This research investigated the response of the dominant salt marsh macrophyte Spartina alterniflora var. Loisel to sedimentation from Hurricanes Gustav and Ike. A range of sedimentation was used to track the above and belowground plant response, as well as the volume of mineral and organic matter, in the upper reaches of the marsh soil from September 2008 to April 2009. Where storm sedimentation was greatest (~3.5 cm), there were significant increases in live aboveground biomass. Although live belowground biomass did not change significantly over time, the volumetric contribution of both mineral and soil organic matter in the shallow marsh soil increased. These results indicate that hurricane sedimentation may benefit subsiding coastal marshes by stimulating aboveground vegetation mass as well as soil organic matter volume. However, these results imply that there may be a sediment thickness threshold that must be met before such positive effects are expressed.

Simulated oil spills were created in S. alterniflora sediment-water microcosms to determine the effects of applied crude oil on S.alterniflora during two 90-day studies. In the first experiment, oil dosage was varied at 0-250 mg crude oil/g wet soil to determine the lethal dosage level. In the second experiment, oil type, dosage, and soil type were varied to determine the effects of oil under multiple scales of resolution. A light, medium, and heavy crude oil at dosages ranging from 0-150 mg crude oil/g wet soil were used in addition to an oiled and non-oiled soil. Following the completion of the 90-day experiment, several key findings were observed: (1) The lethal dosage limit was reached at 250 mg crude oil/g wet soil during the first experiment but not the second, by design; (2) At initial dosages of 10 and 50 mg crude oil/g wet soil, the oiled soil (acclimated for 4 months) was more influential in decreasing cumulative biomass growth rates compared to oil applied at the oil-water interface; (3) At the heaviest dosages applied as a simulated oil slick, concentrations of 150 mg crude oil/g wet soil, evapotranspiration rates were negatively affected by the oil (significant at p=0.05 in a one-tailed t-test); (4) Light, heavy, and then medium crude oil showed the lowest biomass growths, in that order, indicating that light crude oil was the most toxic in these microcosm experiments with S. alterniflora; (5) The 10 mg oil/g wet soil out-performed the 0 mg oil/g wet soil in transpiration and biomass growth.

Light, medium and heavy crude oils were studied at three concentrations and with two different sediments in experimental microcosm settings to determine the ability of Spartina alterniflora and associated microbes to breakdown total extractable hydrocarbons (TEH) in the water. It was a baseline experiment designed to quantify the rates of biodegradation under relatively quiescent conditions from different crude oils at moderate doses ranging from 0-150 mg/kg soil. Upon the completion of the experiment there were several key findings: (1) The lethal dosage for Spartina alterniflora was not reached within the 90 day experiment at these dosages, and all plants survived; (2) More than 97% of the total extractable hydrocarbons (TEH) were shown to be degraded by plants and rhizosphere microorganisms within the 90- day experiment; (3) The dose of oil introduced as a slick (simulated spill) on day zero did not significantly affect the results for TEH degradation within the range of dosages from 50-150 mg/g -- these dosages could be degraded by the marsh cord grass system; (4) A sediment type which was acclimated to oil for several months and one which was non-acclimated did not show significantly different results for TEH degradation in the microcosms -- both sediment systems resulted in TEH degradation over the 90-day experiment; and (5) A mathematical model was developed which simulated experiment results quite closely including TEH diffusion from the crude oil slick into the water and subsequent biodegradation.

La spéciation est un mécanisme central de la diversification biologique. Ce travail vise à analyser l'évolution transcriptomique accompagnant la spéciation chez les spartines (Poaceae) qui jouent un rôle important dans la dynamique sédimentaire des marais salés. Ce genre est caractérisé par différents types de spéciation divergente et réticulée au niveau polyploïde. L'évolution du transcriptome par différentes analyses de polymorphisme et par microarrays a été analysée chez deux espèces soeurs hexaploïdes S. maritima (en régression en Europe) et S. alterniflora (envahissante). Malgré une faible divergence nucléotidique, ces deux espèces montrent des différences d'expression importantes. Les conséquences de l'hybridation et de la duplication du génome ont été examinées chez deux hybrides F1 (S. x neyrautii et S. x townsendii) formés récemment et indépendamment à partir des mêmes parents, et chez l'allopolyploïde envahissant S. anglica. Nos résultats ont montré les effets importants, mais différents de l'hybridation et de la duplication du génome sur le transcriptome. Cet effet se manifeste par une dominance d'expression maternelle (chez les hybrides F1) qui s'atténue chez l'allopolyploïde. Ce dernier se distingue par une surexpression de la majorité des gènes. Les régions flanquant les éléments transposables Ins2, Wis-like, Cassandra apparaissent également affectées par cette dynamique. Les deux événements d'hybridation ont engendré des réponses différentes, en accord avec la morphologie très différente des hybrides. Les catégories de gènes différentiellement exprimées entre les espèces sont discutées dans le contexte des différences phénotypiques et écologiques de ces espèces.

Les Spartines jouent un rôle écologique majeur sur les marais salés. Elles représentent un excellent modèle pour appréhender les conséquences écologiques de la spéciation par hybridation et polyploïdie dans le contexte d'invasion biologique. On s'intéresse plus particulièrement, à l'hybridation récente entre une espèce hexaploïde d'origine américaine Spartina alterniflora et une espèce hexaploïde européenne S. maritima ayant donnés deux hybrides F1 (S. x townsendii et S. x neyrautii) et la nouvelle espèce envahissante allododécaploïde (S. anglica). Les nouvelles technologies de séquençage haut-débit facilitent l'exploration de ces génomes peu connus. L'assemblage et l'annotation d'un transcriptome de référence ont permis d'annoter 16 753 gènes chez les spartines hexaploïdes et d'identifier des gènes d'intérêts écologique et évolutif. Une sélection de ces gènes a ensuite été analysée à travers une étude d'expression par PCR quantitative sur les populations naturelles des 5 espèces du complexe. Les résultats ont permis de mettre en évidence une expression homogène intra-populations mais une grande variabilité entre les espèces. L'analyse du génome des Spartines a ciblé prioritairement le développement de ressources génomiques concernant l'espèce S. maritima pour l'analyse des compartiments codant et répété à l'aide de séquençage d'une banque BAC et d'un run de pyroséquençage d'ADN génomique. Les analyses ont permis d'évaluer une proportion d'éléments répétés représentant près de 30% du génome. Les données générées ont alors été comparées avec les génomes séquencés phylogénétiquement proches et ont permis de premières comparaisons entre les spartines et les autres Poaceae.

Part of a cutover bog in Pokesudie Island, New Brunswick, Canada was contaminated with seawater and was still largely devoid of vegetation 5 years after the event and was consequently chosen for study. The study area consisted of rectangular fields with cambered surface that sloped down (2%) to the drainage ditches on both sides. Across this slope zones were created: Up-, Mid- and Low- areas on either side of the centerline of fields. Two field experiments were conducted to determine abiotic stresses to plant re-establishment in terms of hydrology and peat characteristics along this cambered surface. The general objective was to identify microsites or zones that could be suitable to the introduction of wetland halophytes <em>Juncus balticus</em> Willd. and <em>Spartina pectinata</em> Link obtained from nearby salt marshes. <br /><br /> In the first experiment, cylindrical <em>J. balticus</em> sods were transplanted into the Up- and Low- areas, at 1, 3, 5, 10 and 20 d of incubation (in May 2005) with measurements made on the Outer and Inner annular sod sections, replicated over 4 blocks. Moisture (% dry weight basis (dwb)) reached maximum values 1 day after transplantation, 84±0. 05 for Outer and 103±0. 07 for Inner sod section. Salinity (dS m^-1) in sods due to ingress of sodium (Na⁺ ) and chloride (Cl^-) reached values of the surrounding peat 3 days after transplantation, 3. 52±1. 06 for Inner sod section and 4. 11±0. 99 for Outer sod section in Up-areas, and 1. 76±0. 24 for Inner sod section and 2. 57±0. 28 for Outer sod section in Low-areas. Maximum decrease in pH was at 5 days after transplantation, in Outer sod section in the Up-areas (from 5. 89 to 4. 88±0. 14) which was much higher than the pH range of 3-4 of the surrounding peat. This was due to the buffering capacity of calcium (Ca²⁺) and magnesium (Mg²⁺) in sods which did not change in concentration after 20 days of incubation. Therefore, Inner sod sections were less affected by the surrounding peat compared to the Outer sod sections, suggesting that a larger sod volume may alleviate stressful conditions for a longer time at transplantation and consequently allow greater time for adaptation. <br /><br /> In the second experiment, <em>J. balticus</em> and <em>S. pectinata</em> were transplanted on the 3 Locations Up-, Mid- and Low- areas, replicated over 10 blocks; and peat characteristics were measured at Depths 0-5, 5-10, 10-15 and 15-20 cm 5 times during the study period May-August 2005. Survival of <em>J. balticus</em> was poorest (27. 5±8. 3 %) in the Low-areas compared to 68. 5±8. 9 % in the Up- and 58. 5±8. 7% in the Mid- areas. <em>S. pectinata</em> survival was very good at all Locations (89±5. 3, 91. 6±3. 1 and 84. 2±4. 4 for Up-, Mid- and Low- areas, respectively) having better adaptation to early season waterlogged conditions. Waterlogged conditions resulted from a perched water table during the early part of the growing season (May-June) and were alleviated only upon the complete thaw of the frozen peat layer on 8 July. Thereafter, important changes in hydrology and peat characteristics occurred: water table depths decreased from -8. 5±1. 7 and -1. 6±1. 2 cm on 26 May, to -51. 5±2. 5 and -40. 7±2. 4 cm by 9 August in Up- and Low-areas, respectively; redox potentials at 12 cm depth increased from 26 June (190. 9±8, 175±10. 8 and 109. 2±29. 4 mV) to 9 August (282. 8±8, 302. 8±14. 3 and 312. 3±29. 6 mV) in the Up-, Mid- and Low-areas, respectively which showed that anaerobic conditions were maintained throughout the study period; decreased moisture content from 1256. 8±61. 9, 1667. 4±126. 3 and 1728. 6±153 on 30 May, to 851. 7±21. 2, 874. 6±47 and 1008. 2±57. 5 % dwb on 25 July) which caused increased dry bulk density (from 0. 07±0. 002, 0. 06±0. 003 and 0. 07±0. 01 to 0. 09±0. 003, 0. 09±0. 005 and 0. 08±0. 004) in the Up-, Mid- and Low-areas, respectively; and increased electrical conductivity (salinity) especially on the 0-5cm surface (from 1. 9±0. 13, 1. 8±0. 31 and 1. 5±0. 29 to 18±1. 9, 17. 5±1. 1 and 12. 2±1 dS m^-1) which also caused decreased pH (from 3. 5±0. 04, 3. 5±0. 08 and 3. 6±0. 01 to 2. 85±0. 04, 2. 85±0. 01 and 2. 9±0. 03) in the Up-, Mid- and Low-areas, respectively. Therefore, spring flooding followed by high surface salinity in summer precludes plant establishment by seeding and explains the current lack of spontaneous revegetation. Waterlogged conditions were of greater magnitude and duration at lower elevation areas unfavourable to <em>J. balticus</em> survival but salinity levels were high in the Up- and Mid-areas. <br /><br /> In the subsequent part of the second experiment, plants of <em>J. balticus</em> and <em>S. pectinata</em> grown in the study area and those collected from marshes were divided into above- and below- ground parts and accumulation of salt ions in plant tissues were determined to understand the species' salt-tolerance mechanism, as well as the accumulation of potentially toxic levels of iron (Fe) and manganese (Mn). Both plant species had similar accumulations (mmol kg^-1 dry wt,) of Na⁺ (474. 3±41 and 468. 3±31. 7, respectively) and Cl^- (314. 9±21. 9 and 310. 5±27. 5, respectively) in the above-ground parts but differed in how they managed Na⁺. <em>J. balticus</em> accumulated more Na⁺ in below-ground parts (659. 3±88. 7) and had limited transport to the above-ground parts, while <em>S. pectinata</em> accumulated and excreted Na⁺ in the above-ground parts and had less accumulation in the below-ground parts (397. 4±25. 1). <em>S. pectinata</em> maintained (313. 1±23. 8 in marsh <em>vs. </em> 292. 4±26. 2 in bog) and <em>J. balticus</em> increased (84. 2±1. 2 in marsh <em>vs. </em> 531. 2±38. 6 in bog) K⁺-selectivity in the shoots, a key requirement for survival in saline conditions. Compared with their respective marsh plants, <em>S. pectinata</em> had more salinity-tolerance than <em>J. balticus</em> primarily through its maintenance of Ca²⁺ (21. 5±1. 7 in marsh <em>vs. </em> 35. 6±3. 8 in bog) compared to a decrease in <em>J. balticus</em> (144. 7±12. 5 in marsh <em>vs. </em> 41±3. 7 in bog). Furthermore, Fe and Mn uptake in both species decreased but reached critical Fe-deficiency levels (1. 1±0. 1 mmol kg^-1 dry wt,) only in <em>S. pectinata</em> grown in drier areas. <br /><br /> It is concluded that local conditions of waterlogging (especially in lower elevation areas) and high salinity and low pH (notably in the upper elevation areas) were favourable to the survival of <em>S. pectinata</em> in all areas and <em>J. balticus</em> only in upper elevation areas. Sod transplanting may alleviate the acidity problem and depending on sod volume may delay the effects of harsh conditions of the cutover bog. However, long-term survival and growth of both species in drier areas may be constrained by deficiency in calcium in <em>J. balticus</em> and iron in <em>S. pectinata</em>.

Part of a cutover bog in Pokesudie Island, New Brunswick, Canada was contaminated with seawater and was still largely devoid of vegetation 5 years after the event and was consequently chosen for study. The study area consisted of rectangular fields with cambered surface that sloped down (2%) to the drainage ditches on both sides. Across this slope zones were created: Up-, Mid- and Low- areas on either side of the centerline of fields. Two field experiments were conducted to determine abiotic stresses to plant re-establishment in terms of hydrology and peat characteristics along this cambered surface. The general objective was to identify microsites or zones that could be suitable to the introduction of wetland halophytes <em>Juncus balticus</em> Willd. and <em>Spartina pectinata</em> Link obtained from nearby salt marshes. <br /><br /> In the first experiment, cylindrical <em>J. balticus</em> sods were transplanted into the Up- and Low- areas, at 1, 3, 5, 10 and 20 d of incubation (in May 2005) with measurements made on the Outer and Inner annular sod sections, replicated over 4 blocks. Moisture (% dry weight basis (dwb)) reached maximum values 1 day after transplantation, 84±0. 05 for Outer and 103±0. 07 for Inner sod section. Salinity (dS m^-1) in sods due to ingress of sodium (Na⁺ ) and chloride (Cl^-) reached values of the surrounding peat 3 days after transplantation, 3. 52±1. 06 for Inner sod section and 4. 11±0. 99 for Outer sod section in Up-areas, and 1. 76±0. 24 for Inner sod section and 2. 57±0. 28 for Outer sod section in Low-areas. Maximum decrease in pH was at 5 days after transplantation, in Outer sod section in the Up-areas (from 5. 89 to 4. 88±0. 14) which was much higher than the pH range of 3-4 of the surrounding peat. This was due to the buffering capacity of calcium (Ca²⁺) and magnesium (Mg²⁺) in sods which did not change in concentration after 20 days of incubation. Therefore, Inner sod sections were less affected by the surrounding peat compared to the Outer sod sections, suggesting that a larger sod volume may alleviate stressful conditions for a longer time at transplantation and consequently allow greater time for adaptation. <br /><br /> In the second experiment, <em>J. balticus</em> and <em>S. pectinata</em> were transplanted on the 3 Locations Up-, Mid- and Low- areas, replicated over 10 blocks; and peat characteristics were measured at Depths 0-5, 5-10, 10-15 and 15-20 cm 5 times during the study period May-August 2005. Survival of <em>J. balticus</em> was poorest (27. 5±8. 3 %) in the Low-areas compared to 68. 5±8. 9 % in the Up- and 58. 5±8. 7% in the Mid- areas. <em>S. pectinata</em> survival was very good at all Locations (89±5. 3, 91. 6±3. 1 and 84. 2±4. 4 for Up-, Mid- and Low- areas, respectively) having better adaptation to early season waterlogged conditions. Waterlogged conditions resulted from a perched water table during the early part of the growing season (May-June) and were alleviated only upon the complete thaw of the frozen peat layer on 8 July. Thereafter, important changes in hydrology and peat characteristics occurred: water table depths decreased from -8. 5±1. 7 and -1. 6±1. 2 cm on 26 May, to -51. 5±2. 5 and -40. 7±2. 4 cm by 9 August in Up- and Low-areas, respectively; redox potentials at 12 cm depth increased from 26 June (190. 9±8, 175±10. 8 and 109. 2±29. 4 mV) to 9 August (282. 8±8, 302. 8±14. 3 and 312. 3±29. 6 mV) in the Up-, Mid- and Low-areas, respectively which showed that anaerobic conditions were maintained throughout the study period; decreased moisture content from 1256. 8±61. 9, 1667. 4±126. 3 and 1728. 6±153 on 30 May, to 851. 7±21. 2, 874. 6±47 and 1008. 2±57. 5 % dwb on 25 July) which caused increased dry bulk density (from 0. 07±0. 002, 0. 06±0. 003 and 0. 07±0. 01 to 0. 09±0. 003, 0. 09±0. 005 and 0. 08±0. 004) in the Up-, Mid- and Low-areas, respectively; and increased electrical conductivity (salinity) especially on the 0-5cm surface (from 1. 9±0. 13, 1. 8±0. 31 and 1. 5±0. 29 to 18±1. 9, 17. 5±1. 1 and 12. 2±1 dS m^-1) which also caused decreased pH (from 3. 5±0. 04, 3. 5±0. 08 and 3. 6±0. 01 to 2. 85±0. 04, 2. 85±0. 01 and 2. 9±0. 03) in the Up-, Mid- and Low-areas, respectively. Therefore, spring flooding followed by high surface salinity in summer precludes plant establishment by seeding and explains the current lack of spontaneous revegetation. Waterlogged conditions were of greater magnitude and duration at lower elevation areas unfavourable to <em>J. balticus</em> survival but salinity levels were high in the Up- and Mid-areas. <br /><br /> In the subsequent part of the second experiment, plants of <em>J. balticus</em> and <em>S. pectinata</em> grown in the study area and those collected from marshes were divided into above- and below- ground parts and accumulation of salt ions in plant tissues were determined to understand the species' salt-tolerance mechanism, as well as the accumulation of potentially toxic levels of iron (Fe) and manganese (Mn). Both plant species had similar accumulations (mmol kg^-1 dry wt,) of Na⁺ (474. 3±41 and 468. 3±31. 7, respectively) and Cl^- (314. 9±21. 9 and 310. 5±27. 5, respectively) in the above-ground parts but differed in how they managed Na⁺. <em>J. balticus</em> accumulated more Na⁺ in below-ground parts (659. 3±88. 7) and had limited transport to the above-ground parts, while <em>S. pectinata</em> accumulated and excreted Na⁺ in the above-ground parts and had less accumulation in the below-ground parts (397. 4±25. 1). <em>S. pectinata</em> maintained (313. 1±23. 8 in marsh <em>vs. </em> 292. 4±26. 2 in bog) and <em>J. balticus</em> increased (84. 2±1. 2 in marsh <em>vs. </em> 531. 2±38. 6 in bog) K⁺-selectivity in the shoots, a key requirement for survival in saline conditions. Compared with their respective marsh plants, <em>S. pectinata</em> had more salinity-tolerance than <em>J. balticus</em> primarily through its maintenance of Ca²⁺ (21. 5±1. 7 in marsh <em>vs. </em> 35. 6±3. 8 in bog) compared to a decrease in <em>J. balticus</em> (144. 7±12. 5 in marsh <em>vs. </em> 41±3. 7 in bog). Furthermore, Fe and Mn uptake in both species decreased but reached critical Fe-deficiency levels (1. 1±0. 1 mmol kg^-1 dry wt,) only in <em>S. pectinata</em> grown in drier areas. <br /><br /> It is concluded that local conditions of waterlogging (especially in lower elevation areas) and high salinity and low pH (notably in the upper elevation areas) were favourable to the survival of <em>S. pectinata</em> in all areas and <em>J. balticus</em> only in upper elevation areas. Sod transplanting may alleviate the acidity problem and depending on sod volume may delay the effects of harsh conditions of the cutover bog. However, long-term survival and growth of both species in drier areas may be constrained by deficiency in calcium in <em>J. balticus</em> and iron in <em>S. pectinata</em>.

Eutrophication, particularly due to nitrogen (N) and phosphorus (P) input, has been massively altered by anthropogenic activities. Thus it is important to understand the impact on salt marsh plants; however studies on salt marsh plants within Galveston Bay, Texas are limited. In this study, the effects of repeated nutrient additions in monospecific plots of Spartina alterniflora, Batis maritima¸ and Salicornia virginica as well as mixed plots of B. maritima and S. virginica were studied over 15 months. Results showed that nutrient loading led to an increase in height, biomass, growth rate and percent nitrogen (N) within all three species studied, but were species specific more than dose dependent. Nitrogen content in leaves had a positive correlation with P content in leaves but a negative correlation with carbon (C) content. Nutrient loading lead to a significant increase in total chlorophyll in the fertilized plots of S. alterniflora and S. virginica one month into the study. Nutrient addition to two succulent species, B. maritima and S. virginica in mixed plots did not reveal a distinct superior competitor within the 15 month study in terms of growth and nutrient use efficiencies; however using the maximum growth rates of the monospecific plots, the Monod model was used to determine which species would dominate at high nutrient loads. Based on height data S. alterniflora would dominate, while B. maritima would dominate according to the Monod model based on biomass.

Cultivation and drainage projects associated with livestock production have substantially disturbed resaca wetlands and wet prairie habitats in southern Texas. As a consequence of the anthropogenic disturbances, the area of these wetlands has been reduced and the ecological integrity of the remaining wetlands has been compromised. The goal of this study was to explore effective strategies for ecological restoration of coastal prairie and resaca ecosystems in south Texas and provide restoration recommendations to the National Park Service at Palo Alto Battlefield National Historic Site (NHS). Field experiments were conducted to evaluate the effectiveness of different approaches for restoring Spartina spartinae on disturbed saline flats. A resaca hydrologic study was initiated to evaluate the groundwater hydrology in disturbed versus undisturbed resaca wetlands and explore potential restoration strategies. Transplanting S. spartinae in the fall season was more successful (80% survivability) than seeding (0% initial establishment), spring transplanting (0% survival), spring and fall mechanical transplanting (0% and 6% survivability, respectively). Soil disturbance significantly affected (p < 0.05) survival of transplanted tillers and basal diameter of both the bare root and container-grown transplants in the fall manual treatments. The initial hydrologic study of the resaca wetlands found that vegetation rooting zone hydrology was likely dependent on surface water rather than groundwater. These findings suggest that strategies that restore surface hydrologic regimes will likely restore the ecosystem structure and function of disturbed resacas. Manually transplanting bare-root stock of S. spartinae in the late fall season without soil disturbance will increase the likelihood of successful saline flat restoration.

Thesis (Ph. D.)--Florida State University, 2005. / Advisor: Dr. Joel Kostka, Florida State University, College of Arts and Sciences, Dept. of Oceanography. Title and description from dissertation home page (viewed June 22, 2005). Document formatted into pages; contains xi, 108 pages. Includes bibliographical references.