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Tesi sul tema "Salt marsh"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 31 agosto 2024

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1

Fritz, Alyce T. "Trophodynamics of estuarine (salt marsh) heterotrophic nanoplankton (microbial ecology, salt marsh ecology, choanoflagellates, Virginia)". W&M ScholarWorks, 1986. https://scholarworks.wm.edu/etd/1539616651.

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Seasonal occurrence and activity of heterotrophic nanoflagellates (HNANO or heteroflagellates) and bacteria were studied in a sheltered brackish water embayment of Chesapeake Bay wetlands (Virginia, USA) over a three year period (1981 - 1984). Epifluorescence direct counts and Scanning and Transmission Electron Microscopy (SEM and TEM) techniques were used for the description of organisms, enumeration, and biomass determinations. Seasonal bacterial growth rates and growth and grazing rates of bactivorous HNANO were estimated using diffusion chambers equipped with Nuclepore polycarbonate membrane filters in natural salt marsh tidal pools. Environmental monitoring of nanoplankton populations revealed a seasonal pattern of bacterial abundances with temperature while heteroflagellate abundances and growth rates showed no seasonal pattern nor correlation with fluctuations in bacterial densities. Heteroflagellate populations were dominated by 34 to 50 (mu)m('3) sized monads, choanoflagellates, bodonids, and Paraphysomonas sp., all found in varying abundances throughout the year. Blooms were concurrent with extended low tide or specific bacterial populations (i.e., cyanobacteria) typical of spring and autumn periods. Heteroflagellate growth in diffusion chambers reflected the environmental blooms and increased diversity of low water assemblages. Growth and grazing rates of heteroflagellates at ambient densities thus could account for 20 to 80% of daily bacterial carbon production. Although heteroflagellate ingestion rates did not regulate seasonal bacteria densities or vice versa, maximum growth of bacteria and heteroflagellates in chambers was closely coupled. Heteroflagellate grazing activity may regulate the rate of bacterial production by preventing substrate limitation and maintaining the population in an active growth phase. The seasonal study demonstrated the dynamic nature of nanoplankton populations during autumn and spring transitional periods. SEM photomicroscopy revealed that the dominant component of spring blooms may be composed of several members of the loricate choanoflagellate family, Acanthoecidae. Using modified EM techniques, eleven Acanthoecidae choanoflagellates species, identified from spring in situ chamber experiments, were described. In situ growth and grazing rates for the spring chamber populations ranged from 0.023 h('-1) to 0.196 h('-1) and 40 to 210 bacteria h('-1) respectively. These high rates represent an opportunistic response to optimum conditions and an expression of maximum grazing potential. (Abstract shortened with permission of author.).

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2

Marshall, William Alderman. "Geochronology of salt-marsh sediments". Thesis, University of Plymouth, 2007. http://hdl.handle.net/10026.1/2826.

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Salt-marsh sediments can provide important achives of past sea levels if they can be securely dated. This thesis investigates eight methods for dating salt-marsh sediments. These include traditional and established dating methods (¹⁴C dating and the radionuclides ¹³⁷Cs and ²¹ºPb) and more novel approaches to dating the deposition of salt-marsh sediments (palaeomagnetic dating, the use of' atmospheric stable lead deposition, tephra chronologies, pollen markers, SCP analysis and the use of atmospheric ¹⁴C 'bomb spike' and high-precision AMS ¹⁴C measurements). Sites were selected to provide contrasting sediment sequences that differed both in lithology and accumulation rates and included salt marshes from the Taf estuary (southwest Wales), the Arne Peninsula (southern England) and Vioarholmi (western Iceland). The investigations in the Taf estuary produced the first palaeomagnetic chronology from a salt marsh. From the Arne Peninsula this thesis reports the first successful use of bomb-spike calibrated ¹⁴C analyses in a salt marsh as well as high-precision AMS ¹⁴C ages for the 'problem' period AD 1700-1950. Stable Pb analysis at all three sites produced a number of chronological markers that signalled the timing of increases in industrial Pb emissions, and the later use of Pb petrol additives during the 20th century. In addition, a unique isotopic signal, attributed to the working of Pb metal during the height of the Roman Empire in Europe, was found in the Icelandic sediments. The radionuclides ²¹ºPb and ¹³⁷Cs produced precise chronologies for the last 100 yr in the Taf estuary. However, post-depositional mobility of ¹³⁷Cs on the Arne Peninsula and low ²¹ºPb concentrations at Vioarholmi prevents the construction of reliable ²¹ºPb and ¹³⁷Cs chronologies. In contrast, the use of tephra at Vioarholmi, and pollen and spheroidal carbonaceous particle markers on the Arne Peninsula, showed great potential as independent unique-event dating tools that could be used to constrain conventional ¹⁴C calibrations. Finally, the chronological information produced by all the individual methods was combined to construct an integrated chronology for each site. This approach significantly reduced age uncertainties and produced higher resolution, and more robust, salt-marsh sedimentation histories

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3

Nuttle, William Kensett. "Elements of salt marsh hydrology". Thesis, Massachusetts Institute of Technology, 1986. http://hdl.handle.net/1721.1/14991.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil Engineering, 1986.
MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Includes bibliographies.
by William Kensett Nuttle.
Ph.D.

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4

Pepper, Margaret A. "Salt marsh bird community responses to open marsh water management". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 61 p, 2008. http://proquest.umi.com/pqdweb?did=1597631021&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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5

Bin, Yasin Z. "The ecology of salt marsh control". Thesis, University of Salford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381722.

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6

Reed, D. J. "Suspended sediment transport in salt marsh creeks". Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355891.

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7

Husain, Mohd Lokman bin. "Salt marsh sedimentary response to sea level rise". Thesis, University of Hull, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384865.

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8

Tobias, Craig 1967. "Nitrate reduction at the groundwater - salt marsh interface". W&M ScholarWorks, 1999. https://scholarworks.wm.edu/etd/1539616877.

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The influence of groundwater discharge on the hydrology and biogeochemical cycling of nitrogen in a fringing intertidal wetland was studied by characterizing groundwater discharge, determining N-cycling rates in cores, and examining nitrate reduction in situ using 15N enrichment and natural gradient tracer techniques. Groundwater discharge was estimated by three independent methods: Darcy's Law, a water/salt mass balance, and a subsurface tracer test. Seasonal patterns of discharge predicted by Darcy's Law and the mass balance were similar. Discharge maxima and minima occurred in April and September, respectively. The water/salt mass balance provided the more reasonable estimate of groundwater flux at high flows, and the Darcy technique was better at estimating low flow at our site. The high discharge seasonally purged porewater from the marsh to the estuary, and marsh processing of groundwater solute loads would occur only during this period. Mineralization, nitrification, potential denitrification (DNF), and potential dissimilatory nitrate reduction to ammonium (DNRA) rates were estimated in cores during periods of high and low groundwater discharge. All N-cycling processes occurred in sediments <1.5 meters deep. Natural abundance isotope measures, and core experiments indicated that coupled nitrification-denitrification was a sizeable sink for mineralized N. Mineralization, nitrification, and DNRA rates were 6--12x greater during Spring high discharge. DNF rates, were 10x higher during Fall low discharge. Despite accelerated mineralization and nitrification during high discharge, the DNF:DNRA ratio was <1, indicating that more of the N cycled through nitrification was retained as ammonium rather than exported as dinitrogen through coupled nitrification-denitrification. Nitrate reduction pathways in the marsh were studied in situ by creating a nitrate plume enriched in 15N. Isotopic enrichment of the ammonium, PON, dissolved nitrous oxide, and dissolved dinitrogen pools initially accounted for 14--36% of the observed nitrate loss. Adjustment of these estimates with potential losses through gas evasion, and ammonium turnover, accounted for nearly all of the N missing from the mass balance. The adjusted mass balance indicated that 68% of the nitrate load was denitrified, and 30% was assimilated and retained in the marsh.

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9

Miller, Carrie J. "Factors influencing algal biomass in hydrologically dynamic salt ponds in a subtropical salt marsh". [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1392.

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10

Sibley, Samuel D. Jr. "The Impact of Salt Marsh Hydrogeology on Dissolved Uranium". Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7262.

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We quantified U removal and investigated the efficacy of uranium as a quantitative tracer of groundwater discharge in a headwater salt marsh of the Okatee River, Bluffton, SC. Determining the magnitude of U removal is important for advancing U as a tracer of paleo-oceanic conditions. Since salt marsh groundwater is typically enriched in nutrients and other biologically and chemically reactive species, quantifying groundwater discharge from marshes is critical for understanding the ability of salt marshes to modify the chemistry of important species in surface waters. We hypothesized that water-column U(VI) was removed by tidally-induced advection of surface water into permeable, anoxic salt marsh sediments, a process resulting in bacterially-mediated precipitation of insoluble U(IV)O2 and/or sorption of uranium to iron-oxides at the oxic/anoxic sediment interface. Furthermore, we suggested that hydraulic pressure gradients established by marsh-surface tidal inundation and seasonally-variable rainfall promote the discharge of salt-marsh-processed, uranium-depleted groundwater to tidal creeks, producing the surface-water U-removal signal. Groundwater and surface water data revealed non-conservative uranium behavior. We documented extensive uranium removal from shallow marsh groundwater and seasonally variable uranium removal from surface waters. These observations allowed for the calculation of seasonally-dependent salt marsh uranium removal rates. On a yearly basis, our removal rate (58 to 104 mol m-2 year-1) reemphasized the importance of anoxic coastal environments for U removal. High uranium removal, high barium concentration water observed seeping from creek banks at low tide supported our hypothesis that groundwater discharge must contribute to uranium removal documented in tidal surface waters. Average site groundwater provided an analytically reasonable endmember for explaining uranium depletion in surface water. Therefore, we used three endmember mixing models for estimating the fraction of surface water with presumed a groundwater signature. Our discharge estimates of 8 to 37 L m-2 day-1 agreed closely with previously published salt marsh values. Seasonality in discharge rates can be rationalized with appeal to seasonal patterns in observed rainfall, tidal forcing, and marsh surface bioturbation. Although more work is needed, the results of this portion of the study suggest that U may be an effective quantitative tracer of groundwater discharge from salt marshes.

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11

Ruddy, Gavin. "Microenvironmental modelling of redox chemistry in salt marsh sediments". Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359334.

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12

Smillie, Christian. "The impacts of mine pollution on salt marsh flora". Thesis, University of Exeter, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.479199.

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13

Wesenbeeck, Bregje Karien van. "Thresholds and shifts : consequences of habitat modification in salt-marsh pioneer zones /". PURL, 2007. http://www.arlis.org/docs/vol1/A/433191982.pdf.

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14

Newton, Jennifer Denise. "Evidence for manganese-catalyzed nitrogen cycling in salt marsh sediments". Thesis, Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-04072006-133610/.

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Thesis (M. S.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2006.
Taillefert, Martial, Committee Chair ; Ingall, Ellery, Committee Member ; DiChristina, Thomas, Committee Member.

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15

Emmerson, Richard Hugh Christian. "Salt marsh restoration by managed retreat : metal and nutrient fluxes". Thesis, Imperial College London, 1997. http://hdl.handle.net/10044/1/8454.

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16

Wang, Jian. "Carbon Dioxide and Methane Emissions from a California Salt Marsh". Thesis, University of California, Santa Barbara, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10687609.

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Wetland carbon sequestration is offset by carbon dioxide (CO₂) and methane (CH₄) emissions for which the magnitudes remain coarsely constrained. To better understand the spatial and temporal variations of gaseous carbon fluxes from marsh soils in a Mediterranean climate, I collected air and soil samples over the course of 10 months at Carpinteria Salt Marsh Reserve (CSMR) located in the County of Santa Barbara, California. The CSMR consists of four zones characterized by differences in elevation, tidal regime, soil properties, and vegetation. Twelve static chambers were deployed among two lower marsh zones, a mudflat, and a marsh-upland transition zone for fortnightly flux measurements from September 2015 to May 2016. In August 2015 and June 2016, soil cores up to 50 cm deep were extracted near the chambers, segmented by depth, and analyzed for soil moisture, bulk density, particle size distribution, electrical conductivity, pH, organic/inorganic carbon, and total nitrogen content. Averaged over the 9-month study period, the marsh-upland transition zone had the highest CO₂ fluxes at 5.3 ± 0.7 g CO₂ m^–2 d^–1, followed closely by the lower marsh zones (3.8 ± 0.6 g CO₂ m^–2 d^–1 and 2.8 ± 0.7 g CO₂ m^–2 d^–1), which were one order of magnitude higher than the CO₂ fluxes from the mudflat (0.4 ± 0.1 g CO₂ m^–2 d^–1). The CO₂ fluxes varied significantly on a seasonal scale but were not consistently correlated with environmental variables measured. The CH₄ fluxes had no clear seasonal patterns, but overall CH₄ flux rates from the lower marsh zones (2.2 ± 1.5 mg CH₄ m^–2 d^–1 and 1.9 ± 0.2 mg CH₄ m^–2 d^–1) surpassed those from the mudflat (0.2 ± 0.06 mg CH₄ m^–2 d^–1) by an order of magnitude, and the marsh-upland transition zone was a net methane sink (-0.07 ± 0.1 mg CH₄ m^–2 d^–1). The CH₄ fluxes correlated well with most soil properties by zone. Our results show that soil gaseous carbon fluxes from a coastal salt marsh vary by salt marsh zone.

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17

Kurian, Ruth A. "Temperature and thermal diffusivity of Sapelo Island salt marsh sediments". Thesis, Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/25779.

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18

Murray, Anne Louise. "Tidal exchanges in a backbarrier salt marsh, North Norfolk, England". Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242992.

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19

Don-Pedro, Patience Osayemwenre. "Differential responses of perennial salt marsh plants to oil pollution". Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/38290.

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20

Schiebel, Hayley Nicole. "Dissolved organic carbon fluxes from a New England salt marsh". Thesis, University of Massachusetts Boston, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10118488.

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Blue carbon systems (mangroves, salt marshes, and seagrass beds) sequester large amounts of carbon via primary productivity and sedimentation. Sequestered carbon can be respired back to the atmosphere, buried for long time periods, or exported (“outwelled”) to adjacent ecosystems. This study estimates the total outwelling of dissolved organic carbon (DOC) from the Neponset Salt Marsh (Boston, Massachusetts) as well as the major plant and sediment processes contributing to the overall flux. The total export was quantified via high-resolution in situ chromophoric dissolved organic matter (CDOM) measurements as a proxy for DOC using 12 years of transect data. Seasonal trends, alternate sources of fresh water, and long-term trends in DOC export will be discussed. To characterize the percentage of this flux attributable to marsh vegetation, the effects of sunlight, anoxia, plant species, biomass type, and microbes on plant leaching were studied using incubations of above- and belowground biomass over four seasons. Seasonal comparisons led to the “Fall Dump” hypothesis in which higher DOC concentrations are leached during the fall when marsh plants senesce for winter. In summing seasonal fluxes from vegetation, approximately 46% of the total DOC export from the marsh may be attributed to leaching from the three dominant plant species in the Neponset Salt Marsh. The influence of seasonality and climate change (e.g., drought) on both overland flow and deep sediment pore water leaching were also investigated. Depending on season and marsh condition, overland flow and sediment pore water leaching combined could contribute 8–16% of the total export from the marsh. Finally, the influence of natural sunlight irradiation and microbes on the release of dissolved organic matter (DOM) from resuspended surface sediments was studied and approximately 11–22% of the total export could be attributable to this flux. Approximately 49 mol C m⁻² yr⁻¹ are outwelled from the Neponset Salt Marsh and, using net primary productivity estimates from the literature, 16 ± 12 mol C m⁻² yr⁻¹ are buried in the Neponset Salt Marsh.

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21

Bristow, Gwendolyn. "The effect of tidal forcing on iron cycling in intertidal salt marsh sediments". Thesis, Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-07102006-112540/.

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Thesis (M. S.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2007.
Dr. Emanuele Di Lorenzo, Committee Member ; Dr. Ellery Ingall, Committee Member ; Dr. Martial Taillefert, Committee Chair.

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22

Taylor, David Ian. "Tidal exchanges of carbon, nitrogen and phosphorus between a Sarcocornia salt-marsh and the Kariega estuary, and the role of salt-marsh brachyura in this transfer". Thesis, Rhodes University, 1988. http://hdl.handle.net/10962/d1004524.

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Tidal exchanges of organic carbon, nitrogen and phosphorus between a south temperate Sarcocornia marsh and its associated estuary are examined. Subterranean water flow was small, and the hydraulic exchange between the two systems largely surficial. The dominant tidal signal was semi-diurnal, and the extent of inundation of the marsh varied considerably as a consequence of interactions of semi-lunar tidal cycles with changes in daily mean sea level. Annual net fluxes of organic carbon were directed from the marsh to the estuary, but amounted to less than 2% of marsh aerial net primary productivity. This indicates the incompatibility of E.P. Odum's outwelling hypothesis to this marsh-estuarine system. The direction of net flux of organic carbon switched on a time-scale of days. These directions were largely correlated with mesoscale oceanic events, which materially altered the extent of marsh inundation, and which provided evidence of the mutual exclusivity of outwelling of DOC from the marsh and oceanic upwelling. Laboratory mesocosm experiments using intact marsh blocks of sediment from the marsh were conducted to identify the proximate processes and interactions at the marsh-water interface responsible for the variability of marsh-estuarine exchanges. Patterns of fluxes of organic carbon, total nitrogen and phosphorus were markedly different in the structurally contrasted tidal creek and Sarcocornia Zone regions of the marsh. Both regions exported these components, but the fluxes of organic carbon and total phosphorus were significantly larger from the tidal creek than from the Sarcocornia zone, and the opposite applied to nitrogen. The presence of brachyuran crabs . the most numerous macrofauna on the marsh enhanced the flux of carbon, nitrogen and phosphorus from the marsh biocoenosis, largely as a result of the effect of their bioturbation. Evidence is examined which suggests that differential mobilization of nutrients in the two zones by crabs is responsible for biogeochemical coupling of these two regions , which may account for the elevated productivity of salt- marsh systems

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23

Martinson, Holly Marie. "Critical patch sizes and the spatial structure of salt marsh communities". College Park, Md.: University of Maryland, 2009. http://hdl.handle.net/1903/9938.

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Thesis (Ph. D.) -- University of Maryland, College Park, 2009.
Thesis research directed by: Behavior, Ecology, Evolution, and Systematics Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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24

Joslin, Paul Anthony. "The ecology of a cyanobactivorous salt marsh amoeba, Thecamoeba pulchra (Biernacka)". Thesis, Lancaster University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302961.

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25

Smith, M. H. "Life-histories of annual plants in a heterogeneous salt marsh environment". Thesis, University of East Anglia, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356614.

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1. Population differentiation was studied in the halophytic annuals Salicornia and Suaeda maritima at Stiffkey, Norfolk, England. 2. The salt marsh at Stiffkey shows considerable spatial and temporal heterogeneity. The gradient in height across the marsh results in extreme differences in tidal regime and edaphic conditions, while physiographic features such as salt pans, creeks and their associated levees, impose smaller-scale heterogeneity. Salicornia and Suaeda maritima occur throughout the marsh and exhibit striking variations in phenotype associated with particular microhabitats. 3. Monitoring of field populations of these annuals during successive phases of the life cycle showed that morphologically distinct populations differed in aspects of their life-histories. These differences included the control of dormancy and germination, the phenology of growth and development, and fecundity. 4. The genetic and environmental components of these differences were examined in reciprocal transplant experiments of both seed and seedling material and in uniform growth conditions in growth cabinets and in a glasshouse. Survival and many aspects of both vegetative and reproductive performance were measured throughout the life cycle. 5. Much of the variation in natural populations was attributable to differences in plant density. Plant size and fecundity were extremely plastic in their response to density. Phenological features were more stable and structural characters were most stable. Survival was density independent. 6. Environmental differences between sites also had profound effects on growth and survival of the plants. In particular, some aspect of hypersaline edaphic conditions and the presence of perennial vegetation reduced considerably the survival and growth of annual plants. 7. When the density dependent components of performance were removed, and plants from different parts of the marsh were grown under the same environmental conditions, significant differences remained between them in morphology and life-history. This applied both to plants grown on the same site in the field and to those grown under uniform conditions. These differences between populations were likely to be genetic. 8. Three sorts of explanation of the adaptive significance of genetic differences between populations were examined. First, the relative performance and survival of local and foreign populations planted on the same site were examined at all stages of the life cycle. These differences were expressed as relative selection coefficients. The relative success of populations was also measured over an entire generation by comparing numbers of seeds sown with those produced. This gives an estimate of the relative fitness of the local and foreign populations at each site. Second, correlations were examined between life history characteristics of the populations and features of their environment that were likely to act as selective agents. Third, parallel variation was examined between Salicornia and Suaeda maritima populations within the same zone of the marsh. 9. All three of these approaches were adopted to achieve a concensus of information. Each approach suffers different limitations and the interpretation of information obtained from each is discussed critically. 10. Selection usually favoured the survival and growth of local relative to that of foreign populations at all sites and at all stages in the life cycle. The highest selection coefficients were for survival of the lower marsh 1 t" ... upper morsn 1 . popu a lon ln competltlon wlth the~perennla vegetatlon during the growth phase (ca 0.7) and for seed production of upper marsh Suaeda maritima on the lower marsh (ca 0.9). 11. Measures of the intensity of selection at specific stages of the life cycle did not predict accurately the magnitude of selection over an entire generation. All populations planted as seeds on their native site were relatively fitter than foreign populations transplanted to same site. Relative fitness is likely to have been underestimated because the local and foreign populations at each site were not grown in competition with one another. 12. Chromosome numbers were counted in Salicornia plants typical of the populations recognized by their morphologies and life histories. Three tetraploid and three diploid Salicornia populations and three diploid Suaeda maritima populations were identified at stiffkey. 13. The breeding systems and possible genetic structures of Salicornia and Suaeda maritima populations are discussed in relation to population differentiation. salicornia populations appear to be largely inbreeding and consist of many predominantly homozygous lines. occasional outcrossing provides sufficient variability to allow divergence of the populations under selection. population differentiation in Suaeda maritima apears to be maintained by restriction of gene flow between populations by divergence in flowering times, as well as by intense selection.

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Fenwick, Helen. "The Lincolnshire marsh : landscape evolution, settlement development and the salt industry". Thesis, University of Hull, 2007. http://hydra.hull.ac.uk/resources/hull:5669.

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The coastal wetland, known as the Lincolnshire Marsh, is investigated in order to understand the ways in which people in the past exploited coastal zones. This research into a previously neglected area has tested the validity of' Rippon's (2000) three-part model ofcoastal strategies - exploitation, modification and transformation. The Lincolnshire Marsh, as considered in this thesis, covers a region from Cleethorpes in the north to Wainfleet in the south. The study area also encompasses areas of the adjacent dry land, of the Middle Marsh and the Wolds, to the west. A wide range of data are studied to help build a picture of the methods people have used to settle this region, from earlier prehistory through to the sixteenth century. It has been shown that the strategies adopted have varied over space and time, and that the region cannot be viewed as a single developmental unit. Four separate development zones have been postulated. showing differences in the visible Bronze Age reactions to rising sea-levels; in the concentration of salt production to specific regions, in certain periods; in the place-name evidence; in the Domesday landholdings; and in the settlement pattern. Following Rippon's (2000) three-part model it has been shown that for the majority of its history, people have been happy to exploit the natural resources on offer along the Marsh, whether they be salt or the natural havens or pasture. Although salt was important in this development, it is limited in specific periods, to specific areas. On occasion the occupants of the Lincolnshire Marsh have modified the coast to aid with settlement and exploitation; however, there were no large-scale attempts at reclamation, or transformation until the sixteenth century. In this respect the region is significantly different from many other coastal wetlands in north-west Europe which see large-scale attempts at transformation by the thirteenth century at the latest. A subdivision has also been apparent at the modification stage - in some cases this strategy was intentionally adopted, in other areas the modification was accidental, a by-product of the salt industry.

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French, Jonathan Rupert. "Hydrodynamics and sedimentation in a macro-tidal salt marsh, Norfolk, England". Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235907.

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This thesis integrates existing work on surface accretion rates with more recent advances in the understanding of creek hydrodynamics. Concepts drawn from various disciplines are formulated into a revised framework within which marsh sedimentation may be better understood. Channel flux studies that treat the marsh as a 'black box' contribute little to our understanding of marsh functioning, whatever the accuracy of their execution. Marshes are better conceptualised as complex bio-sedimentary systems, characterised not only by an intimate relationship with adjacent tidal waters, but also by numerous internal pathways along which transport of water and materials may take place. Data relating to surface sediments, surface sedimentation, channel and over-marsh hydrodynamics, and suspended sediment composition and settling behaviour have been obtained within a relatively mature back-barrier marsh, 54 ha in area, at Scolt Head Island, on the north Norfolk coast. Tidal range averages 3.2m at neaps and 6.4m at springs. The annual sediment input to the marsh surface is estimated at 675 tonnes, equivalent to a mean accretion rate of approximately 0.26 cm/year. The broad pattern in sedimentation reflects surface topography via its control over inundation frequency. Locally, however, proximity to the creek system as an intermediate sediment source determines the rate and nature of sedimentation. The formation of composite particles via the action of flocculation and organic binding agents determines the depositional behaviour of fine cohesive sediment introduced to the marsh. Particle fall velocities are thereby enhanced, with settling from over-marsh tidal flows being a continuous process and not confined to slack water. Reworking of newly deposited material by deposit feeding gastropods appears to be intense over much of the marsh, and may be an explanation for the paucity of sedimentary structures. The marsh surface acts as a topographic threshold separating markedly different spring and neap creek flow regimes. Morphological development of the creeks is effectively confined to ebb-dominated spring tides, when export of sand occurs. Though the creeks act as effective conduits for material transport, a large proportion of the total spring tidal prism may be exchanged directly over the marsh edge. These results may be viewed in the context of present concern over rising sea levels linked to human-induced global warming. Scenarios for future sea-level change vary widely, though most estimates put the present rate of eustatic rise at approximately 1-2 mm/year. Subsidence along this coast is around 1mm/year. Thus many marshes exist in delicate equilibrium with present relative sea level. A numerical model incorporating quasi-continuous deposition, annual tide data, and eustatic and crustal movements successfully simulates historic marsh sedimentation along the north Norfolk coast and provides an insight into the possible effects of future eustatic changes.

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28

Hoyt, Kimberly Ann. "Levels of metals from salt marsh plants from Southern California, USA". Diss., [La Jolla] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p1467903.

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Thesis (M.S.)--University of California, San Diego, 2009.
Title from first page of PDF file (viewed September 15, 2009). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 80-91).

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29

Dos, Santos Pereira Maria da Gloria. "Bacterial degradation of linseed and sunflower oils in salt marsh sediments". Thesis, Bangor University, 1999. https://research.bangor.ac.uk/portal/en/theses/bacterial-degradation-of-linseed-and-sunflower-oils-in-salt-marsh-sediments(4697b1cb-815d-46a6-8b52-880c0cfcf62c).html.

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This work investigated the consequences of vegetable oils spills in salt marsh sediments. The role of autochthonous bacteria in the oils degradation and degradative pathways were also studied 'in situ' and 'in vitro'. Simulated spills of sunflower and linseed oils revealed that both oils penetrated the sediments at a rate of 10-7 CM2 s-1. However, whereas 60% of the linseed oil had disappeared from the sediments after 2 months most of the sunflower oil remained after 6 months. Differences were noted in the adsorption of the oils to sediment particles and the depth at which they accumulate and these factors most likely influenced the route of the oil degradation and the sediments properties such as permeability. The contamination of the sediments with vegetable oils lead to a noticeable reduction in the abundance of plant roots and infauna. The abundance of aerobic, anaerobic and sulphate reducing bacteria in the sediments was increased by the addition of both oils, with linseed oil supporting greater bacterial density than sunflower oil. During the course of the experiment the relative abundance of oil degrading bacteria also increased. As a consequence of the increased bacterial activity, the sediments pH and Eh decreased and anoxic conditions were established, earlier in the case of linseed than that of sunflower oils. The degradation of the oils appeared to be a sequential process, initiated by the aerobic and/or anaerobic bacteria and continued by the sulphate reducing bacteria which themselves where unable to utilise the raw oils. The original composition of both oils underwent alterations mostly associated with their main fatty acid: the concentration of 18: 3(o3 and 18: 2o)6 in linseed and sunflower oil, respectively, decreased whereas that of the remaining fatty acids increased. As a result of the bacterial degradation of the vegetable oils 'new' fatty acids were detected and their identification was attempted using GC-MS analysis of their picolinyl and methyl esters. Various degradative pathways of linseed and sunflower oils involving the formation of the 'new' fatty acids are suggested with isomerisation, hydrogenation and P-oxidation as the primary routes for the degradation.

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Al-Khayat, Jassim Abdulla A. A. "Biodiversity and biology of salt marsh and mangal Brachyura in Qatar". Thesis, Bangor University, 1996. https://research.bangor.ac.uk/portal/en/theses/biodiversity-and-biology-of-salt-marsh-and-mangal-brachyura-in-qatar(ff9d667e-8d07-469e-938f-f07db75d64fa).html.

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Although there have been comprehensive ecological surveys of impacted mangal and salt marshes in the Gulf states, especially Saudi Arabia, no data exists regarding the mangal or salt marshes fauna of Qatar, where recent replanting has expanded the area of mangal . The first aim of the present investigation was, to study the biodiversity of the Brachyura and fish living within these habitats quantitatively together with relevant features of the abiotic and biotic environments of natural, replanted mangal and salt marsh so that the progress of recolonisation of the new habitat could be evaluated. Measurements of sediment organic matter, grain size and moisture content indicate that natural mangrove areas have the finest grain size and highest organic and moisture contents while planted mangrove areas have a higher mean grain size, but lower organic and moisture content. Mean soil water pH within the natural mangrove areas was 7.21, in planted mangrove areas slightly higher with a value of 7.55, and 7.53 at the salt marsh, while sea water pH was 7.91 - 8.30. Differences in brachyuran species in planted and natural mangrove areas were found, but biodiversity was similar in salt marsh and natural mangrove areas. Nasima dotilliformis was the only species not to occur at any planted mangrove site, while Serenella leachii was missing from natural mangrove. Four crabs Nasima dotilliformis, Metopograpsus messor, Eurycarcinus orientalis, and Macrophthalmus depressus dominated natural and planted mangroves and salt-marsh, extending through the upper intertidal. Ilyoplax frater, Manningis arabicum, Macrophthalmus depressus occur in the mid intertidal zone. On the lower intertidal zone the two dominant species in all areas were M. depressus and Metaplax indica. In planted mangrove areas where sandy sediment dominates Scopimera crabricauda occurs between the upper intertidal to mid intertidal zone. Fish surveys indicate that Ablennes hians, Gerres oyena, Hemiramphus marginatus and Liza macrolepis, enter mangroves using these as nursery areas and significant differences occurred between sites demonstrating that mangrove areas, especially pneumatophores, form a special habitat for these small fish. The first zoeal larval stage for 6 common intertidal crabs is described, and new generic diagnoses are erected for Paracleistostoma arabicum and Cleistostoma kuwaitense, crabs belonging to the Camptandriinae. A modified key based on Manning and Holthuis (1981) is constructed to separate these from other members of the subfamily. The biological characteristics of 5 species of crab were monitored during a monthly sampling programme over the period June 1993-1994 including carapace widthweight relationship, size frequency, sex-ratio and breeding biology. Male: female ratios differed, indicating spatial and temporal variations by size-classes and season. The ovigerous females of N. dotilliformis and S. leachii were encountered over 7 months while those of M. depressus were seen almost throughout the year. Metopograpsus messor were ovigerous over a5 month period and E. orientalis over 6 months. From size frequency modes and data on recruitment and ovigerous females it appear that late spring and summer is the ecologically-active season. The mouthparts of 6 species of the family, Ocypodidae, 2 species of the family Grapsidae and 1 species of Xanthidae are described. These crabs were observed and collected from mangrove sites mud and saltflats between the midlittoral intertidal zone and supralittoral fringe. Detail of the mouthpart structure reveal differences between deposit feeders with spoon-tipped setae in sandy habitat dwellers and plumose setae in mud feeders, while spinose setae occur in omnivorous and carnivorous species. Scanning Electronic Microscope studies of the structure of proventriculus of these crab species again revealed different structures related to the type of feeding and particular type of sediment in which deposit feeding crabs live. In conclusion this study has demonstrated that mangrove in Qatar whether natural or planted acts to conserve species and enhance diversity and abundance. As yet recently planted mangroves (10 y) have not reached the full brachyuran diversity seen in natural mangroves, and present work demonstrates that this is only likely to occur when full physical habitat comparability with natural mangroves is attained.

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31

Carroll, Robert A. "Nekton Utilization of Intertidal Fringing Salt Marsh and Revetment Hardened Shorelines". W&M ScholarWorks, 2002. https://scholarworks.wm.edu/etd/1539617792.

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32

Lavado, Ana Rita Bajanca. "Zonas húmidas: contribuição do arquitecto paisagista para um turismo ecológico. Requalificação de áreas de sapal e de salinas". Master's thesis, ISA/UL, 2015. http://hdl.handle.net/10400.5/11198.

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Mestrado em Arquitectura Paisagista - Instituto Superior de Agronomia
This work focuses on the study of wetlands estuary, concentrating on two particular ecosystems: one natural, the estuarine salt marsh and other artificial, the salt pans. The main goal is to provide support to the intervention aimed at the conservation of these areas. Salt pans are secular artificial ecosystems, responsible for significant changes in the landscape, currently are threatened to disappear, resulting in an irreversible loss of biological richness, ecological, historic-cultural and landscaping. They play a key role for waterbirds, especially for waders. The case study of this work is a proposal for the redevelopment of the salt pans Cavalos and Olhos that are disabled in the Herdade da Mourisca (Setúbal, Sado Estuary, Portugal). This recovery is aimed at creating a "living museum" which allows the observation of the salt activity, whose role was central to the development of this region. The undeniable importance of the Mourisca’s area in ornithological terms implies that recovery be designed so as to combine the salt pan activity with the conservation of this site as refuge for these birds. The proposal will be directed to raising awareness and environmental education and eco-tourism activities, being a vehicle to promote the natural and cultural values of the Sado Estuary

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33

Hays, Rebecca Lynn. "Vegetation patterns and nutrient cycling in Delaware Bay salt marshes Great Marsh (Lewes) and Webbs Marsh (South Bowers), Delaware /". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 420 p, 2010. http://proquest.umi.com/pqdweb?did=1992440941&sid=10&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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34

Wilson, Kristin R. "Ecogeomorphology of Salt Pools of the Webhannet Estuary, Wells, Maine, U.S.A". Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/WilsonKR2006.pdf.

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35

Apple, Jude Kolb. "The regulation of bacterioplankton carbon metabolism in a temperate salt-marsh system". College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2857.

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Thesis (PhD) -- University of Maryland, College Park, 2005.
Thesis research directed by: Marine-Estuarine-Environmental Sciences. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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36

Connor, Richard 1969. "An examination of carbon flow in a Bay of Fundy salt marsh". Thesis, McGill University, 1995. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23879.

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This study examines carbon flow in the Dipper Harbour salt marsh, a macrotidal system located on the north-west coast of the Bay of Fundy, New Brunswick. The vegetated marsh surface is composed of three major zones; the Spartina alterniflora-dominated low marsh, the Plantago maritima-dominated Middle marsh, and the Spartina patens-dominated high marsh. The total net primary production (NPP) of these dominant macrophytes is 860, 300 and 650 g C m$ sp{-2}$ yr$ sp{-1}$ respectively. In all plant zones, 66% of the NPP occurs in the belowground fraction.
Empirical measurements of organic matter burial indicate that the marsh sediment acts as a carbon sink, accumulating between 75 and 105 g C m$ sp{-2}$ yr$ sp{-1}$. The tidal export of aboveground plant biomass in the form of particulate organic matter accounts for a net loss of carbon ranging from 65 to 170 g C m$ sp{-2}$ yr$ sp{-1}$. An experiment examining the exchange of dissolved organic carbon (DOC) suggest a net annual export of roughly 500 g C m$ sp{-2}$ yr$ sp{-1}$. The forementioned fluxes are combined with estimates of surface gas exchange and algal productivity in order to construct a carbon budget. The budget predicts a DOC export term of 365 g C m$ sp{-2}$ yr$ sp{-1}$, which is of the same order of magnitude as that obtained from the empirical DOC data.
The results of this study show that the Plantago zone plays a significant role in the circulation of carbon in the Dipper Harbour salt marsh. This suggests that the patterns of carbon circulation in northern marshes may differ considerably from those in marshes further south where no distinct Plantago zone has been reported.

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37

Mohamed, Musbah F. "Ecological studies on Atriplex portulacoides and its role in salt marsh zonation". Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267473.

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This study investigated the zonation of the halophytic shrub Atriplex portulacoides (chenopodiaceae) on three main habitats on the high marsh, shingle ridge and low marsh at Stiffkey saltmarsh, on the north Norfolk coast. The aim was to examine the physical and biological factors controlling the distribution of this species within an apparently wide amplitude of elevation within the tidal frame. The field investigation revealed significant differences in some of the physical characteristics of the sediment of five sites. Soil drainage and soil texture were significantly different between the shingle ridge and the general marsh habitat. Other environmental factors, including duration of tidal submergence proved to have significant effects on the distribution and percentage cover of the plant. Sediment accretion rates were greatly variable between the high and low marsh and may be responsible for low seed germination rates of this species on the low marsh. Laboratory experiments showed that the seed germination was largely inhibited at high salinities. Seed germination can occur under anoxic conditions but only in the presence of light. Seed germination in the laboratory was significantly higher under alternating temperature (20/10 °C) than at continuous lower temperatures (1 or 4 °C). Seed germination under burial with sediment was significantly reduced and this is due to the failure of seeds to germinate in the first place and also due to the difficulty in emergence from burial. Glasshouse experiments showed that long-term waterlogging created hypoxic conditions that were harmful to growth of A. portulacoides at all three stages of the life history tested; mainly changes to morphology occurred. However, the seedlings are the more adversely affected than young established plants or the mature plants. Unlike the seedlings, the young established and mature plants were relatively tolerant to waterlogging, mainly because they produced abundant adventitious roots from their aerial branches. Seed and seedling transplant experiments in the field showed that plants can not establish lower on the marsh than their current lower limit because of physicochemical conditions. The obstacle is mainly at the seed germination, establishment phase as transplanted seedlings had much higher survival rates generally than transplanted seeds. However, the low marsh was generally more conducive to seedlings than the high marsh. Certain biotic interactions were also investigated. Competition of A. portulacoides with Puccinellia maritima tested in a prolonged experiment in the glasshouse with and without waterlogging showed no significant effect on the dry mass of either species. Fruits (seeds) of A. portulacoides were significantly predated by larvae of the moth Coleophora atriplicis.

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38

Yallop, Adrian Roy. "Biotic interactions in salt marsh zonation with particular reference to abuscular mycorrhizas". Thesis, University of East Anglia, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251656.

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Salt marshes occupy a narrow intertidal zone where conditions change from marine to terrestrial. As a consequence they exhibit severe clines in salinity and soil saturation. The characteristic zonation of the vascular plant communities occupying these habitats is believed to develop as a result of differential tolerance and competitive abilities of the plants that comprise them. There are however few data on the structure of salt marsh communities relative to either elevation or tidal inundation. The consequences of soil saturation and salinity may also affect the distributions of soil microflora, including the occurrence and development of arbuscular mycorrhizal fungi. As AM development can result in enhanced plant performance, and may alter competitive interactions, any edaphic limitation in their development could influence plant community development. Detailed surveying, and the use of two objective methods of defining zonation, has allowed a full description of the plant community structure, relative to elevation, to be made. This identifies three distinct species groupings within the zonation, and has enabled the identification of competitive dominants within the zonational sequence. The occurrence of AM development within the salt marsh community has also been accurately determined for the first time. This represents the first survey of AM fungi in UK salt marshes since 1928, and identifies a distinct cline in the occurrence of these fungi relative to inundation. The effects of mycorrhizal development by AMF isolated from salt marsh sediments on the growth of 5 halophytes is ascertained. The results suggest salt marshes are environments where the usual benefits of AM development do not apply. This may explain the low levels of mycotrophy observed amongst halophytes.

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Proudfoot, Andrew Macdonald. "Relationships between Coleophora atriplicis and its host plants on a salt marsh". Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332362.

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40

Alghamdi, Ahmed. "Phenotypic plasticity and population differentiation in Suaeda maritima on a salt marsh". Thesis, University of East Anglia, 2012. https://ueaeprints.uea.ac.uk/42351/.

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Suaeda maritima (L) Dumort is a polymorphic annual species of the family Chenopodiaceae that in the UK occurs exclusively in coastal salt marshes. The main aim of this study has been to examine the phenotypic variations within and between its populations in the heterogeneous microenvironments of a salt marsh. Detailed field characterizations of the growth, seed production and seed heteromorphism of four Suaeda maritima populations at Stiffkey salt marsh were conducted over three consecutive years, revealing considerable consistent phenotypic variation between populations on the high marsh, high-marsh creek bank, upper low marsh, and low marsh. Field environmental heterogeneity was assessed by taking measurements of sediment salinity, water content, organic content, redox potential, elevation in the tidal frame and annual number of tidal inundations. They demonstrated that different Suaeda maritima populations do indeed experience divergences between their environments that could both affect the phenotypic responses of developing plants and constitute selection pressures for the evolution of genetically differentiated populations. Experiments involving seedling reciprocal transplantation in the field and seedling transplantation to uniform laboratory conditions revealed significant differences among populations in terms of survival, growth and fecundity parameters. Detailed experiments examining the effect of salinity, temperature, light and storage conditions on seed germination and dormancy also revealed seed dimorphism and significant variation in the germination behaviour among populations. Suaeda maritima populations exhibited substantial evidence of genetic differentiation (reflecting the complex heterogeneity in their natural microhabitats) and, therefore, it can be suggested that this differentiation reflects adaptive ability to colonize wider range of habitats along the environmental gradients. Key words: Suaeda maritima, Salt marsh, Microhabitat, Population differentiation, Phenotypic plasticity, Fecundity, Seed heteromorphism, Dormancy, Germination, Survival, Reciprocal transplantation, Spatial heterogeneity

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41

Tsuzaki, Toru. "Spartina anglica population and environmental studies within the Solent salt marsh system". Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/196463/.

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The thesis examines the possible causes of decline of Spartina anglica marshes along the south coast of Britain with emphasis on the Solent marshes. The study shows that although there may be some genotypic differences between S. anglica gathered from sites in Britain. The disparities are not large enough to explain the significant differences in morphological vigour of S. anglica observed in the field. It concludes that the discrepancies observed in the field are the result of phenotypic differences resulting from environmental factors. The work shows that in the S. anglica marshes of the south coast, anaerobic soil conditions prevail with impeded drainage being the most likely cause of the dwarf growth forms and lack of re-colonisation of pans and mudflats observed in the field. The thesis concludes that the ultimate demise of the S. anglica marshes of the south coast of England is the result of frontal and creek erosion of the mature marsh and the failure of S. anglica to establish itself on the newly exposed sediments of the foreshore. When S. anglica establishes itself in a flood /ebb neutral zone of an estuary, it changes the bathymetry to that of ebb dominant morphology. As a result eroded sediment is swept away with the outgoing tide. Furthermore, S. anglica is then unable to recolonise the exposed foreshore sediments because of its low redox potential resulting from poor permeability which is the consequence of the of historic overburden pressure of a once colonising marsh.

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Czapla, Kenneth Michael. "Impacts Of Fertilization On Salt Marsh Resilience: Altered By Location-Specific Drivers". W&M ScholarWorks, 2020. https://scholarworks.wm.edu/etd/1593091565.

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Salt marshes provide valuable ecosystem services to human society, but are currently under threat from accelerating sea level rise and nutrient enrichment. Carbon (C) and mineral accumulation allow salt marshes to maintain elevation above sea level and survive. Anthropogenic nitrogen (N) loading is increasing in many salt marshes, causing negative impacts on marsh resilience such as increased decomposition and decreased below-ground production. However, increasing N may also have simultaneous positive effects such as increased primary production and above-ground biomass, surface sediment accretion, and denitrification rates, which remove excess N from coastal waters. Many studies have been conducted to determine the effect of fertilization on salt marsh resilience; however, inconsistent conclusions across studies may result from varying physical and chemical characteristics across salt marsh locations that impact responses to fertilization. In this dissertation we performed experiments to determine how C cycling, C accumulation, N cycling, and microbial communities vary in both natural and fertilized salt marsh locations at Marine Corps Base Camp Lejeune, North Carolina, USA. Here we show that edge marsh with a high elevation berm had lower pore water sulfide, ammonium, dissolved organic C (DOC), and dissolved organic C (DIC) concentrations than interior marsh, which displayed longer pore water residence time and flooding duration with high pore water sulfide, ammonium, DOC, and DIC concentrations. Respiration and primary production were higher in the edge marsh compared to the interior marsh but net ecosystem CO2 exchange (NEE) was nearly balanced at all sites. Fertilization had a much greater impact on edge than interior NEE, shifting edge NEE toward net CO2 emission. Net ecosystem carbon balance (NECB), based on the mass balance of NEE, lateral C export, and sediment C deposition for edge and interior sites was calculated to examine the effect of fertilization on net C accumulation. NECB displayed a net C gain in the interior marsh but a large net C loss on the edge; fertilization stimulated more C loss on the edge than in the interior. When extrapolating NECB to the entire marsh, C loss on the edge greatly impacted the whole marsh C budget, causing the marsh to have a net loss of 53 kg C yr-1 under natural conditions and a five-fold increase in C loss with fertilization. N removal through denitrification was greater on the edge and increased with fertilization, but was not affected by fertilization at the site with highest sulfide concentrations. DNRA, which retains N in the marsh, dominated over denitrification only during summer, and varied widely across locations. Fertilization generally decreased DNRA rates. Microbial community composition was distinct on the edge vs. interior, with differences driven by the differences in pore water sulfide, ammonium, DOC, and DIC. The edge was a hotspot for nitrifying microbial communities. The processes of respiration and denitrification were positively correlated to the relative abundance of sulfate reducers and ammonia oxidizers, respectively. Thus, we conclude that fertilization had an overall negative effect on marsh resilience with especially large impacts on edge marsh.

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Roner, Marcella. "READING THE SIGNATURES OF CHANGING ENVIRONMENTAL FORCINGS IN SALT-MARSH BIOGEOMORPHIC SYSTEMS". Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3424455.

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The question on whether actual tidal morphologies are in equilibrium with current environmental conditions or retain signatures of past climatic changes or human interventions is a classical and fascinating one, furthermore being of intellectual as well as practical interest. Understanding the dynamic response of tidal landscapes to past conditions is critical to predict their response to future environmental changes, such as rate of relative sea-level rise and sediment supply. This is an open and fundamentally important point, particularly in times of natural and anthropogenic changes, during which tidal environments are most exposed to possibly irreversible transformations with far-reaching socio-economic and ecological implications worldwide. The proposed work aims at analyzing the signatures of changing environmental forcings imprinted in the landscape and in the sedimentary record of the Venice Lagoon to refine our knowledge of tidal landforms dynamics. The thesis is developed following a biogeomorphic approach to the study of salt-marsh landscapes. Marsh biomorphological evolution, in response to changes in the environmental forcings, is analyzed investigating the relative role and mutual interactions and adjustments between physical and biological processes shaping the salt-marsh landscape. This thesis was carried out through a series of extensive temporal and spatial high-resolution morphological, sedimentological, geochronological and elemental analyses, aimed at exploring the main features of sub-surface marsh samples and lagoonal sediment cores. The study of sub-surface marsh samples highlights the mutual role of inorganic and organic accretion on salt marshes, which is mainly driven by the inorganic component near the channels, while the organic component largely contributes in the inner-marsh portion. The analyses carried out on sediment cores refine the knowledge of the latest Holocene sedimentary succession of the Venice Lagoon, and furnish a chronostratigraphical model for the evolution over the last two millennia. In particular, for a salt-marsh succession, the analyses highlight the occurrence of a delayed marsh-dynamic response to changing sediment delivery rates.
La questione inerente l’equilibrio delle morfologie tidali con le attuali condizioni ambientali, o se esse conservino tutt’ora i segni dei cambiamenti climatici o degli interventi antropici passati, è un argomento classico ed affascinante nel campo delle Geoscienze, oltre ad essere di interesse sia intellettuale che pratico. Comprendere i meccanismi che governano la risposta di un ambiente a marea a variazioni passate delle forzanti ambientali è fondamentale per prevedere la loro risposta a cambiamenti ambientali futuri, quali il tasso di innalzamento del livello del mare relativo e l’apporto di sedimenti. Si tratta di un tema tutt’oggi sospeso e di fondamentale importanza, soprattutto in tempi di cambiamenti sia naturali che umanamente indotti, durante i quali gli ambienti tidali sono maggiormente esposti a trasformazioni potenzialmente irreversibili, con implicazioni di vasta portata socio-economica ed ecologica in tutto il mondo. Il presente lavoro si propone di analizzare le firme del cambiamento delle forzanti ambientali impresse nella morfologia e nel record sedimentario della Laguna di Venezia, con lo scopo di affinare la conoscenza delle dinamiche tidali. La tesi volge allo studio di sistemi di barena attraverso un approccio biogeomorfologico. L’evoluzione geomorfologica delle barene, in risposta ai cambiamenti delle forzanti ambientali, è analizzata investigando il ruolo relativo, le interazioni reciproche e le regolazioni esistenti tra i processi fisici e biologici che modellano gli ambienti di barena. Il lavoro è realizzato attraverso una serie di analisi morfologiche, sedimentologiche, geocronologiche ed elementali, eseguite ad alta risoluzione spazio-temporale, volte ad esplorare le principali caratteristiche sia di campioni sub-superficiali di barena, sia di carote di sedimenti lagunari. Lo studio dei campioni sub-superficiali evidenzia il ruolo reciproco delle componenti organica ed inorganica nell’accrezione delle barene, la quale è principalmente guidata dalla componente inorganica in prossimità dei canali, mentre la componente organica contribuisce in gran parte nelle porzioni più interne delle barene. L’analisi effettuata sulle carote lagunari implementa la conoscenza della successione sedimentaria tardo-Olocenica della Laguna di Venezia, e fornisce un modello di evoluzione cronostratigrafica degli ultimi due millenni. In particolare, le analisi effettuate su una successione sedimentaria di barena, evidenziano la presenza di una risposta dinamica ritardata dell’ambiente a cambiamenti nei tassi di apporto sedimentario.

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44

Elsey-Quirk, Tracy. "Inter- and intraspecific variation in carbon and nutrient pools of salt marsh plants". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 236 p, 2010. http://proquest.umi.com/pqdweb?did=1993336371&sid=9&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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45

Li, Bo. "Tidal channel meandering and salt marsh development in a marine transgressed incised valley system the Great Marsh at Lewes, Delaware /". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 710 p, 2006. http://proquest.umi.com/pqdweb?did=1208133431&sid=9&Fmt=2&clientId=8331&RQT=309&VName=PQD.

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46

Smith, Neil. "The ecology of nekton assemblages within pools and creeks of salt marsh and claimed marsh, Ribble estuary, north-west England". Thesis, Lancaster University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397044.

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47

Tempest, James Alexander. "Hydrodynamic effects of salt marsh canopies and their prediction using remote sensing techniques". Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/267914.

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The aim of this thesis was to improve our understanding of plant – flow interactions and to develop new remote sensing techniques that would allow a marsh scale assessment of flow modification due to the presence of salt marsh vegetation. The limitations of current approaches which improve our understanding and prediction of tidal flows centre around poor assessments of canopy structure and mechanical properties. The validity of such simplified and reductionist assessments of canopy structure were tested and found to contribute considerable error in estimations of canopy frontal area and canopy drag. New metrics to assess canopy structure were tested as part of a flume study using two salt marsh species with varying form and architecture. Results from this experiment found that biomass located immediately below the water surface are important for determining fluid momentum losses in salt marsh canopies. These results led to the development of a new empirical based model using vertical measures of biomass and approach (incident) velocity which can accurately (R2 0.71) predict flow momentum losses. This suggests that the characteristic vegetation parameter and the drag coefficient may be substituted with vertical canopy biomass and an empirical coefficient. This may lead to more accurate assessments of canopy structure and thus comparable results across the literature as well as potentially apriori assignment of parameters in the force drag model. Vertical canopy biomass (3D biomass) was then estimated at the marsh scale using a combined remote sensing approach and an empirical model. Accurate assessments of the marsh surface are critical for hydrodynamic models and important if we are to determine vertical changes in canopy structure. The approach first identified marsh surface returns by operating a moving average smoothing filter on Airborne Laser Scanning (ALS) data. The automated procedure detected vegetated and non–vegetated surfaces using aerial NDVI which calibrated the filter and ensured ALS returns were representative of marsh surface elevation. Using the marsh surface DEM, vegetation was reconstructed at 0.2 m grid cells. Terrestrial Laser Scanning (TLS) was found to accurately quantify maximum canopy height (RMSE 0.14m) whilst a regression model using aerial NDVI and spatial coordinates gave reasonable predictions (RMSE 0.08kg/m2) of total plot canopy biomass within each 0.2 m cell across a ~20,000 m2 area of marsh. Ground measurements found the vertical distribution of canopy biomass followed a power law increase with elevation from the marsh bed. Combining all the approaches allowed the creation of a 3D assessment of canopy biomass with an average error of 30% of the mean amongst plots exhibiting larger canopy biomass ( > 0.4 kg/m2). This vertical measure of biomass can be combined with the flow momentum loss model generated in the flume experiment to assess hydrodynamic canopy drag potential at the marsh scale. Roughness coefficients can also be calculated using this approach which can be easily fed into commercially available numerical flow models.

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48

Shaw, Gregory Alan. "Rehabilitation of the Orange River Mouth Salt Marsh : seed, wind and sediment characteristics". Thesis, Nelson Mandela Metropolitan University, 2007. http://hdl.handle.net/10948/603.

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Abstract (sommario):

The Orange River is an important source of freshwater and like many other wetlands in semi-arid regions, supports various social (Spurgeon, 1998), economic (Spurgeon, 1998; Bornman et al., 2005) and ecological functions. The saltmarsh at the Orange River Mouth has become degraded over time following numerous anthropogenic impacts. As a result the Transboundary RAMSAR site was placed on the Montreux record emphasising the importance for rehabilitation. The potential of the marsh for natural rehabilitation was assessed through three physical factors which were considered to have the most influence on the saltmarsh i.e. 1) sediment 2) water 3) wind. Three sampling areas were chosen to investigate the sediment characteristics of the ORM saltmarsh and the suitability for seed germination and adult survival. Site A was representative of the general marsh area, Site B was thought to have favourable sediment conditions for saltmarsh growth because of the large numbers of seedlings and Site C was prone to inundation by wind blown sediment. The sites were sampled in 2005 (dry conditions) and in 2006 after high rainfall and river flooding. Electrical conductivity (EC) of the sediment throughout the marsh was hypersaline in many instances above the tolerance range for S. pillansii (> 80 mS.cm-1) The freshwater event in 2006 lowered salinity significantly in two of the three sites. Differences in sediment characteristics were also compared for three habitats i.e. driftlines, open sites and under vegetation. Driftlines (C. coronopifolia = 872 seedlings m-2; S. pillansii = 1296 seedlings m-2) and the microhabitat associated with adult plants (C. coronopifolia = 803 seedlings m-2; S. pillansii = 721 seedlings m-2) created favourable conditions for seedling growth, however open unvegetated (C. coronopifolia = 56 seedlings m-2; S. pillansii = 49 seedlings m-2) areas had significantly lower seedling density. Due to the marsh currently being in a desertified state this study aimed to establish whether the remaining vegetation could produce enough seed to revegetate the marsh. Laboratory studies indicated that seeds of both species germinated best in freshwater (0 psu). The germination of S. pillansii seeds was 40 percent at 0 psu compared to 5 percent at 35 psu. After storage under hypersaline conditions (35 psu) C. coronopifolia showed 100 percent seed germination when returned to freshwater whereas storage at 70 psu decreased the viability of S. pillansii seeds. The plants are producing adequate seed that will allow for regrowth and rehabilitation if sediment and groundwater characteristics are suitable for seed germination, seedling growth and adult survival. However the increase in bare areas at the Orange River mouth as a result of salt marsh dieback has increased the available sediment source. The wind blown sediment has covered large areas of the remaining adult salt marsh vegetation, particularly in the northern corner at Site C, causing further die-back.

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49

Asef, Tania S. "Associating genetically diverse tamarisk invaders with their impacts in a salt marsh ecosystem". Thesis, California State University, Long Beach, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1522618.

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Abstract (sommario):

Invasive tamarisk has many impacts in freshwater systems including increasing soil salinity, decreasing water content, and causing a shift in food web structure. Tamarisk species originally introduced to the US have hybridized and have been documented invading salt marsh systems in San Diego County, California. The main goals of this study were to determine the impacts of tamarisk within a salt marsh and among genetic types of tamarisk. Amplified Fragment Length Polymorphism was used to determine genetic identity of each individual salt-marsh invading tamarisk. Abiotic impacts depended on microhabitat, as did tamarisk tree morphology, and infauna community composition. Tamarisk altered abiotic factors in the upland and upstream microhabitats and altered infauna community composition in the marsh microhabitat. 17.8% of trees were hybrids of T. ramosissima x T. chinensis. The remainder were pure T. chinensis. Tamarisk genetic identity did not influence abiotic factors, although invertebrate diversity was lower beneath pure T. chinensis than the hybrid. The tamarisk invasion was not an in-situ hybridization and had the most pervasive impact on the infauna in the marsh microhabitat.

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50

Mayer, Mary Anne. "Ecology of juvenile white shrimp, Penaeus setiferus Linnaeus, in the salt marsh habitat". Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/25348.

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