R; van de Koppel, Johan; McCoy, Michael W; Diller, Jessica; Kasozi, Gabriel N; Earl, Kamala; Adams, Peter N; Zimmerman, Andrew R

    2012-07-10

    More than 2 y have passed since the BP-Deepwater Horizon oil spill in the Gulf of Mexico, yet we still have little understanding of its ecological impacts. Examining effects of this oil spill will generate much-needed insight into how shoreline habitats and the valuable ecological services they provide (e.g., shoreline protection) are affected by and recover from large-scale disturbance. Here we report on not only rapid salt-marsh recovery (high resilience) but also permanent marsh area loss after the BP-Deepwater Horizon oil spill. Field observations, experimental manipulations, and wave-propagation modeling reveal that (i) oil coverage was primarily concentrated on the seaward edge of marshes; (ii) there were thresholds of oil coverage that were associated with severity of salt-marsh damage, with heavy oiling leading to plant mortality; (iii) oil-driven plant death on the edges of these marshes more than doubled rates of shoreline erosion, further driving marsh platform loss that is likely to be permanent; and (iv) after 18 mo, marsh grasses have largely recovered into previously oiled, noneroded areas, and the elevated shoreline retreat rates observed at oiled sites have decreased to levels at reference marsh sites. This paper highlights that heavy oil coverage on the shorelines of Louisiana marshes, already experiencing elevated retreat because of intense human activities, induced a geomorphic feedback that amplified this erosion and thereby set limits to the recovery of otherwise resilient vegetation. It thus warns of the enhanced vulnerability of already degraded marshes to heavy oil coverage and provides a clear example of how multiple human-induced stressors can interact to hasten ecosystem decline.

  20. Salt marsh stability modelled in relation to sea level rise

    NASA Astrophysics Data System (ADS)

    Bartholdy, Jesper; Bartholdy, Anders T.; Kroon, Aart

    2010-05-01

    Accretion on a natural backbarrier salt marsh was modeled as a function of high tide level, initial salt marsh level and distance to the source. Calibration of the model was based on up to ca 80 year old marker horizons, supplemented by 210Pb/137Cs datings and subsequent measurements of clay thickness. Autocompaction was incorporated in the model, and shown to play a major role for the translation of accretion rates measured as length per unit time to accumulation rates measured as mass per area per unit time. This is important, even for shallow salt marsh deposits for which it is demonstrated that mass depth down core can be directly related to the bulk dry density of the surface layer by means of a logarithmic function. The results allow for an evaluation of the use of marker horizons in the topmost layers and show that it is important to know the level of the marker in relation to the salt marsh base. In general, deeper located markers will indicate successively smaller accretion rates with the same sediment input. Thus, stability analysis made on the basis of newly established marker horizons will be biased and indicate salt marsh stabilities far above the correct level. Running the model with a constant sea level revealed that balance between the inner and the outer salt marsh deposition can not be achieved within a reasonable time scale. Likewise it is shown that only one specific sea level rise provides equilibrium for a given location on the salt marsh. With a higher sea level rise, the marsh at the specific location will eventually drown, whereas - with a sea level rise below this level - it will grow towards the top of the rising tidal frame. The short term variation of salt marsh accretion was found to correlate well with variations in the North Atlantic Oscillation - the NAO winter index. Comparisons between the geomorphological development of wind tide affected salt marshes, like those present on the Danish North Sea coasts, and primary astronomically

  1. Comparative Geomorphology of Salt and Tidal Freshwater Marsh Environments

    NASA Astrophysics Data System (ADS)

    Pasternack, G. B.

    2002-05-01

    Temperate estuaries include a spectrum of coastal marshes ranging from highly saline near the ocean to fresh in tributaries with substantial watershed drainage. While the hydrologic, sedimentary, and geomorphic dynamics of salt marshes have been thoroughly investigated, those aspects of tidal freshwater marshes have only begun to be addressed. Based on a recent burst in research on tidal freshwater systems in Chesapeake Bay by different universities, an attempt is made here to provide comparative geomorphology. In terms of similarities, both have tidal channels whose hydraulic geometry is primarily controlled by the tidal prism. Both show decreasing sedimentation and increasing organics with elevation and distance from channels. At seasonal to interannual time scales, the morphodynamics of both show similarities in the interplay among hydroperiod, vegetation, and geomorphology. Rather than simply evolving from youth to maturity, both systems exhibit strong evidence for dynamic equilibrium between process and morphology. Despite these similarities, there are key differences that motivate further research of tidal freshwater marshes. First, whereas salt marshes are limited by sediment supply, tidal fresh ones may not be limited depending on upstream basin size. E.g., fringing marshes along Pumunkey River have very low sediment supply, while deltaic marshes in Bush River and Sassafras River are not supply-limited. Instead, the growth of deltaic fresh marshes is transport limited, as winds and tides can only generate low momentum and turbulence for sediment transport. As illustrated in multiple systems, a constant availability of sediment leads to higher sedimentation in fresh marshes. Second, in high latitude salt marshes where the tidal range is large and the climate cold, ice acts as a strong erosional agent. In fresh marshes, ice serves to sequester sediment and buffer the erosional impact of autumnal vegetation dieback. Third, the high spatial variation in plant

  2. Salt marshes: An important coastal sink for dissolved uranium

    SciTech Connect

    Church, T.M.; Sarin, M.M.; Fleisher, M.Q.; Ferdelman, T.G.

    1996-10-01

    The global budget for marine uranium demands another geochemical sink other than deep-sea systems, and the coastal environment may host some or all of this missing sink. In a previous paper, we have shown that some large subtidal estuaries are seasonal summer sinks at low salinities. In this paper, we show that intertidal salt marshes are even stronger sinks at all salinities, if for somewhat different reasons. Uranium was sampled in dissolved and particulate fractions over several tidal cycles and seasons for a lower Delaware Bay salt marsh (Canary Creek, Lewes, Delaware, USA), and uniquely, during summer months, the dissolved uranium is nonconservative. Moreover, because uranium extraction is greater on higher tides and occurs over the entire salinity gradient, this processing appears associated with surface of vegetated high marsh, We hypothesize that either (1) uranium scavenging occurs during the process of tidal mixing and attendant flocculation of humic acids and iron oxides-favoring this process is the presence of sulfonate complexes in salt marsh humic substances, and iron coprecipitation during its extensive redox cycling in the salt marsh-or (2) uranium extraction occurs at the marsh surface during extensive flooding of the salt marsh surface sediments-favoring this process is the increase in sulfuric acidity at the summer salt marsh surface that could destabilize the tetracarbonate species of U(VI). The latter option is favored by both field observations of maximum removal at the surface during the spring and summer tide conditions, and selective extraction of sediment phases where uranium is found as adsorbed and complexed forms in the ascorbate-citrate and humic acid fractions, respectively. Mass balance calculations show that under steady-state conditions, nearly two-thirds of the uranium extracted from tidal waters is retained in the sediments, while one-third is exported as U-enriched particles during ebbing tides. 41 refs., 7 figs., 3 tabs.

  3. Fluoride pollution in a salt marsh: movement between soil, vegetation, and sheep

    SciTech Connect

    Baars, A.J.; van Beek, H.; Spierenburg, T.J.; de Graaf, G.J.; Beeftink, W.G.; Nieuwenhuize, J.; Boom, J.; Pekelder, J.J.

    1987-12-01

    The river Scheldt (southwestern part of The Netherlands) is responsible for a considerable pollution of its estuary with organic and inorganic waste, which becomes manifest particularly in the salt marshes. Of these marshes, the 3400 ha nature reserve of the Saeftinge sale marsh constitutes a representative example of such a valuable tidal brackish ecosystem. This marsh is partly grazed by sheep, thus contributing to its original character and assisting in the preservation of the local flora and fauna. Preceding reports indicated a significant degree of contamination with heavy metals, which were shown to enter food chains. The present study focuses on fluoride, an environmental contaminant known to be spread by water and air, and, although assumed to be beneficial in small quantities, a potential threat for plants and animals, particularly herbivores.

  4. Effect of dominant Spartina species on salt marsh detritus production in SW Atlantic estuaries

    NASA Astrophysics Data System (ADS)

    Montemayor, Diana I.; Addino, Mariana; Fanjul, Eugenia; Escapa, Mauricio; Alvarez, M. Fernanda; Botto, Florencia; Iribarne, Oscar O.

    2011-08-01

    Two cordgrass species of the genus Spartina cohabit in SW Atlantic (southern Brazil 31º48' S to Argentinean Patagonia, 43º20' S) salt marshes. Some salt marshes are dominated by the dense-flowered cordgrass Spartina densiflora (which inhabits the upper intertidal level) and others by the smooth cordgrass Spartina alterniflora (which inhabits the lower intertidal level). We investigated how the different species dominance affects the detritus dynamics in the Bahia Blanca estuary (38º47' S, 62º20' W Argentina). Field measurements of annual detritus production using destructive methods show that both plants are similar. However, detritus of S. alterniflora shows higher decomposition rates than that of S. densiflora. This difference may be due to a larger N content, lower lignocellulose content and lower C/N ratio of S. alternifora when compared with S. densiflora. Moreover, field sampling shows that S. alterniflora has a larger amount of trapped litter that, according to the litterbag method, has higher decomposition rates. Therefore it is highly likely that S. alterniflora salt marshes contribute towards more profitable detritus for estuarine food webs than marshes dominated by S. densiflora. These results illustrate that the composition of the coastal plant community can determine the quality and profitability of the detritus that support estuarine food webs. They also illustrate that salt marshes belonging to a same biogeographic group and even coexisting in great proximity can have very different ecosystemic roles.

  5. Herbivory Drives the Spread of Salt Marsh Die-Off

    PubMed Central

    Bertness, Mark D.; Brisson, Caitlin P.; Bevil, Matthew C.; Crotty, Sinead M.

    2014-01-01

    Salt marsh die-off is a Western Atlantic conservation problem that has recently spread into Narragansett Bay, Rhode Island, USA. It has been hypothesized to be driven by: 1) eutrophication decreasing plant investment into belowground biomass causing plant collapse, 2) boat wakes eroding creek banks, 3) pollution or disease affecting plant health, 4) substrate hardness controlling herbivorous crab distributions and 5) trophic dysfunction releasing herbivorous crabs from predator control. To distinguish between these hypotheses we quantified these variables at 14 Narragansett Bay salt marshes where die-off intensity ranged from <5% to nearly 98%. Nitrogen availability, wave intensity and plant growth did not explain any variation in die-off. Herbivory explained 73% of inter-site variation in die-off and predator control of herbivores and substrate hardness also varied significantly with die-off. This suggests that salt marsh die-off is being largely driven by intense herbivory via the release of herbivorous crabs from predator control. Our results and those from other marsh systems suggest that consumer control may not simply be a factor to consider in marsh conservation, but with widespread predator depletion impacting near shore habitats globally, trophic dysfunction and runaway consumption may be the largest and most urgent management challenge for salt marsh conservation. PMID:24651837

  6. Herbivory drives the spread of salt marsh die-off.

    PubMed

    Bertness, Mark D; Brisson, Caitlin P; Bevil, Matthew C; Crotty, Sinead M

    2014-01-01

    Salt marsh die-off is a Western Atlantic conservation problem that has recently spread into Narragansett Bay, Rhode Island, USA. It has been hypothesized to be driven by: 1) eutrophication decreasing plant investment into belowground biomass causing plant collapse, 2) boat wakes eroding creek banks, 3) pollution or disease affecting plant health, 4) substrate hardness controlling herbivorous crab distributions and 5) trophic dysfunction releasing herbivorous crabs from predator control. To distinguish between these hypotheses we quantified these variables at 14 Narragansett Bay salt marshes where die-off intensity ranged from <5% to nearly 98%. Nitrogen availability, wave intensity and plant growth did not explain any variation in die-off. Herbivory explained 73% of inter-site variation in die-off and predator control of herbivores and substrate hardness also varied significantly with die-off. This suggests that salt marsh die-off is being largely driven by intense herbivory via the release of herbivorous crabs from predator control. Our results and those from other marsh systems suggest that consumer control may not simply be a factor to consider in marsh conservation, but with widespread predator depletion impacting near shore habitats globally, trophic dysfunction and runaway consumption may be the largest and most urgent management challenge for salt marsh conservation.

  7. Nutrient enrichment induces dormancy and decreases diversity of active bacteria in salt marsh sediments

    PubMed Central

    Kearns, Patrick J.; Angell, John H.; Howard, Evan M.; Deegan, Linda A.; Stanley, Rachel H. R.; Bowen, Jennifer L.

    2016-01-01

    Microorganisms control key biogeochemical pathways, thus changes in microbial diversity, community structure and activity can affect ecosystem response to environmental drivers. Understanding factors that control the proportion of active microbes in the environment and how they vary when perturbed is critical to anticipating ecosystem response to global change. Increasing supplies of anthropogenic nitrogen to ecosystems globally makes it imperative that we understand how nutrient supply alters active microbial communities. Here we show that nitrogen additions to salt marshes cause a shift in the active microbial community despite no change in the total community. The active community shift causes the proportion of dormant microbial taxa to double, from 45 to 90%, and induces diversity loss in the active portion of the community. Our results suggest that perturbations to salt marshes can drastically alter active microbial communities, however these communities may remain resilient by protecting total diversity through increased dormancy. PMID:27666199

  8. Nutrient enrichment induces dormancy and decreases diversity of active bacteria in salt marsh sediments

    NASA Astrophysics Data System (ADS)

    Kearns, Patrick J.; Angell, John H.; Howard, Evan M.; Deegan, Linda A.; Stanley, Rachel H. R.; Bowen, Jennifer L.

    2016-09-01

    Microorganisms control key biogeochemical pathways, thus changes in microbial diversity, community structure and activity can affect ecosystem response to environmental drivers. Understanding factors that control the proportion of active microbes in the environment and how they vary when perturbed is critical to anticipating ecosystem response to global change. Increasing supplies of anthropogenic nitrogen to ecosystems globally makes it imperative that we understand how nutrient supply alters active microbial communities. Here we show that nitrogen additions to salt marshes cause a shift in the active microbial community despite no change in the total community. The active community shift causes the proportion of dormant microbial taxa to double, from 45 to 90%, and induces diversity loss in the active portion of the community. Our results suggest that perturbations to salt marshes can drastically alter active microbial communities, however these communities may remain resilient by protecting total diversity through increased dormancy.

  9. Carbon cycling in salt marsh dominated estuaries along the US Atlantic coast

    NASA Astrophysics Data System (ADS)

    Forbrich, Inke; Nahrawi, Hafsah B.; Wang, Shiyu; Leclerc, Monique; Hopkinson, Charles S.; Giblin, Anne E.; Alber, Merryl; Cai, Wei-Jun

    2016-04-01

    Salt marshes are effective carbon sinks, because they rely on vertical accretion of organic and inorganic matter to keep their relative position to sea level. They are also described as 'carbon pumps' that fix atmospheric carbon but deliver organic and inorganic carbon to estuarine and coastal waters. These fluxes are still highly uncertain due to their temporal and spatial variability. Here, we present observations on atmospheric CO2 exchange and lateral DIC exchange measured at two salt marsh dominated estuaries along the US Atlantic coast. Atmospheric exchange was measured with the eddy covariance method supplemented by measurements of DIC concentrations and discharge in tidal creeks during selected tidal cycles. Together with estimates of long-term carbon burial, this allows us to constrain their export potential. Since the Plum Island Ecosystems LTER and Georgia Coastal Ecosystems LTER are located along a temperature gradient, we will use the data to assess the temperature effect on ecosystem productivity and respiration.

  10. Making and Measuring a Model of a Salt Marsh

    ERIC Educational Resources Information Center

    Fogleman, Tara; Curran, Mary Carla

    2007-01-01

    Students are often confused by the difference between the terms "accuracy" and "precision." In the following activities, students explore the definitions of accuracy and precision while learning about salt march ecology and the methods used by scientists to assess salt marsh health. The activities also address the concept that the ocean supports a…

  11. Responses of eastern Chinese coastal salt marshes to sea-level rise combined with vegetative and sedimentary processes

    NASA Astrophysics Data System (ADS)

    Ge, Zhen-Ming; Wang, Heng; Cao, Hao-Bin; Zhao, Bin; Zhou, Xiao; Peltola, Heli; Cui, Li-Fang; Li, Xiu-Zhen; Zhang, Li-Quan

    2016-06-01

    The impacts of sea-level rise (SLR) on coastal ecosystems have attracted worldwide attention in relation to global change. In this study, the salt marsh model for the Yangtze Estuary (SMM-YE, developed in China) and the Sea Level Affecting Marshes Model (SLAMM, developed in the U.S.) were used to simulate the effects of SLR on the coastal salt marshes in eastern China. The changes in the dominant species in the plant community were also considered. Predictions based on the SLAMM indicated a trend of habitat degradation up to 2100; total salt marsh habitat area continued to decline (4–16%) based on the low-level scenario, with greater losses (6–25%) predicted under the high-level scenario. The SMM-YE showed that the salt marshes could be resilient to threats of SLR through the processes of accretion of mudflats, vegetation expansion and sediment trapping by plants. This model predicted that salt marsh areas increased (3–6%) under the low-level scenario. The decrease in the total habitat area with the SMM-YE under the high-level scenario was much lower than the SLAMM prediction. Nevertheless, SLR might negatively affect the salt marsh species that are not adapted to prolonged inundation. An adaptive strategy for responding to changes in sediment resources is necessary in the Yangtze Estuary.

  12. Responses of eastern Chinese coastal salt marshes to sea-level rise combined with vegetative and sedimentary processes.

    PubMed

    Ge, Zhen-Ming; Wang, Heng; Cao, Hao-Bin; Zhao, Bin; Zhou, Xiao; Peltola, Heli; Cui, Li-Fang; Li, Xiu-Zhen; Zhang, Li-Quan

    2016-06-23

    The impacts of sea-level rise (SLR) on coastal ecosystems have attracted worldwide attention in relation to global change. In this study, the salt marsh model for the Yangtze Estuary (SMM-YE, developed in China) and the Sea Level Affecting Marshes Model (SLAMM, developed in the U.S.) were used to simulate the effects of SLR on the coastal salt marshes in eastern China. The changes in the dominant species in the plant community were also considered. Predictions based on the SLAMM indicated a trend of habitat degradation up to 2100; total salt marsh habitat area continued to decline (4-16%) based on the low-level scenario, with greater losses (6-25%) predicted under the high-level scenario. The SMM-YE showed that the salt marshes could be resilient to threats of SLR through the processes of accretion of mudflats, vegetation expansion and sediment trapping by plants. This model predicted that salt marsh areas increased (3-6%) under the low-level scenario. The decrease in the total habitat area with the SMM-YE under the high-level scenario was much lower than the SLAMM prediction. Nevertheless, SLR might negatively affect the salt marsh species that are not adapted to prolonged inundation. An adaptive strategy for responding to changes in sediment resources is necessary in the Yangtze Estuary.

  13. Responses of eastern Chinese coastal salt marshes to sea-level rise combined with vegetative and sedimentary processes.

    PubMed

    Ge, Zhen-Ming; Wang, Heng; Cao, Hao-Bin; Zhao, Bin; Zhou, Xiao; Peltola, Heli; Cui, Li-Fang; Li, Xiu-Zhen; Zhang, Li-Quan

    2016-01-01

    The impacts of sea-level rise (SLR) on coastal ecosystems have attracted worldwide attention in relation to global change. In this study, the salt marsh model for the Yangtze Estuary (SMM-YE, developed in China) and the Sea Level Affecting Marshes Model (SLAMM, developed in the U.S.) were used to simulate the effects of SLR on the coastal salt marshes in eastern China. The changes in the dominant species in the plant community were also considered. Predictions based on the SLAMM indicated a trend of habitat degradation up to 2100; total salt marsh habitat area continued to decline (4-16%) based on the low-level scenario, with greater losses (6-25%) predicted under the high-level scenario. The SMM-YE showed that the salt marshes could be resilient to threats of SLR through the processes of accretion of mudflats, vegetation expansion and sediment trapping by plants. This model predicted that salt marsh areas increased (3-6%) under the low-level scenario. The decrease in the total habitat area with the SMM-YE under the high-level scenario was much lower than the SLAMM prediction. Nevertheless, SLR might negatively affect the salt marsh species that are not adapted to prolonged inundation. An adaptive strategy for responding to changes in sediment resources is necessary in the Yangtze Estuary. PMID:27334452

  14. Responses of eastern Chinese coastal salt marshes to sea-level rise combined with vegetative and sedimentary processes

    PubMed Central

    Ge, Zhen-Ming; Wang, Heng; Cao, Hao-Bin; Zhao, Bin; Zhou, Xiao; Peltola, Heli; Cui, Li-Fang; Li, Xiu-Zhen; Zhang, Li-Quan

    2016-01-01

    The impacts of sea-level rise (SLR) on coastal ecosystems have attracted worldwide attention in relation to global change. In this study, the salt marsh model for the Yangtze Estuary (SMM-YE, developed in China) and the Sea Level Affecting Marshes Model (SLAMM, developed in the U.S.) were used to simulate the effects of SLR on the coastal salt marshes in eastern China. The changes in the dominant species in the plant community were also considered. Predictions based on the SLAMM indicated a trend of habitat degradation up to 2100; total salt marsh habitat area continued to decline (4–16%) based on the low-level scenario, with greater losses (6–25%) predicted under the high-level scenario. The SMM-YE showed that the salt marshes could be resilient to threats of SLR through the processes of accretion of mudflats, vegetation expansion and sediment trapping by plants. This model predicted that salt marsh areas increased (3–6%) under the low-level scenario. The decrease in the total habitat area with the SMM-YE under the high-level scenario was much lower than the SLAMM prediction. Nevertheless, SLR might negatively affect the salt marsh species that are not adapted to prolonged inundation. An adaptive strategy for responding to changes in sediment resources is necessary in the Yangtze Estuary. PMID:27334452

  15. Winter climate change and coastal wetland foundation species: salt marshes vs. mangrove forests in the southeastern United States

    USGS Publications Warehouse

    Osland, Michael J.; Day, Richard H.; Doyle, Thomas W.; Enwright, Nicholas

    2013-01-01

    We live in an era of unprecedented ecological change in which ecologists and natural resource managers are increasingly challenged to anticipate and prepare for the ecological effects of future global change. In this study, we investigated the potential effect of winter climate change upon salt marsh and mangrove forest foundation species in the southeastern United States. Our research addresses the following three questions: (1) What is the relationship between winter climate and the presence and abundance of mangrove forests relative to salt marshes; (2) How vulnerable are salt marshes to winter climate change-induced mangrove forest range expansion; and (3) What is the potential future distribution and relative abundance of mangrove forests under alternative winter climate change scenarios? We developed simple winter climate-based models to predict mangrove forest distribution and relative abundance using observed winter temperature data (1970–2000) and mangrove forest and salt marsh habitat data. Our results identify winter climate thresholds for salt marsh–mangrove forest interactions and highlight coastal areas in the southeastern United States (e.g., Texas, Louisiana, and parts of Florida) where relatively small changes in the intensity and frequency of extreme winter events could cause relatively dramatic landscape-scale ecosystem structural and functional change in the form of poleward mangrove forest migration and salt marsh displacement. The ecological implications of these marsh-to-mangrove forest conversions are poorly understood, but would likely include changes for associated fish and wildlife populations and for the supply of some ecosystem goods and services.

  16. Inventory and protection of salt marshes from risks of sea-level rise at Acadia National Park, Maine

    USGS Publications Warehouse

    Dudley, Robert W.; Nielsen, Martha G.

    2011-01-01

    Recent U.S. Geological Survey (USGS) climate studies in the northeastern United States have shown substantial evidence of climate-related changes during the last 100 years, including earlier snowmelt runoff, decreasing occurrence of river ice, and decreasing winter snowpack. These studies related to climate change are being expanded to include investigation of coastal wetlands that might be at risk from sealevel rise. Coastal wetlands, particularly salt marshes, are important ecosystems that provide wildlife nursery and breeding habitat, migratory bird habitat, water quality enhancement, and shoreline erosion control. The USGS is investigating salt marshes in Acadia National Park with the goal of determining which salt marshes may be threatened by sea-level rise and which salt marshes may be able to adapt to sea-level rise by migrating into adjacent low-lying lands.

  17. Microbial community analysis of an Alabama coastal salt marsh impacted by the Deepwater Horizon Oil Spill

    NASA Astrophysics Data System (ADS)

    Beazley, M. J.; Martinez, R.; Rajan, S.; Powell, J.; Piceno, Y.; Tom, L.; Andersen, G. L.; Hazen, T. C.; Van Nostrand, J. D.; Zhou, J.; Mortazavi, B.; Sobecky, P. A.

    2011-12-01

    Microbial community responses of an Alabama coastal salt marsh environment to the Deepwater Horizon oil spill were studied by 16S rRNA (PhyloChip) and functional gene (GeoChip) microarray-based analysis. Oil and tar balls associated with the oil spill arrived along the Alabama coast in June 2010. Marsh and inlet sediment samples collected in June, July, and September 2010 from a salt marsh ecosystem at Point Aux Pines Alabama were analyzed to determine if bacterial community structure changed as a result of oil perturbation. Sediment total petroleum hydrocarbon (TPH) concentrations ranged from below detection to 189 mg kg-1 and were randomly dispersed throughout the salt marsh sediments. Total DNA extracted from sediment and particulates were used for PhyloChip and GeoChip hybridization. A total of 4000 to 8000 operational taxonomic units (OTUs) were detected in marsh and inlet samples. Distinctive changes in the number of detectable OTUs were observed between June, July, and September 2010. Surficial inlet sediments demonstrated a significant increase in the total number of OTUs between June and September that correlated with TPH concentrations. The most significant increases in bacterial abundance were observed in the phyla Actinobacteria, Firmicutes, Gemmatimonadetes, Proteobacteria, and Verrucomicrobia. Bacterial richness in marsh sediments also correlated with TPH concentrations with significant changes primarily in Acidobacteria, Actinobacteria, Firmicutes, Fusobacteria, Nitrospirae, and Proteobacteria. GeoChip microarray analysis detected 5000 to 8300 functional genes in marsh and inlet samples. Surficial inlet sediments demonstrated distinctive increases in the number of detectable genes and gene signal intensities in July samples compared to June. Signal intensities increased (> 1.5-fold) in genes associated with petroleum degradation. Genes related to metal resistance, stress, and carbon cycling also demonstrated increases in oiled sediments. This study

  18. Ecogeomorphic Properties of Flood-ebb Flows on a Coastal North Carolina Salt-marsh Platform

    NASA Astrophysics Data System (ADS)

    Howell, S.; Furbish, D.; Mudd, S.

    2006-12-01

    Salt marsh ecosystems play a vital role in nutrient processing, shoreline defense, and as habitats for commercially important species. Along the Albemarle and Pamlico Sounds, North Carolina, where the tidal amplitude ranges from 1.0 to 1.5 m, salt marsh communities are expected to undergo a transition from intertidal marshes to subtidal habitats in response to sea-level rise and associated increases in inundation and possibly tidal range. Intertidal areas along the back-barrier sound of Bogue Banks feature well developed networks of tidal channels and exhibit classic macrophyte zonation, with Spartina spp. residing along lower elevations and Juncus roemerianus at higher elevations. As part of a long-term study of macrophyte dynamics, sedimentation and geomorphology in the Albemarle and Pamlico Sounds area, here we describe the pattern of flood-ebb flow on a marsh platform. Continuous measurements from a set of pressure transducers arranged along a marsh transect are used to describe spatial variations in the frequency, duration and depth of inundation as a function of platform elevation, macrophyte biomass, and proximity to the tidal creek. Stem density and diameter of Spartina alterniflora and Juncus roemerianus affect the magnitude of drag forces on the marsh platform during flooding; our field measurements are used to constrain the relationship between macrophyte stand characteristics and these drag forces.

  19. Effects of Experimental Warming on Net Greenhouse Gas Fluxes from a New England Salt Marsh

    NASA Astrophysics Data System (ADS)

    Carey, J.; Kroeger, K. D.; Morkeski, K.; Chen, X.; Tang, J.

    2014-12-01

    Salt marsh ecosystems face a variety of anthropogenic stressors, including rising temperature, increasing rate of relative sea level rise, changing sediment loads, and increasing nitrogen loads. In this study, we focus on the role of increased temperatures in altering net greenhouse gas fluxes (CO2, CH4, N2O) in a relatively undisturbed New England salt marsh (Waquoit Bay National Estuarine Research Reserve, USA). Salt marshes are considered large net sinks of carbon (C), due in part to the high rates of primary production and relatively slow decomposition rates. However, increased temperature as a result of climate change may alter the net carbon balance of these ecosystems, due to changes in relative rates of respiration and photosynthesis. In addition to altering the net C balance, nitrous oxide (N2O) is produced in part via microbially-mediated processes that also respond to temperature (e.g. nitrification, denitrification). Thus, we hypothesize that higher temperatures may increase the fluxes of this potent GHG from marshes to the atmosphere. To examine the role of warming in altering net GHG fluxes, we installed six open-top-chambers (OTCs) in both the high and low marsh during July of 2014. We used the cavity ring-down spectroscopy method (Picarro and LGR) to measure in-situ fluxes of CO2, CH4, N2O monthly in light and dark conditions. We will present data demonstrating that our OTCs successfully warmed the air temperature in the plots at least 5 ˚C and evaluate how this temperature increase altered GHG net ecosystem exchange in the marsh.

  20. Methane fluxes along a salinity gradient on a restored salt marsh, Harpswell, ME

    NASA Astrophysics Data System (ADS)

    Gunn, Cailene; Johnson, Beverly, ,, Dr.; Dostie, Phil; Bohlen, Curtis; Craig, Matthew

    2016-04-01

    This study functions as a pilot project to understand the relationship between salinity and methane emissions on a recently restored salt marsh in Casco Bay, Maine. Salt marshes are dynamic and highly productive ecosystems that provide a multitude of ecosystem services including nutrient filtration, storm-water buffering and carbon sequestration. These ecosystems are highly susceptible to anthropogenic alteration. The emplacement of causeways and narrow culverts, restricts tidal flow and leads to loss of healthy salinity gradients. Consequently, numerous salt marshes have experienced increases in freshwater vegetation growth as a result of coastal population expansion. Recent restoration efforts on Long Marsh, Harpswell, ME replaced a severely undersized culvert with a larger one in February, 2014. The salinity gradient has since been restored along much of the marsh, and freshwater vegetation that encroached on the marsh platform has died back. Vegetation and salinity are key indicators and drivers of CH4 emissions on salt marshes. Using static gas chambers, we quantified CH4 fluxes along two transects at five diverse sites ranging from healthy marsh (salinity of 27 to 31 psu) with Spartina vegetation, to regions invaded by Typha and other freshwater vegetation (salinity of 0 to 4 psu). Sampling was executed in the months of July, August and October. CH4 concentrations were determined using a gas chromatograph with a flame-ionization detector. Preliminary findings suggest reintroduction of healthy tidal flows into the marsh inhibits CH4 production, where the lowest fluxes with least variability were observed at the most saline sites with Spartina vegetation. The largest range of CH4 fluxes exhibited emissions from 0.75 μmol CH4/m2/hr to 518.4 μmol CH4/m2/hr at the Typha dominated sites from July to October. Fluxes at the saltwater and brackish regions were far less variable with ranges from 0.94 μmol CH4/m2/hr to 8.2 μmol CH4/m2/hr and 2.6 to 9.5 μmol CH4/m2

  1. The persistence of endangered Florida Salt Marsh Voles in salt marshes of the central Florida Gulf Coast

    USGS Publications Warehouse

    Hotaling, A.S.; Percival, H.F.; Kitchens, W.M.; Kasbohm, J.W.

    2010-01-01

    Two endangered Microtus pennsylvanicus dukecampbelli (Florida Salt Marsh Vole) were captured at a new location, in February of 2009, at Lower Suwannee National Wildlife Refuge. Since the species discovery in 1979, only 43 Florida Salt Marsh Voles (hereafter FSM Vole) have been captured. Outside of the type locality, this is only the second documented location for the FSM Vole. Given the difficulty in trapping this species and the lack of information about its life history, its discovery in a new location lends itself to the possibility that it is more widespread in the Central Florida Gulf Coast than previously thought. Although much of the salt marsh in the area is in public ownership, a good deal of it has already been altered by logging or development and is threatened by global climate change. More research is needed to adequately protect and manage the habitat for the FSM Vole. A study of FSM Vole coastal salt marsh habitat could also serve as a valuable monitoring tool for subtle changes in salt marsh habitats as global climate change progresses.

  2. A RAPID NON-DESTRUCTIVE METHOD FOR ESTIMATING ABOVEGROUND BIOMASS OF SALT MARSH GRASSES

    EPA Science Inventory

    Understanding the primary productivity of salt marshes requires accurate estimates of biomass. Unfortunately, these estimates vary enough within and among salt marshes to require large numbers of replicates if the averages are to be statistically meaningful. Large numbers of repl...

  3. Mangrove expansion and salt marsh decline at mangrove poleward limits.

    PubMed

    Saintilan, Neil; Wilson, Nicholas C; Rogers, Kerrylee; Rajkaran, Anusha; Krauss, Ken W

    2014-01-01

    Mangroves are species of halophytic intertidal trees and shrubs derived from tropical genera and are likely delimited in latitudinal range by varying sensitivity to cold. There is now sufficient evidence that mangrove species have proliferated at or near their poleward limits on at least five continents over the past half century, at the expense of salt marsh. Avicennia is the most cold-tolerant genus worldwide, and is the subject of most of the observed changes. Avicennia germinans has extended in range along the USA Atlantic coast and expanded into salt marsh as a consequence of lower frost frequency and intensity in the southern USA. The genus has also expanded into salt marsh at its southern limit in Peru, and on the Pacific coast of Mexico. Mangroves of several species have expanded in extent and replaced salt marsh where protected within mangrove reserves in Guangdong Province, China. In south-eastern Australia, the expansion of Avicennia marina into salt marshes is now well documented, and Rhizophora stylosa has extended its range southward, while showing strong population growth within estuaries along its southern limits in northern New South Wales. Avicennia marina has extended its range southwards in South Africa. The changes are consistent with the poleward extension of temperature thresholds coincident with sea-level rise, although the specific mechanism of range extension might be complicated by limitations on dispersal or other factors. The shift from salt marsh to mangrove dominance on subtropical and temperate shorelines has important implications for ecological structure, function, and global change adaptation. PMID:23907934

  4. Remote sensing of biomass of salt marsh vegetation in France

    NASA Technical Reports Server (NTRS)

    Gross, M. F.; Klemas, V.; Levasseur, J. E.

    1988-01-01

    Spectral data (gathered using a hand-held radiometer) and harvest data were collected from four salt marsh vegetation types in Brittany, France, to develop equations predicting live aerial biomass from spectral measurements. Remote sensing estimates of biomass of the general salt marsh community (GSM) and of Spartina alterniflora can be obtained throughout the growing season if separate biomass prediction equations are formulated for different species mixtures (for the GSM) and for different canopy types (for S. alterniflora). Results suggest that remote sensing will not be useful for predicting Halimione portulacoides biomass, but can be used to estimate Puccinellia maritima biomass early in the growing season.

  5. Variability of fresh- and salt-water marshes characteristics on the west coast of France: a spatio-temporal assessment.

    PubMed

    Tortajada, Sébastien; David, Valérie; Brahmia, Amel; Dupuy, Christine; Laniesse, Thomas; Parinet, Bernard; Pouget, Frederic; Rousseau, Frederic; Simon-Bouhet, Benoit; Robin, François-Xavier

    2011-08-01

    The degradation of water quality and the multiple conflicts of interest between users make marsh restoration very important. A Water Quality Evaluation System (WQES) was developed for river systems by the European Water Framework Directive (WFD). Some form of biologically-based, habitat-specific reference standard seems absolutely essential for wise management and stewardship of marsh ecosystems. The goal of this study was to develop a statistical method to define and to characterize a water body typology for drained marshes of the Charente-Maritime wetlands on the French Atlantic coast, placing particular emphasis on environmental factors as hydraulic functioning, human activities and pedological substratum. The Charente-Maritime marshes represent a good field study because of his high diversity of types of marshes and of anthropogenic activities in a restrictive area thus erasing spatial climatic effect (latitude effect). The statistical method developed here had permitted to define and characterize 12 different water bodies, 7 in freshwater (F1 to F7) and 5 in salt water marshes for the Charente-Maritime area. This typology demonstrated an important link between the size catchment area, nitrate concentrations, and leaching of precipitation from cultured soils. Even though the Charente-Maritime marshes are strongly impacted by humans, they may still retain the ability to remove nitrate. The increasing gradient of water renewal in the freshwater marshes from F1 to F7 explained the decreasing gradient of eutrophication. A better management of the hydrodynamic of the marshes can avoid eutrophication risk on the coastal sea area. Reliance on the WFD parameter set necessarily placed limits on the kinds of interpretations that could be made and on the study's potential contribution to the basic science of marshes. Ecologically-based insights regarding both external flows (links between ecosystems, meta-ecosystem theory) and internal flows (structure of the planktonic

  6. Variability of fresh- and salt-water marshes characteristics on the west coast of France: a spatio-temporal assessment.

    PubMed

    Tortajada, Sébastien; David, Valérie; Brahmia, Amel; Dupuy, Christine; Laniesse, Thomas; Parinet, Bernard; Pouget, Frederic; Rousseau, Frederic; Simon-Bouhet, Benoit; Robin, François-Xavier

    2011-08-01

    The degradation of water quality and the multiple conflicts of interest between users make marsh restoration very important. A Water Quality Evaluation System (WQES) was developed for river systems by the European Water Framework Directive (WFD). Some form of biologically-based, habitat-specific reference standard seems absolutely essential for wise management and stewardship of marsh ecosystems. The goal of this study was to develop a statistical method to define and to characterize a water body typology for drained marshes of the Charente-Maritime wetlands on the French Atlantic coast, placing particular emphasis on environmental factors as hydraulic functioning, human activities and pedological substratum. The Charente-Maritime marshes represent a good field study because of his high diversity of types of marshes and of anthropogenic activities in a restrictive area thus erasing spatial climatic effect (latitude effect). The statistical method developed here had permitted to define and characterize 12 different water bodies, 7 in freshwater (F1 to F7) and 5 in salt water marshes for the Charente-Maritime area. This typology demonstrated an important link between the size catchment area, nitrate concentrations, and leaching of precipitation from cultured soils. Even though the Charente-Maritime marshes are strongly impacted by humans, they may still retain the ability to remove nitrate. The increasing gradient of water renewal in the freshwater marshes from F1 to F7 explained the decreasing gradient of eutrophication. A better management of the hydrodynamic of the marshes can avoid eutrophication risk on the coastal sea area. Reliance on the WFD parameter set necessarily placed limits on the kinds of interpretations that could be made and on the study's potential contribution to the basic science of marshes. Ecologically-based insights regarding both external flows (links between ecosystems, meta-ecosystem theory) and internal flows (structure of the planktonic

  7. EVALUATING THE INTEGRITY OF SALT MARSHES IN NARRAGANSETT BAY SUB-ESTUARIES USING A WATERSHED APPROACH

    EPA Science Inventory

    A watershed approach to examine measures of structure and function in salt marshes of similar geomorphology and hydrology in Narragansett Bay is being used to develop a reference system for evaluating salt marsh integrity. We describe integrity as the capability of a salt marsh t...

  8. Record of the accumulation of sediment and trace metals in a Connecticut salt marsh

    SciTech Connect

    McCaffrey, R.J.; Thomson, J.

    1980-12-01

    The possibility that a useful, historical record of deposition might be found in a salt marsh is investigated by considering a record of the accumulation of sediment and trace metals in a Connecticut salt marsh. Evidence of salt-marsh deposition dominated by riverine runoff is presented.

  9. EVALUATING THE INTEGRITY OF SALT MARSHES IN NARRAGANSETT BAY SUBESTUARIES USING A WATESHED APPROACH

    EPA Science Inventory

    A watershed approach to examine measures of structure and function in salt marshes of similar geomorphology and hydrology in Narragansett Bay was used to develop a reference system for evaluating salt marsh integrity. We describe integrity as the capability of a salt marsh to pro...

  10. Long-term remote monitoring of salt marsh biomass

    NASA Technical Reports Server (NTRS)

    Gross, M. F.; Klemas, V.; Hardisky, M. A.

    1990-01-01

    Methods developed for monitoring salt-marsh biomass remotedly are considered in the framework of NASA's Biospheric Research Program. Satellite-derived estimates of the aboveground biomass is considered, and it is noted that a long-term program for long-term remote monitoring is only practical if the relationship between biomass and spectral data remains essentially constant from year to year. Emphasis is placed on ground-based sampling, satellite measurements of mean marsh live aboveground biomass, the spatial distribution of biomass within the marsh, and changes in marsh hydrography as seen from a satellite. Linking aboveground and belowground biomass is discussed, as well as the problem with obtaining cloud-free images and measuring dead biomass.

  11. Salt marshes: An important coastal sink for dissolved uranium

    NASA Astrophysics Data System (ADS)

    Church, T. M.; Sarin, M. M.; Fleisher, M. Q.; Ferdelman, T. G.

    1996-10-01

    The global budget for marine uranium demands another geochemical sink other than deep-sea systems, and the coastal environment may host some or all of this missing sink. In a previous paper ( Sarin and Church, 1994), we have shown that some large subtidal estuaries are seasonal summer sinks at low salinities. In this paper, we show that intertidal salt marshes are even stronger sinks at all salinities, if for somewhat different reasons. Uranium was sampled in dissolved and particulate fractions over several tidal cycles and seasons for a lower Delaware Bay salt marsh (Canary Creek, Lewes, Delaware, USA), and uniquely, during summer months, the dissolved uranium is nonconservative. Moreover, because uranium extraction is greater on higher tides and occurs over the entire salinity gradient, this processing appears associated with surface of vegetated high marsh. We hypothesize that either (1) uranium scavenging occurs during the process of tidal mixing and attendant flocculation of humic acids and iron oxides—favoring this process is the presence of sulfonate complexes in salt marsh humic substances, and iron coprecipitation during its extensive redox cycling in the salt marsh—or (2) uranium extraction occurs at the marsh surface during extensive flooding of the salt marsh surface sediments—favoring this process is the increase in sulfuric acidity at the summer salt marsh surface that could destabilize the tetracarbonate species of U(VI). The latter option is favored by both field observations of maximum removal at the surface during the spring and summer tide conditions, and selective extraction of sediment phases where uranium is found as adsorbed and complexed forms in the ascorbate-citrate and humic acid fractions, respectively. Mass balance calculations show that under steady-state conditions, nearly two-thirds of the uranium extracted from tidal waters is retained in the sediments, while one-third is exported as U-enriched particles during ebbing tides

  12. Salt marsh mapping based on a short-time interval NDVI time-series from HJ-1 CCD imagery

    NASA Astrophysics Data System (ADS)

    SUN, C.

    2015-12-01

    Salt marshes are regard as one of the most dynamic and valuable ecosystems in coastal zone. It is crucial to obtain accurate information on the species composition and spatial distribution of salt marshes in time since they are experiencing tremendous replacement and disappearance. However, discriminating various types of salt marshes is a rather difficult task because of the strong spectral similarities. In previous studies, salt marsh mappings were mainly focused on high-spatial and hyperspectral resolution imageries combined with auxiliary information but this method can hardly extend to a large region. With high temporal and moderate spatial resolutions, Chinese HJ-1 CCD imagery would not only allow monitoring phenological changes of salt marsh vegetation in short-time intervals, but also cover large areas of salt marshes. Taking the middle coast of Jiangsu (east China) as an example, our study first constructed a monthly NDVI time-series to classify various types of salt marshes. Then, we tested the idea of compressed time-series continuously to broaden the applicability and portability of this particular approach. The results showed that (1) the overall accuracy of salt marsh mapping based on the monthly NDVI time-series reached 90.3%, which increased approximately 16.0% in contrast with a single-phase classification strategy; (2) a compressed time-series, including NDVI from six key months (April, June to September, and November) demonstrated very little decline (2.3%) in overall accuracy but led to obvious improvements in unstable regions; (3) Spartina alterniflora identification could be achieved with only a scene NDVI image from November, which could provide an effective way to regularly monitor its distribution. Besides, by comparing the calibrated performance between HJ-1 CCD and other sensors (i.e., Landsat TM/ETM+, OLI), we certified the reliability of HJ-1 CCD imagery, which is expected to pave the way for laws expansibility from this imagery.

  13. A monitoring protocol to assess tidal restoration of salt marshes on local and regional scales

    USGS Publications Warehouse

    Neckles, H.A.; Dionne, M.D.; Burdick, D.M.; Roman, C.T.; Buchsbaum, R.; Hutchins, E.

    2002-01-01

    Assessing the response of salt marshes to tidal restoration relies on comparisons of ecosystem attributes between restored and reference marshes. Although this approach provides an objective basis for judging project success, inferences can be constrained if the high variability of natural marshes masks differences in sampled attributes between restored and reference sites. Furthermore, such assessments are usually focused on a small number of restoration projects in a local area, limiting the ability to address questions regarding the effectiveness of restoration within a broad region. We developed a hierarchical approach to evaluate the performance of tidal restorations at local and regional scales throughout the Gulf of Maine. The cornerstone of the approach is a standard protocol for monitoring restored and reference salt marshes throughout the region. The monitoring protocol was developed by consensus among nearly 50 restoration scientists and practitioners. The protocol is based on a suite of core structural measures that can be applied to any tidal restoration project. The protocol also includes additional functional measures for application to specific projects. Consistent use of the standard protocol to monitor local projects will enable pooling information for regional assessments. Ultimately, it will be possible to establish a range of reference conditions characterizing natural tidal wetlands in the region and to compare performance curves between populations of restored and reference marshes for assessing regional restoration effectiveness.

  14. Effects of open marsh water management on numbers of larval salt marsh mosquitoes.

    PubMed

    James-Pirri, Mary-Jane; Ginsberg, Howard S; Erwin, R Michael; Taylor, Janith

    2009-11-01

    Open marsh water management (OMWM) is a commonly used approach to manage salt marsh mosquitoes than can obviate the need for pesticide application and at the same time, partially restore natural functions of grid-ditched marshes. OMWM includes a variety of hydrologic manipulations, often tailored to the specific conditions on individual marshes, so the overall effectiveness of this approach is difficult to assess. Here, we report the results of controlled field trials to assess the effects of two approaches to OMWM on larval mosquito production at National Wildlife Refuges (NWR). A traditional OMWM approach, using pond construction and radial ditches was used at Edwin B. Forsythe NWR in New Jersey, and a ditch-plugging approach was used at Parker River NWR in Massachusetts. Mosquito larvae were sampled from randomly placed stations on paired treatment and control marshes at each refuge. The proportion of sampling stations that were wet declined after OMWM at the Forsythe site, but not at the Parker River site. The proportion of samples with larvae present and mean larval densities, declined significantly at the treatment sites on both refuges relative to the control marshes. Percentage of control for the 2 yr posttreatment, compared with the 2 yr pretreatment, was >90% at both treatment sites. PMID:19960686

  15. Effects of open marsh water management on numbers of larval salt marsh mosquitoes.

    PubMed

    James-Pirri, Mary-Jane; Ginsberg, Howard S; Erwin, R Michael; Taylor, Janith

    2009-11-01

    Open marsh water management (OMWM) is a commonly used approach to manage salt marsh mosquitoes than can obviate the need for pesticide application and at the same time, partially restore natural functions of grid-ditched marshes. OMWM includes a variety of hydrologic manipulations, often tailored to the specific conditions on individual marshes, so the overall effectiveness of this approach is difficult to assess. Here, we report the results of controlled field trials to assess the effects of two approaches to OMWM on larval mosquito production at National Wildlife Refuges (NWR). A traditional OMWM approach, using pond construction and radial ditches was used at Edwin B. Forsythe NWR in New Jersey, and a ditch-plugging approach was used at Parker River NWR in Massachusetts. Mosquito larvae were sampled from randomly placed stations on paired treatment and control marshes at each refuge. The proportion of sampling stations that were wet declined after OMWM at the Forsythe site, but not at the Parker River site. The proportion of samples with larvae present and mean larval densities, declined significantly at the treatment sites on both refuges relative to the control marshes. Percentage of control for the 2 yr posttreatment, compared with the 2 yr pretreatment, was >90% at both treatment sites.

  16. Effects of open marsh water management on numbers of larval salt marsh mosquitoes

    USGS Publications Warehouse

    James-Pirri, Mary-Jane; Ginsberg, Howard S.; Erwin, R. Michael; Taylor, Janith

    2009-01-01

    Open marsh water management (OMWM) is a commonly used approach to manage salt marsh mosquitoes than can obviate the need for pesticide application and at the same time, partially restore natural functions of grid-ditched marshes. OMWM includes a variety of hydrologic manipulations, often tailored to the specific conditions on individual marshes, so the overall effectiveness of this approach is difficult to assess. Here, we report the results of controlled field trials to assess the effects of two approaches to OMWM on larval mosquito production at National Wildlife Refuges (NWR). A traditional OMWM approach, using pond construction and radial ditches was used at Edwin B. Forsythe NWR in New Jersey, and a ditch-plugging approach was used at Parker River NWR in Massachusetts. Mosquito larvae were sampled from randomly placed stations on paired treatment and control marshes at each refuge. The proportion of sampling stations that were wet declined after OMWM at the Forsythe site, but not at the Parker River site. The proportion of samples with larvae present and mean larval densities, declined significantly at the treatment sites on both refuges relative to the control marshes. Percentage of control for the 2 yr posttreatment, compared with the 2 yr pretreatment, was >90% at both treatment sites.

  17. Marshes on the Move: Testing effects of seawater intrusion on vegetation communities of the salt marsh-upland ecotone

    EPA Science Inventory

    The Northeastern United States is a hotspot for sea level rise (SLR), subjecting coastal salt marshes to erosive loss, shifts in vegetation communities, and altered biogeochemistry due to seawater intrusion. Salt marsh plant community zonation is driven by tradeoffs in stress to...

  18. New model describes toppling of salt marsh banks

    NASA Astrophysics Data System (ADS)

    Wendel, JoAnna

    2014-05-01

    Salt marshes are coastal habitats that store important nutrients and serve as shelter for many estuarial species. These habitats are threatened by rising seas and human expansion, so it has become increasingly important to improve models of how these habitats degrade.

  19. Results of Total Mercury Analysis in Salt Marsh Invertebrates

    EPA Science Inventory

    Analysis of blood samples obtained from saltmarsh sparrows revealed high levels (> 1.0 µg/g(wet)) of mercury (Hg) in sparrows inhabiting a salt marsh site in the Narrow River, RI (also known as Pettaquamscutt River). These analyses were conducted by Oksana Lane at the Biodiversit...

  20. Biogeomorphically driven salt pan formation in Sarcocornia-dominated salt-marshes

    NASA Astrophysics Data System (ADS)

    Escapa, Mauricio; Perillo, Gerardo M. E.; Iribarne, Oscar

    2015-01-01

    Salt-marshes are under increasing threat, particularly from sea-level rise and increased wave action associated with climate change. The development and stability of these valuable habitats largely depend on complex interactions between biotic and abiotic processes operating at different scales. Also, interactions between biotic and abiotic processes drive internal morphological change in salt-marshes. In this paper we used a biogeomorphological approach to assess the impact of biological activities and interactions on salt pan formation in Sarcocornia-dominated salt marshes. Salt pans represent a key physiographic feature of salt-marshes and recent studies hypothesized that biogeomorphic processes could be related to salt pan formation in SW Atlantic salt-marshes. The glasswort Sarcocornia perennis is one of the dominant plants in the salt-marshes of the Bahía Blanca Estuary (Argentina) where they form patches up to 8 m in diameter. These salt-marshes are also inhabited in great densities by the burrowing crab Neohelice (Chasmagnathus) granulata whose bioturbation rates are among the highest reported for salt-marshes worldwide. A set of biological interactions between N. granulata and S. perennis appears to be responsible for salt pan development in these areas which has not been described elsewhere. The main objective of this work was to determine the ecological interactions occurring between plants and crabs that lead to salt pan formation by using field-based sampling and manipulative experiments. Our results showed that S. perennis facilitated crab colonization of the salt-marsh by buffering otherwise stressful physical conditions (e.g., temperature, desiccation). Crabs preferred to construct burrows underneath plants and, once they reach high densities (up to 40 burrows m- 2), the sediment reworking caused plant die-off in the central area of patches. At this state, the patches lose elevation and become depressed due to the continuous bioturbation by crabs

  1. The Resilience and Recovery of Salt Marshes to Landfalling Storms and Sea-Level Rise, New Jersey, USA

    NASA Astrophysics Data System (ADS)

    Horton, B.; Nikitina, D.; Kemp, A.; Vane, C. H.; Engelhart, S. E.; Khan, N. S.

    2014-12-01

    Instrumental and observational records are too short to adequately describe the history of land-falling storms or sea-level rise, especially for extreme and rare events such as Hurricane Sandy. However, the sediment preserved beneath coastal wetlands is an archive of when storms impacted the coast and past changes in sea level, and how long it takes for wetlands recovery from such events. Here, we describe late Holocene sediments beneath the Sea Breeze salt marsh on the New Jersey side of Delaware Bay from more than 200 gouge cores positioned along seven transects. The stratigraphic record documents at least seven depositional sequences consisting of salt-marsh peat and mud couplets that represent dramatic changes in sedimentation regime. There are number of processes that could cause this salt-marsh erosion including lateral migration of tidal creeks, rapid relative sea-level rise, tsunamis, formation and expansion of salt pans, and storms. The abrupt contacts between the salt-marsh peat and overlying intertidal mud suggest that erosion of the peat was followed by rapid infilling of accommodation space. Correlation of erosional surfaces across 2.5 km suggests a common mechanism and we propose that the erosion was caused by hurricanes and/or large winter storms. Further, the changes in salt-marsh sedimentation documented at several sites on the north shore of Delaware Bay were synchronous and broadly correlate with storm over-wash deposits and historical record of hurricane landfalls in New Jersey. We estimated wetland recovery time from hurricane-induced erosion using radiocarbon dates that bracket the erosive event in the sedimentary record. Following erosion and lowering of the marsh surface into the tidal frame a low-marsh ecosystem recolonizes the site, followed by recovery to a high salt-marsh environment. We estimate that this ecological and sedimentary succession can take up to 200 years.

  2. Windows of opportunity for salt marsh vegetation establishment on bare tidal flats: The importance of temporal and spatial variability in hydrodynamic forcing

    NASA Astrophysics Data System (ADS)

    Hu, Zhan; Belzen, Jim; Wal, Daphne; Balke, Thorsten; Wang, Zheng Bing; Stive, Marcel; Bouma, Tjeerd J.

    2015-07-01

    Understanding the mechanisms limiting and facilitating salt marsh vegetation initial establishment is of widespread importance due to the many valuable services salt marsh ecosystems offer. Salt marsh dynamics have been investigated by many previous studies, but the mechanisms that enable or disable salt marsh initial establishment are still understudied. Recently, the "windows of opportunity" (WoO) concept has been proposed as a framework providing an explanation for the initial establishment of biogeomorphic ecosystems and the role of physical disturbance herein. A WoO is a sufficiently long disturbance-free period following seedling dispersal, which enables successful establishment. By quantifying the occurrence of WoO, vegetation establishment pattern can be predicted. For simplicity sake and as prove of concept, the original WoO framework considers tidal inundation as the only physical disturbance to salt marsh establishment, whereas the known disturbance from tidal currents and wind waves is ignored. In this study, we incorporate hydrodynamic forcing in the WoO framework. Its spatial and temporal variability is considered explicitly in a salt marsh establishment model. We used this model to explain the observed episodic salt marsh recruitment in the Westerschelde Estuary, Netherlands. Our results reveal that this model can significantly increase the spatial prediction accuracy of salt marsh establishment compared to a model that excludes the hydrodynamic disturbance. Using the better performing model, we further illustrate how tidal flat morphology determines salt marsh establishing elevation and width via hydrodynamic force distribution. Our model thus offers a valuable tool to understand and predict bottlenecks of salt marsh restoration and consequences of changing environmental conditions due to climate change.

  3. Exposed salt marsh morphodynamics: An example from the Danish Wadden Sea

    NASA Astrophysics Data System (ADS)

    Pedersen, Jørn B. T.; Bartholdy, Jesper

    2007-10-01

    In the Danish Wadden Sea, exposed salt marshes grow in the form of sequences of salt marsh platforms which terminate at the tidal flat with an erosional cliff. On the tidal flat adjacent to the salt marsh, a marsh-parallel small depression is usually formed which acts as a tidal channel (landpriel) creating levees on its landward side, on which salt marsh from the mainland spreads seaward with an uneven topography. On the seaward side of the landpriel, patches of slightly higher elevations form as a result of wave action. As plants get a foothold on these patches salt marsh growth is initiated. Along with this process a salt marsh cliff develops against wave attack from the tidal flat during storms. The unit consisting of levee, landpriel and patches of higher elevation eventually silts up and buries the former cliff on top of the levee, so this now stands as a small (≈ 0.25 m) ridge separating the new platform from the older one. Thus, the salt marsh accretes through a sequence of salt marsh platforms, each with its own landpriel, levee and erosional cliff. The landpriel and levee can be recognised later as topographic lows and highs, respectively, in the sand beneath the fine-grained salt marsh sediments, while the erosional cliff can be recognised in the salt marsh topography. Based on these observations, a conceptual evolutionary/accretionary model for exposed salt marshes with associated erosional cliff, landpriel and levee is presented. The deposition across the salt marsh platform decreases in an exponential manner away from the salt marsh edge at a lower rate than that found on a lee side salt marsh at the Skallingen backbarrier north of the study area. This is interpreted as a result of wave action.

  4. Response of salt-marsh carbon accumulation to climate change.

    PubMed

    Kirwan, Matthew L; Mudd, Simon M

    2012-09-27

    About half of annual marine carbon burial takes place in shallow water ecosystems where geomorphic and ecological stability is driven by interactions between the flow of water, vegetation growth and sediment transport. Although the sensitivity of terrestrial and deep marine carbon pools to climate change has been studied for decades, there is little understanding of how coastal carbon accumulation rates will change and potentially feed back on climate. Here we develop a numerical model of salt marsh evolution, informed by recent measurements of productivity and decomposition, and demonstrate that competition between mineral sediment deposition and organic-matter accumulation determines the net impact of climate change on carbon accumulation in intertidal wetlands. We find that the direct impact of warming on soil carbon accumulation rates is more subtle than the impact of warming-driven sea level rise, although the impact of warming increases with increasing rates of sea level rise. Our simulations suggest that the net impact of climate change will be to increase carbon burial rates in the first half of the twenty-first century, but that carbon-climate feedbacks are likely to diminish over time.

  5. Seasonal Variation in the Quality of Dissolved and Particulate Organic Matter Exchanged Between a Salt Marsh and Its Adjacent Estuary

    NASA Astrophysics Data System (ADS)

    Osburn, C. L.; Mikan, M.; Etheridge, J. R.; Burchell, M. R.; Birgand, F.

    2015-12-01

    Salt marshes are transitional ecosystems between terrestrial and marine environments. Along with mangroves and other vegetated coastal habitats, salt marshes rank among the most productive ecosystems on Earth, with critical global importance for the planet's carbon cycle. Fluorescence was used to examine the quality of dissolved and particulate organic matter (DOM and POM) exchanging between a tidal creek in a created salt marsh and its adjacent estuary in eastern North Carolina, USA. Samples from the creek were collected hourly over four tidal cycles in May, July, August, and October of 2011. Absorbance and fluorescence of chromophoric DOM (CDOM) and of base-extracted POM (BEPOM) served as the tracers for organic matter quality while dissolved organic carbon (DOC) and base-extracted particulate organic carbon (BEPOC) were used to compute fluxes. Fluorescence was modeled using parallel factor analysis (PARAFAC) and principle components analysis (PCA) of the PARAFAC results. Of nine PARAFAC components modeled, we used multiple linear regression to identify tracers for recalcitrant DOM; labile soil-derived source DOM; detrital POM; and planktonic POM. Based on mass balance, recalcitrant DOC export was 86 g C m-2 yr-1 and labile DOC export was 49 g C m-2 yr-1. The marsh also exported 41 g C m-2 yr-1 of detrital terrestrial POC, which likely originated from lands adjacent to the North River estuary. Planktonic POC export from the marsh was 6 g C m-2 yr-1. Using the DOM and POM quality results obtained via fluorescence measurements and scaling up to global salt marsh area, we estimated that the potential release of CO2 from the respiration of salt marsh DOC and POC transported to estuaries could be 11 Tg C yr-1, roughly 4% of the recently estimated CO2 release for marshes and estuaries globally.

  6. Tidal circulation alteration for salt marsh mosquito control

    NASA Astrophysics Data System (ADS)

    Resh, Vincent H.; Balling, Steven S.

    1983-01-01

    Mosquito control ditches designed to increase tidal circulation are widely used as a physical control alternative to insecticidal applications The impact of such ditching on Pacific Coast marshlands was largely unknown before this five-year study of impact in two types of San Francisco Bay salt marshes, a Salicornia virginica (pickleweed) monoculure and a mixed vegetation marsh Results of our studies suggest that ditches cause less environmental disturbance than insecticidal applications The article describes the following environmental consequences of ditching for mosquito control: increased tidal flushing of soils occurs adjacent to ditches compared with that in the open marsh, thereby reducing ground water and soil surface salinities and water table height; primary productivity of S. virginica, as determined by both the harvest method and infrared photographic analysis, is higher directly adjacent to ditches than in the open marsh, distribution of selected arthropod populations is similar at ditches and natural channels, although arthropod community response differs seasonally; aquatic invertebrate biomass is similar within ditched and natural ponds, but diversity is lower in ditched habitats, ditching increases fish diversity and density by improving fish access from tidal channels; ditches provide additional salt marsh song sparrow habitat, although ditches are less preferred than natural channels or sloughs. Management criteria can be used to design ditches that provide effective mosquito control and reduced environmental impact

  7. Seventy years of continuous encroachment substantially increases 'blue carbon' capacity as mangroves replace intertidal salt marshes.

    PubMed

    Kelleway, Jeffrey J; Saintilan, Neil; Macreadie, Peter I; Skilbeck, Charles G; Zawadzki, Atun; Ralph, Peter J

    2016-03-01

    Shifts in ecosystem structure have been observed over recent decades as woody plants encroach upon grasslands and wetlands globally. The migration of mangrove forests into salt marsh ecosystems is one such shift which could have important implications for global 'blue carbon' stocks. To date, attempts to quantify changes in ecosystem function are essentially constrained to climate-mediated pulses (30 years or less) of encroachment occurring at the thermal limits of mangroves. In this study, we track the continuous, lateral encroachment of mangroves into two south-eastern Australian salt marshes over a period of 70 years and quantify corresponding changes in biomass and belowground C stores. Substantial increases in biomass and belowground C stores have resulted as mangroves replaced salt marsh at both marine and estuarine sites. After 30 years, aboveground biomass was significantly higher than salt marsh, with biomass continuing to increase with mangrove age. Biomass increased at the mesohaline river site by 130 ± 18 Mg biomass km(-2)  yr(-1) (mean ± SE), a 2.5 times higher rate than the marine embayment site (52 ± 10 Mg biomass km(-2) yr(-1) ), suggesting local constraints on biomass production. At both sites, and across all vegetation categories, belowground C considerably outweighed aboveground biomass stocks, with belowground C stocks increasing at up to 230 ± 62 Mg C km(-2) yr(-1) (± SE) as mangrove forests developed. Over the past 70 years, we estimate mangrove encroachment may have already enhanced intertidal biomass by up to 283 097 Mg and belowground C stocks by over 500 000 Mg in the state of New South Wales alone. Under changing climatic conditions and rising sea levels, global blue carbon storage may be enhanced as mangrove encroachment becomes more widespread, thereby countering global warming. PMID:26670941

  8. Seventy years of continuous encroachment substantially increases 'blue carbon' capacity as mangroves replace intertidal salt marshes.

    PubMed

    Kelleway, Jeffrey J; Saintilan, Neil; Macreadie, Peter I; Skilbeck, Charles G; Zawadzki, Atun; Ralph, Peter J

    2016-03-01

    Shifts in ecosystem structure have been observed over recent decades as woody plants encroach upon grasslands and wetlands globally. The migration of mangrove forests into salt marsh ecosystems is one such shift which could have important implications for global 'blue carbon' stocks. To date, attempts to quantify changes in ecosystem function are essentially constrained to climate-mediated pulses (30 years or less) of encroachment occurring at the thermal limits of mangroves. In this study, we track the continuous, lateral encroachment of mangroves into two south-eastern Australian salt marshes over a period of 70 years and quantify corresponding changes in biomass and belowground C stores. Substantial increases in biomass and belowground C stores have resulted as mangroves replaced salt marsh at both marine and estuarine sites. After 30 years, aboveground biomass was significantly higher than salt marsh, with biomass continuing to increase with mangrove age. Biomass increased at the mesohaline river site by 130 ± 18 Mg biomass km(-2)  yr(-1) (mean ± SE), a 2.5 times higher rate than the marine embayment site (52 ± 10 Mg biomass km(-2) yr(-1) ), suggesting local constraints on biomass production. At both sites, and across all vegetation categories, belowground C considerably outweighed aboveground biomass stocks, with belowground C stocks increasing at up to 230 ± 62 Mg C km(-2) yr(-1) (± SE) as mangrove forests developed. Over the past 70 years, we estimate mangrove encroachment may have already enhanced intertidal biomass by up to 283 097 Mg and belowground C stocks by over 500 000 Mg in the state of New South Wales alone. Under changing climatic conditions and rising sea levels, global blue carbon storage may be enhanced as mangrove encroachment becomes more widespread, thereby countering global warming.

  9. The use of lipid markers to define sources of organic matter in sediment and food web of the intertidal salt-marsh-flat ecosystem of Mont-Saint-Michel Bay, France

    NASA Astrophysics Data System (ADS)

    Meziane, Tarik; Bodineau, Laurent; Retiere, Christian; Thoumelin, Guy

    1997-12-01

    Salt marsh plants and seven surface sediment samples along a transect in the intertidal flat area of Mont-Saint-Michel Bay were analysed for fatty acids and sterols. The presence of lipid markers of halophytes (long-chain fatty acids, 18:3ω3, and phytosterols) in the surface layers of the sediment confirms the export of organic matter from the salt marsh to the intertidal flat. The spatial distribution of this organic matter over the tidal-flat area was controlled by the tidal currents and the presence of mussel beds. Lipid markers of diatoms (20:5ω3 and brassicasterol) and bacteria (18:1ω7 and odd, linear and branched, fatty acids) were also found in the surface sediments. Diatoms and benthic bacteria as well as organic matter from the salt marsh were the significant food sources available to the macrozoobenthos on the intertidal flat. The ingestion of these food types by the dominant species of the macrozoobenthos was confirmed by the presence of their respective lipid markers in the animals. The presence of these markers in animals subjected to a starvation experiment confirmed that these food types are really assimilated. The lipid composition of the starved animals indicated that the species studied were able to accumulate the fatty acid 20:5ω3 (considered to be a diatom marker), and that the annelid Nereis diversicolor supported an internal bacterial population.

  10. Vulnerability of Northeastern U.S. Salt Marshes to Climatic and Anthropogenic Stressors

    EPA Science Inventory

    In the Northeastern U.S., salt marsh area is in decline. Habitat change analysis has revealed fragmentation, displacement of high marsh by low marsh species, and marsh drowning, while development of adjacent uplands limits upslope migration. Using inundation experiments, field s...

  11. Restoration of Tidal Flow to Impounded Salt Marsh Exerts Mixed Effect on Leaf Litter Decomposition

    NASA Astrophysics Data System (ADS)

    Henry, B. A.; Schade, J. D.; Foreman, K.

    2015-12-01

    Salt marsh impoundments (e.g. roads, levees) disconnect marshes from ocean tides, which impairs ecosystem services and often promotes invasive species. Numerous restoration projects now focus on removing impoundments. Leaf litter decomposition is a central process in salt marsh carbon and nutrient cycles, and this study investigated the extent to which marsh restoration alters litter decomposition rates. We considered three environmental factors that can potentially change during restoration: salinity, tidal regime, and dominant plant species. A one-month field experiment (Cape Cod, MA) measured decay of litter bags in impounded, restored, and natural marshes under ambient conditions. A two-week lab experiment measured litter decay in controlled incubations under experimental treatments for salinity (1ppt and 30 ppt), tidal regime (inundated and 12 hr wet-dry cycles), and plant species (native Spartina alterniflora and invasive Phragmites australis). S. alterniflora decomposed faster in situ than P. australis (14±1.0% mass loss versus 0.74±0.69%). Corroborating this difference in decomposition, S. alterniflora supported greater microbial respiration during lab incubation, measured as CO2 flux from leaf litter and biological oxygen demand of water containing leached organic matter (OM). However, nutrient analysis of plant tissue and leached OM show P. australis released more nitrogen than S. alterniflora. Low salinity treatments in both lab and field experiments decayed more rapidly than high salinity treatments, suggesting that salinity inhibited microbial activity. Manipulation of inundation regime did not affect decomposition. These findings suggest the reintroduction of tidal flow to an impounded salt marsh can have mixed effects; recolonization by the native cordgrass could supply labile OM to sediment and slow carbon sequestration, while an increase in salinity might inhibit decomposition and accelerate sequestration.

  12. Diversity, composition, and geographical distribution of microbial communities in California salt marsh sediments

    USGS Publications Warehouse

    Cordova-Kreylos, A. L.; Cao, Y.; Green, P.G.; Hwang, H.-M.; Kuivila, K.M.; LaMontagne, M.G.; Van De Werfhorst, L. C.; Holden, P.A.; Scow, K.M.

    2006-01-01

    The Pacific Estuarine Ecosystem Indicators Research Consortium seeks to develop bioindicators of toxicant-induced stress and bioavailability for wetland biota. Within this framework, the effects of environmental and pollutant variables on microbial communities were studied at different spatial scales over a 2-year period. Six salt marshes along the California coastline were characterized using phospholipid fatty acid (PLFA) analysis and terminal restriction fragment length polymorphism (TRFLP) analysis. Additionally, 27 metals, six currently used pesticides, total polychlorinated biphenyls and polycyclic aromatic hydrocarbons, chlordanes, nonachlors, dichlorodiphenyldichloroethane, and dichlorodiphenyldichloroethylene were analyzed. Sampling was performed over large (between salt marshes), medium (stations within a marsh), and small (different channel depths) spatial scales. Regression and ordination analysis suggested that the spatial variation in microbial communities exceeded the variation attributable to pollutants. PLFA analysis and TRFLP canonical correspondence analysis (CCA) explained 74 and 43% of the variation, respectively, and both methods attributed 34% of the variation to tidal cycles, marsh, year, and latitude. After accounting for spatial variation using partial CCA, we found that metals had a greater effect on microbial community composition than organic pollutants had. Organic carbon and nitrogen contents were positively correlated with PLFA biomass, whereas total metal concentrations were positively correlated with biomass and diversity. Higher concentrations of heavy metals were negatively correlated with branched PLFAs and positively correlated with methyl- and cyclo-substituted PLFAs. The strong relationships observed between pollutant concentrations and some of the microbial indicators indicated the potential for using microbial community analyses in assessments of the ecosystem health of salt marshes. Copyright ?? 2006, American Society for

  13. Foundation species' overlap enhances biodiversity and multifunctionality from the patch to landscape scale in southeastern United States salt marshes.

    PubMed

    Angelini, Christine; van der Heide, Tjisse; Griffin, John N; Morton, Joseph P; Derksen-Hooijberg, Marlous; Lamers, Leon P M; Smolders, Alfons J P; Silliman, Brian R

    2015-07-22

    Although there is mounting evidence that biodiversity is an important and widespread driver of ecosystem multifunctionality, much of this research has focused on small-scale biodiversity manipulations. Hence, which mechanisms maintain patches of enhanced biodiversity in natural systems and if these patches elevate ecosystem multifunctionality at both local and landscape scales remain outstanding questions. In a 17 month experiment conducted within southeastern United States salt marshes, we found that patches of enhanced biodiversity and multifunctionality arise only where habitat-forming foundation species overlap--i.e. where aggregations of ribbed mussels (Geukensia demissa) form around cordgrass (Spartina alterniflora) stems. By empirically scaling up our experimental results to the marsh platform at 12 sites, we further show that mussels--despite covering only approximately 1% of the marsh surface--strongly enhance five distinct ecosystem functions, including decomposition, primary production and water infiltration rate, at the landscape scale. Thus, mussels create conditions that support the co-occurrence of high densities of functionally distinct organisms within cordgrass and, in doing so, elevate salt marsh multifunctionality from the patch to landscape scale. Collectively, these findings suggest that patterns in foundation species' overlap drive variation in biodiversity and ecosystem functioning within and across natural ecosystems.We therefore argue that foundation species should be integrated in our conceptual understanding of forces that moderate biodiversity--ecosystem functioning relationships, approaches for conserving species diversity and strategies to improve the multifunctionality of degraded ecosystems.

  14. Foundation species' overlap enhances biodiversity and multifunctionality from the patch to landscape scale in southeastern United States salt marshes

    PubMed Central

    Angelini, Christine; van der Heide, Tjisse; Griffin, John N.; Morton, Joseph P.; Derksen-Hooijberg, Marlous; Lamers, Leon P. M.; Smolders, Alfons J. P.; Silliman, Brian R.

    2015-01-01

    Although there is mounting evidence that biodiversity is an important and widespread driver of ecosystem multifunctionality, much of this research has focused on small-scale biodiversity manipulations. Hence, which mechanisms maintain patches of enhanced biodiversity in natural systems and if these patches elevate ecosystem multifunctionality at both local and landscape scales remain outstanding questions. In a 17 month experiment conducted within southeastern United States salt marshes, we found that patches of enhanced biodiversity and multifunctionality arise only where habitat-forming foundation species overlap—i.e. where aggregations of ribbed mussels (Geukensia demissa) form around cordgrass (Spartina alterniflora) stems. By empirically scaling up our experimental results to the marsh platform at 12 sites, we further show that mussels—despite covering only approximately 1% of the marsh surface—strongly enhance five distinct ecosystem functions, including decomposition, primary production and water infiltration rate, at the landscape scale. Thus, mussels create conditions that support the co-occurrence of high densities of functionally distinct organisms within cordgrass and, in doing so, elevate salt marsh multifunctionality from the patch to landscape scale. Collectively, these findings suggest that patterns in foundation species' overlap drive variation in biodiversity and ecosystem functioning within and across natural ecosystems. We therefore argue that foundation species should be integrated in our conceptual understanding of forces that moderate biodiversity–ecosystem functioning relationships, approaches for conserving species diversity and strategies to improve the multifunctionality of degraded ecosystems. PMID:26136442

  15. Assessing the Wildlife Habitat Value of New England Salt Marshes: I. Model and Application

    EPA Science Inventory

    We developed an assessment model to quantify the wildlife habitat value of New England salt marshes based on marsh characteristics and the presence of habitat types that influence habitat use by terrestrial wildlife. Applying the model to12 salt marshes located in Narragansett B...

  16. Soil Respiration and Belowground Carbon Stores Among Salt Marshes Subjected to Increasing Watershed Nitrogen Loadings in Southern New England

    EPA Science Inventory

    Coastal salt marshes are ecosystems located between the uplands and sea, and because of their location are subject to increasing watershed nutrient loadings and rising sea levels. Residential development along the coast is intense, and there is a significant relationship between...

  17. Links Between Watershed Activities and the Degradation of Coastal, Tidal Salt Marshes in Southern New England USA

    EPA Science Inventory

    Human activities (e.g., land development, wastewater) in coastal watersheds in New England USA are linked with community- and system-level changes in tidal, organic-rich salt marshes. Significant relationships between various indicators of watershed activities and ecosystem stru...

  18. Seasonal variability of denitrification efficiency in northern salt marshes: an example from the St. Lawrence Estuary.

    PubMed

    Poulin, Patrick; Pelletier, Emilien; Saint-Louis, Richard

    2007-06-01

    In coastal ecosystems, denitrification is a key process in removing excess dissolved nitrogen oxides and participating in the control of eutrophication process. Little is known about the role of salt marshes on nitrogen budgets in cold weather coastal areas. Although coastal salt marshes are important sites for organic matter degradation and nutrient regeneration, bacterial-mediated nitrogen cycling processes, such as denitrification, remain unknown in northern and sub-arctic regions, especially under winter conditions. Using labelled nitrogen (15N), denitrification rates were measured in an eastern Canadian salt marsh in August, October and December 2005. Freshly sampled undisturbed sediment cores were incubated over 8h and maintained at their sampling temperatures to evaluate the influence of low temperatures on the denitrification rate. From 2 to 12 degrees C, average denitrification rate and dissolved oxygen consumption increased from 9.6 to 25.5 micromol N2 m-2 h-1 and from 1.3 to 1.8 mmol O2 m-2 h-1, respectively, with no statistical dependence of temperature (p>0.05). Nitrification has been identified as the major nitrate source for denitrification, supplying more than 80% of the nitrate demand. Because no more than 31% of the nitrate removed by sediment is estimated to be denitrified, the presence of a major nitrate sink in sediment is suspected. Among possible nitrate consumption mechanisms, dissimilatory reduction of nitrate to ammonium, metal and organic matter oxidation processes are discussed. Providing the first measurements of denitrification rate in a St. Lawrence Estuary salt marsh, this study evidences the necessity of preserving and restoring marshes. They constitute an efficient geochemical filter against an excess of nitrate dispersion to coastal waters even under cold northern conditions. PMID:17276505

  19. Characterization of marine debris in North Carolina salt marshes.

    PubMed

    Viehman, Shay; Vander Pluym, Jenny L; Schellinger, Jennifer

    2011-12-01

    Marine debris composition, density, abundance, and accumulation were evaluated in salt marshes in Carteret County, North Carolina seasonally between 2007 and 2009. We assessed relationships between human use patterns and debris type. Wave effects on marine debris density were examined using a GIS-based forecasting tool. We assessed the influence of site wave exposure, period, and height on debris quantity. Presence and abundance of debris were related to wave exposure, vegetation type and proximity of the strata to human population and human use patterns. Plastic pieces accounted for the majority of all debris. Small debris (0-5 cm) was primarily composed of foam pieces and was frequently affiliated with natural wrack. Large debris (>100 cm) was encountered in all marsh habitat types surveyed and was primarily composed of anthropogenic wood and derelict fishing gear. Marsh cleanup efforts should be targeted to specific habitat types or debris types to minimize further damage to sensitive habitats.

  20. Salt Marsh Formation in the Lower Hudson River Estuary

    NASA Technical Reports Server (NTRS)

    Merley, Michael; Peteet, Dorothy; Hansen, James E. (Technical Monitor)

    2001-01-01

    Salt marshes are constant depositional environments and as a result contain accurate indicators of past relative sea level rise and salinity. The Hudson River marshes are at least twice as deep when compared to coastal marshes on either side of the mouth of the Hudson. The reason for this difference in sedimentation is unclear. This study uses macrofossil data as well as sediment stratigraphy in order to understand the formation and evolution of these marshes. The composition of seeds, roots, shoots and foraminifera, are used to indicate past sea levels. The four sites involved in this study are, from south to north, the Arthur Kill Marsh in Staten Island (40 36 N, 74 77W), Piermont marsh (N 4100; 73 55W) Croton Point (41 14 N; 73 50W) and Iona Island (41 18N, 73 58W). These are all tidally influenced but with increasing distances from the New York Bight, which gives a good spectrum of tidal influence. AMS-C14 dates on basal macrofossils will document the time of each marsh formation. Basal material from Arthur Kill (8 m) includes freshwater seeds such as Viola, Potomageton and Alnus along with Salix buds. Basal material from Croton Point (10 m) includes fibrous woody material, foraminifera and Zanichellia seeds and other brackish vegetational components. The basal material from Piermont (13.77 m) is lacking any identifiable macrofossils between 150 and 500 microns. The basal material from Iona Island (10 m) has vegetation such as Scirpus and Cyperus seeds, probably implying a brackish environment. The freshwater origin of the Arthur Kill marsh in Staten Island is significant because it predates either sea level rise or the western channel incision. Additional implications for this study include evidence for changes in river channel geomorphology. Reasons for the relatively deeper river marshes include possible basal clay compaction, high production due to river and marine nutrients as well as tectonic activity. This study provides the groundwork for more high

  1. Salt Marsh Formation in the Lower Hudson River Estuary

    NASA Astrophysics Data System (ADS)

    Merley, M. M.; Peteet, D. M.; Peteet, D. M.

    2001-05-01

    Salt marshes are constant depositional environments and as a result contain accurate indicators of past relative sea level rise and salinity. The Hudson River marshes are at least twice as deep when compared to coastal marshes on either side of the mouth of the Hudson. The reason for this difference in sedimentation is unclear. This study uses macrofossil data as well as sediment stratigraphy in order to understand the formation and evolution of these marshes. The composition of seeds, roots, shoots and foraminifera, are used to indicate past sea levels. The four sites involved in this study are, from south to north, the Arthur Kill Marsh in Staten Island ( 40 36 N, 74 77W), Piermont marsh (N 41 00; 73 55W) Croton Point ( 41 14 N; 73 50W) and Iona Island( 41 18N, 73 58W). These are all tidally influenced but with increasing distances from the New York Bight, which gives a good spectrum of tidal influence. AMS-C14 dates on basal macrofossils will document the time of each marsh formation. Basal material from Arthur Kill (8m) includes freshwater seeds such as Viola, Potomageton and Alnus along with Salix buds. Basal material from Croton Point (10m) includes fibrous woody material, foraminifera and Zanichellia seeds and other brackish vegetational components. The basal material from Piermont (13.77m) is lacking any identifyable macrofossils between 150 and 500 microns. The basal material from Iona Island (10m) has vegetation such as Scirpus and Cyperus seeds, probably implying a brackish environment. The freshwater origin of the Arthur Kill marsh in Staten Island is significant because it predates either sea level rise or the western channel incision. Additional implications for this study include evidence for changes in river channel geomorphology. Reasons for the relatively deeper river marshes include possible basal clay compaction, high production due to river and marine nutrients as well as tectonic activity. This study provides the groundwork for more high

  2. Biogeochemical effects of seawater restoration to diked salt marshes

    USGS Publications Warehouse

    Portnoy, J.W.; Giblin, A.E.

    1997-01-01

    We conducted greenhouse microcosm experiments to examine the biogeochemical effects of restoring seawater to historically diked Cape Cod salt marshes. Peat cores from both seasonally flooded and drained diked marshes were waterlogged with seawater, and porewater chemistry was subsequently monitored for 21 mo. The addition of seawater to highly organic, seasonally flooded peat caused the death of freshwater wetland plants, 6-8 cm of sediment subsidence, and increased N and P mineralization. Also, sulfides and alkalinity increased 10-fold, suggesting accelerated decomposition by sulfate reduction. Addition of seawater to the low-organic-content acidic peat from the drained marsh increased porewater pH, alkalinity, PO4-P, and Fe(II), which we attribute to the reestablishment of SO4 and Fe(III) mineral reduction. Increased cation exchange contributed to 6-fold increases in dissolved Fe(II) and Al and 60-fold increases in NH4-N within 6 mo of sail-nation. Seawater reintroductions to seasonally flooded diked marshes will cause porewater sulfides to increase, likely reducing the success of revegetation efforts. Sulfide toxicity is of less concern in resalinated drained peats because of the abundance of Fe(II) to precipitate sulfides, and of NH4-N to offset sulfide inhibition of N uptake. Restoration of either seasonally flooded or drained diked marshes could stimulate potentially large nutrient and Fe(II) releases, which could in turn increase primary production and lower oxygen in receiving waters. These findings suggest that tidal restoration be gradual and carefully monitored.

  3. Connectivity Among Salt Marsh Subhabitats: Residency and Movements of the Mummichog (Fundulus heteroclitus)

    EPA Science Inventory

    We examined connectivity among marsh subhabitats to determine the structural limits and important components of a polyhaline salt marsh by studying the patterns of abundance, residency, and movement of a numerically and ecologically dominant nektonic fish (mummichog, Fundulus het...

  4. Effects of livestock species and stocking density on accretion rates in grazed salt marshes

    NASA Astrophysics Data System (ADS)

    Nolte, Stefanie; Esselink, Peter; Bakker, Jan P.; Smit, Christian

    2015-01-01

    Coastal ecosystems, such as salt marshes, are threatened by accelerated sea-level rise (SLR). Salt marshes deliver valuable ecosystem services such as coastal protection and the provision of habitat for a unique flora and fauna. Whether salt marshes in the Wadden Sea area are able to survive accelerated SLR depends on sufficient deposition of sediments which add to vertical marsh accretion. Accretion rate is influenced by a number of factors, and livestock grazing was recently included. Livestock grazing is assumed to reduce accretion rates in two ways: (a) directly by increasing soil compaction through trampling, and (b) indirectly by affecting the vegetation structure, which may lower the sediment deposition. For four years, we studied the impact of two livestock species (horse and cattle) at two stocking densities (0.5 and 1.0 animal ha-1) on accretion in a large-scale grazing experiment using sedimentation plates. We found lower cumulative accretion rates in high stocking densities, probably because more animals cause more compaction and create a lower canopy. Furthermore, a trend towards lower accretion rates in horse-compared to cattle-grazed treatments was found, most likely because (1) horses are more active and thus cause more compaction, and (2) herbage intake by horses is higher than by cattle, which causes a higher biomass removal and shorter canopy. During summer periods, negative accretion rates were found. When the grazing and non-grazing seasons were separated, the impact of grazing differed among years. In summer, we only found an effect of different treatments if soil moisture (precipitation) was relatively low. In winter, a sufficiently high inundation frequency was necessary to create differences between grazing treatments. We conclude that stocking densities, and to a certain extent also livestock species, affect accretion rates in salt marshes. Both stocking densities and livestock species should thus be taken into account in management

  5. Groundwater controls ecological zonation of salt marsh macrophytes.

    PubMed

    Wilson, Alicia M; Evans, Tyler; Moore, Willard; Schutte, Charles A; Joye, Samantha B; Hughes, Andrea H; Anderson, Joseph L

    2015-03-01

    Ecological zonation of salt marsh macrophytes is strongly influenced by hydrologic factors, but these factors are poorly understood. We examined groundwater flow patterns through surficial sediments in two saltmarshes in the southeastern United States to quantify hydrologic differences between distinct ecological zones. Both sites included tall- or medium-form Spartina alterniflora near the creek bank; short-form Spartina alterniflora in the mid-marsh; salt flats and Salicornia virginica in the high marsh; and Juncus roemarianus in brackish-to-fresh areas adjacent to uplands. Both sites had relatively small, sandy uplands and similar stratigraphy consisting of marsh muds overlying a deeper sand layer. We found significant hydrologic differences between the four ecological zones. In the zones colonized by S. alterniflora, the vertical flow direction oscillated with semi-diurnal tides. Net flow (14-day average) through the tall S. alterniflora zones was downward, whereas the short S. alterniflora zones included significant periods of net upward groundwater flow. An examination of tidal efficiency at these sites suggested that the net flow patterns rather than tidal damping controlled the width of the tall S. alterniflora zone. In contrast to the S. alterniflora zones, hypersaline zones populated by S. virginica were characterized by sustained periods (days) of continuous upward flow of saline water during neap tides. The fresher zone populated by J. roemarianus showed physical flow patterns that were similar to the hypersaline zones, but the upwelling porewaters were fresh rather than saline. These flow patterns were influenced by the hydrogeologic framework of the marshes, particularly differences in hydraulic head between the upland water table and the tidal creeks. We observed increases in hydraulic head of approximately 40 cm from the creek to the upland in the sand layers below both marshes, which is consistent with previous observations that sandy aquifers

  6. Groundwater controls ecological zonation of salt marsh macrophytes.

    PubMed

    Wilson, Alicia M; Evans, Tyler; Moore, Willard; Schutte, Charles A; Joye, Samantha B; Hughes, Andrea H; Anderson, Joseph L

    2015-03-01

    Ecological zonation of salt marsh macrophytes is strongly influenced by hydrologic factors, but these factors are poorly understood. We examined groundwater flow patterns through surficial sediments in two saltmarshes in the southeastern United States to quantify hydrologic differences between distinct ecological zones. Both sites included tall- or medium-form Spartina alterniflora near the creek bank; short-form Spartina alterniflora in the mid-marsh; salt flats and Salicornia virginica in the high marsh; and Juncus roemarianus in brackish-to-fresh areas adjacent to uplands. Both sites had relatively small, sandy uplands and similar stratigraphy consisting of marsh muds overlying a deeper sand layer. We found significant hydrologic differences between the four ecological zones. In the zones colonized by S. alterniflora, the vertical flow direction oscillated with semi-diurnal tides. Net flow (14-day average) through the tall S. alterniflora zones was downward, whereas the short S. alterniflora zones included significant periods of net upward groundwater flow. An examination of tidal efficiency at these sites suggested that the net flow patterns rather than tidal damping controlled the width of the tall S. alterniflora zone. In contrast to the S. alterniflora zones, hypersaline zones populated by S. virginica were characterized by sustained periods (days) of continuous upward flow of saline water during neap tides. The fresher zone populated by J. roemarianus showed physical flow patterns that were similar to the hypersaline zones, but the upwelling porewaters were fresh rather than saline. These flow patterns were influenced by the hydrogeologic framework of the marshes, particularly differences in hydraulic head between the upland water table and the tidal creeks. We observed increases in hydraulic head of approximately 40 cm from the creek to the upland in the sand layers below both marshes, which is consistent with previous observations that sandy aquifers

  7. Distribution and metabolism of quaternary amines in salt marshes

    NASA Technical Reports Server (NTRS)

    King, Gary M.

    1985-01-01

    Quaternary amines such as glycine betaine (GBT) are common osmotically active solutes in much of the marine biota. GBT is accumulated by various bacteria, algae, higher plants, invertebrates, and vertebrates in response to salinity or water stresses; in some species, GBT occurs at tens to hundreds of millimolar concentrations and can account for a significant fraction of total nitrogen. Initial studies suggest that GBT is readily converted to two potential methane precursors, trimethylamine (TMA) and acetate, in anoxic sediments. TMA is apparently the most important methane precursor in surface sediments containing sulfate reducing bacteria. In salt marshes, the bulk of the methane formed may be due to the metabolism of TMA rather than other substrates. Current research is focussed on testing this hypothesis and on determining the role of quaternary amino osmoregulatory solutes in methane fluxes from marine environments. Preliminary studies have dealt with several problems: (1) determination of GBT concentrations in the dominant flora and fauna of salt marshes; (2) synthesis of radiolabelled GBT for metabolic studies; and (3) determination of fates of BGT in marine sediments using radiotracers. Both GC and HPLC techniques have been used to assay GBT concentrations in plant and animal tissues. S. alterniflora is probably the only significant source of GBT (and indirectly of methane) since the biomass and distribution of most other species is limited. Current estimates suggest that S. alterniflora GBT could account for most of the methane efflux from salt marshes.

  8. Disturbance and recovery of salt marsh arthropod communities following BP Deepwater Horizon oil spill.

    PubMed

    McCall, Brittany D; Pennings, Steven C

    2012-01-01

    Oil spills represent a major environmental threat to coastal wetlands, which provide a variety of critical ecosystem services to humanity. The U.S. Gulf of Mexico is a hub of oil and gas exploration activities that historically have impacted intertidal habitats such as salt marsh. Following the BP Deepwater Horizon oil spill, we sampled the terrestrial arthropod community and marine invertebrates found in stands of Spartina alterniflora, the most abundant plant in coastal salt marshes. Sampling occurred in 2010 as oil was washing ashore and a year later in 2011. In 2010, intertidal crabs and terrestrial arthropods (insects and spiders) were suppressed by oil exposure even in seemingly unaffected stands of plants; however, Littoraria snails were unaffected. One year later, crab and arthropods had largely recovered. Our work is the first attempt that we know of assessing vulnerability of the salt marsh arthropod community to oil exposure, and it suggests that arthropods are both quite vulnerable to oil exposure and quite resilient, able to recover from exposure within a year if host plants remain healthy. PMID:22412916

  9. Disturbance and Recovery of Salt Marsh Arthropod Communities following BP Deepwater Horizon Oil Spill

    PubMed Central

    McCall, Brittany D.; Pennings, Steven C.

    2012-01-01

    Oil spills represent a major environmental threat to coastal wetlands, which provide a variety of critical ecosystem services to humanity. The U.S. Gulf of Mexico is a hub of oil and gas exploration activities that historically have impacted intertidal habitats such as salt marsh. Following the BP Deepwater Horizon oil spill, we sampled the terrestrial arthropod community and marine invertebrates found in stands of Spartina alterniflora, the most abundant plant in coastal salt marshes. Sampling occurred in 2010 as oil was washing ashore and a year later in 2011. In 2010, intertidal crabs and terrestrial arthropods (insects and spiders) were suppressed by oil exposure even in seemingly unaffected stands of plants; however, Littoraria snails were unaffected. One year later, crab and arthropods had largely recovered. Our work is the first attempt that we know of assessing vulnerability of the salt marsh arthropod community to oil exposure, and it suggests that arthropods are both quite vulnerable to oil exposure and quite resilient, able to recover from exposure within a year if host plants remain healthy. PMID:22412916

  10. Disturbance and recovery of salt marsh arthropod communities following BP Deepwater Horizon oil spill.

    PubMed

    McCall, Brittany D; Pennings, Steven C

    2012-01-01

    Oil spills represent a major environmental threat to coastal wetlands, which provide a variety of critical ecosystem services to humanity. The U.S. Gulf of Mexico is a hub of oil and gas exploration activities that historically have impacted intertidal habitats such as salt marsh. Following the BP Deepwater Horizon oil spill, we sampled the terrestrial arthropod community and marine invertebrates found in stands of Spartina alterniflora, the most abundant plant in coastal salt marshes. Sampling occurred in 2010 as oil was washing ashore and a year later in 2011. In 2010, intertidal crabs and terrestrial arthropods (insects and spiders) were suppressed by oil exposure even in seemingly unaffected stands of plants; however, Littoraria snails were unaffected. One year later, crab and arthropods had largely recovered. Our work is the first attempt that we know of assessing vulnerability of the salt marsh arthropod community to oil exposure, and it suggests that arthropods are both quite vulnerable to oil exposure and quite resilient, able to recover from exposure within a year if host plants remain healthy.

  11. Modeling the Effects of Changes to Physical, Hydrological, and Biological Processes on Porewater Salinity Distributions in a Southeastern Salt Marsh

    NASA Astrophysics Data System (ADS)

    Miklesh, D.; Meile, C. D.

    2014-12-01

    Coastal wetlands provide many important ecosystem services, which include carbon and nitrogen sequestration and transformations, the provision of habitats, and the reduction of erosion by the vegetation. Coastal wetlands will be affected by projected climate change and sea level rise and may fail to provide such services, prompting a need to understand the environmental controls on marsh and vegetation distribution. Therefore, as part of the Georgia Coastal Ecosystems Long Term Ecological Research project, an integrated modeling approach is being developed to simulate how changes in salinity and inundation may change marsh ecosystem services, by coupling a hydrodynamic with a soil and a plant model. In coastal marsh ecosystems, porewater salinity strongly determines vegetation distribution and productivity. We will present the development of the soil model, which is based on mass conservation for water and salt and links physical, hydrological, and biological processes that determine porewater salinity, including precipitation, evapotranspiration, salt exchange between surface and subsurface, drainage, groundwater exchange, tidal inundation, and surface runoff, with the lateral exchange controlled by marsh topography. The model is applied to the Duplin River marsh, Sapelo Island, Georgia. Model validation is performed by comparing model-estimated salinities to porewater salinity measurements taken in different vegetation classes and over a range of marsh elevations. Modeled variability in porewater salinities will be presented over spring-neap, seasonal, and annual time scales. To discuss potential impacts of climate change and sea level rise, a sensitivity analysis will be presented that demonstrates the effect precipitation intensity, evapotranspiration, permeability, and marsh elevation have on porewater salinities.

  12. Differentiating salt marsh species using foreground/background analysis

    SciTech Connect

    Zhang, M.; Pinzon, J.; Ustin, S.L.; Rejmankova, E.

    1996-10-01

    Three California salt marsh plant species have distinctive morphologies that could be remotely sensed by airborne spectrometers because the architectures create differences in canopy reflectance characteristics. This paper presents a method to differentiate wetland species using a modified spectral mixture analysis termed hierarchical foreground and background analysis (HFBA). To validate this approach, the method was applied to field spectral data from several salt marshes. Foreground and background analysis allows the user to direct analysis along a specified axis of variance by identifying vectors through the n-dimensional spectral volume by identifying vectors that comprise the information of selected subset of spectra which emphasizes the presence of a discriminative signature of interest. The goal of FBA is to project spectral variation along the most relevant axis of variance that maximizes spectral differences between groups, while minimizing spectral variation within each group. For this work, we selected a training set that allowed us to create HFBA vectors which efficiently discriminate species based on canopy spectral characteristics. Results indicated that the dominant species in these salts marshes could be clearly differentiated with greater than 90% certainty from field collected canopy spectrometer data. Hundred percent of Spartina and 79% of Salicornia were correctly classified at the first level of classification. The accuracy of classification for Salicornia improved to 87% in the second level of classification. The unclassified spectral samples were related to extraordinary conditions within the wetlands such as extreme biomass, salinity and nitrogen conditions. These patterns were apparent in AVIRIS (Airborne Visible/infrared Imaging Spectrometer) images which showed distinct zonation corresponding to the distributions of these species in the marsh. Results were confirmed by field reconnaissance. 19 refs., 3 figs., 4 tabs.

  13. Sulfate reduction in the salt marshes at Sapelo Island, Georgia

    SciTech Connect

    Howarth, R.W.; Giblin, A.

    1983-01-01

    Sulfate reduction rates were measured in stands of Spartina alterniflora at Sapelo Island, Georgia, in November 1980 by injecting tracer amounts of /sup 35/SO/sub 4//sup 2 -/ into cores, incubating overnight, and analyzing for the incorporation of /sup 35/S into reduced sulfur compounds. Qualitatively, sulfate reduction in the Georgia marsh is very similar to that in the Massachusetts marshes the authors have studied: FeS/sup 2/ (pyrite or marcasite) is the major end product. Lesser amounts of soluble sulfides, iron monosulfides, and elemental sulfur are also formed. The rate of sulfate reduction (determined by the same method)is significantly lower during November in Georgia than in the Great Sippewissett Marsh in Massachusetts, 0.090 vs. 0.27 moles SO/sub 4//sup 2 -/xm/sup -2/xd/sup -1/ in stands of short Spartina. The lower rates in Georgia may reflect a lower rate of organic carbon input by below ground production. Sulfate reduction appears to be the major form of respiration in the sediments of salt marshes in Georgia as well as in Massachusetts.

  14. Salt marsh hydrology data web site facilitates research

    NASA Astrophysics Data System (ADS)

    Gardner, L. R.; Reeves, H. W.

    The interface between maritime forests and inter-tidal salt marshes along the southeastern coast of the United States is a major ecological boundary characterized by a sequence of botanical zones that typically consist of pine/ oak forest>Iva>Juncus>Salicornia>Spartina. In addition to questions regarding the physical and chemical factors that govern this ecotone, this interface is of interest because of the potential for groundwater flow to transfer nutrients and pollutants from developed uplands to the adjacent marshes. The interface is also of interest because it is presumably migrating upslope as a result of ongoing sea level rise and concomitant aquifer salinization.A new Web site, http://links.baruch.sc.edu/data/GRNDWATER/data/data.htm, contains long-term and spatially dense measurements of groundwater heads and salinity from a network of nested piezometers that has been installed along three forest-marsh transects across the Crab Haul Creek finger marsh basin at the North Inlet-Winyah Bay National Estuarine Research Reserve in Georgetown County South Carolina (Figure 1).

  15. Mercury Speciation, Retention and Genomics in Fertilized Salt Marsh Sediments

    NASA Astrophysics Data System (ADS)

    Collins, C. W.; Lamborg, C. H.; Whalen, K.; Mincer, T.; Buchanan, W.; Huber, J. A.; Swarr, G.; Ganguli, P. M.; Bernhard, A.

    2014-12-01

    Recent studies have demonstrated that increased nutrient loading and eutrophication can impact the production of monomethylmercury (MMHg) in marine systems. Experimental plots in Great Sippewisset Marsh (GSM), Falmouth, Massachusetts USA, have been chronically treated with a mixed fertilizer during the growing season since 1971, providing nutrients and other elements, including mercury (Hg) to the salt marsh. To assess the retention, release and methylation of Hg in these marsh sediments in response to fertilization, we collected cores from control, low, high, and extra high fertilization plots across low and high marsh settings. We determined total mercury (HgT) and MMHg concentration and accumulation rates and compared them to those of atmospheric deposition and the loading from the mixed fertilizer. Environmental DNA was extracted from the core sub-samples and polymerase chain reaction (PCR) was used to detect three genes of interest: merA (Hg(II) reducing), hgcA (Hg(II) methylating) and dsrAB (dissimilatory sulfite reduction). Quantitative PCR (qPCR) will be performed in order to overlay the abundance and diversity of the three genes to the Hg profiles and speciation metadata. By comparing the genomic data to the geochemical patterns within the treatment plots we can develop a greater sense of how Hg cycling has changed as a result of fertilization and the overall response of GSM to long-term nutrient loading.

  16. Consequences of climate change, eutrophication, and other anthropogenic impacts to coastal salt marshes: multiple stressors reduce resiliency and sustainability

    NASA Astrophysics Data System (ADS)

    Watson, E. B.; Wigand, C.; Nelson, J.; Davey, E.; Van Dyke, E.; Wasson, K.

    2011-12-01

    Coastal salt marshes provide a wide variety of ecosystem services, including habitat for protected vertebrates and ecologically valuable invertebrate fauna, flood protection, and improvements in water quality for adjacent marine and estuarine environments. Here, we consider the impacts of future sea level rise combined with other anthropogenic stressors to salt marsh sustainability through the implementation of field and laboratory mesocosms, manipulative experiments, correlative studies, and predictive modeling conducted in central California and southern New England salt marshes. We report on measurements of soil respiration, decomposition, sediment accumulation, and marsh elevation, which considered jointly suggest an association between nitrate input and marsh elevation loss resulting from mineralization of soil organic matter. Furthermore, use of imaging techniques (CT scans) has shown differences in belowground root and rhizome structure associated with fertilization, resulting in a loss of sediment cohesion promoted by fine root structure. Additionally, field and greenhouse mesocosm experiments have provided insight into the specific biogeochemical processes responsible for plant mortality at high immersion or salinity levels. In conclusion, we have found that poor water quality (i.e. eutrophication) leads to enhanced respiration and decomposition of soil organic matter, which ultimately contributes to a loss of salt marsh sustainability. However, marsh deterioration studied at field sites (Jamaica Bay, NY and Elkhorn Slough, CA) is associated not only with enhanced nutrient loads, but also increased immersion due to tidal range increases resulting from dredging. To ensure the continuation of the ecosystem services provided by tidal wetlands and to develop sustainable management strategies that provide favorable outcomes under a variety of future sea level rise and land use scenarios, we need to develop a better understanding of the relative impacts of the

  17. Role of crab herbivory in die-off of New England salt marshes.

    PubMed

    Holdredge, Christine; Bertness, Mark D; Altieri, Andrew H

    2009-06-01

    Die-offs of cordgrass are pervasive throughout western Atlantic salt marshes, yet understanding of the mechanisms precipitating these events is limited. We tested whether herbivory by the native crab, Sesarma reticulatum, is generating die-offs of cordgrass that are currently occurring on Cape Cod, Massachusetts (U.S.A.), by manipulating crab access to cordgrass transplanted into die-off areas and healthy vegetation. We surveyed 12 Cape Cod marshes to investigate whether the extent of cordgrass die-off on creek banks, where die-offs are concentrated, was related to local Sesarma grazing intensity and crab density. We then used archived aerial images to examine whether creek bank die-off areas have expanded over the past 2 decades and tested the hypothesis that release from predation, leading to elevated Sesarma densities, is triggering cordgrass die-offs by tethering crabs where die-offs are pervasive and where die-offs have not yet been reported. Intensity of crab grazing on transplanted cordgrass was an order of magnitude higher in die-off areas than in adjacent vegetation. Surveys revealed that Sesarma herbivory has denuded nearly half the creek banks in Cape Cod marshes, and differences in crab-grazing intensity among marshes explained >80% of variation in the extent of the die-offs. Moreover, the rate of die-off expansion and area of marsh affected have more than doubled since 2000. Crab-tethering experiments suggest that release from predation has triggered elevated crab densities that are driving these die-offs, indicating that disruption of predator-prey interactions may be generating the collapse of marsh ecosystems previously thought to be exclusively under bottom-up control.

  18. Vulnerability of Northeastern U.S. Salt Marshes to Climatic and Anthropogenic Stressors (AGU)

    EPA Science Inventory

    In the Northeastern U.S., salt marsh area is in decline. Habitat change analysis has revealed fragmentation, displacement of high marsh by low marsh species, and ecological drowning, while development of adjacent uplands limits upslope migration. Using inundation experiments, fi...

  19. Impacts of the Deepwater Horizon oil spill on the salt marsh vegetation of Louisiana.

    PubMed

    Hester, Mark W; Willis, Jonathan M; Rouhani, Shahrokh; Steinhoff, Marla A; Baker, Mary C

    2016-09-01

    The coastal wetland vegetation component of the Deepwater Horizon oil spill Natural Resource Damage Assessment documented significant injury to the plant production and health of Louisiana salt marshes exposed to oiling. Specifically, marsh sites experiencing trace or greater vertical oiling of plant tissues displayed reductions in cover and peak standing crop relative to reference (no oiling), particularly in the marsh edge zone, for the majority of this four year study. Similarly, elevated chlorosis of plant tissue, as estimated by a vegetation health index, was detected for marsh sites with trace or greater vertical oiling in the first two years of the study. Key environmental factors, such as hydrologic regime, elevation, and soil characteristics, were generally similar across plant oiling classes (including reference), indicating that the observed injury to plant production and health was the result of plant oiling and not potential differences in environmental setting. Although fewer significant impacts to plant production and health were detected in the latter years of the study, this is due in part to decreased sample size occurring as a result of erosion (shoreline retreat) and resultant loss of plots, and should not be misconstrued as indicating full recovery of the ecosystem. PMID:27299994

  20. Ecological succession reveals potential signatures of marine-terrestrial transition in salt marsh fungal communities.

    PubMed

    Dini-Andreote, Francisco; Pylro, Victor Satler; Baldrian, Petr; van Elsas, Jan Dirk; Salles, Joana Falcão

    2016-08-01

    Marine-to-terrestrial transition represents one of the most fundamental shifts in microbial life. Understanding the distribution and drivers of soil microbial communities across coastal ecosystems is critical given the roles of microbes in soil biogeochemistry and their multifaceted influence on landscape succession. Here, we studied the fungal community dynamics in a well-established salt marsh chronosequence that spans over a century of ecosystem development. We focussed on providing high-resolution assessments of community composition, diversity and ecophysiological shifts that yielded patterns of ecological succession through soil formation. Notably, despite containing 10- to 100-fold lower fungal internal transcribed spacer abundances, early-successional sites revealed fungal richnesses comparable to those of more mature soils. These newly formed sites also exhibited significant temporal variations in β-diversity that may be attributed to the highly dynamic nature of the system imposed by the tidal regime. The fungal community compositions and ecophysiological assignments changed substantially along the successional gradient, revealing a clear signature of ecological replacement and gradually transforming the environment from a marine into a terrestrial system. Moreover, distance-based linear modelling revealed soil physical structure and organic matter to be the best predictors of the shifts in fungal β-diversity along the chronosequence. Taken together, our study lays the basis for a better understanding of the spatiotemporally determined fungal community dynamics in salt marshes and highlights their ecophysiological traits and adaptation in an evolving ecosystem. PMID:26824176

  1. Man's Impact on the Environment: The Freshwater Marsh as an Ecosystem.

    ERIC Educational Resources Information Center

    Brevard County School Board, Cocoa, FL.

    This teaching guide deals with the ecological composition of a marsh and the ecological effects certain changes might have on a marsh. This study focuses on the fresh water marsh found in the Florida Everglades which can furnish the student with several examples of past, present, and possible future ecological changes which impact this ecosystem.…

  2. Effects of warming and altered precipitation on plant and nutrient dynamics of a New England salt marsh.

    PubMed

    Charles, Heather; Dukes, Jeffrey S

    2009-10-01

    Salt marsh structure and function, and consequently ability to support a range of species and to provide ecosystem services, may be affected by climate change. To better understand how salt marshes will respond to warming and associated shifts in precipitation, we conducted a manipulative experiment in a tidal salt marsh in Massachusetts, USA. We exposed two plant communities (one dominated by Spartina patens-Distichlis spicata and one dominated by short form Spartina alternifora) to five climate manipulations: warming via passive open-topped chambers, doubled precipitation, warming and doubled precipitation, extreme drought via rainout shelter, and ambient conditions. Modest daytime warming increased total aboveground biomass of the S. alterniflora community (24%), but not the S. patens-D. spicata community. Warming also increased maximum stem heights of S. alterniflora (8%), S. patens (8%), and D. spicata (15%). Decomposition was marginally accelerated by warming in the S. alternifora community. Drought markedly increased total biomass of the S. alterniflora community (53%) and live S. patens (69%), perhaps by alleviating waterlogging of sediments. Decomposition was accelerated by increased precipitation and slowed by drought, particularly in the S. patens-D. spicata community. Flowering phenology responded minimally to the treatments, and pore water salinity, sulfide, ammonium, and phosphate concentrations showed no treatment effects in either plant community. Our results suggest that these salt marsh communities may be resilient to modest amounts of warming and large changes in precipitation. If production increases under climate change, marshes will have a greater ability to keep pace with sea-level rise, although an increase in decomposition could offset this. As long as marshes are not inundated by flooding due to sea-level rise, increases in aboveground biomass and stem heights suggest that marshes may continue to export carbon and nutrients to coastal

  3. Loss of 'blue carbon' from coastal salt marshes following habitat disturbance.

    PubMed

    Macreadie, Peter I; Hughes, A Randall; Kimbro, David L

    2013-01-01

    Increased recognition of the global importance of salt marshes as 'blue carbon' (C) sinks has led to concern that salt marshes could release large amounts of stored C into the atmosphere (as CO2) if they continue undergoing disturbance, thereby accelerating climate change. Empirical evidence of C release following salt marsh habitat loss due to disturbance is rare, yet such information is essential for inclusion of salt marshes in greenhouse gas emission reduction and offset schemes. Here we investigated the stability of salt marsh (Spartinaalterniflora) sediment C levels following seagrass (Thallasiatestudinum) wrack accumulation; a form of disturbance common throughout the world that removes large areas of plant biomass in salt marshes. At our study site (St Joseph Bay, Florida, USA), we recorded 296 patches (7.5 ± 2.3 m(2) mean area ± SE) of vegetation loss (aged 3-12 months) in a salt marsh meadow the size of a soccer field (7 275 m(2)). Within these disturbed patches, levels of organic C in the subsurface zone (1-5 cm depth) were ~30% lower than the surrounding undisturbed meadow. Subsequent analyses showed that the decline in subsurface C levels in disturbed patches was due to loss of below-ground plant (salt marsh) biomass, which otherwise forms the main component of the long-term 'refractory' C stock. We conclude that disturbance to salt marsh habitat due to wrack accumulation can cause significant release of below-ground C; which could shift salt marshes from C sinks to C sources, depending on the intensity and scale of disturbance. This mechanism of C release is likely to increase in the future due to sea level rise; which could increase wrack production due to increasing storminess, and will facilitate delivery of wrack into salt marsh zones due to higher and more frequent inundation.

  4. Vegetation effects on fish distribution in impounded salt marshes

    USGS Publications Warehouse

    Stolen, Eric D.; Collazo, Jaime; Percival, H. Franklin

    2009-01-01

    We compared the density and biomass of resident fish in vegetated and unvegetated flooded habitats of impounded salt marshes in the northern Indian River Lagoon (IRL) Estuary of east-central Florida. A 1-m2 throw trap was used to sample fish in randomly located, paired sample plots (n = 198 pairs) over 5 seasons in 7 impoundments. We collected a total of 15 fish taxa, and 88% of the fishes we identified from the samples belonged to three species: Cyprinodon variegatus (Sheepshead Minnow), Gambusia holbrooki (Eastern Mosquitofish), and Poecilia latipinna (Sailfin Molly). Vegetated habitat usually had higher density and biomass of fish. Mean fish density (and 95% confidence interval) for vegetated and unvegetated sites were 8.2 (6.7–9.9) and 2.0 (1.6–2.4) individuals m-2, respectively; mean biomass (and 95%) confidence interval) for vegetated and unvegetated sites were 3.0 (2.5–3.7) and 1.1 (0.9–1.4) g m-2, respectively. We confirmed previous findings that impounded salt marshes of the northern IRL Estuary produce a high standing stock of resident fishes. Seasonal patterns of abundance were consistent with fish moving between vegetated and unvegetated habitat as water levels changed in the estuary. Differences in density, mean size, and species composition of resident fishes between vegetated and unvegetated habitats have important implications for movement of biomass and nutrients out of salt marsh by piscivores (e.g., wading birds and fishes) via a trophic relay.

  5. Salt marsh monitoring from remote sensing: vegetation and morphology

    NASA Astrophysics Data System (ADS)

    Belluco, E.; Camuffo, M.; D`Alpaos, A.; Silvestri, S.; Marani, A.; Marani, M.

    2003-04-01

    Lagoons are very sensitive components of coastal areas with high environmental value and a key buffer role between land and sea. In the present work we use remote sensing to study and monitor the Lagoon of Venice (Italy), an environment of great historical, environmental and socio-economic importance. The current state of the lagoon is the result of invasive human interventions during at least four centuries and many of the most recent interventions (e.g. artificial channel dredging and the construction/extensions of jetties at the lagoon mouths) showed the sensitivity and the importance of salt marshes as indicators of the trends of the entire tidal environment. Salt marshes, vegetated surfaces periodically flooded by the tide, were in fact deeply affected by such changes, and have virtually disappeared in some areas of the lagoon. We show that remote sensing is the ideal instrument for the monitoring, over large scales and with high resolutions, of these areas of difficult accessibility. We study vegetation and morphological changes of salt marshes at different spatial and temporal scales using accurately georeferenced field observations coupled to aerial (ROSIS, MIVIS, CASI, and LiDar) and satellite (IKONOS and QuickBird) remotely sensed data. We then analyze the spatial distribution and variability of some vegetation indicators (e.g. NDVI) and the typical patterns of vegetation clusters obtained through classification and unmixing techniques. Finally, we study the relationships between vegetation species and organisation and various topographic/geomorphic parameters (e.g. soil elevation, proximity to the channel network, etc.).

  6. Salt Marsh as a Coastal Filter for the Oceans: Changes in Function with Experimental Increases in Nitrogen Loading and Sea-Level Rise

    PubMed Central

    Nelson, Joanna L.; Zavaleta, Erika S.

    2012-01-01

    Coastal salt marshes are among Earth's most productive ecosystems and provide a number of ecosystem services, including interception of watershed-derived nitrogen (N) before it reaches nearshore oceans. Nitrogen pollution and climate change are two dominant drivers of global-change impacts on ecosystems, yet their interacting effects at the land-sea interface are poorly understood. We addressed how sea-level rise and anthropogenic N additions affect the salt marsh ecosystem process of nitrogen uptake using a field-based, manipulative experiment. We crossed simulated sea-level change and ammonium-nitrate (NH4NO3)-addition treatments in a fully factorial design to examine their potentially interacting effects on emergent marsh plants in a central California estuary. We measured above- and belowground biomass and tissue nutrient concentrations seasonally and found that N-addition had a significant, positive effect on a) aboveground biomass, b) plant tissue N concentrations, c) N stock sequestered in plants, and d) shoot:root ratios in summer. Relative sea-level rise did not significantly affect biomass, with the exception of the most extreme sea-level-rise simulation, in which all plants died by the summer of the second year. Although there was a strong response to N-addition treatments, salt marsh responses varied by season. Our results suggest that in our site at Coyote Marsh, Elkhorn Slough, coastal salt marsh plants serve as a robust N trap and coastal filter; this function is not saturated by high background annual N inputs from upstream agriculture. However, if the marsh is drowned by rising seas, as in our most extreme sea-level rise treatment, marsh plants will no longer provide the ecosystem service of buffering the coastal ocean from eutrophication. PMID:22879873

  7. Salt marsh as a coastal filter for the oceans: changes in function with experimental increases in nitrogen loading and sea-level rise.

    PubMed

    Nelson, Joanna L; Zavaleta, Erika S

    2012-01-01

    Coastal salt marshes are among Earth's most productive ecosystems and provide a number of ecosystem services, including interception of watershed-derived nitrogen (N) before it reaches nearshore oceans. Nitrogen pollution and climate change are two dominant drivers of global-change impacts on ecosystems, yet their interacting effects at the land-sea interface are poorly understood. We addressed how sea-level rise and anthropogenic N additions affect the salt marsh ecosystem process of nitrogen uptake using a field-based, manipulative experiment. We crossed simulated sea-level change and ammonium-nitrate (NH(4)NO(3))-addition treatments in a fully factorial design to examine their potentially interacting effects on emergent marsh plants in a central California estuary. We measured above- and belowground biomass and tissue nutrient concentrations seasonally and found that N-addition had a significant, positive effect on a) aboveground biomass, b) plant tissue N concentrations, c) N stock sequestered in plants, and d) shoot:root ratios in summer. Relative sea-level rise did not significantly affect biomass, with the exception of the most extreme sea-level-rise simulation, in which all plants died by the summer of the second year. Although there was a strong response to N-addition treatments, salt marsh responses varied by season. Our results suggest that in our site at Coyote Marsh, Elkhorn Slough, coastal salt marsh plants serve as a robust N trap and coastal filter; this function is not saturated by high background annual N inputs from upstream agriculture. However, if the marsh is drowned by rising seas, as in our most extreme sea-level rise treatment, marsh plants will no longer provide the ecosystem service of buffering the coastal ocean from eutrophication.

  8. Topsoil morphology indicates bio-effective redox conditions in Venice salt marshes

    NASA Astrophysics Data System (ADS)

    Lang, Friederike; von der Lippe, Moritz; Schimpel, Susanne; Scozzafava-Jaeger, Tiberio; Straub, Wolfgang

    2010-03-01

    Visual traces of iron reduction and oxidation are linked to the redox status of soils and have been used to characterise the quality of agricultural soils. We tested whether this feature could also be used to explain the spatial pattern of the natural vegetation of tidal habitats. If so, an easy assessment of the effect of rising sea level on tidal ecosystems would be possible. Our study was conducted at the salt marshes of the northern lagoon of Venice, which are strongly threatened by erosion and rising sea level and are part of the world heritage "Venice and its lagoon". We analysed the abundance of plant species at 255 sampling points along a land-sea gradient. In addition, we surveyed the redox morphology (presence/absence of red iron oxide mottles in the greyish topsoil horizons) of the soils and the presence of disturbances. We used indicator species analysis, correlation trees and multivariate regression trees to analyse relations between soil properties and plant species distribution. Plant species with known sensitivity to anaerobic conditions (e.g. Halimione portulacoides) were identified as indicators for oxic soils (showing iron oxide mottles within a greyish soil matrix). Plant species that tolerate a low redox potential (e.g. Spartina maritima) were identified as indicators for anoxic soils (greyish matrix without oxide mottles). Correlation trees and multivariate regression trees indicate the dominant role of the redox morphology of the soils in plant species distribution. In addition, the distance from the mainland and the presence of disturbances were identified as tree-splitting variables. The small-scale variation of oxygen availability plays a key role for the biodiversity of salt marsh ecosystems. Our results suggest that the redox morphology of salt marsh soils indicates the plant availability of oxygen. Thus, the consideration of this indicator may enable an understanding of the heterogeneity of biological processes in oxygen-limited systems

  9. Rhizosphere heterogeneity shapes abundance and activity of sulfur-oxidizing bacteria in vegetated salt marsh sediments

    PubMed Central

    Thomas, François; Giblin, Anne E.; Cardon, Zoe G.; Sievert, Stefan M.

    2014-01-01

    Salt marshes are highly productive ecosystems hosting an intense sulfur (S) cycle, yet little is known about S-oxidizing microorganisms in these ecosystems. Here, we studied the diversity and transcriptional activity of S-oxidizers in salt marsh sediments colonized by the plant Spartina alterniflora, and assessed variations with sediment depth and small-scale compartments within the rhizosphere. We combined next-generation amplicon sequencing of 16S rDNA and rRNA libraries with phylogenetic analyses of marker genes for two S-oxidation pathways (soxB and rdsrAB). Gene and transcript numbers of soxB and rdsrAB phylotypes were quantified simultaneously, using newly designed (RT)-qPCR assays. We identified a diverse assemblage of S-oxidizers, with Chromatiales and Thiotrichales being dominant. The detection of transcripts from S-oxidizers was mostly confined to the upper 5 cm sediments, following the expected distribution of root biomass. A common pool of species dominated by Gammaproteobacteria transcribed S-oxidation genes across roots, rhizosphere, and surrounding sediment compartments, with rdsrAB transcripts prevailing over soxB. However, the root environment fine-tuned the abundance and transcriptional activity of the S-oxidizing community. In particular, the global transcription of soxB was higher on the roots compared to mix and rhizosphere samples. Furthermore, the contribution of Epsilonproteobacteria-related S-oxidizers tended to increase on Spartina roots compared to surrounding sediments. These data shed light on the under-studied oxidative part of the sulfur cycle in salt marsh sediments and indicate small-scale heterogeneities are important factors shaping abundance and potential activity of S-oxidizers in the rhizosphere. PMID:25009538

  10. Quantifying vegetation and nekton response to tidal restoration of a New England salt marsh

    USGS Publications Warehouse

    Roman, C.T.; Raposa, K.B.; Adamowicz, S.C.; James-Pirri, M.J.; Catena, J.G.

    2002-01-01

    Tidal flow to salt marshes throughout the northeastern United States is often restricted by roads, dikes, impoundments, and inadequately sized culverts or bridge openings, resulting in altered ecological structure and function. In this study we evaluated the response of vegetation and nekton (fishes and decapod crustaceans) to restoration of full tidal flow to a portion of the Sachuest Point salt marsh, Middletown, Rhode Island. A before, after, control, impact study design was used, including evaluations of the tide-restricted marsh, the same marsh after reintroduction of tidal flow (i.e., tide-restored marsh), and an unrestricted control marsh. Before tidal restoration vegetation of the 3.7-ha tide-restricted marsh was dominated by Phragmites australis and was significantly different from the adjacent 6.3-ha Spartina -dominated unrestricted control marsh (analysis of similarities randomization test, p < 0.001). After one growing season vegetation of the tide-restored marsh had changed from its pre-restoration condition (analysis of similarities randomization test, p < 0.005). Although not similar to the unrestricted control marsh, Spartina patens and S. alterniflora abundance increased and abundance and height of Phragmites significantly declined, suggesting a convergence toward typical New England salt marsh vegetation. Before restoration shallow water habitat (creeks and pools) of the unrestricted control marsh supported a greater density of nekton compared with the tide-restricted marsh (analysis of variance, p < 0.001), but after one season of restored tidal flow nekton density was equivalent. A similar trend was documented for nekton species richness. Nekton density and species richness from marsh surface samples were similar between the tide-restored marsh and unrestricted control marsh. Fundulus heteroclitus and Palaemonetes pugio were the numerically dominant fish and decapod species in all sampled habitats. This study provides an example of a

  11. Relationships Between Watershed Emergy Flow and Coastal New England Salt Marsh Structure, Function, and Condition

    EPA Science Inventory

    This study evaluated the link between watershed activities and salt marsh structure, function, and condition using spatial emergy flow density (areal empower density) in the watershed and field data from 10 tidal salt marshes in Narragansett Bay, RI. The field-collected data wer...

  12. 20 Years of sea-levels, accretion, and vegetation on two Long Island Sound salt marshes

    EPA Science Inventory

    The long-term 1939-2013 rate of RSLR (Relative Sea-Level Rise) at the New London, CT tide gauge is ~2.6 mm/yr, near the maximum rate of salt marsh accretion reported in eastern Long Island Sound salt marshes. Consistent with recent literature RSLR at New London has accelerated si...

  13. Vulnerability of Rhode Island Salt Marshes to Sea Level Rise and Poor Water Quality

    EPA Science Inventory

    Across the northeastern Unites States, salt marshes are losing ground. Edges are eroding, tidal channel networks are expanding, and new ponds are forming and expanding within salt marshes. This leaves shorelines - and in some cases houses - more vulnerable to nor'easters and tr...

  14. DENITRIFICATION ENZYME ACTIVITY OF FRINGE SALT MARSHES IN NEW ENGLAND (USA)

    EPA Science Inventory

    Coastal salt marshes are a buffer between the uplands and adjacent coastal waters in New England (USA). With increasing N loads from developed watersheds, salt marshes could play an important role in the water quality maintenance of coastal waters. In this study we examined seaso...

  15. IMPACTS OF NITROGEN LOADING ON SALT MARSH INTEGRITY IN NEW ENGLAND, USA

    EPA Science Inventory

    Salt marsh habitat integrity is linked with the ability to provide good water quality and high biodiversity. We measured high denitrification enzyme activity (DEA) in ten coastal salt marshes in Narragansett Bay, Rhode Island (seasonal means ranging from 7,476 - 53,494 kg N-1ha-...

  16. COASTAL SALT MARSH COMMUNITY CHANGE IN NARRAGANSETT BAY IN RESPONSE TO CULTURAL EUTROPHICATION

    EPA Science Inventory

    Coastal salt marshes are susceptible to cultural eutrophication, particularly the over-enrichment of nitrogen, because they are often located where surface water and groundwater discharge into estuaries. In this report, the current areal extent of coastal salt marshes in Narrag...

  17. Assessing Wildlife Habitat Value of New England Salt Marshes: II. Model Testing and Validation

    EPA Science Inventory

    We test a previously described model to assess the wildlife habitat value of New England salt marshes by comparing modeled habitat values and scores with bird abundance and species richness at sixteen salt marshes in Narragansett Bay, Rhode Island USA. Assessment scores ranged f...

  18. New England salt marsh pools: A quantitative analysis of geomorphic and geographic features

    USGS Publications Warehouse

    Adamowicz, S.C.; Roman, C.T.

    2005-01-01

    New England salt marsh pools provide important wildlife habitat and are the object of on-going salt marsh restoration projects; however, they have not been quantified in terms of their basic geomorphic and geographic traits. An examination of 32 ditched and unditched salt marshes from the Connecticut shore of Long Island Sound to southern Maine, USA, revealed that pools from ditched and unditched marshes had similar average sizes of about 200 m2, averaged 29 cm in depth, and were located about 11 m from the nearest tidal flow. Unditched marshes had 3 times the density (13 pools/ha), 2.5 times the pool coverage (83 m pool/km transect), and 4 times the total pool surface area per hectare (913 m2 pool/ha salt marsh) of ditched sites. Linear regression analysis demonstrated that an increasing density of ditches (m ditch/ha salt marsh) was negatively correlated with pool density and total pool surface area per hectare. Creek density was positively correlated with these variables. Thus, it was not the mere presence of drainage channels that were associated with low numbers of pools, but their type (ditch versus creek) and abundance. Tidal range was not correlated with pool density or total pool surface area, while marsh latitude had only a weak relationship to total pool surface area per hectare. Pools should be incorporated into salt marsh restoration planning, and the parameters quantified here may be used as initial design targets.

  19. Ionic alkylleads in salt marsh periwinkles (Littorina irrorata)

    SciTech Connect

    Krishnan, K.; Marshall, W.D.; Hatch, W.I.

    1988-07-01

    Salt marsh periwinkles (Littorina irrorata), from six sites in Maryland and Virginia, were examined to determine ionic alkyllead concentrations and possible alkyllead sources in lower Chesapeake Bay. Different sources of ethylleads and trimethyllead to this species were demonstrated by statistical comparisons of the concentrations of individual analytes from different sites. These comparisons also indicated (1) that environmentally mediated methylation of Pb/sup 2 +/ contributes appreciably to Me/sub 3/Pb/sup +/ concentrations in snails and (2) that the relative concentrations of individual analytes were consistent with an environmental methylation of ethyllead salts. Compared to females, males were characterized by significantly higher concentrations of several of the alkyllead analytes. In addition, an unknown lead-containing compound was present in all samples.

  20. Geochemical evidence for cryptic sulfur cycling in salt marsh sediments

    NASA Astrophysics Data System (ADS)

    Mills, Jennifer V.; Antler, Gilad; Turchyn, Alexandra V.

    2016-11-01

    Cryptic sulfur cycling is an enigmatic process in which sulfate is reduced to some lower-valence state sulfur species and subsequently quantitatively reoxidized; the rate and microbial energetics of this process and how prevalent it may be in the environment remain controversial. Here we investigate sulfur cycling in salt marsh sediments from Norfolk, England where we observe high ferrous iron concentrations with no depletion of sulfate or change in the sulfur isotope ratio of that sulfate, but a 5‰ increase in the oxygen isotope ratio in sulfate, indicating that sulfate has been through a reductive cycle replacing its oxygen atoms. This cryptic sulfur cycle was replicated in laboratory incubations using 18O-enriched water, demonstrating that the field results do not solely result from mixing processes in the natural environment. Numerical modeling of the laboratory incubations scaled to represent the salt marsh sediments suggests that the uptake rate of sulfate during this cryptic sulfur cycling is similar to the uptake rate of sulfate during the fastest microbial sulfate reduction that has been measured in the natural environment. The difference is that during cryptic sulfur cycling, all of the sulfur is subsequently reoxidized to sulfate. We discuss mechanisms for this pathway of sulfur cycling including the possible link to the subsurface iron cycle.

  1. Biogeochemical drivers of phosphatase activity in salt marsh sediments

    NASA Astrophysics Data System (ADS)

    Freitas, Joana; Duarte, Bernardo; Caçador, Isabel

    2014-10-01

    Although nitrogen has become a major concern for wetlands scientists dealing with eutrophication problems, phosphorous represents another key element, and consequently its biogeochemical cycling has a crucial role in eutrophication processes. Microbial communities are a central component in trophic dynamics and biogeochemical processes on coastal systems, since most of the processes in sediments are microbial-mediated due to enzymatic action, including the mineralization of organic phosphorus carried out by acid phosphatase activity. In the present work, the authors investigate the biogeochemical sediment drivers that control phosphatase activities. Authors also aim to assess biogeochemical factors' influence on the enzyme-mediated phosphorous cycling processes in salt marshes. Plant rhizosediments and bare sediments were collected and biogeochemical features, including phosphatase activities, inorganic and organic phosphorus contents, humic acids content and pH, were assessed. Acid phosphatase was found to give the highest contribution for total phosphatase activity among the three pH-isoforms present in salt marsh sediments, favored by acid pH in colonized sediments. Humic acids also appear to have an important role inhibiting phosphatase activity. A clear relation of phosphatase activity and inorganic phosphorous was also found. The data presented reinforces the role of phosphatase in phosphorous cycling.

  2. Estimates of future inundation of salt marshes in response to sea-level rise in and around Acadia National Park, Maine

    USGS Publications Warehouse

    Nielsen, Martha G.; Dudley, Robert W.

    2013-01-01

    Salt marshes are ecosystems that provide many important ecological functions in the Gulf of Maine. The U.S. Geological Survey investigated salt marshes in and around Acadia National Park from Penobscot Bay to the Schoodic Peninsula to map the potential for landward migration of marshes using a static inundation model of a sea-level rise scenario of 60 centimeters (cm; 2 feet). The resulting inundation contours can be used by resource managers to proactively adapt to sea-level rise by identifying and targeting low-lying coastal areas adjacent to salt marshes for conservation or further investigation, and to identify risks to infrastructure in the coastal zone. For this study, the mapping of static inundation was based on digital elevation models derived from light detection and ranging (LiDAR) topographic data collected in October 2010. Land-surveyed control points were used to evaluate the accuracy of the LiDAR data in the study area, yielding a root mean square error of 11.3 cm. An independent accuracy assessment of the LiDAR data specific to salt-marsh land surfaces indicated a root mean square error of 13.3 cm and 95-percent confidence interval of ± 26.0 cm. LiDAR-derived digital elevation models and digital color aerial photography, taken during low tide conditions in 2008, with a pixel resolution of 0.5 meters, were used to identify the highest elevation of the land surface at each salt marsh in the study area. Inundation contours for 60-cm of sea-level rise were delineated above the highest marsh elevation for each marsh. Confidence interval contours (95-percent,± 26.0 cm) were delineated above and below the 60-cm inundation contours, and artificial structures, such as roads and bridges, that may present barriers to salt-marsh migration were mapped. This study delineated 114 salt marshes totaling 340 hectares (ha), ranging in size from 0.11 ha (marshes less than 0.2 ha were mapped only if they were on Acadia National Park property) to 52 ha, with a median

  3. Heavily Oiled Salt Marsh following the Deepwater Horizon Oil Spill, Ecological Comparisons of Shoreline Cleanup Treatments and Recovery.

    PubMed

    Zengel, Scott; Bernik, Brittany M; Rutherford, Nicolle; Nixon, Zachary; Michel, Jacqueline

    2015-01-01

    The Deepwater Horizon oil spill affected hundreds of kilometers of coastal wetland shorelines, including salt marshes with persistent heavy oiling that required intensive shoreline "cleanup" treatment. Oiled marsh treatment involves a delicate balance among: removing oil, speeding the degradation of remaining oil, protecting wildlife, fostering habitat recovery, and not causing further ecological damage with treatment. To examine the effectiveness and ecological effects of treatment during the emergency response, oiling characteristics and ecological parameters were compared over two years among heavily oiled test plots subject to: manual treatment, mechanical treatment, natural recovery (no treatment, oiled control), as well as adjacent reference conditions. An additional experiment compared areas with and without vegetation planting following treatment. Negative effects of persistent heavy oiling on marsh vegetation, intertidal invertebrates, and shoreline erosion were observed. In areas without treatment, oiling conditions and negative effects for most marsh parameters did not considerably improve over two years. Both manual and mechanical treatment were effective at improving oiling conditions and vegetation characteristics, beginning the recovery process, though recovery was not complete by two years. Mechanical treatment had additional negative effects of mixing oil into the marsh soils and further accelerating erosion. Manual treatment appeared to strike the right balance between improving oiling and habitat conditions while not causing additional detrimental effects. However, even with these improvements, marsh periwinkle snails showed minimal signs of recovery through two years, suggesting that some ecosystem components may lag vegetation recovery. Planting following treatment quickened vegetation recovery and reduced shoreline erosion. Faced with comparable marsh oiling in the future, we would recommend manual treatment followed by planting. We caution

  4. Heavily Oiled Salt Marsh following the Deepwater Horizon Oil Spill, Ecological Comparisons of Shoreline Cleanup Treatments and Recovery.

    PubMed

    Zengel, Scott; Bernik, Brittany M; Rutherford, Nicolle; Nixon, Zachary; Michel, Jacqueline

    2015-01-01

    The Deepwater Horizon oil spill affected hundreds of kilometers of coastal wetland shorelines, including salt marshes with persistent heavy oiling that required intensive shoreline "cleanup" treatment. Oiled marsh treatment involves a delicate balance among: removing oil, speeding the degradation of remaining oil, protecting wildlife, fostering habitat recovery, and not causing further ecological damage with treatment. To examine the effectiveness and ecological effects of treatment during the emergency response, oiling characteristics and ecological parameters were compared over two years among heavily oiled test plots subject to: manual treatment, mechanical treatment, natural recovery (no treatment, oiled control), as well as adjacent reference conditions. An additional experiment compared areas with and without vegetation planting following treatment. Negative effects of persistent heavy oiling on marsh vegetation, intertidal invertebrates, and shoreline erosion were observed. In areas without treatment, oiling conditions and negative effects for most marsh parameters did not considerably improve over two years. Both manual and mechanical treatment were effective at improving oiling conditions and vegetation characteristics, beginning the recovery process, though recovery was not complete by two years. Mechanical treatment had additional negative effects of mixing oil into the marsh soils and further accelerating erosion. Manual treatment appeared to strike the right balance between improving oiling and habitat conditions while not causing additional detrimental effects. However, even with these improvements, marsh periwinkle snails showed minimal signs of recovery through two years, suggesting that some ecosystem components may lag vegetation recovery. Planting following treatment quickened vegetation recovery and reduced shoreline erosion. Faced with comparable marsh oiling in the future, we would recommend manual treatment followed by planting. We caution

  5. Heavily Oiled Salt Marsh following the Deepwater Horizon Oil Spill, Ecological Comparisons of Shoreline Cleanup Treatments and Recovery

    PubMed Central

    Zengel, Scott; Bernik, Brittany M.; Rutherford, Nicolle; Nixon, Zachary; Michel, Jacqueline

    2015-01-01

    The Deepwater Horizon oil spill affected hundreds of kilometers of coastal wetland shorelines, including salt marshes with persistent heavy oiling that required intensive shoreline “cleanup” treatment. Oiled marsh treatment involves a delicate balance among: removing oil, speeding the degradation of remaining oil, protecting wildlife, fostering habitat recovery, and not causing further ecological damage with treatment. To examine the effectiveness and ecological effects of treatment during the emergency response, oiling characteristics and ecological parameters were compared over two years among heavily oiled test plots subject to: manual treatment, mechanical treatment, natural recovery (no treatment, oiled control), as well as adjacent reference conditions. An additional experiment compared areas with and without vegetation planting following treatment. Negative effects of persistent heavy oiling on marsh vegetation, intertidal invertebrates, and shoreline erosion were observed. In areas without treatment, oiling conditions and negative effects for most marsh parameters did not considerably improve over two years. Both manual and mechanical treatment were effective at improving oiling conditions and vegetation characteristics, beginning the recovery process, though recovery was not complete by two years. Mechanical treatment had additional negative effects of mixing oil into the marsh soils and further accelerating erosion. Manual treatment appeared to strike the right balance between improving oiling and habitat conditions while not causing additional detrimental effects. However, even with these improvements, marsh periwinkle snails showed minimal signs of recovery through two years, suggesting that some ecosystem components may lag vegetation recovery. Planting following treatment quickened vegetation recovery and reduced shoreline erosion. Faced with comparable marsh oiling in the future, we would recommend manual treatment followed by planting. We

  6. Comparison of wetland structural characteristics between created and natural salt marshes in southwest Louisiana, USA

    USGS Publications Warehouse

    Edwards, K.R.; Proffitt, C.E.

    2003-01-01

    The use of dredge material is a well-known technique for creating or restoring salt marshes that is expected to become more common along the Gulf of Mexico coast in the future. However, the effectiveness of this restoration method is still questioned. Wetland structural characteristics were compared between four created and three natural salt marshes in southwest Louisiana, USA. The created marshes, formed by the pumping of dredge material into formerly open water areas, represent a chronosequence, ranging in age from 3 to 19 years. Vegetation and soil structural factors were compared to determine whether the created marshes become more similar over time to the natural salt marshes. Vegetation surveys were conducted in 1997, 2000, and 2002 using the line-intercept technique. Site elevations were measured in 2000. Organic matter (OM) was measured in 1996 and 2002, while bulk density and soil particle-size distribution were determined in 2002 only. The natural marshes were dominated by Spartina alterniflora, as were the oldest created marshes; these marshes had the lowest mean site elevations ( 35 cm NGVD) and became dominated by high marsh (S. patens, Distichlis spicata) and shrub (Baccharis halimifolia, Iva frutescens) species. The higher elevation marsh seems to be following a different plant successional trajectory than the other marshes, indicating a relationship between marsh elevation and species composition. The soils in both the created and natural marshes contain high levels of clays (30-65 %), with sand comprising < 1 % of the soil distribution. OM was significantly greater and bulk density significantly lower in two of the natural marshes when compared to the created marshes. The oldest created marsh had significantly greater OM than the younger created marshes, but it may still take several decades before equivalency is reached with the natural marshes. Vegetation structural characteristics in the created marshes take only a few years to become similar

  7. A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes.

    PubMed

    Leonardi, Nicoletta; Ganju, Neil K; Fagherazzi, Sergio

    2016-01-01

    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. PMID:26699461

  8. A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes

    PubMed Central

    Leonardi, Nicoletta; Ganju, Neil K.; Fagherazzi, Sergio

    2016-01-01

    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. PMID:26699461

  9. A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes.

    PubMed

    Leonardi, Nicoletta; Ganju, Neil K; Fagherazzi, Sergio

    2016-01-01

    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.

  10. A linear relationship between wave power and erosion determines salt-marsh resilience to violent storms and hurricanes

    USGS Publications Warehouse

    Leonardi, Nicoletta; Ganju, Neil K.; Fagherazzi, Sergio

    2016-01-01

    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.

  11. Seasonal habitat-use patterns of nekton in a tide-restricted and unrestricted New England salt marsh

    USGS Publications Warehouse

    Raposa, K.B.; Roman, C.T.

    2001-01-01

    Many New England salt marshes remain tide-restricted or are undergoing tidal restoration. Hydrologic manipulation of salt marshes affects marsh biogeochemistry and vegetation patterns, but responses by fishes and decapod crustaceans (nekton) remain unclear, This study examines nekton habitat-use patterns in the tide-restricted Hatches Harbor salt marsh (Provincetown, Massachusetts) relative to a downstream, unrestricted marsh. Nekton assemblages were sampled in tidal creek, marsh pool, and salt marsh surface habitats. Pools and creeks were sampled every two weeks for one year to account for seasonal variability, and the marsh surface was sampled at two-week intervals in summer and fall. Density, richness, and community composition of nekton in creek and marsh surface habitats were similar between the unrestricted and restricted marsh, but use of pools differed drastically on the two sides of the tide-restricting dike. In 95% of the cases tested, restricted marsh habitats provided equal or greater habitat value for nekton than the same habitat in the unrestricted marsh (based on density), suggesting that the restricted marsh did not provide a degraded habitat for most species. For some species, the restricted marsh provided nursery, breeding, and overwintering habitat during different seasons, and tidal restoration of this salt marsh must be approached with care to prevent losses of these valuable marsh functions.

  12. Exploiting wild population diversity and somaclonal variation in the salt marsh grass Distichlis spicata (Poaceae) for marsh creation and restoration.

    PubMed

    Seliskar, D M; Gallagher, J L

    2000-01-01

    The salt marsh grass Distichlis spicata was regenerated from tissue culture and propagated in a greenhouse. Selected regenerants, along with selections from six wild populations, were grown for two years in a common garden flood-irrigated thrice weekly with tidal creek water. Selected wild and regenerated plants were also planted in a created salt marsh. Significant differences among regenerant and wild population selections were found in several functionally important salt marsh plant characteristics, including potential detritus production, belowground organic matter production, canopy structure, and decomposition rate. A combination of characteristics not found in the wild populations was evident in a regenerated line that exhibited both a high detritus production potential and a high decomposition rate. The amount of variation that occurred among regenerants from one parental line via somaclonal variation was similar to that which occurred among the wild population selections. Results of this study suggest that tissue culture may provide a means of producing marsh grasses with specific characteristics for directing the functional development of newly created salt marshes.

  13. Sulfur isotope ratios as evidence of dissolved sulfur uptake by salt marsh cordgrass. [Spartina alterniflora

    SciTech Connect

    Carlson, P.R. Jr.; Forrest, J.

    1985-06-01

    The difference in stable sulfur isotope ratios of sulfate and sulfide in marsh porewater was used to verify the uptake of hydrogen sulfide by the salt marsh cordgrass, Spartina alterniflora, in North Carlina salt marsh. Most of the plant sulfur derived from porewater sulfide was recovered as sulfate indicating that the sulfide had been oxidized within the plant. The analysis of sulfur isotope ratios of other marsh halophytes is suggested as a technique to determine whether sulfide is taken up by plants. 15 refs., 2 figs., 1 tab.

  14. Salt Marsh Sediment Mixing Following Petroleum Hydrocarbon Exposure from the Deepwater Horizon Oil Spill

    NASA Astrophysics Data System (ADS)

    Hatch, R. S.; Yeager, K. M.; Brunner, C. A.; Wade, T. L.; Briggs, K. B.; Schindler, K. J.

    2013-12-01

    Tidal marshes support valuable ecosystems, but their coastal locations make them susceptible to oil spills. Oil spilled in the ocean is easily transported via tidal and wind-driven currents to the shore and incorporated into sediments. The primary goal of this research was to determine how deeply oil from the 2010 Deepwater Horizon spill has penetrated sediments along the Gulf Coast, and whether oil has quantifiably affected benthic ecosystems at these sites. Sediment cores were taken from three marsh environments at sites classified as unoiled, lightly oiled, and heavily oiled based on data from NOAA's Environmental Response Management Application (ERMA). These classifications have been verified by measurements of total polycyclic aromatic hydrocarbons ([TPAH] without perylene). Bioturbators, such as polychaetes and oligochaetes, constantly rework sediments as they burrow into them. In this way, bioturbators can play a role in the fate of organic contaminants, either by allowing for natural remediation of contaminants via enhanced microbial degradation, or by mixing oil from the surface deeper into the sediment column. The constant fallout radionuclide 7Be was measured to determine short-term sediment mixing depths. However, there was a conspicuous absence of 7Be at most sites. This could be due to sediment composition constraints on 7Be sorption (coarse-grained sediment, high organic matter contents), or rapid erosion of the marsh surface. Instead, minimum mixing depths were derived from 234Thxs profiles. Thorium-234 is a lithogenic isotope that has widely been used to trace particle mixing on short time scales near that of its mean life (36 days). Penetration depths of 234Thxs ranged between 0.25 and 4.5 cm. Sediment accumulation rates will be determined using 210Pb, with verification from an independent tracer, 137Cs, in selected cores. Preliminary results from 210Pb profiles reveal thorough, long-term (decadal) sediment mixing to at least 40 cm at all sites

  15. Rapid shoreward encroachment of salt marsh cordgrass in response to accelerated sea-level rise

    PubMed Central

    Donnelly, Jeffrey P.; Bertness, Mark D.

    2001-01-01

    The distribution of New England salt marsh communities is intrinsically linked to the magnitude, frequency, and duration of tidal inundation. Cordgrass (Spartina alterniflora) exclusively inhabits the frequently flooded lower elevations, whereas a mosaic of marsh hay (Spartina patens), spike grass (Distichlis spicata), and black rush (Juncus gerardi) typically dominate higher elevations. Monitoring plant zonal boundaries in two New England salt marshes revealed that low-marsh cordgrass rapidly moved landward at the expense of higher-marsh species between 1995 and 1998. Plant macrofossils from sediment cores across modern plant community boundaries provided a 2,500-year record of marsh community composition and documented the migration of cordgrass into the high marsh. Isotopic dating revealed that the initiation of cordgrass migration occurred in the late 19th century and continued through the 20th century. The timing of the initiation of cordgrass migration is coincident with an acceleration in the rate of sea-level rise recorded by the New York tide gauge. These results suggest that increased flooding associated with accelerating rates of sea-level rise has stressed high-marsh communities and promoted landward migration of cordgrass. If current rates of sea-level rise continue or increase slightly over the next century, New England salt marshes will be dominated by cordgrass. If climate warming causes sea-level rise rates to increase significantly over the next century, these cordgrass-dominated marshes will likely drown, resulting in extensive losses of coastal wetlands. PMID:11724926

  16. Rapid shoreward encroachment of salt marsh cordgrass in response to accelerated sea-level rise.

    PubMed

    Donnelly, J P; Bertness, M D

    2001-12-01

    The distribution of New England salt marsh communities is intrinsically linked to the magnitude, frequency, and duration of tidal inundation. Cordgrass (Spartina alterniflora) exclusively inhabits the frequently flooded lower elevations, whereas a mosaic of marsh hay (Spartina patens), spike grass (Distichlis spicata), and black rush (Juncus gerardi) typically dominate higher elevations. Monitoring plant zonal boundaries in two New England salt marshes revealed that low-marsh cordgrass rapidly moved landward at the expense of higher-marsh species between 1995 and 1998. Plant macrofossils from sediment cores across modern plant community boundaries provided a 2,500-year record of marsh community composition and documented the migration of cordgrass into the high marsh. Isotopic dating revealed that the initiation of cordgrass migration occurred in the late 19th century and continued through the 20th century. The timing of the initiation of cordgrass migration is coincident with an acceleration in the rate of sea-level rise recorded by the New York tide gauge. These results suggest that increased flooding associated with accelerating rates of sea-level rise has stressed high-marsh communities and promoted landward migration of cordgrass. If current rates of sea-level rise continue or increase slightly over the next century, New England salt marshes will be dominated by cordgrass. If climate warming causes sea-level rise rates to increase significantly over the next century, these cordgrass-dominated marshes will likely drown, resulting in extensive losses of coastal wetlands.

  17. Phylogenetic and physiological diversity of sulphate-reducing bacteria isolated from a salt marsh sediment.

    PubMed

    Rooney-Varga, J N; Genthner, B R; Devereux, R; Willis, S G; Friedman, S D; Hines, M E

    1998-12-01

    The phylogenetic and physiological diversity of sulphate-reducing bacteria inhabiting a salt marsh rhizosphere were investigated. Sulphate-reducing bacteria were isolated from a salt marsh rhizosphere using enrichment cultures with electron donors thought to be prevalent in the rhizosphere of Spartina alterniflora. The relationship between phylogeny and nutritional characteristics of 10 strains was investigated. None of the isolates had 16S rRNA sequences identical to other delta subclass sulphate-reducers, sharing 85.3 to 98.1% sequence similarity with 16S rRNA sequences of their respective closest relatives. Phylogenetic analysis placed two isolates, obtained with ethanol as an electron donor, within the Desulfovibrionaceae. Seven isolates, obtained with acetate, butyrate, propionate, or benzoate, were placed within the Desulfobacteriaceae. One isolate, obtained with butyrate, fell within the Desulfobulbus assemblage, which is currently considered part of the Desulfobacteriaceae family. However, due to the phylogenetic breadth and physiological traits of this group, we propose that it be considered a new family, the "Desulfobulbusaceae." The isolates utilised an array of electron donors similar to their closest relatives with a few exceptions. As a whole, the phylogenetic and physiological data indicate isolation of several sulphate-reducing bacteria which might be considered as new species and representative of new genera. Comparison of the Desulfobacteriaceae isolates' 16S rRNA sequences to environmental clones originating from the same study site revealed that none shared more than 86% sequence similarity. The results provide further insight into the diversity of sulphate-reducing bacteria inhabiting the salt marsh ecosystem, as well as supporting general trends in the phylogenetic coherence of physiological traits of delta Proteobacteria sulphate reducers.

  18. Consumer trait variation influences tritrophic interactions in salt marsh communities

    PubMed Central

    Hughes, Anne Randall; Hanley, Torrance C; Orozco, Nohelia P; Zerebecki, Robyn A

    2015-01-01

    The importance of intraspecific variation has emerged as a key question in community ecology, helping to bridge the gap between ecology and evolution. Although much of this work has focused on plant species, recent syntheses have highlighted the prevalence and potential importance of morphological, behavioral, and life history variation within animals for ecological and evolutionary processes. Many small-bodied consumers live on the plant that they consume, often resulting in host plant-associated trait variation within and across consumer species. Given the central position of consumer species within tritrophic food webs, such consumer trait variation may play a particularly important role in mediating trophic dynamics, including trophic cascades. In this study, we used a series of field surveys and laboratory experiments to document intraspecific trait variation in a key consumer species, the marsh periwinkle Littoraria irrorata, based on its host plant species (Spartina alterniflora or Juncus roemerianus) in a mixed species assemblage. We then conducted a 12-week mesocosm experiment to examine the effects of Littoraria trait variation on plant community structure and dynamics in a tritrophic salt marsh food web. Littoraria from different host plant species varied across a suite of morphological and behavioral traits. These consumer trait differences interacted with plant community composition and predator presence to affect overall plant stem height, as well as differentially alter the density and biomass of the two key plant species in this system. Whether due to genetic differences or phenotypic plasticity, trait differences between consumer types had significant ecological consequences for the tritrophic marsh food web over seasonal time scales. By altering the cascading effects of the top predator on plant community structure and dynamics, consumer differences may generate a feedback over longer time scales, which in turn influences the degree of trait

  19. Consumer trait variation influences tritrophic interactions in salt marsh communities.

    PubMed

    Hughes, Anne Randall; Hanley, Torrance C; Orozco, Nohelia P; Zerebecki, Robyn A

    2015-07-01

    The importance of intraspecific variation has emerged as a key question in community ecology, helping to bridge the gap between ecology and evolution. Although much of this work has focused on plant species, recent syntheses have highlighted the prevalence and potential importance of morphological, behavioral, and life history variation within animals for ecological and evolutionary processes. Many small-bodied consumers live on the plant that they consume, often resulting in host plant-associated trait variation within and across consumer species. Given the central position of consumer species within tritrophic food webs, such consumer trait variation may play a particularly important role in mediating trophic dynamics, including trophic cascades. In this study, we used a series of field surveys and laboratory experiments to document intraspecific trait variation in a key consumer species, the marsh periwinkle Littoraria irrorata, based on its host plant species (Spartina alterniflora or Juncus roemerianus) in a mixed species assemblage. We then conducted a 12-week mesocosm experiment to examine the effects of Littoraria trait variation on plant community structure and dynamics in a tritrophic salt marsh food web. Littoraria from different host plant species varied across a suite of morphological and behavioral traits. These consumer trait differences interacted with plant community composition and predator presence to affect overall plant stem height, as well as differentially alter the density and biomass of the two key plant species in this system. Whether due to genetic differences or phenotypic plasticity, trait differences between consumer types had significant ecological consequences for the tritrophic marsh food web over seasonal time scales. By altering the cascading effects of the top predator on plant community structure and dynamics, consumer differences may generate a feedback over longer time scales, which in turn influences the degree of trait

  20. Geochemical Evidence of Cryptic Sulfur Cycling in Salt Marsh Sediments

    NASA Astrophysics Data System (ADS)

    Mills, J. V.; Antler, G.; Turchyn, A. V.

    2014-12-01

    In modern marine and marginal marine sediments, bacterial sulfate reduction dominates the subsurface oxidation of organic carbon due to the abundance of sulfate in many surface environments. While bacterial sulfate reduction may control anaerobic organic carbon oxidation, there is increasing evidence that iron redox chemistry may be intimately linked to sulfur redox chemistry in the anoxic subsurface, with iron species acting as catalysts or electron shuttles for the microbial use of sulfur, and vice versa. We use stable isotope and geochemical techniques to explore the coupling of the iron and sulfur cycles in salt marsh sediments in North Norfolk, UK. Unique among previously studied environments, these sediments contain high concentrations of both sulfate (20-40mM) and ferrous iron (1-3mM). High ferrous iron concentrations require extended regions of bacterial iron reduction. Within these zones of iron reduction we would predict no sulfate reduction, and lack of change in sulfur isotopes and no loss of sulfate suggest that there is no net sulfate reduction in this zone. However, coincident with the increase in ferrous iron concentrations, the δ18Osulfate exhibits significant increases of up to 5‰. The decoupling of the sulfur and oxygen isotopes of sulfate is suggestive of a cryptic sulfur cycle in which sulfate is reduced to an intermediate valence state sulfur species and subsequently reoxidized to sulfate; this cycle must by quasi-quantitative to produce the suite of geochemical observations. We further explore the nature of this cycling through a series of batch reactor incubation experiments. When sediments are incubated in 18O-enriched water, significant shifts (>15‰) in the δ18Osulfate are observed with no corresponding shift in sulfur isotopes. This provides direct evidence that microbial assemblages in these salt marsh sediments facilitate a cryptic cycling of sulfur, potentially mediated by iron species in the zone of iron reduction. We contrast

  1. Season changes of cadmium and copper levels in stem-boring larvae of Agapanthia villosoviridescens (coleoptera) on salt marshes of the Westerschelde estuary

    SciTech Connect

    Hemminga, M.A.; Nieuwenhuize, J.; Poley-Vos, C.H.; van Soelen, J. )

    1989-11-01

    Analyses of heavy metals in insects, including their developmental stages, have been widely used to monitor the penetration of these pollutants in various ecosystems. There are few reports dealing with seasonal changes in heavy metal content of insects. The seasonal pattern found in one herbivorous insect closely followed seasonal trends in metal contamination levels in the local vegetation. No data are available on season changes in insect larvae. To obtain more detailed information on seasonal changes of heavy metal levels in insects and their relation with the seasonally changing conditions in the habitat, the authors studied the time course of cadmium and copper concentrations in larvae of the longhorn beetle Agapanthia villosoviridescens. These live as stem-borers in the salt marsh halophyte Aster tripolium. The authors collected larvae from three salt marshes along the Westerschelde estuary. This estuary is severely polluted by heavy metals originating mainly from upstream sources; a large fraction of these metals is retained within the estuary. The fringing salt marsh soils, which are a sink for trace metals, show a gradient in pollution, with levels of heavy metals generally increasing in upstream direction. Salt marsh halophytes growing on these marshes show uptake of metals from the soil. Further transfers of heavy metals through the natural food chains on these salt marshes have not been investigated sofar.

  2. Acetate concentrations and oxidation in salt marsh sediments

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Acetate concentrations and rates of acetate oxidation and sulfate reduction were measured in S. alterniflora sediments in New Hampshire and Massachusetts. Pore water extracted from cores by squeezing or centrifugation contained in greater than 0.1 mM acetate and, in some instances, greater than 1.0 mM. Pore water sampled nondestructively contained much less acetate, often less than 0.01 mM. Acetate was associated with roots, and concentrations varied with changes in plant physiology. Acetate turnover was very low whether whole core or slurry incubations were used. Radiotracers injected directly into soils yielded rates of sulfate reduction and acetate oxidation not significantly different from core incubation techniques. Regardless of incubation method, acetate oxidation did not account for a substantial percentage of sulfate reduction. These results differ markedly from data for unvegetated coastal sediments where acetate levels are low, oxidation rate constants are high, and acetate oxication rates greatly exceed rates of sulfate reduction. The discrepancy between rates of acetate oxidation and sulfate reduction in these marsh soils may be due either to the utilization of substrates other than acetate by sulfate reducers or artifacts associated with measurements of organic utilization by rhizosphere bacteria. Care must be taken when interpreting data from salt marsh sediments since the release of material from roots during coring may affect the concentrations of certain compounds as well as influencing results obtained when sediment incubations are employed.

  3. Lignocellulose-responsive bacteria in a southern California salt marsh identified by stable isotope probing

    PubMed Central

    Darjany, Lindsay E.; Whitcraft, Christine R.; Dillon, Jesse G.

    2014-01-01

    Carbon cycling by microbes has been recognized as the main mechanism of organic matter decomposition and export in coastal wetlands, yet very little is known about the functional diversity of specific groups of decomposers (e.g., bacteria) in salt marsh benthic trophic structure. Indeed, salt marsh sediment bacteria remain largely in a black box in terms of their diversity and functional roles within salt marsh benthic food web pathways. We used DNA stable isotope probing (SIP) utilizing 13C-labeled lignocellulose as a proxy to evaluate the fate of macrophyte-derived carbon in benthic salt marsh bacterial communities. Overall, 146 bacterial species were detected using SIP, of which only 12 lineages were shared between enriched and non-enriched communities. Abundant groups from the 13C-labeled community included Desulfosarcina, Spirochaeta, and Kangiella. This study is the first to use heavy-labeled lignocellulose to identify bacteria responsible for macrophyte carbon utilization in salt marsh sediments and will allow future studies to target specific lineages to elucidate their role in salt marsh carbon cycling and ultimately aid our understanding of the potential of salt marshes to store carbon. PMID:24917856

  4. The ecology of New England high salt marshes: A community profile

    SciTech Connect

    Nixon, S.W. . Graduate School of Oceanography)

    1982-03-01

    The high salt marshes of New England have evolved in response to sea-level rises through accretion of sediments entrapped by marsh vegetation. Early theories of marsh development are traced and are reconciled in Redfield's synthesis accounting for marsh growth by aggradation over sand and mud flats as well as by accretion on existing marsh surfaces. The shape and appearance of high marshes result from unique, complex interactions of local topography and bathymetry, sea-level rise, tides, sediment supply and vegetation. These factors, particularly the major influences of tides and short-term changes in sea-level, are incorporated in short-term processes that define and mold the ecology of the high marsh. Short- and long-term mechanisms have produced approximate zonation of vegetation in the high marsh. High marshes are contrasted to Spartina-dominated low marsh in terms of plant and animal species and the relative importance of the dynamics of production, export, decomposition, and accumulation of materials in the sediments. High marshes have been subjected to man's activities since earliest English settlement. This history of New Englanders' impact on this community is traced from their use of marshes as hay fields to depositories of pollutants. Habitat management considerations today include mosquito control and sewage sludge treatment. 154 refs., 29 figs., 14 tabs.

  5. Vulnerability of Northeastern U.S. Salt Marshes to Climatic and Anthropogenic Stressors

    NASA Astrophysics Data System (ADS)

    Watson, E. B.; Oczkowski, A. J.; Hanson, A.; Davey, E. W.; Crosby, S. C.; Johnson, R. L.

    2014-12-01

    In the Northeastern U.S., salt marsh area is in decline. Habitat change analysis has revealed fragmentation, displacement of high marsh by low marsh species, and ecological drowning, while development of adjacent uplands limits upslope migration. Using inundation experiments, field surveys, and LiDAR datasets, we developed an elevation-productivity relationship for Spartina alterniflora specific to the U.S. Northeast states of New York, Connecticut, Rhode Island, southern Massachusetts and located current salt marsh orthometric heights on this curve. We determined that 89% of salt marshes in these Northeastern states are located at elevations where growth is limited by inundation, suggesting links between current salt marsh loss patterns and sea level rise. By manipulating water column nutrients, precipitation, and elevation, we further found that altered precipitation receipt was associated with significant reductions in biomass, and that nutrient enrichment adversely impacts organic matter accumulation and peat formation. These results provide evidence that Northeastern U.S. marshes are vulnerable to the effects of accelerated sea level rise, and that neither precipitation changes, nor cultural eutrophication, will contribute positively to long-term salt marsh survival.

  6. Distribution patterns of salt marsh vegetation on Parramore Island, Virginia Coast Reserve

    SciTech Connect

    Hegnauer, E.A.; Furman, T. . Dept. of Environmental Sciences)

    1994-03-01

    The Virginia Coast Reserve is a classic example of an estuarine-barrier island complex, and is dominated physiographically by tidal salt marshes. Marsh vegetation includes Spartina alterniflora and patens, Juncus romerianus, Disticlis spicata and Salicornia virginica; these species occur in a random mosaic pattern throughout the salt marsh. Previous work has shown that porewater salinity and flooding frequency control plant distributions at a gross scale (daily tidal inundation versus occasional flooding), but variations in these parameters are extremely subtle in the Parramore marshes. The goal of this research is to document and monitor small-scale physical factors that control spatial distribution of marsh species. The results of this study have serious implications for development of artificial wetlands. Topographic variations on the order of < 10 cm are significant in determining both flooding history and water table salinity, and therefore affect the colonization and growth of marsh plant species dramatically.

  7. Building a Probabilistic Denitrification Model for an Oregon Salt Marsh

    NASA Astrophysics Data System (ADS)

    Moon, J. B.; Stecher, H. A.; DeWitt, T.; Nahlik, A.; Regutti, R.; Michael, L.; Fennessy, M. S.; Brown, L.; Mckane, R.; Naithani, K. J.

    2015-12-01

    Despite abundant work starting in the 1950s on the drivers of denitrification (DeN), mechanistic complexity and methodological challenges of direct DeN measurements have resulted in a lack of reliable rate estimates across landscapes, and a lack of operationally valid, robust models. Measuring and modeling DeN are particularly challenging in tidal systems, which play a vital role in buffering adjacent coastal waters from nitrogen inputs. These systems are hydrologically and biogeochemically complex, varying on fine temporal and spatial scales. We assessed the spatial and temporal variability of soil nitrate (NO3-) levels and O2 availability, two primary drivers of DeN, in surface soils of Winant salt marsh located in Yaquina estuary, OR during the summers of 2013 and 2014. We found low temporal variability in soil NO3- concentrations across years, tide series, and tide cycles, but high spatial variability linked to elevation gradients (i.e., habitat types); spatial variability within the high marsh habitat (0 - 68 μg N g-1 dry soil) was correlated with distance to major tide creek channels and connectivity to upslope N-fixing red alder. Soil O2 measurements collected at 5 cm below ground across three locations on two spring tide series showed that O2 drawdown rates were also spatially variable. Depending on the marsh location, O2 draw down ranged from sub-optimal for DeN (> 80 % O2 saturation) across an entire tide series (i.e., across days) to optimum (i.e., ~ 0 % O2 saturation) within one overtopping tide event (i.e., within hours). We are using these results, along with empirical relationships created between DeN and soil NO3- concentrations for Winant to improve on a pre-existing tidal DeN model. We will develop the first version of a fully probabilistic hierarchical Bayesian tidal DeN model to quantify parameter and prediction uncertainties, which are as important as determining mean predictions in order to distinguish measurable differences across the marsh.

  8. Silica uptake by Spartina—evidence of multiple modes of accumulation from salt marshes around the world

    PubMed Central

    Carey, Joanna C.; Fulweiler, Robinson W.

    2014-01-01

    Silicon (Si) plays a critical role in plant functional ecology, protecting plants from multiple environmental stressors. While all terrestrial plants contain some Si, wetland grasses are frequently found to have the highest concentrations, although the mechanisms driving Si accumulation in wetland grasses remain in large part uncertain. For example, active Si accumulation is often assumed to be responsible for elevated Si concentrations found in wetland grasses. However, life stage and differences in Si availability in the surrounding environment also appear to be important variables controlling the Si concentrations of wetland grasses. Here we used original data from five North American salt marshes, as well as all known published literature values, to examine the primary drivers of Si accumulation in Spartina, a genus of prolific salt marsh grasses found worldwide. We found evidence of multiple modes of Si accumulation in Spartina, with passive accumulation observed in non-degraded marshes where Spartina was native, while rejective accumulation was found in regions where Spartina was invasive. Evidence of active accumulation was found in only one marsh where Spartina was native, but was also subjected to nutrient over-enrichment. We developed a conceptual model which hypothesizes that the mode of Si uptake by Spartina is dependent on local environmental factors and genetic origin, supporting the idea that plant species should be placed along a spectrum of Si accumulation. We hypothesize that Spartina exhibits previously unrecognized phenotypic plasticity with regard to Si accumulation, allowing these plants to respond to changes in marsh condition. These results provide new insight regarding how salt marsh ecosystems regulate Si exchange at the land-sea interface. PMID:24904599

  9. Latitudinal variation in herbivore pressure in Atlantic Coast salt marshes.

    PubMed

    Pennings, Steven C; Ho, Chuan-Kai; Salgado, Cristiano S; Wieski, Kazimierz; Davé, Nilam; Kunza, Amy E; Wason, Elizabeth L

    2009-01-01

    Despite long-standing interest in latitudinal variation in ecological patterns and processes, there is to date weak and conflicting evidence that herbivore pressure varies with latitude. We used three approaches to examine latitudinal variation in herbivore pressure in Atlantic Coast salt marshes, focusing on five abundant plant taxa: the grass Spartina alterniflora, the congeneric rushes Juncus gerardii and J. roemerianus, the forb Solidago sempervirens, and the shrubs Iva frutescens and Baccharis halimifolia. Herbivore counts indicated that chewing and gall-making herbivores were typically > or = 10 times more abundant at low-latitude sites than at high-latitude sites, but sucking herbivores did not show a clear pattern. For two herbivore taxa (snails and tettigoniid grasshoppers), correctly interpreting latitudinal patterns required an understanding of the feeding ecology of the species, because the species common at high latitudes did not feed heavily on plant leaves whereas the related species common at low latitudes did. Damage to plants from chewing herbivores was 2-10 times greater at low-latitude sites than at high-latitude sites. Damage to transplanted "phytometer" plants was 100 times greater for plants transplanted to low- than to high-latitude sites, and two to three times greater for plants originating from high- vs. low-latitude sites. Taken together, these results provide compelling evidence that pressure from chewing and gall-making herbivores is greater at low vs. high latitudes in Atlantic Coast salt marshes. Sucking herbivores do not show this pattern and deserve greater study. Selective pressure due to greater herbivore damage at low latitudes is likely to partially explain documented patterns of low plant palatability to chewing herbivores and greater plant defenses at low latitudes, but other factors may also play a role in mediating these geographic patterns.

  10. Tagus estuary and Ria de Aveiro salt marsh dynamics and the impact of sea level rise

    NASA Astrophysics Data System (ADS)

    Valentim, J. M.; Vaz, N.; Silva, H.; Duarte, B.; Caçador, I.; Dias, J. M.

    2013-09-01

    Different characteristics of Spartina maritima found in two distinct salt marshes located in different estuaries were analysed through interpretation of their local hydrodynamic patterns, as well as the impact of sea level rise on physical processes and consequently on plant dynamics and salt marshes stability. These salt marshes are situated in two of the most important Portuguese coastal systems, Tagus estuary (Rosário salt marsh) and Ria de Aveiro lagoon (Barra salt marsh), which are dominated by physical processes that induce strong tidal currents. They were monitored during one year and plant and sediment samples of S. maritima were collected quarterly in order to determine the vegetation coverage, above and belowground biomass, organic matter and sediment moisture. Residual circulation, tidal asymmetry and tidal dissipation were determined from numerical modelling results of the MOHID 2D model that was applied to each coastal system, considering the actual sea level and a sea level rise (SLR) scenario. Results suggest that the different characteristics found for Spartina maritima in the Rosário and the Barra salt marshes may be related with the diverse hydrodynamic conditions identified for each salt marsh. Consequently, the exploration of SLR scenario predictions indicates how these salt marshes could evolve in the future, showing that the important changes in these hydrodynamic parameters under climate change context might induce significant modifications in the salt marshes dynamics and stability. SLR scenario could lead to changes in nutrients and sediments patterns around the salt marshes and thus vegetation coverage percentage would be affected. Additionally, as a consequence of flood duration increase, sediment moisture will increase causing a stress condition to plants. Hence, the ratio below/aboveground biomass might increase, becoming critical to plants survival under conditions of accelerated sea level rise. Accordingly, both SLR and expected

  11. Tidal flushing restores the physiological condition of fish residing in degraded salt marshes.

    PubMed

    Dibble, Kimberly L; Meyerson, Laura A

    2012-01-01

    Roads, bridges, and dikes constructed across salt marshes can restrict tidal flow, degrade habitat quality for nekton, and facilitate invasion by non-native plants including Phragmites australis. Introduced P. australis contributes to marsh accretion and eliminates marsh surface pools thereby adversely affecting fish by reducing access to intertidal habitats essential for feeding, reproduction, and refuge. Our study assessed the condition of resident fish populations (Fundulus heteroclitus) at four tidally restricted and four tidally restored marshes in New England invaded by P. australis relative to adjacent reference salt marshes. We used physiological and morphological indicators of fish condition, including proximate body composition (% lipid, % lean dry, % water), recent daily growth rate, age class distributions, parasite prevalence, female gravidity status, length-weight regressions, and a common morphological indicator (Fulton's K) to assess impacts to fish health. We detected a significant increase in the quantity of parasites infecting fish in tidally restricted marshes but not in those where tidal flow was restored to reduce P. australis cover. Using fish length as a covariate, we found that unparasitized, non-gravid F. heteroclitus in tidally restricted marshes had significantly reduced lipid reserves and increased lean dry (structural) mass relative to fish residing in reference marshes. Fish in tidally restored marshes were equivalent across all metrics relative to those in reference marshes indicating that habitat quality was restored via increased tidal flushing. Reference marshes adjacent to tidally restored sites contained the highest abundance of young fish (ages 0-1) while tidally restricted marshes contained the lowest. Results indicate that F. heteroclitus residing in physically and hydrologically altered marshes are at a disadvantage relative to fish in reference marshes but the effects can be reversed through ecological restoration.

  12. Tidal Flushing Restores the Physiological Condition of Fish Residing in Degraded Salt Marshes

    PubMed Central

    Dibble, Kimberly L.; Meyerson, Laura A.

    2012-01-01

    Roads, bridges, and dikes constructed across salt marshes can restrict tidal flow, degrade habitat quality for nekton, and facilitate invasion by non-native plants including Phragmites australis. Introduced P. australis contributes to marsh accretion and eliminates marsh surface pools thereby adversely affecting fish by reducing access to intertidal habitats essential for feeding, reproduction, and refuge. Our study assessed the condition of resident fish populations (Fundulus heteroclitus) at four tidally restricted and four tidally restored marshes in New England invaded by P. australis relative to adjacent reference salt marshes. We used physiological and morphological indicators of fish condition, including proximate body composition (% lipid, % lean dry, % water), recent daily growth rate, age class distributions, parasite prevalence, female gravidity status, length-weight regressions, and a common morphological indicator (Fulton’s K) to assess impacts to fish health. We detected a significant increase in the quantity of parasites infecting fish in tidally restricted marshes but not in those where tidal flow was restored to reduce P. australis cover. Using fish length as a covariate, we found that unparasitized, non-gravid F. heteroclitus in tidally restricted marshes had significantly reduced lipid reserves and increased lean dry (structural) mass relative to fish residing in reference marshes. Fish in tidally restored marshes were equivalent across all metrics relative to those in reference marshes indicating that habitat quality was restored via increased tidal flushing. Reference marshes adjacent to tidally restored sites contained the highest abundance of young fish (ages 0–1) while tidally restricted marshes contained the lowest. Results indicate that F. heteroclitus residing in physically and hydrologically altered marshes are at a disadvantage relative to fish in reference marshes but the effects can be reversed through ecological restoration. PMID

  13. Impacts of salt marsh plants on tidal channel initiation and inheritance

    NASA Astrophysics Data System (ADS)

    Schwarz, C.; Ye, Q. H.; Wal, D.; Zhang, L. Q.; Bouma, T.; Ysebaert, T.; Herman, P. M. J.

    2014-02-01

    At the transition between mudflat and salt marsh, vegetation is traditionally regarded as a sustaining factor for previously incised mudflat channels, able to conserve the channel network via bank stabilization following plant colonization (i.e., vegetation-stabilized channel inheritance). This is in contrast to recent studies revealing vegetation as the main driver of tidal channel emergence through vegetation-induced channel erosion. We present a coupled hydrodynamic morphodynamic plant growth model to simulate plant expansion and channel formation by our model species (Spartina alterniflora) during a mudflat-salt marsh transition with various initial bathymetries (flat, shoal dense, shoal sparse, and deep dense channels). This simulated landscape development is then compared to remote sensing images of the Yangtze estuary, China, and the Scheldt estuary in Netherlands. Our results propose the existence of a threshold in preexisting mudflat channel depth, which favors either vegetation-stabilized channel inheritance or vegetation-induced channel erosion processes. The increase in depth of preexisting mudflat channels favors flow routing through them, consequently leaving less flow and momentum remaining for vegetation-induced channel erosion processes. This threshold channel depth will be influenced by field specific parameters such as hydrodynamics (tidal range and flow), sediment characteristics, and plant species. Hence, our study shows that the balance between vegetation-stabilized channel inheritance and vegetation-induced channel erosion depends on ecosystem properties.

  14. Measuring the Role of Ecological Shift and Environmental Change on Organic Carbon Stocks in Salt Marshes and Mangrove Dominated Wetlands from the Texas Gulf Coast

    NASA Astrophysics Data System (ADS)

    Norwood, M. J.; Louchouarn, P.; Armitage, A. R.; HighField, W.; Brody, S.; White, N.

    2014-12-01

    Texas coastal wetlands are dynamic marsh-mangrove ecotones that play an important role in fishery recruitment, storm buffering, and carbon storage. Historically, C4 salt marsh plants, such as Spartina alterniflora, have dominated the Texas Gulf Coast. For the past 2-3 decades, some of these ecosystems have experienced community shifts with woody tropical plants (Avicennia germinans) competing for resources. This study presents new results on the carbon sequestration potential following such ecological shifts as well as coastal development and wetland loss along the coast of Texas. The recorded change from native grass-dominated C4 salt marshes to wood-dominated C3 mangroves over the last 20 years (1990-2010: 4,660 km2) leads to a non-significant loss in aboveground organic carbon (OC) stocks (-6.5.106 g OC). The most substantial loss of aboveground OC in Texas coastal salt marshes is due to the transformation of these wetlands into tidal flats and open water (-7.53.108 g OC). Similarly, the largest losses in aboveground OC stocks from mangrove ecosystems (-1.57.107 g OC) are due to replacement by open water. Along with the decrease in aboveground OC stocks, we identified a significant decrease in sedimentary OC inventories due to the loss of salt marsh and mangrove coverage (-3.69.109 g OC and 5.71.107 g OC, respectively). In contrast, mangrove expansion into mudflat and salt marsh environments led to a positive addition in aboveground OC stocks (2.78.108 g OC) and increased OC sedimentary inventories (2.32.109 g OC). Mangrove expansion offsets only 70% of the total calculated OC loss (-4.51.109 g OC) in coastal wetlands along the Texas gulf coast over the 20-year study period. This deficit loss is primarily attributed to environmental pressures on coastal salt marshes (i.e., sea level rise, urban and coastal development, erosion).

  15. Salt Marsh Sediment Biogeochemical Response to the Deep Water Horizon BP Oil Spill (Skiff Island, LA, and Cat Island, Marsh Point, and Salt Pan Island, MS)

    NASA Astrophysics Data System (ADS)

    Guthrie, C. L.; McNeal, K. S.; Mishra, D. R.; Blakeney, G. A.

    2012-12-01

    The large scale impact of the Deep Water Horizon BP Oil Spill on biological communities can be better predicted by developing an understanding of how carbon loading from the spill is affecting the microbial and biological communities of salt marshes along the Mississippi and Louisiana Gulf Coast. Sediment biogeochemical processes that degrade enriched carbon pools through sulfate reduction are primarily responsible for the biological breakdown of spilled hydrocarbons (Shin et al., 2000). Determination of sulfide concentration in contaminated areas, therefore, allows for an assessment of the oil spill impact on salt marsh at Skiff Island, LA, and Marsh Point, Cat Island, and Salt Pan Island, MS. As a result of carbon loading, porewater hydrogen sulfide (H2S) concentrations are expected to show an increase in the largely anoxic wetland sediment, making the sediment more toxic and inhospitable to marsh vegetation (Alber et al., 2008). High sulfide levels due to carbon loading in hydrocarbon contaminated salt marshes cause microbial activity to increase at the plant rhizospere, leading to plant browning and die back (Eldridge and Morse 2000). Preliminary analysis of the Marsh Point study area was conducted in Fall 2010. Sediment cores indicated that sulfate reducing bacteria are significantly more active in contaminated sediments, producing sulfide concentrations 20x higher than in non-contaminated sediments. The difference in the sediment biogeochemistry between the contaminated site and non-contaminated site at Marsh Point, MS indicated that the effects of hydrocarbon contamination on sulfur cycling in salt marshes should be more spatially explored. In Fall 2011, the study was expanded to include Skiff Island, LA, and Cat Island, and Salt Pan Island, MS in addition to Marsh Point, MS. Sediment electrode profiles (H2S, O2, pH, and Eh), degree of hydrocarbon contamination (GC), grain size analysis, microbial community substrate level carbon utilization profiles, and

  16. How sea level rise affects sedimentation, plant growth, and carbon accumulation on coastal salt marshes

    NASA Astrophysics Data System (ADS)

    Mudd, S. M.; Howell, S. M.; Morris, J. T.

    2009-12-01

    The rate of accretion on coastal salt marshes depends on feedbacks between flow, macrophyte growth, and sedimentation. Under favourable conditions, marsh accretion rates will keep pace with the local rate of sea level rise. Marsh accretion is driven by both organic and inorganic sedimentation; mineral rich marshes will need less organic sedimentation to keep pace with sea level rise. Here we use a numerical model of marsh accretion, calibrated by sediment cores, to explore the relationship between sea level rise and carbon sequestration on salt marshes in the face of differing supplies of inorganic sediment. The model predicts that changes in carbon storage resulting from changing sediment supply or sea-level rise are strongly dependant on the background sediment supply: if inorganic sediment supply is reduced in an already sediment poor marsh the storage of organic carbon will increase to a far greater extent than in a sediment-rich marsh, provided that the rate of sea-level rise does not exceed a threshold. These results imply that altering sediment supply to estuaries (e.g., by damming upstream rivers or altering littoral sediment transport) could lead to significant changes in the carbon budgets of coastal salt marshes.

  17. Marine fungal diversity: a comparison of natural and created salt marshes of the north-central Gulf of Mexico.

    PubMed

    Walker, Allison K; Campbell, Jinx

    2010-01-01

    Marine fungal communities of created salt marshes of differing ages were compared with those of two reference natural salt marshes. Marine fungi occurring on the lower 30 cm of salt marsh plants Spartina alterniflora and Juncus roemerianus were inventoried with morphological and molecular methods (ITS T-RFLP analysis) to determine fungal species richness, relative frequency of occurrence and ascomata density. The resulting profiles revealed similar fungal communities in natural salt marshes and created salt marshes 3 y old and older with a 1.5 y old created marsh showing less fungal colonization. A 26 y old created salt marsh consistently exhibited the highest fungal species richness. Ascomata density of the dominant fungal species on each host was significantly higher in natural marshes than in created marshes at all three sampling dates. This study indicates marine fungal saprotroph communities are present in these manmade coastal salt marshes as early as 1 y after marsh creation. The lower regions of both plant hosts were dominated by a small number of marine ascomycete species consistent with those species previously reported from salt marshes of the East Coast of USA. PMID:20524584

  18. Marine fungal diversity: a comparison of natural and created salt marshes of the north-central Gulf of Mexico.

    PubMed

    Walker, Allison K; Campbell, Jinx

    2010-01-01

    Marine fungal communities of created salt marshes of differing ages were compared with those of two reference natural salt marshes. Marine fungi occurring on the lower 30 cm of salt marsh plants Spartina alterniflora and Juncus roemerianus were inventoried with morphological and molecular methods (ITS T-RFLP analysis) to determine fungal species richness, relative frequency of occurrence and ascomata density. The resulting profiles revealed similar fungal communities in natural salt marshes and created salt marshes 3 y old and older with a 1.5 y old created marsh showing less fungal colonization. A 26 y old created salt marsh consistently exhibited the highest fungal species richness. Ascomata density of the dominant fungal species on each host was significantly higher in natural marshes than in created marshes at all three sampling dates. This study indicates marine fungal saprotroph communities are present in these manmade coastal salt marshes as early as 1 y after marsh creation. The lower regions of both plant hosts were dominated by a small number of marine ascomycete species consistent with those species previously reported from salt marshes of the East Coast of USA.

  19. Balanced Sediment Fluxes in Southern California's Mediterranean-climate Zone Salt Marshes

    NASA Astrophysics Data System (ADS)

    Rosencranz, J. A.; Dickhudt, P.; Ganju, N. K.; Thorne, K.; Takekawa, J.; Ambrose, R. F.; Guntenspergen, G. R.; Brosnahan, S.; MacDonald, G. M.

    2015-12-01

    Salt marsh elevation and geomorphic stability depends on mineral sedimentation. Many southern California, USA salt marshes import sediment during El Niño storm events, but sediment fluxes and mechanisms during dry weather are also potentially important for marsh stability. We calculated tidal creek sediment fluxes within a sediment starved 1.5 km2 salt marsh (Seal Beach) and a less modified 1 km2 marsh (Mugu) with a watershed sediment supply. We measured salt marsh plain suspended sediment concentration and vertical accretion using single stage samplers and marker horizons. At Seal Beach, a 2014 storm yielded 39 and 28 g/s mean sediment fluxes and imported 12000 and 8800 kg in a western channel. This offset 8700 kg export during two months of dry weather, while landward net fluxes in the eastern channel accounted for 33% of the import. During the storm, suspended sediment concentrations on the marsh plain increased by a factor of four; accretion was 1-2 mm near creek levees. An exceptionally high tide sequence at Mugu yielded 4.4 g/s mean sediment flux, importing 1700 kg, accounting for 20% of dry weather fluxes. Overall, low sediment fluxes were observed, suggesting that these salt marshes are currently geomorphically stable. Our results suggest that storms and exceptionally high lunar tides may play large roles, importing sediment and maintaining dry weather sediment flux balances for southern California salt marshes. However, under future climate change and sea-level rise scenarios, results suggest that balanced sediment fluxes may lead to marsh elevational instability, based on estimated mineral sediment deficits.

  20. Balanced sediment fluxes in southern California’s Mediterranean-climate zone salt marshes

    USGS Publications Warehouse

    Rosencranz, Jordan A.; Ganju, Neil K.; Ambrose, Richard F.; Brosnahan, Sandra M.; Dickhudt, Patrick J.; Guntenspergen, Glenn R.; MacDonald, Glen M.; Takekawa, John Y.; Thorne, Karen M.

    2016-01-01

    Salt marsh elevation and geomorphic stability depends on mineral sedimentation. Many Mediterranean-climate salt marshes along southern California, USA coast import sediment during El Niño storm events, but sediment fluxes and mechanisms during dry weather are potentially important for marsh stability. We calculated tidal creek sediment fluxes within a highly modified, sediment-starved, 1.5-km2 salt marsh (Seal Beach) and a less modified 1-km2marsh (Mugu) with fluvial sediment supply. We measured salt marsh plain suspended sediment concentration and vertical accretion using single stage samplers and marker horizons. At Seal Beach, a 2014 storm yielded 39 and 28 g/s mean sediment fluxes and imported 12,000 and 8800 kg in a western and eastern channel. Western channel storm imports offset 8700 kg exported during 2 months of dry weather, while eastern channel storm imports augmented 9200 kg imported during dry weather. During the storm at Mugu, suspended sediment concentrations on the marsh plain increased by a factor of four; accretion was 1–2 mm near creek levees. An exceptionally high tide sequence yielded 4.4 g/s mean sediment flux, importing 1700 kg: 20 % of Mugu’s dry weather fluxes. Overall, low sediment fluxes were observed, suggesting that these salt marshes are geomorphically stable during dry weather conditions. Results suggest storms and high lunar tides may play large roles, importing sediment and maintaining dry weather sediment flux balances for southern California salt marshes. However, under future climate change and sea level rise scenarios, results suggest that balanced sediment fluxes lead to marsh elevational instability based on estimated mineral sediment deficits.

  1. Mosquitoes associated with ditch-plugged and control tidal salt marshes on the Delmarva Peninsula.

    PubMed

    Leisnham, Paul T; Sandoval-Mohapatra, Sarah

    2011-08-01

    A study was conducted during the summer of 2009 (from July to September) to characterize mosquito communities among different habitats in five historically ditched tidal salt marshes and three adjacent wooded areas in the E.A. Vaughn Wetland Management Area on the Maryland Delmarva Peninsula, USA. Study marshes are characteristic of Atlantic coastal salt marshes that had undergone grid ditching from the 1930s to 1950s. In the autumn of 2008 (October and November) ditches were plugged near their outlets in two ('experimental') marshes with the aim to restore their natural tidal hydrology. The three other marshes were not plugged. Marshes were sampled from July to September in 2009 by using standard dip count method. A total of 2,457 mosquito larvae representing six species were collected on 15.4% (86/557) of all sample occasions and 399 adults representing four mosquito species were collected from landing counts. Aedes sollicitans, Anopheles bradleyi and Culex salinarius were the most common species collected in larval habitats, and Ae. sollicitans was the most common adult collected. Wooded habitats had more total mosquitoes, were also more frequently occupied by mosquitoes and had higher densities of mosquitoes than marsh habitats. Almost all larvae collected from marshes were from one experimental and one control site. The majority of larvae at the control site were Ae. sollicitans in marsh pannes while Cx. salinarius, An. bradleyi, Ae. cantator, and Ae. sollicitans were collected in high numbers from ditches at the experimental site. We found a difference in the proportion of marsh pannes occupied by Ae. sollicitans but not total mosquitoes sampled 4-5 days after spring tide events than on other occasions. Salinity measures of 42 larval habitats showed lower median salinity in mosquito-occupied habitats (11.5 ppt) than unoccupied habitats (20.1 ppt), and in habitats in wooded areas followed by ditches and pannes in marsh areas. The results of this study suggest

  2. Mosquitoes Associated with Ditch-Plugged and Control Tidal Salt Marshes on the Delmarva Peninsula

    PubMed Central

    Leisnham, Paul T.; Sandoval-Mohapatra, Sarah

    2011-01-01

    A study was conducted during the summer of 2009 (from July to September) to characterize mosquito communities among different habitats in five historically ditched tidal salt marshes and three adjacent wooded areas in the E.A. Vaughn Wetland Management Area on the Maryland Delmarva Peninsula, USA. Study marshes are characteristic of Atlantic coastal salt marshes that had undergone grid ditching from the 1930s to 1950s. In the autumn of 2008 (October and November) ditches were plugged near their outlets in two (‘experimental’) marshes with the aim to restore their natural tidal hydrology. The three other marshes were not plugged. Marshes were sampled from July to September in 2009 by using standard dip count method. A total of 2,457 mosquito larvae representing six species were collected on 15.4% (86/557) of all sample occasions and 399 adults representing four mosquito species were collected from landing counts. Aedes sollicitans, Anopheles bradleyi and Culex salinarius were the most common species collected in larval habitats, and Ae. sollicitans was the most common adult collected. Wooded habitats had more total mosquitoes, were also more frequently occupied by mosquitoes and had higher densities of mosquitoes than marsh habitats. Almost all larvae collected from marshes were from one experimental and one control site. The majority of larvae at the control site were Ae. sollicitans in marsh pannes while Cx. salinarius, An. bradleyi, Ae. cantator, and Ae. sollicitans were collected in high numbers from ditches at the experimental site. We found a difference in the proportion of marsh pannes occupied by Ae. sollicitans but not total mosquitoes sampled 4–5 days after spring tide events than on other occasions. Salinity measures of 42 larval habitats showed lower median salinity in mosquito-occupied habitats (11.5 ppt) than unoccupied habitats (20.1 ppt), and in habitats in wooded areas followed by ditches and pannes in marsh areas. The results of this study

  3. Biostimulation For The Treatment Of An Oil-Contaminated Coastal Salt Marsh

    EPA Science Inventory

    A field study was conducted on a coastal salt marsh in Nova Scotia, Canada, during the summer of 2000. The objective of the study was to assess the effectiveness of biostimulation in restoring an oil-contaminated coastal marsh dominated by Spartina alterniflora under north...

  4. RELATIONSHIPS OF NITROGEN LOADINGS AND PHYSICAL CHARACTERISTICS WITH PLANT STRUCTURE IN NEW ENGLAND SALT MARSHES

    EPA Science Inventory

    Nitrogen enrichment is hypothesized to cause competitive displacement of dominant plants in New England salt marshes. In this Narragansett Bay, RI, field survey, we examined the vascular plant species richness and the extent, density, and height of Spartina species in ten marshe...

  5. Effects of Tide Stage on the Use of Salt Marshes by Wading Birds in Rhode Island

    EPA Science Inventory

    To determine how tide stage affects wading bird abundance, behavior, and foraging in three Narragansett Bay salt marshes (RI), we conducted surveys at 10-min intervals—across the full tidal range—during six days at each marsh in July/September of 2006. The wading bird community ...

  6. Northeastern Salt Marshes: Elevation Capital and Resilience to Sea Level Rise

    EPA Science Inventory

    Stable tidal salt marshes exist at an elevation that is supra-optimal relative to peak biomass production, which for Spartina alterniflora, and other marsh macrophytes, follows a parabolic distribution as a function of elevation, as a surrogate for inundation frequency. In order...

  7. Effects of salinity variations on pore water flow in salt marshes

    NASA Astrophysics Data System (ADS)

    Shen, Chengji; Jin, Guangqiu; Xin, Pei; Kong, Jun; Li, Ling

    2015-06-01

    Spatial and temporal salinity variations in surface water and pore water commonly exist in salt marshes under the combined influence of tidal inundation, precipitation, evapotranspiration, and inland freshwater input. Laboratory experiments and numerical simulations were conducted to investigate how density gradients associated with salinity variations affect pore water flow in the salt marsh system. The results showed that upward salinity (density) gradients could lead to flow instability and the formation of salt fingers. These fingers, varying in size with the distance from the creek, modified significantly the pore water flow field, especially in the marsh interior. While the flow instability enhanced local salt transport and mixing considerably, the net effect was small, causing only a slight increase in the overall mass exchange across the marsh surface. In contrast, downward salinity gradients exerted less influence on the pore water flow in the marsh soil and slightly weakened the surface water and groundwater exchange across the marsh surface. Numerical simulations revealed similar density effects on pore water flow at the field scale under realistic conditions. These findings have important implications for studies of marsh soil conditions concerning plant growth as well as nutrient exchange between the marsh and coastal marine system.

  8. Comparison of Bottomless Lift Nets and Breder Traps for Sampling Salt-Marsh Nekton

    EPA Science Inventory

    Vegetated salt-marsh surfaces provide refuge, forage, and spawning habitat for estuarine nekton, yet are threatened by accelerating rates of sea-level rise in southern New England and elsewhere. Nekton responses to ongoing marsh surface changes need to be evaluated with effective...

  9. Response of salt marsh and mangrove wetlands to changes in atmospheric CO2, climate, and sea-level

    USGS Publications Warehouse

    Mckee, Karen L.; Rogers, Kerrylee; Saintilan, Neil; Middleton, Beth A.

    2012-01-01

    Coastal salt marsh and mangrove ecosystems are particularly vulnerable to changes in atmospheric CO2 concentrations and associated climate and climate-induced changes. We provide a review of the literature detailing theoretical predictions and observed responses of coastal wetlands to a range of climate change stressors, including CO2, temperature, rainfall, and sea-level rise. This review incorporates a discussion of key processes controlling responses in different settings and thresholds of resilience derived from experimental and observational studies. We specifically consider the potential and observed effects on salt marsh and mangrove vegetation of changes in (1) elevated [CO2] on physiology, growth, and distribution; (2) temperature on distribution and diversity; (3) rainfall and salinity regimes on growth and competitive interactions; and (4) sea level on geomorphological, hydrological, and biological processes.

  10. Salt marshes. (Latest citations from Oceanic abstracts). Published Search

    SciTech Connect

    Not Available

    1993-03-01

    The bibliography contains citations concerning the environmental protection of coastal marshes. The citations explore the fauna and flora of the marshes, geological and ecological processes, and the effects of marine pollution. Seasonal and environmental variations, the effects of erosion, and stabilization techniques of marshes are also considered. (Contains 250 citations and includes a subject term index and title list.)

  11. Feedbacks underlie the resilience of salt marshes and rapid reversal of consumer-driven die-off.

    PubMed

    Altieri, Andrew H; Bertness, Mark D; Coverdale, Tyler C; Axelman, Eric E; Herrmann, Nicholas C; Szathmary, P Lauren

    2013-07-01

    Understanding ecosystem resilience to human impacts is critical for conservation and restoration. The large-scale die-off of New England salt marshes was triggered by overfishing and resulted from decades of runaway crab grazing. In 2009, however, cordgrass began to recover, decreasing die-off -40% by 2010. We used surveys and experiments to test whether plant-substrate feedbacks underlie marsh resilience. Initially, grazer-generated die-off swept through the cordgrass, creating exposed, stressful peat banks that inhibited plant growth. This desertification cycle broke when banks eroded and peat transitioned into mud with fewer herbivores, less grazing, and lower physical stress. Cordgrass reestablished in these areas through a feedback where it engineered a recovery zone by further ameliorating physical stresses and facilitating additional revegetation. Our results reveal that feedbacks can play a critical role in rapid, reversible ecosystem shifts associated with human impacts, and that the interplay of facilitative and consumer interactions should be incorporated into resilience theory.

  12. Test of salt marsh as a site of production and export of fish biomass with implications for impoundment management and restoration

    USGS Publications Warehouse

    Stevens, Philip W.

    2002-01-01

    Salt marshes are among the most productive ecosystems in the world, and although they are thought to enhance the productivity of open estuarine waters, the mechanism by which energy transfer occurs has been debated for decades. One possible mechanism is the transfer of saltmarsh production to estuarine waters by vagile fishes and invertebrates. Saltmarsh impoundments in the Indian River Lagoon, Florida, that have been reconnected to the estuary by culverts provide unique opportunities for studying marsh systems with respect to aquatic communities. The boundaries between salt marshes and the estuary are clearly defined by a system of dikes that confine fishes into a known area, and the exchange of aquatic organisms are restricted to culverts where they may be easily sampled. A multi-gear approach was used monthly to estimate fish standing stock, fish ingress/egress, and predation. Changes in saltmarsh fish abundance, and exchange with the estuary reflected the seasonal pattern of marsh flooding in the xv northern Indian River Lagoon system. During a six month period of marsh flooding, saltmarsh fishes had continuous access to marsh food resources. Piscivorous fishes regularly entered the marsh via creeks and ditches to prey upon marsh fishes, and piscivorous birds aggregated following major fish migrations to the marsh surface or to deep habitats. As water levels receded in winter, saltmarsh fishes concentrated into deep habitats and migration to the estuary ensued. The monthly estimates of fish standing stock, net fish ingress, and predation were used to develop a biomass budget to estimate annual production of fishes and the relative yield to predatory fish, birds, and direct migration to the estuary. Annual production of saltmarsh fishes was estimated to be 17.7 g·m-2 salt marsh, which falls within the range of previously reported values for estuarine fish communities. The relative yields were at least 21% to piscivorous fishes, 14% to piscivorous birds, and 32

  13. Greenhouse gas emissions in salt marshes and their response to nitrogen loading

    NASA Astrophysics Data System (ADS)

    Tang, J.; Moseman-Valtierra, S.; Kroeger, K. D.; Morkeski, K.; Carey, J.

    2015-12-01

    Salt marshes play an important role in global and regional carbon and nitrogen cycling. Anthropogenic nitrogen loading may alter greenhouse gas (GHG, including CO2, CH4, and N2O) emissions and carbon sequestration in salt marshes. We measured GHG emissions biweekly for two growing seasons across a nitrogen-loading gradient of four Spartina salt marshes in Waquoit Bay, Massachusetts. In addition, we conducted nitrogen addition experiments in a pristine marsh by adding low and high nitrate bi-weekly during the summer. The GHG flux measurements were made in situ with a state-of-the-art mobile gas measurement system using the cavity ring down technology that consists of a CO2/CH4 analyzer (Picarro) and an N2O/CO analyzer (Los Gatos). We observed strong seasonal variations in greenhouse gas emissions. The differences in gas emissions across the nitrogen gradient (between 1 and 10 gN m-2y-1) were not significant, but strong pulse emissions of N2O were observed after nitrogen was artificially added to the marsh. We found that the studied salt marsh was a significant carbon sink (NEP ~ 380 gC m-2y-1). CH4 fluxes are 3 orders of magnitude less than CO2 fluxes in the salt marsh. Carbon fluxes are driven by light, salinity, tide, and temperature. We conclude that restoration or conservation of this carbon sink has a significant social benefit for carbon credit.

  14. The ecology of regularly flooded salt marshes of New England: A community profile

    SciTech Connect

    Teal, J.M.

    1986-06-01

    The current state-of-the-art in scientific knowledge about intertidal salt marshes is presented, but restricted to one habitat in New England, specifically Great Sippewissett at Falmouth, Massachusetts. (PSB)

  15. Rhode Island Salt Marshes: Elevation Capital and Resilience to Sea Level Rise

    EPA Science Inventory

    Tidal salt marsh is especially sensitive to deterioration due to the effects of accelerated sea level rise when combined with other anthropogenically linked stressors, including crab herbivory, changes in tidal hydrology, nutrient loading, dam construction, changes in temperature...

  16. DENITRIFICATION IN FRINGING SALT MARSHES OF NARRAGANSETT BAY, RHODE ISLAND, USA

    EPA Science Inventory

    In the past century, loading of terrestrial inorganic nitrogen to coastal receiving waters has increased dramatically. Salt marshes, because of their location between upland regions and coastal waters and their recognized role as nutrient transformers, have the potential to ameli...

  17. Two New Murals by John Biggers: Salt Marsh and Nubia, Origins of Business and Commerce.

    ERIC Educational Resources Information Center

    Theisen, Olive Jensen

    2001-01-01

    Provides background information on the life and career of muralist John Biggers. Focuses on two of his murals, offering a description and information about each: (1) "Salt Marsh;" and (2) "Nubia, the Origins of Business and Commerce." (CMK)

  18. The role of Phragmites australis in mediating inland salt marsh migration in a Mid-Atlantic estuary.

    PubMed

    Smith, Joseph A M

    2013-01-01

    Many sea level rise adaptation plans emphasize the protection of adjacent uplands to allow for inland salt marsh migration, but little empirical information exists on this process. Using aerial photos from 1930 and 2006 of Delaware Estuary coastal habitats in New Jersey, I documented the rate of coastal forest retreat and the rate of inland salt marsh migration across 101.1 km of undeveloped salt marsh and forest ecotone. Over this time, the amount of forest edge at this ecotone nearly doubled. In addition, the average amount of forest retreat was 141.2 m while the amount of salt marsh inland migration was 41.9 m. Variation in forest retreat within the study area was influenced by variation in slope. The lag between the amount of forest retreat and salt marsh migration is accounted for by the presence of Phragmites australis which occupies the forest and salt marsh ecotone. Phragmites expands from this edge into forest dieback areas, and the ability of salt marsh to move inland and displace Phragmites is likely influenced by salinity at both an estuary-wide scale and at the scale of local subwatersheds. Inland movement of salt marsh is lowest at lower salinity areas further away from the mouth of the estuary and closer to local heads of tide. These results allow for better prediction of salt marsh migration in estuarine landscapes and provide guidance for adaptation planners seeking to prioritize those places with the highest likelihood of inland salt marsh migration in the near-term.

  19. Flow, sedimentation, and biomass production on a vegetated salt marsh in South Carolina: toward a predictive model of marsh morphologic and ecologic evolution

    NASA Astrophysics Data System (ADS)

    Fagherazzi, S.; Mudd, S. M.; Morris, J. T.; Furbish, D. J.

    2004-12-01

    A 1-D model for exploring the interaction between hydrodynamics, sedimentation, and plant community evolution on a salt marsh populated by Spartina alterniflora is developed. In the model tidally induced flows over marsh platforms are affected by S. alterniflora through drag forces. In general macrophyte characteristics are determined by a wide range of processes; here, based on field studies at North Inlet estuary, South Carolina, the biomass of the S. alterniflora on the marsh platform is simply related to their time of submergence under tidally induced flows. Additionally, field data collected at North Inlet are used to relate biomass to plant area per unit volume, stem diameter, and an empirical drag coefficient. Sedimentation is also related to biomass, through either organogenic deposition or trapping of suspended sediment particles. The morphologic evolution of simulated marshes is explored by varying the sedimentation process and the rate of sea level rise. Different sedimentation processes result in marshes with different morphologies. An organogenic marsh is predicted to evolve under a regime of steady sea level rise into a platform with a relatively flat surface, whereas a marsh developed primarily through a trapping mechanism is predicted to have a surface that slopes gently away from the salt marsh creek. As predicted by 0-D modeling studies, sea level rise may be accommodated up to a certain critical sea level rise rate, after which the salt marsh platform will drown. Marshes that accrete through sediment trapping adjust to changes in sea level more rapidly than marshes that accrete through organogenic deposition.

  20. Biotic interactions mediate the expansion of black mangrove (Avicennia germinans) into salt marshes under climate change.

    PubMed

    Guo, Hongyu; Zhang, Yihui; Lan, Zhenjiang; Pennings, Steven C

    2013-09-01

    Many species are expanding their distributions to higher latitudes due to global warming. Understanding the mechanisms underlying these distribution shifts is critical for better understanding the impacts of climate changes. The climate envelope approach is widely used to model and predict species distribution shifts with changing climates. Biotic interactions between species, however, may also influence species distributions, and a better understanding of biotic interactions could improve predictions based solely on climate envelope models. Along the northern Gulf of Mexico coast, USA, subtropical black mangrove (Avicennia germinans) at the northern limit of its distribution grows sympatrically with temperate salt marsh plants in Florida, Louisiana, and Texas. In recent decades, freeze-free winters have led to an expansion of black mangrove into salt marshes. We examined how biotic interactions between black mangrove and salt marsh vegetation along the Texas coast varied across (i) a latitudinal gradient (associated with a winter-temperature gradient); (ii) the elevational gradient within each marsh (which creates different marsh habitats); and (iii) different life history stages of black mangroves (seedlings vs. juvenile trees). Each of these variables affected the strength or nature of biotic interactions between black mangrove and salt marsh vegetation: (i) Salt marsh vegetation facilitated black mangrove seedlings at their high-latitude distribution limit, but inhibited black mangrove seedlings at lower latitudes; (ii) mangroves performed well at intermediate elevations, but grew and survived poorly in high- and low-marsh habitats; and (iii) the effect of salt marsh vegetation on black mangroves switched from negative to neutral as black mangroves grew from seedlings into juvenile trees. These results indicate that the expansion of black mangroves is mediated by complex biotic interactions. A better understanding of the impacts of climate change on ecological

  1. Restoring marsh elevation in a rapidly subsiding salt marsh by thin-layer deposition of dredged material

    USGS Publications Warehouse

    Ford, M.A.; Cahoon, D.R.; Lynch, J.C.

    1999-01-01

    Thin-layer deposition of dredged material on coastal marsh by means of high-pressure spray dredging (Jet-Spray??2) technology has been proposed as a mechanism to minimize wetland impacts associated with traditional bucket dredging technologies and to restore soil elevations in deteriorated marshes of the Mississippi River delta. The impact of spray dredging on vegetated marsh and adjacent shallow-water habitat (formerly vegetated marsh that deteriorated to open water) was evaluated in a 0.5-ha Spartina alterniflora-dominated salt marsh in coastal Louisiana. The thickness of dredged sediment deposits was determined from artificial soil marker horizons and soil elevation change was determined from sedimentation-erosion tables (SET) established prior to spraying in both sprayed and reference marshes. The vertical accretion and elevation change measurements were made simultaneously to allow for calculation of shallow (~5 m depth) subsidence (accretion minus elevation change). Measurements made immediately following spraying in July 1996 revealed that stems of S. alterniflora were knocked down by the force of the spray and covered with 23 mm of dredged material. Stems of S. alterniflora soon recovered, and by July 1997 the percent cover of S. alterniflora had increased three-fold over pre-project conditions. Thus, the layer of dredged material was thin enough to allow for survival of the S. alterniflora plants, with no subsequent colonization by plant species typical of higher marsh zones. By February 1998, 62 mm of vertical accretion accumulated at this site, and little indication of disturbance was noted. Although not statistically significant, soil elevation change was greater than accretion on average at both the spray and reference marshes, suggesting that subsurface expansion caused by increased root biomass production and/or pore water storage influence elevation in this marsh region. In the adjacent shallow water pond, 129 mm of sediment was deposited in July

  2. Intertidal variation in foraminiferal species diversity: Mississippi-Louisiana salt marshes

    SciTech Connect

    Lariccia, M.P.; Krutak, P.R.

    1983-03-01

    Salt marshes are tide-stressed environments where ecologic variables exert strong selective control upon the distribution, type, and abundance of organisms. Ecologic conditions range from marine to terrestrial; hence gradational and/or abrupt environmental changes across marshes produce similar gradients in communities of organisms and their biotopes. Salt marshes are one of the present-day sites of peat accumulation. They represent a potential millieu for lignite and coal formation. Recognition of microenvironments within such marshes will provide coal explorationists and paleontologists with another tool for predicting the location of subsurface peats, lignites, and coals. Twenty-eight modern bottom samples were collected for analysis for foraminiferal populations (total = live + dead) in the Hancock County, Mississippi, and Pearl River, Louisiana, marshes during May and June 1981. After extracting a minimum of 300 specimens/sample, foraminiferal species diversity patterns among the 14 doubly sampled stations were studied.

  3. Evidence for iron-sulfate coupling in salt marsh sediments

    NASA Astrophysics Data System (ADS)

    Mills, Jennifer; Antler, Gilad; Turchyn, Alexandra

    2014-05-01

    Organic carbon burial in shallow marine sediments represents an important net sink in the global carbon cycle. Microbially mediated oxidation of organic matter in oxic, suboxic, and anoxic sediments however, prevents the ultimate burial of organic carbon and its removal from the surface of the planet. Although the subsurface transformations of organic carbon have been studied extensively, an enigmatic question remains: when organic matter is deposited, what determines whether it will be buried, reoxidized, or undergo methanogenesis? One hypothesis is that the sulfur cycle, due to the abundance of sulfate in many surface environments, dominates the subsurface oxidation or other fate of organic carbon. However, it has also been suggested that iron may in turn play a key role in determining the behavior of the sulfur cycle. To better understand the controls on these processes, we are using stable isotope and geochemical techniques to explore the microbially mediated oxidation of organic carbon in salt marsh sediments in North Norfolk, UK. In these sediments there is a high supply of organic carbon, iron, and sulfate (from diurnal tidal cycles). Thus these environments may provide insight into the nature of interactions between the carbon, iron, and sulfur cycles. A series of sampling missions was undertaken in the autumn and winter of 2013-2014. In subsurface fluid samples we observe very high ferrous iron concentrations (>1mM), indicative of extended regions of iron reduction (to over 30cm depth). Within these zones of iron reduction we would predict no sulfate reduction, and as expected δ34Ssulfate remains unchanged with depth. However, δ18Osulfate exhibits significant enrichments of up to 5 permil. This decoupling in the sulfur and oxygen isotopes of sulfate is suggestive of a sulfate recycling process in which sulfate is reduced to an intermediate sulfur species and subsequently reoxidized to sulfate. Taken together, these data suggest that microbial assemblages

  4. Accumulation and transport of Cd, Cu, and Pb in an estuarine salt marsh surface microlayer

    SciTech Connect

    Lion, L.W.; Leckie, J.O.

    1982-01-01

    Dissolved and particulate Cd, Cu, and Pb were measured in bulk solution and surface microlayer samples from an intertidal salt marsh in south San Francisco Bay. The phase distribution (dissolved vs. particulate) of metals was consistent with their calculated speciation in computer-simulated sea-salt matrices. Trace metal enrichment at the microlayer corresponded with physical events at the sample site. Advective exchange of Cd, Cu, and Pb between the estuary and marsh systems was dominated by transport of bulk suspended particulate metals, with an apparent net export from the marsh to the bay.

  5. What happens to soil organic carbon as coastal marsh ecosystems change in response to increasing salinity? An exploration using ramped pyrolysis

    NASA Astrophysics Data System (ADS)

    Williams, Elizabeth K.; Rosenheim, Brad E.

    2015-07-01

    Coastal wetlands store vast amounts of organic carbon, globally, and are becoming increasingly vulnerable to the effects of anthropogenic sea level rise. To understand the effect of sea level rise on organic carbon fate and preservation in this global sink, it is necessary to characterize differences in the biogeochemical stability of coastal wetland soil organic carbon (SOC). Here we use ramped pyrolysis/oxidation decomposition characteristics as proxies for SOC stability to understand the fate of carbon storage in coastal wetlands comprising the Mississippi River deltaic plain, undergoing rapid rates of local sea level rise. Soils from three wetland types (fresh, brackish, and salt marshes) along a salinity gradient were subjected to ramped pyrolysis analysis to evaluate decomposition characteristics related to thermochemical stability of SOC. At equivalent soil depths, we observed that fresh marsh SOC was more stable than brackish and salt marsh SOC. Depth, isotopic, elemental, and chemical compositions, bulk density, and water content of SOC all exhibited different relationships with SOC stability across the marsh salinity gradient, indicative of different controls on SOC stability within each marsh type. The differences in stability imply stronger preservation potential of fresh marsh soil carbon, compared to that of salt and brackish marshes. Considering projected marsh ecosystem responses to sea level rise, these observed stability differences are important in planning and implementing coastal wetland carbon-focused remediation and improving climate model feedbacks with the carbon cycle. Specifically, our results imply that ecosystem changes associated with sea level rise will initiate the accumulation of less stable carbon in coastal wetlands.

  6. High Frequency Monitoring of the Quantity and Quality of Dissolved Organic Matter Flux Between Salt Marshes and Plum Island Sound, MA

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Raymond, P.

    2012-12-01

    Salt marshes are highly productive continental margin ecosystems, due to abundant solar radiation, water, and nutrients provided by tidal water. The unique bi-directional water movement introduced by tidal effect has a major impact on the formation and productivity of salt marsh and the material exchange between salt marsh and adjacent estuary. As a major term in carbon, energy, and nutrient budget for aquatic ecosystem, dissolved organic matter (DOM) has broad impact on food webs, carbon cycle, and nutrient retention/release. The frequency and period of DOM measurement is greatly increased by the use of reagent-free, low-cost, and reliable measurement with fluorescent and UV sensors measuring the chromophoric fraction of total DOM. Although fluorescent sensors can only measure concentration, UV absorbance in a wide spectral range (200nm-380nm) could potentially provide information on DOM composition. With the help of accurate direct real time water flux measurement and lab analysis of lability, DON, and 3D excitation emission matrix spectroscopy (EEMs), a database of DOM quantity and quality exchanged between several comparative salt marshes and Plum Island Sound, MA could be established to study the dynamics of DOM behavior in the salt marsh-estuary system. Understanding DOM source and fate is very important for evaluating the role of salt marsh in the carbon cycle and food web in coastal and global scale because coastal carbon cycling represents up to 21% of the ocean's primary production (Jahnke 2008). In addition, the approaches outlined in this proposal have broad applicability to study DOM quantity and quality in the material exchange theme between systems.

  7. Native-Invasive Plants vs. Halophytes in Mediterranean Salt Marshes: Stress Tolerance Mechanisms in Two Related Species.

    PubMed

    Al Hassan, Mohamad; Chaura, Juliana; López-Gresa, María P; Borsai, Orsolya; Daniso, Enrico; Donat-Torres, María P; Mayoral, Olga; Vicente, Oscar; Boscaiu, Monica

    2016-01-01

    Dittrichia viscosa is a Mediterranean ruderal species that over the last decades has expanded into new habitats, including coastal salt marshes, ecosystems that are per se fragile and threatened by human activities. To assess the potential risk that this native-invasive species represents for the genuine salt marsh vegetation, we compared its distribution with that of Inula crithmoides, a taxonomically related halophyte, in three salt marshes located in "La Albufera" Natural Park, near the city of Valencia (East Spain). The presence of D. viscosa was restricted to areas of low and moderate salinity, while I. crithmoides was also present in the most saline zones of the salt marshes. Analyses of the responses of the two species to salt and water stress treatments in controlled experiments revealed that both activate the same physiological stress tolerance mechanisms, based essentially on the transport of toxic ions to the leaves-where they are presumably compartmentalized in vacuoles-and the accumulation of specific osmolytes for osmotic adjustment. The two species differ in the efficiency of those mechanisms: salt-induced increases in Na(+) and Cl(-) contents were higher in I. crithmoides than in D. viscosa, and the osmolytes (especially glycine betaine, but also arabinose, fructose and glucose) accumulated at higher levels in the former species. This explains the (slightly) higher stress tolerance of I. crithmoides, as compared to D. viscosa, established from growth inhibition measurements and their distribution in nature. The possible activation of K(+) transport to the leaves under high salinity conditions may also contribute to salt tolerance in I. crithmoides. Oxidative stress level-estimated from malondialdehyde accumulation-was higher in the less tolerant D. viscosa, which consequently activated antioxidant responses as a defense mechanism against stress; these responses were weaker or absent in the more tolerant I. crithmoides. Based on these results, we

  8. Native-Invasive Plants vs. Halophytes in Mediterranean Salt Marshes: Stress Tolerance Mechanisms in Two Related Species.

    PubMed

    Al Hassan, Mohamad; Chaura, Juliana; López-Gresa, María P; Borsai, Orsolya; Daniso, Enrico; Donat-Torres, María P; Mayoral, Olga; Vicente, Oscar; Boscaiu, Monica

    2016-01-01

    Dittrichia viscosa is a Mediterranean ruderal species that over the last decades has expanded into new habitats, including coastal salt marshes, ecosystems that are per se fragile and threatened by human activities. To assess the potential risk that this native-invasive species represents for the genuine salt marsh vegetation, we compared its distribution with that of Inula crithmoides, a taxonomically related halophyte, in three salt marshes located in "La Albufera" Natural Park, near the city of Valencia (East Spain). The presence of D. viscosa was restricted to areas of low and moderate salinity, while I. crithmoides was also present in the most saline zones of the salt marshes. Analyses of the responses of the two species to salt and water stress treatments in controlled experiments revealed that both activate the same physiological stress tolerance mechanisms, based essentially on the transport of toxic ions to the leaves-where they are presumably compartmentalized in vacuoles-and the accumulation of specific osmolytes for osmotic adjustment. The two species differ in the efficiency of those mechanisms: salt-induced increases in Na(+) and Cl(-) contents were higher in I. crithmoides than in D. viscosa, and the osmolytes (especially glycine betaine, but also arabinose, fructose and glucose) accumulated at higher levels in the former species. This explains the (slightly) higher stress tolerance of I. crithmoides, as compared to D. viscosa, established from growth inhibition measurements and their distribution in nature. The possible activation of K(+) transport to the leaves under high salinity conditions may also contribute to salt tolerance in I. crithmoides. Oxidative stress level-estimated from malondialdehyde accumulation-was higher in the less tolerant D. viscosa, which consequently activated antioxidant responses as a defense mechanism against stress; these responses were weaker or absent in the more tolerant I. crithmoides. Based on these results, we

  9. Native-Invasive Plants vs. Halophytes in Mediterranean Salt Marshes: Stress Tolerance Mechanisms in Two Related Species

    PubMed Central

    Al Hassan, Mohamad; Chaura, Juliana; López-Gresa, María P.; Borsai, Orsolya; Daniso, Enrico; Donat-Torres, María P.; Mayoral, Olga; Vicente, Oscar; Boscaiu, Monica

    2016-01-01

    Dittrichia viscosa is a Mediterranean ruderal species that over the last decades has expanded into new habitats, including coastal salt marshes, ecosystems that are per se fragile and threatened by human activities. To assess the potential risk that this native-invasive species represents for the genuine salt marsh vegetation, we compared its distribution with that of Inula crithmoides, a taxonomically related halophyte, in three salt marshes located in “La Albufera” Natural Park, near the city of Valencia (East Spain). The presence of D. viscosa was restricted to areas of low and moderate salinity, while I. crithmoides was also present in the most saline zones of the salt marshes. Analyses of the responses of the two species to salt and water stress treatments in controlled experiments revealed that both activate the same physiological stress tolerance mechanisms, based essentially on the transport of toxic ions to the leaves—where they are presumably compartmentalized in vacuoles—and the accumulation of specific osmolytes for osmotic adjustment. The two species differ in the efficiency of those mechanisms: salt-induced increases in Na+ and Cl− contents were higher in I. crithmoides than in D. viscosa, and the osmolytes (especially glycine betaine, but also arabinose, fructose and glucose) accumulated at higher levels in the former species. This explains the (slightly) higher stress tolerance of I. crithmoides, as compared to D. viscosa, established from growth inhibition measurements and their distribution in nature. The possible activation of K+ transport to the leaves under high salinity conditions may also contribute to salt tolerance in I. crithmoides. Oxidative stress level—estimated from malondialdehyde accumulation—was higher in the less tolerant D. viscosa, which consequently activated antioxidant responses as a defense mechanism against stress; these responses were weaker or absent in the more tolerant I. crithmoides. Based on these results

  10. Herbivory affects salt marsh succession dynamics by suppressing the recovery of dominant species.

    PubMed

    Daleo, Pedro; Alberti, Juan; Pascual, Jesús; Canepuccia, Alejandro; Iribarne, Oscar

    2014-05-01

    Disturbance can generate heterogeneous environments and profoundly influence plant diversity by creating patches at different successional stages. Herbivores, in turn, can govern plant succession dynamics by determining the rate of species replacement, ultimately affecting plant community structure. In a south-western Atlantic salt marsh, we experimentally evaluated the role of herbivory in the recovery following disturbance of the plant community and assessed whether herbivory affects the relative importance of sexual and clonal reproduction on these dynamics. Our results show that herbivory strongly affects salt marsh secondary succession by suppressing seedlings and limiting clonal colonization of the dominant marsh grass, allowing subordinate species to dominate disturbed patches. These results demonstrate that herbivores can have an important role in salt marsh community structure and function, and can be a key force during succession dynamics.

  11. Remote sensing of biomass and annual net aerial primary productivity of a salt marsh

    NASA Technical Reports Server (NTRS)

    Hardisky, M. A.; Klemas, V.; Daiber, F. C.; Roman, C. T.

    1984-01-01

    Net aerial primary productivity is the rate of storage of organic matter in above-ground plant issues exceeding the respiratory use by the plants during the period of measurement. It is pointed out that this plant tissue represents the fixed carbon available for transfer to and consumption by the heterotrophic organisms in a salt marsh or the estuary. One method of estimating annual net aerial primary productivity (NAPP) required multiple harvesting of the marsh vegetation. A rapid nondestructive remote sensing technique for estimating biomass and NAPP would, therefore, be a significant asset. The present investigation was designed to employ simple regression models, equating spectral radiance indices with Spartina alterniflora biomass to nondestructively estimate salt marsh biomass. The results of the study showed that the considered approach can be successfully used to estimate salt marsh biomass.

  12. Amylase Variation in the Salt Marsh Amphipod, GAMMARUS PALUSTRIS

    PubMed Central

    Borowsky, Richard; Borowsky, Betty; Milani, Haleh; Greenberg, Pietra

    1985-01-01

    There are two common alleles at the Amylase-2 locus in populations of Gammarus palustris, the salt marsh amphipod. Intensive sampling of individuals from two localities at Jamaica Bay revealed a consistent pattern of heterozygote deficiency.—Five possible sources of heterozygote deficiency were examined in this study. Four of them—selection against heterozygotes, null alleles at the locus, assortative mating for amylase genotype and inbreeding—are inconsistent with the evidence and are rejected. The fifth possibility, Wahlund effects due to genetic differentiation of the population, is tentatively accepted. Although there is no direct evidence for differentiation within this population, separate populations along the Eastern seaboard are highly differentiated in a nonclinal pattern. Furthermore, the Wahlund hypothesis is consistent with observations on differences in degree of deficiency exhibited among collections at Jamaica Bay.—Animals from this population exhibit feeding preferences correlated with genotype. Given the choice of two green algae, Enteromorpha or Ulva, the frequency of the slow allele among individuals choosing Enteromorpha was higher than among those choosing Ulva. This suggests that the animals assort themselves in the field into subpopulations with different allelic frequencies. This assortment could contribute to the maintenance of the polymorphism and to the observed heterozygote deficiency. We hypothesize that genotype influences behavior in this system through the action of enzyme on substrate, which determines the nature of the oligosaccharide pool liberated early in amylolysis. PMID:17246300

  13. Amylase Variation in the Salt Marsh Amphipod, GAMMARUS PALUSTRIS.

    PubMed

    Borowsky, R; Borowsky, B; Milani, H; Greenberg, P

    1985-10-01

    There are two common alleles at the Amylase-2 locus in populations of Gammarus palustris, the salt marsh amphipod. Intensive sampling of individuals from two localities at Jamaica Bay revealed a consistent pattern of heterozygote deficiency.-Five possible sources of heterozygote deficiency were examined in this study. Four of them-selection against heterozygotes, null alleles at the locus, assortative mating for amylase genotype and inbreeding-are inconsistent with the evidence and are rejected. The fifth possibility, Wahlund effects due to genetic differentiation of the population, is tentatively accepted. Although there is no direct evidence for differentiation within this population, separate populations along the Eastern seaboard are highly differentiated in a nonclinal pattern. Furthermore, the Wahlund hypothesis is consistent with observations on differences in degree of deficiency exhibited among collections at Jamaica Bay.-Animals from this population exhibit feeding preferences correlated with genotype. Given the choice of two green algae, Enteromorpha or Ulva, the frequency of the slow allele among individuals choosing Enteromorpha was higher than among those choosing Ulva. This suggests that the animals assort themselves in the field into subpopulations with different allelic frequencies. This assortment could contribute to the maintenance of the polymorphism and to the observed heterozygote deficiency. We hypothesize that genotype influences behavior in this system through the action of enzyme on substrate, which determines the nature of the oligosaccharide pool liberated early in amylolysis. PMID:17246300

  14. A comparison of fungal communities from four salt marsh plants using automated ribosomal intergenic spacer analysis (ARISA).

    PubMed

    Torzilli, Albert P; Sikaroodi, Masoumeh; Chalkley, David; Gillevet, Patrick M

    2006-01-01

    Fungal decomposers are important contributors to the detritus-based food webs of salt marsh ecosystems. Knowing the composition of salt marsh fungal communities is essential in understanding how detritus processing is affected by changes in community dynamics. Automated ribosomal intergenic spacer analysis (ARISA) was used to examine the composition of fungal communities associated with four temperate salt marsh plants, Spartina alterniflora (short and tall forms), Juncus roemerianus, Distichlis spicata and Sarcocornia perennis. Plant tissues were homogenized and subjected to a particle-filtration protocol that yielded 106 microm particulate fractions, which were used as a source of fungal isolates and fungal DNA. Genera identified from sporulating cultures demonstrated that the 106 microm particles from each host plant were reliable sources of fungal DNA for ARISA. Analysis of ARISA data by principal component analysis (PCA), principal coordinate analysis (PCO) and species diversity comparisons indicated that the fungal communities from the two grasses, S. alterniflora and D. spicata were more similar to each other than they were to the distinct communities associated with J. roemerianus and S. perennis. Principal component analysis also showed no consistent, seasonal pattern in the composition of these fungal communities. Comparisons of ARISA fingerprints from the different fungal communities and those from pure cultures of selected Spartina ascomycetes supported the host/substrate specificity observed for the fungal communities.

  15. Tidal events and salt-marsh structure influence black mangrove (Avicennia germinans) recruitment across an ecotone.

    PubMed

    Peterson, Jennifer M; Bell, Susan S

    2012-07-01

    Field experiments were conducted at a black mangrove-salt-marsh ecotone in southwest Florida (U.S.A.) to investigate retention of propagules of the black mangrove, Avicennia germinans, by salt-marsh plants as a mechanism of facilitation operating on recruitment success at landward boundaries. Buoyant A. germinans propagules are dispersed by tides, and stranding is required for establishment; therefore, processes that enable stranding should facilitate mangrove recruitment. We expected the physical structure of salt-marsh vegetation to define propagule retention capacity, and we predicted that salt-marsh plants with distinct growth forms would differentially retain propagules. Experimental monoculture plots (1 m2) of salt-marsh plants with different growth forms (Sporobolus virginicus [grass], Sesuvium portulacastrum [succulent forb], and Batis maritima [succulent scrub]) were created, and A. germinans propagules were emplaced into these plots and monitored over time. For comparison, propagules were also placed into natural polyculture plots (1 m2). Polyculture plots contained at least two of the salt-marsh plant taxa selected for monoculture treatments, and S. virginicus was always present within these polyculture plots. Natural polyculture plots retained 59.3% +/- 11.0% (mean +/- SE) of emplaced propagules. Monocultures varied in their propagule retention capacities with plots of S. virginicus retaining on average 65.7% +/- 11.5% of transplanted propagules compared to 7.2% +/- 1.8% by B. maritima and 5.0% +/- 1.9% by S. portulacastrum. Plots containing S. virginicus retained a significantly greater percentage of emplaced propagules relative to the two succulent salt-marsh taxa. Furthermore, propagule entrapment, across all treatments, was strongly correlated with salt-marsh structure (r2 = 0.6253, P = 0.00001), which was estimated using an indirect quantitative metric (lateral obstruction) calculated from digital images of plots. Overall, our findings imply that

  16. A Salt Marsh Erosion Model: Interplay Between Biotic and Physical Factors at the Seaward Edge

    NASA Astrophysics Data System (ADS)

    Weiner, M. E.; Gilbert, L. A.; Alves, C. L.; Poole, P. A.; Schleicher, S.

    2014-12-01

    We present a new model to monitor the cycle of erosion occurring on the seaward edge of salt marshes as sea level rises. In our model, a southern New England salt marsh edge is stable when the bank edge exhibits a normal slope, is fringed by the low-marsh grass Spartina alterniflora, and the ribbed mussel Guekensia demissa is abundant. As erosion proceeds, the seaward bank becomes vertical (Stage 1), then undercut (Stage 2), then slumped (Stage 3), and finally a detached island (Stage 4) to expose a new vertical bank. If erosion progresses relatively slowly, S. alterniflora will dominate and G. demissa will be abundant. We applied this model to four sites at the Barn Island Salt Marsh in southeastern Connecticut. The central headland of the heavily mosquito-ditched Headquarters Marsh appears to be the most rapidly retreating: from 2006 to 2014, the seaward bank advanced two erosional stages and lost 3 m horizontally. This headland is dominated by low-marsh S. alterniflora, with mid-marsh grasses Distichlis spicata and Spartina patens also present on the seaward edge. By comparison, the nearby seaward edge of Wequetequock Point has only S. alterniflora and bare patches with no mid-marsh species. Wequetequock Point also appears more stable, with about one quarter of the seaward bank on a normal slope and abundant mussels (mean 4,500 m-2; max 20,000 m-2). Repeat surveys since 2006 show mussel vacancy rate is related to the rate of erosion. Open holes appear in normal slope banks due to wave erosion of rocks and other material embedded in the exposed peat. Banks that remain in the same erosion stage for multiple years show increased mussel occupation of these holes. In contrast, rapidly eroding banks at Barn Island Marsh have very few mussels (<100 m-2) and are typically fringed by grasses other than S. alterniflora. Much of the Barn Island Marsh bank is eroding too rapidly for mussel settlement and growth and normal marsh grass succession. In addition to documenting

  17. Accretion rates in salt marshes in the Eastern Scheldt, South-west Netherlands

    NASA Astrophysics Data System (ADS)

    Oenema, Oene; DeLaune, Ronald D.

    1988-04-01

    Vertical accretion and sediment accumulation rates were determined from the distribution of 137Cs in sediment cores, from historic documents, and from artificial white-coloured tracer layers in salt marshes in the Eastern Scheldt. Salt marsh accretion is related to the steady rise of the mean high tide in the Eastern Scheldt during the last few decades. Mean accretion rates vary from 0·4-0·9 cm year -1 in the St Annaland marsh to 1·0-1·5 cm year -1 in the Rattekaai marsh. Sediment accumulation in accreting marshes exceed the loss of sediment, by retreat of the marsh cliffs, by a factor of 10-20. Short-term spatial and temporal variations in accretion rates are large. Spatial variations are associated with levee and backmarsh sites and the density of marsh vegetation. Temporal variations are mainly related to fluctuations in hydrodynamic conditions. The net vertical accretion rate of organic carbon is 0·4±0·1 kg m -2 year -1; approximately half this rate is associated with the current deposit, and the other half with net additions from the belowground root biomass. A simple model for the root biomass distribution of Spartina anglica with depth and the depth-dependent fossilization of root biomass in sediments of the Rattekaai marsh is presented.

  18. Intertidal salt marshes as an important source of inorganic carbon to the coastal ocean

    USGS Publications Warehouse

    Wang, Zhaohui Aleck; Kroeger, Kevin D.; Ganju, Neil K.; Gonneea, Meagan; Chu, Sophie N.

    2016-01-01

    Dynamic tidal export of dissolved inorganic carbon (DIC) to the coastal ocean from highly productive intertidal marshes and its effects on seawater carbonate chemistry are thoroughly evaluated. The study uses a comprehensive approach by combining tidal water sampling of CO2parameters across seasons, continuous in situ measurements of biogeochemically-relevant parameters and water fluxes, with high-resolution modeling in an intertidal salt marsh of the U.S. northeast region. Salt marshes can acidify and alkalize tidal water by injecting CO2 (DIC) and total alkalinity (TA). DIC and TA generation may also be decoupled due to differential effects of marsh aerobic and anaerobic respiration on DIC and TA. As marsh DIC is added to tidal water, the buffering capacity first decreases to a minimum and then increases quickly. Large additions of marsh DIC can result in higher buffering capacity in ebbing tide than incoming tide. Alkalization of tidal water, which mostly occurs in the summer due to anaerobic respiration, can further modify buffering capacity. Marsh exports of DIC and alkalinity may have complex implications for the future, more acidified ocean. Marsh DIC export exhibits high variability over tidal and seasonal cycles, which is modulated by both marsh DIC generation and by water fluxes. The marsh DIC export of 414 g C m−2 yr−1, based on high-resolution measurements and modeling, is more than twice the previous estimates. It is a major term in the marsh carbon budget and translates to one of the largest carbon fluxes along the U.S. East Coast.

  19. Interactions among Plant Species and Microorganisms in Salt Marsh Sediments

    PubMed Central

    Burke, David J.; Hamerlynck, Erik P.; Hahn, Dittmar

    2002-01-01

    The interactions among Spartina patens and sediment microbial populations and the interactions among Phragmites australis and sediment microbial populations were studied at monotypic sites in Piermont Marsh, a salt marsh of the Hudson River north of New York, N.Y., at key times during the growing season. Arbuscular mycorrhizal fungi (AMF) effectively colonized S. patens but not P. australis, and there were seasonal increases and decreases that coincided with plant growth and senescence (17 and 6% of the S. patens root length were colonized, respectively). In sediment samples from the Spartina site, the microbial community and specific bacterial populations were at least twice as large in terms of number and biomass as the microbial community and specific bacterial populations in sediment samples from the Phragmites site, and peak values occurred during reproduction. Members of the domain Bacteria, especially members of the α-, γ-, and δ-subdivisions of the Proteobacteria, were the most abundant organisms at both sites throughout the growing season. The populations were generally more dynamic in samples from the Spartina site than in samples from the Phragmites site. No differences between the two sites and no differences during the growing season were observed when restriction fragment length polymorphism analyses of nifH amplicons were performed in an attempt to detect shifts in the diversity of nitrogen-fixing bacteria. Differences were observed only in the patterns generated by PCR or reverse transcription-PCR for samples from the Spartina site, suggesting that there were differences in the overall and active populations of nitrogen-fixing bacteria. Regression analyses indicated that there was a positive interaction between members of the δ-subdivision of the Proteobacteria and root biomass but not between members of the δ-subdivision of the Proteobacteria and macroorganic matter at both sites. In samples from the Spartina site, there were indications that

  20. Role of salt-marsh erosion in barrier island evolution and deterioration in coastal Louisiana

    SciTech Connect

    Reed, D.J. )

    1989-09-01

    Barrier shoreline erosion in Louisiana reaches over 10 m/year, and island area decreased by 40% between 1880 and 1979. Salt-marsh erosion is an important factor in evolutionary barrier shoreline development and is presently contributing, both directly and indirectly, to the deterioration of Louisiana's barrier islands. The marshes originally developed as fresh marshes associated with regression of Mississippi River delta lobes. After abandonment, salinity gradually increased and natural habitat change occurred as subsidence of deltaic sediments and transgression of the coastline by marine processes proceeded. The marsh surface is subjected to relative sea level rise and unless there is sufficient sedimentation to maintain marsh elevation, erosional processes become dominant. Increased inundation of marsh vegetation stresses even halophytic vegetation and leads to plant death. Examination of variations in marsh topography over an area of approximately 1 ha. revealed marked variations in the frequency and duration of tidal inundation. Increased flooding of lower areas can be sufficient to cause plant death and the opening of marsh ponds. As small ponds expand and coalesce to form larger areas of open water, wave action becomes important in eroding pond banks and mobilizing sediment from the bed causing pond deepening. Fragmentation of the marsh by these subsidence-induced processes is part of the evolution of morphostratigraphic forms in the Mississippi deltaic plain from erosional headland with flanking barriers to barrier island arc.

  1. Implications of Vegetation Shifts on Greenhouse Gas Production in a Coastal Salt Marsh

    NASA Astrophysics Data System (ADS)

    Ouni, S.; Corbett, J. E.; Peteet, D. M.

    2014-12-01

    Methane production in salt marshes is understudied, although these anaerobic environments store vast amounts of carbon and may release large quantities as climate shifts. Studies show ranges of salt marsh methane emissions that vary widely from 0.4-160 g CH4 m-2 y-1. CH4 production in salt marshes is governed by several variables. Due to high sulfate concentrations in these environments, less CH4 is expected to form and escape from the subsurface. However, vascular plants allow greater amounts of CH4 escape from subsurface porewater and produce more labile organic carbon substrates, which support higher rates of microbial decomposition. Coastal salt marshes are also dominated by various vascular plant species both native and invasive which may allow for greater amounts of CH4 formation and escape than previously thought. To better understand CH4 dynamics in coastal salt marshes, pore water samples were collected from various depths in Piermont salt marsh, NY (40 ̊00' N, 73 ̊55'W), a tidal wetland that has been invaded in the last century by Phragmites australis. Dissolved organic carbon lability was measured, previously developed isotope-mass balance equations were utilized, and root depth and density were analyzed from several vegetation zones. Areas dominated by invasive Phragmites australis vegetation contain deeper and denser root zones and are expected to produce more subsurface methane and release more methane than areas dominated by native vegetation types. This study will allow us to identify zones more likely to contribute greenhouse gases to the atmosphere and increase knowledge of CH4 production and release in coastal salt marshes.

  2. Elevation dynamics in a restored versus a submerging salt marsh in Long Island Sound

    NASA Astrophysics Data System (ADS)

    Anisfeld, Shimon C.; Hill, Troy D.; Cahoon, Donald R.

    2016-03-01

    Accelerated sea-level rise (SLR) poses the threat of salt marsh submergence, especially in marshes that are relatively low-lying. At the same time, restoration efforts are producing new low-lying marshes, many of which are thriving and avoiding submergence. To understand the causes of these different fates, we studied two Long Island Sound marshes: one that is experiencing submergence and mudflat expansion, and one that is undergoing successful restoration. We examined sedimentation using a variety of methods, each of which captures different time periods and different aspects of marsh elevation change: surface-elevation tables, marker horizons, sediment cores, and sediment traps. We also studied marsh hydrology, productivity, respiration, nutrient content, and suspended sediment. We found that, despite the expansion of mudflat in the submerging marsh, the areas that remain vegetated have been gaining elevation at roughly the rate of SLR over the last 10 years. However, this elevation gain was only possible thanks to an increase in belowground volume, which may be a temporary response to waterlogging. In addition, accretion rates in the first half of the twentieth century were much lower than current rates, so century-scale accretion in the submerging marsh was lower than SLR. In contrast, at the restored marsh, accretion rates are now averaging about 10 mm yr-1 (several times the rate of SLR), much higher than before restoration. The main cause of the different trajectories at the two marshes appeared to be the availability of suspended sediment, which was much higher in the restored marsh. We considered and rejected alternative hypotheses, including differences in tidal flooding, plant productivity, and nutrient loading. In the submerging marsh, suspended and deposited sediment had relatively high organic content, which may be a useful indicator of sediment starvation.

  3. Elevation dynamics in a restored versus a submerging salt marsh in Long Island Sound

    USGS Publications Warehouse

    Anisfeld, Shimon C.; Hill, Troy D.; Cahoon, Donald R.

    2016-01-01

    Accelerated sea-level rise (SLR) poses the threat of salt marsh submergence, especially in marshes that are relatively low-lying. At the same time, restoration efforts are producing new low-lying marshes, many of which are thriving and avoiding submergence. To understand the causes of these different fates, we studied two Long Island Sound marshes: one that is experiencing submergence and mudflat expansion, and one that is undergoing successful restoration. We examined sedimentation using a variety of methods, each of which captures different time periods and different aspects of marsh elevation change: surface-elevation tables, marker horizons, sediment cores, and sediment traps. We also studied marsh hydrology, productivity, respiration, nutrient content, and suspended sediment. We found that, despite the expansion of mudflat in the submerging marsh, the areas that remain vegetated have been gaining elevation at roughly the rate of SLR over the last 10 years. However, this elevation gain was only possible thanks to an increase in belowground volume, which may be a temporary response to waterlogging. In addition, accretion rates in the first half of the twentieth century were much lower than current rates, so century-scale accretion in the submerging marsh was lower than SLR. In contrast, at the restored marsh, accretion rates are now averaging about 10 mm yr−1 (several times the rate of SLR), much higher than before restoration. The main cause of the different trajectories at the two marshes appeared to be the availability of suspended sediment, which was much higher in the restored marsh. We considered and rejected alternative hypotheses, including differences in tidal flooding, plant productivity, and nutrient loading. In the submerging marsh, suspended and deposited sediment had relatively high organic content, which may be a useful indicator of sediment starvation.

  4. Uranium, thorium and lead nuclides in a Delaware salt marsh sediment

    NASA Astrophysics Data System (ADS)

    Church, Thomas M.; Lord, Charles J.; Somayajulu, B. L. K.

    1981-09-01

    Natural isotopes of uranium (234, 238), thorium (232, 230) and lead (210) have been assayed in sediments from a lower Delaware salt marsh. Uranium is concentrated in the top sections of the core and decreases with depth (3 to 1 d min -1 g -1). A significant proportion of this uranium has been authigenically extracted from seawater as demonstrated by an excess ratio of 234U: 238U (1·03-1·14). Thorium (232) is rather constant (2·4-4·7 parts 10 -6 for all but one sample), while the concentration of 230Th is deficient with respect to its uranium parent. In contrast to the deep sea, the fixation of authigenic reduced uranium dominates over the scavenging of 230Th in these tidal sediments. Excess 210Pb shows an exponential decay over the length of the core, and when corrected for a correspondingly significant exponential decrease in organic carbon and salt yields a sedimentation rate of 0·47 cm year -1. Although this rate approximates the local apparent rate of sea-level rise, a lower limit for the rate of salt marsh accumulation, the actual rate is higher suggesting net filling and acccretion of salt marshes. The total integrated flux of 210Pb to this and other salt marsh surfaces in the eastern U.S. is calculated to more often exceed the reported local atmospheric flux. It appears that salt marshes may scavenge 210Pb, as other trace metals, from flooding waters.

  5. Salt Marsh Diking and Restoration: Biogeochemical Implications of Altered Wetland Hydrology.

    PubMed

    Portnoy

    1999-07-01

    / In salt marshes, most biomass plus large reserves of biologically important N, P, Fe, and S are sequestered below ground under saline, waterlogged, and anaerobic conditions. Thus, hydrologic alterations such as diking and ditch drainage that reduce salinity and increase peat aeration can cause radical changes in the composition of salt marsh soils.Experimental short-term desalination and drainage of salt marsh cores in greenhouse microcosms caused Spartina production to increase after one growing season, reflecting decreased salt stress and sulfide toxicity. However, production thereafter declined, likely due to pyrite oxidation and acidification in drained treatments and sulfide accumulation in waterlogged treatments.A survey of longer-term (decadal) effects of diking on peat composition of Cape Cod, Massachusetts, USA, marshes revealed acidification, Fe(II) mobilization, and decreased organic content in drained sites. Despite the aerobic decomposition of organic matter, abundant nutrients remained as sorbed NH4 and mineral-bound PO4. In diked, seasonally waterlogged sites, porewater alkalinity, sulfide, ammonium and orthophosphate were much lower, and organic solids higher, than in adjacent natural marsh.Seawater was added to cores from diked marshes to study the effects of tidal restoration. Salination of the drained peat increased porewater pH, alkalinity, ammonium, orthophosphate, Fe, and Al; copious ammonium N, and Fe(II) for sulfide precipitation favored Spartina growth. Salination of diked-waterlogged peat increased sulfate reduction and caused 6-8 cm of sediment subsidence. The resulting increase in porewater sulfides and waterlogging decreased vigor of transplanted Spartina alterniflora. Results indicate that seawater restoration should proceed cautiously to avoid nutrient loading of surface waters in drained sites or sulfide toxicity in diked-waterlogged marshes.KEY WORDS: Salt marsh; Diking; Biogeochemical cycling; Restoration; Massachusettshttp

  6. Population Dynamics and Community Composition of Ammonia Oxidizers in Salt Marshes after the Deepwater Horizon Oil Spill.

    PubMed

    Bernhard, Anne E; Sheffer, Roberta; Giblin, Anne E; Marton, John M; Roberts, Brian J

    2016-01-01

    The recent oil spill in the Gulf of Mexico had significant effects on microbial communities in the Gulf, but impacts on nitrifying communities in adjacent salt marshes have not been investigated. We studied persistent effects of oil on ammonia-oxidizing archaeal (AOA) and bacterial (AOB) communities and their relationship to nitrification rates and soil properties in Louisiana marshes impacted by the Deepwater Horizon oil spill. Soils were collected at oiled and unoiled sites from Louisiana coastal marshes in July 2012, 2 years after the spill, and analyzed for community differences based on ammonia monooxygenase genes (amoA). Terminal Restriction Fragment Polymorphism and DNA sequence analyses revealed significantly different AOA and AOB communities between the three regions, but few differences were found between oiled and unoiled sites. Community composition of nitrifiers was best explained by differences in soil moisture and nitrogen content. Despite the lack of significant oil effects on overall community composition, we identified differences in correlations of individual populations with potential nitrification rates between oiled and unoiled sites that help explain previously published correlation patterns. Our results suggest that exposure to oil, even 2 years post-spill, led to subtle changes in population dynamics. How, or if, these changes may impact ecosystem function in the marshes, however, remains uncertain. PMID:27375576

  7. Population Dynamics and Community Composition of Ammonia Oxidizers in Salt Marshes after the Deepwater Horizon Oil Spill.

    PubMed

    Bernhard, Anne E; Sheffer, Roberta; Giblin, Anne E; Marton, John M; Roberts, Brian J

    2016-01-01

    The recent oil spill in the Gulf of Mexico had significant effects on microbial communities in the Gulf, but impacts on nitrifying communities in adjacent salt marshes have not been investigated. We studied persistent effects of oil on ammonia-oxidizing archaeal (AOA) and bacterial (AOB) communities and their relationship to nitrification rates and soil properties in Louisiana marshes impacted by the Deepwater Horizon oil spill. Soils were collected at oiled and unoiled sites from Louisiana coastal marshes in July 2012, 2 years after the spill, and analyzed for community differences based on ammonia monooxygenase genes (amoA). Terminal Restriction Fragment Polymorphism and DNA sequence analyses revealed significantly different AOA and AOB communities between the three regions, but few differences were found between oiled and unoiled sites. Community composition of nitrifiers was best explained by differences in soil moisture and nitrogen content. Despite the lack of significant oil effects on overall community composition, we identified differences in correlations of individual populations with potential nitrification rates between oiled and unoiled sites that help explain previously published correlation patterns. Our results suggest that exposure to oil, even 2 years post-spill, led to subtle changes in population dynamics. How, or if, these changes may impact ecosystem function in the marshes, however, remains uncertain.

  8. Population Dynamics and Community Composition of Ammonia Oxidizers in Salt Marshes after the Deepwater Horizon Oil Spill

    PubMed Central

    Bernhard, Anne E.; Sheffer, Roberta; Giblin, Anne E.; Marton, John M.; Roberts, Brian J.

    2016-01-01

    The recent oil spill in the Gulf of Mexico had significant effects on microbial communities in the Gulf, but impacts on nitrifying communities in adjacent salt marshes have not been investigated. We studied persistent effects of oil on ammonia-oxidizing archaeal (AOA) and bacterial (AOB) communities and their relationship to nitrification rates and soil properties in Louisiana marshes impacted by the Deepwater Horizon oil spill. Soils were collected at oiled and unoiled sites from Louisiana coastal marshes in July 2012, 2 years after the spill, and analyzed for community differences based on ammonia monooxygenase genes (amoA). Terminal Restriction Fragment Polymorphism and DNA sequence analyses revealed significantly different AOA and AOB communities between the three regions, but few differences were found between oiled and unoiled sites. Community composition of nitrifiers was best explained by differences in soil moisture and nitrogen content. Despite the lack of significant oil effects on overall community composition, we identified differences in correlations of individual populations with potential nitrification rates between oiled and unoiled sites that help explain previously published correlation patterns. Our results suggest that exposure to oil, even 2 years post-spill, led to subtle changes in population dynamics. How, or if, these changes may impact ecosystem function in the marshes, however, remains uncertain. PMID:27375576

  9. Hydrogeochemical zonation in intertidal salt marsh sediments: evidence of positive plant-soil feedback?

    NASA Astrophysics Data System (ADS)

    Moffett, K. B.; Dittmar, J.; Seyfferth, A.; Fendorf, S.; Gorelick, S.

    2012-12-01

    Surface and subsurface environments are linked by the biogeochemical activity in near-surface sediment and by the hydrological fluxes that mobilize its reagents and products. A particularly dynamic and interesting setting to study near-surface hydrogeochemistry is the intertidal zone. Here, the very strong tidal hydraulic forcing is often thought to dominate water and solute transport. However, we demonstrated the importance of two additional subsurface drivers: groundwater flow and plant root water uptake. A high-resolution, coupled surface water-groundwater model of an intertidal salt marsh in San Francisco Bay, CA showed that these three drivers vary over different spatial scales: tidal flooding varies over 10's of meters; groundwater flow varies over meters, particularly within channel banks; and plant root water uptake varies in 3D at the sub-meter scale. Expanding on this third driver, we investigated whether the spatial variations in soil-water-plant hydraulic interactions that occur due to vegetation zonation also cause distinct geochemical zonation in salt marsh sediment pore waters. The existence of such geochemical zonation was verified and mapped by detailed field observations of the chemical composition of sediments, pore waters, surface waters, and vegetation. The field data and the coupled hydrologic model were then further analyzed to evaluate potential causal mechanisms for the geochemical zonation, including testing the hypothesis that the vegetation affects pore water geochemistry via a positive feedback beneficial to itself. If further supported by future studies, this geochemical feedback may complement known physical ecosystem engineering mechanisms to help stabilize and organize intertidal wetlands.

  10. Further data on elevational changes and water circulation in a Cumbrian salt marsh

    NASA Astrophysics Data System (ADS)

    Carr, A. P.; Blackley, M. W. L.

    1987-01-01

    A further year's elevational data has been obtained from creek profiles at a salt marsh site on the north side of the Esk estuary, Cumbria. Comparative sections were taken on the south shore. The 'seasonality' found previously on the north shore and again recorded was less well defined at the southern site probably reflecting smaller proportions of clay minerals and greater exposure. Porewater pressure data from an upper salt marsh location showed a similar situation to that obtained previously from a lower marsh site, i.e. when tides overtopped the marsh surface the uppermost transducers responded first. Neap tides were only registered by the lowest transducers (or not at all) with upper sensors showing draining except during periods of precipitation. Only low quantities of artificial radionuclides were measured but their distribution appears to reflect the proportions of fine sediment present and the water circulation pattern.

  11. Methane Emissions from a Hydrologically Altered Region of the Sprague River Salt Marsh, Phippsburg, ME

    NASA Astrophysics Data System (ADS)

    Cohen-Kaplan, Dana; Johnson, Beverly; Dostie, Phil; Carey, Joanna

    2016-04-01

    Humans have been altering salt marshes for 200 years, by ditching, or excavating channels to drain pools to reduce mosquito habitat and to make the marsh platform suitable for agriculture. The presence of these ditches has had a negative impact on the marsh hydrology. The Sprague River Salt Marsh, located in Phippsburg, ME, has been ditched for centuries. In 2002, the United States Fish and Wildlife Service installed several ditch-plugs in the marsh in and attempt to restore pool habitat and marsh hydrology. This study seeks to examine the effects of one ditch-plug in particular, and the impact it has had on methane emissions, soil salinity, and soil carbon densities. Three sites above and three sites below the ditch-plug were analyzed in these three areas. Methane emissions were slightly elevated above the ditch-plug relative to below the ditch-plug, with average fluxes of 12.9 +/- 4.83 umol/hr/m2 and 3.5 +/- 0.66 umol/hr/m^2, respectively. Soil salinities were higher above the ditch-plug, and soil carbon densities were higher below the ditch-plug. These results suggest that the hydrologic regime of the study area has been degraded, resulting in methane emissions, interrupted accretion, decreased marsh self-maintenance processes, stagnation and saturation of seawater in the pores of the sediment. Though salt marshes are generally considered effective carbon sinks, methane emissions may play a role on hydrologically altered marshes in terms of their net contribution to greenhouse gas sequestration.

  12. Classification mapping and species identification of salt marshes based on a short-time interval NDVI time-series from HJ-1 optical imagery

    NASA Astrophysics Data System (ADS)

    Sun, Chao; Liu, Yongxue; Zhao, Saishuai; Zhou, Minxi; Yang, Yuhao; Li, Feixue

    2016-03-01

    Salt marshes are seen as the most dynamic and valuable ecosystems in coastal zones, and in these areas, it is crucial to obtain accurate remote sensing information on the spatial distributions of species over time. However, discriminating various types of salt marsh is rather difficult because of their strong spectral similarities. Previous salt marsh mapping studies have focused mainly on high spatial and spectral (i.e., hyperspectral) resolution images combined with auxiliary information; however, the results are often limited to small regions. With a high temporal and moderate spatial resolution, the Chinese HuanJing-1 (HJ-1) satellite optical imagery can be used not only to monitor phenological changes of salt marsh vegetation over short-time intervals, but also to obtain coverage of large areas. Here, we apply HJ-1 satellite imagery to the middle coast of Jiangsu in east China to monitor changes in saltmarsh vegetation cover. First, we constructed a monthly NDVI time-series to classify various types of salt marsh and then we tested the possibility of using compressed time-series continuously, to broaden the applicability of this particular approach. Our principal findings are as follows: (1) the overall accuracy of salt marsh mapping based on the monthly NDVI time-series was 90.3%, which was ∼16.0% higher than the single-phase classification strategy; (2) a compressed time-series, including NDVI from six key months (April, June-September, and November), demonstrated very little reduction (2.3%) in overall accuracy but led to obvious improvements in unstable regions; and (3) a simple rule for Spartina alterniflora identification was established using a scene solely from November, which may provide an effective way for regularly monitoring its distribution.

  13. Reading the signatures of biologic-geomorphic feedbacks in salt-marsh landscapes

    NASA Astrophysics Data System (ADS)

    D'Alpaos, Andrea; Marani, Marco

    2016-07-01

    How do interacting physical and biological processes control the form and evolution of salt-marsh landscapes? Salt marshes are shaped by the erosion, transport and deposition of sediment, all of which are mediated by vegetation. In addition, vegetation plays a key role in deposition of organic material within marsh sediments. The influence of biota on salt-marsh landscapes is indeed well established. However, a fascinating and relevant question is whether one can identify the signatures of the underlying and intertwined physical and biological processes in marsh landscapes, and indeed infer from them the dynamic behavior of these coupled physical and biological systems. Can one detect landscape features that would not have emerged in the absence of interactions and feedbacks between physical and biological processes? Here we use field evidence and a two-dimensional biomorphodynamic model to show that the interplay between physical and biological processes generates striking biological and morphological patterns. One such pattern, vegetation zonation, consists of a mosaic of vegetation patches, of approximately uniform composition, displaying sharp transitions in the presence of extremely small topographic gradients. The model describes the mutual interaction and adjustment between tidal flows, sediment transport, morphology, and vegetation distribution, thus allowing us to study the biomorphodynamic evolution of salt-marsh platforms. A number of different scenarios were modelled to analyze the changes induced in bio-geomorphic patterns by varying environmental forcings, such as the rate of relative sea level rise (RSLR) andsediment supply (SS), and by plant species with different characteristics. Model results show how marsh responses to changes in forcings are highly spatially dependent: while changes in SS most directly affect marsh areas closest to the channels, changes in the rate of RSLR affect the marsh platform as a whole. Organic sediment accretion is very

  14. N2O Flux from Salt Marshes in Estuaries along the Gulf of St. Lawrence

    NASA Astrophysics Data System (ADS)

    Roughan, B.; Kellman, L. M.; Chmura, G. L.

    2013-12-01

    Wetlands are widely noted as filters for nutrient-laden waters. However, soils in tidal salt marshes emit nitrous oxide (N2O) when experimentally fertilized, which suggests that improved water quality comes at the expense of increased atmospheric concentrations of this potent greenhouse gas. Here we report on N2O emissions from four salt marshes located in estuaries along the Gulf of St. Lawrence. Our control site is located in a National Park on the coast of New Brunswick, which is in a region of low population density and limited agriculture, whereas the other estuaries have watersheds characterized by intensive agriculture activities on Prince Edward Island (PEI). N2O gas was collected during low tide, using opaque, static-chambers (17 L, 25 cm diameter) placed over marsh vegetation in the Spartina patens-dominated high marsh, which is typical of salt marshes along the northwest Atlantic coast, from New York north to Atlantic Canada. Preliminary analysis of gas samples collected in June revealed that the average N2O flux from the marshes located in agriculturally intensive watersheds (6.17 ×1.82 μg N2O m-2 hr-1) was significantly higher than the flux from the control marsh, which was negligible (-2.63 ×2.22 μg N2O m-2 hr-1). Assuming this elevated N2O flux is typical of the growing season (May-October), these marshes emit an average of 27 ×8 mg N2O m-2 yr-1 (or 8 g CO2e m-2 yr-1), 8.4% of the annual soil C accumulation rate reported for PEI. These results suggest that unintentional N fertilization of salt marshes located in agriculturally dominated watersheds may be fueling significant anthropogenic greenhouse gas emissions in some marshes. Further work during the 2013 growing season will provide insight into the environmental variables that affect the flux of N2O from these tidal salt marshes.

  15. Precision Monitoring of Water Level in a Salt Marsh with Low Cost Tilt Loggers

    NASA Astrophysics Data System (ADS)

    Sheremet, Vitalii A.; Mora, Jordan W.

    2016-04-01

    Several salt pannes and pools in the Sage Lot tidal marsh of Waquoit Bay system, MA were instrumented with newly developed Arm-and-Float water level gauges (utilizing accelerometer tilt logger) permitting to record water level fluctuations with accuracy of 1 mm and submillimeter resolution. The methodology of the instrument calibration, deployment, and elevation control are described. The instrument performance was evaluated. Several month long deployments allowed us to analyze the marsh flooding and draining processes, study differences among the salt pannes. The open channel flow flooding-draining mechanism and slower seepage were distinguished. From the drain curve the seepage rate can be quantified. The seepage rate remains approximately constant for all flooding draining episodes, but varies from panne to panne depending on bottom type and location. Seasonal differences due to the growth of vegetation are also recorded. The analysis of rain events allows us to estimate the catch area of subbasins in the marsh. The implication for marsh ecology and marsh accretion are discussed. The gradual sea level rise coupled with monthly tidal datum variability and storm surges result in migration and development of a salt marsh. The newly developed low cost instrumentation allows us to record and analyze these changes and may provide guidance for the ecological management.

  16. Assessing the sedimentation deficit problem in Louisiana's coastal salt marshes

    SciTech Connect

    Reed, D.J.

    1990-09-01

    The imbalance between relative sea-level rise and vertical marsh accretion is frequently cited as a major factor in the problem of wetland loss in coastal Louisiana. Relative sea-level rise rates are high, compared to the rest of the Gulf coast, owing to subsidence of Holocene Mississippi deltaic plain sediments, and although marsh accretion rates are also high, in comparison with other coastal areas of the US, they are usually insufficient to maintain the relative elevation of the marsh surface. This situation is commonly referred to as a sedimentation deficit. One of the problems with evaluating the magnitude of the sedimentation deficit problem in Louisiana, and its spatial variation, is that measurements of subsidence and marsh accretion or sedimentation are rarely made on similar time scales. Subsidence affecting the marsh surface is composed of a number of factors, including compaction of recently deposited sediments, regional downwarping, and diagenesis of underlying Pleistocene and earlier sediments. The total effect of these factors, in combination with eustatic sea-level rise, is frequently obtained from tide gauge measurements over the last 50 years or so. Subsidence is also measured by dating sedimentary horizons of known depth that characterize surface environments. Carbon-14 is a common tool for this type of study and subsidence is then averaged over periods of up to several thousand years. In comparison, marsh accretion or sediment deposition can be measured over periods from several hundred years, using Lead-210 dating, to several days, using marsh surface sediment traps. The many techniques available for measuring the sedimentary status of the marsh surface can provide a variety of information concerning the processes responsible for sediment deposition and vertical accretion.

  17. Relationships between watershed emergy flow and coastal New England salt marsh structure, function, and condition.

    PubMed

    Brandt-Williams, Sherry; Wigand, Cathleen; Campbell, Daniel E

    2013-02-01

    This study evaluated the link between watershed activities and salt marsh structure, function, and condition using spatial emergy flow density (areal empower density) in the watershed and field data from 10 tidal salt marshes in Narragansett Bay, RI, USA. The field-collected data were obtained during several years of vegetation, invertebrate, soil, and water quality sampling. The use of emergy as an accounting mechanism allowed disparate factors (e.g., the amount of building construction and the consumption of electricity) to be combined into a single landscape index while retaining a uniform quantitative definition of the intensity of landscape development. It expanded upon typical land use percentage studies by weighting each category for the intensity of development. At the RI salt marsh sites, an impact index (watershed emergy flow normalized for marsh area) showed significant correlations with mudflat infauna species richness, mussel density, plant species richness, the extent and density of dominant plant species, and denitrification potential within the high salt marsh. Over the 4-year period examined, a loading index (watershed emergy flow normalized for watershed area) showed significant correlations with nitrite and nitrate concentrations, as well as with the nitrogen to phosphorus ratios in stream discharge into the marshes. Both the emergy impact and loading indices were significantly correlated with a salt marsh condition index derived from intensive field-based assessments. Comparison of the emergy indices to calculated nitrogen loading estimates for each watershed also produced significant positive correlations. These results suggest that watershed emergy flow is a robust index of human disturbance and a potential tool for rapid assessment of coastal wetland condition.

  18. Radionuclides transfer into halophytes growing in tidal salt marshes from the Southwest of Spain.

    PubMed

    Luque, Carlos J; Vaca, Federico; García-Trapote, Ana; Hierro, Almudena; Bolívar, Juan P; Castellanos, Eloy M

    2015-12-01

    Estuaries are sinks of materials and substances which are released directly into them or transported from rivers that drain the basin. It is usual to find high organic matter loads and fine particles in the sediments. We analyzed radionuclide concentrations ((210)Po, (230)Th, (232)Th, (234)U, (238)U, (226)Ra, (228)Th, (228)Ra, (40)K) in sediments and three different organs (roots, stems and leaves) of three species of halophytes plants (Spartina maritima, Spartina densiflora and Sarcocornia perennis). The study was carried out in two tidal salt marshes, one polluted by U-series radionuclides and another nearby that was unpolluted and was used as a control (or reference) area. The Tinto River salt marsh shows high levels of U-series radionuclides coming from mining and industrial discharges. On the contrary, the unperturbed Piedras River salt marsh is located about 25 km from the Tinto marsh, and shows little presence of contaminants and radionuclides. The results of this work have shown that natural radionuclide concentrations (specially the U-isotopes) in the Tinto salt marsh sediments are one order of magnitude higher than those in the Piedras marsh. These radionuclide enhancements are reflected in the different organs of the plants, which have similar concentration increases as the sediments where they have grown. Finally, the transfer factor (TF) of the most polluted radionuclides (U-isotopes and (210)Po) in the Tinto area are one order of magnitude higher than in the Piedras area, indicating that the fraction of each radionuclide in the sediment originating from the pollution is more available for the plants than the indigenous fraction. This means that the plants of the salt marshes are unhelpful as bioindicators or for the phytoremediation of radionuclides. PMID:26334596

  19. Radionuclides transfer into halophytes growing in tidal salt marshes from the Southwest of Spain.

    PubMed

    Luque, Carlos J; Vaca, Federico; García-Trapote, Ana; Hierro, Almudena; Bolívar, Juan P; Castellanos, Eloy M

    2015-12-01

    Estuaries are sinks of materials and substances which are released directly into them or transported from rivers that drain the basin. It is usual to find high organic matter loads and fine particles in the sediments. We analyzed radionuclide concentrations ((210)Po, (230)Th, (232)Th, (234)U, (238)U, (226)Ra, (228)Th, (228)Ra, (40)K) in sediments and three different organs (roots, stems and leaves) of three species of halophytes plants (Spartina maritima, Spartina densiflora and Sarcocornia perennis). The study was carried out in two tidal salt marshes, one polluted by U-series radionuclides and another nearby that was unpolluted and was used as a control (or reference) area. The Tinto River salt marsh shows high levels of U-series radionuclides coming from mining and industrial discharges. On the contrary, the unperturbed Piedras River salt marsh is located about 25 km from the Tinto marsh, and shows little presence of contaminants and radionuclides. The results of this work have shown that natural radionuclide concentrations (specially the U-isotopes) in the Tinto salt marsh sediments are one order of magnitude higher than those in the Piedras marsh. These radionuclide enhancements are reflected in the different organs of the plants, which have similar concentration increases as the sediments where they have grown. Finally, the transfer factor (TF) of the most polluted radionuclides (U-isotopes and (210)Po) in the Tinto area are one order of magnitude higher than in the Piedras area, indicating that the fraction of each radionuclide in the sediment originating from the pollution is more available for the plants than the indigenous fraction. This means that the plants of the salt marshes are unhelpful as bioindicators or for the phytoremediation of radionuclides.

  20. Middle to Late Holocene Fluctuations of C3 and C4 Vegetation in a Northern New England Salt Marsh, Sprague Marsh, Phippsburg Maine

    SciTech Connect

    Johnson, B J; Moore, K A; Lehmann, C; Bohlen, C; Brown, T A

    2006-05-26

    A 3.1 meter sediment core was analyzed for stable carbon isotope composition of organic matter and higher plant leaf wax (HPLW) lipid biomarkers to determine Holocene shifts in C{sub 3} (higher high marsh) and C{sub 4} (low and/or high marsh) plant deposition at the Sprague River Salt Marsh, Phippsburg, Maine. The carbon isotope composition of the bulk sediment and the HPLW parallel each other throughout most of the core, suggesting that terrestrial plants are an important source of organic matter to the sediments, and diagenetic alteration of the bulk sediments is minimal. The current salt marsh began to form 2500 cal yr BP. Low and/or high C{sub 4} marsh plants dominated deposition at 2000 cal yr BP, 700 cal yr BP, and for the last 200 cal yr BP. Expansion of higher high marsh C{sub 3} plants occurred at 1300 and 600 cal yr BP. These major vegetation shifts result from a combination of changes in relative sea-level rise and sediment accumulation rates. Average annual carbon sequestration rates for the last 2500 years approximate 40 g C yr{sup -1} m{sup -2}, and are in strong agreement with other values published for the Gulf of Maine. Given that Maine salt marshes cover an area of {approx}79 km{sup 2}, they represent an important component of the terrestrial carbon sink. More detailed isotopic and age records from a network of sediment cores at Sprague Marsh are needed to truly evaluate the long term changes in salt marsh plant communities and the impact of more recent human activity, including global warming, on salt marsh vegetation.

  1. Cable bacteria associated with long-distance electron transport in New England salt marsh sediment.

    PubMed

    Larsen, Steffen; Nielsen, Lars Peter; Schramm, Andreas

    2015-04-01

    Filamentous Desulfobulbaceae have been proposed as 'cable bacteria', which electrically couple sulfide oxidation and oxygen reduction in marine sediment and thereby create a centimetre-deep suboxic zone. We incubated New England salt marsh sediment and found long-distance electron transport across 6 mm and 16S rRNA genes identical to those of previously observed cable bacteria in Aarhus Bay sediment incubations. Cable bacteria density in sediment cores was quantified by fluorescence in situ hybridization. In contrast to the coastal, subtidal sediments with short-termed blooms of cable bacteria based on rapidly depleted iron sulfide pools, the salt marsh cable community was based on ongoing sulfate reduction and therefore probably more persistent. Previously observed seasonal correlation between Desulfobulbaceae dominance and extensive reduced sulfur oxidation in salt marshes suggest that cable bacteria at times may have an important role in situ.

  2. Enrichment and Association of Bacteria and Particulates in Salt Marsh Surface Water

    PubMed Central

    Harvey, R. W.; Young, L. Y.

    1980-01-01

    Elevated counts of bacteria were found during outgoing tides in surface microlayers (∼300 μm) of Sippewissett salt marsh, Falmouth, Massachusetts, and Palo Alto salt marsh, Palo Alto, California. At both sampling sites, the degrees by which bacteria were concentrated into the surface microlayer were linearly dependent upon surface concentration of particulate material. A significant percentage of bacteria in the microlayer were found to be attached to particulate material, while bacterial populations in the subsurface water were largely planktonic. Proportions of the bacterial populations which could be grown on seawater nutrient agar were also greater in the microlayer than in the subsurface waters and were positively correlated with the fraction of bacteria attached to particulate matter. Data from these studies suggest that particulates in the microlayer waters of the salt marsh influenced the observed increase in both the readily grown and the total numbers of bacteria. PMID:16345554

  3. Size and species diversity of zooplankton communities in fluctuating Mediterranean salt marshes

    NASA Astrophysics Data System (ADS)

    Brucet, Sandra; Boix, Dani; López-Flores, Rocío; Badosa, Anna; Quintana, Xavier D.

    2006-04-01

    Differences in size and species diversity were analysed in a zooplankton community of a Mediterranean salt marsh (Empordà wetlands, NE Iberian Peninsula), where the dominance of a single species was frequent. In the permanent salt marsh, species diversity and size diversity had similar patterns along zooplankton succession. In the temporary salt marsh species diversity was high after flooding and diminished once water inputs ceased. As species diversity declined size diversity increased. Eventually, one species of calanoid dominated the zooplankton community. The high size diversity in situations of calanoid dominance was possibly due to the co-occurrence of different developmental stages, each of which have different diets. Size diversity would thus indicate trophic niche segregation among different sizes. The combined use of species and size diversity values allows the identification of the successional phases.

  4. Evolving Landscapes: the Effect of Genetic Variation on Salt Marsh Erosion

    NASA Astrophysics Data System (ADS)

    Bernik, B. M.; Blum, M. J.

    2014-12-01

    Ecogeomorphic studies have demonstrated that biota can exert influence over geomorphic processes, such as sediment transport, which in turn have biotic consequences and generate complex feedbacks. However, little attention has been paid to the potential for feedback to arise from evolutionary processes as population genetic composition changes in response to changing physical landscapes. In coastal ecosystems experiencing land loss, for example, shoreline erosion entails reduced plant survival and reproduction, and thereby represents a geomorphic response with inherent consequences for evolutionary fitness. To get at this topic, we examined the effect of genetic variation in the saltmarsh grass Spartina alterniflora, a renowned ecosystem engineer, on rates of shoreline erosion. Field transplantation studies and controlled greenhouse experiments were conducted to compare different genotypes from both wild and cultivated populations. Plant traits, soil properties, accretion/subsidence, and rates of land loss were measured. We found significant differences in rates of erosion between field plots occupied by different genotypes. Differences in erosion corresponded to variation in soil properties including critical shear stress and subsidence. Plant traits that differed across genotypes included belowground biomass, root tensile strength, and C:N ratios. Our results demonstrate the importance of genetic variation to salt marsh functioning, elucidating the relationship between evolutionary processes and ecogeomorphic dynamics in these systems. Because evolutionary processes can occur on ecological timescales, the direction and strength of ecogeomorphic feedbacks may be more dynamic than previously accounted for.

  5. Relating salt marsh pore water geochemistry patterns to vegetation zones and hydrologic influences

    NASA Astrophysics Data System (ADS)

    Moffett, Kevan B.; Gorelick, Steven M.

    2016-03-01

    Physical, chemical, and biological factors influence vegetation zonation in salt marshes and other wetlands, but connections among these factors could be better understood. If salt marsh vegetation and marsh pore water geochemistry coorganize, e.g., via continuous plant water uptake and persistently unsaturated sediments controlling vegetation zone-specific pore water geochemistry, this could complement known physical mechanisms of marsh self-organization. A high-resolution survey of pore water geochemistry was conducted among five salt marsh vegetation zones at the same intertidal elevation. Sampling transects were arrayed both parallel and perpendicular to tidal channels. Pore water geochemistry patterns were both horizontally differentiated, corresponding to vegetation zonation, and vertically differentiated, relating to root influences. The geochemical patterns across the site were less broadly related to marsh hydrology than to vegetation zonation. Mechanisms contributing to geochemical differentiation included: root-induced oxidation and nutrient (P) depletion, surface and creek-bank sediment flushing by rainfall or tides, evapotranspiration creating aerated pore space for partial sediment flushing in some areas while persistently saturated conditions hindered pore water renewal in others, and evapoconcentration of pore water solutes overall. The concentrated pore waters draining to the tidal creeks accounted for 41% of ebb tide solutes (median of 14 elements), including being a potentially toxic source of Ni but a slight sink for Zn, at least during the short, winter study period in southern San Francisco Bay. Heterogeneous vegetation effects on pore water geochemistry are not only significant locally within the marsh but may broadly influence marsh-estuary solute exchange and ecology.

  6. Wetland loss patterns and inundation-productivity relationships prognosticate widespread salt marsh loss for southern New England

    EPA Science Inventory

    Tidal salt marsh is a key defense against, yet is especially vulnerable to, the effects of accelerated sea level rise. To determine whether salt marshes in southern New England will be stable given increasing inundation over the coming decades, we examined current loss patterns, ...

  7. Does livestock grazing affect sediment deposition and accretion rates in salt marshes?

    NASA Astrophysics Data System (ADS)

    Nolte, Stefanie; Müller, Frauke; Schuerch, Mark; Wanner, Antonia; Esselink, Peter; Bakker, Jan P.; Jensen, Kai

    2013-12-01

    Accretion rates, defined as the vertical growth of salt marshes measured in mm per year, may be influenced by grazing livestock in two ways: directly, by increasing soil compaction through trampling, and indirectly, by reducing aboveground biomass and thus decreasing sediment deposition rates measured in g/m² per year. Although accretion rates and the resulting surface elevation change largely determine the resilience of salt marshes to sea-level rise (SLR), the effect of livestock grazing on accretion rates has been little studied. Therefore, this study aimed to investigate the effect of livestock grazing on salt-marsh accretion rates. We hypothesise that accretion will be lower in grazed compared to ungrazed salt marshes. In four study sites along the mainland coast of the Wadden Sea (in the south-eastern North Sea), accretion rates, sediment deposition rates, and soil compaction of grazed and ungrazed marshes were analysed using the 137Cs radionuclide dating method. Accretion rates were on average 11.6 mm yr-1 during recent decades and thus higher than current and projected rates of SLR. Neither accretion nor sediment deposition rates were significantly different between grazing treatments. Meanwhile, soil compaction was clearly affected by grazing with significantly higher dry bulk density on grazed compared to ungrazed parts. Based on these results, we conclude that other factors influence whether grazing has an effect on accretion and sediment deposition rates and that the effect of grazing on marsh growth does not follow a direct causal chain. It may have a great importance when interacting with other biotic and abiotic processes on the marsh.

  8. Lithium in the brines of Fish Lake Valley and Columbus Salt Marsh, Nevada

    USGS Publications Warehouse

    Smith, C.L.; Meier, Allen L.; Downey, H.D.

    1977-01-01

    Analyses of waters-from springs in Nevada have led to the identification of an area containing anomalous amounts of lithium northwest of the Clayton Valley-area. Fish Lake Valley and Columbus Salt Marsh contain waters having, relatively high lithium and potassium concentrations. At least a part of these waters is probably derived from the leaching of Tertiary rocks containing saline minerals. The high-lithium waters at Columbus Salt Marsh could be derived not only by the leaching of rocks with a high soluble lithium ands, potassium content but also by subsurface outflow from Fish Lake Valley.

  9. Modern salt-marsh and tidal-flat foraminifera from Sitkinak and Simeonof Islands, southwestern Alaska

    USGS Publications Warehouse

    Kemp, Andrew C.; Engelhart, Simon E.; Culver, Stephen J.; Nelson, Alan R.; Briggs, Richard W.; Haeussler, Peter J.

    2013-01-01

    We describe the modern distribution of salt-marsh and tidal-flat foraminifera from Sitkinak Island (Trinity Islands) and Simeonof Island (Shumagin Islands), Alaska, to begin development of a dataset for later use in reconstructing relative sea-level changes caused by great earthquakes along the Alaska-Aleutian subduction zone. Dead foraminifera were enumerated from a total of 58 surface-sediment samples collected along three intertidal transects around a coastal lagoon on Sitkinak Island and two intertidal transects on Simeonof Island. Two distinctive assemblages of salt-marsh foraminifera were recognized on Sitkinak Island. Miliammina fusca dominated low-marsh settings and Balticammina pseudomacrescens dominated the high marsh. These two species make up >98% of individuals. On Simeonof Island, 93% of individuals in high-marsh settings above mean high water were B. pseudomacrescens. The tidal flat on Simeonof Island was dominated by Cibicides lobatulus (60% of individuals), but the lower limit of this species is subtidal and was not sampled. These results indicate that uplift or subsidence caused by repeated earthquakes along the Alaska-Aleutian subduction zone could be reconstructed in coastal sediments using alternating assemblages of near monospecific B. pseudomacrescens and low-marsh or tidal-flat foraminifera.

  10. Long-term salt marsh vertical accretion in a tidal bay with reduced sediment supply

    NASA Astrophysics Data System (ADS)

    Ma, Zhigang; Ysebaert, Tom; van der Wal, Daphne; de Jong, Dick J.; Li, Xiuzhen; Herman, Peter M. J.

    2014-06-01

    Because of damming and intensive human activities, the sediment supply to many estuaries and deltas is dramatically decreasing. In the Oosterschelde (southwest Netherlands), a storm surge barrier (SSB) and two compartmentalization dams were built in the 1980s to protect the densely inhabited inland against flooding. After these constructions, the tidal range and mean high water level in the Oosterschelde decreased by about 12% and suspended sediment concentrations in the channels dropped by 52-70% compared to the pre-barrier conditions. The vertical accretion rates of the three largest salt marshes (Rattekaai, Sint Annaland and Slaak) in the Oosterschelde in response to this decreased sediment supply were investigated. There was a general accreting trend over the entire post-barrier period (1988-2011) in all three marshes. The predicted slowdown in accretion rates by De Jong et al. (1994) did not persist, although accretion rates were lower than in the pre-barrier period. More than 20 year observations from kaoline markers showed variation of accretion rates within and among marshes. Year-to-year variation in accretion rates was large, but only weakly (not significantly) related to the duration and frequency of marsh overflow and over-marsh extreme flooding events. However, storm events are hypothesized to be responsible for the observed trends, but our observations lack the temporal resolution to identify specific storm events. Salt marshes in the Oosterschelde are expected to survive under the present sea level rise rate and subsidence rate scenarios.

  11. Geochemistry of selenium in a coastal salt marsh

    SciTech Connect

    Velinsky, D.J.; Cutter, G.A. )

    1991-01-01

    The cycling of sedimentary selenium was examined over a one-year period in the Great Marsh, Delaware (USA). While total selenium and elemental selenium decrease with depth in the sediments at similar rates, Se(IV + VI) exhibits pronounced seasonality related to the redox conditions of the marsh. Porewater selenium reflects the diagenetic cycling of Se(IV + VI) in the sediments and suggests that a partial remobilization of sedimentary selenium occurs when the upper sediments become oxidizing. Diagenetic and mass-balance models indicate that the major sources of selenium to the marsh are creek waters and atmospheric deposition, while total selenium may be removed from the sediments via the flux of volatile selenium compounds.

  12. Acute salt marsh dieback in the Mississippi River deltaic plain: A drought-induced phenomenon?

    USGS Publications Warehouse

    McKee, K.L.; Mendelssohn, I.A.; Materne, M.D.

    2004-01-01

    Aims Extensive dieback of salt marsh dominated by the perennial grass Spartina alterniflora occurred throughout the Mississippi River deltaic plain during 2000. More than 100,000 ha were affected, with 43,000 ha severely damaged. The aim of this work was to determine if sudden dieback could have been caused by a coincident drought and to assess the significance of this event with respect to long-term changes in coastal vegetation. Location Multiple dieback sites and reference sites were established along 150 km of shoreline in coastal Louisiana, USA. Methods Aerial and ground surveys were conducted from June 2000 to September 2001 to assess soil conditions and plant mortality and recovery. Results Dieback areas ranged in size from???300 m2-5 km2 in area with 50-100% mortality of plant shoots and rhizomes in affected zones. Co-occurring species such as Avicennia germinans (black mangrove) and Juncus roemerianus (needlegrass rush) were unaffected. Historical records indicate that precipitation, river discharge, and mean sea level were unusually low during the previous year. Although the cause of dieback is currently unknown, plant and soil characteristics were consistent with temporary soil desiccation that may have reduced water availability, increased soil salinity, and/or caused soil acidification (via pyrite oxidation) and increased uptake of toxic metals such as Fe or Al. Plant recovery 15 months after dieback was variable (0-58% live cover), but recovering plants were vigorous and indicated no longlasting effects of the dieback agent. Main conclusions These findings have relevance for global change models of coastal ecosystems that predict vegetation responses based primarily on long-term increases in sea level and submergence of marshes. Our results suggest that large-scale changes in coastal vegetation may occur over a relatively short time span through climatic extremes acting in concert with sea-level fluctuations and pre-existing soil conditions. ?? 2004

  13. Long-Term Sediment Dynamics in a Tidal Salt Marsh, North Inlet, South Carolina

    NASA Astrophysics Data System (ADS)

    Murphy, S.; Voulgaris, G.

    2001-05-01

    The salt marshes along the southeastern U.S. coast are in a delicate balance between rates of sediment accretion and relative sea level rise. Short-term sediment flux studies in the region indicate a net export of suspended sediment out of salt marsh systems despite the necessity for these marshes to import sediment in order to keep pace with relative sea level rise. Long-term suspended sediment concentration data collected daily through the Long-Term Ecological Research Program (LTER) are utilized in this study. The objective of this study is to identify the relative importance of different processes including tidal range, rainfall, winds, water temperature and river discharge in effecting suspended sediment concentrations in salt marsh channels. The study area is a small {\\Spartina}- and {\\Juncus}-dominated salt marsh located at North Inlet, South Carolina. Suspended sediment concentrations were collected daily at 3 sites in the marsh basin at approximately 1000 hrs EST for a period of 10 to 15 years. The determination of how suspended sediment concentrations vary with respect to the tidal cycle required identification of the phase within the cycle that the sample was collected. This was achieved predicting tidal phases using sea surface elevation data. Suspended sediment concentrations collected during periods of different rainfall, tidal ranges, wind conditions, water temperatures and freshwater discharge were used to develop "representative" tidal cycles for each of the aforementioned forcings. Mean suspended sediment concentrations were found to be highest during the ebb tide while the lowest concentrations were found following high and low slack water. These concentrations vary spatially throughout the marsh with the highest concentrations located at the most landward site and lowest at the site nearest the inlet. A seasonal bias of suspended sediment concentrations was observed with highest concentrations in the summer months. Import of sediment in the

  14. The Role of Phragmites australis in Mediating Inland Salt Marsh Migration in a Mid-Atlantic Estuary

    PubMed Central

    Smith, Joseph A. M.

    2013-01-01

    Many sea level rise adaptation plans emphasize the protection of adjacent uplands to allow for inland salt marsh migration, but little empirical information exists on this process. Using aerial photos from 1930 and 2006 of Delaware Estuary coastal habitats in New Jersey, I documented the rate of coastal forest retreat and the rate of inland salt marsh migration across 101.1 km of undeveloped salt marsh and forest ecotone. Over this time, the amount of forest edge at this ecotone nearly doubled. In addition, the average amount of forest retreat was 141.2 m while the amount of salt marsh inland migration was 41.9 m. Variation in forest retreat within the study area was influenced by variation in slope. The lag between the amount of forest retreat and salt marsh migration is accounted for by the presence of Phragmites australis which occupies the forest and salt marsh ecotone. Phragmites expands from this edge into forest dieback areas, and the ability of salt marsh to move inland and displace Phragmites is likely influenced by salinity at both an estuary-wide scale and at the scale of local subwatersheds. Inland movement of salt marsh is lowest at lower salinity areas further away from the mouth of the estuary and closer to local heads of tide. These results allow for better prediction of salt marsh migration in estuarine landscapes and provide guidance for adaptation planners seeking to prioritize those places with the highest likelihood of inland salt marsh migration in the near-term. PMID:23705031

  15. Effects of nitrogen loading on greenhouse gas emissions in salt marshes

    NASA Astrophysics Data System (ADS)

    Tang, J.; Moseman-Valtierra, S.; Kroeger, K. D.; Morkeski, K.; Mora, J.; Chen, X.; Carey, J.

    2014-12-01

    Salt marshes play an important role in global and regional carbon and nitrogen cycling. We tested the hypothesis that anthropogenic nitrogen loading alters greenhouse gas (GHG, including CO2, CH4, and N2O) emissions and carbon sequestration in salt marshes. We measured GHG emissions biweekly for two growing seasons across a nitrogen-loading gradient of four Spartina salt marshes in Waquoit Bay, Massachusetts. In addition, we conducted nitrogen addition experiments in a pristine marsh by adding low and high nitrate to triplicate plots bi-weekly during the summer. The GHG flux measurements were made in situ with a state-of-the-art mobile gas measurement system using the cavity ring down technology that consists of a CO2/CH4 analyzer (Picarro) and an N2O/CO analyzer (Los Gatos). We observed strong seasonal variations in greenhouse gas emissions. The differences in gas emissions across the nitrogen gradient were not significant, but strong pulse emissions of N2O were observed after nitrogen was artificially added to the marsh. Our results will facilitate model development to simulate GHG emissions in coastal wetlands and support methodology development to assess carbon credits in preserving and restoring coastal wetlands.

  16. Remote Estimation of Salt Marsh Biophysical Parameters in the Georgia Coast: Model Cal/Val using NASA Sensors to Improve Monitoring and Restoration Efforts by the Georgia Department of Natural Resources

    NASA Astrophysics Data System (ADS)

    White, J. A.; Padgett-Vasquez, S.; Ghosh, S.; Baruch, A.; Chen, N.; Mote, J.; Mishra, D. R.

    2013-12-01

    Salt marshes are highly productive ecosystems that provide habitat and nutrition to wildlife, offer protection from flooding and storm surges, and help filter polluted run-off from upland areas. This study demonstrates the ability to identify ';hotspots' of early stages of marsh degradation which can only be delineated by evaluating marsh biophysical characteristics including distribution of chlorophyll content (Chl), leaf area index (LAI) (a ratio of green foliage area vs. ground area), and green vegetation fraction (VF) (percent green canopy cover). These biophysical characteristics are primary indicators of photosynthetic capacity, nitrogen content, and physiological status of vegetation. Through use of NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) sensor, we retrieve the above described biophysical characteristics in Georgia salt marshes. This work is significant because it allows for the first time the use of NASA satellite data to study the biophysical characteristics of salt marshes along Georgia's coast. Our results show an efficient and non-destructive biophysical mapping protocol for emergent wetlands to be used in restoration decision-making by the Georgia Department of Natural Resources. Our primary objectives are (1) to calibrate and validate a range of MODIS-based vegetation indices (VIs) and develop prototype weekly and monthly composites of the salt marsh biophysical characteristics for the coast of Georgia from 2000 through 2013, for the growing season (March-November) and (2) to perform a time-series analysis, with map products developed from MODIS imagery, to study the overall trend of salt marsh productivity during the last decade. These VIs (NDVI, WDRVI, EVI2, SAVI, and VARI) have been widely used and tested for monitoring terrestrial vegetation, but not for salt marsh ecosystems.

  17. Relationships of salt-marsh plant distributions to tidal levels in Connecticut, USA

    SciTech Connect

    Lefor, M.W.; Kennard, W.C.; Civco, D.L.

    1987-01-01

    A three-year study of Connecticut, USA, salt-marsh vegetation was undertaken to determine the relationship of its distribution on the marsh surface to tidal levels, particularly mean high water (MHW) as measured on each of three sites representing different tidal amplitudes. Elevations and species present were measured on 1-m/sup 2/ grids in 10 x 70-m belt transects at each site. After the data were subjected to discriminant analysis and other standard statistical procedures, the results showed that 98.4% of all observations of Spartina alterniflora Loisel. occurred at or below MHW. The data can aid in salt-marsh restoration by offering a reliable indicator of what species should be planted when restored elevations and on-site MHW are known.

  18. Importance of biogeomorphic and spatial properties in assessing a tidal salt marsh vulnerability to sea-level rise

    USGS Publications Warehouse

    Thorne, Karen M.; Elliott-Fisk, Deborah L.; Wylie, Glenn D.; Perry, William M.; Takekawa, John Y.

    2014-01-01

    We evaluated the biogeomorphic processes of a large (309 ha) tidal salt marsh and examined factors that influence its ability to keep pace with relative sea-level rise (SLR). Detailed elevation data from 1995 and 2008 were compared with digital elevation models (DEMs) to assess marsh surface elevation change during this time. Overall, 37 % (113 ha) of the marsh increased in elevation at a rate that exceeded SLR, whereas 63 % (196 ha) of the area did not keep pace with SLR. Of the total area, 55 % (169 ha) subsided during the study period, but subsidence varied spatially across the marsh surface. To determine which biogeomorphic and spatial factors contributed to measured elevation change, we collected soil cores and determined percent and origin of organic matter (OM), particle size, bulk density (BD), and distance to nearest bay edge, levee, and channel. We then used Akaike Information Criterion (AICc) model selection to assess those variables most important to determine measured elevation change. Soil stable isotope compositions were evaluated to assess the source of the OM. The samples had limited percent OM by weight (-3, indicating that the soils had high mineral content with a relatively low proportion of pore space. The most parsimonious model with the highest AICc weight (0.53) included distance from bay's edge (i.e., lower intertidal) and distance from levee (i.e., upper intertidal). Close proximity to sediment source was the greatest factor in determining whether an area increased in elevation, whereas areas near landward levees experienced subsidence. Our study indicated that the ability of a marsh to keep pace with SLR varied across the surface, and assessing changes in elevation over time provides an alternative method to long-term accretion monitoring. SLR models that do not consider spatial variability of biogeomorphic and accretion processes may not correctly forecast marsh drowning rates, which may be especially true in modified and urbanized

  19. Depth-distribution patterns and control of soil organic carbon in coastal salt marshes with different plant covers

    PubMed Central

    Bai, Junhong; Zhang, Guangliang; Zhao, Qingqing; Lu, Qiongqiong; Jia, Jia; Cui, Baoshan; Liu, Xinhui

    2016-01-01

    This study was carried out in three kinds of salt marshes according to the vegetation covers, including Phragmites australis salt marsh (PSM), Suaeda salus salt marsh (SSM) and Tamarix chinensis-Suaeda salus salt marsh (TSSM). We applied allometric function, exponential function and logistic function to model the depth distribution of the SOCv and SOCc for each salt marsh, respectively. The results showed that the exponential function fits the depth distribution of the SOCv more well than other two functions. The SOCc can be fitted very well by all three functions for three salt marsh (Adj. R2 > 0.99), of which the allometric function was the best one. The mean topsoil concentration factors (TCFs) of three salt marshes were beyond 0.1, which means the SOC enrichment in surface soils due to plant cycling, but TCFs in PSM were significantly higher than those in SSM (P < 0.05). Nearly 30% of SOC was concentrated in the top 20 cm soils. The results of general linear model (GLM) suggested that four soil properties (soil water content, pH, soil salt content and silt+clay) and their interactive effects explained about 80% of the total variation of SOC stock in the top 20 cm soils and the 20–100 cm soil layers. PMID:27708421

  20. Classification of salt marsh vegetation using edaphic and remote sensing-derived variables

    NASA Astrophysics Data System (ADS)

    Hladik, Christine; Alber, Merryl

    2014-03-01

    Salt marsh plant communities are known for their striking patterns of vertical zonation. Two of the most important edaphic parameters that affect species distribution patterns are soil salinity and waterlogging, both of which are related to topographical variations and distance to the water. The primary objective of this study was to evaluate whether information on elevation and distance derived through remote sensing could be used to predict plant distributions in a southeastern United States salt marsh. We classified four marsh vegetation classes (tall Spartina alterniflora, medium S. alterniflora/short S. alterniflora, marsh meadow, and Borrichia frutescens/Juncus roemerianus) based on landscape metrics obtained from a light detection and ranging (LIDAR)-derived digital elevation model (DEM) and compared results to a classification based on field-collected edaphic variables. Our secondary objective was to compare the performance of linear discriminant analysis (LDA) with non-parametric classification and regression trees (CART) for these classifications. Models based on the edaphic variables soil water content, salinity, and redox potential attained accuracies of 0.62 and 0.71 with LDA and CART, respectively. When the remote sensing-derived variables DEM elevation, slope, distance to the mean high water line, and distance to upland area were used, classification accuracies improved to 0.78 for LDA and 0.79 for CART. Our results suggest that remote sensing-derived metrics can capture edaphic gradients effectively, which makes them especially suited to landscape level analyses of salt marsh plant habitats, with potential application for predicting the effects of sea level rise on salt marsh plant distribution.

  1. Is Residential Development Adjacent to Salt Marshes Causing Declines in Seaside Sparrows?

    EPA Science Inventory

    To assess the possible effects of residential development on nesting populations of Seaside Sparrow (Ammodramus maritimus), we repeated a 1982 survey conducted by Stoll and Golet. In June and July 2007, 23 RI salt marshes were surveyed in their entirety for the presenc...

  2. WATER LEVEL AND OXYGEN DELIVERY/UTILIZATION IN POROUS SALT MARSH SEDIMENTS

    EPA Science Inventory

    Increasing terrestrial nutrient inputs to coastal waters is a global water quality issue worldwide, and salt marshes may provide a valuable nutrient buffer, either by direct removal or by smoothing out pulse inputs between sources and sensitive estuarine habitats. A major challen...

  3. Fish utilization of a salt marsh intertidal creek in the Yangtze River estuary, China

    NASA Astrophysics Data System (ADS)

    Jin, Binsong; Fu, Cuizhang; Zhong, Junsheng; Li, Bo; Chen, Jiakuan; Wu, Jihua

    2007-07-01

    The structure and temporal variations of the fish community in salt marshes of Chinese estuaries are poorly understood. Fish utilization of a salt marsh intertidal creek in the Yangtze River estuary was studied based on quarterly sampling surveys in July and November, 2004, and February and May, 2005. Fishes were collected by consecutive day and night samplings using fyke nets during the ebbing spring tides. A total of 25,010 individuals were caught during the study. 17 families and 33 species were documented, and the most species-rich family was Gobiidae. Three species, Synechogobius ommaturus, Chelon haematocheilus and Lateolabrax maculatus together comprised 95.65% of the total catch, which were also the most important commercial fishery species in the Yangtze River estuary. The fish community was dominated by juvenile individuals of estuarine resident species. Time of year significantly affected fish use of salt marshes, but no significant effects of diel periodicity on the fish community were found except for fish sampling in July. These findings indicate that salt marshes in the Yangtze River estuary may play important nursery roles for fish community.

  4. HEMIPARASITES GENERATE ENVIRONMENTAL HETEROGENEITY AND ENHANCE SPECIES COEXISTENCE IN SALT MARSHES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tidal inundation and salinity are considered to be controlling factors in salt marsh species distributions. Parasitic plants may also influence community organization as parasite – host interactions may play a functional role in stress amelioration due to physiological mechanisms for salinity toler...

  5. Suspended Solids Flux Between Salt Marsh and Adjacent Bay: A Long-term Continuous Measurement

    NASA Astrophysics Data System (ADS)

    Suk, N. S.; Guo, Q.; Psuty, N. P.

    1999-07-01

    The beneficial roles of coastal salt marshes have been well identified as a storm surge protector, a nursery for young fish and a natural filter for pollutants. However, the vectors of nutrients and suspended solids exchanges between the salt marsh and the adjacent bay are not completely known. In this study, suspended solids flux between a salt marsh at Tuckerton, New Jersey, U.S.A. and Great Bay was continuously measured for an extended period of time by an improved monitoring methodology. A field infrared nephelometric turbidimeter was deployed to measure turbidity continuously at the mouth of the tidal creek, and the measured turbidity data were used to derive suspended solids concentrations. Current velocity and water surface elevation were measured concurrently at the same location. During the monitoring period from March to October 1996, suspended solids were found to be imported into the salt marsh from the adjacent bay. The small net import appeared to be inadequate for wetlands areal viability when compared to the relative sea-level rise rates. Results of this study suggested that a minimum of five water sample sets were needed to establish a reasonably good overall TSS-turbidity regression relationship in terms of flux quantification.

  6. Using Nitrogen Stable Isotope Tracers to Track Climate Change Impacts on Coastal Salt Marshes

    EPA Science Inventory

    Climate change impacts on coastal salt marshes are predicted to be complex and multi-faceted. In addition to rising sea level and warmer water temperatures, regional precipitation patterns are also expected to change. At least in the Northeast and Mid-Atlantic U.S., more severe s...

  7. Calcite-accumulating large sulfur bacteria of the genus Achromatium in Sippewissett Salt Marsh.

    PubMed

    Salman, Verena; Yang, Tingting; Berben, Tom; Klein, Frieder; Angert, Esther; Teske, Andreas

    2015-11-01

    Large sulfur bacteria of the genus Achromatium are exceptional among Bacteria and Archaea as they can accumulate high amounts of internal calcite. Although known for more than 100 years, they remain uncultured, and only freshwater populations have been studied so far. Here we investigate a marine population of calcite-accumulating bacteria that is primarily found at the sediment surface of tide pools in a salt marsh, where high sulfide concentrations meet oversaturated oxygen concentrations during the day. Dynamic sulfur cycling by phototrophic sulfide-oxidizing and heterotrophic sulfate-reducing bacteria co-occurring in these sediments creates a highly sulfidic environment that we propose induces behavioral differences in the Achromatium population compared with reported migration patterns in a low-sulfide environment. Fluctuating intracellular calcium/sulfur ratios at different depths and times of day indicate a biochemical reaction of the salt marsh Achromatium to diurnal changes in sedimentary redox conditions. We correlate this calcite dynamic with new evidence regarding its formation/mobilization and suggest general implications as well as a possible biological function of calcite accumulation in large bacteria in the sediment environment that is governed by gradients. Finally, we propose a new taxonomic classification of the salt marsh Achromatium based on their adaptation to a significantly different habitat than their freshwater relatives, as indicated by their differential behavior as well as phylogenetic distance on 16S ribosomal RNA gene level. In future studies, whole-genome characterization and additional ecophysiological factors could further support the distinctive position of salt marsh Achromatium.

  8. Dynamics of pore-water and salt in estuarine marshes subjected to tide and evaporation

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Shen, C.; Li, L.; Lockington, D. A.

    2015-12-01

    Salt dynamics in estuarine tidal marshes are strongly associated with their intrinsic hydrological processes and ecological behaviors, which are not well understood. Numerical simulations were carried out to investigate the transport and distribution of pore water and salt in a vertical cross section perpendicular to the tidal creek that subjects to spring-neap tide and evaporation. Vaporizing pore water from unsaturated soil surface with salt left in soils, the time-variant actual evaporation is affected by aerodynamic factors as well as soil conditions, including pore-water saturation, solute concentration and the thickness of salt precipitation above the soil surface (efflorescence). Different simulation cases were performed by adjusting the tidal signal, marsh platform slope and soil properties. The simulation analysis indicates that, the tide-averaged soil salinity increases with the reduction of inundation period in a spring-neap tide cycle. As the salt accumulated by evaporation could leave soil from seepage back to seawater during ebbtide, the pore-water salinity at the surface within the tidal range remains close to that of seawater. With the presence of hyper-saline soil and efflorescence, salt flat develops only in the area where capillary connection between evaporating surface and water-saturated soil is maintained while tidal inundation absent. On the contrary, the sandy supratidal marsh where hydrological connections are disrupted keeps a relatively low soil salinity (40-60 ppt) and pore-water saturation as evaporation remains low throughout the tidal cycles.

  9. Dynamics of bacterial community succession in a salt marsh chronosequence: evidences for temporal niche partitioning

    PubMed Central

    Dini-Andreote, Francisco; de Cássia Pereira e Silva, Michele; Triadó-Margarit, Xavier; Casamayor, Emilio O; van Elsas, Jan Dirk; Salles, Joana Falcão

    2014-01-01

    The mechanisms underlying community assembly and promoting temporal succession are often overlooked in microbial ecology. Here, we studied an undisturbed salt marsh chronosequence, spanning over a century of ecosystem development, to understand bacterial succession in soil. We used 16S rRNA gene-based quantitative PCR to determine bacterial abundance and multitag 454 pyrosequencing for community composition and diversity analyses. Despite 10-fold lower 16S rRNA gene abundances, the initial stages of soil development held higher phylogenetic diversities than the soil at late succession. Temporal variations in phylogenetic β-diversity were greater at initial stages of soil development, possibly as a result of the great dynamism imposed by the daily influence of the tide, promoting high immigration rates. Allogenic succession of bacterial communities was mostly driven by shifts in the soil physical structure, as well as variations in pH and salinity, which collectively explained 84.5% of the variation concerning community assemblage. The community assembly data for each successional stage were integrated into a network co-occurrence analysis, revealing higher complexity at initial stages, coinciding with great dynamism in turnover and environmental variability. Contrary to a spatial niche-based perspective of bacterial community assembly, we suggest temporal niche partitioning as the dominant mechanism of assembly (promoting more phylotype co-occurrence) in the initial stages of succession, where continuous environmental change results in the existence of multiple niches over short periods of time. PMID:24739625

  10. Crabs Mediate Interactions between Native and Invasive Salt Marsh Plants: A Mesocosm Study

    PubMed Central

    Zhang, Xiao-dong; Jia, Xin; Chen, Yang-yun; Shao, Jun-jiong; Wu, Xin-ru; Shang, Lei; Li, Bo

    2013-01-01

    Soil disturbance has been widely recognized as an important factor influencing the structure and dynamics of plant communities. Although soil reworkers were shown to increase habitat complexity and raise the risk of plant invasion, their role in regulating the interactions between native and invasive species remains unclear. We proposed that crab activities, via improving soil nitrogen availability, may indirectly affect the interactions between invasive Spartina alterniflora and native Phragmites australis and Scirpus mariqueter in salt marsh ecosystems. We conducted a two-year mesocosm experiment consisting of five species combinations, i.e., monocultures of three species and pair-wise mixtures of invasive and native species, with crabs being either present or absent for each combination. We found that crabs could mitigate soil nitrogen depletion in the mesocosm over the two years. Plant performance of all species, at both the ramet-level (height and biomass per ramet) and plot-level (density, total above- and belowground biomass), were promoted by crab activities. These plants responded to crab disturbance primarily by clonal propagation, as plot-level performance was more sensitive to crabs than ramet-level. Moreover, crab activities altered the competition between Spartina and native plants in favor of the former, since Spartina was more promoted than native plants by crab activities. Our results suggested that crab activities may increase the competition ability of Spartina over native Phragmites and Scirpus through alleviating soil nitrogen limitation. PMID:24023926

  11. The rationale for attempting to define salt marsh mosquito-breeding areas in Galveston County by remote sensing the associated vegetation

    NASA Technical Reports Server (NTRS)

    Arp, G. K.

    1975-01-01

    The rationale for attempting to define salt marsh mosquito breeding areas in Galveston County was discussed, including a botanical survey of the marsh plant communities, their relationship to flooding, and their exposure to salt water. Particular emphasis is given to Distichlis spicata, a widespread marsh grass. Evidence suggests that breeding areas of Aedes sollicitans are associated with Distichlis and that both species respond to similar ecological conditions in the salt marsh. Aspects of the remote sensing of the Distichlis are considered.

  12. Evaluating a portable cylindrical bait trap to capture diamondback terrapins in salt marsh

    USGS Publications Warehouse

    Henry, Paula F.; Haramis, Michael; Day, Daniel

    2016-01-01

    Diamondback terrapins (Malaclemys terrapin) are currently in decline across much of their historical range, and demographic data on a regional scale are needed to identify where their populations are at greatest risk. Because terrapins residing in salt marshes are difficult to capture, we designed a cylindrical bait trap (CBT) that could be deployed in shallow tidal waters. From 2003 to 2006, trials were conducted with CBTs in the Chesapeake Bay, Maryland (USA) to determine terrapin sex, size, and age distribution within 3 salt marsh interior habitats—open bays, tidal guts, and broken marshes—using 15 traps/habitat. Analyses based on 791 total captures with CBTs indicate that smaller terrapins, (i.e., adult male and subadult) were more prevalent within the transecting tidal guts and broken marshes, whereas the adult females were more evenly distributed among habitats, including open bays. Subadult females made up the largest percent of catch in the CBTs deployed within the 3 marsh interior habitats. During a 12-day trial in which we compared capture performance of CBTs and modified fyke nets along open shorelines during the nesting season, fyke nets outperformed CBTs by accounting for 95.2% of the 604 terrapin captures. Although the long drift leads of the fyke nets proved more effective for intercepting along-shore travel of adult female terrapins during the nesting season, CBTs provided a more effective means of live-trapping terrapins within the shallow interior marshes.

  13. Recommended design for more accurate duplication of natural conditions in salt marsh creation.

    PubMed

    Darnell, T M; Smith, E H

    2002-06-01

    Construction of 653 ha of salt marsh habitat from dredged material near the Aransas National Wildlife Refuge, Texas, has been proposed, with the goal of increasing the area of habitat available to endangered whooping cranes ( Grus americana). We assessed prototype created wetlands, and their similarity to natural reference sites, in terms of topography, vegetation, and hydrology. The created sites were steeply sloped relative to natural sites and were dominated by monotypic stands of Spartina alterniflora. Natural sites were dominated by vegetation more tolerant of desiccation and hypersalinity and by unvegetated salt pans. Differences in vegetation communities and distributions of habitat types resulted from efforts to enhance habitat diversity in created marsh cells through manipulation of marsh topography. However, the scale at which this diversity occurred in natural marsh of the study area was not considered. When constructing wetlands in cellular configurations, we recommend creation of large complexes of adjoining, hydrologically linked, cells wherein the desired habitat diversity is created at the scale of the entire complex, rather than within a single cell. Suggested design modifications would increase the similarity of created marshes to natural reference sites, potentially improving habitat function.

  14. The use of chlorate, nitrate, and perchlorate to promote crude oil mineralization in salt marsh sediments.

    PubMed

    Brundrett, Maeghan; Horita, Juske; Anderson, Todd; Pardue, John; Reible, Danny; Jackson, W Andrew

    2015-10-01

    Due to the high volume of crude oil released by the Deepwater Horizon oil spill, the salt marshes along the gulf coast were contaminated with crude oil. Biodegradation of crude oil in salt marshes is primarily limited by oxygen availability due to the high organic carbon content of the soil, high flux rate of S(2-), and saturated conditions. Chlorate, nitrate, and perchlorate were evaluated for use as electron acceptors in comparison to oxygen by comparing oil transformation and mineralization in mesocosms consisting of oiled salt marsh sediment from an area impacted by the BP Horizon oil spill. Mineralization rates were determined by measuring CO2 production and δ (13)C of the produced CO2 and compared to transformation evaluated by measuring the alkane/hopane ratios over a 4-month period. Total alkane/hopane ratios decreased (~55-70 %) for all treatments in the following relative order: aerated ≈ chlorate > nitrate > perchlorate. Total CO2 produced was similar between treatments ranging from 550-700 mg CO2-C. The δ (13)C-CO2 values generally ranged between the indigenous carbon and oil values (-17 and -27‰, respectively). Oil mineralization was greatest for the aerated treatments and least for the perchlorate amended. Our results indicate that chlorate has a similar potential as oxygen to support oil mineralization in contaminated salt marshes, but nitrate and perchlorate were less effective. The use of chlorate as a means to promote oil mineralization in situ may be a promising means to remediate contaminated salt marshes while preventing unwanted secondary impacts related to nutrient management as in the case of nitrate amendments. PMID:25854211

  15. The use of chlorate, nitrate, and perchlorate to promote crude oil mineralization in salt marsh sediments.

    PubMed

    Brundrett, Maeghan; Horita, Juske; Anderson, Todd; Pardue, John; Reible, Danny; Jackson, W Andrew

    2015-10-01

    Due to the high volume of crude oil released by the Deepwater Horizon oil spill, the salt marshes along the gulf coast were contaminated with crude oil. Biodegradation of crude oil in salt marshes is primarily limited by oxygen availability due to the high organic carbon content of the soil, high flux rate of S(2-), and saturated conditions. Chlorate, nitrate, and perchlorate were evaluated for use as electron acceptors in comparison to oxygen by comparing oil transformation and mineralization in mesocosms consisting of oiled salt marsh sediment from an area impacted by the BP Horizon oil spill. Mineralization rates were determined by measuring CO2 production and δ (13)C of the produced CO2 and compared to transformation evaluated by measuring the alkane/hopane ratios over a 4-month period. Total alkane/hopane ratios decreased (~55-70 %) for all treatments in the following relative order: aerated ≈ chlorate > nitrate > perchlorate. Total CO2 produced was similar between treatments ranging from 550-700 mg CO2-C. The δ (13)C-CO2 values generally ranged between the indigenous carbon and oil values (-17 and -27‰, respectively). Oil mineralization was greatest for the aerated treatments and least for the perchlorate amended. Our results indicate that chlorate has a similar potential as oxygen to support oil mineralization in contaminated salt marshes, but nitrate and perchlorate were less effective. The use of chlorate as a means to promote oil mineralization in situ may be a promising means to remediate contaminated salt marshes while preventing unwanted secondary impacts related to nutrient management as in the case of nitrate amendments.

  16. Long-term changes and historical uses of one of the largest French salt-marshes since 1705

    NASA Astrophysics Data System (ADS)

    Godet, Laurent; Pourinet, Laurent; Decaulne, Armelle

    2014-05-01

    The salt-marshes of the Baie de l'Aiguillon (Western France) are among the largest of Western Europe. Thanks to exceptional historical data, including old maps, manuscripts and aerial photographs, we propose one of the first long-term accurate cartographies of such a large salt-marsh, dating back to the beginning of the 18th century. Like other salt-marshes in Western Europe, including those of the Mont Saint-Michel Bay (France), we found that they are expanding for the three last decades. However, our historical analysis also reveals that the area of these salt-marshes shrinked by two thirds over the last three centuries, due to massive land-reclamations starting from the mid-17th century. As revealed by historical testimonies and archeological remains, we also demonstrated that these salt-marshes were actively mowed as soon as the 1700s. In consequence, the oldest and the non-used parts of such salt-marshes correspond to very restricted patches that may present a high conservation stake. In the context of massive land-use and land-cover changes along the European coastal zones, historical analyses exploring long-term changes and historical uses of coastal habitats may help to identify old and natural patches of coastal habitats. Salt-marshes, that are easy to map and monitor, are good candidates for such investigations.

  17. Man's Impact on the Environment: The Freshwater Marsh as an Ecosystem. Update.

    ERIC Educational Resources Information Center

    Brevard County School Board, Cocoa, FL.

    This environmental education program emphasizes the cause and effect of change in a freshwater marsh ecosystem with special attention given to man and his role in environmental change. Concepts are employed from the natural and social sciences to investigate environmental problems. Unit activities are inquiry oriented and answer these questions:…

  18. Comparison of vesicular-arbuscular mycorrhizae in plants from disturbed and adjacent undisturbed regions of a coastal salt marsh in Clinton, Connecticut, USA

    NASA Astrophysics Data System (ADS)

    Cooke, John C.; Lefor, Michael W.

    1990-01-01

    Roots of salt marsh plant species Spartina alterniflora, S. patens, Distichlis spicata, and others were examined for the presence of vesicular-arbuscular mycorrhizal (VAM) fungi. Samples were taken from introduced planted material in a salt marsh restoration project and from native material in adjacent marsh areas along the Indian River, Clinton, Connecticut, USA. After ten years the replanted area still has sites devoid of vegetation. The salt marsh plants introduced there were devoid of VAM fungi, while high marsh species from the adjacent undisturbed region showed consistent infection, leading the authors to suggest that VAM fungal infection of planting stocks may be a factor in the success of marsh restoration.

  19. Influences of Salinity Variations on Pore-water Flow in Salt Marshes

    NASA Astrophysics Data System (ADS)

    Shen, C.; Jin, G.; Xin, P.; Li, L.

    2013-12-01

    Salt marshes are important wetlands at the ocean-land interface with various ecological functions, serving as essential habitats for intertidal fauna, affecting the productivity of coastal waters through nutrient exchange, moderating the greenhouse gas emission and global warming. They are influenced by various physical and biogeochemical processes, among which the pore-water flow and associated solute transport processes play an important role in determining the material exchange between marsh soils and coastal water. Previous studies have examined such processes under the solo or combined effects of tidal fluctuation, evapotranspiration, stratigraphy, inland freshwater input, and topography. However, these investigations have neglected the spatial and temporal salinity variations in surface water and pore-water, which commonly exist in salt marshes due to the impacts of tidal inundation, precipitation and evapotranspiration. The density contrast between the surface water and pore-water may lead to significant modifications of the pore-water flow. Based on results from laboratory experiments and numerical simulations, we will demonstrate that: (1) under upward salinity gradients, flow instabilities in the form of fingers occur once the salinity contrast reaches a certain level, whereas under downward salinity gradients the system is stable; (2) because of the strong tidally-induced advective process occurring near the creek, both the number and size of fingers change gradually from the near-creek zone to the marsh interior; and (3) both upward and downward salinity gradients enhance the exchange between the surface water and pore-water in the marsh sediments. Keywords: Salt marshes; density effect; salinity gradient; pore-water flow; fingers. Instabilities under upward salinity gradient Stable system under downward salinity gradient

  20. Impacts of salt marsh plants on tidal channel initiation and inheritance

    NASA Astrophysics Data System (ADS)

    Schwarz, Christian; Ye, Qinghua; van der Wal, Daphne; Zhang, Liquan; Ysebaert, Tom; Herman, Peter MJ

    2013-04-01

    channels on vegetation mediated channel incision. This simulated landscape development was then compared to aerial photographs from the Scheldt estuary (the Netherlands) and the Yangtze estuary (China). Our results suggest a significant impact of plant properties on tidal channel network emergence, specifically in respect to network drainage density and channel width. This emphasizes the repercussions of vegetation mediated channel incision on estuarine landscape development. Further do our results point to the existence of a threshold in pre-existing mudflat channel depth favoring either vegetation stabilized channel inheritance or vegetation mediated channel incision processes. Increasing depth in mudflat channels favors flow routing via these channels, leaving less flow and momentum remaining for the interaction between vegetation, sediment and flow and therefore vegetation mediated channel incision. This threshold will be influenced by field specific parameters such as hydrodynamics (tidal range, waves, and flow), sediments and predominant plant species. Hence our study not only demonstrates to importance of plant properties on landscape development it also shows that vegetation stabilized channel inheritance or vegetation mediated channel incision are two occurring mechanisms depending on ecosystem properties, adding important information for salt marsh management and conservation.

  1. Ecology of irregularly flooded salt marshes of the northeastern Gulf of Mexico: a community profile

    SciTech Connect

    Stout, J.P.

    1984-12-01

    The salt marshes of the northeastern Gulf of Mexico are distinguished by irregular flooding, low energy wave and tidal action, and long periods of exposure. The plant community is most often dominated by black needlerush (Juncus roemerianus), the species of focus in this synthesis. Distinct marsh zones include those dominated by Juncus and Spartina alterniflora at low elevations, sparsely vegetated salt flats, and higher elevation salt meadows of Juncus and Spartina patens. A diverse microbial and algal assemblage is also present. A diverse fauna has adapted to the physical rigors of these marshes. Zooplankton are dominated by the larvae of fiddler crabs and other decapods. The meiofauna consist primarily of nematodes and harpacticoid copepods. Macroinvertebrates are represented by crustaceans (especially mollusks and crabs), annelids, and insects. Grass shrimp, blue crabs, and other crustaceans are seasonally abundant in marsh creeks, as are a number of resident and migratory fish species. Birds comprise one of the larger herbivore groups and are also significant at higher tropic levels as top carnivores. Muskrat and nutria are important mammals. 43 figs., 38 tabs.

  2. The Effect of Nitrogen Enrichment on C1-Cycling Microorganisms and Methane Flux in Salt Marsh Sediments

    PubMed Central

    Irvine, Irina C.; Vivanco, Lucía; Bentley, Peris N.; Martiny, Jennifer B. H.

    2012-01-01

    Methane (CH4) flux from ecosystems is driven by C1-cycling microorganisms – the methanogens and the methylotrophs. Little is understood about what regulates these communities, complicating predictions about how global change drivers such as nitrogen enrichment will affect methane cycling. Using a nitrogen addition gradient experiment in three Southern California salt marshes, we show that sediment CH4 flux increased linearly with increasing nitrogen addition (1.23 μg CH4 m−2 day−1 for each g N m−2 year−1 applied) after 7 months of fertilization. To test the reason behind this increased CH4 flux, we conducted a microcosm experiment altering both nitrogen and carbon availability under aerobic and anaerobic conditions. Methanogenesis appeared to be both nitrogen and carbon (acetate) limited. N and C each increased methanogenesis by 18%, and together by 44%. In contrast, methanotrophy was stimulated by carbon (methane) addition (830%), but was unchanged by nitrogen addition. Sequence analysis of the sediment methylotroph community with the methanol dehydrogenase gene (mxaF) revealed three distinct clades that fall outside of known lineages. However, in agreement with the microcosm results, methylotroph abundance (assayed by qPCR) and composition (assayed by terminal restriction fragment length polymorphism analysis) did not vary across the experimental nitrogen gradient in the field. Together, these results suggest that nitrogen enrichment to salt marsh sediments increases methane flux by stimulating the methanogen community. PMID:22470369

  3. Seasonal and topographic variations in porewaters of a southeastern USA salt marsh as revealed by voltammetric profilingdagger.

    PubMed

    Bull, D C; Taillefert, M

    2001-11-01

    We report electrochemical profiles from unvegetated surficial sediments of a Georgia salt marsh. In creek bank sediments, the absence of Sigma H2S or FeSaq and the presence of Fe(III)-organic complexes suggest that Mn and Fe reduction dominates over at least the top ca. 5 cm of the sediment column, consistent with other recent results. In unvegetated flats, accumulation of Sigma H2S indicates that SO42- reduction dominates over the same depth. A summer release of dissolved organic species from the dominant tall form Spartina alterniflora, together with elevated temperatures, appears to result in increased SO42- reduction intensity and hence high summer concentrations of Sigma H2S in flat sediments. However, increased bioturbation and/or bioirrigation seem to prevent this from happening in bank sediments. Studies of biogeochemical processes in salt marshes need to take such spatial and temporal variations into account if we are to develop a good understanding of these highly productive ecosystems. Furthermore, multidimensional analyses are necessary to obtain adequate quantitative pictures of such heterogeneous sediments.

  4. Salt marsh equilibrium states and transient dynamics in response to changing rates of sea level rise and sediment supply

    NASA Astrophysics Data System (ADS)

    D'Alpaos, A.; Mudd, S. M.; Carniello, L.

    2012-12-01

    Understanding and predicting the response of salt-marsh bio-geomorphic systems to changes in the rate of sea level rise and sediment supply is an issue of paramount importance due to the crucial role exerted by salt marshes within the tidal landscape. Salt-marsh platforms, in fact, buffer coastlines against storms, filter nutrients and pollutants from tidal waters, provide nursery areas for coastal biota, and serve as a sink for organic carbon. Observations of marsh degradation worldwide and the acceleration in the rate of global sea level rise highlight the importance of improving our understanding of the chief processes which control salt-marsh response to current natural climate changes and to the effects of variations in sediment supply. The results of our analytical model of salt-marsh bio-morphodynamic evolution in the vertical plane, accounting for two-way interactions between ecological and geomorphological processes, show that marshes are more resilient to a step decrease in the rate of relative sea level rise rather than to a step increase of the same magnitude. Interestingly, marshes respond more rapidly to an increase in sediment load or vegetation productivity, rather than to a decrease (of the same amount) in sediment load or vegetation productivity. Model results also suggest that marsh stability is positively correlated with tidal range: marshes with high tidal ranges respond more slowly to changes in the environmental forcings and therefore are less likely to be affected by perturbations than their counterparts in low tidal ranges. Finally, the model suggests that, in the case of a oscillating rate of sea level rise, marsh stratigraphy will be unable to fully record short term fluctuations in relative mean sea level, whereas it will be able to capture long term fluctuations particularly in sediment rich, microtidal settings.

  5. Feedbacks underlie the resilience of salt marshes and rapid reversal of consumer-driven die-off.

    PubMed

    Altieri, Andrew H; Bertness, Mark D; Coverdale, Tyler C; Axelman, Eric E; Herrmann, Nicholas C; Szathmary, P Lauren

    2013-07-01

    Understanding ecosystem resilience to human impacts is critical for conservation and restoration. The large-scale die-off of New England salt marshes was triggered by overfishing and resulted from decades of runaway crab grazing. In 2009, however, cordgrass began to recover, decreasing die-off -40% by 2010. We used surveys and experiments to test whether plant-substrate feedbacks underlie marsh resilience. Initially, grazer-generated die-off swept through the cordgrass, creating exposed, stressful peat banks that inhibited plant growth. This desertification cycle broke when banks eroded and peat transitioned into mud with fewer herbivores, less grazing, and lower physical stress. Cordgrass reestablished in these areas through a feedback where it engineered a recovery zone by further ameliorating physical stresses and facilitating additional revegetation. Our results reveal that feedbacks can play a critical role in rapid, reversible ecosystem shifts associated with human impacts, and that the interplay of facilitative and consumer interactions should be incorporated into resilience theory. PMID:23951724

  6. SALT MARSH HABITAT FROM A FISH EYE VIEW: A TEST OF THE DIMENSIONLESS INDEX OF HABITAT COMPLEXITY

    EPA Science Inventory

    Salt marshes are considered important foraging and predator refuge areas for fish, but these functions are rarely measured. The goal of this study was to examine the relationship between the structural complexity of the habitat and fish size in marshes subjected to different wat...

  7. The new CutSprof sampling tool and method for micromorphological and microfacies analyses of subsurface salt marsh sediments, Algarve, Portugal

    NASA Astrophysics Data System (ADS)

    Araújo-Gomes, João; Ramos-Pereira, Ana

    2015-02-01

    A new tool and method for collecting undisturbed subsurface samples in estuarine environments by means of trenching, timbering and sectioning is presented. Smoothing of sidewalls is achieved by a so-called cutting sediment profiler (CutSprof), while water draining into the trench is cleared by pumping. From smoothed sidewall sections, undisturbed thin sediment slices can then be collected for micromorphological and microfacies analyses. Results demonstrating the successful application of this procedure are presented for salt marshes of the Bensafrim River estuary (Lagos, Algarve, Portugal). In addition to palaeo-reconstructions in salt marsh settings, the CutSprof would be highly suitable in various other research domains as well as for environmental management purposes, particularly where sampling below the groundwater table is desirable to explore, for example, animal-sediment relationships in tidal-flat and mangrove ecosystems as well as the dynamics of coastal wetlands today threatened by ever-increasing anthropogenic influence.

  8. Spartina alterniflora genotype influences facilitation and suppression of high marsh species colonizing an early successional salt marsh

    USGS Publications Warehouse

    Proffitt, C.E.; Chiasson, R.L.; Owens, A.B.; Edwards, K.R.; Travis, S.E.

    2005-01-01

    1. Genetically based phenotypic and ecotypic variation in a dominant plant species can influence ecological functions and patterns of recruitment by other species in plant communities. However, the nature and degree of importance of genotypic differences is poorly understood in most systems. 2. The dominant salt marsh species, Spartina alterniflora, is known to induce facultative and competitive effects in different plant species, and the outcomes of interactions can be affected by nutrients and flooding stress. Clonal genotypes, which maintained their different plant architecture phenotypes throughout 31 months of a field experiment, underwent considerable genet-specific senescence in their centres over the last 12 months. 3. Different clonal genotypes and different locations (robust edges vs. senescent centres) permitted significantly different levels of light penetration of the canopy (14.8-77.6%), thus establishing spatial heterogeneity for this important environmental factor. 4. S. alterniflora clonal genotype influenced the degree of suppression of the previously dominant Salicornia bigelovii as well as facilitation of recruitment and growth by other plant species. Aster subulatus and Atriplex, patula performed better in Spartina clone centres, and experienced reduced growth in Salicornia-dominated areas. 5. Four other high marsh species (Borrichia frutescens, Aster tenuifolius, Iva frutescens and Limonium carolinianum) colonized only into Spartina clones but not into the Salicornia-dominated area. 6. These results suggest that differences in clone size, centre senescence, stem density, height, total stem length and biomass in different genotypes of a dominant marsh plant species can influence recruitment and growth of other plant species. The spatial pattern of habitat heterogeneity is, at least in part, dependent on the genotypic diversity, and possibly the genetic diversity, of such foundation species. 7. We hypothesize that as genotypic diversity

  9. Community composition and activity of anaerobic ammonium oxidation bacteria in the rhizosphere of salt-marsh grass Spartina alterniflora.

    PubMed

    Zheng, Yanling; Hou, Lijun; Liu, Min; Yin, Guoyu; Gao, Juan; Jiang, Xiaofen; Lin, Xianbiao; Li, Xiaofei; Yu, Chendi; Wang, Rong

    2016-09-01

    Anaerobic ammonium oxidation (anammox) as an important nitrogen removal pathway has been investigated in intertidal marshes. However, the rhizosphere-driven anammox process in these ecosystems is largely overlooked so far. In this study, the community dynamics and activities of anammox bacteria in the rhizosphere and non-rhizosphere sediments of salt-marsh grass Spartina alterniflora (a widely distributed plant in estuaries and intertidal ecosystems) were investigated using clone library analysis, quantitative PCR assay, and isotope-tracing technique. Phylogenetic analysis showed that anammox bacterial diversity was higher in the non-rhizosphere sediments (Scalindua and Kuenenia) compared with the rhizosphere zone (only Scalindua genus). Higher abundance of anammox bacteria was detected in the rhizosphere (6.46 × 10(6)-1.56 × 10(7) copies g(-1)), which was about 1.5-fold higher in comparison with that in the non-rhizosphere zone (4.22 × 10(6)-1.12 × 10(7) copies g(-1)). Nitrogen isotope-tracing experiments indicated that the anammox process in the rhizosphere contributed to 12-14 % N2 generation with rates of 0.43-1.58 nmol N g(-1) h(-1), while anammox activity in the non-rhizosphere zone contributed to only 4-7 % N2 production with significantly lower activities (0.28-0.83 nmol N g(-1) h(-1)). Overall, we propose that the rhizosphere microenvironment in intertidal marshes might provide a favorable niche for anammox bacteria and thus plays an important role in nitrogen cycling. PMID:27225476

  10. A geohydrologic continuum theory for the spatial and temporal evolution of marsh-estuarine ecosystems

    NASA Astrophysics Data System (ADS)

    Dame, R.; Childers, D.; Koepfler, E.

    Using ecosystem development theory and the River Continuum Concept as starting points, we present a new holistic theory to explain the spatial and temporal behaviour of marsh-estuarine ecosystems Along the marine-estuarine-freshwater gradient in response to sea-level rise. In this theory, a geohydrologic continuum represented by tidal channel provides a predictable physical model of how the marsh-estuarine ecosystem adapts until there is a change of state. North Inlet, South Carolina is used as an example of this marsh-estuarine continuum. Mature creeks are at the ocean-estuary interface and are strongly influenced by marine factors. Further into the estuary, less and less mature creeks are encountered which are dominated by smaller scale spatial and temporal controls such as oyster reefs. Immature or ephemeral creeks import both particulate and dissolved materials, while mature creeks export both forms of nutrients. Mid-aged creeks appear to take up particulate materials and release dissolved constituents. Ultimately, the continuum reaches the fresh-saltwater interface where a very young estuarine ecosystem invades a more mature type, under the influence of disturbance. Our new explanation satisfies most criteria for a good theory by being internally consistent to the location specified, generating testable hypothesis, not blindly adapting existing theories, agreeing with known properties of the ecosystem described and by generating new invigorating discussion within the scientific community.

  11. Exchanges and photo-biogeochemical transformation of dissolved organic compounds in Eastern US tidal marsh ecosystems.

    NASA Astrophysics Data System (ADS)

    Tzortziou, Maria; Neale, Patrick; Megonigal, Patrick; Butterworth, Megan; Jaffe, Rudolf

    2010-05-01

    The role of tidal marshes as sources, sinks and/or transformers of biologically important nutrients, carbon and pollutants has been studied in various marsh-estuarine environments and geomorphological settings. Although there is no consensus on the magnitude and direction of marsh-estuary net (particulate and dissolved) organic fluxes, most previous studies suggest that salt marshes export dissolved organic carbon (DOC) to the surrounding estuarine waters. There has been less attention, however, to the influence of transformations on marsh-exported organic carbon composition or "quality". Yet, carbon composition affects a wide variety of estuarine processes, including microbial respiration and photochemistry. Our objectives in this study were to quantify the photo-reactivity and bio-availability of dissolved organic carbon compounds exported from tidal wetlands of the Chesapeake Bay and determine their effects on the optical properties of colored organic matter (CDOM). We quantified DOC bioavailability with two assays of microbial mineralization: the traditional batch incubation approach in which a suspension of DOM and microbial cells (1 µm filtrate) was incubated in bottles for 7 d, and a continuous-flow bioreactor approach in which DOC (0.2 µm filtrate) was passed through a microbial community that had been pre-established on glass beads from the same source water. Photochemical degradation was measured after a 10h exposure to filtered xenon irradiance simulating midday surface exposure. We measured decreases in CDOM absorption and fluorescence spectra, DOC concentrations, changes in molecular weight distribution, and increases in dissolved inorganic carbon (DIC) and CO2. Results provide important insights on the transformation, fate and cycling of marsh-exported organic compounds, and the role of tidal marsh systems as major regulators of short-scale biological, optical and biogeochemical variability in highly dynamic coastal margins and catchment areas.

  12. Sediment quality assessment in tidal salt marshes in northern California, USA: An evaluation of multiple lines of evidence approach

    USGS Publications Warehouse

    Hwang, Hyun-Min; Carr, Robert S.; Cherr, Gary N.; Green, Peter G.; Grosholz, Edwin G.; Judah, Linda; Morgan, Steven G.; Ogle, Scott; Rashbrook, Vanessa K.; Rose, Wendy L.; Teh, Swee J.; Vines, Carol A.; Anderson, Susan L.

    2013-01-01

    The objective of this study was to evaluate the efficacy of integrating a traditional sediment quality triad approach with selected sublethal chronic indicators in resident species in assessing sediment quality in four salt marshes in northern California, USA. These included the highly contaminated (Stege Marsh) and relatively clean (China Camp) marshes in San Francisco Bay and two reference marshes in Tomales Bay. Toxicity potential of contaminants and benthic macroinvertebrate survey showed significant differences between contaminated and reference marshes. Sublethal responses (e.g., apoptotic DNA fragmentation, lipid accumulation, and glycogen depletion) in livers of longjaw mudsucker (Gillichthys mirabilis) and embryo abnormality in lined shore crab (Pachygrapsus crassipes) also clearly distinguished contaminated and reference marshes, while other responses (e.g., cytochrome P450, metallothionein) did not. This study demonstrates that additional chronic sublethal responses in resident species under field exposure conditions can be readily combined with sediment quality triads for an expanded multiple lines of evidence approach. This confirmatory step may be warranted in environments like salt marshes in which natural variables may affect interpretation of toxicity test data. Qualitative and quantitative integration of the portfolio of responses in resident species and traditional approach can support a more comprehensive and informative sediment quality assessment in salt marshes and possibly other habitat types as well.

  13. Sediment and vegetation spatial dynamics facing sea-level rise in microtidal salt marshes: Insights from an ecogeomorphic model

    NASA Astrophysics Data System (ADS)

    Belliard, J.-P.; Di Marco, N.; Carniello, L.; Toffolon, M.

    2016-07-01

    Modeling efforts have considerably improved our understanding on the chief processes that govern the evolution of salt marshes under climate change. Yet the spatial dynamic response of salt marshes to sea-level rise that results from the interactions between the tidal landforms of interest and the presence of bio-geomorphic features has not been addressed explicitly. Accordingly, we use a modeling framework that integrates the co-evolution of the marsh platform and the embedded tidal networks to study sea-level rise effects on spatial sediment and vegetation dynamics in microtidal salt marshes considering different ecological scenarios. The analysis unveils mechanisms that drive spatial variations in sedimentation rates in ways that increase marsh resilience to rising sea-levels. In particular, marsh survival is related to the effectiveness of transport of sediments toward the interior marshland. This study hints at additional dynamics related to the modulation of channel cross-sections affecting sediment advection in the channels and subsequent delivery in the inner marsh, which should be definitely considered in the study of marsh adaptability to sea-level rise and posterior management.

  14. Activity and growth efficiency of heterotrophic bacteria in a salt marsh (Ria de Aveiro, Portugal).

    PubMed

    Cunha, M A; Pedro, R; Almeida, M A; Silva, M H

    2005-01-01

    Bacterial utilization of monomers is recognized as an important step in the biogeochemical cycling of organic matter. In this study we have compared the heterotrophic activity of bacterial communities from different micro-habitats within a salt marsh environment (Ria de Aveiro, Portugal) in order to establish spatial patterns of bacterial abundance, monomer turnover rates (Tr) and bacterial growth efficiency (BGE). Differences in bacterial abundance and activity could be found between distinct plant rhizospheres. BGE tended to be lower at Halimione portulacoides banks, when compared to Sarcocornia perennis subsp. perennis banks which, on the contrary, showed the highest bacterial densities. Experiments of amendment of natural samples with organic and inorganic supplements indicated that salt marsh bacteria are not strongly regulated by salinity but the increased availability of labile organic matter causes a significant metabolic shift towards mineralization.

  15. Calcite-accumulating large sulfur bacteria of the genus Achromatium in Sippewissett Salt Marsh

    PubMed Central

    Salman, Verena; Yang, Tingting; Berben, Tom; Klein, Frieder; Angert, Esther; Teske, Andreas

    2015-01-01

    Large sulfur bacteria of the genus Achromatium are exceptional among Bacteria and Archaea as they can accumulate high amounts of internal calcite. Although known for more than 100 years, they remain uncultured, and only freshwater populations have been studied so far. Here we investigate a marine population of calcite-accumulating bacteria that is primarily found at the sediment surface of tide pools in a salt marsh, where high sulfide concentrations meet oversaturated oxygen concentrations during the day. Dynamic sulfur cycling by phototrophic sulfide-oxidizing and heterotrophic sulfate-reducing bacteria co-occurring in these sediments creates a highly sulfidic environment that we propose induces behavioral differences in the Achromatium population compared with reported migration patterns in a low-sulfide environment. Fluctuating intracellular calcium/sulfur ratios at different depths and times of day indicate a biochemical reaction of the salt marsh Achromatium to diurnal changes in sedimentary redox conditions. We correlate this calcite dynamic with new evidence regarding its formation/mobilization and suggest general implications as well as a possible biological function of calcite accumulation in large bacteria in the sediment environment that is governed by gradients. Finally, we propose a new taxonomic classification of the salt marsh Achromatium based on their adaptation to a significantly different habitat than their freshwater relatives, as indicated by their differential behavior as well as phylogenetic distance on 16S ribosomal RNA gene level. In future studies, whole-genome characterization and additional ecophysiological factors could further support the distinctive position of salt marsh Achromatium. PMID:25909974

  16. Assessing wildlife benefits and carbon storage from restored and natural coastal marshes in the Nisqually River Delta: Determining marsh net ecosystem carbon balance

    USGS Publications Warehouse

    Anderson, Frank; Bergamaschi, Brian; Windham-Myers, Lisamarie; Woo, Isa; De La Cruz, Susan; Drexler, Judith; Byrd, Kristin; Thorne, Karen M.

    2016-01-01

    Working in partnership since 1996, the U.S. Fish and Wildlife Service and the Nisqually Indian Tribe have restored 902 acres of tidally influenced coastal marsh in the Nisqually River Delta (NRD), making it the largest estuary-restoration project in the Pacific Northwest to date. Marsh restoration increases the capacity of the estuary to support a diversity of wildlife species. Restoration also increases carbon (C) production of marsh plant communities that support food webs for wildlife and can help mitigate climate change through long-term C storage in marsh soils.In 2015, an interdisciplinary team of U.S. Geological Survey (USGS) researchers began to study the benefits of carbon for wetland wildlife and storage in the NRD. Our primary goals are (1) to identify the relative importance of the different carbon sources that support juvenile chinook (Oncorhynchus tshawytscha) food webs and contribute to current and historic peat formation, (2) to determine the net ecosystem carbon balance (NECB) in a reference marsh and a restoration marsh site, and (3) to model the sustainability of the reference and restoration marshes under projected sea-level rise conditions along with historical vegetation change. In this fact sheet, we focus on the main C sources and exchanges to determine NECB, including carbon dioxide (CO2) uptake through plant photosynthesis, the loss of CO2 through plant and soil respiration, emissions of methane (CH4), and the lateral movement or leaching loss of C in tidal waters.

  17. Assessing wildlife benefits and carbon storage from restored and natural coastal marshes in the Nisqually River Delta: Determining marsh net ecosystem carbon balance

    USGS Publications Warehouse

    Anderson, Frank; Bergamaschi, Brian; Windham-Myers, Lisamarie; Woo, Isa; De La Cruz, Susan; Drexler, Judith; Byrd, Kristin; Thorne, Karen M.

    2016-06-24

    Working in partnership since 1996, the U.S. Fish and Wildlife Service and the Nisqually Indian Tribe have restored 902 acres of tidally influenced coastal marsh in the Nisqually River Delta (NRD), making it the largest estuary-restoration project in the Pacific Northwest to date. Marsh restoration increases the capacity of the estuary to support a diversity of wildlife species. Restoration also increases carbon (C) production of marsh plant communities that support food webs for wildlife and can help mitigate climate change through long-term C storage in marsh soils.In 2015, an interdisciplinary team of U.S. Geological Survey (USGS) researchers began to study the benefits of carbon for wetland wildlife and storage in the NRD. Our primary goals are (1) to identify the relative importance of the different carbon sources that support juvenile chinook (Oncorhynchus tshawytscha) food webs and contribute to current and historic peat formation, (2) to determine the net ecosystem carbon balance (NECB) in a reference marsh and a restoration marsh site, and (3) to model the sustainability of the reference and restoration marshes under projected sea-level rise conditions along with historical vegetation change. In this fact sheet, we focus on the main C sources and exchanges to determine NECB, including carbon dioxide (CO2) uptake through plant photosynthesis, the loss of CO2 through plant and soil respiration, emissions of methane (CH4), and the lateral movement or leaching loss of C in tidal waters.

  18. Bacterial community response to petroleum contamination and nutrient addition in sediments from a temperate salt marsh.

    PubMed

    Ribeiro, Hugo; Mucha, Ana P; Almeida, C Marisa R; Bordalo, Adriano A

    2013-08-01

    Microbial communities play an important role in the biodegradation of organic pollutants in sediments, including hydrocarbons. The aim of this study was to evaluate the response of temperate salt marsh microbial communities to petroleum contamination, in terms of community structure, abundance and capacity to degrade hydrocarbons. Sediments un-colonized and colonized (rhizosediments) by Juncus maritimus, Phragmites australis and Triglochin striata were collected in a temperate estuary (Lima, NW Portugal), spiked with petroleum under variable nutritional conditions, and incubated for 15 days. Results showed that plant speciation emerged as the major factor for shaping the rhizosphere community structure, overriding the petroleum influence. Moreover, when exposed to petroleum contamination, the distinct salt marsh microbial communities responded similarly with (i) increased abundance, (ii) changes in structure, and (iii) decreased diversity. Communities, particularly those associated to J. maritimus and P. australis roots displayed a potential to degrade petroleum hydrocarbons, with degradation percentages between 15% and 41%, depending on sediment type and nutritional conditions. In conclusion, distinct salt marsh microbial communities responded similarly to petroleum contamination, but presented different pace, nutritional requirements, and potential for its biodegradation, which should be taken into account when developing bioremediation strategies.

  19. Genetic and epigenetic differences associated with environmental gradients in replicate populations of two salt marsh perennials.

    PubMed

    Foust, C M; Preite, V; Schrey, A W; Alvarez, M; Robertson, M H; Verhoeven, K J F; Richards, C L

    2016-04-01

    While traits and trait plasticity are partly genetically based, investigating epigenetic mechanisms may provide more nuanced understanding of the mechanisms underlying response to environment. Using AFLP and methylation-sensitive AFLP, we tested the hypothesis that differentiation to habitats along natural salt marsh environmental gradients occurs at epigenetic, but not genetic loci in two salt marsh perennials. We detected significant genetic and epigenetic structure among populations and among subpopulations, but we found multilocus patterns of differentiation to habitat type only in epigenetic variation for both species. In addition, more epigenetic than genetic loci were correlated with habitat in both species. When we analysed genetic and epigenetic variation simultaneously with partial Mantel, we found no correlation between genetic variation and habitat and a significant correlation between epigenetic variation and habitat in Spartina alterniflora. In Borrichia frutescens, we found significant correlations between epigenetic and/or genetic variation and habitat in four of five populations when populations were analysed individually, but there was no significant correlation between genetic or epigenetic variation and habitat when analysed jointly across the five populations. These analyses suggest that epigenetic mechanisms are involved in the response to salt marsh habitats, but also that the relationships among genetic and epigenetic variation and habitat vary by species. Site-specific conditions may also cloud our ability to detect response in replicate populations with similar environmental gradients. Future studies analysing sequence data and the correlation between genetic variation and DNA methylation will be powerful to identify the contributions of genetic and epigenetic response to environmental gradients.

  20. Implication of salt marsh foraminiferal assemblages in Suncheon Bay, South Korea

    NASA Astrophysics Data System (ADS)

    Jeong, Da Un; Lee, Yeon Gyu; Kang, Sora; Kim, Shin; Lee, Jung Sick

    2016-03-01

    Analyses of the compositions of benthic foraminifera and sediment, observations of tidal level and salinity, and a geographic survey of the tidal salt marsh in Suncheon Bay were conducted to examine the vertical distribution of foraminifera and evaluate their potential use for sea level studies. The salt marsh is composed mainly of fine-grained silty clay sediment and its salinity is below approximately 11 psu. The tidal current flows in the southwest-tonortheast direction with an average velocity of 26.57 cm/s. A total of 33 species of foraminifera (17 agglutinated and 16 calcareoushyaline) belonging to 24 genera was identified. The species diversity (1.1 on average) was relatively low. Dominant species were Ammonia beccarii, Miliammina fusca, Haplophragmoides wilberti, and Jadammina macrescens. Calcareous foraminifera (29.5%) were dominantly represented by the Ammonia beccarii assemblage, which characterized the region between mean tide level and mean low high water (MLHW). Agglutinated species (70.5%) were represented mostly by Miliammina fusca, Miliammina fusca-Haplophragmoides wilberti, and Haplophragmoides wilberti assemblages, which characterized the MLHW-mean high water (MHW), MHW-mean highest high water (MHHW), and MHHW-Approx. highest high water tide levels, respectively. In particular, the Haplophragmoides wilberti assemblage is believed to represent the highest elevation zone of foraminifera in the salt marshes of Suncheon Bay and is considered to be a reliable indicator of sea level as a result of its narrow vertical range.

  1. Evaluation of the ability of two plants for the phytoremediation of Cd in salt marshes

    NASA Astrophysics Data System (ADS)

    Nunes da Silva, Marta; Mucha, Ana P.; Rocha, A. Cristina; Silva, Carla; Carli, Carolina; Gomes, Carlos R.; Almeida, C. Marisa R.

    2014-03-01

    Several salt marsh plant species have shown to be able to uptake and concentrate metals in their tissues, showing potential for metal phytoremediation. However, studies in controlled conditions, mimicking as much as possible the plants natural environment, are needed to confirm this potential. For the present study, Juncus maritimus and Phragmites australis were collected in an estuary together with the sediment surrounding their roots, put in vessels and maintained in greenhouses under estuarine tidal simulation. After 3 weeks of acclimation, vessels were spiked with two different cadmium concentrations. After 2 months, cadmium was assessed in plant tissues and sediments. Results indicate that both plant species were able to uptake and translocate cadmium into their tissues, contributing also to retain it in rhizosediments and thus reducing the available amount of metal in the environment. Metal was preferentially accumulated in belowground structures, in concentrations not directly proportional to the amount of cadmium present in the sediment. Although no visual toxicity signs were observed, some defence mechanisms were triggered as observed by the changes in carotenoids, lignin, total soluble phenolic compounds and thiolic compounds levels, this response differing between plant species. This work shows that these two salt marsh plants can contribute for the retention of cadmium in salt marshes being useful for the phytostabilization of this metal in estuarine environments.

  2. Effect of spring-neap tide and evaporation on the salt dynamics in estuarine marshes

    NASA Astrophysics Data System (ADS)

    Zhang, Chenming; Shen, Chengji; Xin, Pei; Li, Ling

    2016-04-01

    Salt dynamics in estuarine tidal marshes are strongly associated with their intrinsic hydrological processes and ecological behaviors, which are not well understood. Numerical simulations were carried out to investigate the transport and distribution of pore-water and salt in a vertical cross section perpendicular to a tidal creek that subjects to spring-neap tide and evaporation. Vaporizing pore-water from the unsaturated soil surface with salt left in, the time-variant actual evaporation is affected by aerodynamic factors as well as soil conditions, including pore-water saturation, salinity and the thickness of salt precipitation above the soil surface (efflorescence). Different simulation cases were performed by adjusting the potential evaporation rate, tidal signals, marsh platform slope and soil properties. The simulation analysis indicates that, the tide-averaged soil salinity increases with the reduction of inundation period under a spring-neap tide cycle. As the salt accumulated by evaporation could leave soil from seepage back to seawater during ebbtide, the pore-water salinity at the surface within the tidal range remains below solubility. Coarse soils tend to have more intensified seepage flow and hence less pore-water salinity than fine soils. With the presence of hyper-saline soil and efflorescence, salt flat develops only in the area where capillary connection between evaporating surface and water table is maintained while tidal inundation absent. On the contrary, the supratidal marsh where hydrological connections are disrupted keeps a relatively low soil salinity (40-60 ppt) and pore-water saturation as evaporation remains low throughout the tidal cycles.

  3. Spatially structured environmental filtering of collembolan traits in late successional salt marsh vegetation.

    PubMed

    Widenfalk, Lina A; Bengtsson, Jan; Berggren, Åsa; Zwiggelaar, Krista; Spijkman, Evelien; Huyer-Brugman, Florrie; Berg, Matty P

    2015-10-01

    Both the environment and the spatial configuration of habitat patches are important factors that shape community composition and affect species diversity patterns. Species have traits that allow them to respond to their environment. Our current knowledge on environment to species traits relationships is limited in spite of its potential importance for understanding community assembly and ecosystem function. The aim of our study was to examine the relative roles of environmental and spatial variables for the small-scale variation in Collembola (springtail) communities in a Dutch salt marsh. We used a trait-based approach in combination with spatial statistics and variance partitioning, between environmental and spatial variables, to examine the important ecological factors that drive community composition. Turnover of trait diversity across space was lower than for species diversity. Most of the variation in community composition was explained by small-scale spatial variation in topography, on a scale of 4-6 m, most likely because it determines the effect of inundation, which restricts where habitat generalists can persist. There were only small pure spatial effects on species and trait diversity, indicating that biotic interactions or dispersal limitation probably were less important for structuring the community at this scale. Our results suggest that for springtails, life form (i.e. whether they live in the soil or litter or on the surface/in vegetation) is an important and useful trait to understand community assembly. Hence, using traits in addition to species identity when analysing environment-organism relationships results in a better understanding of the factors affecting community composition. PMID:26001605

  4. Tidal Flooding and Vegetation Patterns in a Salt Marsh Tidal Creek Imaged by Low-altitude Balloon Aerial Photography

    NASA Astrophysics Data System (ADS)

    White, S. M.; Madsen, E.

    2013-12-01

    Inundation of marsh surfaces by tidal creek flooding has implications for the headward erosion of salt marsh creeks, effect of rising sea levels, biological zonation, and marsh ecosystem services. The hydroperiod; as the frequency, duration, depth and flux of water across the marsh surface; is a key factor in salt marsh ecology, but remains poorly understood due to lack of data at spatial scales relevant to tracking the spatial movement of water across the marsh. This study examines how hydroperiod, drainage networks, and tidal creek geomorphology on the vegetation at Crab Haul Creek. Crab Haul Creek is the farthest landward tidal basin in North Inlet, a bar-built estuary in South Carolina. This study measures the hydroperiod in the headwaters Crab Haul Creek with normal and near-IR photos from a helium balloon Helikite at 75-100 m altitude. Photos provide detail necessary to resolve the waterline and delineate the hydroperiod during half tidal cycles by capturing the waterline hourly from the headwaters to a piezometer transect 260 meters north. The Helikite is an ideal instrument for local investigations of surface hydrology due to its maneuverability, low cost, ability to remain aloft for extended time over a fixed point, and ability to capture high-resolution images. Photographs taken from aircraft do not provide the detail necessary to determine the waterline on the marsh surface. The near-IR images make the waterline more distinct by increasing the difference between wet and dry ground. In the headwaters of Crab Haul Creek, individual crab burrows are detected by automated image classification and the number of crab burrows and their spatial density is tracked from January-August. Crab burrows are associated with the unvegetated region at the creek head, and we relate their change over time to the propagation of the creek farther into the tidal basin. Plant zonation is influenced by the hydroperiod, but also may be affected by salinity, water table depth, and

  5. Joint Geophysical and Hydrologic Constraints on Shallow Groundwater Flow Systems in Clastic Salt Marshes of the South Atlantic Bight

    NASA Astrophysics Data System (ADS)

    Ruppel, C.; Fulton, P.; Schultz, G. M.; Castillo, L.; Bartlett, J.; Sibley, S.

    2005-12-01

    Salt marsh systems play a critical role in buffering upland coastal areas from the influence of open saltwater bodies and in filtering contaminants that originate offshore or are flushed from uplands. For these reasons, it is important to understand the salt marsh hydrologic cycle, especially the interaction of groundwater and surface water across low-lying coastal fringes and the changes in physical, chemical, and ecological parameters across salinity gradients extending from upland to tidal creek to open water. For the past 5 years, we have conducted hydrogeophysical surveys (inductive EM and DC resistivity) and collected limited, coincident groundwater hydrologic data in clastic salt marshes throughout the South Atlantic Bight (SAB), stretching from South Carolina on the north to the Georgia-Florida border on the south. All of the marshes are dominated by Spartina and Juncus grasses and are cut by tidally-influenced creeks, but both the lithology and age of the marshes vary widely. For example, one highly homogeneous marsh study site has formed only within the past century, while most sites have existed for thousands of years and have laterally and vertically heterogeneous lithology. Geophysical images of the marsh subsurface and coincident monitoring of groundwater temperature, water level, and/or chemistry consistently show that marshes in the mixed energy environment of the middle part of the SAB (GCE LTER) tend to be dominated by submarsh discharge of freshwater to adjacent tidal creeks. In the South Carolina part of the SAB, we have greater evidence for seepage, particularly through biologically-created macropore networks and permeable sediment bodies that intersect tidal creeks. It is possible though that the South Carolina results are not so much 'universal' as reflective of local lithology. In a very young marsh near the Florida border, geophysical imaging implies a mixture of seepage and submarsh flow, and hydrologic data provide unequivocal proof that

  6. Effects of petroleum pollution on epiphytic salt marsh N{sub 2}-fixing communities

    SciTech Connect

    Piehler, M.; Swistak, J.; Pinckney, J.; Paerl, H.

    1995-12-31

    Increasing human activity in and around coastal waters of the US had led to elevations in both acute and chronic petroleum pollution. Petroleum inputs may have significant effects on Spartina altemiflora marshes, which are widespread on the east coast of the US and play an integral role in coastal nutrient cycling and trophodynamics. Because productivity and decomposition are often N limited in these systems, N{sub 2}-fixation may be an important source of erogenous N. Epiphytic N{sub 2}-fixing cyanobacterial communities occur on Spartina stems throughout coastal salt marshes. Short-term (3 hour) incubations of standing dead Spartina stems in creek water amended with weathered diesel fuel led to a reduction in N{sub 2}-fixation rates relative to natural rates. Lower level diesel fuel additions (between 0.33% and 0.0167% v/v) had either no significant effect or led to increases in acetylene reduction rates. Reduction of epiphytic N{sub 2}-fixation on Spartina stems by acute petroleum pollution could have several implications for salt marsh functioning including, reduction in prey for resident macrofauna and magnification of N limitation in the system. The fact that N{sub 2}-fixation is not completely inhibited, even at high levels of petroleum pollution, should be considered when formulating remedial strategies for petroleum spills in salt marshes. Removal of Spartina by burning or cutting may be counter-productive in that it eliminates an important functional component of the microbial community that may facilitate pollution assimilation. Efforts are currently underway to assess the effect of chronic petroleum pollution on this N{sub 2}-fixing community.

  7. Early diagenesis of lignin-associated phenolics in the salt marsh grass Spartina alterniflora

    SciTech Connect

    Haddad, R.I.; Martens, C.S. ); Newell, S.Y. ); Fallon, R.D. )

    1992-10-01

    The predepositional stability of lignin in the salt marsh cordgrass Spartina alterniflora was examined in two different degradation studies: one was a traditional litterbag study carried out using post-senescent brown leaves in a North Carolina marsh creek, and the other was a study in which senescing, standing plants were tagged and allowed to undergo in situ degradation in a Sapelo Island, Georgia, salt marsh. Based on results from lignin oxidation product (LOP) analysis of leaves, lignin in the S. alterniflora was shown to be significantly degraded in both studies, with 13 [plus minus] 2% and 25 [plus minus] 12% of the total lignin mass loss occurring over the 496-day litterbag and 146-day tagged studies, respectively. A comparison of the results from both studies suggests that most of the calculated lignin loss (> 90%) occurs early in the degradation history of the plant, with a significant portion occurring while the plant is still standing in the salt marsh. Further detailed evaluation of this loss demonstrates that selective lignin degradation occurs in S. alterniflora, deriving from the preferential loss of labile lignin moieties. Based on measured changes in both the lignin mass loss and the LOP acid/aldehyde ratio, as well as evidence suggesting that degradation occurred under oxic conditions, it is proposed that aromatic ring cleavage was the predominant mechanism of lignin degradation in both studies. In light of these results and those from other recent lignin degradation studies, the authors discuss the geochemical consequences regarding the usefulness of lignin oxidation products as quantitative tracers of vascular plant-derived organic matter being transported, deposited, and buried in aquatic environments.

  8. Impact of exposure of crude oil and dispersant (COREXIT® EC 9500A) on denitrification and organic matter mineralization in a Louisiana salt marsh sediment.

    PubMed

    Shi, Rujie; Yu, Kewei

    2014-08-01

    In response to the 2010 oil spill from the explosion of the Deepwater Horizon oil rig in the Gulf of Mexico, this experiment aims to study the ecological impact of the crude oil and dispersant (COREXIT® EC 9500A) in a coastal salt marsh ecosystem. The marsh sediment was incubated under an anaerobic condition with exposure to the crude oil or/and dispersant. The experiments were conducted in two continuous phases of nitrate addition to study denitrification potential using acetylene blockage technique and organic matter mineralization potential indicated by CO2 production in the sediment. Results show that the oil slightly (with no statistical significance p>0.05) increased both the denitrification and organic matter mineralization activities, likely due to oil components serving as additional organic matter. In contrast, the dispersant significantly (p<0.05) inhibited denitrification, but stimulated organic matter mineralization activities in the sediment due to unknown mechanisms. As a consequence, redox potentials (Eh) were much lower in the dispersant treated systems. The ecological impacts from the dispersant exposure may come from two fronts. First, loss of organic matter from the coastal marsh will threaten the long-term stability of the ecosystem, and the decrease in denitrification activity will weaken the N removal efficiency. Secondly, more reducing conditions developed by the dispersant exposure will likely preserve the oil in the ecosystem for an extended period of time due to weaker oil biodegradation under anaerobic conditions. PMID:24582034

  9. Impact of exposure of crude oil and dispersant (COREXIT® EC 9500A) on denitrification and organic matter mineralization in a Louisiana salt marsh sediment.

    PubMed

    Shi, Rujie; Yu, Kewei

    2014-08-01

    In response to the 2010 oil spill from the explosion of the Deepwater Horizon oil rig in the Gulf of Mexico, this experiment aims to study the ecological impact of the crude oil and dispersant (COREXIT® EC 9500A) in a coastal salt marsh ecosystem. The marsh sediment was incubated under an anaerobic condition with exposure to the crude oil or/and dispersant. The experiments were conducted in two continuous phases of nitrate addition to study denitrification potential using acetylene blockage technique and organic matter mineralization potential indicated by CO2 production in the sediment. Results show that the oil slightly (with no statistical significance p>0.05) increased both the denitrification and organic matter mineralization activities, likely due to oil components serving as additional organic matter. In contrast, the dispersant significantly (p<0.05) inhibited denitrification, but stimulated organic matter mineralization activities in the sediment due to unknown mechanisms. As a consequence, redox potentials (Eh) were much lower in the dispersant treated systems. The ecological impacts from the dispersant exposure may come from two fronts. First, loss of organic matter from the coastal marsh will threaten the long-term stability of the ecosystem, and the decrease in denitrification activity will weaken the N removal efficiency. Secondly, more reducing conditions developed by the dispersant exposure will likely preserve the oil in the ecosystem for an extended period of time due to weaker oil biodegradation under anaerobic conditions.

  10. Greenhouse Gas Fluxes from Salt Marshes Exposed to Chronic Nutrient Enrichment.

    PubMed

    Chmura, Gail L; Kellman, Lisa; van Ardenne, Lee; Guntenspergen, Glenn R

    2016-01-01

    We assessed the impact of nutrient additions on greenhouse gas fluxes using dark static chambers in a microtidal and a macrotidal marsh along the coast of New Brunswick, Canada approximately monthly over a year. Both were experimentally fertilized for six years with varying levels of N and P. For unfertilized, N and NPK treatments, average yearly CO2 emissions (which represent only respiration) at the microtidal marsh (13, 19, and 28 mmoles CO2 m(-2) hr(-1), respectively) were higher than at the macrotidal marsh (12, 15, and 19 mmoles m(-2) hr(-1), respectively, with a flux under the additional high N/low P treatment of 21 mmoles m(-2) hr(-1)). Response of CH4 to fertilization was more variable. At the macrotidal marsh average yearly fluxes were 1.29, 1.26, and 0.77 μmol CH4 m(-2) hr(-1) with control, N, and NPK treatments, respectively and 1.21 μmol m(-2) hr(-1) under high N/low P treatment. At the microtidal marsh CH4 fluxes were 0.23, 0.16, and -0.24 μmol CH4 m(-2) hr(-1) in control, N, and NPK and treatments, respectively. Fertilization changed soils from sinks to sources of N2O. Average yearly N2O fluxes at the macrotidal marsh were -0.07, 0.08, and 1.70, μmol N2O m(-2) hr(-1) in control, N, NPK and treatments, respectively and 0.35 μmol m(-2) hr(-1) under high N/low P treatment. For the control, N, and NPK treatments at the microtidal marsh N2O fluxes were -0.05, 0.30, and 0.52 μmol N2O m(-2) hr(-1), respectively. Our results indicate that N2O fluxes are likely to vary with the source of pollutant nutrients but emissions will be lower if N is not accompanied by an adequate supply of P (e.g., atmospheric deposition vs sewage or agricultural runoff). With chronic fertilization the global warming potential of the increased N2O emissions may be enough to offset the global cooling potential of the C sequestered by salt marshes.

  11. Greenhouse gas fluxes from salt marshes exposed to chronic nutrient enrichment

    USGS Publications Warehouse

    Chmura, Gail L.; Kellman, Lisa; van Ardenne, Lee; Guntenspergen, Glenn R.

    2016-01-01

    We assessed the impact of nutrient additions on greenhouse gas fluxes using dark static chambers in a microtidal and a macrotidal marsh along the coast of New Brunswick, Canada approximately monthly over a year. Both were experimentally fertilized for six years with varying levels of N and P. For unfertilized, N and NPK treatments, average yearly CO2 emissions (which represent only respiration) at the microtidal marsh (13, 19, and 28 mmoles CO2 m-2 hr-1, respectively) were higher than at the macrotidal marsh (12, 15, and 19 mmoles m-2 hr-1, respectively, with a flux under the additional high N/low P treatment of 21 mmoles m-2 hr-1). Response of CH4 to fertilization was more variable. At the macrotidal marsh average yearly fluxes were 1.29, 1.26, and 0.77 μmol CH4 m-2 hr-1 with control, N, and NPK treatments, respectively and 1.21 μmol m-2 hr-1 under high N/low P treatment. At the microtidal marsh CH4fluxes were 0.23, 0.16, and -0.24 μmol CH4 m-2 hr-1 in control, N, and NPK and treatments, respectively. Fertilization changed soils from sinks to sources of N2O. Average yearly N2O fluxes at the macrotidal marsh were -0.07, 0.08, and 1.70, μmol N2O m-2 hr-1 in control, N, NPK and treatments, respectively and 0.35 μmol m-2 hr-1 under high N/low P treatment. For the control, N, and NPK treatments at the microtidal marsh N2O fluxes were -0.05, 0.30, and 0.52 μmol N2O m-2 hr-1, respectively. Our results indicate that N2O fluxes are likely to vary with the source of pollutant nutrients but emissions will be lower if N is not accompanied by an adequate supply of P (e.g., atmospheric deposition vs sewage or agricultural runoff). With chronic fertilization the global warming potential of the increased N2O emissions may be enough to offset the global cooling potential of the C sequestered by salt marshes.

  12. Greenhouse Gas Fluxes from Salt Marshes Exposed to Chronic Nutrient Enrichment.

    PubMed

    Chmura, Gail L; Kellman, Lisa; van Ardenne, Lee; Guntenspergen, Glenn R

    2016-01-01

    We assessed the impact of nutrient additions on greenhouse gas fluxes using dark static chambers in a microtidal and a macrotidal marsh along the coast of New Brunswick, Canada approximately monthly over a year. Both were experimentally fertilized for six years with varying levels of N and P. For unfertilized, N and NPK treatments, average yearly CO2 emissions (which represent only respiration) at the microtidal marsh (13, 19, and 28 mmoles CO2 m(-2) hr(-1), respectively) were higher than at the macrotidal marsh (12, 15, and 19 mmoles m(-2) hr(-1), respectively, with a flux under the additional high N/low P treatment of 21 mmoles m(-2) hr(-1)). Response of CH4 to fertilization was more variable. At the macrotidal marsh average yearly fluxes were 1.29, 1.26, and 0.77 μmol CH4 m(-2) hr(-1) with control, N, and NPK treatments, respectively and 1.21 μmol m(-2) hr(-1) under high N/low P treatment. At the microtidal marsh CH4 fluxes were 0.23, 0.16, and -0.24 μmol CH4 m(-2) hr(-1) in control, N, and NPK and treatments, respectively. Fertilization changed soils from sinks to sources of N2O. Average yearly N2O fluxes at the macrotidal marsh were -0.07, 0.08, and 1.70, μmol N2O m(-2) hr(-1) in control, N, NPK and treatments, respectively and 0.35 μmol m(-2) hr(-1) under high N/low P treatment. For the control, N, and NPK treatments at the microtidal marsh N2O fluxes were -0.05, 0.30, and 0.52 μmol N2O m(-2) hr(-1), respectively. Our results indicate that N2O fluxes are likely to vary with the source of pollutant nutrients but emissions will be lower if N is not accompanied by an adequate supply of P (e.g., atmospheric deposition vs sewage or agricultural runoff). With chronic fertilization the global warming potential of the increased N2O emissions may be enough to offset the global cooling potential of the C sequestered by salt marshes. PMID:26914333

  13. Greenhouse Gas Fluxes from Salt Marshes Exposed to Chronic Nutrient Enrichment

    PubMed Central

    Chmura, Gail L.; Kellman, Lisa

    2016-01-01

    We assessed the impact of nutrient additions on greenhouse gas fluxes using dark static chambers in a microtidal and a macrotidal marsh along the coast of New Brunswick, Canada approximately monthly over a year. Both were experimentally fertilized for six years with varying levels of N and P. For unfertilized, N and NPK treatments, average yearly CO2 emissions (which represent only respiration) at the microtidal marsh (13, 19, and 28 mmoles CO2 m-2 hr-1, respectively) were higher than at the macrotidal marsh (12, 15, and 19 mmoles m-2 hr-1, respectively, with a flux under the additional high N/low P treatment of 21 mmoles m-2 hr-1). Response of CH4 to fertilization was more variable. At the macrotidal marsh average yearly fluxes were 1.29, 1.26, and 0.77 μmol CH4 m-2 hr-1 with control, N, and NPK treatments, respectively and 1.21 μmol m-2 hr-1 under high N/low P treatment. At the microtidal marsh CH4 fluxes were 0.23, 0.16, and -0.24 μmol CH4 m-2 hr-1 in control, N, and NPK and treatments, respectively. Fertilization changed soils from sinks to sources of N2O. Average yearly N2O fluxes at the macrotidal marsh were -0.07, 0.08, and 1.70, μmol N2O m-2 hr-1 in control, N, NPK and treatments, respectively and 0.35 μmol m-2 hr-1 under high N/low P treatment. For the control, N, and NPK treatments at the microtidal marsh N2O fluxes were -0.05, 0.30, and 0.52 μmol N2O m-2 hr-1, respectively. Our results indicate that N2O fluxes are likely to vary with the source of pollutant nutrients but emissions will be lower if N is not accompanied by an adequate supply of P (e.g., atmospheric deposition vs sewage or agricultural runoff). With chronic fertilization the global warming potential of the increased N2O emissions may be enough to offset the global cooling potential of the C sequestered by salt marshes. PMID:26914333

  14. Alterations to Tidal Marsh Carbon Cycling and Greenhouse Gas Exchange in Response to Sea-Level and Salt-Water Intrusion (Invited)

    NASA Astrophysics Data System (ADS)

    Weston, N. B.

    2013-12-01

    Tidal marshes are highly productive ecosystems with the potential to sequester large amounts of carbon. However, tidal wetlands may be sources of the powerful greenhouse gases (GHGs) methane (CH4) and nitrous oxide (N2O), which are produced via microbial metabolic processes. As global climate changes it is increasingly important to understand the factors that control ecosystem productivity, GHG fluxes, and potential feedbacks between global change factors, C cycling, and marsh resilience to sea-level rise (SLR). Field measurements were undertaken to quantify rates of GHG (CO2 and CH4) exchange rates, plant biomass, microbial sulfate reduction and methanogenesis rates, and soil biogeochemistry at three tidal wetland sites along the salinity gradient in the Delaware River Estuary over four years. Despite similar plant productivity between marsh types, differences in microbial processes largely determined the GHG source/sink status of the wetland types. Mesohaline salt-marshes consistently sequestered C (~300 g C m-2 yr-1), and due to negligible CH4 release, were also a GHG sink (~1350 g CO2-eq m-2 yr-1). In contrast, the TFM sequestered C (~350 g C m-2 yr-1) but because of appreciable release of CH4 from freshwater wetland soils was GHG neutral. The oligohaline marsh site experienced significant seasonal salt-water intrusion (SWI) in the late summer during the four year study period, resulting in major alterations to marsh C cycling. The oligohaline marsh did not sequester C (loss of ~45 g C m-2 yr-1) in part due to surprisingly high rates of CH4 release (190 g CH4 m-2 yr-1). The oligohaline marsh undergoing SWI was therefore a significant source of GHG to the atmosphere (~4000 g CO2-eq m-2 yr-1). These results indicate that SWI alters C cycling and GHG exchange in marsh systems, and may accelerate the decomposition of organic matter limiting the ability of marshes to accrete material and keep pace with SLR. The impacts of SWI on TFM soil C cycling were further

  15. Examining effects of sea level rise and marsh crabs on Spartina patens using mesocosms

    EPA Science Inventory

    Coastal salt marshes provide essential ecosystem services but face increasing threats from habitat loss, eutrophication, changing precipitation patterns, and accelerating rates of sea level rise (SLR). Recent studies have suggested that herbivory and burrowing by native salt mars...

  16. Inorganic and organic sulfur cycling in salt-marsh pore waters

    SciTech Connect

    Luther, G.W. III; Church, T.M.; Scudlark, J.R.; Cosman, M.

    1986-05-09

    Sulfur species in pore waters of the Great Marsh, Delaware, were analyzed seasonally by polarographic methods. The species determined (and their concentrations in micromoles per liter) included inorganic sulfides (less than or equal to3360), polysulfides (less than or equal to326), thiosulfate (less than or equal to104), tetrathionate (less than or equal to302), organic thiols (less than or equal to2411), and organic disulfides (less than or equal to139). Anticipated were bisulfide increases with depth due to sulfate reduction and subsurface sulfate excesses and pH minima, the result of a seasonal redox cycle. Unanticipated was the pervasive presence of thiols (for example, glutathione), particularly during periods of biological production. Salt marshes appear to be unique among marine systems in producing high concentrations of thiols. Polysulfides, thiosulfate, and tetrathionate also exhibited seasonal subsurface maxima. These results suggest a dynamic seasonal cycling of sulfur in salt marshes involving abiological and biological reactions and dissolved and solid sulfur species. The chemosynthetic turnover of pyrite to organic sulfur is a likely pathway for this sulfur cycling. Thus, material, chemical, and energy cycles in wetlands appear to be optimally synergistic.

  17. Field observations and morphodynamic modeling of spontaneous tidal network formation within a constructed salt marsh

    NASA Astrophysics Data System (ADS)

    D'Alpaos, A.; Lanzoni, S.; Marani, M.; Rinaldo, A.

    2007-12-01

    We have monitored and analyzed, through remote sensing and ancillary field surveys, the rapid (O(1) year) development of a tidal network within a newly established artificial salt marsh in the Venice Lagoon. After the construction of the salt marsh, a network of volunteer creeks established themselves away from an artificially constructed main channel (with mean and maximum annual headward-growth rates of 11 m/yr and 18 m/yr, respectively). The rapid formation of this system of tidal creeks provides a unique opportunity to test the reliability of a model of tidal network initiation and development, previously proposed by the authors. The restored marsh presents the characteristics of a controlled environment analogous to a large-scale field laboratory, as it allows comparison of the morphologic features of real and simulated network structures under the reasonable assumption of neglecting accretion and deposition processes over the timescales of observation. Our results compare favorably with observational evidence, showing that the model proves reasonably capable of reproducing the main features of the actual channel-network patterns. The model reproduces statistical network characteristics of eco-morphodynamic and hydrodynamic relevance and captures the dominant modes of the network-incision process.

  18. Spontaneous tidal network formation within a constructed salt marsh: Observations and morphodynamic modelling

    NASA Astrophysics Data System (ADS)

    D'Alpaos, Andrea; Lanzoni, Stefano; Marani, Marco; Bonometto, Andrea; Cecconi, Giovanni; Rinaldo, Andrea

    2007-11-01

    We have monitored and analyzed, through remote sensing and ancillary field surveys, the rapid (O(1) year) development of a tidal network within a newly established artificial salt marsh in the Venice Lagoon. After the construction of the salt marsh, a network of volunteer creeks established themselves away from an artificially constructed main channel (with mean and maximum annual headward-growth rates of 11 m/yr and 18 m/yr, respectively). The rapid formation of this system of tidal creeks provides a unique opportunity to test the reliability of a model of tidal network initiation and development, previously proposed by the authors. The restored marsh presents the characteristics of a controlled environment analogous to a large-scale field laboratory, as it allows comparison of the morphologic features of real and simulated network structures under the reasonable assumption of neglecting accretion and deposition processes over the timescales of observation. Our results compare favorably with observational evidence, showing that the model proves reasonably capable of reproducing the main features of the actual channel-network patterns. The model reproduces statistical network characteristics of eco-morphodynamic and hydrodynamic relevance and captures the dominant modes of the network-incision process.

  19. Potential uses of TerraSAR-X for mapping herbaceous halophytes over salt marsh and tidal flats

    NASA Astrophysics Data System (ADS)

    Lee, Yoon-Kyung; Park, Jeong-Won; Choi, Jong-Kuk; Oh, Yisok; Won, Joong-Sun

    2012-12-01

    This study presents a method and application results of mapping different halophytes over tidal flats and salt marshes using high resolution space-borne X-band synthetic aperture radar (SAR) that has been rarely used for salt marsh mapping. Halophytes in a salt marshes are sensitive to sea-level changes, sedimentation, and anthropogenic modifications. The alteration of the demarcations among halophyte species is an indicator of sea level and environmental changes within a salt marsh. The boundary of an herbaceous halophyte patch is, however, difficult to determine using remotely sensed data because of its sparseness. We examined the ecological status of the halophytes and their distribution changes using TerraSAR-X and optical data. We also determined the optimum season for halophyte mapping. An annual plant, Suaeda japonica (S. japonica), and a typical perennial salt marsh grass, Phragmites australis (P. australis), were selected for halophyte analysis. S. japonica is particularly sensitive to sea level fluctuation. Seasonal variation for the annual plant was more significant (1.47 dB standard deviation) than that for the perennial grass, with a pattern of lower backscattering in winter and a peak in the summer. The border between S. japonica and P. australis was successfully determined based on the distinctive X-band radar backscattering features. Winter is the best season to distinguish between the two different species, while summer is ideal for analyzing the distribution changes of annual plants in salt marshes. For a single polarization, we recommend using HH polarization, because it produces maximum backscattering on tidal flats and salt marshes. Our results show that high resolution SAR, such as TerraSAR-X and Cosmo-SkyMed, is an effective tool for mapping halophyte species in tidal flats and monitoring their seasonal variations.

  20. Nitrogen cycle of a typical Suaeda salsa marsh ecosystem in the Yellow River estuary.

    PubMed

    Mou, Xiaojie; Sun, Zhigao; Wang, Lingling; Wang, Chuanyuan

    2011-01-01

    The nitrogen (N) biological cycle of the Suaeda salsa marsh ecosystem in the Yellow River estuary was studied during 2008 to 2009. Results showed that soil N had significant seasonal fluctuations and vertical distribution. The N/P ratio (15.73 +/- 1.77) of S. salsa was less than 16, indicating that plant growth was limited by both N and P. The N absorption coefficient of S. salsa was very low (0.007), while the N utilization and cycle coefficients were high (0.824 and 0.331, respectively). The N turnover among compartments of S. salsa marsh showed that N uptake from aboveground parts and roots were 2.539 and 0.622 g/m2, respectively. The N translocation from aboveground parts to roots and from roots to soil were 2.042 and 0.076 g/m2, respectively. The N translocation from aboveground living bodies to litter was 0.497 g/m2, the annual N return from litter to soil was far less than 0.368 g/m2, and the net N mineralization in topsoil during the growing season was 0.033 g/m2. N was an important limiting factor in S. salsa marsh, and the ecosystem was classified as unstable and vulnerable. S. salsa was seemingly well adapted to the low-nutrient status and vulnerable habitat, and the nutrient enrichment due to N import from the Yellow River estuary would be a potential threat to the S. salsa marsh. Excessive nutrient loading might favor invasive species and induce severe long-term degradation of the ecosystem if human intervention measures were not taken. The N quantitative relationships determined in our study might provide a scientific basis for the establishment of effective measures.

  1. Composition of Fish Communities in a European Macrotidal Salt Marsh (the Mont Saint-Michel Bay, France)

    NASA Astrophysics Data System (ADS)

    Laffaille, P.; Feunteun, E.; Lefeuvre, J.-C.

    2000-10-01

    At least 100 fish species are known to be present in the intertidal areas (estuaries, mudflats and salt marshes) of Mont Saint-Michel Bay. These and other comparable shallow marine coastal waters, such as estuaries and lagoons, play a nursery role for many fish species. However, in Europe little attention has been paid to the value of tidal salt marshes for fishes. Between March 1996 and April 1999, 120 tides were sampled in a tidal creek. A total of 31 species were caught. This community was largely dominated by mullets ( Liza ramada represent 87% of the total biomass) and sand gobies ( Pomatoschistus minutus and P. lozanoi represent 82% of the total numbers). These species and also Gasterosteus aculeatus , Syngnathus rostellatus, Dicentrarchus labrax, Mugil spp., Liza aurata and Sprattus sprattus were the most frequent species (>50% of monthly frequency of occurrence). In Europe, salt marshes and their creeks are flooded only during high spring tides. So, fishes only invade this environment during short immersion periods, and no species can be considered as marsh resident. But, the salt marsh was colonized by fish every time the tide reached the creek, and during the short time of flood, dominant fishes fed actively and exploited the high productivity. Nevertheless, this study shows that there is little interannual variation in the fish community and there are three ' seasons ' in the fish fauna of the marsh. Marine straggler and marine estuarine dependent species colonize marshes between spring (recruitment period in the bay) and autumn before returning into deeper adjacent waters. Estuarine fishes are present all year round with maximum abundances in the end of summer. The presence of fishes confirms that this kind of wetland plays an important trophic and nursery role for these species. Differences in densities and stages distribution of these species into Mont Saint-Michel systems (tidal mudflats, estuaries and tidal salt marshes) can reduce the trophic

  2. The history of metals pollution in Narragansett Bay as recorded by salt-marsh sediments

    SciTech Connect

    Bricker, S.B.

    1990-01-01

    Sediment cores from 5 salt marshes from the head to the mouth of Narragansett Bay and an additional core from a lagoon on Block Island Sound were analyzed for [sup 210]Pb and for Fe, Mn, Cu, Pb, Cr, Zn, Ag, and Ni in order to examine the long-term variation of metal inputs to Narragansett Bay. The [sup 210]Pb results were used to determine accretion rates for each core. Distributions of Fe and Mn were used as indicators of chemical conditions of sediment cores and Cu, Pb, Cr, Zn, Ag, and Ni distributions with time were compared with known or estimated source inputs to examine the long-term variation of pollutant metal inputs to Narragansett Bay. At one location, duplicate cores were sampled to look at variability within a marsh. At another location, a high marsh, receiving predominantly atmospheric inputs and a low marsh, receiving waterborne and atmospheric inputs, were sampled so that atmospheric and tidal contributions could be determined. A comparison was made of the distributions of metals in bay cores and in the lagoon core. All the Rhode Island marshes accrete at rates equal to or greater than the local rise in sea level. Based on the [sup 210]Pb chronologies, pollutant metals began to increase in the mid to late 1800s, corresponding to coal burning emissions to the atmosphere. Steeper increases in the 1900s reflect industrial and sewage discharges. Maximum concentrations were reached in the 1950s and have declined almost continuously since then. Observed reductions were attributable to implementation of and improvements to sewage treatment, and controls on atmospheric emissions.

  3. Estimating shallow subsidence in microtidal salt marshes of the southeastern United States: Kaye and Barghoorn revisited

    USGS Publications Warehouse

    Cahoon, D.R.; Reed, D.J.; Day, J.W., Jr.

    1995-01-01

    Simultaneous measurements of vertical accretion and change in surface elevation relative to a shallow (3-5 m) subsurface datum were made in selected coastal salt marshes of Louisiana, Florida, and North Carolina to quantitatively test Kaye and Barghoorn's contention that vertical accretion is not a good surrogate for surface elevation change because of autocompaction of the substrate. Rates of subsidence of the upper 3-5 m of marsh substrate were calculated for each marsh as the difference between vertical accretion and elevation change measured with feldspar marker horizons and a sedimentation-erosion table. Surface elevation change was significantly lower than vertical accretion at each site after 2 years, indicating a significant amount of shallow subsidence had occurred, ranging from 0.45 to 4.90 cm. The highest rate of shallow subsidence occurred in the Mississippi delta. Results confirm Kaye and Barghoorn's contention that vertical accretion is not generally a good surrogate for elevation change because of processes occurring in the upper few meters of the substrate, including not only compaction but also apparently shrink-swell from water storage and/or plant production--decomposition at some sites. Indeed, surface elevation change was completely decoupled from vertical accretion at the Florida site. The assumption of a 1:1 relationship between accretionary and substrate processes. Consequently, the potential for coastal marsh submergence should be expressed as an elevation deficit based on direct measures of surface elevation change rather than accretion deficits. These findings also indicate the need for greater understanding of the influence of subsurface and small-scale hydrologic processes on marsh surface elevation.

  4. Long-term variation of fiddler crab populations in North Carolina salt marshes

    SciTech Connect

    Cammen, L.M.; Seneca, E.D.; Stroud, L.M.

    1984-06-01

    As part of the environmental monitoring of possible effects of the Brunswick nuclear power plant fiddle crab populations were sampled in several salt marshes in the lower Cape Fear River estuary, North Carolina for five years. Total biomass of the fiddler crabs Uca Pugnax and U. minax in four Spartina marshes declined by 65 to 70% between the summers of 1974-1975 and 1976-1977 with no significant decrease in population density; there was evidence of a recovery in summer of 1978 to the 1974-1975 levels. The cause of these fluctuations is unknown, but such a degree of variability in intertidal populations emphasizes the need for caution in using one or two-year baseline studies to evalute potential environmental impacts. 1 figure, 2 table.

  5. Effect of root metabolism on the post-depositional mobilization of mercury in salt marsh soils

    SciTech Connect

    Marins, R.V. |; Lacerda, L.D.; Goncalves, G.O.; Paiva, E.C. de

    1997-05-01

    Salt marsh soils are an efficient sink for trace metals associated with particulate material in tidal waters and have been proposed as monitors for trace metal contamination in coastal areas, on the basis that vertical profiles provide a record of loading rates. However, the complex nature of the biogeochemical processes occurring in these soils, may prevent this use, since post-depositional mobilization of some trace metals may occur, resulting in their release to pore water, vertical movement through the soil column and exchange with overlying waters. This paper presents and compares the vertical profiles of mercury in soil cores taken under a Spartina altermilflora marsh and in adjacent mod flats without plant cover to characterize the role played by this plant on the post-depositional movement of mercury through the soil and on the possibility of using such profiles as indicators of mercury loading rates in coastal areas. 19 refs., 1 fig., 1 tab.

  6. Alteration of a Salt Marsh Bacterial Community by Fertilization with Sewage Sludge

    PubMed Central

    Hamlett, Nancy V.

    1986-01-01

    The effects of long-term fertilization with sewage sludge on the aerobic, chemoheterotrophic portion of a salt marsh bacterial community were examined. The study site in the Great Sippewissett Marsh, Cape Cod, Mass., consisted of experimental plots that were treated with different amounts of commercial sewage sludge fertilizer or with urea and phosphate. The number of CFUs, percentage of mercury- and cadmium-resistant bacteria, and percentage of antibiotic-resistant bacteria were all increased in the sludge-fertilized plots. Preliminary taxonomic characterization showed that sludge fertilization markedly altered the taxonomic distribution and reduced diversity within both the total heterotrophic and the mercury-resistant communities. In control plots, the total heterotrophic community was fairly evenly distributed among taxa and the mercury-resistant community was dominated by Pseudomonas spp. In sludge-fertilized plots, both the total and mercury-resistant communities were dominated by a single Cytophaga sp. PMID:16347183

  7. Salt marsh retreat induced by wind waves: experiments, field and modeling

    NASA Astrophysics Data System (ADS)

    Solari, L.; Francalanci, S.; Bendoni, M.; Cappietti, L.

    2013-12-01

    Edge erosion of salt marshes due to surface waves and tide forcing is likely the chief mechanism that models marsh boundaries and by which salt marshes in worldwide areas are being lost. To address this problem, an experimental investigation in a laboratory flume and field measurements collected in the lagoon of Venice were conducted to understand the main processes controlling marsh edge retreat with a focus on the erosion mechanisms caused by the impact of wind waves in the case of various tidal levels. A physical model reproducing a salt marsh bank was built inside a long wave current flume where random surface waves have been generated according to a given wave spectrum. The physical model was constructed with the original soil of salt marshes from the Venice Lagoon, while the wave climate was reproduced according to field measurements. In order to reveal the effect of vegetation on bank stability, two identical banks were built but for the inclusion of halophytic plants. A first set of experiments was conducted reproducing only tidal waves, a second set with wind waves superimposed to the tide. A third set o f experiments were aimed to investigate the dynamic impact and transmission of the waves on and within the bank. The following quantities were collected during the experiments: water content and pore water pressure inside the bank, water levels and velocities at various distances from the bank, dynamic pressures on the bank edge surface and internal pressure fluctuations due to wave impact. Bank geometry profile and bottom topography at different times have also been collected to characterize the erosion rate with time and the evolution of bank retreat. Two types of mass failures were observed during the experiments: slides and toppling failures. The latter were most frequently observed failures, consisting in the toppling of blocks and were often the consequence of the presence of deep tension cracks. In most cases the impact of wind waves caused the

  8. Avian response to early tidal salt marsh restoration at former commercial salt evaporation ponds in San Francisco Bay, California, USA

    USGS Publications Warehouse

    Athearn, Nicole D.; Takekawa, John Y.; Shinn, Joel

    2009-01-01

    Restoration of former commercial salt evaporation ponds in the San Francisco Bay estuary is intended to reverse a severe decline (>79%) in tidal salt marshes. San Francisco Bay is a critical migratory stopover site and wintering area for shorebirds and waterfowl, and salt ponds are important high tide roosting and foraging areas. Conservation of past bird abundance is a stated goal of area restoration projects, and early adaptive management will be critical for achieving this objective. However, initial avian response at sites restored to tidal flow may not be indicative of long-term results. For example, winter shorebirds at a 529 ha pond breached in 2002 showed a marked increase in shorebird abundance following breaching. Shorebirds comprised 1% of area totals during 1999-2002 and increased to 46% during 2003-2008. These changes accompanied increased tidal range and sedimentation, but minimal vegetation establishment. Conversely, a fully vegetated, restored 216 ha pond in the same system consistently supported less than 2% of all waterbirds in the region. Early restoration may temporarily increase habitat, but managed ponds will be needed for long-term waterbird abundance within a restored pond-marsh system.

  9. Primary production of edaphic algal communities in a Mississippi salt marsh

    SciTech Connect

    Sullivan, M.J.; Moncreiff, C.A.

    1988-03-01

    Primary production rates of edaphic algae associated with the sediments beneath four monospecific canopies of vascular plants were determined over an annual cycle in a Mississippi salt marsh. The edaphic algal flora was dominated by small, motile pennate diatoms. Algal production (as measured by /sup 14/C uptake) was generally highest in spring-early summer and lowest in fall. Hourly rates ranged from a low of 1.4 mg C/m/sup 2/ in Juncus roemerianus Scheele to a high of 163 mg C/m/sup 2/ beneath the Scirpus olneyi Gray canopy. Stepwise multiple regressions identified a soil moisture index and chlorophyll a as the best environmental predictors of hourly production; light energy reaching the marsh surface and sediment and air temperature proved of little value. Adding the relative abundances of 33 diatom taxa to the set of independent variables only slightly increased R/sup 2/; however, virtually all variables selected were diatom taxa. R/sup 2/ was only 0.38 for the Spartina alterniflora Loisel. habitat but ranged from 0.70 to 0.87 for the remaining three vascular plant zones. Annual rates of algal production (g C/m/sup 2/) were estimated as follows: Juncus (28), Spartina (57), Distichlis spicata (L.) Greene (88), and Scirpus (151). The ratio of annual edaphic algal production to vascular plant net aerial production (EAP/VPP) was 10-12% for the first three habitats and 61% for Scirpus. Chlorophyll a concentrations, annual algal production rates, and EAP/VPP values were comparable to those determined in Texas, Delaware, and Massachusetts salt marshes but lower than those reported for Georgia and particularly California marshes.

  10. Assessing the wildlife habitat value of New England salt marshes: II. Model testing and validation.

    PubMed

    McKinney, Richard A; Charpentier, Michael A; Wigand, Cathleen

    2009-07-01

    We tested a previously described model to assess the wildlife habitat value of New England salt marshes by comparing modeled habitat values and scores with bird abundance and species richness at sixteen salt marshes in Narragansett Bay, Rhode Island USA. As a group, wildlife habitat value assessment scores for the marshes ranged from 307-509, or 31-67% of the maximum attainable score. We recorded 6 species of wading birds (Ardeidae; herons, egrets, and bitterns) at the sites during biweekly survey. Species richness (r (2)=0.24, F=4.53, p=0.05) and abundance (r (2)=0.26, F=5.00, p=0.04) of wading birds significantly increased with increasing assessment score. We optimized our assessment model for wading birds by using Akaike information criteria (AIC) to compare a series of models comprised of specific components and categories of our model that best reflect their habitat use. The model incorporating pre-classification, wading bird habitat categories, and natural land surrounding the sites was substantially supported by AIC analysis as the best model. The abundance of wading birds significantly increased with increasing assessment scores generated with the optimized model (r (2)=0.48, F=12.5, p=0.003), demonstrating that optimizing models can be helpful in improving the accuracy of the assessment for a given species or species assemblage. In addition to validating the assessment model, our results show that in spite of their urban setting our study marshes provide substantial wildlife habitat value. This suggests that even small wetlands in highly urbanized coastal settings can provide important wildlife habitat value if key habitat attributes (e.g., natural buffers, habitat heterogeneity) are present.

  11. Temporal factors influencing killifish abundance and recruitment in Gulf of Mexico salt marshes

    NASA Astrophysics Data System (ADS)

    Lipcius, Romuald N.; Subrahmanyam, C. B.

    1986-01-01

    Killifish ( Fundulus grandis and F. similis ) were seined monthly for two years near the mounths of three tidal creeks in each of two north Florida salt marshes. Abundance patterns were identified by a combination of multivariate analyses and quantitative graphical techniques. Abundance (numbers and biomass) peaked in the summer and fall as successive waves of juveniles accumulated. Relative abundance of age groups that reached their second breeding and growing seasons was low; the largest individuals of both species were less than two years old. Most killifish reproduced frequently in their first year of life. Temporal abundance patterns were regulated significantly by tidal phase, water depth, water temperature, and dissolved oxygen, but not by salinity or percent cloud cover. There were no significant differences between populations in the various creeks and marshes. Killifish apparently moved over submerged marsh surfaces at high tide, then retreated to tidal creeks at low tide, resulting in high abundance near creek mouths at low tide. However, these tidal movements were modulated by water depth; regardless of tidal phase, abundance at creek mouths was correlated negatively with water depth, indicating that killifish remained in the salt marsh when its surface was inundated. Thus, tidal movements of killifish were flexible and influenced by environmental conditions producing variation in water depth (e.g. wind-driven effects). Abundance correlated positively with water temperature and dissolved oxygen, reflecting juvenile recruitment peaks during warmer seasons and increased recruitment in year 2 of this study when dissolved oxygen values were higher. In both abundance and recruitment, Fundulus grandis and F. similis responded similarly to varying temporal environmental conditions. Fundulus similis is now considered to be F. majalis by some authors (e.g. Relyea, 1983).

  12. Variability of intertidal foraminferal assemblages in a salt marsh, Oregon, USA

    USGS Publications Warehouse

    Milker, Yvonne; Horton, Benjamin P.; Nelson, Alan R.; Engelhart, Simon E.; Witter, Robert C.

    2015-01-01

    We studied 18 sampling stations along a transect to investigate the similarity between live (rose Bengal stained) foraminiferal populations and dead assemblages, their small-scale spatial variations and the distribution of infaunal foraminifera in a salt marsh (Toms Creek marsh) at the upper end of the South Slough arm of the Coos Bay estuary, Oregon, USA. We aimed to test to what extent taphonomic processes, small-scale variability and infaunal distribution influence the accuracy of sea-level reconstructions based on intertidal foraminifera. Cluster analyses have shown that dead assemblages occur in distinct zones with respect to elevation, a prerequisite for using foraminifera as sea-level indicators. Our nonparametric multivariate analysis of variance showed that small-scale spatial variability has only a small influence on live (rose Bengal stained) populations and dead assemblages. The dissimilarity was higher, however, between live (rose Bengal stained) populations in the middle marsh. We observed early diagenetic dissolution of calcareous tests in the dead assemblages. If comparable post-depositional processes and similar minor spatial variability also characterize fossil assemblages, then dead assemblage are the best modern analogs for paleoenvironmental reconstructions. The Toms Creek tidal flat and low marsh vascular plant zones are dominated by Miliammina fusca, the middle marsh is dominated by Balticammina pseudomacrescens and Trochammina inflata, and the high marsh and upland–marsh transition zone are dominated by Trochamminita irregularis. Analysis of infaunal foraminifera showed that most living specimens are found in the surface sediments and the majority of live (rose Bengal stained) infaunal specimens are restricted to the upper 10 cm, but living individuals are found to depths of 50 cm. The dominant infaunal specimens are similar to those in the corresponding surface samples and no species have been found living solely infaunally. The

  13. MAPPING AND MONITORING OF SALT MARSH VEGETATION AND TIDAL CHANNEL NETWORK FROM HIGH RESOLUTION IMAGERY (1975-2006). EXAMPLE OF THE MONT-SAINT-MICHEL BAY (FRANCE)

    NASA Astrophysics Data System (ADS)

    Puissant, A. P.; Kellerer, D.; Gluard, L.; Levoy, F.

    2009-12-01

    Coastal landscapes are severely affected by environmental and social pressures. Their long term development is controlled by both physical and anthropogenic factors, which spatial dynamics and interactions may be analysed by Earth Observation data. The Mont-Saint-Michel Bay (Normandy, France) is one of the European coastal systems with a very high tidal range (approximately 15m during spring tides) because of its geological, geomorphological and hydrodynamical contexts at the estuary of the Couesnon, Sée and Sélune rivers. It is also an important touristic place with the location of the Mont-Saint-Michel Abbey, and an invaluable ecosystem of wetlands forming a transition between the sea and the land. Since 2006, engineering works are performed with the objective of restoring the maritime character of the Bay. These works will lead to many changes in the spatial dynamics of the Bay which can be monitored with two indicators: the sediment budget and the wetland vegetation surfaces. In this context, the aim of this paper is to map and monitor the tidal channel network and the extension of the salt marsh vegetation formation in the tidal zone of the Mont-Saint-Michel Bay by using satellite images. The spatial correlation between the network location of the three main rivers and the development of salt marsh is analysed with multitemporal medium (60m) to high spatial resolution (from 10 to 30 m) satellite images over the period 1975-2006. The method uses a classical supervised algorithm based on a maximum likelihood classification of eleven satellites images. The salt-marsh surfaces and the tidal channel network are then integrated in a GIS. Results of extraction are assessed by qualitative (visual interpretation) and quantitative indicators (confusion matrix). The multi-temporal analysis between 1975 and 2006 highlights that in 1975 when the study area is 26000 ha, salt marshes cover 16% (3000ha), the sandflat (slikke) and the water represent respectively 59% and 25

  14. The Life Cycle of Entzia, an Agglutinated Foraminifer from the Salt Marshes in Transylvania

    NASA Astrophysics Data System (ADS)

    Kaminski, Michael; Telespan, Andreea; Balc, Ramona; Filipescu, Sorin; Varga, Ildiko; Görög, Agnes

    2013-04-01

    The small salt marshes associated with Miocene salt domes in Transylvania are host to a variety of marine organisms, including communities of halophytic plants as well as an agglutinated foraminifer that is normally found in coastal salt marshes worldwide. Originally described as the species Entzia tetrastoma by Daday (1884), the foraminifer is more widely known by the name Jadammina macrescens (Brady, 1870). Because the genus name Entzia has priority over Jadammina, the valid name of this taxon is Entzia macrescens (Brady, 1870). In 2007, we discovered a living population of Entzia inhabiting a small salt marsh just outside the town of Turda in central Transylvania, only a kilometer from the famous Maria Theresa Salt Mine. This is the first discovery of a living population of Entzia in Transylvania since the species was originally described in 1884. To determine whether or not the specimens we found represent a breeding population, samples were collected from the marsh on a monthly basis over the span of a year. This species can be found among the roots of the halophytic plants, in the uppermost one or two centimeters of the mud. Sediment samples were preserved in Vodka with Rose Bengal to distinguish living and dead specimens, and examined quantitatively. To document the life cycle of the species the following metrics were carried out: test size, abundance, number of chambers, ratio between live and dead specimens, and the diameter of the proloculus. An increase in the mean diameter of specimens was found from October to December. However the mean diameter decreased again in January, which suggests that asexual reproduction had apparently taken place. Small specimens again appeared in March, when sexual reproduction is presumed to have taken place. The median proloculus diameter was smallest in April and May, but the monthly changes in mean proloculus size within the population over the span of a year are not significant. However, specimens with largest

  15. The weathering of oil after the Deepwater Horizon oil spill: insights from the chemical composition of the oil from the sea surface, salt marshes and sediments

    NASA Astrophysics Data System (ADS)

    Liu, Zhanfei; Liu, Jiqing; Zhu, Qingzhi; Wu, Wei

    2012-09-01

    The oil released during the Deepwater Horizon (DWH) oil spill may have both short- and long-time impacts on the northern Gulf of Mexico ecosystems. An understanding of how the composition and concentration of the oil are altered by weathering, including chemical, physical and biological processes, is needed to evaluate the oil toxicity and impact on the ecosystem in the northern Gulf of Mexico. This study examined petroleum hydrocarbons in oil mousse collected from the sea surface and salt marshes, and in oil deposited in sediments adjacent to the wellhead after the DWH oil spill. Oil mousses were collected at two stations (OSS and CT, located 130 and 85 km away from the wellhead, respectively) in May 2010, and two sediment samples from stations SG and SC, within 6 km of the wellhead, in May 2011. We also collected oil mousse from salt marshes at Marsh Point (MP), Mississippi, 186 km away from the wellhead in July 2010. In these samples, n-alkanes, polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, BTEX (collective name of benzene, toluene, ethylbenzene and p-, m-, and o-xylenes), C3-benzenes and trace metals were measured to examine how the oil was altered chemically. The chemical analysis indicates that the oil mousses underwent different degrees of weathering with the pattern of OSS < CT < MP. This pattern is consistent with the projected oil mousse movement from the accident site to salt marshes. Also, the contents of trace metals Al, V, Cr, Fe, Mn, Ni, Co, Cu, As and Pb in the oil mousse generally increased along the way to the salt marshes, indicating that these trace metals were perhaps aggregated into the oil mousse during the transport. Petroleum hydrocarbon data reveal that the oil deposited in sediments underwent only light to moderate degradation one year after the DWH oil spill, as supported by the presence of short-chained n-alkanes (C10-C 15), BTEX and C 3-benzenes. The weathering of oil in sediment may result from biological degradation and

  16. The salt marsh vegetation spread dynamics simulation and prediction based on conditions optimized CA

    NASA Astrophysics Data System (ADS)

    Guan, Yujuan; Zhang, Liquan

    2006-10-01

    The biodiversity conservation and management of the salt marsh vegetation relies on processing their spatial information. Nowadays, more attentions are focused on their classification surveying and describing qualitatively dynamics based on RS images interpreted, rather than on simulating and predicting their dynamics quantitatively, which is of greater importance for managing and planning the salt marsh vegetation. In this paper, our notion is to make a dynamic model on large-scale and to provide a virtual laboratory in which researchers can run it according requirements. Firstly, the characteristic of the cellular automata was analyzed and a conclusion indicated that it was necessary for a CA model to be extended geographically under varying conditions of space-time circumstance in order to make results matched the facts accurately. Based on the conventional cellular automata model, the author introduced several new conditions to optimize it for simulating the vegetation objectively, such as elevation, growth speed, invading ability, variation and inheriting and so on. Hence the CA cells and remote sensing image pixels, cell neighbors and pixel neighbors, cell rules and nature of the plants were unified respectively. Taking JiuDuanSha as the test site, where holds mainly Phragmites australis (P.australis) community, Scirpus mariqueter (S.mariqueter) community and Spartina alterniflora (S.alterniflora) community. The paper explored the process of making simulation and predictions about these salt marsh vegetable changing with the conditions optimized CA (COCA) model, and examined the links among data, statistical models, and ecological predictions. This study exploited the potential of applying Conditioned Optimized CA model technique to solve this problem.

  17. Porewater evidence for a dynamic sedimentary iron cycle in salt marshes. [Spartina alterniflora

    SciTech Connect

    Giblin, A.E.; Howarth, R.W.

    1984-01-01

    Dynamic transformations of iron occur seasonally at Great Sippewissett Marsh, Massachusetts. Small changes in the dissolved iron concentration in prewater represent only a small fraction of the iron involved in transformation reactions during the year. During the growing season, salt marsh grasses oxidize the sediment, and a large percentage of sedimentary pyrite is converted to an oxidized iron mineral. Over the fall and winter there is a net increase in pyrite as the grass is anaerobically decomposed. When oxidation rates in summer are high enough to neutralize the alkalinity produced by sulfate reduction and substantially lower the pH, oxidized iron minerals become increasingly soluble and iron levels in the porewater increase. If large amounts of soluble iron are lost by tidal flushing, iron availability may limit pyrite formation in later years. Sulfide concentrations in the porewater would then increase, leading to depressed growth of Spartina alterniflora. For most of the year the porewaters of Great Sippewissett were undersaturated with respect to all iron monosulfide minerals and supersaturated with respect to pyrite (FeS/sub 2/). Thus pyrite formation at Great Sippewissett probably occurs directly by reaction of polysulfides with iron and not by reactions of FeS with elemental sulfur. Porewaters were always undersaturated with respect to manganese minerals. Porewaters taken from marshes at Sapelo Island, Georgia, in fall were supersaturated with respect to pyrite at all depths and appear to be saturated for iron monosulfides below 12 cm at all sites.

  18. Accumulation and distribution of trace metals within soils and the austral cordgrass Spartina densiflora in a Patagonian salt marsh.

    PubMed

    Idaszkin, Yanina L; Lancelotti, Julio L; Bouza, Pablo J; Marcovecchio, Jorge E

    2015-12-15

    Concentrations of Cd, Cu, Fe, Pb, and Zn were determined in soils and in below- and above-ground structures of Spartina densiflora in a Patagonian salt marsh (San Antonio, Río Negro, Argentina). Also, the relationship between trace metal concentrations in soils and plants was investigated to improve our knowledge regarding the ability of this plant species to take up and accumulate trace metals from the soil. Our results indicate that, within the studied salt marsh, soil trace metal concentrations follow a decreasing concentration gradient toward the sea. They show moderate pollution and a potentially negative biological effect in one site of the salt marsh. While below-ground structures reflect the soil metal concentration pattern, this is not so evident in above-ground concentrations. Also, S. densiflora is able to absorb a limited amount of metals present in the soil, the soil bioaccumulation factor being lower in sites where soil metal concentration is higher.

  19. Accumulation and distribution of trace metals within soils and the austral cordgrass Spartina densiflora in a Patagonian salt marsh.

    PubMed

    Idaszkin, Yanina L; Lancelotti, Julio L; Bouza, Pablo J; Marcovecchio, Jorge E

    2015-12-15

    Concentrations of Cd, Cu, Fe, Pb, and Zn were determined in soils and in below- and above-ground structures of Spartina densiflora in a Patagonian salt marsh (San Antonio, Río Negro, Argentina). Also, the relationship between trace metal concentrations in soils and plants was investigated to improve our knowledge regarding the ability of this plant species to take up and accumulate trace metals from the soil. Our results indicate that, within the studied salt marsh, soil trace metal concentrations follow a decreasing concentration gradient toward the sea. They show moderate pollution and a potentially negative biological effect in one site of the salt marsh. While below-ground structures reflect the soil metal concentration pattern, this is not so evident in above-ground concentrations. Also, S. densiflora is able to absorb a limited amount of metals present in the soil, the soil bioaccumulation factor being lower in sites where soil metal concentration is higher. PMID:26481413

  20. Effects of Natural and Anthropogenic Change on Habitat Use and Movement of Endangered Salt Marsh Harvest Mice

    PubMed Central

    Smith, Katherine R.; Barthman-Thompson, Laureen; Gould, William R.; Mabry, Karen E.

    2014-01-01

    The northern salt marsh harvest mouse (Reithrodontomys raviventris halicoetes) is an endangered species endemic to the San Francisco Bay Estuary. Using a conservation behavior perspective, we examined how salt marsh harvest mice cope with both natural (daily tidal fluctuations) and anthropogenic (modification of tidal regime) changes in natural tidal wetlands and human-created diked wetlands, and investigated the role of behavioral flexibility in utilizing a human-created environment in the Suisun Marsh. We used radio telemetry to determine refuge use at high tide, space use, and movement rates to investigate possible differences in movement behavior in tidal versus diked wetlands. We found that the vast majority of the time salt marsh harvest mice remain in vegetation above the water during high tides. We also found no difference in space used by mice during high tide as compared to before or after high tide in either tidal or diked wetlands. We found no detectable difference in diurnal or nocturnal movement rates in tidal wetlands. However, we did find that diurnal movement rates for mice in diked wetlands were lower than nocturnal movement rates, especially during the new moon. This change in movement behavior in a relatively novel human-created habitat indicates that behavioral flexibility may facilitate the use of human-created environments by salt marsh harvest mice. PMID:25310800

  1. Effects of natural and anthropogenic change on habitat use and movement of endangered salt marsh harvest mice.

    PubMed

    Smith, Katherine R; Barthman-Thompson, Laureen; Gould, William R; Mabry, Karen E

    2014-01-01

    The northern salt marsh harvest mouse (Reithrodontomys raviventris halicoetes) is an endangered species endemic to the San Francisco Bay Estuary. Using a conservation behavior perspective, we examined how salt marsh harvest mice cope with both natural (daily tidal fluctuations) and anthropogenic (modification of tidal regime) changes in natural tidal wetlands and human-created diked wetlands, and investigated the role of behavioral flexibility in utilizing a human-created environment in the Suisun Marsh. We used radio telemetry to determine refuge use at high tide, space use, and movement rates to investigate possible differences in movement behavior in tidal versus diked wetlands. We found that the vast majority of the time salt marsh harvest mice remain in vegetation above the water during high tides. We also found no difference in space used by mice during high tide as compared to before or after high tide in either tidal or diked wetlands. We found no detectable difference in diurnal or nocturnal movement rates in tidal wetlands. However, we did find that diurnal movement rates for mice in diked wetlands were lower than nocturnal movement rates, especially during the new moon. This change in movement behavior in a relatively novel human-created habitat indicates that behavioral flexibility may facilitate the use of human-created environments by salt marsh harvest mice. PMID:25310800

  2. Using the radium quartet for evaluating groundwater input and water exchange in salt marshes

    SciTech Connect

    Moore, R.; Moore, W.S.

    1996-12-01

    The fluxes of {sup 226}Ra (half-life = 1600 years) and {sup 228}Ra (half-life = 5.7 years) from the North Inlet salt marsh to the sea are much larger than can be supported by decay of their Th parents in the surface marsh sediments. These fluxes are sustained almost entirely by groundwater flow through the marsh. An average groundwater flow of approximately 10 cm{sup 3} cm{sup -2} day{sup -1} is indicated if the groundwater activities we have measured are representative. The fluxes of {sup 223}Ra (half-life = 11.4 day) and {sup 224}Ra (half-life = 3.6 day) are factors of 22, and ten more than those expected from the flux of {sup 226}Ra. Groundwater also sustains most of the flux of the short-lived isotopes. The measured Ra activity ratio pattern in the marsh creeks matches the groundwater signature but is distinct from the pattern of the parent thorium isotopes in the sediment. We present a model to explain the anomalous distribution pattern of these isotopes. Despite their large throughput, the inventories of desorbable {sup 226}Ra and {sup 228}Ra in the top 15 cm sediment layer are very low. Nevertheless, the activities of {sup 226}Ra and {sup 228}Ra in the porewaters are large, indicating a low distribution coefficient ({approximately}10) for radium and a short retention time ({approximately}10 days) in the surface sediment layer. We surmise that groundwater flow may be a significant source of radium isotopes in the waters of shallow estuaries and coastal margins. This source must be recognized while considering mass balance of any tracer, be it radium, nutrients, other metals, or {delta}{sup 18}O. 11 refs., 2 figs., 4 tabs.

  3. Monitoring environmental controls on salt-marsh foraminifera in Tuckerton, NJ: implications for sea-level research

    NASA Astrophysics Data System (ADS)

    Walker, Jennifer; Khan, Nicole; Shaw, Timothy; Garcia-Artola, Ane; Dura, Tina; Horton, Ben

    2016-04-01

    Salt-marsh foraminifera have been widely used as proxies to reconstruct sea-level trends because their modern distribution is strongly linked with tidal elevation, and they are relatively abundant and have a high preservation potential in intertidal sediments. To determine former sea levels, the relation between contemporary foraminifera and their controlling environmental variables must be determined and the influence of post-depositional changes elucidated. Duration and frequency of tidal exposure, while the dominant control, is not the only environmental variable controlling the distribution of foraminifera. Complex interactions between organisms and their environment factor into foraminifera species distributions and these factors will vary over space and time. Here we present preliminary results of a spatial and temporal ecological study to monitor short-term, seasonal, and interannual variations in salt-marsh foraminifera assemblages along a salinity gradient of an intertidal zone of New Jersey, USA. The temporal nature is beneficial in recording potential lags in response to changes in environmental conditions compared with one-time sampling. Live foraminifera assemblage samples are compared with measured environmental parameters (porewater chemistry, porewater nutrients, tidal inundation, grain size) and experiments (bioturbation, overwash deposit, and infaunal) to determine the controlling environmental variables on foraminifera and how these variables and the foraminifera assemblages change through time. Ultimately, this multi-year monitoring experiment provides a more comprehensive understanding of environmental controls on salt-marsh foraminifera and will provide a background data set of salt-marsh foraminifera to compare with future studies and with sampling after large events such as storms. A greater understanding of salt-marsh foraminifera in their environment will contribute to sea-level reconstructions. Since sea-level records use the distribution

  4. Draft Genome Sequence of Bacillus sp. Strain NSP2.1, a Nonhalophilic Bacterium Isolated from the Salt Marsh of the Great Rann of Kutch, India

    PubMed Central

    Pal, Kamal Krishna; Sherathia, Dharmesh; Dalsania, Trupti; Savsani, Kinjal; Patel, Ilaxi; Sukhadiya, Bhoomika; Mandaliya, Mona; Thomas, Manesh; Ghorai, Sucheta; Vanpariya, Sejal; Rupapara, Rupal; Rawal, Priya; Saxena, Anil Kumar

    2013-01-01

    The 5.52-Mbp draft genome sequence of Bacillus sp. strain NSP2.1, a nonhalophilic bacterium isolated from the salt marsh of the Great Rann of Kutch, India, is reported here. An analysis of the genome of this organism will facilitate the understanding of its survival in the salt marsh. PMID:24158559

  5. Physical Stress, Not Biotic Interactions, Preclude an Invasive Grass from Establishing in Forb-Dominated Salt Marshes

    PubMed Central

    He, Qiang; Cui, Baoshan; An, Yuan

    2012-01-01

    Background Biological invasions have become the focus of considerable concern and ecological research, yet the relative importance of abiotic and biotic factors in controlling the invasibility of habitats to exotic species is not well understood. Spartina species are highly invasive plants in coastal wetlands; however, studies on the factors that control the success or failure of Spartina invasions across multiple habitat types are rare and inconclusive. Methodology and Principal Findings We examined the roles of physical stress and plant interactions in mediating the establishment of the smooth cordgrass, Spartina alterniflora, in a variety of coastal habitats in northern China. Field transplant experiments showed that cordgrass can invade mudflats and low estuarine marshes with low salinity and frequent flooding, but cannot survive in salt marshes and high estuarine marshes with hypersaline soils and infrequent flooding. The dominant native plant Suaeda salsa had neither competitive nor facilitative effects on cordgrass. A common garden experiment revealed that cordgrass performed significantly better when flooded every other day than when flooded weekly. These results suggest that physical stress rather than plant interactions limits cordgrass invasions in northern China. Conclusions and Significance We conclude that Spartina invasions are likely to be constrained to tidal flats and low estuarine marshes in the Yellow River Delta. Due to harsh physical conditions, salt marshes and high estuarine marshes are unlikely to be invaded. These findings have implications for understanding Spartina invasions in northern China and on other coasts with similar biotic and abiotic environments. PMID:22432003

  6. Potential of phytoremediation for the removal of petroleum hydrocarbons in contaminated salt marsh sediments.

    PubMed

    Ribeiro, Hugo; Mucha, Ana P; Almeida, C Marisa R; Bordalo, Adriano A

    2014-05-01

    Degradation of petroleum hydrocarbons in colonized and un-colonized sediments by salt marsh plants Juncus maritimus and Phragmites australis collected in a temperate estuary was investigated during a 5-month greenhouse experiment. The efficiency of two bioremediation treatments namely biostimulation (BS) by the addition of nutrients, and bioaugmentation (BA) by addition of indigenous microorganisms was tested in comparison with hydrocarbon natural attenuation in un-colonized and with rhizoremediation in colonized sediments. Hydrocarbon degrading microorganisms and root biomass were assessed as well as hydrocarbon degradation levels. During the study, hydrocarbon degradation in un-colonized sediments was negligible regardless of treatments. Rhizoremediation proved to be an effective strategy for hydrocarbon removal, yielding high rates in most experiments. However, BS treatments showed a negative effect on the J. maritimus potential for hydrocarbon degradation by decreasing the root system development that lead to lower degradation rates. Although both plants and their associated microorganisms presented a potential for rhizoremediation of petroleum hydrocarbons in contaminated salt marsh sediments, results highlighted that nutrient requirements may be distinct among plant species, which should be accounted for when designing cleanup strategies.

  7. Population variation affects interactions between two California salt marsh plant species more than precipitation.

    PubMed

    Noto, Akana E; Shurin, Jonathan B

    2016-02-01

    Species that occur along broad environmental gradients often vary in phenotypic traits that make them better adapted to local conditions. Variation in species interactions across gradients could therefore be due to either phenotypic differences among populations or environmental conditions that shift the balance between competition and facilitation. To understand how the environment (precipitation) and variation among populations affect species interactions, we conducted a common garden experiment using two common salt marsh plant species, Salicornia pacifica and Jaumea carnosa, from six salt marshes along the California coast encompassing a large precipitation gradient. Plants were grown alone or with an individual of the opposite species from the same site and exposed to one of three precipitation regimes. J. carnosa was negatively affected in the presence of S. pacifica, while S. pacifica was facilitated by J. carnosa. The strength of these interactions varied by site of origin but not by precipitation treatment. These results suggest that phenotypic variation among populations can affect interaction strength more than environment, despite a threefold difference in precipitation. Geographic intraspecific variation may therefore play an important role in determining the strength of interactions in communities.

  8. Physiological Diversity of the Rhizosphere Diazotroph Assemblages of Selected Salt Marsh Grasses

    PubMed Central

    Bagwell, Christopher E.; Piceno, Yvette M.; Ashburne-Lucas, Amy; Lovell, Charles R.

    1998-01-01

    Rhizosphere diazotroph assemblages of salt marsh grasses are thought to be influenced by host plant species and by a number of porewater geochemical parameters. Several geochemical variables can adversely affect plant productivity and spatial distributions, resulting in strong zonation of plant species and growth forms. This geochemically induced stress may also influence the species compositions and distributions of rhizosphere diazotroph assemblages, but little is currently known about these organisms. The diversity and key physiological features of culturable, O2-tolerant rhizosphere diazotrophs associated with the tall and short growth forms of Spartina alterniflora and with Juncus roemerianus were examined. A total of 339 gram-negative strains were isolated by a root stab culture approach and morphologically and physiologically characterized by using API and BIOLOG tests. Eighty-six distinct groups composed of physiologically similar strains were identified. Of these groups, 72% were shown to be capable of N2 fixation through molecular analyses, and a representative strain was chosen from each diazotroph group for further characterization. Cluster and principal-components analysis of BIOLOG data allowed the designation of physiologically distinct strain groupings. Most of these groups were dominated by strains that were not identifiable to species on the basis of API or BIOLOG testing. Representatives of several families including the Enterobacteriaceae, Vibrionaceae, Azotobacteraceae, Spirillaceae, Pseudomonadaceae, and Rhizobiaceae were recovered, as well as strains with no clear taxonomic affiliations. This study identifies numerous potentially important physiological groups of the salt marsh diazotroph assemblage. PMID:9797277

  9. Interactions between salt marsh plants and Cu nanoparticles - Effects on metal uptake and phytoremediation processes.

    PubMed

    Andreotti, Federico; Mucha, Ana Paula; Caetano, Cátia; Rodrigues, Paula; Rocha Gomes, Carlos; Almeida, C Marisa R

    2015-10-01

    The increased use of metallic nanoparticles (NPs) raises the probability of finding NPs in the environment. A lot of information exists already regarding interactions between plants and metals, but information regarding interactions between metallic NPs and plants, including salt marsh plants, is still lacking. This work aimed to study interactions between CuO NPs and the salt marsh plants Halimione portulacoides and Phragmites australis. In addition, the potential of these plants for phytoremediation of Cu NPs was evaluated. Plants were exposed for 8 days to sediment elutriate solution doped either with CuO or with ionic Cu. Afterwards, total metal concentrations were determined in plant tissues. Both plants accumulated Cu in their roots, but this accumulation was 4 to 10 times lower when the metal was added in NP form. For P. australis, metal translocation occurred when the metal was added either in ionic or in NP form, but for H. portulacoides no metal translocation was observed when NPs were added to the medium. Therefore, interactions between plants and NPs differ with the plant species. These facts should be taken in consideration when applying these plants for phytoremediation of contaminated sediments in estuaries, as the environmental management of these very important ecological areas can be affected.

  10. Population variation affects interactions between two California salt marsh plant species more than precipitation.

    PubMed

    Noto, Akana E; Shurin, Jonathan B

    2016-02-01

    Species that occur along broad environmental gradients often vary in phenotypic traits that make them better adapted to local conditions. Variation in species interactions across gradients could therefore be due to either phenotypic differences among populations or environmental conditions that shift the balance between competition and facilitation. To understand how the environment (precipitation) and variation among populations affect species interactions, we conducted a common garden experiment using two common salt marsh plant species, Salicornia pacifica and Jaumea carnosa, from six salt marshes along the California coast encompassing a large precipitation gradient. Plants were grown alone or with an individual of the opposite species from the same site and exposed to one of three precipitation regimes. J. carnosa was negatively affected in the presence of S. pacifica, while S. pacifica was facilitated by J. carnosa. The strength of these interactions varied by site of origin but not by precipitation treatment. These results suggest that phenotypic variation among populations can affect interaction strength more than environment, despite a threefold difference in precipitation. Geographic intraspecific variation may therefore play an important role in determining the strength of interactions in communities. PMID:26481794

  11. Annual net ecosystem exchanges of carbon dioxide and methane from a temperate brackish marsh: should the focus of marsh restoration be on brackish environments?

    NASA Astrophysics Data System (ADS)

    Windham-Myers, L.; Anderson, F. E.; Bergamaschi, B. A.; Ferner, M. C.; Schile, L. M.; Spinelli, G.

    2015-12-01

    The exchange and transport of carbon in tidally driven, saline marsh ecosystems provide habitat and trophic support for coastal wildlife and fisheries, while potentially accumulating and storing carbon at some of the highest rates compared to other ecosystems. However, due to the predicted rise in sea level over the next century, the preservation and restoration of estuarine habitats is necessary to compensate for their expected decline. In addition, restoration of these marsh systems can also reduce the impacts of global climate change as they assimilate as much carbon as their freshwater counterparts, while emitting less methane due to the higher concentrations of sulfate in seawater. Unfortunately, in brackish marshes, with salinity concentrations less than 18 parts per thousand (ppt), simple relationships between methane production, salinity and sulfate concentrations are not well known. Here we present the net ecosystem exchange (NEE) of carbon dioxide and methane, as calculated by the eddy covariance method, from a brackish marsh ecosystem in the San Francisco Estuary where salinity ranges from oligohaline (0.5-5 ppt) to mesohaline (5-18 ppt) conditions. Daily rates of carbon dioxide and methane NEE ranged from approximately 10 gC-CO2 m-2 d-1 and 0 mgC-CH4 m-2 d-1, during the winter to -15 gC-CO2 m-2 d-1 and 30 mgC-CH4 m-2 d-1, in the summer growing season. A comparison between similar measurements made from freshwater wetlands in the Sacramento-San Joaquin Delta found that the daily rates of carbon dioxide NEE were similar, but daily rates of methane NEE were just a small fraction (0-15%). Our research also shows that the daily fluxes of carbon dioxide and methane at the brackish marsh were highly variable and may be influenced by the tidal exchanges of seawater. Furthermore, the observed decline in methane production from summer to fall may have resulted from a rise in salinity and/or a seasonal decline in water and air temperatures. Our research goals are

  12. Seed dispersal and seedling emergence in a created and a natural salt marsh on the Gulf of Mexico coast in Southwest Louisiana, U.S.A

    USGS Publications Warehouse

    Elsey-Quirk, T.; Middleton, B.A.; Proffitt, C.E.

    2009-01-01

    Early regeneration dynamics related to seed dispersal and seedling emergence can contribute to differences in species composition among a created and a natural salt marsh. The objectives of this study were to determine (1) whether aquatic and aerial seed dispersal differed in low and high elevations within a created marsh and a natural marsh and (2) whether seedling emergence was influenced by marsh, the presence of openings in the vegetation, and seed availability along the northern Gulf of Mexico coast. Aerial seed traps captured a greater quantity of seeds than aquatic traps. Several factors influenced aquatic and aerial seed dispersal in a created and a natural salt marsh, including distance from the marsh edge, cover of existing vegetation, and water depth. The natural marsh had a high seed density of Spartina alterniflora and Distichlis spicata, the low-elevation created marsh had a high seed density of S. alterniflora, and the high-elevation created marsh had a high seed density of Aster subulatus and Iva frutescens. The presence of adult plants and water depth above the marsh surface influenced seed density. In the natural marsh, openings in vegetation increased seedling emergence for all species, whereas in the low-elevation created marsh, S. alterniflora had higher seedling density under a canopy of vegetation. According to the early regeneration dynamics, the future vegetation in areas of the low-elevation created marsh may become similar to that in the natural marsh. In the high-elevation created marsh, vegetation may be upland fringe habitat dominated by high-elevation marsh shrubs and annual herbaceous species. ?? 2009 Society for Ecological Restoration International.

  13. Spatial variation of salt-marsh organic and inorganic deposition and organic carbon accumulation: Inferences from the Venice lagoon, Italy

    NASA Astrophysics Data System (ADS)

    Roner, M.; D'Alpaos, A.; Ghinassi, M.; Marani, M.; Silvestri, S.; Franceschinis, E.; Realdon, N.

    2016-07-01

    Salt marshes are ubiquitous features of the tidal landscape governed by mutual feedbacks among processes of physical and biological nature. Improving our understanding of these feedbacks and of their effects on tidal geomorphological and ecological dynamics is a critical step to address issues related to salt-marsh conservation and response to changes in the environmental forcing. In particular, the spatial variation of organic and inorganic soil production processes at the