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Sample records for salt marsh ecosystem

  1. Centuries of human-driven change in salt marsh ecosystems.

    PubMed

    Gedan, K Bromberg; Silliman, B R; Bertness, M D

    2009-01-01

    Salt marshes are among the most abundant, fertile, and accessible coastal habitats on earth, and they provide more ecosystem services to coastal populations than any other environment. Since the Middle Ages, humans have manipulated salt marshes at a grand scale, altering species composition, distribution, and ecosystem function. Here, we review historic and contemporary human activities in marsh ecosystems--exploitation of plant products; conversion to farmland, salt works, and urban land; introduction of non-native species; alteration of coastal hydrology; and metal and nutrient pollution. Unexpectedly, diverse types of impacts can have a similar consequence, turning salt marsh food webs upside down, dramatically increasing top down control. Of the various impacts, invasive species, runaway consumer effects, and sea level rise represent the greatest threats to salt marsh ecosystems. We conclude that the best way to protect salt marshes and the services they provide is through the integrated approach of ecosystem-based management. PMID:21141032

  2. Centuries of Human-Driven Change in Salt Marsh Ecosystems

    NASA Astrophysics Data System (ADS)

    Gedan, K. Bromberg; Silliman, B. R.; Bertness, M. D.

    2009-01-01

    Salt marshes are among the most abundant, fertile, and accessible coastal habitats on earth, and they provide more ecosystem services to coastal populations than any other environment. Since the Middle Ages, humans have manipulated salt marshes at a grand scale, altering species composition, distribution, and ecosystem function. Here, we review historic and contemporary human activities in marsh ecosystems—exploitation of plant products; conversion to farmland, salt works, and urban land; introduction of non-native species; alteration of coastal hydrology; and metal and nutrient pollution. Unexpectedly, diverse types of impacts can have a similar consequence, turning salt marsh food webs upside down, dramatically increasing top down control. Of the various impacts, invasive species, runaway consumer effects, and sea level rise represent the greatest threats to salt marsh ecosystems. We conclude that the best way to protect salt marshes and the services they provide is through the integrated approach of ecosystem-based management.

  3. 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)

  4. 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.

  5. Mercury Cycling in Salt Marsh Pond Ecosystems: Cape Cod, MA

    NASA Astrophysics Data System (ADS)

    Ganguli, P. M.; Gonneea, M. E.; Lamborg, C. H.; Kroeger, K. D.; Swarr, G.; Vadman, K. J.; Baldwin, S.; Brooks, T. W.; Green, A.

    2014-12-01

    We are measuring total mercury (HgT) and monomethylmercury (CH3Hg+ or MMHg) in pore water, surface water, and sediment cores from two salt marsh pond systems on the south shore of Cape Cod, MA to characterize the distribution of mercury species and to identify features that influence mercury speciation and transport. Sage Lot Pond is relatively undisturbed and has low nitrogen loading (12 kg ha-1 y-1). It is part of the Waquoit Bay National Estuarine Reserve and is surrounded by undeveloped wooded uplands. In contrast, Great Pond is highly impacted. Nitrogen loading to the site is elevated (600 kg ha-1 y-1) and the marsh is adjacent to a large residential area. In both systems, a 1 to 2 m organic-rich peat layer overlies the permeable sand aquifer. Groundwater in this region is typically oxic, where pore water within salt marsh peat is suboxic to anoxic. We hypothesize that redox gradients at the transition from the root zone to peat and at the peat-sand interface may provide habitat for MMHg-producing anaerobic bacteria. Preliminary results from a 2-m nearshore depth profile at Sage Lot Pond indicate HgT in groundwater within the sand aquifer occurred primarily in the > 0.2 μm fraction, with unfiltered concentrations exceeding 100 pM. Filtered (< 0.2 μm) HgT in groundwater was substantially lower (~ 5 pM). In contrast, HgT concentrations in filtered and unfiltered pore water within the peat layer were similar and ranged from about 2 to 3 pM. Complexation between mercury and dissolved organic carbon may account for the elevated fraction of filtered HgT in peat pore water. Although MMHg in both groundwater and pore water remained around 1 pM throughout our depth profile, we observed an increase in sediment MMHg (0.3 to 1.6 μg/kg) at the peat-sand interface. MMHg comprised ~50% of the HgT concentration in pore water suggesting mercury in the salt marsh peat is biologically available.

  6. Productivity and nutrient cycling in salt marshes: Contribution to ecosystem health

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    This study aimed to assess the contribution of different salt marsh halophytes ( Spartina maritima, Scirpus maritimus, Halimione portulacoides, Sarcocornia fruticosa, and Sarcocornia perennis) to nutrient cycling and sequestration in warm-temperate salt marshes. Carbon, nitrogen and phosphorus concentration in plant organs and rhizosediment, as well as plant biomass were monitored every two months during one year. Results show that the C retained in the rhizosediment does not seem to be species or site specific. However, some halophytes seem to have a higher contribution to retain C from external sources, namely S. perennis and S. maritima. Regarding N, halophytes colonizing the upper and middle marsh areas had the highest NBPP (net belowground primary production) as well as the retention of N in the rhizosediment. Yet, excluding S. maritimus, all halophytes seem to contribute to the retention of N from external sources. The P retained in the rhizosediment does not seem to be species or site specific. Still, only S. maritima colonizing the lower marsh areas, which also had comparatively lower NBPP, seem to have a higher contribution to retain P from external sources. Additionally, it seems that there is no relation between plants sequestration capacity for nutrients and plant photosynthetic pathway. This work shows that nutrient cycling and accumulation processes by salt marsh halophytes contribute to reduce eutrophication (N and P retention) and also to reduce atmospheric CO 2 (C retention), highlighting salt marsh ecosystems services and the crucial role of halophytes in maintaining ecosystem functions and health.

  7. DIEL FLUX OF DISSOLVED CARBOHYDRATE IN A SALT MARSH AND A SIMULATED ESTUARINE ECOSYSTEM

    EPA Science Inventory

    The concentrations of total dissolved carbohydrate (TCHO), monosaccharide (MCHO) and polysaccharide (PCHO) were followed over a total of ten diel cycles in a salt marsh and a 13 cu m seawater tank simulating an estuarine ecosystem. Their patterns are compared to those for total d...

  8. 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. PMID:22834380

  9. 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

  10. 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

  11. Ecosystem assembly rules: the interplay of green and brown webs during salt marsh succession.

    PubMed

    Schrama, Maarten; Berg, Matty P; Olff, Han

    2012-11-01

    Current theories about vegetation succession and food web assembly are poorly compatible, as food webs are generally viewed to be static, and succession is usually analyzed without the inclusion of higher trophic levels. In this study we present results from a detailed analysis of ecosystem assembly rules over a chronosequence of 100 years of salt marsh succession. First, using 13 yearlong observations on vegetation and soil parameters in different successional stages, we show that the space-for-time substitution is valid for this chronosequence. We then quantify biomass changes for all dominant invertebrate and vertebrate species across all main trophic groups of plants and animals. All invertebrate and vertebrate species were assigned to a trophic group according to feeding preference, and changes in trophic group abundance were quantified for seven different successional stages of the ecosystem. We found changes from a marine-fueled, decomposer-based (brown) food web in early stages to a more terrestrial, plant-based, herbivore-driven (green) food web in intermediate succession stages, and finally to a decomposer-based, terrestrial-driven food web in the latest stages. These changes were accompanied not only by an increase in live plant biomass and a leveling toward late succession but also by a constant increase in the amount of dead plant biomass over succession. Our results show that the structure and dynamics of salt marsh food webs cannot be understood except in light of vegetation succession, and vice versa. PMID:23236907

  12. 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

  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. 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.

  16. 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

  17. 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

  18. 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.

  19. 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 ...

  20. 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 ...

  1. 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

  2. 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.

  3. Mercury cycling and sequestration in salt marshes sediments: an ecosystem service provided by Juncus maritimus and Scirpus maritimus.

    PubMed

    Marques, B; Lillebø, A I; Pereira, E; Duarte, A C

    2011-07-01

    In this study two time scales were looked at: a yearlong study was completed, and a 180-day decay experiment was done. Juncus maritimus and Scirpus maritimus have different life cycles, and this seems to have implications in the Hg-contaminated salt marsh sediment chemical environment, namely Eh and pH. In addition, the belowground biomass decomposition rates were faster for J. maritimus, as well as the biomass turnover rates. Results show that all these species-specific factors have implications in the mercury dynamics and sequestration. Meaning that J. maritimus belowground biomass has a sequestration capacity for mercury per square metre approximately 4-5 times higher than S. maritimus, i.e., in S. maritimus colonized areas Hg is more extensively exchange between belowground biomass and the rhizosediment. In conclusion, J. maritimus seems to provide a comparatively higher ecosystem service through phytostabilization (Hg complexation in the rhizosediment) and through phytoaccumulation (Hg sequestration in the belowground biomass). PMID:21514707

  4. 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.

  5. 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

  6. 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

  7. 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

  8. 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.

  9. 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...

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

    PubMed Central

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

    2014-01-01

    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. PMID:24766277

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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)

  1. 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. PMID:23566036

  2. 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 ...

  3. 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...

  4. 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.

  5. 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...

  6. 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...

  7. 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.

  8. 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.

  9. 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

  10. 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.

  11. Potential for Carbon Sequestration in Transplanted Salt Marshes

    NASA Astrophysics Data System (ADS)

    O'Brien, C.; Davis, J.; Currin, C.

    2014-12-01

    The photosynthetic uptake of atmospheric carbon dioxide (CO2) by tidal salt marshes results in the long-term storage of carbon in the sediment. In recent decades, pressures such as land-use change and sea level rise have significantly reduced the global extent of salt marshes and increased the need for restoration projects. Restored salt marshes have been shown to provide many of the same ecological and economic benefits as natural marshes, including fish habitat, pollution filtration, and shoreline stabilization. Given the high carbon sequestration capacity of tidal marshes, carbon storage is likely an additional benefit of restoration; however, the degree to which restored marshes achieve equivalency with natural marshes in terms of carbon burial has not been well-defined. In this study, annual carbon sequestration rates in transplanted marshes were estimated and belowground carbon stocks were compared in transplanted versus natural marshes. Sediment cores were collected from five transplanted Spartina alterniflora marshes of known age (12-38 years old) in the Newport River Estuary, NC and from two natural marshes of unknown age. Organic matter content was estimated using the loss on ignition method and carbon content was estimated based on previously established relationships. In transplanted marshes, the rate of carbon sequestration in the top 30 cm decreased with marsh age and ranged from 76.70 g C/m2/yr (38 year old marsh) to 212.83 g C/m2/yr (12 year old marsh). The natural marshes contained significantly larger carbon stocks in the top 30 cm (4534.61 - 7790.18 g C m-2) than the transplanted marshes (1822.97 - 3798.62 g C m-2). However, the annual sequestration rates in the transplanted marshes are similar to those observed by others in natural marshes, and therefore it is likely that over time restored marshes are capable of accreting belowground carbon stocks equivalent to those found in natural marshes.

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. Hydrocarbon degradation potential of salt marsh plant-microorganisms associations.

    PubMed

    Ribeiro, Hugo; Mucha, Ana P; Almeida, C Marisa R; Bordalo, Adriano A

    2011-07-01

    Estuaries are often considered sinks for contaminants and the cleanup of salt marshes, sensitive ecosystems with a major ecological role, should be carried out by means of least intrusive approaches, such as bioremediation. This study was designed to evaluate the influence of plant-microorganisms associations on petroleum hydrocarbons fate in salt marshes of a temperate estuary (Lima River, NW Portugal). Sediments un-colonized and colonized (rhizosediments) by different plants (Juncus maritimus, Phragmites australis, Triglochin striata and Spartina patens) were sampled in four sites of the lower and middle estuary for hydrocarbon degrading microorganisms (HD), total cell counts (TCC) and total petroleum hydrocarbons (TPHs) assessment. In general, TPHs, HD and TCC were significantly higher (P < 0.05) in rhizosediments than in un-colonized sediments. Also recorded were differences on the abundance of hydrocarbon degraders among the rhizosediment of the different plants collected at the same site (J. maritimus < P. australis < T. striata), with statistically significant differences (P < 0.05) between J. maritimus and T. striata. Moreover, strong positive correlations-0.81 and 0.84 (P < 0.05), between biotic (HD) and abiotic (organic matter content) parameters and TPHs concentrations were also found. Our data clearly suggest that salt marsh plants can influence the microbial community, by fostering the development of hydrocarbon-degrading microbial populations in its rhizosphere, an effect observed for all plants. This effect, combined with the plant capability to retain hydrocarbons around the roots, points out that salt marsh plant-microorganisms associations may actively contribute to hydrocarbon removal and degradation in estuarine environments. PMID:21188477

  1. 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.

  2. 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.

  3. 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

  4. 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

  5. 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

  6. Influence of multiple stressors on the auto-remediation processes occurring in salt marshes.

    PubMed

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

    2011-07-01

    Due to increasing global population, salt marshes have been subjected to multiple stressors such as increasing nutrient loadings and historical contamination. In order to better understand how does the salt marsh plants auto-remediation capacity (phytoaccumulation of metals) is affected by cultural eutrophication, an experiment was performed under controlled conditions. Plants were exposure to equal metal concentrations (Zn, Cu, and Ni - micronutrients, and Cd - class B metal) simulating historical contamination and three different concentrations of nitrogen (nitrate) simulating steps of cultural eutrophication. According to our study, under the tested concentrations, cultural eutrophication does not seem to affect Zn, Cu and Ni phytoremediation of H. portulacoides, but the ecosystem service of Cd phytoremediation seems to be promoted. Nevertheless, Cd high toxicity and bioaccumulation should be taken into account, as well as the vulnerability of salt marsh ecosystems, whose reduction will have drastic consequences to the ecosystem health. PMID:21592533

  7. 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 ...

  8. 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 ...

  9. 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...

  10. 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.

  11. Large methyl halide emissions from south Texas salt marshes

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  12. 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

  13. 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.

  14. 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...

  15. 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.

  16. [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

  17. Salt marsh Claviceps purpurea in native and invaded Spartina marshes in Northern California

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The fungal pathogen Claviceps purpurea (subgroup G3) has a worldwide distribution on salt marsh Spartina species. In Northern California (US), native S. foliosa sustains high rates of infection by G3 C. purpurea in marshes north of the San Francisco Estuary. Invasive populations of S. alterniflora a...

  18. 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...

  19. 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

  20. OUTLINE OF A NEW APPROACH TO EVALUATE ECOLOGICAL INTEGRITY OF SALT MARSHES

    EPA Science Inventory

    The integrity of coastal salt marshes can be determined from the extent to which they provide key ecosystem services: food and habitat for fish and wildlife, good water quality, erosion and flood control, and recreation and cultural use. An outline of a new approach for linking e...

  1. 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...

  2. 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...

  3. 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...

  4. 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.

  5. Tropical salt marsh succession as sea-level indicator during Heinrich events

    NASA Astrophysics Data System (ADS)

    González, Catalina; Dupont, Lydie M.

    2009-05-01

    Centennial-millennial dynamics of tropical salt marsh vegetation are documented in the pollen record from marine core MD03-2622, Cariaco Basin, Venezuela, which spans the glacial period between 63 and 29 ka. Five rapid and abrupt expansions of salt marsh vegetation are linked with North Atlantic Heinrich events (HEs). Within each event, a recurrent pattern - starting with species of Chenopodiaceae, followed by grasses, and subsequently by Cyperaceae species - suggests a successional process that is determined by the close relationship between sea-level and community dynamics. The salt tolerant Chenopodiaceae, at the base of each sequence, indicate hypersaline intertidal environments, which were most likely promoted by extremely dry atmospheric conditions. Rapid sea-level rise characterizes the onset of HE stadials, causing erosion of marsh sediments, and continued recruitment of pioneer species (Chenopodiaceae), which are the only ones capable of tolerating the rapid rate of disturbance. Once, as sea-level drops or as rise decelerates, marsh plants are able to trap and stabilize sediments, favouring the establishment of more competitive species (graminoids). The increment of marsh height as a result of autochthonous sediment accumulation reduces the extent of hypersaline environments, and allows the establishment of mesohaline species. These results add to the scarce knowledge on tropical salt marsh ecosystems, and provide independent paleoclimatic evidence on sea-level changes occurring simultaneously with Antarctica climate variations.

  6. 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

  7. Tidal regime, salinity and salt marsh plant zonation

    NASA Astrophysics Data System (ADS)

    Silvestri, Sonia; Defina, Andrea; Marani, Marco

    2005-01-01

    Salt marsh morphology is known to be strongly correlated to vegetation patterns through a complex interplay of biological and physical processes. This paper presents the results of field surveys at several study salt marshes within the Venice Lagoon (Italy), which indicate that salt-marsh macrophyte species may indeed be associated with narrow ranges of soil topographic elevation. Statistical analyses show that several properties of the frequency distributions of halophytes presence are sensitive not only to variations in soil elevation, but also to the specific marsh considered. Through direct in situ sampling and by use of a finite-element hydrodynamic model the role of plant submersion duration and frequency in determining the observed variability of vegetation species is then studied. Measurements of soil salinity have also been performed at selected salt marshes to address its influence on vegetation occurrence. With implications for tidal marshes in general, the distribution of halophytes in the salt marshes considered is found not to be responding to simple rules dictated by the tidal cycle or to salinity, and that such factors, when singularly considered, cannot explain the observed spatial distribution of halophytes. On the basis of observations and modelling results it is thus concluded that a combination of multiple factors, likely dominated by saturated/unsaturated flow in the soil, may be responsible for the observed macrophyte distribution.

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

    NASA Astrophysics Data System (ADS)

    Solari, L.; Bendoni, M.; Mel, R.; Oumeraci, H.; Francalanci, S.; Lanzoni, S.

    2014-12-01

    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 that we are currently carrying out 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 0.4m), only one pin is employed. Significant wave height has been measured during three storm surges by means of pressure transducers (Pts). 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

  9. 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

  10. 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

  11. 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.

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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…

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. Salt marsh-atmosphere exchange of energy, water vapor, and carbon dioxide: Effects of tidal flooding and biophysical controls

    NASA Astrophysics Data System (ADS)

    Moffett, Kevan B.; Wolf, Adam; Berry, Joe A.; Gorelick, Steven M.

    2010-10-01

    The degree to which short-duration, transient floods modify wetland-atmosphere exchange of energy, water vapor, and carbon dioxide (CO2) is poorly documented despite the significance of flooding in many wetlands. This study explored the effects of transient floods on salt marsh-atmosphere linkages. Eddy flux, micrometeorological, and other field data collected during two tidal phases (daytime versus nighttime high tides) quantified the salt marsh radiation budget, surface energy balance, and CO2 flux. Analysis contrasted flooded and nonflooded and day and night effects. The salt marsh surface energy balance was similar to that of a heating-dominated sparse crop during nonflooded periods but similar to that of an evaporative cooling-dominated, well-watered grassy lawn during flooding. Observed increases in latent heat flux and decreases in net ecosystem exchange during flooding were proportional to flood depth and duration, with complete CO2 flux suppression occurring above some flood height less than the canopy height. Flood-induced changes in the salt marsh energy balance were dominated by changes in sensible heat flux, soil heat flux, and surface water heat storage. Parameters suitable for predicting the salt marsh surface energy balance were obtained by calibrating common models (e.g., Penman-Monteith, Priestley-Taylor, and pan coefficient). Biophysical controls on salt marsh-atmosphere exchange were identified following calibration of models describing the coupling of canopy photosynthesis and stomatal conductance in the salt marsh. The effects of flooding on salt marsh-atmosphere exchange are temporary but strongly affect the marsh water, carbon, and energy balance despite their short duration.

  10. 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.

  11. Does vegetation prevent wave erosion of salt marsh edges?

    PubMed Central

    Feagin, R. A.; Lozada-Bernard, S. M.; Ravens, T. M.; Möller, I.; Yeager, K. M.; Baird, A. H.

    2009-01-01

    This study challenges the paradigm that salt marsh plants prevent lateral wave-induced erosion along wetland edges by binding soil with live roots and clarifies the role of vegetation in protecting the coast. In both laboratory flume studies and controlled field experiments, we show that common salt marsh plants do not significantly mitigate the total amount of erosion along a wetland edge. We found that the soil type is the primary variable that influences the lateral erosion rate and although plants do not directly reduce wetland edge erosion, they may do so indirectly via modification of soil parameters. We conclude that coastal vegetation is best-suited to modify and control sedimentary dynamics in response to gradual phenomena like sea-level rise or tidal forces, but is less well-suited to resist punctuated disturbances at the seaward margin of salt marshes, specifically breaking waves. PMID:19509340

  12. Remote sensing salt marsh biomass and stress detection

    NASA Astrophysics Data System (ADS)

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

    A hand-held radiometer was used to gather spectral radiance data simulating bands 3, 4 and 5 of the Landsat-D Thematic Mapper. Variations in biomass of the salt marsh plant Spartina alterniflora were highly correlated to changes in spectral radiance expressed as the vegetation index or the infrared index. Negative stresses like increased soil salinity and increased concentrations of copper or zinc yielded reductions in biomass which were detected spectrally. Positive stresses like freshwater and sewage effluent additions produced an increase in biomass which also were detected using spectral data. The demonstrated detection of biomass from spectral data was expanded spatially and temporally to estimate net primary productivity of a salt marsh. Remote sensing estimates of production ranged from 5 to 20% of estimates from harvest data. Future applications of this biomass estimation technique, employing data gathered from satellite platforms and from the ground, are discussed for salt marsh systems.

  13. Coatal salt marshes and mangrove swamps in China

    NASA Astrophysics Data System (ADS)

    Yang, Shi-Lun; Chen, Ji-Yu

    1995-12-01

    Based on plant specimen data, sediment samples, photos, and sketches from 45 coastal crosssections, and materials from two recent countrywide comprehensive investigations on Chinese coasts and islands, this paper deals with China’s vegetative tidal-flats: salt marshes and mangrove swamps. There are now 141700 acres of salt marshes and 51000 acres of mangrove swamps which together cover about 30% of the mud-coast area of the country and distribute between 18°N (Southern Hainan Island) and 41 °N (Liaodong Bay). Over the past 45 years, about 1750000 acres of salt marshes and 49400 acres of mangrove swamps have been reclaimed. The 2.0×109 tons of fine sediments input by rivers into the Chinese seas form extensive tidal flats, the soil basis of coastal helophytes. Different climates result in the diversity of vegetation. The 3˜8 m tidal range favors intertidal zone development. Of over 20 plant species in the salt marshes, native Suaeda salsa, Phragmites australis, Aeluropus littoralis, Zoysia maerostachys, Imperata cylindrica and introduced Spartina anglica are the most extensive in distribution. Of the 41 mangrove swamps species, Kandelia candel, Bruguiera gymnorrhiza, Excoecaria agallocha and Avicennia marina are much wider in latitudinal distribution than the others. Developing stages of marshes originally relevant to the evolution of tidal flats are given out. The roles of pioneer plants in decreasing flood water energy and increasing accretion rate in the Changjiang River delta are discussed.

  14. Salt marsh ecohydrological zonation due to heterogeneous vegetation - groundwater - surface water interactions

    NASA Astrophysics Data System (ADS)

    Moffett, K. B.; Gorelick, S.; McLaren, R.; Sudicky, E. A.

    2011-12-01

    Among the most fundamental characteristics of intertidal salt marshes are distinctive vegetation zonation and tidally-forced hydrology. Vegetation zones often correlate with tidal hydrology and plant water use is significant in the wetland balance; however, specific links between vegetation zonation, plant water use, and spatiotemporally variable intertidal hydrology have eluded thorough characterization. This investigation developed the first comprehensive salt marsh ecohydrology models integrating the transient, 3D, coupled surface water and groundwater flow and plant water use of an intensively studied salt marsh field site. The physics-based modeling demonstrated that superimposing heterogeneous sediment hydraulic properties, evapotranspiration rates, and rooting depths, together with tidal dynamics, induced surprising spatial variations in root zone hydraulics: variations pronounced enough to constitute wholly different root zone habitats with different pressure heads, saturations, and vertical groundwater velocities. These diverse habitats were apparent only when both hydraulic and vegetative influences were accounted for, leading to their definition as discrete "ecohydrological zones." We distinguished five different ecohydrological zones (EHZs) by distinct combinations of sediment hydraulic properties and evapotranspiration rates and two EHZs by topography. The hydraulic variations among EHZs were masked shortly after a flooding tide, but again became prominent during prolonged marsh exposure. Boundaries between EHZs exhibited large gradients in head, saturation, and vertical flow magnitude and direction due to a combination of vegetation and sediment effects. We suggest that ecohydrological zones, combining spatially-variable topographic, sediment, and vegetation influences, are the fundamental spatial habitat units comprising the salt marsh ecosystem. This perspective contrasts with historical emphasis on vegetation zones as the foremost unit of habitat

  15. 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...

  16. 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

  17. 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.

  18. Salt marsh response to the effects of physical and biological processes

    NASA Astrophysics Data System (ADS)

    Roner, Marcella; D'Alpaos, Andrea; Ghinassi, Massimiliano; Franceschinis, Erica; Realdon, Nicola; Marani, Marco

    2014-05-01

    Salt marshes are widespread features of the tidal landscape governed by the interacting physical and biological processes. These crucially important ecosystems provide valuable services and are currently threatened by the effects of increasing rates of relative sea level rise (RSLR) and decreasing sediment supply. Although a few studies have analyzed the biomorphological evolution of salt marsh systems, a complete understanding of the two-way feedbacks between physical and biological processes is still lacking. The temporal evolution of marsh elevation is governed by the balance between inorganic and organic accretion rates, and the rate of RSLR. Studies based on field observations and modeling suggest that, in equilibrium conditions, marsh inorganic accretion rates, and the related platform elevations, decrease with distance from the main creek whereas the organic deposition gradually increases. In order to analyze salt marsh responses to the effect of physical and biological processes, about 100 sediment samples were collected on the San Felice salt marsh, Venice Lagoon. For each sample, local coordinates, surface elevations and vegetation cover were detected, whereas inorganic and organic sediment content, together with grain size distribution, were determined and analyzed. Loss On Ignition (LOI) and a double treatment with H2O2 and NaClO, were used to estimate the amount of organic matter in each sample. Particle size analysis was carried out on the inorganic fraction with a Mastersizer that uses laser diffraction techniques to measure the grain size. Our results show that the San Felice salt marsh is characterized by a concave-up profile, as commonly displayed by marshes worldwide. Marsh elevation is highest along the boundary and decreases toward the inner marsh. The inorganic deposition, which is maximum along the marsh edge, decreases with distance from the channel network, because as water moves across the marsh, the velocity is reduced and sediment

  19. 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.

  20. 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...

  1. 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...

  2. 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.

  3. 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.

  4. 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.

  5. NUTRIENT-UPTAKE MODEL IN MARSH ECOSYSTEMS

    EPA Science Inventory

    Mechanistic models of nutrient dynamics in natural wetlands were developed and applied in a study of Kissimmee River (Florida) flood-plain marshes. The models describe hydrodynamics and transport diffusion in wetland basins and the ecological processes of nutrient uptake, convers...

  6. 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.

  7. 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

  8. 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...

  9. 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

  10. 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.

  11. 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.

  12. 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. PMID:23018965

  13. 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.

  14. 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

  15. 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

  16. Accumulation, distribution and cellular partitioning of mercury in several halophytes of a contaminated salt marsh.

    PubMed

    Castro, Rita; Pereira, Sofia; Lima, Ana; Corticeiro, Sofia; Válega, Mónica; Pereira, Eduarda; Duarte, Armando; Figueira, Etelvina

    2009-09-01

    This work evaluates the role of a plant community in mercury (Hg) stabilization and mobility in a contaminated Portuguese salt marsh. With this aim, the distribution of Hg in below and aboveground tissues, as well as the metal partitioning between cellular fractions (soluble and insoluble) in four different species (Triglochin maritima L., Juncus maritimus Lam, Sarcocornia perennis (Miller) A.J. Scott, and Halimione portulacoides (L.) Aellen) was assessed. Mercury accumulation, translocation and compartmentation between organs and cellular fractions were related to the plant species. Results showed that the degree of Hg absorption and retention was influenced both by environmental parameters and metal translocation/partitioning strategies. Different plant species presented different allocation patterns, with marked differences between monocots (T. maritima and J. maritimus) and dicots (S. perennis, H. portulacoides). Overall, the two monocots, in particular T. maritima showed higher Hg retention in the belowground organs whereas the dicots, particularly S. perennis presented a more pronounced translocation to the aboveground tissues. Considering cellular Hg partitioning, all species showed a higher Hg binding to cell walls and membranes rather than in the soluble fractions. This strategy can be related to the high degree of tolerance observed in the studied species. These results indicate that the composition of salt marsh plant communities can be very important in dictating the Hg mobility within the marsh ecosystem and in the rest of the aquatic system as well as providing important insights to future phytoremediation approaches in Hg contaminated salt marshes. PMID:19595432

  17. 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...

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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. PMID:26136442

  3. 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...

  4. 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...

  5. 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...

  6. 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

  7. 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

  8. 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.

  9. 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...

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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.

  15. 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).

  16. 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.

  17. 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.

  18. 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

  19. 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...

  20. 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

  1. 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

  2. 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.…

  3. Loss of ‘Blue Carbon’ from Coastal Salt Marshes Following Habitat Disturbance

    PubMed Central

    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 m2 mean area ± SE) of vegetation loss (aged 3-12 months) in a salt marsh meadow the size of a soccer field (7 275 m2). 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. PMID:23861964

  4. 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

  5. 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

  6. Salt marsh vegetation promotes efficient tidal channel networks

    NASA Astrophysics Data System (ADS)

    Kearney, W. S.; Fagherazzi, S.

    2014-12-01

    Tidal channel networks mediate the exchange of water, nutrients and sediment between an estuary and marshes and mudflats. Biology feeds back into channel morphodynamics through vegetation's influence on the cohesive strength of channel banks. Understanding the morphology of a tidal channel network is thus essential to understanding both the biological functioning of intertidal ecosystems and the topographic signature of life. A critical measure of the morphology of a channel network is the unchanneled path length, which is characteristic of the efficiency with which a network dissects the marsh platform. However, the processes which control the formation and maintenance of an efficient tidal channel network remain unclear. Here we show that an unvegetated marsh platform (Estero La Ramada, Baja California, Mexico) is dissected by a less efficient channel network than a vegetated one (Barnstable, Massachusetts, United States). The difference in geometric efficiency reflects a difference in the branching and meandering characteristics of the network, characteristics controlled by the density of vegetation on the channel banks. Our results suggest a feedback between network geometry and vegetation, mediated by fluxes of nutrients and salinity through the channel network, maintains the observed network geometries. An efficient network can support a denser vegetation community which stabilizes channel banks, leading to an efficient meandering geometry.

  7. 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

  8. 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...

  9. 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...

  10. 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-...

  11. 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...

  12. 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...

  13. 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...

  14. 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.

  15. 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.

  16. 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.

  17. Suitability of different salt marsh plants for petroleum hydrocarbons remediation.

    PubMed

    Couto, M Nazaré P F S; Basto, M Clara P; Vasconcelos, M Teresa S D

    2011-08-01

    The suitability of the salt-marsh species Halimione portulacoides, Scirpus maritimus, Juncus maritimus and an association of the last two for remediation of petroleum hydrocarbons (PHC) in soil was investigated. An outdoor laboratory experiment (microcosm-scale) was carried out using contaminated soil collected in a refinery, as a complement of another study carried out in the refinery environment (mesocosm-scale). Soil samples with old contamination (mainly crude oil) and with a mixture of the old and recent (turbine oil) contamination were tested. Studies in both micro- and mesocosm-scale provided results coherent in substance. The presence of S. maritimus caused removal of old contamination which was refractory to natural attenuation (after 7months of exposure, efficiency was 13% when only old contamination was present and 40% when the soil also contained recent contamination). H. portulacoides (only included in the microcosm-scale study) revealed also potentiality for PHC remediation, although with less efficiency than S. maritimus. Degradation of recent contamination was also faster in the presence of plants (after 7months: 100% in the presence of S. maritimus vs. 63% in its absence). As these species are common in salt marsh areas in Atlantic coast of Europe, it is probable they will be also useful for recovering coast sediments. In contrast, J. maritimus and association did not reveal capability to remove PHC from soil, the presence of J. maritimus inhibiting the capability of S. maritimus. PMID:21601235

  18. 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

  19. 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

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. Geophysical and stratigraphic analysis of a southeastern salt marsh, North Inlet, SC

    NASA Astrophysics Data System (ADS)

    Montane, Juana Maria

    Salt marshes are recognized as among the most dynamic, productive and important ecosystems today. This study presents new evidence of a low sea level stand within the North Inlet-Winyah Bay salt marsh system on the South Carolina coast between 4000-6500 yrs BP as well as the first use of high-resolution seismic reflection surveys to map the surficial and sub-bottom geology of this dynamic system. Facies maps based on sediment stratigraphy, lead-210 analyses and radiocarbon dates show the direct impact of sea level on the formation, evolution and stability of a low gradient saltmarsh system. Parallel to this geological investigation, an evaluation was conducted of Lidar (Light Detecting and Ranging) topographic data accuracy against a statistically representative array of Real-Time Kinematic (RTK) GPS data on the marsh platform. Although airborne Lidar is able to measure micro-topographic features in difficult settings rapidly and accurately, Lidar data were found to overestimate the RTK GPS topographic data by an overall average of 7 cm. Additionally, these data showed little effect from the dominant macrophyte vegetation within the Lidar footprint. From this evaluation, 7 cm appears to be an appropriate vertical adjustment factor for using Lidar data in low gradient salt marshes. However, local ground control will continue to be crucial in studies of intertidal environments incorporating airborne laser data collection. Reflection surfaces were recorded from the channel bottom to as deep as 25 m below surface. These data were acquired utilizing innovative methodology to investigate the unconsolidated sedimentary lensc from a floating platform. Isopach surfaces derived from interpreted horizons and the present day surface including the RTK GPS/Lidar topographic assessment illustrate quantitatively the spatial and temporal residual control paleo-surfaces have on their latter counterparts. Analysis of these data reveal the integral role that antecedent geology and

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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).

  1. 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

  2. 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

  3. 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.

  4. 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

    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.

  5. 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...

  6. 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 ...

  7. 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...

  8. 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...

  9. 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...

  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. 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

  12. 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.

  13. 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...

  14. 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...

  15. 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)

  16. Native plant restoration combats environmental change: development of carbon and nitrogen sequestration capacity using small cordgrass in European salt marshes.

    PubMed

    Curado, Guillermo; Rubio-Casal, Alfredo E; Figueroa, Enrique; Grewell, Brenda J; Castillo, Jesús M

    2013-10-01

    Restoration of salt marshes is critical in the context of climate change and eutrophication of coastal waters because their vegetation and sediments may act as carbon and nitrogen sinks. Our primary objectives were to quantify carbon (C) and nitrogen (N) stocks and sequestration rates in restored marshes dominated by Spartina maritima to provide support for restoration and management strategies that may offset negative aspects of eutrophication and climate change in estuarine ecosystems. Sediment C content was between ca. 13 mg C g(-1)and sediment N content was ca. 1.8 mg N g(-1). The highest C content for S. maritima was recorded in leaves and stems (ca. 420 mg C g(-1)) and the lowest in roots (361 ± 4 mg C g(-1)). S. maritima also concentrated more N in its leaves (31 ± 1 mg N g(-1)) than in other organs. C stock in the restored marshes was 29.6 t C ha(-1); ca. 16 % was stored in S. maritima tissues. N stock was 3.6 t N ha(-1), with 8.3 % stored in S. maritima. Our results showed that the S. maritima restored marshes, 2.5 years after planting, were sequestering atmospheric C and, therefore, provide some mitigation for global warming. Stands are also capturing nitrogen and reducing eutrophication. The concentrations of C and N contents in sediments, and cordgrass relative cover of 62 %, and low below-ground biomass (BGB) suggest restored marshes can sequester more C and N. S. maritima plantations in low marshes replace bare sediments and invasive populations of exotic Spartina densiflora and increase the C and N sequestration capacity of the marsh by increasing biomass production and accumulation. PMID:23591677

  17. 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

  18. 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

  19. 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.

  20. Salt marsh and seagrass communities of Bakkhali Estuary, Cox's Bazar, Bangladesh

    NASA Astrophysics Data System (ADS)

    Hena, M. K. Abu; Short, F. T.; Sharifuzzaman, S. M.; Hasan, M.; Rezowan, M.; Ali, M.

    2007-10-01

    The species identification, distribution pattern, density and biomass of salt marsh and seagrass plants with some of the ecological parameters were studied in the Bakkhali river estuary, Cox's Bazar, Bangladesh during the first half of 2006. Two salt marsh species ( Spartina sp. and Imperata cylindrica) and one seagrass species ( Halophila beccarii) were identified during this investigation, providing the first reports of Spartina sp. and H. beccarii in coastal Bangladesh. Seagrass H. beccarii was found in an accreted area and co-existing with salt marsh, and scattered sparsely in the salt marsh habitat and macroalgae Ulva intestinalis. Flowering and fruiting were recorded from the seagrass H. beccarri during January and February. No flowers and fruits were observed for the salt marsh Spartina sp. during the study period. Results showed that the shoot density of Spartina ranged from 400 to 2875 shoots m -2 with the highest total biomass (165.80 g dry weight (DW) m -2) in March. Shoot density of H. beccarii ranged from 2716 to 14320 shoots m -2 in this estuarine coastal environment. The total biomass of seagrass was higher (17.56 g DW m -2) in March compared to the other months. The highest H. beccarii above ground (AG) biomass and below ground (BG) biomass were 9.59 g DW m -2 and 9.42 g DW m -2, respectively. These parameters are comparable with those generally observed for the salt marsh and seagrass species in the other places of the world.

  1. Evaluation of tidal marsh restoration: Comparison of selected macroinvertebrate populations on a restored impounded valley marsh and an unimpounded valley marsh within the same salt marsh system in Connecticut, USA

    NASA Astrophysics Data System (ADS)

    Peck, Myron A.; Fell, Paul E.; Allen, Elizabeth A.; Gieg, Jennifer A.; Guthke, Carl R.; Newkirk, Michael D.

    1994-03-01

    Macroinvertebrates were examined on an impounded valley marsh in Stonington, Connecticut, that has changed from a Typha-dominated system to one with typical salt-marsh vegetation during 13 years following the reintroduction of tidal exchange. Animal populations on this restored impounded marsh were evaluated by comparing them with populations on a nearby unimpounded valley marsh of roughly the same size. Populations of the high marsh snail, Melampus bidentatus Say, were quantitatively sampled along transects that extended from the water-marsh edge to the upland; those of the ribbed mussel, Geukensia demissa Dillwyn, were sampled in low marsh areas on transects along the banks of creeks and mosquito ditches. The occurrence of other marsh invertebrates also was documented, but their abundance was not measured. The mean density of Melampus was 332±39.6 SE/m2 on the restored impounded marsh and 712±56.0 SE/m2 on the unimpounded marsh. However, since snails were larger on the restored impounded marsh, the difference in snail biomass was less pronounced than the difference in snail density. Mean Melampus biomass was 4.96±0.52 SE g dry wt/m2 on the restored impounded marsh and 6.96±0.52 SE g dry wt/m2 on the unimpounded marsh. On the two marshes, snail density and biomass varied in relation to plant cover and other factors. The density and biomass of Geukensia at the edge of the marsh were comparable on the restored impounded and unimpounded marshes. Mean mussel densities ranged from 80 to 240/m2 and mean mussel biomass varied from 24.8-64.8 g dry wt/m2 in different low marsh areas. In contrast, below the impoundment dike, mean Geukensia density was 1100±96.4 SE/m2 and mean Geukensia biomass was 303.6±33.28 SE g dry wt/m2. A consideration of all available evidence leads to the conclusion that the impounded marsh is in an advanced phase of restoration.

  2. Salt Marshes as Monitors of Late Holocene Outlet Glacier Retreat

    NASA Astrophysics Data System (ADS)

    Wake, L. M.; Woodroffe, S.; Long, A. J.; Milne, G. A.

    2014-12-01

    New proxy sea-level records extracted from salt marshes in the vicinity of Jakobshavn Isbrae (Pakitsoq; 69.51°N, 50.74°W) and at previous sites in central western Greenland (Sisimiut; 66.47°N, 53.61°W and Aasiaat; 68.69°N, 52.88°W) are analyzed with respect to their ability to act as proximal tide gauges detecting mass balance changes in nearby outlet glaciers associated with the transition from the Little Ice Age ("LIA", 1400-1850AD) to the Industrial Period (>1850AD). Data at Pakitsoq demonstrate that sea-level rose at a rate of 3.5 ±1.7 mm/yr prior to 1850AD and slowed to 0.3 ±0.6mm/yr thereafter, producing a slowdown in sea level of 3.2 ± 1.8 mm/yr. A similar slowdown, occurring at 1600AD, is observed at Aasiaat and Sisimiut. We interpret these observed changes using a glacial isostatic adjustment model of sea-level change truncated at degree and order 4096, with an aim to determine if the sea-level data can be used to place constraints on changes in Jakobshavn Isbrae and/or Kangiata Nunaata Sermia (Nuuk fjord) during this period. Modelled sea level at Pakitsoq is insensitive to the location of thickening (thinning) associated with grounding line advance (retreat) and the rate of advance and retreat but is sensitive to the change point in time between periods of growth associated with LIA expansion (sea level rise) and the onset of 19th century recession (sea level fall) of Jakobshavn Isbrae. We conclude that the change in sea-level rate observed at Pakitsoq circa 1850AD marks the onset of post LIA retreat of this outlet glacier. Conversely, the modelled sea-level response to the retreat of Kangiata Nunaata Sermia from its LIA maximum at ca. 1761AD is below the detection threshold of the salt marsh record at Sisimiut.

  3. 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.

  4. Importance of allochthonous material in benthic macrofaunal community functioning in estuarine salt marshes

    NASA Astrophysics Data System (ADS)

    Kon, Koetsu; Hoshino, Yukihiro; Kanou, Kouki; Okazaki, Daisuke; Nakayama, Satoko; Kohno, Hiroshi

    2012-01-01

    Allochthonous input provides important food and spatial resources for estuarine benthic fauna. While it is known that autochthonous materials are important for fauna occupying small marshes, here, we present the significance of allochthonous materials for benthic fauna inhabiting a large salt marsh. To assess the effects of allochthonous input on benthic macrofaunal communities in estuarine salt marshes, we determined the source of substrate sediments and food resource utilisation patterns of benthic invertebrates in 2 temperate estuaries (the Tama River and the Obitsu River estuarine outlets into Tokyo Bay) by using stable carbon and nitrogen isotope analyses. In the Tama River estuary, which has small patches of marsh vegetation upstream of the river mouth, there was an input of sedimentary organic matter from autochthonous sources (i.e. common reed and microphytobenthos). In the Obitsu River estuary salt marsh, which is situated immediately upstream of the river mouth and is well connected to the sea, sediment consists of allochthonous sources (i.e. imported phytoplankton), along with microphytobenthos. Isotope analysis indicated that most benthic invertebrates in the Tama River estuary depend on benthic microalgae (autochthonous) as a food resource, whereas the macrofauna in the Obitsu River estuary are supported by drift macroalgae (allochthonous), in addition to microphytobenthos or phytoplankton. Our results indicated that allochthonous material provides a food resource and potential habitat for benthic macrofauna in extensive salt marshes that have a strong connection to the sea but is not substantial in smaller marshes with limited connectivity to coastal water.

  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 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

  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. 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. PMID:24549938

  10. 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.

  11. Hydrodynamic modeling for river delta salt marshes using lidar topography

    NASA Astrophysics Data System (ADS)

    Hodges, Ben R.

    2014-05-01

    Topographic data from lidar and multi-beam sonar create new challenges for hydrodynamic models of estuaries, tidelands, and river deltas. We now can readily obtain detailed elevation data on 1 m scales and finer, but solving hydrodynamics with model grid cells at these small scales remains computationally prohibitive (primarily because of the small time step required for small grid cells). Practical estuarine models for the next decade or so will likely have grid scales in the range of 5 to 15 m. So how should we handle known subgrid-scale features? Simply throwing out known data does not seem like a good idea, but there is no consensus on how best to incorporate knowledge of subgrid topography into either hydrodynamic or turbulence models. This presentation discusses both the theoretical foundations for modeling subgrid-scale features and the challenges in applying these ideas in the salt marshes of a river delta. The subgrid problem highlights some important areas for field and laboratory research to provide calibration parameters for new models that upscale the effects of known subgrid features.

  12. 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

  13. 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

  14. Microbial Community Composition and Denitrifying Enzyme Activities in Salt Marsh Sediments▿

    PubMed Central

    Cao, Yiping; Green, Peter G.; Holden, Patricia A.

    2008-01-01

    Denitrifying microbial communities and denitrification in salt marsh sediments may be affected by many factors, including environmental conditions, nutrient availability, and levels of pollutants. The objective of this study was to examine how microbial community composition and denitrification enzyme activities (DEA) at a California salt marsh with high nutrient loading vary with such factors. Sediments were sampled from three elevations, each with different inundation and vegetation patterns, across 12 stations representing various salinity and nutrient conditions. Analyses included determination of cell abundance, total and denitrifier community compositions (by terminal restriction fragment length polymorphism), DEA, nutrients, and eluted metals. Total bacterial (16S rRNA) and denitrifier (nirS) community compositions and DEA were analyzed for their relationships to environmental variables and metal concentrations via multivariate direct gradient and regression analyses, respectively. Community composition and DEA were highly variable within the dynamic salt marsh system, but each was strongly affected by elevation (i.e., degree of inundation) and carbon content as well as by selected metals. Carbon content was highly related to elevation, and the relationships between DEA and carbon content were found to be elevation specific when evaluated across the entire marsh. There were also lateral gradients in the marsh, as evidenced by an even stronger association between community composition and elevation for a marsh subsystem. Lastly, though correlated with similar environmental factors and selected metals, denitrifier community composition and function appeared uncoupled in the marsh. PMID:18978080

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Hyperspectral remote sensing of salt marsh vegetation, morphology and soil topography

    NASA Astrophysics Data System (ADS)

    Silvestri, Sonia; Marani, Marco; Marani, Alessandro

    The present paper deals with the relationship between vegetation patterns and salt marsh morphology in the Venice lagoon and with the use of remote sensing to infer salt marsh morphologic characteristics from vegetation mapping. Field measurements indicate that salt marsh vegetation species (halophytes) are reliable indicators of ground elevation and live within typical elevation ranges characterised by standard deviations of less than 5 cm. A model is then developed which uses vegetation as a morphological indicator of soil topography to estimate ground elevation from fractional cover values of each vegetation type. The use of data from an airborne remote hyperspectral sensor is presented as a means of discriminating between different salt marsh vegetation communities. Vegetation maps obtained from unmixing techniques have then been used to produce digital elevation maps (DEM) of salt marsh areas. The DEM based on halophytes cover estimates and extracted from high spatial and spectral resolution data allows a high estimation accuracy, with an error standard deviation of a few centimetres in the considered study area within the Venice lagoon. The accuracy and resolution attainable through this method are comparable and often superior to those obtained through state of the art laser altimetry.

  5. 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

  6. 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.

  7. 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.

  8. 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. PMID:22535367

  9. 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

  10. 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.

  11. Hypoxic coma as a strategy to survive inundation in a salt-marsh inhabiting spider

    PubMed Central

    Pétillon, Julien; Montaigne, William; Renault, David

    2009-01-01

    Spiders constitute a major arthropod group in regularly inundated habitats. Some species survive a flooding period under water. We compared survival during both submersion and a recovery period after submersion, in three stenotopic lycosids: two salt-marsh species Arctosa fulvolineata and Pardosa purbeckensis, and a forest spider Pardosa lugubris. Both activity and survival rates were determined under controlled laboratory conditions by individually surveying 120 females kept submerged in sea water. We found significant differences between the three species, with the two salt-marsh spiders exhibiting higher survival abilities. To our knowledge, this study reports for the first time the existence of a hypoxic coma caused by submersion, which is most pronounced in A. fulvolineata, the salt-marsh spider known to overcome tidal inundation under water. Its ability to fall into that coma can therefore be considered a physiological adaptation to its regularly inundated habitat. PMID:19411268

  12. Classification And Monitoring Of Salt Marsh Habitats With Multi-Polarimetric Airborne SAR

    NASA Astrophysics Data System (ADS)

    van Beijma, Sybrand; Comber, Alexis; Lamb, Alistair

    2013-12-01

    Within the Copernicus programme there is much interest in the ability of remote sensing technology to deliver operational solutions to many areas of life including environmental management. This paper describes research focused on the application of Earth Observation for Integrated Coastal Zone Management. The main topic of this research is to explore to which extent salt marsh vegetation habitats can be identified from polarimetric SAR remotely sensed data. Multi- frequency, multi-polarimetric SAR images from airborne (S- and X-Band quad-polarimetric from the Astrium airborne SAR Demonstrator) is used to examine salt marsh habitat classification potential in the Llanrhidian salt marshes in South Wales, UK. This is achieved by (1) using both supervised and unsupervised classification routines, using several polarimetric SAR data layers as backscatter intensity, band ratios and polarimetric decomposition products, and by (2) statistical analysis by regression of these different SAR data layers and botanical parameters acquired from recent ecological fieldwork.

  13. Effects of several salt marsh plants on mouse spleen and thymus cell proliferation using mtt assay

    NASA Astrophysics Data System (ADS)

    Seo, Youngwan; Lee, Hee-Jung; Kim, You Ah; Youn, Hyun Joo; Lee, Burm-Jong

    2005-12-01

    In the present study, we have tested the effects of 21 salt marsh plants on cell proliferation of mouse immune cells (spleen and thymus) using MTT assay in culture. The methanolic extracts of six salt marsh plants ( Rosa rugosa, Ixeris tamagawaensis, Artemisia capillaris, Tetragonia tetragonoides, Erigeron annus, and Glehnia littoralis) showed very powerful suppressive effects of mouse immune cell death and significant activities of cell proliferation in vitro. Especially, the methanolic extract of Rosa rugosa was found to have fifteen times compared to the control treatment, demonstrating that Rosa rugosa may have a potent stimulation effect on immune cell proliferation. These results suggest that several salt marsh plants including Rosa rugosa could be useful for further study as an immunomodulating agent.

  14. 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.

  15. 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. PMID:25224178

  16. 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.

  17. 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, ...

  18. 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.

  19. 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.

  20. Critical bifurcation of shallow microtidal landforms in tidal flats and salt marshes.

    PubMed

    Fagherazzi, Sergio; Carniello, Luca; D'Alpaos, Luigi; Defina, Andrea

    2006-05-30

    Shallow tidal basins are characterized by extensive tidal flats and salt marshes that lie within specific ranges of elevation, whereas intermediate elevations are less frequent in intertidal landscapes. Here we show that this bimodal distribution of elevations stems from the characteristics of wave-induced sediment resuspension and, in particular, from the reduction of maximum wave height caused by dissipative processes in shallow waters. The conceptual model presented herein is applied to the Venice Lagoon, Italy, and demonstrates that areas at intermediate elevations are inherently unstable and tend to become either tidal flats or salt marshes. PMID:16707583

  1. Critical bifurcation of shallow microtidal landforms in tidal flats and salt marshes

    PubMed Central

    Fagherazzi, Sergio; Carniello, Luca; D'Alpaos, Luigi; Defina, Andrea

    2006-01-01

    Shallow tidal basins are characterized by extensive tidal flats and salt marshes that lie within specific ranges of elevation, whereas intermediate elevations are less frequent in intertidal landscapes. Here we show that this bimodal distribution of elevations stems from the characteristics of wave-induced sediment resuspension and, in particular, from the reduction of maximum wave height caused by dissipative processes in shallow waters. The conceptual model presented herein is applied to the Venice Lagoon, Italy, and demonstrates that areas at intermediate elevations are inherently unstable and tend to become either tidal flats or salt marshes. PMID:16707583

  2. 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.

  3. 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.

  4. Populations of Anaerobic Phototrophic Bacteria in a Spartina alterniflora Salt Marsh

    PubMed Central

    Paterek, J. Robert; Paynter, M. J. B.

    1988-01-01

    Habitat-simulating media were used with the Hungate anaerobic roll tube technique to enumerate culturable anaerobic photosynthetic bacteria in sediment, tidal waters, and Spartina alterniflora plant samples collected from the salt marsh at Sapelo Island, Ga. No phototrophs were detected in samples of creekside (low marsh) sediment or in tidal waters in creekside regions. In the high marsh region, 90% of anaerobic phototrophic bacteria occurred in the top 5 mm of sediment and none were detected below 6 mm. There was a seasonal variation, with maximal populations occurring in summer and fall (mean, 4.4 × 105 phototrophs g of dry sediment−1) and minimal numbers occurring in winter (mean, 3.9 × 103 phototrophs g of dry sediment−1). During winter and late spring, phototrophs had a patchy distribution over the high marsh sediment surface. In contrast, during late summer they had a random uniform distribution. Tidal water collected over high marsh sediment contained an average of 8.7 × 102 phototrophs ml−1, with no significant seasonal variation. Anaerobic phototrophic bacteria were also cultured from the lower stem tissue of S. alterniflora growing in both the high (4.3 × 104 phototrophs g of dry tissue−1) and creekside (4.9 × 104 phototrophs g of dry tissue−1) marsh regions. Chromatium buderi, Chromatium vinosum, Thiospirillum sanguineum, Rhodospirillum molischianum, and Chlorobium phaeobacteroides were the predominant anaerobic phototrophic species cultured from high marsh sediment. The two Chromatium species were dominant. PMID:16347646

  5. 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

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. GUIDANCE DOCUMENT ON THE BIOREMEDIATION OF OIL-CONTAMINATED SALT MARSHES.

    EPA Science Inventory

    A comprehensive guidance document that includes all known information about the implementation of bioremediation for cleanup of oil-contaminated coastal salt marshes was developed and the project completed. The document is the second in a series of two that has been produced. The...

  13. 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...

  14. Characterization of humic substances in salt marsh soils under sea rush ( Juncus maritimus)

    NASA Astrophysics Data System (ADS)

    Santín, C.; González-Pérez, M.; Otero, X. L.; Vidal-Torrado, P.; Macías, F.; Álvarez, M. Á.

    2008-09-01

    Humic substances (HS) from salt marsh soils were characterized and the relationships among HS composition and some geochemical factors were analysed. For this, three salt marshes with the same vegetation cover ( Juncus maritimus), but with different geochemical characteristics, were selected. The qualitative characterization of the soil humic acids and fulvic acids was carried out by elemental analysis, FTIR spectroscopy, fluorescence spectroscopy and VACP/MAS 13C NMR spectroscopy. HS from salt marsh soils under sea rush ( Juncus maritimus) displayed some shared characteristics such as low degree of humification, low aromatic content and high proportion of labile compounds, mainly polysaccharides and proteins. However, although the three salt marsh soils under study were covered by the same type of vegetation, the HS showed some important differences. HS composition was found to be determined not only by the nature of the original organic material, but also by environmental factors such as soil texture, redox conditions and tidal influence. In general, an increase in the humification process appeared to be related to aerobic conditions and predominance of sand in the mineral fraction of the soil, while the preservation of labile organic compounds may be associated with low redox potential values and fine soil texture.

  15. 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...

  16. 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...

  17. 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...

  18. LINKING PLANT TRAITS TO SPECIES PERFORMANCE IN REMNANT AND RESTORED INLAND SALT MARSH COMMUNITIES

    EPA Science Inventory

    This research will build upon prior efforts where regression was used to model salt marsh species persistence and productivity along hydrologic and edaphic gradients at the SWB. Upcoming results will enable the optimization of planting combinations at a given salinity leve...

  19. Methyl and Total Mercury Budget of a Mid-Atlantic Estuarine Salt Marsh

    NASA Astrophysics Data System (ADS)

    Mitchell, C. P.; Gilmour, C. C.

    2007-12-01

    Coastal and estuarine salt marshes are both efficient accumulators of particulate-bound inorganic mercury (Hg) and transformers of inorganic Hg to methylmercury (MeHg). As part of continuing studies on the biogeochemical controls, sources, and fate of Hg and MeHg in the Chesapeake Bay region, we have recently expanded our research to examine Hg and MeHg cycling in Chesapeake tidal marshes. Our main study site is the Kirkpatrick Marsh, a salt marsh at the Smithsonian Environmental Research Center (SERC) on the shores of a Chesapeake Bay sub-estuary, the Rhode River. Kirkpatrick Marsh is dominated by Spartina patens, Scirpus olneyi, Phragmites australis, and several other species and is influenced by a mean tidal range of approximately 30 cm. The marsh is currently and has previously been the subject of various biogeochemical studies, thus basic biogeochemistry, carbon, and nutrient cycling for this system is well understood. Research goals for our study include an estimation of the contribution of salt marshes to MeHg budgets in the Chesapeake specifically and in coastal zones more generally; a first look at the sources of Hg for methylmercury production in tidal marshes; and an improved understanding of the biogeochemical controls on net MeHg production and flux in these wetlands. The research study has two major components. One is a spatially-distributed investigation of the geochemical and microbial controls on MeHg production in this high sulfate/high sulfide wetland system. Detailed biogeochemical measurements were made across three marsh zones distinguished by vegetation/elevation characteristics. Microbial activity in the three zones peaks at depths approximately equal to the mean water table depth, but always in the upper 5-10 cm of soil. Pore water sulfide concentrations increase substantially with depth in marsh soil cores, with highest sulfide concentrations (up to 1.5 M) found deeper in the least frequently flooded site. Initial data show that Me

  20. 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

  1. Crabs mediate interactions between native and invasive salt marsh plants: a mesocosm study.

    PubMed

    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

  2. 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

  3. 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.

  4. Temporal changes and spatial variation of soil oxygen consumption, nitrification and denitrification rates in a tidal salt marsh of the Lagoon of Venice, Italy

    NASA Astrophysics Data System (ADS)

    Eriksson, P. G.; Svensson, J. M.; Carrer, G. M.

    2003-12-01

    The aim of the present study was to investigate seasonal and spatial patterns of soil oxygen consumption, nitrification, denitrification and fluxes of dissolved inorganic nitrogen (DIN) in a tidal salt marsh of the Lagoon of Venice, Italy. In the salt marsh, intact soil cores including overlying water were collected monthly at high tide from April to October in salt marsh creeks and in areas covered by the dominant vegetation, Limonium serotinum. In May, cores were also collected in areas with vegetation dominated by Juncus maritimus and Halimione portulacoides. In laboratory incubations at in situ temperature in the dark, flux rates of oxygen and DIN were monitored in the overlying water of the intact cores. 15N-nitrate was added to the overlying water and nitrification and denitrification were measured using isotope-dilution and -pairing techniques. The results show that highest soil oxygen consumption coincided with the highest water temperature in June and July. The highest denitrification rates were recorded in spring and autumn coinciding with the highest nitrate concentrations. Soil oxygen consumption and nitrification rates differed between sampling sites, but denitrification rates were similar among the different vegetation types. The highest rates were recorded in areas covered with L. serotinum. Burrowing soil macrofauna enhanced oxygen consumption, nitrification and denitrification in April and May. The data presented in this study indicate high temporal as well as spatial variations in the flux of oxygen and DIN, and nitrogen transformations in the tidal salt marshes of the Venice lagoon during the growth season. The results identify the salt marshes of the Venice lagoon as being metabolically very active ecosystems with a high capacity to process nitrogen.

  5. 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.

  6. 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.

  7. 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

  8. 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.

  9. 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:…

  10. 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.

  11. The influence of mosquito control recirculation ditches on plant biomass, production and composition in two San Francisco Bay salt marshes

    NASA Astrophysics Data System (ADS)

    Balling, Steven S.; Resh, Vincent H.

    1983-02-01

    Vegetation of two San Francisco Bay, California, U.S.A. tidal marshes was examined to determine the effects of recirculation ditches designed to eliminate mosquito-breeding. Salicornia virginica L. biomass and production in Petaluma Marsh and plant species composition in Suisun Marsh were measured with respect to distance from ditches and natural channels. In Petaluma Marsh, both annual above-ground production estimates and infrared aerial photographs indicated that S. virginica growth rates were higher near ditches than in the open marsh. In the floristically diverse, less saline Suisun Marsh, there was a displacement of the more salt tolerant S. virginica by the less tolerant Juncus balticus Willd. and a significantly greater number of species near the ditches. Results in both marshes are correlated with low groundwater salinities near ditches and suggest that tidal circulation within ditches locally ameliorates extremes in soil conditions.

  12. Seasonal Variability and Transport of Suspended Microfungi in a Southeastern Salt Marsh

    PubMed Central

    Chrzanowski, Thomas H.; Stevenson, L. Harold; Spurrier, J. D.

    1982-01-01

    Tidally induced fluctuations and transports of microfungi were investigated. Samples were collected at three depths from three stations positioned at a transect in a large salt marsh creek. Samples were taken every 1.5 h for 50 consecutive h during neap tides and 50 consecutive h during the corresponding spring tides. In each season, microfungi concentrations fluctuated out of phase with the tides during both neap and spring tides. Mean concentrations of suspended microfungi did not vary appreciably throughout the year. Fungi were exported from the marsh during the majority of the tidal cycles studied. The results suggest that microfungi may serve as indicators of water mass movements. PMID:16345945

  13. Using Projections of Tidal Marsh Ecosystem Response to Sea-Level Rise to Guide Adaptation Planning

    NASA Astrophysics Data System (ADS)

    Veloz, S.; Nur, N.; Salas, L. A.; Stralberg, D.; Jongsomjit, D.; Wood, J.; Liu, L.; Ballard, G.

    2011-12-01

    The large uncertainty associated with estimating the effects of sea-level rise and climate change on tidal marsh ecosystems exacerbates the difficulty in planning for their effective conservation. To address this uncertainty, we modeled the distribution and abundance of tidal marsh bird species in the San Francisco Estuary for the period 2010 to 2110 in relation to projected changes in sea-level rise, salinity, and sediment availability using four future scenarios with assumptions of low or high suspended sediment concentrations and low or high rates of sea-level rise (0.52 or 1.65 m/100 yr). We used the projections of bird populations the modeled uncertainty to develop spatially explicit priorities for conservation and restoration using Zonation conservation planning software. In our models, marsh bird population generally declined from current levels due to the conversion of high and mid-marsh habitat to low-marsh and mudflats and changes in spring and summer salinity. High sea-level rise scenarios had the biggest impact on bird populations, although the effects were muted under high sediment availability scenarios. There was considerable variation in bird population projections among the four future scenarios we tested and the uncertainty tended to increase from 2030 to 2110. Because so little tidal marsh habitat currently remains in the San Francisco Estuary, the spatial prioritization found that all areas currently open to tidal influence were high priorities for conservation. We repeated this prioritization exercise with all barriers to tidal flow (e.g. levees) removed and identified important locations in which restoration by breaching levees would most efficiently provide long-term benefit to tidal marsh bird populations. The projected species distributions and changes in tidal marsh elevations are available in the form of interactive maps and downloadable GIS layers at: www.prbo.org/sfbayslr. This website can help managers plan effective conservation and

  14. 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.

  15. 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

  16. Seasonal and topographic variations in porewaters of a southeastern USA salt marsh as revealed by voltammetric profilingdagger.

    PubMed

    Bull, D C; Taillefert, M

    2001-01-01

    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. PMID:16759419

  17. 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

  18. 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.

  19. 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...

  20. 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

  1. 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

  2. Influence of halophytes and metal contamination on salt marsh macro-benthic communities

    NASA Astrophysics Data System (ADS)

    Vinagre, C.; Cabral, H. N.; Caçador, I.

    2008-03-01

    Since an important fraction of the organic matter produced by salt marshes is decomposed in situ, macro-benthic communities are particularly exposed to the trace metals retained by these systems. Yet, few studies have investigated the macro-benthic communities using the between-root sediment habitat of the salt marsh halophytes (salt-tolerant plants), or the effect of trace metal pollution on its population dynamics. In the present study, samples were collected in vegetated and unvegetated sediment, in three salt marshes in the Tagus estuary, for trace metal concentration determination in the sediment and in the halophytes roots, grain size determination and macro-benthic organism identification. Data analysis revealed that the distribution of macro-benthic organisms is mainly determined by metal contamination, metal type and by the presence/absence of halophytes, not by the halophyte species. Five different associations were identified: resistant organisms were associated with the highest concentrations of lead (sediment); tolerant organisms with zinc, copper (sediment and roots) and lead (roots); cadmium in the sediment with a lack of macro-benthic life; sensitive organisms with low levels of metals except for cadmium in the roots; and macro-benthos typical of intertidal mudflats with unvegetated areas with low metal contamination.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Long-term CH3Br and CH3Cl flux measurements in temperate salt marshes

    NASA Astrophysics Data System (ADS)

    Blei, E.; Heal, M. R.; Heal, K. V.

    2010-08-01

    Fluxes of CH3Br and CH3Cl and their relationship with potential drivers such as sunlight, temperature and soil moisture, were monitored at fortnightly to monthly intervals for more than two years at two contrasting temperate salt marsh sites in Scotland. Manipulation experiments were conducted to further investigate possible links between drivers and fluxes. Mean (± 1 sd) annually and diurnally-weighted net emissions from the two sites were found to be 300 ± 44 ng m-2 h-1 for CH3Br and 662 ± 266 ng m-2 h-1 for CH3Cl. A tentative scale-up indicates that salt marshes account for 0.5-3.2% and 0.05-0.33%, respectively, of currently-estimated total global production of these two gases, in line with previous findings from this and other research groups, but consistently lower than past global scale-up estimates from Southern Californian salt marshes. Fluxes followed both seasonal and diurnal trends with highest fluxes during summer days and lowest (negative) fluxes during winter nights. Statistical analysis generally did not demonstrate a strong link between temperature or sunlight levels and methyl halide fluxes, although it is likely that temperatures have a weak direct influence on emissions, and both certainly have indirect influence via the annual and daily cycles of the vegetation. CH3Cl flux magnitudes from different measurement locations depended on the plant species enclosed whereas such dependency was not discernible for CH3Br fluxes. In 14 out of 19 collars CH3Br and CH3Cl net fluxes were significantly correlated. The CH3Cl/CH3Br net-emission mass ratio was 2.2, a magnitude lower than mass ratios of global methyl halide budgets (~22) or emissions from tropical rainforests (~60). This is likely due to preference for CH3Br production by the relatively high bromine content in the salt marsh plant material.

  8. 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. PMID:25909974

  9. 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.

  10. 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. PMID:23707865

  11. Pyrite formation and the measurement of sulfate reduction in salt marsh sediments

    SciTech Connect

    Howarth, R.W.; Merkel, S.

    1984-05-01

    A new method was used to study the formation of pyrite plus elemental sulfur during /sup 35/SO/sub 4//sup 2 -/ reduction experiments in salt marsh sediments: the reduction with chromium(II) of pyrite and elemental sulfur to hydrogen sulfide. It is both more specific and more sensitive than the previous method, the oxidation of pyrite and elemental sulfur to sulfate by aqua regia, which measures the formation of refractory organic sulfur compounds as well as pyrite and elemental sulfur. A direct comparison of the two methods in salt marsh sediments in Georgia and in Massachusetts showed that they compare very well. The chromium(II) reduction method, combined with the authors' previous results, conclusively shows that pyrite is the major product of /sup 35/SO/sub 4//sup 2 -/ reduction measurements in these sediments. The agreement between the two methods indicates that the formation of /sup 35/S-labeled, refractory organic matter is a minor process if it occurs at all. The authors' results suggest that both the aqua regia oxidation method and the chromium(II) reduction method, if used with care, are suitable for measuring incorporation of /sup 35/S into pyrite and elemental sulfur during /sup 35/SO/sub 4//sup 2 -/ reduction measurements in salt marsh sediments. Failure to explicitly measure the formation of /sup 35/S-labeled pyrite can result in the rate of sulfate reduction being underestimated by 2-fold to 10-fold or more.

  12. 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.

  13. 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.

  14. 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

  15. Biogeochemical and hydrological controls on fate and distribution of trace metals in oiled Gulf salt marshes

    NASA Astrophysics Data System (ADS)

    Keevan, J.; Natter, M.; Lee, M.; Keimowitz, A.; Okeke, B.; Savrda, C.; Saunders, J.

    2011-12-01

    On April 20, 2010, the drilling rig Deepwater Horizon exploded in the Gulf of Mexico, resulting in the release of approximately 5 million barrels of crude oil into the environment. Oil and its associated trace metals have been demonstrated to have a detrimental effect on coastal wetland ecosystems. Wetlands are particularly susceptible to oil contamination because they are composed largely of fine-grained sediments, which have a high capacity to adsorb organic matter and metals. The biogeochemical cycling of trace metals can be strongly influenced by microbial activity, specifically those of sulfate- and iron-reducing bacteria. Microbial activity may be enhanced by an increase in amounts of organic matter such as oil. This research incorporates an assessment of levels of trace metals and associated biogeochemical changes from ten coastal marshes in Alabama, Mississippi, and Louisiana. These sampling sites range in their pollution levels from pristine to highly contaminated. A total digestion analysis of wetland sediments shows higher concentrations of certain trace metals (e.g., Ni, Cu, Pb, Zn, Sr, Co, V, Ba, Hg, As) in heavily-oiled areas compared to less-affected and pristine sites. Due to chemical complexation among organic compounds and metals, crude oils often contain elevated levels (up to hundreds of mg/kg) of trace metals At the heavily-oiled Louisiana sites (e.g., Bay Jimmy, Bayou Dulac, Bay Batiste), elevated levels of metals and total organic carbon have been found in sediments down to depths of 30 cm. Clearly the contamination is not limited to shallow sediments and oil, along with various associated metals, may be invading into deeper (pre-industrial) portions of the marsh sediments. Pore-waters extracted from contaminated sediments are characterized by very high levels of reduced sulfur (up to 80 mg/kg), in contrast to fairly low ferrous iron concentrations (<0.02 mg/kg). The influx of oil into the wetlands might provide the initial substrate and

  16. Long-term effects of mercury in a salt marsh: hysteresis in the distribution of vegetation following recovery from contamination.

    PubMed

    Válega, M; Lillebø, A I; Pereira, M E; Duarte, A C; Pardal, M A

    2008-03-01

    During four decades, the Ria de Aveiro was subjected to the loading of mercury from a chlor-alkali industry, resulting in the deposition of several tons of mercury in the sediments. The present study evaluates the impact of this disturbance and the recovery processes, temporally and spatially, by means of examining the richness of the species of salt marsh plants and mercury concentrations in sediments over the last fifty years. The temporal assessment showed that the mercury loading induced a shift in the species composition of the salt marsh from a non-disturbed salt marsh with higher species richness to an alternative state dominated by Phragmites australis. The horizontal assessment, through a mercury gradient, presents the same trend, indicating that P. australis is the species most tolerant to higher mercury concentrations, comparative to Halimione portulacoides, Arthrocnemum fruticosum, Triglochin maritima, Juncus maritimus and Scirpus maritimus. After the reduction of mercury discharges in 1994, the salt marsh shows a slowly return path recovery response. The hysteresis in the response results in the temporal gap between the reduction in mercury concentrations in the sediment and the salt marsh species richness response, comparatively to the existing diversity in the local reference marsh. PMID:18061237

  17. Long-term CH3Br and CH3Cl flux measurements in temperate salt marshes

    NASA Astrophysics Data System (ADS)

    Blei, E.; Heal, M. R.; Heal, K. V.

    2010-11-01

    Fluxes of CH3Br and CH3Cl and their relationship with potential drivers such as sunlight, temperature and soil moisture, were monitored at fortnightly to monthly intervals for more than two years at two contrasting temperate salt marsh sites in Scotland. Manipulation experiments were conducted to further investigate possible links between drivers and fluxes. Fluxes followed both seasonal and diurnal trends with highest fluxes during summer days and lowest (negative) fluxes during winter nights. Mean (± 1 sd) annually and diurnally-weighted net emissions from the two sites were found to be 300 ± 44 ng m-2 h-1 for CH3Br and 662 ± 266 ng m-2 h-1 for CH3Cl. The fluxes from this work are similar to findings from this and other research groups for salt marshes in cooler, higher latitude climates, but lower than values from salt marshes in the Mediterranean climate of southern California. Statistical analysis generally did not demonstrate a strong link between temperature or sunlight levels and methyl halide fluxes, although it is likely that temperatures have a weak direct influence on emissions, and both certainly have indirect influence via the annual and daily cycles of the vegetation. CH3Cl flux magnitudes from different measurement locations depended on the plant species enclosed whereas such dependency was not discernible for CH3Br fluxes. In 14 out of 18 collars with vegetation CH3Br and CH3Cl net fluxes were significantly positively correlated. The CH3Cl/CH3Br net-emission mass ratio was 2.2, a magnitude lower than mass ratios of global methyl halide budgets (~22) or emissions from tropical rainforests (~60). This is likely due to preference for CH3Br production by the relatively high bromine content in the salt marsh plant material. Extrapolation based solely on data from this study yields salt marsh contributions of 0.5-3.2% and 0.05-0.33%, respectively, of currently-estimated total global production of CH3Br and CH3Cl, but actual global contributions likely

  18. 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

  19. Long-term surface elevation changes in German North Sea salt marshes

    NASA Astrophysics Data System (ADS)

    Suchrow, Sigrid; Pohlmann, Nina; Stock, Martin; Jensen, Kai

    2012-02-01

    We analyzed long-term (19-21 years) surface elevation changes of salt marshes along the German mainland North Sea coast in a large and consistent data set (423 plots). Our aim was to determine the influence of 12 predictor variables, e.g. elevation, micro-topography and management data. For each plot, we measured elevation above sea level, once 1988-1990 and again 2009. The calculated surface elevation change per year (target variable SEC) was +0.6 cm yr -1 on average. 85.8% of the plots showed positive SEC values. Although 11 predictors were significantly correlated to SEC, only five driving on different scales were included by the tree fitting algorithm when using regression tree analysis. The resulting tree model with 11 terminal nodes explained 45.7% proportion of the variance in SEC values. Plots tended to high SEC values when a) lying low in relation to mean high tide, b) being located in the northern regions of the study area, and c) lying in drainage ditches. d) Grazing management did account for SEC variance only in northern regions. e) SEC was enhanced on non-grazed plots lying high in relation to mean high tide. We concluded that most of the studied salt marshes may outpace a predicted sea-level rise of about 0.1-0.2 cm yr -1, but barely half of the marsh areas might follow a sea-level rise of 0.6 cm yr -1. Regression tree analysis is a useful approach for studying changes in elevation of salt marshes when considering various variables.

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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

  5. 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...

  6. Long-term biological effects of petroleum residues on fiddler crabs in salt marshes.

    PubMed

    Culbertson, Jennifer B; Valiela, Ivan; Peacock, Emily E; Reddy, Christopher M; Carter, Anna; VanderKruik, Rachel

    2007-07-01

    In September 1969, the Florida barge spilled 700,000L of No. 2 fuel oil into the salt marsh sediments of Wild Harbor (Buzzards Bay, MA). Today the aboveground environment appears unaffected, but a substantial amount of moderately degraded petroleum still remains 8-20cm below the surface. The salt marsh fiddler crabs, Uca pugnax, burrow into the sediments at depths of 5-25cm, and are chronically exposed to the spilled oil. Behavioral studies conducted with U. pugnax from Wild Harbor and a control site, Great Sippewissett marsh, found that crabs exposed to the oil avoided burrowing into oiled layers, suffered delayed escape responses, lowered feeding rates, and achieved lower densities. The oil residues are therefore biologically active and affect U. pugnax populations. Our results add new knowledge about long-term consequences of spilled oil, a dimension that should be included when assessing oil-impacted areas and developing management plans designed to restore, rehabilitate, or replace impacted areas. PMID:17448504

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Multitemporal spectroradiometry-guided object-oriented classification of salt marsh vegetation

    NASA Astrophysics Data System (ADS)

    Civco, Daniel L.; Gilmore, Martha S.; Wilson, Emily H.; Barrett, Nels; Prisloe, Sandy; Hurd, James D.; Chadwick, Cary

    2008-10-01

    This study addresses the use of multitemporal field spectral data, satellite imagery, and LiDAR top of canopy data to classify and map common salt marsh plant communities. Visible to near-infrared (VNIR) reflectance spectra were measured in the field to assess the phenological variability of the dominant species - Spartina patens, Phragmites australis and Typha spp. The field spectra and single date LiDAR canopy height data were used to define an objectoriented classification methodology for the plant communities in multitemporal QuickBird imagery. The classification was validated using an extensive field inventory of marsh species. Overall classification accuracies were 97% for Phragmites, 63% for Typha spp. and 80% for S. patens meadows. Using a fuzzy assessment analysis, these accuracies were 97%, 76%, and 92%, respectively, for the three major species.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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. PMID:18597178

  17. 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.

  18. 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

  19. 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

  20. 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

  1. Characterising the distribution and morphology of creeks and pans on salt marshes in England and Wales using Google Earth

    NASA Astrophysics Data System (ADS)

    Goudie, Alice

    2013-09-01

    By using Google Earth images and simple morphometric analyses, pan and creek characteristics of salt marshes across England and Wales have been mapped and related to key environmental variables, including tidal range, sea level change, coastal configuration, sediment type and erosion state. Pan density was found to be higher on the west coast or where there is a moderate tidal range and low sea level change. Pan density is also higher on back barrier and drowned valley marshes and when creek density is low. Maximum pan size is partly controlled by pan density. Creek density and sinuosity showed great variability between areas with marshes in the south having a higher creek density. Creek density is related to tidal prism and marshes undergoing high rates of sea level change usually have higher creek densities. Marshes with an upstream configuration (embayment, drowned valley and back barrier) have lower creek densities due to a lower tidal prism. Sediment type also plays a role with lower creek densities found on coarser sediment types. Creek sinuosity seems to be largely controlled by tidal range with higher sinuosities on meso- or macro-tidal marshes. This large-scale, Google Earth-based, analysis of the distribution and likely environmental controls on salt marsh morphometry illustrates the utility of Digital Globes as sources of freely-available, high resolution imagery for geomorphological research.

  2. 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.

  3. Salt marsh plants ( Juncus maritimus and Scirpus maritimus) as sources of strong complexing ligands

    NASA Astrophysics Data System (ADS)

    Mucha, Ana P.; Almeida, C. Marisa R.; Bordalo, Adriano A.; Vasconcelos, M. Teresa S. D.

    2008-03-01

    This work aimed to evaluate, in vitro, the capability of roots of salt marsh plants to release strong Cu-complexing ligands and to ascertain whether Cu contamination would stimulate ligands' exudation or not. The sea rush Juncus maritimus and the sea-club rush Scirpus maritimus, both from the lower Douro river estuary (NW Portugal), were used. Plants were collected seasonally, four times a year in 2004, during low tide. After sampling, plant roots were washed for removal of adherent particles and immersed for 2 h in a solution that matched salinity (3) and pH (7.5) of the pore water from the same location and spiked with Cu 2+ in the range 0-1600 nM to obtain plant exudates. In the final solutions as well as in sediment pore water total dissolved Zn and Cu, Cu-complexing ligand concentrations and the respective conditional stability constants ( KCuL') values were determined by voltammetry. This study demonstrated that plants are able to release, in a short period of time, relatively high amounts of strong Cu-complexing ligands (56-265 nmol g root-1), which differed among plants and sampling site but were independent of the season. Cu contamination did not stimulate exudation of Cu-complexing ligands. On the other hand, in media contaminated with Cu both plants accumulated relatively high amounts (29-83%) of the initially dissolved Cu, indicating that they have alternative internal mechanisms for Cu detoxification. Cu exchange between roots and medium (either accumulation in contaminated medium or release in the absence of Cu) was more intense for S. maritimus than for J. maritimus. It was observed that exudate solutions obtained in the absence of added Cu and sediment pore water (the densities of roots observed inside the salt marsh where comparable to those used in the in vitro experiments), displayed similarities in terms of total dissolved metals, Cu-complexing ligands concentrations, values of KCuL' (12 < log KCuL' < 14), as well as patterns of variation among

  4. Persistence of white phosphorus (P{sub 4}) particles in salt marsh sediments

    SciTech Connect

    Walsh, M.E.; Collins, C.M.; Racine, C.H.

    1996-06-01

    Remediation of sediments at Eagle River Flats, Alaska, a salt marsh contaminated with solid particles of white phosphorus (P{sub 4}), may require severe alterations of the wetland by dredging, draining, or covering. However, some sediments may undergo decontamination naturally in areas that are seasonally subaerially exposed. The persistence of millimeter-size P{sub 4} particles was studied in laboratory and field experiments. White phosphorus particles were found to be persistent in saturated sediments. In unsaturated sediments, loss was rapid (within 24 h) at 20 C, and was retarded by low temperatures.

  5. Marsh Equilibrium Theory: A Paleo Perspective

    NASA Astrophysics Data System (ADS)

    Morris, J. T.; Kemp, A.; Barber, D. C.; Culver, S. J.; Kegel, J.; Horton, B.

    2014-12-01

    Salt marshes adapt to changes in sea level by means of biogeomorphological feedback. These feedbacks maintain a dynamic equilibrium with sea level, within limits. Reconstructions of sea-level changes derived from salt-marsh sediment provide a paleo perspective for evaluating these feedbacks and for predicting the ecological effects of future sea-level rise. The Marsh Equilibrium Model (MEM) was modified to accommodate long records of sea level and sediment physical and chemical variables derived from high resolution (decadal and decimeter) reconstruction of sea level spanning the late Holocene using foraminifera preserved in North Carolina salt-marsh sediments. Model outputs from a run of nearly 1100-yr show periods of time when the marsh was predicted to be positioned near the top of the tidal frame (inundation time near zero) and times when the marsh was much deeper in the intertidal zone (inundation time of ca. 0.4). An elevation at mean sea level would correspond to an inundation time of 0.5, which is close to the lower limit of the vegetation and is indicative of a marsh that is just forming or, alternatively, a marsh that is on the verge of collapse. The model also indicates that the standing biomass on the marsh surface and sediment organic matter (SOM) content would have varied in harmony with the inundation time. In times past when the inundation time and the opportunity for mineral sedimentation decreased, the sediment organic matter (SOM) content increased. The low SOM concentration near the marsh surface today is consistent with a marsh that is low in the tidal frame. The SOM depth profile is a function of the relative elevation of the marsh, as well as changes in the input of inorganic sediment to the estuary. To effectively manage and preserve valuable salt-marsh ecosystems it is critical to accurately predict their response to projected sea-level changes.

  6. Suspended sediment deposition and trapping efficiency in a Delaware salt marsh

    NASA Astrophysics Data System (ADS)

    Moskalski, Susanne M.; Sommerfield, Christopher K.

    2012-02-01

    This study examined sediment deposition and retention in a section of salt marsh in the St. Jones River estuary in Delaware. Sediment traps, siphon samplers, a LISST particle sizer, and four water level sensors were deployed in a 100 m by 200 m grid over the course of a spring tide in June 2007. The objective was to determine the relative influences of suspended sediment concentration, settling velocity, tidal hydroperiod, and vegetation density on sediment deposition and trapping efficiency within a small section of marsh. Hydroperiod is not a major contributor to sediment deposition in the study plot. Spatial patterns in depositional processes on tidal timescales are instead primarily controlled by overmarsh SSC, settling velocity, and distance from the tidal channel. Trapping efficiency, or the ratio of measured deposition and the amount of sediment available for deposition, decreased with distance away from the tidal channel, indicating that less of the available suspended sediment was deposited in the marsh interior. The suspended particles were flocculated, but floc sizes decreased with distance away from the tidal channel.

  7. 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.

  8. Use of airborne polarimetric SAR, optical and elevation data for mapping and monitoring of salt marsh vegetation habitats

    NASA Astrophysics Data System (ADS)

    van Beijma, Sybrand; Comber, Alexis; Lamb, Alistair

    2014-10-01

    Within the Copernicus programme there is much interest in the ability of remote sensing technology to deliver operational solutions to many areas of life including environmental management. This paper describes research focused on the application of Earth Observation for Integrated Coastal Zone Management. The main topic of this research is to explore to which extent salt marsh vegetation habitats can be identified from polarimetric SAR remotely sensed data. Multi-frequency, multi-polarimetric SAR images from airborne (S- and X-Band quad-polarimetric from the Astrium airborne SAR Demonstrator) is used to examine salt marsh habitat classification potential in the Llanrhidian salt marshes in South Wales, UK. This is achieved by (1) using both supervised and unsupervised classification routines, using several polarimetric SAR data layers as backscatter intensity, band ratios and polarimetric decomposition products, and by (2) statistical analysis by regression of these different SAR data layers and botanical parameters acquired from recent ecological fieldwork.

  9. 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

  10. 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

  11. 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

  12. 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.

  13. 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

  14. Dynamics of Rainfall-mobilized Suspended Particulate Organic Carbon in Salt Marsh Tidal Creeks

    NASA Astrophysics Data System (ADS)

    Chen, S.; Torres, R.; Goni, M. A.

    2011-12-01

    Climate models have projected a trend of more frequent and more intense rainfall events in many coastal landscapes due to goble climate change. Rainfall kinetic energy and runoff from severe thunderstorms have the ability to do a substantial amount of work on intertidal landscapes. For instance, low tide rainfall events can produce a 2-3 order of magnitude increase in suspended sediment concentration in subtidal channels. Moreover, low tide rainfall affects the bulk composition of carbon and other nutrients in surface sediments and in the water column. We sampled rainfall-mobilized suspended sediment in two intertidal creeks in North Inlet (South Carolina) salt marsh, examined their elemental (carbon and nitrogen), isotopic (δ13C and δ15N), CuO oxidation product (COP) compositions, Chlorophyll a content, and use upscaling methods, to analyze the biogeochemical composition of rainfall-entrained suspended particulate organic carbon (RSPOC) and quantify the flux of RSPOC between marsh platform and subtidal channel. The concentrations and compositions of RSPOC varied widely but were significantly different from no-rain samples and salt marsh surface sediment. COP parameters such as lignin contents are higher in RSPOC, indicating a preferential transportation of terrestrial materials. Acid/aldehyde ratios of vanillyl and syringyl phenols, cinnamyl/vanillyl ratios and syringyl/vanillyl ratios indicate that RSPOC is more degraded and from distinct terrigenous sources. Chla/TSS ratio indicates that rainfall-entrained sediment contains less biotic material. Preliminary results indicated that 7-12 tons/km2 of POC can be mobilized in a single rain event. Therefore, low tide rainfall-runoff processes likely detach and transport organic matter which is compositionally distinct from tidally-resuspended particulate matter. The RSPOC is more degraded, with more of a terrestrial contribution and a higher abundance of abiotic materials. The significant input of these specific

  15. 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. PMID:24584003

  16. 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. PMID:26094036

  17. 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

  18. Comparison of Bulk and Compound-Specific Carbon Isotope Analyses and Determination of Carbon Sources to Salt Marsh Sediments Using n-Alkane Distributions (Maine, USA)

    NASA Astrophysics Data System (ADS)

    Tanner, B. R.; Uhle, M. E.; Kelley, J. T.; Mora, C. I.

    2005-12-01

    Sources of sedimentary organic matter to a Morse River, Maine (USA) salt marsh over the last 3390+/-60 RCYBP are determined using distribution patterns of n-alkanes as well as bulk and compound-specific carbon isotopic analysis. Marsh foraminiferal counts indicate the ubiquitous presence of zone 1B deposits, suggesting that the deposits were laid down ~0.2 to 0.5m above mean high water. Distributions of n-alkanes show a primary contribution from higher plants, confirmed by an average ACL value of 27.5 for the core sediments and CPI values above 3. Many sample depths have a maximum abundance at the C25 alkane. Ten low marsh, high marsh, and higher-high marsh plant species common to Maine salt marshes were sampled, including Spartina alterniflora, Spartina patens, Juncus gerardi and Solidago sempervirens. The ACL value for the average of the 10 marsh species is 29.1. Salicornia europa, usually not considered to be a dominant species in Maine marshes, has a similar n-alkane distribution to many of the salt marsh sediments, suggesting that it is an important source to the biomass of the marsh through time. Bacterial degradation or algal inputs to the marsh sediments appear to be minor. Compound specific carbon isotopic analyses of the C27 alkanes are, on average, 7.2ppt. depleted relative to bulk values, but the two records are strongly correlated (R2 = 0.87), suggesting that marsh plants are "swamping" the bulk carbon isotopic signal. The apparent abundance of a subordinate (though common) salt marsh plant species (Salicornia europa) within our core underscores the importance of using caution when applying mixing models of relatively few plant species to marsh sediments.

  19. 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

  20. 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.

  1. 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 marsh scale, a key piece of information to understand marsh responses to a changing climate, remains virtually unexplored. In order to characterize the relative importance of organic vs. inorganic deposition as a function of space, we collected 33 shallow soil sediment samples along three transects in the San Felice and Rigà salt marshes located in the Venice lagoon, Italy. The amount of organic matter in each sample was evaluated using Loss On Ignition (LOI), a hydrogen peroxide (H2O2) treatment, and a sodium hypochlorite (NaClO) treatment following the H2O2 treatment. The grain size distribution of the inorganic fraction was determined using laser diffraction techniques. Our study marshes exhibit a weakly concave-up profile, with maximum elevations and coarser inorganic grains along their edges. The amount of organic and inorganic matter content in the samples varies with the distance from the marsh edge and is very sensitive to the specific analysis method adopted. The use of a H2O2+NaClO treatment yields an organic matter density value which is more than double the value obtained from LOI. Overall, inorganic contributions to soil formation are greatest near the marsh edges, whereas organic soil production is the main contributor to soil accretion in the inner marsh. We interpret this pattern by considering that while plant biomass productivity is generally lower in the inner part of the marsh, organic soil decomposition rates are highest in the better aerated edge soils. Hence the higher

  2. Aquatic insects of New York salt marsh associated with mosquito larval habitat and their potential utility as bioindicators.

    PubMed

    Rochlin, Ilia; Dempsey, Mary E; Iwanejko, Tom; Ninivaggi, Dominick V

    2011-01-01

    The aquatic insect fauna of salt marshes is poorly characterized, with the possible exception of biting Diptera. Aquatic insects play a vital role in salt marsh ecology, and have great potential importance as biological indicators for assessing marsh health. In addition, they may be impacted by measures to control mosquitoes such as changes to the marsh habitat, altered hydrology, or the application of pesticides. Given these concerns, the goals of this study were to conduct the first taxonomic survey of salt marsh aquatic insects on Long Island, New York, USA and to evaluate their utility for non-target pesticide impacts and environmental biomonitoring. A total of 18 species from 11 families and five orders were collected repeatedly during the five month study period. Diptera was the most diverse order with nine species from four families, followed by Coleoptera with four species from two families, Heteroptera with three species from three families, then Odonata and the hexapod Collembola with one species each. Water boatmen, Trichocorixa verticalis Fieber (Heteroptera: Corixidae) and a shore fly, Ephydra subopaca Loew (Diptera: Ephydridae), were the two most commonly encountered species. An additional six species; Anurida maritima Guérin-Méneville (Collembola: Neanuridae), Mesovelia mulsanti White (Heteroptera: Mesovelidae), Enochrus hamiltoni Horn (Coleoptera: Hydrophilidae), Tropisternus quadristriatus Horn (Coleoptera: Hydrophilidae), Dasyhelea pseudocincta Waugh and Wirth (Diptera: Ceratopogonidae), and Brachydeutera argentata Walker (Diptera: Ephydridae), were found regularly. Together with the less common Erythrodiplax berenice Drury (Odonata: Libellulidae), these nine species were identified as the most suitable candidates for pesticide and environmental impact monitoring due to abundance, position in the food chain, and extended seasonal occurrence. This study represents a first step towards developing an insect-based index of biological integrity for

  3. Free-living plathelminthes in sheep-grazed and ungrazed supralittoral salt marshes of the North Sea: Abundance, biomass, and their significance in food chains

    NASA Astrophysics Data System (ADS)

    Armonies, W.

    The supralittoral salt marshes of the North Sea are marked by high halophyte primary productivity. The environmental factors are strongly fluctuating. Despite these features the metazoan meiofaunal abundance is equal to that found in other littoral habitats. On average 1250 marine metazoans are found per 10 cm 2 in ungrazed and 770 per 10 cm 2 in sheep-grazed supralittoral salt marshes. Nematoda dominate in numerical abundance, Oligochaeta in biomass. Plathelminthes account for 15% of marine metazoans in ungrazed and 5% in grazed salt marshes. Total plathelminth abundance increases with halophyte density, whereas the abundance of diatom-feeding Plathelminthes decreases. In ungrazed marshes on average 104 Plathelminthes are found per 10 cm 2, accounting for a biomass of 0.65 g DW·m -2. In sheep-grazed marshes the average abundance is only 32 individuals per 10 cm 2, accounting for a biomass of 0.1 g DW·m -2. Average individual weight is 3.2 μg DW or 2.5 μg AFDW. In grazed salt marshes, 30% of plathelminthes feed on diatoms, 66% are predators, and 4% feed on bacteria (gut analysis). In ungrazed salt marshes only 3% are diatom-feeders, and 90% are predators feeding on Nematoda, Copepoda, Oligochaeta, and smaller Plathelminthes. Presumably plathelminthes are top predators on the salt marsh meiofauna.

  4. New England Salt Marsh Recovery: Opportunistic Colonization of an Invasive Species and Its Non-Consumptive Effects

    PubMed Central

    Coverdale, Tyler C.; Axelman, Eric E.; Brisson, Caitlin P.; Young, Eric W.; Altieri, Andrew H.; Bertness, Mark D.

    2013-01-01

    Predator depletion on Cape Cod (USA) has released the herbivorous crab Sesarmareticulatum from predator control leading to the loss of cordgrass from salt marsh creek banks. After more than three decades of die-off, cordgrass is recovering at heavily damaged sites coincident with the invasion of green crabs (Carcinusmaenas) into intertidal Sesarma burrows. We hypothesized that Carcinus is dependent on Sesarma burrows for refuge from physical and biotic stress in the salt marsh intertidal and reduces Sesarma functional density and herbivory through consumptive and non-consumptive effects, mediated by both visual and olfactory cues. Our results reveal that in the intertidal zone of New England salt marshes, Carcinus are burrow dependent, Carcinus reduce Sesarma functional density and herbivory in die-off areas and Sesarma exhibit a generic avoidance response to large, predatory crustaceans. These results support recent suggestions that invasive Carcinus are playing a role in the recovery of New England salt marshes and assertions that invasive species can play positive roles outside of their native ranges. PMID:24009763

  5. Native plant restoration combats environmental change: development of carbon and nitrogen sequestration capacity using small cordgrass in European salt marshes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Restoration of salt marshes is critical in the context of climate change and eutrophication of coastal waters, because their vegetation and sediments may act as carbon and nitrogen sinks. Our primary objectives were to quantify carbon (C) and nitrogen (N) stocks and sequestration rates in restored m...

  6. Ecological effects of climate change on salt marsh wildlife: a case study from a highly urbanized estuary

    USGS Publications Warehouse

    Thorne, Karen M.; Takekawa, John Y.; Elliott-Fisk, Deborah L.

    2012-01-01

    Coastal areas are high-risk zones subject to the impacts of global climate change, with significant increases in the frequencies of extreme weather and storm events, and sea-level rise forecast by 2100. These physical processes are expected to alter estuaries, resulting in loss of intertidal wetlands and their component wildlife species. In particular, impacts to salt marshes and their wildlife will vary both temporally and spatially and may be irreversible and severe. Synergistic effects caused by combining stressors with anthropogenic land-use patterns could create areas of significant biodiversity loss and extinction, especially in urbanized estuaries that are already heavily degraded. In this paper, we discuss current ideas, challenges, and concerns regarding the maintenance of salt marshes and their resident wildlife in light of future climate conditions. We suggest that many salt marsh habitats are already impaired and are located where upslope transgression is restricted, resulting in reduction and loss of these habitats in the future. In addition, we conclude that increased inundation frequency and water depth will have negative impacts on the demography of small or isolated wildlife meta-populations as well as their community interactions. We illustrate our points with a case study on the Pacific Coast of North America at San Pablo Bay National Wildlife Refuge in California, an area that supports endangered wildlife species reliant on salt marshes for all aspects of their life histories.

  7. FATE OF FENTHION IN SALT-MARSH ENVIRONMENTS: 1. FACTORS AFFECTING BIOTIC AND ABIOTIC DEGRADATION RATES IN WATER AND SEDIMENT

    EPA Science Inventory

    Fenthion (Baytex), an organophosphate insecticide, is frequently applied to salt-marsh environments to control mosquitoes. hake-flask tests were used to study rates of abiotic and biotic degradation of fenthion and the environmental parameters that affect these rates. Water or wa...

  8. Nitrogen retention in salt marsh systems across nutrient-enrichment, elevation, and precipitation regimes: a multiple stressor experiment

    EPA Science Inventory

    In the Northeastern U.S., multiple anthropogenic stressors, including changing nutrient loads, accelerated sea-level rise, and altered climactic patterns are co-occurring, and are likely to influence salt marsh nitrogen (N) dynamics. We conducted a multiple stressor mesocosm expe...

  9. Examination of Below-Ground Structure and Soil Respiration Rates of Stable and Deteriorating Salt Marshes in Jamaica Bay (NY)

    EPA Science Inventory

    CAT scan imaging is currently being used to examine below-ground peat and root structure in cores collected from salt marshes of Jamaica Bay, part of the Gateway National Recreation Area (NY). CAT scans or Computer-Aided Tomography scans use X-ray equipment to produce multiple i...

  10. EFFECTS OF SALT MARSH ALTOSID EXPOSURE ON FEMALE GROWTH & PRODUCTION IN GULF SAND FIDDLER CRAB, UCA PANACEA

    EPA Science Inventory

    Effects of Salt Marsh Altosid(R) Exposure on Female Growth and Reproduction in the Gulf Sand Fiddler Crab, Uca panacea (Abstract). Presented at the 62nd Annual Meeting of the Association of Southern Biologists, 4-7 July 2001, New Orleans, LA. 1 p.

    Adult Uca panacea were p...

  11. RELATIONSHIPS OF NITROGEN LOADINGS, RESIDENTIAL DEVELOPMENT, AND PHYSICAL CHARACTERISTICS WITH PLANT STRUCTURE IN NEW ENGLAND SALT MARSHES

    EPA Science Inventory

    We examined the vascular plant species richness and the extent, density, and height of Spartina species of ten Narragansett Bay, Rhode Island (United States) fringe salt marshes which had a wide range of residential land development N-loadings associated with their watersheds. Si...

  12. New England salt marsh recovery: opportunistic colonization of an invasive species and its non-consumptive effects.

    PubMed

    Coverdale, Tyler C; Axelman, Eric E; Brisson, Caitlin P; Young, Eric W; Altieri, Andrew H; Bertness, Mark D

    2013-01-01

    Predator depletion on Cape Cod (USA) has released the herbivorous crab Sesarmareticulatum from predator control leading to the loss of cordgrass from salt marsh creek banks. After more than three decades of die-off, cordgrass is recovering at heavily damaged sites coincident with the invasion of green crabs (Carcinusmaenas) into intertidal Sesarma burrows. We hypothesized that Carcinus is dependent on Sesarma burrows for refuge from physical and biotic stress in the salt marsh intertidal and reduces Sesarma functional density and herbivory through consumptive and non-consumptive effects, mediated by both visual and olfactory cues. Our results reveal that in the intertidal zone of New England salt marshes, Carcinus are burrow dependent, Carcinus reduce Sesarma functional density and herbivory in die-off areas and Sesarma exhibit a generic avoidance response to large, predatory crustaceans. These results support recent suggestions that invasive Carcinus are playing a role in the recovery of New England salt marshes and assertions that invasive species can play positive roles outside of their native ranges. PMID:24009763

  13. Implications of sedimentological and hydrological processes on the distribution of radionuclides in a salt marsh near Sellafield, Cumbria

    SciTech Connect

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

    1985-01-01

    The report examines sedimentological and hydrological processes affecting a salt marsh in the Ravenglass estuary, which is situated south of the Sellafield nuclear-fuel-reprocessing plant. The results are discussed in the context of the distribution of low-level radioactive effluent at the site.

  14. Temporal trends in microbial abundance and biodegradation in Louisiana salt marshes following the Deepwater Horizon oil spill

    NASA Astrophysics Data System (ADS)

    Mahmoudi, N.; Fulthorpe, R. R.; Zimmerman, A. R.; Silliman, B. R.; Slater, G. F.

    2012-12-01

    The Deepwater Horizon oil spill that began in April 2010 released approximately 4.9 million barrels of crude oil into the Gulf of Mexico waters. Coastal salt marshes experienced moderate to heavy oiling as spilled oils washed ashore and threatened economically important habitats. In situ biodegradation of petroleum by microbes is one of the most effective methods used to remediate oil spills. However, demonstrating biodegradation can be challenging due to heterogeneous distributions of contaminants and dynamic conditions of coastal ecosystems. Salt marshes provide a unique opportunity in which variations in the natural abundance of δ13C can be used to confirm in situ biodegradation of petroleum. Marsh grasses, specifically Spartina sp., have δ13C values of -12 to -14‰ whereas the BP crude oil has a δ13C signature of -27‰. Thus, the 13C content of microbial membrane lipids (which reflects their carbon source) can be used to detect incorporation of petroleum-derived carbon. We investigated biodegradation in marsh sediments in oiled and non-oiled portions of Barataria Bay, Louisiana which experienced some of the most extensive oil contamination. Samples were collected 3, 9 and 15 months following Deepwater Horizon oil intrusion to assess biodegradation over time. Total alkane and PAH analyses confirmed that by Oct 2011 (15 months), concentrations had been significantly reduced (by up to 50,000 ug/kg at some sites). Microbial phospholipid fatty acids (PLFA) analysis revealed that cell densities decreased over the 1 year sampling period across both oil-impacted and non-impacted sites indicating that, rather than petroleum presence, seasonal variability was likely the primary control on microbial abundance. The ranges of δ13C PLFA values in oil-impacted (-26.7 to -30.5‰ ± 1.0) and non-impacted sediments (-24.5 to -33.3‰ ± 0.7) in Oct 2010 overlap, thereby reducing confidence in confirmation of biodegradation at this time point. However, in Oct 2011, PLFA

  15. Invasion of tamarisk (Tamarix spp.) in a southern California salt marsh

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Exotic plants have been demonstrated to be one of the greatest threats to wetlands, as they are capable of altering ecosystem-wide physical and biological properties. One of the most problematic invaders in the western United States has been salt cedar, Tamarix sp., and the impacts of this species i...

  16. Plant communities as indicators of salt marsh hydrology A study at Goose Fare Brook, Saco, Maine

    SciTech Connect

    Millette, P.M. . Dept. of Geological Sciences)

    1993-03-01

    Salt marsh stratigraphy often relies on vegetation fragment distribution as an indicator of paleo-sea level. This study is attempting to validate the use of Spartina alterniflora and Spartina patens at Goose Fare Brook in Saco, Maine as paleo-sea level indicators. Plant zones were mapped and each zone boundary was surveyed to describe the relationship between sea level and plant species zonation. Data showing the contact elevations between S. patens and S. alterniflora were examined, and contacts from different environments in the marsh were compared. Differences in contact elevations ranged from only a few centimeters to more than eighty centimeters. Three series of groundwater monitoring wells were installed along transects. Within a single transect, one well was placed in the creek bottom, measuring the free water surface, and one was placed at each of several plant zone boundaries. Strip chart recordings from one series of monitoring wells show the flood dominated patterns of tidally influenced groundwater fluctuations in the wells. Root depths of 100 plugs each of S. alterniflora and S. patens were also measured. A comparison of these measurements and those from monitoring wells will assist in the determination of the average length of submergence time for each species. Preliminary findings suggest that sea level is not the only force affecting the modern zonation of these two indicator plants in Goose Fare Brook.

  17. Nitrogen dynamics in an Alaskan salt marsh following spring use by geese

    USGS Publications Warehouse

    Zacheis, A.; Ruess, R.W.; Hupp, J.W.

    2002-01-01

    Lesser snow geese (Anser caerulescens caerulescens) and Canada geese (Branta canadensis) use several salt marshes in Cook Inlet, Alaska, as stopover areas for brief periods during spring migration. We investigated the effects of geese on nitrogen cycling processes in Susitna Flats, one of the marshes. We compared net nitrogen mineralization, organic nitrogen pools and production in buried bags, nitrogen fixation by cyanobacteria, and soil and litter characteristics on grazed plots versus paired plots that had been exclosed from grazing for 3 years. Grazed areas had higher rates of net nitrogen mineralization in the spring and there was no effect of grazing on organic nitrogen availability. The increased mineralization rates in grazed plots could not be accounted for by alteration of litter quality, litter quantity, microclimate, or root biomass, which were not different between grazed and exclosed plots. In addition, fecal input was very slight in the year that we studied nitrogen cycling. We propose that trampling had two effects that could account for greater nitrogen availability in grazed areas: litter incorporation into soil, resulting in increased rates of decomposition and mineralization of litter material, and greater rates of nitrogen fixation by cyanobacteria on bare, trampled soils. A path analysis indicated that litter incorporation by trampling played a primary role in the nitrogen dynamics of the system, with nitrogen fixation secondary, and that fecal input was of little importance.

  18. The role of elevation, relative sea-level history and vegetation transition in determining carbon distribution in Spartina alterniflora dominated salt marshes

    NASA Astrophysics Data System (ADS)

    Kulawardhana, Ranjani W.; Feagin, Rusty A.; Popescu, Sorin C.; Boutton, Thomas W.; Yeager, Kevin M.; Bianchi, Thomas S.

    2015-03-01

    Spartina alterniflora salt marshes are among the most productive ecosystems on earth, and represent a substantial global carbon sink. Understanding the spatial heterogeneity in the distribution of both above- and below-ground carbon in these wetland ecosystems is especially important considering their potential in carbon sequestration projects, as well as for conservation efforts in the context of a changing climate and rising sea-level. Through the use of extensive field sampling and remote sensing data (Light Detection and Ranging - LiDAR, and aerial images), we sought to map and explain how vegetation biomass and soil carbon are related to elevation and relative sea-level change in a S. alterniflora dominated salt marsh on Galveston Island, Texas. The specific objectives of this study were to: 1) understand the relationship between elevation and the distribution of salt marsh vegetation percent cover, plant height, plant density, above-and below-ground biomass, and carbon, and 2) evaluate the temporal changes in relative sea-level history, vegetation transitions, and resulting changes in the patterns of soil carbon distribution. Our results indicated a clear zonation of terrain and vegetation characteristics (i.e., height, cover and biomass). In the soil profile, carbon concentrations and bulk densities showed significant and abrupt change at a depth of ∼10-15 cm. This apparent transition in the soil characteristics coincided temporally with a transformation of the land cover, as driven by a rapid increase in relative sea-level around this time at the sample locations. The amounts of soil carbon stored in recently established S. alterniflora intertidal marshes were significantly lower than those that have remained in situ for a longer period of time. Thus, in order to quantify and predict carbon in coastal wetlands, and also to understand the heterogeneity in the spatial distribution of carbon stocks, it is essential to understand not only the elevation, the

  19. Role of different salt marsh plants on metal retention in an urban estuary (Lima estuary, NW Portugal)

    NASA Astrophysics Data System (ADS)

    Almeida, C. M. R.; Mucha, Ana P.; Teresa Vasconcelos, M.

    2011-01-01

    The aim of the present work was to understand the role different salt marsh plants on metal distribution and retention in the Lima River estuary (NW Portugal), which to our knowledge have not been ascertained in this area yet. The knowledge of these differences is an important requirement for the development of appropriate management strategies, and is poorly described for Eurosiberian estuaries, like the one selected. In addition it is important to understand the difference among introduced and native salt marsh plants. In this work, metal levels (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were surveyed (by atomic absorption spectrometry) in sediments from sites vegetated with Juncus maritimus, Spartina patens, Phragmites australis and Triglochin striata (rhizo-sediments), in non-vegetated sediments and in the different tissues of the plants (roots, rhizomes and aerial shoots). In general, rhizo-sediments had higher metal concentrations than non-vegetated sediments, a feature that seems common to sediments colonized by salt marsh plants of different estuarine areas. All plants concentrated metals, at least Cd, Cu and Zn (and Pb for T. striata) in their belowground structures ([ M] belowground tissues/[ M] non-vegetated sediment > 1). However, when considered per unit of salt marsh area, the different selected plants played a different role on sediment metal distribution and retention. Triglochin striata retained a significant metal burden in it belowground structures (root plus rhizomes) acting like a possible phyto-stabilizer, whereas P. australis had an higher metal burden in aboveground tissues acting as a possible phyto-extractor. As for J. maritimus and S. patens, metal burden distribution between above and belowground structures depended on the metal, with J. maritimus retaining, for instance, much more Cd and Cu in the aboveground than in the belowground structures. Therefore, the presence of invasive and exotic plants in some areas of the salt marsh may

  20. A multi-proxy study of sedimentary humic substances in the salt marsh of the Changjiang Estuary, China

    NASA Astrophysics Data System (ADS)

    Zhang, Yaoling; Du, Jinzhou; Zhao, Xin; Wu, Wangsuo; Peng, Bo; Zhang, Jing

    2014-12-01

    To better understand the origin, composition, and reactivity of sedimentary humic substances (HSs) in salt marshes in the Changjiang Estuary, HS samples were isolated from a sediment core that was collected from the Eastern Chongming salt marsh. Chemical and spectroscopic methods were used to analyze the features of these HSs. The results indicate that the studied HSs in the salt marsh sediments are mainly terrestrial-derived and that the sedimentary organic matter (SOM) in the top layer may contain more organic matter from marine sources and/or autochthonous materials due to the dramatic decreasing of the sediment supply as a result of damming. The degradation of labile carbohydrates and proteins and the preservation of refractory lignin components dominate the early diagenetic reactions of SOM in the salt marsh area. The average contents of the carboxylic groups in FAs and HAs are 11.64 ± 1.08 and 7.13 ± 0.16 meq/gC, and those of phenolic groups are 1.95 ± 0.13 and 2.40 ± 0.44 meq/gC, respectively. The content of carboxylic groups increased with increasing depth, while there were no obvious changes in the content of phenolic groups. The average concentration of total proton-binding sites is approximately 12.5 μmol/g sediment for the studied HSs. These values may provide insight into the migration and fate of HS-bound contaminants in sediments and the overlying sea water in the salt marsh areas of the Changjiang Estuary.

  1. Seasonal variation of bromine monoxide over the Rann of Kutch salt marsh seen from space

    NASA Astrophysics Data System (ADS)

    Hörmann, Christoph; Beirle, Steffen; Penning de Vries, Marloes; Sihler, Holger; Platt, Ulrich; Wagner, Thomas

    2015-04-01

    Bromine monoxide (BrO) is an important catalyst in the depletion of tropospheric and stratospheric ozone (O3). In the troposphere, reactive bromine can be released from sea ice, volcanoes, sea-salt aerosol or salt lakes. For all of these natural sources enhanced BrO vertical column densities (VCDs) have been successfully observed from ground using Differential Optical Absorption Spectroscopy (DOAS). Until now, satellite observations were only reported for polar regions during springtime and volcanic emissions (mostly for major eruptions). We present the first satellite observations of enhanced monthly mean BrO VCDs over a salt marsh, the Rann of Kutch (India/Pakistan), during 2004-2014 as seen by the Ozone Monitoring Instrument (OMI). The Rann of Kutch is a so-called 'seasonal' salt marsh. During India's summer monsoon (June/July - September/October), the flat desert of salty clay and mudflats, which average 15 meters above sea level, fills with standing rain and sea water. With more than 7500 km2 it is the largest salt desert in the world and additionally one of the hottest areas of India with summer temperatures around 50 ° C and winter temperatures decreasing below 0 ° C. Probably due to these rather extreme conditions, the Rann of Kutch has not been yet investigated for atmospheric composition measurements by ground-based instruments. Satellite observations, however, provide the unique possibility to investigate the entire area remotely over a long-time period. The OMI data reveals recurring maximum BrO VCDs during April/May, but no enhanced column densities during the monsoon season while the area is flooded. In the following months the signal only recovers slowly while the salty surface dries up. We discuss the possible effects of temperature, precipitation and relative humidity on the release of enhanced reactive bromine concentrations. In order to investigate a possible diurnal cycle of the BrO concentration, the OMI results (at a local overflight time

  2. Impact of Deepwater Horizon Oil Contamination on the Aqueous Geochemistry of Salt Marsh Sediment/Seawater Microcosms

    NASA Astrophysics Data System (ADS)

    Rentschler, E. K.; Donahoe, R. J.

    2011-12-01

    On April 20th, 2010, the Deepwater Horizon oil drilling rig, located in the Gulf of Mexico about 41 miles off the Louisiana coast, exploded, burned for two days, and sank. Approximately 4.9 million gallons of crude oil were released and traveled with ocean currents to reach the coasts of Louisiana, Mississippi, Alabama, and Florida. Previous studies have primarily considered the direct impact of oil and dispersant contamination on coastal ecosystems, but have not examined the potential impact of the accident on the inorganic geochemistry of coastal waters and sediments. In this study, microcosm experiments were conducted to determine how oil contamination will affect the concentration and distribution of trace elements in a salt marsh environment. Uncontaminated sediment and seawater, collected from a salt marsh at Bayou la Batre, Alabama, were measured into jars and spiked with 500 ppm MC-252 oil. Twenty jars, including duplicates and both sterile and non-sterile controls, were placed on a shaker table at 100 rpm. The jars were sacrificed at predetermined time intervals (0 h, 6 h, 12 h, 24 h, 48 h, 7 d, and 14 d), and the aqueous samples prepared for analysis by ICP-OES and IC. The pH for the water in the time series experiment ranged from 7.16 to 8.06. Seawater alkalinity was measured at 83.07 mg CaCO3/L. ICP-OES data show variations in aqueous element concentrations over the 14 day microcosm experiment. Significant positive correlations (>0.75) were found for the following pairs of elements: calcium and magnesium, calcium and sodium, magnesium and sodium, silica and boron, beryllium and boron, iron and silica, manganese and silica, boron and manganese, arsenic and nickel, beryllium and selenium, beryllium and zinc, copper and chloride, bromide and sulfate. Aqueous iron concentrations were highly correlated with solution pH. The presence of iron oxide and clays in the sediment indicates a potential for adsorption of trace elements sourced from the environment and

  3. Biogeochemistry of the Stable Isotopes of Hydrogen and Carbon in Salt Marsh Biota 1

    PubMed Central

    Smith, Bruce N.; Epstein, Samuel

    1970-01-01

    Deuterium to hydrogen ratios of 14 plant species from a salt marsh and lagoon were 55‰ depleted in deuterium relative to the environmental water. Carbon tetrachloride-extractable material from these plants was another 92‰ depleted in deuterium. This gave a fractionation factor from water to CCl4 extract of 1.147. This over-all fractionation was remarkably constant for all species analyzed. Plants also discriminate against 13C, particularly in the lipid fraction. Data suggest that different mechanisms for carbon fixation result in different fractionations of the carbon isotopes. Herbivore tissues reflected the isotopic ratios of plants ingested. Apparently different metabolic processes are responsible for the different degrees of fractionation observed for hydrogen and carbon isotopes. PMID:16657539

  4. Prescribed fire and cutting as tools for reducing woody plant succession in a created salt marsh

    USGS Publications Warehouse

    Owens, A.B.; Proffitt, C.E.; Grace, J.B.

    2007-01-01

    This paper reports on efforts to reduce woody successional growth by the native shrub Iva frutescens L. in a created salt marsh by using prescribed fire and cutting. Experimental treatments included a winter burn, cutting plants at ground level, and a combination burn-and-cut treatment, with replicate plots of each. Iva frutescens proved to be extremely hardy, with zero mortality following the cutting, burning, or combination treatment; similar levels of regrowth were observed for all treatments. Individual shrub response, however, was found to be related to initial plant size, ground water level and salinity, and two fire characteristics (total heating >60??C and total heat index >60??C). Fire severity, sediment nutrient concentrations, and other abiotic factors had no observable effects. ?? 2007 Springer Science+Business Media B.V.

  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, Christopher L.; Mikan, Molly P.; Etheridge, J. Randall; Burchell, Michael R.; Birgand, François

    2015-07-01

    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 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 (C) modeled, C3 represented recalcitrant DOM and C4 represented fresher soil-derived source DOM. Component 1 represented detrital POM, and C6 represented 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; no planktonic DOC was exported. 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. Assuming the exported organic matter was oxidized to CO2 and scaled up to global salt marsh area, respiration of salt marsh DOC and POC transported to estuaries could amount to a global CO2 flux of 11 Tg C yr-1, roughly 4% of the recently estimated CO2 release for marshes and estuaries globally.

  6. Phytoextraction of heavy metals by Sesuvium portulacastrum l. a salt marsh halophyte from tannery effluent.

    PubMed

    Ayyappan, Durai; Sathiyaraj, Ganesan; Ravindran, Konganapuram Chellappan

    2016-05-01

    The present study investigated the sources for remediation of heavy metals and salts from tannery effluent using salt marsh halophyte Sesuvium portulacastrum. From the results observed, in tannery effluent treated soil from 1 kg dry weight of plant sample, Sesuvium portulacastrum accumulated 49.82 mg Cr, 22.10 mg Cd, 35.10 mg Cu and 70.10 mg Zn and from 1 g dry weight of the plant sample, 246.21 mg Na Cl. Cultivation of Sesuvium portulacastrum significantly reduced the EC, pH and SAR levels in tannery effluent and salt treated soil and correspondingly increased in plant sample after 125 days of cultivation. In conclusion, Sesuvium portulacastrum was an efficient in accumulating heavy metals such as Chromium, Cadmium, Copper and Zinc, sodium and chloride maximum through its leaves when compared to stem and root. The finding of these bioacccumulation studies indicates that Sesuvium portulacastrum could be used for phytoremediation of tannery effluent contaminated field. PMID:26552858

  7. The effect of tidal forcing on biogeochemical processes in intertidal salt marsh sediments

    PubMed Central

    Taillefert, Martial; Neuhuber, Stephanie; Bristow, Gwendolyn

    2007-01-01

    Background Early diagenetic processes involved in natural organic matter (NOM) oxidation in marine sediments have been for the most part characterized after collecting sediment cores and extracting porewaters. These techniques have proven useful for deep-sea sediments where biogeochemical processes are limited to aerobic respiration, denitrification, and manganese reduction and span over several centimeters. In coastal marine sediments, however, the concentration of NOM is so high that the spatial resolution needed to characterize these processes cannot be achieved with conventional sampling techniques. In addition, coastal sediments are influenced by tidal forcing that likely affects the processes involved in carbon oxidation. Results In this study, we used in situ voltammetry to determine the role of tidal forcing on early diagenetic processes in intertidal salt marsh sediments. We compare ex situ measurements collected seasonally, in situ profiling measurements, and in situ time series collected at several depths in the sediment during tidal cycles at two distinct stations, a small perennial creek and a mud flat. Our results indicate that the tides coupled to the salt marsh topography drastically influence the distribution of redox geochemical species and may be responsible for local differences noted year-round in the same sediments. Monitoring wells deployed to observe the effects of the tides on the vertical component of porewater transport reveal that creek sediments, because of their confinements, are exposed to much higher hydrostatic pressure gradients than mud flats. Conclusion Our study indicates that iron reduction can be sustained in intertidal creek sediments by a combination of physical forcing and chemical oxidation, while intertidal mud flat sediments are mainly subject to sulfate reduction. These processes likely allow microbial iron reduction to be an important terminal electron accepting process in intertidal coastal sediments. PMID:17567893

  8. Changes in soils and vegetation in a Mediterranean coastal salt marsh impacted by human activities

    NASA Astrophysics Data System (ADS)

    Álvarez-Rogel, J.; Jiménez-Cárceles, F. J.; Roca, M. J.; Ortiz, R.

    2007-07-01

    This paper reports changes in vegetation distribution and species cover in relation to soil factors and hydrology in a semiarid Mediterranean salt marsh adjacent to the Mar Menor saline lagoon. Species cover, soil salinity, and the groundwater level were monitored between 1991 and 1993 and between 2002 and 2004, and total organic carbon, total nitrogen, total phosphorus, nitrates, ammonium and exchangeable phosphorus were measured in the soils in both study periods. In addition, three soil profiles were described in August 1992 and August 2004. The results indicate an elevation of the water table throughout the 13-year period, which was attributable to water flowing from areas with intensive agriculture. Flooding increased and soil salinity dropped in the most saline sites and increased in the least saline ones. The morphology of the soil profiles reflected the increase in flooding periods, due to the appearance of a greyer matrix in the deeper horizons and a more diffuse pattern of Fe mottles. Following these environmental changes, Sarcocornia fruticosa, Phragmites australis and Juncus maritimus strongly expanded at the wettest sites, which led to the disappearance of the original zonation pattern. The cover of Limonium delicatulum, in turn, decreased with the increase in moisture but increased following the increase in salinity. Changes in soil nutrients were only very evident in the sandy soils of the beach, probably due to the influence of organic debris deposited on the shoreline by the storms and due to the strong increase in the colonisation of this habitat by perennial species. According to the results obtained, control measures are needed in order to preserve habitat diversity in this and other salt marshes of this area. Monitoring of the vegetation distribution could be a useful tool to identify environmental impacts, in order to implement remedial actions.

  9. Microbial Abundances in Salt Marsh Soils: A Molecular Approach for Small Spatial Scales

    NASA Astrophysics Data System (ADS)

    Granse, Dirk; Mueller, Peter; Weingartner, Magdalena; Hoth, Stefan; Jensen, Kai

    2016-04-01

    The rate of biological decomposition greatly determines the carbon sequestration capacity of salt marshes. Microorganisms are involved in the decomposition of biomass and the rate of decomposition is supposed to be related to microbial abundance. Recent studies quantified microbial abundance by means of quantitative polymerase chain reaction (QPCR), a method that also allows determining the microbial community structure by applying specific primers. The main microbial community structure can be determined by using primers specific for 16S rRNA (Bacteria) and 18S rRNA (Fungi) of the microbial DNA. However, the investigation of microbial abundance pattern at small spatial scales, such as locally varying abiotic conditions within a salt-marsh system, requires high accuracy in DNA extraction and QPCR methods. Furthermore, there is evidence that a single extraction may not be sufficient to reliably quantify rRNA gene copies. The aim of this study was to establish a suitable DNA extraction method and stable QPCR conditions for the measurement of microbial abundances in semi-terrestrial environments. DNA was extracted from two soil samples (top WE{5}{cm}) by using the PowerSoil DNA Extraction Kit (Mo Bio Laboratories, Inc., Carlsbad, CA) and applying a modified extraction protocol. The DNA extraction was conducted in four consecutive DNA extraction loops from three biological replicates per soil sample by reusing the PowerSoil bead tube. The number of Fungi and Bacteria rRNA gene copies of each DNA extraction loop and a pooled DNA solution (extraction loop 1 - 4) was measured by using the QPCR method with taxa specific primer pairs (Bacteria: B341F, B805R; Fungi: FR1, FF390). The DNA yield of the replicates varied at DNA extraction loop 1 between WE{25 and 85}{ng

  10. A regional assessment of salt marsh restoration and monitoring in the Gulf of Maine

    USGS Publications Warehouse

    Konisky, R.A.; Burdick, D.M.; Dionne, M.; Neckles, H.A.

    2006-01-01

    We compiled salt marsh monitoring datasets from 36 complete or imminent restoration projects in the Gulf of Maine to assess regional monitoring and restoration practices. Data were organized by functional indicators and restoration project types (culvert replacement, excavation works, or ditch plugging) then pooled to generate mean values for indicators before restoration, after restoration, and at reference sites. Monitoring data were checked against the regional standards of a voluntary protocol for the Gulf of Maine. Data inventories showed that vegetation and salinity indicators were most frequently collected (89 and 78% of sites, respectively), whereas nekton, bird, and hydrologic measures were collected at only about half of the sites. Reference conditions were monitored at 72% of sites. Indicators were analyzed to see if project sites were degraded relative to reference areas and to detect ecological responses to restoration activities. Results showed that compared to reference areas, prerestoration sites had smaller tidal ranges, reduced salinity levels, greater cover of brackish plants species, and lower cover of halophyte plants. Following restoration, physical factors rebounded rapidly with increased flood and salinity levels after about one year, especially for culvert projects. Biological responses were less definitive and occurred over longer time frames. Plant communities trended toward recovered halophytes and reduced brackish species at 3+ years following restoration. Nekton and avian indicators were indistinguishable among reference, impacted, and restored areas. The protocol was successful in demonstrating restoration response for the region, but results were limited by regional inconsistencies in field practices and relatively few multiyear datasets. To improve future assessment capabilities, we encourage greater adherence to the standard protocol throughout the Gulf of Maine salt marsh restoration community.

  11. Salt marsh plants as key mediators on the level of cadmium impact on microbial denitrification.

    PubMed

    Almeida, C Marisa R; Mucha, Ana P; da Silva, Marta Nunes; Monteiro, Maria; Salgado, Paula; Necrasov, Tatiana; Magalhães, Catarina

    2014-09-01

    The fate of excess nitrogen in estuaries is determined by the microbial-driven nitrogen cycle, being denitrification a key process since it definitely removes fixed nitrogen as N2. However, estuaries receive and retain metals, which may negatively affect this process efficiency. In this study, we evaluated the role of salt marsh plants in mediating cadmium (Cd) impact on microbial denitrification process. Juncus maritimus and Phragmites australis from an estuary were collected together with the sediment involving their roots, each placed in vessels and maintained in a greenhouse, exposed to natural light, with tides simulation. Similar non-vegetated sediment vessels were prepared. After 3 weeks of accommodation, nine vessels (three per plant species plus three non-vegetated) were doped with 20 mg/L Cd(2+) saline solution, nine vessels were doped with 2 mg/L Cd(2+) saline solution and nine vessels were left undoped. After 10 weeks, vessels were dissembled and denitrification potential was measured in sediment slurries. Results revealed that the addition of Cd did not cause an effect on the denitrification process in non-vegetated sediment but had a clear stimulation in colonized ones (39 % for P. australis and 36 % for J. maritimus). In addition, this increase on denitrification rates was followed by a decrease on N2O emissions and on N2O/N2 ratios in both J. maritimus and P. australis sediments, increasing the efficiency of the N2O step of denitrification pathway. Therefore, our results suggested that the presence of salt marsh plants functioned as key mediators on the degree of Cd impact on microbial denitrification. PMID:24792983

  12. Aquatic macroinvertebrate communities of natural and ditched potholes in a San Francisco Bay salt marsh

    NASA Astrophysics Data System (ADS)

    Barnby, Mark A.; Collins, Joshua N.; Resh, Vincent H.

    1985-03-01

    Differences in macroinvertebrate community structure and composition were examined from April 1980 to March 1981 in three potholes that had been ditched for mosquito control and three natural (i.e. unditched) potholes, which are located in a San Francisco Bay, California, U.S.A. salt marsh. Measurements of incipient tidal flooding into potholes (i.e. pothole inundation threshold) indicated that these sites comprise a gradient of tidal influences. Exponential decreases in the frequency and duration of tidal inundation corresponded to linear increases in inundation threshold. Since ditched study sites had low thresholds they tended to be more uniformly and regularly influenced by tides, were less saline, had less variable temperature regimens, and supported less filamentous algae than natural potholes. Habitat conditions were generally more similar among ditched than unditched potholes, but environmental conditions were most severe at natural sites near the upper limit of the inundation threshold gradient, where some potholes desiccate during the dry season each year. Differences in macroinvertebrate communities corresponded to differences in habitat conditions. Species richness and diversity (Simpson's Index) were generally highest near the middle of the inundation threshold gradient, which is a pattern predicted by the Intermediate Disturbance Hypothesis. Analysis of faunal composition using discriminant functions indicated more similarity among potholes located at the lowest positions of the inundation gradient than among potholes with intermediate thresholds. Since ditching lowers the inundation thresholds of potholes, it reduces species richness and diversity, while increasing faunal similarity. As a result, extensive ditching to control salt marsh mosquitoes can reduce the overall complexity of lentic macroinvertebrate communities.

  13. Mercury uptake and allocation in Juncus maritimus: implications for phytoremediation and restoration of a mercury contaminated salt marsh.

    PubMed

    Figueira, Etelvina; Freitas, Rosa; Pereira, Eduarda; Duarte, Armando

    2012-08-01

    Juncus maritimus is the most abundant macrophyte in Laranjo bay, a Portuguese salt marsh heavily polluted by mercury (Hg). With the aim to elucidate the role of this species in the salt marsh Hg cycling and restoration, plants were harvested between March 2006 and January 2008 from four locations differing in Hg contamination. Metal uptake and distribution between plant organs were evaluated, biomass and Hg pools were also determined. Results showed that J. maritimus may influence the sediment pH and Eh, thus increasing the Hg available for uptake. Most (95-98%) of the absorbed Hg was retained belowground, phytostabilizing the metal and reducing the amount of Hg in the sediments. These results suggest that in salt marshes dominated by J. maritimus the approach could be phytostabilization, where these plants can be used to immobilize metals and store them belowground, reducing the pool of bioavailable Hg within contaminated marshes and acting as a sink rather than a source of contamination to the surrounding areas. PMID:22739436

  14. Accumulation of soil carbon drives denitrification potential and lab-incubated gas production along a chronosequence of salt marsh development

    NASA Astrophysics Data System (ADS)

    He, Yanlong; Widney, Sarah; Ruan, Michelle; Herbert, Ellen; Li, Xiuzhen; Craft, Christopher

    2016-04-01

    We measured sediment organic carbon and nitrogen accumulation and rates of denitrification enzyme activity and greenhouse gas (CO2, CH4, N2O) production from slurries of sediments of a mudflat that formed in 2002, a young (8-year-old) natural Spartina alterniflora salt marsh that developed on part of the mudflat, and four mature (>200 years old) salt marshes in southeastern Georgia to examine microbial processes related to carbon (C) and nitrogen (N) cycling during succession from mudflat to mature marsh. Soil organic C and N and C: N ratio (0-30 cm) increased across the chronosequence from mudflat (791 ± 35 g C/m2, 125 ± 17 g N/m2) to young marsh (2520 ± 131 g C/m2, 190 ± 10 g N/m2) to mature marshes (5827 ± 250 g C/m2, 372 ± 20 g N/m2). After 8 years of colonization by S. alterniflora, sediment organic carbon increased 3.2 times, and nitrogen increased 1.5 times relative to the mudflat. The high rate of organic C and N accumulation based on time series measurements (188 g C/m2/yr, 7.8 g N/m2/yr) and feldspar marker layers (359 g C/m2/yr, 26.2 g N/m2/yr) was attributed to high accretion (3 cm/yr) in this low elevation (0.18 m NAVD88) emerging marsh. Carbon dioxide production increased with increasing sediment organic C from mudflat to mature marshes. Un-amended denitrification enzyme activity, measured in slurry incubations, ranged from an average of 0.020 ± 0.005 μg g-1 hr-1 in the mature marshes to 0.094 ± 0.03 μg g-1 hr-1 in the young marsh. We also measured denitrification potential in slurry incubations amended with C (glucose), N (nitrate), and C + N to assess the potential for substrate limitations. Denitrification potential in the mudflat did not show strong nutrient limitation. In the young marsh, denitrification potential was C-limited, and in the mature marsh, it was co-limited by C and N. In July samples, CO2 production showed a statistically significant increase with age from the mudflat to the mature marshes. However, in both months, CO2

  15. Seasonal patterns in energy partitioning of two freshwater marsh ecosystems in the Florida Everglades

    NASA Astrophysics Data System (ADS)

    Malone, Sparkle L.; Staudhammer, Christina L.; Loescher, Henry W.; Olivas, Paulo; Oberbauer, Steven F.; Ryan, Michael G.; Schedlbauer, Jessica; Starr, Gregory

    2014-08-01

    We analyzed energy partitioning in short- and long-hydroperiod freshwater marsh ecosystems in the Florida Everglades by examining energy balance components (eddy covariance derived latent energy (LE) and sensible heat (H) flux). The study period included several wet and dry seasons and variable water levels, allowing us to gain better mechanistic information about the control of and changes in marsh hydroperiods. The annual length of inundation is ~5 months at the short-hydroperiod site (25°26'16.5″N, 80°35'40.68″W), whereas the long-hydroperiod site (25°33'6.72″N, 80°46'57.36″W) is inundated for ~12 months annually due to differences in elevation and exposure to surface flow. In the Everglades, surface fluxes feed back to wet season precipitation and affect the magnitude of seasonal change in water levels through water loss as LE (evapotranspiration (ET)). At both sites, annual precipitation was higher than ET (1304 versus 1008 at the short-hydroperiod site and 1207 versus 1115 mm yr-1 at the long-hydroperiod site), though there were seasonal differences in the ratio of ET:precipitation. Results also show that energy balance closure was within the range found at other wetland sites (60 to 80%) and was lower when sites were inundated (60 to 70%). Patterns in energy partitioning covaried with hydroperiods and climate, suggesting that shifts in any of these components could disrupt current water and biogeochemical cycles throughout the Everglades region. These results suggest that the complex relationships between hydroperiods, energy exchange, and climate are important for creating conditions sufficient to maintain Everglades ecosystems.

  16. Molecular hydrogen uptake by soils in forest, desert, and marsh ecosystems in California

    NASA Astrophysics Data System (ADS)

    Smith-Downey, Nicole V.; Randerson, James T.; Eiler, John M.

    2008-09-01

    The mechanism and environmental controls on soil hydrogen (H2) uptake are not well understood but are essential for understanding the atmospheric H2 budget. Field observations of soil H2 uptake are limited, and here we present the results from a series of measurements in forest, desert, and marsh ecosystems in southern California. We measured soil H2 fluxes using flux chambers from September 2004 to July 2005. Mean H2 flux rates and standard deviations were -7.9 + -4.2, -7.6 + -5.3 and -7.5 + -3.4 nmol m-2 s-1 for the forest, desert, and marsh, respectively (corresponding to deposition velocities of 0.063 + -0.029, 0.051 + -0.036, 0.035 + -0.013 cm s-1). Soil profile measurements showed that H2 mixing ratios were between 3% and 51% of atmospheric levels at 10 cm and that the penetration of H2 into deeper soil layers increased with soil drying. Soil removal experiments in the forest demonstrated that the litter layer did not actively consume H2, the removal of this layer increased uptake by deeper soil layers, and the exposure of subsurface soil layers to ambient atmospheric H2 levels substantially increased their rate of uptake. Similar soil removal experiments at the desert site showed that extremely dry surface soils did not consume H2 and that fluxes at the surface increased when these inactive layers were removed. We present a model of soil H2 fluxes and show that the diffusivity of soils, along with the vertical distribution of layers that actively consume H2 regulate surface fluxes. We found that soil organic matter, CO2 fluxes, and ecosystem type were not strong controllers of H2 uptake. Our experiments highlight H2 diffusion into soils as an important limit on fluxes and that minimum moisture level is needed to initiate microbial uptake.

  17. Salt Marsh and Phytoplankton Bloom Influences on the Composition and Metabolism of Organic Matter in a Temperate Estuary, Delaware, USA

    NASA Astrophysics Data System (ADS)

    Barnes, R. T.; Voynova, Y. G.; Ullman, W. J.; Sikes, E. L.; Aufdenkampe, A. K.

    2014-12-01

    Low oxygen levels within the Murderkill Estuary, DE, are largely driven by organic matter (OM) metabolism and chemical oxygen demand within the fringing salt marshes. To assess how the connectivity to and inundation of salt marshes impact OM quality and cycling within the Estuary, fluorescence excitation-emission matrix (EEM) data were used to characterize both dissolved and particulate OM pools. Parallel Factor Analysis (PARAFAC) identified five fluorophores that illustrated greater tidal variation in the particulate (POM) than dissolved (DOM) OM pools. The terrestrial-wetland and marine OM sources were statistically separated using the fluorophores in conjunction with the elemental composition and isotopic signature of particulates, as well as dissolved water chemistry (e.g. salinity, dissolved nitrogen, carbon, silica, and phosphorus). DOM pools in the Murderkill and leaving the marsh are dominated by soil humics, while POM pools have greater contributions of protein-rich sources and are generally are less processed. Tidal survey results point to the salt marshes as a sink of fine particulates, in particular protein rich OM, and a source of coarse particulates and DOM dominated by humic substances. Results from dark 24-hour bioassays suggest that coarse and fine POM pools are larger drivers of oxygen consumption than DOM pools. Correlations between community respiration rates during ebb tide, water chemistry, and OM fractions suggest that biological oxygen demand in the Murderkill is driven, in part, by the metabolism of protein-rich, phytoplankton from Delaware Bay. Thus, while the bulk of oxygen drawdown occurs within the salt marshes, in-stream metabolism appears to be driven by marine OM pools.

  18. The Protective Role of Coastal Marshes: A Systematic Review and Meta-analysis

    PubMed Central

    Shepard, Christine C.; Crain, Caitlin M.; Beck, Michael W.

    2011-01-01

    Background Salt marshes lie between many human communities and the coast and have been presumed to protect these communities from coastal hazards by providing important ecosystem services. However, previous characterizations of these ecosystem services have typically been based on a small number of historical studies, and the consistency and extent to which marshes provide these services has not been investigated. Here, we review the current evidence for the specific processes of wave attenuation, shoreline stabilization and floodwater attenuation to determine if and under what conditions salt marshes offer these coastal protection services. Methodology/Principal Findings We conducted a thorough search and synthesis of the literature with reference to these processes. Seventy-five publications met our selection criteria, and we conducted meta-analyses for publications with sufficient data available for quantitative analysis. We found that combined across all studies (n = 7), salt marsh vegetation had a significant positive effect on wave attenuation as measured by reductions in wave height per unit distance across marsh vegetation. Salt marsh vegetation also had a significant positive effect on shoreline stabilization as measured by accretion, lateral erosion reduction, and marsh surface elevation change (n = 30). Salt marsh characteristics that were positively correlated to both wave attenuation and shoreline stabilization were vegetation density, biomass production, and marsh size. Although we could not find studies quantitatively evaluating floodwater attenuation within salt marshes, there are several studies noting the negative effects of wetland alteration on water quantity regulation within coastal areas. Conclusions/Significance Our results show that salt marshes have value for coastal hazard mitigation and climate change adaptation. Because we do not yet fully understand the magnitude of this value, we propose that decision makers employ natural

  19. HUMAN IMPACTS ON NEW ENGLAND SALT MARSHES: PAST, PRESENT, AND FUTURE

    EPA Science Inventory

    Results from this research will explain differences between coastal marshes with different histories of human disturbance and distinguish between natural features of coastal marshes and features that are artifacts of human land use.

  20. Seasonal changes in community composition and trophic structure of fish populations of five salt marshes along the Essex coastline, United Kingdom

    NASA Astrophysics Data System (ADS)

    Green, Benjamin C.; Smith, David J.; Earley, Sarah E.; Hepburn, Leanne J.; Underwood, Graham J. C.

    2009-11-01

    European intertidal salt marshes are important nursery sites for juvenile fish and crustaceans. Due to the increasing threat of habitat loss, the seasonal changes of salt marsh fish communities need to be understood in order to appreciate the ecological and economic importance of the saltmarsh habitat. This study was the first in Great Britain to investigate the seasonal changes of salt marsh fish communities and the variation in community structure between closely located marsh habitats. Between February 2007 and March 2008, five marshes on three estuaries of the Essex coastline were sampled using flume nets to block off intertidal creeks at high tide. Fourteen fish species were caught. The community overall was dominated by three species that made up 91.6% of the total catch: the common goby Pomatoschistus microps (46.2% of the total catch), juvenile herring Clupea harengus (24.3%), and juvenile and larval sea bass Dicentrarchus labrax (21.2%). Cluster analysis demonstrated clear seasonal patterns, with some community structures unique to specific marshes or estuaries. The marsh fish community shifts from a highly diverse community during spring, to a community dominated by D. labrax and P. microps in autumn, and low diversity during winter months. Gravimetric stomach content analysis of fish community identified three main trophic guilds; macroinvertivores, planktivores and omnivores. The macroinvertivore feeding guild contained D. labrax and P. microps, the two most frequently occurring species. This investigation demonstrates the importance of British salt marshes as nursery habitats for commercial fish species.

  1. [Evolvement of soil quality in salt marshes and reclaimed farmlands in Yancheng coastal wetland].

    PubMed

    Mao, Zhi-Gang; Gu, Xiao-Hong; Liu, Jin-E; Ren, Li-Juan; Wang, Guo-Xiang

    2010-08-01

    Through vegetation investigation and soil analysis, this paper studied the evolvement of soil quality during natural vegetation succession and after farmland reclamation in the Yancheng coastal wetland of Jiangsu Province. Along with the process of vegetation succession, the soil physical, chemical, and biological properties in the wetland improved, which was manifested in the improvement of soil physical properties and the increase of soil nutrient contents, microbial biomass, and enzyme activities. Different vegetation type induced the differences in soil properties. Comparing with those in salt marshes, the soil salt content in reclaimed farmlands decreased to 0.01 - 0.04%, the soil microbial biomass and enzyme activities increased, and the soil quality improved obviously. The soil quality index (SQI) in the wetland was in the order of mudflat (0.194) < Suaeda salsa flat (0.233) < Imperata cylindrica flat (0.278) < Spartina alterniflora flat (0.446) < maize field (0.532) < cotton field (0.674) < soybean field (0.826), suggesting that positive vegetation succession would be an effective approach in improving soil quality. PMID:21043105

  2. The greenhouse gas flux and potential global warming feedbacks of a northern macrotidal and microtidal salt marsh

    USGS Publications Warehouse

    Chmura, Gail L.; Kellman, Lisa; Guntenspergen, Glenn R.

    2011-01-01

    Conversion of wetlands by drainage for agriculture or other anthropogenic activities could have a negative or positive feedback to global warming (GWF). We suggest that a major predictor of the GWF is salinity of the wetland soil (a proxy for available sulfate), a factor often ignored in other studies. We assess the radiative balance of two northern salt marshes with average soil salinities > 20 ppt, but with high (macro-) and low (micro-) tidal amplitudes. The flux of greenhouse gases from soils at the end of the growing season averaged 485 ± 253 mg m-2 h-1, 13 ± 30 μg m-2 h-1, and 19 ± 58 μg m-2 h-1 in the microtidal marsh and 398 ± 201 mg m-2 h-1, 2 ± 26 μg m-2 h-1, and 35 ± 77 μg m-2 h-1 in the macrotidal marsh for CO2, N2O, and CH4, respectively. High rates of C sequestration mean that loss of these marshes would have a radiative balance of - 981 CO2_eq. m-2 yr-1 in the microtidal and - 567 CO2_eq. m-2 yr-1 in the macrotidal marsh.

  3. Release of Dimethylsulfide from Dimethylsulfoniopropionate by Plant-Associated Salt Marsh Fungi

    PubMed Central

    Bacic, M. K.; Newell, S. Y.; Yoch, D. C.

    1998-01-01

    The range of types of microbes with dimethylsulfoniopropionate (DMSP) lyase capability (enzymatic release of dimethylsulfide [DMS] from DMSP) has recently been expanded from bacteria and eukaryotic algae to include fungi (a species of the genus Fusarium [M. K. Bacic and D. C. Yoch, Appl. Environ. Microbiol. 64:106–111, 1998]). Fungi (especially ascomycetes) are the predominant decomposers of shoots of smooth cordgrass, the principal grass of Atlantic salt marshes of the United States. Since the high rates of release of DMS from smooth cordgrass marshes have a temporal peak that coincides with peak shoot death, we hypothesized that cordgrass fungi were involved in this DMS release. We tested seven species of the known smooth cordgrass ascomycetes and discovered that six of them exhibited DMSP lyase activity. We also tested two species of ascomycetes from other DMSP-containing plants, and both were DMSP lyase competent. For comparison, we tested 11 species of ascomycetes and mitosporic fungi from halophytes that do not contain DMSP; of these 11, only 3 were positive for DMSP lyase. A third group tested, marine oomycotes (four species of the genera Halophytophthora and Pythium, mostly from mangroves), showed no DMSP lyase activity. Two of the strains of fungi found to be positive for DMSP lyase also exhibited uptake of DMS, an apparently rare combination of capabilities. In conclusion, a strong correlation exists between a fungal decomposer’s ability to catabolize DMSP via the DMSP lyase pathway and the host plant’s production of DMSP as a secondary product. PMID:16349548

  4. The Coordination and Harmonics of Biogeochemical Cycles in North Inlet, SC Salt Marshes

    NASA Astrophysics Data System (ADS)

    Morris, J. T.

    2015-12-01

    North Inlet is a pristine estuary within a small coastal watershed with minimal surface water input or human impact. North Inlet exchanges its water with the coastal ocean with a turnover time of about 0.5 per day. Its marshes are dominated by the grass Spartina alterniflora. Growth rates of Spartina have been measured monthly on permanent plots in North Inlet since 1984, and concentrations of porewater ammonium and phosphate, and sulfide have been measured monthly over depth (10-100 cm) since 1994. The salt marsh shows pronounced seasonal biogeochemical cycles that are highly correlated. Ammonium, phosphate and sulfide concentrations all peak in August-October and are minimal during February-April. Mean monthly ammonium concentration varies between 42 and 87 μM, phosphate between 3 and 18 μM, and sulfide between 8 and 87 μM. Monthly growth rates of Spartina range from 91 to 111 g dry weight m-2 between April and September. The integrated total aboveground production is 25 mol C m-2 yr-1. The inventories of N and P in porewater are small fractions of what is required to support primary production. Primary production is N-limited and this is consistent with the N:P ratio declining from 14 during early spring to 5 in late summer. There are losses, especially of N, from drainage, denitrification, and export of organic production. These have to be compensated by gains from N fixation, most likely from coupled sulfate reduction. There is also a coupling between sulfide, iron, and phosphorous that appears to conserve P during the winter and generate soluble P during the active growing season. These couplings coordinate the biogeochemical cycles, and this extends to the tidal creeks that are dominated by benthic sources of nutrients.

  5. Accelerated Rates of Nitrogen Cycling and N2O Production in Salt Marsh Sediments due to Long-Term Fertilization

    NASA Astrophysics Data System (ADS)

    Peng, X.; Ji, Q.; Angell, J.; Kearns, P.; Bowen, J. L.; Ward, B. B.

    2014-12-01

    Intensified sedimentary production of nitrous oxide (N2O), one of the most potent greenhouse gases, is one of the many possible environmental consequences of elevated nitrogen (N) loading into estuarine ecosystems. This study investigates the response to over 40 years of fertilization of nitrogen removal processes in the sediments of the Great Sippewissett Marsh in Falmouth, MA. Sediment slurries were incubated (1.5 hr) with trace amounts (< 10% of ambient concentration) of 15NH4+ + 14NO3- or 15NO3- + 14NH4+. An additional parallel incubation with 15NH4+ + 14NO3- and 1 mM of allylthiourea (ATU) was included to measure rates of anaerobic ammonia oxidation (anammox). Well-homogenized slurries filled about 10% of the volume in the gas-tight incubation vials, and the rest of the volume was replaced with an O2/He (20%/80%) mixture. The production of 29N2, 44N2O and 45N2O were determined using isotope ratio mass spectrometry. The rate of total N2O production in fertilized sediments (0.89 nmol hr-1 g-1 wet weight) was 30-fold higher than in unfertilized sediments. The ratio of N2O to N2 production was also significantly higher in fertilized sediments (2.9%) than in unfertilized sediments (1.2%). This highlights the disproportionally large effect of long-term fertilization on N2O production in salt marsh sediments. The reduced oxygen level and higher ammonium concentrations in situ probably contributed to the significant rise in N2O production as a result of long-term fertilization. When detected, anammox and coupled nitrification-denitrification accounted for 10% and 14% of the total N2 production in fertilized sediments (30.5 nmol hr-1 g-1 wet weight), respectively, whereas neither was detected in unfertilized sediments. Thus these experiments indicate that N loading has important effects on multiple N cycle processes that result in N loss and N2O production.

  6. Response of salt marshes to oiling from the Deepwater Horizon spill: Implications for plant growth, soil surface-erosion, and shoreline stability.

    PubMed

    Lin, Qianxin; Mendelssohn, Irving A; Graham, Sean A; Hou, Aixin; Fleeger, John W; Deis, Donald R

    2016-07-01

    We investigated the initial impacts and post spill recovery of salt marshes over a 3.5-year period along northern Barataria Bay, LA, USA exposed to varying degrees of Deepwater Horizon oiling to determine the effects on shoreline-stabilizing vegetation and soil processes. In moderately oiled marshes, surface soil total petroleum hydrocarbon concentrations were ~70mgg(-1) nine months after the spill. Though initial impacts of moderate oiling were evident, Spartina alterniflora and Juncus roemerianus aboveground biomass and total live belowground biomass were equivalent to reference marshes within 24-30months post spill. In contrast, heavily oiled marsh plants did not fully recover from oiling with surface soil total petroleum hydrocarbon concentrations that exceeded 500mgg(-1) nine months after oiling. Initially, heavy oiling resulted in near complete plant mortality, and subsequent recovery of live aboveground biomass was only 50% of reference marshes 42months after the spill. Heavy oiling also changed the vegetation structure of shoreline marshes from a mixed Spartina-Juncus community to predominantly Spartina; live Spartina aboveground biomass recovered within 2-3years, however, Juncus showed no recovery. In addition, live belowground biomass (0-12cm) in heavily oiled marshes was reduced by 76% three and a half years after the spill. Detrimental effects of heavy oiling on marsh plants also corresponded with significantly lower soil shear strength, lower sedimentation rates, and higher vertical soil-surface erosion rates, thus potentially affecting shoreline salt marsh stability. PMID:27016685

  7. Trematodes in snails near raccoon latrines suggest a final host role for this mammal in California Salt Marshes

    USGS Publications Warehouse

    Lafferty, K.D.; Dunham, E.J.

    2005-01-01

    Of the 18 trematode species that use the horn snail, Cerithidea californica, as a first intermediate host, 6 have the potential to use raccoons as a final host. The presence of raccoon latrines in Carpinteria Salt Marsh, California, allowed us to investigate associations between raccoons and trematodes in snails. Two trematode species, Probolocoryphe uca and Stictodora hancocki, occurred at higher prevalences in snails near raccoon latrines than in snails away from latrines, suggesting that raccoons may serve as final hosts for these species. Fecal remains indicated that raccoons fed on shore crabs, the second intermediate host for P. uca, and fish, the second intermediate host for S. hancocki. The increase in raccoon populations in the suburban areas surrounding west coast salt marshes could increase their importance as final hosts for trematodes in this system. ?? American Society of Parasitologists 2005.

  8. Organochlorine pesticide and polychlorinated biphenyl residues in selected fauna from a New Jersey salt marsh--1967 vs. 1973

    USGS Publications Warehouse

    Klaas, E.E.; Belisle, A.A.

    1977-01-01

    More than a half million pounds of DDT were applied to control mosquitoes in salt marsh estuaries of Cape May County, New Jersey, from 1946 to 1966. The use of DDT was discontinued in the County after 1966. In 1967, mean concentrations of DDT and metabolites ranged from 0.63 to 9.05 ppm in aquatic fauna, but by 1973 mean residue levels had decreased 84 to 99 percent among nine species. DDE was still present at reduced levels in nearly all samples in 1973, but other DDT isomers had mostly disappeared. Dieldrin was detected only in clapper rails, and residue levels decreased during the period. Mean concentrations of PCB's increased in the clapper rail, remained the same in the fiddler crab and mud snail, and decreased in the sheepshead minnow, mummichog, striped killifish, and salt marsh snail. Small amounts of mirex, toxaphene, cis-chlordane (and/or trans-nonachlor), oxychlordane, and HCB were detected in a few specimens.

  9. A comparison between conventional and AMS [sup 14]C dates on basal salt marsh peats from coastal Maine. [Accelerator Mass Spectroscopy

    SciTech Connect

    Gehrels, R.W.; Belknap, D.F. . Dept. of Geological Sciences)

    1992-01-01

    This study reports AMS dates from four Maine salt marshes: Webbannet Marsh (Wells), Morse and Sprague River marshes (Phippsburg), and Sanborn Cove marsh (Machiasport). The AMS dates are compared with conventional dates on bulk samples obtained from either the same cores or from other cores at comparable depths. Four AMS dates from the Webhannet and Sanborn Cove marshes were considerably older than their conventional counterparts, by as much as 1,000 years. Three causes for this age discrepancy are suggested. First, under slow rates of marsh accretion, peats remain within the root zone of modern plants for a relatively long period, causing a continued input of younger carbon. Intruded roots are undetectable in the highly macerated, 4,000--5,000 C-14 year old peats. Another source of contamination is the percolation of mobile humic acids along the impermeable Pleistocene substrate. Finally, a date on a bulk peat of 10 cm vertical extent represents an average age for a portion of peat that spans a time interval possibly of several centuries. The age difference between the bulk date and the AMS date from the base of the peat increases with decreasing rates of marsh accretion. The forested steep slopes of the upland surrounding the marsh seem a likely source of old carbon that can easily be washed onto the marsh surface. The slow rate of late-Holocene sea-level rise in Maine, as well as the geologic and hydrologic setting of the salt marshes, make conventional C-14 dating of salt marsh peats in Maine a problematic affair. This study implies that AMS dates may be needed to verify Holocene sea-level curves from other coastal areas that have hitherto been based solely on conventional C-14 peat dates.

  10. The Distribution of Talitrid Amphipods (Crustacea) on a Salt Marsh in Southern Tasmania, in relation to Vegetation and Substratum

    NASA Astrophysics Data System (ADS)

    Richardson, A. M. M.; Mulcahy, M. E.

    1996-12-01

    Supralittoral and terrestrial talitrid amphipods were collected from a salt marsh in Southern Tasmania by pitfall trapping along transects from the mid-tidal level to above the high-tide mark, and by hand collecting from sites chosen to represent the full range from salt marsh to terrestrial vegetation. At each site, the cover of all major plant species was recorded, and soil samples were collected from which soil moisture, organic content and salinity were measured. Eight talitrid species from four ecological groups were collected; one palustral species, one beachflea, three coastal landhoppers and three eastern forest landhoppers. There was substantial overlap in the distributions of these groups. The undescribed beachflea had the widest distribution, from the wettest, most saline sites to the Schoenus nitenstussock grassland at the extreme high-tide mark. The palustral species, Eorchestia palustris, overlapped substantially with the beachflea, but was found within a narrower band of salinities (though not in the most saline sites) and in more poorly-drained sites than the beachflea. Coastal landhoppers, Austrotroides maritimus, Keratroides rexand an undescribed species of Tasmanorchestia, were found mainly in the S. nitenstussock grassland, where they overlapped with forest landhoppers, Keratroides vulgaris, Mysticotalitrus tasmaniaeand M. cryptus, which were found mainly in non-saltmarsh terrestrial sites, well above the high-tide mark. These distributions are discussed in terms of the likelihood that salt marshes provided the route by which talitrid amphipods colonized land. There is no reason from these data to reject salt marshes as the route to land, and it is suggested that they are a more likely route than via rocky or sandy shores.

  11. High Tolerance to Salinity and Herbivory Stresses May Explain the Expansion of Ipomoea Cairica to Salt Marshes

    PubMed Central

    Liu, Gang; Huang, Qiao-Qiao; Lin, Zhen-Guang; Huang, Fang-Fang; Liao, Hui-Xuan; Peng, Shao-Lin

    2012-01-01

    Background Invasive plants are often confronted with heterogeneous environments and various stress factors during their secondary phase of invasion into more stressful habitats. A high tolerance to stress factors may allow exotics to successfully invade stressful environments. Ipomoea cairica, a vigorous invader in South China, has recently been expanding into salt marshes. Methodology/Principal Findings To examine why this liana species is able to invade a stressful saline environment, we utilized I. cairica and 3 non-invasive species for a greenhouse experiment. The plants were subjected to three levels of salinity (i.e., watered with 0, 4 and 8 g L−1 NaCl solutions) and simulated herbivory (0, 25 and 50% of the leaf area excised) treatments. The relative growth rate (RGR) of I. cairica was significantly higher than the RGR of non-invasive species under both stress treatments. The growth performance of I. cairica was not significantly affected by either stress factor, while that of the non-invasive species was significantly inhibited. The leaf condensed tannin content was generally lower in I. cairica than in the non-invasive I. triloba and Paederia foetida. Ipomoea cairica exhibited a relatively low resistance to herbivory, however, its tolerance to stress factors was significantly higher than either of the non-invasive species. Conclusions/Significance This is the first study examining the expansion of I. cairica to salt marshes in its introduced range. Our results suggest that the high tolerance of I. cairica to key stress factors (e.g., salinity and herbivory) contributes to its invasion into salt marshes. For I. cairica, a trade-off in resource reallocation may allow increased resources to be allocated to tolerance and growth. This may contribute to a secondary invasion into stressful habitats. Finally, we suggest that I. cairica could spread further and successfully occupy salt marshes, and countermeasures based on herbivory could be ineffective for

  12. Transport and distribution of bacteria and diatoms in the aqueous surface micro-layer of a salt marsh

    USGS Publications Warehouse

    Harvey, Ronald W.; Lion, Leonard W.; Young, Lily Y.

    1983-01-01

    The effects of tide and wind upon the distribution and transport of bacteria and diatoms in the aqueous surface microlayers of a Massachusetts and San Francisco Bay salt marsh were examined. The compression of the surface films by both tide and wind resulted in significant enrichments of bacterioneuston. At the San Francisco Bay site, significant numbers of diatoms were transported within the microlayer over a tidal cycle.

  13. Low persistence of Bacillus thuringiensis serovar israelensis spores in four mosquito biotopes of a salt marsh in southern France.

    PubMed

    Hajaij, Myriam; Carron, Alexandre; Deleuze, Julien; Gaven, Bruno; Setier-Rio, Marie-Laure; Vigo, Gerard; Thiéry, Isabelle; Nielsen-LeRoux, Christina; Lagneau, Christophe

    2005-11-01

    We studied the persistence of Bacillus thuringiensis serovar israelensis (Bti) in a typical breeding site of the mosquito Ochlerotatus caspius in a particularly sensitive salt marsh ecosystem following two Bti-based larvicidal applications (Vectobac 12AS, 1.95 L/ha). The treated area was composed of four larval biotopes that differed in terms of the most representative plant species (Sarcocornia fruticosa, Bolboschoenus maritimus, Phragmites australis, and Juncus maritimus) and the physical and chemical characteristics of the soil. We sampled water, soil, and plants at various times before and after the applications (from spring to autumn, 2001) and quantified the spores of B. thuringiensis (Bt) and Bacillus species. The B. cereus group accounted for between 0% and 20% of all Bacillus spp. before application depending on the larval biotope. No Bti were found before application. The variation in the quantity of bacilli during the mosquito breeding season depended more on the larval biotope than on the season or the larvicidal application. More bacilli were found in soil (10(4)-10(6) spores/g) than on plant samples (10(2)-10(4) spores/g). The abundance in water (10(5) to 10(7) spores/L) appeared to be correlated to the water level of the breeding site. The number of Bti spores increased just after application, after declining; no spores were detected in soil or water 3 months after application. However, low numbers of Bti spores were present on foliage from three of the four studied plant strata. In conclusion, the larvicidal application has very little impact on Bacillus spp. flora after one breeding season (two applications). PMID:16328650

  14. Communities of ammonia oxidizers at different stages of Spartina alterniflora invasion in salt marshes of Yangtze River estuary.

    PubMed

    Xia, Fei; Zeleke, Jemaneh; Sheng, Qiang; Wu, Ji-Hua; Quan, Zhe-Xue

    2015-05-01

    Spartina alterniflora, an aggressive invasive plant species at the estuarine wetlands of China's coasts, has become a major threat to the natural ecosystems. To understand its potential influence on nitrification processes, the community structures and abundance of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were investigated using 454-pyrosequencing and quantitative real-time PCR (qPCR) in S. alterniflora invading salt marsh sediments at the Yangtze River estuary in Chongming island, Shanghai, China. Copy numbers of archaeal and bacterial ammonia monooxygenase subunit A (amoA) genes did not show accordant shifts with S. alterniflora invasion in the two sampling sites. However, the copy numbers of archaeal amoA gene were higher in summer than in spring. Phylogenetic analysis indicated that more than 90% of the archaeal and 92% of the bacterial amoA gene sequences were closely related to marine group I.1a and the clusters 13 and 15 in Nitrosospira lineage, respectively. The effect of different seasons (spring and summer) was important for the abundance variation of AOA, while different stages of S. alterniflora invasion did not show significant effect for both AOA and AOB. Variation of AOA community was significantly related to total carbon (TC) and sulfate concentration (P < 0.05), whereas the AOB community was significantly related to sulfate concentration, total nitrogen (TN), TC and pH (P < 0.05). In conclusion, the abundance and diversity of ammonia oxidizing microbial communities were not strongly affected by S. alterniflora invasion. PMID:25935302

  15. Salt tolerance underlies the cryptic invasion of North American salt marshes by an introduced haplotype of the common reed Phragmites australis (Poaceae)

    USGS Publications Warehouse

    Vasquez, E.A.; Glenn, E.P.; Brown, J.J.; Guntenspergen, G.R.; Nelson, S.G.

    2005-01-01

    A distinct, non-native haplotype of the common reed Phragmites australis has become invasive in Atlantic coastal Spartina marshes. We compared the salt tolerance and other growth characteristics of the invasive M haplotype with 2 native haplotypes (F and AC) in greenhouse experiments. The M haplotype retained 50% of its growth potential up to 0.4 M NaCl, whereas the F and AC haplotypes did not grow above 0.1 M NaCl. The M haplotype produced more shoots per gram of rhizome tissue and had higher relative growth rates than the native haplotypes on both freshwater and saline water treatments. The M haplotype also differed from the native haplotypes in shoot water content and the biometrics of shoots and rhizomes. The results offer an explanation for how the M haplotype is able to spread in coastal salt marshes and support the conclusion of DNA analyses that the M haplotype is a distinct ecotype of P. australis.

  16. Tidal salt marsh sediment in California, USA: part 3. Current and historic toxicity potential of contaminants and their bioaccumulation.

    PubMed

    Hwang, Hyun-Min; Green, Peter G; Young, Thomas M

    2008-05-01

    To assess potential health risks to benthic organisms from exposure to toxic contaminants, sediment chemistry data from five salt marshes along the coast of California were compared with threshold effects levels (TELs) and probable effects levels (PELs). As an integrated estimate of toxicity potential of multiple contaminants, mean PEL quotients (mPELQs) were used to categorize sampling stations into three groups: high (>0.5), medium (0.1-0.5) and low (<0.1). In all sediments from Stege Marsh located in San Francisco Bay, at least one contaminant exceeded PELs by up to 18-fold and mPELQs were higher than 0.7. Mean PELQs in two core sediments from eastern Stege Marsh ranged from 0.7 to 2.1, indicating that benthic organisms in Stege Marsh may have been adversely affected for several decades. To investigate bioavailability and bioaccumulation of contaminants in sediments, longjaw mudsuckers (Gillichthys mirabilis) were transplanted to six Stege Marsh stations for 60 days. Body burdens of organic contaminants clearly showed that they were readily available for benthic organisms. Measured concentrations of organic contaminants in mudsuckers were similar to estimated levels computed using a theoretical bioaccumulation potential model. Levels of PCBs and arsenic in mudsuckers were higher than screening values set as guidelines for the protection of humans and levels of PCBs and DDTs were higher than criteria for wildlife. The results of this study indicate that the levels of contaminants in Stege Marsh sediments may not fully support the well-being of benthic organisms and also may provoke adverse effects on fish-eating animals and humans through trophic transfer. PMID:18316112

  17. Stocks and sources of carbon buried in the salt marshes and seagrass beds of Patos Lagoon Estuary, Southern Brazil

    NASA Astrophysics Data System (ADS)

    Patterson, Elizabeth; Johnson, Beverly; Dostie, Philip; Copertino, Margareth

    2016-04-01

    This project investigates carbon stocks in salt marshes and seagrass beds in the Patos Lagoon estuary, the largest choked lagoon in the world, located in Southern Brazil. The study was conducted in the mesohaline region, at three shallow shoals. At each shoal, three sediment cores (50 cm deep) and plant biomass samples (above and belowground) were collected along a transect line, spanning from the marsh to seagrass beds (total = 9 sediment cores). The 50cm cores were subsampled and analyzed for organic carbon (C) and nitrogen (N) content, C/N ratios, and the isotope ratios of 13C/12C, and 15N/14N. The organic carbon content of these sediments ranged between 10% (in surface sediments) and 1% (deeper in the core), suggesting that both the salt marshes and seagrass beds in this region are sequestering carbon. Early results indicate that cores taken in marsh dominated by C3 plants (Scirpus maritimus) tended to be the most depleted in 13C with δ13C values around -25‰. Cores taken in marsh dominated by C4 plants (Spartina alterniflora, Spartina densiflora), seagrass beds (Ruppia maritima) , and non vegetated areas were generally isotopically heavier with δ13C values ranging -20‰ to -15‰, indicating a mix of organic sources in the sediments. The δ15N values and C/N ratios both varied with most values falling in a range of 2-8‰ and 7-20 respectively. Analysis of the δ 34S isotope composition of the sediments is currently underway and may provide better information on the relative contributions of macro and micro algae in the sediments. The present data will reveal the carbon stock size, as well as the types and history of organic matter deposition in Patos Lagoon estuary.

  18. Thermophilic bacteria in Moroccan hot springs, salt marshes and desert soils

    PubMed Central

    Aanniz, Tarik; Ouadghiri, Mouna; Melloul, Marouane; Swings, Jean; Elfahime, Elmostafa; Ibijbijen, Jamal; Ismaili, Mohamed; Amar, Mohamed

    2015-01-01

    The diversity of thermophilic bacteria was investigated in four hot springs, three salt marshes and 12 desert sites in Morocco. Two hundred and forty (240) thermophilic bacteria were recovered, identified and characterized. All isolates were Gram positive, rod-shaped, spore forming and halotolerant. Based on BOXA1R-PCR and 16S rRNA gene sequencing, the recovered isolates were dominated by the genus Bacillus (97.5%) represented by B. licheniformis (119), B. aerius (44), B. sonorensis (33), B. subtilis (subsp. spizizenii (2) and subsp. inaquosurum (6)), B. amyloliquefaciens (subsp. amyloliquefaciens (4) and subsp. plantarum (4)), B. tequilensis (3), B. pumilus (3) and Bacillus sp. (19). Only six isolates (2.5%) belonged to the genus Aeribacillus represented by A. pallidus (4) and Aeribacillus sp. (2). In this study, B. aerius and B. tequilensis are described for the first time as thermophilic bacteria. Moreover, 71.25%, 50.41% and 5.41% of total strains exhibited high amylolytic, proteolytic or cellulolytic activity respectively. PMID:26273259

  19. Carbon metabolism in model microbial systems from a temperate salt marsh.

    PubMed

    Fallon, R D; Pfaender, F K

    1976-06-01

    The metabolism of a saltwater leachate of 14C-labeled Spartina alterniflora was examined in laboratory systems using mixed, salt marsh microbial communities and, by addition of appropriate antibiotics, communities with bacteria or eukaryotes inhibited. Label uptake was more rapid in the systems with bacteria alone and with the mixed microbial community than with fungi alone. Mineralization of the added label was more extensive in the mixed and bacterial systems, whereas the fungi appear more efficient at converting the label into particulate biomass. Particulate biomass production efficiencies ranged from a high of 0.82 for the fungal system to 0.21 in the mixed community, with the bacterial system giving an intermediate value of 0.54. The presence of protozoa and microcrustaceans in the mixed system appears to account for an increase in the mineralization of the label assimilated. Additional experiments with whole labeled Spartina, a leachate from Spartina, and Spartina after leaching revealed that the seawater-soluble portions of the plants were attacked most rapidly by the microbial community. PMID:938043

  20. Carbon metabolism in model microbial systems from a temperate salt marsh.

    PubMed Central

    Fallon, R D; Pfaender, F K

    1976-01-01

    The metabolism of a saltwater leachate of 14C-labeled Spartina alterniflora was examined in laboratory systems using mixed, salt marsh microbial communities and, by addition of appropriate antibiotics, communities with bacteria or eukaryotes inhibited. Label uptake was more rapid in the systems with bacteria alone and with the mixed microbial community than with fungi alone. Mineralization of the added label was more extensive in the mixed and bacterial systems, whereas the fungi appear more efficient at converting the label into particulate biomass. Particulate biomass production efficiencies ranged from a high of 0.82 for the fungal system to 0.21 in the mixed community, with the bacterial system giving an intermediate value of 0.54. The presence of protozoa and microcrustaceans in the mixed system appears to account for an increase in the mineralization of the label assimilated. Additional experiments with whole labeled Spartina, a leachate from Spartina, and Spartina after leaching revealed that the seawater-soluble portions of the plants were attacked most rapidly by the microbial community. PMID:938043

  1. Phylogenetic diversity of Archaea in sediment samples from a coastal salt marsh.

    PubMed Central

    Munson, M A; Nedwell, D B; Embley, T M

    1997-01-01

    The Archaea present in salt marsh sediment samples from a tidal creek and from an adjacent area of vegetative marshland, both of which showed active methanogenesis and sulfate reduction, were sampled by using 16S rRNA gene libraries created with Archaea-specific primers. None of the sequences were the same as reference sequences from cultured taxa, although some were closely related to sequences from methanogens previously isolated from marine sediments. A wide range of Euryarchaeota sequences were recovered, but no sequences from Methanococcus, Methanobacterium, or the Crenarchaeota were recovered. Clusters of closely related sequences were common and generally contained sequences from both sites, suggesting that some related organisms were present in both samples. Recovery of sequences closely related to those of methanogens such as Methanococcoides and Methanolobus, which can use substrates other than hydrogen, provides support for published hypotheses that such methanogens are probably important in sulfate-rich sediments and identifies some likely candidates. Sequences closely related to those of methanogens such as Methanoculleus and Methanogenium, which are capable of using hydrogen, were also discovered, in agreement with previous inhibitor and process measurements suggesting that these taxa are present at low levels of activity. More surprisingly, we recovered a variety of sequences closely related to those from different halophilic Archaea and a cluster of divergent sequences specifically related to the marine group II archaeal sequences recently shown by PCR and probing to have a cosmopolitan distribution in marine samples. PMID:9406392

  2. Influence of different salt marsh plants on hydrocarbon degrading microorganisms abundance throughout a phenological cycle.

    PubMed

    Ribeiro, Hugo; Almeida, C Marisa R; Mucha, Ana Paula; Bordalo, Adriano A

    2013-01-01

    The influence of Juncus maritimus, Phragmites australis, and Triglochin striata on hydrocarbon degrading microorganisms (HD) in Lima River estuary (NW Portugal) was investigated through a year-long plant life cycle. Sediments un-colonized and colonized (rhizosediments) by those salt marsh plants were sampled for HD, total cell counts (TCC), and total petroleum hydrocarbons (TPHs) assessment. Generally, TCC seemed to be markedly thriving by the presence of roots, but without significant (p > 0.05) differences among rhizosediments. Nevertheless, plants seemed to have a distinct influence on HD abundance, particularly during the flowering season, with higher HD abundance in the rhizosediments of the fibrous roots plants (J. maritimus < P. australis < T. striata). Our data suggest that different plants have distinct influence on the dynamics of HD populations within its own rhizosphere, particularly during the flowering season, suggesting a period of higher rhizoremediation activity. Additionally, during the vegetative period, plants with fibrous and dense root system tend to retain hydrocarbons around their belowground tissues more efficiently than plants with adventitious root system. Overall results indicate that fibrous root plants have a higher potential to promote hydrocarbons degradation, and that seasonality should be taken into account when designing long-term rhizoremediation strategies in estuarine areas. PMID:23819270

  3. Seed storage conditions change the germination pattern of clonal growth plants in Mediterranean salt marshes.

    PubMed

    Espinar, José L; García, Luis V; Clemente, Luis

    2005-07-01

    The effect of salinity level and extended exposure to different salinity and flooding conditions on germination patterns of three salt-marsh clonal growth plants (Juncus subulatus, Scirpus litoralis, and S. maritimus) was studied. Seed exposure to extended flooding and saline conditions significantly affected the outcome of the germination process in a different, though predictable, way for each species, after favorable conditions for germination were restored. Tolerance of the germination process was related to the average salinity level measured during the growth/germination season at sites where established individuals of each species dominated the species cover. No relationship was found between salinity tolerance of the germination process and seed response to extended exposure to flooding and salinity conditions. The salinity response was significantly related to the conditions prevailing in the habitats of the respective species during the unfavorable (nongrowth/nongermination) season. Our results indicate that changes in salinity and hydrology while seeds are dormant affect the outcome of the seed-bank response, even when conditions at germination are identical. Because these environmental-history-dependent responses differentially affect seed germination, seedling density, and probably sexual recruitment in the studied and related species, these influences should be considered for wetland restoration and management. PMID:21646131

  4. The Relationship of Salt Marsh Vegetation Lateral Obstruction to Vegetation Morphology

    NASA Astrophysics Data System (ADS)

    Lemein, T.; Cox, D. T.; Albert, D.

    2013-12-01

    Vegetation in salt marshes attenuates wave energy while influencing sediment accretion and turbulence in the water column. Modeling the interaction of waves and vegetation has been typically approached through an empirical coefficient of drag variable that is calibrated for a given set of biologic conditions dependent upon stem density and diameter. This method oversimplifies the complexity of vegetation morphology while also requiring assumptions to be made about the vegetation itself (uniform stem diameters for all stems) and leads to large uncertainty in the drag coefficient. As an alternative to the uniform vegetation model, we focus on the variation of the lateral obstruction of vegetation. This measure of cover in the vertical plane over a given horizontal distance is useful for presenting and quantifying complex vegetation morphology from live, in situ, vegetation. We compare the lateral obstruction of two common Pacific Northwest estuarine species, threesquare bulrush (Schoenoplectus pungens), and Lyngbye's sedge (Carex lyngbyei), to their in situ morphologic characteristics (density, height, diameter, aboveground biomass) over varying horizontal distances. From this, the amount of lateral obstruction is used to determine an estimate of the morphologic characteristics of the species in other environments and vice versa, therefore providing a means of making more accurate comparisons between and among species. We anticipate that this method will improve the calibration of the coefficient of drag variable in wave attenuation equations by incorporating the vertical variation of plant density.

  5. Microscale sulfur cycling in the phototrophic pink berry consortia of the Sippewissett Salt Marsh

    PubMed Central

    Wilbanks, Elizabeth G; Jaekel, Ulrike; Salman, Verena; Humphrey, Parris T; Eisen, Jonathan A; Facciotti, Marc T; Buckley, Daniel H; Zinder, Stephen H; Druschel, Gregory K; Fike, David A; Orphan, Victoria J

    2014-01-01

    Microbial metabolism is the engine that drives global biogeochemical cycles, yet many key transformations are carried out by microbial consortia over short spatiotemporal scales that elude detection by traditional analytical approaches. We investigate syntrophic sulfur cycling in the ‘pink berry’ consortia of the Sippewissett Salt Marsh through an integrative study at the microbial scale. The pink berries are macroscopic, photosynthetic microbial aggregates composed primarily of two closely associated species: sulfide-oxidizing purple sulfur bacteria (PB-PSB1) and sulfate-reducing bacteria (PB-SRB1). Using metagenomic sequencing and 34S-enriched sulfate stable isotope probing coupled with nanoSIMS, we demonstrate interspecies transfer of reduced sulfur metabolites from PB-SRB1 to PB-PSB1. The pink berries catalyse net sulfide oxidation and maintain internal sulfide concentrations of 0–500 μm. Sulfide within the berries, captured on silver wires and analysed using secondary ion mass spectrometer, increased in abundance towards the berry interior, while δ34S-sulfide decreased from 6‰ to −31‰ from the exterior to interior of the berry. These values correspond to sulfate–sulfide isotopic fractionations (15–53‰) consistent with either sulfate reduction or a mixture of reductive and oxidative metabolisms. Together this combined metagenomic and high-resolution isotopic analysis demonstrates active sulfur cycling at the microscale within well-structured macroscopic consortia consisting of sulfide-oxidizing anoxygenic phototrophs and sulfate-reducing bacteria. PMID:24428801

  6. Distribution of Root-Associated Bacterial Communities Along a Salt-Marsh Primary Succession

    PubMed Central

    Wang, Miao; Yang, Pu; Falcão Salles, Joana

    2016-01-01

    Proper quantification of the relative influence of soil and plant host on the root-associated microbiome can only be achieved by studying its distribution along an environmental gradient. Here, we used an undisturbed salt marsh chronosequence to study the bacterial communities associated with the soil, rhizosphere and the root endopshere of Limonium vulgare using 454-pyrosequencing. We hypothesize that the selective force exerted by plants rather than soil would regulate the dynamics of the root-associated bacterial assembly along the chronosequence. Our results showed that the soil and rhizosphere bacterial communities were phylogenetically more diverse than those in the endosphere. Moreover, the diversity of the rhizosphere microbiome followed the increased complexity of the abiotic and biotic factors during succession while remaining constant in the other microbiomes. Multivariate analyses showed that the rhizosphere and soil-associated communities clustered by successional stages, whereas the endosphere communities were dispersed. Interestingly, the endosphere microbiome showed higher turnover, while the bulk and rhizosphere soil microbiomes became more similar at the end of the succession. Overall, we showed that soil characteristics exerted an overriding influence on the rhizosphere microbiome, although plant effect led to a clear diversity pattern along the succession. Conversely, the endosphere microbiome was barely affected by any of the environmental measurements and very distinct from other communities. PMID:26779222

  7. Mercury in sediments and vegetation in a moderately contaminated salt marsh (Tagus Estuary, Portugal).

    PubMed

    Canário, João; Vale, Carlos; Poissant, Laurier; Nogueira, Marta; Pilote, Martin; Branco, Vasco

    2010-01-01

    Depth variations of total mercury (Hg) and methylmercury (MeHg) concentrations were studied in cores from non-colonized sediments, sediments colonized by Halimione portulacoides, Sarcocorniafruticosa and Spartina maritima and belowground biomass, in a moderately contaminated salt marsh (Tagus Estuary, Portugal). Concentrations in belowground biomass exceeded up to 3 (Hg) and 15 (MeHg) times the levels in sediments, and up to 198 (Hg) and 308 (MeHg) times those found in aboveground parts. Methylmercury in colonized sediments reached 3% of the total Hg, 50 times above the maximum values found in non-colonized sediments. The absence of correlations between total Hg concentrations in sediments and the corresponding MeHg levels suggested that methylation was only dependent on the environmental and microbiological factors. The analysis of belowground biomass at high-depth resolution (2 cm) provided evidence that Hg and MeHg were actively absorbed from sediments, with higher enrichment factors at layers where higher microbial activity was probably occurring. The results obtained in this study indicated that the biotransformation of Hg to the toxic MeHg could increase the toxicity of plant-colonized sediments. PMID:21179951

  8. Magnetic properties of salt-marsh soils contaminated by iron industry emissions (southeast France)

    NASA Astrophysics Data System (ADS)

    Lecoanet, Hélène; Lévêque, François; Ambrosi, Jean-Paul

    2001-09-01

    Detailed magnetic properties of salt-marsh soils exposed to intense atmospheric deposition of fly ashes from the iron industry (southeast France) are reported. An enhancement in the concentration of magnetic particles in topsoil through this area is observed. Low values of frequency-dependent susceptibility ( χFD) are characteristic of coarse multidomain (MD) grains and were observed in surface samples. Concentration of ferrimagnetic minerals in different soil horizons is linked to pollution sources and the prevailing wind direction. The anhysteretic remanent magnetisation/saturation anhysteretic remanent magnetisation (ARM 40 mT/SARM) ratio versus isothermal remanent magnetisation/saturation isothermal remanent magnetisation (IRM -100 mT/SIRM) ratio and the IRM -20 mT/SIRM ratio versus IRM -200 mT/SIRM ratio can differentiate two different contamination emission sources. Magnetic methods used reflect not only the concentration of ferrimagnetic minerals but also their grain size, thus enabling discrimination of metallurgical dusts and fine pedogenic particles created in situ. Our results suggest that pollution is not the only source and that pedogenesis also plays a role.

  9. Can salt marsh plants influence levels and distribution of DDTs in estuarine areas?

    NASA Astrophysics Data System (ADS)

    Carvalho, Pedro N.; Rodrigues, Pedro Nuno R.; Evangelista, Rafael; Basto, M. Clara P.; Vasconcelos, M. Teresa S. D.

    2011-07-01

    Sediments are depositories of toxic substances such as organochlorine pesticides and there is a global need for their removal in contaminated environments. Studies that combine contaminated sediments and phytoremediation are relatively recent and their number has been increasing. This work aimed to investigate whether salt marsh plants (sea club-rush Scirpus maritimus, sea rush Juncus maritimus and sea purslane Halimione portulacoides) can favor DDT and metabolites remediation in estuarine environment. For this purpose the levels of DDT, DDE and DDD were compared in vegetated and non-vegetated sediments from an estuary in the North of Portugal ( in-situ study) and from another in the South of Portugal ( ex-situ study). Results obtained both in the in-situ study, involving S. maritimus and J. maritimus, and in the ex-situ study, involving H. portulacoides, indicated that these plants did not have a significant role in DDTs removal and/or degradation. Therefore, it seems that the tested plants cannot influence levels and distribution of DDTs in estuarine areas.

  10. Determining meteorological drivers of salt marsh mosquito peaks in tropical northern Australia.

    PubMed

    Jacups, Susan P; Carter, Jane; Kurucz, Nina; McDonnell, Joseph; Whelan, Peter I

    2015-12-01

    In northern Australia the northern salt marsh mosquito Aedes vigilax is a vector of Ross River virus and is an appreciable pest. A coastal wetland adjacent to Darwin's residential suburbs offers a favorable habitat for Ae. vigilax, and despite vigilant mosquito control efforts, peaks of Ae. vigilax occur in excess of 500/trap/night some months. To improve mosquito control for disease and nuisance biting to nearby residential areas, we sought to investigate meteorological drivers associated with these Ae. vigilax peaks. We fitted a cross-sectional logistic regression model to weekly counts of female Ae. vigilax mosquitoes collected between July, 1998 and June, 2009 against variables, tide, rainfall, month, year, and larval control. Aedes vigilax peaks were associated with rainfall during the months September to November compared with January, when adjusted for larval control and tide. To maximize mosquito control efficiency, larval control should continue to be implemented after high tides and with increased emphasis on extensive larval hatches triggered by rainfall between September and November each year. This study reiterates the importance of monitoring and evaluating service delivery programs. Using statistical modelling, service providers can obtain solutions to operational problems using routinely collected data. These methods may be applicable in mosquito surveillance or control programs in other areas. PMID:26611962

  11. The effect of multiple stressors on salt marsh end-of-season biomass

    USGS Publications Warehouse

    Visser, J.M.; Sasser, C.E.; Cade, B.S.

    2006-01-01

    It is becoming more apparent that commonly used statistical methods (e.g., analysis of variance and regression) are not the best methods for estimating limiting relationships or stressor effects. A major challenge of estimating the effects associated with a measured subset of limiting factors is to account for the effects of unmeasured factors in an ecologically realistic matter. We used quantile regression to elucidate multiple stressor effects on end-of-season biomass data from two salt marsh sites in coastal Louisiana collected for 18 yr. Stressor effects evaluated based on available data were flooding, salinity, air temperature, cloud cover, precipitation deficit, grazing by muskrat, and surface water nitrogen and phosphorus. Precipitation deficit combined with surface water nitrogen provided the best two-parameter model to explain variation in the peak biomass with different slopes and intercepts for the two study sites. Precipitation deficit, cloud cover, and temperature were significantly correlated with each other. Surface water nitrogen was significantly correlated with surface water phosphorus and muskrat density. The site with the larger duration of flooding showed reduced peak biomass, when cloud cover and surface water nitrogen were optimal. Variation in the relatively low salinity occurring in our study area did not explain any of the variation in Spartina alterniflora biomass. ?? 2006 Estuarine Research Federation.

  12. Thermophilic bacteria in Moroccan hot springs, salt marshes and desert soils.

    PubMed

    Aanniz, Tarik; Ouadghiri, Mouna; Melloul, Marouane; Swings, Jean; Elfahime, Elmostafa; Ibijbijen, Jamal; Ismaili, Mohamed; Amar, Mohamed

    2015-06-01

    The diversity of thermophilic bacteria was investigated in four hot springs, three salt marshes and 12 desert sites in Morocco. Two hundred and forty (240) thermophilic bacteria were recovered, identified and characterized. All isolates were Gram positive, rod-shaped, spore forming and halotolerant. Based on BOXA1R-PCR and 16S rRNA gene sequencing, the recovered isolates were dominated by the genus Bacillus (97.5%) represented by B. licheniformis (119), B. aerius (44), B. sonorensis (33), B. subtilis (subsp. spizizenii (2) and subsp. inaquosurum (6)), B. amyloliquefaciens (subsp. amyloliquefaciens (4) and subsp. plantarum (4)), B. tequilensis (3), B. pumilus (3) and Bacillus sp. (19). Only six isolates (2.5%) belonged to the genus Aeribacillus represented by A. pallidus (4) and Aeribacillus sp. (2). In this study, B. aerius and B. tequilensis are described for the first time as thermophilic bacteria. Moreover, 71.25%, 50.41% and 5.41% of total strains exhibited high amylolytic, proteolytic or cellulolytic activity respectively. PMID:26273259

  13. Methane production and simultaneous sulphate reduction in anoxic, salt marsh sediments

    USGS Publications Warehouse

    Oremland, R.S.; Marsh, L.M.; Polcin, S.

    1982-01-01

    It has been generally believed that sulphate reduction precludes methane generation during diagenesis of anoxic sediments1,2. Because most biogenic methane formed in nature is thought to derive either from acetate cleavage or by hydrogen reduction of carbon dioxide3-6, the removal of these compounds by the energetically more efficient sulphate-reducing bacteria can impose a substrate limitation on methanogenic bacteria 7-9. However, two known species of methanogens, Methanosarcina barkeri and Methanococcus mazei, can grow on and produce methane from methanol and methylated amines10-13. In addition, these compounds stimulate methane production by bacterial enrichments from the rumen11,14 and aquatic muds13,14. Methanol can enter anaerobic food webs through bacterial degradation of lignins15 or pectin16, and methylated amines can be produced either from decomposition of substances like choline, creatine and betaine13,14 or by bacterial reduction of trimethylamine oxide17, a common metabolite and excretory product of marine animals. However, the relative importance of methanol and methylated amines as precursors of methane in sediments has not been previously examined. We now report that methanol and trimethylamine are important substrates for methanogenic bacteria in salt marsh sediments and that these compounds may account for the bulk of methane produced therein. Furthermore, because these compounds do not stimulate sulphate reduction, methanogenesis and sulphate reduction can operate concurrently in sulphate-containing anoxic sediments. ?? 1982 Nature Publishing Group.

  14. Monitoring crude oil mineralization in salt marshes: Use of stable carbon isotope ratios

    SciTech Connect

    Jackson, A.W.; Pardue, J.H.; Araujo, R.

    1996-04-01

    In laboratory microcosms using salt marsh soils and in field trials, it was possible to monitor and quantify crude oil mineralization by measuring changes in CO{sub 2} {delta}{sup 13}C signatures and the rate of CO{sub 2} production. These values are easy to obtain and can be combined with simple isotope mass balance equations to determine the rate of mineralization from both the crude oil and indigenous carbon pool. Hydrocarbon degradation was confirmed by simultaneous decreases in alkane-, isoprenoid-, and PAH-hopane ratios. Additionally, the pseudo-first-order rate constants of alkane degradation (0.087 day{sup -1}) and CO{sub 2} production (0.082 day{sup -1}) from oil predicted by the {delta}{sup 13}C signatures were statistically indistinguishable. The addition of inorganic nitrogen and phosphate increased the rate of mineralization of crude oil in aerated microcosms but had no clear effect on in situ studies. This procedure appears to offer a means of definitively quantifying crude oil mineralization in a sensitive, inexpensive, and simple manner in environments with appropriate background {delta}{sup 13}C signatures. 23 refs., 5 figs., 1 tab.

  15. Porewater evidence for a dynamic sedimentary iron cycle in salt marshes

    SciTech Connect

    Giblin, A.E.; Howarth, R.W.

    1984-01-01

    Dynamic transformations of iron occur seasonally at Great Sippewissett March, Massachusetts. Small changes in the dissolved iron concentration in porewater represent only a small fraction of the iron involved in transformation reactions during the year. During the growing seasons, 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. 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 formations 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.

  16. Synergistic effect of crude oil plus dispersant on bacterial community in a louisiana salt marsh sediment.

    PubMed

    Al-Jawasim, Mohammed; Yu, Kewei; Park, Joong-Wook

    2015-09-01

    A combined effect of crude oil plus dispersant (Corexit 9500A) significantly altered indigenous bacterial communities in a Louisiana salt marsh sediment after 30 days of incubation; the crude oil and/or Corexit 9500A treatments triggered shifts in bacterial communities and the shifted bacterial structure by crude oil plus Corexit 9500A was considerably different from those by either crude oil or Corexit 9500A. However, the synergistic effect of crude oil plus Corexit 9500A was not observed after 7 days of incubation; the bacterial community was slightly shifted by Corexit 9500A and the crude oil did not trigger any bacterial community shift after 7 days of incubation. DNA sequencing data indicated that Chromobacterium species was enriched in the Corexit 9500A microcosms after 7 days of incubation, while Pseudomonas, Advenella, Acidocella and Dyella spp. were enriched after 30 days of incubation. Parvibaculum was a dominant species in the crude oil microcosms after 30 days of incubation. Rhodanobacter, Dyella and Frateuria spp. were dominant in crude oil plus Corexit 9500A microcosms after 30 days of incubation. Our data show that the effect of crude oil plus Corexit 9500A on bacterial community is synergistic, and thus the dispersant effect should be considered with the spilled oil to correctly evaluate the environmental impact. PMID:26316543

  17. Where temperate meets tropical: Multi-factorial effects of elevated CO2, nitrogen enrichment, and competition on a mangrove-salt marsh community

    USGS Publications Warehouse

    McKee, K.L.; Rooth, J.E.

    2008-01-01

    Our understanding of how elevated CO2 and interactions with other factors will affect coastal plant communities is limited. Such information is particularly needed for transitional communities where major vegetation types converge. Tropical mangroves (Avicennia germinans) intergrade with temperate salt marshes (Spartina alterniflora) in the northern Gulf of Mexico, and this transitional community represents an important experimental system to test hypotheses about global change impacts on critical ecosystems. We examined the responses of A. germinans (C3) and S. alterniflora (C4), grown in monoculture and mixture in mesocosms for 18 months, to interactive effects of atmospheric CO2 and pore water nitrogen (N) concentrations typical of these marshes. A. germinans, grown without competition from S. alterniflora, increased final biomass (35%) under elevated CO2 treatment and higher N availability. Growth of A. germinans was severely curtailed, however, when grown in mixture with S. alterniflora, and enrichment with CO2 and N could not reverse this growth suppression. A field experiment using mangrove seedlings produced by CO2- and N-enriched trees confirmed that competition from S. alterniflora suppressed growth under natural conditions and further showed that herbivory greatly reduced survival of all seedlings. Thus, mangroves will not supplant marsh vegetation due to elevated CO2 alone, but instead will require changes in climate, environmental stress, or disturbance to alter the competitive balance between these species. However, where competition and herbivory are low, elevated CO2 may accelerate mangrove transition from the seedling to sapling stage and also increase above- and belowground production of existing mangrove stands, particularly in combination with higher soil N. ?? 2008 The Authors Journal compilation ?? 2008 Blackwell Publishing Ltd.

  18. Long-term impacts of disturbance on nitrogen-cycling bacteria in a New England salt marsh.

    PubMed

    Bernhard, Anne E; Dwyer, Courtney; Idrizi, Adrian; Bender, Geoffrey; Zwick, Rachel

    2015-01-01

    Recent studies on the impacts of disturbance on microbial communities indicate communities show differential responses to disturbance, yet our understanding of how different microbial communities may respond to and recover from disturbance is still rudimentary. We investigated impacts of tidal restriction followed by tidal restoration on abundance and diversity of denitrifying bacteria, ammonia-oxidizing bacteria (AOB), and ammonia-oxidizing archaea (AOA) in New England salt marshes by analyzing nirS and bacterial and archaeal amoA genes, respectively. TRFLP analysis of nirS and betaproteobacterial amoA genes revealed significant differences between restored and undisturbed marshes, with the greatest differences detected in deeper sediments. Additionally, community patterns indicated a potential recovery trajectory for denitrifiers. Analysis of archaeal amoA genes, however, revealed no differences in community composition between restored and undisturbed marshes, but we detected significantly higher gene abundance in deeper sediment at restored sites. Abundances of nirS and betaproteobacterial amoA genes were also significantly greater in deeper sediments at restored sites. Porewater ammonium was significantly higher at depth in restored sediments compared to undisturbed sediments, suggesting a possible mechanism driving some of the community differences. Our results suggest that impacts of disturbance on denitrifying and ammonia-oxidizing communities remain nearly 30 years after restoration, potentially impacting nitrogen-cycling processes in the marsh. We also present data suggesting that sampling deeper in sediments may be critical for detecting disturbance effects in coastal sediments. PMID:25699033

  19. Long-term impacts of disturbance on nitrogen-cycling bacteria in a New England salt marsh

    PubMed Central

    Bernhard, Anne E.; Dwyer, Courtney; Idrizi, Adrian; Bender, Geoffrey; Zwick, Rachel

    2015-01-01

    Recent studies on the impacts of disturbance on microbial communities indicate communities show differential responses to disturbance, yet our understanding of how different microbial communities may respond to and recover from disturbance is still rudimentary. We investigated impacts of tidal restriction followed by tidal restoration on abundance and diversity of denitrifying bacteria, ammonia-oxidizing bacteria (AOB), and ammonia-oxidizing archaea (AOA) in New England salt marshes by analyzing nirS and bacterial and archaeal amoA genes, respectively. TRFLP analysis of nirS and betaproteobacterial amoA genes revealed significant differences between restored and undisturbed marshes, with the greatest differences detected in deeper sediments. Additionally, community patterns indicated a potential recovery trajectory for denitrifiers. Analysis of archaeal amoA genes, however, revealed no differences in community composition between restored and undisturbed marshes, but we detected significantly higher gene abundance in deeper sediment at restored sites. Abundances of nirS and betaproteobacterial amoA genes were also significantly greater in deeper sediments at restored sites. Porewater ammonium was significantly higher at depth in restored sediments compared to undisturbed sediments, suggesting a possible mechanism driving some of the community differences. Our results suggest that impacts of disturbance on denitrifying and ammonia-oxidizing communities remain nearly 30 years after restoration, potentially impacting nitrogen-cycling processes in the marsh. We also present data suggesting that sampling deeper in sediments may be critical for detecting disturbance effects in coastal sediments. PMID:25699033

  20. Short-term endproducts of sulfate reduction in a salt marsh: Formation of acid volatile sulfides, elemental sulfur, and pyrite

    NASA Astrophysics Data System (ADS)

    King, Gary M.; Howes, B. L.; Dacey, J. W. H.

    1985-07-01

    Rates of sulfate reduction, oxygen uptake and carbon dioxide production in sediments from a short Spartina alterniflora zone of Great Sippewissett Marsh were measured simultaneously during late summer. Surface sediments (0-2 cm) were dominated by aerobic metabolism which accounted for about 45% of the total carbon dioxide production over 0-15 cm. Rates of sulfate reduction agreed well with rates of total carbon dioxide production below 2 cm depth indicating that sulfate reduction was the primary pathway for sub-surface carbon metabolism. Sulfate reduction rates were determined using a radiotracer technique coupled with a chromous chloride digestion and carbon disulfide extraction of the sediment to determine the extent of formation of radiolabelled elemental sulfur and pyrite during shortterm (48 hr) incubations. In the surface 10 cm of the marsh sediments investigated, about 50% of the reduced radiosulfur was recovered as dissolved or acid volatile sulfides, 37% as carbon disulfide extractable sulfur, and only about 13% was recovered in a fraction operationally defined as pyrite. Correlations between the extent of sulfate depletion in the marsh sediments and the concentrations of dissolved and acid volatile sulfides supported the results of the radiotracer work. Our data suggest that sulfides and elemental sulfur may be major short-term end-products of sulfate reduction in salt marshes.

  1. Primary productivity of angiosperm and macroalgae dominated habitats in a New England salt marsh: a comparative analysis

    USGS Publications Warehouse

    Roman, C.T.; Able, K.W.; Lazzari, M.A.; Heck, K.L.

    1990-01-01

    Net primary productivity estimates were made for the major macrophyte dominated habitats of the Nauset Marsh system, Cape Cod, Massachusetts. Above-ground primary productivity of short form Spartina alterniflora, the dominant habitat of the system, was 664 g m-2 y-1. Productivity of the other dominant angiosperm (Zostera marina) was estimated to range from 444?987 g m-2 y-1. The marsh creekbank habitat was dominated by an intertidal zone of fucoid algae (Ascophyllum nodosum ecad. scorpioides, 1179 g m-2 y-1; Fucus vesiculosus, 426 g m-2 y-1), mixed intertidal filamentous algae (91 g m-2 y-1), and a subtidal zone of assorted macroalgae (68 g m-2 y-1). Intertidal mudflats were dominated by Cladophora gracilis, with net production ranging from 59?637 g m-2 y-1. These angiosperm and macrophyte and macrophyte dominated habitats produce over 3 ? 106 kg y-1 of biomass (1?2 ? 106 kg carbon y-1). Twenty-eight per cent (28%) of this carbon production is derived from the Zostera and macroalgae habitats. Although S. alterniflora is considered the major macrophyte primary producer in Nauset Marsh and other north temperate salt marshes, it is concluded that other habitats also contribute significantly to total system carbon production.

  2. Nonlinear responses of coastal salt marshes to nutrient additions and sea level rise

    EPA Science Inventory

    Increasing nutrients and accelerated sea level rise (SLR) can cause marsh loss in some coastal systems. Responses to nutrients and SLR are complex and vary with soil matrix, marsh elevation, sediment inputs, and hydroperiod. We describe field and greenhouse studies examining sing...

  3. Effects of long-term grazing on sediment deposition and salt-marsh accretion rates

    NASA Astrophysics Data System (ADS)

    Elschot, Kelly; Bouma, Tjeerd J.; Temmerman, Stijn; Bakker, Jan P.

    2013-11-01

    Many studies have attempted to predict whether coastal marshes will be able to keep up with future acceleration of sea-level rise by estimating marsh accretion rates. However, there are few studies focussing on the long-term