A research report submitted in partial fulfilment of the requirements for a Masters Degree in Environmental Sciences, School of Animal, Plant and Environmental Sciences. University of the Witwatersrand. Johannesburg, 2016. / Wetland ecosystems cover approximately 6% of the Earth’s surface area and provide important ecosystems goods and services for the sustenance of human livelihoods. According to the Millennium Ecosystems Assessment, wetlands’ ecosystems goods and services cover the provisioning, regulating, support of biodiversity, and wider community cultural values. However, wetland ecosystems are threatened by human interference in combination with effects of climate change, both of which might compromise the functionality of these socio-ecological systems. The study used a combination of observations, interviews and remote sensing combined with GIS to investigate evidence of change and the possible effects on the Blesbokspruit wetland’s natural integrity, and thus availability of ecosystem goods and services in the wetland. Documented spatial changes in land uses were analysed to determine the extent to which land use and cover changes have affected the natural capital (i.e. ecosystem goods and services) for people. The interaction of local people with the wetland was assessed in order to establish how they use the wetland as a livelihood support system. The study found that people from the surrounding communities both in the upper (Putfontein) and lower catchments (Marievale) are interacting with the wetland in different ways. The provisioning services from the Blesbokspruit wetland to the surrounding communities include water used for both domestic and agricultural activities. Both subsistence and commercial farming are taking place along the wetland (crop farming and livestock rearing). The wetland is therefore providing a safety net to disadvantaged households who are able to supplement their food. The wetland is also able to regulate climate change (carbon sequestration and flood attenuation) and water quality due to the presence of vegetation. The wetland also supports high biodiversity (flora and fauna) such as within the Marievale Bird sanctuary. Recreational services of the wetland come from the scenic views noted at both Marievale (picnic spots) and Putfontein (evidenced by children playing and swimming). The integrity of the wetland is primarily threatened by population increase and urbanisation. Remote sensing analyses of land use/land cover patterns between 1998 and 2015 indicate that major changes of the wetland have been due to human encroachment. Subsistence agriculture in the wetland has increased, which fuels damage to the wetland. Direct observation and interviews with female farmers showed that they compete for plot size which is proportional to the respect one farmer earns in the community. Water quality of the wetland seemed to be compromised by industrial activities and use of fertilisers by farmers. Unlike the pristine upper part of the wetland at Putfontein, eutrophication downstream was evidenced by polluted water, algal blooms and change of water colour at Marievale – all suggesting loss of natural benefits such as high quality water. Despite the observed threats, it is concluded that the Blesbokspruit wetland ecosystem goods and services play a significant role in supporting the well-being and livelihoods of surrounding poor communities. It is suggested that activities threatening the wetland’s integrity may be managed effectively through community-based approaches for natural resource management. There is a need for all stakeholders to be equipped with proper conservation knowledge for them to appreciate the indirect (e.g. climate regulation and water quality control) as well as direct (agricultural and water provisioning) benefits of Blesbokspruit wetland. A better understanding of this socio-ecological system would benefit from comprehensive research on hydrological dynamics associated with agricultural practices within the catchment, and the development of an integrated model of natural resources management with a strong social component. / LG2017

In tropical wetlands, breeding wading birds rely on concentrations of aquatic fauna during the dry season to meet increased energetic demands. Wetland microtopography increases aquatic fauna concentration levels. Crocodilians modify the landscape creating deep-water refugia but their role as a mechanism for aquatic fauna concentration is unknown. I sampled alligator (Alligator mississippiensis) abundance and slough microtopography to examine correlation between the two measures. Despite increased microtopography in high alligator use sloughs, the differences were not significant. Using an in situ experimental approach, I quantified the magnitude, timing, and spatial extent of aquatic fauna concentrations within simulated alligator depressions and the surrounding marsh. Aquatic fauna density and biomass were greater within simulated depressions, thus enhancing wading bird foraging habitat. Further understanding the mechanisms creating microtopography, thus enhancing wading bird habitat, is critical to facilitate restoration and prevent declines of wading bird populations in seasonally pulsed wetlands worldwide. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Thesis (M.S.)--University of Delaware, 2007. / Principal faculty advisor: Jacob L. Bowman, Dept. of Entomology & Wildlife Ecology. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xx, 417 p. : ill. (some col.), maps (some col.). Includes abstract. Includes bibliographical references.

Wetlands have long been recognised as enhancing the quality of inflowing waters, particularly regarding the plant macronutrients nitrogen and phosphorus. Any research into non-limiting solutes has largely been of a 'black box' nature, with no insights into mechanism of retention presented. Research in the Okavango Delta, Botswana and preliminary work in the uMkhuze Wetland System, South Africa has identified retention of large amounts of non-limiting solutes within these wetland systems. Chemical sedimentation in the Okavango accounts for 360 000 tonnes per year, while a rough mass balance in the uMkhuze Wetland System suggested retention on a scale of 16 000 tonnes per year. The Yengweni and Totweni Drainage Lines are north-south oriented systems that, together with the uMkhuze River floodplain, were selected to investigate chemical retention in the uMkhuze Wetland System. These drainage lines were once tributaries of the uMkhuze River that have been dammed at their southern ends by alluvial deposition on the uMkhuze River floodplain to form tributary valley lakes. Considering seasonal variations in groundwater levels in combination with conductivity, sites of solute concentration were revealed in the groundwater. The use of chloride as a concentration tracer has indicated that solutes are progressively depleted in the groundwater under the influence of a concentration mechanism, with silicate minerals and calcite attaining saturation. Groundwater chemistry and hydrological factors have highlighted the southern Yengweni and floodplain regions as active sites of solute concentration. In these areas, groundwater elevations are variable, which is mirrored by variation in groundwater chemistry. Although elevated solute concentrations do occur elsewhere, the seasonal variation is less marked. The search for solute sinks in the uMkhuze Wetland System also considered the sediment of the wetland system as a possible sink. Elevated solute concentrations in the groundwater could be linked to the accumulation of minerals in the soil, suggesting precipitation of minerals by saturation under a concentration process. In tho southern Yengweni and floodplain regions, concentrated groundwater bodies were linked to high concentrations of minerals in the soil, including neoformed montmorillonite, and calcite deposits. Other sites of chemical concentration in the groundwater in the northern Yengweni and Totweni Drainage Lines have produced little modification of the reworked marine sands on which the wetland is founded. Processes in the southern Yengweni and floodplain regions are clearly more efficient in removing solutes from the wetland surface water and immobilising them in the soil of the drainage line than is happening in the Totweni and northern Yengweni regions. Transpiration by vegetation seems to be the major factor driving chemical sedimentation in this subtropical system, and as such vegetation in this wetland system is not the passive factor it is often assumed to be. The vegetation of the wetland is itself initiating and perpetuating the retention of chemicals in the system. Hierarchical patch dynamics in combination with the theory of thresholds, derived from geomorphology, is useful for placing chemical sedimentation in wetlands into a spatiotemporal framework that increases understanding of the process, and allows identification of sites where chemical sedimentation is likely to occur in wetlands. There are a number of thresholds that define chemical sedimentation driven by evapotranspiration in the uMkhuze Wetland System, which may be considered at increasing spatiotemporal scales from the microscale of seconds within a limited section of the groundwater, to the macroscale thousands of years at the landscape scale of the wetland system. With increasing scale, the effects of the transformations at each hierarchical level have corresponding increasing influence on the structure and function of the wetland system. The initial threshold is surpassed once concentration products of evapotranspiration are retained to some degree within the wetland system, due to increased residence times of groundwater on modification of the hydrological regime from discharge to recharge. Increased residence times allow the products of seasonal concentration to persist beyond the timescale of seasons. The second threshold is the saturation and precipitation of mineral phases that accumulate within the soil profile. With sufficient accumulation of chemical sediments, the physical properties of the sediment are modified, which reduces the velocity of water flow in the soil (Threshold 3). This has implications for hydrological flows between the surface water and groundwater systems. Threshold 4 is attained once the sediment is modified to such a degree that the chemical sediments act as an aquitard, such that surface water and groundwater may be effectively separated. Extrinsic factors influencing the process of chemical sedimentation, such as the atmospheric water demand, chemical composition and volume of inflowing waters, as well as the nature and density of vegetation, may indicate the potential of a system to sequester chemical sediments but cannot predict their occurrence completely, except maybe at the extremes of semi-arid and arid systems. It is the local and intrinsic factors of hydrological flows, their chemical composition and nature of clastic sediments that will govern residence times of water in the system, and therefore the location, nature and extent of chemical sedimentation. Furthermore, chemical sedimentation driven by evapotranspiration is not limited by sediment type as are adsorption and complexation reactions, which are dependent on the availability of active sites, nor by chemical composition of inflowing waters as this factor simply dictates the suite of minerals produced. Therefore, chemical sedimentation in wetlands is expected in a wide range of settings from temperate to arid, with varied substrates and hydrological regimes. The large-scale removal and retention of solutes within wetland soil has system-wide implications for wetland structure and functioning. The ramifications of chemical evolution of the groundwater and soil extend from influencing the distribution of plants and animals, to geomorphological implications of accumulating chemical sediments, as well as off-site effects including water quality enhancement of water available to downstream systems and users. An understanding of the process of chemical sedimentation in wetlands may inform good management to protect this vital function of wetlands, particularly with increasing development and industrialisation pressures in many areas. Extensive chemical sedimentation has been discovered in both the Okavango Delta, Botswana by Ellery, McCarthy and colleagues and through this study in the uMkhuze Wetland System, with the proposed driving force being transpiration. Vegetation induced chemical sedimentation is a hitherto unknown, although seemingly important component, of chemical processing in tropical and subtropical wetlands, and under certain conditions, even in temperate wetlands. This insight into chemical transformations in wetland systems adds a further dimension to the accepted model of chemical cycling. / Thesis (Ph.D.)-University of KwaZulu-Natal, 2008.

No description available.

Thesis (Ph. D.)--Dept. of Geosciences and School of Computing and Engineering. University of Missouri--Kansas City, 2006. / "A dissertation in geoscience and software architecture." Advisor: Wei Ji. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Nov. 13, 2007. Includes bibliographical references (leaves 248-261). Online version of the print edition.

Thesis (Ph.D.) --Murdoch University, 2004. / Thesis submitted to the Division of Science and Engineering. Includes bibliographical references (leaves R-1 - R-24). Also available via the World Wide Web at.

Thesis (Ph.D.) - James Cook University, 2008. / Typescript (photocopy) Bibliography: leaves 198-218.

Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 114-116). Also available in electronic format on the Internet.