These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Arsenic incorporation in a salt marsh ecosystem  

NASA Astrophysics Data System (ADS)

Replicate portions of a Delaware salt marsh were enclosed in cylindrical microcosms and exposed to elevated levels of inorganic arsenic (arsenate). All biotic and abiotic components in dosed cylinders rapidly incorporated arsenic. Spartina blades showed the greatest arsenic enrichment, with dosed plants incorporating arsenic concentrations an order of magnitude higher than controls. Spartina detritus and sediments also exhibited greatly elevated arsenic concentrations. Virtually all of the arsenic was incorporated into plant tissue or strongly sorbed to cell surfaces. Thus, elevated arsenic concentrations in estuarine waters will be reflected in living and non-living components of a salt marsh ecosystem, implying that increased arsenic will be available to organisms within the marsh ecosystem.

Sanders, James G.; Osman, Richard W.

1985-04-01

2

Centuries of Human-Driven Change in Salt Marsh Ecosystems  

NASA Astrophysics Data System (ADS)

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.

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

2009-01-01

3

Self-organization and vegetation collapse in salt marsh ecosystems.  

PubMed

Complexity theory predicts that local feedback processes may strongly affect the organization of ecosystems on larger spatial scales. Whether complexity leads to increased resilience and stability or to increased vulnerability and criticality remains one of the dominant questions in ecology. We present a combined theoretical and empirical study of complex dynamics in mineralogenic salt marsh ecosystems that emerge from a positive feedback between clay accumulation and plant growth. Positive feedback induces self-organizing within the ecosystem, which buffers for the strong physical gradient that characterizes the marine-terrestrial boundary, and improves plant growth along the gradient. However, as a consequence of these self-organizing properties, salt marshes approach a critical state as the edge of the salt marsh and the adjacent intertidal flat becomes increasingly steep and vulnerable to wave attack. Disturbance caused, for instance, by a storm may induce a cascade of vegetation collapse and severe erosion on the cliff edge, leading to salt marsh destruction. Our study shows that on short timescales, self-organization improves the functioning of salt marsh ecosystems. On long timescales, however, self-organization may lead to destruction of salt marsh vegetation. PMID:15729634

van de Koppel, Johan; van der Wal, Daphne; Bakker, Jan P; Herman, Peter M J

2005-01-01

4

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

Microsoft Academic Search

Salt marshes are coastal ecosystems characterized by high biodiversity and rates of primary productivity, providing fundamental ecosystem services. Salt-marsh ecosystems are important indicators of environmental change as the dynamics are governed by interacting physical and biological processes, whose intertwined feedbacks critically affect the evolution. Settling deposition of inorganic sediment allows the platform to reach a threshold elevation for vegetation encroachment;

Andrea D'Alpaos

2011-01-01

5

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...

6

Fate and effects of nutrients and heavy metals in experimental salt marsh ecosystems  

Microsoft Academic Search

Fate and effects of the macro nutrients nitrogen and phosphorus, and the heavy metals zinc, copper and cadmium, brought into experimental salt marsh ecosystems via sediment supply, were studied over a three-year period.The supply of sediment from the Marsdiep (at a low and high rate) and from the harbour of Delfzijl (at a high rate) led to an increase of

Peter C. Leendertse; Martin C. Th. Scholten; Jan Tjalling van der Wal

1996-01-01

7

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

PubMed

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

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

2012-06-01

8

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

PubMed

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

Bertness, Mark D; Coverdale, Tyler C

2013-09-01

9

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

NASA Astrophysics Data System (ADS)

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 flooding. To partition the net flux into its component fluxes gross primary production (GPP) and ecosystem respiration (Reco), these tidal influences have to be incorporated in the NEE model. Differences in GPP and Reco during high tide and low tide events can be used to constrain estimates of lateral carbon transport. These will need to be compared to direct measurements of tidal carbon fluxes to determine how much of the reduction in atmospheric fluxes is due to metabolic changes and how much is due to the exchange of carbon between the marsh and water.

Forbrich, I.; Giblin, A.

2013-12-01

10

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

NASA Astrophysics Data System (ADS)

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

D'Alpaos, A.; Marani, M.

2010-12-01

11

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

PubMed

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

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

2012-11-01

12

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

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

13

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

PubMed Central

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

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

2014-01-01

14

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

PubMed

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

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

2014-01-01

15

Ecosystem Functions of Tidal Fresh, Brackish, and Salt Marshes on the Georgia Coast  

E-print Network

greatest at brackish sites, followed by freshwater then saline sites. Nitrogen stocks in plants and soil estuary, variation in salinity may lead to marked differences in the functioning of tidal marsh plant communities (Odum 1988). Odum argued that salinity-driven stress should reduce plant diversity in tidal salt

Pennings, Steven C.

16

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

NASA Astrophysics Data System (ADS)

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 provide detailed imagery of fluid interactions at the ground/surface water interface during a tidal cycle. The resistivity profiles are presented as color contoured tomograms representing the shallow aquifer system to depths exceeding 20 meters. Measurements took place during a series of large precipitation events, including immediately before and after a tropical storm, as well as during relatively dry conditions. Taking into account the metrological variability, our initial results indicate that the SGD process is most strongly influenced by tidal pumping. Radon analysis and resistivity measurements reveal strong inverse relationships with water level. Percent difference resistivity models indicate substantial tidally controlled pore fluid flushing and mixing within the shallow aquifer system. These measurements will be further used to construct a water budget within the Duplin River and to delineate the extent of variability in salinity of shallow marsh sediments. In addition, these measurements will provide accurate rates and flow geometries useful as constraints on ongoing reactive transport modeling efforts.

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

2013-12-01

17

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

USGS Publications Warehouse

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.

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

2012-01-01

18

A laboratory study on biochemical degradation and microbial utilization of organic matter comprising a marine diatom, land grass, and salt marsh plant in estuarine ecosystems  

Microsoft Academic Search

We studied the biochemical degradation of organic matter comprising marine diatom, land grass, and salt marsh plant in estuarine\\u000a ecosystems in two laboratory microcosms consisting of estuarine sediments and coastal seawater. The materials were incubated\\u000a separately and together under controlled oxic and anoxic conditions to test effects of co-metabolism and redox on overall\\u000a degradation of organic matter. We followed variations

Jihong Dai; Ming-Yi Sun; Randolph A. Culp; John E. Noakes

2009-01-01

19

Salt marsh geomorphology: Physical and ecological effects on landform Keywords: salt marsh geomorphology; AGU Chapman Conference  

E-print Network

Editorial Salt marsh geomorphology: Physical and ecological effects on landform Keywords: salt marsh geomorphology; AGU Chapman Conference Evidence that the three-dimensional structure of salt marsh, and the ratio of marsh edge:marsh interior have all been shown to affect the distribution and density of salt

Fagherazzi, Sergio

20

Salt marsh geomorphology: Physical and ecological effects on landform  

NASA Astrophysics Data System (ADS)

Salt marshes are among the most productive ecosystems on the planet, producing more organic matter per unit area than forests, grasslands, and cultivated fields. Marsh landscapes typically fringe low-energy coastal environments, but in places they may extend inland tens to hundreds of kilometers.As a consequence of their high productivity and interactions with the coastal ocean, salt marshes provide numerous benefits to society. For example, salt marshes are critical habitats for commercially harvested marine and estuarine biota; they filter nutrients and sediment from the water column; and they provide recreational opportunities. In addition, salt marshes help dissipate erosive tide and wave energy and they have intrinsic aesthetic values. All of these societal benefits have a quantifiable economic value, and salt marsh impairment and degradation have associated costs.

Fagherazzi, Sergio; Torres, Raymond; Hopkinson, Charles; Van Proosdij, Danika

21

Chemical and Biological Gradients: Controls on Nitrous Oxide Release in Salt Marsh Ecosystems  

E-print Network

Jennifer Reeve (Haverford College, 2014) With guidance from: Anne Giblin (The Ecosystems Center, Marine. These cores were treated for 3 weeks before their consumption of nitrous oxide was measured. The nitrate

Vallino, Joseph J.

22

Relationships between Sediment Microbial Communities and Pollutants in Two California Salt Marshes  

Microsoft Academic Search

Salt marshes are important ecosystems whose plant and microbial communities can alter terrestrially derived pollutants prior to coastal water discharge. However, knowledge regarding relationships between anthropogenic pollutant levels and salt marsh microbial communities is limited, and salt marshes on the West Coast of the United States are rarely examined. In this study, we investigated the relationships between microbial community composition

Y. Cao; G. N. Cherr; A. L. Córdova-Kreylos; T. W.-M. Fan; P. G. Green; R. M. Higashi; M. G. LaMontagne; K. M. Scow; C. A. Vines; J. Yuan; P. A. Holden

2006-01-01

23

Coastal eutrophication as a driver of salt marsh loss.  

PubMed

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

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

2012-10-18

24

Experimental predator removal causes rapid salt marsh die-off.  

PubMed

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

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

2014-07-01

25

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

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 open water habitat vs. 11% of the plugged marsh). The response of birds, categorized as waterfowl & waterbirds, shorebirds & wading birds, gulls & terns, and miscellaneous (raptors, passerines, other), was variable. Following ditch plugging, bird species richness increased at the Granite Point site (1999 pre-plug = 15.4, 2000 post-plug = 26.2, 2001 post-plug = 38.7). Because of a low sample size at Moody Marsh, reliable statements on species richness cannot be made. Density of birds (no. of birds per ha) remained unchanged with ditch plugging at Granite Point Marsh, although there was a strong, but not statistically significant, trend toward increased density. This study only reports on initial responses of marsh functions to ditch plugging. Monitoring should continue at these sites, and perhaps at additional sites, for the next decade or so. A monitoring plan is recommended. Long-term monitoring will include evaluation of salt marsh development processes using SET (surface elevation table) methodology. There is concern, although not confirmed, that as ditch-plugged marshes become wetter and marsh grass production declines their ability to keep pace with sea level rise could be jeopardized. It is suggested that ditch plugging should be considered an experimental marsh management technique. Additional monitoring on the physical and habitat responses of ditch-plugged marshes is required, along with assessments of other techniques aimed at restoring open water habitat to the marsh surface.

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

2002-01-01

26

Restoring Ecological Function to a Submerged Salt Marsh  

USGS Publications Warehouse

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.

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

2010-01-01

27

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

Microsoft Academic Search

Fungal decomposers are important con- tributors to the detritus-based food webs of salt marsh ecosystems. Knowing the composition of salt marsh fungal communities is essential in under- standing how detritus processing is affected by changes in community dynamics. Automated ribo- somal intergenic spacer analysis (ARISA) was used to examine the composition of fungal communities associated with four temperate salt marsh

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

2006-01-01

28

Wave attenuation over coastal salt marshes under storm surge conditions  

NASA Astrophysics Data System (ADS)

Coastal communities around the world face an increasing risk from flooding as a result of rising sea level, increasing storminess and land subsidence. Salt marshes can act as natural buffer zones, providing protection from waves during storms. However, the effectiveness of marshes in protecting the coastline during extreme events when water levels are at a maximum and waves are highest is poorly understood. Here we experimentally assess wave dissipation under storm surge conditions in a 300-metre-long wave flume tank that contains a transplanted section of natural salt marsh. We find that the presence of marsh vegetation causes considerable wave attenuation, even when water levels and waves are highest. From a comparison with experiments without vegetation, we estimate that up to 60% of observed wave reduction is attributed to vegetation. We also find that although waves progressively flatten and break vegetation stems and thereby reduce dissipation, the marsh substrate remained stable and resistant to surface erosion under all conditions. The effectiveness of storm wave dissipation and the resilience of tidal marshes even at extreme conditions suggest that salt marsh ecosystems can be a valuable component of coastal protection schemes.

Möller, Iris; Kudella, Matthias; Rupprecht, Franziska; Spencer, Tom; Paul, Maike; van Wesenbeeck, Bregje K.; Wolters, Guido; Jensen, Kai; Bouma, Tjeerd J.; Miranda-Lange, Martin; Schimmels, Stefan

2014-10-01

29

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

USGS Publications Warehouse

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.

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

30

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

USGS Publications Warehouse

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.

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

31

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

Microsoft Academic Search

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,

Patrick Poulin; Emilien Pelletier; Richard Saint-Louis

2007-01-01

32

Natural and Manipulated Sources of Heterogeneity Controlling Early Faunal Development of a Salt Marsh  

Microsoft Academic Search

Ecosystem recovery following wetland restoration offers exceptional op- portunities to study system structure, function, and successional processes in salt marshes. This study used observations of natural variation and large-scale manipulative experiments to test the influence of vascular vegetation and soil organic matter on the rate and trajectory of macrofaunal recovery in a southern California created salt marsh, the Crown Point

Lisa A. Levin; Theresa S. Talley

2002-01-01

33

Utilization of invasive tamarisk by salt marsh consumers  

Microsoft Academic Search

Plant invasions of coastal wetlands are rapidly changing the structure and function of these systems globally. Alteration\\u000a of litter dynamics represents one of the fundamental impacts of an invasive plant on salt marsh ecosystems. Tamarisk species\\u000a (Tamarix spp.), which extensively invade terrestrial and riparian habitats, have been demonstrated to enter food webs in these ecosystems.\\u000a However, the trophic impacts of

Christine R. Whitcraft; Lisa A. Levin; Drew Talley; Jeffrey A. Crooks

2008-01-01

34

Making and Measuring a Model of a Salt Marsh  

NSDL National Science Digital Library

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 great diversity of life and ecosystems, which is one of the ocean literacy principles outlined by the Ocean Literacy Network.

Curran, Mary C.; Fogleman, Tara

2007-12-01

35

Mobile dunes and eroding salt marshes  

NASA Astrophysics Data System (ADS)

The paper deals with general outlines of salt marsh and dune vegetation in the Ellenbogen and Listland area on Sylt (Schleswig-Holstein, FRG). The composition of current salt marsh vegetation is considered to be mainly the result of a long-lasting process of tidal inundation, grazing, and a permanent influence of groundwater seepage from the surrounding dunes. The lower salt marsh communities have shown constancy for 67 years, due to the effect of heavy grazing. The mid-upper salt marsh communities demonstrated a succession from a Puccinellia maritima-dominated community of the lower marsh to a Juncus gerardii-dominated community of the mid-upper salt marsh, which may be due to the transport of sand — over a short time — on the surface of the marsh. The area covered by plant communities of annuals below Mean High Water (MHW) seemed to diminish. Salt marsh soils, especially of the mid-upper marsh, indicate sandy layers resulting from sand drift of the dunes. Dry and wet successional series of the dunes in the Listland/Ellenbogen area both show grassy stages shifting to dwarf shrubs as final stages. White primary dunes can only be found on the accreting shoreline of the Ellenbogen, which is also grazed by sheep; vegetation cover therefore remains dominated by grasses, mosses and lichens. Three mobile dunes (as the most prominent features of this landscape) have been left unaffected by seeding and planting by local authorities. Grazing is considered to be an inadequate tool in nature conservation as long as natural processes are to prevail in the landscape as major determinants.

Neuhaus, R.

1994-06-01

36

Responses of Salt Marsh Plant Rhizosphere Diazotroph Assemblages to Changes in Marsh Elevation, Edaphic Conditions and Plant Host Species  

Microsoft Academic Search

An important source of new nitrogen in salt marsh ecosystems is microbial diazotrophy (nitrogen fixation). The diazotroph\\u000a assemblages associated with the rhizospheres (sediment directly affected by the roots) of salt marsh plants are highly diverse,\\u000a somewhat stable, and consist mainly of novel organisms. In Crab Haul Creek Basin, North Inlet, SC, the distribution of plant\\u000a types into discrete zones is

Debra A. Davis; Megan D. Gamble; Christopher E. Bagwell; Peter W. Bergholz; Charles R. Lovell

2011-01-01

37

Regional ontogeny of New England salt marsh die-off.  

PubMed

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

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

2013-10-01

38

Mercury volatilization from salt marsh sediments  

Microsoft Academic Search

In situ volatilization fluxes of gaseous elemental mercury, Hg(0), were estimated for tidally exposed salt marsh sediments in the summer at the urban\\/industrial Secaucus High School Marsh, New Jersey Meadowlands (Secaucus, New Jersey) and in the early autumn at a regional background site in the Great Bay estuary (Tuckerton, New Jersey). Estimated daytime sediment-air mercury volatilization fluxes at the Secaucus

Lora M. Smith; John R. Reinfelder

2009-01-01

39

Effects of pH and plant sourceon lignocellulose biodegradation rates in two wetland ecosystems, the Okefenokee Swamp and a Georgia salt marsh  

Microsoft Academic Search

The microbial mineralization of synthetic ( L4C)lignin, specifically radiolabeled ( 14C-ligninl-lig- nocellulose and ( L4C-polysaccharide)-lignocellulose from a variety of aquatic herbaceous and woody plants was investigated in water and sediment from a salt marsh on Sapelo Island, Georgia, and from the Okefenokee Swamp, an acidic peat-forming freshwater swamp in southern Georgia. Rates of microbial degradation of lignocellulose were depressed in

RONALD BENNER; MARY ANN MORAN; ROBERT E. HODSON

1985-01-01

40

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...

41

Tidal regime, salinity and salt marsh plant zonation  

Microsoft Academic Search

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

Sonia Silvestri; Andrea Defina; Marco Marani

2005-01-01

42

Tidal regime, salinity and salt marsh plant zonation  

Microsoft Academic Search

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

Sonia Silvestri; Andrea Defina; Marco Marani

2004-01-01

43

Gross production exceeds gross consumption of methyl halides in northern California salt marshes  

NASA Astrophysics Data System (ADS)

Coastal salt marshes are sources of CH3Br and CH3Cl to the atmosphere, but the wide range of reported emission rates illustrates the need to understand better the factors controlling net fluxes. Here we demonstrate the use of a stable isotope tracer method to separately evaluate gross production and consumption fluxes to determine their relative roles in the overall net flux. At two salt marshes in northern California, gross production exceeds gross consumption at all measured sites, leading to a large net source overall. Emission rates are within the range observed at other temperate salt marshes. By evaluating the consumption component separately, we explain how a typical salt marsh source might convert into a temporary net sink by exposing the ecosystem to uncharacteristically high concentrations of methyl halides. This circumstance may account for the reported net uptake of methyl chloride during the growing season at a coastal salt marsh in China.

Rhew, Robert; Mazéas, Olivier

2010-09-01

44

Factors controlling dimethylsulfide emission from salt marshes  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

45

Vegetable Oil Spills On Salt Marshes  

Microsoft Academic Search

Following the wreck of the M.V. Kimya during which 1500 tonnes of sunflower oil was spilled, sandy sediments bound together with sunflower oil were discovered on the beach. These are still present 2½ years later. Sunflower and linseed oil were applied to salt marsh sediments to reproduce potential spills. Cores were taken and the vertical migration and degradation rates determined.

Stephen M. Mudge; Ian D. Goodchild; Matthew Wheeler

1995-01-01

46

The Effects of Tidal Export from Salt Marsh Ditches on Estuarine Water Quality and Plankton Communities  

Microsoft Academic Search

Salt marshes are an important transition zone between terrestrial and marine ecosystems, and in their natural state, they\\u000a often function to cycle or trap terrestrially derived nutrients and organic matter. Many US salt marshes were ditched during\\u000a the twentieth century, potentially altering their functionality. The goal of this 4-year study was to assess the impact of\\u000a water from ditches within

Florian Koch; Christopher J. Gobler

2009-01-01

47

Accelerating the Restoration of Vegetation in a Southern California Salt Marsh  

Microsoft Academic Search

Re-establishing plant cover is essential for restoring ecosystem functions, but revegetation can be difficult in severe sites,\\u000a such as salt marshes that experience hypersalinity and sedimentation. We tested three treatments (adding tidal creeks, planting\\u000a seedlings in tight clusters, and rototilling kelp compost into the soil) in a site that was excavated to reinstate tidal flows\\u000a and restore salt marsh. The

Erin L. O’Brien; Joy B. Zedler

2006-01-01

48

Mapping salt marsh vegetation using aerial hyperspectral imagery and linear unmixing in Humboldt Bay, California  

Microsoft Academic Search

Composition of salt marsh vegetation is important to wetland ecosystem health, and monitoring invasive species is critical.\\u000a The purpose of this study was to examine the utility of airborne hyperspectral imagery in mapping salt marsh vegetation in\\u000a Humboldt Bay, California, USA. An unmixing algorithm was applied to spatial and spectral image subsets. Overall accuracy among\\u000a Spartina densiflora, Salicornia virginica, and

Chaeli Judd; Steven Steinberg; Frank Shaughnessy; Greg Crawford

2007-01-01

49

A trophic cascade regulates salt marsh primary production.  

PubMed

Nutrient supply is widely thought to regulate primary production of many ecosystems including salt marshes. However, experimental manipulation of the dominant marsh grazer (the periwinkle, Littoraria irrorata) and its consumers (e.g., blue crabs, Callinectes sapidus, terrapins, Malaclemys terrapin) demonstrates plant biomass and production are largely controlled by grazers and their predators. Periwinkle grazing can convert one of the most productive grasslands in the world into a barren mudflat within 8 months. Marine predators regulate the abundance of this plant-grazing snail. Thus, top-down control of grazer density is a key regulatory determinant of marsh grass growth. The discovery of this simple trophic cascade implies that over-harvesting of snail predators (e.g., blue crabs) may be an important factor contributing to the massive die-off (tens of km(2)) of salt marshes across the southeastern United States. In addition, our results contribute to a growing body of evidence indicating widespread, predator regulation of marine macrophyte production via trophic cascades (kelps, seagrasses, intertidal algae). PMID:12149475

Silliman, Brian Reed; Bertness, Mark D

2002-08-01

50

Response of a salt marsh microbial community to metal contamination  

NASA Astrophysics Data System (ADS)

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 potential and further work on this subject is in need.

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

2013-09-01

51

Storm-driven groundwater flow in a salt marsh  

NASA Astrophysics Data System (ADS)

Storms can cause significant groundwater flow in coastal settings, but prior studies of the effects of storms on groundwater flow and transport have largely focused on very large storms and used salinity as a tracer. We have little information about the effects of smaller storms on coastal flow and how storm-induced variability affects key tidal wetlands like salt marshes, which may remain saline throughout a storm. Here we show that even the distant passage of a moderate storm can strongly increase groundwater flow and transport in salt marsh ecosystems and adjacent barrier islands. Groundwater monitoring and radium isotope tracer analyses revealed significant influx of saline creek water into the confined aquifer below the marsh platform, driven by storm surge. This pulse of fluids reached depths exceeding 5 m, and surge-enhanced tides propagated through the aquifer to affect flow in the upland >100 m from the creek bank. Groundwater discharge from the marsh varied significantly prior to the storm, doubling during inundating tides compared to a period of noninundating neap tides. Storm surge then caused groundwater discharge to decline ˜50% compared to similar inundating tides. Ra- and nutrient-poor creek water that entered the confined aquifer below the marsh was quickly enriched in nutrients and carbon, even on 12 h tidal cycles, so that nutrient discharge was likely proportional to groundwater discharge. Storm-related flow could also drive significant contaminant discharge from developed coastlines. The enhanced transport and variability observed here likely affected hundreds of kilometers of the coastline impacted by the storm.

Wilson, Alicia M.; Moore, Willard S.; Joye, Samantha B.; Anderson, Joseph L.; Schutte, Charles A.

2011-02-01

52

Nest repair behavior in birds nesting in salt marshes  

Microsoft Academic Search

Studied 5 species of birds nesting in salt marshes in New Jersey to determine their ability to respond to natural and experimental changes in their nests. Laughing gulls and clapper rails nest in the lowest areas of the marsh, common terns nest in intermediate areas, and herring gulls and mallards nest in high marsh areas. Manipulations of nests included wetting

Joanna Burger

1979-01-01

53

Nutrient enrichment and the role of salt marshes in the Tagus estuary (Portugal)  

NASA Astrophysics Data System (ADS)

Eutrophication is one of the most common impacts of nutrient enrichment on coastal ecosystems. Since there is a wide ecosystem response variety in scale, intensity and impact to nutrient enrichment, the loading required to produce eutrophication symptoms to each system is also variable. In estuaries and coastal zones salt marsh primary producers have received less attention, mainly because salt marsh dominated systems are considered less sensitive to nutrient enrichment and, for that reason, their response is slower and more difficult to quantify. Salt marshes have been considered as major attenuators of the effects of nitrogen enrichment in several coastal systems, and are indicated as a measure of the system susceptibility to nutrient enrichment. The main goal of the present work is to discuss the role of salt marsh vegetation in the nutrient dynamics of coastal systems and in the nutrient enrichment process. For these purposes salt marsh vegetation growth in the Tagus estuary is described through a mathematical model which includes the simulation of the nutrient dynamics through the sediment-water interface and the uptake kinetics by the vascular plants. An analysis of the role of salt marsh vegetation on the nutrient dynamics of the Tagus estuary is carried out through the discussion of the model results and comparison with data obtained for other primary producers in the system. The results indicate that C 4 salt marsh plants have the highest productivity, followed by seaweeds. The total net production of salt marsh plants and is about 12,600 ton C yr -1, accounting for 25% of the total primary production within the system.

Simas, T. C.; Ferreira, J. G.

2007-11-01

54

Remote sensing of wetland conditions in West Coast salt marshes  

NASA Astrophysics Data System (ADS)

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.

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

2004-11-01

55

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...

56

Effects of historic tidal restrictions on salt marsh sediment chemistry  

Microsoft Academic Search

The effects of tidalrestrictions by diking on salt marshbiogeochemistry were interpreted by comparingthe hydrology, porewater chemistry and solidphase composition of both seasonally floodedand drained diked marshes with adjacentnatural salt marshes on Cape Cod,Massachusetts. Flooding periods weregreatest in natural and least in drainedmarshes.

J. W. PORTNOY; A. E. GIBLIN

1997-01-01

57

New York State Salt Marsh Restoration and Monitoring Guidelines  

E-print Network

#12;New York State Salt Marsh Restoration and Monitoring Guidelines prepared by: Nancy L. Niedowski Resources Bureau of Marine Resources 205 N. Belle Meade Road East Setauket, NY 11733 December 1, 2000 #12;The Salt Marsh Restoration and Monitoring Guidelines were prepared under the National Oceanic

58

Large methyl halide emissions from south Texas salt marshes  

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

59

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

USGS Publications Warehouse

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.

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

1995-01-01

60

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

PubMed Central

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

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

2014-01-01

61

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...

62

Development of Salt Marsh Monitoring Methodology Using Remote Sensing and GIS  

E-print Network

Development of Salt Marsh Monitoring Methodology Using Remote Sensing and GIS Y.Q. Wang, PI://www.ltrs.uri.edu #12;New Satellite Data in Salt Marsh Change Monitoring Given that salt marsh monitoring requires update the salt marsh maps are necessary. Recent development of high spatial resolution satellite remote

Wang, Y.Q. "Yeqiao"

63

Methane flux from coastal salt marshes  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

64

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...

65

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

NASA Astrophysics Data System (ADS)

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.

González, Catalina; Dupont, Lydie M.

2009-05-01

66

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

SciTech Connect

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.

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

1990-09-01

67

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

PubMed Central

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?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

Lovell, Charles R.; Davis, Debra A.

2012-01-01

68

Effect of light intensity upon salt marsh benthic microalgal photosynthesis  

Microsoft Academic Search

The rate of photosynthesis was measured in the field with in-situ populations of benthic microalgae during both summer and winter in three distinct areas of the salt marshes adjacent to Sapelo Island, Georgia, USA. In the vegetated portions of the marsh, maximum rates of photosynthesis occurred at light intensities higher than the average light intensities beneath the canopy. In the

D. E. Whitney; W. M. Darley

1983-01-01

69

Proximate nutritive value changes during decomposition of salt marsh plants  

Microsoft Academic Search

Recognition of salt marsh plant detritus as a nutritious source of food for estuarine consumers prompted investigation of in situ decomposition and proximate nutritive values of three plants and their detritus namely: Spartina cynosuroides and Distichlis spicata (Gramineae) and Scirpus americanus (Cyperaceae) growing abundantly in Mississippi tidal marshes. During decomposition to particulate detritus, these plants retain 60–70% organic content and

Armando A. Cruz

1975-01-01

70

The impact of grazing on plant communities, plant populations and soil conditions on salt marshes  

Microsoft Academic Search

Grazing an abandoned salt marsh causes retrogressive succession, since mid salt-marsh communities change into lower salt-marsh communities. Grazing and mowing are compared in detail. Both management practices enhance species diversity in an abandoned salt marsh. This can be attributed to the removal of litter. The finding that lower salt-marsh species appear more with grazing than with mowing or abandoning is

J. P. Bakker

1985-01-01

71

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

USGS Publications Warehouse

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.

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

2013-01-01

72

Effects of crab burrows on pore water flows in salt marshes  

NASA Astrophysics Data System (ADS)

Macro-pores such as crab burrows are found commonly distributed in salt marsh sediments. Their disturbance on the soil structure is likely to influence both pore water flows and solute transport in salt marshes; however, the effects of crab burrows are not well understood. Here, a three-dimensional model simulated tidally driven pore water flows subject to the influence of crab burrows in a marsh system. The model, based on Richards' equation, considered variably saturated flow in the marsh with a two-layer soil configuration, as observed at the Chongming Dongtan wetland (Shanghai, China). The simulation results showed that crab burrows distributed in the upper low-permeability soil layer, acting as preferential flow paths, affected pore water flows in the marsh particularly when the contrast of hydraulic conductivity between the lower high-permeability soil layer and the overlying low-permeability soils was high. The burrows were found to increase the volume of tidally driven water exchange between the marsh soil and the tidal creek. The simulations also showed improvement of soil aeration conditions in the presence of crab burrows. These effects may lead to increased productivity of the marsh ecosystem and enhancement of its material exchange with coastal waters.

Xin, Pei; Jin, Guangqiu; Li, Ling; Barry, D. A.

2009-03-01

73

Salt marshes along the coast of The Netherlands  

Microsoft Academic Search

The area of salt marshes does no longer increase. The recent erosion coincides with a rise in MHT-level in the last 25 years.\\u000a Despite the decrease in area, sedimentation continues, especially in the lower salt marsh, which acts as a sink of nitrogen.\\u000a Assimilation and mineralization of nitrogen are in balance in most plant communities along the gradient from lower

J. P. Bakker; J. de Leeuw; K. S. Dijkema; P. C. Leendertse; H. H. T. Prins; J. J. Rozema

1993-01-01

74

Effects of global climate change on coastal salt marshes  

Microsoft Academic Search

A methodology combining ecological modelling with geographical information analysis and remote sensing was employed to determine the effects of sea-level rise in estuarine salt marshes, using the Tagus estuary (Portugal) as a case study. The development of salt marsh vegetation was simulated separately for C3 and C4 plants, using a combined biogeochemical and demographic model. This simulation, which provided small-scale

T. Simas; J. P. Nunes; J. G. Ferreira

2001-01-01

75

Vesicular-arbuscular mycorrhizae in salt marshes in North Carolina  

Microsoft Academic Search

The primary objective of this research was to determine if vesicular-arbuscular (VA) mycorrhizal fungi are associated with\\u000a the roots of common plant species found in North Carolina salt marshes. Root samples of Spartina alterniflora, S. patents, S. cynosuroides, Distichlis spicata, and Juncus roemerianus were collected from eight salt marsh sites. With the exception of S. alterniflora, all plant species were

Marielle H. Hoefnagels; Stephen W. Broome; Steven R. Shafer

1993-01-01

76

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

PubMed Central

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

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

77

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

PubMed

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

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

78

The influence of tidal channels on the distribution of salt marsh plant species in Petaluma Marsh, CA, USA  

Microsoft Academic Search

Tidal channels influence the distribution and composition of salt marsh vegetation in a San Francisco Bay salt marsh. Two channel networks in the Petaluma Marsh, Sonoma County, CA, were mapped and characterized using global positioning and geographic information systems. Plant species abundance was sampled on transects placed perpendicular to and extending away from the channel banks. The vegetation showed significant

Eric W. Sanderson; Susan L. Ustin; Theodore C. Foin

2000-01-01

79

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

NASA Astrophysics Data System (ADS)

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.

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

2011-08-01

80

Living foraminifera and total populations in salt marsh peat cores: Kelsey Marsh (Clinton, CT) and the Great Marshes (Barnstable, MA)  

Microsoft Academic Search

Common species of intertidal agglutinated benthic foraminifera in salt marshes in Massachusetts and Connecticut live predominantly at the marsh surface and in the topmost sediment (0–2.5 cm), but a considerable part of the fauna lives at depths of 2.5–15 cm. Few specimens are alive at depths of 15–25 cm, with rare individuals alive between 25–50 cm in the sediments. Specimens

H. Saffert; E. Thomas

1998-01-01

81

Salt marshes: An important coastal sink for dissolved uranium  

SciTech Connect

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.

Church, T.M.; Sarin, M.M.; Fleisher, M.Q.; Ferdelman, T.G. [Univ. of Delaware, Newark, DE (United States)] [Univ. of Delaware, Newark, DE (United States)

1996-10-01

82

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

USGS Publications Warehouse

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.

Dudley, Robert W.; Nielsen, Martha G.

2011-01-01

83

Effects of nitrogen addition and salt grass ( Distichlis spicata ) upon high salt marsh vegetation in Northern California, USA  

Microsoft Academic Search

In the salt marshes of Tomales Bay, California, where grazing by cattle increases the input of nitrogen to the marsh (either\\u000a directly or indirectly as runoff from within the salt marsh watershed), high salt marsh vegetation is dominated byDistichlis spicata and is less diverse than marshes without excess nutrients. Using a field experiment, I investigated the role of soil fertility

BIBIT HALLIDAY TRAU' T

2005-01-01

84

Salt stress limitation of seedling recruitment in a salt marsh plant community  

Microsoft Academic Search

Seedling recruitment in salt marsh plant communities is generally precluded in dense vegetation by competition from adults, but is also relatively rare in disturbance-generated bare space. We examined the constraints on seedling recruitment in New England salt marsh bare patches. Under typical bare patch conditions seed germination is severely limited by high substrate salinities. We examined the germination requirements of

Scott W. Shumway; Mark D. Bertness

1992-01-01

85

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

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

86

Herbivory Drives the Spread of Salt Marsh Die-Off  

PubMed Central

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

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

2014-01-01

87

Herbivory drives the spread of salt marsh die-off.  

PubMed

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

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

2014-01-01

88

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

NASA Astrophysics Data System (ADS)

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.

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

2010-10-01

89

Methanogenesis and microbial lipid synthesis in anoxic salt marsh sediments  

Microsoft Academic Search

In anoxic salt marsh sediments of Sapelo Island, GA, USA, the vertical distribution of CH4 production was measured in the upper 20 cm of surface sediments in ten locations. In one section of high marsh sediments,\\u000a the concentration and oxidation of acetate in sediment porewaters and the rate and amount of14C acetate and14CO2 incorporation into cellular lipids of the microbial

H. Rodger Harvey; Robert D. Fallon; John S. Patton

1989-01-01

90

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

USGS Publications Warehouse

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.

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

2010-01-01

91

Does vegetation prevent wave erosion of salt marsh edges?  

PubMed Central

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

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

2009-01-01

92

Does vegetation prevent wave erosion of salt marsh edges?  

PubMed

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

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

2009-06-23

93

The role of denitrification in the nitrogen cycle of New England salt marshes  

E-print Network

I used direct measurements of nitrogen gas (N? fluxes and a ¹?N stable isotope tracer to determine the contribution of denitrification to salt marsh sediment N cycling. Denitrification in salt marsh tidal creekbottoms is ...

Hamersley, Michael Robert

2002-01-01

94

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...

95

Salt marshes: An important coastal sink for dissolved uranium  

NASA Astrophysics Data System (ADS)

The global budget for marine uranium demands another geochemical sink other than deep-sea systems, and the coastal environment may host some or all of this missing sink. In a previous paper ( Sarin and Church, 1994), we have shown that some large subtidal estuaries are seasonal summer sinks at low salinities. In this paper, we show that intertidal salt marshes are even stronger sinks at all salinities, if for somewhat different reasons. Uranium was sampled in dissolved and particulate fractions over several tidal cycles and seasons for a lower Delaware Bay salt marsh (Canary Creek, Lewes, Delaware, USA), and uniquely, during summer months, the dissolved uranium is nonconservative. Moreover, because uranium extraction is greater on higher tides and occurs over the entire salinity gradient, this processing appears associated with surface of vegetated high marsh. We hypothesize that either (1) uranium scavenging occurs during the process of tidal mixing and attendant flocculation of humic acids and iron oxides—favoring this process is the presence of sulfonate complexes in salt marsh humic substances, and iron coprecipitation during its extensive redox cycling in the salt marsh—or (2) uranium extraction occurs at the marsh surface during extensive flooding of the salt marsh surface sediments—favoring this process is the increase in sulfuric acidity at the summer salt marsh surface that could destabilize the tetracarbonate species of U(VI). The latter option is favored by both field observations of maximum removal at the surface during the spring and summer tide conditions, and selective extraction of sediment phases where uranium is found as adsorbed and complexed forms in the ascorbate-citrate and humic acid fractions, respectively. Mass balance calculations show that under steady-state conditions, nearly two-thirds of the uranium extracted from tidal waters is retained in the sediments, while one-third is exported as U-enriched particles during ebbing tides. Independent confirmation of this balance comes from the measured accumulation rate of uranium buried at depth. This represents the net inventory buried below the geochemically reactive surface responsible for the initial extraction and redistribution of uranium onto sediment or tidally exported phases. Extrapolated globally, uranium burial in salt marshes alone or total marine wetlands including mangroves could comprise at least 10% and perhaps as much as 50% the total marine sink for uranium, or on an area specific basis, up to 50 times their marine areal extent.

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

1996-10-01

96

Spatial variability of phosphorus sorption dynamics in Louisiana salt marshes  

NASA Astrophysics Data System (ADS)

(P) biogeochemistry has been studied in multiple wetland ecosystems, though few data exist on P sorption in U.S. Gulf Coast marshes. There also is a limited understanding of how oil spills in coastal zones can influence P dynamics in wetland soils. In this study, we measured P sorption potential, using the P sorption index (PSI), soil properties, and P saturation at increasing distances from the marsh edge in oiled and unoiled marshes in three regions along the southeastern Louisiana coast (Terrebonne Bay, western, and eastern Barataria Bay). Individual PSI values were highly variable, ranging from 19.5 to 175.6 mg P 100 g-1 and varying by at least a factor of five within each of the three regions, and did not significantly differ between regions or between oiled and unoiled marshes. Soil pH, organic matter, total N, N:P ratio, moisture content, cation exchange capacity, and P saturation differed between regions, and all soil parameters showed great variability between and within individual marshes. Extractable iron was the strongest predictor of PSI across all regions, explaining between 51 and 95% of the variability in individual regions. PSI increased with distance from marsh edge in Terrebonne Bay where other soil properties exhibited similar trends. Results suggest mineral composition of marsh soils, influenced by elevation-inundation gradients, are critical in dictating P loading to estuaries and open waters, and overall marsh functioning. Further, within 2 years of the Deepwater Horizon oil spill, oiled marshes are able to sorb phosphorus at comparable levels as unoiled marshes.

Marton, John M.; Roberts, Brian J.

2014-03-01

97

MARSH LAKE, APPLETON, MINNESOTA ECOSYSTEM RESTORATION PROJECT  

E-print Network

of the Lac qui Parle reservoir, a previously constructed USACE reservoir system on the Minnesota River. The project includes modifications to the existing dam and other project structures, rerouting of the Pomme de-Federal sponsor. Construction of the Marsh Lake Dam initially began in the late 1930's by the State of Minnesota

US Army Corps of Engineers

98

Size and structure of a South Carolina salt marsh avian community  

Microsoft Academic Search

Although birds are a conspicuous element in estuarine ecosystems, annual fluctuations in the size and structure of avian salt\\u000a marsh communities have not been studied extensively. From October 1978 through October 1980, we censused an avian community\\u000a inhabiting a 3000-hectare estuary in SC using 4 censusing techniques: bi-monthly aerial surveys, airboat surveys, ground counts\\u000a at communal roosts, and almost daily

Keith L. Bildstein; Roberta Christy; Patricia DeCoursey I

1982-01-01

99

Mangrove expansion and salt marsh decline at mangrove poleward limits.  

PubMed

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

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

2014-01-01

100

Remote sensing of biomass of salt marsh vegetation in France  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

101

Abstract We explored the generality of the processes mediating shrub zonation in western Atlantic salt marsh-  

E-print Network

salt marsh- es by comparing the results of our experiments in Geor- gia, USA with previous studies from salt marshes. Within the shrub zone, physical stress increased at lower elevations, shrubs at lower gerardi in Rhode Island salt marshes. However, markedly different processes appear to occur further

Pennings, Steven C.

102

Nekton of New Seagrass Habitats Colonizing a Subsided Salt Marsh in Galveston Bay, Texas  

E-print Network

Delwood Beach Road, Panama City, Florida 32408 ABSTRACT: Subsidence and erosion of intertidal salt marshNekton of New Seagrass Habitats Colonizing a Subsided Salt Marsh in Galveston Bay, Texas SETH P species and their forage. Salt marshes and seagrasses are particularly important in main- taining

103

ASSESSING HABITAT SELECTION BY FORAGING EGRETS IN SALT MARSHES AT MULTIPLE SPATIAL SCALES  

Microsoft Academic Search

We assessed salt marsh use by foraging egrets in coastal Rhode Island, USA. Two species (great egret (Ardea alba) and snowy egret (Egretta thula)) nest in mixed-species colonies on islands in Narragansett Bay and regularly forage in adjacent salt marshes. We surveyed 13 salt marshes approximately twice weekly during the breeding and post-breeding seasons in 2001 and 2002. Based on

Carol Lynn Trocki; Peter W. C. Paton

2006-01-01

104

Habitat selection of wintering passerines in salt marshes of the German Wadden Sea  

Microsoft Academic Search

The salt marshes of the Wadden Sea are important wintering areas for some species of granivorous passerines, which have declined considerably since the 1960s. We investigated the habitat choice of all wintering passerines in eight study areas in German salt marshes with special consideration of human impact on these habitats. Granivorous species that almost exclusively winter in salt marshes, Shorelark

Jochen Dierschke; Franz Bairlein

2004-01-01

105

Microclimate and substrate quality controls on nitrogen mineralization in a New England high salt marsh  

Microsoft Academic Search

New England high salt marsh primary productivity is limited by N, but variation in plant N availability across salt marsh vegetation zones has not been quantified. To investigate this, we measured in situ net N mineralization rates throughout the growing season in three zones of a Maine high salt marsh, Juncus gerardii, Spartina patens, and mixed perennial forb. We also

Theresa A. Theodose; Janette Martin

2003-01-01

106

Distribution and salinity tolerance of intertidal mosses from Nova Scotian salt marshes  

Microsoft Academic Search

Five moss species were found in the high intertidal zone of salt marshes in Nova Scotia, eastern Canada. This is the first report of bryophytes from salt marshes from North America. In each of the salt marshes where mosses occurred, one to three moss species occurred in monospecific or mixed species assemblages. Campylium stellatum and Bryum capillare were the most

David J. Garbary; Anthony G. Miller; Ricardo Scrosati; Kwang-Young Kim; Wilfred B. Schofield

2008-01-01

107

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...

108

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...

109

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

USGS Publications Warehouse

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.

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

2009-01-01

110

Created versus natural wetlands: Avian communities in Virginia salt marshes  

Microsoft Academic Search

Permits to destroy wetlands often require the creation of the same type of wetland elsewhere. An assumption underlying this practice is that such created wetlands will replace the ecological functions lost when the developed wetland was destroyed. Part of this ecological function is providing habitat for wildlife, including, in coastal areas, a suite of bird species tied to salt marshes

David W. Desrochers; Jason C. Keagy; Daniel A. Cristol

2008-01-01

111

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

Microsoft Academic Search

The rate of accretion on coastal salt marshes depends on feedbacks between flow, macrophyte growth, and sedimentation. Under favourable conditions, marsh accretion rates will keep pace with the local rate of sea level rise. Marsh accretion is driven by both organic and inorganic sedimentation; mineral rich marshes will need less organic sedimentation to keep pace with sea level rise. Here

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

2009-01-01

112

Flood tolerance and the distribution of Iva frutescens across New England salt marshes  

Microsoft Academic Search

Tidal flooding is widely believed to be an important determinant of marsh plant distributions but has rarely been tested in the field. In New England the marsh elder Iva frutescens often dominates the terrestrial border of salt marshes and we examined its flood tolerance and distribution patterns. Marsh elders only occur at elevations where their roots are not subject to

Mark D. Bertness; Karen Wikler; Tom Chatkupt

1992-01-01

113

Heat budget for a shallow, sinuous salt marsh estuary  

NASA Astrophysics Data System (ADS)

An experimental study of temperature cycles and the heat budget in the Duplin River, a tidal creek bordered by extensive intertidal salt marshes, was carried out in late summer of 2003 and spring of 2004 near Sapelo Island on the central Georgia coast in the southeastern US. Three water masses are identified with differing temperature and salinity regimes, the characteristics of which are dictated by channel morphology, tidal communication with the neighboring sound, ground water hydrology, the extent of local intertidal salt marshes and side channels and the spring-neap tidal cycle (which controls both energetic mixing and, presumably, ground water input). For the first experiment, heat budgets are constructed for the upper (warmer) and lower (cooler) areas of the Duplin River showing the diminishing importance of tidal advection away from the mouth of the creek along with the concomitant increase in the importance of both direct atmospheric fluxes and of interactions with the marsh and side creeks. The second experiment, in the spring of 2004, reexamines the heat budget on seasonal and daily averaged scales revealing the decreased importance of advective fluxes relative to direct atmospheric fluxes on this scale but the constant importance of marsh/creek interactions regardless of time scale or season. Short period temperature fluctuations which affect larval development are examined and analogies are drawn to use heat to understand the marsh as a source of sediment, carbon and other nutrients.

McKay, Paul; Iorio, Daniela Di

2008-08-01

114

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...

115

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

PubMed

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

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

2007-06-01

116

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...

117

Relationships between sedimentation, plant species, and the proximity to tidal channels in coastal salt marshes  

Microsoft Academic Search

Deposition of sediment on vegetated salt marshes enables these marshes to maintain their elevation relative to rising sea level. It has been found that deposition rates of suspended sediment on vegetated salt marshes are highest near tidal channels. This is due to the reduction in turbulence as flows from the tidal channel encounter the stems of the macrophytes that live

S. M. Mudd; S. M. Howell; D. J. Furbish; J. T. Morris

2006-01-01

118

The ebb and flood of Silica: Quantifying dissolved and biogenic silica fluxes from a temperate salt marsh  

NASA Astrophysics Data System (ADS)

Salt marshes are widely studied due to the broad range of ecosystem services they provide including serving as crucial wildlife habitat and as hotspots for biogeochemical cycling. Nutrients such as nitrogen (N), phosphorus (P), and carbon (C) are well studied in these systems. However, salt marshes may also be important environments for the cycling of another key nutrient, silica (Si). Found at the land-sea interface, these systems are silica replete with large stocks in plant biomass, sediments, and porewater, and therefore, have the potential to play a substantial role in the transformation and export of silica to coastal waters. In an effort to better understand this role, we measured the fluxes of dissolved (DSi) and biogenic (BSi) silica into and out of two tidal creeks in a temperate, North American (Rowley, Massachusetts, USA) salt marsh. One of the creeks has been fertilized from May to September for six years allowing us to examine the impacts of nutrient addition on silica dynamics within the marsh. High-resolution sampling in July 2010 showed no significant differences in Si concentrations between the fertilized and reference creeks with dissolved silica ranging from 0.5 to 108 ?M and biogenic from 2.0 to 56 ?M. Net fluxes indicated that the marsh is a point source of dissolved silica to the estuary in the summer with a net flux of approximately 169 mol h -1, demonstrating that this system exports DSi on the same magnitude as some nearby, mid-sized rivers. If these findings hold true for all salt marshes, then these already valuable regions are contributing yet another ecosystem service that has been previously overlooked; by exporting DSi to coastal receiving waters, salt marshes are actively providing this important nutrient for coastal primary productivity.

Vieillard, Amanda M.; Fulweiler, Robinson W.; Hughes, Zoe J.; Carey, Joanna C.

2011-12-01

119

Marsh Collapse Does Not Require Sea Level Rise  

E-print Network

Salt marshes are among the most productive ecosystems on Earth, providing nurseries for fish species and shelter and food for endangered birds. Salt marshes also mitigate the impacts of hurricanes and tsunamis, and sequester ...

Fagherazzi, Sergio

120

Salt Marsh Formation in the Lower Hudson River Estuary  

NASA Technical Reports Server (NTRS)

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-resolution studies of these marshes to understand the fluctuations in salinity caused by relative sea level rise, tectonic faulting and/or changes in precipitation/evaporation.

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

2001-01-01

121

Gross nitrous oxide production and consumption along a salt marsh redox gradient  

NASA Astrophysics Data System (ADS)

Coastal wetlands denitrify nitrate (NO3-)-rich urban and agricultural runoff, and thus decrease anthropogenic nitrogen loading on downslope aquatic ecosystems. Elevation gradients in coastal wetlands likely create redox gradients that result in a range of denitrification dynamics. Our objective was to determine if this redox gradient could elucidate the controls on nitrous oxide (N2O) production and consumption in a salt marsh bordering Tomales Bay, CA. We installed soil equilibration chambers to measure soil oxygen (O2) at 10 cm depth along a transect in each of three marsh zones: high, mid, and low (n=4 per zone). We used the stable isotope trace gas pool dilution technique to measure gross rates of N2O production and consumption over three hour sampling periods at low tide when the surface soils were not saturated. Intact soil cores (0-10 cm depth) taken from the flux chamber footprints were extracted for ammonium, NO3-, and ferric and ferrous iron (Fe(III) and Fe(II)) concentrations as well as assayed for denitrifying enzyme activity (DEA). We sampled on four dates to characterize N2O dynamics across a range of environmental conditions. Bulk soil O2 concentrations in the soil equilibration chambers were higher in the high marsh than in the mid and low marshes (p<0.001, n=44). Soil NO3- concentrations were significantly lower and HCl-extractable Fe(II) concentrations were significantly higher in the low marsh compared to the high and mid marshes (NO3- p<0.001, Fe(II) p<0.001, n=44). Despite differences in redox among the marsh zones, neither gross rates of N2O production (Figure 1a) nor consumption (Figure 1b) varied significantly among the zones. DEA also did not differ among marsh zones, with averages ranging from 136 ± 30 ng-N g-1 h-1 in the mid marsh to 550 ± 121 ng-N g-1 h-1 in the low marsh. Overall, this salt marsh was neither an N2O source nor sink, with net N2O fluxes averaging 51 ± 40 ?g-N m-2 d-1 across all marsh zones and sampling dates. However, net N2O fluxes were negative in 29 out of 44 measurements. Sub-atmospheric soil N2O concentrations at 10 cm depth together with the quantification of significant gross N2O consumption rates suggest that the net uptake of atmospheric N2O by the soil occurred in all marsh zones. Boxplots of (1) gross N2O production rates and (2) gross N2O consumption rates along a salt marsh elevation gradient. The y-axes are shown on log10 scale.

Yang, W. H.; Silver, W. L.

2012-12-01

122

Oil bioremediation in salt marsh mesocosms as influenced by nitrogen, phosphorus, and bacterial seeding  

E-print Network

Glasshouse experiments were conducted to determine the effects of N and P fertilization and bacterial seeding on crude oil degradation in salt marsh mesocosms containing marsh soil and Spartina alterniflora. Fertilization with urea, NH4, and N03...

Wright, Alan Lee

2012-06-07

123

Spatial variations of carbon, nitrogen, phosphorous and sulfur in the salt marsh sediments of the Yangtze Estuary in China  

NASA Astrophysics Data System (ADS)

Surface sediments and three sediment vibrocores were collected from the salt marsh of the Yangtze Estuary in order to examine the C, N, P and S distributions. Marsh plants and suspended particulate matter (SPM) from the river were also sampled and analyzed in order to determine their elemental compositions. The levels of total organic carbon (0.1-0.7%) and C/N ratios (6-11) in the surface sediments of the Yangtze Estuary salt marsh were relatively low compared with those reported for other salt marshes in European and North American coastal areas. The total organic carbon (TOC) level and C/N ratio of the surface sediments were similar to those of the SPM in the Yangtze Estuary, but were much lower than those of the marsh plant samples. These findings support the view that organic matter in the surface sediments is largely derived from SPM in the river, with minor contributions from the marsh vegetation. Total phosphorus (TP) showed irregular variation in its spatial distribution, whereas the TOC, total nitrogen (TN) and total sulfur (TS) concentrations were highest in the high marsh zones and lowest in the bare flat areas. This pattern was related to the spatial variability of the sediment grain size (i.e. clay-rich sediments in the high marsh zones resulted in elevated TOC, TN and TS contents). Some vibrocore sediments in the mid-depths of the high and low marsh zones, however, showed greater TOC contents than might have been predicted from the TOC-grain size relationship. This suggested the existence of additional organic inputs (i.e. marsh vegetation) for these vibrocore sediment sections, despite their original riverine source. After eliminating the effect of grain size, it was calculated that 22-55% of the TOC and 0.6-35% of the TN in the sediment samples were derived from the marsh vegetation. Considering both the vertical accretion rate and the ecosystem evolution of the salt marsh, it was estimated that the annual contributions of TOC and TN made by the marsh vegetation to the sediments in the Yangtze Estuary were 5.8 × 10 11 g C yr -1 and 2.3 × 10 10 g N yr -1, respectively, with corresponding accumulation rates of 1.1-1.5 × 10 10 g C yr -1 and 4.4-5.8 × 10 8 g N yr -1 at the present time.

Zhou, Junli; Wu, Ying; Kang, Qinshu; Zhang, Jing

2007-01-01

124

Identification of metrics to monitor salt marsh integrity on National Wildlife Refuges in relation to conservation and management objectives  

USGS Publications Warehouse

Most salt marshes in the US have been degraded by human activities, and threats from physical alterations, surrounding land-use, species invasions, and global climate change persist. Salt marshes are unique and highly productive ecosystems with high intrinsic value to wildlife, and many National Wildlife Refuges (NWRs) have been established in coastal areas to protect large tracts of salt marsh and wetland-dependent species. Various management practices are employed routinely on coastal NWRs to restore and enhance marsh integrity and ensure ecosystem sustainability. Prioritizing NWR salt marshes for application of management actions and choosing among multiple management options requires scientifically-based methods for assessing marsh condition. Monitoring is integral to structured decision-making (SDM), a formal process for decomposing a decision into its essential elements. Within a natural resource context, SDM involves identifying management objectives, alternative management actions, and expected management outcomes. The core of SDM is a set of criteria for measuring system performance and evaluating management responses. Therefore, use of SDM to frame natural resource decisions leads to logical selection of monitoring attributes that are linked explicitly to management needs. We used SDM to guide selection of variables for monitoring the ecological integrity of salt marshes within the National Wildlife Refuge System (NWRS). Our objectives were to identify indicators of salt marsh integrity that are effective across large geographic regions, responsive to a wide range of threats, and feasible to implement within funding and staffing constraints of the NWRS. In April, 2008, we engaged interdisciplinary experts in a week-long rapid prototyping SDM workshop to define the essential elements of salt marsh management decisions on refuges throughout the northeastern, southwestern, and northwestern US, corresponding to respective Regions 5, 2, and 1 of the US Fish and Wildlife Service (FWS). Through this process we identified measurable attributes for monitoring salt marsh ecosystems that are integrated into conservation practice and target management objectives. The following salt marsh attributes were identified through the SDM process either for describing state condition to determine management needs or for evaluating the achievement of management objectives: historical condition and geomorphic setting; ditch density; surrounding land use; ratio of open water area to vegetation area; rate of pesticide application; environmental contaminant concentration; change in marsh surface elevation relative to sea level rise; tidal range and groundwater level; surface topography; salinity; and species composition and abundance of vegetation, invasive species, invertebrates, nekton, and breeding and wintering birds. The identified attributes were too broadly defined to serve as operational monitoring variables. Therefore, we tested specific metrics for quantifying most of these attributes in summers of 2008 and 2009. The first four attributes in the above list can be characterized by office-based analysis of existing GIS data layers. The remaining attributes require field-based methods for assessment. We were forced to exclude a small number of attributes from field tests due to inconsistent data (pesticide application rate, environmental contaminant concentrations) or requirements that exceeded the scope of this project (change in marsh surface elevation; surface topography; benthic invertebrates; wintering birds). We evaluated potential metrics for evaluating all remaining field attributes. In partnership with NWRS biologists, we tested rapid versus intensive metrics for monitoring field attributes (tidal range and groundwater level; marsh surface elevation; salinity; and species composition and abundance of vegetation, invasive species, nekton, and breeding birds) at coastal refuges throughout FWS Region 5. Seven refuges participated in metric testing in 2008: Rachel Carson (ME), Parker River (MA), Wertheim (NY), E. B. Forsythe

Neckles, Hilary A.; Guntenspergen, Glenn R.; Shriver, W. George; Danz, Nicholas P.; Wiest, Whitney A.; Nagel, Jessica L.; Olker, Jennifer H.

2013-01-01

125

White Phosphorus Poisoning of Waterfowl in an Alaskan Salt Marsh  

Microsoft Academic Search

The cause of the yearly death of an estimated 1,000 to 2,000 migrating dabbling ducks (Anas spp.) and 10 to 50 swans (Cygnus buccinator and C. columbianus) has remained a mystery for the last ten years in Eagle River Flats (ERF), a 1,000 ha estuarine salt marsh near Anchorage, Alaska, used for artillery training by the U.S. Army. We have

Charles H. Racine; Marianne E. Walsh; Bill D. Roebuck; Charles M. Collins; Darryl Calkins

126

Comparative Phylogeography of North American Atlantic Salt Marsh Communities  

Microsoft Academic Search

Identifying differential population structure within metacommunities is key toward describing the mechanisms that maintain\\u000a biodiversity in natural systems. At both local and regional scales on the North American Atlantic coast, we assessed phylogeographic\\u000a and genetic diversity patterns of six common salt marsh invertebrates using equivalent sampling schemes and sequence data\\u000a from the same mitochondrial locus. In general, our results suggest

Edgardo Díaz-Ferguson; John D. Robinson; Brian Silliman; John P. Wares

2010-01-01

127

Salt-marsh vegetation in the Shetland Islands  

Microsoft Academic Search

Details are given of a preliminary study of salt marshes near Sullom Voe, Mainland, Shetland, using 50×50 cm quadrats placed systematically along transects. Computer-generated clusters are shown to match well against generally accepted syntaxa, whilst high-similarity clusters in certain alliances possess internal structure related to dominance and to effects of freshwater irrigation. The syntaxa provisionally identified are the Eleocharion uniglumis,

D. H. Dalby

1985-01-01

128

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

ERIC Educational Resources Information Center

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

Brevard County School Board, Cocoa, FL.

129

Dual role of salt marsh retreat: Long-term loss and short-term resilience  

NASA Astrophysics Data System (ADS)

major causes of salt marsh loss are vertical drowning, when sediment accumulation on the platform cannot keep vertical pace with sea level rise, and horizontal retreat, associated with wave-induced marsh boundary erosion. Despite these processes having been extensively documented and modeled, it is unclear which loss modality dominates given a set of environmental parameters. A three-point dynamic model was developed to predict marsh loss as a function of sea level rise, allochthonous sediment supply, wind regime, tidal range, and marsh bank and mudflat erodability. Marsh horizontal and vertical evolutions were found to respond in opposing ways to wave-induced erosion processes. Marsh horizontal retreat was triggered by large mudflats, strong winds, high erodability of marsh bank and mudflat, whereas the opposite conditions acted to reduce the sediment supply to the marsh platform, promoting marsh loss to drowning. With low and moderate rates of sea level rise (˜5 mm/yr), retreat was found to be a more likely marsh loss modality than drowning. However, conditions associated with marsh retreat also increase the system resilience by transferring sediment on the marsh platform and preventing drowning. Our results suggest the use of a modular strategy for short-term marsh management: selectively protect extensive salt marsh regions by maintaining healthy vegetation on the platform, while allowing other areas to retreat, leveraging the natural resilience embedded in the lateral loss of marsh extent.

Mariotti, G.; Carr, J.

2014-04-01

130

Sulfate reduction in the salt marshes at Sapelo Island, Georgia  

SciTech Connect

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.

Howarth, R.W. (Ecosystems Center, Woods Hole, MA); Giblin, A.

1983-01-01

131

Salt marsh hydrology data web site facilitates research  

NASA Astrophysics Data System (ADS)

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).

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

132

Habitat Development Field Investigations, Salt Pond Number 3 Marsh Development Site, South San Francisco Bay, California; Summary Report.  

National Technical Information Service (NTIS)

A study of marsh development on confined dredged material substrate in an abandoned salt pond in South San Francisco Bay demonstrated that a California cordgrass (Spartina foliosa) marsh can be established within 2 years. For successful marsh development,...

J. H. Morris, C. L. Newcombe, R. T. Huffman, J. S. Wilson

1978-01-01

133

Evaluation of white plastic flags as visual repellents for Snow Geese on coastal salt marshes  

Microsoft Academic Search

Excessive grazing by Snow Geese (Chen caerulescens) causes severe damage to salt marshes along the eastern seaboard of the United States and to traditional agricultural practices such as salt hay farming. The effectiveness of white plastic flags as visual repellents to Snow Geese (Chen caerulescens) on six Delaware Bay salt hay (Spartina sp.) marshes was evaluated. At each site, two

J. Russell Mason

1995-01-01

134

Release of Metals by the Leaves of the Salt Marsh Grasses Spartina alterniflora and Phragmites australis  

Microsoft Academic Search

The perennial grass Spartina alterniflora, common to salt marshes of eastern North America, is known to accumulate metals from marsh sediment and release them into the environment. One pathway by which Spartina alterniflora releases metals is through the excretion of metal-containing salts produced by leaf salt glands. We examined the differential release of metals by Spartina alterniflora and the invasive

D. J. Burke; J. S. Weis; P. Weis

2000-01-01

135

The role of research in coastal westlands management: Salt Marshes of Santoña and Noja (Spain).  

PubMed

Coastal environments, such as marshes, dunes, or estuaries, are characterized by their high natural values that usually cause them to be subjected to high protection levels, affecting activities taking place within them. This is why the action in these spaces must be based on the use of proper techniques and approaches, which integrate ecology with practical engineering necessities. In this context, the Department of Sciences and Techniques of the Water and Environment of the University of Cantabria, through methods developed in the natural reserve of the Salt Marshes of Santoña and Noja, proposes the use of a working methodology based on the discipline of "ecosystem management" combined with the "adaptive management" methodologies; the application of mathematical, statistical, and specific predictive instruments; and the utilization of an "ecologic niche" as a union between the scientific knowledge of the littoral environments and the true actuation scale of the projects and activities carried out within them. PMID:21400243

Castillo-Lopez, Elena; Valle, Alberto

2012-01-01

136

Assessing habitat selection by foraging egrets in salt marshes at multiple spatial scales  

Microsoft Academic Search

We assessed salt marsh use by foraging egrets in coastal Rhode Island, USA. Two species [great egret (Ardea alba) and snowy egret (Egretta thula)] nest in mixed-species colonies on islands in Narragansett Bay and regularly forage in adjacent salt marshes. We surveyed\\u000a 13 salt marshes approximately twice weekly during the breeding and post-breeding seasons in 2001 and 2002. Based on

Carol Lynn Trocki; Peter W. C. Paton

2006-01-01

137

Pyrite accumulation in salt marshes in the Eastern Scheldt, southwest Netherlands  

Microsoft Academic Search

Pore water composition, pyrite distribution and pyrite crystal morphology of sediments from salt marshes in the Eastern Scheldt, southwestern Netherlands, were examined from July 1984 to October 1986.

Oene Oenema

1990-01-01

138

Long-term Surface Elevation Change in Salt Marshes: a Prediction of Marsh Response to Future Sea-Level Rise  

NASA Astrophysics Data System (ADS)

Accretion rates and surface elevation changes were measured in three natural salt marshes in the Wadden Sea. Derived from these measurements, a simple predictive model was made which describes changes in surface elevation during more than 100 years of salt-marsh development at several sea-level rise scenarios. The model was tested with data on long-term surface elevation changes at several successional stages in the salt marsh of Schiermonnikoog (The Netherlands), where sites differ in age from a few years to more than 100 years. The model predicts in all scenarios a fast increase in surface elevation during the first 100 years of marsh development. Results showed a very high similarity between the prediction of the model and field-data. A scenario without sea-level rise revealed a stabilization of surface elevation and inundation frequency after approximately 100 years. In a scenario with a rise in mean sea-level, however, marsh surface elevation continues to increase after 100 years, although at a slower pace. Previous studies expected marsh surface elevation on coastal barrier marshes to keep pace with sea-level rise, if sea-level rise was lower than 5 mm yr -1. We found that inundation frequency starts to increase after 100 years of marsh development, even if sea-level rise is lower than 5 mm yr -1. Shrinkage of the clay layer during summer probably caused an elevation deficit in older marshes. This means that in the long run (more than 500 years) marshes will probably degenerate on these islands, especially at a low elevation. New marshes may develop at sites with a higher elevation, if these sites are available.

van Wijnen, H. J.; Bakker, J. P.

2001-03-01

139

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

PubMed

Coastal salt marshes are among Earth's most productive ecosystems and provide a number of ecosystem services, including interception of watershed-derived nitrogen (N) before it reaches nearshore oceans. Nitrogen pollution and climate change are two dominant drivers of global-change impacts on ecosystems, yet their interacting effects at the land-sea interface are poorly understood. We addressed how sea-level rise and anthropogenic N additions affect the salt marsh ecosystem process of nitrogen uptake using a field-based, manipulative experiment. We crossed simulated sea-level change and ammonium-nitrate (NH(4)NO(3))-addition treatments in a fully factorial design to examine their potentially interacting effects on emergent marsh plants in a central California estuary. We measured above- and belowground biomass and tissue nutrient concentrations seasonally and found that N-addition had a significant, positive effect on a) aboveground biomass, b) plant tissue N concentrations, c) N stock sequestered in plants, and d) shoot:root ratios in summer. Relative sea-level rise did not significantly affect biomass, with the exception of the most extreme sea-level-rise simulation, in which all plants died by the summer of the second year. Although there was a strong response to N-addition treatments, salt marsh responses varied by season. Our results suggest that in our site at Coyote Marsh, Elkhorn Slough, coastal salt marsh plants serve as a robust N trap and coastal filter; this function is not saturated by high background annual N inputs from upstream agriculture. However, if the marsh is drowned by rising seas, as in our most extreme sea-level rise treatment, marsh plants will no longer provide the ecosystem service of buffering the coastal ocean from eutrophication. PMID:22879873

Nelson, Joanna L; Zavaleta, Erika S

2012-01-01

140

THE EFFECT OF DOMINANT GRASS SPECIES ON NITROGEN CYCLING IN GREAT SIPPEWISSETT SALT MARSH SEDIMENTS  

E-print Network

of the salt marsh. To do this, I studied three dominant high-marsh grass species: Phragmites australis alterniflora, S. patens, Phragmites australis, nitrogen cycling, Great Sippewissett Marsh INTRODUCTION: Phragmites australis. Phragmites is a common reed that grows in dense, often monoculture stands that achieve

Vallino, Joseph J.

141

Long-Term Retention and Loss of Heavy Metals from Experimental Salt Marsh Plots  

E-print Network

Long-Term Retention and Loss of Heavy Metals from Experimental Salt Marsh Plots Katie Harrold Middlebury College, Middlebury, VT 05753 Abstract: Following earlier studies of metal retention in Great Sippewissett Marsh I have tested the long-term retention of heavy metals by the marsh. Beginning in the early

Vallino, Joseph J.

142

Strontium 90 in Maize Field, Cattail Marsh and Oakwood Ecosystems Author(s): J. D. Ovington and D. B. Lawrence  

E-print Network

Strontium 90 in Maize Field, Cattail Marsh and Oakwood Ecosystems Author(s): J. D. Ovington and D Ecology. http://www.jstor.org #12;STRONTIUM 90 IN MAIZE FIELD, CATTAIL MARSH AND OAKWOOD ECOSYSTEMS BY J

Minnesota, University of

143

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

144

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

PubMed

Increased recognition of the global importance of salt marshes as 'blue carbon' (C) sinks has led to concern that salt marshes could release large amounts of stored C into the atmosphere (as CO2) if they continue undergoing disturbance, thereby accelerating climate change. Empirical evidence of C release following salt marsh habitat loss due to disturbance is rare, yet such information is essential for inclusion of salt marshes in greenhouse gas emission reduction and offset schemes. Here we investigated the stability of salt marsh (Spartinaalterniflora) sediment C levels following seagrass (Thallasiatestudinum) wrack accumulation; a form of disturbance common throughout the world that removes large areas of plant biomass in salt marshes. At our study site (St Joseph Bay, Florida, USA), we recorded 296 patches (7.5 ± 2.3 m(2) mean area ± SE) of vegetation loss (aged 3-12 months) in a salt marsh meadow the size of a soccer field (7 275 m(2)). Within these disturbed patches, levels of organic C in the subsurface zone (1-5 cm depth) were ~30% lower than the surrounding undisturbed meadow. Subsequent analyses showed that the decline in subsurface C levels in disturbed patches was due to loss of below-ground plant (salt marsh) biomass, which otherwise forms the main component of the long-term 'refractory' C stock. We conclude that disturbance to salt marsh habitat due to wrack accumulation can cause significant release of below-ground C; which could shift salt marshes from C sinks to C sources, depending on the intensity and scale of disturbance. This mechanism of C release is likely to increase in the future due to sea level rise; which could increase wrack production due to increasing storminess, and will facilitate delivery of wrack into salt marsh zones due to higher and more frequent inundation. PMID:23861964

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

2013-01-01

145

Ability of salt marsh plants for TBT remediation in sediments  

Microsoft Academic Search

Introduction  The capability of Halimione portulacoides, Spartina maritima, and Sarcocornia fruticosa (halophytes very commonly found in salt marshes from Mediterranean areas) for enhancing remediation of tributyltin (TBT)\\u000a from estuarine sediments was investigated, using different experimental conditions.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  The influence of H. portulacoides on degradation of the butyltin compounds was assessed in two different ways: (1) a 9-month ex situ study carried out

Pedro N. Carvalho; M. Clara P. Basto; Manuela F. G. M. Silva; Ana Machado; A. A. Bordalo; M. Teresa S. D. Vasconcelos

2010-01-01

146

Spring phytoplankton dynamics in a shallow, turbid coastal salt marsh system undergoing extreme salinity variation, South Texas  

E-print Network

in salt marshes. Across three consecutive springs (2001 to 2003), I sampled the upper Nueces Delta in south Texas, a shallow, turbid, salt marsh system stressed by low freshwater inflow and wide ranging salinity (300 ppt). Water column productivity...

Hebert, Elizabeth Michele

2005-08-29

147

Gas exchange in the salt marsh species Atriplex portulacoides L. and Limoniastrum monopetalum L. in Southern Portugal  

Microsoft Academic Search

Salt marshes are ecosystems subjected to a variety of environmental stresses like high salinity, water deficit, intense radiation\\u000a or high temperatures. Field measurements were conduced in two halophyte species, Atriplex portulacoides L. and Limoniastrum monopetalum L., in the Reserva Natural do Sapal de Castro Marim, to compare their physiological response, i.e., water potential (?),\\u000a net photosynthetic rate (A), stomatal conductance

João Pedro Correia das Neves; Luís Filipe Portugal Ferreira; Maria Margarida Vaz; Luiz Carlos Gazarini

2008-01-01

148

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

USGS Publications Warehouse

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 size of 1.0 ha. Inundation contours were mapped at 110 salt marshes. Approximately 350 ha of low-lying upland areas adjacent to these marshes will be inundated with 60 cm of sea-level rise. Many of these areas are currently freshwater wetlands. There are potential barriers to marsh migration at 27 of the 114 marshes. Although only 23 percent of the salt marshes in the study are on ANP property, about half of the upland areas that will be inundated are within ANP; most of the predicted inundated uplands (approximately 170 ha) include freshwater wetlands in the Northeast Creek and Bass Harbor Marsh areas. Most of the salt marshes analyzed do not have a significant amount of upland area available for migration. Seventy-five percent of the salt marshes have 20 meters or less of adjacent upland that would be inundated along most of their edges. All inundation contours, salt marsh locations, potential barriers, and survey data are stored in geospatial files for use in a geographic information system and are a part of this report.

Nielsen, Martha G.; Dudley, Robert W.

2013-01-01

149

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

E-print Network

of Houston, Houston, Texas, United States of America Abstract Oil spills represent a major environmental intertidal habitats such as salt marsh. Following the BP Deepwater Horizon oil spill, we sampled and Recovery of Salt Marsh Arthropod Communities following BP Deepwater Horizon Oil Spill. PLoS ONE 7(3): e

Pennings, Steven C.

150

The role of succulent halophytes in the water balance of salt marsh rodents  

Microsoft Academic Search

The role of succulent halophytes in the water balance and ecology of salt marsh rodents is dependent upon an evaluation of the composition of the available sources and the physiological properties of their potential consumers. Studies of the osmotic properties of succulent halophytes from southern California coastal salt marshes are presented, together with experiments regarding the utilization of Common Pickleweed

Harry N. Coulombe

1970-01-01

151

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

EPA Science Inventory

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

152

Wave Transformation Over Salt Marshes: A Field and Numerical Modelling Study from North Norfolk, England  

NASA Astrophysics Data System (ADS)

This paper presents quantitative evidence for the effectiveness of a meso- to macro-tidal open coast salt marsh in attenuating incoming waves over a range of tidal and meteorological conditions. Field measurements of wind waves at three locations on a sand flat to salt marsh cross-shore transect showed that wave energy dissipation rates over the salt marsh were significantly higher (at an average of 82%) than over the sand flat (at an average of 29%). The difference in water depth between the sand flat and salt marsh sections of the transect was not sufficient to account for the difference in wave attenuation, indicating that an increase in surface friction is the primary reason for increased wave attenuation over the salt marsh. Comparison of the field results with a numerical model based on theoretical wave energy dissipation suggests that surface friction factors of the order of ?0·4 are responsible for the high values of wave attenuation over the salt marsh. The results provide empirical support, both for maintaining salt marshes in front of existing sea defence lines and for creating new salt marsh as part of coastal set-back/shoreline realignment schemes.

Möller, I.; Spencer, T.; French, J. R.; Leggett, D. J.; Dixon, M.

1999-09-01

153

Effects of Nitrate on Decomposition in Salt Marsh Peats Arianna Goodman  

E-print Network

Effects of Nitrate on Decomposition in Salt Marsh Peats Arianna Goodman Oberlin College `13 Advisor and loss. Rapid nitrate addition to salt marshes may stimulate bacterial decomposition of existing peat, and the decomposition may contribute to creek bank destabilization and collapse. Alternately, peat deposited in high-nitrate

Vallino, Joseph J.

154

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...

155

Impact of sheep grazing on juvenile sea bass, Dicentrarchus labrax L., in tidal salt marshes  

E-print Network

Impact of sheep grazing on juvenile sea bass, Dicentrarchus labrax L., in tidal salt marshes P L., from sheep grazed and ungrazed tidal salt marshes were com- pared qualitatively and quantitatively in Mont Saint-Michel Bay. In areas without grazing pressure, the vegetation gradient changes from

Paris-Sud XI, Université de

156

Influence of Spartina alterniflora on the mobility of heavy metals in salt marsh sediments of the Yangtze River Estuary, China.  

PubMed

Using bio-disturbed sulphide to trace the mobility and transformation of Cu, Pb, Ni and Zn in the sediments of the Spartina alterniflora-dominated salt marsh in the Yangtze River Estuary, measurements were made of the seasonal variations of acid-volatile sulphide (AVS) and of the simultaneously extracted metals (SEM) in the rhizosphere sediments. Microcosm incubation experiments recreating flooding conditions were conducted to evaluate the effect of AVS and other metal binding phases upon the dynamics of Cu, Pb, Ni and Zn in the salt marsh sediments. The results demonstrate that the ratio values of SEM/AVS have a significant seasonal variation in the rhizosphere sediments and that the anoxic conditions in the sediments were likely enhanced by S. alterniflora during the summer and autumn compared with the anoxic conditions resulting from the native species Phragmites australis and Scirpus mariqueter. The incubation experiments suggest that Fe(III) and Mn(IV/III) (hydr)oxides provide important binding sites for heavy metals under oxic conditions, and sulphide provides important binding sites for the Cu and Pb under anoxic conditions. Our observations indicate that the mobility of heavy metals in the salt marsh sediments is strongly influenced by biogeochemical redox processes and that the invasive S. alterniflora may increase the seasonal fluctuation in heavy metal bioavailability in the salt marsh ecosystem. PMID:22821343

Wang, Yongjie; Zhou, Limin; Zheng, Xiangmin; Qian, Peng; Wu, Yonghong

2013-03-01

157

The effect of cattle grazing on the abundance and distribution of selected macroinvertebrates in west Galveston Island salt marshes  

E-print Network

of salt marsh nursery habitats could significantly decrease the annual fisheries catch. The abundant nutrient rich salt marsh habitats along the Texas Coast serve a variety of vital purposes. The dense shallow water stands of smooth cordgrass (Spartina..., adjacent to Snake Island Cove. 6 CHAPTER II VEGETATION DIFFERENCES BETWEEN GRAZED AND UNGRAZED SALT MARSH ELEVATION ZONES INTRODUCTION Texas coastal salt marshes are dominated by Spartina alterniflora (smooth cordgrass) at lower tidal...

Martin, Jennifer Lynn

2004-09-30

158

Ionic alkylleads in salt marsh periwinkles (Littorina irrorata)  

SciTech Connect

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.

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

1988-07-01

159

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

USGS Publications Warehouse

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 to those in the natural marshes, just so long as the marshes are formed at a proper elevation. This agrees with other studies from North Carolina and Texas. However, it will take several decades for the soil characteristics to reach equivalency with the natural marshes, if they ever will.

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

2003-01-01

160

Biogeochemical drivers of phosphatase activity in salt marsh sediments  

NASA Astrophysics Data System (ADS)

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.

Freitas, Joana; Duarte, Bernardo; Caçador, Isabel

2014-10-01

161

White phosphorus poisoning of waterfowl in an Alaskan salt marsh.  

PubMed

The cause of the yearly death of an estimated 1,000 to 2,000 migrating dabbling ducks (Anas spp.) and 10 to 50 swans (Cygnus buccinator and C. columbianus) has remained a mystery for the last ten years in Eagle River Flats (ERF), a 1,000 ha estuarine salt marsh near Anchorage, Alaska, used for artillery training by the U.S. Army. We have gathered evidence that the cause of this mortality is the highly toxic, incendiary munition white phosphorus (P4). The symptoms of poisoning we observed in wild ducks included lethargy, repeated drinking, and head shaking and rolling. Death was preceded by convulsions. Farm-reared mallards dosed with white phosphorus showed nearly identical behavioral symptoms to those of wild ducks that became sick in ERF. White phosphorus does not occur in nature but was found in both the sediments where dabbling ducks and swans feed and in the gizzards of all carcasses collected in ERF. We hypothesize that feeding waterfowl are ingesting small particles of the highly toxic, incendiary munition P4 stored in the bottom anoxic sediments of shallow salt marsh ponds. PMID:1474672

Racine, C H; Walsh, M E; Roebuck, B D; Collins, C M; Calkins, D; Reitsma, L; Buchli, P; Goldfarb, G

1992-10-01

162

Shoreline Development Drives Invasion of Phragmites australis and the Loss of Plant Diversity on New England Salt Marshes  

Microsoft Academic Search

The reed Phragmites australis Cav. is aggressively invading salt marshes along the Atlantic Coast of North America. We examined the interactive role of habitat alteration (i.e., shoreline development) in driv- ing this invasion and its consequences for plant richness in New England salt marshes. We surveyed 22 salt marshes in Narragansett Bay, Rhode Island, and quantified shoreline development, Phragmites cover,

BRIAN R. SILLIMAN; MARK D. BERTNESS

2004-01-01

163

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

PubMed

The salt marsh grass Distichlis spicata was regenerated from tissue culture and propagated in a greenhouse. Selected regenerants, along with selections from six wild populations, were grown for two years in a common garden flood-irrigated thrice weekly with tidal creek water. Selected wild and regenerated plants were also planted in a created salt marsh. Significant differences among regenerant and wild population selections were found in several functionally important salt marsh plant characteristics, including potential detritus production, belowground organic matter production, canopy structure, and decomposition rate. A combination of characteristics not found in the wild populations was evident in a regenerated line that exhibited both a high detritus production potential and a high decomposition rate. The amount of variation that occurred among regenerants from one parental line via somaclonal variation was similar to that which occurred among the wild population selections. Results of this study suggest that tissue culture may provide a means of producing marsh grasses with specific characteristics for directing the functional development of newly created salt marshes. PMID:10636837

Seliskar, D M; Gallagher, J L

2000-01-01

164

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

NASA Astrophysics Data System (ADS)

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 subsurface topography has played in the area's geomorphological evolution. By defining the shallow-subsurface geologic framework, we hope to provide a foundation for future process-orientated and modeling studies of the evolution of coastal marshes.

Montane, Juana Maria

165

Phylogenetic Analysis of Culturable Dimethyl Sulfide-Producing Bacteria from a Spartina-Dominated Salt Marsh and Estuarine Water  

PubMed Central

Dimethylsulfoniopropionate (DMSP), an abundant osmoprotectant found in marine algae and salt marsh cordgrass, can be metabolized to dimethyl sulfide (DMS) and acrylate by microbes having the enzyme DMSP lyase. A suite of DMS-producing bacteria isolated from a salt marsh and adjacent estuarine water on DMSP agar plates differed markedly from the pelagic strains currently in culture. While many of the salt marsh and estuarine isolates produced DMS and methanethiol from methionine and dimethyl sulfoxide, none appeared to be capable of producing both methanethiol and DMS from DMSP. DMSP, and its degradation products acrylate and ?-hydroxypropionate but not methyl-3-mecaptopropionate or 3-mercaptopropionate, served as a carbon source for the growth of all the ?- and ?- but only some of the ?-proteobacterium isolates. Phylogenetic analysis of 16S rRNA gene sequences showed that all of the isolates were in the group Proteobacteria, with most of them belonging to the ? and ? subclasses. Only one isolate was identified as a ?-proteobacterium, and it had >98% 16S rRNA sequence homology with a terrestrial species of Alcaligenes faecalis. Although bacterial population analysis based on culturability has its limitations, bacteria from the ? and ? subclasses of the Proteobacteria were the dominant DMS producers isolated from salt marsh sediments and estuaries, with the ? subclass representing 80% of the isolates. The ?-proteobacterium isolates were all in the Roseobacter subgroup, while many of the ?-proteobacteria were closely related to the pseudomonads; others were phylogenetically related to Marinomonas, Psychrobacter, or Vibrio species. These data suggest that DMSP cleavage to DMS and acrylate is a characteristic widely distributed among different phylotypes in the salt marsh-estuarine ecosystem. PMID:11229912

Ansede, John H.; Friedman, Robert; Yoch, Duane C.

2001-01-01

166

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

PubMed Central

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

Donnelly, Jeffrey P.; Bertness, Mark D.

2001-01-01

167

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

PubMed

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

Donnelly, J P; Bertness, M D

2001-12-01

168

Silica uptake by Spartina--evidence of multiple modes of accumulation from salt marshes around the world  

PubMed Central

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

Carey, Joanna C.; Fulweiler, Robinson W.

2014-01-01

169

Importance of Vascular Plant and Algal Production to Macro-invertebrate Consumers in a Southern California Salt Marsh  

Microsoft Academic Search

The dietary importance of marsh vascular plants (primarilySalicornia virginica), algae and upland particulate inputs to macro-invertebrate consumers was studied in Carpinteria Salt Marsh, southern California, using stable carbon and nitrogen isotope ratios. This marsh is predominantly a marine or hypersaline system and succulents are the most common vascular plant species. Of invertebrates collected from the vegetated marsh, tidal flats and

H. M. Page

1997-01-01

170

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

SciTech Connect

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.

Nixon, S.W. (Rhode Island Univ., Kingston, RI (USA). Graduate School of Oceanography)

1982-03-01

171

Nitrogen Cycling and Ecosystem Exchanges in a Virginia Tidal Freshwater Marsh  

E-print Network

Nitrogen Cycling and Ecosystem Exchanges in a Virginia Tidal Freshwater Marsh SCOTT C. NEUBAUER1 of Biology, Villanova, Pennsylvania 19085 ABSTRACT: Tidal freshwater marshes are diverse habitats that differ, and nutrient status. Because our knowledge of the nitrogen (N) biogeochemistry of tidal freshwater systems

Neubauer, Scott C.

172

Net ecosystem CO 2 exchange in a temperate cattail marsh in relation to biophysical properties  

Microsoft Academic Search

Net ecosystem exchange (NEE) of carbon dioxide (CO2) was measured at a temperate cattail marsh using the eddy covariance technique in order to examine the relationships between NEE, weather, and vegetation properties. Analyses of CO2 fluxes for a complete year (May 9, 2005 to May 30, 2006) showed that the marsh wetland was a net CO2 sink for each month

Marie-Claude Bonneville; Ian B. Strachan; Elyn R. Humphreys; Nigel T. Roulet

2008-01-01

173

Evidence for iron-sulfate coupling in salt marsh sediments  

NASA Astrophysics Data System (ADS)

Organic carbon burial in shallow marine sediments represents an important net sink in the global carbon cycle. Microbially mediated oxidation of organic matter in oxic, suboxic, and anoxic sediments however, prevents the ultimate burial of organic carbon and its removal from the surface of the planet. Although the subsurface transformations of organic carbon have been studied extensively, an enigmatic question remains: when organic matter is deposited, what determines whether it will be buried, reoxidized, or undergo methanogenesis? One hypothesis is that the sulfur cycle, due to the abundance of sulfate in many surface environments, dominates the subsurface oxidation or other fate of organic carbon. However, it has also been suggested that iron may in turn play a key role in determining the behavior of the sulfur cycle. To better understand the controls on these processes, we are using stable isotope and geochemical techniques to explore the microbially mediated oxidation of organic carbon in salt marsh sediments in North Norfolk, UK. In these sediments there is a high supply of organic carbon, iron, and sulfate (from diurnal tidal cycles). Thus these environments may provide insight into the nature of interactions between the carbon, iron, and sulfur cycles. A series of sampling missions was undertaken in the autumn and winter of 2013-2014. In subsurface fluid samples we observe very high ferrous iron concentrations (>1mM), indicative of extended regions of iron reduction (to over 30cm depth). Within these zones of iron reduction we would predict no sulfate reduction, and as expected ?34Ssulfate remains unchanged with depth. However, ?18Osulfate exhibits significant enrichments of up to 5 permil. This decoupling in the sulfur and oxygen isotopes of sulfate is suggestive of a sulfate recycling process in which sulfate is reduced to an intermediate sulfur species and subsequently reoxidized to sulfate. Taken together, these data suggest that microbial assemblages in these salt marsh sediments facilitate a cryptic cycling of sulfur, potentially mediated by iron species in the zone of iron reduction.

Mills, Jennifer; Antler, Gilad; Turchyn, Alexandra

2014-05-01

174

Using the radium quartet for evaluating groundwater input and water exchange in salt marshes  

Microsoft Academic Search

The fluxes of 226Ra (half-life = 1600 years) and 228Ra (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

W Rama; Willard S. Moore

1996-01-01

175

Spatial pattern of localized disturbance along a Southeastern salt marsh tidal creek  

Microsoft Academic Search

Geomorphology may be an important predictor of vegetation pattern in systems where suceptibility to disturbance is unevenly\\u000a distributed across the landscape. Salt marsh communities exhibit spatial pattern in vegetation at a variety of spatial scales.\\u000a In coastal Georgia, the low marsh is a virtual monoculture ofSpartina alterniflora interspersed with patches of species that are more typical of the high marsh.

Janet M. Fischer; Tara Reed-Andersen; Jennifer L. Klug; Alice G. Chalmers

2000-01-01

176

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

PubMed Central

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:23029423

Dibble, Kimberly L.; Meyerson, Laura A.

2012-01-01

177

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

NASA Astrophysics Data System (ADS)

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 changes in vegetation coverage percentage in controlling salt marshes evolution have important implications in their stability and consequently in coastal management. These conditions are unlikely to be unique to these salt marshes and it is suggested that similar analyses are replicated for other tidally dominated systems to improve understanding and characterization of their dynamics and stability under climate change context.

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

2013-09-01

178

A mid-Holocene record of sediment dynamics and high resolution accretion rates in a coastal salt marsh from Northern California  

NASA Astrophysics Data System (ADS)

Sediment accretion rates in coastal salt marshes are the critical determining factor in terms of ecosystem stability in the face of accelerated sea level rise (SLR), projected to rise by up to 1.4 m by 2100 in Southern California (National Research Council, 2012). However, high resolution studies of accretion rates in coastal salt marshes over the past several millennia have not yet been conducted for most of the US west coast. We collected multiple sediment records from small salt marshes surrounding Humboldt Bay, California. Due to this unique tectonic setting, many suspect cores from these marshes have evidence of coastal subsidence due to earthquake activity or large tsunami deposits (Jacoby et al., 1995). These records therefore are one of the best proxy measures for how salt marshes in California may respond to accelerated SLR. We analyzed all cores for magnetic susceptibility, % organic matter, and select cores for particle size. High resolution, millennial and centennial scale, radiocarbon dating for these sediment records reveals a detailed history of marsh accretion rates.

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

2013-12-01

179

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

PubMed Central

A study was conducted during the summer of 2009 (from July to September) to characterize mosquito communities among different habitats in five historically ditched tidal salt marshes and three adjacent wooded areas in the E.A. Vaughn Wetland Management Area on the Maryland Delmarva Peninsula, USA. Study marshes are characteristic of Atlantic coastal salt marshes that had undergone grid ditching from the 1930s to 1950s. In the autumn of 2008 (October and November) ditches were plugged near their outlets in two (‘experimental’) marshes with the aim to restore their natural tidal hydrology. The three other marshes were not plugged. Marshes were sampled from July to September in 2009 by using standard dip count method. A total of 2,457 mosquito larvae representing six species were collected on 15.4% (86/557) of all sample occasions and 399 adults representing four mosquito species were collected from landing counts. Aedes sollicitans, Anopheles bradleyi and Culex salinarius were the most common species collected in larval habitats, and Ae. sollicitans was the most common adult collected. Wooded habitats had more total mosquitoes, were also more frequently occupied by mosquitoes and had higher densities of mosquitoes than marsh habitats. Almost all larvae collected from marshes were from one experimental and one control site. The majority of larvae at the control site were Ae. sollicitans in marsh pannes while Cx. salinarius, An. bradleyi, Ae. cantator, and Ae. sollicitans were collected in high numbers from ditches at the experimental site. We found a difference in the proportion of marsh pannes occupied by Ae. sollicitans but not total mosquitoes sampled 4–5 days after spring tide events than on other occasions. Salinity measures of 42 larval habitats showed lower median salinity in mosquito-occupied habitats (11.5 ppt) than unoccupied habitats (20.1 ppt), and in habitats in wooded areas followed by ditches and pannes in marsh areas. The results of this study suggest that wooded areas adjacent to salt marshes may be a substantial source of biting adult mosquitoes usually associated with salt marsh habitats and that ditch plugging may alter the productivity of mosquitoes on some marshes. We recommend future studies consider mosquito productivity from habitats surrounding salt marshes, and if assessments of marsh alterations are a goal, compare multiple experimental and control areas before and after treatments to determine if alterations have a consistent impact on regional mosquito production. PMID:21909293

Leisnham, Paul T.; Sandoval-Mohapatra, Sarah

2011-01-01

180

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...

181

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...

182

Seasonal patterns of CO 2 and water vapor exchange of three salt marsh succulents  

Microsoft Academic Search

Diurnal carbon dioxide exchange patterns of three salt marsh succulents, Borrichia frutescens, Batis maritima and Salicornia virginica, were determined on a seasonal basis in the marsh at Sapelo Island, Georgia. Year-round photosynthetic activity was observed in these species though winter rates of CO2 exchange were reduced. Net primary productivity, estimated using gas exchange techniques, agreed with previously reported harvest data.

Ann E. Antlfinger; E. L. Dunn

1979-01-01

183

Early diagenesis of lignin-associated phenolics in the salt marsh grass Spartina alterniflora  

Microsoft Academic Search

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

R. I. Haddad; C. S. Martens; S. Y. Newell; R. D. Fallon

1992-01-01

184

Salt marsh sediment bacteria: their distribution and response to external nutrient inputs.  

PubMed

A primary focus among microbial ecologists in recent years has been to understand controls on the distribution of microorganisms in various habitats. Much less attention has been paid to the way that environmental disturbance interacts with processes that regulate bacterial community composition. We determined how human disturbance affected the distribution and community structure of salt marsh sediment bacteria by using denaturing gradient gel electrophoresis of 16S rRNA in five different habitats in each of four salt marshes located in northeastern Massachusetts, USA. Two of the four marsh creeks were experimentally enriched 15 x above background by the addition of nitrogen and phosphorus fertilizers for two or more growing seasons. Our results indicate that extrinsic factors acting at broad scales do not influence the distribution of salt marsh sediment bacteria. Intrinsic factors, controlled by local-scale environmental heterogeneity, do play a role in structuring these sediment microbial communities, although nutrient enrichment did not have a consequential effect on the microbial community in most marsh habitats. Only in one habitat, a region of the marsh creek wall that is heavily colonized by filamentous algae, did we see any effect of fertilization on the microbial community structure. When similar habitats were compared among marshes, there was considerable convergence in the microbial community composition during the growing season. Environmental factors that correlated best with microbial community composition varied with habitat, suggesting that habitat-specific intrinsic forces are primarily responsible for maintaining microbial diversity in salt marsh sediments. PMID:19421233

Bowen, Jennifer L; Crump, Byron C; Deegan, Linda A; Hobbie, John E

2009-08-01

185

Modification of sediments and macrofauna by an invasive marsh plant  

Microsoft Academic Search

Invasive grasses have recently altered salt marsh ecosystems throughout the northern hemisphere. On the eastern seaboard of the USA, Phragmites australis has invaded both brackish and salt marsh habitats. Phragmites australis influence on sediments and fauna was investigated along a salinity and invasion-age gradient in marshes of the lower Connecticut River estuary. Typical salinities were about 19-24 ppt in Site

T. S. Talley; L. A. Levin

2001-01-01

186

Annual nitrogen budget of a temperate coastal barrier salt-marsh system along a productivity gradient at low and high marsh elevation  

Microsoft Academic Search

An annual nitrogen budget was established for a temperate back barrier salt-marsh system along a productivity gradient at low and high marsh elevation. We measured plant biomass and nitrogen content in three plant compartments to deduce plant N-allocation patterns. Measurements were done along a successional sequence in a salt-marsh system. In addition, N-mineralization, wet and dry atmospheric N-deposition and sediment

Harm J. van Wijnen; Jan P. Bakker

2000-01-01

187

EXPLOITING WILD POPULATION DIVERSITY AND SOMACLONAL VARIATION IN THE SALT MARSH GRASS DISTICHLIS SPICATA (POACEAE) FOR MARSH CREATION AND RESTORATION1  

Microsoft Academic Search

The salt marsh grass Distichlis spicata was regenerated from tissue culture and propagated in a greenhouse. Selected regenerants, along with selections from six wild populations, were grown for two years in a common garden flood-irrigated thrice weekly with tidal creek water. Selected wild and regenerated plants were also planted in a created salt marsh. Significant differences among regenerant and wild

DENISE M. SELISKAR; JOHN L. GALLAGHER

188

Factors Affecting Carbohydrate Production and Loss in Salt Marsh Sediments of Galveston Bay  

E-print Network

Benthic microalgae (BMA) living within the surface sediment of salt marshes are highly productive organisms that provide a significant proportion of organic carbon inputs into estuarine systems. BMA secrete extracellular carbohydrates in the form...

Wilson, Carolyn E.

2010-10-12

189

EFFECTS OF MALATHION ON MICROORGANISMS OF AN ARTIFICIAL SALT-MARSH ENVIRONMENT  

EPA Science Inventory

Laboratory salt-marsh environments were treated with malathion, an organophosphate insectide, and aerobic heterotrophic bacteria were monitored to determine changes in their microbial ecology. Several physiological activities were assayed in both treated and untreated controls; h...

190

Regulation of benthic algal and animal communities by salt marsh plants: Impact of shading  

E-print Network

of remineralized plant matter, higher salinity, or lessPlant zonation in low-latitude salt marshes: disentangling roles of ?ooding, salinity, andplant cover induced higher soil temperature, increased porewater salinities, and

Whitcraft, Christine R.; Levin, Lisa A.

2007-01-01

191

Utilization of salt marsh edge habitats by newly settled Sciaenids in a subtropical estuary  

E-print Network

Postsettlement patterns of habitat use along salt marsh shorelines of West Galveston Bay, Texas were examined for the bay spawning spotted seatrout (Cynoscion nebulosus), inshore spawning red drum (Sciaenops ocellatus), and offshore spawning...

Geary, Bert Wilson

2012-06-07

192

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...

193

Quantification of Salt Marsh Carbon Stocks: Integration of Remote Sensing Data and Techniques with Field Measurements  

E-print Network

in this study show the capability of remote sensing data for the characterization of salt marsh terrain and vegetation heights and the estimation of above-ground biomass quantities. The best biomass prediction models using lidar heights reported considerably...

Kulawardhana, Ranjani W

2013-12-02

194

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)

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.

Zhao, Y.; Raymond, P.

2012-12-01

195

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

Microsoft Academic Search

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

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

2011-01-01

196

Sexual productivity and spring intramarsh distribution of a key salt-marsh microbial secondary producer  

Microsoft Academic Search

Phaeosphaeria spartinicola is known to be an important fungal (ascomycetous) secondary producer in the smooth-cordgrass (Spartina alterniflora) decomposition system of western Atlantic salt marshes, yet its degree of predominance among the ascomycete assemblages of\\u000a salt marshes and the concentration of its sexual reproductive structures (ascomata) have been largely unknown. During May–June,\\u000a we measured by direct microscopy the percent occupancy of

Steven Y. Newell; Jennifer Wasowski

1995-01-01

197

Allocation of nitrogen and carbon in an estuarine salt marsh in Portugal  

Microsoft Academic Search

Above and below-ground biomass and nitrogen and carbon composition ofSpartina maritima, Halimione portulacoides andArthrocnemum perenne, dominating species in plant communities of the lower, middle and higher salt marsh, respectively, were compared in an estuarine\\u000a salt marsh in Portugal. Plant and soil nitrogen and carbon pools were estimated. For all three species root biomass was significantly\\u000a higher (70–92% of total biomass)

F. Catarino

1997-01-01

198

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

Microsoft Academic Search

The use of dredge material is a well-known technique for creating or restoring salt marshes that is expected to become more\\u000a common along the Gulf of Mexico coast in the future. However, the effectiveness of this restoration method is still questioned.\\u000a Wetland structural characteristics were compared between four created and three natural salt marshes in southwest Louisiana,\\u000a USA. The created

Keith R. Edwards; C. Edward Proffitt

2003-01-01

199

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

USGS Publications Warehouse

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 1996 as a result of spraying, and despite initial shallow subsidence and continual erosion through February 1998, water bottom elevation was raised sufficiently to allow S. alterniflora to invade via rhizome growth from the adjacent marsh. Hence, thin-layer deposition of dredged material at this site was effective at restoring and maintaining marsh elevation after 1.5 years. However, if the open water sediment deposits are not soon completely stabilized via further vegetative colonization, erosion may eventually lower elevations to the level where emergent vegetation cannot persist.

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

1999-01-01

200

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

PubMed

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 communities requires incorporating context-dependent biotic interactions into species range models. PMID:23580161

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

2013-09-01

201

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)

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.

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

1994-03-01

202

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

NASA Astrophysics Data System (ADS)

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.

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

2012-01-01

203

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

PubMed

Fungal decomposers are important contributors to the detritus-based food webs of salt marsh ecosystems. Knowing the composition of salt marsh fungal communities is essential in understanding how detritus processing is affected by changes in community dynamics. Automated ribosomal intergenic spacer analysis (ARISA) was used to examine the composition of fungal communities associated with four temperate salt marsh plants, Spartina alterniflora (short and tall forms), Juncus roemerianus, Distichlis spicata and Sarcocornia perennis. Plant tissues were homogenized and subjected to a particle-filtration protocol that yielded 106 microm particulate fractions, which were used as a source of fungal isolates and fungal DNA. Genera identified from sporulating cultures demonstrated that the 106 microm particles from each host plant were reliable sources of fungal DNA for ARISA. Analysis of ARISA data by principal component analysis (PCA), principal coordinate analysis (PCO) and species diversity comparisons indicated that the fungal communities from the two grasses, S. alterniflora and D. spicata were more similar to each other than they were to the distinct communities associated with J. roemerianus and S. perennis. Principal component analysis also showed no consistent, seasonal pattern in the composition of these fungal communities. Comparisons of ARISA fingerprints from the different fungal communities and those from pure cultures of selected Spartina ascomycetes supported the host/substrate specificity observed for the fungal communities. PMID:17256573

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

2006-01-01

204

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

PubMed

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

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

2014-05-01

205

Effects of ciprofloxacin on salt marsh sediment microbial communities.  

PubMed

Fluoroquinolones, a widely used class of antibiotics, are frequently detected in sediments and surface waters. Given their antimicrobial properties, the presence of these compounds may alter the composition of microbial communities and promote antibiotic resistance in the environment. The purpose of this study was to measure sorption, and effects of ciprofloxacin on microbial community composition, in sediment samples from three California salt marshes. Sediments were exposed to a ciprofloxacin concentration gradient (0-200 microg ml(-1) ciprofloxacin) and microbial community composition characterized using phospholipid fatty acid (PLFA) analysis. Sorption coefficients, expressed as log K(d), were calculated from fits using the Freundlich isotherm model. Ciprofloxacin strongly sorbed to all sediments and had log K(d) values, ranging from 2.9 to 4.3. Clay content was positively (r(2)=0.98) and pH negatively (r(2)=0.99) correlated to K(d) values. Biomass, PLFA richness, sulfate reducer and Gram-negative bacteria markers increased with ciprofloxacin concentrations, while the 17 cy/precursor and saturated/unsaturated biomarker ratios, indicators of starvation stress, decreased. The magnitude of the effect of ciprofloxacin on microbial communities was inversely correlated to the degree of sorption to the sediments. Despite the fact that ciprofloxacin is a wide-spectrum antibiotic, its impact on sediment microbial communities was selective and appeared to favor sulfate-reducing bacteria and Gram-negative bacteria. PMID:18043666

Córdova-Kreylos, Ana Lucía; Scow, Kate M

2007-11-01

206

Hydrodynamic modeling for river delta salt marshes using lidar topography  

NASA Astrophysics Data System (ADS)

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.

Hodges, Ben R.

2014-05-01

207

Mineralization of Detrital Lignocelluloses by Salt Marsh Sediment Microflora †  

PubMed Central

Specifically radiolabeled 14C-(cellulose)-lignocellulose and 14C-(lignin)-lignocellulose were isolated from labeled cuttings of Spartina alterniflora (cordgrass) and Pinus elliottii (slash pine). These were used to estimate the rates of mineralization to CO2 of lignocelluloses of estuarine and terrestrial origin in salt marsh estuarine sediments. The lignin moiety of pine lignocellulose was mineralized 10 to 14 times more slowly than that of Spartina lignocellulose, depending on the source of inoculum. Average values for percent mineralization after 835 h of incubation were 1.4 and 13.9%, respectively. For Spartina lignocellulose, mineralization of the cellulose moiety was three times faster than that of the lignin moiety. Average values for percent mineralization after 720 h of incubation were 32.1 and 10.6%, respectively. Lignocellulose and lignin contents of live pine and Spartina plants were analyzed and found to be 60.7 and 20.9%, respectively, for pine and 75.6 and 15.1%, respectively, for Spartina. PMID:16345647

Maccubbin, A. E.; Hodson, Robert E.

1980-01-01

208

Salt marsh community structure in the Tijuana Estuary, California  

NASA Astrophysics Data System (ADS)

Vegetation of the Tijuana Estuary salt marsh was investigated in relationship to measured environmental factors over a one-meter elevation gradient. Elevation was a good indicator of the changing environment, with lower elevations having higher salinity, more inundation, higher soil organic matter and more clay than upper elevations. Dominance of vascular plants changed gradually with elevation. Spartina foliosa dominated the lowest elevations, then Salicornia bigelovii and Batis maritima, Jaumea carnosa, Suaeda californica, Frankenia grandifolia, Monanthochloe littoralis, and Salicornia subterminalis, with Salicornia virginica common at all but the highest elevations studied. The vegetation could not be separated into realistic zones or associations on the basis of occurrence measured in 0·25 m 2 quadrats. The most discernible change in composition across the elevation gradient corresponds to the replacement of the tall Spartina foliosa with a mixture of low-growing succulents at 6-7 dm above Mean Sea Level. Species interactions of joint occurrence and cover were investigated to develop hypotheses concerning the role of competition in determining species distributions. It is hypothesized that Salicornia virginica, which has a bimodal distribution over the elevation gradient, is limited in the central part of its range by competition with Batis maritima or Salicornia bigelovii or both. And, because of their common co-occurrence and mutual abundance, it is hypothesized that Batis maritima and Salicornia bigelovii are not competitors.

Zedler, Joy B.

209

Populations of Methanogenic Bacteria in a Georgia Salt Marsh  

PubMed Central

Methanogens represented about 0.5% of the total bacteria in sediments from a Georgia salt marsh in which Spartina alterniflora is the predominant vegetation. The population of methanogens was composed of at least two groups of nearly equal size. One group was represented by cocci which were able to utilize trimethylamine and were unable to use H2 or acetate. The second group was composed of two subgroups which were able to utilize H2 but were unable to use trimethylamine or acetate. The more common subgroup included rod- or plate-shaped methanogens which could utilize isopropanol in addition to H2 and formate. The second subgroup included Methanococcus maripaludis, which utilized only H2 and formate. Other groups of methanogens were also present, including Methanosarcina sp. which utilized acetate, H2, and methylamines. In addition to the overall variability in the types of methanogens, the numbers of methanogens in sediments also exhibited significant spatial variability both within and between tall- and short-Spartina zones. Images PMID:16347628

Franklin, Michael J.; Wiebe, William J.; Whitman, William B.

1988-01-01

210

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

SciTech Connect

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.

Reed, D.J. (Louisiana Universities Marine Consortium, Chauvin (USA))

1989-09-01

211

One of the most pervasive human impacts to salt marshes around the world is the introduction of nonnative species. Plant introductions to salt marsh systems have  

E-print Network

and the changes it produces in the physical and chemical environment strongly influence benthic communities abundance and diversity. These physical and chemical changes can result in dramatic shifts in benthic of nonnative species. Plant introductions to salt marsh systems have resulted in significant changes ranging

Levin, Lisa

212

Interactions among Plant Species and Microorganisms in Salt Marsh Sediments  

PubMed Central

The interactions among Spartina patens and sediment microbial populations and the interactions among Phragmites australis and sediment microbial populations were studied at monotypic sites in Piermont Marsh, a salt marsh of the Hudson River north of New York, N.Y., at key times during the growing season. Arbuscular mycorrhizal fungi (AMF) effectively colonized S. patens but not P. australis, and there were seasonal increases and decreases that coincided with plant growth and senescence (17 and 6% of the S. patens root length were colonized, respectively). In sediment samples from the Spartina site, the microbial community and specific bacterial populations were at least twice as large in terms of number and biomass as the microbial community and specific bacterial populations in sediment samples from the Phragmites site, and peak values occurred during reproduction. Members of the domain Bacteria, especially members of the ?-, ?-, and ?-subdivisions of the Proteobacteria, were the most abundant organisms at both sites throughout the growing season. The populations were generally more dynamic in samples from the Spartina site than in samples from the Phragmites site. No differences between the two sites and no differences during the growing season were observed when restriction fragment length polymorphism analyses of nifH amplicons were performed in an attempt to detect shifts in the diversity of nitrogen-fixing bacteria. Differences were observed only in the patterns generated by PCR or reverse transcription-PCR for samples from the Spartina site, suggesting that there were differences in the overall and active populations of nitrogen-fixing bacteria. Regression analyses indicated that there was a positive interaction between members of the ?-subdivision of the Proteobacteria and root biomass but not between members of the ?-subdivision of the Proteobacteria and macroorganic matter at both sites. In samples from the Spartina site, there were indications that there were bacterium-fungus interactions since populations of members of the ?-subdivision of the Proteobacteria were negatively associated with AMF colonization and populations of members of the ?-subdivision of the Proteobacteria were positively associated with AMF colonization. PMID:11872463

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

2002-01-01

213

Assessing the performance of salt marsh and mangrove foraminifera as sea-level indicators  

NASA Astrophysics Data System (ADS)

Salt marsh foraminifera have proven to be an accurate sea-level indicator because their distributions on low-energy, organic coasts are vertically zoned with respect to the tidal frame and their tests are readily preserved in the sedimentary sequences. However, in contrast to salt marsh-based studies, there are fewer studies using mangrove foraminifera to reconstruct former sea level despite the importance of far field tropical localities for inferring the ice-equivalent component to relative sea-level change. This study compares the performance of salt marsh and mangrove foraminifera as sea-level indicators and attempts to reconstruct relative sea-level (RSL) change at decimeter scale using mangrove foraminifera. We chose one salt marsh site (St. Marys) and one mangrove site (Hobe Sound) along the Atlantic coast of Florida with similar climatic, biological, and geological conditions. At each site we collected modern (88 samples from 6 transects) and fossil (salt marsh and mangrove peat cores) material. We found differences between these environments with regards to the abundance, composition and diversity of the foraminiferal assemblages. The most abundant species in the salt marsh are Ammobaculites spp., Ammoastuta inepta, Haplophragmoides spp., and Trochammina inflata, while the dominant mangrove species are Arenoparrelle mexicana, Ammodiscoides spp., Glomospira spp., and Haplophragmoides spp. We quantified the optimum and tolerance of each foraminiferal species to elevations relative to tidal frame and subsequently developed salt marsh and mangrove transfer functions (TF). The TFs estimate vertical uncertainty of ~ ± 0.2 m, indicating that precise reconstructions of RSL are possible. The fossil mangrove core is dominated by species similar to the modern assemblages. We applied the mangrove-based TF and combined this with a preliminary chronology based on 210Pb and 14C dates to reconstruct RSL, which was validated against regional tide-gauge records, demonstrating its usefulness in assessing sea level changes in tropical to semi-tropical locations.

Liu, S.; Horton, B. P.; Toscano, M. A.; Engelhart, S. E.; Hawkes, A.

2011-12-01

214

Salt marsh as Culex salinarius larval habitat in coastal New York.  

PubMed

Culex salinarius is considered one of the most likely bridge vectors involved in the human transmission cycle of West Nile virus (WNV) and eastern equine encephalomyelitis virus (EEEV) in the northeastern USA. The larval habitats of this species in the coastal region of New York State are currently poorly known. Between 2005 and 2007, a larval survey was carried out to identify and characterize possible larval habitats in Suffolk County, encompassing natural and man-made freshwater wetlands, artificial containers, and salt marshes. Only relatively undisturbed salt marsh yielded Cx. salinarius larvae in considerable numbers from several sites over a period of 2 years. The immature stages of this species were found associated with Spartina patens and S. alterniflora of the upper marsh at salinities ranging from 4.3 to 18.8 parts per thousand. Both heavily impacted and relatively undisturbed salt marshes produced several hundreds of adult Cx. salinarius per Centers for Disease Control and Prevention (CDC) light trap per night, an order of magnitude higher than CDC light traps deployed at upland sites. The ability of Cx. salinarius to use both heavily impacted and relatively undisturbed salt marshes for reproduction has significant repercussions for marsh restoration and vector control practices. PMID:18939687

Rochlin, Ilia; Dempsey, Mary E; Campbell, Scott R; Ninivaggi, Dominick V

2008-09-01

215

Predation by the black-clawed mud crab, Panopeus herbstii , in Mid-Atlantic salt marshes: Further evidence for top-down control of marsh grass production  

Microsoft Academic Search

Although top-down control of plant growth has been shown in a variety of marine systems, it is widely thought to be unimportant\\u000a in salt marshes. Recent caging experiments in Virginia and Georgia have challenged this notion and shown that the dominant\\u000a marsh grazer (the periwinkle,Littoraria irrorata) not only suppresses plant growth, but can denude marsh substrate at high densities. In

Brian Reed Silliman; Craig A. Layman; Kane Geyer; J. C. Zieman

2004-01-01

216

Composition of Fish Communities in a European Macrotidal Salt Marsh (the Mont Saint-Michel Bay,  

E-print Network

Composition of Fish Communities in a European Macrotidal Salt Marsh (the Mont Saint-Michel Bay At least 100 fish species are known to be present in the intertidal areas (estuaries, mudflats and salt, such as estuaries and lagoons, play a nursery role for many fish species. However, in Europe little attention has

Boyer, Edmond

217

Germination in relation to salinity in some plants of salt marshes in Otago, New Zealand  

Microsoft Academic Search

Germination characteristics were examined for nine halophytes occurring on Otago salt marshes and were compared with two glycophytes. The seed of most halophytes remained dormant, but viable, in saline solution for at least several months. In comparison, of the two glycophyte species, one germinated in saline solution whereas the other suffered seed mortality. There was a correlation between the salt

T. R. Partridge; J. B. Wilson

1987-01-01

218

The importance of salt-marsh wetness for seed exploitation by dabbling ducks Anas sp  

Microsoft Academic Search

The relationship between the inundation of a salt marsh in southeast Denmark not subject to lunar tides and the availability and predation of seeds of the annuals Salicornia spp. and Suada maritima by autumn staging dabbling ducks was studied by carrying out exclosure experiments over the course of 2 years. There was a marked difference in the wetness of the salt

Ole R. Therkildsen; Thomas Bregnballe

2006-01-01

219

Environmental gradients, plant distribution, and species richness in arctic salt marsh near Prudhoe Bay, Alaska  

Microsoft Academic Search

Spatial patterns of plant cover and species composition in arctic salt marsh and salt affected tundra near Prudhoe Bay, Alaska reflect gradients in elevation, soil conductivity, and soil concentrations of the ions prevalent in seawater. Soil conductivity and soil concentrations of Ca2+, Mg2+, Na+, K+, SO4= and Cl- were significantly related to site elevation, decreasing as elevation increased. Vascular plant

Dale W. Funk; Lynn E. Noel; Adam H. Freedman

2004-01-01

220

Biostimulation for the Treatment of an oil-contaminated Coastal Salt Marsh  

Microsoft Academic Search

A field study was conducted on a coastal salt marsh in Nova Scotia, Canada, during the summer of 2000. The objective of the\\u000a study was to assess the effectiveness of biostimulation in restoring an oil-contaminated coastal marsh dominated by Spartina alterniflora under north-temperate conditions. Three remediation treatments were tested with two additional unoiled treatments, with and\\u000a without added nutrients, serving

Susana Garcia-Blanco; Albert D. Venosa; Makram T. Suidan; Kenneth Lee; Susan Cobanli; John R. Haines

2007-01-01

221

Crab: snail size-structured interactions and salt marsh predation gradients  

Microsoft Academic Search

We studied size-structured predator-prey interactions between blue crabs (Callinectes sapidus) and marsh periwinkles (Littoraria irrorata) with a combination of field studies, laboratory experiments and individual-based modeling. Size distributions of Littoraria differed among years at the same sites in a salt marsh and could largely be explained by dominance of strong cohorts in the population. At a given site, abundance increased

Daniel E. Schindler; Brett M. Johnson; Neil A. MacKay; Nicolaas Bouwes; James F. Kitchell

1994-01-01

222

Pyrite and oxidized iron mineral phases formed from pyrite oxidation in salt marsh and estuarine sediments  

Microsoft Academic Search

We used scanning electron microscopy and energy dispersive X-ray analysis to examine sediments from vegetated portions of three salt marshes, the Great Sippewissett Marsh (Cape Cod, MA), Sapelo Island (Georgia), and the Hackensack Meadowlands (N.J.), and from the sediments of an estuary, Newark Bay (N.J.). Pyrite particles were abundant in sediments from all sites. Both fine grained pyrite crystals and

George W. Luther III; Anne Giblin; Robert W. Howarth; Robert A. Ryans

1982-01-01

223

The effect of tidal exclusion on salt marsh vegetation in Baja California, México  

Microsoft Academic Search

Changes in salt marsh vegetation were analyzed over a two-year period (November 1984–November 1986) following the construction of a dike in the southwest corner of Punta Banda Estuary, Baja California, México. Changes included: increased interstitial soil salinity, reduced soil moisture, increased mortality of Spartina foliosa and decreased middle marsh species diversity due to the elimination of annual and short-lived species.

Silvia E. Ibarra-Obando; Miriam Poumian-Tapia

1991-01-01

224

Multi-seasonal spectral characteristics analysis of coastal salt marsh vegetation in Shanghai, China  

NASA Astrophysics Data System (ADS)

Remote sensing technology has become the primary tool for ecological research on a large scale. The spectral characteristics of the salt marsh vegetation canopy, including four main communities, Phragmites australis community, Spartina alterniflora community, Scirpus mariqueter community and Carex scabrifolia community, were measured in the seasons of spring, summer and autumn by a ground FieldSpec™ Pro JR spectroradiometer, at the Chongming Dongtan Nature Reserve in Shanghai. The spectral data were converted to the reflectance curves, and their first derivative curves between 350 nm and 1000 nm were calculated. The differences in the reflectance and first derivative curves were then analyzed, with particular attention paid to the characteristics in the bands of visible, "green peak", "red edge" and near infrared. The results from this study showed that the different salt marsh communities had different and rather unique spectral characteristics during the three seasons studied. The near-ground spectral reflectance varied with the growing season, community type and its phenology. The discrimination ability, in terms of variations in the spectral reflectance, among the four major salt marsh communities was highest in autumn. It is proposed that a realistic strategy for classifying the salt marsh vegetation could be adopted by integrating and analyzing their remotely sensed images of multi-seasons. The implications of the results from this study in terms of serving as a tool for monitoring and mapping the distribution pattern and dynamics of salt marsh vegetation on the eastern coast of China are discussed.

Gao, Z. G.; Zhang, L. Q.

2006-08-01

225

Anthropogenic ecological change and impacts on mosquito breeding and control strategies in salt-marshes, Northern Territory, Australia.  

PubMed

Darwin, in the tropical north of Australia, is subject to high numbers of mosquitoes and several mosquito-borne diseases. Many of Darwin's residential areas were built in close proximity to tidally influenced swamps, where long-term storm-water run-off from nearby residences into these swamps has led to anthropogenic induced ecological change. When natural wet-dry cycles were disrupted, bare mud-flats and mangroves were transformed into perennial fresh to brackish-water reed swamps. Reed swamps provided year-round breeding habitat for many mosquito species, such that mosquito abundance was less predictable and seasonally dependent, but constant and often occurring in plague proportions. Drainage channels were constructed throughout the wetlands to reduce pooled water during dry-season months. This study assesses the impact of drainage interventions on vegetation and mosquito ecology in three salt-marshes in the Darwin area. Findings revealed a universal decline in dry-season mosquito abundance in each wetland system. However, some mosquito species increased in abundance during wet-season months. Due to the high expense and potentially detrimental environmental impacts of ecosystem and non-target species disturbance, large-scale modifications such as these are sparingly undertaken. However, our results indicate that some large scale environmental modification can assist the process of wetland restoration, as appears to be the case for these salt marsh systems. Drainage in all three systems has been restored to closer to their original salt-marsh ecosystems, while reducing mosquito abundances, thereby potentially lowering the risk of vector-borne disease transmission and mosquito pest biting problems. PMID:22476689

Jacups, Susan; Warchot, Allan; Whelan, Peter

2012-06-01

226

Anthropogenic modification of New England salt marsh landscapes  

E-print Network

and eutrophication. On the seaward border of these marshes, nitrogen eutrophication stimulated by local shoreline of the common reed, Phragmites, by means of nitrogen eutrophication caused by the removal of the woody

Bertness, Mark D.

227

Sulfate reduction in the salt marshes at Sapelo Island, Georgia  

Microsoft Academic Search

Sulfate reduction rates were measured in stands of Spartina alterniflora at Sapelo Island, Georgia, in November 1980 by injecting tracer amounts of ³⁵SOâ\\/sup 2 -\\/ into cores, incubating overnight, and analyzing for the incorporation of ³⁵S into reduced sulfur compounds. Qualitatively, sulfate reduction in the Georgia marsh is very similar to that in the Massachusetts marshes the authors have studied:

ROBERT W. HOWARTH; ANNE GIBLIN

1983-01-01

228

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

PubMed Central

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

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

1980-01-01

229

Nitrogen addition does not reduce belowground competition in a salt marsh clonal plant community in Mississippi (USA)  

Microsoft Academic Search

Previous studies have suggested that belowground competition for nutrients influences plant zonation in salt marshes. In this study, I tested the hypothesis that competition for nitrogen structured a clonal plant community in a nitrogen-limited salt marsh in coastal Mississippi, USA. In contrast to most previous field studies that have investigated mechanisms of competition, I examined clonal growth responses of established

J. Stephen Brewer

2003-01-01

230

Using Marker Horizons and Cryogenic Coring to Monitor Sediment Deposition in Salt Marshes of the Bay of Fundy  

E-print Network

Using Marker Horizons and Cryogenic Coring to Monitor Sediment Deposition in Salt Marshes that has accumulated over the marker horizon is measured. Cryogenic coring is one method of extracting out of the soil, a frozen core of marsh sediment is obtained. Using cryogenic coring to obtain salt

Chmura, Gail L.

231

Joint Geophysical and Hydrologic Constraints on Shallow Groundwater Flow Systems in Clastic Salt Marshes of the South Atlantic Bight  

Microsoft Academic Search

Salt marsh systems play a critical role in buffering upland coastal areas from the influence of open saltwater bodies and in filtering contaminants that originate offshore or are flushed from uplands. For these reasons, it is important to understand the salt marsh hydrologic cycle, especially the interaction of groundwater and surface water across low-lying coastal fringes and the changes in

C. Ruppel; P. Fulton; G. M. Schultz; L. Castillo; J. Bartlett; S. Sibley

2005-01-01

232

Impact of Fertilization on a Salt Marsh Food Web in Georgia Caroline R. McFarlin & J. Stephen Brewer &  

E-print Network

Impact of Fertilization on a Salt Marsh Food Web in Georgia Caroline R. McFarlin & J. Stephen 2008 Abstract We examined the response of a salt marsh food web to increases in nutrients at 19 coastal species. Fertilization increased Spartina cover, height, and biomass and Juncus height, but led

Pennings, Steven C.

233

Lithium in the brines of Fish Lake Valley and Columbus Salt Marsh, Nevada  

USGS Publications Warehouse

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.

Smith, C.L.; Meier, Allen L.; Downey, H.D.

1977-01-01

234

Long-term salt marsh vertical accretion in a tidal bay with reduced sediment supply  

NASA Astrophysics Data System (ADS)

Because of damming and intensive human activities, the sediment supply to many estuaries and deltas is dramatically decreasing. In the Oosterschelde (southwest Netherlands), a storm surge barrier (SSB) and two compartmentalization dams were built in the 1980s to protect the densely inhabited inland against flooding. After these constructions, the tidal range and mean high water level in the Oosterschelde decreased by about 12% and suspended sediment concentrations in the channels dropped by 52-70% compared to the pre-barrier conditions. The vertical accretion rates of the three largest salt marshes (Rattekaai, Sint Annaland and Slaak) in the Oosterschelde in response to this decreased sediment supply were investigated. There was a general accreting trend over the entire post-barrier period (1988-2011) in all three marshes. The predicted slowdown in accretion rates by De Jong et al. (1994) did not persist, although accretion rates were lower than in the pre-barrier period. More than 20 year observations from kaoline markers showed variation of accretion rates within and among marshes. Year-to-year variation in accretion rates was large, but only weakly (not significantly) related to the duration and frequency of marsh overflow and over-marsh extreme flooding events. However, storm events are hypothesized to be responsible for the observed trends, but our observations lack the temporal resolution to identify specific storm events. Salt marshes in the Oosterschelde are expected to survive under the present sea level rise rate and subsidence rate scenarios.

Ma, Zhigang; Ysebaert, Tom; van der Wal, Daphne; de Jong, Dick J.; Li, Xiuzhen; Herman, Peter M. J.

2014-06-01

235

Modern salt-marsh and tidal-flat foraminifera from Sitkinak and Simeonof Islands, southwestern Alaska  

USGS Publications Warehouse

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.

Kemp, Andrew C.; Engelhart, Simon E.; Culver, Stephen J.; Nelson, Alan R.; Briggs, Richard W.; Haeussler, Peter J.

2013-01-01

236

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

PubMed

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 x 10 phototrophs g of dry sediment) and minimal numbers occurring in winter (mean, 3.9 x 10 phototrophs g of dry sediment). 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 x 10 phototrophs ml, 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 x 10 phototrophs g of dry tissue) and creekside (4.9 x 10 phototrophs g of dry tissue) 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

Paterek, J R; Paynter, M J

1988-06-01

237

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

ERIC Educational Resources Information Center

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:…

Brevard County School Board, Cocoa, FL.

238

Primary Research Paper Ecosystem response to changes in water level of Lake Ontario marshes: lessons  

E-print Network

Primary Research Paper Ecosystem response to changes in water level of Lake Ontario marshes, Great Lake, Lake Ontario, emergent vegetation, submersed aquatic vegetation, coastal wetland Abstract restoration of Great Lakes coastal wetlands because inter-annual and seasonal variations often confound

McMaster University

239

Long-Term Sediment Dynamics in a Tidal Salt Marsh, North Inlet, South Carolina  

NASA Astrophysics Data System (ADS)

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 system coincides with spring tides while export occurs during neap tidal conditions. Rainfall increases sediment concentration in the channels and appears to be associated with periods of sediment redistribution within the marsh. The impact of river discharge on suspended sediment concentrations affects the marsh over longer time intervals with years of low discharge into adjacent Winyah Bay coinciding with periods of low suspended sediment concentrations. Water discharge through each channel will be estimated using harmonic analysis of tidal current records collected over a 30-day period in order to resolve spring-neap variations in tidal velocity. The coupling of mean suspended sediment concentration and water discharge of the same phase will later be used to produce a long-term sediment budget for the marsh basin.

Murphy, S.; Voulgaris, G.

2001-05-01

240

The Role of Phragmites australis in Mediating Inland Salt Marsh Migration in a Mid-Atlantic Estuary  

PubMed Central

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

Smith, Joseph A. M.

2013-01-01

241

Clonal structure of Elytrigia atherica along different successional stages of a salt marsh.  

PubMed

Elytrigia atherica is a tall clonal grass species typical of higher salt marshes, but is gradually invading to the lower marshes. At young successional stages of a salt marsh, E. atherica is found sparsely dispersed in small groups of ramets. These patches increase in size and ramet density over time, eventually forming extensive swards as succession proceeds. This study investigates the change in the clonal diversity of E. atherica stands during colonization as a result of its reproductive strategy. Clonal diversities of differently sized patches of E. atherica were investigated on two lower salt-marsh sites of different age, 25 years and 35 years, respectively. Microsatellite fingerprint patterns were used to determine genet identities and to estimate relatedness and genetic differentiation between the sites, between patches within sites and within patches. The majority of the patches on both sites contained more than one genet. On the older site, the clonal diversity was higher than on the younger site. However, the clonal diversity tended to decrease with increasing patch size. Low genetic differentiation was found between the two sites, indicating habitat differentiation, whereas differentiation between patches within sites was high. It is reasoned that different environmental conditions could have resulted in different clonal structures: On an older marsh, the increase of successful seedling recruitment, due to more suitable environmental conditions, leads to an increase in clonal diversity. Over time, with increasing ramet density, intraspecific competition is likely to increase, resulting in a decrease of clonal diversity. PMID:17305865

Scheepens, J F; Veeneklaas, R M; Van De Zande, L; Bakker, J P

2007-03-01

242

Importance of biogeomorphic and spatial properties in assessing a tidal salt marsh vulnerability to sea-level rise  

USGS Publications Warehouse

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 estuaries. In light of SLR, improving our understanding of elevation change in these dynamic marsh systems will play a crucial role in forecasting potential impacts to their sustainability and the survival of these ecosystems.

Thorne, Karen M.; Elliott-Fisk, Deborah L.; Wylie, Glenn D.; Perry, William M.; Takekawa, John Y.

2014-01-01

243

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

NASA Astrophysics Data System (ADS)

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 restoration strategies to foster adaptation to the effects of future climate change.

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

2011-12-01

244

The impact of cattle grazing on salt marsh and elevated hummock vegetation communities of a Texas barrier island  

E-print Network

consumed by some species of foraging waterfowl, after cattle had been introduced into a marsh in Sweden (however, grazing was found to be detrimental to the seed production of Scirpus man tintus (salt-marsh bulrush), the seeds of which are consumed... consumed by some species of foraging waterfowl, after cattle had been introduced into a marsh in Sweden (however, grazing was found to be detrimental to the seed production of Scirpus man tintus (salt-marsh bulrush), the seeds of which are consumed...

Carothers, James Michael

2012-06-07

245

High site fidelity and low site connectivity in temperate salt marsh fish populations: a stable isotope approach.  

PubMed

Adult and juvenile fish utilise salt marshes for food and shelter at high tide, moving into adjacent sublittoral regions during low tide. Understanding whether there are high levels of site fidelity for different species of coastal fish has important implications for habitat conservation and the design of marine protected areas. We hypothesised that common salt marsh fish species would demonstrate a high site fidelity, resulting in minimal inter-marsh connectivity. Carbon ((13)C) and nitrogen ((15)N) stable isotope ratios of larvae and juveniles of five common salt marsh fish (Atherina presbyter, Chelon labrosus, Clupea harengus, Dicentrarchus labrax, Pomatoschistus microps), seven types of primary producer and seven secondary consumer food sources were sampled in five salt marshes within two estuary complexes along the coast of south-east England. Significant differences in (13)C and (15)N signatures between salt marshes indicated distinct sub-populations utilising the area of estuary around each salt marsh, and limited connectivity, even within the same estuary complex. (15)N ratios were responsible for the majority of inter-marsh differences for each species and showed similar site-specific patterns in ratios in primary producers, secondary consumers and fish. Fish diets (derived from isotope mixing models) varied between species but were mostly consistent between marsh sites, indicating that dietary shifts were not the source of variability of the inter-marsh isotopic signatures within species. These results demonstrate that for some common coastal fish species, high levels of site fidelity result in individual salt marshes operating as discrete habitats for fish assemblages. PMID:21786154

Green, Benjamin C; Smith, David J; Grey, Jonathan; Underwood, Graham J C

2012-01-01

246

Classification of salt marsh vegetation using edaphic and remote sensing-derived variables  

NASA Astrophysics Data System (ADS)

Salt marsh plant communities are known for their striking patterns of vertical zonation. Two of the most important edaphic parameters that affect species distribution patterns are soil salinity and waterlogging, both of which are related to topographical variations and distance to the water. The primary objective of this study was to evaluate whether information on elevation and distance derived through remote sensing could be used to predict plant distributions in a southeastern United States salt marsh. We classified four marsh vegetation classes (tall Spartina alterniflora, medium S. alterniflora/short S. alterniflora, marsh meadow, and Borrichia frutescens/Juncus roemerianus) based on landscape metrics obtained from a light detection and ranging (LIDAR)-derived digital elevation model (DEM) and compared results to a classification based on field-collected edaphic variables. Our secondary objective was to compare the performance of linear discriminant analysis (LDA) with non-parametric classification and regression trees (CART) for these classifications. Models based on the edaphic variables soil water content, salinity, and redox potential attained accuracies of 0.62 and 0.71 with LDA and CART, respectively. When the remote sensing-derived variables DEM elevation, slope, distance to the mean high water line, and distance to upland area were used, classification accuracies improved to 0.78 for LDA and 0.79 for CART. Our results suggest that remote sensing-derived metrics can capture edaphic gradients effectively, which makes them especially suited to landscape level analyses of salt marsh plant habitats, with potential application for predicting the effects of sea level rise on salt marsh plant distribution.

Hladik, Christine; Alber, Merryl

2014-03-01

247

Dynamics of bacterial community succession in a salt marsh chronosequence: evidences for temporal niche partitioning.  

PubMed

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 ?-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

Dini-Andreote, Francisco; de Cássia Pereira e Silva, Michele; Triadó-Margarit, Xavier; Casamayor, Emilio O; van Elsas, Jan Dirk; Salles, Joana Falcão

2014-10-01

248

Crabs Mediate Interactions between Native and Invasive Salt Marsh Plants: A Mesocosm Study  

PubMed Central

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

Zhang, Xiao-dong; Jia, Xin; Chen, Yang-yun; Shao, Jun-jiong; Wu, Xin-ru; Shang, Lei; Li, Bo

2013-01-01

249

INTRODUCTION Salt-marsh sites along the North Sea coasts of  

E-print Network

on the salt marsh than sympatric Dark-bellied Brent Geese. 84% of the Barnacle Goose flocks were encountered April, whereas this applied to only 44% of the Dark-bellied Brent Goose flocks. Barnacle Geese avoided (Holmes & Phillips 1985; Goldstein & Skadhauge 2000). In addition, geese perform drinking flights

Kleyer, Michael

250

The effect of competition and salinity on the growth of a salt marsh plant species  

Microsoft Academic Search

Young rhizome sprouts of the herbaceous perennial Jaumea carnosa were propagated from material collected in a salt marsh along the central California coast. The sprouts were transplanted to flats of sand sown with different densities of seeds of a representative glycophyte, Lolium perenne L. “Derby, turf type.” Controls flats contained only Jaumea or Lolium. Three series of replicated flats were

Michael G. Barbour

1978-01-01

251

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...

252

Archaeal Diversity and the Prevalence of Crenarchaeota in Salt Marsh Sediments  

Microsoft Academic Search

Crenarchaeal 16S rRNA sequences constituted over 70% of the archaeal clones recovered from three salt marsh sites dominated by different grasses. Group I.1a Crenarchaeota dominated at two sites, while group I.3b Crenarchaeota sequences were most abundant at a third site. Abundances of 16S rRNA genes related to \\

Katelyn A. Nelson; Nicole S. Moin; Anne E. Bernhard

2009-01-01

253

Biogeochemical cycling of methylmercury at Barn Island Salt Marsh, Stonington, CT, USA  

Microsoft Academic Search

Monomethylmercury (MMHg) is toxic, and is the primary form of Hg thatbioaccumulates in the food web. An understanding of its distribution,production, and transport is needed. Prior investigations indicate thatmethylation is mediated by sulfate-reducing bacteria, yet limited in highsulfate environments. High rates of microbial respiration and strong oxygengradients are found in salt marshes. It is hypothesized that significant in situ methylation

C. S. Langer; W. F. Fitzgerald; P. T. Visscher; G. M. Vandal

2001-01-01

254

Fish-Nursery Use in Georgia Salt-Marsh Estuaries: The Influence of Springtime Freshwater Conditions  

Microsoft Academic Search

The fish assemblage using shallow nursery habitats in the Ogeechee River-Ossabaw Sound salt-marsh estuary, Georgia, was investigated during the winter and spring of two successive years. High river discharges during these periods produced fully freshwater conditions (all tidal stages and amplitudes) in the upper portion of the study area for up to 4 months. Abundances of Atlantic croaker Micropogonias undulatus,

S. Gordon Rogers; Timothy E. Targett; Scott B. Van Sant

1984-01-01

255

DECEMBER, 1976 MOSQUITO NEWS W6 9 437 BEHAVIORAL CHANGES IN THE SALT MARSH MOSQUITO,  

E-print Network

DECEMBER, 1976 MOSQUITO NEWS W6 9 437 BEHAVIORAL CHANGES IN THE SALT MARSH MOSQUITO, AEDES SOLLICITANS, AS A RESULT OF INCREASED PHYSIOLOGICAL AGE' WAYNE'J. CRANS, JERE DOWNING MARC E. SLAFF Mosquito for less than week the inland site and that few bites would be received from mosquitoes. When the nuisance

256

Nitrogen resorption from senescing leaves of three salt marsh plant species  

Microsoft Academic Search

Seasonalvariation in leaf nitrogen of mature green and senescent leaves and nitrogenresorption efficiency in three plants (Spartina maritima, Halimioneportulacoides and Arthrocnemum perenne) of aTagus estuary salt marsh are reported. Total nitrogen concentrations in greenand senescent leaves were higher during winter (December and March). Soilinorganic nitrogen availability showed an opposite pattern with higherconcentrations during summer (June and September) when total leaf

P. Cartaxana; F. Catarino

2002-01-01

257

Critical Bifurcation of Shallow Microtidal Landforms in Tidal Flats and Salt Marshes  

Microsoft Academic Search

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

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

2006-01-01

258

The effect of cattle and sheep grazing on salt-marsh vegetation at Skallingen, Denmark  

Microsoft Academic Search

The aggregated effect of cattle and sheep grazing on Puccinellion maritimae and other salt-marsh vegetation has been studied together with changes in species composition, the percentage cover of each species, total cover and the percentage of bare ground, six years after grazing had been prevented by construction of experimental exclosures. The results of these experiments are discussed in relation to

A. Jensen

1985-01-01

259

Respiratory enzyme activities correlate with anoxia tolerance in salt marsh grasses  

Microsoft Academic Search

Salt marsh communities are known for well-defined species zonation patterns. Lower limits of plant growth are thought to be set by an ability to tolerate anoxic sediments, but the physiological differences between species have not previously been examined. To investigate responses to anoxic sediments, several estuarine species were grown in greenhouse experiments to compare how respiratory processes were affected by

Brian R. Maricle; Jeramiah J. Crosier; Brian C. Bussiere; Raymond W. Lee

2006-01-01

260

REGULATION OF BENTHIC ALGAL AND ANIMAL COMMUNITIES BY SALT MARSH PLANTS: IMPACT OF SHADING  

Microsoft Academic Search

Plant cover is a fundamental feature of many coastal marine and terrestrial systems and controls the structure of associated animal communities. Both natural and human-mediated changes in plant cover influence abiotic sediment properties and thus have cascading impacts on the biotic community. Using clipping (structural) and light (shading) manipulations in two salt marsh vegetation zones (one dominated by Spartina foliosa

Christine R. Whitcraft; Lisa A. Levin

2007-01-01

261

Habitat structure and vegetation relationships in central Argentina salt marsh landscapes  

Microsoft Academic Search

Relationships between habitat structure and spatial variations in vegetation composition were determined in catenas of central Argentina salt marsh landscapes. Vegetation was classified following a multi-technique strategy. An analysis of species distributions along an environmental gradient was made and a redundancy analysis was used to relate the environmental variables to vegetation data. The spatial covariation was evaluated through fractal analysis.

Juan José Cantero; Rolando Leon; José Manuel Cisneros; Alberto Cantero

1998-01-01

262

Physiological Integration among Clonal Ramets during Invasion of Disturbance Patches in a New England Salt Marsh  

Microsoft Academic Search

Resource sharing between ramets growing across environmental resource gradients may have important consequences for clonal plant populations and community dynamics. As the clonal salt marsh grasses, Spartina patens and Distichlis spicata, vegetatively colonize disturbance-generated bare patches, they span steep gradients in soil salinity and available sunlight. Examination of water relations and carbon translocation in the field and greenhouse revealed that

Scott W. Shumway

1995-01-01

263

Effects of nutrient enrichment on Distichlis spicata and Salicornia bigelovii in a marsh salt pan  

Microsoft Academic Search

We investigated how nutrient addition affects the abundance, nutrient storage, and competition between Distichlis spicata and Salicornia bigelovii, two dominant species in salt pans of Northern Gulf of Mexico marshes. Namely, we compared fertilized and unfertilized plots\\u000a in monospecific areas colonized respectively by D. spicata or S. bigelovii, and in a mixed area colonized by the two species. Nutrient addition

Amy Hunter; Nicole M. B. Morris; Céline Lafabrie; Just Cebrian

2008-01-01

264

Quantification of Macrobenthic Effects on Diagenesis Using a Multicomponent Inverse Model in Salt Marsh Sediments.  

National Technical Information Service (NTIS)

Using a multicomponent inverse model, we quantified the rates of organic matter (OM) remineralization and the relative importance of major terminal electron acceptors Fe(III)-(oxy)hydroxides and SO 2/4 in salt marsh sediments with varying degrees of biotu...

Y. Furukawa, A. C. Smith, J. E. Kostka, J. Watkins, C. R. Alexander

2004-01-01

265

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...

266

Cattail invasion and persistence in a coastal salt marsh: The role of salinity reduction  

Microsoft Academic Search

The hypothesis thatTypha domingensis (cattail) can invade tidal marshes only after soil salinities are substantially reduced was tested experimentally by comparing\\u000a the salt tolerance of seeds, seedlings, and plants reared from rhizomes. Germination rates for four southern California populations\\u000a reached 100% in fresh water, decreasing to 2% at 20‰. The salt tolerance of seeds from three coastal populations was lower

Pamela A. Beare; Joy B. Zedler

1987-01-01

267

Effects of increased inundation and wrack deposition on a high salt marsh plant community  

Microsoft Academic Search

Salt marshes respond to both slowly increasing tidal inundation with sea level rise and abrupt disturbances, such as storm-induced\\u000a wrack deposition. The effects of inundation pattern and wrack deposition have been studied independently but not in combination.\\u000a We manipulated inundation of tidal creek water and wrack presence individually and in combination, in two neighboring communities\\u000a within a Virginia high salt

Patricia M. Tolley; Robert R. Christian

1999-01-01

268

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

NASA Astrophysics Data System (ADS)

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 MeHg concentrations are maximal in the top 5-10 cm of soil, right above the transition into high sulfide zones. In contrast to some other marine systems, our initial data reveals high MeHg concentrations (up to 2.5 ng/L) in marsh pore water across a wider range of sulfide concentrations between 5 and 400 uM. The other component of this research is the construction of comprehensive and temporally-intensive water, total mercury, and methylmercury budgets for the salt marsh. This includes local Hg deposition, continuous flow- weighted Hg/MeHg flux measurements through the main tidal channel, monthly Hg/MeHg measurements along a salinity gradient in the adjacent Rhode River, and various other hydrologic and climatologic measurements. Initial results indicate, as expected, that the marsh is a major sink for particulate bound Hg. Linking process scale measurements with larger-scale hydrology is a key step in attributing the source/sink characteristics of the marsh to spatial and temporal variability of processes within it.

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

2007-12-01

269

Pyrite and oxidized iron mineral phases formed from pyrite oxidation in salt marsh and estuarine sediments  

NASA Astrophysics Data System (ADS)

We used scanning electron microscopy and energy dispersive X-ray analysis to examine sediments from vegetated portions of three salt marshes, the Great Sippewissett Marsh (Cape Cod, MA), Sapelo Island (Georgia), and the Hackensack Meadowlands (N.J.), and from the sediments of an estuary, Newark Bay (N.J.). Pyrite particles were abundant in sediments from all sites. Both fine grained pyrite crystals and framboids were found. Single, fine grained crystals (diameter = 0.2 to 2.0 micrometers) predominated in all samples, strong evidence for rapid formation of pyrite. We also found both microcrystalline and framboidal iron-oxyhydroxide phases in many of the sediment samples. This is evidence of pyrite oxidation within the sediments and suggests that iron is conserved in salt marshes even as pyrite is oxidized. The thermodynamic stability of iron phases in marsh sediments, and recent pyrite oxidation studies in coal, suggest goethite as the crystalline iron-oxyhydroxide phase present. In addition, we sometimes found a red amorphous coating on grass roots from the Great Sippewissett and Sapelo Island marshes. This coating is likely a form of hydrated iron (III) oxide.

Luther, George W., III; Giblin, Anne; Howarth, Robert W.; Ryans, Robert A.

1982-12-01

270

Stability of Juncus roemerianus patches in a salt marsh  

Microsoft Academic Search

In a Virginia (USA) marsh undergoing transgression due to rising sea level, we examined the stability of the boundary between\\u000a nearly monotypic patches ofJuncus roemerianus and adjacent plant communities for 6 years. Patch stability was evaluated by examining interannual changes in 5 cover classes:J. roemerianus, Spartina alterniflora, S. patens, Distichlis spicata, and wrack. Patches were chosen at four sites ranging

Mark M. Brinson; Robert R. Christian

1999-01-01

271

Does the invasive plant Elymus athericus modify fish diet in tidal salt marshes?  

NASA Astrophysics Data System (ADS)

The invasion of Mont-Saint-Michel Bay salt marshes (France) by a grass species ( Elymus athericus) has led to important changes in vegetation cover, which is likely to modify the habitat for many invertebrates. Some of them constitute the main food items for several fish species, such as young sea bass ( Dicentrarchus labrax) and sand goby ( Pomatoschistus minutus), that feed in salt marsh creeks during high tides. As a result, fish nursery functions of salt marshes could be modified by the E. athericus invasion. In order to test this hypothesis, gut contents of the two most abundant fish species (sea bass and sand goby) were compared before and after E. athericus invasion in the same salt marsh creek and using the same methodology. The accessibility and availability of the main food item, the semi-terrestrial amphipod Orchestia gammarella, were estimated and compared between invaded (dominated by E. athericus) and original areas (dominated by Atriplex portulacoides). Gut content analysis showed a significantly greater percentage of fish leaving with empty guts from E. athericus areas than from A. portulacoides areas. The sea bass diet composition study showed a major shift in the relative importance of the main food items: before E. athericus invasion, diets were dominated by the semi-terrestrial species O. gammarella, whereas after the E. athericus invasion they were dominated by a marine mysid Neomysis integer. The same trend was found for sand gobies, with a shift of the main food item from O. gammarella before invasion to the polychaete Hediste diversicolor after invasion. These trophic changes may be explained by the lower accessibility and availability of O. gammarella in invaded communities than in natural ones. The E. athericus invasion, observed throughout northern Europe, is thus likely to disturb trophic function of natural salt marshes for fish. This preliminary study of the E. athericus invasion is also an illustration that invasive species are an urgent problem in conservation biology.

Laffaille, P.; Pétillon, J.; Parlier, E.; Valéry, L.; Ysnel, F.; Radureau, A.; Feunteun, E.; Lefeuvre, J.-C.

2005-12-01

272

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

PubMed

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

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

2013-07-01

273

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)

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.

Cooke, John C.; Lefor, Michael W.

1990-01-01

274

Seasonal and topographic variations in porewaters of a southeastern USA salt marsh as revealed by voltammetric profiling+  

PubMed Central

We report electrochemical profiles from unvegetated surficial sediments of a Georgia salt marsh. In creek bank sediments, the absence of ?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 ?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 ?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

Bull, David C; Taillefert, Martial

2001-01-01

275

Impacts of salt marsh plants on tidal channel initiation and inheritance  

NASA Astrophysics Data System (ADS)

Tidal channel networks are the most prominent and striking features visible in tidal wetlands. They serve as major pathways for the exchange of water, sediments, nutrients and contaminants between the wetland and the adjacent open water body. Previous studies identified topography guided sheet flows, as the predominate process for tidal channel initiation. Guided through differences in local topography, sheet flows are able to locally exceed bottom shear stress thresholds, initiating scouring and incision of tidal channels, which then further grow through head ward erosion. The fate of these channels after plant colonization is described in literature as being inherited into the salt marsh through vegetation induced bank stabilization (further referred to as vegetation stabilized channel inheritance). In this study we present a combination of flume experiments and modelling simulations elucidating the impact of vegetation on tidal channel initiation. We first studied the impact of plant properties (stiff: Spartina alterniflora versus flexible: Scirpus mariqueter) on local sediment transport utilizing a flume experiment. Then a coupled hydrodynamic morphodynamic plant growth model was set up to simulate plant colonization by these two different species in the pioneer zone at the mudflat - salt marsh transition. Based on the model we investigated the ramifications of interactions between vegetation, sediment and flow on tidal channel initiation. We specifically compared the effect of vegetation properties (such as stiffness, growth velocity and stress tolerance) on emerging channel patterns, hypothesizing that vegetation mediated channel incision (vegetation induced flow routing and differential sedimentation/erosion patterns leading to tidal channel incision) plays an active role in intertidal landscape evolution. We finally extended our model simulation by imposing pre-existing mudflat channels with different maximum depths, to investigate the impact of existing channels on vegetation mediated channel incision. This simulated landscape development was then compared to aerial photographs from the Scheldt estuary (the Netherlands) and the Yangtze estuary (China). Our results suggest a significant impact of plant properties on tidal channel network emergence, specifically in respect to network drainage density and channel width. This emphasizes the repercussions of vegetation mediated channel incision on estuarine landscape development. Further do our results point to the existence of a threshold in pre-existing mudflat channel depth favoring either vegetation stabilized channel inheritance or vegetation mediated channel incision processes. Increasing depth in mudflat channels favors flow routing via these channels, leaving less flow and momentum remaining for the interaction between vegetation, sediment and flow and therefore vegetation mediated channel incision. This threshold will be influenced by field specific parameters such as hydrodynamics (tidal range, waves, and flow), sediments and predominant plant species. Hence our study not only demonstrates to importance of plant properties on landscape development it also shows that vegetation stabilized channel inheritance or vegetation mediated channel incision are two occurring mechanisms depending on ecosystem properties, adding important information for salt marsh management and conservation.

Schwarz, Christian; Ye, Qinghua; van der Wal, Daphne; Zhang, Liquan; Ysebaert, Tom; Herman, Peter MJ

2013-04-01

276

Influences of Salinity Variations on Pore-water Flow in Salt Marshes  

NASA Astrophysics Data System (ADS)

Salt marshes are important wetlands at the ocean-land interface with various ecological functions, serving as essential habitats for intertidal fauna, affecting the productivity of coastal waters through nutrient exchange, moderating the greenhouse gas emission and global warming. They are influenced by various physical and biogeochemical processes, among which the pore-water flow and associated solute transport processes play an important role in determining the material exchange between marsh soils and coastal water. Previous studies have examined such processes under the solo or combined effects of tidal fluctuation, evapotranspiration, stratigraphy, inland freshwater input, and topography. However, these investigations have neglected the spatial and temporal salinity variations in surface water and pore-water, which commonly exist in salt marshes due to the impacts of tidal inundation, precipitation and evapotranspiration. The density contrast between the surface water and pore-water may lead to significant modifications of the pore-water flow. Based on results from laboratory experiments and numerical simulations, we will demonstrate that: (1) under upward salinity gradients, flow instabilities in the form of fingers occur once the salinity contrast reaches a certain level, whereas under downward salinity gradients the system is stable; (2) because of the strong tidally-induced advective process occurring near the creek, both the number and size of fingers change gradually from the near-creek zone to the marsh interior; and (3) both upward and downward salinity gradients enhance the exchange between the surface water and pore-water in the marsh sediments. Keywords: Salt marshes; density effect; salinity gradient; pore-water flow; fingers. Instabilities under upward salinity gradient Stable system under downward salinity gradient

Shen, C.; Jin, G.; Xin, P.; Li, L.

2013-12-01

277

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

PubMed Central

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

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

1982-01-01

278

Practical proxies for tidal marsh ecosystem services: application to injury and restoration.  

PubMed

Tidal marshes are valued, protected and restored in recognition of their ecosystem services: (1) high productivity and habitat provision supporting the food web leading to fish and wildlife, (2) buffer against storm wave damage, (3) shoreline stabilization, (4) flood water storage, (5) water quality maintenance, (6) biodiversity preservation, (7) carbon storage and (8) socio-economic benefits. Under US law, federal and state governments have joint responsibility for facilitating restoration to compensate quantitatively for ecosystem services lost because of oil spills and other contaminant releases on tidal marshes. This responsibility is now met by choosing and employing metrics (proxies) for the suite of ecosystem services to quantify injury and scale restoration accordingly. Most injury assessments in tidal marshes are triggered by oil spills and are limited to: (1) documenting areas covered by heavy, moderate and light oiling; (2) estimating immediate above-ground production loss (based on stem density and height) of the dominant vascular plants within each oiling intensity category and (3) sampling sediments for chemical analyses and depth of contamination, followed by sediment toxicity assays if sediment contamination is high and likely to persist. The percentage of immediate loss of ecosystem services is then estimated along with the recovery trajectory. Here, we review potential metrics that might refine or replace present metrics for marsh injury assessment. Stratifying plant sampling by the more productive marsh edge versus the less accessible interior would improve resolution of injury and provide greater confidence that restoration is truly compensatory. Using microphytobenthos abundance, cotton-strip decomposition bioassays and other biogeochemical indicators, or sum of production across consumer trophic levels fails as a stand-alone substitute metric. Below-ground plant biomass holds promise as a potential proxy for resiliency but requires further testing. Under some conditions, like chronic contamination by organic pollutants that affect animals but not vascular plants, benthic infaunal density, toxicity testing, and tissue contamination, growth, reproduction and mortality of marsh vertebrates deserve inclusion in the assessment protocol. Additional metrics are sometimes justified to assay microphytobenthos, use by nekton, food and habitat for reptiles, birds and mammals, or support of plant diversity. Empirical research on recovery trajectories in previously injured marshes could reduce the largest source of uncertainty in quantifying cumulative service losses. PMID:18929066

Peterson, Charles H; Able, Kenneth W; Dejong, Christin Frieswyk; Piehler, Michael F; Simenstad, Charles A; Zedler, Joy B

2008-01-01

279

Exchanges and photo-biogeochemical transformation of dissolved organic compounds in Eastern US tidal marsh ecosystems.  

NASA Astrophysics Data System (ADS)

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.

Tzortziou, Maria; Neale, Patrick; Megonigal, Patrick; Butterworth, Megan; Jaffe, Rudolf

2010-05-01

280

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...

281

Nitrogen cycle of a typical Suaeda salsa marsh ecosystem in the Yellow River estuary  

Microsoft Academic Search

The nitrogen (N) biological cycle of the Suaeda salsa marsh ecosystem in the Yellow River estuary was studied during 2008 to 2009. Results showed that soil N had significant seasonal fluctuations and vertical distribution. The N\\/P ratio (15.73±1.77) of S. salsa was less than 16, indicating that plant growth was limited by both N and R The N absorption coefficient

Xiaojie Mou; Zhigao Sun; Lingling Wang; Chuanyuan Wang

2011-01-01

282

Modification of Sediments and Macrofauna by an Invasive Marsh Plant  

Microsoft Academic Search

Invasive grasses have recently altered salt marsh ecosystems throughout the northern hemisphere. On the eastern seaboard of\\u000a the USA, Phragmites australis has invaded both brackish and salt marsh habitats. Phragmites australis influence on sediments and fauna was investigated along a salinity and invasion-age gradient in marshes of the lower Connecticut\\u000a River estuary. Typical salinities were about 19–24?ppt in Site I,

T. S. Talley; L. A. Levin

2001-01-01

283

MARSH INSITU EH DATA FOR SOUTH FLORIDA ECOSYSTEM ASSESSMENT PROJECT  

EPA Science Inventory

The South Florida Ecosystem Assessment Project is an innovative, large-scale monitoring and assessment program designed to measure current and changing conditions of ecological resources in South Florida using an integrated holistic approach. This data set contains results for f...

284

The effects of decreased management on plant-species distribution patterns in a salt marsh nature reserve in the Wadden Sea  

Microsoft Academic Search

To restore natural salt-marsh habitats, maintenance of the artificial drainage system was discontinued and cattle grazing was reduced in man-made salt marshes in the Dollard estuary, the Netherlands. We studied the vegetation development in these marshes shortly after these marshes became a nature reserve, and again 8–9 years later. Cattle distribution showed a gradient of intensive use close to the

Peter Esselink; Wiebo Zijlstra; Kees S. Dijkema; Rudy van Diggelen

2000-01-01

285

Effects of Life History Strategy on Fish Distribution and Use of Estuarine Salt Marsh and Shallow-Water Flat Habitats  

Microsoft Academic Search

To assess the potential for habitat isolation effects on estuarine nekton, we used two species with different dispersal abilities\\u000a and life history strategies, mummichog (Fundulus heteroclitus) and pinfish (Lagodon rhomboides) to examine: (1) distribution trends among estuarine shallow-water flat and various intertidal salt marsh habitats and (2)\\u000a the influence of salt marsh habitat size and isolation. Collections were conducted using

David L. Meyer; Martin H. Posey

2009-01-01

286

Sediment quality assessment in tidal salt marshes in northern California, USA: An evaluation of multiple lines of evidence approach  

USGS Publications Warehouse

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.

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

287

Sediment quality assessment in tidal salt marshes in northern California, USA: an evaluation of multiple lines of evidence approach.  

PubMed

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. PMID:23542672

Hwang, Hyun-Min; Carr, R Scott; Cherr, Gary N; Green, Peter G; Grosholz, Edwin D; Judah, Linda; Morgan, Steven G; Ogle, Scott; Rashbrook, Vanessa K; Rose, Wendy L; Teh, Swee J; Vines, Carol A; Anderson, Susan L

2013-06-01

288

Beneath the Salt Marsh Canopy: Loss of Soil Strength with Increasing Nutrient Loads  

Microsoft Academic Search

Although the broadly observed increase in nutrient loading rates to coastal waters in the last 100 years may increase aboveground\\u000a biomass, it also tends to increase soil metabolism and lower root and rhizome biomass—responses that can compromise soil strength.\\u000a Fourteen different multiyear field combinations of nutrient amendments to salt marshes were made to determine the relationship\\u000a between soil strength and various

R. Eugene Turner

2011-01-01

289

OCS, H2S, and CS2 fluxes from a salt water marsh  

Microsoft Academic Search

The diurnal-to-monthly behavior of the fluxes of OCS, H2S, and CS2 from a mixed-Spartina grass-covered site in a Wallops Island salt water marsh was determined through a series of experiments in August and September, 1982. Absolute flux values were determined for OCS and H2S, while only relative values were determined for CS2. The rates of emission of OCS and H2S

Mary Anne Carroll; Leroy E. Heidt; Ralph J. Cicerone; Ronald G. Prinn

1986-01-01

290

Twenty years of salt marsh succession on a Dutch coastal barrier island  

Microsoft Academic Search

After a formerly grazed salt marsh was released from cattle grazing, changes in plant species composition were monitored for\\u000a 20 yr, using vegetation maps and permanent plots. Three areas, differing in age and nutrient status were compared. The number\\u000a of plant species and plant communities decreased.Elymus athericus (Elytrigia pungens) became dominant in most plant communities after 5–20 yr on the

H. J. van Wijnen; J. P. Bakker; Y. de Vries

1997-01-01

291

Inundation Frequency Determines the Post-Pioneer Successional Pathway in a Newly Created Salt Marsh  

Microsoft Academic Search

The effect of inundation frequency on plant community composition, species turnover, total and growth form cover, species\\u000a richness, and abundance of individual species was investigated in a newly created salt marsh (Belgium) with a gradient of\\u000a inundation frequencies from 0.01% to 100%. Cover of all plant species was estimated in 119 permanent 2?×?2 m plots along seven\\u000a randomly chosen transects perpendicular

Julien Pétillon; Reza Erfanzadeh; Angus Garbutt; Jean-Pierre Maelfait; Maurice Hoffmann

2010-01-01

292

Dynamics of potential waterfowl foods in great salt lake marshes during summer  

Microsoft Academic Search

Changes in biomass of potential waterfowl foods were investigated in Great Salt Lake marshes during July and August of 1988–89.\\u000a In freshwater habitats, biomass of midge (Chironomidae) larvae and pupae and water boatman (Corixidae) nymphs declined from\\u000a early to late summer. Biomass of mayfly (Ephemeroptera) and damselfly (Zygoptera) nymphs increased over the same time interval.\\u000a Seeds of horned pondweed (Zannichellia

Robert R. Cox; John A. Kadlec

1995-01-01

293

Temporal and Spatial Relationships Between Watershed Land Use and Salt Marsh Disturbance in a Pacific Estuary  

Microsoft Academic Search

Historical and recent remote sensing data can be used to address temporal and spatial relationships between upland land cover\\u000a and downstream vegetation response at the watershed scale. This is demonstrated for sub-watersheds draining into Elkhorn Slough,\\u000a California, where salt marsh habitat has diminished because of the formation of sediment fans that support woody riparian\\u000a vegetation. Multiple regression models were used

Kristin B. Byrd; N. Maggi Kelly; Adina M. Merenlender

2007-01-01

294

Characterization of Methanococcus maripaludis sp. nov., a new methanogen isolated from salt marsh sediment  

Microsoft Academic Search

A predominant methanogenic bacterium was isolated from salt-marsh sediment near Pawley's Island, South Carolina. A habitat-simulating medium with H2:CO2 as substrate was used for enrichment and isolation. The methanogen is strictly anaerobic, weakly-motile, non-sporeforming, Gram negative, and a pleomorphic coccoid-rod averaging 1.2 by 1.6 µm. Colonies are circular, translucent, pale yellow, and have a smooth surface and an entire edge.

W. Jack Jones; M. J. B. Paynter; R. Gupta

1983-01-01

295

Mineralization of Clapper Rail Eggshell from a Contaminated Salt Marsh System  

Microsoft Academic Search

The effect of contamination on eggshell mineralization has been studied for clapper rails (Rallus longirostris) inhabiting a contaminated salt marsh in coastal Georgia. To assess the impact of contaminants, the thickness, microstructure\\u000a (crystal orientation), mineral composition, and chemistry of shell material were analyzed from a contaminated site and a nearby\\u000a reference site using optical microscopy, X-ray diffraction, inductively coupled plasma

Alejandro Rodriguez-Navarro; Karen F. Gaines; Christopher S. Romanek; G. R. Masson

2002-01-01

296

Archaeal diversity and the prevalence of Crenarchaeota in salt marsh sediments.  

PubMed

Crenarchaeal 16S rRNA sequences constituted over 70% of the archaeal clones recovered from three salt marsh sites dominated by different grasses. Group I.1a Crenarchaeota dominated at two sites, while group I.3b Crenarchaeota sequences were most abundant at a third site. Abundances of 16S rRNA genes related to "Candidatus Nitrosopumilus maritimus" differed by site and sampling date. PMID:19395565

Nelson, Katelyn A; Moin, Nicole S; Bernhard, Anne E

2009-06-01

297

Damage to cordgrass by scale insects in a constructed salt marsh: Effects of nitrogen additions  

Microsoft Academic Search

Because tall cordgrass (Spartina foliosa) is needed for nesting by the endangered light-footed, clapper rail, managers of constructed salt marshes in southern California\\u000a are proposing large-scale nitrogen fertilization to improve cordgrass growth. How this might affect an existing infestation\\u000a of scale insects (Haliaspis spartina) and the degree of damage these insects cause to their cordgrass hosts was unknown. We explored

Katharyn E. Boyer; Joy B. Zedler

1996-01-01

298

Catastrophic events reveal the dynamic nature of salt-marsh vegetation in Southern California  

Microsoft Academic Search

Recent hydrological disturbances, including flooding, dry-season streamflow, and drought, greatly altered coastal wetland\\u000a habitats in sourthern California. At Tijuana Estuary, a six-year study of salt-marsh vegetation patterns during these rare\\u000a conditions documented substantial temporal variability in plant growth and distribution. Important to cordgrass (Spartina foliosa Trin.) dynamics were the amount and timing of streamflows, which reduced soil salinity and alleviated

Joy B. Zedler; Jordan Covin; Chris Nordby; Phil Williams; John Boland

1986-01-01

299

Nesting habitat of Belding’s Savannah sparrows in coastal salt marshes  

Microsoft Academic Search

Although the Belding’s Savannah sparrow (Passerculus sandwichensis beldingl) is listed as endangered in California, little is known about the factors that affect its abundance and distribution. Numbers\\u000a of breeding pairs, nesting territory sizes, and vegetation characteristics were measured at fourteen study plots in two southern\\u000a California coastal wetlands, Tijuana Estuary and Los Peñasquitos Lagoon. Sparrows nested in middle salt marsh

Abby N. Powell

1993-01-01

300

LATITUDINAL VARIATION IN PALATABILITY OF SALT-MARSH PLANTS: ARE DIFFERENCES CONSTITUTIVE?  

Microsoft Academic Search

Biogeographic theory argues that consumer-prey interactions are more in- tense, and prey defenses better developed, at lower latitudes. Along the Atlantic Coast of the United States, low-latitude salt marsh plants are less palatable than high-latitude con- specifics. To test the hypothesis that latitudinal variation in palatability would occur in the absence of geographically different environmental cues (i.e., that differences in

Cristiano S. Salgado; Steven C. Pennings

2005-01-01

301

Restoring assemblages of salt marsh halophytes in the presence of a rapidly colonizing dominant species  

Microsoft Academic Search

Establishing species-rich plant communities is a common goal of habitat restoration efforts, but not all species within a\\u000a target assemblage have the same capacity for recruitment and survival in created habitats. We investigated the development\\u000a of a tidal salt marsh plant community in the presence of a rapidly colonizing dominant species, Salicornia virginica, in a newly created habitat in Mugu

Anna R. Armitage; Katharyn E. Boyer; Richard R. Vance; Richard F. Ambrose

2006-01-01

302

Home ranges of brown hares in a natural salt marsh: comparisons with agricultural systems  

Microsoft Academic Search

This is the first study on spatial behaviour of brown haresLepus europaeus Pallas, 1778 based on radio-telemetry in a natural system, which we contrast with data from agricultural systems. Radio tracking\\u000a took place in a Dutch salt marsh over a 10-month period, with intensive tracking sessions during April\\/May and December\\/January.\\u000a Six hares could be followed in both periods and in

Peter J. G. Kunst; René van der Wal; Sip van Wieren

2001-01-01

303

Below and Aboveground Spartina alterniflora Production in a Louisiana Salt Marsh  

Microsoft Academic Search

The monthly variations of below- and aboveground biomass of Spartina alterniflora were documented for a south Louisiana salt marsh from March 2004 to March 2005, and in March 2006 and 2007. The annual production\\u000a rate above- and belowground was 1821 and 11,676 g m?2, respectively (Smalley method), and the annual production rate per biomass belowground was 10.7 g dry weight?1, which are

Faith A. Darby; R. Eugene Turner

2008-01-01

304

Below and Aboveground Biomass of Spartina alterniflora : Response to Nutrient Addition in a Louisiana Salt Marsh  

Microsoft Academic Search

The responses of Spartina alterniflora above- and belowground biomass to various combinations of N, P, and Fe were documented in a 1-year field experiment in a\\u000a Louisiana salt marsh. Five levels of N additions to 0.25 m2 plots resulted in 18% to 138% more live aboveground biomass compared to the control plots and higher stem densities, but\\u000a had no effect on

Faith A. Darby; R. Eugene Turner

2008-01-01

305

The Ecological Society of America wwwwww..ffrroonnttiieerrssiinneeccoollooggyy..oorrgg Tidal wetlands such as salt, brackish, and freshwater  

E-print Network

wetlands such as salt, brackish, and freshwater marshes provide essential ecosystem services to soci- ety to provide ecosystem ser- vices associated with waste treatment, biological produc- tivity, and disturbance migration, as salt marshes transgress landward and replace tidal freshwater and brackish marshes (Park et al

Craft, Christopher B.

306

Tidal Flooding and Vegetation Patterns in a Salt Marsh Tidal Creek Imaged by Low-altitude Balloon Aerial Photography  

NASA Astrophysics Data System (ADS)

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 soil water content. These other factors are all directly affected by the hydroperiod, creating a complex system of feedbacks. Inundation frequencies show a pronounced relationship to zonation. Creek bank height and the hydroperiod have a curvilinear relationship at low bank heights such that small decreases in creek bank height can result in large increases in inundation frequency. Biological zonation is not simply a result of bank height and inundation frequency, other contributing factors include species competition, adaptability, and groundwater flow. Vegetation patterns delineated by a ground-based GPS survey and image classification from the aerial photos show that not all changes in eco-zonation are a direct function of elevation. Some asymmetry across the creek is observed in plant habitat, and eliminating topography (and thereby tidal inundation) as a factor, we attribute the remaining variability to groundwater flow.

White, S. M.; Madsen, E.

2013-12-01

307

Evaluation of the ability of two plants for the phytoremediation of Cd in salt marshes  

NASA Astrophysics Data System (ADS)

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.

Nunes da Silva, Marta; Mucha, Ana P.; Rocha, A. Cristina; Silva, Carla; Carli, Carolina; Gomes, Carlos R.; Almeida, C. Marisa R.

2014-03-01

308

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

NASA Astrophysics Data System (ADS)

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 carbon source for stimulating sulfate-reducing bacteria. The high sulfur levels, coupled with the low levels of iron, indicate that iron-reducing bacteria are outcompeted by sulfate reducers in oiled salt marshes. Moreover, pore-water pH values show a general increasing trend (ranging from 6.6 to 8.0) with depth, possibly reflecting the combined effects of bacterial sulfate reduction and saltwater intrusion at depth. Despite high levels of trace metals in bulk sediments, concentrations of trace metals dissolved in pore-waters are generally low. It is very likely that high organic matter content and bacterially-mediated sulfate reduction promote metal retention through the formation of sulfide solids. Framboidal pyrites, as well as other sulfides, have been identified, and are currently undergoing XRD, SEM, and EDAX analyses. Continued research is needed to monitor possible re-mobilization of trace metals in changing redox and biogeochemical conditions.

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

2011-12-01

309

GEOLOGY, May 2011 511 Salt marshes occur extensively along mid-  

E-print Network

in the Chesapeake Bay was elevated by an order of magnitude over background rates due to European settlement valuable ecosystem services such as filtering pollutants, attenuat- ing waves during storms, enhancing,000 ha in the San Fran- cisco Bay (Gedan et al., 2009, and references therein) and approximately 4000 km2

310

Tracer analysis of methanogenesis in salt marsh soils.  

PubMed

Differences in paths of carbon flow have been found in soils of the tall (TS) and short (SS) Spartina alterniflora marshes of Sapelo Island, Ga. Gaseous end products of [U-C]glucose metabolism were CO(2) and CH(4) in the SS region and primarily CO(2) in the TS region. Sulfate concentration did not demonstrably affect glucose catabolism or the distribution of end products in either zone. [U-C]acetate was converted to CO(2) and CH(4) in the SS soils and almost exclusively to CO(2) in the TS soils. Sulfate concentration did not affect acetate metabolism in the SS soils; however, a noticeable effect of sulfate dilution was seen in TS soils. Sulfate dilution in TS samples resulted in increased methane formation. Total glucose and acetate metabolism were similar in TS and SS soils despite differences in end products. A microbial community characterized by fermentative/sulfate-reducing processes has developed in TS soils as opposed to the fermentative/methanogenic/sulfate-reducing community found in SS soils. PMID:16345551

King, G M; Wiebe, W J

1980-04-01

311

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)

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 investigated in a one year laboratory experiment. Microbial organic matter mineralization to CO2 increased following simulated SWI. This was linked to greater availability of sulfate (SO42-) and higher rates of microbial sulfate reduction, resulting in significantly greater flux of CO2 from TFM soils. Rates of CH4 release were also significantly greater from soils following SWI, and microbial acetoclastic methanogensis was not inhibited by the introduction of salt-water, supporting findings from the field measurements. Higher rates of microbial organic matter mineralization via both sulfate reduction and methanogenesis resulted in declining soil organic matter following SWI. A multi-year field manipulation utilizing modified marsh ';organs' to examine the interactive effects of both SWI and SLR indicated that, while N2O emissions decreased with flooding (-0.3 g m-2 yr-1 cm-1), rates of CH4 flux increased with flooding (2.3 g m-2 yr-1 cm-1) corresponding to measured increases in microbial methanogenesis and resulting in a net increase in GHG release. There were complex interactions between changes in plant production and microbial organic matter decomposition with both SLR and SWI, and TFMs experiencing both SLR and SWI simultaneously had reduced C sequestration and increased GHG release. SLR and SWI therefore limit the vertical accretion potential of TFMs, put TFMs at risk of permanent submergence, and produce a feedback to atmospheric GHG concentrations.

Weston, N. B.

2013-12-01

312

Factors influencing algal biomass in hydrologically dynamic salt ponds in a subtropical salt marsh  

E-print Network

realized, underscoring the importance of understanding algal dynamics in such systems. Benthic and planktonic chlorophyll-a (surrogate for total algal biomass), sediment AFDW, total suspended solids, salinity, and nutrients were examined in marsh ponds...

Miller, Carrie J.

2009-05-15

313

Populations of methane-producing bacteria and in vitro methanogenesis in salt marsh and estuarine sediments.  

PubMed

Most probable numbers (MPNs) of methanogens in various salt marsh and estuarine sediments were determined with an anaerobic, habitat-simulating culture medium with 80% H(2) plus 20% CO(2) as substrate. Average MPNs for the short Spartina (SS) marsh sediments of Sapelo Island, Ga., were maximal at the 5- to 7-cm depth (1.2 x 10/g of dry sediment). Populations decreased to approximately 880/g of dry sediment at the 34- to 36-cm depth. There was no significant difference between summer and winter populations. In tall Spartina (TS) marsh sediments, average populations were maximal (1.2 x 10/g of dry sediment) in the upper 0- to 2-cm zone; populations from the 5- to 36-cm zones were similar (average of 9 x 10/g of dry sediment). Methanogenic populations for TS sediments of James Island Creek marsh, Charleston, S.C., were similar (average of 3 x 10/g of dry sediment) for all depths tested (0 to 22 cm), which was comparable to the trend observed for TS sediments at Sapelo Island, Ga. Sediment grab samples collected along a transect of James Island Creek and its adjacent Spartina marsh had MPNs that were approximately 20 times greater for the region of Spartina growth (average of 10/g of dry sediment) compared with the channel (approximately 5 x 10 methanogens per g of dry sediment). A similar trend was found at Pawley's Island marsh, S.C., but populations were approximately one order of magnitude lower. In vitro rates of methanogenesis with SS sediments incubated under 80% H(2)-20% CO(2) showed that the 5- to 7-cm region exhibited maximal activity (51 nmol of CH(4) g h), which was greater than rates for sediments above and below this depth. SS sediment samples (5 to 7 cm) incubated under 100% N(2) and supplemented with formate exhibited rates of methanogenesis similar to those generated by samples under 80% H(2)-20% CO(2). Replacing the N(2) atmosphere with H(2) resulted in an eightfold decrease in the rate of methanogenesis. In vitro methanogenic activity by TS salt marsh sediments, incubated under 80% H(2)-20% CO(2), was similar for all depths tested (0 to 22 cm). TS sediment samples (0 to 7 cm) supplemented with formate and incubated under 100% N(2) had greater rates of methanogenesis compared with unsupplemented samples. PMID:16345550

Jones, W J; Paynter, M J

1980-04-01

314

Joint Geophysical and Hydrologic Constraints on Shallow Groundwater Flow Systems in Clastic Salt Marshes of the South Atlantic Bight  

NASA Astrophysics Data System (ADS)

Salt marsh systems play a critical role in buffering upland coastal areas from the influence of open saltwater bodies and in filtering contaminants that originate offshore or are flushed from uplands. For these reasons, it is important to understand the salt marsh hydrologic cycle, especially the interaction of groundwater and surface water across low-lying coastal fringes and the changes in physical, chemical, and ecological parameters across salinity gradients extending from upland to tidal creek to open water. For the past 5 years, we have conducted hydrogeophysical surveys (inductive EM and DC resistivity) and collected limited, coincident groundwater hydrologic data in clastic salt marshes throughout the South Atlantic Bight (SAB), stretching from South Carolina on the north to the Georgia-Florida border on the south. All of the marshes are dominated by Spartina and Juncus grasses and are cut by tidally-influenced creeks, but both the lithology and age of the marshes vary widely. For example, one highly homogeneous marsh study site has formed only within the past century, while most sites have existed for thousands of years and have laterally and vertically heterogeneous lithology. Geophysical images of the marsh subsurface and coincident monitoring of groundwater temperature, water level, and/or chemistry consistently show that marshes in the mixed energy environment of the middle part of the SAB (GCE LTER) tend to be dominated by submarsh discharge of freshwater to adjacent tidal creeks. In the South Carolina part of the SAB, we have greater evidence for seepage, particularly through biologically-created macropore networks and permeable sediment bodies that intersect tidal creeks. It is possible though that the South Carolina results are not so much 'universal' as reflective of local lithology. In a very young marsh near the Florida border, geophysical imaging implies a mixture of seepage and submarsh flow, and hydrologic data provide unequivocal proof that the near-surface marsh muds act as a low permeability barrier to downward penetration of tidal creek surface waters during periodic inundation of the marsh. Taken together, the results imply that subsurface freshwater bodies flowing beneath some salt marshes act as extensions of the classic freshwater lens that develops beneath uplands and help to resist saline intrusion toward uplands. Certain factors allow us to predict the occurrence of seepage, instead of submarsh flow, in SAB salt marshes with some degree of confidence. Where we have acquired time series, both the hydrogeophysical and hydrologic data suggest that groundwater transport processes are at approximate steady-state at the length scales (vertical and horizontal) and over the duration of our measurements.

Ruppel, C.; Fulton, P.; Schultz, G. M.; Castillo, L.; Bartlett, J.; Sibley, S.

2005-12-01

315

Early diagenesis of lignin-associated phenolics in the salt marsh grass Spartina alterniflora  

SciTech Connect

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.

Haddad, R.I.; Martens, C.S. (Univ. of North Carolina, Chapel Hill (United States)); Newell, S.Y. (Univ. of Georgia Marine Inst., Sapelo Island (United States)); Fallon, R.D. (DuPont Co., Wilmington, DE (United States))

1992-10-01

316

Early diagenesis of lignin-associated phenolics in the salt marsh grass Spartina alterniflora  

NASA Astrophysics Data System (ADS)

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 ± 2% and 25 ± 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. The most labile component, trans-ferulic acid, accounted for 57% and 82% of the total lignin loss in the litterbag and tagged studies, respectively, based on normalization to syringyl-phenol concentrations. Comparison of these two data sets supports the following approximate lignin stability sequence for S. alterniflora:S ? Ca ? V > P > Fa. 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, we 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.

Haddad, R. I.; Newell, S. Y.; Martens, C. S.; Fallon, R. D.

1992-10-01

317

Potential uses of TerraSAR-X for mapping herbaceous halophytes over salt marsh and tidal flats  

NASA Astrophysics Data System (ADS)

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.

Lee, Yoon-Kyung; Park, Jeong-Won; Choi, Jong-Kuk; Oh, Yisok; Won, Joong-Sun

2012-12-01

318

Magnitudes and spatial and temporal patterns of self-organized processes between geomorphology and biota that drive salt marsh evolution  

NASA Astrophysics Data System (ADS)

Many complex systems show non-equilibrium fluctuations, often determining the spontaneous evolution towards a critical state. In this context salt marshes are known to be characterized by complex patterns in both geomorphological and ecological features, which often appear to be strongly correlated. One of the main drivers on low-order channel network geometry is the hydrodynamic forcing entering the system in the form of an intermittent stress: the occurrence of infrequent rainfall events determines saturation-excess overland flow, which results in higher stream energy to be dissipated through an increase in cross section and meandering of the tidal channels in the marsh. This external driver determines a second, important effect on the intertidal zone: together with the emergence of a higher number of minor draining channels, salt marshes are provided with pulses of sediment input, causing a vertical build-up that allows pioneer species to colonize new areas of mudflat and channels. This eventually leads to salt marsh development through the higher frequency of occurrence and horizontal spread of marsh pioneer patterns, coupled with the displacement of the limit between the salt marsh and mudflat. As opposed to infrequent events, a much more frequent source of variation and uncertainty affecting the system is the difference between the observed and astronomical tide, which is referred to as surge. Since it would be difficult to simultaneously monitor these parameters through field surveys, and even harder to analyze them over medium to large time scales, we propose a remote sensing approach to monitor the temporal dynamics of both biotic and abiotic factors in salt marshes. We characterized the complex interactions between morphology and biota in two salt marshes in the densely populated Scheldt estuary through the implementation of different algorithms on multispectral endmember fraction maps from optical space-borne remote sensing. Multitemporal fractional abundance maps spanning from 1986 to 2011 were used to identify the interaction between vegetation pattern dynamics and channel drainage density, and integrated with field sampling and in situ spectroradiometry. The objectives were to: a) analyze and validate the processing procedure used to define the patterns of macrophyte vegetation cover; b) obtain field data on microphytobenthos biomass in two intertidal mudflat areas differing in the degree of sediment cohesiveness; c) integrate spectroradiometric measurements with simultaneous sampling; d) build a spectral library of salt marsh vegetation composition and zonation of Northern Europe estuarine areas. The latter can then be compared with vegetation field sampling data already available on the Plymouth estuary, Po Delta and Venice lagoon, in order to support the classification of the different surface cover types for the development of new methods of monitoring salt marsh-mudflat systems.

Cornacchia, L.; Taramelli, A.; Valentini, E.; Monbaliu, J. A.; Sabbe, K.

2012-12-01

319

Estimating shallow subsidence in microtidal salt marshes of the southeastern United States: Kaye and Barghoorn revisited  

USGS Publications Warehouse

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.

Cahoon, D.R.; Reed, D.J.; Day, J.W., Jr.

1995-01-01

320

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

NASA Astrophysics Data System (ADS)

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.

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

2008-10-01

321

Source reduction in Florida's salt marshes: management to reduce pesticide use and enhance the resource.  

PubMed

Source reduction as part of an integrated pest management program is a cornerstone of the American Mosquito Control Association's Pesticide Environmental Stewardship Program Strategy Document to reduce pesticide risk. Since the early 1980s, Florida has made important strides in implementing environmentally sound source reduction strategies in salt marshes while managing them for both mosquito control and natural resource enhancement. The political mechanism for this progress has been interagency cooperation through the Florida Coordinating Council on Mosquito Control and its Subcommittee on Managed Marshes. Challenges in accomplishing source reduction continue because both public and private lands are involved. Public lands include those owned by federal (e.g., U.S. Fish and Wildlife Service, National Park Service), state (Florida Department of Environmental Protection), and local governments, and they have a diversity of management objectives. This diversity adds to the challenge facing mosquito control agencies in providing mosquito control services while protecting and enhancing the environment. PMID:17067058

Carlson, Douglas B

2006-09-01

322

Alteration of a Salt Marsh Bacterial Community by Fertilization with Sewage Sludge  

PubMed Central

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

Hamlett, Nancy V.

1986-01-01

323

Accumulation of COGEMA-La Hague-derived reprocessing wastes in French salt marsh sediments.  

PubMed

Over the past five decades, authorized low-level discharges from coastal nuclear facilities have released significant quantities of artificial radionuclides into the marine environment. In northwest Europe, the majority of the total discharge has derived from nuclear reprocessing activities at Sellafield in the United Kingdom and COGEMA-La Hague in France. At the Sellafield site, a significant amount of the discharges has been trapped in offshore fine sediment deposits, and notably in local coastal and estuarine sediments, and much research has been focused on understanding the distribution, accumulation, and reworking of long-lived radionuclides in these deposits. In contrast, there are few high-resolution published data on the vertical distribution of radionuclides in fine-grained estuarine sediments near, and downstream of, COGEMA-La Hague. This paper therefore examines the vertical distribution of a range of anthropogenic radionuclides in dated salt marsh cores from two estuaries, one adjacent to, and the other downstream of, the COGEMA-La Hague discharge point (the Havre de Carteret at Barneville-Carteret and the Baie de Somme, respectively). The radionuclides examined show a vertical distribution which predominantly reflects variations in input from COGEMA-La Hague (albeit much more clearly at Barneville-Carteret than at the Baie de Somme site), and Pu isotopic ratios are consistent with a La Hague, rather than weapons' fallout, source. Because of sediment mixing, the marshes apparently retain an integrated record of the La Hague discharges, rather than an exact reproduction of the discharge history. Sorption of radionuclides increases in the order 90Sr < 137Cs < 60Co < 239,240Pu, which is consistent with Kd values reported in the literature. In general, the radionuclide activities observed at the sites studied are low (particularly in comparison with salt marsh sediments near the Sellafield facility), but are similar to those found in areas of fine sedimentation in the central Channel. These marshes are not major sinks for discharged reprocessing wastes. PMID:12523411

Cundy, Andrew B; Croudace, Ian W; Warwick, Phillip E; Oh, Jung-Suk; Haslett, Simon K

2002-12-01

324

Primary production of edaphic algal communities in a Mississippi salt marsh  

SciTech Connect

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.

Sullivan, M.J.; Moncreiff, C.A.

1988-03-01

325

Ecosystem response to changes in water level of Lake Ontario marshes: lessons from the restoration of Cootes Paradise Marsh  

Microsoft Academic Search

A general understanding of how aquatic vegetation responds to water-level fluctuations is needed to guide restoration of Great Lakes coastal wetlands because inter-annual and seasonal variations often confound effects of costly remedial actions. In 1997, common carp (Cyprinus carpio) was removed from Cootes Paradise Marsh (L. Ontario) to reduce sediment resuspension and bioturbation, and thus regenerate marsh plants that had

Patricia Chow-Fraser

2005-01-01

326

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

NASA Astrophysics Data System (ADS)

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.

Goudie, Alice

2013-09-01

327

A comparison of bird use and species diversity of created and natural salt marshes in the Galveston Bay complex, Texas  

E-print Network

(Webb and Dodd 1983, Webb and Newling 1985, Webb pers. comm): 1) dredged material from channels deposited in intertidal shallow water locations 2) shoreline locations with natural substrate 3) upland areas which are cut down to lower elevation... in natural systems. Salt marshes have been created for a variety of reasons. Historically, they were designed to beneficially use dredge material, expand wetland area, and control erosion on exposed shorelines (Chabreck 1990). Experimental marshes have...

Melvin, Stefani Lynn

2012-06-07

328

Pyrolysis-gas chromatography\\/mass spectrometry of soil organic matter extracted from a Brazilian mangrove and Spanish salt marshes  

Microsoft Academic Search

The soil organic matter (SOM) extracted under different vegetation types from a Brazilian mangrove (Pai Matos Island, São Paulo State) and from three Spanish salt marshes (Betanzos Ría and Corrubedo Natural Parks, Galícia, and the Albufera Natural Park, Valencia) was investigated by pyrolysis-gas chromatography\\/mass spectrometry (Py-GC\\/MS). The chemical variation was larger in SOM from the Spanish marshes than in the

Fernando Perobelli Ferreira; P. Buurman; F. Macias; X. L. Otero; R. Boluda

2009-01-01

329

Distribution and diversity of archaeal and bacterial ammonia oxidizers in salt marsh sediments.  

PubMed

Diversity and abundance of ammonia-oxidizing Betaproteobacteria (beta-AOB) and archaea (AOA) were investigated in a New England salt marsh at sites dominated by short or tall Spartina alterniflora (SAS and SAT sites, respectively) or Spartina patens (SP site). AOA amoA gene richness was higher than beta-AOB amoA richness at SAT and SP, but AOA and beta-AOB richness were similar at SAS. beta-AOB amoA clone libraries were composed exclusively of Nitrosospira-like amoA genes. AOA amoA genes at SAT and SP were equally distributed between the water column/sediment and soil/sediment clades, while AOA amoA sequences at SAS were primarily affiliated with the water column/sediment clade. At all three site types, AOA were always more abundant than beta-AOB based on quantitative PCR of amoA genes. At some sites, we detected 10(9) AOA amoA gene copies g of sediment(-1). Ratios of AOA to beta-AOB varied over 2 orders of magnitude among sites and sampling dates. Nevertheless, abundances of AOA and beta-AOB amoA genes were highly correlated. Abundance of 16S rRNA genes affiliated with Nitrosopumilus maritimus, Crenarchaeota group I.1b, and pSL12 were positively correlated with AOA amoA abundance, but ratios of amoA to 16S rRNA genes varied among sites. We also observed a significant effect of pH on AOA abundance and a significant salinity effect on both AOA and beta-AlphaOmicronBeta abundance. Our results expand the distribution of AOA to salt marshes, and the high numbers of AOA at some sites suggest that salt marsh sediments serve as an important habitat for AOA. PMID:19801456

Moin, Nicole S; Nelson, Katelyn A; Bush, Alexander; Bernhard, Anne E

2009-12-01

330

Assessment of Hydraulic Restoration of San Pablo Marsh, California  

Microsoft Academic Search

Inter-tidal marshes are dynamic diverse ecosystems at the transition zone between terrestrial and ocean environments. Geomorphologically, inter-tidal salt marshes are vegetated landforms at elevations slightly greater than mean tidal levels that have distributed channels formed under ebb (drainage) tidal flows that widen and deepen in the seaward direction. The drainage channels enable tidal flows to circulate sediments and nutrients through

Mark E. Grismer; J. Kollar; J. Syder

2004-01-01

331

Nekton utilization of intertidal salt marsh creeks: Tidal influences in natural Spartina, invasive Phragmites, and marshes treated for Phragmites removal  

Microsoft Academic Search

Intertidal creeks provide an extensive and direct interface with the marsh surface during periods of tidal inundation, and as such they represent a critically important corridor between the marsh surface and subtidal habitats. However, invasion by Phragmites can potentially alter this intertidal creek function. Habitat restoration was conducted in the oligohaline Alloway Creek watershed of Delaware Bay, USA, to ameliorate

Matthew E. Kimball; Kenneth W. Able

2007-01-01

332

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

Microsoft Academic Search

BackgroundSalt 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,

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

2011-01-01

333

Interisland dispersal of the black salt marsh mosquito, Ochlerotatus taeniorhynchus (Diptera: Culicidae) in the Florida Keys.  

PubMed

Mark-release-recapture experiments were conducted in 2001 and 2002 to determine whether Ochlerotatus taeniorhynchus, black salt marsh mosquitoes, were dispersing from uninhabited islands in the Key Deer National Wildlife Refuge to inhabited islands within Monroe County, Florida. An estimated 1,658,000 mosquitoes were marked during 2001, and an estimated 300,000 mosquitoes were marked during 2002. Recapture rates were 0.0061% and 0.0117%, respectively. Oc. taeniorhynchus disperse from uninhabited islands to other uninhabited islands and also to inhabited islands, namely, Big Pine Key and No Name Key. PMID:17304926

Vlach, Joshua J; Hall, Kristopher J; Day, Jonathan F; Curtis, G Alan; Hribar, Lawrence J; Fussell, Edsel M

2006-12-01

334

Studies on the production and decomposition of Spartina alterniflora Loisel. in a Galveston salt marsh  

E-print Network

(from clipped samples) 55 viii LIST OF FIGURES 1 Watershed of Galveston Bay 2 Galveston Island, West Bay, and surrounding salt marshes . . 16 3' Location of study area on Galveston Island 4a method of finding leaf area lost 4b Alternative method... Method Evans Method leaf losses Galveston Bay Bolivar Peninsula Pe pper Grove 0. 5 m low (20) med (43) hi (66) low (20) med (43) hi (66) 1162 282 219 520 438 205 Webb et al. (1979) Galveston Bay 0. 5 m Bolivar low (31) Peninsula med...

Sears, Norman Evans

2012-06-07

335

Suspended sediment deposition and trapping efficiency in a Delaware salt marsh  

NASA Astrophysics Data System (ADS)

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.

Moskalski, Susanne M.; Sommerfield, Christopher K.

2012-02-01

336

Porewater evidence for a dynamic sedimentary iron cycle in salt marshes. [Spartina alterniflora  

SciTech Connect

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.

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

1984-01-01

337

Comparison of vesicular-arbuscular mycorrhizae in plants from disturbed and adjacent undisturbed regions of a coastal salt marsh in Clinton, Connecticut, USA  

Microsoft Academic Search

Roots of salt marsh plant speciesSpartina alterniflora, S. patens, Distichlis spicata, and others were examined for the presence of vesicular-arbuscular mycorrhizal (VAM) fungi. Samples were taken from introduced\\u000a planted material in a salt marsh restoration project and from native material in adjacent marsh areas along the Indian River,\\u000a Clinton, Connecticut, USA. After ten years the replanted area still has sites

John C. Cooke; Michael W. Lefor

1990-01-01

338

Effects of Natural and Anthropogenic Change on Habitat Use and Movement of Endangered Salt Marsh Harvest Mice  

PubMed Central

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

Smith, Katherine R.; Barthman-Thompson, Laureen; Gould, William R.; Mabry, Karen E.

2014-01-01

339

The effects of metal and nutrient addition on Ribbed Mussels, Geukensia demissa, in the Great Sippewissett Salt Marsh and Eel Pond  

E-print Network

of metal pollution include sewage, lead paint and gasoline, boat paint, and pressure-treated wood. Salt the potential effects of nutrient loading and heavy metal pollution on salt marshes, researchers established long term experiments in the Great Sippewissett Marsh, Massachusetts, in which sewage

Vallino, Joseph J.

340

Physical Stress, Not Biotic Interactions, Preclude an Invasive Grass from Establishing in Forb-Dominated Salt Marshes  

PubMed Central

Background Biological invasions have become the focus of considerable concern and ecological research, yet the relative importance of abiotic and biotic factors in controlling the invasibility of habitats to exotic species is not well understood. Spartina species are highly invasive plants in coastal wetlands; however, studies on the factors that control the success or failure of Spartina invasions across multiple habitat types are rare and inconclusive. Methodology and Principal Findings We examined the roles of physical stress and plant interactions in mediating the establishment of the smooth cordgrass, Spartina alterniflora, in a variety of coastal habitats in northern China. Field transplant experiments showed that cordgrass can invade mudflats and low estuarine marshes with low salinity and frequent flooding, but cannot survive in salt marshes and high estuarine marshes with hypersaline soils and infrequent flooding. The dominant native plant Suaeda salsa had neither competitive nor facilitative effects on cordgrass. A common garden experiment revealed that cordgrass performed significantly better when flooded every other day than when flooded weekly. These results suggest that physical stress rather than plant interactions limits cordgrass invasions in northern China. Conclusions and Significance We conclude that Spartina invasions are likely to be constrained to tidal flats and low estuarine marshes in the Yellow River Delta. Due to harsh physical conditions, salt marshes and high estuarine marshes are unlikely to be invaded. These findings have implications for understanding Spartina invasions in northern China and on other coasts with similar biotic and abiotic environments. PMID:22432003

He, Qiang; Cui, Baoshan; An, Yuan

2012-01-01

341

Physiological Diversity of the Rhizosphere Diazotroph Assemblages of Selected Salt Marsh Grasses  

PubMed Central

Rhizosphere diazotroph assemblages of salt marsh grasses are thought to be influenced by host plant species and by a number of porewater geochemical parameters. Several geochemical variables can adversely affect plant productivity and spatial distributions, resulting in strong zonation of plant species and growth forms. This geochemically induced stress may also influence the species compositions and distributions of rhizosphere diazotroph assemblages, but little is currently known about these organisms. The diversity and key physiological features of culturable, O2-tolerant rhizosphere diazotrophs associated with the tall and short growth forms of Spartina alterniflora and with Juncus roemerianus were examined. A total of 339 gram-negative strains were isolated by a root stab culture approach and morphologically and physiologically characterized by using API and BIOLOG tests. Eighty-six distinct groups composed of physiologically similar strains were identified. Of these groups, 72% were shown to be capable of N2 fixation through molecular analyses, and a representative strain was chosen from each diazotroph group for further characterization. Cluster and principal-components analysis of BIOLOG data allowed the designation of physiologically distinct strain groupings. Most of these groups were dominated by strains that were not identifiable to species on the basis of API or BIOLOG testing. Representatives of several families including the Enterobacteriaceae, Vibrionaceae, Azotobacteraceae, Spirillaceae, Pseudomonadaceae, and Rhizobiaceae were recovered, as well as strains with no clear taxonomic affiliations. This study identifies numerous potentially important physiological groups of the salt marsh diazotroph assemblage. PMID:9797277

Bagwell, Christopher E.; Piceno, Yvette M.; Ashburne-Lucas, Amy; Lovell, Charles R.

1998-01-01

342

Potential of phytoremediation for the removal of petroleum hydrocarbons in contaminated salt marsh sediments.  

PubMed

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

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

2014-05-01

343

Dynamics of Bacterial and Fungal Communities on Decaying Salt Marsh Grass†  

PubMed Central

Both bacteria and fungi play critical roles in decomposition processes in many natural environments, yet only rarely have they been studied as an integrated microbial community. Here we describe the bacterial and fungal assemblages associated with two decomposition stages of Spartina alterniflora detritus in a productive southeastern U.S. salt marsh. 16S rRNA genes and 18S-to-28S internal transcribed spacer (ITS) regions were used to target the bacterial and ascomycete fungal communities, respectively, based on DNA sequence analysis of isolates and environmental clones and by using community fingerprinting based on terminal restriction fragment length polymorphism (T-RFLP) analysis. Seven major bacterial taxa (six affiliated with the ?-Proteobacteria and one with the Cytophagales) and four major fungal taxa were identified over five sample dates spanning 13 months. Fungal terminal restriction fragments (T-RFs) were informative at the species level; however, bacterial T-RFs frequently comprised a number of related genera. Amplicon abundances indicated that the salt marsh saprophyte communities have little-to-moderate variability spatially or with decomposition stage, but considerable variability temporally. However, the temporal variability could not be readily explained by either successional shifts or simple relationships with environmental factors. Significant correlations in abundance (both positive and negative) were found among dominant fungal and bacterial taxa that possibly indicate ecological interactions between decomposer organisms. Most associations involved one of four microbial taxa: two groups of bacteria affiliated with the ?-Proteobacteria and two ascomycete fungi (Phaeosphaeria spartinicola and environmental isolate “4clt”). PMID:14602628

Buchan, Alison; Newell, Steven Y.; Butler, Melissa; Biers, Erin J.; Hollibaugh , James T.; Moran, Mary Ann

2003-01-01

344

Salt marsh sediment diversity: a test of the variability of the rare biosphere among environmental replicates  

PubMed Central

Much of the phylogenetic diversity in microbial systems arises from rare taxa that comprise the long tail of taxon rank distribution curves. This vast diversity presents a challenge to testing hypotheses about the effects of perturbations on microbial community composition because variability of rare taxa among environmental replicates may be sufficiently large that it would require a prohibitive degree of sequencing to discern differences between samples. In this study we used pyrosequencing of 16S rRNA tags to examine the diversity and within-site variability of salt marsh sediment bacteria. Our goal was to determine whether pyrosequencing could produce similar patterns in community composition among replicate environmental samples from the same location. We hypothesized that repeated sampling from the same location would produce different snapshots of the rare community due to incomplete sequencing of the taxonomically rich rare biosphere. We demonstrate that the salt marsh sediments we sampled contain a remarkably diverse array of bacterial taxa and, in contrast to our hypothesis, repeated sampling from within the same site produces reliably similar patterns in bacterial community composition, even among rare organisms. These results demonstrate that deep sequencing of 16s tags is well suited to distinguish site-specific similarities and differences among rare taxa and is a valuable tool for hypothesis testing in microbial ecology. PMID:22739491

Bowen, Jennifer L; Morrison, Hilary G; Hobbie, John E; Sogin, Mitchell L

2012-01-01

345

Salt marsh sediment diversity: a test of the variability of the rare biosphere among environmental replicates.  

PubMed

Much of the phylogenetic diversity in microbial systems arises from rare taxa that comprise the long tail of taxon rank distribution curves. This vast diversity presents a challenge to testing hypotheses about the effects of perturbations on microbial community composition because variability of rare taxa among environmental replicates may be sufficiently large that it would require a prohibitive degree of sequencing to discern differences between samples. In this study we used pyrosequencing of 16S rRNA tags to examine the diversity and within-site variability of salt marsh sediment bacteria. Our goal was to determine whether pyrosequencing could produce similar patterns in community composition among replicate environmental samples from the same location. We hypothesized that repeated sampling from the same location would produce different snapshots of the rare community due to incomplete sequencing of the taxonomically rich rare biosphere. We demonstrate that the salt marsh sediments we sampled contain a remarkably diverse array of bacterial taxa and, in contrast to our hypothesis, repeated sampling from within the same site produces reliably similar patterns in bacterial community composition, even among rare organisms. These results demonstrate that deep sequencing of 16s tags is well suited to distinguish site-specific similarities and differences among rare taxa and is a valuable tool for hypothesis testing in microbial ecology. PMID:22739491

Bowen, Jennifer L; Morrison, Hilary G; Hobbie, John E; Sogin, Mitchell L

2012-11-01

346

Effects of flooding and warming on soil organic matter mineralization in Avicennia germinans mangrove forests and Juncus roemerianus salt marshes  

NASA Astrophysics Data System (ADS)

Under a changing climate, coastal wetlands experience sea level rise, warming, and vegetation change, all of which may influence organic matter mineralization. In coastal wetlands of subtropical west-central Florida (USA), we investigated how soil carbon (C) and nitrogen (N) mineralization respond to soil water, temperature, and ecosystem type (Avicennia germinans mangrove forest vs. Juncus roemerianus salt marsh). We evaluated how soil respiration and mineral N concentration varied along a soil moisture gradient, and whether these relationships differed between ecosystem types. Then, we manipulated soils in a 28-d laboratory incubation to evaluate how potentially mineralizable C and N respond to temperature (23 vs. 27 °C), soil hydroperiod (inundated 4 vs. 20 h/d), and soil source. Soil saturation and inundation suppressed short-term (minutes to weeks) C mineralization from near-surface soils. Soil CO2 efflux declined by 65% as soil moisture increased from 75% to 85%, and potentially mineralizable C was 18% lower with a 20-h hydroperiod than with a 4-h hydroperiod. Organic C quality appears to be greater in A. germinans than in J. roemerianus soils, as A. germinans soils had higher field CO2 efflux rates and greater mineralizable C:N (despite lower total C:N). Increasing incubation temperature from 23 to 27 °C elevated potentially mineralizable C by 40%, indicating that two symptoms of climate change (increased inundation from sea level rise, and warming) may have opposing effects on soil C mineralization. Temperature sensitivity of C mineralization was high for long-hydroperiod soils, however, suggesting that protection of soil organic matter (SOM) due to prolonged inundation will be undermined by warming. Potentially mineralizable N was greater in J. roemerianus soils, although in situ mineral N was not different between ecosystems, instead correlating positively with SOM. These results indicate that models forecasting soil elevation responses to climate change might include inundation effects on mineralization rates.

Lewis, David Bruce; Brown, Jewel A.; Jimenez, Kristine L.

2014-02-01

347

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

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.

Elsey-Quirk, T.; Middleton, B.A.; Proffitt, C.E.

2009-01-01

348

Biodiversity of arbuscular mycorrhizal fungi in roots and soils of two salt marshes.  

PubMed

The occurrence of arbuscular mycorrhizal fungi (AMF) was assessed by both morphological and molecular criteria in two salt marshes: (i) a NaCl site of the island Terschelling, Atlantic Coast, the Netherlands and (ii) a K(2)CO(3) marsh at Schreyahn, Northern Germany. The overall biodiversity of AMF, based on sequence analysis, was comparably low in roots at both sites. However, the morphological spore analyses from soil samples of both sites exhibited a higher AMF biodiversity. Glomus geosporum was the only fungus of the Glomerales that was detected both as spores in soil samples and in roots of the AMF-colonized salt plants Aster tripolium and Puccinellia sp. at both saline sites and on all sampling dates (one exception). In roots, sequences of Glomus intraradices prevailed, but this fungus could not be identified unambiguously from DNA of soil spores. Likewise, Glomus sp. uncultured, only deposited as sequence in the database, was widely detected by DNA sequencing in root samples. All attempts to obtain the corresponding sequences from spores isolated from soil samples failed consistently. A small sized Archaeospora sp. was detected, either/or by morphological and molecular analyses, in roots or soil spores, in dead AMF spores or orobatid mites. The study noted inconsistencies between morphological characterization and identification by DNA sequencing of the 5.8S rDNA-ITS2 region or part of the 18S rDNA gene. The distribution of AMF unlikely followed the salt gradient at both sites, in contrast to the zone formation of plant species. Zygotes of the alga Vaucheria erythrospora (Xanthophyceae) were retrieved and should not be misidentified with AMF spores. PMID:19220401

Wilde, Petra; Manal, Astrid; Stodden, Marc; Sieverding, Ewald; Hildebrandt, Ulrich; Bothe, Hermann

2009-06-01

349

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

PubMed

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 salt marsh health assessment. PMID:22957707

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

2011-01-01

350

Aquatic Insects of New York Salt Marsh Associated with Mosquito Larval Habitat and their Potential Utility as Bioindicators  

PubMed Central

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 insectbased index of biological integrity for salt marsh health assessment. PMID:22957707

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

2011-01-01

351

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

352

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...

353

Long-term effects of an oil spill on populations of the salt-marsh crab Uca pugnax  

Microsoft Academic Search

A spill of fuel oil at West Falmouth, Massachusetts, in 1969, contaminated contiguous salt marshes with up to 6000 micrograms of oil per gram (ppM) of wet mud and affected local populations of Uca pugnax. Directly related to high-sediment oil content were reduced crab density, reduced ratio of females to males, reduced juvenile settlement, heavy overwinter mortality, incorporation of oil

C. T. Krebs; K. A. Burns

1977-01-01

354

Copper, lead and zinc in salt marsh sediments of the Severn Estuary, UK: The potential for their early diagnetic mobility.  

PubMed

A detailed lithostratigraphic analysis already exists for salt marsh sediments of the Severn Estuary, which provides an ideal background for an investigation of phase associations of trace elements within sediment depth profiles. The first stages of a detailed investigation are reported in which phase associations of Cu, Pb and Zn are related to early diagenetic processes. PMID:24202421

Rae, J E

1989-12-01

355

Species-specific patterns of litter processing by terrestrial isopods (Isopoda: Oniscidea) in high intertidal salt marshes and coastal forests  

Microsoft Academic Search

Summary 1. The species-specificity of litter processing by three species of isopods at the interface between salt marsh and coastal forest habitats in the south-eastern United States was examined. 2. To quantify isopod performance, measurements were taken of feeding, digestion and growth of isopods fed on three litter types ( Juncus roemerianus , Quercus virginiana and Pinus palustris ) and

M. Zimmer; S. C. Pennings; T. L. Buck; T. H. Carefoot

2002-01-01

356

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...

357

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

Microsoft Academic Search

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

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

2008-01-01

358

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...

359

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

PubMed

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

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

2013-01-01

360

Changes in methanogenic substrate utilization and communities with depth in a salt-marsh, creek sediment in southern England  

Microsoft Academic Search

A combined biogeochemical and molecular genetic study of creek sediments (down to 65 cm depth) from Arne Peninsula salt-marsh (Dorset, UK) determined the substrates used for methanogenesis and the distribution of the common methanogens, Methanosarcinales and Methanomicrobiales capable of metabolising these substrates. Methane concentrations increased by 11 cm, despite pore water sulphate not being removed until 45 cm. Neither upward

Fiona Brock; Natasha Banning; Edward R. C. Hornibrook; Erwan G Roussel; Andrew J Weightman; John. C. Fry

361

Intertidal distribution, population dynamics and production of the amphipod Uhlorchestia spartinophila in a Georgia, USA, salt marsh  

Microsoft Academic Search

The talitrid amphipod Uhlorchestia spartinophila Bousfield and Heard occurs in close association with the smooth cordgrass Spartina alterniflora Loisel in salt marshes along the U.S. Atlantic coast. In order to assess its potential as a prey resource for secondary consumers, we followed the population and production dynamics of this amphipod from 3 November 1990 to 2 October 1991 in a

M. P. Covi; R. T. Kneib

1995-01-01

362

Relative contributions of bacteria and fungi to rates of degradation of lignocellulosic detritus in salt-marsh sediments.  

PubMed

Specifically radiolabeled [C-lignin]lignocellulose and [C-polysaccharide]lignocellulose from the salt-marsh cordgrass Spartina alterniflora were incubated with an intact salt-marsh sediment microbial assemblage, with a mixed (size-fractionated) bacterial assemblage, and with each of three marine fungi, Buergenerula spartinae, Phaeosphaeria typharum, and Leptosphaeria obiones, isolated from decaying S. alterniflora. The bacterial assemblage alone mineralized the lignin and polysaccharide components of S. alterniflora lignocellulose at approximately the same rate as did intact salt-marsh sediment inocula. The polysaccharide component was mineralized twice as fast as the lignin component; after 23 days of incubation, ca. 10% of the lignin component and 20% of the polysaccharide component of S. alterniflora lignocellulose were mineralized. Relative to the total sediment and bacterial inocula, the three species of fungi mediated only very slow mineralization of the lignin and polysaccharide components of S. alterniflora lignocellulose. Experiments with uniformly C-labeled S. alterniflora material indicated that the three fungi and the bacterial assemblage were capable of degrading the non-lignocellulosic fraction of S. alterniflora material, but only the bacterial assemblage significantly degraded the lignocellulosic fraction. Our results suggest that bacteria are the predominant degraders of lignocellulosic detritus in salt-marsh sediments. PMID:16346598

Benner, R; Newell, S Y; Maccubbin, A E; Hodson, R E

1984-07-01

363

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

USGS Publications Warehouse

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.

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

2012-01-01

364

The effect of macrofauna, meiofauna and microfauna on the degradation of Spartina maritima detritus from a salt marsh area  

Microsoft Academic Search

Decomposition of salt marsh plants results from physical, chemical and biological processes including abiotic and biotic fragmentation, microbial decay and chemical transformation. According to literature data, only a few species have the ability to feed directly on living plant material, so fungi and bacteria seem to be the principal competitors for the organic substrates. Nevertheless, by consuming bacteria, protists and

Ana Isabel Lillebø; Mogens R. Flindt; Miguel Ângelo Pardal; João Carlos Marques

1999-01-01

365

A Tripartite Interaction Between Spartina alterniflora, Fusarium palustre, and the Purple Marsh Crab (Sesarma reticulatum) Contributes to Sudden Vegetation Dieback of Salt Marshes in New England.  

PubMed

ABSTRACT Tripartite interactions are common and occur when one agent (an arthropod or pathogen) changes the host plant in a manner that alters the attack of the challenging agent. We examined herbivory from the purple marsh crab (Sesarma reticulatum) on Spartina alterniflora following exposure to drought or inoculation with Fusarium palustre in mecocosms in the greenhouse and in crab-infested creek banks along intertidal salt marshes. Initially, drought stress on S. alterniflora and disease from F. palustre were examined in the greenhouse. Then, a second challenger, the purple marsh crab, was introduced to determine how drought and disease from F. palustre affected the attraction and consumption of S. alterniflora. Plant height and shoot and root weights were reduced in plants subjected to severe drought treatment when compared with normally irrigated plants. When the drought treatment was combined with inoculation with F. palustre, plants were significantly more stunted and symptomatic, had less fresh weight, more diseased roots, and a greater number of Fusarium colonies growing from the roots (P < 0.001) than noninoculated plants. The effects were additive, and statistical interactions were not detected between drought and inoculation. Estimates of herbivory (number of grass blades cut or biomass consumption) by the purple marsh crab were significantly greater on drought-stressed, diseased plants than on healthy plants irrigated normally. Drought increased attraction to the purple marsh crab more than inoculation with F. palustre. However, when only mild drought conditions were imposed, plant consumption was greater on inoculated plants. Healthy, nonstressed transplants set into plots in crabinfested intertidal creek banks were grazed less each year than inoculated plants or plants that were exposed to drought. Several hypotheses relating to nutrition, chemotaxis, and visual attraction are presented to explain how stress from drought or disease might favor herbivory. PMID:24679153

Elmer, Wade H

2014-10-01

366

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

NASA Astrophysics Data System (ADS)

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 from crude oil contamination. The release of aqueous Fe(II) between 2 to 14 days could be caused by desorption from, and/or by reductive dissolution of, iron-bearing clays or iron oxide. Metals associated with crude oil are releasing into the water at similar times. Cadmium and vanadium, metals commonly associated with crude oil, both increase in concentration six hours into the experiment, followed by another small peak after seven days. Other trace elements (nickel, copper, and zinc) are released after one day. Geochemical modeling is being used to interpret the aqueous geochemistry of the experiments.

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

2011-12-01

367

Nutrient retention in plant biomass and sediments from the salt marsh in Hangzhou Bay estuary, China.  

PubMed

Nutrient load into the ocean can be retained during the process of plant uptake and sedimentation in marshes along the bay zone. Seasonal variations of biomass and nutrient concentration in three dominated plant assemblages and associated sediments were monitored in this study area to determine effects of salt marsh on nutrient retention. Results showed that plant aboveground biomass displayed a unimodal curve with nutrient concentration generally decreased from spring to winter. Belowground biomass was relatively low during the rapid growth period with nutrient concentration tending to decrease and then increase during this period. Plant total nitrogen (TN) pools are higher than total phosphorus (TP) pools, and both pools showed significant seasonal variations. Water purification coefficients (WPC) of nutrients by plant assimilation were 34.4/17.3, 19.3/24.0, and 5.14/6.04 t/(m(2) year) (TN/TP) for Phragmites australis, Spartina alterniflora, and Scirpus mariqueter, respectively. Overall, these results suggest that higher annual plant biomass and nutrient assimilation contribute to greater nutrient retention capacity and accumulation in sediments, thereby enabling reduced eutrophication in transitional waters. PMID:23589271

Shao, Xuexin; Wu, Ming; Gu, Binhe; Chen, Yinxu; Liang, Xinqiang

2013-09-01

368

Release of dimethylsulfide from dimethylsulfoniopropionate by plant-associated salt marsh fungi.  

PubMed

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

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

1998-04-01

369

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

PubMed Central

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

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

1998-01-01

370

Dissolved organic Fe(III) and Fe(II) complexes in salt marsh porewaters  

NASA Astrophysics Data System (ADS)

Fe(III) and Fe(II) organic complexes were determined by spectroscopic methods after sephadex gel fractionation of salt marsh porewaters during June and July 1993. Fe(III), which is a significant anaerobic oxidant for sulfide mineral oxidation, was typically found in the 100-5000 molecular weight (MW) fraction indicative of humic and other organic complexing agents. Fe(II) was found in both the <100 and the 100-5000 MW fractions with most of the Fe(II) found in the smaller MW class. Both forms of Fe precipitated with humic material when the pH of the porewaters became less than 3. There was a twofold decrease in the <5000 MW fractions, a ninefold increase in the >5000 MW class, and a tenfold decrease in dissolved Fe concentration in sephadex gel fractions as the pH decreased from 5.0 to <3 for porewater samples. Low pH values are attributed to sulfide mineral oxidation from severe drought conditions that caused significant dessication of the vegetated marsh. Microelectrode measurements demonstrated that O 2 was not detected below 2 mm and that Fe(III) organic complexes should be significant oxidants in anoxic waters.

Luther, George W.; Shellenbarger, P. Ann; Brendel, Paul J.

1996-03-01

371

Ecological Relationships between Meloidogyne spartinae and Salt Marsh Grasses in Connecticut  

PubMed Central

Healthy specimens of selected grasses were collected from salt marshes and grown in the greenhouse. Plants were inoculated with Meloidogyne spartinae to determine the host range of this nematode. After 12 weeks, Spartina alterniflora plants formed root galls in response to infection and increased M. spartinae populations. Spartina patens, Spartina cynosuroides, Juncus gerardii and Distichlis spicata were non-hosts. In order to determine the natural distribution of M. spartinae in dieback areas, S. alterniflora plants were sampled from transects adjacent to dieback areas in Madison, CT, at low tide. Plants were sampled at the top or the creek and at 1-m intervals to the lowest area of plant growth at the low tide water's edge. Five samples were taken over an elevation drop of 90 cm. Two transects were taken each day on 21 June and 5 July 2007, and one transect was taken on 31 October 2007. Meloidogyne spartinae galls per gram root were higher at the higher elevations. In late June and early July 2007, M. spartinae developed more quickly in the higher elevations, perhaps because peat and sediments were drier and warmer away from low tide water levels. The effects of M. spartinae on S. alterniflora and the role of the nematode in marsh decline and dieback in the northeast United States remain to be determined. PMID:19440262

Elmer, W. H.

2008-01-01

372

Ecological Relationships between Meloidogyne spartinae and Salt Marsh Grasses in Connecticut.  

PubMed

Healthy specimens of selected grasses were collected from salt marshes and grown in the greenhouse. Plants were inoculated with Meloidogyne spartinae to determine the host range of this nematode. After 12 weeks, Spartina alterniflora plants formed root galls in response to infection and increased M. spartinae populations. Spartina patens, Spartina cynosuroides, Juncus gerardii and Distichlis spicata were non-hosts. In order to determine the natural distribution of M. spartinae in dieback areas, S. alterniflora plants were sampled from transects adjacent to dieback areas in Madison, CT, at low tide. Plants were sampled at the top or the creek and at 1-m intervals to the lowest area of plant growth at the low tide water's edge. Five samples were taken over an elevation drop of 90 cm. Two transects were taken each day on 21 June and 5 July 2007, and one transect was taken on 31 October 2007. Meloidogyne spartinae galls per gram root were higher at the higher elevations. In late June and early July 2007, M. spartinae developed more quickly in the higher elevations, perhaps because peat and sediments were drier and warmer away from low tide water levels. The effects of M. spartinae on S. alterniflora and the role of the nematode in marsh decline and dieback in the northeast United States remain to be determined. PMID:19440262

Lamondia, J A; Elmer, W H

2008-09-01

373

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

NASA Astrophysics Data System (ADS)

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 considerably affect metal distribution and retention in the estuarine region.

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

2011-01-01

374

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

PubMed Central

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 systems to maximize the benefits and ecosystem services provided by salt marshes and exercise caution when making decisions that erode these services. PMID:22132099

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

2011-01-01

375

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

PubMed Central

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

Smith, Bruce N.; Epstein, Samuel

1970-01-01

376

Greenhouse Gas and Mercury Emissions from a Salt Marsh on the Bay of Fundy  

NASA Astrophysics Data System (ADS)

The Bay of Fundy, primarily situated between the provinces of New Brunswick and Nova Scotia in Canada is known have tides among the highest in the world, where tidal amplitudes have reached 17 m, and regularly exceed 12-13m. The reason for these extremely high tides has been attributed to basin morphology and tidal resonance. Along the margin of the Bay of Fundy, salt marshes are exposed to these high tidal ranges. These salt marshes have unknown greenhouse gas (CO2, CH4 specifically) and mercury trace gas budgets. Tides here exert significant pressure on salt marsh sediments, to the point where gases are visibly seen escaping around the waters edge. This pressure-driven gas transport phenomena is markedly different than most greenhouse gas releases from other sediments, which occurs primarily by diffusion. Our study site in Kingsport, NS, Canada also provides a unique opportunity to examine pressure-driven emissions using differential pressure measurements. This work is significant in determining the role of salt marshes in the carbon and mercury emission budgets in the maritime region, and their sensitivity to environmental forcings. For our study, mercury fluxes were measured using Teflon flux chamber technique with Tekran gaseous mercury analysis, while CO2 and CH4 fluxes were measured at 60 second intervals using a new technique called continuous timeseries-forced diffusion (CT-FD). A portable meteorological station was located on site, with soil temperature, solar radiation, soil O2, and soil-atmosphere differential pressure measurements logged continuously for 10 days and 19 tidal cycles. After the field deployment, the CO2 and CH4 instrumentation was moved to soil plots in mesocosm tidal-simulation benches to conduct experiments that would allow us to separate the difference between tidal forcings and thermally-driven microbial greenhouse gas production in sediments. In the field, differential pressure varied according to tidal cycles and was surprising in that rebound to atmospheric pressure rarely occurred. Instead, pressure gradients were sustained in the sediments during high (excess pressure) and low (pressure deficit) tides. While no compelling relationship appears evident between mercury, CO2, or CH4 flux and tidal height, ratios of flux to solar radiation suggest that tidal inundation and gas release does at least facilitate mercury release from sediments during peak flux times. Low gas diffusivity sediments (very fine, impermeable, compact) are potentially very important at these sites, potentially damping transport rates across the soil surface. Gas bubbles, which can be observed at the incoming waterline, may be preferentially emitted through more permeable sediment layers and subsurface sand channels rather than the surface. The Bay of Fundy setting provides a rather unique and challenging opportunity to study extreme examples of trace gas flux and gas transport dynamics.

O'Driscoll, N.; McArthur, G. S.; Risk, D. A.; Dalziel, J.; Beltrami, H.

2009-12-01

377

A potential mechanism for disturbance-mediated channel migration in a southeastern United States salt marsh  

NASA Astrophysics Data System (ADS)

Coastal salt marsh tidal creeks are thought to show less channel adjustment/movement relative to their terrestrial fluvial counterparts. We propose a mechanism for disturbance-mediated bank failure that may allow/initiate channel migration in these otherwise stable systems. The stability of tidal creeks is promoted by the extensive vegetation root structure along the banks. However, wrack mats (i.e., dead vegetation) deposited on creek banks can cause the death of below-ground vegetation leading to bare, unstable banks that may slump into the channel. We measured the frequency of bank failures associated with wrack-disturbed sites along three creeks on Sapelo Island, Georgia, USA to determine whether these sites were vulnerable to erosion. Approximately 81% of the disturbed sites showed signs of bank failure. Therefore, wrack-induced bank failure may potentially lead to channel migration in creeks previously believed to be static landscape features.

Lottig, Noah R.; Fox, Justin M.

2007-05-01

378

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

USGS Publications Warehouse

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.

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

2007-01-01

379

Nitrogen cycling and ecosystem exchanges in a Virginia tidal freshwater marsh  

Microsoft Academic Search

Tidal freshwater marshes are diverse habitats that differ both within and between marshes in terms of plant community composition,\\u000a sediment type, marsh elevation, and nutrient status. Because our knowledge of the nitrogen (N) biogeochemistry of tidal freshwater\\u000a systems is limited, it is difficult to assess how these marshes will respond to long-term progressive nutrient loading due\\u000a to watershed development and

Scott C. Neubauer; Iris C. Anderson; Betty B. Neikirk

2005-01-01

380

New species of Fusarium associated with dieback of Spartina alterniflora in Atlantic salt marshes.  

PubMed

Sudden vegetation dieback (SVD) is the loss of smooth cordgrass (Spartina alterniflora) along intertidal creeks in salt marshes of the Atlantic and Gulf states. The underlying cause of SVD remains unclear, but earlier work suggested a contributing role for Fusarium spp. in Louisiana. This report investigated whether these or other Fusarium species were associated with S. alterniflora dieback in mid- to north-Atlantic states. Isolations from seven SVD sites yielded 192 isolates of Fusarium spp., with more than 75% isolated from aboveground tissue. Most isolates (88%) fell into two undescribed morphospecies (MS) distinguished from each other by macroconidial shape, phialide ontogeny and growth rates. Pathogenicity tests on wound-inoculated S. alterniflora stems and seedling roots revealed that isolates in MS1 were more virulent than those in MS2 but no single isolate caused plant mortality. No matches to known species of Fusarium were revealed by DNA sequence queries of translation elongation factor 1-? (tef1) sequences. A phylogenetic analysis of partial sequences of three genes, ?-tubulin (?-tub), calmodulin (cal) and tef1, was conducted on representative isolates from MS1 (n = 20) and MS2 (n = 18); it provided strong evidence that the MS1 isolates form a clade that represents a heretofore undescribed species, which we designate Fusarium palustre sp. nov. Isolates from the more variable MS2 clustered with the F. incarnatum-equiseti species complex as F. cf. incarnatum. Although a strong association exists between both species and declining S. alterniflora in SVD sites, neither appears to play a primary causal role in SVD. However, our findings suggest that F. palustre might play an important secondary role in the ecological disruption of the salt marshes. PMID:21471289

Elmer, Wade H; Marra, Robert E

2011-01-01

381

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

NASA Astrophysics Data System (ADS)

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.

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

2007-07-01

382

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

PubMed Central

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

Taillefert, Martial; Neuhuber, Stephanie; Bristow, Gwendolyn

2007-01-01

383

Comparison of biomass production and decomposition between Phragmites australis (common reed) and Spartina patens (salt hay grass) in brackish tidal marshes of New Jersey, USA  

Microsoft Academic Search

The recent expansion of Phragmites australis (common reed) from the marsh-upland interface into high marsh zones provides an opportunity to assess the impact of individual\\u000a plant species on biomass production and decomposition in salt marshes. Seasonal harvests of aboveground and belowground biomass\\u000a demonstrate that annual production of P. australis is approximately three times greater for aboveground biomass, two times greater

Lisamarie Windham

2001-01-01

384

Functional gene pyrosequencing and network analysis: an approach to examine the response of denitrifying bacteria to increased nitrogen supply in salt marsh sediments  

PubMed Central

Functional gene pyrosequencing is emerging as a useful tool to examine the diversity and abundance of microbes that facilitate key biogeochemical processes. One such process, denitrification, is of particular importance because it converts fixed nitrate (NO?3) to N2 gas, which returns to the atmosphere. In nitrogen limited salt marshes, removal of NO?3 prior to entering adjacent waters helps prevent eutrophication. Understanding the dynamics of salt marsh microbial denitrification is thus imperative for the maintenance of healthy coastal ecosystems. We used pyrosequencing of the nirS gene to examine the denitrifying community response to fertilization in experimentally enriched marsh plots. A key challenge in the analysis of sequence data derived from pyrosequencing is understanding whether small differences in gene sequences are ecologically meaningful. We applied a novel approach from information theory to determine that the optimal similarity level for clustering DNA sequences into OTUs, while still capturing the ecological complexity of the system, was 88%. With this clustering, phylogenetic analysis yielded 6 dominant clades of denitrifiers, the largest of which, accounting for more than half of all the sequences collected, had no close cultured representatives. Of the 638 OTUs identified, only 11 were present in all plots and no single OTU was dominant. We did, however, find a large number of specialist OTUs that were present only in a single plot. The high degree of endemic OTUs, while accounting for a large proportion of the nirS diversity in the plots, were found in lower abundance than the generalist taxa. The proportion of specialist taxa increased with increasing supply of nutrients, suggesting that addition of fertilizer may create conditions that expand the niche space for denitrifying organisms and may enhance the genetic capacity for denitrification. PMID:24348464

Bowen, Jennifer L.; Byrnes, Jarrett E. K.; Weisman, David; Colaneri, Cory

2013-01-01

385

Impact of bioaugmentation on crude oil degradation in salt-marsh-sediment microcosms  

E-print Network

Bioremediation is the method of choice for eliminating oil from marshes and is dependent on microorganisms capable of mineralizing oil. Because populations of oil degrading microorganisms are low in marshes there is a potential for increasing...

Neralla, Srinivasan

2012-06-07

386

Rapid shoreward encroachment of salt marsh cordgrass in response to accelerated  

E-print Network

, whereas a mosaic of marsh hay (Spartina patens), spike grass (Distichlis spicata), and black rush (Juncus, whereas a mosaic of marsh hay (Spartina patens), spike grass (Distichlis spicata), and black rush (Juncus

Bertness, Mark D.

387

VARYING LANDSCAPE STRUCTURE AND POTENTIAL DENITRIFICATION ACTIVITY AMONG SALT MARSHES ALONG AN ANTHROPOGENIC DISTURBANCE GRADIENT  

EPA Science Inventory

Marsh landscape structure and denitrification are proposed as indicators of key wetland services, providing animal habitat and water quality maintenance, respectively. We examined marsh landscape structure (i.e., plant species richness and extent of dominant plant species) and po...

388

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)

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.

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

2009-11-01

389

Size and age at first reproduction of the ribbed mussel Geukensia demissa (Dillwyn) in relation to shore level in a New York salt marsh  

Microsoft Academic Search

The shell lengths and dry body weights of ribbed mussels (Geukensia demissa) at the onset of sexual maturation were determined at two shore levels within the tall Spartina alterniflora zone in a New York City salt marsh. Mussels grow faster at the lower level (marsh edge) than at the higher shore level (15 m upshore of the edge), and have

David R Franz

1996-01-01

390

Importance of Vascular Plant and Algal Production to Macro-invertebrate Consumers in a Southern California Salt Marsh  

NASA Astrophysics Data System (ADS)

The dietary importance of marsh vascular plants (primarily Salicornia virginica), algae and upland particulate inputs to macro-invertebrate consumers was studied in Carpinteria Salt Marsh, southern California, using stable carbon and nitrogen isotope ratios. This marsh is predominantly a marine or hypersaline system and succulents are the most common vascular plant species. Of invertebrates collected from the vegetated marsh, tidal flats and channels, only detritivores from the vegetated marsh ( Traskorchestia traskiana, Melampus olivaceus) had isotope values (? 13C=-20‰) that suggested some use of Salicornia-derived carbon. T. traskianacultured in the laboratory on decomposing S. virginicaor blue-green micro-algal mat had distinctive isotopic signatures, reflecting the capability of this consumer to assimilate carbon and nitrogen derived from these sources. The ? 13C values (generally -16‰ to -15‰) of species from tidal flats and channels (e.g. Cerithidea californica, Protothaca staminea, Mytilus galloprovincialis, Neotrypaea californiensis) were most similar to values for benthic algae and phytoplankton. Specimens of M. galloprovincialisalong a gradient of presumed increase in marine influence had similar isotope values, suggesting little contribution to diet from upland runoff. The present results differ most noticeably from published values in the 13C enrichment of suspension-feeders, suggesting the use of resuspended 13C-enriched benthic microalgae in tidal channels by these consumers, and in the 13C depletion and 15N enrichment of plants and consumers along a portion of the marsh boundary receiving inputs of nutrient-enriched perched groundwater. In general, the isotopic composition of macro-invertebrates indicated the incorporation of algal production rather than of S. virginicaor upland sources into the marsh food web.

Page, H. M.

1997-12-01

391

Net ecosystem methane and carbon dioxide exchanges in a Lake Erie coastal marsh and a nearby cropland  

NASA Astrophysics Data System (ADS)

ecosystem carbon dioxide (FCO2) and methane (FCH4) exchanges were measured by using the eddy covariance method to quantify the atmospheric carbon budget at a Typha- and Nymphaea-dominated freshwater marsh (March 2011 to March 2013) and a soybean cropland (May 2011 to May 2012) in northwestern Ohio, USA. Two year average annual FCH4 (49.7 g C-CH4 m-2 yr-1) from the marsh was high and compatible with its net annual CO2 uptake (FCO2: -21.0 g C-CO2 m-2 yr-1). In contrast, FCH4 was small (2.3 g C-CH4 m-2 yr-1) and accounted for a minor portion of the atmospheric carbon budget (FCO2: -151.8 g C-CO2 m-2 yr-1) at the cropland. At the seasonal scale, soil temperature associated with methane (CH4) production provided the dominant regulator of FCH4 at the marsh (R2 = 0.86). At the diurnal scale, plant-modulated gas flow was the major pathway for CH4 outgassing in the growing season at the marsh. Diffusion and ebullition became the major pathways in the nongrowing season and were regulated by friction velocity. Our findings highlight the importance of freshwater marshes for their efficiency in turning over and releasing newly fixed carbon as CH4. Despite marshes accounting for only ~4% of area in the agriculture-dominated landscape, their high FCH4 should be carefully addressed in the regional carbon budget.

Chu, Housen; Chen, Jiquan; Gottgens, Johan F.; Ouyang, Zutao; John, Ranjeet; Czajkowski, Kevin; Becker, Richard

2014-05-01

392

Vegetation death and rapid loss of surface elevation in two contrasting Mississippi delta salt marshes: The role of sedimentation, autocompaction and sea-level rise  

USGS Publications Warehouse

From 1990 to 2004, we carried out a study on accretionary dynamics and wetland loss in salt marshes surrounding two small ponds in the Mississippi delta; Old Oyster Bayou (OB), a sediment-rich area near the mouth of the Atchafalaya River and Bayou Chitigue (BC), a sediment-poor area about 70. km to the east. The OB site was stable, while most of the marsh at BC disappeared within a few years. Measurements were made of short-term sedimentation, vertical accretion, change in marsh surface elevation, pond wave activity, and marsh soil characteristics. The OB marsh was about 10. cm higher than BC; the extremes of the elevation range for Spartina alterniflora in Louisiana. Vertical accretion and short-term sedimentation were about twice as high at BC than at OB, but the OB marsh captured nearly all sediments deposited, while the BC marsh captured <30%. The OB and BC sites flooded about 15% and 85% of the time, respectively. Marsh loss at BC was not due to wave erosion. The mineral content of deposited sediments was higher at OB. Exposure and desiccation of the marsh surface at OB increased the efficiency that deposited sediments were incorporated into the marsh soil, and displaced the marsh surface upward by biological processes like root growth, while also reducing shallow compaction. Once vegetation dies, there is a loss of soil volume due to loss of root turgor and oxidation of root organic matter, which leads to elevation collapse. Revegetation cannot occur because of the low elevation and weak soil strength. The changes in elevation at both marsh sites are punctuated, occurring in steps that can either increase or decrease elevation. When a marsh is low as at BC, a step down can result in an irreversible change. At this point, the option is not restoration but creating a new marsh with massive sediment input either from the river or via dredging. ?? 2010 Elsevier B.V.

Day, J.W.; Kemp, G.P.; Reed, D.J.; Cahoon, D.R.; Boumans, R.M.; Suhayda, J.M.; Gambrell, R.

2011-01-01

393

The Utilization of Airborne Digital Multispectral Image Dynamics and Kinematic Global Positioning Systems for Assessing and Monitoring Salt Marsh Habitats in Southern California  

Microsoft Academic Search

\\u000a The utility of two data acquisition technologies, airborne digital multispectral imaging, and kinematic global positioning\\u000a systems (KGPS), for providing spatially detailed and precise habitat data for salt marsh reserves in southern California is\\u000a assessed. Two case studies demonstrate that by combining these technologies, habitat of endangered bird species that occupy\\u000a these salt marshes can be mapped and analyzed in an

Douglas Stow; Alice E. Brewster; Brian K. Bradshaw

394

Trematodes in snails near raccoon latrines suggest a final host role for this mammal in California salt marshes.  

PubMed

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. PMID:15986632

Lafferty, K D; Dunham, E J

2005-04-01

395

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

PubMed

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

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

2005-11-01

396

Growth patterns of Carolina wolfberry ( Lycium carolinianum L.) in the salt marshes of Aransas National Wildlife Refuge, Texas, USA  

Microsoft Academic Search

The coastal salt marshes of the Aransas National Wildlife Refuge (ANWR), Texas, USA support a wintering population of the\\u000a endangered Whooping Crane (Grus americana). Although the bulk of their winter diet is comprised of blue crabs, berries from the Carolina wolfberry (Lycium carolinianum) can contribute 21–52% of crane energy intake early in the wintering period. Monthly, from November 2003 to

Rachel E. Butzler; Stephen E. Davis

2006-01-01

397

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

PubMed Central

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 controlling this invasion. PMID:23166596

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

2012-01-01

398

Seasonal analyses of arbuscular mycorrhizae, nitrogen-fixing bacteria and growth performance of the salt marsh grass Spartina patens  

Microsoft Academic Search

Seasonal variation of arbuscular mycorrhizal fungi (AMF) in roots of the high salt marsh plant Spartina patens, the diversity of nitrogen-fixing bacteria in the rhizosphere and plant growth performance was studied at key stages of the\\u000a growing season coinciding with major plant phenological stages, i.e., vegetative growth, reproduction and senescence. AMF\\u000a colonization was highest during vegetative growth, with values declining

Allana K. Welsh; David J. Burke; Erik P. Hamerlynck; Dittmar Hahn

2010-01-01

399

Natural-abundance radiocarbon as a tracer of assimilation of petroleum carbon by bacteria in salt marsh sediments  

Microsoft Academic Search

The natural abundance of radiocarbon (14C) provides unique insight into the source and cycling of sedimentary organic matter. Radiocarbon analysis of bacterial phospholipid lipid fatty acids (PLFAs) in salt-marsh sediments of southeast Georgia (USA)---one heavily contaminated by petroleum residues---was used to assess the fate of petroleum-derived carbon in sediments and incorporation of fossil carbon into microbial biomass. PLFAs that are

Stuart G. Wakeham; Ann P. McNichol; Joel E. Kostka; Tamara K. Pease

2006-01-01

400

Seasonal abundance, distribution and growth of postlarval and juvenile grass shrimp ( Palaemonetes pugio ) in a Georgia, USA, salt marsh  

Microsoft Academic Search

Postlarval and juvenile grass shrimp (Palaemonetes pugio Holthuis) ?15 mm total length (TL) were abundant at low tide in shallow aquatic microhabitats (i.e. puddles and films of\\u000a residual tidal water) in the intertidal zone of a salt marsh on Sapelo Island, Georgia, USA from 1982 to 1984. The highest\\u000a concentrations of young P. pugio occurred at 190 to 200 cm

R. T. Kneib

1987-01-01

401

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

Microsoft Academic Search

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

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

2010-01-01

402

Isolation and Characterization of Polycyclic Aromatic Hydrocarbon-Degrading Bacteria Associated with the Rhizosphere of Salt Marsh Plants  

Microsoft Academic Search

Polycyclic aromatic hydrocarbon (PAH)-degrading bacteria were isolated from contaminated estuarine sediment and salt marsh rhizosphere by enrichment using either naphthalene, phenanthrene, or biphenyl as the sole source of carbon and energy. Pasteurization of samples prior to enrichment resulted in isolation of gram-positive, spore-forming bacteria. The isolates were characterized using a variety of phenotypic, morpho- logic, and molecular properties. Identification of

L. L. Daane; I. Harjono; G. J. Zylstra; M. M. Haggblom

2001-01-01

403

Macro-invertebrate populations and production on a salt-marsh in east England dominated by Spartina anglica  

Microsoft Academic Search

The populations and production of the macroinvertebrates of a Spartina anglica salt-marsh in eastern England were studied over two years. A total of fifteen species were recorded in the sediments, of which twelve species were of regular occurrence, and the total population density recorded ranged from 3,481 m-2 to 11,444m-2 over the twenty-four sampling occasions.The four most abundant species were

D. Jackson; C. F. Mason; S. P. Long

1985-01-01

404

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

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.

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

2005-01-01

405

The effects of marsh edge and surface elevation on the distribution of salt marsh infauna and prey availability for nekton predators  

E-print Network

., and ten meters from the marsh edge. During most of the year,, densities of most polychaetes and crustaceans within marsh vegetation were highest one meter from the marsh edge compared with densities farther from the marsh e ' dge. Distributions of surface...

Whaley, Shannon Diann

2012-06-07

406

Impact of land-use change and hard structures on the evolution of fringing marsh shorelines  

Microsoft Academic Search

Estuarine fringe marshes provide essential ecosystem services to coastal regions, including carbon sequestration and provision of shelter and nursery grounds for aquatic and terrestrial animals. The ability of a marsh to sustain itself by vertical accretion in response to sea-level rise is, in part, limited by inorganic sediment supply. Models attempting to forecast salt-marsh response to future sea-level rise commonly

Christopher R. Mattheus; Antonio B. Rodriguez; Brent A. McKee; Carolyn A. Currin

2010-01-01