Salt Marsh Complex Research Articles

Comparison of waterbird communities in a Mediterranean salina – saltmarsh complex

Coastal wetlands provide habitat for large numbers and many species of waterbirds. Man-made salinas are a particu-lar habitat type often found in such wetlands. This study is an initiative to understand the differences in bird communities between a salina (including evaporation ponds and prebasin) and a saltmarsh. Bird counts and nest surveys took place in the wetlands of Angelochori, Thessaloniki, Greece, in 1991, when the salina was inactive, and in 1997, 2000-01 when it was active. Counts in evaporation ponds were richer in species, abundance and nests compared to the prebasin and the saltmarsh. These three wetland types supported different bird communities. Similarities among bird communities depended on the inundation of the salina with seawater. Evaporation ponds in their inactive period presented low similarity with the communities of the prebasin and the saltmarsh ; in the active period this was observed only for the saltmarsh. Species showing clear selection for the evaporation ponds were Charadrius alexandrinus, Calidris alpina, Calidris minuta, Recurvirostra avosetta, Sterna hirundo, Sternula albifrons, Sterna sandvicensis and Haematopus ostralegus; the prebasin was preferred by Phoenicopterus roseus and Anas platyrhynchos, and the saltmarsh by Anas querquedula, Anas clypeata, Plegadis falcinellus, Tringa totanus, Tringa glareola, Tringa stagnatilis and Himantopus himantopus.

Морфолого-генетична та агрономічна характеристики контрастних за засоленням ґрунтів солонцевого комплексу Приорілля

The article presents the results of field and laboratory studies on the determination of the morphological, genetic and agronomic characteristics of the soils of the Solon complex of Prioril, contrasting in terms of salinity - the establishment of the peculiarities of the morphological structure of the profiles, the granulometric composition, and the parameters of the main agrochemical, salt and physicochemical parameters of the salt marsh of the meadow-black earth shallow salt marsh and black earth-meadow soil - as typical components of the salt complex of the Oril river valley. Standardized field survey and laboratory-analytical methods were used. It has been established that manifestations of halogenation increase with depth in the Luchno-chernozem salt marsh. Alkalinity in the humus-iluvial horizon increases to a strong degree, in deeper horizons - to a very strong one; the degree of salinity increases to medium, strong, and finally to very strong in the bedrock. According to the depth of the upper horizon of salt accumulation, this soil is classified as saline. The content of absorbed sodium in the humus-iluvial and illuvial horizons corresponds to the "saline" gradation. The chernozem-meadow soil is non-saline according to the content of toxic salts in the entire profile, there are no signs of physical and physico-chemical salinity. The content of the silt fraction in the salt marsh profile increases with depth and reaches its maximum value in the illuvial horizon, which is typical for salt marshes and is explained by the redistribution of soil colloids in the profile, the granulometric composition of the salt marsh in the humus-eluvial and illuvial horizons is light clay, in the humus-illuvial - medium clay. The profile of the chernozem-meadow soil is also heterogeneous in granulometric composition, which is heavier from medium loam in the humus horizon to heavy loam in the transitional horizons. The reason for this may be ancient alluvial processes that formed the soil-forming rock of the single-forest terrace. The content of humus in the salt pan in humus-eluvial and humus-iluvial horizons is average, the content of mineral (nitrate and ammonia) nitrogen is very low. The content of mobile potassium turned out to be elevated, and the content of mobile phosphorus was very high. In the chernozem-meadow soil, the content of humus in the humus arable horizon is high, in the first transitional one, it is average. The content of mineral nitrogen is low. The content of mobile phosphorus exceeds the upper limit of the high level by 3.5 times, and mobile potassium by 3.1 times, which is typical for the soils of closed depressions and is a consequence of long-term accumulation of surface runoff waters. Conclusions. The salt marsh complex of Priorillya with the number of salt marshes in the soil cover of about 50% is typical for the southern part of the Middle Forest Steppe in terms of the structure of soil profiles and soil halogenation. A characteristic feature of the studied salt marsh complex is the significant contrast of its components in terms of halogenation manifestations: at a short distance there are salt marsh highly saline salt marsh and leached chernozem-meadow soil without physical and physico-chemical signs of salinity.

A Wet/Dry Point Treatment Method of FVCOM, Part II: Application to the Okatee/Colleton River in South Carolina

The wet/dry point treatment method of FVCOM was applied to simulate the tide-induced flooding/drying process in the estuarine–tidal-creek–saltmarsh complex of the Okatee/Colleton River Estuary, South Carolina. The simulation results were compared with observed currents at three mooring sites and flooded areas observed from remote-sensing hypsometric measurements, demonstrating that FVCOM can robustly reproduce tidal and residual currents in the river and the flooding process onto the intertidal saltmarsh. The simulated flow field reveals that the Okatee/Colleton River Estuary is characterized by multiple residual eddies. Driven by the periodic tidal forcing, this estuarine system features a chaotic water transport process. Numerous residual eddies around the barrier complex in the Colleton River likely enhance the water exchange between the Okatee/Colleton River Estuary and the outer Broad River. A sensitivity study of flooding speed to the slope of the inter-tidal zone suggests that the saltmarsh bathymetry considerably influences the water elevation near low slack water but not on the maximum water coverage area at high slack water.

Conceptual marsh units for Fire Island National Seashore and central Great South Bay salt marsh complex, New York

The salt marsh complex of Fire Island National Seashore (FIIS) and central Great South Bay was delineated to smaller, conceptual marsh units by geoprocessing of surface elevation data. Flow accumulation based on the relative elevation of each location is used to determine the ridge lines that separate each marsh unit while the surface slope is used to automatically assign each unit a drainage point, where water is expected to drain through. Through scientific efforts initiated with the Hurricane Sandy Science Plan, the U.S. Geological Survey has been expanding national assessment of coastal change hazards and forecast products to coastal wetlands, including the Fire Island National Seashore and central Great South Bay salt marshes, with the intent of providing Federal, State, and local managers with tools to estimate the vulnerability and ecosystem service potential of these wetlands. For this purpose, the response and resilience of coastal wetlands to physical factors need to be assessed in terms of the ensuing change to their vulnerability and ecosystem services.

Early Ecological Responses to Hydrologic Restoration of a Tidal Pond and Salt Marsh Complex in Narragansett Bay, Rhode Island

Tidal exchange was restored to the flow-restricted, 2.3-ha Potter Pond salt marsh on Prudence Island in the Narragansett Bay National Estuarine Research Reserve in April 2003. Ecological monitoring was conducted for 1 year before and 2 years after restoration to quantify ecological changes. Simultaneous monitoring was conducted in a nearby marsh that served as an experimental control. Tidal restoration increased the tide range in Potter Pond from approximately 4 cm in 2000 to 120 cm in 2003. After 2 years of restoration, the height of Spartina alterniflora remained unchanged, and the same was true of the composition of the emergent marsh vegetation community. However, by 2004, the percent cover of live Phragmites australis decreased by 69%, and the average height of Phragmites decreased by 76 cm. Seven additional bird species were observed at Potter Pond after 1 year of restoration, and the number of birds observed increased from 6 to 85 per viewing effort, mostly due to large numbers of shorebirds using the newly exposed mud flats. Nekton density decreased from 100 m−2 to 38 m−2 after 1 year, probably because of the change from subtidal to mostly intertidal conditions and increased predation by birds. Initial results from monitoring demonstrate that restoration of the Potter Pond marsh complex improved tidal exchange, negatively impacted Phragmites, and increased bird use, resulting in an overall shift to a more natural functioning salt marsh system. This study also demonstrates that restoring even very small tide-restricted marshes can result in impressive ecological improvements.

Hyperspectral imagery for mapping intertidal vegetation at Roberts Bank tidal flats, British Columbia, Canada

This study assesses the effectiveness of hyperspectral airborne imagery to map the intertidal vegetation at Roberts Bank, a large salt marsh and tidal flat complex in the Fraser River delta, British Columbia, Canada. This ecosystem is an important habitat for migratory and resident birds and fish and is part of the largest single salmon-producing stream in the world, the Fraser River. Imagery acquired by the compact airborne spectrographic imager (CASI) was radiometrically and geometrically corrected and mosaicked. A simple maximum likelihood classifier was used to classify intertidal vegetation cover. Training and test sites were collected using field observations and oblique aerial photographs. Seven vegetation-substrate classes were accurately (92.3%) classified, ranging from muddy sediments in the regularly inundated tidal flat and low marsh areas, to higher marsh communities of cattails, grasses, sedges, and rushes. This study showed that both the hyperspectral and hyperspatial characteristics of the CASI imagery were important for achieving high separability among the classes due to reduced spectral mixing of different substrates at the subpixel scale when compared with simulated Landsat and Ikonos imagery.

The influence of legacy effects and recovery from perturbations in a tritrophic salt marsh complex

Abstract. 1. Much has been learned in recent years regarding the influence of environmental conditions on top-down and bottom-up effects acting on insect herbivores. Temporal variation in environmental conditions, however, has gone largely unstudied in spite of undoubtedly strong influences in most systems. 2. A 2-year study was conducted to examine the legacy effects of previous manipulations of host plant quality and parasitism pressure on the top-down and bottom-up effects influencing population densities of the salt marsh planthopper Pissonotus quadripustulatus. 3. For 10 months in 1998, a 2 × 2 factorial experiment was carried out, in which host plant quality was increased by the addition of nitrogen fertiliser, and parasitism pressure was decreased through the use of yellow sticky traps. This was followed by 2 months in the winter with no treatment applications. Treatments were then reversed in 1999 for a further 10 months. 4. In 1998, fertilisation treatments increased plant quality significantly, which resulted in strong effects on P. quadripustulatus density. Parasitism reduction treatments had weaker and time-dependent effects on the herbivore, increasing planthopper density in late summer and autumn. 5. After 2 months without treatments, previous fertilisation treatments were still influencing all response variables measured significantly. The legacy effects of fertilisation persisted for at least 7 months for the host plant, and at least 5 months for the herbivore and parasitoid. 6. Fertilisation treatments in 1999 increased P. quadripustulatus density by approximately the same percentage as in 1998, suggesting that previous reductions in parasitism had no influence on herbivore responses to increased nutrients. Parasitism reduction treatments in 1999, however, resulted in greater increases in herbivore density than in 1998, suggesting that previous increases in nutrients enabled greater responses to reductions in top-down pressure. 7. The results show that the top-down effects of parasitism attenuated more quickly than did the bottom-up effects of increased plant quality through greater nutrient availability. They also suggest that the recent history of nutrient status in an ecosystem may be important in determining the relative strengths of top-down and bottom-up forces.

A modeling study of the Satilla River estuary, Georgia. I: Flooding-drying process and water exchange over the salt marsh-estuary-shelf complex

The flooding-drying process over the intertidal zone of the Satilla River estuary of Georgia was examined using a three-dimensional (3-D) primitive equations numerical model with Mellor and Yamada's (1982) level 2.5 turbulent closure scheme. The model was forced by the semi-diurnal M2, S2, and N2 tides and freshwater discharge at the upstream end of the estuary. The intertidal salt marsh was treated using a 3-D wet-dry point treatment technique that was developed for the σ-coordinate transformation estuary model. Good agreement was found between model-data comparison at anchor monitoring sites and also along the estuary that suggested that the model provided a reasonable simulation of the temporal and spatial distribution of the 3-D tidal current and salinity in the Satilla River estuary. Numerical experiments have shown that the flooding-drying process plays a key role in the simulation of tidal currents in the main river channel and in water transport over the estuarine-salt marsh complex. Ignoring this process could lead to a 50% under-estimation of the amplitude of tidal currents. The model results also revealed a complex spatial structure of the residual flow in the main channel of the river, with characteristics of multiple eddy-like cell circulations. These complicated residual currents are formed due to tidal rectification over variable topography with superimposition of inertial effects, asymmetry of tidal currents, and baroclinic pressure gradients. Water exchanges over the estuary-intertidal salt marsh complex are asymmetric across the estuary, and tend to vary periodically on the northern side while quickly washing out of the marsh zone on the southern side. Strong Stokes’ drifting velocity was predicted in the estuary, so that the Lagrangian trajectories of particles were characterized by strong nonlinear processes that differ significantly from those estimated by the Eulerian residual currents.

NEKTON IN GULF COAST WETLANDS: FINE-SCALE DISTRIBUTIONS, LANDSCAPE PATTERNS, AND RESTORATION IMPLICATIONS

Many decapod crustaceans and fishes are common inhabitants of flooded salt marshes in the northwestern Gulf of Mexico, but spatial distributions are uneven, and population sizes are difficult to estimate. We measured fine-scale (1–10 m) distributions of nekton on the vegetated marsh surface using enclosure samplers in Galveston Bay, Texas, and used these patterns to estimate population size. Natant decapod crustaceans were abundant in the marsh; densities of juvenile brown shrimp Farfantepenaeus aztecus, white shrimp Litopenaeus setiferus, and blue crabs Callinectes sapidus were highest 1 m from the water's edge and declined rapidly to 10 m from the edge. We developed regression models to describe these fine-scale density patterns and validated the models with independent data on density distributions from two other marsh systems. We used a Geographic Information System to transfer the density models to a natural marsh landscape; the highly fragmented Elmgrove Point marsh was composed of shallow nonvegetated bottom (37.4% of the area) and Spartina alterniflora vegetation (62.6%) with ∼15% of the vegetated area within 1 m of the marsh–water interface. We estimated that this 437-ha salt marsh complex supported populations of 16.2 million brown shrimp, 15.5 million white shrimp, and 11.3 million blue crabs. We divided the marsh complex into 39 sectors and examined relationships between nekton populations and landscape-scale patterns of marsh fragmentation. The amount of edge and the population estimates in a sector increased consistently with the amount of water up to ∼20–25%. Nekton population declines were not apparent until the late stages of marsh disintegration (>70% open water). We also used our fine-scale density models to simulate the effects of adding creeks to a 1-ha created salt marsh of solid vegetation. For shrimp, 1–2 creeks/ha (or a comparable amount of edge) were required to reach populations equivalent to shallow nonvegetated bottom, and up to 6 creeks/ha were required to reach populations similar to those estimated for the natural marsh complex. Simulated populations of blue crabs reached levels in the natural marsh complex with the addition of fewer creeks (2–3 creeks/ha).

Microbial community patterns of potential substrate utilization: a comparison of salt marsh, sand dune, and seawater-irrigated agronomic systems

Microbial community patterns of potential substrate utilization were examined at eight study sites. Sample microbial communities were from different habitats including constructed and natural salt marshes, a seawater-irrigated agronomic system, and, for a non-saline comparison, a coastal sand dune. Microbial communities were characterized by patterns of sole carbon source (substrate) utilization using Biolog microplates. Sampling sites were characterized based on analysis of soil biotic and physical properties. Relationships among the eight microbial communities based on substrate utilization potential, and among the sampling sites based on biotic and physical characteristics, were similar. Microbial communities from natural salt marshes at two geographically distant locations had similar patterns of potential substrate utilization. The constructed salt marsh community was dissimilar from the other communities (including two from natural salt marshes located in the same salt marsh complex) in potential substrate utilization. Seawater-irrigated agronomic sites were distinct from the other saline soil sites, possibly due to disturbance caused by agronomic practices. Potential substrate utilization of the microbial communities at the agronomic sites was intermediate compared to the other sites, e.g. higher than the constructed marsh but lower than the natural salt marshes. Relationships among the study communities determined by microbial potential substrate utilization and analysis of site characteristics primarily reflected similarity in habitat type, while geographical influences were less important.

Sediment aggregation in a salt-marsh complex, Great Sound, New Jersey

Suspended sediments in a major tidal channel in southern New Jersey consist dominantly of three inorganic particle types: single grains, organic-mineral aggregates and fecal pellets. Single mineral grains range from clays (<2 μm) to fine sands (200 μm), but are dominant only in size fractions above 88 μm. Organic-mineral aggregates are characterized by low settling velocities (<4.7 × 10 −2 cm/s) and densities (<1.4 mg/m 3), and comprise approximately 70% of the suspensate under fair-weather conditions. Fecal pellets are somewhat more dense (1.7–1.8 mg/m 3) and settle more rapidly (4.7 × 10 −2–5×10 −1 cm/s) than organic-mineral aggregates. Because of the contrasting settling velocities, organic-mineral aggregates constitute an ever present background suspensate population, whereas single grains and fecal pellets are dominant only on maximum tidal flow or under storm conditions. Organic-mineral aggregates are composed almost exclusively of grains smaller than 6 μm, so that they are the dominant vehicle by which fine-grained particles are transported and deposited. Fecal pellets are most commonly comprised of a wide range of particle sizes, although occasionally their constituent grains exhibit a well-defined mode of particles ≈6-<16 μm in size. Given their relatively rapid settling velocities, fecal pellets are probably an important mechanism by which silt- and clay-size particles are introduced to the coarse-grained deposits (sands) which characterize the major tidal channels.

Hydrodynamics and sedimentation in a back-barrier lagoon-salt marsh system, Great Sound, New Jersey — A summary

Southern New Jersey is a barrier island coast, characterized by a tide-dominated hydrographic regime. Great Sound, a shallow, open lagoon which is fed by tidal channels within the back-barrier salt marsh complex, is a sediment sink, apparently for detritus imported from the inner continental shelf through two tidal inlets. Study of the system tidal hydrodynamics and sediment accumulation patterns provides the basis for a numerical sedimentation model. This model predicts rapid accumulation of coarse-grained (> 20 μm) sediment near the Intracoastal Waterway which cuts through Great Sound, and dominance of storm-related sedimentation events. Observations generally confirm the model predictions. Sands are deposited rapidly on flood tidal deltas associated with the two major channels, Great Channel and Ingram Thorofare, and along the Intracoastal Waterway. Finer detritus is transported predominantly as organic-mineral aggregates, and accumulates slowly (< 2.7 mm/yr) in the southwestern and eastern parts of the sound. Resuspension of bottom sediments is common in the shallow (0.6 m) sound due to wave action and flood tidal currents on the deltas ( U 0.4 d max ≲ 42 cm/s). Low tidal flow velocities ( U 0.4 d max < 18 cm/s) over much of Great Sound and the presence of macroalgae in some locations, however, promote net accumulation. Although sediment deposition and accumulation data are variable, the range of accumulation rates suggests that recent accretion in Great Sound is approximately equivalent to the local sea-level rise of 4 mm/yr.

Shoreline Depositional Environments of Glen Rose Formation (Lower Cretaceous) in Type Area, Somervell and Hood Counties, Texas: ABSTRACT

ABSTRACT The Comanchean Series in north-central Texas was deposited along the margin of a shallow sea as it transgressed northwestward across the Central Texas platform during early Cretaceous time. A lithologic and paleontologic study of the Glen Rose Formation (uppermost Trinity Division) in its type area was undertaken to define the shoreline sediments deposited during Aptian-Albian time. The studied interval was subdivided into informal units A, B, and C based on lithology and fossil content. The primary focus was on the lowermost Unit A for purposes of facies analysis. Unit A comprises a clastic-to-carbonate transition deposited in a seaward-fining tidal-flat salt-marsh complex. Eight distinct facies were identified, including the calcareous sandstone, calcareous shale, bivalve shale, oyster shale, transitional terrigenous-carbonate, dolomite, bioclastic packstone-grainstone, and shell fragment wackestone facies. These facies were deposited in sand flats; small fluvial creeks; an ecologically complex, mud-dominated intertidal flat; and an subtidal, nearshore lagoon. Thin bioclastic packstone-grainstones and dolomites of the high energy intertidal and supratidal environments regularly interrupt the terrigenous clastic facies. The microfossils are severely restricted to absent, and the macrofossils are dominated by euryhaline bivalves (including Corbula martinae), gastropods, serpulid worm colonies, and dasychladacean algae. Other abundant nearshore features include salt-tolerant land plants, dinosaur tracks, desiccation cracks, and localized concentrations of gypsum and barite. This tidal flat-salt marsh complex received sediments from both terrestrial and marine sources. A broad intertidal zone of vegetated sand and mud flats was dissected landward by small fluvial creeks and seaward by storm beaches and marine inlets. The fine size of the terrigenous clastics indicates a low energy flat with a very gently seaward-dipping substrate. A warm, semi-arid to arid climate favored the development of salt marshes and the precipitation of evaporites. The faunal restriction also suggests the abnormal salinites of tidal marshes. this sequence is considered ocmparable to the Holocene salt marshes on Sapelo Island, Georgia, based on similar seaward-fining substrates, sedimentary structures, and biological components. Unit B (the Thorp Spring Member) consists of a peloidal, molluscan packstone-wackestone facies. The fossil assemblage (including Orbitolina texana) suggests slightly brackish to near normal marine salinites in a shallow, restricted platform lagoon. Thorough bioturbation indicates deposition in the well aerated subtidal zone. Unit C is characterized by coarsening-upward limestones capped with thin intertidal-supratidal deposits, indicated a transitional nearshor lagoon-tidal flat environment. Repeated inundation with marine waters produced stacked, shallowing-upward sequences. The entire studied interval reflects fluctuating sea levels along a line of section nearly normal to the paleoshoreline, and represents the final waning of Glen Rose seas. End_of_Record - Last_Page 588-------

Does salt marsh fertilization enhance shellfish production? An application of flow analysis

The method of flow analysis, which is similar to economic input-output analysis, is presented as a means of making flow models of ecological systems more useful to environmental managers. This paper considers as an illustration the extent to which nitrogen fertilizer added toSpartina salt marsh sediments can enhance shellfish growth. Nitrogen flow models of both the Barataria Bay salt marsh complex of coastal Louisiana and the Sippewissett Marsh of western Cape Cod are analyzed. The analysis shows the transfer of added nitrogen to shellfish growth viaSpartina growth, decomposition, and detrital feeding to be considerably less efficient than its transfer toSpartina growth itself. These results are similar for both marsh systems, despite their great physical differences and despite the inclusion of considerably more microbial processing of nitrogen in the Barataria Bay model than in the Sippewissett models. The results suggest that the most efficient mechanism by which added nitrogen could enhance shellfish growth in salt marshes may have to bypass the route through theSpartina life cycle.

Profile of Biogenic Sedimentary Structures in Holocene Barrier Island--Salt Marsh Complex, Georgia: ABSTRACT

Biogenic sedimentary structures, many of which are characteristic of particular depositional environments, are abundant among Holocene barrier island-salt marsh habitats of coastal Georgia. The major environments represented are (1) beaches, including the shoreface, lower and upper foreshore, backshore, dunes, and washover fans; (2) salt marshes, consisting of the low marsh, high marsh, and salt pans; and (3) estuaries and tidal streams, including channel deposits, point bars, stream banks, and natural levees. Biogenic sedimentary structures in these environments consist of bioturbate textures and tracks, trails, burrows, and dwelling tubes, and are produced chiefly by polychaetes, gastropods, pelecypods, decapods, amphipods, and insects. Such structures, either singly or as assemblages of lebensspuren, are ordinarily sufficient to delimit major habitats. Further, most of these structures are capable of preservation, and many of them have been documented in the Pleistocene of Georgia and Florida. End_of_Article - Last_Page 2036------------