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.

The stability and survival of salt marshes is typically linked to the competing influences of sea-level rise, subsidence, and sediment accumulation and erosion. However, consideration must also be made for wind waves that regulate the erosion of salt marsh shorelines and resuspend sediments in bordering tidal flats thus providing material for marsh accretion. This thesis examines the mechanisms in which wind waves affect marsh morphology, the mechanisms of salt marsh boundary erosion, in addition to linking the processes responsible for sediment mobilization between tidal flats and adjacent salt marshes. Sediment concentration within an open-coast marsh creek along the Louisiana chenier plain is shown to be related to the local wave climate and channel velocity. Calculations of sediment fluxes during ebb and flood tides indicates that while large volumes of sediment are mobilized into the marsh when wind waves are present, only a small portion is stored during each tidal cycle. In the coastal lagoon setting of Hog Island Bay, Virginia, marsh shoreline erosion rates were estimated from direct surveys and through analysis of aerial photographs. Erosion rates averaged 1.3 m/yr, similar to the 50-year historical average determined from previous work at the same location. Based on a calibrated numerical model for wind waves, the average erosion rate was linked to the energy of the waves attacking the marsh boundary. Additionally, results suggest that the effect of large waves forming during storms on erosion rates is negligible. Variations in erosion rates were linked to shoreline sinuosity (a proxy used to describe the result of wave concentration through erosive gullies), sediment characteristics, faunal activity, and marsh elevation. The culmination of the work leads to the hypothesis that waves have two opposite effects on salt marshes. On one hand they erode marsh boundaries thus reducing marsh area; on the other hand they mobilize large volumes of sediments in nearby tidal flats which may facilitate marsh accretion thus contrasting sea-level rise. In conclusion, wind waves destabilize marshes along the horizontal direction despite their potential vertical stability.

AN ABSTRACT OF THE THESIS OF Benjamin S. Lewis Jr., for the Master of Science degree in ZOOLOGY, presented on December, 2, 2015 at Southern Illinois University Carbondale. TITLE: DETERMINING FOOD RESOURCES FOR AMERICAN BLACK DUCKS WINTERING AND SPRING STAGING ON THE EASTERN SHORE OF VIRGINIA MAJOR PROFESSOR: Dr. Michael W. Eichholz I evaluated food availability and food preference for American black ducks (Anas rubripes) wintering and spring staging on the Eastern Shore of Virginia during 2006–2007 and 2007–2008. I estimated food availability by taking core and sweep net sample at 78 sites selected by a stratified random sample throughout our study area, representing 4 dominant wetland habitat types. Seed and invertebrate biomass found in each of these samples were converted to measurements of kilograms per hectare. I found that salt marsh and mudflat habitats contained the highest amount of invertebrate biomass, while freshwater habitats contained the highest amount of seed biomass. I estimated food preference by collecting crop samples from 76 foraging black ducks. Animal matter made up 73% of the aggregate percent biomass of all foods eaten by black ducks. Foods found in black duck crops were compared to their availability in the environment and classified as either selected for, avoided or consumed relative to their availability. Although they were not found to be the most abundant foods, amphipods (Gammarus spp), salt marsh snails (Melampus bidentatus) and ribbed mussels (Geukensia demissa) were foods selected for in black duck wintering habitats. These food items are found most predominantly in salt marsh and mudflat habitats. As may be expected these areas are identified as the most important habitats for black ducks wintering on the Eastern Shore of Virginia. Results from this study provide energetic supply data for bioenergetically based habitat conservation for black ducks in Virginia and in the Atlantic Flyway. I found that the density of food items available for wintering black ducks were lower than densities found in in the more northern wintering range of the black duck and considerably lower than estimates from the wintering regions of other species of dabbling ducks. By concurrently measuring food selection and availability I was also able to reliably determine food preference. Removing avoided food items from food availability estimates provides more accurate estimates of preferred food biomass and it is important for bioenergetically based habitat models to use estimates of preferred food biomass in determining habitat objectives. I found that when avoided food items are removed, estimates of available food biomass decrease substantially, (up to 97%) further emphasizing discrepancies in estimates of food availability between coastal black duck wintering areas and estimates from the wintering regions of other species of dabbling ducks.

A detailed geochronological and geochemical study has been undertaken on selected sediment cores from four lowland coastal marsh environments in Argyll, Western Scotland. This region of northern Britain has experienced differential crustal uplift and relative sea-level changes throughout the Holocene in response to glacio-isostatic adjustment. The complex interplay between land movements and relative sea-level continues to influence the morphological development of the Scottish coast. The study of lowland inter-tidal sedimentary environments from this region provides an opportunity to investigate the linkages between current estimated crustal movements, regional relative sea-level rise and the evolution of contemporary coastal saltmarshes derived from the record of historical sedimentation. The four sites are located across a ca. 70 km transect extending from the head of Loch Scridain (western Isle of Mull), across the Firth of Lorne to the head of Loch Etive, (mainland Argyll). Vertical activity distributions of the natural radionuclide 21OPb and anthropogenic isotopes (137Cs and 243Am) have been measured and are used to assess the depositional history of marsh sediment accumulation recorded in the four marsh cores. Down-core activity profiles of radionuclides are only reliable as a means of modelling recent marsh evolution provided no early-diagenetic (redox) reactions have compromised the historical depositional record within the marsh sediments. Solid-phase major and trace element down-core geochemical distributions provide a means of assessing the extent to which post-depositional (redox) reactions may have influenced the reliability of the radiometric dating methods. Marsh sediment geochemistry also serves as a useful proxy for identifying compositional variability over the period of marsh development investigated. Dating of the Argyll saltmarsh cores indicates that over the period corresponding to mature marsh conditions rates of sedimentation vary significantly across the study area. At Loch Scridain an average rate of 1.1 mm yr-1 corresponding to an historical period of ca. 130 years is recorded. Comparison with estimated rates of regional sea-level rise suggest an established asymptotic relationship between marsh accretion and coastal forcing, implying historical crustal stability at this site. At sites within the Firth of Lome (Loch Don and Loch Creran) average rates of 2.5 and 3.3 mm yr-1 are recorded for the ca. 70 year period to 1995 with a figure of 2.2 mm yr-1 recorded in the marsh core from the head of Loch Etive. These values are well in excess of estimated relative sea-level rise during the twentieth century suggesting that these marshes may not yet have reached full equilibrium with sea-level. Microfossil analysis of the Loch Etive core helps to identify a more complex depositional history with an underlying trend of marine transgression for the ca. 110 year period of marsh development recorded in these sediments. Over the most recent period of marsh development (ca. 5 years) a significant increase in the rate of marsh sedimentation at all sites is recorded. This signifies the response of these marshes to a very recent increase in the rate of relative sea-level rise across the region. Comparison with available storm frequency data indicates that the evolution of these marsh environments have not been subject to the influence of significant storm activity over the last in the late Twetieth century. The findings suggest that the more clastic sedimentary composition of the Argyll marshes results in these inter-tidal areas being extremely sensitive to changes in coastal forcing (sea-level rise). The implications of recent relative sea-level rise, current vertical crustal movements and future coastal management are discussed.

Managed realignment is now widely seen as an important part of coastal management strategy, as an environmentally sustainable, cost-effective alternative to traditional, hard defences. However, the trajectory of salt marsh development in managed realignment schemes remains uncertain and it is unclear how sites should be managed to fulfil both coastal defence and biodiversity objectives. In this study, the overarching aim is to find out ways in which we can create salt marshes that are self-sustaining and function as closely to natural ecosystems as possible, by considering the linked biogeomorphological processes in salt marsh ecosystems. Such an approach will improve predictions of habitat development and recommendations for future practice in managed realignment schemes. The first important question is: How do pre-alignment plant species growing within managed realignment sites respond to salt water inundation upon re-exposure to flooding? Understanding the responses of the terrestrial vegetation community to initial seawater flooding may improve predictions of the short-term transition into salt marsh vegetation. To answer this, the effects of seawater inundation on pre-existing vegetation are initially examined in a greenhouse experiment in Chapter 3. It was demonstrated that one common plant species component of many coastal grasslands, Trifolium repens, responds poorly to simulated seawater soil flooding, but the response is population-, i.e. ecotype-, specific; therefore, the species consequently has an adaptive capacity to withstand short periods of soil inundation by seawater. In addition, I look at how and why the vegetation community of a restored site transitions following the reintroduction of tidal water, including the response of the original community of non-salt marsh plant species to salt water inundation and subsequent salt marsh plant community reassembly. After three years of tidal inundation at South Efford managed realignment site (SEM), terrestrial vegetation had decreased in cover and nearly all species recorded on the adjacent natural marsh had colonised. However, the cover of salt marsh species was limited by waterlogging, caused by modifications to the tidal regime by a self-regulating tidal gate. This leads on to the second question: How do new engineering techniques alter the tidal regime and what specific aspects of the new regime drive plant community reassembly and sedimentation patterns? In Chapters 4, 5 and 6, three years of ecological and geomorphological development are investigated in response to a variable inundation regime imposed by regulated tidal exchange at SEM. Inundation of the marsh surface was very regular, but water levels were not deep enough to encourage sufficient morphological development, sedimentation nor hydrochory. In contrast, ecological development was limited by waterlogging. Balancing the tidal regime with the drainage efficiency of managed realignment sites may be the most likely scenario under which restored salt marsh will develop with maximum biodiversity benefits. Otherwise, further management techniques, such as the excavation of tidal channels, may need to be employed to improve site drainage. Consequently, the final question is: How can biodiversity be maximized on realignment sites through the use of different management techniques and site design? Tidal channels on a range of managed and natural sites were shown to improve the drainage efficiency of adjacent soils (particularly channels of greater width and/or higher Strahler order). Plant species diversity was generally higher on channel banks in managed realignment sites. On sites with highly reduced soils, the colonisation and establishment of halophytes could be advanced on the banks of tidal channels. Additionally, topographic heterogeneity introduced by tidal channels created a variety of habitat niches, which allowed a range of salt marsh species to establish in the absence of highly competitive species, such as Elymus repens. Results from this study could contribute to the generation of a number of recommendations for the implementation of managed realignment schemes, particularly regarding the excavation of tidal creek networks.

There is a paucity of published information on fish utilization of salt marshes outside North America. This dissertation represents the first intensive examination of the ichthyofauna associated with salt marshes in southern Africa and examines the species composition, diversity, size structure, distribution and estuarine dependence of fishes that utilize salt marshes in the Kariega Estuary. The research was concentrated on Taylor's salt marsh, with comparative studies being conducted on other salt marshes and habitats within the marine dominated Kariega Estuary. The possible importance of salt marshes as feeding and refuge areas for fishes was examined, as was the role of salt marshes in the food web of the estuary. The fishes frequenting salt marshes in the Kariega Estuary were predominantly the juveniles of marine species, with Mugilidae being the dominant family. The ichthyofauna was distributed primarily in the intertidal creeks with very few specimens captured on the vegetated Spartina maritima and Sarcocomia perennis flats. The different reaches of the intertidal creek were characterised by distinct fish assemblages. The fish assemblages associated with the intertidal salt marsh creeks were significantly different from those found in the eelgrass beds, the other dominant intertidal habitat in the Kariega Estuary. The eelgrass beds were dominated by estuarine fish species and had a higher density and standing stock of fishes when compared to the salt marsh creeks. The diversity of fishes in the two habitats was however similar. The intertidal salt marsh creek ichthyofauna also differed significantly from that found in the main estuary channel. The creek ichthyofauna was dominated by 0+ juveniles while the main channel had many subadult and adult fishes. The channel habitat also had numerous large piscivorous fishes which were absent from the salt marsh creeks. The low number of piscivorous fishes, together with limited fish predation from other sources, may be the reason why salt marshes provide a refuge for juvenile fishes that frequent these habitats. Unlike previous studies on North American, Australian and European salt marshes, the dominant fish species that frequented Taylor's marsh were not recorded feeding extensively on the marsh, and those that did had a limited distribution. The role of fishes in the transfer of energy off the Kariega salt marshes is therefore likely to be minimal. A stable carbon isotope study on the dominant primary producers and consumers within the Kariega Estuary revealed that detritus originating from the high lying salt marsh plants Sarcocornia perennis and Chenolea diffusa was not utilized by fishes in the Kariega Estuary. Preliminary results indicated that the cord grass Spartina maritima may be an important energy source to the fishes in the Kariega Estuary, but further research is needed to confirm this.

A comprehensive field and laboratory study of nitrogen uptake in intertidal seaweeds was undertaken. Methods for measuring nitrogen uptake rates were evaluated. Short initial periods of rapid ammonium uptake were common in nitrogen deficient plants. The presence of ammonium inhibited nitrate uptake, but a certain degree of nitrogen starvation overcame this suppression. Laboratory studies with Porphyra perforata showed that nitrogen starved cultures maintained rapid initial ammonium uptake rates. The nitrate uptake system did not remain activated. Nitrogen starvation also resulted in a general decrease in soluble nitrogen content and a transient increase in nitrate reductase activity. The effectiveness of in vitro and in vivo nitrate reductase assays was investigated. The rate of nitrite production in the in vivo assay varied with incubation time. Therefore, the in vitro assay was used. Nitrate grown cultures of Porphyra perforata maintained high ammonium uptake rates. It was suggested that the rate of nitrate reduction was limiting the supply of nitrogen for further assimilation which may control ammonium uptake. Ammonium arid ammonium plus nitrate grown cultures had very low nitrogen uptake rates and nitrate reductase activities. Field studies with Gracilaria verrucosa confirmed that growth on ammonium inhibited nitrate uptake, nitrate accumulation and nitrate reductase activity. The presence of ammonium did not inhibit nitrate uptake rates in severely starved populations. All populations maintained high ammonium uptake rates suggesting that they were nitrogen limited at this time (August). Ammonium and nitrate uptake were saturable in the high intertidal G. verrucosa population but not in the low intertidal population. An investigation was made into the effect of nitrogen source and periodic exposure to air on growth, development and nitrogen uptake in Fucus distichus germlings. Gamete release, fertilization, germination and germling growth had no requirement for a specific form of nitrogen. Periodic exposure to air increased secondary rhizoid development. Ammonium and nitrate uptake rates of the germlings were much higher than for the mature thalli, but the affinity for nitrate was similar. The germlings showed saturable uptake kinetics but the mature thalli did not. The presence of ammonium inhibited nitrate uptake by the mature plants but not by the germlings. Mild desiccation enhanced nutrient uptake rates in several intertidal seaweeds. This uptake response occurred when growth was limited by that particular nutrient and when the thallus had been exposed to periodic desiccation for several weeks. The degree of enhancement, the percent desiccation producing maximum uptake rates and the tolerance to higher degrees of desiccation were related to intertidal location. This was shown to be an intraspecific as well as an interspecific adaptation. Transplant experiments with G. verrucosa showed that enhanced nutrient uptake rates after desiccation were related to intertidal height and not geographic location and that this response could be induced in approximately five weeks. It was suggested that this enhanced uptake response was an adaptation to nitrogen procurement and C/N homeostasis following periodic exposure when carbon was assimilated but when other nutrients were not available. / Science, Faculty of / Botany, Department of / Graduate

Coastal bays and salt marshes are buffer zones located at the interface between land and ocean, and provide ecologically and commercially important services worldwide. Unfortunately, their location makes them vulnerable and sensitive to sea-level rise (SLR), reduced sediment loads and anthropogenic modifications of the shoreline. Sediment budget and sediment availability are direct metrics for evaluating the resilience of salt marshes and coastal bays to various stressors (e.g. SLR). Salt marshes requires adequate sediment inputs to maintain their elevation with respect to sea level. Understanding sediment trajectories, sediment fluxes and sediment trapping capacities in different geomorphic unit facilitates efficient restorations and coastal management. In this research I used remote sensing, field observations and numerical modelling in the Plum Island Sound in Massachusetts, USA, to explore mechanisms controlling sediment dynamics and their feedbacks with SLR. The analysis of remote-sensed suspended sediment concentrations (SSC) reveals that a 5-year record (2013-2018) is sufficient to capture a representative range of meteorological and tidal conditions required to determine the main drivers of SSC dynamics in hydrodynamically-complex and small-scale coastal bays. The interplay between river and tidal flows dominated SSC dynamics in this estuary, whereas wind-driven resuspension had a more moderate effect. The SSC was higher during spring because of increased river discharge due to snowmelt. Tidal asymmetry also enhanced sediment resuspension during flood tides, possibly favoring deposition on marsh platforms. Together, water level, water-level rate of change, river discharge and wind speed were able to explain > 60% of the variability in the main channel SSC, thereby facilitating future prediction of SSC from these readily available variables. To determine the fate of cohesive sediments and spatial variations of trapping capacity in the system, a high-resolution (20 m) numerical model coupled to a vegetation module was developed. The results highlight the importance of the timing between sediment inputs and tidal phase and show that sediment discharged from tidal rivers deposit within the rivers themselves or in adjacent marshes. Most sediment is deposited in shallow tidal flats and channels and is unable to penetrate farther inside the marshes because of the limited water depths and velocities on the marsh platform. Trapping capacity of sediment in different intertidal subdomains decreases logarithmically with the ratio between advection length and the typical length of channels and tidal flats. Moreover, sediment deposition on the marsh decreases exponentially with distance from the channels and marsh edge. This decay rate is a function of settling velocity and the maximum value of water depth and velocity on the marsh platform. Bed sediment compositions were generated to further explore feedbacks between SLR, sediment dynamics and morphological changes. The results show SLR increases tidal prism and inundation depth, facilitating sediment deposition on the marsh platform. At the same time, SLR enhances ebb-dominated currents and increases sediment resuspension, reducing the sediment-trapping capacity of tidal flats and bays, leading to a negative sediment budget for the entire system. This bimodal distribution of sediment budget trajectories will have a profound impact on the morphology of coastal bays, increasing the difference in elevation between salt marshes and tidal flats and potentially affecting intertidal ecosystems. The results also clearly indicate that landforms lower with respect to the tidal frame are more affected by SLR than salt marshes. Therefore, Salt marshes, shallow bays, tidal flats, and barrier islands are inherently and physically connected systems, and evaluating the effect of SLR on salt marshes should involve all these units.

This dissertation deals with evaluation of lamb growth ability and lamb carcass value of Romney Marsh sheep breed. Monitoring and evaluation of lambs were conducted with 18 lambs on the family organic farm of Ing. Paul Šeliga in Vrbětice in the years 2014 to 2017. In the first charter, there are listed information about the importance and general characteristics of sheep breeding in the Czech republic. Then there are also included a development, trends and perspectives of sheep breeding in the Czech Republic. In the next section, it is described the issue of growth and carcass quality of lambs. The following is a characteristic of a farm in Vrbětice in district Zlin and characteristic of Romney Marsh sheep breed. In scope of this evaluation of lamb growth live weight at birth, in 100 days of age and before slaughter was observed. In term of monitoring there was traced influence of lamb sex on growth ability indicators, more precisely on live lamb weight and lambs´ daily weight gain. Effect of gender had inconclusive impact on most of monitored live weight. With regards to the daily weight gain, there was inconclusive effect of the above mentioned indicators on all daily weight gains. There was evaluated influence of lamb sex on carcass value during the monitoring all slaughter lambs. There has also been evaluated the slaughter yield, fattiness and flesh ratio of individual body parts. Results of check slaughter show that sex factor had inconclusive impact on most carcass value´s monitored indicators. Highly provable sex effect was recorded only on live weight before slaughter. Conclusive impact was recorded on slaughter ready body weight, kidney weight, weight of lamb kindey fat, weight of shoulders, kidney ratio, kidney fat ratio and shoulder ratio. On the other hand sex factor did not have evidential influence on slaughter age, slaughter yield, subjective grading, getting meatiness, fattiness, weight and proportion of skin, back and legs. From the point of view of the quality of the right leg, there was a very evident effect of sex on the proportion of fat from the leg, the apparent influence on the weight of the bones from the leg and the inconclusive influence on the weight of the leg, the weight of fat from the leg, the proportion of the meat from the leg and the proportion of the bones from the leg.

This thesis investigates how the Bear River marsh’s protection became a national interest and a cause for conservation in the Progressive Era. The thesis documents how the marsh declined because of irrigation development culminating with an outbreak of avian botulism in 1910, and traces the long process to protect the marshland. The research focused on examining local water development patterns of the nineteenth and early twentieth centuries, ornithological research in the 1910s, and the national sportsmen’s conservation movement of the 1920s. Upon examination of these events, it becomes clear that a coalition of ornithologists, sportsmen, and policy makers worked together to institute change that affected the marsh. Through showing how groups came together in the past to work for conservation, this research highlights the important role that a coalition of groups can have in reshaping how a landscape is viewed and managed.